Infra Red Drying and Hot Air Drying of Potato: A Theoretical Consideration

Comparative study of drying of potato (Solanum tuberosum) cubes by infra-red drying (IRD) and hot air drying (HAD) was carried out with and without taking shrinkage into account. Results of this study were compared with experimental data satisfactorily in case of IRD as well as HAD. In both the cases results were found to be very close to the experimental data when shrinkage was taken into account. IRD experimental data were fitted well as compared to HAD data when shrinkage was not considered. It was shown that shrinkage of the potato cubes during initial phase of drying caused the falling drying rate period and was controlled by the external water transfer resistance. It was recommended that Neuman type rather than Dirichlet type boundary conditions should be used for calculation of the effective diffusivity during the first phase of the falling rate period of drying of the potato cubes.