臺灣博碩士論文加值系統

This research uses a CFD simulation software to study the temperature and velocity characteristics in a room equipped with an Underfloor air distribution (UFAD) system. The objective is to establish a simulation model that considers the influence of the ambient air conditions and properly predicts the flow and temperature fields in a full-scale room. In the first part, different boundary assumptions are introduced and their influences on the temperature profiles are analyzed. The effects of the governing parameters, such as momentum and buoyancy flux, are discussed and compared to the previous studies. The CFD model is validated by using experimental data measured in a full-scale room. It is concluded that non-adiabatic wall conditions play a significant role in the correct prediction of the air stratification. The research shows that the characteristics of the UFAD system are represented accurately by the CFD model that is employing the constant wall temperature boundary condition. In the second part, the interaction of the temperature and velocity profiles is studied at several locations. The two profiles clearly change with different distance from the supply diffuser. Three regions based on the characteristics of the temperature and velocity profiles are defined, and the two profiles are strongly interdependent. The profiles show a clear correlation between the velocity and temperature distribution in the regions. Region one is mainly dominated by the supply jet flow from the diffuser, and Region two is influenced by the spreading gravity current of conditioned cool air. In Region three, there is no clear level which determines the stratification layer in the temperature and velocity profiles, and the temperature profile maintains a nearly constant gradient along the room height. Thus, Region two limits the distance until which a two-layer stratification is observed in the room.

This research uses a CFD simulation software to study the temperature and velocity characteristics in a room equipped with an Underfloor air distribution (UFAD) system. The objective is to establish a simulation model that considers the influence of the ambient air conditions and properly predicts the flow and temperature fields in a full-scale room. In the first part, different boundary assumptions are introduced and their influences on the temperature profiles are analyzed. The effects of the governing parameters, such as momentum and buoyancy flux, are discussed and compared to the previous studies. The CFD model is validated by using experimental data measured in a full-scale room. It is concluded that non-adiabatic wall conditions play a significant role in the correct prediction of the air stratification. The research shows that the characteristics of the UFAD system are represented accurately by the CFD model that is employing the constant wall temperature boundary condition. In the second part, the interaction of the temperature and velocity profiles is studied at several locations. The two profiles clearly change with different distance from the supply diffuser. Three regions based on the characteristics of the temperature and velocity profiles are defined, and the two profiles are strongly interdependent. The profiles show a clear correlation between the velocity and temperature distribution in the regions. Region one is mainly dominated by the supply jet flow from the diffuser, and Region two is influenced by the spreading gravity current of conditioned cool air. In Region three, there is no clear level which determines the stratification layer in the temperature and velocity profiles, and the temperature profile maintains a nearly constant gradient along the room height. Thus, Region two limits the distance until which a two-layer stratification is observed in the room.

1 Introduction
2 Simulation model
3 Validating the simulation model
4 Air flow and temperature characteristics
5 Conclusion

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