Development And Thermal Comfort Research Of Experimental System Of Cold Radiation Ceiling Combined With Displacement Ventilation

Now with the rapid development of air-conditioning technology,People’s comfort requirements are increasing.Radiation air-conditioning has become a new type of airconditioning terminal because of its advantages of high energy-saving,low noise,good comfort and less occupied space.Displacement ventilation will send outdoor fresh air into indoor,indoor dirty air through the top of the air outlet,ventilation,ventilation efficiency is high.But because of the limitation of the velocity and temperature difference of the air supply,the capacity of the single displacement ventilation is limited.Radiation ceiling combined with displacement ventilation air conditioning system solves the problems of no fresh air and insufficient cooling capacity of displacement ventilation in radiation air conditioning,but radiation ceiling will affect the air distribution of displacement ventilation,and then affect the comfort.Therefore,it is of practical significance to carry out experimental and simulation study on the system form and operation parameter matching of radiation ceiling combined with displacement ventilation.Based on the theory of radiant cooling and displacement ventilation,the experimental platform of the air conditioning system with the combination of radiant ceiling and displacement ventilation is designed and built.The test-bed includes airconditioning room,cold and heat source system,water system,air system,control system and data acquisition system.The radiation cooling of air-conditioned room is in the form of radiation ceiling,and the displacement ventilation is in the form of ground air supply.Taking the air-conditioned room as the research object,the CFD method is used to simulate the air-conditioned room.The velocity field,temperature field,PMV and PPD distribution in the room under different working conditions are obtained by changing the air supply parameters,and the optimal air supply combination is obtained by analyzing,and the simulation results are verified by experiments,the results show that the indoor air distribution and comfort are best when the air supply temperature is 22 °C and the air supply velocity is 0.25 m/s,and the higher the air supply temperature is,the smaller the vertical temperature gradient is,the stronger the air entrainment near the heat source in the room,the stronger the air entrainment when the air velocity is increased,the more obvious the eddy current will appear in the room,and the higher the wind velocity near the human body will cause the wind sensation The temperature of air supply has a great influence on indoor temperature gradient,and the velocity of air supply has a great influence on indoor air distribution.By changing the number and position of the air supply outlet,the influence of the number and position of the air supply outlet on the indoor air distribution and thermal comfort is analyzed.The results show that the indoor heat load can not be eliminated well when the number of tuyere is small,it is necessary to reduce the air supply temperature or increase the air supply speed to better eliminate the indoor residual heat,at the same time,the air supply outlet should not be arranged in the location where the heat transfer of the enclosure is large,and the air supply outlet and return outlet should be arranged on the different sides of the room.There are 66 pictures,25 tables and 55 references.