Design optimization of central processing unit (CPU) casing

Transcription

1 Design optimization of central processing unit (CPU) casing Khushairy Bin Ahmad Nawawi School of Manufacturing Engineering Universiti Malaysia Perlis, Abstract Designing computer casing should have capability that can transfer heat from inside to outside. Temperature inside computer casing should reduce when reach outside the computer casing. Modeling and analysis of a thermal inside computer casing is presented in this project. Optimization is implemented with the goal to reduce the internal temperature. Two proposals of optimal design are simulated employing the FEM software which is ANSYS. Those proposals differ in shape but same load and material. Some especial techniques are used to build the two-dimensional model and to finish the FEM analysis. The thermal characteristics of the computer casing are then investigated in model analysis based on the thermal steady state theory. The result is acquired by comparing the model parameters of those in different proposals. A preferable model takes also the simple design into account. The passive cooling proved can cooled computer with correct in structure design. Thermal analysis also make easy with ANSYS during analyze process done. Keywords Computer casing, heat transfer, Ansys, computer cooling, thermal 1. Introduction Computer casing is the place to all the computer components. The motherboard, the graphic card, the hard drive, the CD drive, the floppy drive and the power supply are inside a computer casing. Computer desktop casing generally has trays for the CD/DVD drives, floppy drives and hard drives. There is also a place for the power supply and the on-switch cables which usually come with the case. These are connected with the buttons at the front and these connect to pins on the motherboard. When placing hard drive or CD drive into the motherboard should have correct space between them as possible. If they are too close there is more chance they will overheat. A good computer case also has a few fans circulating the perimeter of the case. These either connect to the motherboard or to the power supply and they keep the computer much cooler [1]. A few years ago, desktop computer were just plain and just use at home. Nowadays, with computer casing comes with front USB, card reader, fire wire or ports. Desktop computer need high graphic performance, fast in data processing and capable work with many software in work station extremely[3]. Therefore, new design of Central Processing Unit (CPU) casing hope can give advantages for the needs. As everyone knows, a good computer casing should have functionality and aesthetics. Most end users would choose a computer casing by its outside appearance and price. Most computer experts would choose by inside functionality and brands. In the past few years the quality of most cases that would be considered to have aesthetically pleasing have dramatically increased in quality. Quality use to be a major problem, however over the years it has gotten a lot better. The quality of the case is determined by material, thickness or material, and sturdiness of the machine. However, if want a cheap case it cannot expect the quality of an expensive case. So, simply put depending on how much to put into the case determines the quality of it [3]. Cooling is one of the most important things to look for in a case. With the new graphics cards and high rpm hard drives heat can become an issue in the wrong case. The first thing that needs to do is decide on what going to put in the case. Depending on the motherboard chosen will changes which case that needed. A lot of motherboards only support certain motherboards. One major thing to look for is the possibility to add a fan if cooling becomes an issue[11]. Also depending on where the computer is stored and what the ambient temperature is around the machine. If the machine is in a cabinet it might be necessary to have enough fans to keep a constant flow of air. However if the machine sits in the open it could be possible to have less fans and still have adequate cooling. The cooler a machine runs the more stable the machine operates. Heat can destroy hard drives, power supplies, and processors so it is extremely important to make sure these remain cool at all times[4]. A roomy case that is easy to access and does not have sharp edges is often on a PC technician's wish list. To be fair, the manufacturers are doing much better than before in removing the sharp edges. The case should ease to use that technicians do not have particular problems to work with. Some type of person like and always change something in their system like graphic card, mother board and so on. With suitable design of case, it can save time features and really Passive cooling was one of method for cool inside desktop

