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Technical Paper

Unregulated Emissions Evaluation of Gasoline Combustion Systems (Lean Burn / Stoichiometric DISI and MPI), State of the Art Diesel Aftertreatment Technologies (DPF, urea-SCR and DOC), and Fuel Qualities Effects (EtOH, ETBE, Aromatics and FAME)

In order to clarify future automobile technologies and fuel qualities to improve air quality, second phase of Japan Clean Air Program (JCAPII) had been conducted from 2002 to 2007. Predicting improvement in air quality that might be attained by introducing new emission control technologies and determining fuel qualities required for the technologies is one of the main issues of this program. Unregulated material WG of JCAPII had studied unregulated emissions from gasoline and diesel engines. Eight gaseous hydrocarbons (HC), four Aldehydes and three polycyclic aromatic hydrocarbons (PAHs) were evaluated as unregulated emissions. Specifically, emissions of the following components were measured: 1,3-Butadiene, Benzene, Toluene, Xylene, Ethylbenzene, 1,3,5-Trimethyl-benzene, n-Hexane, Styrene as gaseous HCs, Formaldehyde, Acetaldehyde, Acrolein, Benzaldehyde as Aldehydes, and Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene as PAHs.
Technical Paper

Thermal Fatigue Life of Exhaust Manifolds Predicted by Simulation

A combined computational fluid dynamics (CFD) and finite element (FE) analysis approach has been developed to simulate in the early stages of design the temperature distribution and estimate the thermal fatigue life of an engine exhaust manifold. To simulate the temperature distribution under actual operating conditions, we considered the external and internal flow fields. Digital mock-ups of the vehicle and engine were used to define the geometry of the engine compartment. External-air-flow simulation using in-house CFD code was used to predict the flow fields in the engine compartment and the heat transfer coefficients between the air and the exhaust manifold wall at various vehicle speeds. Unsteady-gas-flow calculation using the STAR-CD thermal- fluids analysis code was to predict the heat transfer coefficients between the exhaust gas and the manifold wall under various operating conditions.
Technical Paper

The Development of a High Speed Steel Based Sintered Material for High Performance Exhaust Valve Seat Inserts

The demands on valve seat insert materials, in terms of providing greater wear-resistance at higher temperatures, enhanced machinability and using non-environmentally hazardous materials at a reasonably low cost have intensified in recent years. Due therefore to these strong demands in the market, research was made into the possibility of producing a new valve seat insert material. As a result a high speed steel based new improved material was developed, which satisfies the necessary required demands and the evaluation trials, using actual gasoline engine endurance tests, were found to be very successful.
Technical Paper

The Development of a Cobalt-Free Exhaust Valve Seat Insert

Generally, cobalt-contained sintered materials have mainly been applied for exhaust valve seat inserts (VSI). However, there is a trend to restrict the use of cobalt as well as lead environmental law, and cobalt is expensive. To solve these problems, a new exhaust VSI on the assumption of being cobalt and lead free, applicable for conventional engines, having good machinability, and with a reduced cost was developed. The new exhaust VSI is a material dispersed with two types of hard particles, Fe-Cr-C and Fe-Mo-Si, in the matrix of an Fe-3.5mass%Mo at the ratio of 15 mass % and 10 mass % respectively.
Technical Paper

Technologies for Reducing Cold-Start Emissions of V6 ULEVs

New technologies are needed to reduce cold-start emissions in order to meet the more stringent regulations that will go into effect in Europe (EC2000 or EC2005) and in California (ULEV), especially for larger engines such as 6- and 8-cylinder units. One new technology in this regard is the electrically heated catalyst (EHC). However, the use of EHCs alone is not sufficient to achieve the necessary reduction in emissions. This paper discusses techniques for effectively combining the elements of an EHC system, including the introduction of secondary air into the exhaust, improved control of the air/fuel ratio, and an electric power supply method for EHCs. It is shown that it is more effective to promote exothermic reactions in the exhaust manifold than at the EHC. A suitable method for this purpose is to introduce secondary air into the exhaust near the exhaust valves.
Technical Paper

