Non-contact temperature sensor sensitive components in contact with the measured object and do not

Non-contact temperature sensor sensitive components in contact with the measured object and do not , also known as non- contact Thermometer . This Automotive Temperature Sensors is used to measure moving objects instrumentation , small target and heat capacity smaller or rapid temperature changes ( transient ) the surface temperature of the object , can also be used to measure the temperature of the temperature distribution . The most commonly used non- contact Thermometer Based on the basic law of blackbody radiation , called radiation thermometer tables. Including brightness radiation thermometry method ( see optical pyrometer ) , radiation ( see radiation pyrometer ) and colorimetry ( see colorimetric thermometer ) . Various types of radiation thermometry method can only measure the temperature corresponding to the luminosity , temperature or radiation colorimetric temperature . Only blackbody ( absorbs all radiation is not reflected light of the object ) is the real temperature of the measured temperature . To determine the true temperature of an object , it must be material surface emissivity correction . The emissivity of the material surface depends not only on temperature and wavelength , but also with the surface state , and microstructure of the coating , etc., and therefore difficult to accurately measure . In automated production method often requires the use of radiation to measure the temperature or the surface temperature control some , such as metallurgical rolling temperature of the strip , the roll temperature, the forging temperature, and a variety of molten metal in the smelting furnace or a temperature in the crucible . In these particular cases , surface emissivity measurement is rather difficult . For solid surface temperature automatic measurement and control, the use of additional mirror surface with the composition of the measured blackbody cavity . Additional effects of radiation can increase the effective surface to be measured and the effective radiated emission coefficient . By using effective instrument for emission coefficient measured temperature corrected accordingly , and ultimately obtain the true temperature of the measured surface . The most typical auxiliary reflector is hemispherical reflector . Coolant Temperature Sensor the center of the sphere diffuse radiation reflected back by the mirror surface of the hemispherical form additional radiation, thus increasing the effective emission coefficient of the formula: wherein ε is the emissivity material , ρ is the mirror reflectivity. As to the gas and the liquid medium to the real temperature radiation measurements, the heat-resistant material can be inserted into the tube to a certain depth to form a blackbody cavity approach. Obtained by calculation to reach thermal equilibrium with the medium after the effective emission coefficient cylindrical cavity . In the automatic measurement and control can use this value for the measured temperature at the bottom chamber ( ie, medium temperature ) is corrected to obtain the true temperature of the media .