Heat Transfer in Channels Having Rough and Smooth Surfaces

Abstract

The author proposes a method of comparing the heat transfer coefficients in two channels in which (1) the cross-sectional shape is different; (2) there are different proportions of rough and smooth surfaces; (3) there are different proportions of heated and unheated surfaces. In particular the method applies to experimental results for the system in which a roughened, heated cylinder is placed centrally in a smooth unheated pipe. The effective diameter concept is used to allow for changes in shape, and the heat-transfer boundary conditions are modified to make them similar to the fluid-flow boundary conditions before the comparison is made.