Study of the Generation mechanism for Abnormal Exhaust Noise

Based on experimental analysis, the generation mechanism of abnormal exhaust noise which is characterized by an intermittent high frequency aetallic sound, is clarified by bench testing of a FWD vehicle. The noise is caused by large amplitude pressure waves (finite amplitude waves) in the exhaust pipe. They are amplified due to interference between reflected waves and subsequent waves from the engine, and are finally transformed into shock waves in the propagation process along the exhaust pipe, resulting in abnormal exhaust noise. By theoretical analysis of finite amplitude waves, the wave profile in the propagation process and the transition distance to the shock wave can be solved analytically where the assumptions of mass, momentum, and energy conservation are valid, until the moment of shock wave formation. The transition distance is a key parameter in analyzing the growth and existence of shock waves.
Technical Paper

Soot Regeneration Model for SiC-DPF System Design

The Diesel Particulate Filter (DPF) system has been developed as one of key technologies to comply with tight diesel PM emission regulations. For the DPF control system, it is necessary to maintain temperature inside the DPF below the allowable service temperature, especially during soot regeneration to prevent catalyst deterioration and cracks. Therefore, the evaluation of soot regeneration is one of the key development items for the DPF system. On the other hand, regeneration evaluation requires a lot of time and cost since many different regeneration conditions should be investigated in order to simulate actual driving. The simulation tool to predict soot regeneration behavior is a powerful tool to accelerate the development of DPF design and safe regeneration control strategies. This paper describes the soot regeneration model applied to fuel additive and catalyzed types, and shows good correlation with measured data.
Technical Paper

Small Engine - Concept Emission Vehicles

Three Japanese automobile manufacturers-Mitsubishi Motors Corp., Nissan Motor Co., Ltd., and Toyo Kogyo Co., Ltd.-have been making efforts over the past three years to design and develop effective thermal reactor-exhaust gas recirculation and catalytic converter systems suitable for small engines. The work is being done by members participating in the IIEC (Inter-Industry Emission Control) Program, and the exhaust emission levels of the concept vehicles developed by these companies have met the goal established by the IIEC Program at low mileage. Each system, however, has a characteristic relationship between exhaust emission level and loss of fuel economy. Much investigation is required, particularly with respect to durability, before any system that will fully satisfy all service requirements can be completed. This paper reports the progress of research and development of the individual concept vehicles.
Technical Paper

Radiation Noise Due to Longitudinal Vibration of the Exhaust Pipe

The front exhaust pipe and the heat-shield plate of the catalytic converter are excited by the engine vibration. Noise radiation occurs on their surface. Concerning vehicle exterior noise, noise radiated from the exhaust system is often one of major sources as well as engine and exhaust noise. This paper describes the longitudinal vibration model-as a beam-is applied to the high frequency vibration that causes the noise radiated from the exhaust system. It describes also some methods of reducing such noise radiation by isolating the vibration from the front exhaust pipe. These methods are: adding mass to the front pipe, changing the material of the front pipe to a smaller Young's modulus one, installing flexible pipe composed by two sections, and so on.
Technical Paper

Numerical Analysis of the Exhaust Gas Flow and Heat Transfer in a Close-Coupled Catalytic Converter System During Warm-Up

A new multidimensional calculation method has been developed to simulate the warm-up characteristics of close-coupled catalytic converter systems. First, a one-dimensional gas exchange simulation and a three-dimensional exhaust gas flow calculation are combined to simulate the pulsation gas flow caused by the gas exchange process. The gas flow calculation and a heat transfer calculation are then combined to simulate heat transfer in the exhaust manifold and the catalyst honeycomb under pulsation flow. The predicted warm-up characteristics of the systems examined agreed well with the experimental data. In this simulation, CPU time was reduced greatly through the use of new calculation methods. Finally, the warm-up process of close-coupled catalysts is analyzed in detail with this simulation method. The design requirements for improving warm-up characteristics have been made clear.
Technical Paper

New PM Valve Seat Insert Materials for High Performance Engines

Internal combustion engines experience severe valve train wear and the reduction of valve seat and seat insert wear has been a long-standing issue. In this work, worn valve seats and inserts were examined to obtain a fundamental understanding of the wear mechanisms and the results were applied in developing new valve seat insert materials. The new exhaust valve insert material for gasoline engines is a sintered alloy steel containing Co-base hard particles, with lead infiltrated only for inserts used in unleaded gasoline engines. The new intake valve insert material for gasoline engines is a high-Mo sintered steel, obtained through transient liquid phase sintering and with copper precipitated uniformly. This material can be used for both leaded and unleaded gasoline engines. Valve and valve seat insert wear has long been an issue of concern to engine designers and manufacturers.
Technical Paper

