Performance investigation of newly developed novel hemispherical solar dryer for sustainable food preservation: Comparative analysis with traditional methods

To preserve the world’s food resources, drying agricultural products is crucial for prolonging their shelf life. A novel concept of 1.5 m hemispherical solar dryer surmounts the limitations of conventional dryers like long drying time, solar tracking, large space requirement etc. Trials were performed on Thomson grapes to convert into raisins. For the purpose of fair accuracy in comparison, experiments were conducted on hemispherical solar dryer (active and passive mode), traditional cabinet solar dryer as well as open sun drying (OSD) by maintaining the uniform test conditions. An average moisture removal rate of 0.1935096 kg/h was obtained in hemispherical dryer. The hemispherical solar dryer significantly reduced drying time for converging grapes into raisins to 13 days, compared to 18 days in a cabinet solar dryer and 19 days with OSD. The hemispherical dryer, through a gap, creates a greenhouse effect, reaching a 70.1 °C maximum temperature and an average of 60.7 °C at 796 W/m2 average solar energy. The hemispherical dryer attained a drying efficiency of 5.67 %. Six mathematical models were employed for hemispherical and cabinet dryers. Amongst these Two term and Wang & Singh models were found suitable for the experimental data and provided precise prediction of moisture ratio.