Abstract
An investigation has been made into the effect of a right angled pipe bend on the heat transfer from a hot air stream to cold pipe walls. Pipe bends of various curvatures have been studied and the internal pipe diameter has been maintained constant. Reynolds numbers in the turbulent, transitional and Streamline regions have been considered and the variation of heat transfer coefficient with Reynolds number is illustrated. The test section consisted of a pipe bend and upstream and down stream straight pipes. The pipe wall was at constant temperature and the heat flux varied. A complete heat flux survey of each test section has been carried out and local heat transfer coefficients over the length and around the periphery of the pipe have been calculated. Average heat transfer coefficients have also been determined. The results have been correlated by relating heat transfer coefficients to established friction factors for curved pipe flow. The following equations are recommended for calculating heat transfer coefficients for systems containing pipe bends.