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Viewing 1 to 30 of 125
2017-03-28
Technical Paper
2017-01-0636
Vijai Shankar Bhavani Shankar, Nhut Lam, Arne Andersson, Bengt Johansson
Abstract The concept of double compression, and double expansion engine (DCEE) for improving the efficiency of piston reciprocating engines was introduced in SAE Paper 2015-01-1260. This engine configuration has separate high, and low pressure units thereby effectively reducing friction losses for high effective compression ratios. The presence of an additional expander stage also theoretically allows an extra degree of freedom to manipulate the combustion heat release rate so as to achieve better optimum between heat transfer, and friction losses. This paper presents a 1-D modeling study of the engine concept in GT-Power for assessing the sensitivity of engine losses to heat release rate. The simulations were constrained by limiting the maximum pressure to 300 bar.
2017-03-28
Technical Paper
2017-01-0560
Mateusz Pucilowski, Mehdi Jangi, Sam Shamun, Changle Li, Martin Tuner, Xue-Song Bai
Abstract Methanol as an alternative fuel in internal combustion engines has an advantage in decreasing emissions of greenhouse gases and soot. Hence, developing of a high performance internal combustion engine operating with methanol has attracted the attention in industry and academic research community. This paper presents a numerical study of methanol combustion at different start-of-injection (SOI) in a direct injection compression ignition (DICI) engine supported by experimental studies. The aim is to investigate the combustion behavior of methanol with single and double injection at close to top-dead-center (TDC) conditions. The experimental engine is a modified version of a heavy duty D13 Scania engine. URANS simulations are performed for various injection timings with delayed SOI towards TDC, aiming at analyzing the characteristics of partially premixed combustion (PPC).
2017-03-28
Technical Paper
2017-01-0708
Carlos Jorques Moreno, Ola Stenlaas, Per Tunestal
Abstract Factors influencing the effect of pilot-injection on main-injection combustion were investigated using heat release analysis in a heavy-duty diesel engine fuelled with standard diesel fuel, and included the effect of those factors on engine performance and emissions. Combinations of pilot injection parameters i.e. pilot start of injection, pilot mass, pilot-main injection separation, and rail pressure were studied for various operating conditions and combustion phases. It was concluded that the effect of pilot-injection combustion on main injection can be studied based on the phase of pilot combustion at the start of main injection. Four cases were identified: a) main injection during the mixing phase of pilot injection; b) main injection during the premixed phase of pilot combustion; c) main injection during the diffusive phase of pilot combustion and d) main injection after pilot combustion was completed.
2017-03-28
Technical Paper
2017-01-0511
Tianhao Yang, Lianhao Yin, Gabriel Ingesson, Per Tunestal, Rolf Johansson, Wuqiang Long
Abstract In this paper, a control-oriented soot model was developed for real-time soot prediction and combustion condition optimization in a gasoline Partially Premixed Combustion (PPC) Engine. PPC is a promising combustion concept that achieves high efficiency, low soot and NOx emissions simultaneously. However, soot emissions were found to be significantly increased with high EGR and pilot injection, therefore a predictive soot model is needed for PPC engine control. The sensitivity of soot emissions to injection events and late-cycle heat release was investigated on a multi-cylinder heavy duty gasoline PPC engine, which indicated main impact factors during soot formation and oxidation processes. The Hiroyasu empirical model was modified according to the sensitivity results, which indicated main influences during soot formation and oxidation processes. By introducing additional compensation factors, this model can be used to predict soot emissions under pilot injection.
