Study On Indoor Thermal Environment Of Radiant Ceiling Heating And Optimization Of Air Distribution

Compared with traditional convection air conditioners,radiant air conditioners can improve human comfort and save energy.At present,for the summer working conditions,most of the radiant cooling roof systems are used.For buildings that require cooling in summer and heating in winter,if radiant cold ceilings are used in summer and radiant floors or radiators are used for heating in winter,the air conditioning system is complicated and costly.According to existing research,it is found that the radiant ceiling has weak heating capacity compared with other radiant heatingsystem,less convection heat exchange,and inconsistency with the human body’s "head-cooling and foot-warming" requirements.Therefore,this article proposes three airflow organization methods: fan coil side blowing,ceiling fan blowing reversely,ceiling fan blowing.Explore the influence of these three air distribution methods on radiant ceiling heating.This article first introduces the radiant air conditioning system and theoretically analyzes the heat exchange between the radiant ceiling and the surrounding environment.The evaluation indexes of indoor thermal environment of radiant air-conditioning system are summarized.Taking an experimental room in Changsha as the research object,the three air distribution methods combined with the radiant ceiling heating system were tested.The results show that all three airflow organization methods can increase the wall temperature of the enclosure structure,increase the average air temperature of the room,and optimize the indoor thermal environment.The indoor operating temperature of the experimental test of the fan coil side blowing and the ceiling fan blowing reversely is increased,the vertical temperature difference is reduced,and the unsatisfactory rate of the calculated vertical temperature difference is reduced.The indoor operating temperature is reduced under the test conditions of the ceiling fan blow mode,and the vertical temperature difference and dissatisfaction rate increase.After that,using the CFD simulation method,a numerical model was established for the experimental test room,and four working conditions were selected for model verification.The result shows that the simulated value is consistent with the measured value.The relative errors of the four operating conditions are 3.96%,2.54%,2.07%,3.47%,and the root mean square errors are 0.81,0.60℃,0.58℃,0.95℃,respectively.The model is reliable.Finally,the Z=1.7 section is selected to analyze the indoor air velocity distribution under the three airflow organization modes.Finally,based on the verified CFD model,an extended simulation study was carried out on the three airflow organization forms,fan coil side blowing,ceiling fan blowing reversely,and the blowing of the ceiling fan.Calculate PMV and PPD of indoor personnel,and the relationship between the different air velocity and various thermal comfort indexes of the three airflow organization methods is fitted.Through overall and partial evaluation,it is concluded that when the air velocity of fan coil side blowing is 1m/s、1.5m/s、2m/s,the air velocity of ceiling fan blowing reversely is 0.5m/s and the air velocity of ceiling fan blowing is 0.5m/s,the comfort degree of indoor environment is class I.And it provides a reference for the radiant ceiling to couple air a different airflow organization methods for winter heating.