Development of electrically heated dryer for turmeric
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Date
2020
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DRPCAU, Pusa
Abstract
An electrically heated dryer was designed and fabricated for turmeric drying for 25 kg capacity with five drying trays. The fabricated dryer has the dimensions of drying chamber as 102 × 53 × 57 cm, tray-100 × 50 × 5 cm and stand-102 × 53 × 70 cm. The procured turmeric lot was thoroughly cleaned, washed and trimmed to get rhizomes which were boiled and tempered in laboratory autoclave for total 220 minutes. After determining initial moisture content (82.19 % w.b.), turmeric rhizomes were evenly spread on five drying trays (5 kg in each tray) and were put inside the preheated dryer. The data were recorded for weight reduction in samples from each tray at prefixed time interval. Other observations included the inlet and outlet temperature of drying air, dryer temperature and RH at bottom tray 1 and top tray 5, ambient temperature and RH, air velocity and energy consumed during entire period of experiment. Drying was continued till three consecutive weights were recorded as almost same indicating the samples had reached at their equilibrium in different trays. Weight reduction data was used to calculate moisture content in wet and dry basis and drying rate. The performance of the dryer was evaluated on the basis of moisture reduction, drying rate, time taken for drying, heat utilization factor and dryer efficiency. Some important physical properties like size, shape, surface area & volume, bulk density, true density, porosity were also determined for fresh, boiled and dried turmeric rhizomes. The turmeric rhizomes were dried from initial moisture content of 82.19 % (w.b.) to final moisture content in the range of 8.22% in 1980 minutes, 10.07% in 2280 minutes, 12.96% in 2580 minutes,13.98% in 2820 minutes, 15.68% in 3120 minutes for tray 1, tray 2, tray3 ,tray4 and tray 5 respectively. Overall drying rate during the process varied from 0.172 × 10-3 to 0.086 × 10-3 kgW /kg.dm.h. The dryer had an average HUF of 0.842 during turmeric drying with drying efficiency of 33.483%. The total moisture content reduction (from initial to final moisture content) was found 73.97, 72.12, 69.23, 68.20 and 66.51(%w.b.) in tray1, tray2, tray3, tray4 and tray5 in 1980, 2280, 2580, 2820, and 3120 minutes respectively. During full load condition, the average temperature in the drying chamber was 56.45°C, which is near to the optimum temperature required for drying of turmeric rhizomes. It can be concluded that the developed system is suitable for drying of 25 kg/batch turmeric for the farming community with good quality.