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Principle of Fluorescent Fiber Optic Thermometer
Fluorescent fiber optic thermometer is a temperature measurement device based on the photoluminescence phenomenon of fluorescent materials. Compared with traditional thermocouple measurement methods, it has advantages such as anti electromagnetic interference, مقاومة التآكل, and high temperature and high pressure resistance. It can achieve real-time temperature detection in more harsh external environments and has broad application prospects. The fluorescence fiber temperature measurement system developed by Huaguang Tianrui based on fluorescence fiber temperature measurement technology has unique advantages compared to other temperature measurement methods. It deeply explains the working principle of the fluorescence fiber thermometer, analyzes the key factors affecting temperature measurement, and establishes a theoretical basis for the design of the fluorescence fiber thermometer. Then, the overall design of the fluorescent fiber thermometer was carried out, including the optical path, circuit, software, structure, and algorithm. To verify the feasibility of the overall plan, a comparative experiment of temperature measurement was designed, and the overall plan was analyzed and studied based on actual data. The fiber optic temperature measurement system has been summarized and discussed, and future directions and ideas for improving fiber optic temperature measurement have been proposed.
The technology of fluorescent fiber thermometer:
(1) Key technologies of optical mechanical structure:
Using a single optical fiber to simultaneously transmit light source signals and fluorescence signals, reducing the volume and fluorescence loss of the fluorescence fiber thermometer;
Using filters to screen excitation light and fluorescence;
Adopting advanced technology to achieve sealing of fluorescent fiber optic probes.
(2) The key technology of demodulation circuit:
Using dynamic adjustment signal input to achieve periodic switching and output power adjustment of the light source, indirectly achieving amplitude adjustment of the sampling signal;
Using correction signals to amplify sampled signals and correct biases;
Simplify circuit components and integrate control, processing, communication and other functions into chips, which is conducive to the miniaturization of fluorescence fiber thermometers;
Using fitting algorithms to calculate fluorescence lifetime and convert temperature;
Filter the fluorescence lifetime results using a filtering algorithm to reduce errors and improve the accuracy of the output results.
Design of Fluorescent Fiber Optic Thermometer:
1、 The fluorescence probe part of the optical path adopts advanced technology to replace traditional probe protection schemes, increasing the flexibility and sealing effect of the probe;
2、 The electrical characteristics of some components in the demodulator vary with temperature, and a dynamic adjustment signal is added to the circuit to adjust the stability of the signal waveform, balance waveform accuracy and error;
3、 The data processing section proposes a combination filtering method for data processing, which effectively reduces errors and improves the accuracy of output results;
4、 The software part is designed with multiple working modes and parameter reading and configuration functions to improve the adaptability of this system.
Why use fluorescent fiber optic temperature measurement:
Temperature is an important reference quantity in daily production and life, and with the continuous advancement of technology and the development of human society, people have increasingly high requirements for temperature in daily industrial production and daily life. In the field of industrial production, steel production, from raw material processing, ironmaking to mold casting, steel rolling, الخ., has strict temperature control. For example, the preservation and transportation of fresh food in daily life, as well as temperature monitoring and control, have a significant impact on food safety and taste. لذلك, the importance of accurate temperature measurement is self-evident. At the same time, in the face of increasingly specialized technical requirements classification and continuous refinement of technical conditions, corresponding measurement equipment and measurement technology classification are also increasing, and the demand for temperature measurement devices designed for various specialized environments and special requirements is constantly emerging. Under special circumstances and extreme environmental conditions, as well as different requirements such as fast dynamic response, remote measurement, and multi-point measurement, traditional temperature measurement and signal transmission have become increasingly difficult to meet different demanding conditions, and the difficulty of implementation has also increased.
Fluorescence fiber optic temperature measurement function:
حالا, traditional temperature measurement equipment has some practical difficulties in use in many special measurement environments, such as the harsh environment of the temperature measurement point, such as corrosion, high voltage, narrow space, الخ., or the strong electromagnetic interference in the area where the measurement point is located, such as temperature monitoring of motors and high-voltage transformers. In response to the above difficulties, most new temperature sensors need to have advantages such as strong electromagnetic interference resistance, good insulation performance, استجابة سريعة, and small size. With the application of various new materials and processes, as well as the exploration of new measurement methods, a variety of new temperature measurement devices have emerged. One of them is temperature measurement equipment based on fiber optic communication technology.
Before the birth of fiber optic fluorescence measurement technology, there were already various temperature measurement techniques. The first mercury thermometer was born as early as 1714. Mercury thermometers belong to the expansion measurement technology, which utilizes the principle of thermal expansion and contraction, and the space occupied by mercury volume varies with different temperatures. The scale of a mercury thermometer vividly displays the numerical value of temperature. Based on this principle, in addition to liquids, measurement technologies for different materials such as gases and metals have also emerged in the future. With the continuous advancement of technology, the vigorous development of electricity has brought new measurement ideas and technologies. Thermocouple technology is based on the different electrical properties of electronic components at different temperatures, and is currently the most widely used and diverse temperature measurement technology. بالإضافة, optical communication technology has also pointed out a new direction for temperature measurement. Infrared temperature measurement devices made using the different characteristics of thermal radiation of objects at different temperatures can achieve temperature measurement over long distances and large ranges, as well as indirect temperature measurement methods using intermediate devices such as fluorescent materials and gratings.
