新风侧凝结对间接蒸发冷却器换热性能的影响研究
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摘要
为研究间接蒸发冷却系统作为空调系统的新风预冷装置在夏季相对湿度较高的环境下的换热性能,利用微元分析法构建了适用于叉流板式间接蒸发冷却换热器的二维传热传质分析解模型,并对不同新风温湿度状态下间接蒸发冷却系统的换热性能进行了试验测试。理论计算及试验结果表明:在夏季高温潮湿环境下,间接蒸发冷却器新风通道内将出现凝结换热。换热壁面上的凝结液膜虽然会增加导热热阻降低显热传热量,但系统总换热量将随凝结换热过程的增强而显著提高,凝结过程产生的潜热换热量占总换热量的75%左右。换热器的湿球换热效率在新风相对湿度为50%,70%,90%状态下分别为70%,62%,50%左右。蒸发过程中的喷淋水消耗量与系统总换热量相关,平均每产生1 kW的热量传递对应消耗水量为1.5 L/h。
In order to research the heat transfer performance of indirect evaporative cooling unit as a fresh air pre-cooling device in air conditioning system under the environment of relatively high humidity in summer,the paper provided a two-dimension mass transfer analytical model for cross-flow indirect plate type evaporative cooler based on control volume analysis,and a series of experiments were also conducted on heat transfer performance of the indirect evaporative cooling system under different temperature and humidity states of fresh air. The results of simulations and experiments show that:in the fresh air channel of IEC unit there would appear condensation when the fresh air under the environment of relatively high humidity in summer.Although the condensed water film on heat exchanger surface would increase the thermal resistance and reduce the quantity of sensible heat transfer,the total heat transfer quantity of the system would be increased significantly with the intensification of the latent heat transfer from condensation,which accounts for about 75%.The wet-bulb heat transfer efficiency of the heat exchanger was 70%,62% and 50%,respectively when the relative humidity of fresh air was 50%,70% and 90%,respectively. The water consumption in evaporation process is related to the total heat transfer quantity of the system,and the average amount of water consumption for 1 kW heat transfer was 1.5 L/h.
In order to research the heat transfer performance of indirect evaporative cooling unit as a fresh air pre-cooling device in air conditioning system under the environment of relatively high humidity in summer,the paper provided a two-dimension mass transfer analytical model for cross-flow indirect plate type evaporative cooler based on control volume analysis,and a series of experiments were also conducted on heat transfer performance of the indirect evaporative cooling system under different temperature and humidity states of fresh air. The results of simulations and experiments show that:in the fresh air channel of IEC unit there would appear condensation when the fresh air under the environment of relatively high humidity in summer.Although the condensed water film on heat exchanger surface would increase the thermal resistance and reduce the quantity of sensible heat transfer,the total heat transfer quantity of the system would be increased significantly with the intensification of the latent heat transfer from condensation,which accounts for about 75%.The wet-bulb heat transfer efficiency of the heat exchanger was 70%,62% and 50%,respectively when the relative humidity of fresh air was 50%,70% and 90%,respectively. The water consumption in evaporation process is related to the total heat transfer quantity of the system,and the average amount of water consumption for 1 kW heat transfer was 1.5 L/h.
引文
[1]褚俊杰,黄翔,孙铁柱.国内外露点间接蒸发冷却技术研究最新进展[J].流体机械, 2017,45(9):71-76.
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[4]赵振生,任承钦,涂敏,等.叉流板式间接蒸发冷却换热器的试验研究[J].制冷学报,2010,31(1):45-49.
[5]黄翔,稽伏耀,狄育慧,等.包覆吸水性材料椭圆管式间接蒸发冷却器的理论与试验研究[J].制冷学报,2006,27(2):48-54.
[6]王玉刚,黄翔,武俊梅,等.包覆在椭圆管式间接蒸发冷却器上功能性吸湿材料的理论与试验研究[J].流体机械,2005,33(3):46-49.
[7]刘佳莉,黄翔,韩正林,等.干燥工况下新型复合式露点间接蒸发冷却空调机组的试验研究[J].流体机械, 2015,43(3):52-57.
[8]CuiX,ChuaKJ,IslamMR,etal.Fundamental formulation of amodified LMTD method to study indirectevaporativeheatexchangers[J].Energy Convers Manage,2014(88):372-381.
[9]AntonellisSD,JoppoloCM,LiberatiP,etal.Modelingandexperimentalstudyofanindirect evaporativecooler[J].EnergyandBuildings,2017(142):147-157.
[10]Heidarinejad G,Bozorgmehr M,Delfani S,et al.Experimentalinvestigationoftwo-stageindirect/directevaporativecoolingsysteminvariousclimatic conditions[J].Building and Environment,2009(44):2073-2079.
[11]Bolotin S,Vager B,Vasilijev V.Comparative analysis of the cross-flow indirect evaporative air coolers[J].International Journal of Heat and Mass Transfer,2015(88):224-235.
[12]Zalewski W,Gryglaszewski P A. Mathematical model of heat and mass transfer processes in evaporative fluid coolers[J].ChemicalEngineeringandProcessing,1997(36):271-280.
[2]Campani?o H,Soares PM,Hollmuller P,et al. Climatic cooling potential and building cooling demand savings:highresolutionspatiotemporalanalysisofdirect ventilationandevaporativecoolingfortheIberian Peninsula[J].Renew Energy,2016,85:766-776.
[3]Ren C Q,Yang H X. An analytical model for the heat andmasstransferprocessesinindirectevaporative cooling with parallel/counter flow configurations[J].Int. J. Heat Mass Transf.,2006,49(3):617-627.
[4]赵振生,任承钦,涂敏,等.叉流板式间接蒸发冷却换热器的试验研究[J].制冷学报,2010,31(1):45-49.
[5]黄翔,稽伏耀,狄育慧,等.包覆吸水性材料椭圆管式间接蒸发冷却器的理论与试验研究[J].制冷学报,2006,27(2):48-54.
[6]王玉刚,黄翔,武俊梅,等.包覆在椭圆管式间接蒸发冷却器上功能性吸湿材料的理论与试验研究[J].流体机械,2005,33(3):46-49.
[7]刘佳莉,黄翔,韩正林,等.干燥工况下新型复合式露点间接蒸发冷却空调机组的试验研究[J].流体机械, 2015,43(3):52-57.
[8]CuiX,ChuaKJ,IslamMR,etal.Fundamental formulation of amodified LMTD method to study indirectevaporativeheatexchangers[J].Energy Convers Manage,2014(88):372-381.
[9]AntonellisSD,JoppoloCM,LiberatiP,etal.Modelingandexperimentalstudyofanindirect evaporativecooler[J].EnergyandBuildings,2017(142):147-157.
[10]Heidarinejad G,Bozorgmehr M,Delfani S,et al.Experimentalinvestigationoftwo-stageindirect/directevaporativecoolingsysteminvariousclimatic conditions[J].Building and Environment,2009(44):2073-2079.
[11]Bolotin S,Vager B,Vasilijev V.Comparative analysis of the cross-flow indirect evaporative air coolers[J].International Journal of Heat and Mass Transfer,2015(88):224-235.
[12]Zalewski W,Gryglaszewski P A. Mathematical model of heat and mass transfer processes in evaporative fluid coolers[J].ChemicalEngineeringandProcessing,1997(36):271-280.