2017-03-28
Technical Paper
2017-01-0752
Sara Lonn, Alexios Matamis, Martin Tuner, Mattias Richter, Oivind Andersson
Abstract Low temperature combustion modes, such as Homogeneous Charge Compression Ignition (HCCI) and Partially Premixed Combustion (PPC), have been researched over recent decades since the concepts show promise for high efficiency and low emissions compared to conventional diesel combustion. PPC is an intermediate combustion type ranging from HCCI-like combustion to diesel-like combustion. The purpose of this paper is to study optically how the combustion and ignition are affected by different start of injection (SOI) timings. The study is carried out in an optically accessible heavy-duty single-cylinder engine with swirl. The intake pressure was kept constant while the intake temperature was varied to keep the combustion phasing (CA50) constant at ∼3 CAD atdc during an SOI sweep. The fuel used is a mix of primary reference fuels with octane number 81. To determine where the combustion starts, high-speed combustion imaging is used to detect the natural luminosity.
2017-03-28
Technical Paper
2017-01-0753
Marcus Olof Lundgren, Zhenkan Wang, Alexios Matamis, Oivind Andersson, Mattias Richter, Martin Tuner, Marcus Alden, Andersson Arne
Abstract Gasoline partially premixed combustion (PPC) has shown potential in terms of high efficiency with low emissions of oxides of nitrogen (NOx) and soot. Despite these benefits, emissions of unburned hydrocarbons (UHC) and carbon monoxide (CO) are the main shortcomings of the concept. These are caused, among other things, by overlean zones near the injector tip and injector dribble. Previous diesel low temperature combustion (LTC) research has demonstrated post injections to be an effective strategy to mitigate these emissions. The main objective of this work is to investigate the impact of post injections on CO and UHC emissions in a quiescent (non-swirling) combustion system. A blend of primary reference fuels, PRF87, having properties similar to US pump gasoline was used at PPC conditions in a heavy duty optical engine. The start of the main injection was maintained constant. Dwell and mass repartition between the main and post injections were varied to evaluate their effect.
2017-03-28
Journal Article
2017-01-1046
Christian Binder, Fahed Abou Nada, Mattias Richter, Andreas Cronhjort, Daniel Norling
Abstract Diesel engine manufacturers strive towards further efficiency improvements. Thus, reducing in-cylinder heat losses is becoming increasingly important. Understanding how location, thermal insulation, and engine operating conditions affect the heat transfer to the combustion chamber walls is fundamental for the future reduction of in-cylinder heat losses. This study investigates the effect of a 1mm-thick plasma-sprayed yttria-stabilized zirconia (YSZ) coating on a piston. Such a coated piston and a similar steel piston are compared to each other based on experimental data for the heat release, the heat transfer rate to the oil in the piston cooling gallery, the local instantaneous surface temperature, and the local instantaneous surface heat flux. The surface temperature was measured for different crank angle positions using phosphor thermometry.
2017-03-28
Journal Article
2017-01-0718
Carlos Jorques Moreno, Ola Stenlaas, Per Tunestal
Abstract Factors influencing pilot-injection combustion were investigated using heat release analysis in a heavy-duty diesel engine fuelled with standard diesel fuel. Combinations of pilot-injection parameters i.e. pilot start of injection, pilot mass, pilot-main injection separation, and rail pressure were studied for various operating conditions and combustion phases. An experiment was designed to investigate the factors influencing the combustion of the pilot. For improved injected fuel-mass accuracy, reference data for the injectors were measured in a spray rig prior to the engine experiments. Results show that cycle-to-cycle variations and cylinder-to-cylinder variations influence pilot autoignition and the amount of heat released. Rail pressure and injected pilot mass affect the obtained variance depending on the chamber conditions. The obtained combustion modes (premixed, diffusive) of pilot combustion were found to be a function of the injected mass and rail pressure.
