Efforts by UK scientists to achieve a breakthrough in cooling efficiency could spell the end of long-standing methods of refrigeration and air conditioning.
Scientists at the National Physical Laboratory (NPL) and Imperial College in Britain are attempting to apply the electrocaloric effect to the development of new cooling techniques which will promise to be far more efficient, economical and environmentally friendly than conventional vapour-compression methods.
The electrocaloric effect refers to changes in the temperature of materials which occur as a result of exposure to an applied electric field – a mysterious phenomenon whose underlying mechanism has yet to be fully elucidated by scientists.
While electrocaloric materials were the object of keen interest within the scientific community as early as the 1960s and 1970s, they were never used for commercial purposes at the time due to inability to deliver significant change in temperature. The highest response logged back then was a 2.5 degrees Celsius temperature change under an applied potential of 750 volts.
Since the turn of the century, however, materials scientists have made major strides in developing the potential of electrocaloric materials, with researchers producing a ferroelectric polymer which is capable of 12 K of cooling in 2008.
If successfully developed as a viable cooling method, the electrocaloric effect would harbour major advantages compared to the vapour-compression methods which have been in vogue for over a century, yet fall significantly short of modern expectations with respect to efficiency and environmental impact.
Vapour compression cooling involves a continuous cycle of the compression and expansion of chemicals, which permits the absorption of heat as they undergo phase changes.
The method suffers from severe shortcomings however, including poor efficiency and high energy requirements, the need for bulky, ungainly equipment, as well as the potential damage caused to the environment by some of the chemicals used in the process, such as freon gas.
Electrocaloric cooling would dispense with the need for hazardous gases and would potentially be far more efficient, as the amount of energy required to generate an electric field is lower than that needed for the compression process.
The team of scientists at NPL and Imperial College are now confident that electrocaloric materials have finally reached the point where they can be applied to practical cooling purposes, with the potential to replace the conventional, time-honoured method.
Tatiana Correia, an NPL scientist who is the leader for the project, is confident the team will develop the first electrocaloric refrigerator capable of operating at close to room temperature within the next several years by building upon the extensive expertise that NPL has already amassed in the field.
In order to support its endeavours, NPL is taking the lead on the METCO (Metrology of Electro-Thermal Coupling) project, which is being funded to the tune of millions of pounds by the European Metrology Research Programme.
The programme will bring together top research bodies and members of industry in Europe, to further research into the electrocaloric properties of different materials.