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2-Stroke CAI Combustion Operation in a GDI Engine with Poppet Valves

2012-06-18
In order to extend the CAI operation range in 4-stroke mode and maximize the benefit of low fuel consumption and emissions in CAI mode, 2-stroke CAI combustion is revived operating in a GDI engine with poppet valves, where the conventional crankcase scavenging is replaced by boosted scavenging. The CAI combustion is achieved through the inherence of the 2-Stroke operation, which is retaining residual gas. A set of flexible hydraulic valve train was installed on the engine to vary the residual gas fraction under the boosting condition. The effects of spark timing, intake pressure and short-circuiting on 2-stroke CAI combustion and its emissions are investigated and discussed in this paper. Results show the engine could be controlled to achieve CAI operation over a wide range of engine speed and load in the 2-stroke mode because of the flexibility of the electro-hydraulic valvetrain system. Presenter Yan Zhang, Brunel University
Technical Paper

2-Stroke CAI Combustion Operation in a GDI Engine with Poppet Valves

2012-04-16
2012-01-1118
In order to extend the CAI operation range in 4-stroke mode and maximize the benefit of low fuel consumption and emissions in CAI mode, 2-stroke CAI combustion is revived operating in a GDI engine with poppet valves, where the conventional crankcase scavenging is replaced by boosted scavenging. The CAI combustion is achieved through the inherence of the 2-Stroke operation, which is retaining residual gas. A set of flexible hydraulic valve train was installed on the engine to vary the residual gas fraction under the boosting condition. The effects of spark timing, intake pressure and short-circuiting on 2-stroke CAI combustion and its emissions are investigated and discussed in this paper. Results show the engine could be controlled to achieve CAI operation over a wide range of engine speed and load in the 2-stroke mode because of the flexibility of the electro-hydraulic valvetrain system.
Technical Paper

2-Stroke CAI Operation on a Poppet Valve DI Engine Fuelled with Gasoline and its Blends with Ethanol

2013-04-08
2013-01-1674
Controlled Auto Ignition (CAI), also known as Homogeneous Charge Compression Ignition (HCCI), is one of the most promising combustion technologies to reduce the fuel consumption and NOx emissions. Currently, CAI combustion is constrained at part load operation conditions because of misfire at low load and knocking combustion at high load, and the lack of effective means to control the combustion process. Extending its operating range including high load boundary towards full load and low load boundary towards idle in order to allow the CAI engine to meet the demand of whole vehicle driving cycles, has become one of the key issues facing the industrialisation of CAI/HCCI technology. Furthermore, this combustion mode should be compatible with different fuels, and can switch back to conventional spark ignition operation when necessary. In this paper, the CAI operation is demonstrated on a 2-stroke gasoline direct injection (GDI) engine equipped with a poppet valve train.
Technical Paper

4-Stroke Multi-Cylinder Gasoline Engine with Controlled Auto-Ignition (CAI) Combustion: a comparison between Naturally Aspirated and Turbocharged Operation

2008-10-07
2008-36-0305
Controlled Auto-Ignition (CAI) also known as Homogeneous Charge Compression Ignition (HCCI) is increasingly seen as a very effective way of lowering both fuel consumption and emissions. Hence, it is regarded as one of the best ways to meet stringent future emissions legislation. It has however, still many problems to overcome, such as limited operating range. This combustion concept was achieved in a production type, 4-cylinder gasoline engine, in two separated tests: naturally aspirated and turbocharged. Very few modifications to the original engine were needed. These consisted basically of a new set of camshafts for the naturally aspirated test and new camshafts plus turbocharger for the test with forced induction. After previous experiments with naturally aspirated CAI operation, it was decided to investigate the capability of turbocharging for extended CAI load and speed range.
Technical Paper

A Study of the Effects of 30% Biodiesel Fuel on Soot Loading and Regeneration of a Catalytic DPF

2007-07-23
2007-01-2023
Biofuels are a renewable energy source. When used as extenders for transportation fuels, biofuels contribute to the global reduction of Green House Gas and CO2 emissions from the transport sector and to security and independence of energy supply. On a “Well to Wheel” basis they are much more CO2 efficient than conventional fossil fuels. All vehicles currently in circulation in Europe are capable of using 5 % biodiesel. The introduction of higher percentages biodiesel needs new specific standards and vehicle tests validation. The development of vehicles compatible with 30% biodiesel blends in diesel fuel includes the validation of each part of both engine and fuel vehicle systems to guarantee normal operation for the entire life of the vehicle.
Technical Paper

