One of the unsolved problems in
energy conversion is to convert low grade radiative heat into brake horsepower. This breakthrough allows us to begin
engineering plausible solutions. We are
not given the actual transition temperature, but indications are that it is
well within the usual working ranges.
Now imagine a magnetic motor
effect that switches on or off depending on changing temperature. It is mind boggling to piece something
together, but this should spur inventive talents everywhere.
Better designs for rotary power
takeoff have enthralled garage tinkerers for decades. Add in a few niobium magnets and we are off. This could keep even me busy for years.
Engineering researchers discover source for generating 'green'
electricity
by Staff Writers
During a small-scale demonstration in the lab, University of
Minnesota researchers showed how their
new material can spontaneously produce electricity when the temperature is
raised a small amount. Pictured (from left) are aerospaceengineering and
mechanics professor Richard James, Ph.D. student Yintao Song and post-doctoral
researchers Kanwal Bhatti and Vijay Srivastava.
Researchers say the material could potentially be used to capture waste
heat from a car's exhaust that would heat the material and produce electricity
for charging the battery in a hybrid car. Other possible future uses include
capturing rejected heat from industrial and power plants or temperature
differences in the ocean to create electricity. The research team is looking
into possible commercialization of the technology.
"This research is very promising because it presents an entirely
new method for energy conversion that's never been done before," said
University of Minnesota aerospace engineering and mechanics professor Richard
James, who led the research team."It's also the ultimate 'green' way to
create electricity because it uses waste heat to create electricity with no
carbon dioxide."
To create the material, the research team combined elements at the
atomic level to create a new multiferroic alloy, Ni45Co5Mn40Sn10. Multiferroic
materials combine unusual elastic, magnetic and electric properties.
The alloy Ni45Co5Mn40Sn10 achieves multiferroism by undergoing a highly
reversible phase transformation where one solid turns into another solid.
During this phase transformation the alloy undergoes changes in its magnetic
properties that are exploited in the energy conversion device.
During a small-scale demonstration in a University of Minnesota
A critical discovery of the team is a systematic way to minimize
hysteresis in phase transformations. The team's research was recently published
in the first issue of the new scientific journal Advanced Energy Materials.
Watch a short research video of
the new material suddenly become magnetic when heated.
In addition to Professor James, other members of the research team
include University
of Minnesota University of Minnesota
"This research crosses all boundaries of science and
engineering," James said. "It includes engineering, physics, materials, chemistry,
mathematics and more. It has required all of us within the university's College of Science
New alloy converts heat directly into electricity
By Ben
Coxworth
13:49 June 24, 2011
A newly-created alloy (center disc) is able to convert heat directly
into electricity (Image: University
of Minnesota
The heat given off by electronics, automobile engines, factories and
other sources is a potentially huge source of energy, and various technologies
are being developed in order to capture that heat, and then convert it into
electricity. Thanks to an alloy that was recently developed at the University of Minnesota
The multiferroic alloy, with the catchy name Ni45Co5Mn40Sn10, was
created by combining its various elements at the atomic level. Multiferroic
materials are known for having unique elastic, magnetic and electric
properties, and in the case of this alloy, that takes a form of an usual phase
change. When heated, the non-magnetic solid material suddenly becomes a
strongly magnetic solid.
In a lab test, upon becoming magnetic, the material absorbed heat in
its environment and proceeded to produce electricity in an attached coil.
Although some of the heat energy is lost in a process known as hysteresis,
the U
Minnesotaresearchers have developed a method of minimizing that energy
loss.
"This research is very promising because it presents an entirely
new method for energy conversion that's never been done before," said
aerospace engineering and mechanics professor Richard James, who led the
research team. "It's also the ultimate 'green' way to create electricity
because it uses waste heat to create electricity with no carbon dioxide."
The research was recently published in the journal Advanced Energy Materials.
Abstract
We demonstrate a new method for the direct conversion of heat to
electricity using the recently discovered multiferroic alloy, Ni45Co5Mn40Sn101.
This alloy undergoes a low hysteresis, reversible martensitic phase
transformation from a nonmagnetic martensite phase to a strongly ferromagnetic
austenite phase upon heating. When biased by a suitably placed permanent
magnet, heating through the phase transformation causes a sudden increase of
the magnetic moment to a large value. As a consequence of Faraday’s law of
induction, this drives a current in a surrounding circuit. Theory predicts that
under optimal conditions the performance compares favorably with the best
thermoelectrics. Because of the low hysteresis of the alloy, a promising area
of application of this concept appears to be energy conversion at small ΔT,
suggesting a possible route to the conversion of the vast amounts of energy
stored on earth at small temperature difference. We postulate other new methods
for the direct conversion of heat to electricity suggested by the underlying
theory
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