Dimension pipe networks Optimise pumping Optimise flow pipe temperatures Minimise heat losses. NetSim includes:

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1 Introduction What is NetSim? NetSim is an interactive tool for calculations of pipe networks for district heating, district cooling and steam. With NetSim, you can: NetSim includes: Dimension pipe networks Optimise pumping Optimise flow pipe temperatures Minimise heat losses A powerful graphical interface which is used to define the pipe networks and calculation criteria. An effective calculation drawing module. A powerful graphic presentation of calculation results in the form of charts, diagrams and tables. Powerful export tools which directly export data to Excel format, DXF/DWG and a number of raster formats. Powerful import tools for importing data from a number of network information systems on the market. The manual This manual covers NetSim release /02/2017: Updated manual Note that changes are made to software without updating the manual. Doc-To-Help Standard Template Introduction 1

2 Basic principles Basic elements The calculation model for a network consists of the basic elements nodes and pipes. All numerical information is linked to these elements. A node is represented by a circle on the chart, while a pipe (comprising a supply pipe and a return pipe) is represented by a line between two nodes. Calculation model for a district heating network. Nodes and pipes. Nodes The following can be simulated in nodes: Loads produced from nominal or measured values at consumer level. Alternatively, consumption can be given as zero. Thermostatic bypass Bypass with fixed diameter or Kv value Production plants Shunt valves Accumulators

3 In addition, the node is a coupling between one or more pipes (max. 8). The model describes the nodes by providing names, coordinates, an elevation, a cooling or return temperature and information on bypasses. Model of a node and its potential controls. Consumers can be divided into categories. This makes it possible to execute a simulation with varying load factors depending on consumer category. The consumer categories are defined by the user. Up to 99 different categories can be defined. Categories are characterised by category type numbers (1 99) and corresponding names. A factor by which the customer's recorded power requirements is to be multiplied is indicated for every category as a function of the outdoor temperature. In a similar way, type curves are defined for the customer's cooling as a function of the outdoor temperature and the return temperature as a function of the outdoor temperature. Every consumer can belong to only one category, but a node can stand in relation to many consumers with different categories. A single node, such as a branch, is the same thing as a node without a load. A production plant is a node where supplements have been made to the node information for supply temperature, possible production quantity and absolute pressure. The accumulators work in two ways: Doc-To-Help Standard Template Basic principles 3

4 The accumulator can be given an unknown power consumption. This may be useful when the calculations are to be used as dimensioning tools for accumulators. The accumulator can be given a given power consumption with a set of power factors. This allows the behaviour of an accumulator to be checked. The accumulators in question are expected to behave as follows: Power is stored at a constant return temperature which is the same as the accumulator's minimum temperature, Tmin, depending on the stratification of the liquid in the accumulator. When power is extracted, this takes place at a constant temperature which is the same as the accumulator's maximum temperature, Tmax, depending on the stratification of the liquid in the accumulator. Pipes The pipes in the model are couplings between the nodes. Pumps, valves and heat exchangers can be connected to pipes. A pipe is characterised by the name of the connecting nodes, length, internal diameter, roughness, heat transfer coefficient, individual loss, two pressure losses at both ends and the flow in the pipe. The model assumes that the network is geometrically symmetrical from inlet to return. Various physical units such as diameter, heat transfer coefficient, individual loss, length and roughness can be specified. Pumps and valves can be connected to either the upstream pipe end or the downstream pipe end; see the figure. Pipe model defined with lengths and pressures. A pump can either be described with a pressure increase, ΔP, or by means of a pump characteristic, where the pressure is calculated as a function of the flow in

5 the pipe. The pump velocity can also be calculated when the pressure and flow are described by means of the characteristics. The pump characteristics are indicated by up to 12 points which are described with pressure, flow and power consumption at a specific velocity for the pump. Calculation of ΔP is interpolated from the characteristics. Specification of pump characteristics A valve is indicated either by an applied pressure loss or by valve characteristics where the pressure loss is calculated as a function of the flow in the pipe at a given valve setting. The characteristics have to be entered as a set of operating points determined by the values of the valve setting and valve coefficient. Up to 10 points can be entered for determination of the characteristics. Specification of valve characteristics A heat exchanger can be connected to a pipe end. Quite simply, the heat exchanger describes an increased or a decreased temperature for the water in the pipe. The power supplied or removed via the heat exchanger is a linear function of the temperature upstream in the pipe. Doc-To-Help Standard Template Basic principles 5

6 Boundary conditions Like all other calculation models, NetSim needs specific input data. These requirements are all quite simple and natural. A calculation model has to meet a number of hydraulic and thermal requirements before a problem is defined and can be resolved. Fundamentally, the following conditions have to be met: Flow or power consumption must be specified at all nodes except for one. An absolute pressure must be specified. A differential pressure must be specified. The cooling or return temperature must be specified at all nodes with consumption. The temperature in the supply pipe must be specified at production plants (producers). Pressure drop in a single pipe The simplest possible system - one pipe and two nodes - is shown in the figure above. This system meets the requirements for both pressure and differential pressure and the flow being known at all nodes, except for one. The nodes in which the flow and pressure are stated is of no significance. In some cases, more than one pressure check must be specified; for example, if a pressure increase or a pressure drop in a valve is to be calculated. In these cases, more than one pressure must be known, one for every ΔP to be calculated. The unknown pressure change must be positioned between the known absolute pressures in relation to the direction of flow of the liquid.

7 Model of a pipe network provided with a pump controlled to find a set pressure at the end point Pressure gradients for model defined in figure above The two examples below show exceptions which may occur in respect of what was described above: If the unknown pressure P is set in a pipe which is part of a system containing ring connections. In a node, the known flow can be replaced by another known pressure. The flow is then calculated on the basis of the calculated pressure profiles. Dimensioning NetSim can be used for dimensioning pipes. The user can specify which of three criteria are to be used: 1. Maximum permitted velocity in the pipe. 2. Maximum permitted gradient in the pipe. 3. Dimension-dependent criterion where a velocity criterion is used if the diameter is less than a diameter specified by the user, and a pressure Doc-To-Help Standard Template Basic principles 7

8 gradient criterion is used if the diameter is less than the diameter specified by the user. It is possible to specify the criterion as a global criterion, i.e. it is used for all pipes to be dimensioned. It is also possible to assign individual criteria to the pipes. NetSim uses dimensions from a pipe directory, which ensures that the criterion is not breached. There is no limit on how many pipes can be dimensioned, but the number of pipe types to choose from is limited to 20 different types/dimensions. A name, internal diameter, roughness and heat loss factor are specified for every pipe type. A pipe's diameter is dimensioned if the pipe's diameter is not defined from the outset. NetSim assigns a diameter to the pipe, which is chosen from the pipe types in the active directory. If the roughness of the pipe is not defined, the pipe's roughness is also selected. The user must be aware that it is possible to define problems relating to pipe dimensioning which have no hydraulic solution. One example is a looped system. If the pipe to be dimensioned is part of a loop and two different pressure gradients are specified, a hydraulic solution does not necessarily exist. In cases such as this, NetSim will not arrive at a solution and the maximum number of iterations will be exceeded. Dynamic calculations An insoluble dimensioning problem In the example above, the user has to specify at least one of the dimensions. Note that there may be combinations of dimensioning criteria, pipe lengths and reference pressure values in a model which has a hydraulic solution despite everything. In the example above, a solution can be found if the two pressure gradients and the two pipes are equal in size. The purpose of the dynamic module is to simulate changes in input temperatures and loads as a function of time. By using the dynamic module, the user can study how temperature fronts prepare themselves in the pipe network as a function of the time. Water hammer cannot be simulated using the dynamic calculations due to the time scale for water hammer, normally less than one tenth of a second. The results are presented in tables, graphs and plots. Simulation is carried out as a series of stationary calculations separated by a user-identified time interval where the results of the preceding time step adjusted by time-dependent factors constitute input data to the next time step calculation.

9 To change the load in different parts of the network with time, the nodes can be linked to one of ten potential categories. For every category, the load can be scaled using a time-dependent factor. The supply temperature, return temperatur and production price for the production plants can be changed during the specified time in a similar way. Steam module The steam module is used like the regular liquid phase module, apart from the fact that the system requires steam in the supply pipe and liquid phase in the return pipe. Latent heat is taken into account when a phase shift takes place in the heat exchangers. The compressibility of the steam is integrated into the pressure drop calculations. District cooling When the calculation relates to a district cooling network, the physical properties of the water are adapted to the temperatures used in district cooling networks. Input and power data is adapted to take into account the fact that energy is removed at the production plants. When calculating a district cooling network, the consumers' return temperature must be stated as a parameter, along with power/flow. You should be aware that rules of thumb from district heating distribution are not directly applicable. There are small temperature differences, and large water flows in these networks in relation to power! Doc-To-Help Standard Template Basic principles 9

10 What should I do? Introduction Start NetSim This section of the manual describes how to use NetSim by way of an example whereby a completely new model will be created. The model will gradually be supplemented to add functions in NetSim. When you need more detailed descriptions of functions, menus and forms in NetSim, look up these descriptions in the relevant sections of the manual. Start NetSim from the start menu. Enter your username, password and the name of the database. If you check the Remember username/password box, your login details will be saved for the next time you start NetSim.

11 When you have connected to the database, you can select which model to work with; 1. Select a model from the drop down menu 2. Click the green arrow to load that model and when you have done this, content from the NetSim database is loaded. At the same time, the grid in the model is drawn in the graphic window and the model data form is completed with data for the model. If this is the first time you have used the system, there will be no model available and so you will have to create one. See below. Pipe types If your NetSim has been converted from an earlier version of NetSim, type data will already be installed. The same is true if type data was installed when you installed NetSim. Otherwise you now have to create one or more pipe types to be linked to pipes in the model before we create the first model in NetSim. Create a new pipe type Go to the tab Pipe type and right-click in the grid. From the menu, select Create new.. The detail form for pipe types now opens. Give your type a name (max. 25 chars recommended), enter the external diameter for the media pipe (mm), the internal diameter for the media pipe (mm), pipe roughness (mm) and U value (W/m C). Note that the U value (thermal coefficient) relates to the individual media pipe. Indicate that the type is approved for dimensioning. Create the other pipe types that you need. Also create a type and name it? (without ) and an internal diameter of 0.00 mm, with pipe roughness 0.05 and thermal conductivity We set this type for pipes that are to be dimensioned. (At the end of the manual, you will find a suggestion for pipe types, steel and copper pipes, that you can use as a specimen.) Doc-To-Help Standard Template What should I do? 11

12 Create a new model Select in the menu File Model management Create new The calculation form now opens. It contains a number of preset values which you do not need to change at this stage. It is possible that you should now select the type of network, cooling or steam, if it is not a district heating network. Give your model a name in the model name field, then save your model. Close the calculation form, and in the model dropdown menu select your new model. Creating a grid You now have to create the first pipe in the model. For them to end up in the right place in geographical terms, we will load a map as our background in the graphic window. Background maps may be in DXF or DWG format. Background maps can be straightforward basic maps, but they can also be pipe maps. The important thing is to ensure that the scaling is correct. In NetSim, one drawing unit is interpreted as meaning 1 m. Retrieve your background map by going to the Tools tab and selecting Load in the menu backgrounds menu. When your map has been loaded, select Zoom boundaries in the right-click menu.find the right place on the map using Zoom window from the right-click menu. You can also scroll using the roller on the mouse to zoom in, or use the zoom tools under the Home ribbon. It may be wise to purge the background map to remove unnecessary information before loading it into NetSim.

13 Create or delete objects Under the Home ribbon there is a menu called Graphics, in this Menu we find tools for creating or deleting objects in the map window. 1. Create Pipe 2. Create Node 3. Delete Object 4. Cut Pipe left-click left-click left-click Create the first pipe In the right-click menu, or under the Home ribbon, select Draw pipe and leftclick at the point where you want the pipe to start. Move the cursor to where you want the pipe to go, then left-click at every location where you want the pipe to change direction. When you arrive at the first branch or dimension change, leftclick to view the coordinates for this point, then right-click to terminate the draw command and define data for the pipe. A number of dialog boxes now open which lead you through creation of the pipe. The dialog box Spec. start node is opened, and here you can change the suggested node name if you like (max. 8 characters in the present version). Select Create node. The dialog box now displays data for the node. Note that the z coordinate is 0. Change this to the relevant value, then save. The dialog box containing values for the end node is then opened. Note the z coordinate, it is copied from the nearest node in the model. Save the node and close it. Finally, the dialog box for the pipe is opened (a pipe in NetSim always includes both a supply pipe and a return pipe). The nodes between which the pipe will be connected are shown at the top. If you like, you can change the suggested pipe name (max. 8 characters in the present version). Then select the type of pipe in the list box. Then select Create pipe. The dialog box now displays data for the pipe. If necessary, you can change the pipe length and pipe type here for the supply and return pipe. Select Save to finish creation. The pipe is ready, and you can now view your pipe in pipe form and the nodes in node form. If you select Cancel instead of Save... in the dialog boxes, the object handled by the dialog box a start node, end node or pipe will not be created and the command will be terminated. Doc-To-Help Standard Template What should I do? 13

14 Create the second and subsequent pipes When the next pipe is to be created and the pipe is to be connected to the previous pipe, move the cursor towards the circle indicating the node. Start by right-clicking, then select Draw pipe. Move the cursor towards the node. When you have contact with the node, this is shown by an indication. IMPORTANT! You have to left-click to start the draw command while the indication is on. If the indication is not visible when you start drawing, a new node is created when you start drawing and you will not get the designated link between the pipes as intended. You can see this because a new start node is created, not an end node. If so, cancel this and start again! Of course, you can both start and end the pipe in an existing node. If you leftclick on a node which indicates that it has been hit and then right-click straight away, the pipe will be connected to the selected node. Important: In NetSim versions before , you could create a pipe with a length of 0 m by right-clicking immediately after starting drawing at the first pipe. This pipe cannot be calculated! If you have updated from an earlier version, sort the pipe table according to length in order to locate the pipes with 0 length. Pay attention to the name of the end node (copy it to the clipboard by pressing Ctrl+C). From the right-click menu, select Delete object. Open the node table, select the node column, then from the right-click menu select Search, paste in the node name by pressing Ctrl+V in the search box and the node table now displayed the node sought. In the right-click menu, select Delete object and the unwanted node will disappear. We will select this method instead of selecting the node in the map because this will have exactly the same coordinates as another node and so it is difficult to select the correct node for deletion! Cut an existing pipe The command Cut pipe in the right-click menu, or under the Home ribbon, divides an existing pipe into two parts, where you point at the pipe and place a node in the division. The command then continues as a draw command so that you have the opportunity to directly draw the pipe which connects at the division. However, you have the option of terminating the pipe both with a new node and to an existing node or an existing pipe by also dividing that pipe! Make sure that you have zoomed in sufficiently when you have to select a pipe or node so that the snap function does not select anything in the background map. Delete an object You are sure to create pipes and nodes that you need to delete! In map view, right-click and select Delete object, or select delete from the Home ribbon. Then point at the object to be deleted. If you point at a pipe, the pipe will disappear. If you point at a node, the node will disappear in addition to the pipes starting from the node. Calculable network When you have created all pipes in the network and these pipes have been connected to one another to form a continuous network, it is time to check whether the network hydraulics are all connected.

