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It is well known that an EHC (Electrically Heated Catalyst) is very effective in reducing cold start HC emissions. However, the large electric power consumption of the EHC is a major technical issue. When installed in the exhaust manifold, the EHC can take advantage of exhaust heat to warm up faster, resulting in a reduced electric power demand. Therefore, a structurally durable EHC which can withstand the severe manifold conditions is desirable. Through the use of a extruded monolithic metal substrate, with a flexible hexagonal cell structure and a special canning method, we have succeeded in developing a structurally durable EHC. This new EHC installed in the exhaust manifold with a light-off catalyst directly behind it demonstrated a drastic reduction in FTP (Federal Test Procedure) Total HC emissions.

Catalytic performance can be improved by increasing geometric surface area (GSA) and reducing bulk density (BD), namely heat capacity, using high cell-density / thinwall advanced ceramic substrates. The advanced substrates, such as 3 mil/600 cpsi and 2 mil/900 cpsi have improved the catalytic performance over the conventional substrates, and are expected to help in complying with future emission regulations, as well as catalyst downsizing. This paper describes the effects of GSA and BD using Pd-based catalysts. The reduction of hydrocarbons emissions was demonstrated significantly at close-coupled location, and dual bed design was proven effective. The effectiveness at under-floor location was not as significant as the close-coupled location.

Particle Number (PN) regulation was firstly introduced for European light-duty diesel vehicles back in 2011[1]. Since then, PN regulation has been and is being expanded to heavy-duty diesel vehicles and non-road diesel machineries. PN regulation will also be expanded to China and India around 2020 or later. Diesel Particulate Filter (DPF) is significant factor for the above-mentioned PN regulation. This filter technology is to be continuously evolved for the near future tighter PN regulation. Generally, PN filtration performance test for filter technology development is carried out with chassis dynamometer, engine dynamometer or simulator [2]. This paper describes a simplified and relatively quicker alternative PN filtration performance test method for accelerating filter technology development compared to the current test method.

The electrically-heated catalyst ( EHC ) has been established as an effective technology for lower-emission regulations. High electrical power consumption was a major concern for the EHC system in the past. This issue was addressed through the development of the EHC design and the alternator-powered EHC system combined with a light-off ( L/O ) catalyst. The subsequent challenges have been to prove the EHC's reliability and durability. NGK has developed a durable, extruded EHC for very severe exhaust system installations. In addition, the EHC's electrical connector system is required to meet high performance and reliability objectives under extreme environmental conditions unique to this application. This report describes the design concept of NGK's EHC including our new electrical connector system and durability results. In summary, the NGK EHC design concept has been confirmed to have excellent durability performance.

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.

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

The future emission limits for gasoline fuelled passenger cars require more and more efficient exhaust gas aftertreatment devices - the catalytic converter being one essential part of the complex system design. The present paper summarizes the results of several basic research programs putting major emphasis on the application of highly sophisticated three-way catalyst technologies being taylored for the utilization on ultra thin-wall ceramic substrates. In the first part of the investigation the following effects were examined in detail: Different washcoat loadings at constant PGM-loadings Different volumes of catalysts for constant amounts of PGM and washcoat Similar washcoat technologies at different ratios of WC-loading to precious metal concentration in the washcoat.

As emissions regulations are becoming more stringent, various efforts to improve emission performance have been carried out in different areas including the honeycomb structure of catalytic converters. This report describes the development of a simulation tool to predict emission performance and simulation results for different cell structures. The simulation model was developed based on global kinetic chemical reaction model [1]. Having tuned the reaction parameters through a light-off test and estimated oxygen storage capacity through an oxygen storage test, we ultimately tuned the model in a vehicle test (with Bags 1 and 2, FTP 75). As a result, the simulated cumulative tailpipe emissions are within ±25 percent of the test results. Parameter analyses indicate that the amount of emissions decreased as the density of cells increased and that the amount of emissions also decreased the thinner the wall thicknesses were.

The effect on engine performance of insulating combustion chambers was simulated for a turbocharged direct injection diesel engine. We developed a low heat rejection (LHR) diesel cycle simulation. It includes a gas flow model, a heat transfer model, and a two zone combustion model. In the heat transfer model, convective and radiation heat transfer between the gas and walls was computed, taking into account the combustion chamber surface temperature swings. In the combustion model's combustion zone, the temperature and the chemical equilibrium compositions were determined. They were used to calculate the NO formation rate by assuming a modified Zeldvich mechanism. The combustion zone temperature was also used to estimate the radiation heat transfer. Simulations were performed of various combustion chamber surface materials and various LHR levels. The factors which affect thermal efficiency and exhaust emissions were deduced and their influences discussed.

Particulate matter (PM) emission from vehicles is one of the biggest issues in terms of environmental protection and influence to human body. Thus, a variety of measurement technologies have been develop so far. Currently, a gravimetric method is most commonly used in the automotive industry, partially because it is specified in the regulations. This method uses a combination of a dilution tunnel and a filter that collects the PM from the diluted sample gas with subsequent weighting by a micro balance. However, since this technique is a batch measurement, it is impossible to determine at what point of the emissions test the Soot, SOF (Soluble Organic Fraction), and the total PM are emitted. Thus the demand for real-time PM measurement under transient test conditions has increased.

