CFD based analysis of heat transfer enhancement in solar air heater provided with transverse rectangular ribs

A numerical analysis of convective heat transfer enhancement in solar air heaters with artificially roughened absorber is presented in this paper. CFD numerical simulations were carried out to analyze the flow and heat transfer in the air duct of a solar air heater provided with transverse rectangular ribs. The air flows in forced convection and the absorber is heated with uniform flux. Since the flow is turbulent, we used the RANS formulation to model the flow. We solved continuity, momentum and energy equations in turbulent mode using four closure models: k-epsilon RNG, k-epsilon RZ, k-omega Standard, k-omega SST. A two-dimensional non uniform grid was generated according to used geometry, with local refining near the wall, in order to critically examine the flow and heat transfer in the inter-rib region. The effect of major parameters (Reynolds number, Nusselt number, friction factor, global thermohydraulic performance parameter ... etc) is examined and discussed. The results obtained are concordant to those found in the literature and shows clearly the heat transfer enhancement without big penalty of friction losses. (C) 2014 Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.ore/liccns cs/by-nc-nd/3.0,1). Selection and peer-review under responsibility of the Euro-Mediterranean Institute for Sustainable Development (EUMISD)