An advance in transfer line chilldown heat transfer of cryogenic propellants in microgravity using microfilm coating for enabling deep space exploration

J N Chung,J W Hartwig,Jun Dong,Hao Wang,S R Darr

doi:10.1038/s41526-021-00149-5

Abstract

The extension of human space exploration from a low earth orbit to a high earth orbit, then to Moon, Mars, and possibly asteroids is NASA’s biggest challenge for the new millennium. Integral to this mission is the effective, sufficient, and reliable supply of cryogenic propellant fluids. Therefore, highly energy-efficient thermal-fluid management breakthrough concepts to conserve and minimize the cryogen consumption have become the focus of research and development, especially for the deep space mission to mars. Here we introduce such a concept and demonstrate its feasibility in parabolic flights under a simulated space microgravity condition. We show that by coating the inner surface of a cryogenic propellant transfer pipe with low-thermal conductivity microfilms, the quenching efficiency can be increased up to 176% over that of the traditional bare-surface pipe for the thermal management process of chilling down the transfer pipe. To put this into proper perspective, the much higher efficiency translates into a 65% savings in propellant consumption.

Highlights

The currently planned lower-earth-orbiting propellant space depots and the human orbital transfer spacecraft to the moon and Mars will need to depend on the high thrust and high efficiency of liquid cryogenic chemical propulsion or nuclear thermal propulsion[1,2,3,4]
When a cryogenic propellant such as liquid hydrogen (LH2) or liquid oxygen (LOX) is first introduced into a warm pipe from a depot supply tank to an engine or a receiver storage tank, a chilldown process follows where the liquid propellant boils into vapor until the transfer pipe and the receiving tank are quenched down to the liquid propellant temperature
Since the current chilldown technology can only manage to offer relatively very low thermal energy efficiencies[5] and further that it has never been developed under space microgravity conditions, a new breakthrough technology advancement that significantly raises these efficiencies, and is verified under space conditions is needed for enabling deep space missions

Summary

Introduction

The currently planned lower-earth-orbiting propellant space depots and the human orbital transfer spacecraft to the moon and Mars will need to depend on the high thrust and high efficiency of liquid cryogenic chemical propulsion or nuclear thermal propulsion[1,2,3,4]. When a cryogenic propellant such as liquid hydrogen (LH2) or liquid oxygen (LOX) is first introduced into a warm pipe from a depot supply tank to an engine or a receiver storage tank, a chilldown process follows where the liquid propellant boils into vapor until the transfer pipe and the receiving tank are quenched down to the liquid propellant temperature. After this transient “chilldown” procedure, single-phase liquid propellant can be transferred to the destination for designated uses such as the rocket engine fuel for combustion. Since the current chilldown technology can only manage to offer relatively very low thermal energy efficiencies[5] and further that it has never been developed under space microgravity conditions, a new breakthrough technology advancement that significantly raises these efficiencies, and is verified under space conditions is needed for enabling deep space missions

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Conclusion