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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Heat transfer of supercritical carbon dioxide flowing in heated horizontal and vertical miniature tubes

Get access (open in a dialog) DOI: 10.1615/IHTC12.1420
6 pages

Abstract

Turbulent heat transfer of supercritical carbon dioxide flowing in heated horizontal and vertical miniature circular tubes have been investigated experimentally. Three stainless steel circular tubes having inside-diameters of 0.7 mm, 1.4 mm, and 2.16 mm were tested. Measurements were carried out for the pressures ranging from 74 to 120 bar , the temperatures ranging from 20 to 110 °C, and the mass flow rates ranging from 0.02 to 0.2 kg/min. The corresponding Reynolds number and Prandtl number ranged from 104 to 2×105 and from 0.9 to 10, respectively. It is found that the buoyancy effect appeared to influence the heat transfer of supercritical carbon dioxide flowing in miniature tubes even at Reynolds numbers up to 105. The experimental results reveal that near the pseudocritical point the heat transfer performance in a downward flow was deteriorated significantly compared to that in a horizontal flow and an upward flow, and compared to that of constant property fluids. The experimental results also indicate that the Nusselt number decreased with the reduction in tube diameters.