2 pc. Heat can transfer through computer casing to reduce temperature inside. It is to design computer casing that can transfer heat from inside to outside[15]. Temperature inside computer casing should reduce when reach outside the computer casing. The of this study are an improvement casing should be satisfied with aspects as mentioned under improve cooling in desktop chasis as result in analysis and study. While design a new CPU casing with simple structure was to complete the objective. No. Parameter Measurement (mm) 1 Casing Height Casing Length Casing Width Casing Thickness 0.5 Table 1: Parameter of modeling computer casing in analysis. The scope of work is to study Suitable cooling method and technologies. It is to ensure improvement in cooling was archive. Using ASYS one of FEM method to analyze the thermal inside CPU casing. 2. Methodology of project This experiment method will be conducted using the work station Z400 Computer. Using ANSYS will do thermal analysis a steady-state thermal analysis. It can determine the temperature distribution and other thermal quantities under steady-state loading conditions[4]. A steady-state loading condition is a situation where heat storage effects varying over a period of time can be ignored. In order to achieve the objective of the research, the factor selections of experimental equipments play a big role. Selections of experimental equipments are based on the previous research. Deployed Pc Wizard to determine temperature and internal computer hardware. ANSYS 11 is to analyze by assess the data and display the result of heat transfer study. Desktop computer internal hardware specification was determined by using PC wizard 2010 software. By installing this software in the modeling desktop it can easily identify type of hardware inside the computer, driver, operating system, voltage, temperature and fan. Figure 2: ASYS 2D view Modeling Computer To build the model, specify the job name and a title for the analysis. Then, use the ANSYS preprocessor (PREP7) to define the element types, element real constants, material properties, and the model geometry. The Casing computer was design with Catia V5. It was draw with actual dimension to ensure success and avoid error during run the analysis with ANSYS. Using catia V5 it will make easy to import the drawing into ANSYS Experiment Procedure Figure 3: Meshing modeling computer Figure 1: 3D view modeling computer Specify a Smart Size of 4. This will allow a slightly finer mesh than the default and yet the resulting number of

3 elements will be within the ANSYS ED program limits for the maximum number of elements. After meshing no of nodes are 54. Meshing process continue with refining the Power supply unit area. After refine the number of node raise to 859. Boundary Condition was apply between internal casing and ambient. Apply convection loads on the exposed boundary lines to ensure heat inside casing transfer to the ambient. Loads applied to solid modeling entities are automatically transferred to the finite element model during solution. The simulation results are plotted and presented in figures and graphs. The figures are generated via ANSYS report generator which uses a color scale to resolve the difference between locations of high temperature to that of low temperature. Generally, blue color indicates low temperature and the color gradually increases to red which implies that the location exhibits the highest temperature. Figure 5: Colour scale in ANSYS Ambient 25 C 70 C 47 C 45 C 3.2. Result of thermal analysis of the first design From the ANSYS analysis, the results visualize the temperature distribution throughout the First design over than 4 hour span. The contour show red as the highest temperature and dark blue was the low temperature. The animation from ANSYS analysis also shows temperature distribution from the computer hardware as a source of heat to outside the casing (ambient). Power supply unit was the highest temperature followed by hard disk and graphic processing unit. Figure 4: Hardware and temperature load No. Hardware Temperature 1 Power suppy unit 70 C 2 Hard Disk 47 C 3 Graphic Processing Unit 45 C 4 Ambient 25 C The first design was analyze to see how fast internal hardware cooled through the computer casing in 4 hours. Without change hardware component, location every contribute hardware, a new design computer casing should satisfied in cooling inside the computer. In this first design analysis, the result will be a reference to produce a new design computer casing that can improve cooling inside computer. Table.2: Computer hardware and temperature contribution in analysis 3. RESULT AND DISCUSSION 3.1 Results After conducting the analysis and collect the result, then in this chapter, the results during each type of analysis are discussed. There are two thermal analysis results as follow i. Result of thermal analysis of the first design. ii. Result of thermal analysis of the second design. Figure 6: Contour Casing 1Frame 1 (1)

4 Figure 7: Contour Casing 1Frame 24 Figure 8 : Contour Casing 2 Frame 1 Result casing 1show the temperature inside the computer casing 1with time distribution in 4 hours. The result show internal temperature around power supply unit with C. At the end, temperature inside computer casing 1then drop until C. Figure 9: Contour Casing 2 Frame 24 Graph 1: The graph temperature versus time casing 1 (hr) The graph 1 is a graph temperature ( o C) versus time (hr) for casing 1. From this graph it appears from the temperature different following the time. Temperature starts at C and dramatically drop until C. Then, temperatures slowly drop until C. 3.3 Result of thermal analysis of the second design Result show the temperature inside the computer casing 2 with time distribution in 4 hours. The result show internal temperature with C. Temperature inside computer casing 2 then drop until C. Graph 2: The graph temperature Verses Time Casing 2

