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2003/12/3

Designing a more silent and ecological refrigerator with more precise temperature maintenance

The Thermal Engineering group of researchers at the Public University of Navarre is working on the design of a domestic thermoelectric refrigerator. Unlike the conventional system of producing a cold environment – by vapour compression – the thermoelectricity used in the design of this refrigerator allows the manufacture of more compact and quieter units which respect the environment more.

This first prototype of the thermoelectric domestic refrigerator, commissioned by the multinational BSH Siemens, will be ready in January 2004. Moreover, in current domestic refrigerators the motor cuts in and cuts out, something which does not happen with thermoelectricity and, thus, maintaining the temperature is more accurately carried out.

Innovative technology

Research carried out by the group centred round obtaining of both hot and cold environments with thermoelectricity. This technology is based on the Peltier pad, composed of two plates which have semiconductors incorporated. On applying a direct current and thanks to the electromotive force, one plate is left cold and heat is produced on the other. So, it can work as either a refrigerator or a heat pump.

They are square pads measuring 40 millimetres each side. This pad concentrates all the cold and all the heat and, in order to obtain maximum efficiency, a way of distributing them effectively has to be found. For example, dissipating this heat from here is very difficult, and so a heat exchange device, currently in the patent stage, has been designed. It is a system which enables this highly concentrated heat to be distributed and the heat exchanger to obtain optimum performance.

In the field of the production of cold environments, unlike the conventional system with vapour compression, thermoelectricity offers a great number of advantages. The units are much more compact, they are smaller and do not need maintenance. Moreover, they completely respect the environment as they do not use refrigerant fluids of any kind. Not having CNCs, their operation does not affect the ozone layer nor does it contribute to the greenhouse effect. Nor is acoustic contamination produced as no sound is made. Moreover, a better quality of cold environment is produced due to greater precision in temperature control.

A disadvantage of the system is electrical consumption which is somewhat greater than in a conventional refrigerator.