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In order to reduce diesel NOx emissions, aftertreatment methods including LNT (Lean NOx Trap) and urea SCR (Selective Catalytic Reduction) have been researched. One of the shortcomings of urea SCR is its NOx reduction performance degradation at low exhaust gas temperatures and possible emission of unregulated byproducts. Here, a new type of a urea-dosing device to overcome these shortcomings is studied. This dosing device actively produces ammonia without depending upon the exhaust gas temperature, and designed for onboard application. The device incorporates an electrically heated bypass with a hydrolysis catalyst. An injector supplies urea solution into the bypass. The bypass is heated only when thermolysis is needed to produce ammonia (NH3). The hydrolysis catalyst further assists in the production of NH3. The ammonia gas obtained is then mixed with the main exhaust gas flow.

In the automotive sector, the time to market has become increasingly important. Consequently, powertrain systems require specific exhaust systems solutions to meet engine performance, pollutant emissions and acoustic targets delivered in a shorten time period. In this context, exhaust system suppliers need to constantly update their development process and according to project demands, tail-pipe noise has to be managed with advanced tools and methodologies. Flow generated noise has a broad band character and depending on the product design, some tonal frequencies could appear and produce a whistling noise. In order to anticipate and solve all these sound quality problems, an innovative computational aeroacoustic methodology has been developed and validated for a large range of exhaust system products.

Approximately 200,000 units of Hino J-series diesel engine were produced for 7 years. The J-series engines had a reputation all over the world for their performance, reliability, lightweight, and installation ability. They are composed of 4, 6 cylinders engines and unique 5-cylinder engine J07C. In 2002, newly modified J-series engines, which met the Japan 2001 noise emission regulations, were developed and J07C-TI, 5-cylinder TI engine, equipped with a common-rail fuel injection system was added in the J-series. Common-rail fuel injection system was equipped in order to achieve the emission targets in the future as well as to meet the current emission regulations. Achieving higher injection pressure level through the all engine speed, include excess low speed, was effective in reduction of PM emissions and in increasing of low engine speed torque drastically.

Diesel Particulate Filter (DPF) is a very effective aftertreatment device to limit particulate emissions from diesel engines. As the amount of soot collected in the DPF increases, the pressure loss increases. Therefore, DPF regeneration needs to be performed. Injected fuel into the exhaust line upstream of the Diesel Oxidation Catalyst (DOC), hydrocarbons are oxidized on the DOC, which increases the exhaust gas temperature at the DPF inlet. It is also necessary that the injected fuel is completely vaporized before entering the DOC, and uniformly mixed with the exhaust gases in order to make the DOC work efficiency. However, ensuring complete evaporation and an optimum mixture distribution in the exhaust line are challenging. Therefore, it is important that the fuel spray feature is grasped to perform DPF regeneration effectively. The purpose of this study is the constructing a simulation model.

Meeting backpressure and flow uniformity requirements within severe packaging constraints presents a particular challenge in the layout of catalyst inlet cones. In these cases, a parameterized optimization of the potentially complex cone geometries is inefficient (and inappropriate). Even assuming that a parameterization of the complex surface forms is possible, the choice of parametric shapes invariably affects the achievable results. Additionally, the long computation time for solving the flow fields limits the number of shape parameters that can be considered. To overcome these restrictions, an optimization tool has been developed at EMCON Technologies that is based on the continuous adjoint method (augmented Lagrange method) of Othmer et al. The open source CFD toolbox OpenFOAM® is used as the platform for the implementation.

Urea selective catalyst reduction (SCR) systems have a high NOx conversion rate because the ammonia formed by the hydrolyzing urea solution reacts with NOx efficiently as a reducing agent. Systems combining urea-SCR and a diesel particulate filter (DPF) have been adopted in heavy duty vehicles to meet the post new long term emissions regulations in Japan. This study examined the emissions reduction performance of these systems after 160,000 km. The emissions that were examined included both regulated emissions (NOx, PM, HC, and CO) and unregulated emissions. As a result, the cleanness of diesel emissions from a urea-SCR and DPF system was confirmed.

Stringent emissions standards (Euro 6 and Tier2Bin5) lead to the use of nitrogen oxides (NOx) aftertreatment. One of the most widespread technical solutions able to meet these legislations is Urea Selective Catalytic Reduction (Urea SCR). A urea aqueous solution is introduced into the exhaust system in order to reduce NOx over SCR catalyst. Before reaching the catalyst, the aqueous solution has to be transformed into ammonia. Current serial applications need long distances (≻ 400 mm) from injection point to SCR catalyst and a mixer apparatus to ensure sufficient mixing between exhaust gas and ammonia. Because of this distance, SCR catalyst is located far from the engine. The light-off of the catalyst is penalized and therefore the efficiency of the SCR system is low. The purpose of this paper is to show a compact mixing device able to ensure mixing in a short distance (~ 75 mm).

