Solid state refrigerator

From Yenra

Conventional cooling systems such as refrigerators and air conditioners rely on the properties of gases to cool and most systems use the change in density of gases at changing pressures to cool. Refrigerators and other cooling devices may one day lose their compressors and coils of piping and become solid state, according to researchers who are investigating electrically induced heat effects of some ferroelectric polymers.

Penn State scientists studied ferroelectric polymers that exhibit temperature changes at room temperature under an electrical field. These polarpolymers include poly(vinylidene fluoride-trifluoroethylene) and poly(vinylidene fluoride-trifluoroethylene)-chlorofluoroethylene, however there are other polarpolymers that exhibit the same effect.

Electrical Engineering Professor Qiming Zhang used the change form disorganized to organized that occurs in some polarpolymers when placed in an electric field. The natural state of these materials is disorganized with the various molecules randomly positioned. When electricity is applied, the molecules become highly ordered and the material gives off heat and becomes colder. When the electricity is turned off, the material reverts to its disordered state and absorbs heat.

The change in temperature for the material was about 22.6 degrees Fahrenheit. Repeated randomizing and ordering of the material combined with an appropriate heat exchanger could provide a wide range of heating and cooling temperatures.

The polymers are flexible and can be used for heating and cooling.

Besides air conditioning and refrigeration units, applications could include heating or cooling of a variety of clothing including cooling of protective gear for fire fighters, heating of mittens and socks or shoes for athletes, sportsmen and law enforcement officers. Another application would be in electronics, where small amounts of the polymers could effectively cool over heating circuit boards and allow closer packing, and therefore smaller devices.