Study On Enhancing The Performance Of Heat Transfer Of The Water Based Surface Radiant Panels

The water based surface radiant air-conditioning system is a new type of air-conditioning system.The system has been widely used in engineering because of its advantages of low consumption of energy and good comfort.Although the scholars have carried out theoretical analysis and experimental research on the radiant air-conditioning systems,there are still some problems in the later application of the radiation air-conditioning system.These problems are mainly about the fact that the condensation of radiation panels and the cooling capability of the radiant panels which can not meet the requirements.When the cooling load in the room is large and the cooling capability of radiant panels can not meet the requirements,which often restricts the popularity of the radiation air-conditioning system.The popularity rate of radiant air-conditioning systems in China is very low,and there is a lot of room for development.Through the study of the heat transfer performance of the water based surface radiant panels,we can put forward some technical measures to enhance the heat transfer performance of the radiant panel,which has great significance to promote the water based surface radiant system.Firstly,this paper has been introduced the development of radiation air-conditioning system in China in recent years.This paper not only generalized the basic types of radiation systems,but also introduced the research status of radiation air-conditioning system by scholars at home and abroad.The heat transfer of the water based surface radiant panels includes heat transfer by convection and heat transfer by radiation.The radiation heat transfer is an important part of the total heat transfer,and there are many factors that affect the heat transfer.On the basis of analyzing the influence factors of the cooling capability of the water based surface radiant panel,a simple three-dimensional physical model of air-conditioning room was built by using Gambit.Fluent software was used to simulate the total heat flux of radiant panels under different positions.When the radiant cooling system was combined with the air supply system,the cooling capability of the radiant panel was affected by the parameters of air supply and the form of air supply.By changing the parameters of air supply and the form of air supply,the total heat flux of the radiant panel was studied,and the form of air supply and the parameters of air supply were found which can improve the cooling capability of the cooled radiant water based surface.The results show that the total heat flux of the radiant panel is the highest when the radiant panel is located at the ceiling.After the introduction of a new wind jet,the total heat flux of radiant panel in the room increases with the increase of air supply temperature when the air supply velocity is constant.When the air supply temperature is constant,the total heat flux of the radiant panel increases with the increase of the velocity of the air supply,and the growth rate of the total heat flux of the radiant panel is reduced when the air supply velocity is about 1.6m/s.The numerical models of radiant cooling combined with air supply systems were built,the nine cases that the terminal units of radition cooling system were in the ceiling,floor,side wall,and the terminal units of air supply system were in topside,underside,side were numerically simulated.When under floor air supply/floor radiant cooling,the total heat flux of the radiant panel is the largest,about 36.11W/m~2.And the thermal environment,the distribution of the temperature and velocity in the room were studied under different working conditions.The results show that with the increase of supply air velocity,the average temperature of the room and the inner surface of the enclosure structure is higher.With the increase of air supply temperature,the average temperature in the inner surface of the enclosure structure and the room temperature is rising.The internal environment was studied by CFD under the different working conditions.The results show that:when the radiant panel is installed at the ceiling,the difference of the vertical temperature in the working area is the smallest,about 2.0?,and it does not have much effect on the speed field in the room.The average temperature in the room decreases when the new wind jet is introduced and the distribution of temperature is more uniform when the air supply speed increases.When the ceiling cooling and floor air supply,the gradient of speed in the room is smaller.In this paper,the results of the experiment were analyzed,then the technical measures were put forward to optimize the cooling capability of the water based surface radiant air-conditioning system,and it provided a reference for the research of the water based surface radiant air-conditioning system.