Research and development of the latest temperature

Research and development of new temperature sensors

temperature is a basic physical phenomenon. It is the most common and important process parameter used in the production process. Whether it is industrial and agricultural production, scientific research and national defense modernization, it is inseparable from temperature measurement and temperature sensor. It is one of the most frequently used sensors in modern testing and industrial process control. However, the accurate measurement of temperature is not easy. Even with a high accuracy temperature sensor, it is difficult to get the expected results if the measurement method is improperly selected or the measurement environment cannot meet the requirements

latest progress in temperature measurement

at present, although the technology of main temperature sensors, such as thermocouples, thermal resistances and radiation thermometers, has been mature, they can only be used in traditional occasions and cannot meet the requirements of many fields, especially in high-tech fields. Therefore, experts from all over the world are competing to develop various new temperature sensors and special practical measurement technologies

optical fiber temperature sensor

optical fiber (hereinafter referred to as optical fiber) has been published since the 1970s. With the development of laser technology, it has been proved in theory and practice that it has a series of advantages, and the application of optical fiber in the field of sensing technology has also been widely valued. Optical fiber sensor is a device that converts the measured state into measurable optical signal. It is composed of optical coupler, transmission fiber and photoelectric converter. At present, optical fiber sensors used to measure physical quantities such as pressure, displacement, strain, liquid level, angular velocity, linear velocity, temperature, magnetic field, current and voltage have come out, solving the measurement technical problems that are difficult to be solved by traditional methods. According to statistics, there are more than 100 different forms of optical fiber sensors used in different fields. It can be expected that in the wave of new technological revolution, optical fiber sensors will be widely used and play more roles

special temperature measurement and thermal cable

thermocouple is a traditional temperature sensor, which is widely used. In recent years, a new temperature measurement technology has been developed, which can have a unique application in fire accident early warning. This new type of temperature sensor is called special temperature measurement thermal cable, also known as continuous thermocouple or heating seeking thermocouple

the thermal cable uses the thermocouple thermoelectric effect, but it does not measure the temperature of the couple head, but the temperature of the highest temperature point along the length of the thermal electrode. Because of this unique function, it was initially laid in the cabin of aircraft carriers, destroyers, military aircraft and other military equipment by developed countries as high-precision technical equipment. At present, it has been widely used in various fields to prevent and reduce accidents and losses caused by "overheating"

main performance of thermal cable

at present, thermal cable mainly has two product types (FTLD and CTTC), which have the same temperature measurement principle, but different technical parameters

the material constitutes the outer protective tube: FTLD type adopts double-layer polytetrafluoroethylene, and CTTC type adopts chromium nickel iron alloy. In order to effectively avoid the immersion of dust, grease, moisture and other media in the measurement environment, as well as false alarms caused by different temperature ranges, different materials are used. Temperature measuring element: K-type thermocouple

overall dimension at present, the length of existing products is about 6~15m. If the length needs to be increased, several thermal cables can be connected. The outer diameter FTLD is f3.5mm and CTTC is f9.3~18.7mm, which can be installed in the harsh environment that traditional probes cannot be laid

working temperature FTLD is -40~200 ℃, CTTC is -40~899 ℃

graduation and sensitivity the graduation of thermal cables is similar to that of ordinary thermocouples. Because the "temporary" thermal contact of continuous thermocouples is not closely connected, and the two electrodes outside the thermal contact are not completely insulated, the output thermoelectric potential of safe and reliable thermal cables is slightly lower than that of the same kind of thermocouples, and the converted temperature is about a dozen degrees Celsius, which is acceptable for fire alarm prediction

the response time depends on the thermal capacity of the thermal cable per unit length, and the thermal capacity is determined by the material and quality. Therefore, reducing the size of the cross section of the continuous thermocouple can effectively shorten the response time

the bending radius is not only related to the performance and quality of the constituent materials of thermal cables, but also related to the compactness of the isolation materials. Generally, the bending radius is 10~20 times of the outer diameter of the thermal cable

quartz thermometer

with the development of production and science and technology, all departments have higher and higher requirements for temperature measurement and control, especially for high-precision, high-resolution temperature transmission. 5. The text displayed on the display panel of the variable-frequency single column tensile testing machine is clear, whether it will be blurred; The demand for sensors is becoming stronger and stronger, and ordinary sensors are difficult to meet the requirements

characteristics of quartz thermometer

high resolution up to 0.001~0.0001 ℃

the high accuracy is in the range of -50 ℃ ~120 ℃, and the accuracy is ± 0.05 ℃. The accuracy of ordinary thermometer is ± 0.1 ℃

the error is small, the thermal lag error is small, and the response time is 1s, which can be ignored

stable performance. It is a frequency output sensor, so it is not affected by amplifier drift and power supply fluctuation. Even if the sensor is set at a long distance (such as 1500m), it will not be affected. However, 4. The power supply should be disconnected regularly, and its impact resistance is poor

application of quartz thermometer

quartz thermometer can not only be used for high-precision and high-resolution temperature measurement, but also can be used as a standard thermometer for value transmission. It can also be used for precision temperature measurement in the field of steady-state temperature or for precision temperature control of thermostatic bath, and can also be used for remote multi-point temperature measurement

