Enhancement of Forced Convection Heat Transfer Using Turbulence Promoters with Clearance Between Heat Transfer Surface

Abstract

This study is a part of a research program whose objective is to determine an optimum way of enhancing forced convection heat transfer using turbulence promoters. Effectiveness of turbulence promoters with clearance between the heat transfer surface is tested. Flow friction and heat transfer coefficients are measured at Reynolds numbers ranged from 1.5×10⁴ to 9×10⁴. Inclination of the rib plate used as a promoter is also varied in addition to the variation of clearance. The result of performance evaluation suggests that a turbulence promoter with clearance and inclination shows a slight improvement of performance in the case where the clearance is small. A possible reason that such a type of turbulence promoter does not show much improvement in its performance characateristics may be the considerable reduction of the local heat transfer rate around the region where the separated flow reattaches.