Showing papers in "International Journal of Engine Research in 2016"
TL;DR: Low-temperature combustion is an emerging engine technology that has the ability to yield low NOx and soot emissions while maintaining high fuel efficiency as discussed by the authors, and it has been shown that low temperature combustion strategies can reduce SOI and NOx emissions.
Abstract: Low-temperature combustion is an emerging engine technology that has the ability to yield low NOx and soot emissions while maintaining high fuel efficiency. Low-temperature combustion strategies in...
150 citations
TL;DR: Further significant CO2 emission reduction beyond 2020 is mandatory in the United States and might also become mandatory in Europe, depending on the passenger car CO2 legislation, which is to be en... as discussed by the authors.
Abstract: Further significant CO2 emission reduction beyond 2020 is mandatory in the United States and might also become mandatory in Europe, depending on the passenger car CO2 legislation, which is to be en...
127 citations
TL;DR: In this paper, it has been demonstrated that achieving low temperature combustion with diesel fuel over a wide range of conditions is difficult because of its properties, namely, low volatility and high chemical reactivity.
Abstract: Many research studies have shown that low temperature combustion in compression ignition engines has the ability to yield ultra-low NOx and soot emissions while maintaining high thermal efficiency. To achieve low temperature combustion, sufficient mixing time between the fuel and air in a globally dilute environment is required, thereby avoiding fuel-rich regions and reducing peak combustion temperatures, which significantly reduces soot and NOx formation, respectively. It has been demonstrated that achieving low temperature combustion with diesel fuel over a wide range of conditions is difficult because of its properties, namely, low volatility and high chemical reactivity. On the contrary, gasoline has a high volatility and low chemical reactivity, meaning it is easier to achieve the amount of premixing time required prior to autoignition to achieve low temperature combustion. In order to achieve low temperature combustion while meeting other constraints, such as low pressure rise rates and maintaining ...
108 citations
TL;DR: Increasing carbon dioxide accumulation in earth's atmosphere and the depletion of fossil resources pose huge challenges for our society and, in particular, for all stakeholders in the transportatio... as discussed by the authors.
Abstract: Increasing carbon dioxide accumulation in earth’s atmosphere and the depletion of fossil resources pose huge challenges for our society and, in particular, for all stakeholders in the transportatio...
99 citations
TL;DR: In this paper, a 1.6-L naturally-aspirated prototype engine consisted of water direct injection and port fuel injection systems, and the effects of water injection were further investigated under full load condition within the engine speed range of 1500-3000 r/min.
Abstract: Water was directly injected into the cylinder with an injection pressure of 5 MPa to investigate its effect on engine performance and emissions in a gasoline engine. The test engine was a 1.6-L naturally aspirated prototype engine consisted of water direct injection and port fuel injection systems. The engine featured a compression ratio of 13.5. Commercial gasoline direct injection injectors were used to inject the water. The water was injected at a fixed timing of −120 crank angle degrees after top dead center. The addition of water showed potential to mitigate the knock occurrence at part-load condition where the knock initially started to occur due to the high compression ratio. It allowed a further advance of spark timing; thus, the brake-specific fuel consumption was improved. The effects of water injection were further investigated under full-load condition within the engine speed range of 1500–3000 r/min. The water effectively reduced the in-cylinder temperature and the exhaust gas temperature; th...
63 citations
TL;DR: The sudden occurrence of boiling inside the fuel can change the spray structure dramatically as discussed by the authors, and up to 99% of all injection proces are superheated injections, which is referred to as flashboiling.
Abstract: By definition, flashboiling is referred to as superheated injections. The sudden occurrence of boiling inside the fuel can change the spray structure dramatically. Up to 99% of all injection proces...
56 citations
TL;DR: In this article, large efforts are currently being made toward improving internal combustion engine efficiency without degrading overall performance, which requires in-cycle combustion strategies that require in-cycling engines.
