An experimental investigation of forced convection flat plate solar air heater with storage material

Abstract

Solar air heater is a heating device that uses the heated air in the drying of agriculture products and many engineering applications. The purpose of the present work is to study a forced convection flat plate solar air heater with granite stone storage material bed under the climatic conditions of Egypt-Aswan. Experiments are performed at different air mass flow rates; varying from 0.016 kg/s to 0.08 kg/s, for five hot summer days of July 2008. Hourly values of global solar radiation and some meteorological data (temperature, pressure, relative humidities, etc.) for measuring days are obtained from the Egyptian Meteorological Authority, Aswan station. Inlet and outlet temperatures of air from a solar air heater have been recorded. In this work, attempt has been made to present the temperature distribution in non-dimensional form that makes it useable for any region and not restricted to local conditions. The variation of solar radiation, air heater efficiency, Nusselt number, and temperature distribution along the air heater are discussed. Comparisons between the calculated values of outlet air temperatures, average air temperatures and storage material temperatures and the corresponding measured values showed good agreement. Comparison between current work and those in previous investigations showed fair agreement.