A Validated Numerical Simulation of Diesel Injector Flow Using a VOF Method

2000-10-16
2000-01-2932
Progress in Diesel spray modelling highly depends on a better knowledge of the instantaneous injection velocity and of the hydraulic section at the exit of each injection hole. Additionally a better identification of the mechanisms which cause fragmentation is needed. This necessitates to begin with a precise computation of the two-phase flow which arises due to the presence of cavitation within the injectors. For that aim, a VOF type interface tracking method has been developed and improved (Segment Lagrangian VOF method) which allows to describe numerically the onset and development of cavitation within Diesel injectors. Furthermore, experiments have been performed for validation purpose, on transparent one-hole injectors for high pressure injection conditions. Two different entrance geometries (straight and rounded) and various upstream and downstream pressure levels have been considered.
Technical Paper

Advanced Onboard Fuel Processor for PEM Fuel Cell Vehicles

2006-04-03
2006-01-0216
To reduce greenhouse gas emissions such as CO2, automakers are actively pursuing alternative propulsion systems. Improvements to current engine technology are being investigated along with new power plant technologies. Fuel Cell Vehicles offer an exciting option by producing electric power through a reaction that combines hydrogen and oxygen to make water. However, hydrogen storage onboard vehicles and construction of an expensive hydrogen distribution and fueling infrastructure remain as challenges today. In addition, greenhouse gas emissions from the production of hydrogen must be considered since most hydrogen is currently produced from non-renewable sources. While these issues are being worked on, Renault has chosen to pursue a fuel cell vehicle with a fuel processor that converts gasoline and other liquid fuels to hydrogen onboard the vehicle.
Technical Paper

Air Quality and Odors Evaluation for Passengers Compartment

1995-02-01
950016
The paper presents the VALEO and RENAULT approach to study odor problems for passengers compartment. The first part describes the method chosen to form a panel, and the second part presents a vehicle application.
Technical Paper

Air System Conception for a Downsized Two-Stroke Diesel Engine

2012-04-16
2012-01-0831
This paper introduces a research work on the air loop system for a downsized two-stroke two-cylinder diesel engine conducted in framework of the European project dealing with the POWERtrain for Future Light-duty vehicles - POWERFUL. The main objective was to determine requirements on the air management including the engine intake and exhaust system, boosting devices and the EGR system and to select the best possible technical solution. With respect to the power target of 45 kW and scavenging demands of the two-cylinder two-stroke engine with a displacement of 0.73 l, a two-stage boosting architecture was required. Further, to allow engine scavenging at any operation, supercharger had to be integrated in the air loop. Various air loop system layouts and concepts were assessed based on the 1-D steady state simulation at full and part load with respect to the fuel consumption.
Technical Paper

An Investigation into the Influence of LPG (Autogas) Composition on the Exhaust Emissions and Fuel Consumption of 3 Bi-Fuelled Renault Vehicles

1996-05-01
961170
Studies using a bi-fuelled (autogas/gasoline) Renault Laguna vehicle meeting °the 1996 European exhaust emission legislation has demonstrated that over the European test cycle at 25°C the LPG operated vehicle provides substantial benefits of reduced emissions compared to unleaded reference gasoline. At lower test temperatures (i.e. 5°C) even larger reduction in emissions have been observed. Lower CO (up to 95% at -5°C and 65% at 25°C), HC (90% at -5°C and 40% at 25°C) emissions and lower ozone HC reactivity have been observed and could all offer significant environmental air-quality benefits for LPG. Various autogas mixtures have been tested including 70/30, 30/70 and 49/30/21 (% mass propane / butane / propene). Results show that NOx emissions for this vehicle appear dependent on autogas composition. The two gas mixtures containing only 30% butane gave about 50% more NOx at +25°C than the 70% butane autogas mixture.
Technical Paper

Analysis of Gaseous and PM Emissions of 4-Stroke CAI/HCCI and SI Combustion in a DI Gasoline Engine