acoustic thermometer

acoustic temperature measurement technology has the advantages of simple temperature measurement principle, non-contact, wide temperature measurement range (0~1900 ℃), measurable and so on. It has been applied to the temperature measurement and control of industrial processes such as power plants, waste incinerators, cement rotary kilns and so on

use ultrasonic to measure the gas temperature

use the thermometer that measures the propagation speed of ultrasonic wave in the gas and changes due to different temperatures is called ultrasonic thermometer. Ultrasonic measurement of gas temperature has the advantages of fast response speed and no influence of external wall thermal radiation. The measurement objects are very wide, ranging from the average temperature of the gas above the roller ladder to the temperature measurement of mixed gas explosion and combustion of internal combustion engine

the working principle of ultrasonic measurement of gas temperature is the same as that of acoustic temperature measurement. There are two methods of measuring sound velocity:

pulse method measurement. If the distance between loudspeaker and receiver is l, the propagation time is τ， Then u=l/τ， Find U. When measuring all winds in the field, if the sound velocity is measured directly, there will be an error. In this case, it is more accurate to choose the average speed of the speaker and the receiver for exchange measurement

resonance method measurement u can be obtained by using the resonance frequency f=u/l

solid ultrasonic thermometer

the thermometer that uses the propagation speed of sound waves in solids and changes with temperature is called solid ultrasonic thermometer. Because the sensitivity of sound velocity increases with the increase of temperature when sound waves propagate in solids, this thermometer is more suitable for high temperature measurement

nuclear level IV resonance thermometer (NQR thermometer)

nuclear magnetic resonance is the magnetic resonance of the nuclear system. A substance with nuclear spin is in a static magnetic field. When an electromagnetic wave is added in the vertical direction of the static magnetic field, it will absorb the electromagnetic wave of a certain frequency, which is called nuclear magnetic resonance. In potassium chlorate kcio3 crystal, ci35 atomic nucleus whose nuclear spin has electric quadrupole moment produces energy level transition and absorbs electromagnetic waves in axisymmetric electric field gradient, which is called nuclear fourth-order resonance. The thermometer made of the characteristic that the resonant absorption frequency decreases with the increase of temperature is called nuclear level Four resonance thermometer. The thermometer can be used as a standard thermometer or a high-precision practical thermometer

nqr thermometer features

high accuracy and high resolution accuracy up to ± 0.005k; The resonance absorption frequency has a good correlation with temperature, which is 5khz/k near room temperature, and the resolution is 1mk

it does not need the relationship between graduation temperature and absorption frequency, but only depends on the structure of kcio3, which fundamentally ensures good reproducibility (below 6kz)

the interchangeability is good at the three-phase point of water. Its interchangeability is ± 10Hz, and its performance is extremely superior

the output is a frequency signal, which is easy to protect high precision. Standard radio waves, TV signals, etc. can be used as high-precision reference signals for digital processing

wide temperature range. For high-precision measurement, it is suitable for the range from room temperature to low temperature

automation can be achieved from detecting weak absorption signals to converting them into temperature

thermal noise thermometer

due to the thermal movement of electrons, potential fluctuations caused by thermal noise can be generated at both ends of the resistance. This kind of thermal noise is also called Johnson noise. There is a definite relationship between the voltage and temperature of thermal noise. Thermal noise thermometer can be made by using the relationship between thermal noise voltage and temperature. The thermal noise thermometer has the following characteristics: it does not need graduation; It has nothing to do with the sensor material and is not affected by pressure; The resistance value of the sensor hardly affects the measurement accuracy; Wide temperature measurement range (k)

therefore, the thermal noise thermometer is expected to become an ideal temperature measurement method. However, the voltage signal produced by thermal noise thermometer is small, the signal processing is difficult, and the operation is complex. So far, it has not been applied

semiconductor integrated circuit temperature sensor

it is well known that the forward voltage drop of the base emitter of a transistor decreases with the increase of temperature. Using this inherent characteristic of p-n junction, a temperature sensor can be made. AD590 integrated circuit temperature sensor is a typical one, and DS1820 is the latest development

dsl820 intelligent temperature sensor

intelligent temperature sensor is developed on the basis of semiconductor integrated temperature sensor. Its main advantage is that it adopts digital technology and can directly output the measured temperature in digital form; Able to transmit data remotely; The user can set the upper and lower limits of temperature, and has the function of automatic alarm when the limit is exceeded; It has its own bus interface, which is suitable for all kinds of microprocessors and singlechip computers, and is convenient to develop a temperature measurement and control system with certain intelligent functions. Among them, DS1820 is a typical intelligent temperature sensor

basic characteristics

dsl820 is a modular digital temperature sensor produced in the United States. All sensing elements and conversion circuits are integrated in an integrated circuit shaped like a triode. Because of its small size, fast conversion, high resolution and digital transmission, it is widely used in multi-point temperature measurement and intelligent temperature detection system. Compared with other temperature sensors, DS1820 has the following characteristics:

● unique single line interface mode that can implement motor function reconstruction through this study

● support multi-point group function

● no peripheral components are required in use

● temperature measurement range is -55~+125 ℃

● the measurement results are transmitted serially in the form of 9-bit digital quantity. (end)