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Magnetic Stirling cycles - A new application for magnetic materialsThere is the prospect of a fundamental new application for magnetic materials as the working substance in thermodynamic cycles. Recuperative cycles which use a rare-earth ferromagnetic material near its Curie point in the field of a superconducting magnet appear feasible for applications from below 20 K to above room temperature. The elements of the cycle, advanced in an earlier paper, are summarized. The basic advantages include high entropy density in the magnetic material, completely reversible processes, convenient control of the entropy by the applied field, the feature that heat transfer is possible during all processes, and the ability of the ideal cycle to attain Carnot efficiency. The mean field theory is used to predict the entropy of a ferromagnet in an applied field and also the isothermal entropy change and isentropic temperature change caused by applying a field. Results are presented for J = 7/2 and g = 2. The results for isentropic temperature change are compared with experimental data on Gd. Coarse mixtures of ferromagnetic materials with different Curie points are proposed to modify the path of the cycle in the T-S diagram in order to improve the efficiency or to increase the specific power.
Document ID
19770054191
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Brown, G. V.
(NASA Lewis Research Center Cleveland, Ohio, United States)
Date Acquired
August 9, 2013
Publication Date
June 1, 1977
Subject Category
Thermodynamics And Statistical Physics
Meeting Information
Meeting: International Magnetics Conference
Location: Los Angeles, CA
Start Date: June 6, 1977
End Date: June 10, 1977
Sponsors: Institute of Electrical and Electronics Engineers
Accession Number
77A37043
Distribution Limits
Public
Copyright
Other

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