Modeling and simulation of moisture transfer during solar drying of carrot slices

Carrot slices of 0.03m diameter and 0.005m thickness were dried in direct, indirect and mixed mode type natural convection solar dryers. Thin layer drying behavior of carrot slices was studied using 10 empirical and semi-empirical mathematical models. Wang and Singh model described the drying behavior of carrot accurately with maximum values of coefficient of determination (R-2) and minimum reduced chi-square ((2)), and root mean square error (RMSE). The effective diffusivity (D-eff) and convective mass transfer coefficient (h(m)) of carrot slices ranged from 2.59x10(-8)-6.36x10(-8) m(2)/s and 3.15x10(-7) to 4.28x10(-7) m/s, respectively, with maximum values obtained for mixed mode solar dried samples followed by direct and indirect solar dried samples. The diffusivity of carrot slices dried in direct, indirect and mixed-mode solar dryer were expressed as a function of temperature using Arrhenius relation. Finite element model was developed using COMSOL Multiphysics software to simulate moisture ratio during drying. The developed model predicted the transient moisture migration phenomenon inside the samples precisely during the drying process. Practical applicationsThe ever increasing worriment on climate change and growing demand for enactment of clean energy technologies in food industries is the motivation for investigating the solar drying behavior of carrot slices. It is well known that the physico-chemical and sensorial changes during drying are very much dependent on the moisture content of food product. In this regard, proper understanding and controlling of the solar drying process by accurately predicting moisture distribution inside the product will result in superior quality dried products. Moreover, mathematical models will assist in predicting the drying behavior of food product by analyzing the influence of process parameters and will be helpful to minimize the cost of drying process and deterioration of quality attributes of the product. The use of solar dryers is a proven technology and the food industry should promote its practical applications in food processing sector.