Local Heat Transfer Coefficient Distribution on a Ribbed Surface

Abstract

The present study deals with the local heat transfer of ribbed surfaces. The whole ribbed surface is divided into six subregions according to different flow patterns over the subregions. They include separated and redevelopment regions on the base surface between ribs with a large rib pitch and cavity region on the base surface with small rib pitch, front, top and back regions on the rib surface. The local heat transfer coefficient in those subregions have been experimentally investigated over a wide range of Re ( = 3 × 103 − 1 × 105), hp/De ( = 0.0324 − 0.174), p/hp ( = 2.5 − 60) and qp/qb ( = 0.5 − 2.5). The relationship between the local Nusselt number and these parameters are discussed and empirical correlations for the local Nusselt number are proposed. Experiments are performed with a rectangular test duct having a smooth upper and ribbed lower wall. Air of atmospheric pressure and room temperature was used as the working fluid.