Heat transfer during transient cooling of high temperature surface with an impinging jet |
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Authors: | Y Mitsutake M Monde |
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Institution: | (1) Department of Mechanical Engineering Saga University, 1 Honjo Saga City Saga 840-8502, Japan, JP |
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Abstract: | An experimental study of transient boiling heat transfer during a cooling of a hot cylindrical block with an impinging water
jet has been made at atmospheric pressure. The experimental data were taken for the following conditions: a degree of subcooling
of ΔT
sub = 20–80 K, a jet velocity of u
j
= 5–15 m/s, a nozzle diameter of d
j
= 2 mm and three materials of copper, brass and carbon steel. The block was initially and uniformly heated to about 250 °C
and the transient temperatures in the block were measured at eight locations in r-direction at two different depths from the surface during the cooling of hot block. The surface heat flux distribution with
time was evaluated using a numerical analysis of 2-D heat conduction. Behavior of the wetting front, which is extending the
nucleate boiling region outward, is observed with a high-speed video camera. A position of wetting region is measured and
it is correlated well with a power function of time. The changes in estimated heat flux and temperature were compared with
the position of wetting region to clarify the effects of subcooling, jet velocity and thermal properties of block on the transient
cooling.
Received on 17 March 2000 |
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Keywords: | |
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