Analysis of CO2Transcritical Cycle Heat Pump Dryers

The heat pump dryer with CO2 as the working medium is investigated in this study. The drying systems were designed based on the thermophysical properties and characteristics of CO2 cycle. The two-stage drying of CO2 transcritical cycle heat pumps are presented and discussed in comparison with the single compression cycle single-stage heat pump dryer, the two-stage drying heat pumps, and electric drying system. The analysis indicates that the specific moisture extraction ratio of the two-stage drying system can be higher than that of the single drying CO2 system. The efficiency of energy utilization of the CO2 heat pump dryer was higher than that of an electric dryer.