Atransient analytical model was presented by Aboul-Enein et al., for aflat-plate solar air heater with and without thermal storage. Assuming the flowing air temperature to vary with time and space coordinates, the effects of design parameters of the air heater such as length, width, gap spacing between the absorber plate and glass cover, mass flow rate and thickness and type of the storage material (sand, granite and water ) on the outlet and average temperatures of the flowing air were studied.