Open-Path FTIR Measurements of NO_x and Other Diesel Emissions

摘要

We have demonstrated the feasibility of using an open-path Fourier transform infrared (OP-FTIR) monitoring technique to address the across-road characterization of diesel vehicle emissions for criteria pollutants and hazardous air pollutants. Four sets of OP-FTIR measurements were made on diesel exhaust from a stationary class 8-tractor that was projected through the OP-FTIR measurement path. The OP-FTIR system was of a monostatic, coaxial, single-telescope design. A physical path of 7 m was used between the FTIR sensor and the corner-cube retroreflector, resulting in a total round-trip beam path of 14 m. In this diesel engine exhaust test, nitrogen oxides (NO_x) were identified in all runs. In addition to the NO_x, we detected and measured concentrations of ethylene, carbon monoxide, carbon dioxide, formaldehyde, and aliphatic hydrocarbons. This is the first report of diesel engine emission measurements using OP-FTIR in an across-road configuration.