This model optimizes cryogenic thermal storage system performance. One of the major advances in this area is the development of an analytical tool for sizing the ZBO system, including tankage, passive insulation, cryocooler, radiator, and power system mass. Right: Lightweight, High Efficiency Cryocooler.Īlong with advancing the SOA of cryocoolers, system studies are also being conducted with GRC, JPL, and MSFC. The ARC Cryogenics Group and its partners have been developing high heat capacity rare earth alloys for just this purpose. The key to such improvements is the design of the regenerator and the selection and forming of the regenerator material. Pulse tube and Stirling coolers offer the best opportunity for achieving high efficiency at these temperatures and power levels. The final development frontier for LH2 coolers is to achieve high efficiency and reliability at lower operating temperatures. Current commercial, non-flight pulse tube cryocoolers are available for temperatures down to 3 K, however, these machines are not space qualified and are inefficient. At present, no long-lived 30 K or colder closed-cycle coolers have flown in space. These systems require extensive development to achieve the same levels of efficiency that are reached for the higher temperature liquid oxygen (LOx) and methane ZBO coolers. For ZBO liquid hydrogen systems, cooling powers of 1 to 20 watts are required at 20 K. New developments are required to significantly improve the performance of coolers for the ZBO storage of liquid hydrogen. Each pound of propellant tank mass saved is directly tradable for payload mass.Ĭryocoolers are the key component of ZBO propellant storage systems. By using cryocoolers to balance the entire parasitic and internally generated heat loads in the cryo-tank, no propellant will be lost, resulting in a Zero Boil Off (ZBO) system, and eliminating the need for oversized tanks and extra propellant. Advances in passive thermal control technology might reduce losses to 1%/month, still an unacceptable rate for a 2+ year mission to Mars. The current State of the Art (SOA) for cryo-propellant storage is a loss rate of 3%/month in Low Earth Orbit (LEO) using passive technology. Cryogenic propellants such as oxygen, methane, and hydrogen can satisfy this requirement. The vision includes in-space cryo-propulsion stages, and In-Situ Resource Utilization (ISRU) for cryo-propellant production and liquefaction of breathable gases. The Exploration vision requires high performance propulsion systems (high specific impulse, Isp) for both human and robotic missions. The challenges of NASA’s Exploration vision require advanced Cryogenic Fluid Management technology.
CFM also plays a key role in infrared and x-ray astronomy, biological sciences, and fundamental investigations into the origins of our universe. Cryogenic Fluid Management (CFM) technology is an integral part of exploration systems for Earth-to-Orbit Transportation, manned missions to the Moon and Mars, Planetary Exploration, and In-Situ Resource Utilization (ISRU).
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