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 (10) for simultaneously densifying two cryogenic liquids at different temperatures is provided. The densifier (10) has a thermoacoustic heat engine (20), a resonance tube (18) and a two stage pulse tube refrigerator (40). The thermoacoustic heat engine (20) generates oscillatory acoustical power required to generate net refrigeration power in the two-stage pulse tube refrigerator (40). The first stage (100) densifies a first cryogenic liquid to a first cryogenic temperature, and the second stage (200) densifies a second cryogenic liquid to a second, lower cryogenic temperature. The thermoacoustic heat engine (20) converts thermal energy to the oscillatory acoustical power required to generate net refrigeration in the first (100) and second (200) stages of the pulse tube refrigerator (40). No mechanical energy input is required, and therefore the invented densifier (10) has no moving parts.