5 3.4 Discussion From the analysis, there is different temperature between design 1 and design 2. This analysis want to show the temperature drop accordingly theory from hot to cool temperature. This temperature comparison was taken during 4 hour prediction time in the analysis. Mostly, the highest temperature inside the computer casing contributed by power supply unit. From the 70 o C it cool until 36 o C 40 o C inside the computer casing. Red colour contour show the highest point of temperature inside. According theory heat will transferred from high temperature to the low temperature. Power supply temperature (70 o C) drop drastically which almost 30 o C inside computer casing (40 o C). A big different temperature with ambient temperature (25 o C ) causes the phenomena. Comparison temperature inside the computer case 1 and case 2 with time distribution in 4 hours. The result show internal temperature with case 1 much higher than temperature case2. Computer case 2 designed to expose internal casing at the top of the casing. This design makes temperature that produced by internal hardware quickly drop compare with the design computer case 1. Graph 3: The graph comparison cooling between case 1 and case 2 The graph 4.3 is a comparison graph temperature ( o C) versus time (hr) for casing 1 and casing 2. According a graph, temperature casing 2 start much low start temperature compare with casing 1. As explain before, the casing design 2 show temperature dramatically drop until o C. Then, temperatures slowly drop until C. The computer design 2 was improve the cooling inside computer casing. The formulate that can show as: Casing 1 (reference) Max. temp. Min. temp. = C C = C Casing 2 Max. temp. Min. temp. = C C = C Therefore, C C = 0.21 x 100% C 21 % improvement in cooling 4. Conclusion Collectively, these studies have managed to achieve the objective. Base on, the result and discussion of all two experiment carried out. The goal of this project is to determine whether new design computer casing that propose can improve cooling than the previous computer casing design. In this study, heat transfer in conduction and convection is use when parameters such as material type, thermal conductivity and hardware temperature are setup. The study was conducted using a common computer casing model which is widely used in the work station, computer casing was made by steel was investigated in this study. Although computer casing can use others material such aluminium that know good in thermal conductivity, this analysis and study more prefer steel as a computer casing because it is cost saving and heat transfer performance can matched with others material also not better. A steady-state thermal analysis calculates the effects of steady thermal loads on a system or component. The main purpose is to determine the temperature effect and observe temperature distribution inside computer casing. Temperature was the factor that will influence how fast computer will be cooled. The results show new design computer casing improved 21% cooling from the previous design. Correct design computer casing ventilation and Computer hardware position is the most influential factor contributing to temperature cooled down. There are many factors that affect a package in cooling semiconductor. Hopefully by completing this project, many unknown interactions between factors or even the most influential factor contributing to the passive cooling can be indentified before designing a new computer casing. Simulation using ANSYS will give the user a good knowledge as a based on what to be expected before running a certain process. 5. References [1] Tzou, G. J. Tsao, C. C.Lin, Y. C.Improvement in the thermal conductivity of aluminum substrate for the desktop PC Central Processing Unit (CPU) by the Taguchi method. [2] Boukhanouf R, Haddad A, A CFD analysis of an electronics cooling enclosure for application in telecommunication systems. [3] Chan, Mark Aaron Yap, Christopher R.Ng, Kim Choon, Modeling and testing of an advanced compact two-phase cooler for electronics cooling. [4] Elnaggar Mohamed H. A., Abdullah M. Z., Abdul Mujeebu M., Experimental analysis and FEM simulation of finned U-shape multi heat pipe for desktop PC cooling.

6 [5] Pashah, S. Arif, Zubair, Syed M. Mustafa, M. T., The effect of coating and interface resistance on thermal performance of variable thickness annular composite fins. [6] Moukalled, F.Verma, S.Darwish, M.The use of CFD for predicting and optimizing the performance of air conditioning equipment. [7] Srinivasan, V., Ghosh, K., Mittal, R. Heat transfer, a review of 2004 literature. [8] Dr. D.S Kumar, Heat and mass transfer, six edition [9] Jiang, Pei-Xue, Zhao, Chen-Ru, Shi, Run-Fu. Chen, Yang, Ambrosini, Walter, Experimental and numerical study of convection heat transfer of CO2 at super-critical pressures during cooling in small vertical tube, 2009 [10] Webb RL. Next generation devices for electronic cooling with heat rejection to air. ASME J Heat Transfer 2005;127:2 10. [11] Chang Y-W, Cheng C-H, Wang J-C, Chen S-L. Heat pipe for cooling of electronic equipment. Energy Convers Manage 2008;49: [12] Groll M, Schneider M, Sartre V, Zaghdoudib MC, Lallemand M. Thermal control of electronic equipment by heat pipes. Revue Générale de Thermique 1998;37(5): [13] Vasiliev LL. Heat pipe in modern heat exchangers. Appl Thermal Eng 2005;25:1 19. [14] Shah RK, London AL. Laminar flow forced convection in ducts. NewYork: Academic Press; p [15] Cengel YunusA. Heat transfer. 2nd ed. New York: McGraw; p. 466 and 468.