A new experiment for investigating evaporation and condensation of cryogenic propellants

Abstract

Passive and active technologies have been used to control propellant boil-off, but the current state of understanding of cryogenic evaporation and condensation in microgravity is insufficient for designing large cryogenic depots critical to the long-term space exploration missions. One of the key factors limiting the ability to design such systems is the uncertainty in the accommodation coefficients (evaporation and condensation), which are inputs for kinetic modeling of phase change. A novel, combined experimental and computational approach is being used to determine the accommodation coefficients for liquid hydrogen and liquid methane. The experimental effort utilizes the Neutron Imaging Facility located at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland to image evaporation and condensation of hydrogenated propellants inside of metallic containers. The computational effort includes numerical solution of a model for phase change in the contact line and thin film regions as well as an CFD effort for determining the appropriate thermal boundary conditions for the numerical solution of the evaporating and condensing liquid. Using all three methods, there is the possibility of extracting the accommodation coefficients from the experimental observations. The experiments are the first known observation of a liquid hydrogen menisci condensing and evaporating inside aluminum and stainless steel cylinders. The experimental technique, complimentary computational thermal model and meniscus shape determination are reported. The computational thermal model has been shown to accurately track the transient thermal response of the test cells. The meniscus shape determination suggests the presence of a finite contact angle, albeit very small, between liquid hydrogen and aluminum oxide.

A New Technique to Determine Accommodation Coefficients of Cryogenic Propellants

“…designing large cryogenic depots critical to the long-term space exploration missions [41]. The ability to predict the rate of phase change inside propellant tanks remains a challenge primarily due to the absence of evaporation-condensation coefficients and the inability to computationally capture the local thermodynamics [3,4,18,19,60,99,101]. In addition to space technology, accurate modeling of phase change is essential in atmospheric science and climate [76,111], aerosol transport [95,103] micro-and nano-scale thermal transport in MEMS applications [16,34,118].…”

“…I built the thermal model published in this manuscript from scratch. Although the geometry of the model is similar, the approach used is different from that used by Arun Tamilarasan in Bellur et al [19] and Chapter 2 of this dissertation. I'm the primary author of all text, figures and tables in the manuscript.…”

“…The material contained in this chapter was previously published in Cryogenics by Bellur et al [19]. See Appendix A for documentation of permission to republish this material.…”

“…The time constants could be matched to within 30%, but further increase in resistance beyond a certain value had no effect on the time constant. In the methane simulations, the Sensor-to- Experimentally measured meniscus profiles did not exhibit any hysteresis during recession and the meniscus shape remained the same during evaporation and condensation tests [18,19]. Therefore, phase change is modeled as quasi-steady with a fixed interface location.…”

An Assessment of the Validity of the Kinetic Model for Liquid-Vapor Phase Change by Examining Cryogenic Propellants

“…Regions of interest in an evaporating meniscus[1] In order to solve for the evaporative mass flux using a kinetic model, the liquid phase temperature is required. The liquid temperature depends on the temperature of the solid in contact with the liquid.…”