DPR is a particulate-emissions reduction system that has been developed to reduce particulate emissions in production commercial vehicles and consists of a multiple fuel-injection system, an engine electronic control unit, and a DPR-Cleaner which includes an oxidation catalyst, a catalyzed particulate filter, and silencers. DPR performs active regeneration to accelerate the regeneration of the filter under engine operating conditions where regeneration by passive regeneration alone is not sufficient. Thus, DPR makes it possible to regenerate the filter regardless of the exhaust gas temperature and enables significant reduction of particulate in commercial vehicles to levels below 0.027 g/kWh under Japan's D13 mode operating conditions. The authors describe development results of the DPR.

Diesel Particulate active Reduction system (DPR) is a system that traps particulate matter in diesel exhaust gas with a particulate filter and actively regenerates the filter when PM accumulates to a specific level. In 2003, DPR was installed on Hino's light-, medium-, and heavy-duty diesel engines, and about 50,000 units of these DPR-equipped diesel engines are currently on the market. This paper reports results of further progress made on optimization of the active regeneration function of DPR. The goal of successful development of DPR is to optimally control the system under various engine-operating conditions to regenerate the filter without producing abnormal combustion of PM and to minimize the amount of unburned PM to keep the filter from clogging. To improve the control of DPR, the combustion phenomena of PM collecting on the filter were studied through visualization, and the factors influencing combustion were determined.

Prior research on assessing multiple inlet and outlet mufflers is limited, and only recently have researchers begun to consider suitable metrics for multiple inlet and outlet mufflers. In this paper, transmission loss and insertion loss are defined for multiple inlet and outlet mufflers using a superposition method that can be extended to any m-inlet n-outlet muffler. Transmission loss is determined assuming that the sources and terminations are anechoic. On the other hand, insertion loss considers reflections. For both metrics, the amplitude and phase relationship between the sources should be known a priori. This paper explains both metrics, and measurement of transmission and insertion loss are demonstrated for a 2-inlet 2-outlet muffler with good agreement.

Diesel particulate trap systems are one of the effective means for the control of particulate emission from diesel vehicles. Hino has been researching and developing various diesel particulate trap systems for city buses. This paper describes two of the systems. One uses a wall flow filter equipped with an electric heater and a sensing device for particulate loading for the purpose of filter regeneration. Another makes use of a special filter named “Cross Flow Filter” with an epoch-making regeneration method called “Reverse Jet Cleaning”, by which it becomes possible to separate the part for particulate burning from the filter. Both systems roughly have come to satisfy the functions of trap systems for city buses, but their durability and reliability for city buses are not yet sufficient.

Environmental protection is now one of the most important social concerns in the world. In 1998, emission controls in the US required the reduction of NOx by 20% from the 1994 limit. Hino Motors has developed new J-series medium-duty diesel engines for trucks that meet the US 1998 emissions regulations. The engines comprise turbocharged and aftercooled 4- and 6-cylinder engines of the same cylinder bore and stroke. The engines feature a 4-valve system, OHC valve train design, centered nozzle arrangement, and an optimum combustion chamber design, which achieved uniform combustion. With these features, the maximum combustion temperature was decreased, and hence reduced the NOx, smoke, and PM emissions. A muffler integrated with a catalytic converter (catalytic muffler) was adopted to reduce PM emissions further. The engines with the catalytic muffler have successfully met the US 1998 emissions regulations.

The new Diesel Particulate active Reduction (DPR) system was developed for a medium-duty commercial vehicle as a deNOx catalyst combined with the conventional DPR system to achieve the Japan Post New-Long-Term (JPNLT) emissions regulations. It consists of a catalyst converter named as the new DPR cleaner, a fuel dosing injector, NOx sensors, temperatures and pressure sensors. The new DPR cleaner was constructed from a Front Diesel Oxidation Catalyst (F-DOC), a catalyzed particulate Filter (Filter), and a Rear Diesel Oxidation Catalyst (R-DOC). A newly developed Hydrocarbon Selective Catalyst Reduction (HC-SCR) catalyst was employed for each catalyst aiming to reduce NOx emissions with diesel fuel supplied from the fuel dosing injector. While the total volume of the catalyst was increased, the compact and easy-to-install catalyst converter was realized through the optimization of the flow vector and flow distribution in it by means of Computational Fluid Dynamics (CFD) analysis.