15 Create production plant Select the node in the network which will include the production plant. Open the table Production plant, right-click in the empty column at the far left, then select Create new. The detail form for production plants now opens. Give your plant a name. Enter the supply temperature. Leave the fields current flow and current power empty. Place the plant in a node by selecting a node in the list, or select the globe if you have selected the node in the map. Select Pressurisation return or supply and then enter the static pressure. The production plant has been defined. Select Save to save it, then close the form. Create consumption in the model Select a node in the network (not the production plant). The node table now shows the node which you selected. Enter the power [kw] and return temperature [ C]. Enter calculation conditions Select in the menu File Calculation. The calculation form opens. To be able to perform a calculation, a number of things must be defined in the calculation form. There must be a differential pressure in the hydraulic model, i.e. a pressure difference between the supply pipe and the return pipe. In reality, this differential pressure is often a long way out into the network. If you have to perform a calculation for the first time, you can set the differential pressure in the same node as the production plant. Right-click to the left of Differential pressure and Doc-To-Help Standard Template What should I do? 15

16 select Create new. Enter the differential pressure and the node where the production plant is located. When a differential pressure has been entered, save it. The next thing to configure is where the calculations are to be saved. This is done by clicking on Enter search path in the form. Save it with a relevant name so that you can find your calculation later. Notice that the standard file path (after the first calculation) is the last filepath used, thise means that if you don t change the filepath between calculations the last result will be overwritte. If you want to save the results change the filepath! The calculation has now been configured and basic data has been entered in the calculation form. Select Save and Close to finish. Execute calculation Identify holes in model You can now perform a calculation, but before you do this you can see whether the network is holding together hydraulically and whether there are any double nodes, i.e. two or more nodes which are very close to one another but not linked together with a pipeline. This is done by selecting Identify holes in model which can be found under Tools. The results are presented in a graph in NetSim, and you can quickly see where the error is and correct it.

17 Make sure that both options are checked in the box. Identify hydraulic networks checks whether the pipe network is holding together hydraulically and Node on node checks whether there are nodes on one another or very close to one another without being connected to pipelines. This distance can be set. Press Esc to delete the pipe highlights if the network is OK. Calculate To perform a calculation, select File Calculation in the menu. Then press the Calculate button. This generates the input data file for the calculation module. One box is checked, Display manual settings. Leave this box checked when the model's calculation properties is unknown. You can now choose a type of calculation; either a static calculation, with the data you entered, or a dynamic calculation. A dynamic calculation is a number of static calculations over a set time and is also known as a time series calculation. This is described later on in the manual. Doc-To-Help Standard Template What should I do? 17

18 Select Start. The calculation begins. The calculation stops when it is complete, and either it will have continued to the end or there will be an error somewhere. The Calculation status box tells you this. If it is complete, it stops as the stop criterion is smaller than the value you set in the calculation window. The stop criterion is by default. In this case, the result is less than The number of calculations or iterations can also be seen, in this case 25. If the calculation is not complete, the Calculation status box tells you this, and if you click on the Chk button you can open the error message in a text editor in order to analyse the error. The results of the calculation can be viewed by clicking on the Out button. See later on in the section on Results analysis. Troubleshoot model If the calculation is not complete, the Calculation status box indicates this, and if you click on the Chk button you can open the error message in a text editor in order to analyse the error. For some types of error, row numbers in the netsim file where the calculation module has encountered problems are written to the Chk file. Open the calculation file and review the rows excluded. There is a list of error messages at the end of the manual. You can see here what an error message means. Fault-free model The model now functions hydraulically, it hangs together. In the next element we will specify the actual consumptions and production plants that must be in the network. Sectioning option If you shut down both the supply pipe and the return pipe, you will force the water to take a different route if there is a loop feed option. Otherwise a larger or

19 a smaller area will be shut down. How large this area is, along with which parts are affected by the shutdown can be displayed graphically in the function Sectioning option. Under the Pipe tab, select the pipe that you want to shut down. It is easiest to click on the pipe in the map, and thus display the pipe in the table. In the grid, go to the column Closeoff status. Close both the supply pipe and the return pipe by selecting Fully closed. Do not forget to save by right-clicking and selecting Save. When the pipe is closed, an area is closed off. Select Tools Notification. The box below is displayed. The pressureless parts of in the network are displayed in black. Doc-To-Help Standard Template What should I do? 19

20 You select the part which is pressureless, and the customers affected are exported to a text file which can be linked to a Word document, for example. Print. Post. Done! The customer has now been advised of a planned shutdown! Split model If you want to divide a model, e.g. to delete a town district, this is easy to do using the function Divide model. Start by copying the model that you want to divide. Then shut pipes so that two hydraulic networks are created. Both the supply pipe and the return pipe have to be shut down. The pipe is shut down. Select Tools Split model. A confirmation request is displayed.

21 The green network is selected and so must be retained. Only the network below is left. Doc-To-Help Standard Template What should I do? 21

22 The model now functions hydraulically, it hangs together. In the next element, we will specify the parameters that have to be met to allow a calculation to be performed: A production plant with pressurisation, a differential pressure, a consumption or flow and the return temperature in a node. Supplement the model with consumption/customers Create a customer via a customer data form. A calculation can take place if there is at least one consumption in a model. This consumption is in a node. Consumption can either be linked to a customer or be entered directly for the node. If consumption is entered directly for the node, power or flow must be specified. Import customer from external file The format for the import of customer data is described in the manual section entitled Consumption data. One very easy way in which you can create a template for import is to create a sample customer in NetSim and then export this customer to a text file! Open a model in NetSim. There must be at least one node in the model! Go to the Customer tab. In the right-click menu, select Create new Now enter values in the fields which you can easily recognised in the exported customer data file. In the menu, select File -> Customer data -> Export of customer data. Open the exported file in Notes, select the row and paste the row into Excel. ANLID KUNDID KUNDNAMN FASTIGHETSBETECKNING ADRESS N766 N76 6 N The file looks like the one above (wrapped). If you want to include notification information, this is added between the last four field separators.

23 Column-separate the file in Excel, the character is the separator. Now create new rows in the Excel file for your customers. Use your sample customer as a template. When you have finished, delete the sample customer. Then set national settings use the character as a column separator, or replace your separator with via a search and replace command in notepad. Note that numerical values must be integers with no decimal places. Save the spreadsheet in CSV format. Import the file by selecting the menu File-> Consumers -> Import all Your consumers are loaded! Doc-To-Help Standard Template What should I do? 23

24 Several production plants Production plants When a plant has been defined in a model, one or more other plants can be added in the same way using the command Create new. Power or flow must be specified for all production plants except for one. The supply temperature must be specified for all plants, and only one plant's pressurization must be activated. If the network consists of several separated networks, the above is applicable for each network. Position a heat exchanger A heat exchanger placed in a pipe can be used to supply energy to or remove energy from a pipe. For a more detailed description of this, see section Heat exchanger form. Pressure regulations Define a pressure increase station A pressure increase station is a pump station where a pressure change takes place. This pressure change can be at the supply pipe or the return pipe or at both pipes. For a more detailed description of this, see Pump form. Define a pressure reduction A pressure reduction is a change in pressure in a pipe, a valve in the pipe affecting the pressure. This valve can be placed in either the supply pipe or the return pipe. For a more detailed description of this, see Valve form elsewhere in the manual.

25 Analyse calculation results Summary calculation results Calculation results are displayed in NetSim Analyse. The tab Overview shows a summary from the simulation. The file simulation-name.out holds all values applicable to the calculation an can be opened in any text editor. It is possible to search where these values are using a search function, either directly in the map or in the node or pipe table. The power balance for the production plants is displayed a little further up in the tab Out. Pipes dimensioned by NetSim are displayed under the header Pipe Dimensioned. Map plots It is possible to print the map from Analyse. The printout is defined in File Print Graphs Graphs are described under Diagrams in the section on Analyse. Table data The node and pipe tables show calculation results in tabular form. Take care to make sure that the values are reasonable. Doc-To-Help Standard Template What should I do? 25

26 NetSim system summary Vitec Release Manager Vitec Release Manager is an application that maintains your NetSim installation. The application manages most of the installation and checks that you are using the latest version of NetSim. When later versions of Vitec are published, it automatically downloads the new version and installs it. Modelling Release Manager indicates the versions of installed products, and if a later version has been assigned to the Vitec installation this version is displayed and the product is flagged up with a different colour in Release Manager. In this case, click on the info button to fix the product. Here, you can download any updated using the Download button. That is to say, there are no automatic updates; you have to enable the download and update yourself. You have to be authorised to download updated via the Internet and to change the content of your NetSim installation for this to work! NetSim and Analyse are copy-deploy installations. This means that everything you need to make the programs work, except for the Oracle client and.net, is collected in the program folders for the relevant programs. If downloading is not permitted, the update can be copied to your computer from a medium created from a computer where downloading is permitted. NetSim version 3 is the graphic tool for managing your calculation models in the NetSim model database. Below is a description of the menus and forms which you will find in NetSim 3. Some forms with a central function, e.g. the calculation form, are described in detail, while other forms of more peripheral significance are described in more general terms. In general: forms and windows include a right-click menu with functions. double-clicking in the leftmost column of the grid forms opens detailed forms for the record if there are any detailed forms for the grid form. forms and toolboxes can be positioned in any location by the user. changing data can be undone copying (Ctrl+C/Ctrl+V) between cells in the forms is permitted if the value pasted in is copied from the same column. if multiple users are logged on to the same database simultaneously, the last value saved is valid.

27 Calculation. The calculation module in NetSim is started directly from the menu under Modules, automatically by NetSim when data is exported from the form Calculation to the calculation module, or directly from the explorer by enabling a calculation file from NetSim. You can reach associated calculation results directly from the calculation module. Doc-To-Help Standard Template What should I do? 27

28 Results anaysis The calculation results are analysed in NetSim Analyse. Analyse is an independent product which displays the calculation results as maps, diagrams and tables divided into levels. Analyse is started directly from the Home Ribbon. As in NetSim, you can use external DWG/DXF files as backgrounds and plot and save in DWG/DXF and raster format.

29 Modelling User interface The NetSim program window includes the above blocks in the basic configuration. A graphic window in which the network map is displayed, a menu, a list of toolboxes, a form with tabs which contain model data, a form with tabs which contain system data, and right-click menus. You have plenty of freedom to move the blocks, create separate blocks, dock and lock and hide blocks, change the order of columns, etc. as you wish. Strictly speaking, only the menu, map window and status list are fixed. You can always return the appearance to its original mode by selecting a command under Help in the File menu. Take the opportunity to adapt the appearance so that it suits you best! It is a good idea to create your own toolbox in which you have your own shortcuts to the most common commands; see the paragraph describing Graphic window for more details. General information on forms The primary way in which you can access the data in the NetSim database is via a grid form in which the data for an object is displayed in columns. Pipes are displayed by way of example here. The grid shows all pipes in the model. When you select a pipe in the map screen, this pipe is highlighted in the grid, and the highlighted pipe in the grid is also highlighted in the map screen. Doc-To-Help Standard Template Modelling 29

30 The fields which provide primary information on the pipe are displayed in the grids. Start and end node, pipe type, etc. All data on a pipe can be accessed in a detailed form. The detailed form is opened if you double-click in the column at the far left. The values listed from another table, e.g. pipe type, are selected from drop-down lists. Double-clicking in the column header sorts the form according to the highlighted column. There are more options in the right-click menu. Search and filter, delete objects and export to Excel. You can generally select a number of fields in a column and paste a value into the highlighted fields. Detailed form for pipe. You can access all data applicable to the pipe here! If you select a value from a drop-down list, you can restore the field to an empty field by selecting the empty value in the list or deleting the content in that field. Graphic window The graphic window in NetSim is a CAD component which shows the pipe network in the selected model with the correct coordinates. The coordinate system is an arbitrary orthogonal system where the y-axis is of north and x-axis is of east.

31 You can use map files, schedules, etc. in DWG/DXF format as backgrounds to the pipe network. These backgrounds may also include graphics as orthophotos. You can create pipes in and delete them in the graphic window. Points and opens the forms in the database. You can save the network image from the graphic window in DWG/DXF + a number of raster formats and print out all or parts of the network to an optional scale. You can use the layer properties manager under Color tab under the tools ribbon in the menu to select colours and line widths in the map screen for the best display of the pipe network. Doc-To-Help Standard Template Modelling 31

32 File menu Model Management Create new... This function creates a new model in the database. The Calculation opens with a number of preset values for the model. Give the model a name in the field Model name. Then save the model using the Create function in the form. You can now select the model as your current model in the model selector. Copy... This function allows you to make an identical copy of your current model. A dialog box opens in which you give this copy a name. In the copy, you can change most things in relation to the master without changing the master. See section Model management Delete... You can use this function to delete your current model from the model database. A dialog box opens where you can select whether you want to delete the model or cancel the function. Import The Import calculation file function allows you to import a calculation file (see section Calculation module's input data file). The file can be a complete calculatable calculation file or a file just containing definitions of the geometry for the model, e.g. manufactured from a CAD file or exported from a network information system. The import adds information to the model and does not need to be a complete model. You must observe what names pipes and nodes have in the import file in relation to which names you use for pipes and nodes in the model database to which you are importing. If nodes/pipes exist with the same names in the import file and the database, the node in the database receives the coordinates which it has in the import file. Likewise, the pipe in the database is given the geometry which it has in the import file. An import file cannot fully build up all boundary conditions in the model database. For e.g. pumps, any reference value to which the pump is regulated cannot be set up by the import function. This has to be added manually to the model after importing. Calculation... The calculation is configured and enabled in the calculation form.

33 Load factor: Δt factor: Return temp. factor: Heat loss factor: Network level: Ambient temp.: Model type: Pipe diam.: Velocity: Gradient: Default pipe type: A given value in node, flow or power is multiplied by the factor in the input data for the calculation module. A given value in node for cooling is multiplied by the factor in the input data for the calculation module. A given value in node for return temperature is multiplied by the factor in the input data for the calculation module. A given value for the pipe types' heat loss factor (W/m C) is multiplied by the factor in the input data for the calculation module. Enter 1, 2 or 3 for calculation of all pipes in the model, distribution and main pipes or just main pipes. The global ambient temperature against which the heat losses of all pipes are calculated, except for the pipes which have a local ambient temperature specified. Planned or normal. (mm) Included in the dimensioning criteria; see below (m/s) Included in the dimensioning criteria; see below (Pa/m) Included in the dimensioning criteria; see below Included in the dimensioning criteria; see below Doc-To-Help Standard Template Modelling 33

34 Dimensioning criteria: Pressure loss factor 1: Pressure loss factor 2: Pipes with an unknown internal diameter are dimensioned as follows: The program makes a selection from pipe types which are approved for use for dimensioning a pipe type which provides the highest stated velocity. If the internal diameter of this selected pipe type exceeds the value given for diameter, a pipe type which gives the highest stated pressure drop gradient is selected instead. If all the pipes in a ring connection are to be dimensioned, the program uses the type specified as the default for one of the pipes in the ring connection. Pipe type? must not be included in the list. Calibration factor for pressure drop calculation; see below. Calibration factor for pressure drop calculation; see below. Pressure drop calibration The calculated pressure drop in the pipe with factor 1 with the addition of the calculated pressure drop factor 2 the internal diameter of the pipe is reported as a pressure drop in a pipe. The defaults are 1 and 0. Common values for factor 1 are in the range Differential pressure, node: In the specified node, the pressure difference between the supply pipe and the return pipe must be the stated value. A differential pressure and node must be specified for every separate hydraulic network in the model. Headers 1, 2 and 3: These texts pass out in input data to the calculation module and on to the results files. Steam system, Annual run: Select whether the model relates to a network for steam and condensate, a district cooling network, if the calculation is to be executed as an annual run, or if only the supply pipe is to be calculated. Outdoor temp.: Enter the outdoor temperature for which factors for power, cooling and return temperature are to be calculated when updating nodes from customer data. This value is also used when determining the supply pipe temperature from the production plants. Method: Network level: Return temp./δt: Update nodes: Bypass: Select which value is to be used when updating nodes from customer data. Select the customer levels service, distribution or main pipe level to which the customer's data is to be written when updating nodes from customer data. Select which is the values is to be used when updating nodes from customer data. Execute summing of power/flow, return temp./δt from customer data to nodes. NB If you change level, first clean node data (Tools General updating). Execute summing of bypasses from customer data to

35 nodes. Stop criterion: Relaxation: Enter search path: Version Calculation continues until the difference in pressure between two iterations is less than this value, normally If the calculation fails to find a solution before the maximum number of iterations has been exceeded, this is changed to the value which the calculation module has reached. If the value does not exceed 0.09, the result is generally adequate. The value by which the calculation module has to adjust input data for the next iteration. Normal value 0.5. If the calculation module does not reach a solution, change this value to 0.8 or 0.9. This field displays the search path and filename for the latest calculation file. Click to change / filename. The value is 1 or 2. This value affects a method used during the simulation. Standard value is 1. Change the value to 2 if the simulation does not converge to the stopping criteria. Display manual settings: If this is selected, calculation does not start automatically when the input data file for the calculation module is complete, but is displayed only [by the calculation module dialog for selection of a calculation type when the input data file is complete. Calculate: Comment: Save: Exit: An input data file is generated for the calculation module, and depending on setting (above), the calculation module is started. A plain text field. Use this field to document valid calibration factors, etc. Use this function to save current settings in the form. Closes the form without a save function. Doc-To-Help Standard Template Modelling 35

36 Consumers You can use the functions under customer data to import and remove information on consumers (consumption data) in the model. The format of the import file is described in the section entitled Consumption data. Consumer data is organized into three information categories. General information, IDs, names, addresses, etc. Consumption information, power, energy, cooling, etc. Node references, the node in the model in question to which the customer is related at the relevant level (service, distribution, main pipe) The details in the general category are the same for all models where the customer is used, while the details in the other categories are specific to every model. Import new only... This function opens a file opening dialog box where you select which customer data file is to be imported. This function creates, in the model, the customers in the customer data file which are not included in the model. Customers in the customer data file which already exist in the model are not affected. Import all... This function opens a file opening dialog box where you select which customer data file is to be imported. This function creates, in the model, the customers in the customer data file which are not included in the model and replaces information for all customers which exist in the customer data file and in the model with information from the customer data file. Customers which exist in the model but not in the customer data file are not affected. Copy customers... This function copies customer data between models in the database. This function opens a dialog box where you select the model from which you have to copy data to the current model. You select whether all data on the customer is to be copied, i.e. if consumption and coupling to nodes are to be copied or if just consumption data is to be copied (see the section entitled Consumption data). Delete customers... This function is used to delete all customer data from the current model. Customer information for other models is not affected by the function. Export customer data This function is used to write data for all customers in the model to a text file. This text file is formatted as an import file for customers, see the section entitled Consumption data. Save as... You can save the model to a file in a range of vector and raster formats such as DWG, DXF, DGN, JPG, TIFF and PDF.

