Method of TDLAS temperature measurement under influence of interference absorption peak
MEI Yuanyuan;CAI Jing;CHANG Haitao;XU Jiangwen;Changcheng Institute of Metrology & Measurement;College of Metrology & Measurement Engineering, China Jiliang University;
In order to solve the problem that the interference absorption peak affects the accuracy of temperature measurement in the current TDLAS wavelength scanning direct absorption method temperature measurement, an integral absorbance calculation method based on the symmetry of absorption spectral line was proposed. By using the absorbance in the frequency range from the center frequency to the side of the noninterference absorption peak, the integral absorbance in the whole frequency domain is obtained according to the symmetry, so as to eliminate the influence of the interference absorption peak and improve the temperature measurement accuracy. Two H_2O absorption lines at 7185.6 cm~(-1)and 7444.4 cm~(-1)were selected, and 8 temperature points were selected for temperature simulation calculation in the range of 400～2600 K using the absorption spectrum simulation data. At the same time, a TDLAS measurement system was set up in the laboratory environment to measure the tube furnace temperature in the temperature range of 573～ 1173 K, and the measurement results of the symmetrical integral absorbance calculation method of absorption spectral lines were compared with those of the single-peak method that ignored the influence of interference peaks. The results showed that the average temperature relative errors calculated by simulation are 1.11% and 5.66% respectively, while the average temperature relative errors measured by experiment are 1.02% and 9% respectively, which verifies the feasibility and accuracy of temperature measurement based on the integrated absorbance obtained by the symmetry of absorption spectral line in the presence of interference absorption peak. It provides an important reference for promoting the development of TDLAS temperature measurement technology.