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Technical Paper

Effects of Mechanical Turbo Compounding on a Turbocharged Diesel Engine

2013-03-25
2013-01-0103
This paper presents the simulation study on the effects of mechanical turbo-compounding on a turbocharged diesel engine. A downstream power-turbine has been coupled to the exhaust manifold after the main turbocharger, in the aim to recover waste heat energy. The engine in the current study is Scania DC13-06, which 6 cylinders and 13 litre in capacity. The possibilities, effectiveness and working range of the turbo compounded system were analyzed in this study. The system was modeled in AVL BOOST, which is a one dimensional (1D) engine code. The current study found that turbo compounding could possibly recover on average 11.4% more exhaust energy or extra 3.7kW of power. If the system is mechanically coupled to the engine, it could increase the average engine power by up to 1.2% and improve average BSFC by 1.9%.
Technical Paper

Experimental Comparison between Stratified Flame Ignition and Micro Flame Ignition in a Gasoline SI-CAI Hybrid Combustion Engine

2017-03-28
2017-01-0737
Controlled Auto-Ignition (CAI), also known as Homogeneous charge compression ignition (HCCI), has been the subject of extensive research because of their ability to providing simultaneous reduction in fuel consumption and NOx emissions in a gasoline engine. However, due to its limited operation range, combustion mode switching between CAI and spark ignition (SI) combustion is essential to cover the overall operational range of a gasoline engine for passenger car applications. Previous research has shown that the SI-CAI hybrid combustion has the potential to control the ignition timing and heat release process during both steady state and transient operations. However, it was found that the SI-CAI hybrid combustion process is often characterized with large cycle-to-cycle variations, due to the flame instability at high dilution conditions.
Technical Paper

Influence of Biodiesel Blending on Particulate Matter (PM) Oxidation Characteristics

2017-03-28
2017-01-0932
The use of diesel particulate filter [DPF] has become a standard in modern diesel engine after treatment technology. However pressure drop develops across the filter as PM accumulates and this requires quick periodic burn-out without incurring thermal runaway temperatures that could compromise DPF integrity during operation. Adequate understanding of soot oxidation is needed for design and manufacture of efficient filter traps for the engine system. In this study, we have examined the impact of blending biodiesel on oxidation of PM generated from a high speed direct injection [HSDI] diesel engine, which was operated with 20% [B20] and 40% [B40] blends of two biodiesel fuels. The PM samples were collected from the engine exhaust using a Pall Tissuquartz filter, the oxidation characteristics of the samples were carried out using thermogravimetric analyzer [TGA]. The biodiesel oxidation data obtained from pure petrodiesel was compared against the fuel blends.
Technical Paper

Experimental Investigation of Combustion and Emission Characteristics of Stoichiometric Stratified Flame Ignited (SFI) Hybrid Combustion in a 4-Stroke PFI/DI Gasoline Engine

2019-04-02
2019-01-0960
Controlled Auto-Ignition (CAI), also known as Homogeneous Charge Compression Ignition (HCCI), can improve the fuel economy of gasoline engines and simultaneously achieve ultra-low NOx emissions. However, the difficulty in combustion phasing control and violent combustion at high loads limit the commercial application of CAI combustion. To overcome these problems, stratified mixture, which is rich around the central spark plug and lean around the cylinder wall, is formed through port fuel injection and direct injection of gasoline. In this condition, rich mixture is consumed by flame propagation after spark ignition, while the unburned lean mixture auto-ignites due to the increased in-cylinder temperature during flame propagation, i.e., stratified flame ignited (SFI) hybrid combustion.
Technical Paper

The Application of Controlled Auto-Ignition Gasoline Engines -The Challenges and Solutions

2019-04-02
2019-01-0949
Controlled Auto-Ignition (CAI) combustion, also known as Homogeneous Charge Compression Ignition (HCCI), has the potential to simultaneously reduce the fuel consumption and nitrogen oxides emissions of gasoline engines. However, narrow operating region in loads and speeds is one of the challenges for the commercial application of CAI combustion to gasoline engines. Therefore, the extension of loads and speeds is an important prerequisite for the commercial application of CAI combustion. The effect of intake charge boosting, charge stratification and spark-assisted ignition on the operating range in CAI mode was reviewed. Stratified flame ignited (SFI) hybrid combustion is one form to achieve CAI combustion under the conditions of highly diluted mixture caused by the flame in the stratified mixture with the help of spark plug.
Technical Paper

