Effect of Ultrasound on Heat Pump Drying Characteristics of Pea Seeds

For the purpose to study the effect of ultrasound treatment on heat pump drying, the experiments were conducted on pea seeds at drying temperature of 30, 35 and 40 degrees C, ultrasound power of 0, 60 and 100 W and frequency of 0, 28 and 40 kHz. The influence of ultrasound and temperature on the drying process was studied by analyzing the drying characteristics of pea seeds. The results demonstrated that increasing the ultrasound power, frequency and drying temperature can improve the drying rate and the Midilli model can describe the drying kinetics of pea seeds well. The effective moisture diffusion coefficient increased with the increase of ultrasound power, frequency and drying temperature, while there was no obvious trend for the change of seed activation energy under different conditions. The seed viability was promoted with the raise of ultrasound power and fell when increasing drying temperature.