Abstract: Large efforts are currently being made toward improving internal combustion engine efficiency without degrading overall performance. To this end, advanced combustion strategies that require in-cyli...
52 citations
TL;DR: In this paper, the authors investigated the effect of wall heat transfer and thermal stratification during the compression stroke under engine relevant conditions using direct numerical simulations (DNS) in order to avoid arcing.
Abstract: Unsteady wall heat transfer and thermal stratification during the compression stroke under engine relevant conditions are investigated using direct numerical simulations (DNS). In order to avoid ar...
47 citations
TL;DR: In this article, the authors highlight and discuss the transition to scale-resolving simulations and propose a systematic approach for model development and application, especially with respect to cycle-to-cycle variations, which cannot be identified with unsteady Reynolds-averaged Navier-Stokes models.
Abstract: The increasing availability of high-performance computing resources will allow scale-resolving simulations such as large eddy simulations to be used instead of unsteady Reynolds-averaged Navier–Stokes approaches, not only in academic research but also for engine combustion process development. The scope of this work is to highlight and discuss this transition to scale-resolving simulations and to propose a systematic approach for model development and application. The current and future scope of industrial and academic research is discussed especially with respect to cycle-to-cycle variations, which cannot be identified with unsteady Reynolds-averaged Navier–Stokes models. The individual processes along the cause-and-effect chain leading to cyclic variations of the combustion process are identified, and the current state of scale-resolving simulations and the required models with respect to these processes are discussed.
47 citations
TL;DR: In this article, practical aspects of light-duty diesel combustion system design are reviewed, with an emphasis on design considerations reported by manufacturers and engine design consultancies, including the factors driving the selection of compression ratio, stroke-to-bore ratio, and various aspects of combustion chamber geometry.
Abstract: Practical aspects of light-duty diesel combustion system design are reviewed, with an emphasis on design considerations reported by manufacturers and engine design consultancies. The factors driving the selection of compression ratio, stroke-to-bore ratio, and various aspects of combustion chamber geometry are examined, along with the trends observed in these parameters in recently released engines. The interactions among geometric characteristics, swirl ratio, and the fuel injection nozzle parameters are also reviewed.
47 citations
TL;DR: In this article, the authors demonstrate that cylinder deactivation improves exhaust thermal management during both loaded and lightly loaded idle conditions, and demonstrate that coupling cylinder deactivations with flexible valve motions results in additional benefits during lightly-loaded idle operation.
Abstract: Fuel efficient thermal management of diesel engine aftertreatment is a significant challenge, particularly during cold start, extended idle, urban driving, and vehicle operation in cold ambient conditions. Aftertreatment systems incorporating NOx-mitigating selective catalytic reduction and diesel oxidation catalysts must reach ∼250 °C to be effective. The primary engine-out condition that affects the ability to keep the aftertreatment components hot is the turbine outlet temperature; however, it is a combination of exhaust flow rate and turbine outlet temperature that impact the warm-up of the aftertreatment components via convective heat transfer. This article demonstrates that cylinder deactivation improves exhaust thermal management during both loaded and lightly loaded idle conditions. Coupling cylinder deactivation with flexible valve motions results in additional benefits during lightly loaded idle operation. Specifically, this article illustrates that at loaded idle, valve motion and fuel injectio...
TL;DR: In this paper, the impact of rail pressure and biodiesel fueling on exhaust particulate agglomerate morphology and primary particle (soot) nanostructure was conducted with a common-rail turboc...
Abstract: An investigation of the impact of rail pressure and biodiesel fueling on exhaust particulate agglomerate morphology and primary particle (soot) nanostructure was conducted with a common-rail turboc...
TL;DR: In this paper, a multi-dimensional model was applied to investigate the influence of combustion regimes on heat transfer losses in internal combustion engines, and the results indicated that the total heat transfer loss of conventional diesel combustion is the largest among the three combustion regimes due to direct interaction of the high-temperature flame with the piston wall.
