Solar-wind ventilation to enhance the cabinet dryer performance for medicinal herbs and horticultural products

Abstract

This paper presents the design, construction and performance evaluation of a mixed-mode solar cabinet dryer (SCD) for medicinal herbs and horticultural products.  Solar- wind ventilation system is used to enhance the cabinet dryer performance.  The solar cabinet is equipped with a vertical blackened solar chimney and a flat plate solar collector to enhance buoyancy force.  The chimney is provided with suction axial fan that can rotate smoothly by wind power.  The performance of SCD was evaluated without load (empty) and with load (potato chips and peppermint).  After performing various standardized pretreatments, products were dried separately under open sun, SCD and electric oven.  Results of parametric studies indicated that, highest drying air temperature was achieved at 60° collector tilt angle followed by 30°, when the dehydration system tracked the sun.  The developed SCD exhibited sufficient ability to dry the chips and peppermint reasonably to a safe moisture level within 9-10 and 5-6 hrs (≈1 clear sunny day), respectively.  The best chips colour was achieved at 15 s frying time.  All the fried chips and dried peppermint were well accepted by the panelists.  The SCD ensures a superior quality of the dried products.  In terms of electricity requirement, frying time, health conscious and utilization of solar energy, the enhanced SCD is considered a suitable method for drying potato chips as well as peppermint.

Keywords: solar cabinet, solar collector, windmill, drying, chips, peppermint