Investigation of the Effect of Porous Material on the Flow and Temperature Patterns of a Passive Solar Air Heater

Abstract

In this work, the effect of flow resistance due to the presence of porous medium representing agricultural products at the exit of free convection-based solar air heater is studied experimentally and numerically. An air heater, along with the drying chamber, is designed as an inclined channel to conduct the experiments. Constant heat flux condition is provided by electrical heating on the top absorber plate of the channel. Experiments are conducted for heat flux ranging from 250 to 750 W/m2 for the channel inclination angle of 30 deg. Porous material bed height is also varied in the drying chamber, while porosity is set at 0.36. The surface-to-surface radiation model is considered for modeling of heat transfer within the flow. For all the heat flux values considered in the experiments, numerical simulations are performed at three different angles of inclinations of 15 deg, 30 deg, and 45 deg. In this analysis, the temperature distribution in the channel wall, the flow pattern, the difference in the mass flowrate, and temperature of the outlet air are investigated with different heights of the porous medium.