Energy Efficiency of Paddy Dehydration Process using Vortex Dryer
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Abstract
Vortex dryer is a novel drying process for drying high-moisture particulate materials such as freshly-harvested paddy or drowned paddy. However, studies of the performance and energy efficiency of the vortex dryer are still incomplete. In this study, a vortex dryer was constructed and study the overall performance in terms of the volumetric water evaporation rate, volumetric heat transfer coefficient, mean particle residence time and specific energy consumption of the dryer was investigated. The drying chamber of the dryer has a diameter of 240 mm, a width of 84 mm, a height of the air inlet of 24 mm and has the chimney outlet diameter of 72 mm. Then, drying the paddy with the initial moisture content of 22% (d.b.) at various drying parameters, namely the drying temperature, the particles feed rate and the constant inlet air velocity of 50 m/s. It was found that the constructed vortex dryer could reduce the moisture content of paddy by 3.63 to 8.87% (d.b.) and the lowest final moisture content of paddy was found to be around 13.20% (d.b.). For the maximum volumetric water evaporation rate was found to be around 475.86 kgwater/m3 h and the maximum volumetric heat transfer coefficient was found to be around 4,190.79 W/m3 ºC. In the case of the mean particle residence time it was found that the mean particle residence time was in the range of 14.07 to 19.17 s. For the total specific energy consumption of the vortex dryer it was found that the lowest total specific energy consumption was to be around 5.6 MJ/kgwater at a drying temperature of 160ºC and a particles feed rate of 70 kgdry solid/h.
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References
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