Laminar Flow Heat Transfer to a Gas With Large Temperature Differences

Abstract

This paper contains the results of three experiments on laminar gas flow heat transfer with moderately large temperature differences. The cases considered are laminar flow inside a circular tube with heating, with cooling, and flow normal to a circular tube with heating. All experiments were performed with air. Temperature ratios up to 1.9 were used in the experiments with flow inside a circular tube, and up to 3.0 in the flow normal to a circular tube experiment. In the laminar internal flow experiments it was found that the constant property thermal entry length solutions of Sellars, Tribus, and Klein [7], and Siegel, Sparrow, and Hallman [8] are accurately applicable to a gas with temperature ratios up to 1.9 if all fluid properties are evaluated at local mixed mean temperature. For flow normal to a circular tube with heating, the constant properly experimental correlations appear to be applicable to gas flow for temperature ratios up to 3.0 if fluid properties are evaluated at free stream temperature.