28 June 2015 to 2 July 2015
JW Marriott Starr Pass Resort
Etc/GMT-7 timezone

Periodic Flow Hydrodynamic Resistance Parameters for ErPr Rare-Earth Regenerator Material at Cryogenic Temperatures

2 Jul 2015, 09:15
15m
Tucson Ballroom AB ()

Tucson Ballroom AB

Contributed Oral Presentation CEC-04 - Cryocoolers (Aerospace) C4OrA - System Issues and Regenerator Performance

Speaker

Matthew Perrella (Georgia Institute of Technology)

Description

The regenerator is a critical component of all Stirling and Pulse Tube cryocoolers. It generally consists of a microporous metallic or rare-earth filler material contained within a cylindrical shell. The accurate modeling of the hydrodynamic and thermal behavior of different regenerator materials is crucial to the successful design of cryogenic systems. Previous investigations have used experimental measurements at steady and periodic flow conditions in conjunction with pore-level CFD analysis to determine the pertinent hydrodynamic parameters, namely the Darcy permeability and Forchheimer coefficients. Due to the difficulty associated with experimental measurement at cryogenic temperatures, past investigations where performed at ambient conditions. These results are assumed to be accurate for cryogenic temperatures since, for fully-developed flow, the Darcy and Forchheimer coefficients should depend only on the geometry of the porous medium. There is, however, a pressing need in the literature to determine the hydrodynamic parameters or ErPr under prototypical conditions and verify the validity of the foregoing assumption. In this analysis, a regenerator filled with spherical Er50Pr50 powder was assembled and tested under periodic helium flow at cryogenic temperatures. The mass flow and pressure drop data was correlated with a porous media CFD model to determine the Darcy Permeability and Forchheimer coefficients. These results are compared to the previous investigations at ambient temperature conditions, and the relevance of room-temperature models and correlations to cryogenic temperatures is critically assessed.

Primary author

Matthew Perrella (Georgia Institute of Technology)

Co-authors

Mr Mihir Pathak (Presidential Management Fellow & Policy Advisor, White House) Dr Mostafa Ghiaasiaan (Georgia Institute of Technology) Dr Thomas Mulcahey (CSA Medical, Inc.)

Presentation Materials