Effect of Shrinkage in Convective Drying of Spherical Food Material: A Numerical Solution

A computational model is generated to analyse the influence of shrinkage on convective drying problems. The object considered here is cranberry which is assumed as 100% spherical. The drying air temperatures were considered from 313 to 348 K. There were four models used in this study, namely one-dimensional models without and with shrinkage, two-dimensional models without and with shrinkage. A finite difference scheme was used to discretize the heat and mass transport equations. Four separate computer codes were written in MATLAB to solve the discretized equations. The Arrhenius model is used to couple the heat and moisture transport equations and solve them simultaneously. The Gauss–Seidel iterative method was used to solve the equations. An empirical shrinkage model was used to calculate the shrinkage effect. The temperature and moisture distributions of cranberry were obtained with drying time. Moisture distributions without and with shrinkage results were calculated and compared to identify the effect of shrinkage. The cranberry lost a maximum of 35% of its size during drying. There was not much variation found in the results between 1- and 2D models. The maximum difference in centre moisture content of cranberry without shrinkage model was 56%, and the difference in mean moisture content was 49.2%. The numerical outcomes were validated with experimental data, and the model with shrinkage was a good fit with them than without shrinkage. Therefore, shrinkage needs to be considered in convective drying phenomena.