Calculated Performance of Low-Porosity Regenerators at 4 K with He-4 and He-3

Published

June 9, 2008

Author(s)

Ray Radebaugh, Yonghua Huang, Agnes A. O'Gallagher, John M. Gary

Abstract

Previously we have shown that the lower volumetric heat capacity and more ideal behavior of helium-3 compared with helium-4 at 4 K results in an improved performance for packed sphere regenerators operating with helium-3 between 4 K and about 20 K. In this paper we use the NIST numerical software REGEN3.3 to calculate the regenerator loss and the coefficient of performance (COP) of 4 K regenerators with porosities between 0.1 and 0.38 for parallel holes in a rare-earth matrix operating at 30 Hz frequency using either helium-3 or helium-4. A comparison is made with packed spheres at a porosity of 0.38. Calculations were made for average pressures ranging from 0.3 MPa to 1.5 MPa, mostly with a pressure ratio of 1.5. The results show that the regenerator loss decreases and the COP increases as the porosity decreases for all average pressures. For helium-3 the regenerator performance is improved for pressures below 1 MPa, whereas the lower pressures do not benefit helium-4 regenerators. The COP of a helium-3 regenerator with 0.2 porosity operating at 30 Hz and 0.5 MPa average pressure is about 3.8 times higher than a helium-4 regenerator using packed spheres with 0.38 porosity. The effect of regenerator matrix material and the temperature of the heat capacity peak are also investigated.

Citation

Cryocoolers 15

Publisher Info

ICC Press, Boulder, CO

Pub Type

Books

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Keywords

cryocoolers, cryogenics, efficiency, helium, helium-3, modeling, pulse tube cryocoolers, regenerators

Citation

Radebaugh, R. , Huang, Y. , O'Gallagher, A. and Gary, J. (2008), Calculated Performance of Low-Porosity Regenerators at 4 K with He-4 and He-3, ICC Press, Boulder, CO, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=832365 (Accessed April 23, 2024)