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Technical Paper

One-Dimensional Modeling of a Thermochemical Recuperation Scheme for Improving Spark-Ignition Range Extender Engine Efficiency

2019-09-09
2019-24-0066
Vehicle electrification has accelerated as global fuel efficiency standards have become more stringent and battery costs have decreased. Although full electrification, i.e.; battery electric vehicles, may be appropriate for some light-duty vehicle applications, many vehicles will still require an engine to overcome range limitations. Range extender (REx) engine generators can be used to charge vehicle batteries as needed to meet driver demands. One advantage of REx engines is that they do not have a direct mechanical connection to the wheels and can frequently within the most efficient speed and load ranges. Therefore, REx engines provide an opportunity to implement advanced engine technologies that are more difficult to apply in conventional engine-powered vehicles. Thermochemical recuperation (TCR) schemes use exhaust waste heat to catalytically convert a portion of the fuel into a gas that has increased heating value.
Technical Paper

Strive for Zero Emission Impact from Hybrid Vehicles

2019-09-09
2019-24-0146
Since several decades, passenger cars and light duty vehicles (LDV) reach full pollutant conversion during warm up conditions; the major challenge has been represented by the cold start and warming up strategies. The focus on technology developments of exhaust after treatment systems have been done in the thermal management in order to reach the warm up conditions as soon as possible. A new challenge is now represented by the Real Driving Emission Regulation as this bring more various, and not any longer cycle defined, Cold Start Conditions. On the other hand, once the full conversion has been reached, it would be beneficial for many EATS components if the exhaust gas temperature could be lowered. To take significant further emission steps, approaching e.g. zero emission concepts, we investigate to bring in electrical heating catalyst (EHC) and emission trap approaches. The clear goal is to have the right temperature in the right place at the right time.
Technical Paper

Experimental Assessment of Ozone Addition Potential in Direct Injection Compression Ignition Engines

2019-09-09
2019-24-0118
The potential of ozone addition in compression ignition engines is investigated experimentally in this paper. Experiments were carried out in an optically accessible single cylinder engine equipped with a common rail direct injection system. A commercially available ozone generator (P <100W) was used to add to the intake flow a controlled amount of ozone. EU Diesel fuel (CN 54) and a Naphtha fuel (CN 33) were tested investigating the impact of Ozone in conventional diesel combustion and LTC cases (e.g. high EGR rate). Minimal ozone concentration in the intake flow (10 ppm) demonstrated to reduce significantly the ignition delay. However, the impact observed strongly depends on the engine conditions tested and, in general, this effect observed becomes significant in conditions characterized by a long ignition delay: low intake temperature, high dilution, and low CN fuel.
Technical Paper

Development of a dedicated CNG three-way catalyst model in 1-D simulation platforms

2019-09-09
2019-24-0074
A growing interest in heavy-duty engines powered with CNG dictated by stringent regulations in terms of emissions, has made it essential to study a specific Three-Way Catalyst (TWC). Oxygen storage phenomena characterize catalytic converter efficiency under real world driving operating conditions and, consequently, during strong dynamics in Air-to-Fuel (A/F) ratio. A numerical “quasi-steady” model has been set-up to simulate the chemical process inside the reactor. A dedicated experimental campaign has been performed in order to evaluate the catalyst response to a defined lambda variation pattern of the engine exhaust stream, thus providing the data necessary for the numerical model validation. In fact, goal of the present research activity was to investigate the effect of very fast composition transitions of the engine exhaust typical of the mentioned driving conditions (including fuel cutoffs etc.) on the catalyst performance and on related emissions at the tailpipe.
Technical Paper

The Effect of Post Injection Coupled with Extremely High Injection Pressure on Combustion Process and Emission Formation in an Off-Road Diesel Engine: a Numerical and Experimental Investigation

2019-09-09
2019-24-0092
In this paper, a numerical and experimental assessment of post injection potential for soot emissions mitigation in an off-road diesel engine is presented, with the aim of supporting hardware selection and engine calibration processes. As a case study, a prototype off-road 3.4 liters 4-cylinder diesel engine developed by Kohler Engines was selected. In order to comply with Stage V emission standards without a dedicated aftertreatment for NOx, the engine was equipped with a low pressure cooled EGR, allowing high EGR rates (above 30%) even at high load. To enable the exploitation of such high EGR rates with acceptable soot penalties, a two stage turbocharger and an extremely high pressure fuel injection system (up to 3000 bar) were adopted. Moreover, post injections events were also exploited to further mitigate soot emissions with acceptable Brake Specific Fuel Consumption (BSFC) penalties.
Technical Paper

Pressure Drop of Particulate Filters and Correlation with the Deposited Soot for Heavy-Duty Engines

2019-09-09
2019-24-0151
Particulate filters are a widely used emission control device on heavy-duty diesel engines. The accumulation of particulate matter, mostly consisting of soot, inside the filter results in increased filter pressure-drop (backpressure). This increased backpressure has been used by the on-board control systems as trigger for regeneration procedures, which aim to actively oxidize the accumulated soot. However, it is known that passive soot oxidation during normal operation affects the correlation between backpressure and the deposited soot mass in filter. Therefore, the backpressure alone cannot be a reliable trigger for regeneration. In this work we highlight operating conditions with very poor correlation between backpressure and accumulated soot mass in filter and evaluate the possible root causes. Experiments with several heavy-duty diesel engines and particulate filters were conducted on engine test bench.
Technical Paper

Evaluation of Water and EGR Effects on Combustion Characteristics of GDI Engines Using a Chemical Kinetics Approach

