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The temperature sensor 1 Category
First, according to a non-contact measurement can be divided into two categories and contact:
1, non-contact temperature sensor
[123 ] it sensitive element are not in contact with the measured object, also known as non-contact thermometer. This type of meter used to measure the moving object, a small thermal capacity and small targets or rapid temperature variations (transients) of the object surface temperature, the temperature field can also be used to measure the distribution.
Non-contact temperature measurement advantages: from measurement limit temperature sensing element limits the degree of temperature, and therefore there is no limit on the maximum temperature can be measured principle. For high temperature of 1800 ℃, mainly non-contact method of temperature measurement. With the development of infrared technology, infrared radiation thermometry gradually expanded from a visible light, at room temperature until 700 ℃ the following are employed, and high resolution.
The most commonly used non-contact thermometer table based on the basic law of black body radiation, referred to as a radiation temperature meter. Radiation thermometry method comprising luminance (see optical pyrometer), radiation (see Radiation pyrometer) and colorimetry (see colorimetric thermometer). Various kinds of method can only measure radiation temperature corresponding to the temperature of luminosity, color temperature or radiation temperature. Only black (not absorb all of the radiation reflected light of the object) the measured temperature is the real temperature.
In automated production often need to use radiation thermometry to measure or control the temperature of the surface of certain objects, such as strip rolling temperature Metallurgy, roll temperature, various forging temperature and the molten metal in the smelting temperature of the furnace or crucible. In these circumstances, the surface emissivity measurement is rather difficult. Automatically measure and control the solid surface temperature, additional mirrors may be employed to make the surface of the blackbody cavity together with the test composition. Effect of the additional radiation can increase the effective radiation and the effective emission coefficient of the surface under test. Using the effective emission coefficient corresponding correction of the measured temperature by the instrument, the real temperature of the surface of the finally obtained measured.
The most typical additional reflector is a hemispherical mirror. Ball Center attachedDiffusing radiant energy near the surface of the measured reflected back by the hemispherical mirror surface formed additional radiation, thereby increasing the effective emission coefficient where Epsilon; emissivity surface materials, Rho; reflectance mirror. As radiometric real gas and liquid medium temperature of the heat-resistant material may be inserted into the tube to a certain depth to form a blackbody cavity method. Effective emission coefficient is obtained by calculation of the medium reaches the cylindrical cavity after thermal equilibrium. In the automatic measurement and control of the chamber temperature at the bottom of the can (i.e., medium temperature) obtained by correcting the measured temperature of the medium with the true value.
2, contact temperature sensor
detecting section and the measured object contact type temperature sensor in good contact, known as a thermometer.
thermometer by conduction or convection thermal equilibrium, so that the indication indicates the temperature of the thermometer can be directly measured object. Usually higher precision measurement. Within a certain temperature range, the thermometer may measure a temperature distribution inside the object. But for the moving body, the heat capacity is very small or small target object will have a greater measurement errors commonly thermometer bimetal thermometer, liquid glass thermometers, pressure thermometer, resistance thermometer, thermistor, and thermocouple and the like. They are widely used in industry, agriculture, commerce and other departments. In daily life, people often use these thermometers.
With the cryogenic technology research and application of superconducting technology in a wide range of defense engineering, space technology, metallurgy, electronics, food, pharmaceutical and petrochemical sector, low temperature thermometer to measure the temperature of 120K or less have been developed, The cryogenic gas thermometer, vapor pressure thermometer, acoustic thermometer, paramagnetic salt thermometer, quantum thermometer, low thermal resistance and low temperature thermocouple and the like. Low temperature thermometer requires the temperature sensing element small size, high accuracy, good stability and reproducibility. A porous high silica glass sintering carburizing carburizing heat resistance glass is a low temperature thermometer, temperature sensing element, it may be used to measure temperature in the range of 1.6 ~ 300K.
Second, the sensor materials and electronic components in accordance with characteristics of heat resistance and thermocouple into two categories.