Thermal shock failures have been considered as one of the most significant issues for wall flow type ceramic diesel particulate filters during their regeneration. This paper describes the experiments which were conducted in order to study effects of heating rates of the accumulated diesel particulate on the thermal shock failure of the filters using an NGK soot generator. The results showed favorable heating rates of the particulate in terms of the amounts of the accumulated particulate up to which the filters are safely regenerated.

This paper proposes a high temperature manifold converter with a thin wall ceramic substrate, such as; 4mil/400cpsi and 4mil/600cpsi. Double-wall cone insulation design was proposed for close-coupled converters to protect the conventional intumescent mat from high temperature. However, the double wall cone insulation is not applicable when the converter is directly mounted to the exhaust manifold without an inlet cone. The prototype manifold converter was tested under hot vibration test with a non-intumescent ceramic fiber mat and retainer rings as a supplemental support. The converter demonstrated durability for 10 hours under 80G acceleration and 100 hours under 60G acceleration with 1,050 °C catalyst bed temperature. The skin temperature of the heat shield was kept below 400 °C.

Back pressure of Diesel Particulate Filter (DPF) varies with accumulation of soot and/or ash. Soot can be cleaned in a high temperature oxidation (regeneration) process. But ash which is incombustible particulate matter derived from lubricant oil, engine wear, etc. cannot be cleaned from DPF without mechanical ash removal process and influences the back pressure perpetually. Design and control of DPF involving variation of the back pressure with ash accumulation will provide further improvement of fuel consumption and reliable operation in extended vehicle life time. Nevertheless, empirical investigations concerning ash accumulation are few because of the long testing time due to the slow accumulation rate, i.e. 0.5 - 2mg/mile [19]. In this investigation, four different designs of Cordierite (Cd) DPF were subjected to an accelerated ash accumulation test which is utilizing artificial ash powder.

This paper reports on the desired performances for Catalyzed Soot Filters (Hereinafter referred as “CSF”), which is composed of a Diesel Particulate Filter (DPF) coated with an Oxidation Catalyst, its design factors and their influence on DPF performance, and on the lifetime prediction method to effectively design a DPF for durability. Performance means pressure drop, Particulate Matter (PM) regeneration limit, time for light-off, and canning strength. Design factors include cell structure, overall DPF size and material porosity. Knowing the relationships between performance and design factors assist the engineer in optimizing the selection of material, cell structure and size of the DPF.

With the push towards more stringent on-road US heavy duty diesel regulations (i.e. HD GHG Phase 2 and the proposed ARB 20 mg/bhp-hr NOx), emission system packaging has grown critical while improving fuel economy and NOx emissions. The ARB regulations are expected to be implemented post 2023 while regulation for EU off-road segment will begin from 2019. The regulation, called Stage V, will introduce particle number (PN) regulation requiring EU OEMs to introduce a diesel particulate filter (DPF) while customer demands will require the OEMs to maintain current emission system packaging. A viable market solution to meet these requirements, especially for EU Stage V being implemented first, is a DPF coated with a selective catalyst reduction (SCR) washcoat (i.e. SCRonDPF).

Since the implementation of Euro 6 in September 2014, diesel engines are facing another drastic reduction of NOx emission limits from 180 to only 80 mg/km during NEDC and real driving emissions (RDE) are going to be monitored until limit values are enforced from September 2017. Considering also long term CO2 targets of 95 g/km beyond 2020, diesel engines must become cleaner and more efficient. However, there is a tradeoff between NOx and CO2 and, naturally, engine developers choose lower CO2 because NOx can be reduced by additional devices such as EGR or a catalytic converter. Lower CO2 engine calibration, unfortunately, leads to lower exhaust gas temperatures, which delays the activation of the catalytic converter. In order to overcome both problems, higher NOx engine out emission and lower exhaust gas temperatures, new aftertreatment systems will incorporate close-coupled DeNOx systems.

Diesel engines are widely used to reduce CO2 emission due to its higher thermal efficiency over gasoline engines. Considering long term CO2 targets, as well as tighter gas emission, especially NOx, diesel engines must become cleaner and more efficient. However, there is a tradeoff between CO2 and NOx and, naturally, engine developers choose lower CO2 because NOx can be reduced by a catalytic converter, such as a SCR catalyst. Lower CO2 engine calibration, unfortunately, leads to lower exhaust gas temperatures, which delays the activation of the catalytic converter. In order to overcome both problems, higher engine out NOx emission and lower exhaust gas temperatures, close-coupled a diesel particulate filter (DPF) system with integration of SCR catalyst technology is preferred. For SCR catalyst activity, it is known that the catalyst loading amount has an influence on NOx performance, so a high SCR catalyst loading will be required.

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.

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.

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.