A Feasibility Experimanet of a Small Scale RTV-655 Cryogenic Liquid Container for Space Applications

Abstract

Space exploration is limited without a sustainable fuel source and the ability to store that fuel over extended periods of time. Liquid hydrogen is widely considered to be the chemical propellant that will be used for long duration missions due to its high specific impulse. Liquid hydrogen and the required oxidizer, liquid oxygen, must be maintained at cryogenic temperatures due to their boiling temperatures. These low boiling points of the cryogenic liquids as well as the surrounding thermal environment result in self-pressurization of the storage tanks. Numerous active and passive systems have been proposed to reduce cryogenic propellant tank self-pressurization. Active systems, such as cryocoolers and thermodynamic venting systems, use some of the cryogenic liquid to reduce the pressure in the tank effectively discarding some of the propellant in the process. Even with the use of passive systems such as multilayer insulation (“MLI”), the use of metal tanks to store these liquid fuels results in large amounts of heat transfer into the tanks creating higher rates of selfpressurization. This study analyzes the low temperature performance of a pressure vessel constructed using the polymer RTV-655 during self-pressurization when filled with liquid nitrogen. The parameters of this performance include stress tolerance at low temperature and the tank pressurization rate. Experimental testing parameters, procedures, and limitations are discussed and performance results for the RTV-655 tank test are presented.