| In recent years, China’s natural gas industry is developing rapidly. Gas leak detection technology is an important means of monitoring and evaluation related to storage and transportation security. Vehicle gas detection device based on spectral absorption technology provides a new technique for confirmation the problem of pipeline and discovering the spill more efficient and accurate.The study based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) was designed and implemented in vehicle gas leak detection system, and gives a preliminary evaluation of its detection performance. The main research work includes:Photoelectric detection subsystem has been designed and implemented. Research the method of harmonic signal extraction for detection beam and drive of laser modulation waveform. The generation of the modulation waveform and quadrature demodulation implement all digitally in the programmable logic device platform. Laser current drive is designed and trans-impedance amplifier is used to analog signal link. Temperature control device was designed for providing a constant temperature performance to laser in mm level.Data transmission protocol for vehicle systems was designed and developed, and token protocol UDP for the multi-host cooperating structure was implemented based on the RS232underlying. Programmable test system (PTS) based on PC was designed, and a test for the monitoring of the language CTS is developed for the study, and MATLAB Engine is used to implement advanced computing and visualization of data.Using the expanded beam fiber collimator and focusing lens structure, broom swept radio detection probe for one meter is designed. Optical structure, the detection circuit and data analysis module was integrated together. Systems deployed are completed in the experiment vehicle. Methane mass detection condition experiments has been done at20km/h and60km/h speed in the outdoor air, and a detection limit of less than3ppm is achieved and detected the gas leakage properly. |
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