The recent studies on thermal performance enhancement of the flat plate solar air collectors are critically reviewed primarily regarding the absorber surface modifications, multiple-passes of air, porous absorbers, air-jet impingement on absorber surface, integration of heat storage materials, dual-purpose hybrid collectors and hybrid photovoltaic/thermal solar collectors. The formation of a laminar viscous layer over the surface causes poor heat transfer to airflow. Enhanced heat transfer surface area and residence time of air are vital factors for heat transfer augmentation using baffles, turbulators, roughness, and obstacles. The streamwise pitch ratio of the jet plate has the maximum contribution to friction and, subsequently, the heat transfer. The thermal efficiency of finned and porous absorber varies from 71.4% to 93%. The integration of phase change material and fins with solar air collector enhance daily thermal efficiency by 0.1%–4%, increasing further with honeycomb and porous structures. The application of agriculture waste as sensible heat storage material is an effective alternative to replace conventional materials. Electrical and thermal efficiencies of hybrid solar collector increased with the addition of thermal energy storage by 9% and 5%, which further enhanced by 3% with the addition of fins into the phase change materials. Thermo-economic performance of the dual-purpose collector and hybrid photovoltaic/thermal solar air collector is comparatively cost-effective with environmental benefits. This review article provides an insight into the recent critical findings on the thermal performance enhancement of the flat plate solar air collector to stimulate further developments towards the betterment of sustainable development.

A review on recent developments in thermal performance enhancement methods of flat plate solar air collector

Jin Liu

Papers

Evaluation of the performance of an improved solar air heater with “S” shaped ribs with gap