Investigation of the effect of porous media under the absorbent plate and thermal recovery on the efficiency of solar air heaters

In the present study, three types of solar air heaters for geographical location and climatic conditions of Kermanshah were analyzed numerically using fluent software. The analysis was carried out for the radiation intensity measured at different hours of July 15th and January 15th at two mass flowrates of 0.011 and 0.037 kg / s. The results show that the use of porous media below the adsorbent surface in double-pass solar air heaters increases the temperature difference and also increases thermal efficiency. The maximum temperature difference in double-pass solar air heater with porous medium was calculated at 13 o'clock at a mass flow rate of 0.011 kg / s and its value was 40.8 ° C. At the same solar air heater, the maximum thermal efficiency was calculated on July 15th at 1:00 pm at a mass flow rate of 0.037 kg / s and its value was 70%. In general, it can be concluded that the temperature difference and thermal efficiency in the single-pass solar air heaters with thermal recovery are less than double-pass heaters with porous medium and simple double-pass heaters.