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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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The ZrNi hydride has been assessed as reversible hydrogen storage material in actuators of gas gap heat switches for applications involving hydride compressors in closed-cycle Joule-Thomson sorption cryocoolers.
This paper summarizes experiments on the behavior of hydrogen in the gas gap switch and formation of methane in the CE sorbent beds.
Two sorption coolers using hydrogen as the working fluid are currently being fabricated and assembled for flight delivery by the Jet Propulsion Laboratory (JPL). Being vibration free, scalable and with the capability for the cold end to be remotely located from the warm spacecraft are the major advantages of this class of cryo-coolers. These systems have been designed to provide a total cooling capacity (per cooler) of 1 W at a cold end temperature less than 19 K. They will be used for the Planck surveyor mission (2007 launch). In this paper we present the level Of maturity of the hydrogen sorption cooler technology at JPL by describing the design and how it has been validated at the subsystem and system levels.
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A transient thermal simulation model has been developed to simulate the dynamic performance of a multiple-stage 10 K sorption cryocooler for spacecraft sensor cooling applications that require periodic quick-cooldown (under 2 minutes) , negligible vibration, low power consumption, and long life (5 to 10 years). The model was specifically designed to represent the Brilliant Eyes Ten-Kelvin Sorption Cryocooler Experiment (BETSCE), but it can be adapted to represent other sorption cryocooler systems as well. The model simulates the heat transfer, mass transfer, and thermodynamic processes in the cryostat and the sorbent beds for the entire refrigeration cycle, and includes the transient effects of variable hydrogen supply pressures due to expansion and overflow of hydrogen during the cooldown operation. The paper describes model limitations and simplifying assumptions, with estimates of errors induced by them, and presents comparisons of performance predictions with ground experiments. An important benefit of the model is its ability to predict performance sensitivities to variations of key design and operational parameters. The insights thus obtained are expected to lead to higher efficiencies and lower weights for future designs.
This paper presents the cryogenic design of Hydrogen Sorption Cooler, part of cryogenic chain in the Planck Mission (ESA).
The Jet Propulsion Laboratory has built and delivered two continuous closed cycle hydrogen Joule-Thomson (JT) cryocoolers for the ESA Planck mission, which will measure the anisotropy in the cosmic microwave background. The metal hydride compressor consists of six sorbent beds containing LaNi4.78Sn0.22 alloy and a low pressure storage bed of the same material. Each sorbent bed contains a separate gas-gap heat switch that couples or isolates the bed with radiators during the compressor operating cycle. ZrNiHx hydride is used in this heat switch. The Planck compressor produces hydrogen gas at a pressure of 48 Bar by heating the hydride to approx.450 K. This gas passes through a cryogenic cold end consisting of a tube-in-tube heat exchanger, three pre-cooling stages to bring the gas to nominally 52 K, a JT value to expand the gas into the two-phase regime at approx.20 K, and two liquid - vapor heat exchangers that must remove 190 and 646 mW of heat respectively.