陶瓷泡沫填料逆流直接蒸发冷却热质传递特性的实验研究

采用30 PPI的氧化铝(Al2O3)陶瓷泡沫块作为蒸发冷却器填料,在人工环境舱中进行了逆流直接蒸发冷却实验.着重研究了填料厚度、进口空气的干球温度、湿球温度以及空气流量对填料热质传递性能的影响.选用冷却效率和加湿量分别作为热传递和质传递性能的评价指标.实验结果表明,以氧化铝陶瓷泡沫为填料的直接蒸发冷却器,冷却效率最高可以达到0.88,出口空气的含湿量最大可以增加3.15 g/kg.当进口干球温度、进口湿球温度升高以及空气流量增大时,陶瓷泡沫的冷却效率都呈下降趋势.加湿量随着进口干球温度的升高而增加,但是随着进口湿球温度升高和空气流量增大而减少.在相同实验条件下,2层陶瓷泡沫的冷却效率、加湿量都高于1层的冷却效率和加湿量.

Experimental study on heat and mass transfer characteristics in evaporative cooler with ceramic foam packings

Alumina(Al2O3) ceramic foam blocks with a pore density of 30 PPI(pores per inch) were selected to be the direct evaporative cooling experimental wetted pad.Experiments were carried out in a psychrometric chamber with controllable air temperature and humidity.The effects of operating parameters,such as height of the packing,the dry-and wet-bulb temperature of inlet air,as well as mass flow ratio of water to air,on the heat and mass transfer performances were analyzed.Cooling efficiency and the humidity increment were chosen as the performance index.Experimental results show that a cooling efficiency of 0.88 and a water content increment of 3.15 g/kg can be achieved.The cooling efficiency of the packing decreases with the increasing inlet air dry-and wet-bulb temperature and the air flow rate.The water content increment rises with the increment of the inlet air dry-bulb temperature,but drops with wet-bulb temperature and the air flow rate.Both the cooling efficiency and the water content increment grow with the height of the packing.