37 Print.. This function opens the print manager. You can select a printer, paper format, print scale, print range, etc. Exit NetSim This function closes NetSim. Options The size of the zoom box (metres) controls how large an areas is to be displayed in the graphic window when you zoom into nodes and pipes. The sizes of nodes and other items are also set here. If you have problems with snapping to nodes, you can make the setting a little larger (perhaps 2 %). You can set at which zoom level nodes are shown. Try out what seems reasonable 200 or 2000, perhaps. Autozoom according to the highlight. Select this if you want to zoom directly into a node or pipe as soon as you have highlighted it in the grids. This is an effective tool in combination with an appropriate zoom box size. Language. Swedish is the default, but you can switch to English. An Analyse search path is specified here. The search path under which Analyse is normally installed is preset. Help Online manual opens the manual in the browser. Team Viewer. Starts online support with Vitec Energy. Contact one of the Vitec Energy consultants and agree on a time so that they can provide you with instruction or control your NetSim remotely. You submit your ID and password as shown in the dialog box. An Internet connection is required! Doc-To-Help Standard Template Modelling 37

38 About Vitec NetSim shows the versions of the modules installed in NetSim. Reset docking windowresets the configuration to the default setting defined on at delivery. If you have undone the Pipe type directory, for example, you can easily redock it using this function. Note that language settings also are restored to initial value. Home Tab Zoom Window A classic function where you can zoom into part of the network. To Extent A function which ensures that the entire network is visible. It may be useful to use this if you want to return to a kind of start level if you have zoomed in. To node If you have selected a node in the node list, you can select Zoom node in order to centre it in the map and zoom in on the node. To pipe If you have selected a pipe in the pipe list, you can select Zoom pipe in order to centre it in the map and zoom in on the pipe. Previous You can use Zoom previous to go back one step at a time to the zoomed-in screen which you saw previously. You can go back several steps. Pan You can use Pan to take hold of the entire map by holding down the left mouse button, and you can then drag it in any direction without changing the degree of zoom. You can exit this command by pressing Esc or clicking on the command again. Modules Calculator

39 This allows you to open the NetSim3 Calculator separately. The main use for this is to open calculations files sent from another database or with manual changes done after the.netsim file has been created Calculation Starts the calculation module's settings form with the last model calculated preselected. You have the option of choosing another file or calculation type or opening the control files created by the calculation module. Analyse Starts Analyse with the last calculation data. Data management Show selection If you have selected an area or selected pipes and nodes, you can select Filter in grid and so view them in the node list or pipe list. E.g. you can then choose to export to Excel. Note that you have to create two exports, one for the node list and one for the pipe list. Note that nodes can be filtered out only when you have zoomed into the map sufficiently. Show on map When you select one or more nodes and/or pipes in the grids, you can see where they are in the map. Select Show selections on the map when you have finished making your selections in the node and pipe grids. You can select more if you hold down Ctrl while left-clicking at the same time. Show level division You can use Show level division to see in the map which pipes are classified as main pipes, distribution pipes and services. These are displayed with different colours in the map. You can easily see whether you have classified the pipes wrongly. Tools Tab Backgrounds Load This function allows you to add one or more maps as backgrounds in the graphic window. Purge the background map beforehand if you are using a heavy file. Doc-To-Help Standard Template Modelling 39

40 Delete This function allows you to delete background maps from the graphic window. A dialog box shows the maps added as backgrounds, and you select the ones which are to be deleted. Color Background Opens a dialog box where you select a background colour for the graphic window. Layers Opens the setting dialog box for layers in the graphic window. Here, you can influence which colours and line widths which NetSim uses for pipes and nodes and flags. Here, you can also influence presentation of the backgrounds which you imported into NetSim. Layers also lets you show or hide the different text options shown below. Text A function in NetSim involves now placing text on nodes and pipes. When you have selected the items for which you want text, you edit the text style, size and colour in order to view this in NetSim. Under Style Name, select the various layers for which you want text. Set the Font, height, etc. To show or hide text go to the Layers settings.

41 Calculation Tools Notifications See the text on Sectioning option earlier on in this manual. There is an option to shut down an area here. Calculate Net Levels You can use this function to determine which pipes are to be classified as service pipes. Before this takes place, you have to have decided which pipes are to be main pipes, level 3. This is most important if you have pipes with smaller dimensions which are main pipes. Doc-To-Help Standard Template Modelling 41

42 Select Display to view the classification of pipes in the map. Change this classification if you like. Select Run if you want to apply Max. internal diameter AND Length of the pipe network. As far as calculations are concerned, you can execute faster calculations for just main pipes if you have a large pipe network with lots of ring feeds. In this case, move the customer power to the main pipe beforehand. Trim Model This function reduces the number of pipes with similar properties in a model. Set the lengths and the differences in internal diameter and thermal conductivity which are to apply to the pipes. Then press Prepare followed by Run. This can be done several times as it only checks two pipes at a time. Report Select the report to be run for the current model. The report's results are displayed in a grid which you can export to Excel or copy to the clipboard. Reports in the present version are: Production plant Key Numbers Status Summary of total production and total defined consumption in the model. Summary of technical key figures for the model. This report shows all steering parameters for the model, production, pumping, reference values, etc. Summarize Pipes This report sums all lengths, grouped by dimension (pipe type) Price Comments This report sums all lengths and costs, grouped by price category. This report shows all comments made for objects in the database. Model data forms The model forms consist of a grid form which shows primary data for the object type (see the section entitled Model concepts). A detailed form showing all data

43 on the object is opened if you double-click in the row number column to the left of the grid form. The grid forms have a right-click menu containing functions for the form, e.g. save, undo and delete. The grid forms can be filtered, sorted and exported to Excel. The model data forms are: Node grid, detail Pipe grid, detail Production plant grid, detail Pump grid, detail Valve grid, detail Heat exchanger grid, detail Accumulator grid, detail Customer grid, detail (only when creating a new customer) Annual data grid, detail Node form The grid form for nodes shows all nodes in the model. Here, you can switch the name of the node, enter powers/temperatures, etc. The node highlighted in the form is indicated in the map screen. The node form is also displayed with a node highlighted when you highlight a node in the map. The map screen includes the command Zoom node which centres the map screen over the highlighted node in the grid form. Besides the general functions, the right-click menu in the form includes the command Display customers which opens the customer form filtered using the highlighted node name. Doc-To-Help Standard Template Modelling 43

44 Double-clicking in the row number column opens the detailed form for the selected node. This detailed form displays all information which can be given to a node.

45 Pipe form The grid form for pipes shows all pipes in the model. Here, you can change the name of a pipe, change the start and end nodes of a pipe, select a pipe type, change the length and open/close pipes. The pipe highlighted in the form is indicated in the map screen. The pipe form is also displayed with a pipe highlighted when you highlight a pipe in the map. The menu includes the command Zoom pipe which centres the map screen over the highlighted pipe in the grid form. Double-clicking in the row number column opens the detailed form for the selected pipe. This detailed form displays all information which can be given to a pipe. Level: the pipe can belong to service (1), distribution (2) or main pipe (3) level. Levels must be selected so that 3 must form a coherent hydraulic network, level 3 + level 2 must form a coherent hydraulic network, level 3 + level 2 + level 1 must form a hydraulically coherent network. (see production plant form and menu Calculation). Local dimensioning criterion: for every pipe to be dimensioned, a local dimensioning criterion can be specified which replaces the global dimensioning criterion (see Calculation menu). Select whether this criterion is to be applied to the supply pipe, the return pipe or both pipes, as well as values for velocity, gradient and max. diameter (see also the keyword *LDIM). Optional: the pipe is not included in reports for length and volume. Doc-To-Help Standard Template Modelling 45

46 Production plant form The grid form for production plants shows all production plants in the model. You can enter production, temperatures and network pressurisation here. The node in which the plant is located is highlighted in the map screen when you highlight the plant in the grid form. The detailed form for the plants is opened if you double-click in the row number column at the far left. To create a new plant in the model, select Create new in the right-click menu. This opens a detailed form. Give the plant a name or select an existing plant from the list at the top right. Connect the plant to a node, the icon to the near right of the field retrieves the node highlighted in the map. The adjacent icon shows the selected node in the map. You should place the plant at the end of an appendix pipe. No other values, i.e. powers, temperatures, shunts or bypasses, are to be specified in the node in which where you place the plant! Enter either power or flow, enter supply pipe temperature. Enter a pump type and pressurisation of the network, where necessary. The fields max. and min. power are only information you provide so as not to define the plant outside its working range. In the model, there but be one and only one plant for every separate hydraulic circuit without a specified power or flow. Likewise, in a model for every separate hydraulic circuit there must be one and only one plant with data for pressurisation of the model (static pressure). It is possible in the grid form to link a temperature curve to the plant (see section Temperature curves under System data form).

47 Pump form The grid form for pumps includes all pumps in the model. In this form, you have a direct overview of how the pumps are set in the model. In the map screen, select the pipe in which the pump is located when you highlight the pump in the grid form. The data which you enter for a pump relates only to the current model. Thus the same pump can be used in several models with different settings! Some of the columns include drop-down icons which are disabled. These values can be changed instead in the pump's detailed form which you open by double-clicking in the row number column at the far left. To create a new pump, select Create new in the right-click menu. Give the pump a name or select an existing pump from the list at the top right. If a pump type is to be entered, select the type from the list. The pump belongs to the pipe and can relate to a pressure change in the supply pipe, the return pipe and both the supply pipe and the return pipe. Therefore, you must enter values for both the supply pipe and the return pipe. This pump lifts both in the supply and the return pipe, The pump's lift is unknown, and therefore the fields in head supply and head return is empty. The pump is controlled to maintain a 150 kpa differential pressure in node S3 (select type of reference value). Quota S/R is set to 70% which means that 70% of the total lift is taken in the supply pipe and 30% in the return pipe. The pump is located in pipe F4- F5, adjacent to node F4. The icon at the near right of the pipe name field is used to retrieve the pipe which you have highlighted in the map screen, while the icon to the right of this indicates in the map screen the pipe you selected. The icon to the right of the reference value node also retrieves the node which you highlight in the map and the icon to the right of this indicates in the map the node you selected. Max. pump lift and mass flow are items of information sent to the pump control function in Analyse. These values do not restrict the work of the pump in the calculation, but in Analyse they provide information on whether the pump is operating beyond its actual capacity. If the pump lift is determined, you cannot give a reference value. In this instance, enter no setpoints as the reference value type. If you select a pump type and enter a speed, the pump lift is determined via the characteristic for the pump type. In this case, the field for lift must be empty and the reference value type must be no reference values. See also the section Pressure regulations pumps and valves. Although in many cases it is valid, it is in most cases preferable to locate the pump next to node 1 in the pipe. Further, if a pump lift is defined in both the supply and return of a pipe, pumping may not be placed in adjacent pipes. Doc-To-Help Standard Template Modelling 47

48 Valve form The grid form for valves includes all valves (for pressure regulation) in the model. Here, you have a direct overview of how the valves are set in the model. In the map screen, the pipe in which the valve is located is highlighted when you highlight the valve in the grid form. If you double-click in the row number column, the detailed form for the highlighted valve is opened. To create a new valve, right-click in the grid form and select Create new. This opens a detailed form where you define the function of the valve. Give the valve a name or select an existing valve from the list at the top right. This valve has a type linked to it (V100) and an opening degree (15 from closed) is set. The reference value type must therefore be set to no setpoints. The valve is located in pipe A1215 in the return pipe adjacent to node F995, and therefore the field for fixed pressure reduction in supply pipe is empty, and for the supply pipe the fixed pressure reduction is set to 0 (kpa). When a fixed pressure reduction or an opening degree has been entered, you cannot use a reference value. In the same way as for pump (see above), the icons adjacent to pipe name and node name can help you to position the valve in the model. The values which you enter for a valve relate only to the current model. Thus the same valve can be used in several models with different settings! See also the section Pressure regulations pumps and valves.

49 Heat exchanger form Heat exchangers are placed in pipes. The heat exchanger is used to supply energy to or remove energy from the water which flows into the pipe. To create a new heat exchanger, right-click in the grid form and select Create new. A detailed form opens in which you can define the exchanger. The data which you enter for the exchanger is valid only for the current model. Thus the same exchanger can be used in several models with different data! Give the heat exchanger a name or select an existing exchanger from the list at the top right. The power (kw) of a heat exchanger is specified with a basic power (kw) + a temperature-dependent component kw/ C where the temperature relates to the temperature of incoming water in the exchanger. Negative power means that energy is removed from the water (temperature reduction), while positive power means that energy is added to the water in the pipe. This exchanger supplies energy with an power of 4000 kw, regardless of the incoming water temperature, is located in the return in pipe A1102 adjacent to node F899. Accumulator form You create a new accumulator by selecting Create new in the right-click menu. Give the accumulator a name or select an existing one from the list at the top right in the form. Doc-To-Help Standard Template Modelling 49

50 Specify the node in which the accumulator is to be located. As for production plants, the accumulator should be placed at the end of an appendix pipe, and there must be no other values such as power/temperatures/bypasses, etc. in the node. The icon to the left of the node field retrieves the name for the highlighted node in the map. The icon to the right of this shows the selected node in the map. Volume (m 3 ): The accumulator's active volume. Nom. power [kw Nominal power consumption. If this the value is left undetermined, the power balance in the network determines whether the accumulator is loaded or emptied. (N.B. the powers of all production plants must then be specified.) If a value is specified (with characters), the accumulator works with this value during the calculation (N.B. a production plant in the model must have an undetermined power). A positive given power acts like the accumulator is storing, while a negative power acts like the accumulator is unloading energy. Thermal coeff. (kw/ C): Heat loss factor which, when multiplied by the difference between the accumulator's average temperature and the ambient temperature, gives the accumulator's heat loss power in kw. Ambient temp. ( C): accumulator's Min. temp. ( C): of the Max. temp. ( C): of the Average temp.: ( C): The ambient temperature against which the heat losses are calculated. Minimum temperature in the accumulator at the start calculation. Maximum temperature in the accumulator at the start calculation. Initial average temperature in the accumulator at the start of the calculation.

