Experimental and Numerical Analysis of a Thermodynamic Control System for Cryogenic Propellant Storage

International audienceA technological barrier for long duration space mission using cryogenic propulsion is the control ofpropellant tank self-pressurization. Since the liquid propellant submitted to solar fluxes tends to vaporize,the pressure rise must be controlled to prevent mission failure. The Thermodynamic Vent System (TVS)is such a control strategy: liquid propellant pumped from the tank, is cooled down by a heat exchangerand re-injected as a sub-cooled spray inside the tank. The tank pressure drops due to vapor condensationand liquid bath destratification (Refs. 1 to 4). Our research strategy combines an on-ground experimentalset up (Ref. 5) and Volume of Fluid (VOF)-based simulations. The cylindrically-shaped tank is filled witha surrogate fluid (Novec1230 by 3M). The thermal input is controlled by an electrical heating coil. Anoriginal insulation technique is used to prevent undesirable heat flux from the wall. The double shroud isthermalized by a water loop, regulated to follow the average tank temperature variation. Injectiontemperature and mass flow rate are fixed during an experiment. Instrumentation gives access to theaccurate measurement of the tank vertical temperature distribution and allows to assess the TVSefficiency. To optimize the TVS design, the experiment will be numerically reproduced using an in-housesolver based on VOF approach for interface tracking (Ref. 6), and a phase change model taking advantageof a sharp mass transfer rate distribution (Ref. 7). Experimental results, including thermal stratificationquantification in the tank will be presented for various heat loads and TVS control parameters.Preliminary numerical results demonstrating the accuracy of the developed solver will be also provided