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An analyzer based on Quantum Cascade Laser (QCL) has been developed for chemical sensing of gaseous nitrogen compounds (NO, NO2, N2O and NH3). The QCL can emit lights in a mid-infrared (Mid-IR) region where these nitrogen compounds have strong absorption. This laser optics configuration can give a super fine resolution of the mid-infrared spectrum. Therefore, utilizing this spectrometer can reduce the interference caused by the spectral overlap of co-existing gases in engine exhaust. The developed analyzer has been evaluated using actual engine exhaust to confirm the influence from coexisting gases and the measurement accuracies and stabilities. Very low detection limit (less than 1 ppm) and quick response time (less than 2 sec) have been achieved even with the newly developed analyzer.

A new hydrogen analyzer using a magnetic sector mass spectrometer (MS) has been developed to perform continuous analysis of hydrogen gas concentrations in exhaust gas. This method is insensitive to substances other than hydrogen gas ions and so is not easily affected by the presence of other molecules. In addition, this analyzer has a fast response compared to conventional hydrogen analyzers, which employ other measurement principles. The T90 response time is about 1 second. The minimum sensitivity is few tens of ppm. Because of these characteristics, the sector MS method has significant potential for analyzing hydrogen concentrations in exhaust gas continuously. In this study, the authors performed continuous emissions measurement of several kinds of gasoline engine vehicle in a chassis test cell using the hydrogen gas analyzer in combination with other gas analyzers.

Fuel cell is one of the promising candidates for low emission and high efficiency power plant for the next generation vehicles. Currently, general discussions are focused on from where and how to supply hydrogen to the fuel cell stack in a vehicle. Two major concepts are presented; (1) storing pure hydrogen on-board and (2) use of hydrocarbon as a fuel in combination with on-board fuel reformer system to extract hydrogen. Although the reformer idea seems to be rather complicated than the pure hydrogen, the fuel reformer system is very much demanded, due to the energy density of liquid fossil fuel and availability of fuel supply infrastructure. In the development of the fuel reformer system, gas composition measurements are required to achieve (1) efficient hydrogen extraction, (2) low carbon monoxide concentration to protect PEM stack, and (3) low emission.

An analyzer based on Quantum Cascade Laser (QCL) has been developed for chemical sensing of gaseous nitrogen compounds (NO, NO₂, N₂O and NH₃). The QCL can emit coherent lights in the Mid-infrared (Mid-IR) region where these nitrogen compounds exhibit strong absorption tendency. Therefore, it is possible to detect very low concentration gas. QCL can also give a super fine resolution of the spectrum in this region. Therefore, utilization of this spectrometer can reduce the interference caused by the spectral overlap of coexisting gases in automobile engine exhaust. In the previous study, the fundamental concept of development along with some basic performance of the analyzer had been reported. In this study, improvement of performance has been attempted. Especially, the cell design, response time of NH₃, broadening the measurement ranges, and increasing the data sampling speed have been considered.

The Bag Mini-diluter (BMD) is a proportional exhaust sampling system that is being studied as an improved measurement system for ultra-low level vehicle exhaust emissions. The traditional method for sampling vehicle exhaust has been the constant volume sampler (CVS) technique. This method dilutes the entire exhaust output from the vehicle, meters the mixture, and then takes a proportional sample for measurement. In contrast, the Mini-diluter sampling method meters a small sample of raw exhaust, and then dilutes this sample to a fixed dilution ratio. This approach offers new opportunities to improve the quality of the sample measurement at very low levels, which will be crucial for accurate vehicle exhaust emission measurements on vehicles that meet the ULEV and SULEV standards. A number of test programs have compared the performance of the Mini-diluter to the CVS on vehicles certified to Tier 1 and LEV standards, and the results demonstrated favorable correlation.