51 Customer form The grid form for customers differs from other grid forms insofar as all data for the customer is displayed in the grids. This is mainly out of consideration for exporting to Excel. When you create a new customer, first select the which is the customer's level 1 placement. In the customer form, then select Create new. This opens a detailed form with which you create the customer. Enter a facility_id, enter a value in at least one of the fields customer ID, customer, property designation or address. Enter a relevant category figure (h) Click on the icon at the near left of the node level 1 field to retrieved the highlighted node's name for node levels 1, 2 and 3. Enter values in the fields for power, consumption, cooling and return temperature. Type 0 (zero) in the fields for which you do not enter values. Select a customer type for power, cooling and return temperature. Then save the customer. You can then edit all data for the customer in the grid form. Doc-To-Help Standard Template Modelling 51

52 System data forms System data is data which is not model-specific but general for all models in the entire installation. Pipe types are one example. The system data forms are structured in the same way as the model data forms, with a grid which shows primary data and a detailed form containing all information for the record. The various types are: Pipe type grid, detail Pump type grid, detail Valve type grid, detail Customer type grid, detail Temperature curves grid, detail Node type/time series grid, detail In general, you can create a new pipe type, pump, etc. by right-clicking and selecting Create new in the number column for the type that you want to create. Pipe types As a minimum, enter a name (max. 25 chars recommended, must NOT include blanks), internal diameter (mm), roughness index (mm) and thermal conductivity (U value, W/m C) for the pipe type. If the type has to be accessible for dimensioning pipes, you must select this. A maximum of 20 pipe types can be selected for dimensioning. An internal diameter of 0 mm signals to the calculation module that the pipe has to be dimensioned! Create a pipe type with a name? which has an internal diameter of 0.00, etc. This allows you to see more clearly which pipes are to be dimensioned. You can provide further information on the type which describes the type in more detail, e.g. material, make, etc. The price categories are utilised by the price report, the pipe's price category being specified with a value of 1 to 6 and the price being retrieved from the pipe type's corresponding value.

53 Pump type The pump characteristic is defined for a pump type in this form, which can then be used for one or more pump facilities. Enter the name of the pump type (max. 8 chars), the speed (revs per second) for which the characteristic is defined. Then enter corresponding values for flow (kg/s), pump lift (kpa) and pump power (kw) in ascending order with regard to flow. Up to 12 points can be entered in the characteristic. Close the curve at both ends, i.e. enter values for flow 0 kg/s and lift 0 kpa. You can provide further details for descriptive information on the pump type, e.g. make and model type. The fields max. speed (revs per second), - power [kw and current (A). Voltage (V) and rated power (kw) are values sent to the Pump control function in Analyse. These values do not restrict the function of the pump in the calculation, but in Analyse they signal whether the pump is operating beyond its actual capacity range. Valve type The characteristic for a valve type is defined in the form. The characteristic is specified as an opening degree 0 90 from fully closed and corresponding capacity value K v (tonnes/h)/bar ½ ). I.e. 0 indicates a fully closed valve and 90 a fully open valve. The characteristic can be specified using up to 10 points. When a valve type is linked to a valve, you specify the current opening degree for the valve; and the pressure drop across the valve is then calculated on the basis of the given characteristic. You can provide further details for descriptive information on the valve type, e.g. make and model type. Doc-To-Help Standard Template Modelling 53

54 Customer type A type for power, return temperature and cooling as a function of outdoor temperature must be related to all customers. The grid form shows the type name and the ID of the type in the database. N.B The type ID must be specified in the import file for customers! If the import file contains types which do not exist in the database, these types are created in the database with a linear function which you can adapt to the required appearance after import. Up to 99 different type curves can be specified in the database. In ascending order with regard to outdoor temperature, enter the factor by which the customer's power, return temperature and cooling is to be multiplied in order to adapt the value to a given outdoor temperature (load case). The calculation form specifies an outdoor temperature for the load case, and use the curves above to sum customers' power/cooling/return temperature to the nodes.

55 Temperature curves You can define the temperature programs for production plants here. In ascending order, enter the outdoor temperature and, for the outdoor temperature, the corresponding supply pipe temperature. In the Production plants form, select which temperature curve is to be used for the plant. When load cases are specified in the calculation form, a function retrieves a supply pipe temperature for the load case from the specified curve. Node type/time series Nodes in NetSim are divided into up to 10 different types. Each type can be controlled individually in a dynamic calculation with regard to flow, power and supply pipe temperature. Typically, all nodes are assigned type 1; apart from production plants, which are given individual types. Furthermore, individual nodes with deviating consumption patterns can be assigned a separate type if necessary. A time (decimal hour) and corresponding factor are specified for every type of value Enter the breakpoints in the time series In the calculation, values for intermediate times are interpolated from the given values. Doc-To-Help Standard Template Modelling 55

56 Calculation The calculation module in NetSim is started directly from the menu under Modules, automatically by NetSim when data is exported from the form Calculation to the calculation module, or directly from the explorer by enabling a calculation file from NetSim. Model file: this field displays the file selected for calculation: You can use the file selector on the right to select a file for calculation, and use the adjacent review icon to open the file in Notes for review/editing (see the section entitled Calculation module, input data file). Results directory: the directory where the results from the calculation are saved. Calculation type: You can switch the calculation type between stationary and dynamic calculation. If you select dynamic calculation, you have to select a time series file using the file selector on the right. You can also open the time series file in Notes using the icon at the far right. Time series calculation: In the case of dynamic calculation, you have to enter a start time, time step length and number of time steps (see the section entitled Dynamic simulation). Calculation status: The calculation status shows the progress of the calculation.

57 Result: You can use the icons on the right to open the text-based results file (.OUT), the control file (.CHK) which shows any errors in input data, and the file containing selected dimensions for pipes which are to be dimensioned (.PTY). You can use soft and quick stop functions to cancel simulation in progress with or without printing the results. You use these functions in cases in which simulation does not appear to converge. File types Input data for the calculation module is: Simulation_name.netsim Keyword. Simulation_name.lmt Simulation_name.cf1 XML file. Limits for pumps. Time series for dynamic calculation. Results files from the calculation module are: Simulation_name.out Simulation_name.xml Simulation_name.plw Simulation_name.plg Simulation_name.plp Simulation_name.pty Simulation_name.sss - Simulation_name.rou Simulation_name.chk Simulation_name.log results printout in text format. results summary in XML format. binary results file. binary results file. XML file. Results limits for pumps. Text file. Dimensions for dimensioned pipes. Text file. Node name for pressure-controlling path through the network. Control file, error messages. Control file, error messages. Doc-To-Help Standard Template Calculation 57

58 Results analysis NetSim Analyse is a tool for analysis and presentation of calculation results produced by NetSim's calculation module. This program is a module operating independently which only requires access to simulation results produced using NetSim. Analyse is started either directly from the menu under Modules or directly from the explorer by enabling a results file from NetSim. Analyse can also be started from the tools field. To be able to open a calculation result, the files beräkningsnamn.plw, beräkningsnamn.plg and beräkningsnamn.out have to be accessible in the same library. The program is structured using menus and tabs for presentation of results as maps, graphs and text-based tables. The tab Overview shows summaries of results for calculation. Click on the links on the left to link to the various sections in the summary. The tab Node table shows node results from the calculation and some input data for calculation. The tab Pipe table shows pipe results from the calculation and some input data for calculation. The tab Charts shows graphs for selected results from the results file. The graph is configured via Settings. The tab Map uses the network's geometry to display result plots and can show supplementary background maps in DWG format. The tab Animation shows the results of a dynamic calculation in graphic format. The menu includes three panels, an archive, chart tools and map tools. In File, you can Open an existing calculation and Save the contents in the Map tab to various vector and raster formats, e.g. DXF, DWG, JPEG. You can use Print to print out the contents in the Map tab. A dialog box opens in which you configure the plot. Pumps opens a dialog box where you can edit design conditions for every pump in the calculation, e.g. max. permitted lifting height. (See the pump and pump type forms.) Reset docking state restores the dockable windows in NetSim to the predefined position. About NetSim Analyse shows version information. Exit closes NetSim Analyse. Dockable windows As in NetSim, you can take hold of a tab and drag it out to a separate window or dock the tab to another window. Try it to see how it works! Remember, you can restore the appearance using Reset docking state!

59 Map A map of the pipe network is created in the Map tab from the geometry description in the results file. A map background in DWG/DXF format can be loaded as a supplement to this screen. Selected calculation results and input data are displayed as tooltips when the cursor is moved next to the object. Nodes are displayed as solid circles (green). Production plants are displayed in red. Nodes with consumption are displayed in magenta. Pipes are displayed with or without colours depending on whether or not the results plotting has been highlighted. The Map tools panel is opened when you select the Map tab. Layer settings Here, you can select whether pipes, nodes, flows and comments are to be displayed or hidden. Zoom This commands can also be found in the right-click menu. Zoom pipe and zoom node highlight and centre the map over the pipe and node highlighted in Pipe table and node table respectively. Pipe settings Select whether the map is to display results for supply pipes or return pipes. Enter a value for scaling the pipe dimension (Scale factor for pipe dimension). A scale factor of 1 displays the pipe without scaling. 100 shows the pipe scaled with a 100 x dimension. Scaling allows you to see clearly which pipes have large and small dimensions. Apply your choice by pressing Apply. Plot limit Select the value to be plotted in the map. You can choose from flow (kg/s), velocity (m/s), temperature ( C), pressure (kpa), pressure difference (kpa), pressure level (kpa) and pressure gradient (Pa/m). Select the Don't show option if you do not want to display any results, just the pipe network. Select the number of colours (interval) to be used to display the results. Enter an upper limit and lower limit for the interval. The maximum and minimum values that appear in the results file are displayed in brackets adjacent to the fields. For example, if you specify 3 intervals and set the upper limit to 100 and the lower limit to 50, all values up to 50 will be displayed in one colour, all values from 50 to 100 will be displayed in the next colour, and all values above 100 will be displayed with the third colour. Apply your settings by pressing Apply. Tooltip Doc-To-Help Standard Template Results analysis 59

60 When you move the cursor over a pipe or node in the map, calculation data can be displayed in a dialog box adjacent to the node/pipe. For pipes and nodes, select which data you want to view in the dialog box. For nodes, you can display name, level (m), pressure in supply and return pipe (kpa), temperature in supply and return pipe ( C), temperature difference ( C), flow from supply pipe to return pipe in the node (kg/s), bypass flow in the node (kg/s) and power (kw). For pipes, you can display name, diameter, pressure gradient in supply and return pipe (Pa/m), velocity in supply and return pipe (m/s), flow in supply and return pipe (kg/s) and heat loss value in supply and return pipe (W/m C). Text Select Add legend and point to the place in the map where you want to position your legend. If you want to move the legend, tag the command again and point to the new location. Select Add title if you want to display the headers from the model. You enter the headers in the calculation form in NetSim. (See also Legend window). Route This function is used to point out a route through the network along which you can display pressure, temperature and pressure gradient in a diagram. You have to enter the node at which the route is to start and where it should end. The routine itself finds the route through the network between the nodes which you indicated. The routine selects in a branch to follow the pipe with the biggest diameter. You can control the route which the routine selects by pointing to nodes which the route has to pass through before you point to the end node. The route selected by the routine is indicated in the map as you point. Remember, you can allow a route to pass to an end point and return from there by continuing to point to nodes. When you have started pointing to nodes with Add node(s) to route, the routine continues to select nodes as long as you continue to point to them. Finish pointing to nodes by pressing Esc. You can delete all nodes in the route by pressing clear route. If you have defined a route, you can add to this route by selecting Add node(s) to route or delete nodes by selecting Undo select. The Route function can also be found in the map's right-click menu. Select object The select object function, which can be found in the map's right-click menu, allows you to point to a pipe or node, and if you switch to the tab Pipe table or Node Table, the data for the selected object is highlighted in the table. Clear selections

61 The clear selections function in the map's right-click menu deletes the highlights in the map which you saw when you opted to display highlighted pipes or nodes in the map in the Pipe table or Node Table tab. Create animation This function creates a slideshow from a time series calculation. See the section on time series calculations. Background maps.. You can use this function to add background maps to your calculation. This function opens a dialog box where you select the map to be displayed. The format can be DWG, DXF or DGN. The dialog box remains open so that you can select more maps or delete maps which you have added as backgrounds. Legend window: In the right-click menu, you can enable a floating window which shows the interval limits in the map.. Charts The tab Charts shows, in diagram form, a selected calculation value along the route through the network which you created in the map. You configure the diagram using the tools in the chart tools panel and in the right-click menu. Plot settings Select which calculation value is to be displayed in the diagram. You can choose from pressure and pressure level in the units kpa, mvp and bar, Pressure gradient in the units Pa/m and bar/km and temperature C. If cavitation pressure is selected, the limit for cavitation in the supply pipe and return pipe is displayed. Select Show level if you want to [go via the nodes elevation. Construction curve 1 Enter a name and value and select whether the temperature in a supply pipe or a return pipe is to form the basis of density calculation, and there is a pressure value which you enter. This curve can, for example, show where there is 16 bar of pressure along the route in a plot of pressure level. Select/deselect Show to enable/disable this curve. Construction curve 2 The same function as Construction curve 1. Doc-To-Help Standard Template Results analysis 61

62 Zoom function You can enlarge a section of the diagram. Hold down the cursor and drag it to the side. Restore the diagram by selecting Undo zoom in the right-click menu. Select data point Click on a point in the diagram to display the coordinates for the point in the diagram in the upper right-hand corner. The node name and curve values are displayed in the bottom left-hand corner. You can use the left/right arrow keys to move along a curve, and use the up/down arrow keys to toggle between curves. Right-click menu You can use the right-click menu to save the diagram to a file/cutout in a range of formats/printers. Check the scaling of the diagram axes, enable/disable grids in the diagram and adapt colours and styles for the curves. The bottom right-hand corner of the diagram shows the time step from which the results are displayed. The total number of time steps included in the calculation. If the calculation includes more than one time step, you can select time steps using < >. Node table Node table displays all calculation results for the nodes in a grid. You can filter and sort in the grid and copy data from there to Excel. You can move the columns so that the sorting suits your needs. Take hold of a column and drag it to the right or left to move it. The table tabs are sorted by doubleclicking the table column headers. You can enable/disable columns by rightclicking in the header row. In the right-click menu, you can opt to view a node in the map, select Show on map. Make sure that you have clicked on Map to load it beforehand. You can select several nodes in the table by holding down Ctrl or Shift. You can select single or multiple rows by pressing Shift/Ctrl and use the clipboard to copy to text or an Excel file by pressing Ctrl+C / Ctrl+V. You can search on node names with the right-click menu. The filter function can be used to filter values less than, greater than, between limits and beyond limits. The bottom right-hand corner shows the time step from which the results are displayed. The total number of time steps included in the calculation. If the

63 calculation includes more than one time step, you can select time steps using < >. Pipe table Pipe table displays all calculation results for the pipes in a grid. You can filter and sort in the grid and copy data from there to Excel. The bottom right-hand corner shows the time step from which the results are displayed. The total number of time steps included in the calculation. If the calculation includes more than one time step, you can select time steps using < >. The table tabs are sorted by double-clicking the table column headers. The filter function can be used to filter the selected column in the table. In the right-click menu, you can opt to view a pipe in the map, select Show on map. Make sure that you have clicked on Map to load it beforehand. You can select several pipes in the table by holding down Ctrl or Shift. The right-click menu also includes a search command which searches on pipe name. You can select single or multiple rows by pressing Shift/Ctrl and use the clipboard to copy to text or an Excel file by pressing Ctrl+C / Ctrl+V. You can move the columns so that the sorting suits your needs. Take hold of a column and drag it to the right or left to move it. Out The tab Out shows input data for the calculation and calculation results for nodes, pipes, pumps, production plants, etc. The pipes dimensioned by NetSim can also be found here, as can a cost calculation if this has been specified in the calculation. The min/max. values for nodes and pipes appear at the bottom of the screen. The dimensioned pipes are only suggestions and must be entered in NetSim to be applicable. Animation The tab Animation shows the results of a dynamic calculation in graphic format, a time series calculation. You can simulate a cold plug or show what it looks like when you load the network. If you have to execute a time series calculation, you Doc-To-Help Standard Template Results analysis 63

64 must configure the input data file prior to calculation. How to configure this is described under Modelling/system data forms earlier on in this manual. Model management General Model concepts The definition of the hydraulic network to be calculated is summarised under a model name in NetSim. This means that the pipes and nodes, production plants, pumps, etc. to be included in the network all have data in the model which has to be calculated. In NetSim, the description of nodes, pipes, etc. is divided between two types of data table, object data tables and model data tables. Names, coordinates, lengths are registered in the object tables. Connections between objects (pipe node, pipe pump, etc.), operating data, e.g. power, cooling, lifting height, pipe dimension are registered in model data tables. A model in NetSim is made up of: A network geometry - a number of pipes connected to one another in nodes Boundary conditions - Values for pressure, flows, powers and temperatures which are given to nodes and pipes. These values can be given directly to the pipes and nodes, but also be applied to these indirectly via other objects such as pumps, production plants, etc. Calculation parameters such as general load factor, ambient temperature, etc. In NetSim, all objects such as pipes, nodes, pumps, etc. are collected in the same database and the model constitutes, in the actual sense, the linking of the above data which has taken place under a model name in the database. This means that one and the same object may be included in several models in the database. Regarding the objects as actual physical objects which can be assigned different properties in different models makes this easier to understand.

