Paper 13: Experimental Investigation of Turbulent Heat Transfer in a Pipe Preceded by a 180° Bend

Abstract

The local values of the heat-transfer coefficient to water flowing turbulently in a pipe were measured for the following entry conditions:

1. (1)

A long hydrodynamic calming section.

(2)

One of three bends, having a radius 2, 3, or 4 times that of the pipe, and itself preceded by the calming section. The experiments covered a range of Reynolds numbers from 10 000 to 94 000 and heat fluxes from 5 to 50 W/cm².

The dependence of the local and average values of the heat-transfer coefficient on the Reynolds number, length of the pipe, ratio of the bend to pipe radius and variation of physical properties of the fluid with temperature, is analysed and discussed. Correlations are proposed for the local and average values of heat transfer in the entrance region of the pipe and for the heat transfer under the fully developed flow conditions.