Research and Analysis of Multi-Condition Performance of a Closed Heat Pump Clothing Drying System

To investigate the effect of different drying conditions on the efficacy of a closed heat pump clothing-drying system, parametric studies with control variables were carried out on the circulating air volumetric flow rate, expansion valve opening, and air inlet temperature within the drying chamber and their impact on system heat production, heat pump system coefficient of performance (S_COP), cooling capacity utilization ratio (E_R), and exergy loss. The findings indicated that when the expansion valve was set to 70% opening, the circulating air volumetric flow rate was increased from 500 m³/h to 1000 m³/h, and the heat generation of the system increased by 59.73%. In contrast, the S_COP, E_R, and exergy loss decreased by 31.29%, 56.65%, and 31.31%, respectively. Furthermore, when the circulating air volumetric flow rate of 1000 m³/h was maintained while adjusting the expansion valve opening from 20% to 70%, the heat generation, S_COP, and E_R of the system increased by 32.58%, 6.51%, and 29.51%, respectively. At the same time, the exergy loss decreased by 12.44%. Finally, under the conditions of a 70% open expansion valve, a circulating air volumetric flow rate of 1000 m³/h, and an increase in the desiccator′s air intake temperature from 40 ℃ to 70 ℃, the heat generation of the system increased by 43.71%, while the S_COP, E_R, and exergy loss decreased by 11.22%, 60.84%, and 14.17%, respectively. These results emphasize the advantages of reducing the circulating air volumetric flow rate and inlet air temperature within the drying chamber while increasing the expansion valve opening, as these adjustments help to improve the overall performance of the system and promote energy efficiency.