Heat transfer in concentrated solar air-heaters filled with a porous medium with radiation effects: A perturbation solution

In this study, convection-radiation heat transfer in solar air-heater filled with a porous medium is investigated. The effects of porous media shape parameter (s), Forchheimer number (F) and radiation parameter (ζ) on the collector efficiency are discussed. Approximate analytical solutions for the dimensionless velocity, temperature, and Nusselt number are obtained using perturbation method. The radiation heat transfer has been modeled using the Rosseland approximation method. A discussion on the accuracy and limiting cases of the solution is represented and a good agreement has been found between the analytical solutions and previous works. The results showed that by increasing the radiation parameter, the efficiency of the collector was improved. Also, the collector heat removal factor enhances when the porous media shape parameter increases.