Parametric Study on CAI Combustion in a GDI Engine with an Air-Assisted Injector

2007-04-16
2007-01-0196
Controlled auto-ignition (CAI) combustion and engine performance and emission characteristics have been intensively investigated in a single-cylinder gasoline direct injection (GDI) engine with an air-assisted injector. The CAI combustion was obtained by residual gas trapping. This was achieved by using low-lift short-duration cams and early closing the exhaust valves. Effects of EVC (exhaust valve closure) and IVO (intake valve opening) timings, spark timing, injection timing, coolant temperature, compression ratio, valve lift and duration, on CAI combustion and emissions were investigated experimentally. The results show that the EVC timing, injection timing, compression ratio, valve lift and duration had significant influences on CAI combustion and emissions. Early EVC and injection timing, higher compression ratio and higher valve lift could enhance CAI combustion. IVO timing had minor effect on CAI combustion.
Technical Paper

Effect of Injection Timing on Mixture and CAI Combustion in a GDI Engine with an Air-Assisted Injector

2006-04-03
2006-01-0206
The application of controlled auto-ignition (CAI) combustion in gasoline direct injection (GDI) engines is becoming of more interest due to its great potential of reducing both NOx emissions and fuel consumption. Injection timing has been known as an important parameter to control CAI combustion process. In this paper, the effect of injection timing on mixture and CAI combustion is investigated in a single-cylinder GDI engine with an air-assisted injector. The liquid and vapour phases of fuel spray were measured using planar laser induced exciplex fluorescence (PLIEF) technique. The result shows that early injection led to homogeneous mixture but late injection resulted in serious stratification at the end of compression. CAI combustion in this study was realized by using short-duration camshafts and early closure of the exhaust valves. During tests, the engine speed was varied from 1200rpm to 2400rpm and A/F ratio from stoichiometric to lean limit.
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

Experimental Investigation of the Effects of Combined Hydrogen and Diesel Combustion on the Emissions of a HSDI Diesel Engine

2008-06-23
2008-01-1787
The effects of load, speed, exhaust gas recirculation (EGR) level and hydrogen addition level on the emissions from a diesel engine have been investigated. The experiments were performed on a 2.0 litre, 4 cylinder, direct injection engine with a high pressure common-rail injection system. Injection timing was varied between 14° BTDC and TDC and injection pressures were varied from 800 bar to 1400 bar to find a suitable base point. EGR levels were then varied from 0% to 40%. Hydrogen induction was varied between 0 and 6% vol. of the inlet charge. In the case of using hydrogen and EGR, the hydrogen replaced air. The load was varied from 0 to 5.4 bar BMEP at two engine speeds, 1500 rpm and 2500 rpm. For this investigation the carbon monoxide (CO), total unburnt hydrocarbons (THC), nitrogen oxides (NOx) and the filter smoke number (FSN) were all measured.
Technical Paper

The Effects on Diesel Combustion and Emissions of Reducing Inlet Charge Mass Due to Thermal Throttling with Hot EGR

1998-02-23
980185
This paper is a complementary to previous investigations by the authors (1,2,3,4) on the different effects of EGR on combustion and emissions in DI diesel engine. In addition to the several effects that cold EGR has on combustion and emissions the application of hot EGR results in increasing the inlet charge temperature, thereby, for naturally aspirated engines, lowering the inlet charge mass due to thermal throttling. An associated consequence of thermal throttling is the reduction in the amount of oxygen in the inlet charge. Uncooled EGR, therefore, affects combustion and emissions in two ways: through the reduction in the inlet charge mass and through the increase in inlet charge temperature. The effect on combustion and emissions of increasing the inlet charge temperature (without reducing the inlet charge mass) has been dealt with in ref. (1).
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

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

Developing a Fuel Stratification Concept on a Spark Ignition Engines

2007-04-16
2007-01-0476
A fuel stratification concept has been developed in a three-valve twin-spark spark ignition engine. This concept requires that two fuels or fuel components of different octane numbers (ON) be introduced into the cylinder separately through two independent inlet ports. They are then stratified into two regions laterally by a strong tumbling flow and ignited by the spark plug located in each region. This engine can operate in the traditional stratified lean-burn mode at part loads to obtain a good part-load fuel economy as long as one fuel is supplied. At high loads, an improved fuel economy might also be obtained by igniting the low ON fuel first and leaving the high ON fuel in the end gas region to resist knock. This paper gives a detailed description of developing the fuel stratification concept, including optimization of in-cylinder flow, mixture and combustion.
Technical Paper

Experimental Studies of a 4-Stroke Multi-Cylinder Gasoline Engine with Controlled Auto-Ignition (CAI) Combustion

2007-11-28
2007-01-2609
Controlled Auto-Ignition (CAI), also known as HCCI (Homogeneous Charge Compression Ignition), is increasingly seen as a very effective way of lowering both fuel consumption and emissions from gasoline engines. Therefore, it's seen as one of the best ways to meet future engine emissions and CO2 legislations. This combustion concept was achieved in a Ford production, port-injected, 4 cylinder gasoline engine. The only major modification to the original engine was the replacement of the original camshafts by a new set of custom made ones. The CAI operation was accomplished by means of using residual gas trapping made possible by the use of VCT (variable cam timing) on both intake and exhaust camshafts. When running on CAI, the engine was able to achieve CAI combustion with in a load range of 0.5 to 4.5 BMEP, and a speed range of 1000 to 3500 rpm. In addition, spark assisted CAI operation was employed to extend the operational range of low NOx and low pumping loss at part-load conditions.
Technical Paper

