Numerical Study of Forced Convection Heat Transfer of Turbulent Flow in a Rough Tube

In this paper, forced convection heat transfer of turbulent flow was numerically investigated under uniform heat flux of the wall in a rough tube. Roughness element created in the upper half sector of a hemisphere and located as bump and dimple on the tube surface with regular arrangement. This roughness increases the heat transfer by a combination of flow turbulence enhancement, disturbing the boundary layer, and heat transfer enhancement. The governing equations are the continuity, momentum and energy equations which were discretized by finite volume method and second-order upstream difference scheme. The results showed that the convection heat transfer coefficient is increased by increasing Reynolds number and at Reynolds number6000, 8000, and 12000, the percent of increasing product of convection heat transfer coefficient in heat transfer surface of rough tube (i.e. hA) was 49٪ , 44٪ and 36٪, respectively compared to the smooth tube in which the share of increasing surface due to the effect of creating roughness was 11٪ and the rest of increases was related to the increasing flow turbulence and producing turbulence.

Keywords:

Roughness , forced heat transfer , turbulent flow , rough tube , Convective heat transfer coefficient , Reynolds number