Effect of Air Inlet Opening on Air Flow Rate and Drag Force of an Active Indirect Mode Solar Dryer

Abstract

The effect of air inlet opening on air flow rate and drag force of an active indirect mode solar dryers was examined. This was done in line with studies which suggested the air flow rate and drag force is affected by the air inlet area of the dryer. The air flow rate of the dryer was obtained as product of the air inlet area and velocity. The shaped of the inlet chosen were: square, rectangular, circular and triangular. The air inlet area was calculated based on the dimension and shape of the inlet. The experimental design adopted (Central Composite Rotatable Design of Response Surface Methodology gave a total of 52 runs for each experiment. The volumetric air flow rate of the dryer increased with increase in air inlet area. The values obtained ranged from 0.0006 to 0.0256 N. The air inlet area of an active indirect mode solar dryer should be increased based on the size of the dryer, to ensure efficient flow of air into the dryer, to fast track drying. The drag force increased with increase in air inlet area. The values obtained ranged from 0.0007 to 0.502 N, as the air inlet area increased across the various shape orientations. The air inlet area of an active indirect mode solar dryer should be increased based on size of the dryer, to enable the blower sufficiently drags air and circulate within the dryer for faster drying of the product.