65 Objects in the database are identified by an internal ID and a unique name. This means, for example, that two pipes in two models with the same name are one and the same object but with two sets of attributes. A set of attributes in either model. Models can be of two different types, normal mode or planned mode. In the database, it is assumed that a model of a pipe network describes normal mode. This model is assigned normal mode type in the model form. All other models which include nodes and pipes from this model are planning models and are assigned planning model type. When a model describing normal mode is present, it is recommended that you create a planning model which is a copy of the normal mode model and that you assign the model type planning to this copy. You can delete and add pipes and nodes in this planning model without affecting the normal mode model. When an object, node or pipe is present in two models and the object is deleted in one of the models, the object disappears in this model only. The object remains in place in the other model. The object is also deleted from the database only when the object appears in only one model. A planning model can be expected to become obsolete as the normal mode model is changed. This is why the content of a planning model should be checked against the foundation on which it is based if it is used after a period of dormancy. This check can take place graphically by visually comparing a drawing from the relevant model or by applying an appropriately formulated SQL script which compares the content of the two models and points out the differences between the models. Model-specific data To be able to operate NetSim correctly, it is crucial to understand how the program differentiates between data which is object-specific and data which is Doc-To-Help Standard Template Model management 65

66 model-specific. The figure shows which data belongs to which group for the objects in NetSim. Not all data is displayed in the figure. Data which is rarely used and data which has no effect on the calculation is not shown. Objects In NetSim, objects refers to pipes, nodes, production plants, accumulators, heat exchangers, pumps and valves. The object has an internal ID which is hidden from the user and a name which is unique within the object type. I.e. there is e.g. only one pipe with the name P1189, but there could well be a node with the same name! A range of information is linked to each object individually, and a range of information is linked to every object's occurrence in a model. Model A model in NetSim connects pipes and nodes to a network, and the other object types are connected to this network. Example: You create a copy of a model, and in this copy you switch the pipe type in a pipe. In the original model, the pipe still has the same pipe type as before. You want to place a pressure increase station in a pipe in the copy. You can then choose to place in the pipe a pressure increase station which you previously created in another model. Either pressure increase station then has its own data in the two models. You delete a pipe in the copy. The pipe remains in place in the original model. You create a new pipe in the copy. The new pipe appears only in the copy, no other model. A range of data which controls the calculation process and results also belongs to the model. Directory data Pipe types, pump types and customer types are all examples of directory data.

67 Summary: object data - model data Object-specific data Production plant ID Name Comments Accumulator ID Name Comments Heat exchanger ID Name Comments Pump ID Name Comments ± Model-specific data Temperature [ C Power [kw Flow [kg/s Static pressure/location [kpa Pump type Max./min. power Temperature programmes Volume [m³ Max./min.temperature [ C Initial temperature [ C Nominal power [kw Heat loss [kw/ C Ambient temperature [ C Basic power [kw Temperature dependency [kw/ C Location, supply/return pipe Location, node 1/2 Fixt lift, supply/return pipe [kpa Revs, supply/return pipe [revs/s Location, node 1/2 Pump type Reference value, node Reference value, type Reference value [kpa Valve ID Name Comments Fixt pressure reduction, supply/return pipe [kpa Location, node 1/2 Opening degree [0-90 Valve type Reference value, node Reference value, type Reference value [kpa Pipe ID Name Comments Length, supply/return pipe [m Coordinates for direction changes Ambient temperature [ C Node ID Name Comments Type x coordinate y coordinate z coordinate Pipe type, supply/return pipe Closing mode Network level Resistance factor, supply/return pipe Dimensioning criteria Output [kw / Flow [kg/s Cooling/return temperature [ C Shunt temperature [ C Bypass [mm or Kv value Doc-To-Help Standard Template Model management 67

68 Create a new model Connect to the database (Menu File Connect database ) In the File menu, select Model Create new. Give your model a name in the model name field. The name must include no more than 255 characters, but we recommend that you keep your descriptions a little shorter than that! The new model has been created with a range of predefined values for factors and dimensioning. Review and change these to the values you require in your model and save the model by pressing the Create button. If you use the Cancel button, no model will be created. Select your new model as the current model in the Model toolbox. You can now create pipes in the new model or import a NetSim calculation file to the model. Copy a model Delete a model This function is used to create, under a new name, a complete copy of the model you choose to copy. In this copy, you can add/remove pipes and nodes, change pipe dimension, change load cases, production, pumpings, etc. without affecting the master for the copy. What you should not do if you want the master to remain untouched is change the geometry (lengths and coordinates) of pipes and nodes which are the same in the two models! Connect to the database (Menu File Connect database ) In the File menu, select Model Copy. Give your model a name in the field. The name must include no more than 255 characters, but we recommend that you keep your descriptions a little shorter than that! The current model is copied and created when you press OK! If you use the Cancel button, no copy will be created. Select your new model as the current model in the Model toolbox. You can use this function to delete a model from the database. If you delete your current model, you should connect to the database again and select a model in order to update information in graphics and forms. Connect to the database (Menu File Connect database ) In the File menu, select Model Delete. Your current model is preselected. Confirm by pressing the Yes button, or cancel by pressing the No button.

69 Pressure regulations pumps and valves In our experience, pressure regulations in the form of pumps and valves are the area which users generally find hardest to review! The effect of all pressure controls over the entire network needs to be taken into account, and the user has to provide sufficient boundary conditions for the degrees of freedom introduced to every pressure regulation. Location of pumps and valves Pump/Valve is a pressure change in the pipe between the pipe and node 1 or node 2 in the supply pipe, the return pipe or both. Thus a pipe contains four positions where pressure changes can take place. The pressure change can be fixed or controlled by a reference value. The pressure change can be unknown in just one of these positions. All the other pressure changes in a pipe must be specified in some way. There is one exception. If the a pumping is defined in both supply and return in the same pipe at the same end of the pipe and the head is undefined in both supply and return will the total head required to obtain the pressure/differential pressure given for the set point node be divided between the supply and return pumping according to the quota given for the pumping. Although in many cases it is valid, it is in most cases preferable to locate the pump or valve next to node 1 in the pipe. Further, if a pump lift is defined in both the supply and return of a pipe, pumping may not be placed in adjacent pipes. Pressure changes can also be described by defining PUMPS and VALVES which are connected to these positions [at the pipe. When undefined pressure changes are introduced in the pipes, corresponding reference values for pressure must be introduced in the model. This is done by specifying nodes and pressures in these nodes. The stated pressures in these nodes relate to the supply pipe pressure, the return pipe pressure or the difference between the supply and the return pressure, the differential pressure. Both pump and valve can be supplemented with a characteristic. In the case of the pump, for a given speed, the link between flow, pressure and power requirement. In the case of the valve, the link between opening degree and capacity (Kv value) is stated. These characteristics are presented to the calculation module in the calculation file using the keywords *PUMP and *VALV. These keywords are sent to the calculation file only if the characteristics have been defined. Doc-To-Help Standard Template Pressure regulations pumps and valves 69

70 A pump or valve can be viewed as a framework so as to control pressure changes in the four named positions in the keyword *PIPE, and to control supply, return or differential pressure in the keyword *NODE and ensure that the boundary conditions are sufficient in the model. The pump location is indicated in the keyword *PUMP: supply+return, supply, return or in node. (The last option is used only for pumps in production plants.) Current speed for location in supply pipe, current speed for location in return pipe followed by the characteristic. Note that the end of the pipe at which the pump is located is indicated in *PIPE. The location of the valve is indicated in *VALV: supply+return, supply or return. Current opening degree 0 90 from closed position, followed by the characteristic. Note that the same opening degree is applicable to both the supply pipe and the return pipe and that the opening degree is always specified. This means that a characteristic is never indicated for a regulating valve. A pump and valve are given the name of the pipe in the calculation file. This means that only one characteristic can be given to the respective pipe of either pump and valve. Therefore, there are a number of valid and invalid combinations that can be entered by the user. Example The table below shows a number of combinations of locations of pumps and valves in one and the same pipe with and without reference values. * in a field means that the value is calculated. (*) Location 0 : located in both supply pipe and return pipe, 1: located in supply pipe, 2: located in return pipe Reference values in nodes: If a number of reference values have been given in a case, these may relate to the same or different nodes. It is important to note that pressure regulations take precedence over a given reference value. PIPE NODE PUMP VALVE Supply Return Setpoint Node 1 Node 2 Node 1 Node 2 Supply Return revol. (rps) Case ΔP kpa ΔP kpa ΔP kpa ΔP kpa Quota (S/R) P kpa P kpa ΔP kpa Location Supply Return Location Opening deg. A B C * D * E * 0 * F * 0 * * 20 F2 * 0 0 * * 20 F3 * 0 0 * F4 * G * * H * 0 * * I * 0 * J 0 0 * K * 0 * L * 0 0 * * 2 5 M * 0 * * * A: Pipe without pump or valve (pressure increase/pressure reduction). B: Pump in supply pipe at node 1, lifts 200 kpa.

71 C: Pump in supply pipe at node 1, lift is calculated so that DP in reference value node is 300 kpa. D: Pump in supply pipe at node 1, lift is calculated so that DP in reference value node is 300 kpa. Pump in return pipe at node 1, lifts 200 kpa E: Identical pumps in the supply pipe and the return pipe at node 1 with different speeds. Lift in respective pipe function of speed F: Identical pumps in the supply pipe and the return pipe at node 1 with different speeds. Lift in return pipeline function of given speed. Lift in supply pipe is calculated so that DP in reference value node is 300 kpa. The speed is calculated. F2: Invalid! Identical pumps in the supply pipe and the return pipe, but located at either end of the pipe! F3: Pump at either of the pipe in supply and return. Supply pump lifts so that DP in reference value node is 300 kpa. Speed is NOT calculated! Return pump operates at set speed. F4: Pumping at both ends of supply pipe. One pumping set to 200 kpa, the other calculated so that DP in reference value node is 300 kpa. NO PUMP CURVES can be utilised! M: Pumpning in the same end of pipe in both supply and return side of pipe. The total lift in supply + return is calculated so that DP in reference value node is 300 kpa. Pump speed is calculated. The total lift is divided between supply and return side according to the Quota given for the pumping. G: : Pump in supply pipe at node 1, lift is calculated so that DP in reference value node is 300 kpa. Valve in return pipe throttles 200 kpa H: Cannot be resolved! Pump in supply pipe at node 1, lift is calculated so that supply pressure in reference value node is 1000 kpa. Valve in return pipe throttles so that return pressure in reference value node is 500 kpa. Pump speed is calculated! I: Can be resolved! Pump in supply pipe at node 1, lift is calculated so that supply pressure in reference value node is 1000 kpa. Valve in return pipe throttles so that return pressure in reference value node is 500 kpa. Pump speed is not calculated! J: Return throttling at node 1. Valve open 5, pressure change calculated. K: Supply and return throttling at node 1. Valve open 5, pressure changes calculated. L: Can be resolved if pump and valve are located at either end of the pipe! Pump in supply pipe at node 1, lift is calculated so that DP in reference value node is 300 kpa. Valve in return pipe open 5 Doc-To-Help Standard Template Pressure regulations pumps and valves 71

72 Import from CAD Data import from CAD file (additional function) This module in NetSim allows you to convert the contents of a DWG file to a calculation model in NetSim. The DWG file must be designed according to a few simple rules so that it can be interpreted. This module includes tools which you can use to edit/create the file to be interpreted. This module is an additional function to NetSim and can be ordered from Vitec. Drawing style Pipe: A 2D polyline or 3D polyline. All pipes which connect to a T-piece must be broken up in the T-piece. (Only 2D information from a 3D polyline is utilised.) Elevation: A text string (Single line text). Values are stated in metres. Decimal points must be used as decimal separators. Any leading text, e.g. z or equivalent, is ignored.

73 If elevation is not given at the pipe end, this is set to 0. The interpreter reports which nodes have no elevation. Pipe type: A text string (Single line text). Max. 80 characters. The string must not contain blanks. Check that NetSim includes the pipe types occurring in the drawing before you interpret it. The interpreter selects an existing pipe type from the NetSim type directory if the type is not present, and replacements are displayed in a report. Node name: A text string (Single line text). The node name must not contain more than 8 characters. If you enter a node name which already exists in NetSim, the name will be replaced with errorn, where N is a serial number. A check is carried out in NetSim to ensure that N is greater than any N values which may occur in nodes in NetSim called errorn. As a consequence, the interpretation does not create a node with the same name as an existing node in NetSim. No symbol is needed for the node per se, this is created during interpretation; but your work will be easier if you place a circle at the point where the node should be! Pipe name or Prefix to pipe name: A text string (Single line text). Max. 8 characters. Note that if a prefix is used, the total number of characters for prefix + lettering must not exceed 8. If a prefix is used, the pipes will be lettered consecutively within the prefix. The name is checked in the database in order to prevent duplicates. If you set a pipe name in the drawing which already exists in NetSim, this name is replaced by errorn, where N is a serial number. If you use a prefix, the letter is listed by the pipe names that exist with this letter in the database. As a consequence, the interpretation does not create a pipe with the same name as an existing pipe in NetSim. Place the node name and elevation adjacent to the ends of the pipes. Place the pipe name and pipe type in the middle of the pipes. Remember that the insertion point of the text is the point to which the distance is measured. Interpretation Start the interpretation module from the NetSim menu File-Importera DWG [Import DWG. Open the file to be converted. Doc-To-Help Standard Template Import from CAD 73

74 All layers in the file are displayed in the module. You have to select which layers do not contain information and classify what type of information is present in the layers which contain data for your model. Specify drawing layers As you can see, a layer can include several types of data if there are different entity types (TEXT/POLYLINES), and the same data type can appear in several layers. However, it is both safer and more convenient for you if you limit the number of layers in the drawing to just the ones you need. I.e. get rid of background maps, tappings/vents, etc. and make your work easier! I n t h e I g n orera [Ignore column, you have to select the layers in the drawing which do NOT contain data to be processed. Select which layer/layers includes/include the pipe geometry (polylines). Select which layer/layers includes/include node name (TEXT), pipe name (TEXT), pipe type (TEXT), Z level (text).

