EFFECT OF LOW-PRESSURE ON THE REFRIGERATING CAPACITY OF DIRECT EXPANSION EVAPORATOR

Convective heat transfer coefficient on the air side of direct expansion evaporator under low airpressure is studied by theory and experiment respectively. Results show the convective heat transfercoefficient will diminish along with the density of air under low-pressure. The lower absolute humidity ofair under lower pressure will reduce the difference of water vapor pressure between the air supply andair return. And the quantity of latent heat transfer between the evaporator and the air will decreaseaccordingly. Meanwhile, the process of heat transfer on the refrigerant side will change under low airpressure, which will make the refrigerating capacity become even smaller.