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The performance of a soft ionization mass spectrometer (MS) has been investigated using nearly one hundred hydrocarbon components and nine inorganic components. Based on a list of typical hydrocarbon emissions from automotive exhaust, synthesized samples have been used to discuss the cross-sensitivity of the target components. The system has been shown to measure hazardous air pollutants (HAPs) such as 1,3-butadiene, benzene and toluene in the vehicle exhaust. As a result, the technique will prove to be very useful in emissions monitoring in the development of low emissions vehicles.

The regulated level of particulate mass for 2007 heavy duty diesel on-road engines is 0.01 g/bkhp-hr. Measurement of this low level of particulate by weighing is costly and time consuming. The weighing method must measure 100 μg or less of particulate on a filter that weighs about 100 mg with a resolution of ± 2.5 μg or better. This means that the microbalance and sampling handling procedure must be accurate within ±25 ppm by mass or ±1/40,000. It requires a microbalance with 0.1 μg precision housed in a special environment. Moreover, the weighing method involves a lengthy process. The filter must be equilibrated, and then pre- and post-weighed, usually with repeat measurements. An alternative to gravimetric analysis is a thermal mass analyzer that measures the semi-volatile organic fraction (SOF), as well as soot and sulfate fractions of the particulate matter (PM) collected on a cleaned quartz filter. The calibration of the thermal mass measurement is discussed in detail.

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.

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.

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.

With the need for emission measurements of super ultra low emission vehicles (SULEV), analyzer manufacturers have been required to produce more precise and accurate analyzers. In order to compare analyzers, the customer must understand the different specifications used by the analyzer manufacturers. One specification that some manufacturers have used is the limit of detection (LOD) to indicate the reliability of the analyzer output at low concentrations. There are various methods for determining the LOD for a given analyzer. The authors will demonstrate how variations in methodology can produce different LOD values for a specific analyzer and what it means for the automotive emission analyzers. It is also demonstrated that the standard deviations of a zero signal, which is related to LOD, can be heavily influenced by data processing, such as data length in use and/or data smoothing. The LOD values obtained will be compared to the limit of quantification (LOQ) for that analyzer.

The effects of engine and after-treatment control conditions on emissions fluctuation were evaluated and the technical idea for improving the repeatability in tailpipe emission measurement from DISI vehicles was provided. To improve measurement repeatability, low emissions analyzers with dilution air refining system were employed for this research. In addition, a new device that enabled monitoring of signals from the Engine Control Unit (ECU) was developed. A novel approach using these devices was applied to DISI gasoline engine vehicles equipped with de-NOx catalyst to clarify emission characteristics in the Japanese 10.15 test cycle emission tests. Through the tests, it is found that NOx emissions most correlated with the temperature at the de-NOx catalyst. CO and HC reaching the de-NOx catalyst played an important role in the temperature increase of de-NOx catalyst by exothermic reactions.

The accuracy and precision of exhaust gas mass emission measurement has recently come under close scrutiny as the absolute mass emission level has become lower. The uncertainty of the mass emission measurement can not be defined simply as it is a combination of many parameters in the measurement system. This paper lists and reviews the major factors that affect the accuracy in super-low emission measurement when using a constant volume sampler (CVS), such as analyzer performance, HC contamination, excessive dilution of sample gases, error in DF calculations and the variation of vehicle emission itself. Additionally, an alternative sampling system, using the bag mini-diluter (BMD) technique, is investigated in comparison with the enhanced CVS system, i.e. use of dilution air refiner, and heating of the whole system. Some ideas for reducing the HC contamination are also described as it is an important parameter that affects measurement accuracy in both the CVS and BMD systems.

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.

This paper presents a technique for examining “Goodness of Fit” of polynomial least square curves using “errorless” data. (The errors in “real world” data tend to mask a polynomial curve's lack of fit). A method of assessing the “quality” of real data before attempting to fit a curve to the data is also presented. If data “quality” proves satisfactory, a cubic spline curve can be generated which provides a much better fit to the data than can ever be attained using polynomial curves.

In order to control diesel engine emission, several after-treatment technologies have been studied and developed to reduce particulate matter (PM) and nitrogen oxides. Such reduction is making it hard to measure the mass of such pollutants. In the present study, a new method to analyze nitrogen compounds in vehicle particulate has been described. The method is based on the technique for separate analysis of SOF, soot and sulfates in particulate, which has been previously reported by the authors. The new method utilizes oxidation process in a furnace at high temperature and a chemiluminescence detector (CLD) to measure generated NO and NO2. In this paper, principle and concept of the method has been described. In addition, feasibility of the method for analyzing nitrogen compounds in vehicle PM has been discussed, with practical experiments using modeled samples and actual particulate.

The European Union has announced the next term emission regulations for light-duty vehicles which include particle number (PN) emission standards. The protocol for PN counting for the regulation is described in UNECE Regulation No.83. The PN counting system required for this regulation should consist of a Volatile Particle Remover (VPR) and a Condensation Particle Counter (CPC). The regulation also requires calibration of the VPR's Particle Concentration Reduction Factor (PCRF) periodically. Since the PCRF is directly used in the calculation of PN emission, an improper calibration of the factor can cause a significant error of PN emission result. This paper investigates propriety to use NaCl particles generated by atomizing method in the PCRF calibration as reference particles. As a result, it is shown that the NaCl particles can be used in PCRF calibration because of the sufficient stability when appropriate thermal treatment is applied.

