J.C. Peltier: discoverer of the Peltier effect
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Chemical effects are obtained from a dry pile if the surface area of the plates is large enough In a series of thermocouple circuits, alternate junctions are cooled and heated
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JEAN CHARLES Peltier was born on February 22, 1785 in Ham, France. His father earned a living as a shoemaker. So his formal education was confined to the local schools. But he displayed, at an early age, quick intelligence and mechanical skills.
Apprentice in a trade
At the age of 15, he was apprenticed to a German clockmaker who ill-treated him. His father then shifted him to another clockmaker in Paris. He worked in this way for six years.
In 1806, Peltier opened his own shop and married Mille Dufant. The marriage brought him a modest inheritance (1815). This was sufficient for his needs, and he retired.
Study of electricity
He devoted his attention to a wide range of studies and then became interested in phrenology of Franz Gall. At the age of 36, he was inspired to study anatomy to obtain a complete knowledge of the structure of the brain.
He attended a number of vivisection demonstrations, in which electricity was used to stimulate nerves. These led Peltier to the study of electricity, which he pursued till the end of his life (October 27, 1845).
Peltier's first scientific paper was presented to the Academy of Sciences, Paris, in 1830. He showed that chemical effects could be obtained from a dry pile if the surface area of the plates is sufficiently large.
This work also displayed that Peltier had some understanding of the difference between current and voltage, with which electricians were to struggle for another ten years.
In 1821, T.J. Seebeck (1770-1831) had shown that temperature differences could produce electric currents.
Peltier observed in 1834 the reverse effect: the passage of electricity through a junction of two different metals (antimony and copper) could produce a rise in temperature at the junction when passing in one direction and a drop in temperature when passed in the reverse direction. The direction of heat transfer is controlled by the direction of the current, which is the basis of thermo-electric coolers.
Leopold Nobili, professor of physics at the Florence Museum, invented (1830) the thermoelectric couple, by which an electric potential is created by the junction of two metals at different temperatures. Stimulated by the above work, he constructed a thermoelectric thermoscope to measure the temperature distribution along a series of thermocouple circuits.
Peltier discovered that a cooling effect could take place at one junction and heating at the other. He then confirmed this discovery by using an air thermometer. He did not pursue study of the effect he had discovered.
Its recognition had to wait for the thermodynamic work (Joule-Thomson effect) of William Thomson (1824-1907), which resulted in a formulation of the Second Law of Thermodynamics — equivalent to that given by Rudolf Clausis in the preceding year (The Dictionary of Scientific Biography).
Material cost reduction
It was only after the advance in semi-conductor technology in 1950s that practical applications for thermoelectric coolers became feasible.
Cooling the hot spots directly in semiconductor packages can reduce material cost and augment electrical power delivery where it is needed in power transistors.
(Semiconductor International, Oct. 2005, Vol. 28)
R. PARTHASARATHY
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