Study On Heat Transfer Performance Of Double-Sided Radiant Cooling System

Energy saving,environmental protection and comfort of building cooling have become a basic direction in modern cooling development. The double-sided radiation cooling system has not only the advantages of high efficient,energy conservation,good comfortable sensation,good indoor sanitary condition,good thermal stability and less construction area which belong to radiant floor cooling system,but also has the advantages of less initial investment and more even indoor temperature field made by the floor and roof radiation。Therefore,it is great significant to make sure the double-sided radiation cooling system construction method,know its heat transfer performance well and provide the indoor environment and intermittent operation indoor environment change.In this study,the construction site is professor fu's villa in Huxi campus of Chongqing university. Double-sided radiation system construction process is studied first and the construction method is made. The project target and assignment are determined, the construction drawing is perfect and the construction management plan, risk management plan and construction schedule are formulated in the construction preparatory stage. During the construction process the special method and requirement is continuously researched and summarized and the radiation tube laid method, work strength and other process of construction methods is determined as well.This paper put forward the definition of double-sided radiant cooling system. Its basic structure and heat transfer characteristics are analyzed and the heat transfer performance of the calculation formula is derived, too.Different outdoor working conditions experiments have been researched after the platform built and the 3 experimental room of heat transfer performance of floor 1,floor 2 and negative floor, 3 experimental rooms,have been compared. The out door high humidity condition experiment lasts 84 hours and the high temperature condition experiment lasts 180 hours. Different experimental conditions such as room temperature field,humidity field,all palisade structure surface temperature in each time,system energy consumption and the error analysis of the experimental data after treatment have been tested. The floor surface temperature and ground upper 0.1 m place dew point of air temperature changing with time lasting has been compared. The roof,floor and wall inner face temperature changing with time lasting,the indoor temperature gradient vertical changing with time,the changes of indoor enclosure structure surface temperature and air temperature after system stopping running and the time required by the system to achieve stable operation stage under the action of radiation and natural convective heat in different experiment condition have been analyzed. The indoor radiation heat transfer,average radiation temperature,radiation heat transfer coefficient,natural convection heat transfer,natural convection heat transfer coefficient,function temperature , comprehensive equivalent parameters in stable system have been calculated,as well. Through calculation and analysis,in high humidity condotions,the comprehensive equivalent heat transfer coefficient of floor 1 is 6.75 W(/㎡·K), floor 2 is 6.28 W/(㎡·K)and negative foor 6.87 W/(㎡·K). And the upward comprehensive equivalent heat transfer coefficient of floor 1 is 6.41 W(/㎡·K),while the downward is 7.18 W/(㎡·K). In high temperature condition,the comprehensive equivalent heat transfer coefficient of floor 1 is 6.16 W(/㎡·K), floor 2 is 6.75 W(/㎡·K)and negative foor 6.48 W/(㎡·K). And the upward comprehensive equivalent heat transfer coefficient of floor 1 is 5.86 W/(㎡·K),while the downward is 6.73 W/(㎡·K).