Mathematical Modelling and Simulation of the Mass and Heat Transfer of Batch Convective Air Drying of Tropical Fruits

Abstract

In the present study, a mathematical model capable of predicting the instantaneous moisture and temperature distribution inside fruit and vegetable material undergoing shrinkage during drying process has been developed. The model takes into account moisture content and shrinkage of material as well as shrinkage dependent effective diffusivity. The mass transfer and heat equations were solved using a numerical technique. For evaluation and validation purposes, the model was applied to drying data obtained from the drying tests carried out on banana slices. An oven dryer was used to conduct the test. Banana slices of approximately 5 mm thickness and 30 mm diameter were dried over a temperature range of 50 ^oC and 70 ^oC for 6 hours. The predicted results compared favourably with the experimental results. Thus, the experimental results validated the model developed. In addition, empirical drying rate equations are developed. The model is therefore capable of predicting dynamic behaviour of drying of fruits undergoing shrinkage and, as such, it can be used as a design tool.

Keywords: Drying; Mathematical modelling; Shrinkage; Simulation; Moisture diffusivity