The objective of this study was to develop a test method for heavy-duty HEVs using a hardware-in-the-loop simulator (HILS) to enhance the type-approval-test method. To achieve our objective, HILS systems for series and parallel HEVs were actually constructed to verify calculation accuracy. Comparison of calculated and measured data (vehicle speed, motor/generator power, rechargeable energy storage system power/voltage/current/state of charge, and fuel economy) revealed them to be in good agreement. Calculation error for fuel economy was less than 2%.

This paper describes the development of an exhaust Thermal Enhancer™ using an airless nozzle fuel system. The purpose of the Thermal Enhancer™ is to increase diesel engine exhaust gas temperatures to a level where catalytic heating can be used for Diesel Particulate Filter regeneration. The system can also be used to achieve adequate temperatures for NOx reduction, employing techniques such as Selective Catalytic Reduction. The Thermal Enhancer™ is used to increase exhaust gas temperatures at conditions that would otherwise be too cold for effective catalyst operation. These conditions include idle and low-load operation. The airless-nozzle fuel system is necessary for engines that do not have a compressed-air system. Performance data, including hydrocarbon slip as a function of Thermal Enhancer™ outlet temperature are presented at steady state conditions. Pressure loss as a function of engine speed indicates it is less than 1 kPa at the maximum exhaust flow rate.

EPA 2010 emissions regulations - currently the strictest standards in the world - place particular emphasis on exhaust gas thermal control technology. The Burner System, a device developed to control exhaust gas temperatures, is the most effective means of raising exhaust gas temperature, as this system can function under any engine conditions, including low engine speed and torque. The Burner System begins operating immediately when the engine is started, activating the Diesel Exhaust Fluid (DEF) - Selective Catalytic Reduction (SCR) System immediately, because the Burner System is active, it enables the diesel particulate filter active regeneration under any engine operating conditions as well. This technical paper reports Burner System (ActiveClean™ Thermal Regenerator) development results.

This study employed a diesel particulate generator (DPG), with an installed engine oil injector for soot and ash accumulation in a diesel particulate filter (DPF). Ash was generated by engine oil injection into the diesel burner flame. The amount of soot accumulation per loading varied from 0.5 g/L to 8 g/L while ash accumulation amount per loading was maintained at 0.5 g/L. Initially, ash accumulation distribution in the DPF was visualized using X-ray computed tomography (CT). It was revealed that the form of ash accumulation changed depending on the amount of soot accumulation before active regeneration, i.e., a large amount of soot accumulation resulted in plug ash, whereas a small amount of soot accumulation resulted in wall ash. To clarify ash accumulation mechanisms, soot and ash transport behavior in DPF during active regeneration process was directly observed using a high-speed camera through an optically accessible D-shaped cut DPF covered with a quartz glass plate.

1 To meet the Japan Post New-Long-Term (Japan 2009) emissions regulation introduced in 2009, The Hydrocarbon Selective Catalytic Reduction (HC-SCR) system for the NOx emission with a diesel fuel was chosen among various deNOx after-treatment systems (the Urea-SCR, the NOx storage-Reduction Catalyst and so on). The HC-SCR was adopted, in addition to combustion modification of diesel engine (mainly cooled EGR) as the New DPR system. The New DPR system for medium and light duty vehicles was developed as a world's first technology by Hino Motors. Advantages of the New DPR are compact to easy-to-install catalyst converter and no urea solution (DEF) injection (regardless urea infrastructure) as compared the Urea-SCR system.

The purpose of this paper is to highlight the importance of material and design selection for future light weight exhaust systems. Material validation for new components usually requires various types of tests on different types of test coupons. There are varieties of corrosion test methods which are in practice since years now. Majority of these testing approaches are used to make relative ranking among different materials. In most of these tests a correlation between testing and field behavior is missing. There is also no test available in which both external as well as internal corrosion can be realized simultaneously. Additionally, none of these corrosion tests cover the design aspects of the components. To combat this challenge Faurecia has built and validated a corrosion test setup where complete exhaust silencer can be tested near to real conditions. A comparative study was performed between field parts and test parts to validate the test cycle.

Four urea SCR systems were developed and evaluated on a C/D and on the road to investigate their potential for Japanese emission regulations in 2005 and beyond. Test results showed that NOx conversion ratios were 50 to 70% during the Japanese D13 mode cycle, and the ratios under the transient driving cycle were lower than those tested during a steady state. Unregulated emissions, such as benzene, aldehyde and benzo[a]pyrene, existed either at a trace level using the oxidation catalyst, or lower than a base diesel engine, when no oxidation catalyst was used. The health effects of particulate matter emitted from the SCR system were almost the same as those from conventional diesel engines, as evaluated by the Ames test and in vitro micronucleus test. Thermal degradation products, such as cyanuric acid and melamine, were two to four figures lower compared with the toxicological information of Safety Information Resources Inc. (SIRI).