Research On Indoor Thermal Environment In An Office With Hybrid System Of Chilled Panel And Displacement Ventilation

Along with the development of economy and the enhancement of people living standard, energy consumption of air-conditioning increases unceasingly. And people become to pay more attention on thermal comfort and indoor air quality. Currently, the hybrid air-conditioning system of chilled panel and displacement ventilation is considered to be one of the economical, energy conservative, comfortable air-conditioning modes and arouses more and more research interests.Firstly, CFD simulation results based on indoor zero-equation turbulence model were validated using experimental data. Then indoor thermal environments of an office with hybrid system of chilled panel and displacement ventilation were numerically simulated under three cooling load conditions. Simulations and comparison results indicate hybrid air-conditioning pattern can achieve the best indoor thermal environment among the four kinds of air conditioning modes, such as, mixing ventilation, chilled ceiling, displacement ventilation and hybrid system of chilled panel and displacement ventilation. It shows that vertical temperature gradients in the hybrid air-conditioned room are between those attained in rooms with chilled ceiling or displacement ventilation individually. And hybrid system can achieve higher ventilation efficiency than mixing ventilation system does, while it is lower than that of displacement ventilation system. Hybrid air-conditioning mode is superior to the other three kinds of air conditioning modes in terms of thermal comfort and energy efficient, especially when cooling load increases.And then, the influences of such parameters as air supply velocity, air supply temperature, cooling panel surface temperature, etc, on indoor thermal environment with hybrid system were studied under medium cooling load condition. Indoor vertical temperature gradient, velocity field, PMV, PD, cooling capacity ratio of CC to DV, ventilation efficiency, etc were analyzed as these parameters change. Also, the effect of locations of heat sources, air inlets and chilled panels on the indoor environment was investigated. Thus, the following suggestions on cooling parameters are proposed: air supply speed should not exceed 0. 3m/s; air supply temperature should not be lower than 19 ℃; the cooling panel surface temperature should not be lower than 17℃.Indoor thermal environment of the office with hybrid system of chilled ceiling and displacement ventilation was compared with that of the office with chilled floor and displacement ventilation. Results show that the hybrid air-conditioning of chilled ceiling panel and displacement ventilation has its superiority in some aspects, and it is more proper to be used under a wider range of cooling load.