Performance Evaluation of Indirect Solar Dryer under Passive and Active Modes during Drying Beetroot Slices

Abstract

In the present work, the drying characteristics of beetroot slabs, thermal and performance characteristics were estimated and analyzed in passive (mode-A) and active (mode-B) indirect solar dryers (ISD). The conventional mode-A dryer was updated with a diverging duct that comprises direct current fans run by photo-voltaic panels to make the mode-B dryer. In mode-B, the drying time of 16.67 and 42.31% is saved compared to mode-A and open sun drying (OSD), respectively, to achieve a final moisture content of 0.057 from 7.7535 kg/kg of dry basis. The Two-term exponential model was observed to be a perfect fit model for beetroot slices in both modes of ISD and OSD, respectively. The improvements in drying rate, dryer and collector efficiencies and specific moisture extraction rate in mode-B over mode-A are found to be 19.97, 19.18, 8.34 and 14.23%, respectively. It is found that mode-B has better thermal and performance properties than mode-A.