Experimental and numerical investigation of solar air collector with different porous media obstructions

This work concerns improving thermal efficiency by investigating the experimental and numerical investigation of thermal performance of different types of balls with high and low thermal conductivity (glass and stainless steel balls) as packed beds in the second channel of the collector. The porous media is attached in the lower channel in order to enhance the heat transfer characteristics of the flow. Value of porosity, solar radiation, mass flow and conductivity are studied. Turbulent flow is implied for continuity, momentum and energy equations of the flow through solar air collectors. Novel CFD application using FORTRAN language was applied, the cells blocked as solid with porosity value. The results show that the thermal efficiency increases with increase in mass flow rate, while the exit temperature decreases for high mass flow rate. The maximum thermal efficiency was achieved with higher thermal conductivity (stainless steel balls) which reached 85.9% at porosity 33.5% while; it reached 76.02% with glass balls at porosity 42.8%. The decrease in porosity increased efficiency. The efficiency with stainless steel balls and glass balls as porous media reached 62 and 45% higher than without porous media.