High Improvement in Solar Heater Performance by Exploitation of Radiating Gas and Airfoil Shaped Ribs

Abstract

​A novel design of solar air heater (SAH) is proposed in this paper based on the simultaneous exploitation of radiating gas and also airfoil shaped ribs. Using participating gases with high radiative characteristics respect to the usual working-gas, namely air, could show a more promising improvement in thermal performance, especially while this technique is combined with the method of extending surface area with low pressure drop. This new concept is demonstrated by simultaneous solution of radiative transfer equation (RTE) considering both diffuse and collimated beams coupled with momentum, energy and continuity equations. The set of governing equations are solved using the finite element method (FEM) in a steady-state condition by the Comsol Multi physics. The well known model is used in calculations of turbulent stress and heat flux. Through the presented results, radiative gas clearly proved well its potent potentials to serve as future working-gas in solar gas heaters (SGHs) and its combination with the airfoil shaped ribs shows magnificent 88% thermal efficiency and gas outlet temperature up to 85 C in the test cases. The contribution of airfoil shaped ribs and gas radiation effect in increasing the thermal performance are computed equal to 10% and 67%, respectively.