Mathematical Model of Radio Frequency Assisted Heat Pump Drying of Ganoderma Lucidum (Ganoderma Boninense)

Abstract

This study proposed a mathematical model which was used to predict the temperature and moisture content of Ganoderma lucidum (Ganoderma boninense) during the radio frequency (RF) assisted heat pump (HP) drying process. The simultaneous heat and mass transfer equations were established based on the physical and flat plate models for drying Ganoderma lucidum and the specific assumptions for the proposed problem. The finite difference method was used to solve the proposed heat transfer and moisture transfer problem, in which, pdepe function was adjusted and complemented with Matlab software. The temperature and moisture content of the material in the drying process was predicted. The effect of the output RF power on the temperature and moisture content of the material was evaluated. The drying process's input parameters were drying air temperature of 40oC, air velocity of 1.2 m/s, and an output RF power of 1.95 kW, 0.65 and 0 kW. The results showed that when the output RF power increases, the heating rate increases, and the drying time is shortened significantly. The drying material temperature reaches the drying air temperature in 20 minutes, 30 minutes, and 220 minutes and the drying time is 465, 555, and 700 minutes, corresponding to output RF power of 1.95 kW, 0.65 and 0 kW. The predicted temperature and moisture content of the material were compared with experimental drying data, and a considerably good agreement was found.