Research On Indoor Thermal Environment Of The Hybrid Radiant Cooling Air-conditioning System

In order to cover the shortage of radiant cooling system, a new kind of hybrid radiantcooling air-conditioning system which is based on the theory of temperature and humiditydecoupled treatment was proposed. The dehunidified fresh air is sent into the room by acertain sort of air supply, not only to low the dew-point temperature, reduce the risk ofindoor condensation and improve the indoor air quality, but also to remove part of coolingload to enhance the cooling capacity of hybrid system. In this way can the radiant coolingsystem be applied in some occasions of large cooling load, while promote the furtherdevelopment of radiant cooling technology.Based on introducing the form and characteristic of the hybrid radiant coolingair-conditioning system,firstly this thesis selected the radiant cooling with wall-attached-jetair-conditioning system to carry on experimental study under the similar outside conditions.Comparative experiments have been performed in a radiant cooling experimental room:radiant wall cooling experiment, wall-attached-jet air supply experiment, radiant coolingwith wall-attached-jet experiment, especially carry on the anti-condensation of radiantpanel experiment and visualizing validation of wall-attached-jet’s coanda effect and airdistribution. Experimental results have proven that wall-attached-jet have the fuction toprevent the condensation of radiant panel and can form the air distribution similar withdisplacement ventilation;The radiant cooling system can’t achieve thermal comfort andwhen the hybrid air-conditioning system stable running, radiant panel temperature is21.8℃, supply air temperature is21.4℃, air velocity is2.53m/s,and indoor air achieves thedesign condition, vertical temperature gradient meets the requirements, thermal comfort isgood.While based on experimental datas,the pre-dehumidifying time,the mean radianttemperature,the operation temperature,radiation asymmetry,proportion of thermal radiationand PMV-PPD of the hybrid system were calculated, which proved the applicationfeasibility of the hybrid system from the experimental and theoretical aspects.Then professional CFD software was used to carry on numerical simulation validation.According to the measured data to set conditions, the results of indoor air temperaturefield,vertical temperature profile and PMV-PPD were procured.The validity of the resultswere verified by experimental data. Finally use the Airpak software to analyze the radiantcooling with wall-attached-jet compared to the radiant cooling with displacementventilation system.It turned out that the latter is slightly better than the former, but becauseof wall-attached-jet arranged on the upper space without affecting by some equipments laidover the floor, the radiant cooling with wall-attached-jet air-conditioning system has certainadvantage and promising applications.