75 Naming methods and prefixes Prefix ledningsnamn [Prefix pipe name: Pipe names are created as a given prefix + a serial number. Prefix knutnamn [Prefix node name: Node names are created as a given prefix + a serial number. Distans [Distance: The distance within which text is searched for pipes and nodes. Hämta prefix ur karta [Get prefix from map: If this option is selected, all pipe names given in the map which match the values you entered in the field will be given this prefix + a serial number. Every value in the list must be separated with a semicolon. Do not use blanks in the list. Identification is shift-sensitive. INTERPRETATION Interpretation starts when you enable the Tolka [Interpret button. The drawing is analysed and a log opens when the process is complete. Interpretation has created a model which has the same name as the drawing which you interpreted. Analyse the log. If it contains a lot of comments. Correct the drawing, save the drawing and close the drawing interpreter. Delete the model created and reopen the drawing in the interpreter. (If you do not delete the model, the pipes Doc-To-Help Standard Template Import from CAD 75

76 and nodes in the model will block the node and pipe names that you have in the drawing.) Create a calculatable model Open the model which your interpretation created. It has the same name as the drawing file. Create a production plant, link it to a node in the model. Enter in the production plant the supply pipe temperature, static pressure and how the pressurisation is positioned, in the supply, the return or between the supply pipe and the return pipe, and also how close to the supply pipe as a percentage. Enter an power and cooling or return temperature in a node. Open the calculation form and enter there the differential pressure in a node, global factors, dimensioning criteria and pressure calibration factors. Specify and name a calculation file and execute a calculation. It may be a good idea to check that the network is connected together before you execute your calculation. Use Identifiera hål i modell [Identify holes in model from the Verktyg [Tools menu in NetSim. Combine interpreted model with existing model There are not so many stages here! Open the calculation form, specify and name a calculation file, select Visa manuella inställningar [Display manual settings and press the Beräkna [Calculate button. Do not start the calculation module without opening the calculation file in Anteckningar [Notes (the button at the top right). Search for the first row starting with *NODE, delete all rows above this row and save the file. If you do this, you will retain all model headers and factors unchanged. Close the calculation module, in NetSim open the model which you have to supplement with pipes from your interpreted drawing. In the menu, select Arkiv [File - Importera beräkningsfil [Import calculation file and highlight your file. The pipes and nodes in the file now become members of the model! Important! The pipes which you import must be linked in one or more cases to an existing node in the model to which you import. If you take the file as it is, you have to search for the connection points and select there the new pipe and switch the node from the node which came with the import to the node which already existed in the model at the connection point. There will now be a node left over in the model which has no pipes to it. You have to delete this node. Search for it in the node table and select Ta bort object [Delete object. Of course, you can switch the node names directly in the import file, but if you do then remember that the name has to be changed both in the keyword *NODE and at the point where it occurs in the keyword *PIPE. The safest thing to do it use search/replace when you do this! Editing a drawing in the interpretation module The drawing function in the interpretation module is a CAD component. This means that you can edit, add and create pipes in the module using standard

77 CAD commands found in the menus Edit, Draw and Modify and save your changes via the File menu. Doc-To-Help Standard Template Import from CAD 77

78 Data import from network information system With NetSim's data storage in a powerful relational database, receiving data exports from various network information systems and building calculation models in NetSim is generally an uncomplicated procedure. Vitec Energy has prepared procedures for importing from most major systems on the market. Contact Vitec for more information.

79 Consumption data Import file for customer data Customer data can be imported to the NetSim database via an ASCII file in a fixt format. All data belonging to a customer (a record in the import file) is given in one and the same row, and all fields have to be separated by the character (ASCII character no. 164). Every record (row) must contain 29 fields. If the last field Memo and the field separator are omitted between the 24th and the 25th field, the value 0 is recorded in the Memo field. The fields must be entered in the sequence shown in Figure 1 below. There must be a value in fields marked NOT NULL. Other fields can be left blank. In fields with data type VARCHAR2, alphanumeric text strings can be entered with a maximum number of characters as stated in ( ). In fields with data type NUMBER, only numerical characters can be entered with a maximum number of characters as stated in ( ). NUMBER(15,3) means that 15 digits can be entered in the field, of which 3 are decimals. NUMBER(2) means that figures between 0 and 99 will be accepted. See also section Input data in general below. Example, Figure 1: ACME AB Kv Bofinken 4 Trastvägen 3, Solna 2250 LA102 LA New customer Import file preparation If the user himself is going to manufacture the import file from a export from a debit system, the easiest way to do this is using a spreadsheet program such as Excel or similar, unless the debit program supplies the data directly in the intended format. 1. Import the data to the spreadsheet program. 2. Arrange the data in columns in the same sequence as shown in Figure 1 above. See Customer data field description below. 3. Calculate the field values not obtained from the debit program in the spreadsheet program, or enter an appropriate default value. Check att the max. number of characters in each field is not exceeded. 4. Open the control panel and national settings. As a list separator, enter the character under the tal [figures tab Doc-To-Help Standard Template Consumption data 79

80 5. Save the spreadsheet in semicolon-delimited format with a TXT extension. 6. Close the spreadsheet. 7. Reset the list separator in national settings to its regular value. Import customer data to NetSim databas 1. Start NetSim, connect to the database and select the model. 2. Select Arkiv [File Kunddata [Customer data. 3. Select what you want to do. The following options are available: Import endast nya [Import new only, Importera alla [Import all, Kopiera kunder [Copy customers, Export kunddata [Export customer data or Ta bort all [Delete all. Select Lägg endast nya [Add new only if only new customers are to be set up and existing customers in the database are not to be updated. Select Importera alla [Import all if the data in the import file is to replace the data in NetSim. Select Kopiera kunder [Copy customers if customers are to be copied from another model to the current model. The import file is not used in this option. 4. Select the file. 5. A message is displayed when the import is complete, and a log is displayed which indicates where any errors were found in the import file. Update nodes with consumption from customer data When updating nodes with consumption from customer data, all customers' loads are summed to the node to which the customer is related. The resulting cooling or return temperature written to the node is a weighted average value for all customers connected to the node. The update affects the active model only. 1. Start NetSim, connect to the database and select the model. 2. Select in the menu Arkiv [File Beräkning [Calculation. 3. In the kundfaktorer [customer factors section, enter a value for outdoor temperature. 4. Indicate the customer data field from which som the customer's power is to be calculated. 5. Indicate the network level to which summing is to take place. 6. Select whether cooling or return temperature is to be transferred to the nodes. 8. Press the Uppdatera knutar [Update nodes button, or press the Bypass button if bypasses at customers' premises are to be summed to the nodes. 9. Close the form. Customer data field description MODEL: Not specified in import file. On import, the customer is bound via the node references given to the customer and active model

81 to model. If no nodes are given on import, the customer is not bound to any specific model. 1. FACILITY ID: The unique code which identifies the customer and the location. NULL: No. VARCHAR2(40). 2. CUSTOMER ID: The code which identifies the customer, may differ from the plant ID. 3. CUSTOMER: Customer name. 4. PROP. DESIGNATION: A property designation, where applicable. 5. ADDRESS: Address. 6. NODE LEVEL 1: The node to which the customer belongs in the model in level 1. The node must belong to the model. 7. NODE LEVEL 2: The node to which the customer belongs in the model in level 2. The node must belong to the model. 8. NODE LEVEL 3: The node to which the customer belongs in the model in level 3. The node must belong to the model. 9.STATUS: The customer is existing or planned. Enter a value 1 for an existing customer and 2 for a planned customer in the import file. 10. CUSTOMER TYPE POWER: Enter a number for a type curve. Type curve 1- constant factor 1.0 is preinstalled. Controls which type curve is to be used for the customer for power requirements. If the specified curve is note present, a new curve is created with factor = CUSTOMER TYPE COOLING: Enter a number for a type curve. Type curve 1 - constant factor 1.0 is preinstalled. Controls which type curve is to be used for the customer for cooling. If the specified curve is note present, a new curve is created with factor = CUSTOMER TYPE RETURN TEMP.:Enter a number for a type curve. Type curve 1 - constant factor 1.0 is preinstalled. Controls which type curve is to be used for the customer for return temperature. If the specified curve is note present, a new curve is created with factor = CATEGORY FACTOR: When energy consumption is summed to nodes, energy consumption is divided by the category factor. 14.PERIOD: The export from customer data may include information on the period from which the details are taken. NULL: No. VARCHAR2(30). 15. NOMINAL POWER: The customer's nominal power, kw 16. NOMINAL FLOW: The customer's nominal flow, kg/s 17. HEAT CONSUMPTION I: Consumed energy for period 1, MWh 18. HEAT CONSUMPTION II: Consumed energy for period 2, MWh 19. WATER CONSUMPTION I: Consumed water for period 1, m3 Doc-To-Help Standard Template Consumption data 81

82 20. WATER CONSUMPTION II: Consumed water for period 2, m3 21.AVERAGE COOLING: The customer's average cooling, degrees C. Customer data includes details on either average cooling, or average return temperature. When importing customer data, 0 is entered as the input data value for the one of the parameters which is not given. 22. AVERAGE RETURN TEMP.: The customer's average return temperature, degrees C. 23. AREA/VOLUME: Area or volume (m2 or m3). When summing customer load to nodes, the value is converted to kw (1:1). 24.BYPASS DIAMETER: Bypass in FC, mm. When summing customer load to nodes, all bypasses are summed in FC and an equivalent bypass is calculated for the node. 25. COMMENTS: Plain text field REG. DATE (TODAY): 26POSTAL ADDRESS: Not specified in import file. This field shows when registration took place in NetSim. The field is completed automatically with system's time specification regarding when the import took place. Postal address for when the notification function is used. 27. NOTIFICATION 1: The customer's name for when the notification function is used. 28. NOTIFICATION 2: The customer's name for when the notification function is used. 29. NOTIFICATION 3: The customer's name for when the notification function is used. Input data in general In fields with data type VARCHAR2, alphanumeric text strings can be entered with a maximum number of characters as stated in ( ). In fields with data type NUMBER, only numerical characters can be entered with a maximum number of characters as stated in ( ). NUMBER(15,3) means that 15 digits can be entered in the field, of which 3 are decimals. NUMBER(2) means that figures between 0 and 99 will be accepted. See also section Input data in general below. Summing of customer data to node Index I indicates the i:th customer of n related to a node. Summing of energy period 1: Summing of energy period 2:

83 Summing of nominal power: Summing of area/volume: Summing of nominal flow: Summing of water consumption period 1: Summing of water consumption period 2: Summing of cooling: Summing of return temperature: Summing of equivalent bypass: Factor-controlled power The function Factor-controlled power means that when power and cooling are summed from customer data to the nodes in the model, a temperature is specified as a parameter. The temperature specified is the outdoor temperature for the current load case. Every subscriber is allocated a type which corresponds to a type curve. This type curve specifies for different outdoor temperatures the factor by which the customer's nominal power has to be corrected in order to Doc-To-Help Standard Template Consumption data 83

84 attain the normal power in this operating case. See the example in the diagram below. Factor-controlled cooling Information on average cooling over the period to which the information applies (normally one year) is stored for the customer in the customer data register. The function Factor-controlled cooling means that when power and cooling are summed from customer data to the nodes in the model, a temperature is specified as a parameter. The temperature specified is the outdoor temperature for the current load case. Every subscriber is allocated a type which corresponds to a type curve. This type curve specifies for different outdoor temperatures the factor by which the annual average cooling has to be corrected in order to attain the normal cooling in this operating case. See the example in the diagram below. The program which sums the load from customer data interpolates/extrapolates from the curve the factor applicable to every type for the temperature specified as a parameter on summing. We assume that the customer type, viewed from this angle, will not be registered previously in the customer database. Therefore, every customer must be assigned customer type 1 on import. This customer typ 1 is a linear curve with the factor value set to 1.0 and is predefined in the table.

85 Factor-controlled return temperature If we assume that the return temperature recorded is the annual average return temperature, we can utilise the customer type above in the same way as the factors for cooling. We assume that the customer type, viewed from this angle, will not be registered previously in the customer database. Therefore, every customer must be assigned customer type 1 on import. This customer typ 1 is a linear curve with the factor value set to 1.0 and is predefined in the table. Calculation module's input data file Summary The calculation module's input data file can be used by an experienced user to directly create input data for the calculation module and define more complex boundary conditions than is possible in the database. The input data file is based on a concept involving keywords combined with plain text. It can be created manually using an editor or from a NetSim database. The editor's only restriction is that the input data file must be saved as an ASCII file. Of course, you can use an input data file created by NetSim as a master and manipulate this in a editor. Data format The input data file contains keywords. Every keyword is linked with a specific number of figures and text strings. Keywords, figures and text strings can be input freely, with the exception of the following rules: Doc-To-Help Standard Template Calculation module's input data file 85

86 Keywords must start in column 1. Only keywords are permitted in column 1. The specified sequence of figures and text strings must be followed. A figure is only recognised as a figure if there is a space on either side of it. A text string is only recognised as a text string if it is enclosed in inverted commas ( ). An unknown value can be indicated by an asterisk * or the figure E+30. Explanatory text may be entered in a keyword. All text which is not a figure or a text string as defined above will be ignored. As a result, the keywords in the example below are all identical: *PFAC *PFAC Faktor 1: 1.3 Faktor 2: 0.3 *PFAC k = * Diameter. The order of the keywords is not free. A keyword which refers to another keyword must be defined after the primary keyword. An example is the pipe keyword which refers to the names of nodes. This is why the pipe keyword has to be placed after the node keyword. Summary: keywords All input data for the calculation module can be entered with the following keywords: - Accumulator *ACCU - Stop input data *STOP - Dimensioning *DIAM - Flow factor *FFAC - Supply/return *FORW - Implicitly defined pressure tank *PSUB - Node *NODE - Pipe *PIPE - Local pipe dimensioning *LDIM - Ambient temperature *ATMP - Pump, booster or regular *PUMP - Pump administration *PQTA - Shunt valve *SHNT - Simulation cooling *COOL - Stop criterion *ILIM - Simulation mode *VERS - Temperature *TEMP - Title *TITL - Pressure loss correction *PFAC

87 - Water hammer calculation *DYNP - Valve *VALV - Heat exchanger located in a pipe *HEAT - Steam in supply pipe *STEA - Year simulation *YEAR Keywords Keyword *ACCU The keyword *ACCU is used to define an accumulator in a node. FORMAT: *ACCU <NodeID, Tmax, Tmin, Volacc, Hloss, Tini, Ts, Pnom> Where: NodeID: Tmax: Tmin: Volacc: Hloss: ambient Tini: Ts: Pnom: Node identification The maximum temperature in the accumulator. ( C). The minimum temperature in the accumulator. ( C). The accumulator's active volume. (m3). A heat loss coefficient which, when multiplied by the average temperature in the accumulator and the average temperature, gives the loss in kw. (kw/ C). Initial average temperature in the accumulator. ( C). The average ambient temperature. ( C). Nominal power. If simulation is used for dimensioning of accumulators, Pnom must not be entered, i.e E+30 or * must be entered. (kw). If Pnom is positive energy is stored in the accumulator. If Pnom is positive energy is delivered from the accumulator. Note that if *COOL is active you have to think the other way around. Note that the keyword *ACCU must be entered after the keyword *NODE. Note that if the node is provided with an accumulator, no other devices are permitted in the node (e.g. a bypass). Keyword *ATMP The keyword *ATMP is to be used to enter individual ambient temperature. FORMAT: *ATMP < ledningsid, omgivn.temp> Where: ledningsid: omgivn.temp: pipe identification specific ambient temperature for the pipe. (C) This keyword can be entered only after *PIPE, where all pipe identifications are entered. If the keyword is entered earlier, an error message will be received as the pipe is unknown at this point. The keyword can be omitted entirely. Example: Doc-To-Help Standard Template Calculation module's input data file 87

88 *ATMP ledning: A3F omgivn. temp.: 10 C Note that if the option of varying the ground temperature in an annual run is used, the program ignores the temperature variation in the pipes assigned an individual temperature via the *ATMP keyword. Keyword *COOL This keyword is used to calculate a cooling system instead of a heating system as normal. This keyword has no arguments. Keyword *DIAM This keyword is used to define the pipe directory used for dimensioning of one or more pipes. This keyword must come before the pipe keyword. FORMAT: *DIAM <krit1 krit2 LIM typ typ1 d1 v1 k1 typ2 d2 v2 k2.... typ20 d20 v20 k20 > Where: krit1: krit2: LIM: Typ: is the velocity criterion in m/s. is the gradient in Pa/m. is the pipe diameter in mm below which the velocity criterion and above which the gradient are to be applied. The default pipe type is used for a possible flow route through a ring connection. The dimension is used only when all pipes in a ring connection have unknown dimensions. In this case, the type will be specified as typ regardless of the dimensioning criterion. The possible flow route is indicated by * in the input data element of the printout. name of the pipe type (max. 8 characters enclosed in inverted typ1: commas) d1: the internal diameter for the pipe type (mm) v1: heat transfer coefficient (W/( C m)) k1: roughness for the pipe type (mm) This list may include up to 20 different pipe types. If fewer than 20 types are specified, the table must be ended with a / (slash). Note that if e.g. the velocity criterion (1 m/s) is to be used for all diameters, krit1, krit2 and LIM must be 1.0, * and * respectively. Similarly, if the gradient criterion of 103 Pa/m is to be used for all diameters, krit1, krit2 and LIM must be *, and * respectively. Example:

