Radiant and convective heat transfer for flow of a transparent gas in a short tube with sinusoidal wall heat flux

Abstract

The present analysis accounts for combined convective and radiant heat transfer to a fluid flowing in a short tube with prescribed wall heat flux. The heat flux distribution used was of sine shape with maximum at the middle of the tube. This solution is known to represent the axial power variation in a nuclear reactor core. The tube wall and gas bulk temperatures were obtained by successive substitutions for the wall and gas energy balance equations. The integrals were approximated by Sympson's rule and initial guesses for the iterative process were based upon limiting cases for pure radiation and pure convection. The results of the combined solution compared with the pure radiation approach show a decrease of 30 percent for the maximum wall temperature using black surface (ε=1). For this same situation, the increase in the gas temperature along the tube shows a reduction of 58 percent when compared to the pure convection solution. © 1985.