Manzoor Ahmad

Improvement of Air Homogeneity in Paddy Dryer With Central Air Flow Channel

Abstract Air heterogeneity in the drying chamber of the batch-type dryer is a major problem because uneven air distribution within the drying chamber reduces the product quality and dryer efficiency. To surmount this problem, a new dryer with central air distribution model has been designed and developed. This is the distinct design feature of the dryer, which ensure the uniformity in the moisture content of the final dried paddy grains. ANSYS-Fluent (Computational Fluid Dynamics [CFD]) was used to predict the flow behavior of the air with respect to pressure and velocity within the drying chamber by applying actual boundary conditions and standard k−ε turbulence model. Pressure and velocity profiles in the drying chamber were determined using CFD to optimize the drying uniformity. An estimated value for velocity input was used and air distribution was found good. For the validation of simulation results several drying tests were performed at different dryer depths of 18, 36, 54 and 72 cm in the drying chamber. The drying results expressed as percentage moisture content reduction, along the length of the dryer and measured the uniformity in the drying rate. The drying curves for each depth showed high R2 value. Numerical simulation and experimental results showed that the newly developed solar-assisted paddy dryer is capable to produce uniform air distribution throughout the length of the drying chamber in the dryer for uniform and quality drying. This approach improved the overall performance of the solar-assisted paddy dryer.