Abstract: A hydrogen storage and delivery system is provided having an orifice pulse tube refrigerator and a liquid hydrogen storage vessel. A cooling system, coupled to the orifice pulse tube refrigerator, cools the vessel and abates ambient heat transfer thereto in order to maintain the liquid hydrogen in the vessel at or below its saturation temperature. Hydrogen boil-off, and the necessity to provide continuous venting of vaporized hydrogen are minimized or avoided. In a preferred embodiment, the hydrogen storage vessel has a toroidal shape, and the pulse tube refrigerator is a two stage pulse tube refrigerator and extends within a central void space defined at the geometric center of the toroidal storage vessel.

Abstract: A hydrogen storage and delivery system is provided having an orifice pulse tube refrigerator and a liquid hydrogen storage vessel. A cooling system, coupled to the orifice pulse tube refrigerator, cools the vessel and abates ambient heat transfer thereto in order to maintain the liquid hydrogen in the vessel at or below its saturation temperature. Hydrogen boil-off, and the necessity to provide continuous venting of vaporized hydrogen are minimized or avoided. In a preferred embodiment, the hydrogen storage vessel has a toroidal shape, and the pulse tube refrigerator is a two stage pulse tube refrigerator and extends within a central void space defined at the geometric center of the toroidal storage vessel.

Abstract: A densifier is provided which in one embodiment can simultaneously densify two cryogenic liquids at different temperatures. The densifier has an oscillatory power source for generating oscillatory power and a two stage pulse tube refrigerator. The oscillatory power source can be a thermoacoustic heat engine or a mechanical oscillatory power source such as a linear flexure bearing compressor. The first stage densifies a first cryogenic liquid to a first cryogenic temperature, and the second stage densifies a second cryogenic liquid to a second, lower cryogenic temperature. A densified propellant management system also is provided which has a densifier for simultaneously densifying two cryogenic liquids at different temperatures, and a cryogenic temperature probe for measuring the temperature gradient in a cryogenic liquid.

Abstract: A densifier is provided which in one embodiment can simultaneously densify two cryogenic liquids at different temperatures. The densifier has an oscillatory power source for generating oscillatory power and a two stage pulse tube refrigerator. The oscillatory power source can be a thermoacoustic heat engine or a mechanical oscillatory power source such as a linear flexure bearing compressor. The first stage densifies a first cryogenic liquid to a first cryogenic temperature, and the second stage densifies a second cryogenic liquid to a second, lower cryogenic temperature. A densified propellant management system also is provided which has a densifier for simultaneously densifying two cryogenic liquids at different temperatures, and a cryogenic temperature probe for measuring the temperature gradient in a cryogenic liquid.