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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

EXPERIMENTAL INVESTIGATION OF SUPERCRITICAL PRESSURE CO2 FLOW AND HEAT TRANSFER INSTABILITY IN VERTICAL TUBE

Get access (open in a dialog) DOI: 10.1615/IHTC16.cov.022567
pages 2783-2806

Аннотация

Convection heat transfer of CO2 at supercritical pressures in a 1.0 mm diameter vertical tube was investigated experimentally for upward flows. The mass flux was in the range of 237 kg/(m2·s) to 481 kg/(m2·s), Reynolds number was in the range of 3300 to 6800, and the heat flux between 27kW/m2 to 200kW/m2. The pressures were 7.7MPa, 8.6MPa and 9.6MPa. The drastically variation of thermal properties, buoyancy effect affect the convection heat transfer of supercritical pressure CO2 in the vertical tube, heat transfer deterioration and heat transfer instability phenomenon was occurred under the experimental conditions. With the increase of heat flux under the pressure of 7.7MPa and 8.6MPa, the heat transfer by deterioration to instability and then recovery. A heat transfer instability interval was observed with the heat flux in the range of 98kW/m2 to 131kW/m2 under the pressure of 7.7MPa. For the heat flux of 121kW/m2, there also exist a mass flow rate interval occurs heat transfer instability phenomena under the pressure of 7.7MPa. The Bo* number closed to 1.2×10-6 is the characteristic of the heat transfer instability phenomenon. A stability map was given for supporting further investigate by the nonlinear dynamic theory.