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Light-duty vehicle emission measurement test protocols defined in the Code of Federal Regulation (40 CFR Part 1066) allow sampling particulate matter (PM) of all phases of Federal Test Procedure (FTP-75) on a single PM sampling filter by means of flow-weighted sampling in order to increase PM mass loaded on the filter. A technical challenge is imposed especially for partial flow dilution systems (PFDS) to maintain a precise dilution ratio (DR) over such a wide sample flow range due to the subtraction flow determination method of dilution air and diluted exhaust flows, because the flow difference is critical at high DR conditions. In this study, an improved flow weighting concept is applied to a PFDS by installing a bypass line with a flow controller in parallel with the PM sampling filter in order to improve DR accuracy during flow-weighted sampling.

Technologies of 4WD chassis dynamometers (CHDY hereinafter) have advanced dramatically over the past several years, enabling 4WD vehicles to be tested without modifying their drive-train into 2WD. These advances have opened the use of 4WD-CHDY in all fuel economy and emission evaluation tests. In this paper, factors that influence the accuracy of fuel economy tests on 4WD CHDY are discussed. Fuel economy tests were conducted on 4WD CHDY and we found that most of the vehicle mechanical loss is the tire loss and that stabilizing the tire loss of the test vehicle is essential for the test reproducibility.

Two new techniques have been applied to FTIR emission analysis which add significant potential to automotive emission measurement. One of these is the use of the mathematical multivariate analysis which is called the partial least squares method. This spectrum discrimination technique, in combination with high resolution spectrum data, enables superior analysis for heavy-overlapping species in the emission. The other technique is a flow conditioned gas sampling cell which is designed especially for real time emission measurement. The flow in the gas cell has been analyzed with computer simulation and the gas cell has a flow conditioner inside with a 10 meter optical path. Seven seconds of 90 percent gas replacement time can be achieved with this cell. As a result, highly accurate realtime data can be obtained with relatively fast response. In this paper, spectrum factors extracted from overlapping species and quantification simulations are shown using standard gases.

Recently, it was reported that the atmospheric pollution levels of nitrogen dioxide (NO2) and particulate matter (PM) are not decreasing despite the introduction of stricter vehicle emission regulations. The difference between conditions of the test cycles defined by the vehicle emission regulations and the real driving can contribute to the differences between expected and actual pollution levels. This has led to the introduction of in-use vehicle emission monitoring and regulations by means of a portable emission measurement system (PEMS). An optimized on-board PM analyzer was developed in this study. The on-board PM analyzer is a combination of a partial flow dilution system (PFDS) particulate sampler and a diffusion charger sensor (DCS) for real-time PM signals. The measuring technology and basic performance of the analyzer will be explained. Acceleration of the vehicle can cause uncertainty of flow measurement in the PM sampler.

Since the introduction of Euro IV legislation [1, 2], Selective Catalytic Reduction (SCR) technology using liquid urea injection is (one of) the primary methods for NOx reduction in many applications. Ammonia (NH3) is the reagent and key element for the SCR system and its control calibration to meet all operational requirements. TNO and Horiba are highly motivated to facilitate a correct interpretation and use of emissions measurement data. Different hypotheses were defined to investigate the impact of temperatures and flow rates on urea decomposition. These parameters are known to strongly affect the urea decomposition process, and thus, the formation of NH3. During a test campaign, different SCR catalyst feed gas conditions (mass flow, temperature, species and dosing quantities) were applied. Three Horiba FTIR gas analyzers were installed to simultaneously sample either all upstream or all downstream of the SCR brick. Both steady-state and dynamic responses were evaluated.

Fine particle emissions from engine exhaust have attracted attention because of concern of their higher deposition fraction in alveoli. Since it was observed that sizes of solid particles in exhaust of conventional internal combustion engine technologies are mainly distributed above 30 nm and the mainly irreproducible sensitivity to volatile particles can be reduced, the current solid particle number (PN) measurement methodology was targeted to PN emissions particles larger than 23 nm. The necessity of the measurement of particles smaller than 23 nm is now under discussion. It is also surmised that there is difference between emissions under regulatory defined test cycles and real driving conditions. Currently, implementation of further real driving emission regulations utilizing portable emissions measurement systems (PEMS) is in place for the EU and being actively discussed in other regions.

An on-board solid particle number (PN) analyzer (OBS-ONE-PN) has been developed to measure PN concentrations in engine exhaust under real-driving conditions. Specification of OBS-ONE-PN is based on the recommendation in PEMS-PN draft. OBS-ONE-PN consists of primary diluter, heated transfer tube, heated catalytic stripper (CS), secondary dilutor and particle detector. Volatile fractions which is emitted from the automobile engine are removed by CS, and then only solid particles are counted by a condensation particle counter (CPC). Finally, the system provides results in number concentration. The detailed specifications relating to the OBS-ONE-PN performance such as dilution factor accuracy, volatile particle removal efficiency, overall detection efficiency and durability test results are described in this paper The OBS-ONE-PN is used to characterize PN emission from a gasoline vehicle.

The accuracy of low-level emission measurements has become increasingly important, due to the development and implementation of ULEV, SULEV, and PZEV vehicles. Measurement of these decreasing levels of automotive emissions requires new sampling and measuring techniques. Several alternative emission sampling techniques have been investigated to minimize measurement variability and maximize system repeatability. An alternative technique to obtain accurate low-level emissions measurement from SULEV vehicles is the Bag Mini-Diluter, which uses a proportional signal from an Exhaust Volume Measurement Device to sample vehicle exhaust. Crucial to successful proportional sampling of vehicle exhaust flow is the performance of the Exhaust Flow Measurement Device. This study evaluates an Exhaust Volume Measurement Device commonly used with a Bag Mini-Diluter.

The Particle Measurement Programme (PMP) established under the United Nations Economic Commission for Europe has developed the solid particle number (PN) measurement methodology, which has relatively higher sensitivity than the particulate matter measurement protocol. The first PN emission regulation was introduced in 2011. The stationary PN measurement system (PMP system) has been applied in the chassis and the engine test cells. In recent years, real driving emissions (RDE) measurement is attracting attention. Portable emissions measurement systems for PN measurement (PN-PEMS) which can be installed on vehicles during RDE testing are available now. The European RDE regulation requires validation of PN-PEMS by comparing emission measurement results with a stationary PMP system on a chassis dynamometer prior to the on-road emissions testing. Measurement differences between the PN-PEMS and the PMP system has to be within the tolerance defined by the regulation.