Abstract: Three dimensional simulations of the single-phase laminar flow and forced convective heat transfer of water in round tube and round microchannel heat exchangers were investigated numerically. This numerical method was developed to measure heat transfer parameters of round tube and round microchannel tube geometries. Then, similarities and differences were compared between different geometries. The geometries and operating conditions of those indicated heat exchangers were created using a finite volume-based computational fluid dynamics technique. In this article, at each Z-location variation of dimensionless local temperature, non-dimensional local heat flux variation and dimensionless local Nusselt number distribution along the tube length were compared between round tube and round microchannel heat exchangers. Consequently, averaged computational Nusselt number was obtained for those indicated models and then validation study was performed for round tube counter flow type heat exchanger model. Finally, all of these numerical results for both kind of geometries in counter flow heat exchangers were discussed in details
