Thermomagnetic motors (also known as Curie wheels, Curie-motors and pyromagnetic motors) convert heat into
kinetic energy
In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion.
In classical mechanics, the kinetic energy of a non-rotating object of mass ''m'' traveling at a speed ''v'' is \fracmv^2.Resnick, Rober ...
using the
thermomagnetic effect,
i.e., the influence of temperature on the magnetic material
magnetization
In classical electromagnetism, magnetization is the vector field that expresses the density of permanent or induced magnetic dipole moments in a magnetic material. Accordingly, physicists and engineers usually define magnetization as the quanti ...
.
Historical background
This technology dates back to 19th century, when a number of scientists submitted patents on the so-called "pyro-magnetic generators". These systems operate in a magnetic Brayton cycle, in a reverse way of the
magnetocaloric refrigerators.
Experiments have produced only extremely inefficient working prototypes,
[
] however,
thermodynamic
Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of th ...
analysis indicate that thermomagnetic motors present high efficiency related to
Carnot efficiency for small temperature differences around the magnetic material
Curie temperature
In physics and materials science, the Curie temperature (''T''C), or Curie point, is the temperature above which certain materials lose their permanent magnetic properties, which can (in most cases) be replaced by induced magnetism. The Curie ...
.
The thermomagnetic motor principle has been studied as a possible actuator in
smart materials, being successful in the generation of electric energy from ultra-low
temperature gradient
A temperature gradient is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location. The temperature spatial gradient is a vector quantity with Dimensional analysis, ...
s.
See also
*
Thermomagnetic convection
References
*
Electric motors
Magnetic devices
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