Application of CFD in C/R Design

1. Application of CFD in C/R Design PERFORMANCE COMPARSION OFAXIAL FAN AND FAN-FILTER UNIT(FFU)TYPE CLEAN ROOMS BY CFD <主講人> 胡石政

2. Outline • INTRODUCTION • NUMERICAL METHODS • Airflow model • Boundary conditions • RESULTS AND DISCUSSION • CONCLUSIONS

3. INTRODUCTION • Recirculation systems currently account for about fifteen percent of the electrical consumption of a fab. • There are several types of air recirculation systems available for uni-directional clean rooms in practice including： a. the axial fan type system b. the fan-filter unit (FFU) type system c. the recirculation air-conditioner type system

4. axial fan type system

5. fan-filter unit (FFU) type system

6. recirculation air-conditioner type system

7. Schematic diagram of the FFU

8. an axial fan’s performance curves

9. a FFU’s performance curves

10. non-uniformity of ULPA filter face velocity (NU) ratio of standard deviation of the velocity to the mean face velocity

11. Airflow model div (V-,eff grad) = S • : air density (kg/m3) ,eff : the effective diffusion coefficient (N.s/m2 ) V:the air velocity vector (m/s) S: source term of the general fluid property  : any one of 1,u,v,w,k

12. The Case Setup Subscript： r-return air chambers-supply air chamberc-Dry coil p-Perforated floor f-ULPA filters-Silencer & System effect of the axial fan

13. deflection angle (α) • Airflow deflection angle, α, in the working zone is affected by • ULPA face velocity non-uniformity • flow resistance across the perforated floors • clean room height • To adjust the α value by increasing the airflow resistance of the perforated floor may create too much resistance to the FFU resulting insufficient system flow rate

14. Comparison of system performance for axial fan type clean room and FFU type clean room predicted power consumption per unit air quantity

15. Comparison of total annual charge for axial fan type clean room and FFU type clean room

16. Comparison of the predicted and experimental data

17. Velocity Vectors (m/s) • Axial Fan system • FFU system the FFU type system splits the system total flow volume to individual FFUs, the highest field velocity value of FFU system is lower than that of axial fan system.

18. Pressure distribution (Pa) • Axial Fan system • FFU system From the viewpoint of sealing work and filter installation/exchange, the FFU system is easier than that of axial fan system because the axial fan system exhibits a positive pressure in the SAP while the FFU system shows a negative one

19. CONCLUSIONS • For the first time, the fan performance curve was successfully input to the CFD model to investigate the operational characteristics of both the axial type clean room and the fan-filter unit (FFU) type clean room. The feasibility of such connection was verified and the predicted results were promising. • The performance of the FFU system examined is superior to that of the axial fan system based on the non-uniformity of the ULPA filter face velocity, deflection angle of airflow in the working zone, and energy consumption. However, more studies are required to understand the performance of these two systems to include the initial cost, the maintenance cost, the flexibility of space management etc.

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