Experimental contrast on the cooling performance of direct evaporative all fresh air handling units with R32 and R410A

Abstract R32, with similar performance to R410A and low GWP, has been applied to refrigeration equipment for industry, commerce and similar purposes. There is an obvious tendency for R410A to be replaced by R32. As a result, the study of replacing R410A with R32 for direct evaporative all fresh air handling units(DEAFAHU), as an important building fresh air supply equipment, is needed urgently at present. In this study, a DEAFAHU originally using R410A is charged with R32 directly with the unit structure and components kept consistent. The experimental contrast between the unit performance using R410A and R32 indicates that the unit performance with R32 is lower than or equal to that with R410A due to direct charge replacement. Under the cooling condition, when ambient temperature is 35℃ and below, the highest dis-charge temperature of R410A and R32 unit is 94.72℃, which is in the acceptable range; while when ambient temperature above 35℃, the discharge temperature of R32 unit has a greater effect on the performance than R410A unit. Then, cooling unit by spraying liquid to keep the discharge temperature of R32 unit at around 90℃. Along with the discharge temperature dropping, the degree of under cooling and superheat and the energy efficiency ratio of unit get lower to a certain extent, so is the cooling capacity. Therefore, the DEAFAHU with R32 can sustain performance and is ensured to work safely in the 90℃. For DEAFAHU, the replacement with R32 needs to notice the high discharge temperature under the cooling condition above 35℃. The technology is worthy recommendation that uses liquid injection cooling with the reduce of cooling capacity to keep the discharge temperature of unit around 90℃.