Influence of Spectral Line Broadening on Measurements of NH<sub>3</sub> Concentration in Automobile Exhaust Using Near-IR Laser Absorption Spectroscopy

Kotaro Tanaka; Masatoshi Takano; Shuji Iimura; Kai Miyamura; Mitsuru Konno

doi:10.4271/2014-01-2833

Recently, highly sensitive near-IR laser absorption spectrometers have been employed to measure ammonia (NH₃) emissions. These instruments allow in-situ measurements of highly time-resolved NH₃ emission levels in automobile exhaust. However, the effect of the automobile exhaust CO₂ in NH₃ measurements has not been studied in detail. Because the CO₂ concentration in automobile exhaust is 2 to 3 orders of magnitude higher than the NH₃ concentration, there is a possibility that spectral overlap by CO₂ lines and/or the spectral broadening of NH₃ by CO₂ could affect the measured NH₃ levels.

This study had two major objectives. First, the effect of CO₂ on the measured NH₃ concentration was assessed using our developed near-IR laser absorption spectrometer. The second objective was to provide on-board NH₃ measurements in the hybrid gasoline automobile exhaust using the developed spectrometer.

As a result, the CO₂ in automobile exhaust was found to affect the measured NH₃ concentration. The NH₃ concentrations in automobile exhaust differed by few percent at 0%-20% CO₂ concentrations. The NH₃ concentration values in automobile exhaust were corrected by using these data. On-board measurements of NH₃ concentration in the hybrid gasoline automobile exhaust system showed that the NH₃ emission prevailed under the conditions in which the automobile was running rich or during overly aggressive driving (e.g. on highway).

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Influence of Spectral Line Broadening on Measurements of NH ₃ Concentration in Automobile Exhaust Using Near-IR Laser Absorption Spectroscopy 2014-01-2833

SAE MOBILUS

Influence of Spectral Line Broadening on Measurements of NH 3 Concentration in Automobile Exhaust Using Near-IR Laser Absorption Spectroscopy 2014-01-2833

SAE MOBILUS

Influence of Spectral Line Broadening on Measurements of NH ₃ Concentration in Automobile Exhaust Using Near-IR Laser Absorption Spectroscopy 2014-01-2833