Effect of Stepped Arrangement of Metal Foam for Enhancement of Heat Transfer in a Commercial Solar Air Heater

A thermo-hydraulic performance study is proposed on a rectangular channel type single-pass solar air heater under forced convection situation. The novelty of the present study considers a stepped type arrangement of porous copper metal foam placed in a horizontal position with varying distances from the absorber plate and glass. The porosity, viscous resistance, and inertial resistance of the copper metal foam are 0.92, 6,082,725.06, and 148.97, respectively. A three-dimensional computational analysis is performed in ANSYS fluent software to analyze temperature distribution, heat transfer coefficient, friction factor, and performance parameter of the solar air heater. The Reynolds number considered for this study ranged between 4401 and 5868. The Rosseland radiation local thermal equilibrium model and Renormalization group k-ε viscous model with enhanced wall function is selected for simulations. The arrangements of metal foams in stepped type are classified as case “a”–“h” with respect to varying distances from the glass and the absorber plate. In this study, case “a” is empty channel, case “b” is 30 mm equal step size of 500 mm length, and case “c,” “d,” “e” are 20, 40, and 60 mm above the absorber plate with 25, 20, and 15 mm equal step sizes, respectively. Case “f,” “g,” “h” are 20, 40, and 60 mm below the glass with 25, 20, and 15 mm equal step sizes, respectively. Among the arrangements evaluated, case “e” emerged as the most effective option, demonstrating an 8.15% increase in temperature and a 77.80% improvement in the heat transfer coefficient compared to an empty channel. Additionally, the friction factor for case “e” is 86.70% lower, while its performance factor is 86% higher than the average performance factors of cases “b” through “h.” Therefore, the superior performance of case “e” can be attributed to its higher heat transfer coefficient and lower friction factor, making it the most efficient choice among all cases examined.