Different Approaches for Mass Transfer Studies on Potato Cylinders and Slices during Solar Drying

Abstract

In this paper, the influence of sample geometry and different solar drying conditions on mass transfer evaluation at food-air interface, hm obtained from different approaches is experimentally investigated. Two different approaches of hm estimation used in the analysis are based on the measurement of moisture loss rate data (direct method) and graphically computed values of drying parameters and moisture diffusion coefficient (indirect method). Drying experiments were performed with potato cylinders and slices of same thickness of 0.01 m with their respective length and diameter of 0.05 m using natural convection mixed-mode solar dryer and open air sun drying conditions. Results of analysis reveal that for each method of estimation, the cylinders vis-à-vis slices produce higher values of hm for both the solar drying conditions. It is also found that the mixed-mode solar drying enhances moisture transfer at food-air interface for each of the sample geometry as expected. Out of the two approaches investigated for hm estimation, the indirect method exhibits lower values of hm and these values are found to be more close to the results reported in the literature. The present analysis also indicates that Chilton-Colburn analogy for heat-mass convection does not hold well in the natural convection air drying of food product.