果蔬预冷冰浆式湿冷热湿交换器性能实验

Performance of ice slurry humidicooling heat and moisture exchanger for precooling of fruits and vegetables

针对果蔬预冷设备应用场合,提出并设计了一套以冰浆作为载冷介质的湿冷热湿交换器,并搭建单体性能测试台架,以出风温度和相对湿度为指标,通过改变填料类型(金属、纸质填料)、载冷介质种类(冰浆、冷水)和喷淋流量进行了性能实验研究。结果表明:实验工况下,金属填料的换热性能较纸质填料好;以冰浆作为载冷介质相比以冷水的情况,可以获得更低的出风温度,但出风相对湿度也有所降低;随着进风干球温度的降低,出风温度明显降低,而出风相对湿度变化并不明显;在一定范围内,提高载冷介质的喷淋流量,有利于湿冷热湿交换器出风温度的降低和出风相对湿度的升高;低浓度的冰浆可以在湿冷热湿交换器中稳定运行,且降温效果较冷水湿冷热湿交换器更加明显,虽然相对湿度略有下降但仍然可保持在90%左右,适用于果蔬预冷和保鲜。

In allusion to the application of fruit and vegetable precooling equipment,a humidicooling heat and moisture exchanger with ice slurry as cold medium was proposed and designed,and a test bench for performance of the humidicooling heat and moisture exchanger was built.By changing fillers types(metal filler and paper filler),cooling media(cold water and ice slurry)and spray flow rate of the humidicooling heat and moisture exchanger,experimental investigations were conducted with the outlet air temperature and relative humidity as the evaluation parameters.The results showed that under the experimental conditions in this paper,the heat transfer performance of metal fillers was better than that of the paper fillers.The lower outlet air temperature was obtained by using ice slurry as cold medium compared to cold water,but the relative humidity of the outlet air was also lowered.When the dry bulb temperature of the inlet air decreased,the temperature of the outlet air decreased significantly,while the relative humidity of the outlet air did not change obviously.Within a certain range,increasing the spray flow rate was beneficial to the decrease of the outlet air temperature and the increase of the outlet air relative humidity of the humidicooling heat and moisture exchanger.The low concentration ice slurry could be used reliably in the humidicooling heat and moisture exchanger,and the cooling effect was more obvious than that of the cold water humidicooling heat and moisture exchanger.Although the relative humidity was slightly decreased,it could still remain at about 90%,which is suitable for precooling and preserving fruits and vegetables.