Heat transfer characteristics of liquid hydrogen flowing inside of a vertical heated pipe under quasi-stationary heat input

• Published in: Cryogenics (Guildford) Vol. 113; p. 103230
• Main Authors: Shirai, Yasuyuki, Shiotsu, Masahiro, Matsumoto, Taito, Kobayashi, Hiroaki, Naruo, Yoshihiro, Nonaka, Satoshi, Inatani, Yoshifumi
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2021
• ISSN: 0011-2275; 1879-2235
• DOI: 10.1016/j.cryogenics.2020.103230

•Heat transfer of liquid hydrogen flowing inside a heated pipe was measured.•Tests were performed under at various pressures, temperatures and mass flow rates.•Test results from non-boiling, nucleate, DNB and to film boiling were obtained.•Calculation code of the DNB heat flux and post DNB heat transfer was presented.•The calculated results are in good agreement with the experimental results.•This code can predict the heat transfers with various pressures and flow velocities. Heat transfer from inner surface of a vertical heated pipe to subcooled or saturated liquid hydrogen flowing upward was measured for quasi-steadily increasing heat input up to fully developed film boiling regime and decreasing the heat input through the film boiling regime. The experiments were carried out at the inlet pressures of 400, 700 and 1100 kPa and subcoolings from 0 K to 11 K. Three test pipe heaters made of SS310S with inner diameters of 6 and 8 mm and lengths of 100 and 200 mm were used. Experimental data from non-boiling to developed film boiling and developed film boiling down to minimum film boiling was obtained with the record of mass flow rate by continuously increasing and decreasing the heat input. It was observed that though the mass flow rate decreases with the increase of the heat generation rate, the heat transfer coefficient increases. Discussions on heat and mass transfer in inverted annular flow, dispersed droplet flow, single-phase vapor flow regimes and their changing conditions from one by one were carried out to clarify the phenomena. A calculation code of heat transfer characteristics was developed based on the discussions. The calculated results are in good agreement with the experimental results.