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Continuous measurement of dilute exhaust gas from the CVS system, which provides gas concentrations proportional to the mass of emissions, is widely used for modal mass analysis of exhaust emission. Recently, exhaust gas flow rate measurement devices have become commercially available. Cost-effective raw exhaust modal mass analysis will be feasible with a combination of the new exhaust gas flow meters and fast response gas analyzers. In this paper, the benefits of raw exhaust modal mass measurement and the impacts of response time for the gas analyzer on the accuracy of exhaust mass calculations are discussed. Gas analyzer system with enhanced speed of response has been developed by hardware modification applied to the existing conventional bench system. De-convolution or inverse digital filter techniques that compensate the delay in the exhaust sampling system and the gas analyzer are described with comparisons to the hardware modifications.

For the purposes of environmental protection, regulations of particulate matter are becoming more stringent year by year. Accordingly, engine systems have been improved and particulate emissions are much lower compared to those of previous engine systems. The automotive industry generally uses a gravimetric method to quantify particulate emissions. It is becoming increasingly difficult to quantify particulate emissions using a conventional gravimetric balance because the amount of particulates continues to decline. In order to overcome this problem, a new method has been developed that uses gas analyzers to measure potentially as much as several micrograms of particulates. Furthermore, with this method, it is possible to simultaneously analyze volatile organic fraction (VOF), soot, and sulfates. The particles collected by a quartz filter are placed in a furnace at a specific temperature, and VOF and sulfates are vaporized in an inert atmosphere.

An approach for raw exhaust gas sampling, different from the conventional diluted exhaust gas sampling method, has been adopted for a solid particle counting system developed in the previous study. The system has been applied for evaluating solid particle emission from a DI diesel engine with DPF. In addition the filtration efficiency of the DPF has been tested from the real time concentrations, measured at upstream and downstream of the DPF. High accuracy and stability of measurement of the system against high exhaust gas pressure condition have been confirmed. The system response satisfies the requirement of ISO 8178-11. Excellent correlation of direct sampling and diluted gas sampling has been achieved with this system. It is found that the filtration efficiency changes during the engine test cycle and is strongly affected by the pre-conditioning of DPF.

A sulfur analyzer utilizing an ultraviolet fluorescent (UVF) detector has been developed to measure sulfur components in vehicle emissions. Generally, it is considered that an UVF detector cannot be used to measure sulfur components in vehicle emission due to a significant interference from NO in sample gases. In this study, an O3 injection technique has been developed to eliminate NO interference. Using this technique, the interference from NO has been reduced to less than 0.01 ppm with 3000 ppm NO. These result show a capability of utilizing UVF with this O3 injection technique to measure sulfur components in vehicle emissions including emissions with high concentrations of NO. An oxidation catalyst has also been evaluated to measure total reduced sulfur, TRS.