Experimental Study on Effect of Loading Density on Performance of A Quasi-Two-Stage Closed Heat Pump Drying System for Lentinus Edodes

The drying of Lentinus edodes is an effective method to prevent problems such as its rotting and browning, and during the drying process, the loading density has a significant impact on system performance and drying quality. Based on a newly designed quasi-two-stage jet-enhanced enthalpy heat pump closed drying system, the effects of different lentinus edodes loading densities on moisture ratio, drying rate, coefficient of performance of the system (COPsys), specific moisture extraction rate (SMER), drying amount per unit energy consumption, and rehydration ratio were experimentally investigated. The results showed that when the drying air supply temperature was 55 °C and the circulating air volume was 580 m3/h, the drying rate of lentinus edodes decreased gradually with the loading density in drying chamber increasing from 1.5 kg/m2 to 3.0 kg/m2, and the average COPsys, average SMER, drying amount per unit energy consumption and rehydration ratio increased first and then decreased. The average SMER, drying amount per unit energy consumption and rehydration ratio reached the maximum values when the loading density was 2.4 kg/m2, which were 0.320 kg/(kW·h), 0.391 kg/(kW·h) and 3.6, respectively. When the loading density was 2.4 kg/m2, the average COPsys reached a maximum of 4.22. The research results can provide a reference basis for determining the packing density in the heat pump drying process of Lentinus edodes.