Modeling of Complex Air Diffuser for CFD Simulation

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The cold air supply system, in which temperature difference between the supply and the return air is higher than usual system, has been applied to the office buildings. The cold air supply system has been mainly studied by experiments and field measurements. Few CFD simulations was applied to that system because it was difficult to reproduced the complex air flow around the air diffuser in the CFD. However the P.V.Method can simulate the airflow around the air diffuser with coarse grids system. In the previous paper, it was reported that CFD simulation using P.V.method showed good agreement with experimental results for Ceiling Air Diffuser.In this research, CFD using the unstructured grid system were conducted to obtain airflow data around the high diffusion type ceiling air diffuser as boundary conditions of coarse grid CFD. In addition, the coarse grid CFD with P.V.method using the airflow data around the diffuser was compared to the result of the unstructured CFD simulations under … More the isothermal condition. The result of the coarse grid CFD with P.V.method showed good agreement with the one simulated using unstructured grid system. The local Archimedes number is very small at virtual box surfaces and the isothermal airflow data can be applied to the non-isothermal simulation as the boundary condition. Furthermore, the measurements were carried out under the non-isothermal condition in the test room and compared to the non-isothermal coarse grid CFD using P.V.method with the isothermal air flow data around the diffuser.The under floor air conditioning system has been applied many office buildings in Japan. When the under floor air conditioning system is installed in office rooms, the occupied area can be effectively controlled in comfortable condition. The vertical temperature difference in the under floor supply system is much larger then in general ceiling supply system. Therefore the control method of the under floor system is important and the position of thermal sensors should be determined carefully. The air distribution in the room installed with the under floor system are studied by the experiment and CFD. The steady states of room temperature are examined and thermal stratification in the room is observed with both the experiment and CFD. Thus, the transient condition is investigated with the CFD in which the heat capacity of walls and floors materials etc is included. The results of the transient CFD are compared with the experimental results. Less