CFD simulation of transient cooling in a typical Hong Kong office.

The transient performance of displacement ventilation has rarely been studied though many researches have been done on the area.. Due to the importance to the analysis and design of an air conditioning system, the unsteady histories of displacement ventilation of a typical office in Hong Kong is simulated numerically with a validated computational fluid dynamics (CFD) model. Solar heat gain is introduced from the glass wall. Turbulent flow with thermal convection is considered. As a preliminary research, the heat capacity of the walls, occupants and machines is ignored. With the reasonable air flux determined by steady state simulated, the transient regime were started with uniform initial temperature and zero velocities profile. The numerical simulation illustrated the evolution of stratified temperature profiles in the office: the cooler fresh air supplied spread horizontally first, then grew along the vertical direction gradually. The simulation also revealed the development of the thermal plum produced by hot walls and objects. Hence the study helps to understand the formation of the initial velocity and temperature fields.