2013-04-08
2013-01-1549
Direct injection gasoline engines have the potential for improved fuel economy through principally the engine down-sizing, stratified charge combustion, and Controlled Auto Ignition (CAI). However, due to the limited time available for complete fuel evaporation and the mixing of fuel and air mixture, locally fuel rich mixture or even liquid fuel can be present during the combustion process of a direct injection gasoline engine. This can result in significant increase in UHC, CO and Particulate Matter (PM) emissions from direct injection gasoline engines which are of major concerns because of the environmental and health implications. In order to investigate and develop a more efficient DI gasoline engine, a camless single cylinder DI gasoline engine has been developed. Fully flexible electro-hydraulically controlled valve train was used to achieve spark ignition (SI) and Controlled Autoignition (CAI) combustion in both 4-stroke and 2-stroke cycles.
Technical Paper

Analysis of a Cost Effective Air Hybrid Concept

2009-04-20
2009-01-1111
The air hybrid engine absorbs the vehicle kinetic energy during braking, stores it in an air tank in the form of compressed air, and reuses it to propel a vehicle during cruising and acceleration. Capturing, storing and reusing this braking energy to give additional power can therefore improve fuel economy, particularly in cities and urban areas where the traffic conditions involve many stops and starts. In order to reuse the residual kinetic energy, the vehicle operation consists of 3 basic modes, i.e. Compression Mode (CM), Expander Mode (EM) and normal firing mode. Unlike previous works, a low cost air hybrid engine has been proposed and studied. The hybrid engine operation can be realised by means of production technologies, such as VVT and valve deactivation. In this work, systematic investigation has been carried out on the performance of the hybrid engine concept through detailed gas dynamic modelling using Ricardo WAVE software.
Technical Paper

Axial Flow Turbine Concept for Conventional and e-Turbocharging

2019-09-09
2019-24-0185
Engine downsizing has established itself as one of the most successful strategies to reduce fuel consumption and pollutant emissions in the automotive field. To this regard, a major role is played by turbocharging, which allows an increase in engine power density, so reducing engine size and weight. However, the need for turbocharging imposes some issues to be solved. In the attempt of mitigating turbo lag and poor low-end torque, many solutions have been presented in the open literature so far, such as: low inertia turbine wheels and variable geometry turbines; or even more complex concepts such as twin turbo and electrically assisted turbochargers. None of them appears as definitive, though. As a possible way of reducing turbine rotor inertia, and so the turbo lag, also the change of turbine layout has been investigated, and it revealed itself to be a viable option, leading to the use of mixed-flow turbines.
Technical Paper

CAI Combustion with Methanol and Ethanol in an Air-Assisted Direct Injection SI Engine

2008-06-23
2008-01-1673
CAI combustion has the potential to be the most clean combustion technology in internal combustion engines and is being intensively researched. Following the previous research on CAI combustion of gasoline fuel, systematic investigation is being carried out on the application of bio-fuels in CAI combustion. As part of an on-going research project, CAI combustion of methanol and ethanol was studied on a single-cylinder direct gasoline engine with an air-assisted injector. The CAI combustion was achieved by trapping part of burnt gas within the cylinder through using short-duration camshafts and early closure of the exhaust valves. During the experiment the engine speed was varied from 1200rpm to 2100rpm and the air/fuel ratio was altered from the stoichiometry to the misfire limit. Their combustion characteristics were obtained by analysing cylinder pressure trace.
Technical Paper

Comparison between the exhaust particles mass determined by the European regulatory gravimetric method and the mass estimated by ELPI

2005-05-11
2005-01-2147
Electrical Low Pressure Impactor (ELPI) is often employed to measure the particle number and size distribution of internal combustion engines exhaust gas. If appropriate values of particle density are available, the particle mass can be estimated by this method. Exhaust particles of three Euro3 passenger cars (one gasoline operating under stoichiometric conditions, one Diesel and one Diesel equipped with Diesel Particulate Filter) are measured using the current European regulations (gravimetric method on the are New European Driving Cycle) and estimated by ELPI particle number and size distribution. Different values for particle density are used to estimate the particle mass using all ELPI stages or only some of them. The results show that the particle mass estimated by ELPI is well correlated with the mass determined by filters for PM emissions higher than 0.025 g/km. This correlation is not very good at lower emissions.
Technical Paper

Comparison of Performance, Efficiency and Emissions between Gasoline and E85 in a Two-Stroke Poppet Valve Engine with Lean Boost CAI Operation

