Study On Effect Mechanism Of Different Layout Methods On The Thermal Environment Of Radiative Refrigeration And Heating Room

Traditional air conditioning systems have the problems of poor thermal comfort and high energy consumption,and radiant cooling heating technology overcomes these inherently difficult drawbacks.Because of the large radiation end area,radiant heat transfer becomes the main heat transfer mode in the room,so the indoor comfort is higher.But radiant cooling and heating room thermal environment as a typical non-uniform thermal environment,the arrangement of the radiation ends directly affects the amount of cooling(heat)in the system,which indirectly affects the amount of heat dissipation of the human body,and therefore has a great influence on the indoor heat environment.The related researches focus on the energy conservation of radiant air conditioners and traditional air conditioners,as well as the comparison of indoor thermal environment.Among them,there are many studies on the traditional radiation position of the roof or the ground,less on the external factors to explain the influence of multi-wall radiation on indoor thermal environment.In the architectural design principles,creating a comfortable environment is the first principle,followed by energy-saving economic factors.Therefore,based on the heat transfer process between the analyst and the indoor environment,room and outdoor environment,this paper establishes three heat transfer models with the same radiation end arrangement(top plate M1,top plate and ground M2,roof and ground and wall M3).To study the influence of the heat gain of the room and the parameters of the indoor thermal environment,and reveal the influence mechanism on the indoor thermal environment.In this paper,the human body and the environment heat transfer model are firstly established,and the uneven distribution results of the radiation angle coefficient of the indoor personnel and the wall surface are obtained,which provides a theoretical basis for the subsequent research of the paper.The function expression of the angle coefficient between the human body and the radiation surface is fitted,the influence of room size,depth and height factors is analyzed.It is found that the fluctuation of the angle coefficient between the person and the radiation surface is the smallest when using M1,and the angle coefficient of the indoor center position and the radiation surface is from large to small,in order M3,M2,M1.The effects of various influencing factors on human body and environment heat transfer were analyzed,and it was concluded that air temperature had a great influence on human body heat balance under the same conditions.According to the existing radiant cooling laboratory,the indoor zero equation model was used to establish the physical model.The indoor wall surface temperature and air temperature were simulated by CFD technology,and the simulated data was compared with the measured data.The error was less than 5% which verifies the accuracy of the model.The heat transfer changes between the room and the outdoor environment were analyzed by using a validated model.The results show that under the same conditions of radiation surface temperature,the indoor wall temperature of M1 is the lowest in summer cooling,because the radiation and convection heat transfer effects of wall are the best;the temperature of M2 indoor wall is the highest in winter heating because of its convective heat transfer dominated;the heat gain of the rooms using M1 and M2 in different working conditions increased by 29.8% and 22.9% respectively.Finally,the indoor wall temperature obtained above is the boundary condition,and the average radiant temperature is calculated by the angular coefficient uneven distribution model.The results show that the M3 is the best in the indoor center area,and the average radiant temperature is reduced(increased)by 0.6?(3.1?)during cooling(heating).According to the obtained average radiant temperature and the air temperature and relative humidity calculated by CFD software,the sensible heat exchange amount and latent heat exchange amount of human body were calculated,and the PMV index was calculated according to the heat dissipation of the human body.The influence of the radiation end arrangement on the indoor average radiant temperature,air temperature and PMV index was analyzed.The results show that under the same conditions of radiation surface temperature,the indoor thermal environment created by M2 arrangement in summer cooling and winter heating is ideal: The indoor PMV using M2 during summer cooling is reduced by up to about 0.35 compared with the other two methods;the indoor PMV during winter heating is increased by up to about 0.5 compared with the other two methods.Therefore,it is recommended to use the top plate and the ground(M2)arrangement.When the distribution ratio of the top plate layout area is 52%~70%,indoor PMV difference between 1.1m and 0.1m height is small which provides some guidance for the design of the radiant panel layout in the hot summer and cold winter regions.