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In the 1998 timeframe increasing numbers of proposed space-instrument programs within NASA and the Balistic Missile Defense Organization (BMDO) were in need of high-reliablility, long-life, low-vibration space cryocoolers.
The design, analysis and predicted performance of the Brilliant Eyes Ten-Kelvin Sorption Cryocooler Experiment (BETSCE) is described from a thermal perspective...
This paper describes the cryogenic system design including the cryogenic loads, thermal performance margins, and performance properties for the cryocoolers.
As the demands for extended space missions and sustained lunar and Martian presence grow, the need for power and mass-efficient cryogenic fluid production and storage becomes paramount. The exploration and advancement of space technologies necessitate the development of innovative cryogenic storage solutions to ensure reliable, long-term production and preservation of cryogens in space environments for propulsion, life-support, and power applications. This paper covers an analysis of the challenges posed by long-duration cryogen storage and production for in-space and surface applications for NASA’s upcoming missions, as well as highlighting cryocooler technology opportunities and gaps to encourage industry stakeholders to contribute innovative solutions to advance the field of cryogenic storage for space applications.
The transition toward a carbon-neutral society based on renewable energies goes hand in hand with the availability of energy-efficient technologies. Here, magnetocaloric cooling is a very promising refrigeration technology to fulfill this role regarding cryogenic gas liquefaction. However, the current reliance on highly resource critical, heavy rare-earth-based compounds as magnetocaloric material makes global usage unsustainable. Here, we aim to mitigate this limitation through the utilization of a multicaloric cooling concept, which uses the external stimuli of isotropic pressure and magnetic field to tailor and induce magnetostructural phase transitions associated with large caloric effects. In this study, La 0.7 Ce 0.3 Fe 11.6 Si 1.4 is used as a nontoxic, low-cost, low-criticality multiferroic material to explore the potential, challenges, and peculiarities of multicaloric cryocooling, achieving maximum isothermal entropy changes up to −28 J (kg K) −1 in the temperature range from 190 K down to 30 K. Thus, the multicaloric cooling approach offers an additional degree of freedom to tailor the phase transition properties and may lead to energy-efficient and environmentally friendly gas liquefaction based on designed-for-purpose, noncritical multiferroic materials.
Principal Investigator Dr. Ram Dhuley has led R&D efforts at the U.S. Department of Energy's Fermi National Accelerator Laboratory to design a cryocooler conduction-cooled SRF accelerator for e-beam irradiation treatment of wastewater. This is a spotlight on the accelerator design and its enabling core technologies.
Superconducting Radio Frequency (SRF) linear accelerators (linacs) have shown tremendous promise in extending the intensity frontier of particle accelerator technology. However, they are large and complex systems, requiring a central refrigeration system and complex piping to distribute liquid helium and nitrogen to the accelerating cavities. In response to these problems, RadiaBeam Technologies, LLC. proposes to develop a small mobile cryomodule that can be safely deployed to its planned field location. The scope of this work is to provide RadiaBeam with the specifications for a complete 650 MHz RF cavity model that can be incorporated into a compact SRF accelerator. Fermilab’s contribution will involve sharing contact resistance measurements, design parameters, and solid models. Design parameters will include the cavity frequency and gradient, length of the linac, number of cryocoolers, etc. This will ensure that the design is useful for practical linacs. A complete cryomodule design is envisioned. Radiabeam will design the cryomodule based on input from Fermilab’s experience on conduction cooling and the needs for a compact SRF accelerator.
A Navy program to develop fractional-watt cryocoolers capable of operating below 10 K is discussed. Several varieties of Stirling coolers were built and are under evaluation. In addition, helium gas compressors designed for use with small, closed cycle Joule-Thomson coolers are under development. An overview of the technical aspects of the program are presented.
At temperatures below 10K, regenerative cycle cryocoolers are limited by regeneration losses in the helium working fluid which result from the decreasing heat capacity of the regenerating material and the increasing density of helium. Experiments examining several approaches to improving the low-temperature regeneration in a four-stage regenerative cycle cooler constructed primarily of fiberglass materials are discussed. Using an interchangeable fourth stage, the experiments included configurations with multiple regeneration passages, and a static helium volume for increased heat capacity. Experiments using helium-3 as the working fluid and a Malone stage are planned. Results indicate that, using these techniques, it should be possible to construct a regenerative cycle cooler which will operate below 6K.
A very low-power, low-interference Stirling cryocooler is being developed based on principles and techniques described in several previous publications over the last four years. It differs in several important details from those built previously. It uses a tapered displacer based upon an analytical optimization procedure. The displacer is driven by an auxiliary piston and cylinder (rather than by mechanical linkage) using some of the working fluid itself to provide the driving force. This provides smooth, vibration-free motion, and, more importantly, allows complete mechanical and spatial separation of the cryostat from the pressure-wave generator. Either of two different pressure-wave generators can be used. One is a non-contaminating, unlubricated ceramic piston and cylinder. The other is a compressed-air-operated rubber diaphragm with motor-driven valves to cycle the pressure between appropriate limits.
