K type thermocouple temperature measurement principle
Shenzhen K type thermocouple temperature measurement principle of
thermocouple thermometer by thermocouple, connecting wires and display instrument of three parts.
If the hot end of thermocouple to heat, cold, hot on both ends of the temperature is different, in the thermocouple loop will produce thermoelectric potential, a physical phenomenon is called thermoelectric phenomena (
The thermoelectric effect)
The potential in the thermocouple loop consists of two parts, the thermoelectric potential and contact potential contact potential: it is two kinds of electron density of different conductor a thermoelectric potential produced when contact with each other.
when the two different conductor A and B in contact, the electronic density hypothesis conductor A and B respectively Na and Nb and Na>
Nb, the contact surface in two conductors, electrons in two direction diffusion rate is not the same, the number of the electrons by A spread the conductor B conductor than from B spread to A number of electrons.
Conductor lose electrons and positive, A conductor B was very electronic and negatively charged.
so, in A, B two conductors of the contact surface to form A electrostatic field from A to B, the electric field will hinder diffusion movement to continue, the accelerated electrons outwards at the same time, multiply the number of the electrons from B to 4, finally reach dynamic equilibrium.
At this time also form A potential difference between A and B, the potential difference is called contact potential.
This potential is only with the nature of the two kinds of conductor temperature contact point, when two conductor material, contact potential is only related to its junction temperature.
the higher the temperature, the more active the electrons in A conductor, by A conductor to spread to B the more electronic conductor, the interface of space electric field intensity is higher, and therefore the greater the contact potential.
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key words: thermal resistance, thermocouple, thermal resistance, platinum resistance, PT100, PT1000, pressure sensor and digital temperature sensor