Search Results

Currently, in the typical internal combustion engine, approximately one third of fossil fuel combustion by-product is wasted heat. In the continued effort to improve fuel economy, one area that is being researched today is the harvesting of wasted energy to increase vehicle efficiency. This paper will address how heat emitted by exhaust systems can be captured and used to increase vehicle efficiency. Overall we will compare energy content in the exhaust manifold and exhaust underfloor mid-vehicle position, where potential exhaust heat exchanger concepts can reside. These heat exchanger concepts are designed primarily to capture heat from these locations and transfer the energy for increased passenger heating and comfort during cold conditions and/or supplement other improvements in power train efficiencies. An analysis of the energy exchange to the heated fluid is compared in the exhaust manifold and underfloor position respectively.

The localized fire test provided in the Global Technical Regulation for Hydrogen Fuel Cell Vehicles gives two separate test methods: the ‘generic installation test - Method 1′ and the ‘specific vehicle installation test - Method 2′. Vehicle manufacturers are required to apply either of the two methods. Focused on Method 2, the present study was conducted to determine the characteristics and validity of Method 2. Test results under identical burner flame temperature conditions and the effects of cylinder protection covers made of different materials were compared between Method 1 and Method 2.

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.

To reduce ultra fine particle number concentration from a heavy-duty diesel engine, the effects of diesel fuel property and after-treatment systems were studied. The reduction of ultra fine particle number concentration over steady state mode using an 8 liter turbocharged and after-cooled diesel engine was evaluated. PM size distribution was measured by a scanning mobility particle sizer (SMPS). The evaluation used a commercially available current diesel fuel (Sulfur Content: 0.0036 wt%), high sulfur diesel fuel (Sulfur Content: 0.046 wt%) and low sulfur diesel fuel (Sulfur Content: 0.007 wt%). The after-treatment systems were an oxidation catalyst, a wire-mesh type DPF (Diesel Particle Filter) and a wall-flow type catalyzed DPF. The results show that fine particle number concentration is reduced with a low sulfur fuel, an oxidation catalyst, a wire-mesh type DPF (Diesel Particulate Filter) and wall flow type catalyzed DPF, respectively.

To reduce NOx and Particulate Matter (PM) emissions from a heavy-duty diesel engine, the effects of urea selective catalytic reduction (SCR) systems were studied. Proto type urea SCR system was composed of NO oxidation catalyst, SCR catalyst and ammonia (NH3) reduction catalyst. The NOx reduction performance of urea SCR system was improved by a new zeolite type catalyst and mixer for urea distribution at the steady state operating conditions. NOx and PM reduction performance of the urea SCR system with DPF was evaluated over JE05 mode of Japan. The NOx reduction efficiency of the urea SCR catalyst system was 72% at JE05 mode. The PM reduction efficiency of the urea SCR catalyst system with DPF was 93% at JE05 mode. Several kinds of un-regulated matters were detected including NH3 and N2O leak from the exhaust gas. It is necessary to have further study for detailed measurements for un-regulated emissions from urea solution.

To reduce NOx emissions from a heavy-duty engine at low exhaust temperature conditions, the plasma-assisted SCR (Selective Catalytic Reduction) system was evaluated. The plasma-assisted SCR system is mainly composed of an ammonia gas supply system and a plasma reactor including a pellet type SCR catalyst. The preliminary test with simulated gases of diesel exhaust showed an improvement in the NOx reduction performance by means of the plasma-assisted SCR system, even below 150°C conditions. Furthermore, NOx reduction ratio was improved up to 77% at 110°C with increase in the catalyst volume. Also NOx emissions from a heavy-duty diesel engine over the transient test mode in Japan (JE05) were reduced by the plasma-assisted SCR system. However, unregulated emissions, e.g., aldehydes, were increased with the plasma environment. This paper reports the advantages and disadvantages of the plasma-assisted SCR system for a heavy-duty diesel engine.

A recently developed superposition approach for determining the insertion loss of a two-inlet muffler is reviewed. To validate the approach, calculated and measured insertion losses are compared for a small engine muffler with two inlets and one outlet. After which, the phasing between the two inputs is varied and the insertion loss is evaluated. Results show that the insertion loss is strongly affected by the phasing between sources at low frequencies while phasing between sources has a lesser impact at high frequencies. At the conclusion of the paper, the theory for applying the superposition approach to transmission loss is reviewed.

