Development of empirical expression for thin layer groundnut drying under open sun and forced convection modes

The thin layer drying behaviour of groundnut was investigated under open sun drying (OSD) and indoor forced convection drying (IFCD) modes. The groundnut samples were dried from initial moisture content of 38% (w.b.) to the safe storage moisture content of 8-10% (w.b.). Four mathematical models were compared for describing the groundnut drying process. The performance of thin layer drying models was investigated by comparing the statistical parameters such as coefficient of correlation (R), reduced chi-square (χ2), root mean square error (RMSE), and mean bias error (MBE) between experimental and predicted moisture ratios. Henderson and Pabis model was observed to give the highest value of R and lowest values of χ2, RMSE and MBE for the groundnut drying under both OSD and IFCD modes. The values of statistical parameters under Lewis model were also found to be very close to Henderson and Pabis model. Therefore, Henderson and Pabis and Lewis models were found to be the best for describing the drying behaviour of groundnut under both given conditions.