This work presents the configuration optimization of a typical square roughness in a circular tube for laminar heat transfer in air using computational fluid dynamics (CFD) modelling. Conjugate heat transfer 2D numerical model has been developed and successfully carried out. CFD numerical simulations were carried out to analyze the flow and heat transfer in the air duct of a solar air heater provided with rectangular ribs. The laminar flow model is used for formulation, since the flow is laminar. A two-dimensional non uniform grid was generated, in order to critically examine the flow and heat transfer in the inter-rib region. The effects of Reynolds number, Nusselt number, friction factor, convective heat transfer coefficient is examined and discussed. The using of artificial roughness supplies considerable increase on heat transfer and pressure drop when compared with the literature. The Nusselt number increases with the increase of Reynolds number. This result is useful for the design of solar thermal heaters and heat exchangers. Keywords: Laminar Flow, Forced Convection, Heat Transfer Enhancement, Artificial Roughness
