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This article is a comparison of the date fruits drying performance of two most simple and common type of solar dryers. A simple even span type forced convection greenhouse dryer (FCGHD) and a forced convection cabinet solar dryer (FCCSD) were developed and tested under the climate of Hisar, India. The average values of convective heat transfer coefficients (HTC) were calculated as 0.46 and 0.53 W m−2 °C−1 for FCGHD and FCCSD, respectively. The respective average evaporative HTC was evaluated as 64.58 and 276.06 W m−2 °C−1. The drying efficiency and specific energy consumption for date fruits drying under FCCSD were, respectively, 55.2% higher and 37.87% lower than that of FCGHD. Amongst seven considered thin layer drying models, Midilli–Kucuk model showed the highest commensuration to the experimentally evaluated drying data of moisture ratio for date fruits. Higher values of effective moisture diffusivity and lower values of activation energy were observed under FCCSD. The economic prospective of both the drying arrangements has also been presented. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper, convective and evaporative heat transfer coefficients of the Indian groundnut were computed under indoor forced convection drying (IFCD) mode. The groundnuts were dried as a single thin layer with the help of a laboratory dryer till the optimum safe moisture storage level of 8 - 10%. The experimental data were used to determine the values of experimental constants C and n in the Nusselt number expression by a simple linear regression analysis and consequently, the convective heat transfer coefficient (CHTC) was determined. The values of CHTC were used to calculate the evaporative heat transfer coefficient (EHTC). The average values of CHTC and EHTC were found to be 2.48 W/m2 oC and 35.08 W/m2 oC, respectively. The experimental error in terms of percent uncertainty was also estimated. The experimental error in terms of percent uncertainty was found to be 42.55%. The error bars for convective and evaporative heat transfer coefficients are also shown for the groundnut drying under IFCD condition. [ABSTRACT FROM AUTHOR]