Optimization Calculations for a 30 Hz, 4 K Regenerator With Helium-3 Working Fluid

Radebaugh, Ray; Huang, Yonghua; O'Gallagher, Agnes; Gary, John; Weisend, J. G.

doi:10.1063/1.3422340

Cited by 13 publications

(5 citation statements)

References 8 publications

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“…Operating at higher frequency ranges, 30 Hz to 60 Hz, leads to greater regenerator losses at 4 K when not operating at ideal conditions. 2 The optimization between the phase angle of the pressure and the flow, where flow lags pressure, is critical at the cold-end of a 4 K cryocooler to provide optimum efficiency. Recent modeling has shown that the optimum phase required at the cold-end is 30°, which would require a 60° phase difference at the pulse tube warm-end.…”

Section: Phase Shiftersmentioning

confidence: 99%

Experiments with linear compressors for phase shifting in pulse tube crycoolers

Lewis¹,

Bradley²,

Radebaugh³

2012

AIP Conference Proceedings

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For the past year NIST has been investigating the use of mechanical phase shifters as warm expanders for pulse tube cryocoolers. Unlike inertance tubes, which have a limited phase shifting ability at low acoustic powers, mechanical phase shifters have the ability to provide nearly any phase angle between the mass flow and the pressure. We discuss our results with experiments and modeling on a commercially available miniature linear compressor operating as an expander on the warm-end of a 4 K pulse tube, whose temperature is nominally about 35 K. We also present results on experiments with a linear compressor operating at room temperature but coupled to the 4 K stage through secondary regenerators and secondary pulse tubes. Experiments on a small pulse tube test apparatus with both 4 He and 3 He showed improved efficiency when using the mechanical expander over that of inertance tubes. Phase locking techniques using function generators and power amplifiers for control of phase angle are detailed. The use of expanders demonstrates flexible control in optimizing phase angles for improved cryocooler performance.

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Section: Phase Shiftersmentioning

confidence: 99%

Experiments with linear compressors for phase shifting in pulse tube crycoolers

Lewis¹,

Bradley²,

Radebaugh³

2012

AIP Conference Proceedings

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“…Recently the use of 3 He in place of the 4 He in a 30 Hz pulse tube cryocooler has shown increased efficiency at 4 K [32]. Modeling studies [43] have shown that optimized regenerators using 3 He can have significantly improved performance, especially if the average pressure is reduced to about 0.5-1.0 MPa. Low-porosity matrix geometries in the high heat capacity materials can lead to further increases in the regenerator performance.…”

Section: High Efficiency Cryocoolers For 4 Kmentioning

confidence: 99%

Cryocoolers: the state of the art and recent developments

Radebaugh

2009

J. Phys.: Condens. Matter

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283

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Cryocooler performance and reliability are continually improving. Consequently, they are more and more frequently implemented by physicists in their laboratory experiments or for commercial and space applications. The five kinds of cryocoolers most commonly used to provide cryogenic temperatures for various applications are the Joule-Thomson, Brayton, Stirling, Gifford-McMahon, and pulse tube cryocoolers. Many advances in all types have occurred in the past 20 years that have allowed all of them to be used for a wide variety of applications. The present state of the art and on-going developments of these cryocoolers are reviewed in this paper. In the past five years new research on these cryocoolers has offered the potential to significantly improve them and make them suitable for even more applications. The general trend of this new cryocooler research is also presented.

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“…In collaboration with our group, Radebaugh et al [8,9] from NIST developed a new version of the regenerator modeling code-REGEN3.3, which incorporates the thermophysical properties of both 4 He and 3 He. Preliminary calculations of high frequency cryocoolers with 3 He and 4 He have been conducted to investigate how geometry and materials, among other aspects, affect the performance of the regenerator working at 4 K at the cold end and 20 K at the hot end.…”

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confidence: 99%