Development of a mid-IR Carbon Monoxide Sensor for a High-Pressure Combustor Rig

摘要

A sensor for carbon monoxide measurement has been developed using a mid-infrared quantum-cascade (QC) laser operating in the fundamental band (Δv=1) of CO near 4.5 μm. The fundamental band was chosen due to its stronger absorption line-strengths compared to the overtone bands near 2.3 μm and 1.55 μm. The mid-IR sensor was applied to a high-pressure combustor to determine the time-history of carbon monoxide and compare it to other measured parameters to fully characterize the combustor's performance. A mixture of natural gas, oxygen, and carbon dioxide was used for combustion. An emissions probe was connected to the exhaust of the combustor that fed into a cell with a known path length and two optical ports to allow mid-IR laser access for absorption. The temperature and pressure of the cell were measured, and the laser wavelength was monitored by a separate calibration process using a known CO/N2 mixture. The QC laser was also applied to validate the absorption time-history of a CO/Ar mixture at elevated temperatures and pressures in a shock tube at Texas A&M University. The spectroscopic parameters of CO were determined using HITRAN. The sensor was demonstrated to provide successful CO time-histories during combustion at both transient and steady combustor conditions.