Urea SCR technology is the most promising technique to reduce NOx emissions from heavy duty diesel engines. 32.5wt% aqueous urea solution is widely used as ammonia storage species for the urea SCR process. The thermolysis and hydrolysis of urea produces reducing agent ammonia and reduces NOx emissions to nitrogen and water. However, the application of urea SCR technology has many challenges at low temperature conditions, such as deposits formation in the exhaust pipe, lack deNOx performance at low temperature and freezing below -12°C. For preventing deposits formation, aqueous urea solution is hardly injected into exhaust gas stream at temperature below 200°C. The aqueous urea solution used as reducing agent precursor is the main obstacle for achieving high deNOx performances at low temperature conditions. This paper presents a solid SCR technology for control NOx emissions from heavy duty diesel engines.

Test procedures for evaluating vehicle compatibility were investigated based on accident analysis and crash tests. This paper summarizes the research reported by Japan to the IHRA Compatibility Working Group. Passenger cars account for the largest share of injuries in head-on collisions in Japan and were identified as the first target for tackling vehicle compatibility in Japan. To ascertain situations in collisions between vehicles of different sizes, we conducted crash tests between minicars and large cars, and between small cars and large cars. The deformation and acceleration of the minicar and small car is greater than that of large car. ODB, Overload and MDB tests were performed as procedures for evaluating vehicle compatibility. In overload tests, methods to evaluate the strength of the passenger compartment were examined, and it is found that this test procedure is suitable for evaluating the strength of passenger compartments.

A 2-LEG NOx Storage-Reduction (NSR) catalyst system is one of potential after-treatment technology to meet stringent NOx and PM emissions standards as Post New Long Term (Japanese 2009 regulation) and US'10. Concerning NOx reduction using NSR catalyst, a secondary fuel injection is necessary to make fuel-rich exhaust condition during the NOx reduction, and causes its fuel penalty. Since fuel injected in the high-temperature (∼250 degrees Celsius) exhaust instantly reacts with oxygen in common diesel exhaust, the proportion of fuel consumption to reduce the NOx stored on NSR catalyst is relatively small. A 2-LEG NSR catalyst system has the decreasing exhaust flow mechanism during NOx reduction, and the potential to improve the NOx reduction and fuel penalty. Therefore, this paper studies the 2-LEG NSR catalyst system. The after-treatment system consists of NSR catalysts, a secondary fuel injection system, flow controlled valves and a Catalyzed Diesel Particulate Filter (CDPF).

This research was conducted to propose appropriate emergency exits for bus crews and passengers. We developed the improved emergency exit based on the results of current bus exit performance tests, and investigated its effect on evacuation readiness. Tests employing human subjects were conducted to measure the time required to evacuate using the improved emergency exit. The subjects' psychological responses during evacuation were also studied to identify any evacuation problems. We also carried out tests of group evacuation through windows in a current bus to obtain the relationship between the evacuation time, the number of evacuation subjects, and the number of windows. The results show that the improved emergency exit is effective in improving evacuation readiness. It is clear that there is a positive correlation between the evacuation time, the number of subjects, and the number of windows.

In the urea SCR system, urea solution is injected by injector installed in the front stage of the SCR catalyst, and NOx can be purified on the SCR catalyst by using NH3 generated by the chemical reaction of urea. NH3 is produced by thermolysis of urea and hydrolysis of isocyanic acid after evaporation of water in the urea solution. But, biuret and cyanuric acid which may cause deposit are sometimes generated by the chemical reactions without generating NH3. Spray behavior and chemical reaction of urea solution injected into the tail-pipe are complicated. The purpose of this study is to reveal the spray behavior and NH3 generation process in the tail-pipe, and to construct the model capable of predicting those accurately. In this report, the impingement spray behavior is clarified by scattered light method in high temperature flow field. Liquid film adhering to the wall and deposit generated after evaporation of water from the liquid film are photographed by the digital camera.