Recently, after-treatment techniques for diesel engine emission have made remarkable progress with the development of suitable De-NOx catalysts. The urea-injection SCR system is one of the candidates for a high efficiency De-NOx method for diesel engine emissions. This system reduces NOx through a reaction with ammonia (NH3) that is generated from injected urea. In this system, it is very important to control the amount and timing of the urea injection so as to minimize the NH3 gas slip. Therefore, NH3 gas measurement is becoming important during the development of NOx after-treatment systems even though NH3 is not a target component of the current emission regulations. In this paper, a new NH3 gas analyzer utilizing a chemi-luminescence detection (CLD) method has been developed. The new NH3 analyzer consists of dual detectors (DCLDs) and a furnace for a NH3 oxidization catalyst. Real-time concentration of NH3 can be calculated from the difference of NOx readings of two detectors.

RDE (Real Driving Emissions) by definition is performed under a wide range of conditions. Altitude, as well as temperature, is one of the boundary conditions that depends on the area where the test is performed, which will vary from country to country. These boundary conditions not only affect the exhaust emissions from the vehicle, they also affect the accuracy of the PEMS (Portable Emission Measurement System). The effect of barometric pressure changes on a PEMS was evaluated by altitude simulation chamber and means of an RDE test on Mt. Fuji. This paper describes the challenges for PEMS measurement with barometric pressure variations and the advanced system that has been developed to meet them.

The Real Diving Emissions (RDE) regulation has been introduced since September, 2017 by utilizing the Portable Emissions Measurement System (PEMS). For the PEMS for the solid Particle Number (PN) measurement (PN-PEMS), the validation tests are required by comparing to the stationary PN measurement system on a chassis dynamometer prior to the on-road emissions testing. However, there are some cases that the emission results of PN-PEMS have big difference for that of the PMP system as the PN-PEMS does not have the same system configuration and calibration procedures as a PMP system. In this paper, the influence of the calibration procedure to the PN emissions results was observed by applying the calibration procedure of the PN-PEMS to the PMP system. The current systems configurations for PMP system and PN-PEMS, and the differences of them were described. And, the calibration procedure of the PN-PEMS was applied to the PMP system to adjust the system detection efficiency at 23 nm.

For the measurements of flow rate, pressure and/or temperature in an engine exhaust pipe, probes are often inserted into the exhaust pipe depending on the application. These measurement probes differ a lot in terms of their size and shape. The flow around the probes become further complicated due to the pulsation of engine exhaust flow. In this study, computational fluid dynamics (CFD) simulations were carried out and a zero-dimensional (0D) model was constructed to analyze the flow field around the probe and flow rate of a pulsating flow. The simulations and the measurements of the flow rate and pressure were performed on flows around a hexagonal prism inserted in a circular pipe which is intended to be a differential pressure flow meter. The velocity field was also measured using the particle image velocimetry (PIV) technique. The CFD simulation results were validated with the experiments for both steady and pulsating flows.

The use of alternative fuels, especially oxygenated fuels in automobile engines, has been increasing owing to the stringent global fuel economy and emission regulations. As a result, it is concerned that the emissions of alcohols and aldehydes have increased significantly. Aldehydes, formaldehyde (HCHO) in particular, are non-criteria pollutants that are acutely toxic and/or carcinogenic. Several reports have associated HCHO with potential lung and airway cancers. Therefore, emission regulations for these compounds have already been implemented in several areas worldwide. The conventional measurement (impinger, etc.) methods for HCHO possess advantages and disadvantages. HCHO can be measured with high sensitivity if measured in a batch. However, in real-time measurements, low concentration measurements are challenging.

Particles generated from lubricant in a gasoline direct injection (*GDI) engine were investigated in detail with the aim to understand the influence of components in lubricant on the amount of particles generated as well as their size. Analytical approach employed in this study was real-time engine tests combined with X-ray spectroscopic and electron-microscopic analyses. Real-time engine tests where particle number (PN) and particle size distribution were consecutively measured with oil consumption for lubricants with different formulas enabled us to extract information regarding lubricant-derived particles. This can be achieved only when sulfur species in lubricant are used as a “tracer” and thus, sulfur-free fuel possessing low PM Index (i.e., isooctane) needs to be used for the measurements.

The authors present a portable NH3 and N2O analyzer utilizing mid-infrared laser absorption spectroscopy for on-board emission measurements. The developed analyzer employs a newly developed absorption spectroscopy named “infrared laser absorption modulation”, hereinafter referred to as IRLAM, for the signal acquisition and concentration determination. Because of IRLAM’s simple and robust signal processing scheme, a highly sensitive, selective and robust measurement system can be realized within a compact size. The following performance metrics of the new analyzer are presented: linearity, detection limit, response time and zero/span drift. Notably, the detection limit (defined as 2σ of the zero signal) of ≤ 0.1 ppm is achieved in both NH3 and N2O measurements. The influence of vibration, and changes in environment conditions such as ambient temperature and atmospheric pressure, are also tested.

The measurement protocol of solid particle number with the lower detection limit (D50) at 10 nm (SPN10) is planned to be implemented in European emission regulations by means of laboratory-grade measurement systems. Furthermore, SPN10 measurement as the real driving emissions (RDE) regulations is under development by defining appropriate technical specifications for the portable emissions measurement system (PEMS). It is under discussion to implement SPN10 limits as one of additional pollutants to the new European emissions regulations, so-called “Euro 7”. As the Consortium for ultra LOw Vehicle Emissions (CLOVE) has proposed, RDE testing by means of PEMS will be the primary means of emissions determination for certification purposes. Measurement equivalency between laboratory-grade emissions measurement systems and PEMS is still important due to the necessity of validation in laboratories before on-road testing by comparing determined emissions by both.