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Green House Gas (GHGs) emission reduction has gained large prominence globally due to the climate change. Nitrous Oxide (N₂O) emission from transportation has significant share on global warming. Therefore, an instrument for sensing ultra-low level of N₂O is a key global demand. In this study, development of an instrument based on the Quantum Cascade Laser (QCL) has been attempted for measuring ultra-low level N₂O in automobile exhaust gas sampled in a sample storage bag. The QCL can emit coherent lights in a mid-infrared (Mid-IR) region where N₂O shows strong absorption peak. This absorption peak can be detected by an MCT (Mercury Cadmium Tellurium) type photovoltaic detector. The optics configuration used in this study can give a superfine resolution of the Mid-IR spectrum such as 0.002 cm-₁ in the target wavelength band. Therefore, utilizing this spectrometer, measurement of ultra-low level N₂O is possible without interference of co-existing gases.

For the past several years, manufacturers have been developing emission measurement systems for Super Ultra Low Emission (SULEV) measurements. The Bag Mini-Diluter (BMD) with an advanced exhaust flow measurement device is designed as an alternative to the traditional method for sampling vehicle exhaust, the constant volume sampler (CVS). Exhaust sampling instruments require system verification tests. The system verification test described and mandated for the CVS in the Code of Federal Regulations (CFR) §86.119-90(c) is a simulated test with propane. The very low concentration measurements required for SULEV regulations demand a more enhanced and accurate verification technique and procedure than the method described in the CFR. This investigation focuses on the technique and necessary equipment for verifying system integrity of the entire emission sampling system, including the Bag Mini-Diluter and the exhaust flow measurement device in the test cell.

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 high speed gas chromatography system has been developed for automotive emissions measurement. The system is capable of quantifying hydrocarbons from C2 to C12 compounds. The separation time required for an analysis is only five minutes. Major technical challenges were (1) tandem quick heat cold traps, (2) four parallel ovens design, and (3) the mid-point back flush technique. Demonstrations of the system have been done using FTP75 cold transient phase. The results indicate that the system is well suited for hydrocarbon speciation measurement with very simple and quick operations.

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.

This report describes a new, maintenance-free exhaust gas analysis system for automobile quality control. It incorporates non-dispersive infrared. (NDIR) gas analyzers employing a cross-flow modulation method which provides virtually drift-free performance and eliminates the need for optical adjustment, Analyzer modulation is by means of alternating the flow of sample gas and reference gas into two cells with a rotary valve of simple construction. Microcomputers are used for system control and to process the data. This system measures oxides of nitrogen (NOx), total hydrocarbon (THC) and carbon monoxide/dioxide (CO/CO2) with three analyzers. Full scale ranges of 50 ppm for NOx and 20 ppm for THC are feasible with cells merely 35 mm long. In each case the signal-to-noise ratio is 100. In actual operation, the system drift was so low that it required no span calibration over a period of three months.

Numerical models of three kinds of mass emission measurement systems, i.e. the constant volume sampler (CVS) system, the mini-diluter system and the direct modal-mass measurement system have been built on PC using a software called Mathematica®. The models are capable of simulating gas compounds concentration in the CVS bags and mass emitted during a test, using the time trend exhaust emission patterns, the exhaust gas flow rate pattern, and initial setting values like dilution ratio. Major error factors in the measurement systems, such as H2O condensation, gas compounds present in ambient air, delay and smoothing of the gas stream, and performance of the analyzers, can also be introduced to the calculation. Using the models, various techniques to optimize the sampling system are quantitatively compared.