2017-03-28
Journal Article
2017-01-0748
Zhenkan Wang, Sara Lonn, Alexios Matamis, Oivind Andersson, Martin Tuner, Marcus Alden, Mattias Richter
Abstract In a previous study, in order to investigate the effect of charge stratification on combustion behavior such as combustion efficiency and combustion phasing which also largely affects the emissions, an experiment was conducted in a heavy-duty compression ignition (CI) metal engine. The engine behavior and emission characteristics were studied in the transition from HCCI mode to PPC mode by varying the start of injection (SOI) timing. To gain more detailed information of the mixing process, in-cylinder laser diagnostic measurements, namely fuel-tracer planar laser induced fluorescence (PLIF) imaging, were conducted in an optical version of the heavy-duty CI engine mentioned above. To the authors’ best knowledge, this is the first time to perform fuel-tracer PLIF measurements in an optical engine with a close to production bowl in piston combustion chamber, under transition conditions from HCCI to PPC mode.
2017-03-28
Journal Article
2017-01-0744
Mohammad Izadi Najafabadi, Slavey Tanov, Hua Wang, Bart Somers, Bengt Johansson, Nico Dam
Abstract Partially Premixed Combustion (PPC) is a promising combustion concept ,based on judicious tuning of the charge stratification, to meet the increasing demands of emission legislation and to improve fuel efficiency. Longer ignition delays of PPC in comparison with conventional diesel combustion provide better fuel/air mixture which decreases soot and NOx emissions. Moreover, a proper injection timing and strategy for PPC can improve the combustion stability as a result of a higher level of fuel stratification in comparison with the Homogeneous Charge Compression Ignition (HCCI) concept. Injection timing is the major parameter with which to affect the level of fuel and combustion stratification and to control the combustion phasing and the heat release behavior. The scope of the present study is to investigate the fluid flow characteristics of PPC at different injection timings.
2016-10-17
Technical Paper
2016-01-2300
Mengqin Shen, Martin Tuner, Bengt Johansson, Per Tunestal, Joakim Pagels
Abstract In order to reduce nitrogen oxides (NOx) and soot emissions while maintaining high thermal efficiency, more advanced combustion concepts have been developed over the years, such as Homogeneous Charge Compression Ignition (HCCI) and Partially Premixed Combustion (PPC), as possible combustion processes in commercial engines. Compared to HCCI, PPC has advantages of lower unburned hydrocarbon (UHC) and carbon monoxide (CO) emissions; however, due to increased fuel stratifications, soot emissions can be a challenge when adding Exhaust-Gas Recirculation (EGR) gas. The current work presents particle size distribution measurements performed from HCCI-like combustion with very early (120 CAD BTDC) to PPC combustion with late injection timing (11 CAD BTDC) at two intake oxygen rates, 21% and 15% respectively. Particle size distributions were measured using a differential mobility spectrometer DMS500.
2016-10-17
Technical Paper
2016-01-2159
Zheming Li, Yann Gallo, Ted Lind, Oivind Andersson, Marcus Alden, Mattias Richter
Abstract Soot emissions from diesel internal combustion engines are strictly regulated nowadays. Laser extinction measurement (LEM) and natural luminosity (NL) of sooty flames are commonly applied to study soot. LEM measures soot along the laser beam path and it can probe soot regardless of temperature. NL integrates the whole field of view and relies on soot temperature. In this work, a comparison of simultaneously recorded LEM and NL data has been performed in a heavy-duty optical engine. A 685 nm laser beam is used for LEM. The laser was modulated at 63 kHz, which facilitated subtraction of the background NL signal from the raw LEM data. By Beer-Lambert’s law, KL factor can be calculated and used as a metric to describe soot measurements. A compensation of transmitted laser intensity fluctuation and soot deposits on optical windows has been performed in this work.
2016-10-17
Technical Paper
2016-01-2212
Peter Larsson, Will Lennard, Jessica Dahlstrom, Oivind Andersson, Per Tunestal
Abstract Yearly 3.3 million premature deaths occur worldwide due to air pollution and NOx pollution counts for nearly one seventh of those [1]. This makes exhaust after-treatment a very important research and has caused the permitted emission levels for NOx to decrease to very low levels, for EURO 6 only 0.4 g/kWh. Recently new legislation on ammonia slip with a limit of 10 ppm NH3 has been added [2], which makes the SCR-technology more challenging. This technology injects small droplets of an aqueous Urea solution into the stream of exhaust gases and through a catalytic reaction within the SCR-catalyst, NOx is converted into Nitrogen and Water. To enable the catalytic reaction the water content in the Urea solution needs to be evaporated and the ammonia molecules need to have sufficient time to mix with the gases prior to the catalyst.
