Heating Cryogenic Helium with a Solid Propellant Gas Generator

Abstract

An airborne system needs 120 standard cubic meters of helium to operate. The physical constraints of the system allow a volume of only 0.26 m3 for the helium storage and supply system. This requires the helium to be stored cryogenically at 20.69 MPa and 10 K. A compact lightweight inexpensive heating system is required to heat the helium from 10 K to 250 K in a very short time period. The system consists of a stainless steel shell and tube heat exchanger (HEX) and a solid propellant gas generator (GG). The propellant used has a flame temperature of 2828 K which minimizes the system size. The temperature extremes and unique gas generator application create unknowns in the analysis and design of the heat exchanger and the high temperature requires a method to cool the hot gas to allow the heat exchanger to be manufactured from stainless steel. The method devised recirculates a portion of the heat exchanger exhaust gas to cool the primary gas generator stream to 1367 K.