Thermodynamic temperature label is the temperature label that does not rely on any specific temperature measurement material and its temperature measurement attributes. Of course, it is the ideal thermal label. However, we cannot create reversible heat machines, so we cannot measure the ratio of the heat absorbed by the reversible thermal machine from the high temperature heat source to the low -temperature heat source ratio.
At the same time, various thermometers of the temperature label of Celsius and the Hua's thermal benchmark are equipped with different liquids (such as kerosene, alcohol or mercury) according to different uses in the glass tube. The relationship, and the non -linear relationship of different liquids and temperatures is different from each other. Because of the temperature measurement material, the accuracy of the temperature standard is affected. For this reason, these experience temperature labels have been abandoned.
In order to solve the practical problem of international temperature standards, internationally negotiated decisions to establish a thermal temperature for both the temperature (that is, to ensure a certain accuracy), and use it convenient and easy to achieve Practical Temperature Scale of 1968 (IPTS-68), also known as international temperature label. It is an international protocol temperature standard, and it is a unified standard for temperature values in the world. The results of all the temperature meters and the results of the temperature measurement should be shown as an international practical thermal temperature. Its temperature value can be expressed as the value of the temperature or the temperature of the Celsius.
The basic idea of international practical thermal beacon is to divide the temperature range into several areas, and each region adopts a relatively simple thermometer to operate. However, their scale approaches the thermodynamic temperature label, that is, there are different standard formulas in different thermal areas. In this way, the scale on the thermometer is not necessarily uniform, but the measured temperature is as close to thermodynamic temperature as much as possible.
Agreement temperature standards have continuously improved with the improvement of scientific and technological levels in order to shrink the gap between the international practical temperature and thermodynamics temperature. For example, to determine the temperature of the standard temperature point more accurately; correct the internal insertion formula; improve the benchmark thermometer, etc.
From the perspective of the definition method of international temperature standards, it is still an experience temperature sign. However, it is based on thermodynamic temperature as the standard. It is similar to the temperature of thermodynamic temperature. This is the fundamental difference between it and various experience temperature beacons in history.
At present, the international practical temperature label of the International GM is formulated by the International Power Committee on the resolution of the 13th International Commission of Rights. Countries have been adopted since 1969, and my country has been implemented nationwide since 1973. The main point of the thermostat is:(1) The thermodynamic temperature of the international practical temperature in 1968 is the basic temperature. It is represented by T. Its unit is Kelvin and the symbol is K.
(2) The international practical temperature benchmark is based on the temperature specified value of 11 reappeared balanced state (defining fixed points), and the standard internal instrument of the standard in the standard on these fixed points. The temperature between the fixed points is determined by the inner insertion formula. 11 reappeared fixed points are a certain balance point of a certain type of pure substance (including the solidification point, boiling point, and three -phase point of different substances) in the international practical thermal insulation (revised version of 1975). The temperature specified value is listed in the attached table.