2016-10-17
Technical Paper
2016-01-2211
Peter Larsson, Will Lennard, Oivind Andersson, Per Tunestal
Abstract Increased research is being driven by the automotive industry facing challenges, requiring to comply with both current and future emissions legislation, and to lower the fuel consumption. The reason for this legislation is to restrict the harmful pollution which every year causes 3.3 million premature deaths worldwide [1]. One factor that causes this pollution is NOx emissions. NOx emission legislation has been reduced from 8 g/kWh (Euro I) down to 0.4 g/kWh (Euro VI) and recently new legislation for ammonia slip which increase the challenge of exhaust aftertreatment with a SCR system. In order to achieve a good NOx conversion together with a low slip of ammonia, small droplets of Urea solution needs to be injected which can be rapidly evaporated and mixed into the flow of exhaust gases.
2016-10-17
Journal Article
2016-01-2288
Sam Shamun, Mengqin Shen, Bengt Johansson, Martin Tuner, Joakim Pagels, Anders Gudmundsson, Per Tunestal
Abstract The focus has recently been directed towards the engine out soot from Diesel engines. Running an engine in PPC (Partially Premixed Combustion) mode has a proven tendency of reducing these emissions significantly. In addition to combustion strategy, several studies have suggested that using alcohol fuels aid in reducing soot emissions to ultra-low levels. This study analyzes and compares the characteristics of PM emissions from naphtha gasoline PPC, ethanol PPC, methanol PPC and methanol diffusion combustion in terms of soot mass concentration, number concentration and particle size distribution in a single cylinder Scania D13 engine, while varying the intake O2. Intake temperature and injection pressure sweeps were also conducted. The fuels emitting the highest mass concentration of particles (Micro Soot Sensor) were gasoline and methanol followed by ethanol.
2016-10-17
Journal Article
2016-01-2183
Yann Gallo, Zheming Li, Mattias Richter, Oivind Andersson
Abstract Soot emissions from diesel engines are the net result of two competing processes: soot formation and soot oxidation. Previous studies have shown poor correlation between soot formation rates and the soot emissions. This article presents a systematic study of a number of parameters affecting soot oxidation rate and how it correlates with the soot emissions. An optical heavy-duty engine is used in conjunction with a laser extinction setup in order to collect time resolved data of the soot concentration in the cylinder during the expansion stroke. Laser extinction is measured using a red (685 nm) laser beam, which is sent vertically through the cylinder and modulated to produce 10 pulses per crank angle degree. Information is obtained about the amount of soot formed and the soot oxidation rate. The parameters studied are the motored density at top dead center (TDC), motored temperature at TDC, injection pressure, engine speed, swirl level and injector orifice diameter.
2016-04-05
Technical Paper
2016-01-0761
Mohammad Izadi Najafabadi, Nico Dam, Bart Somers, Bengt Johansson
Abstract Partially Premixed Combustion (PPC) is a promising combustion concept for future IC engines. However, controllability of PPC is still a challenge and needs more investigation. The scope of the present study is to investigate the ignition sensitivity of PPC to the injection timing at different injection pressures. To better understand this, high-speed shadowgraphy is used to visualize fuel injection and evaporation at different Start of Injections (SOI). Spray penetration and injection targeting are derived from shadowgraphy movies. OH* chemiluminescence is used to comprehensively study the stratification level of combustion which is helpful for interpretation of ignition sensitivity behavior. Shadowgraphy results confirm that SOI strongly affects the spray penetration and evaporation of fuel. However, spray penetration and ignition sensitivity are barely affected by the injection pressure.
