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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.

Investigation of operating parameters have been carried out for an FTIR system dedicated for emission analysis. Discussions are focused on the key parameters, such as spectral resolution, gas cell dimensions, quantification algorithm, and sample gas treatment. The spectral resolution has to be determined so that the scan rate is high enough to make transient analysis, the minimum detection limit is low enough to carry out high sensitivity measurement, and no cross sensitivity can be recognized. A trade-off relationship between the response and the sensitivity exists for the gas cell design. Small volume of the cell is desirable when gas replacement is considered. On the other hand, the sensitivity can be increased by enlarging the cell volume to obtain long optical path. Both quantification algorithm and the sample gas treatment have to be well arranged to obtain accurate concentration values of the gas compounds sampled from the tailpipe.

The subject of engine emissions is expected to be at the forefront of environmental regulations and consumers’ concerns for years to come. As technology develops to comply with new and different requirements in various regions of the world, understanding the fundamental principles of how engine emissions occur, and how they can be properly measured, is vitally important. Engine Emissions Measurement Handbook, developed and co-authored by HORIBA Automotive Test Systems team addresses the main aspects of this subject. Written with the technical user in mind, this title is a must-have for those involved in engine development and testing, and environmental researchers focusing on better ways to minimize emissions pollution.