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

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

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.

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 operat- ing 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. Cool- ing 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.