2019-09-09
2019-24-0019
The modern spark ignition engines, due to the introduced strategies for limiting the consumption without reducing the power, are sensitive to both the detonation and the increase of the inlet turbine temperature. In order to reduce the risk of detonation, the use of dilution with the products of combustion (EGR) is an established practice that has recently was improved with the use of water vapour obtained via direct or indirect injection. The application and optimization of these strategies cannot ignore the knowledge of physical quantities characterizing the combustion such as the laminar flame speed and the ignition delay, both are an intrinsic property of the fuel and are function of the mixture composition (mixture fraction and dilution) and of its thermodynamic conditions. The experimental measurements of the laminar flame speed and the ignition delay available in literature, rarely report the effects of dilution by EGR or water vapor.
Technical Paper

Development of Three Way Catalyst (TWC) ageing model: application of real driving emission condidion

2019-09-09
2019-24-0047
Further reduction of vehicles pollutant and CO2 emissions is required to prevent global warming and to improve air quality. The exhaust system is designed to ensure low emission during all life of the vehicle. As catalyst ageing is affecting the catalyst performance, such impact needs to be consider upfront during the design of the fresh catalyst. Until now, exhaust system design are evaluated based on real tests for each vehicle, using exhaust lines aged on engine test benches or burner benches. This induces major investigation limitations such as: late evaluation in development cycle, high testing and prototyping cost. Usage of Model Based Development approach can be a powerful way to improve this process by allowing system evaluation under several ageing conditions at early development stage. The present study focuses on modelling of Three Way Catalyst (TWC) ageing to predict the mileage impact on tailpipe emissions.
Technical Paper

A New Take on Porous Medium Approach for Modelling Monoliths and Other Multiple Channel Devices

2019-09-09
2019-24-0049
Porous medium approach is widely used in modelling high resistance devices such as heat exchangers, automotive catalysts or filters, where details of flow distribution inside the channels are not important. This reduces the computational time considerably, as the whole length of the monolith does not need to be modelled, and the thin boundary layers in each channel do not need to be resolved. The drawback of the approach is compromised accuracy of the flow predictions downstream of the monolith, because the mixing of the individual jets coming out of the monolith channels is not accounted for. Very few studies exist where this issue has been addressed. The methods include artificial turbulence generation, inferring turbulence information from upstream, or using hybrid modelling approach to separate the flow into channels.
Technical Paper

Learning based MPC control of combustion timing in Multi-Cylinder Partially Premixed Combustion Engine

2019-09-09
2019-24-0016
Partially Premixed Combustion has shown to be a promising advanced combustion mode for future engines in terms of efficiency and emission levels. The combustion timing should be suitably phased to realize high efficiency. However, a simple map-based feed-forward control method is not sufficient for controlling the combustion during transient operation. This article proposes one learning-based model predictive control (MPC) approach to achieve controllability and feasibility. Since PPC engines could have unacceptably high pressure-rise rates at different operation points, triple injection is applied as a solvent, with the use of two pilot fuel injection. The controller utilizes the main injection timing to manage the combustion timing, and the first and second injection timing is considered as a function of the engine load and speed. The cylinder pressure is used as the combustion feedback.
Technical Paper

Analysis and Modeling of NOx Reduction Based on the Reactivity of Cu Active Sites and Brønsted Acid Sites in a Cu-Chabazite SCR Catalyst

2019-09-09
2019-24-0150
In this study, the NOx purification reactivity of a Cu-chabazite SCR catalyst was analyzed over a wide temperature range based on the NH3-SCR mechanism considering Cu redox reactions and reactions on a Brønsted acid site. It was revealed that the De-NOx reactions on the active site of Cu proceeded in different paths at lower and higher temperatures. This means that the rate-limiting step of SCR reactions was changed as each temperature. The reaction rate of NOx purification on a Cu site less than 200 °C was determined by the reaction rate of oxidation of Cu sites. On the other hand, the NH3 adsorption on Cu sites played a dominant role in NOx purification at temperature range higher than 300°C. Moreover, it was also observed that the Cu reaction site took different states at low and high temperatures during the NOx purification and was estimated that the valence state of a Cu site was changed as the temperature increased.
Technical Paper

A Review of Spark-Assisted Compression Ignition (SACI) Research in the Context of Realizing a Production SACI Strategy

2019-09-09
2019-24-0027
Low temperature combustion (LTC) strategies have been a keen interest in the automotive industry for over four decades since they offer improved fuel efficiency compared to conventional spark-ignition (SI) engines. LTC strategies use high dilution to keep combustion temperatures below about 2000 K to reduce heat transfer losses while avoiding locally rich in-cylinder regions that produce high soot. High dilution also enables an efficiency improvement from reduced pumping work and improved thermodynamic properties, though it requires high ignition energy. Combustion can be achieved by triggering autoignition from compression energy. High compression ratios are typically required to produce this level of ignition energy, which further improves fuel efficiency. The timing of the autoignition event is influenced by fuel properties and mixture composition, and is exponentially sensitive to temperature.
Standard

Engine Oil Performance and Engine Service Classification (Other than "Energy Conserving")

2019-07-16
WIP
J183
This SAE Standard outlines the engine oil performance categories and classifications developed through the efforts of the Alliance of Automobile Manufacturers (Alliance), American Petroleum Institute (API), the American Society for Testing and Materials (ASTM), the Engine Manufacturers Association (EMA), International Lubricant Specification Advisory Committee (ILSAC), and SAE. The verbal descriptions by API and ASTM, along with prescribed test methods and limits are shown for active categories in Table 1 and obsolete categories in Table A1. Appendix A is a historical documentation of the obsolete categories. For purposes of this document, active categories are defined as those (a) for which the required test equipment and test support materials, including reference engine oils and reference fuels, are readily available, (b) for which ASTM or the test developer monitors precision for all tests, and (c) which are currently available for licensing by API EOLCS.
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