Introduction of various temperature sensors
There are hundreds of temperature sensors. Today we divide them into two categories, one is a contact temperature sensor, and the other is a non-contact temperature sensor.
The characteristics of the contact temperature sensor: The sensor directly contacts the object to be measured for temperature measurement. Since the heat of the measured object is transferred to the sensor, the temperature of the measured object is reduced, especially when the heat capacity of the measured object is small, the measurement accuracy is low. Therefore, the prerequisite for measuring the true temperature of an object in this way is that the heat capacity of the object to be measured must be large enough.
The characteristics of non-contact temperature sensor: It mainly uses the thermal radiation of the object to be measured to emit infrared rays to measure the temperature of the object, which can be used for long-distance measurement. The manufacturing cost is high, but the measurement accuracy is low. The advantages are: does not absorb the heat of the measured object; does not interfere with the temperature field of the measured object; continuous measurement does not produce consumption; fast response speed, etc.
In addition, there are microwave temperature measurement temperature sensors, noise temperature measurement temperature sensors, nuclear magnetic resonance thermometers, Mössbauer effect thermometers, Josephson effect thermometers, thermograph temperature measurement temperature sensors, heat flow meters, jet thermometers, cryogenic superconducting conversion thermometers, Optical fiber temperature sensor, etc. Some of these temperature sensors are already in use, and some are still under development.
Contact temperature sensor
1. Commonly used thermal resistance
Range: -260～+850℃; accuracy: 0.001℃. After improvement, it can work continuously for 2000h, the failure rate is less than 1%, and the service life is 10 years.
2. Ultra-low temperature thermal resistance The two carbon resistors can measure the temperature of -268.8～253℃-272.9～272.99℃ respectively.
3. The measuring range of ceramic thermal resistance is -200～+500℃, and the accuracy is 0.3 and 0.15.
4. Thermal resistance of pipes and cables The temperature measurement range is -20～+500℃, the highest is 1000℃, and the accuracy is 0.5.
5. Thermistor is suitable for high-sensitivity small temperature measurement occasions. The economy is good and the price is cheap.
Non-contact temperature sensing
1. Radiation pyrometer is used to measure the high temperature above 1000℃. There are four types: optical pyrometer, colorimetric pyrometer, radiation pyrometer and photoelectric pyrometer.
2. Spectral pyrometer The YCI-I type automatic temperature measurement general-purpose spectral pyrometer developed by the former Soviet Union has a measuring range of 400～6000℃. It uses an electronic automatic tracking system to ensure that the automatic measurement has sufficient accuracy.
3. Ultrasonic temperature sensor is characterized by fast response (about 10ms) and strong directionality. At present, there are products that can be measured up to 5000℉.