Numerical Analysis Of A Solar Air Heater With Circular Perforated Absorber Plate

Numerical analysis of a solar air heater with perforated circular absorber plate is carried out to study the effect on the thermo-hydraulic performance due to the elimination of laminar viscous layer that otherwise exist in a conventional solar air heater. The study is conducted for configurations of the absorber plate consisting of 5 mm, 8 mm, 10 mm and 12 mm vent diameters and the number of vents is varied as, 24, 36 and 54. The numerical CFD analysis is conducted for Reynolds numbers ranging from 3000 to 21,000. The CFD analysis is evaluated against the experimental results. The average increase in the thermal efficiency of 23.33% is obtained for the configuration with 8 mm diameter vents and 36 number of vents compared to the base model without the absorber plate. The average increase in thermohydraulic efficiency is 21.78% higher for the configuration with 36 vents and a vent diameter of 8 mm compared to the base model. The highest thermohydraulic efficiency of 72.8% is obtained. The thermohydraulic efficiency of the collector is directly proportional to the increase in vent diameter. The study infers that the circular geometry and vented absorber plate causes vortex formation resulting in increase in turbulence induced heat transfer.