Performance evaluation and optimization of a novel heat pump clothes dryer with ESD-compressor

This study proposes a novel heat pump drying cycle, which uses an enhanced single-stage suction and dual-stage discharge compressor (HPDESD). The system enables the step heating of the cold air at the evaporator exit, reducing the irreversible losses in both compression and heat transfer process. The simulation results agree well with the experimental results. The energy consumption and drying time of the HPDESD system is 1.63kWh and 156mins, respectively, causing an energy-saving rate of 20.3% and saving 4mins compared to the basic heat pump drying cycle. In addition, the SMER and MER are sensitive to the compressor size and air cycle flowrate rather than clothing mass. When compressor size decreases of 20% and the air cycle flowrate increases 20%, the SMER rises by 16.2% and 5.2%, respectively, compared to the original system. Meanwhile, the SMER and MER of the optimized system are 3.64 kg/kWh and 2.21 kg/h, respectively, which are 11% and 7.3% higher than the original design. It is worth noting that the HPDESD system has higher SMER and MER than other types. In future, utilizing the extra energy and adopting the optimization control strategy of compressor can further improve the performance of the heat pump dryers.