Nano Particle Emission Evaluation of State of the Art Diesel Aftertreatment Technologies (DPF, urea-SCR and DOC), Gasoline Combustion Systems (Lean Burn / Stoichiometric DISI and MPI) and Fuel Qualities Effects (EtOH, ETBE, FAME, Aromatics and Distillation)

Newly designed laboratory measurement system, which reproduces particle number size distributions of both nuclei and accumulation mode particles in exhaust emissions, was developed. It enables continuous measurement of nano particle emissions in the size range between 5 and 1000 nm. Evaluations of particle number size distributions were conducted for diesel vehicles with a variety of emission aftertreatment devices and for gasoline vehicles with different combustion systems. For diesel vehicles, Diesel Oxidation Catalyst (DOC), urea-Selective Catalytic Reduction (urea-SCR) system and catalyzed Diesel Particulate Filter (DPF) were evaluated. For gasoline vehicles, Lean-burn Direct Injection Spark Ignition (DISI), Stoichiometric DISI and Multi Point Injection (MPI) were evaluated. Japanese latest transient test cycles were used for the evaluation: JE05 mode driving cycle for heavy duty vehicles and JC08 mode driving cycle for light duty vehicles.
Technical Paper

Microfluidic Simulation of Diesel Exhaust Gas and Soot Oxidation in Diesel Particulate Filter

Particulate matter (PM) including soot in diesel exhaust gas is a serious atmospheric pollutant, and stricter exhaust emission standards are being set in many countries. As one of the key technologies, a diesel particulate filter (DPF) for PM trap in the after-treatment of the exhaust gas has been developed. Typically, the inlet size of filter monolith is about 2 mm, and the thickness of the filter wall is only 0.2 mm, where soot particles are removed. It is impossible to observe the small-scale phenomena inside the filter, experimentally. Then, in the present study, we conducted microfluidic simulation with soot oxidation. Here, a real cordierite filter was used in the simulation. The inner structure of the filter was scanned by a 3D X-ray CT Computed Tomography) technique. The advantage is that it is non-intrusive system, and it has a high spatial resolution in the micrometer.
Technical Paper

Investigations of Compatibility of ETBE Gasoline with Current Gasoline Vehicles

Clarifying the impact of ETBE 8% blended fuel on current Japanese gasoline vehicles, under the Japan Clean Air Program II (JCAPII) we conducted exhaust emission tests, evaporative emission tests, durability tests on the exhaust after-treatment system, cold starting tests, and material immersion tests. ETBE 17% blended fuel was also investigated as a reference. The regulated exhaust emissions (CO, HC, and NOx) didn't increase with any increase of ETBE content in the fuel. In durability tests, no noticeable increase of exhaust emission after 40,000km was observed. In evaporative emissions tests, HSL (Hot Soak Loss) and DBL (Diurnal Breathing Loss) didn't increase. In cold starting tests, duration of cranking using ETBE 8% fuel was similar to that of ETBE 0%. In the material immersion tests, no influence of ETBE on these material properties was observed.
Technical Paper

Impact of Oil-derived Sulfur and Phosphorus on Diesel NOx Storage Reduction Catalyst - JCAP II Oil WG Report

Emission regulations for diesel-powered vehicles have been gradually tightening. Installation of after-treatment devices such as diesel particulate filters (DPF), NOx storage reduction (NSR) catalysts, and so on is indispensable to satisfy rigorous limits of particulate matter (PM) and nitrogen oxides (NOx). Japan Clean Air Program II Oil Working Group (JCAPII Oil WG) has been investigating the effect of engine oil on advanced diesel after-treatment devices. First of all, we researched the impact of oil-derived ash on continuous regeneration-type diesel particulate filter (CR-DPF), and already reported that the less sulfated ash in oil gave rise to lower pressure drop across CR-DPF [1]. In this paper, impact of oil-derived sulfur and phosphorus on NSR catalyst was investigated using a 4L direct injection common-rail diesel engine with turbo-intercooler. This engine equipped with NSR catalyst meets the Japanese new short-term emission regulations.
Technical Paper

Impact of Oil-derived Ash on Continuous Regeneration-type Diesel Particulate Filter - JCAPII Oil WG Report

