By Susan Dieterle
Every time Karl Gschneidner Jr. and Vitalij Pecharsky tell someone new about
magnetic-refrigeration technology, they hear the same question: "Where can I see
it?"
For the last few years, the scientists at the U.S. Department of
Energy's Ames Laboratory have patiently explained that they haven't had the funding to
build a working prototype. But that's about to change.
Ames Laboratory and Milwaukee-based Astronautics Corp. of America have embarked on a
three-year project to build a prototype rotary magnetic-refrigeration unit.
Under the terms of the cooperative research agreement, the Energy Department will provide
$750,000 toward the prototype project. Astronautics, a leader in magnetic-refrigeration
technology, will provide a matching amount through in-kind contributions of personnel,
research, services and facilities.
For Gschneidner, an Ames Lab senior scientist and an Anston Marston distinguished
professor of materials science and engineering at ISU, the agreement provides the
opportunity he's been waiting for.
"Building the prototype is a crucial step in moving magnetic-refrigeration technology
into the marketplace," he said.
If successful, the prototype would be the first magnetic refrigerator capable of sustained
operation and generating enough cooling power for commercial applications.
The technology is based on the magnetocaloric effect -- the ability of some materials to
heat up when magnetized and cool when removed from the magnetic field. Using these
materials as refrigerants would provide an environmentally friendly alternative to the
volatile liquid chemicals, such as chlorofluorocarbons and hydrochlorofluorocarbons, used
in traditional vapor-cycle cooling systems.
Gschneidner said initial findings indicate that magnetic refrigeration is also about 20
percent more energy-efficient than traditional cooling systems. So, although
magnetic-refrigeration technology would initially cost more, consumers could earn back the
difference in energy savings within about five years.
In their preliminary discussions about the design for the rotary prototype, the scientists
have discussed a system that would move the refrigerant materials continuously through
high and low magnetic fields on a rotating disc. Water or antifreeze will be used as the
heat-transfer fluid between the magnetic refrigerant and the heat exchangers.
Gschneidner, Pecharsky and senior physicist David Jiles will concentrate their efforts on
optimizing the performance of the alloys, and developing a source for the magnetic field
that is more cost-effective and convenient than superconducting magnets. Astronautics will
design, build and test the rotary prototype.
Pecharsky, an Ames Lab scientist and ISU associate professor of materials science and
engineering, noted that the agreement enables both organizations to capitalize on their
strengths. "When these pieces of the puzzle are properly put together, it will create
a benchmark for all future developments of this new, emerging technology," he said.
Ames Lab and Astronautics have collaborated for the past eight years. In 1996, they built
a reciprocating, proof-of-principle apparatus demonstrating that magnetic refrigeration
was a reliable, competitive technology. The apparatus operated for 18 months, achieving
cooling power 20 to 100 times greater than previous units.
Large-scale applications using magnetic refrigeration, such as commercial air conditioning
and supermarket refrigeration systems, could be available within five to 10 years,
Gschneidner said. Within 15 years, the technology could be available in home refrigerators
and air conditioners.
Gschneidner and Pecharsky are also investigating magnetic refrigeration for use in
air-conditioning systems for electric vehicles.
Although most people conjure up a futuristic image of what a refrigerator using the
technology would look like, Gschneidner said the outward appearance probably won't change
very much.
"We would just replace the compression system with the magnetic-refrigeration
system," he said. "It probably wouldn't look much different from the
outside."
Last revision: 7/8/99 sd
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