Progress in Diesel HCCI Combustion Within the European SPACE LIGHT Project

2004-06-08
2004-01-1904
The purpose of the European « SPACE LIGHT » (Whole SPACE combustion for LIGHT duty diesel vehicles) 3-year project launched in 2001 is to research and develop an innovative Homogeneous internal mixture Charged Compression Ignition (HCCI) for passenger cars diesel engine where the combustion process can take place simultaneously in the whole SPACE of the combustion chamber while providing almost no NOx and particulates emissions. This paper presents the whole project with the main R&D tasks necessary to comply with the industrial and technical objectives of the project. The research approach adopted is briefly described. It is then followed by a detailed description of the most recent progress achieved during the tasks recently undertaken. The methodology adopted starts from the research study of the in-cylinder combustion specifications necessary to achieve HCCI combustion from experimental single cylinder engines testing in premixed charged conditions.
Technical Paper

Development of a Two-Stroke/Four-Stroke Switching Gasoline Engine - The 2/4SIGHT Concept

2005-04-11
2005-01-1137
The pursuit of flexibility is a recurring theme in engine design and development. Engines that are able to switch between the two-stroke operating cycle and four-stroke operation promise a great leap in flexibility. Such 2S-4S engines could then continuously select the optimum operating mode - including HCCI/CAI combustion - for fuel efficiency, emissions or specific output. With recent developments in valvetrain technology, advanced boosting devices, direct fuel injection and engine control, the 2S-4S engine is an increasingly real prospect. The authors have undertaken a comprehensive feasibility study for 2S-4S gasoline engines. This study has encompassed concept and detailed design, design analysis, one-dimensional gas dynamics simulation, three-dimensional computational fluid dynamics, and vehicle simulation. The resulting 2/4SIGHT concept engine is a 1.04 l in-line three-cylinder engine producing 230 Nm and 85 kW.
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.
Technical Paper

Numerical Study of Effects of Fuel Injection Timings on CAI/HCCI Combustion in a Four-Stroke GDI Engine

2005-04-11
2005-01-0144
The Controlled Auto-Ignition (CAI) combustion, also known as Homogeneous Charge Compression Ignition (HCCI) was achieved by trapping residuals with early exhaust valve closure in conjunction with direct injection. Multi-cycle 3D engine simulations have been carried out for parametric study on four different injection timings, in order to better understand the effects of injection timings on in-cylinder mixing and CAI combustion. The full engine cycle simulation including complete gas exchange and combustion processes was carried out over several cycles in order to obtain the stable cycle for analysis. The combustion models used in the present study are the Shell auto-ignition model and the characteristic-time combustion model, which were modified to take the high level of EGR into consideration. A liquid sheet breakup spray model was used for the droplet breakup processes.
Technical Paper

Investigation of Valve Timings on Lean Boost CAI Operation in a Two-stroke Poppet Valve DI Engine

2015-09-01
2015-01-1794
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. In order to take advantage of the inherent ability to retain a large and varied amount of residual at part-load condition and its potential to achieve extreme engine downsizing of a poppet valve engine running in the 2-stroke cycle, a single cylinder 4-valves camless direct injection gasoline engine has been developed and employed to investigate the CAI combustion process in the 2-stroke cycle mode. The CAI combustion is initiated by trapped residual gases from the adjustable scavenging process enabled by the variable intake and exhaust valve timings. In addition, the boosted intake air is used to provide the in-cylinder air/fuel mixture for maximum combustion efficiency.
Technical Paper

Effects of Ignition Timing on CAI Combustion in a Multi-Cylinder DI Gasoline Engine

2005-10-24
2005-01-3720
Having achieved CAI-combustion in a 4-cylinder four-stroke gasoline DI engine the effects of ignition timing on the CAI combustion process were investigated through the introduction of spark. By varying the start of fuel injection, the effects on Indicated Specific values for NOx, HC, CO emissions and fuel consumption were investigated for CAI combustion. The CAI combustion process was then assisted by spark and three different ignition timings were studied. The effect on engine performance and the emission specific values were investigated further. The engine speed was maintained at 1500 rpm and lambda was kept constant at 1.2. It was found that with spark-assisted CAI, IMEP and ISNOx values increased as compared with typical CAI. ISHC values were lower for spark-assisted CAI as compared to typical CAI. Heat release data was studied to better understand this phenomenon.
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