2016-04-05
Technical Paper
2016-01-0767
Changle Li, Lianhao Yin, Sam Shamun, Martin Tuner, Bengt Johansson, Rickard Solsjo, Xue-Song Bai
Abstract An experiment was conducted to investigate the effect of charge stratification on the combustion phasing in a single cylinder, heavy duty (HD) compression ignition (CI) engine. To do this the start of injection (SOI) was changed from -180° after top dead centre (ATDC) to near top dead centre (TDC) during which CA50 (the crank angle at which 50% of the fuel energy is released) was kept constant by changing the intake temperature. At each SOI, the response of CA50 to a slight increase or decrease of either intake temperature or SOI were also investigated. Afterwards, the experiment was repeated with a different intake oxygen concentration. The results show that, for the whole SOI period, the required intake temperature to keep constant CA50 has a “spoon” shape with the handle on the -180° side.
2016-04-05
Technical Paper
2016-01-0763
Lianhao Yin, Gabriel Ingesson, Per Tunestal, Rolf Johansson, Bengt Johansson
Abstract Partially Premixed Combustion (PPC) is a promising combustion concept with high thermodynamic efficiency and low emission level, and also with minimal modification of standard engine hardware. To use PPC in a production oriented engine, the optimal intake charge conditions for PPC should be included in the analysis. The experiments in this paper investigated and confirmed that the optimal intake conditions of net indicated efficiency for PPC are EGR between 50% and 55% as possible and the lambda close to 1.4. Heat-transfer energy and exhaust gas waste-energy contribute to the majority of the energy loss in the engine. The low EGR region has high heat-transfer and low exhaust gas enthalpy-waste, while the high EGR region has low heat-transfer and high exhaust gas waste-enthalpy. The optimal EGR condition is around 50% where the smallest energy loss is found as a trade-off between heat transfer and exhaust-gas enthalpy-waste.
2016-04-05
Technical Paper
2016-01-0796
Ashish Shah, Per Tunestal, Bengt Johansson
Abstract This article presents a study related to application of pre-chamber ignition system in heavy duty natural gas engine which, as previously shown by the authors, can extend the limit of fuel-lean combustion and hence improve fuel efficiency and reduce emissions. A previous study about the effect of pre-chamber volume and nozzle diameter on a single cylinder 2 liter truck-size engine resulted in recommendations for optimal pre-chamber geometry settings. The current study is to determine the dependency of those settings on the engine size. For this study, experiments are performed on a single cylinder 9 liter large bore marine engine with similar pre-chamber geometry and a test matrix of similar and scaled pre-chamber volume and nozzle diameter settings. The effect of these variations on main chamber ignition and the following combustion is studied to understand the scalability aspects of pre-chamber ignition. Indicated efficiency and engine-out emission data is also presented.
2016-04-05
Technical Paper
2016-01-0805
Pablo Garcia Valladolid, Per Tunestal
Abstract The use of compressed natural gas (CNG) in light duty applications is still restricted to conventional spark ignition engines operating at low compression ratio, so overall efficiency is limited. A combustion concept that has been successfully applied on large stationary engines and to some extent on heavy-duty engines is dual-fuel combustion, where a compression-ignited diesel pilot injection is used to ignite a homogeneous charge of methane gas and air. CNG is injected in the intake ports during the intake stroke and later in the cycle the premixed air-CNG mixture is ignited via a pilot diesel injection close to top dead center. However, this concept has not been applied to a significant extent on light duty engines yet. The main reasons are linked to high temperature methane oxidation requirements and poor combustion efficiency at diluted conditions at low loads.
