Experimental ginger drying by a novel mixed-mode vertical solar dryer under partial and fully loaded conditions

Abstract

An innovative and compact mixed-mode vertical solar dryer (MVSD) with a circular solar collector is developed and tested for ginger slices drying under partial and fully loaded conditions. Ginger slices samples of 4, 5 and 6 mm thick were used for natural convective drying in MVSD under partially loaded condition. The thickness of the ginger slices was observed to affect the performance of the MVSD. The drying rate and thermal efficiency were observed to be highest for 5 mm thick ginger slices sample under partially loaded condition. The MVSD was further tested with full loading capacity for 5 mm thick ginger slices drying under natural and forced convection modes (NC and FC modes). The drying behavior of ginger slices was well described by Midilli-Kucuk model. Heat transfer coefficients and efficiency (thermal and exergy) were observed to be higher under forced convection mode. Embodied energy and energy payback time were observed as 554.44 and 585.53 kWh; and 2.85 and 2.99 years under NC and FC modes, respectively. The values of annualized capital cost and payback period were observed as INR 389.41 and 408.17; and 1.85 and 6.86 years under NC and FC modes, respectively. The quality of the ginger dried under FC mode was found comparatively better than that of under NC mode.