Numerical Research On Heat Lamination Height To Displacement Ventilation System

According to the working principle of displacement ventilation system and domestic research,this paper studies the thermal stratification height of displacement ventilation system. There is no thoroughly rounded theory about displacement ventilation system in our country at present and our research begins recently.The study work of this paper will be useful for further optimization design of displacement ventilation system.This dissertation includes five parts.The first part introduces the development of the displacement ventilation and the background of research in domestic and oversea.In the second part,it gives working principle of displacement ventilation system and it's advantages to the mixture ventilation. The study also gives a series of indexes to evaluate displacement ventilation system and specifies air supply terminal device and so on.It is needed to simulate and analyse the velocity field,temperature field and distribution of flow field.This is the third part.The forth part specifies the simulative method for thermal stratification of displacement ventilation system.It gives some factors affecting thermal stratification height such as inlet temperature, inlet velocity,heat transfer of wall body,distance of heat source and so on. In the last part, an experiential formula for nondimensional thermal stratification height is obtained ,which includes inlet temperature T, inlet velocity V,heat transfer of the wall body Q and the distance of heat source L.In order to obtain a more realistic result,theκ?εmodel is used to simulate the airflow and the buoyancy item is treated by Boussinesq hypothesis.The paper investigates the flow field of the displacement ventilation in an office by a numerical method. The results of calculation are useful for optimization design of system.