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International Heat Transfer Conference 13

ISBN Imprimir: 1-56700-226-9 (CD)
ISBN En Línea: 1-56700-225-0

BOILING HEAT TRANSFER ENHANCEMENT BY SPRAY COATING SURFACE (EFFECT OF GRAVITY ON POOL BOILING HEAT TRANSFER)

DOI: 10.1615/IHTC13.p28.500
page 9

Hitoshi Asano
Kobe University, Department of Mechanical Engineering 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan

K. Akita
Department of Mechanical Engineering, Kobe University, Kobe, Japan

Terushige Fujii
Department of Mechanical Engineering, Kobe University, Kobe, Japan

Sinopsis

This study deals with heat transfer enhancement surface manufactured by thermal spraying. Two thermal spraying methods using copper as a coating material, wire flame spraying (WFS) and vacuum plasma spraying (VPS), were applied to the outside of copper cylinder with 20 mm OD. The surface structure by WFS was denser than that by VPS. The heat transfer performance around the horizontal tubes under microgravity was evaluated in pool boiling experiments with HCFC123 for heat fluxes between 1.0 and 160 kW/m2 and saturation temperature of 30 °C. The microgravity experiments were carried out during a parabolic flight of an airplane. As a result, the surface by VPS produced higher heat transfer coefficient and lower superheat at boiling incipiency under microgravity. For the smooth surface, the effect of gravity on boiling heat transfer coefficient was a little. For the coated surface, a large difference in heat transfer characteristics to gravity was observed in the moderate heat flux range. That is to say, heat transfer was deteriorated by the change from the normal gravity to hyper-gravity, and was improved by the change from the hyper-gravity to microgravity. The difference in heat transfer coefficient was a little between the normal gravity and microgravity.

IHTC-13 Digital Library

Measurement of fluid temperature with an arrangement of three thermocouples FLOW BOILING OF A HIGHLY VISCOUS POLYMER SOLUTION