| Abstract: | This investigation is concerned with the design and performance of a flat-type solar air heater in which air flows perpendicularly from the transparent cover to a porous absorber plate. The design phase involved a stability analysis to determine the critical distance (maximum allowable distance) between the absober and transparent cover, for suppressing convection currents, at various environmental and operating conditions. These results are useful to designers of solar collectors of the proposed type. In addition, the thermal performance of this solar heater at its optimum design conditions was computed for a wide range of system parameters illustrating the contribution of conduction and radiative modes of heat transfer. The results indicate that the best operating efficiency can be obtained when running the collector with a mass flow rate of m > 40 kg/m2.h. Furthermore, the collector thermal performance is superior than channel type solar air heaters operating under similar conditions and much simpler than honeycomb porous bed solar air heaters. |
