Drying Kinetics of Maize Cob Using Mathematical Modelling

Abstract

Maize cobs (with husk and without husk) with initial moisture content of 78.38 % and62.39 % (d.b.), respectively, were dried up to 20 % moisture content (d.b.) at threetemperatures (45°C, 55°C and 65°C). Moisture ratios (MR) were calculated from moistureloss data and fitted to six (Newton’s, Page, Thompson, Modified Page, Henderson andPabis, and Wang and Singh) drying mathematical models. Coefficient of determination(R2) and root mean square error (RMSE) were used for comparison of the models. Fromthe analyses, Modified Page model showed the best fit to the experimental data with R2varying from 0.9924 to 0.9968 for maize cob with husk and 0.9994 to 9989 for cobs withouthusk at given drying temperatures. The Modified Page model was found to be a superiormodel representing the drying kinetics of maize cob with and without husk at dryingtemperatures of 45, 55, and 65°C. The increase in drying temperature caused a reductionin drying time, and the drying took place in the falling rate period. Maize cobs with husktook more time for drying as compared to that without husk at the same temperature.The values of effective diffusivity lied between 1.079×10-8 m2.s-1 and 4.239×10-8 m2.s-1for maize cob with husk, and between 1.194×10-8 m2.s-1 and 5.230×10-8 m2.s-1 for maizecob without husk. Effective diffusivity increased with increase in drying temperature, andwas higher for maize cob without husk than that of with husk.