EXPERIMENTAL STUDY OF HEAT TRANSFER FROM A DISCRETE SOURCE TO A CIRCULAR LIQUID JET WITH ANNULAR COLLECTION OF THE SPENT FLUID

Abstract

Experiments have been performed to determine average convection heat transfer coefficients for axisymmetric, liquid jet impingement, with annular collection of the spent fluid, Measurements were performed for a small, circular heater affixed diameter (D = 22.2 mm), but for a range of jet diameters (4.42 ≤ d ≤ 9.27 mm), nozzle-to-heater spacings (0.25 ≤ S/d ≤. 6), and confining wall diameters (22.2 ≤ Dc ≤ 38.1 mm). Two different liquids, water (Pr ≈ 7) and a dielectric fluorocarbon (Pr ≈ 25), were employed to study Prandil number effects, and flow rates were varied to provide laminar and turbulent jets over the Reynolds number range 1000 ≳ Red ≳ 40,000. The effect of nozzle-to-heater separation was found to be negligible for laminar jets, while, for turbulent jets, significant heat transfer enhancement could be realized by reducing the separation distance in the range S/d ≳ 1. The effect of the confining wall was discernible only for small values of Dc and was manifested by a reduction in heat transfer wit...