89 *DIAM Velocity criterion 3.0 m/s Gradient criterion 1.0 Pa/m Limit 75.0 mm Default pipe type N200 Type I.Diam v k N N N N N N N / Keyword *FFAC This keyword is used to specify a flow factor. The flow factor is a constant which is multiplied by all flows and power demands. FORMAT: *FFAC <faktor> Where: faktor: Constant to multiply by all flows and powers. If *FFAC is not entered, the value 1.0 is used. Example: *FFAC Flow factor : 1.25 Keyword *FORW When the keyword *FORW is specified, only one calculation of the supply pipe is executed. If nothing is specified, the program always calculates both supply and return. FORMAT: *FORW The keyword can be omitted entirely. Example: *FORW Only supply pipe is calculated. Keyword *HEAT This keyword is used to describe the amount of energy supplied to the system via a heat exchanger in the pipe. By default, heat supply takes place in a node. The energy supplied to the system is dependent on the absolute temperature in the pipe. The power is defined as: Power = A + B * T where A: Constant B: Constant T: Temperature upstream of the heat exchanger in degrees Celsius. FORMAT: *HEAT <ledningsid> <ände> <sida> <faktor A> <faktor B> Doc-To-Help Standard Template Calculation module's input data file 89

90 <pris1> <pris2> <pris3> <pris4> Where: Ledningsid: Name of the pipe in inverted commas. Ände: Upstream or downstream end for positioning of heat exchangers. Enter 1 for upstream end and 2 for downstream end. Sida: The water heater can be positioned in either the supply pipe or the return pipe. Enter 1 for supply pipe and 2 for return pipe. faktor A: Power delivered to the pipe in kw. faktor B: Power delivered to the pipe in kw. pris1: The energy price for the energy. SEK/kWh. pris2: C tax for the energy. SEK/kWh. pris3: N tax for the energy. SEK/kWh. pris4: S tax for the energy. SEK/kWh. Example: *HEAT Ledningsid: K01-K02 Ände: 1 Sida: 2 Faktor A: Faktor B: Energy pris: C-tax: N-tax: S.tax: Keyword *ILIM This keyword is used to define the stop criterion and relaxation of iteration. FORMAT: *ILIM <rlim> <relax> / Where: rlim: calculations. Relax Relative stop criterion for pressure and temperature Value for relaxation of the iteration. This figure must be in the range between 0 and 1 A value of 0.8 indicates that only 20% of the difference between two iterations is utilised. If *ILIM is not specified, the defaults for rlim and relax are and 0 respectively. Example: *ILIM Iteration criterion: Relaxation : 0.0 / Keyword *VERS This keyword is used to affect in what mode the simulation is preformed. FORMAT: *VERS <value> Where: value: The value is 1 or 2. This value affects a method used during the simulation. Standard value is 1. Change the value to 2 if the simulation does not converge to the stopping criteria. The keyword is given without closing /

91 Example: *VERS 1 Keyword *LDIM This keyword is used if there are pipes to be dimensioned with criteria other than the ones used in global dimensioning, which is described under the keyword *DIAM. FORMAT: *LDIM < ledningsid, krit1, krit2, LIM, sida> Where: ledningsid : krit1: krit2: LIM: to sida: pipe and The name of the pipe to be dimensioned. Max. permitted velocity in m/s. Maximum permitted gradient in Pa/m. The pipe diameter in mm below which the velocity criterion is be applied and above which the gradient is to be applied. Is the same as *, 1 or 2 depending on whether both the supply the return pipe, only the supply pipe or only the return pipe is to be dimensioned. Note that when this keyword is used, the pipes in question are dimensioned using the specified pipe types under the *DIAM keyword. If only velocity is to be used, krit2 and LIM must be equal to E+30 or *. Similarly, if only the gradient criterion is to be used, krit1 and LIM must be equal to E+30 or *. There is no limit on the number of pipes that can be dimensioned. Keyword *NODE The keyword *NODE is used to enter node data. If a value is unknown, * or E+30 is specified. FORMAT: *NODE < Nodeid, ntyp, xkoord, ykoord, elevation, flöde, effekt, pframl, preturl, dp, tinl, tframl, tretur, dt, lambda1, lambda2, pris1 pris2, pris3, pris4> / Where: Nodeid : node identification (-) Ntyp : node type, an integer in the range 1 to 10. Xkoord : x coordinate (m) Ykoord : y coordinate (m) Elevation : node level (m) Flöde : flow volume through the node (kg/s) Effekt : power (kw) Pframl : pressure, supply pipe (kpa) Preturl : pressure, return pipe (kpa) Dp : differential pressure (kpa) Tinl : inlet temperature in supply pipe (C) Tframl : mixed temperature in supply pipe (C) Treturl : return temperature (C) Dt : cooling (C) lambda1 : reference value for thermostatic bypass (bypass) (C) lambda2 : diameter for fixed bypass (mm) pris1: : production price (SEK/kWh). If no production price is to be Doc-To-Help Standard Template Calculation module's input data file 91

92 specified, type just a / pris2 : COx, Environmental charges. Price per kwh produced. pris3 : NOx, Environmental charges. Price per kwh produced. pris4 : SOx, Environmental charges. Price per kwh produced. If a node includes a bypass, min, power = 0 must be set in the node (no cooling/return temp.) for the bypass to be exported to the calculation file. Example: *NODE Name : NODE01 Node type : 1 X coordinate : m Y coordinate : m Elevation : 22.5 m Flow : * kg/s Power : 12.3 kw Pressure supply pipe : * kpa Pressure return pipe : * kpa Differential pressure : * kpa Supply temperature : * C Supply pipe temperature : * C Return pipe temperature : * C Cooling : 15.9 C Reference value temperature : * C Bypass diameter : 10.0 mm Production price : 0.70 SEK/kWh COx Price : 1.00 SEK/kWh NOx Price : 1.00 SEK/kWh SOx Price : 1.00 SEK/kWh Keyword *PFAC This keyword is used for calibration of the pressure losses in the network. FORMAT: *PFAC <fac1, fac2> where the correction factor multiplied by the normal friction pressure loss in the pipe is: Where: correction factor = fac1 + fac2 *Diameter(i) m fac1 : Constant fac2 : Constant If *PFAC is not specified, the defaults are: fac1 = 1.0 fac2 = 0.0 Example: *PFAC Keyword *PIPE Constant term: 1.05 Diameter dep. term: 0.31 The keyword *PIPE is used to enter pipe data. If any data for the keyword is unknown, * or E+30 must be used. FORMAT: *PIPE < ledningsid, Node1, Node2, ledningstyp, diam1, u1, ε1, z1, längd1 diam2, u2, ε2, z 2, längd2,

93 flöde, dpnode1f, dpnode2f, dpnode1r, dpnode2r, pnode1f, pnode2f, pnode1r, pnode2r, dtnode1f, dtnode2f, dtnode1r, dtnode2r, tnode1f, tnode2f, tnode1r, tnode2r, / xn, yn,> / Where: ledningsid : pipe name (-) Node1 : node name 1 (-) Node2 : node name 2 (-) ledningstyp : from pipe type directory diam1 : internal diameter (mm) supply u1 : total heat transmission coefficient (W/mK) supply ε 1 : pipe roughness (mm) supply z 1 : individual pressure loss in the pipe (-) supply längd1 : length of supply pipe (m) diam2 : internal diameter (mm) return u12 : total heat transmission coefficient (W/mK) return ε 2 : pipe roughness (mm) return z 2 : individual pressure loss in the pipe (-) return längd2 : length of return pipe (m) flöde : mass flow (kg/s) dpnode1f : change of the pressure in node 1 supply (kpa) dpnode2f : change of the pressure in node 2 supply (kpa) dpnode1r : change of the pressure in node 1 return (kpa) dpnode2r : change of the pressure in node 2 return (kpa) pnode1f : pressure in node 1 supply (kpa) pnode2f : pressure in node 2 supply (kpa) pnode1r : pressure in node 1 return (kpa) pnode2r : pressure in node 2 return (kpa) dtnode1f : DT in node 1 supply (C) dtnode2f : DT in node 2 supply (C) dtnode1r : DT in node 1 return (C) dtnode2r : DT in node 2 return (C) tnode1f : temperature in node 1 supply (C) tnode2f : temperature in node 2 supply (C) tnode1r : temperature in node 1 return (C) tnode2r : temperature in node 2 return (C) xn : x coordinate for breakpoint (m) yn : y coordinate for breakpoint (m) A / slash must be typed after tnode2r. After that, up to 100 pairs of coordinates can be specified for the pipe's breakpoints. Breakpoint coordinates are terminated with a / slash. Example: *PIPE Pipe ID: L1 Node1: K1 Node2: K2 Diameter U value. Roughness Single-use resistance Framl Returl Flow * Node1 supply Node2 supply Node1 return Node2 return Pressure changes Pressure * * * * Pressure changes Temperatures * * * * / Breakpoint x: y: Breakpoint x: y: / Keyword *PSUP This keyword is used to define an implicit pressure for a pressure control. Doc-To-Help Standard Template Calculation module's input data file 93

94 The absolute pressure is entered as an arbitrary constant pressure. The constant is a certain element of the differential pressure above the return pressure. The supply and return pressures are defined in equations: Ps = Pa + ( 1 - x) * Pd Pr = Pa - x * Pd where Ps: Supply pipe pressure Pr: Return pipe pressure Pd: Differential pressure Pa: Arbitrary constant defined by the user. X: Fraction FORMAT: *PSUP <Pres, frak Pres: Frak: pressure. Example: *PSUP Constant Proportion of the differential pressure above the return Constant pressure: 1500 kpa Fraction:.2 Keyword *PUMP This keyword is used to enter pump data. FORMAT: *PUMP <pipeid, sida, naf, nar, pris1, pris 2, pris3,pris4, ndef, flödei, dpi, efi, >/ i = 1-12, i.e. up to 12 points can be specified. Where: pipeid : Pipe or node ID sida : 0 both supply pipe and return pipe 1 supply 2 return 3 node naf : Current speed for the supply pipe (revs per sec) nar : Current speed for the return pipe (revs per sec) pris1 : Operating cost for the pump (SEK/kWh) pris2 : C tax (SEK/kWh) pris3 : N tax (SEK/kWh) pris4 : S tax (SEK/kWh) ndef : Speed for which the pump characteristic is specified (revs per sec) flödei : Mass flow at which the pump pressurises dpi (kg/s) dpi : Pressure increase (kpa), corresponding to flödei efi : Power (kw), corresponding to flödei Example:

95 *PUMP Pipe ID : L1 Supply/return : 2 Curr. speed supply pipe : 0 revs per sec Curr. speed return pipe : 25 revs per sec Pump cost : 0.70 SEK/kWh C-tax : 0.4 N-tax : 0.2 S-tax : 0.8 Pump characteristic defined for : 24 revs per sec Flow Lift Power / Keyword *PQTA This keyword administers the distribution of lift between the pumping performed in the same pipe in both supply and return side and located in the same end of the pipe. The total lift must be determined by a boundary condition, pressure in the supply / return pipe or pressure differential in a node in the model where the pumping has authority. The keyword is placed after the key words * PIPE in the calculation file. FORMAT: *PQTA pipeid Quota / Pipeid: Quota: Example: *PQTA F4-F5 50 / *PQTA F7-F8 70 / Pipe identification Proportion in % (integer) of the total lift taken by the supply pump. The rest, (100 Quota) is taken by the return pump. Quota must be in the range of Keyword *SHNT This keyword is used to describe a shunt valve. FORMAT: *SHNT <Nodeid, Tshnt> / Nodeid : node identification (-) Tshnt : Required temperature Note that if the node is provided with a shunt valve device, no other devices are permitted in the node (e.g. a bypass). As there is a node reference under the *SHNT keyword, this must be specified after the *NODE keyword. Even a requested supply pipe temperature cannot always be obtained. If e.g. Tshnt = 100 C and max. temperature in the network is 90 C. In these cases, a warning is issued. Keyword *STEA This keyword is used when the medium in the supply pipe is steam and there is water in the return pipe (liquid phase). Doc-To-Help Standard Template Calculation module's input data file 95

96 FORMAT: *STEA This keyword has no arguments. Keyword *STOP This keyword must be entered last in the file in order to make it clear that there is no further input data. After this keywords, the input data file is closed and calculation begins. FORMAT: *STOP Keyword *TEMP When the keyword *TEMP is entered, it is assumed that there is a constant ambient temperature which is applicable to the entire network. FORMAT: *TEMP <omgivn.temp> Where: omgivn temp.: constant ambient temperature.(c) If there are any deviating temperatures in the network, use the keyword *ATMP. Example: *TEMP Out. temperature: 5 degrees Keyword *TITL *TITL is used to place a header in the printout of results. FORMAT: *TITL <rad1> <rad2> - <rad20> Where: rad : Max. 70 characters per row in the header. Max. 20 text rows can be specified in the header. If fewer rows are specified, the final row must end with a / ( slash ). Example: *TITL Network option /DV / Keyword *VALV This keyword is used to enter data for pressure-regulating valves. FORMAT: *VALV <ledningsid, sida, alfa, alfa1, kv1, alfa2, kv2,..., alfa10, kv10> / Where: ledningsid : Pipe identification (-) sida : 0 both supply and return

97 1 supply 2 return alfa : Valve opening degree (degrees) (0 = closed valve) alfa1 : Valve position (degrees) kv1 : Valve coefficient ((t/h)/bar ½ ) (belongs to alfa1).. alfa10 : Valve position (degrees) kv10 : Valve coefficient (belongs to alfa10) Up to 10 data pairs of valve positions and valve coefficients can be entered. The table must be specified with decreasing valve position values. If fewer than 10 data pairs are specified, the table must be ended with a / (slash). Example: *VALV Pipe ID : R1 Supply pipe : 1 Valve characteristic: Alfa Kv / Keyword *DYNP This keyword is used to create input data from a stationary calculation in NetSim to a dynamic calculation by the network. When keywords are entered in the DAT file, results file is created with the extension.sss. The SSS file contains geometry, pipe types and the ratio in the stationary calculation to pressure and flows in the pipe network. FORMAT: *DYNP <DynOpt> Where: DynOpt is an integer which defines which part of the pipe network must be shown in the SSS file. - To include the supply pipes, enter 1 - To include the return pipes, enter 2 If the keyword is omitted, or DynOpt is set to 0 or *, the link will not be enabled. Otherwise an error message will be generated. Unit conversion for pressure: Pressure is given in the SSS file in mvp, while pressure in NetSim's power data file is given in kpa. To convert the pressures between the units kpa and mvp, the equation below is used: p [mvp = p [kpa x 9.81 where p is pressure. Keyword *YEAR Doc-To-Help Standard Template Calculation module's input data file 97

98 This keyword is used to describe a series of stationary simulations with different loads and durations. This results in an accumulated heat consumption, heat production and operating costs for heat production and pump operation. FORMAT: *YEAR <dur1, tmp1...durn, tmpn fq1(1), fdt1(1), ti1(1), rt1(1), pr1(1) fq2(1), fdtn(1), tin(1), rtn(2),prn(1).. fq1(m), fdt1(m), ti1(m), rt1(m), pr1(m) fq2(m), fdtn(m), tin(m), rtn(m), prn(m) Where: durm : Duration in hours, the N:th period. TmpN : Ground temperature in? C for the N:th period. fqn(m) : Load factor for node type M applicable to the N:th period. fdtn(m) : Temperature factor for node type M applicable to the N:th period. tin(m) : Inlet temperature for node type M applicable to the N:th period. rtn(m) : Change in return temperature for node type M applicable to the N:th period. prn(m) : Production cost for node type M applicable to the N:th period. Example: *YEAR Duration Ground temperature Period_0: 600 h 10 C Period_1: 3000 h 20 C Period_2: 5000 h 30 C / Node type: 1 Qfaktor DTfaktor Tinl Treturl Pris Period_0: Period_1: Period_2: / Node type: 2 Qfaktor DTfaktor Tinl Treturl Pris Period_0: Period_1: Period_2: / /

