Transient heat transfer from a wire to a forced flow of subcooled liquid hydrogen passing through a vertically- mounted pipe

[摘要] Transient heat transfers from Pt-Co wire heaters inserted into vertically-mounted pipes, through which forced flow subcooled liquid hydrogen was passed, were measured by increasing the exponential heat input with various time periods at a pressure of 0.7 MPa and inlet temperature of 21 K. The flow velocities ranged from 0.3 to 7 m/s. The Pt-Co wire heaters had a diameter of 1.2 mm and lengths of 60 mm, 120 mm and 200 mm and were inserted into the pipes with diameters of 5.7mm, 8.0 mm, and 5.0 mm, respectively, which were made of Fiber reinforced plastic due to thermal insulation. With increase in the heat flux to the onset of nucleate boiling, surface temperature increased along the curve predicted by the Dittus-Boelter correlation for longer period, where it can be almost regarded as steady-state. For shorter period, the heat transfer became higher than the Dittus-Boelter correlation. In nucleate boiling regime, the heat flux steeply increased to the transient CHF (critical heat flux) heat flux, which became higher for shorter period. Effect of flow velocity, period, and heated geometry on the transient CHF heat flux was clarified.

[发布机构] J-PARC Center, Japan Atomic Energy Agency, Tokai-Ibaraki, Japan^1;Department of Energy Science and Technology, Kyoto University, Kyoto, Japan^2;Institute of Space and Astronautical Science, JAXA, Kanagawa, Japan^3

[效力级别] 物理学 [学科分类] 材料科学（综合）

[关键词] Boelter correlation;Inlet temperature;Onset of nucleate boiling;Steady state;Subcooled liquid;Surface temperatures;Time-periods;Transient heat transfer