太阳辐射强度和温度对增强型冷却塔换热性能影响的研究

EFFECTS OF SOLAR RADIATION INTENSITY AND AMBIENT TEMPERATURE ON HEAT TRANSFER PERFORMANCE OF SOLAR ENHANCED NATURAL DRAFT DRY COOLING TOWER

太阳能增强型自然通风冷却塔(SENDDCT)作为一种新型空气冷却系统,可利用太阳能提高自然通风冷却塔的效率。利用FLUENT软件建立太阳能增强型冷却塔的三维模型,研究太阳辐射强度和环境温度对其性能的影响;同时设计并搭建太阳能增强型冷却塔的实验系统,在实际天气条件下研究太阳辐射强度对其换热性能的影响。模拟结果表明太阳辐射强度一定时,通过换热器的空气流速以及换热率都会随着环境温度升高而降低。太阳辐射强度为500 W时,环境温度由10℃升到40℃,换热率由1.106 kW下降到0.281 kW。实验结果表明有辐射时冷却塔入口处的平均空气温度要比无辐射时的高5℃;实验期间无辐射时的平均换热率为0.682 kW,有辐射时的平均换热率为0.794 kW,即利用太阳能将平均换热率提高了0.112 kW。

Solar enhanced natural draft dry cooling tower(SENDDCT)is a new heat rejection device that uses solar energy to increase the cooling efficiency of natural draft dry cooling tower.In this paper,a CFD model was developed by using FLUENT to analyze the influences of ambient temperature and solar radiation intensity on the performance of SENDDCT.Simultaneously,an experiment system for SENDDCT was designed and built,and the effect of solar radiation intensity on the performance of SENDDCT under natural conditions was studied.Simulation reaults indicated that air mass flow and heat transfer rate decreases with the increasing of ambient temperature.Specifically,heat transfer decreases from 1.106 kW to 0.281 kW with ambient temperature changing from 10℃to 40℃.Experimental results verified that the average air temperature of cooling tower entrance in natural solar radiation was 5℃higher than that without radiation;SENDDCT uses solar energy to enhance heat transfer rate from 0.682 kW to 0.794 kW during the experiment.