Laser-absorption sensor suite for crank-angle-resolved, <i>in situ</i> measurements in the exhaust of a high-performance internal combustion engine—II: CO, CO₂, and unburned hydrocarbons

Laser absorption sensors have been developed for measuring carbon monoxide (CO), carbon dioxide (<i>C</i><i>O</i>₂), and unburnt hydrocarbons, immediately downstream of the exhaust valves in an internal combustion engine. A spectroscopic database containing absorption linestrengths and collisional broadening parameters for CO and <i>C</i><i>O</i>₂, as well as absorption cross-sections for E85 fuel, was developed at engine-relevant temperatures. The sensors were designed with a 31 kHz bandwidth to measure high-speed exhaust dynamics with crank-angle resolution. Their utility was demonstrated in the exhaust manifold of a high-performance, single-cylinder development engine. At engine-relevant conditions, the measurement uncertainties for both the CO and <i>C</i><i>O</i>₂ sensors are 10%. These sensors, when combined with simultaneous temperature, pressure, and water mole fraction measurements, form an exhaust sensor suite, which can provide insights into rapid processes in the exhaust of an internal combustion engine.