A thermocouple is a thermoelectric effect-based temperature measurement device that uses the change in thermoelectric potential between two different metals to measure temperature. The discovery and development of thermocouples involved a series of studies and experiments dating back to the 19th century.
The following are the main milestones in the history of thermocouples:
Discovery of the Seebeck Effect (1821).: The thermoelectric effect was first described in 1821 by the German physicist Thomas Johann Seebeck, in which the difference in temperature causes a difference in electric potential when two different conductors form a closed loop. This became known as the Seebeck effect, which laid the foundation for the later development of thermocouples.
Discovery of the Peltier Effect (1834).: In 1834, the French physicist Jean Charles Athanase Peltier discovered the opposite of the Seebeck effect, which is that when an electric current passes between two different conductors, heat is generated or absorbed at the junction. This is known as the Peltier effect.
The Formulation of the Thomson Effect (1854).: The British physicist William Thomson (later Lord Kelvin) proposed the Thomson effect in 1854, describing the relationship between the heat produced and the difference in temperature when an electric current flows in a conductor.
Practical application of thermocouples (late 19th century).: With the in-depth study of thermoelectric effects, thermocouples are becoming more and more used as a reliable tool for temperature measurement. They are widely adopted in industry and science because of their wide measurement range and relatively simple structure.
Establishment of the International Temperature Scale (Early 20th Century).: Thermocouples also played an important role in the establishment of international temperature scales. The internationally adopted standard temperature gauge (ITS-90) uses a thermocouple to determine the temperature.
Development of different types of thermocouples: With the development of technology, different types of thermocouples have emerged, such as platinum rhodium (PT-RH) thermocouples, nickel-chromium (Ni-CR) thermocouples, etc., each with its advantages for specific temperature ranges and environmental conditions.
Overall, the discovery and development of thermocouples is based on the continuous in-depth study of thermoelectric effects by many scientists. The wide range of applications of these devices is essential for temperature measurement in industry and science.