MODIFICATION AND EVALUATION OF AN ELECTRIC DRYER FOR HIGH MOISTURE VEGETABLES
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Date
2018
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Engineering Science
Abstract
Food wastage resulting from lack of facilities for drying and the unhygienic methods of processing are major causes of food shortage in supply chain. Thus, to address these issues, an existing electric dryer was modified for drying high moisture vegetables. The machine was evaluated for drying tomatoes with an initial moisture content of 63% (wb). A heating element was attached below the fan of the dryer to allow a through air circulation instead of the cross air flow pattern of the previous design. Four trays, with each having a capacity of 0.092m 3 , were loaded with 30.4kg of slice tomatoes at a rate of 7.6kg per tray and dried for 5h. Thermostat was used to regulate temperature and relative humidity in the drying compartment at 42 o C and 11% RH. Control experiment was set up to determine the quality loss upon drying under sun for 5 h. Nutritional quality parameters of the dried products were determined using standard known methods. The results showed that actual volume of heated air delivered to the drying chambers, thickness of polyurethane used as lagging and power requirement for heating were 8.96m 3 , 38mm and 3000W, respectively. The nutritional quality loss in the sun dried samples was lower than the corresponding loss in the dryer. The modified dryer has 73% drying efficiency, which higher than the efficiency of the existing dryer.