The design of a triple expansion closed cycle Stirling cryocooler optimized for a cooling load of 50 mW at 10 K is described. The cooler was designed with the objectives of low power, low weight, compactness, low mechanical motion, low electromagnetic noise, and low output temperature fluctuations. The design employs a direct drive linear motion piston motor and a triple expansion free displacer. Piston motion is controlled by feedback from an optical position transducer. Mechanical vibrations are attenuated with a passive resonant counterbalance. Electromagnetic noise is attenuated with layered high permeability magnetic shielding. The regenerators move with the displacer within a thin titanium cold finger. The piston and displacer oscillate at 8.33 Hz on bearings and seals of reinforced Teflon. The cooler is designed to provide the desired 50 mW of cooling at 10 K with a power input of less than 100 W. The piston can be driven at a greater stroke to produce up to 200 mW of cooling with an input power of 250 W. A lead and copper cold tip heat exchanger will limit temperature fluctuations to within 0.01 K.
A great diversity of methods and mechanisms were devised to effect cryogenic refrigeration. The basic parameters and considerations affecting the selection of a particular system are reviewed. A classification scheme for mechanical cryocoolers is presented. An important distinguishing feature is the incorporation or not of a regenerative heat exchanger, of valves, and of the method for achieving a pressure variation.
Low power cryocoolers with conical displacers offer several advantages over stepped displacers. The described fabrication process allows quick and reproducible manufacturing of plastic conical displacer units. This could be of commercial interest, but it also makes systematic optimization feasible by constructing a number of different models. The process allows for a wide range of displacer profiles. Low temperature performance as dominated by regenerator losses, and several effects are discussed. A simple device is described which controls gas flow during expansion.
An experimental reciprocating expander was designed with features appropriate for cryocooler cycles. The expander has a displacer piston, simple valves, and a hydraulic/pneumatic stroking mechanism. The expander has a valve in head configuration with the valves extending out the bottom of the vacuum enclosure while the piston extends out the top. The expander was tested using a CTI 1400 liquefier to supply 13 atm in the temperature range 4.2 to 12 K. Expander efficiency was measured in the range 84 to 93% while operating the apparatus as a supercritical wet expander and in the range 91 to 93% aa a single phase expander. The apparatus can also be modified to operate as a compressor for saturated helium vapor.
This paper describes the design and development of a Vuilleumier cycle cryocooler (VM cooler) operating below 8 K, for the application of small superconducting devices. Liquid nitrogen has been used as a heat sink of the hot displacer. The annular gap between the phenolic displacer and SUS 304 stainless cylinder has been used as a gap regenerator. In order to obtain the cooling temperature below 3 K, we designed a single stage VM cooler which is precooled to 10 K by another two stage VM cooler. The effect of the mean operating pressure, cycle speed and phase difference between the hot and cold displacer of each VM cooler will be also discussed, including the experimental results.
Refrigerator with no wear-related moving parts produces 0.5 W of cooling at 118 K. When fully developed, refrigerator needs no electrical power, and life expectancy of more than 10 yr, operates unattended to cool sensitive infrared detectors for long periods. Only moving parts in adsorption cryocooler are check valves. As charcoal is cooled in canister, gas pressure drops, allowing inlet check valve to open and admit more nitrogen. When canister is heated, pressure rises, closing inlet valve and eventually opening outlet valve.
The design, analysis and predicted performance of the Brilliant Eyes Ten-Kelvin Sorption Cryocooler Experiment (BETSCE) is described from a thermal perspective. BETSCE is a shuttle side-wall mounted cryogenic technology demonstration experiment planned for launch in November 1994. BETSCE uses a significant amount of power (about 500 W peak) and the resultant heat must be rejected passively with radiators, as BETSCE has no access to the active cooling capability of the shuttle. It was a major challenge to design and configure the individual hardware assemblies, with their relatively large radiators, to enable them to reject their heat while satisfying numerous severe shuttle-imposed constraints. This paper is a useful case study of a small shuttle payload that needs to reject relatively high heat loads passively in a highly constrained thermal environment. The design approach described is consistent with today's era of 'faster, better, cheaper' small-scale space missions.
This paper provides a summary overview of the vibration characteristics of split Stirling cryocoolers of the Oxford type and describes means being developed to achieve vibration levels consistent with the exacting requirements of sensitive infrared spectrometer instruments currently under development for NASA applications. A key emphasis of the paper is on exploring both active and passive means of reducing the residual upper harmonics of the drive frequency that remain with nulled back-to-back compressor and displacer units. Vibration supression results, measured with JPL's unique six-DOF force dynamometer, are presented for an 80 K Stirling cooler.