基于TDLAS的光学探针式初期火灾探测系统  

Tunable diode laser absorption spectroscopy(TDLAS)-based optical probe initial fire detection system

作　　者：李开远 袁宏永 陈涛 黄丽达 LI Kaiyuan;YUAN Hongyong;CHEN Tao;HUANG Lida(Institute of Public Safety Research,Department of Engineering Physics,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学工程物理系,公共安全研究院,北京100084

出　　处：《清华大学学报（自然科学版）》2023年第6期910-916,共7页Journal of Tsinghua University(Science and Technology)

基　　金：国家重点研发计划课题(2022YFC3003103)。

摘　　要：为了实现火灾初期探测,设计了光学探针式初期火灾探测系统。该探测系统基于可调谐二极管激光吸收光谱(TDLAS)技术与激光遥测技术,采用波长为2.33μm的激光光源与波长调制光谱(WMS)技术,利用激光作为光学探针替代传统吸收测量腔室,实现了火灾初期基于CO路径积分体积分数的开放光路探测。系统对10m内的反射面实现了不低于20(μL/L)·m的检测限。国标木材热解火实验表明,该文研制的系统与提出的阈值报警算法具备实现初期火灾报警响应的能力。[Objective]Current fire smoke detectors are susceptible to many factors that can significantly affect their accuracy,such as environmental disturbances and combustion states,resulting in false alarms.Moreover,point fire detectors inevitably cause time lags for alarms due to their optical darkrooms and insect-proof nets,delaying critical rescue time.Therefore,focusing on the limitations of point carbon monoxide(CO)detectors with absorbing gas cells,this study proposes an optical probe initial fire detection system based on tunable diode laser absorption spectroscopy(TDLAS)and laser remote sensing.Then,we present a preliminary threshold-based fire alarm algorithm.[Methods]Accordingly,this study's detection system relied on TDLAS and laser remote sensing,including wavelength modulation spectroscopy,to extract CO signals from an open-path geometry.A laser(wavelength=2331.93nm)was also used as an optical probe to replace the traditional absorption measurement chambers,achieving a CO path-integrated volume fraction measurement under complex initial fire conditions.First,we tested the signal responses of this detection system for different CO volume fraction combinations,incidence angles,and reflectances using a standard gas cell(length=0.5m)placed at the optical path and a standard reflector plate placed 4.4m from the light source to examine the limitations of the system.Then,we tested the received signal power at different distances,examined the CO released from wood pyrolysis fires,calculated the corresponding integral volume fractions,and set an appropriate threshold based on the detector's limit to verify whether this optical probe fire detector could meet the requirements.[Results]The experimental results of our limitation tests showed the following:(1)At a distance of 4.4m and target reflectance of 0.69,the theoretical detection limit was approximately 5(μL/L)·m,and the actual detection limit was 26.75(μL/L)·m.(2)As the reflectance decreased,the absolute value of the signal intensity also decreased,increasing

关 键 词：激光吸收光谱 激光探测 一氧化碳(CO) 火灾探测 

分 类 号：TN247[电子电信—物理电子学]