99 Time series In an external keyword-based text file, parameters can be specified in order to execute a dynamic simulation. Keywords are used to control how flow, power and supply pipe temperature vary over time. The time scale is in the range minutes to 24 hours. The calculation is executed as a series of stationary calculations in which the results of every calculation execute input data for the next calculation, overlaid with the changes indicated by the keywords for the time series. The interval between calculations is given when calculation begins (see the section Calculation module). Typically, nodes are allocated consumption type 1 and the relevant production plants are allocated node types In general, the keyword normally begins with a * which is placed in column 1 (at the far left of the row). Then comes data, always indented by at least 1 position in the row. Decimal points (.) must be used as decimal separators. This keyword is ended with the / symbol. Keyword *QFAC This keyword controls the given flow for every node type with factors. This keyword is given for every occurring node type in the calculation. Up to 14 values can be given for time and factor. This keyword is ended with /. Time is specified with decimals used to indicate part-hours. In the calculation, given factors are interpolated between given times. FORMAT: *QFAC Nodetyp Tidpunkt 1 Faktor Tidpunkt 2 Faktor... Tidpunkt i Faktor / Where: Nodetyp Node type 1 to 10 Tidpunkt Time (decimal). Faktor Decimal value by which the specified flow is to be multiplied. Example: *QFAC Type: 1 / Keyword *EFAC This keyword controls the power for every node type with factors. This keyword is given for every occurring node type in the calculation. Up to 14 values can be given for time and factor. This keyword is ended with /. Time is specified with Doc-To-Help Standard Template Calculation module's input data file 99

100 decimals used to indicate part-hours. In the calculation, given factors are interpolated between given times. FORMAT: *EFAC Type: Nodetyp Tidpunkt 1 Faktor Tidpunkt 2 Faktor... Tidpunkt i Faktor / Where: Nodetyp Node type 1 to 10 Tidpunkt Time (decimal). Faktor Decimal value by which the specified power is to be multiplied. Example: *EFAC Type: 1 / Keyword *TINL This keyword is used to control supply pipe temperature from production plants for every node type. This keyword is given for every occurring node type in the calculation. Up to 14 values can be given for time and temperature. This keyword is ended with /. Time is specified with decimals used to indicate parthours. In the calculation, given temperatures are interpolated between given times. FORMAT: *TINL Typ:Nodetyp Tidpunkt 1 Temperatur Tidpunkt 2 Temperatur... Tidpunkt i Temperatur / Where: Nodetyp Node type 1 to 10 Tidpunkt Time (decimal). Temperatur Supply pipe temperature. Example:

101 * TINL Typ: 1 / Keyword *OFAC This keyword controls production costs for every node type with factors. This keyword is given for every occurring node type in the calculation. Up to 14 values can be given for time and factor. This keyword is ended with /. Time is specified with decimals used to indicate part-hours. In the calculation, given factors are interpolated between given times. FORMAT: *OFAC Typ:Nodetyp Tidpunkt 1 Faktor Tidpunkt 2 Faktor... Tidpunkt i Faktor / Where: Nodetyp Node type 1 to 10 Tidpunkt Time (decimal). Faktor Decimal value by which the specified production cost is to be multiplied. Example: *OFAC Typ: / Keyword *OUTP This keyword is used to control the print level to the OUT file from the calculation. FORMAT: *OUTP Tidpunkt 1 Utskriftsnivå Where: Tidpunkt 2 Utskriftsnivå... Tidpunkt i Utskriftsnivå / Doc-To-Help Standard Template Calculation module's input data file 101

102 Tidpunkt Utskriftslevel Example: *OUTP Time (decimal). 0 = No printout. 1 = Summary printout only. 2 = Complete printout. / In the example, there is no printout up to A complete printout takes place between and A summary printout takes place from to No printout takes place after

103 Error messages In general, errors during calculation originate from incorrectly defined boundary conditions for the calculation. Study the keywords which give rise to the error message, and study the section on basic elements and properties. As a rule, the name of the node(s)/pipe(s) which generated the error are shown in the message. Error messages generated when the calculation module was inputting keywords are saved to a log file. This file shows row numbers for rows which generated errors. Message Action *** WARNING *** Both keywords: *FORW and *PSUP used Change input data *** WARNING *** Energy cannot be extracted from accumulator The accumulator is empty! Change in node: XX because minimum temperature has been reached. Calculation criteria *** WARNING *** Energy cannot be stored in accumulator The accumulator is empty! Change in node: XX because maximum temperature has been reached. Calculation criteria *** ERROR *** Missing default type in table Change to other Default pipe type Execution stopped due to input error. a? in the calculation formula. *** WARNING *** Heat capacity of accumulator in node: XX Change calculation criteria has been violated. *** WARNING *** Inlet temperature at node: XX on supply side Change input data cannot be calculated. *** WARNING *** Temperature specification not permitted Check data for bypass in the same node! *** WARNING *** Outlet temperature at node: XX Check boundary conditions Too many temperatures specified. *** WARNING *** Temperature at node: XX Check boundary conditions Too many temperatures specified. *** WARNING *** Temperature in pipe: XX Check boundary conditions Too many temperatures specified. *** WARNING *** Temperature in pipe: XX Change input data too many inlet temperatures specified *** WARNING *** To many producers Reduce number of production plants *** WARNING *** Too many flows specified Change input data, check that only one production plant has an unknown flow *** WARNING *** Too many temp. specified in node: XX Check boundary conditions *** Warning *** Blind end in critical route! Suppressed due to the fact that the route is circulating Doc-To-Help Standard Template Calculation module's input data file 103

104 CUBER Number of iterations exceeded Accumulator AND bypass in the same node is not allowed. Accumulator not possible with steam Ambient temperature missing. Bypass is not allowed with steam CBRKFF too many iterations The arithmetical operation caused wastage Too many loops in the model! Change input data Correct type of calculation? Enter ambient temperature Change input data Change so that pipe type? is not approved for dimensioning Criteria for optimization missing! DP is specified at both ends. Data missing Data missing Data missing for pipe XX Diameter in pipe XX is known Elevation not found External temperature missing. Flow cannot be distributed conditions Flow in pipe X-Y between X and Y unknown conditions Flow is specified in node with accumulator with unknown power. Illegal data input Illegal data input for pipe Incorrect pressure Incorrect temperature Incorrect velocity. Invalid node type! This keyword: XX unknown Length of pipe: XX unknown Correct input data for pipe dimensioning Correct input data Correct input data Correct input data for pipe dimensioning Correct input data for the pipe The pipe already has a dimension, delete dimensioning criteria for the pipe Change input data Enter ambient temperature Consequential error, check boundary Consequential error, check boundary Change input data Correct input data for pipe dimensioning Correct input data for pipe dimensioning Correct input data Correct input data Correct input data Correct input data Correct input data Pipe length missing, enter length

105 Max no. of nodes is exceeded Maximum no. of heaters exceeded. Maximum no. of valves exceeded. Minimum 1 line of text must be specified Missing data Missing data in pipe table! Missing default type in pipe table! Neither supply nor return pipe has been specified for pipe No flow in pipe the heater should be turned off. No pump in node: XX No pump in pipe No solution obtained No valve in pipe XX Node XX is not connected to pipes Node given under *ACCU does not exist Node given under *SHUNT does not exist. Node name: XX unknown! Node: is duplicated. PRSADM: Pressure cannot be distributed Pipe XX is unknown Pipe name: XX unknown! Pipe: XX is duplicated. Producer node has a bypass. That is not allowed. Contact Vitec or reduce number of nodes in the model. Reduce number of heat exchangers Reduce number of valves Header must not be empty! Correct input data Correct input data for pipe dimensioning Change input data for pipe dimensioning Change input data for pipe dimensioning Change input data Pump is defined but the node's input data is not complete Pump is defined but the pipe's input data is not complete Check boundary conditions Valve is defined but the pipe's input data is not complete Connect the node to a pipe or remove the node Change input data Correct input data Reference has been made to a node which is not defined Correct input data Check boundary conditions Reference has been made to a pipe which is not defined Reference has been made to a pipe which is not defined Correct input data Correct input data Pump in pipe X-Y cannot be placed correctly Change placement of the pump! Shunt AND bypass in the same node is not allowed. Correct input data Doc-To-Help Standard Template Calculation module's input data file 105

106 Temp. cannot be calculated Temp. cannot be distributed. Temperature change in node must not be zero. Temperature in pipe: XX is unknown The critical route is suppressed due to too many nodes. Too many accumulators Too many local dimension criteria Too many loops Too many pipes in loops Too many shunt valves. Unexpected End of Input File in the file? Unknown keyword(s) in input file! Velocity must be specified. Wrong data Wrong data (pipe end) Wrong data (supply/return pipe) Wrong input of maximum and minimum temperatures Wrong input of mean temperature Missing data (Flow Factors) Incorrect no. of data (Flow Factors) Missing data (Power Factors) Incorrect no. of data (Power Factors) Missing data (Inlet Temp.) Incorrect no. of data (Inlet Temp.) Type unknown! Missing data (Output) Incorrect no. of data (Output) Type unknown! Check boundary conditions Check boundary conditions Correct input data Check boundary conditions Critical route is too long Reduce number! Correct input data Too many loops in model! Reduce number of loops in model! Reduce number of shunts Does *STOP appear in the right place Check input data. Unknown keyword! Correct input data for pipe dimensioning Change input data for pipe dimensioning Check data for heat exchanger Check data for heat exchanger Change input data Change input data Correct file licheat.cf1 Correct file licheat.cf1 Correct file licheat.cf1 Correct file licheat.cf1 Correct file licheat.cf1 Correct file licheat.cf1 Correct file licheat.cf1 Correct file licheat.cf1 Correct file licheat.cf1 Correct file licheat.cf1

107 Missing data (Prices) Incorrect no. of data (Prices) No data in Cf1 file CF1 file missing! Dynamic temperatures missing. They must be in the CF1 file. Correct file licheat.cf1 Correct file licheat.cf1 Correct file licheat.cf1 No CF1 file specified Correct in file licheat.cf1 Doc-To-Help Standard Template Calculation module's input data file 107

108 Mathematical and physical basics Calculation procedure Input data All data needed for the calculation is described in the input data file. This file is created from the model database in NetSim or directly by the user using a text editor. When carrying out calculation using correct input data, the program will undergo the following phases: Pressure The input data file is input. If errors occur during the input procedure, the error messages will be displayed on screen, as well as in a log file with the file extension CHK. Input data is checked on the basis of several different criteria. The ring connections in the pipe network are registered and the foundation for the iterative calculation procedure is optimised. The hydraulic and thermal solutions are found by means of an iterative procedure. Results from the calculation are written to the results files. When the flow is known as all points, the pressure loss depending on friction can be calculated. The pressure loss as a consequence of friction is calculated using the following formula: P 2 v L D K K D g z d z If there is an individual pressure loss in the pipe, this is calculated as follows: P 2 v Where: ΔP = Pressure [Pa ρ = Density [kg/m³ L = Pipe length [m 2 u

109 λ = Friction factor [ - D = Internal diameter of pipe [m v = Flow rate [m/s g = Gravitation constant [m/s² z d = Level downstream [m/s z u = Level upstream [m/s ξ = Individual pressure loss coefficient K1 = Calibration factor 1 K2 = Calibration factor 2 [ m -1 The total pressure loss is the sum of pressure loss due to friction and individual pressure losses. The friction factor is calculated on the basis of the Colebrook and White formula: 1 4 log D Re Where: D v Re k = Roughness in the pipe [m Re = Reynolds number [ - µ = Viscosity [kg/(ms) D = Internal diameter of pipe [m For small Reynolds numbers (< 2300), the friction factor is calculated as: 16 Re If a valve or pump is placed at the end of the pipe, this is incorporated in the pressure loss calculation. The pressure loss or pressure increase is added directly to the pressure at the pipe end. Temperature When the flow throughout the entire network is known, the temperature in the network can be calculated. The cooling at a consumer can be described as follows if the heat power is known: E T Q C P Where: E = given heat power [W C P = thermal capacitivity of the water [J/kg/C Q = mass flow [kg/s The outlet temperature in a pipe is calculated on the basis of the following expression: Doc-To-Help Standard Template Mathematical and physical basics 109

110 T d Where: M K T Ch K C Q P P U g zd zu M C L M e K K L K T Where: C h = total heat transfer coefficient [W/m/C C P = 4190 [J/kg/C Y Valves and pumps A pressure change can be specified at either the upstream or the downstream end of a pipe. These changes can be described as fixed pressure drops, fixed pressure increases or as a function of the mass flow in the pipe. Only a valve or a pump can be specified in a pipe. For a pump, the current pressure is calculated on the basis of the expression below: P A 2 B Q Where: A, B are constants determined through interpolation between relevant reference values (ΔQ,Q) in the pump characteristic. Q = mass flow in the pipe [kg/s η = efficiency of pump For valves, the pressure reduction is calculated according to the following formula: 6 P Q 2 K v Where: Q = Flow [l/s K v = Valve coefficient [t/h/ mwc Bypasses Bypasses can be placed in nodes. The mass flow in the bypass is calculated using the following expression: D o 4 Where: 2 2 P 3.8 ΔP = differential pressure. The bypass is viewed as an individual pressure loss with a pressure loss coefficient of 3.8 and a known pressure loss corresponding to the differential pressure in the node.

111 Density and viscosity The program calculates the current density and viscosity, corrected for pressure and temperature as per the following expression: Densitet e 0 Viskositet Where: 0 e PP0 K e T T0 T T0 P = Absolute pressure [N/m2 P 0 = Reference pressure = x 106 [N/m2 K = Bulk module = 2.1 x 109 [N/m2 T = Current temperature [K T 0 = Reference temperature [ K ρ 0 = Reference density = 988 [kg/m3 Ґ 0 = Reference viscosity = [kg/s/m) α = Constant = [K-1 β = Constant = x 10-4 Keyword *COOL introduces constants to the program which are suitable for the temperature range < 20 C. Steam module The steam module requires steam throughout the entire supply pipe system and liquid throughout the entire return pipe system. Latent heat and compressibility have been taken into account in the calculation. The thermodynamic properties are calculated on the basis of the equation below: p, t P M Z R T Where: P is pressure M molar weight of the water Z supercompressibility R universal gas constant T absolute temperature Compressibility is calculated as a function of pressure and temperature using the SRK equation: Z 3 a 2 P, T Z bp, T Z cp, T 0 Where a, b and c are a function of pressure and temperature only. Thermal capacitivity is calculated using: C p A B T C T 2 D T 3 Where: A = B = C = x 10-3 D = -0.2 x 10-6 Doc-To-Help Standard Template Mathematical and physical basics 111

112 Shunt valve A shunt valve is placed in a node where water should be able to pass from the return pipe to the supply pipe. The supply pipe temperature is used to regulate the flow, i.e. the flow through the valve is selected so as to meet supply requirements. The size of the shunt flow, Qs, is calculated from: i Q T i i i Q T Q Q i s s r T * Where: T* is the required supply temperature. T r is the return temperature. Q i is the supply pipe flow in the node. Note that there are cases in which the requested supply pipe temperature cannot be reached. The programs issues warnings in these cases. Accumulators Accumulators are handled as follows: If the flow is positive in the node with the accumulator (power is stored in the accumulator), the temperature in the return part of the network, Tr, will be the same as the minimum temperature for the accumulator, Tmin. If the flow is negative in the node with the accumulator (power is recovered from the accumulator), the temperature in the supply pipe part of the network, Tf, will be equal to the max. temperature for the accumulator, Tmax. If the accumulator power is known and the accumulator's average temperature falls below Tmin, it will not be possible to recover energy from the accumulator in the next time step. Similarly, if the temperature is above Tmax, it will not be possible to store any energy in the accumulator in the following time step.

113 Pipe types Examples of pipe types Below are some suggestions for designations and properties for common pipe types in district heating networks. The type? with an internal diameter of 0 mm is used for pipes which are to be dimensioned. A roughness of 0.1 mm means a pressure loss which includes the normal losses occurring at bends and branches in district heating networks. It is necessary to consider using smoother pipes for long transitional pipes. Doc-To-Help Standard Template Pipe types 113

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