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 flid (air) flwing inside the system. Th 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. Th aim of this study is to investigate the effct of process air mass flw rate on the thermal performance of a solar air heater working at diffrent operating conditions under the prevailing conditions of Tajoura-Libya. Experiments were conducted on specifid 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 aftrnoon. Th 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 flw rates leads to a corresponding decrease in the temperature at diffrent locations in the solar air heater. Furthermore, the average thermal effiency values of the solar air heater range from 35% to 65%. Average overall heat losscoeffient values tend to decrease with the day time. Finally, the present study results coincide with literature and show a good agreement.

Key words: Solar Air Heater, space heating, crops drying, thermal effiency, heat transfer coeffient