Abstract:

Abstract. Reynolds number is one of the most important parameters in investigation of heat transfer in double tube heat exchangers. In this paper, the effect of this parameter has been investigated on the convective heat transfer coefficient and surface friction coefficient of the wall. Turbulent forced convection heat transfer of nanofluid flow of Al2O3 /water in a double tube heat exchanger with rough tubes in the annular portion was numerically studied. The finite volume method and the second-order upstream difference scheme were used for the discretization of the governing equations. The volume fraction and mean diameter of nanoparticles were assumed to be 4% and 32 nm, respectively. After reviewing the results, it was observed that the convective heat transfer coefficient in the outer and inner walls of heat exchanger increases with the increase of the Reynolds number. The wall surface friction coefficient, which decreases by increasing Reynolds number, is another examined parameter.

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