Performance analysis of indirect solar dryer with natural heat energy retention substances for drying red chilli

Abstract

The world is grappling with substantial food waste after cultivation, mostly due to increased moisture contents. Therefore, the objective of this study concentrates on developing an innovative indirect methodsolar dryer designed to eliminate moisture content by incorporating glass pieces and paraffin wax as Natural Heat Energy Retention Substances (NHERS) in the solar collector. Three distinct dryer setupshave been designed to assess the effectiveness of the suggested innovation namely a collector without NHERS, a collector with glass pieces as NHERS and a collector with combined glass pieces and paraffin wax as NHERS for drying red chilli. Along with these three different dryer setups, open solar drying was done. From the experimental observations, the drying kinetics, energy, exergy and colour analyses were conducted. Red chilli's wetnesscontent dropped from 83.8% (wet basis) in the beginning to 7.3% at the end in 28, 44, 54 and 72 h under the dryer with combined glass pieces and paraffin wax as NHERS, dryer with glass pieces as NHERS, dryer without NHERS and traditional sun drying respectively. The maximum thermal efficiency of the solar collector is determined to be 57.9% and the highest dryer efficiency is 67.2% in the same setup. The maximum exergy efficiency in the dryer with combined glass pieces and paraffin wax as NHERS is 53.7%. Moreover, ten drying models were employed to forecast the MR and the optimal model to describe red chillies drying properties wasthe logarithmic model with the lowest χ2 (0.0008843) and maximum R2 (0.9682) value. The colour of dried red chilli was best in the dryer with combined glass pieces and paraffin wax as NHERS. From these investigations, the developed indirect solar dryer with combined glass pieces and paraffin wax NHERS indicates sustainable drying time and improved product quality.