Characteristics of various temperature measurement systems
Expansion temperature measurement system
1. Low price 2. Convenient operation and reading 3. Simple and easy to manufacture mechanism
1. Low accuracy 2. Easy to damage 3. Cannot achieve automation
Infrared thermal imaging temperature measurement system
1. Non contact temperature measurement 2. Easy to use 3. Low cost 1. Large error
2. Can only measure surface temperature. 3. Cost of manual inspection
نظام قياس درجة الحرارة اللاسلكي
1. Easy installation 2. Low cost
1. Poor reliability, carrying batteries, short lifespan, high false alarm rate
2. Affects the performance of insulators
3. The large volume of sensors affects heat dissipation and poses a safety hazard to primary equipment
Fiber Bragg Grating Temperature Measurement System
1. It can achieve quasi distributed temperature measurement, suitable for long-distance and large area measurement
2. Adopting fiber optic technology to resist electromagnetic interference
3. Good insulation performance
1. The sensor probe is large and difficult to install
2. Low reliability, grating is prone to desensitization and failure
3. Short lifespan
4. Unable to achieve single cabinet matching and on-site display
5. Expensive price
Advantages of Fluorescent Fiber Optic Temperature Measurement System
1. Safe and reliable, can achieve calibration free, with good consistency, interchangeability, and stability
2. عمر طويل, maintenance free
3. The probe has a small volume and can penetrate deep into the hot spot to achieve true monitoring
4. مكافحة التداخل الكهرومغناطيسي, good insulation performance
5. It can achieve on-site display, making it easy to integrate into the operating system
6. Easy installation
Fluorescence temperature measurement technology converts temperature signals into optical signals based on the photoluminescence phenomenon of fluorescent materials, and utilizes the high efficiency of optical fiber in optical signal transmission to effectively achieve real-time and long-distance temperature measurement. Fiber optic fluorescence measurement technology inherits the advantages of fiber optic sensing technology. Compared with other temperature measurement technologies, it not only has the characteristics of corrosion resistance, good insulation, and small size, but also effectively reduces electromagnetic interference. وفي الوقت نفسه, fiber optic fluorescence measurement technology also has the characteristics of long lifespan, maintenance free, good stability, and consistency. بالإضافة, this system also features real-time display, easy integration into other systems, and convenient installation.
Application scenarios of fluorescence fiber optic temperature measurement system
Fluorescence temperature measurement technology, with its characteristics of anti electromagnetic interference, حجم صغير, good dynamic response, مقاومة التآكل, long transmission distance, and low transmission loss, has gradually expanded its application fields to medical applications such as microwave heating therapy, transformer internal temperature detection, or substation temperature monitoring in unique or proprietary environments and requirements, in addition to temperature monitoring and measurement commonly used in daily production and life. It has received attention and research from scholars.
Transformers generate a large amount of heat during operation, which can affect the performance of their various components, leading to changes in transformer load capacity, operational reliability, and lifespan. حالا, oil immersed transformers and oil immersed transformers are widely used in the power system. The appearance of the transformer body is the outer wall of the oil tank, and its interior mainly consists of transformer winding coils and cooling oil. The slender structure of the fiber optic fluorescent probe allows it to be installed and fixed on the transformer coil, minimizing data monitoring lag and improving monitoring accuracy to the greatest extent possible.
High voltage switchgear is commonly used in power system high-voltage situations to control voltage switching. The main temperature measurement point of the switchgear is the contact joint, but the space in this area is relatively narrow. The size and diameter of fiber optic fluorescent probes are very small. The slender shape of the fiber optic probe allows it to be easily bent and inserted into narrow spaces, and then fixed in contact with the stationary contact, which does not affect the normal operation of the equipment and is therefore safer. بالإضافة, fiber optic fluorescence temperature measurement technology can also be applied to mining of coal, oil and other minerals, as well as storage of raw materials (such as oil and natural gas) in industrial production that require long-term strict temperature monitoring.
The research on fiber optic fluorescence temperature measurement technology has been ongoing for many years since its inception, but with the continuous emergence of new devices and the expansion of application fields, the performance requirements for sensors have increased, and there is still a lot of room for development; On the other hand, new materials with superior performance continue to emerge, and sensitive materials with new characteristics provide us with new choices, making the design of sensors face new concepts. As a promising technology, fiber optic fluorescence temperature sensing technology can be widely applied in some special industries, such as medical, high-voltage electrical equipment monitoring, metallurgical processing, and online temperature detection in aerospace. لذلك, establishing a comprehensive and systematic theory of fiber optic fluorescence temperature detection, providing simple and practical technologies, is of great significance for improving the level of scientific instruments in this field in China.
