In-Situ Measurements of CO, CO_2, and H_20 Combustion Emissions with Diode Laser Sensors

摘要

CO, CO_2, and H20 emissions from a laboratory flame are measured in-situ using diode laser sensors in the hot, post-flame gases and the cooler exhaust ducts. CO is a toxic regulated pollutant and CO_2 is an important greenhouse gas; together these two species provide a measure of the total fuel carbon. CO_2 and H20 are the major products of hydrocarbon combustion and can be used to determine combustion efficiency. Light from multiple lasers traverses the flame effluent and each species is monitored by absorption of light that is resonant with nearinfrared vibrational overtone transitions. Absorption spectroscopy yields pathaveraged concentration measurements without intrusive probes that can perturb the gas flow or reaction chemistry. In-situ absorption diagnostics can provide real-time monitoring of the effluent without the inherent time lag for gas transport or risk of species conversion in extractive sampling probes. A CO detection limit less than 0.1 ppdm with a 1 second measurement time is well below the 9 ppm TLV allowed for 8 hours exposure, and this detection limit is sufficient for remote, on-road measurements to quantify the CO emission from the cleanest autos.