Experimental results on a low-temperature magnetic refrigerator

Conference · Tue Jan 01 04:00:00 EST 1985

DOI:https://doi.org/10.1007/978-1-4613-2213-9_84· OSTI ID:5233547

Barclay, J A; Stewart, W F; Overton, W C; Candler, R J; Harkleroad, O D

A Carnot-cycle magnetic refrigerator has been designed, built, and tested in the temperature range of approx.4 K to approx.15 K. Gadolinium gallium garnet in the rim of a wheel is the refrigerant. The wheel rim rotates through a gap between two superconducting Helmholtz coils that produce a magnetic field of up to 6 T. Helium gas is used as the heat-transfer fluid in the hot and cold regions of the wheel. The refrigerator performance has been measured in an open-cycle flow system because no suitable low-temperature helium gas pumps were available for closed loop circulation of helium gas. Over one watt of cooling power with a temperature span of several degrees was achieved. At low frequencies the cooling power and temperature changes of the refrigerator match the entropy-temperature data used in the design. Problems associated with friction and gas mixing limit the performance at frequencies above about 0.1 Hz. Separate friction measurements suggest that gas flow control is the dominant problem that needs to be solved before significant improvement in refrigerator operation can be expected. The present measured efficiency is about 20% of Carnot if the drive motor efficiency is ignored. With friction and other losses in the drive motor mechanism, the overall efficiency is approx.1% of Carnot.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5233547
• Report Number(s): LA-UR-85-2987; CONF-850814-5; ON: DE85017541
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COOLING SYSTEMS
DESIGN
ELEMENTS
ENERGY SYSTEMS
FLUIDS
GADOLINIUM
GALLIUM
GARNETS
GASES
HELIUM
LOW TEMPERATURE
MAGNETIC REFRIGERATORS
MEASURING METHODS
METALS
MINERALS
NONMETALS
OXYGEN COMPOUNDS
RARE EARTHS
RARE GASES
REFRIGERATORS
RESEARCH PROGRAMS
SILICATES
SILICON COMPOUNDS
SUPERCONDUCTING COILS
TESTING