Experimental Investigation of the Thermal Performance of a Solar Air Heater

Abstract

Solar air heaters are widely used in many low temperature applications such as space heating, crops drying, desalination..etc. It collects solar radiant energy and transforms it into heat through a fluid (air) flowing inside the system. The outside cold air is heated through the system and delivered to the required application. It is simple, economic and clean. In this study, an experimental investigation is carried out using a test-rig installed at the laboratories facility for Center of Solar Energy Research and Studies (CSERS) in Tajoura-Libya equipped with all necessary measuring instruments and devices. The aim of this study is to investigate the effect of process air mass flow rate on the thermal performance of a solar air heater working at different operating conditions under the prevailing conditions of Tajoura-Libya. Experiments were conducted on specified days in August 2019, October 2019 and January, 2020.Results show that there is a noticeable increase in the air temperatures of the solar air heater as incident solar radiation values increase during the day time, especially at afternoon. The maximum average outlet air temperature measured reaches 60 oC which is suitable for space heating and crops drying applications. Useful heat energy collected is directly proportional to the incident solar radiation. Increasing air mass flow rates leads to a corresponding decrease in the temperature at different locations in the solar air heater. Furthermore, the average thermal efficiency values of the solar air heater range from 35% to 65%. Average overall heat loss coefficient values tend to decrease with the day time. Finally, the present study results coincide with literature and show a good agreement.