Device Efficiency
The efficiency of a thermoelectric device for electricity generation is given by η, defined as
The maximum efficiency ηmax is defined as
where TH is the temperature at the hot junction and TC is the temperature at the surface being cooled. is the modified dimensionless figure of merit, which takes into consideration the thermoelectric capacity of both thermoelectric materials being used in the device and is defined as
where ρ is the electrical resistivity, is the average temperature between the hot and cold surfaces and the subscripts n and p denote properties related to the n- and p-type semiconducting thermoelectric materials, respectively. Since thermoelectric devices are heat engines, their efficiency is limited by the Carnot efficiency, hence the TH and TC terms in . Regardless, the coefficient of performance of current commercial thermoelectric refrigerators ranges from 0.3 to 0.6, one-sixth the value of traditional vapor-compression refrigerators.
Read more about this topic: Thermoelectric Effect
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—Ambrose Bierce (1842–1914)
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—Lawrence Kutner (20th century)