Abstract: A multi-dimensional model was applied to investigate the influence of combustion regimes on heat transfer losses in internal combustion engines. By utilizing improved turbulence and heat transfer sub-models, the combustion and heat transfer characteristics of the engine were satisfactorily reproduced for operation under conventional diesel combustion, homogeneous charge compression ignition, and reactivity controlled compression ignition regimes. The results indicated that the total heat transfer losses of conventional diesel combustion are the largest among the three combustion regimes due to the direct interaction of the high-temperature flame with the piston wall, while the heat transfer losses of reactivity controlled compression ignition are the lowest and nearly are independent of combustion phasing because of the avoidance of high-temperature regions adjacent to the cylinder walls. Compared to conventional diesel combustion, homogeneous charge compression ignition shows more potential for the reduc...
TL;DR: In this article, it was shown that process operating conditions of modern internal combustion engines can exceed the thermodynamic critical point of an injected liquid fuel, which raises the question of whether the fuel, or at least the combustion engine, is at least as hot as the critical point.
Abstract: Process operating conditions of modern internal combustion engines can exceed the thermodynamic critical point of an injected liquid fuel. This raises the question of whether the fuel, or at least ...
TL;DR: In this article, the impact of geometric variation of the intake port on in-cylinder flow and spray interactions was investigated, focusing on the second injection, since it provides ignitable mixtures at the time of ignition and is subject to strong fluctuations, rather than the first injection, which is very reproducible.
Abstract: Time-resolved particle image velocimetry and Mie-scattering of fuel droplets at 16 kHz were used to capture simultaneously the temporal evolution of the in-cylinder flow field and spray formation within a direct-injection spark-ignition engine. The engine was operated in stratified combustion mode, with stratified mixtures created by a triple injection late in the compression stroke. The impact of geometric variation of the intake port on in-cylinder flow and flow–spray interactions was investigated, focusing on the second injection, since it provides ignitable mixtures at the time of ignition and is subject to strong fluctuations, rather than the first injection, which is very reproducible. Flow field statistics conditioned on the spray shape of the second injection revealed regions with macroscopic cycle-to-cycle flow variations, which correlated with the spray for all recorded cycles. The flow–spray interaction was traced back to before the first injection using correlation analysis, which revealed tha...
TL;DR: The Livengood-Wu correlation has been widely used to predict the state of auto-ignition in internal combustion engines, although its application to two-stage ignition processes remains unresolved.
Abstract: The Livengood–Wu correlation has been widely used to predict the state of auto-ignition in internal combustion engines, although its application to two-stage ignition processes remains unresolved. ...
TL;DR: In this article, a mean value control-oriented model of RCCI is developed by combining the auto-ignition model, the burn duration model, and a Wiebe function to predict combustion phasing.
Abstract: Reactivity-controlled compression ignition (RCCI) is a promising combustion strategy to achieve near-zero NOx and soot emissions and diesel-like efficiencies. Model-based control of RCCI combustion phasing requires a computationally efficient combustion model that encompasses factors such as injection timings, fuel blend composition, and reactivity. In this work, physics-based models are developed to predict the onset of auto-ignition in RCCI and to estimate the burn duration based on an approximation of the spontaneous ignition front speed. A mean value control-oriented model of RCCI is then developed by combining the auto-ignition model, the burn duration model, and a Wiebe function to predict combustion phasing. The control-oriented model is parameterized and validated using simulation data from an experimentally validated, detailed computational fluid dynamics combustion model developed using the KIVA-3V code. The validation results show that the control-oriented model can predict the start of combust...
TL;DR: In this paper, an improved hybrid method applying both the particle swarm optimization method and genetic algorithm was developed, tested, and compared with a basic particle swarm method for improving engine emissions and performance.