Impact of oil-derived ash on the pressure drop of continuous regeneration-type diesel particulate filter (CR-DPF) was investigated through 600hrs running test at maximum power point on a 6.9L diesel engine, which meets the Japanese long-term emission regulations enacted in 1998, using approximately 50ppm sulfur content fuel. Sulfated ash content of test oils were varied as 0.96, 1.31, and 1.70 mass%, respectively. During the running test, the exhaust pressure drop through CR-DPF was measured. And after the test, the ventilation resistance through CR-DPF was also evaluated before and after the baking process, which was applied to eliminate the effect of soot accumulated in CR-DPF. The results revealed that the less sulfated ash in oil gave rise to lower pressure drop across CR-DPF. According to microscope examination of the baked DPF, ash was mainly accumulated on the wall surface of CR-DPF, and that seemed to be related to the magnitude of pressure drop caused by ash.
Technical Paper

Impact Study of High Biodiesel Blends on Performance of Exhaust Aftertreatment Systems

Biodiesel Fuel (BDF) Research Work Group works on identifying technological issues on the use of high biodiesel blends (over 5 mass%) in conventional diesel vehicles under the Japan Auto-Oil Program started in 2007. The Work Group conducts an analytical study on the issues to develop measures to be taken by fuel products and vehicle manufacturers, and to produce new technological findings that could contribute to the study of its introduction in Japan, including establishment of a national fuel quality standard covering high biodiesel blends. For evaluation of the impacts of high biodiesel blends on performance of diesel particulate filter system, a wide variety of biodiesel blendstocks were prepared, ranging from some kinds of fatty acid methyl esters (FAME) to another type of BDF such as hydrotreated biodiesel (HBD). Evaluation was mainly conducted on blend levels of 20% and 50%, but also conducted on 10% blends and neat FAME in some tests.
Technical Paper

Impact Study of High Biodiesel Blends on Exhaust Emissions to Advanced Aftertreatment Systems

In Biodiesel Fuel Research Working Group(WG) of Japan Auto-Oil Program(JATOP), some impacts of high biodiesel blends have been investigated from the viewpoints of fuel properties, stability, emissions, exhaust aftertreatment systems, cold driveability, mixing in engine oils, durability/reliability and so on. In the impact on exhaust emissions, the impact of high biodiesel blends into diesel fuel on diesel emissions was evaluated. The wide variety of biodiesel blendstock, which included not only some kinds of fatty acid methyl esters(FAME) but also hydrofined biodiesel(HBD) and Fischer-Tropsch diesel fuel(FTD), were selected to evaluate. The main blend level evaluated was 5, 10 and 20% and the higher blend level over 20% was also evaluated in some tests. The main advanced technologies for exhaust aftertreatment systems were diesel particulate filter(DPF), Urea selective catalytic reduction (Urea-SCR) and the combination of DPF and NOx storage reduction catalyst(NSR).
Technical Paper

Fuel Enrichment Control System by Catalyst Temperature Estimation to Enable Frequent Stoichiometric Operation at High Engine Speed/Load Condition

Fuel economy can be improved by reducing engine displacement, thanks to the resulting smaller friction losses and pumping losses. However, smaller engines frequently operate at high-engine speed and high-load, when pressure on the accelerator increases during acceleration and at high speed. To protect exhaust system components from thermal stress, exhaust gas temperature is reduced by fuel enrichment. To improve fuel economy, it is important to increase the frequency of stoichiometric operation at high-engine speed and high-load. Usually, the start timing of fuel enrichment is based upon temperature requirements to protect the catalyst. In the high-engine speed and high-load zone, the threshold temperature of catalyst protection is attained after some time because of the heat mass. Therefore, stoichiometric operation can be maintained until the catalyst temperature reaches the threshold temperature.
Technical Paper

Exhaust Noise Abatement with Porous Sintered Metal Silencer

The exhaust system is often one of the main sources of vehicle noise. A new type of exhaust silencer made of porous sintered aluminum and installed at the end of the exhaust tube considerably reduces this noise, with no rise in back pressure. The mechanism of noise abatement is analyzed utilizing fluid dynamic analysis techniques. It is concluded that noise reduction results mainly from the fluid dynamic effects arising from the gas permeability of the material. Among these effects are the boundary layer control effect of the inner flow, flattening of the velocity profile, heat dispersion effect, decrease in turbulence of flow, smoothing of exhaust pulsation, contraction of the mixing region, and the resulting large decrease in the volume of the noise source. In regard to acoustical effect, the sintered metal can be thought of as Helmholtz resonators. The change in the end condition as an acoustic tube also reduces the peak level of acoustic resonance.