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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

STUDY ON HEAT TRANSFER CHARACTERISTICS OF LOW-TEMPERATURE SUPERCRITICAL NITROGEN IN A VERTICAL MINI-TUBE

Get access (open in a dialog) DOI: 10.1615/IHTC16.cov.022674
pages 3295-3303

摘要

Forced convection and heat transfer of cryogenic fluids in small channels has been paid a lot of attentions in applications such as liquid-hydrogen rocket engine and superconductor cooling. In many of the operating conditions, the cryogenic fluids are at supercritical states with distinctive thermophysical properties, e.g. compressibility, specific heat and viscosity, and those properties can have significant impact on the flow and heat transfer characteristics. In this paper, we carry out numerical simulations on the forced convection of low-temperature supercritical nitrogen in a vertical mini-tube. The heat transfer behavior of nitrogen near pseudo-critical point is investigated under different conditions such as the ratio of heat flux to mass flow rate, inlet pressure and flow direction. It is found that the variations of the thermal properties significantly impact the heat transfer. In the vicinity of pseudo-critical point, heat transfer coefficient grows rapidly with the dramatic increase of specific heat. The heat transfer coefficient can reach as high as 8000 W/m2K when inlet pressure is 3.5 MPa. The fluid density decreases fast during the transition to supercritical fluid, which subsequently results in large density difference as well as the gravity effects At the inlet pressure of 3.5 MPa, peak point of heat transfer coefficient with gravity effects happened later than that without gravity effect.