Determining solid-fluid interface temperature distribution during phase change of cryogenic propellants using transient thermal modeling

• Published in: Cryogenics (Guildford) 2018-04, Vol.91, p.103-111, Article 103
• Main Authors: Bellur, K., Médici, E.F., Hermanson, J.C., Choi, C.K., Allen, J.S.
• Format: Article
• Language: English
• Subjects: Contact line evaporation; Contact resistance; Cryostat; Electric resistance; Heat exchange; Helium; Iterative methods; Liquid hydrogen; Liquids; Low temperature physics; Mathematical models; Phase change; Phase transitions; Propellants; Sample holders; Space missions; Temperature; Temperature distribution; Temperature gradients; Thermal analysis; Thermal cycling; Thermal energy; Transient thermal model; Ultrasonic testing; Wall temperature; Wall temperature distribution
• ISSN: 0011-2275; 1879-2235
• DOI: 10.1016/j.cryogenics.2018.02.009

•Transient thermal transport in a cryostat.•Accurate prediction of transient and steady-state temperatures.•Material constants isolated from contact resistances.•High resolution inner wall temperature distributions. Control of boil-off of cryogenic propellants is a continuing technical challenge for long duration space missions. Predicting phase change rates of cryogenic liquids requires an accurate estimation of solid-fluid interface temperature distributions in regions where a contact line or a thin liquid film exists. This paper described a methodology to predict inner wall temperature gradients with and without evaporation using discrete temperature measurements on the outer wall of a container. Phase change experiments with liquid hydrogen and methane in cylindrical test cells of various materials and sizes were conducted at the Neutron Imaging Facility at the National Institute of Standards and Technology. Two types of tests were conducted. The first type of testing involved thermal cycling of an evacuated cell (dry) and the second involved controlled phase change with cryogenic liquids (wet). During both types of tests, temperatures were measured using Si-diode sensors mounted on the exterior surface of the test cells. Heat is transferred to the test cell by conduction through a helium exchange gas and through the cryostat sample holder. Thermal conduction through the sample holder is shown to be the dominant mode with the rate of heat transfer limited by six independent contact resistances. An iterative methodology is employed to determine contact resistances between the various components of the cryostat stick insert, test cell and lid using the dry test data. After the contact resistances are established, inner wall temperature distributions during wet tests are calculated.