Numerical simulation and study on heat and mass transfer in a hybrid ultrasound/convective dryer.

Susceptibility of airborne ultrasonic power to augment heat and mass transfer during hot air dehydration of peppermint leaves was investigated in the present study. To predict the moisture removal curves, a unique non-equilibrium mathematical model was developed. For the samples dried at temperatures of 40‒70 °C and the power intensities of 0‒104 kW m -3 , the diffusion of moisture inside the leaves and coefficients for of mass and heat transfer varied from 0.601 × 10 -4 to 5.937 × 10 -4  s -1 , 4.693 × 10 -4 to 7.975 × 10 -4  m s -1 and 49.2 to 78.1 W m -2  K -1 , respectively. In general, at the process temperatures up to 60 °C, all the studied transfer parameters were augmented in the presence of ultrasonic power.