| With the rapid development of society, lives of human beings are changing silently.Methane as one of the most significant clean energy has been widely used. What methane brings to human beings is not only convenience, but also threats to the safety of people's lives and property, for example, the methane explosions in coal mines and gas leakage while transmission. Therefore, it is full of meanings to design a new methane sensing system with quick response and high sensitivity.Among different kinds of methane sensors, optical fiber sensors is much safer and have longer lives compared to others. After the research on domestic and abroad status of optical fiber methane sensors, a new optical fiber methane sensing unit based on reflective gas cell is proposed in this paper. According to the properties of gas spectral absorption, the main structure of the system, single wavelength combined with double optical paths, is determined.The module of the whole system is set up based on theory and formula derivation.A reflective gas cell is designed in this paper, which results in the extension of the optical length. The cost of the sensor would also benefit from the newly designed gas cell by using one single optical fiber to transfer the signal, which proves the distributed optical fiber methane sensor is practicable. In this paper, software combined with hardware is applied to weak signal detection and processing which is a key factor to the whole system. Frontward amplifier realizes the enlargement of the signal, and then the signal would be transferred to the PC by NI DAQ. The programs on the LabVIEW software would complete the processing of the data. In this way, the flexibility of gas sensor would be highly improved.By analyzing experiment results and data, the optical fiber methane sensing unit based on reflective gas cell presented by this paper shows a high sensitivity and accuracy and provides future research with a new direction. |
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