This work investigated the mechanism of oil dilution by post injection to remove accumulated particulate matter on the diesel particulate filter of diesel engines. We developed a model to simulate post injection spray under low ambient gas pressure conditions. The model can predict the quantity of fuel mass adhered on the cylinder wall. The adhered fuel enters oil sump through the piston ring and cause oil dilution. The fuel in diluted oil evaporates during normal engine operations. We focus on the mechanism of fuel evaporation from diluted oil. The effects of engine speed and oil temperature on the evaporation were investigated. The results showed that the fuel evaporation rate increases with increasing engine speed and oil temperature. Furthermore, we developed an empirical model to predict the fuel evaporation rate of diluted oil through regression analysis with measured data.

A variety of parameters influence the durability of a converter to pipe joint of an automotive exhaust system. Some of the parameters are design variables and some factors are related to manufacturing. The design parameters include the thickness of the components, diameter of the pipe, sleeve length of the cone etc. While the variables like the weld penetration and the fit-up of the joint are related to manufacturing. Traditional durability simulations utilizing computer aided engineering (CAE) methods are conducted using nominal values of the design and manufacturing variables. In reality scatter and randomness in parameters are present due to the tolerance in components and limitations of the manufacturing process. In this paper a CAE based stochastic approach to determine the life distribution for a converter joint of an automotive exhaust system is presented.

For the better understanding of nanoparticles observed on the rode side, adding to the emission test on the chassis dynamometer and engine dynamometer test, possible factors for formation of nanoparticles are investigated. As other possible factors, cold starting of transient test cycle, blow-by gas from heavy duty diesel engine without a positive crankcase ventilation, exhaust braking, and plume mixing of vehicle exhausts were investigated. Nuclei mode particles under the transient test cycles formed during fuel cut period, fuel enrichment period and idling period. Concentration of nuclei mode particles during the idling period are depends on exhaust temperature. The higher exhaust temperature courses the lower number concentration but variation range is within twice. Emission rate of nanoparticles from blow-by gas is one thousandth of tail pipe emissions rate and was found to be negligible.

In recent years the automotive industry has been using an increasing number of high powered engines with fewer cylinders, with the goal to reduce weight and fuel consumption and hence to achieve lower CO2 emissions. In the following paper, an overview about the currently existing methods and products within the exhaust development is given which follow automotive lightweight trend. Continuous innovations in new materials, structural design and manufacturing process as well as mastering the integration of the components and modules within the system with a thorough understanding and optimization of the system behavior is enabling the reduction of weight in exhaust system. Another possibility to reduce the weight is the use of additional components such as valves. In the following, a discussion about the different types of valves is presented.

Under the current emissions legislation, most of the diesel-powered vehicles have to use Diesel Particulate Filters (DPF) to remove soot particles from the exhaust gas and the accumulated soot particles have to be removed in regular intervals. To initialize the exhaust gas temperature for soot regeneration, diesel fuel is either injected into the combustion chamber in late engine cycle (e.g. post injection) or vaporized and then discharged into the exhaust gas via a dosing device (e.g. fuel vaporizer). Both approaches though require the exothermic catalyst to convert the fuel into thermal energy. For practical reasons, this paper is concentrated on describing how CFD could be used to model the fuel distribution in an aftertreatment system equipped with fuel vaporizer and the exothermic reactions in the catalysts.

An ongoing trend among automotive exhaust suppliers is the application of loudspeakers in their systems to tailor the exhaust sound to the customers’ needs. In addition to it, undesirable engine order noise can be cancelled by a closed loop control system. Due to the high sound pressure from the engine, the loudspeaker is often required to run at its power maximum. A higher input power eventually causes a nonlinear behavior, resulting in undesirable sound pressure level or harmonic distortion. Thus, the understanding of nonlinear behavior of loudspeakers and the recognition of dominant effects are required. This paper presents the main nonlinearities of loudspeakers and the comparison of theories on linear and non-linear loudspeaker models. For validation of the model, one loudspeaker enclosure and one typical exhaust system with a loudspeaker have been calculated.

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.

This document describes the advantages of using Mobility transfer function simulations during the development of exhaust systems. The automotive industry demands increasingly stringent levels of acceptable interior noise. The exhaust system is an important contributor to the total vehicle noise and vibration and thus is a target for noise reduction. The use of good vibration isolation systems makes it possible to decrease noise in the vehicle interior compartment. In other words, the vibratory motion in automotive structures results in tactile and acoustic responses. This occurs when the energy coming from the engine (source) is transferred by the Exhaust System (path) and then is transformed into Structural Borne Noise received by the Driver (receiver) through the hanging arrangement of the Exhaust System.