Abstract: “Flat plate solar collectors of water heating and air heating types have been widely studied for variety of utilizations. Water heaters are mostly of water recirculation types, their thermal efficiency curves are represented with the conventional equations and methods. However, for solar air heaters, mostly being without recycling of air and which performance is very much mass flow rate dependent, the conventional equations and methods for evaluating and representing their performance become not so valid and useful. This papers represents and discusses the way of evaluation of performance of solar air heater of conventional and novel types together with the nature of performance curves obtained thereof”

Keywords: Thermal efficiency, performance parameters, plate efficiency factor, collector heat removal factor, fluid inlet and outlet temperature.