2015-04-14
2015-01-0827
Controlled Auto Ignition (CAI), also known as Homogeneous Charge Compression Ignition (HCCI), is one of the most promising combustion technologies to reduce the fuel consumption and NOx emissions. Most research on CAI/HCCI combustion operations have been carried out in 4-stroke gasoline engines, despite it was originally employed to improve the part-load combustion and emission in the two-stroke gasoline engine. However, conventional ported two-stroke engines suffer from durability and high emissions. In order to take advantage of the high power density of the two-stroke cycle operation and avoid the difficulties of the ported engine, systematic research and development works have been carried out on the two-stroke cycle operation in a 4-valves gasoline engine. CAI combustion was achieved over a large range of operating conditions when the relative air/fuel ratio (lambda) was kept at one as measured by an exhaust lambda sensor.
Journal Article

Computational Fluid Dynamics Calculations of Turbocharger's Bearing Losses

2010-05-05
2010-01-1537
Fuel consumption in internal combustion engines and their associated CO2 emissions have become one of the major issues facing car manufacturers everyday for various reasons: the Kyoto protocol, the upcoming European regulation concerning CO2 emissions requiring emissions of less than 130g CO2/km before 2012, and customer demand. One of the most efficient solutions to reduce fuel consumption is to downsize the engine and increase its specific power and torque by using turbochargers. The engine and the turbocharger have to be chosen carefully and be finely tuned. It is essential to understand and characterise the turbocharger's behaviour precisely and on its whole operating range, especially at low engine speeds. The characteristics at low speed are not provided by manufacturers of turbochargers because compressor maps cannot be achieve on usual test bench.
Technical Paper

Control of CAI Combustion Through Injection Timing in a GDI Engine With an Air- Assisted Injector

2005-04-11
2005-01-0134
Controlled auto Ignition (CAI) combustion has great potential for reducing both NOx emissions and fuel consumption in IC engines and the application of direct injection technology to the CAI engine adds another dimension of control to the combustion process. In this work an air-assisted injection system was applied to an engine that used residual gas to initiate and control CAI combustion. Injections were performed at Exhaust valve closure (EVC), intake valve opening (IVO) and BDC of the intake/compression stroke and the effects on combustion phasing (i.e. ignition timing and burn duration), engine output, fuel consumption and exhaust emissions analyzed. Injection at EVC gave the best results in terms of engine output, operating range and combustion stability. Injection at IVO generally resulted in the lowest fuel consumption. It was found that injection timing is an effective means of controlling combustion phasing.
Journal Article

Control-Oriented Modeling of a LNT-SCR Diesel After-Treatment Architecture

2011-04-12
2011-01-1307
Lean NOx trap (LNT) and Selective Catalytic Reduction catalysts (SCR) are two leading candidates for diesel NOx after-treatment. Each technology exhibits good properties to reduce efficiently diesel NOx emissions in order to match the forthcoming EURO 6 standards. NOx reduction in LNT is made through a two-step process. In normal (lean) mode, diesel engine exhausts NOx is stored into the NOx trap; then when necessary the engine runs rich during limited time to treat the stored NOx. This operating mode has the benefit of using onboard fuel as NOx reducer. But NOx trap solution is restrained by limited active temperature windows. On the other hand, NH₃-SCR catalysts operate in a wider range of temperature and do not contain precious metals. However, NH₃-SCR systems traditionally use urea-water solution as reducing agent, requiring thus additional infrastructure to supply the vehicles with enough reducer. These pros and cons are quite restrictive in classical LNT or NH₃-SCR architecture.
Technical Paper

Corporate Responsibility: Example of Local Environment Public-Private Partnership Project

2003-11-18
2003-01-3708
This paper presents the Clean Air Project for Rio de Janeiro jointly managed by Renault and the City of Rio de Janeiro. This project is one of the results of a regional initiative of the World Bank which aimed to develop local public-private actions in order to improve air quality in major metropolitan regions of Latin America. In that case, the partnership will result in the installation of a model, adapted to the local needs and the use of this model to test scenarios, quantifying the impact in terms of emissions. This partnership represents a new kind of long-lasting relationship between the private sector, aware of its social responsibility and local authorities which tend to foster the development of technical capacity to strengthen their role and awareness in that field and open new possibilities for environment investments. This paper presents this case study from the management and technical standpoint underlining the principal benefits of such a partnership.
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