K type thermocouple temperature measurement principle
ThermocoupleThe thermocouple thermometer, connecting wires and display instrument is composed of three parts.If the heat end of thermocouple cold, heat, so that heat at both ends of the temperature is different, the thermocouple loop will produce thermal potential, this phenomenon is called thermoelectric phenomena (thermoelectric effect).Potential generated in the thermocouple loop consists of the potential temperature and contact potential of two parts contact potential: it is a thermal conductor potential generated two different electron density of the contact of the.
When two different conductor A and B contact, electron density assumption conductors A and B were Na and Nb and Na>Nb, in the two conductor of the contact surface, diffusion of electrons in the two directions of the rate is not the same, to the number of electrons by the conductor and conductor B A diffusion than from the diffusion of B to the number of electrons in the A。 Conductor A lose electrons and significantly positive, conductor B was very significantly negatively charged electron。
Therefore, in the A, B two conductor contact surface is formed by A to B of electrostatic field, the electric field will hinder the diffusion was continued, and accelerate the electron in the opposite direction, from B to A。The electron number, reach the dynamic equilibrium state at last. At this time A, B also form a potential difference, the potential difference is called the contact potential. Nature of this potential with only two types of conductor contact point temperature, when the two conductor materials, contact potential only and contact temperature.
The higher the temperature, the more active electronic conductor, spread by the A conductor to the electronic B conductor is more, the electric field intensity produced at higher surface contact, the contact potential is greater。
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