The working principle of the platinum rhodium thermocouple1

Abstract: the size of the thermocouple thermoelectric potential produced by, when material is uniform thermocouple, has nothing to do with the length and diameter of thermocouple, and only at the ends of the thermocouple material composition and temperature difference;

platinum-rhodium thermocouple principle

( Platinum rhodium thermocouple) When two different kinds of metal materials ( Platinum rhodium - Platinum) （ Or hot electrode) Form a closed loop, because temperature changes will be in between these two kinds of metal to produce small current ( Voltage) This phenomenon is called the seebeck effect ( 塞贝克, 效果) 。 If the other side, The reference side) Maintain temperature ( General to 0 ℃) When measuring WenDuan ( The welding end) With the reference to produce circuit, will generate electromotive force, then the circuit of thermoelectric emfs, into a single value function of measuring end temperature. This measurement method to measure the temperature of thermoelectric emfs components, namely the two different pairs of metal conductor, referred to as a thermocouple. Thermocouple thermoelectric emfs, its size is only related to thermal electrode materials and temperature difference on both ends, has nothing to do with the hot electrode length and diameter.

platinum-rhodium thermocouple, in fact, a kind of energy converter, it converts heat into electricity, using thermoelectric potential generated by the measuring temperature, the thermocouple thermoelectric potential, several problems should be paid attention to the following:

( 1) The thermocouple thermoelectric potential is the difference on both ends of the thermocouple temperature function, rather than a function of temperature difference on both ends of the thermocouple;

（ 2) The size of the thermocouple thermoelectric potential produced by, when material is uniform thermocouple, has nothing to do with the length and diameter of thermocouple, only with the thermocouple at both ends of the composition of the material and temperature difference;

( 3) When the two thermocouple wire thermocouple material component is determined, the size of the thermocouple thermoelectric potential, only related with the thermocouple temperature difference; If the thermocouple cold end temperature keeping ( General to 0 ℃) , so that the thermocouple thermoelectric potential is just the end temperature of the single value function, so we are in use, should try to keep the thermocouple cold end temperature constant, avoid have larger temperature fluctuation, in order to get better temperature curve, after understanding the working principle of thermocouple, we should also according to the different environment, choose the most appropriate your thermocouple temperature.

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