CO2高温光谱参数测量系统设计与实验

CO_2和CO被称为燃烧效率指示性气体,燃烧流场中CO_2的精确测量对工业燃烧过程的节能减排和发动机燃烧状态诊断等都具有重要意义.研究CO_2气体的高温光谱参数,包括:线强、自加宽系数、温度系数,可提高燃烧过程中CO_2浓度的测量精度和可靠性.为了获得可用于燃烧诊断的CO_2吸收线的高温光谱参数,基于可调谐半导体激光吸收光谱技术设计了一套最高温度可达2 073 K的精确控温控压气体光谱参数测量系统.采用该系统开展了CO_2R(50e)吸收线(中心频率为5 007. 787 cm-1)的高温光谱测量实验,获得了温度范围1212～1873 K内多个压强下的纯CO_2气体的大量高温吸收光谱,经热辐射背景扣除、基线拟合、时频转换、多线组合非线性最小二乘法拟合等数据处理过程,得到温度范围1 212～1 873 K内CO_2R(50e)吸收线的线强、自加宽系数及温度系数,其中线强不确定度1. 5%,自加宽系数不确定度小于4. 5%.这些参数是对现有数据库的补充和完善,对燃烧诊断中的CO_2浓度检测有很大帮助,能够满足燃烧过程中CO_2浓度精确反演的需求.

Design and experiment of CO2 high temperature spectrum parameter measurement system

CO₂ and CO are called the key indicators of combustion efficiency. Accurate measurement of CO₂ in the combustion flow field is very important for energy conservation and emission reduction in industrial combustion process and engine combustion state diagnosis. Researching intensity, self-broadening coefficient, temperature-dependence exponent and other parameters of CO₂ in high temperature, may improve the accuracy and reliability of measurements for CO₂ concentration. A precise temperature control and pressure control gas spectroscopic parameter measurement system with a design temperature up to 2073K based on absorption spectroscopy has been developed for the measurement of spectroscopic parameters of the R(50e) line at 5007.787cm-1 of CO₂. A large number of high temperature survey spectra of the CO₂ R(50e) line were recorded at temperatures between 1212K and 1873K and many pressures through the system. Through background subtraction, baseline fitting, time-frequency conversion, multi-line combination and nonlinear least squares fitting, and other data processing based on the CO₂ R(50e) survey spectra, intensity, self-broadening full-width and temperature-dependence exponent at temperatures between 1212K and 1873K were obtained. The uncertainty of line strength is less than 1.5%, the uncertainty of self-broadening full-width is less than 4.5%. These parameters are supplement and improvement to the existing database. They are helpful for the detection of CO₂ concentration in combustion diagnosis to ensure the accurate inversion of CO₂ concentration in the combustion process.