Study On Method Of Early Fire Warning Based On Tunable Diode Laser Absorption Spectroscopy

Large number of ancient buildings was destroyed by fire in recent years,so the fire for ancient building must saves developed from fighting and saving passively into detecting and warning actively,Strengthening the prevention of ancient building fire,control,detection,fighting is the urgent requirement of society,In order to avoiding and reducing fire for ancient building,The early detection and warning are important.The traditional fire detection technologies are mainly concentrated in characteristic parameters,produced in after several stages of fire,but the fire at this time has been unable to control.For product fire early-gas,Tunable Diode Laser Absorption Spectroscopy(TDLAS)is proposed to detect fire gases to achievement an early fire warning.With the characteristics of high accuracy,fast response,and multi-gas detection simultaneously,Tunable Diode Laser Absorption Spectroscopy(TDLAS)has now become the fastest growing online monitoring method,especially for the detection of harmful trace gas.The paper analyzes fire gas with Tunable Diode Laser Absorption Spectroscopy(TDLAS),designs the fire alarm system hardware and software system,and finally completes the system simulation analysis and experimental verification.Firstly,In order to lay the foundation for the study of the subject,the domestic and foreign research situation and problems at this stage about gas analysis and fire alarm are analyzed.Then the working principle about TDLAS for gas quantitative analysis are researched;Wavelength modulation technique,the second harmonic technique and gas concentration inversion algorithm and other key technologies are derived;Hardware and software systems based on TDLAS for gas quantitative analysis are designed,includes a light source drive,signal modulation and demodulation,the gas absorption cell,the data acquisition module and software design about the laser control and data acquisition.Finally,the simulation analysis and experimental verification of the system are completed.System simulation is implemented with MATLAB,then the system has been tested experiments.The results show that the maximum amplitude of the gas absorption of the second harmonic signal is proportional to the concentration of the gas,in other words,Second harmonic signal can be used to calculate the concentration of the gas fire.