Research On Gas Concentration And Temperature Field Reconstruction Based On The Fusion Of Acoustic And Laser Method

Real-time monitoring of the concentration and temperature in a mixed gas system has important significance for ensuring the safety, economy and environmental protection of industrial production. There are many technical difficulties in the measurement of multi physical field by a single measurement method respectively. A new method for the reconstruction of temperature and concentration field based on acoustic theory and tunable diode Laser absorption spectroscopy (TDLAS) is proposed in this article.The main research content of this article is as follows:(1) The theory of temperature measurement by acoustic is discussed. The temperature field in the test area is reconstructed by the function relation between temperature and local velocity of sound combined with ART, Tikhonov regularization and exponential SVD inversion algorithm. The exponential SVD inversion algorithm is proved to be the best by numerical comparison of the root mean square error. The locations of acoustic sensors are optimized based on particle swarm optimization in order to further improve the reconstruction accuracy. Effective through grid number is proposed first to judge the quality of the sensitive field.(2) The principle of the temperature and concentration measurement of TDLAS is described with the key research of two important optical parameters:line strength and linear function. CO2 absorption spectra were selected to simulate the two dimensional concentration field of the reconstructed region.(3) A new method for the reconstruction of the concentration and temperature field synchronously with the fusion of acoustic and TDLAS theory is introduced. The corresponding concentration and temperature of the gas is determined by the projection intersection of the fixed laser absorption coefficient and sound velocity to the level of temperature and concentration. The concentration and temperature field are reconstructed at the same time with the new method and the systematic error of this theory is analyzed in detail.(4) A single path measurement platform based on TDLAS theory is set up. The CO2 absorption spectra with the central wavelength of 1572.3nm is selected to measure the concentration of CO2. The fitting of initial light intensity and absorption spectra is improved. The measurement result is more accurate and it can meet the requirements of industrial measurement.