Duration: 24 months
Space explorations are moving farther away from Earth towards the Moon and Mars. In this context, the in-situ production and the long-term storage of cryogenic propellants are paramount to successful space travel. Concerning this last engineering challenge, highly performing cryogenic quenching capability is essential for efficient cryo-propellant liquefaction and condensation processes, transient operation of engine and power cycles, and the more traditional task of propellant handling and transfer. Defined as the transient process, bringing and adjusting the system to low temperatures, cryogenic quenching cannot be avoided. It involves complex, unsteady two-phase heat and mass transfer, which is still poorly understood and is even less in reduced gravity. Decreasing the quenching time of a component is crucial to enhance a cryogenic system's efficiency and reduce energy and/or propellant losses. In this framework, a new, innovative, and passive strategy is proposed to shorten the cryogenic quenching time by creating surface patterns of discontinuous, thin Low Thermal Conductivity layers. This creates a pumping effect from the liquid bulk to the surfaces, enhanced capillary wicking, and local heterogeneous nucleation control at the walls. The global result is an improved convective heat and mass transfer during each quenching stage. For example, it will lead to higher Leidenfrost temperature and anticipated liquid/wall wetting and re-wetting incipience. To reach this goal, fluid physics, heat transfer, and micro-manufacturing are combined, and experimental verification campaigns are conducted. Our investigation will first focus on thin low-conductivity layers made of silicone sealant in austenitic stainless channels with a rectangular cross-section using first cryogenic simulants and then Liquid Nitrogen.
