Numerical Investigation of the Performance of a Solar Air Heater Equipped with Packed Beds

In this work, a numerical study based on pore-scale CFD analysis has been carried out on a solar air heater equipped with intermittent packed beds. Hydraulic and thermal characteristics of the air were determined by testing a range of mass flow rates and various collector configurations, including one (SAH-M1), two (SAH-M2), and three (SAH-M3) packed beds. After the validation of the numerical simulations with general correlations, results showed that as the number of packed zones increases, the total pressure drop grows. As a result, the maximum pressure drop was obtained as 115 kPa for the collector with three packed zones, operating at Re ~ 1.3 × 105. Detailed thermal analysis proved that the intermittent integration of packed beds has the potential to also increase the heat transfer exchange between each packed zone, improving the convection by 25% in the second zone to the first zone and 35% in the third zone to the second zone at Re ~ 1.3 × 105. This enhancement effect can be attributed to the increase in the turbulence conditions of the fluid regime from one bed to the other. Evaluating the effects of design parameters showed that the bed spacing could not change the thermo-hydraulic characteristics significantly, while particles’ randomness may only affect the pressure drop by 13%.