EVALUATION OF HEAT AND MASS TRANSFER COEFFICIENTS AT BEETROOT-AIR INTERFACE DURING CONVECTIVE DRYING
Abhishek Dasore, K. Ramakrishna, B. Kiran Naik
Abstract
In the present work, an experimental and numerical study on heat and mass transfer at the product-air interface is conducted during the drying of red beetroots. First, the effects of various governing parameters like air temperature, air velocity, product thickness, and relative humidity on drying kinetics of red beetroot are investigated experimentally. Later, heat and mass transfer coefficients of red beetroot slices are calculated during experiments, which are found to be in the range of 7−15 W/ms2K and 6.5−13 kg/m2s, respectively. Finally, a thermal model is developed to estimate the heat and mass transfer coefficients using a nondimensionalization technique across the product-air boundary layer. The backtracking algorithm is used to solve these heat and mass transfer equations. Then the developed model is verified using the experimental data and found in reasonable agreement with a percentage deviation of ± 8%. The interactive effect of governing parameters on moisture ratio are investigated and reveal that air temperature has a significant effect on the drying characteristics of red beetroot.