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A new on-board portable emission measurement system (PEMS) for gaseous emissions has been designed and developed to meet CFR Part 1065 requirements. The new system consists of a heated flame ionization detector (HFID) for the measurement of total hydrocarbon, a heated chemiluminescence detector (HCLD) for the measurement of NOx, and a heated non-dispersive infra-red detector (HNDIR) for the measurement of CO and CO2. The oxygen interference and relative sensitivity of several hydrocarbon components have been optimized for the HFID. The CO2 and H2O quenching effect on the HCLD have been compensated using measured CO2 and H2O concentration. The spectral overlap and molecular interaction of H2O on the HNDIR measurement has also been compensated using an independent H2O concentration measurement. The basic performance of the new on-board emission measurement system has been verified accordingly with CFR part 1065 and all of the performances have met with CFR part 1065 requirement.

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.

Due to a need for a robust measurement system for on-board real-world vehicle emission measurement, a heated ND-IR(h-NDIR) technique has been developed and evaluated for its potential. The h-NDIR is capable of measuring CO and CO2 under wet-based condition by correcting interference from co-existing gas with an algorithm specially developed for the present study. The resulting H2O interference to the CO2 measurement is less than 0.01vol% for zero point and less than ±1% for span points and that of CO measurement is less than 0.001vol% for zero point and less than ±2% for span point against 0 to12vol% H2O. An on-board emission measurement system using the h-NDIR in combination with an Annubar® flow meter and an air to fuel ratio sensor has been evaluated. The result reveal correlation between the present system and a chassis test system to be within 7% for fuel consumption, within 5% for CO mass emission, and within 6% for CO2 mass emission.

Most of the recent clean diesel engines are equipped with an exhaust gas recirculation (EGR) technology in order to meet the strict criteria of NOx and particulate matter (PM) as required in the current emission regulations. More attention to strict EGR control is becoming required. Accurate and fast transient EGR ratio operation is becoming very critical in the field of the emission control. The EGR ratio is typically monitored by CO₂ trace method, in which CO₂ emitted from engine, is utilized as a tracer gas. The EGR ratio can be obtained from CO₂ concentration measured at engine intake and engine out at the same time. In this study, authors have developed a new EGR analyzer consisting of two CO₂ detectors, to achieve required performance for transient measurement, i.e., short delay time and quick response, negligible difference between two CO₂ detectors, and capability of wet measurement.

Nitrous oxide (N₂O) emission reduction has gained large prominence recently due to its contribution to the climate change as a greenhouse gas. The United States Environment Protection Agency (US-EPA) together with the United States Department of Transport (DOT) has already regulated the N₂O emissions from light-duty vehicles (LDV) to 0.010 g/mile. For LDV, N₂O measurement should be done from sample storage bags over the light-duty FTP drive cycles. N₂O emission standard of 0.10 g/bhp-hr for heavy-duty engines (HDE) is also finalized. The final N₂O standard becomes effective in 2014 model year for diesel engines. Usually raw or diluted exhaust is measured for HDE emission testing. Therefore, an analyzer capable of measuring N₂O from bag and from diluted sample continuously is required to support both LDV and HDE regulations.

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.

Regulatory compliance measurements for vehicle emissions are generally performed in well equipped test facilities using chassis dynamometers that simulate on-road conditions. There is also a requirement for obtaining accurate information from vehicles as they operate on the road. An on-board system has been developed to measure real-time mass emission of NOx, fuel consumption, road load, and engine output. The system consists of a dedicated data recorder and a variety of sensors that measure air-to-fuel ratios, NOx concentrations, intake air flow rates, and ambient temperature, pressure and humidity. The system can be placed on the passenger seat and operate without external power. This paper describes in detail the configuration and signal processing techniques used by the on-board measurement system. The authors explain the methods and algorithms used to obtain (1) real-time mass emission of NOx, (2) real-time fuel consumption, (3) road load, and (4) engine output.

The environmental effects of particulate matter (PM) emissions from vehicles are an increasing concern to those concerned with air quality. A variety of technologies have been developed to measure exhaust particulates. The automotive industry generally uses the gravimetric method to quantify particulate emissions. This method uses a combination of a dilution tunnel and filter to collect PM from the diluted sample gas. The collected PM is later weighed on a microbalance. Because this technique is a batch measurement, it is not possible to determine at what point of an emissions test drive cycle the soot, soluble organic fraction (SOF) and total PM are emitted. A more accurate characterization of PM emissions will require real-time PM measurement under transient test conditions.

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.

Portable emission measurement systems (PEMS) for particle number (PN) counting are under development in Europe, along with the vehicle testing protocol. A PN PEMS was developed by using a non-heated exhaust diluter, and applying a diffusion charger sensor (DCS) as the PN detector which is fitted with diffusion screens in order to selectively remove all particles, including volatiles, below 30 nm. Detection efficiencies of the DCS could be successfully adjusted by the number of diffusion screens installed before it. Equivalent results of the PN PEMS to a conventional system were observed by vehicle tests. However, variations were observed under specific vehicle operating conditions. Also, as part of the same program, a commercially available hand-held condensation particle counter (CPC) was compared with the standard CPC by vehicle tests as one of candidates to PEMS. Differences in PN concentrations were observed depending on the engine conditions

A novel total hydrocarbon (THC) emission concentration estimation model is proposed for reduction of engine development cost and simplification of exhaust measurements. The proposed method uses the absorbance spectra of a Fourier transform infrared (FTIR) spectrometer, which contains the information on a wide variety of hydrocarbons, as input. The model is based on machine learning algorithms including the least absolute shrinkage and selection operator (LASSO) regression and bagging techniques. To train the model, we created a dataset containing pairs of a spectrum of engine exhaust gas and the THC concentration. In addition, we incorporate absorbance spectra of individual hydrocarbon components and several inorganic components so that the model learns the contribution of each hydrocarbon to THC concentration and to ignore interferences of irrelevant gas components.

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.