Simultaneous and interference-free measurements of temperature and C2H4 concentration using a single tunable diode laser at 1.62 µm

• Published in: Optics express 2019-06, Vol.27 (13), p.17887-17904
• Main Authors: Gao, Guangzhen, Zhang, Ting, Zhang, Gang, Liu, Xin, Cai, Tingdong
• Format: Article
• Language: English
• ISSN: 1094-4087
• DOI: 10.1364/OE.27.017887

In the tunable diode laser absorption spectroscopy-based diagnostics, the absorption of the measured target species may be influenced by the interference absorption from other vapor-phase species and the extinction from particles and liquid droplets, especially at high temperatures and pressures. Here, we report the first application (to our knowledge) of a differential absorption diagnostic for interference-free, simultaneous measurement of temperature and ethylene concentration using a single distributed-feedback diode laser near 1.62 μm. According to the detailed study of the C2H4 spectra in this region, two wavelength pairs are chosen to measure the temperature based on six selection criteria. C2H4 concentration is measured by one of the selected wavelength pairs with higher differential absorption. To validate the developed system, experiments are performed in a well-controlled heated static cell at a range of temperatures (300-900 K) and pressures (1-6 atm). The measurement accuracies for temperature and ethylene concentration are 1.83% and 1.65%, respectively, over the considered ranges. The precision, stability, and detection limit are also analyzed to validate the system's performance. This system can potentially be applied in a variety of combustion applications.