The Cooling Load Characteristic Analysis In The Condition Of Ceiling Radiant Cooling Panels

Ceiling radiant cooling panels have got attention widely for its energy savingeffect. However, the research of it takes example by traditional convection airconditioning at present, due to started relatively late in our country. The paperdiscusses the load characteristic of the radiation cooling system and whether thetraditional air condition design method is suitable to it.The paper introduces the ceiling radiant cooling panels&dedicated outdoor airsystem. In this system, the fresh air controls the room humidity, and the panels dealwith the most cooling load. Thus, the building energy consumption can be saved. Atpresent, the radiation cooling load calculation continues to use the design method oftraditional air system, and it uses the equivalent radiation heat exchanges method tocalculate the cooling panel areas. However, because the room features of the radiationcooling system are different from the traditional system, the cooling load is changedtoo. The paper analyses the differences between the two systems, from the aspect ofthe heat gain, the cooling load and surface temperature of the objects.Through the experimental analysis, the wall temperature distribution of the roomis obtained. It can be regarded as the study basis of the room load characteristic.Experimental results show that the wall temperature is lower than air temperatureunder the radiation cooling system, in contrast to the results of convectionair-conditioning system.The calculation method of air conditioning cooling load is analyzed. Though thecooling load coefficient method adopts the cooling load coefficient which is obtainedfrom convection air-conditioning system, and it calculates the heat quantity whichentering in the room air, it can’t apply to calculate the load of radiation coolingsystem. However, the heat balance method can be used to calculate the wall surfacetemperature and the air temperature, thus it can be used as the basis for cooling loadcalculation.The paper simulates the load characteristic of radiant cooling system byTRNSYS. The simulation shows that: the operative temperature is almost the samewhen the panel temperature of radiation cooling system is25℃and the airtemperature of convection air-conditioning system is26℃. The result can be treatedas the basis of the load characteristic studying. The paper takes the northwest wall of the room as an example, the heat flux that entered the room increases, because thewall temperature is lower in the radiant cooling system by the use of radiation heattransfer. Though the variation trend between the ceiling radiant cooling andconvection cooling is quite similar, there isn’t a curve which is relatively close at bothhigher and lower temperatures. Therefore, we can’t calculate the convection coolingload in order to get the ceiling ra diant cooling load. We should use the simulationsoftware to calculate it by heat balance method.