Performance comparison of R32 and R410A in direct evaporative all fresh air-handling units under variable temperature conditions

摘要

The replacement of R410A with R32 for direct evaporative all fresh air-handling unit, a widely applied equipment for fresh air supply, is experimentally investigated with a bypass added in sample unit to connect condenser outlet and compressor inlet for liquid injection. Performance comparison indicates that, the comprehensive cooling/heating performance of R32 unit is slightly lower than/equal to R410A unit. When ambient temperature goes above 35 degrees C, the bypass is switched on to lower discharge temperature to 90 degrees C in the first injection and 80 degrees C in the second round. This also causes a corresponding decrease in cooling capacity, energy efficient ratio, sub-cooling, and super-heating degree. The sub-cooling and super-heating degree is even pulled to 0 in the second injection and causes operation instability. The results indicate that, the direct evaporative all fresh air-handling unit can be confidently expected to have satisfying cooling capacity, sub-cooling, and super-heat degree when the unit components and design are adjusted for the quality of R32.