2016-04-05
Technical Paper
2016-01-0887
Erik Svensson, Changle Li, Sam Shamun, Bengt Johansson, Martin Tuner, Cathleen Perlman, Harry Lehtiniemi, Fabian Mauss
Abstract Methanol is today considered a viable green fuel for combustion engines because of its low soot emissions and the possibility of it being produced in a CO2-neutral manner. Methanol as a fuel for combustion engines have attracted interest throughout history and much research was conducted during the oil crisis in the seventies. In the beginning of the eighties the oil prices began to decrease and interest in methanol declined. This paper presents the emission potential of methanol. T-Φ maps were constructed using a 0-D reactor with constant pressure, temperature and equivalence ratio to show the emission characteristics of methanol. These maps were compared with equivalent maps for diesel fuel. The maps were then complemented with engine simulations using a stochastic reactor model (SRM), which predicts end-gas emissions. The SRM was validated using experimental results from a truck engine running in Partially Premixed Combustion (PPC) mode at medium loads.
2016-04-05
Technical Paper
2016-01-0882
Martin Tuner
Abstract Alternative fuels have been proposed as a means for future energy-secure and environmentally sustainable transportation. This review and benchmarking show that several of the alternative fuels (e.g. methanol, ethanol, higher alcohols, RME, HVO, DME, and biogas/CNG) work well with several different engine concepts such as conventional SI, DICI, and dual fuel, and with the emerging concepts HCCI, RCCI, and PPC. Energy consumption is in most cases similar to that of diesel or gasoline, with the exception of methanol and ethanol that use less energy, especially in SI engines. Tailpipe emissions of CO2 with respect to engine work output (tank-to-output shaft) can be reduced by more than 15% compared to a highly efficient gasoline SI engine, and are the lowest with CNG / lean-burn SI and with alcohols in several engine concepts. Alternative fuels are considered safe and in most cases are associated with reduced risk with respect to cancer and other health and environmental issues.
2016-04-05
Journal Article
2016-01-0723
Ted Lind, Zheming Li, Carlos Micó, Nils-Erik Olofsson, Per-Erik Bengtsson, Mattias Richter, Öivind Andersson
Abstract The effects of injection pressure and swirl ratio on the in-cylinder soot oxidation are studied using simultaneous PLIF imaging of OH and LII imaging of soot in an optical diesel engine. Images are acquired after the end of injection in the recirculation zone between two adjacent diesel jets. Scalars are extracted from the images and compared with trends in engine-out soot emissions. The soot emissions decrease monotonically with increasing injection pressure but show a non-linear dependence on swirl ratio. The total amount of OH in the images is negatively correlated with the soot emissions, as is the spatial proximity between the OH and soot regions. This indicates that OH is an important soot oxidizer and that it needs to be located close to the soot to perform this function. The total amount of soot in the images shows no apparent correlation with the soot emissions, indicating that the amount of soot formed is a poor predictor of the emission trends.
2016-04-05
Technical Paper
2016-01-0732
Jessica Dahlstrom, Oivind Andersson, Martin Tuner, Håkan Persson
Abstract Heat loss is one of the greatest energy losses in engines. More than half of the heat is lost to cooling media and exhaust losses, and they thus dominate the internal combustion engine energy balance. Complex processes affect heat loss to the cylinder walls, including gas motion, spray-wall interaction and turbulence levels. The aim of this work was to experimentally compare the heat transfer characteristics of a stepped-bowl piston geometry to a conventional re-entrant diesel bowl studied previously and here used as the baseline geometry. The stepped-bowl geometry features a low surface-to-volume ratio compared to the baseline bowl, which is considered beneficial for low heat losses. Speed, load, injection pressure, swirl level, EGR rate and air/fuel ratio (λ) were varied in a multi-cylinder light duty engine operated in conventional diesel combustion (CDC) mode.
