Self-Cultivation System

Transcription

1 Development of a Microorganism Incubator using CFD Simulations

2 Self-Cultivation System A comfortable mixing incubator to grow microorganism for agricultural, animal husbandry and ocean agriculture industries Need to determine the impeller size, rotating speed and temperature of the whole mixing tank to provide optimized environment for microorganism It has been improved to achieve compact size, higher efficiency and lower power consumption. CFD simulations have been performed to study the flow characteristics and to expect the optimized flow condition for microorganism. 2

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4 Incubator (Mixing Tank) Baffle Heating Pipe Air Supplier Oxygen saturation is not considered. Heating effect is not considered yet in this study. Electro- Magnetic Motor Impeller Prototype of a Self-Cultivation System 4

5 Specifications 100 L - Geom L Geom L Impeller Type Turbine (6 blades) Turbine (6 blades) Axial (3 blades) Diameter of Incubator (D) 500 mm 500 mm 700 mm Height of Incubator 1.3D 1.34D 1.086D Water Height D D 0.77D Impeller Diameter 0.336D 0.336D 0.247D Impeller Height 0.122D 0.122D 0.151D RPM Baffle Height 0.64D 0.64D 0.57D Baffle Location (Tank Bottom to Baffle bottom) 0.36D 0.36D 0.26D Number of Baffles

6 100 L - Geom 1 (Round Bottom - standard Type) 100 L - Geom 2 (Inclined Bottom) 6

7 CFD tools : ANSYS FLUENT 14.0 Basic Solution : Time-dependent Working fluid : Liquid water + Air Number of Elements : 2 mil for 100 L, 5 mil for 200 L Multiphase model : Volume of Fluid (VOF), Explicit Geo-Reconstruction Turbulence : standard k-εmodel Moving frame : MRF (Multiple Reference Frame) Pressure-Velocity coupling : PISO Discretization scheme : Green-Gauss node Based, 2 nd order accuracy Time step : sec Number of time steps : 8000 Convergence Criteria : continuity ~ 10-4, velocity, turbulence ~10-4 Parallel computation using 16 processors 7

8 GAIA (IBM p6) System (at KISTI) Rpeak 30.7 TFLOPS Nodes (#) 24 Processor POWER 6 (5GHz) CPU (#) 1,536 Memory 8,704 GB Storage 336 TB Operation started Oct

9 Geom 1 Geom 2 Radial and axial velocity components exist as well as circumferential one. Due to the radial and axial velocity components, the fluid mixing is working effectively. 9

10 Geom 1 Geom 2 Velocity magnitude of Geom 1 is generally greater than that of case 2. Momentum generated from impeller for Geom 2 is not transported to the entire region as much as Geom 1 due to the bottom shape. 10

11 Geom 1 Geom 2 Due to the difference of bottom geometry, fluid momentum of Geom 2 is not transported effectively compared to that of Geom 1. 11

12 Geom 1 Geom 2 It is obviously seen that circumferential motion of fluid of Geom 1 still exists in the middle section of baffle, but at Geom 2, it is nearly disappeared. 12

13 Geom 1 Geom 2 Due to the strong circumferential fluid motion of Geom 1 compared to Geom 2, recirculation occurs behind of baffle at the case of Geom 1. However, at Geom 2, there is no flow circulation because the component of circumferential fluid velocity is much less than other components-axial and radial ones. 13

14 Geom 1 Geom 2 Circumferential motion of fluid from Impeller is still transported to near top surface of fluid in the case of Geom 1. It is hard to observe the rotational fluid motion at Geom 2 and velocity magnitude is low. 14

15 Geom 1 Geom 2 Due to the strong circumferential fluid motion of Geom 1 compared to Geom 2, recirculation occurs behind of baffle at the case of Geom 1. However, at Geom 2, there is no flow circulation because the component of circumferential fluid velocity is much less than other components-axial and radial ones. 15

16 Geom 1 Geom 2 There are all circumferential, axial and radial components of fluid motion generated from Impeller at Geom 1. (effective mixing expected.) 16

17 The magnitude of fluid velocity starts to be steady-state from bottom to top. At about 8 sec, fluid motion was measured to be stabilized. Difficult to measure flow characteristics by experiment.(no experiment experts and equipments) Although the real prototype is slightly different from 3D modeling for CFD simulation, CFD also predicts that fluid flow reaches steady-state at about 8 sec. To get better pattern of time dependence, it needs to run more time step. 17

18 1 Sec 7 Sec 200 L tank equipped with the axial type impeller is also testing. (Numerical study is also running as well.) In the interior region of fluid, there is heating pipe placed. (Energy equation will be included in the numerical simulations.) 18

19 1. Numerical studies have been done for fluid flows in mixing incubator to grow microorganisms. 2. Two cases with different bottom shapes are studied. 3. Fluid motions including circumferential, axial and radial components are well balanced in Geom 1, conventional type of mixing tank. 4. Due to the loss of momentum near the edge of bottom at Geom 2, fluid flows are not strong as much as Geom Mixing does not effectively work at Geom Fluid flow at Geom 1 reached the steady state after about 7 sec, which is nearly the same as measurement. 7. Numerical and experimental studies need to be further performed for various types of bottom shape, impeller and positions of baffles. 19

20 1. Performance of Geom 2 will be examined by experiments for prototype. 2. Numerical studies will consider heat transfer generated from heat pipe. 3. Flow pattern of 200 L with axial type impeller will be further studied. 4. More accurate measurements for flow behaviors and comparing with CFD will be carried out. 20

21 Thank you. Questions? 21

22 Additional Supplements 22

23 Geom 1 Geom 2 23