Solar drying system for energy conservation

Abstract

A low cost portable farm solar dryer was evaluated for drying goose berry candy in the conditions of Vidarbha region of Maharashtra state. Temperature profile at top, middle and bottom in its seven trays loaded with candy was studied with respect to ambient temperature during the course of drying and maximum solar radiation of 1120 W/m2 was observed at 11.30 to 12 h. The solar radiation was varied from 720–500 W/m2 at 9.00 h to 16.00 h. The minimum temperature of 27°C was observed at bottom tray of the dryer and maximum of 44°C in top tray at 9.00 h. The maximum temperature of 70°C was attained at 11.30 h. The conventional drying method took 8 days to dry the product. The moisture content was reduced from 36.38 to 8.33 per cent (wb) in three days in solar drying method. The product recovery was 71.55 per cent as compare to 35 per cent in conventional drying method. The drying period was reduced by 62 per cent and product recovery was doubled using portable farm solar dryer. The goose berry candy was also dried with and without shade drying methods. The temperature variation of dryer without shade was found, in the range of 23–36°C, 31–48°C and 38–55°C in bottom, middle and top trays respectively of dryer. The weight loss of 810, 870 and 820 g were observed in three days at bottom, middle and top trays of the dryer respectively. The thermal efficiency of the dryer onepy first day drying was found 15.55 and 15.23 per cent in shade and without shade drying methods respectively. Appearance, taste and flavour of goose berry candy dried in farm solar dryer with shade were superior to conventional drying. The cost of final product was Rs 114/kg. The profit from a single unit of farm solar dryer per year was Rs 57588/-.