Design, development and performance evaluation of drying cum storage bin for paddy (Oryza sativa L.)
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Date
2018-06
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The present study entitled, “Design, development and performance evaluation of drying cum storage bin for paddy (Oryza sativa L.)” was conducted in the department of Post-Harvest Process and Food Engineering, G.B.P.U.A.T, Pantnagar, Uttarakhand during 2016-18. Cereals such as rice, wheat and maize are particularly important to humans because of their role as staple food crops. India is the second largest producer of food grains globally. The principal food grain of India is rice. While fulfilling the food demand of an increasing population remains a major global concern, more than one-third of food is lost or wasted in postharvest operations. As much as 50 to 60 % cereal grains are lost during the storage stage due to the lack of technical efficiency, rice facing the highest loss. Therefore, an effort was made to develop a drying cum storage bin for paddy where heated air was supplied to the grain bulk from a central perforated duct. A temperature sensor, digital controller and air exhaust valve regulates the temperature and air flow rate in the bin. The air passes horizontally through the grain bulk taking up the moisture and moves towards the perforated walls of the bin and proceeds towards the exhaust. Drying experiments were conducted to analyse the drying characteristics of paddy and thereby evaluate the performance of the dryer. Paddy was dried from 18 % moisture content (wb) to 12 % moisture content (wb). A full factor design with two independent variables at three levels was used for conducting the experiments. The independent variables selected were drying air temperature (35, 40 and 45 °C) and air flow rate (15, 21 and 27 m3/h). The total drying time (h), effective moisture diffusivity (m2/s), heat transfer coefficient (W/m2K) and specific energy consumption (kJ/kg) were determined. The data from all 9 experiments were analysed using Design Expert 10.1.1.0 and the response functions were developed using multiple regression analysis. There was minimum variation in the drying data of the top and bottom basins showing that the drying occurred uniformly throughout the depth of the bin. The optimum level of variables for maximum desirability of cross flow aerated paddy drying were 45°C temperature and 27 m3/h air flow rate. The optimum values of responses were 1.51 hours of drying time, 6.05x10-7 m2/s of effective moisture diffusivity, 0.078 W/m2K of heat transfer coefficient and 823537.1 kJ/kg of specific energy consumption. Significant (p<0.05) effect of process parameters were found in all responses. On validation of the model for drying of paddy, it was found that the developed model was accurate as the prediction error was only in the range of -1 to 9.58 %
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