2015-09-06
Technical Paper
2015-24-2454
Zhenkan Wang, Slavey Tanov, Hua Wang, Mattias Richter, Bengt Johansson, Marcus Alden
It has been proven that partially premixed combustion (PPC) has the capability of high combustion efficiency with low soot and NOx emissions, which meet the requirements of increasingly restricted emission regulations. In order to obtain more homogenous combustion and longer ignition delay in PPC, different fuel injection strategies were employed which could affect the fuel air mixing and control the combustion. In the present work, a light duty optical diesel engine was used to conduct high speed particle image velocimetry (PIV) for single, double and triple injections with different timings. A quartz piston and a cylinder liner were installed in the Bowditch configuration to enable optical access. The geometry of the quartz piston crown is based on the standard diesel combustion chamber design for this commercial passenger car engine, including a re-entrant bowl shape.
2015-09-06
Technical Paper
2015-24-2455
Slavey Tanov, Zhenkan Wang, Hua Wang, Mattias Richter, Bengt Johansson
Abstract Partially premixed combustion (PPC) is used to meet the increasing demands of emission legislation and to improve fuel efficiency. With gasoline fuels, PPC has the advantage of a longer premixed duration of the fuel/air mixture, which prevents soot formation. In addition, the overall combustion stability can be increased with a longer ignition delay, providing proper fuel injection strategies. In this work, the effects of multiple injections on the generation of in-cylinder turbulence at a single swirl ratio are investigated. High-speed particle image velocimetry (PIV) is conducted in an optical direct-injection (DI) engine to obtain the turbulence structure during fired conditions. Primary reference fuel (PRF) 70 (30% n-heptane and 70% iso-octane) is used as the PPC fuel. In order to maintain the in-cylinder flow as similarly as possible to the flow that would exist in a production engine, the quartz piston retains a realistic bowl geometry.
2015-09-06
Journal Article
2015-24-2439
Pablo Garcia, Per Tunestal
In the last decades, emission legislation on pollutant emissions generated by road transportation sector has become the main driving force for internal combustion engine development. Approximately 20% of worldwide emissions of carbon dioxide from fuel combustion come from the transportation sector, and road vehicles contribute up to 80% of those emissions [1]. Light-duty methane gas engines are usually spark-ignited due to similar combustion characteristics for methane gas and gasoline. Since spark ignition requires a low compression ratio to avoid knock problems, gas engines have lower efficiency than diesel engines. A combustion concept that has been successfully applied on large stationary engines and to some extent on heavy-duty engines is dual-fuel combustion, where a compression-ignited diesel pilot injection is used to ignite a homogeneous charge of methane gas and air.
2015-09-06
Journal Article
2015-24-2424
Gabriel Ingesson, Lianhao Yin, Rolf Johansson, Per Tunestal
Abstract In low-temperature combustion concepts such as partially premixed combustion, the ignition delay should be large enough in order to ensure sufficient fuel and air mixing before the start of combustion. It is also necessary that the combustion timing is sufficiently well phased for high thermal efficiency. Since the ignition delay and combustion timing are intimately coupled, the decoupling of these two quantities gives rise to an interesting multiple input, multiple output control problem where the control of the air system and the fuel injection system have to be combined. In a multi-cylinder engine this problem becomes underdetermined or uncontrollable with more outputs than inputs. This article investigates model-based cycle-to-cycle cylinder-individual closed-loop control of the ignition delay and the combustion phasing in a multi-cylinder heavy-duty DI engine running on a gasoline fuel mixture.
2015-09-01
Technical Paper
2015-01-1790
Mengqin Shen, Sara Lonn, Bengt Johansson
Partially premixed combustion (PPC) is a promising way to achieve high efficiency and low engine-out emissions simultaneously in a heavy-duty engine. Compared to Homogeneous Charge Compression Ignition (HCCI), it can be controlled by injection events and much lower HC and CO emissions can be achieved. This work focuses on the transition from HCCI to PPC and combustion and emissions characteristics during the process are investigated. Injection strategies, EGR and boost pressure were the main parameters used to present the corresponding effect during the transition.
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