Abstract: Heuristic methods have been a successful tool for optimizing engine parameters in both simulation and experimental testing. An improved hybrid method applying both the particle swarm optimization method and genetic algorithm was developed, tested, and compared with a basic particle swarm method for improving engine emissions and performance. A computational comparison between the particle swarm optimization–genetic algorithm hybrid, basic particle swarm optimization, and basic genetic algorithm was done using standard test problems. Computational results indicated improvements in both the efficiency and effectiveness of the present hybrid method. Engine testing was performed under steady-state conditions at 1400 r/min at 4.15 bar brake mean effective pressure. The basic particle swarm optimization and the hybrid particle swarm optimization–genetic algorithm method were applied to the test apparatus and used to locate the optimum neighborhood of the engine operation. A single-objective function representin...
TL;DR: In this paper, the effects of charge stratification in a direct-injection compression ignition engine under low load conditions were investigated using the spray-interactive flamelet and extended multi-zone combustion models coupled with multi-dimensional computational fluid dynamics.
Abstract: The spray-interactive flamelet and extended multi-zone combustion models coupled with multi-dimensional computational fluid dynamics are applied to investigate the effects of charge stratification in a direct-injection compression ignition engine under low load conditions. A parametric study was carried out in order to compare the two approaches for early and late fuel injection timings. Comparison of numerical results with available experimental data shows that for early fuel injection, both models predict the auto-ignition and combustion characteristics with comparable fidelity. As the fuel injection timing is delayed, however, the spray-interactive flamelet model is found to capture the onset of combustion and subsequent heat release with greater accuracy. Further investigation reveals that the better performance of the spray-interactive flamelet model over a wider range of mixture-stratified conditions is mainly attributed to its ability to capture the diffusive transport resulting from small-scale mi...
TL;DR: In this paper, the authors studied the starved lubrication problem for textured surfaces and proposed a two-dimensional solvable solver for the textured surface, where the solver can be used to solve the problem.
Abstract: The starved lubrication is common in engine. However, there are only few studies on starved lubrication problem for textured surfaces. In particular, for the textured surface, a two-dimensional sol...
TL;DR: In this paper, the authors present a methodology for zero-dimensional modeling of the mass flow rate and the rail pressure of a common rail system, constructed from a set of experimental measurements in engine-like operating conditions, for single-and multiple-injection strategies.
Abstract: Modern engine design has challenging requirements toward maximum power output, fuel consumption and emissions. For engine combustion development programs, the injection system has to be able to operate reliable under a variety of operating conditions. Today’s legislations for quieter and cleaner engines require multiple-injection strategies, where it is important to understand the behavior of the system and to measure the effect of one injection on subsequent injections. This study presents a methodology for zero-dimensional modeling of the mass flow rate and the rail pressure of a common rail system, constructed from a set of experimental measurements in engine-like operating conditions, for single- and multiple-injection strategies. The model is based on mathematical expressions and correlations that can simulate the mass flow rate obtained with the Bosch tube experiment, focusing on the shape and the injected mass, using few inputs: rail pressure, back pressure, energizing time and so on. The model tar...
TL;DR: In this article, the entire gas exchange process of turbocharged spark-ignition engines is regarded as a complete air management system instead of just looking at the boosting system, which encourages the entire process of gas exchange to be regarded as an air management problem instead of a boosting system.
Abstract: Engine downsizing, which is the use of a smaller engine that provides the power of a larger engine, is now considered a mega-trend for the internal combustion engine market. It is usually achieved using one or more boosting devices including a supercharger or a turbocharger. Although supercharging is beneficial for engine’s transient response, turbocharging technology is more widely adopted considering its advantages in fuel efficiency. Compared to turbocharged compression ignition engines, turbocharged spark-ignition engines tend to be more challenging with respect to the gas exchange process mainly due to their higher pumping loss, the need for throttling and the fact that spark-ignition engines demand more controllability due to the mitigation of knock, particularly with regard to minimizing trapped residuals. These challenges encourage the entire gas exchange process of turbocharged spark-ignition engines to be regarded as a complete air management system instead of just looking at the boosting system...
TL;DR: In this article, the performance of a turbo compressor for automo-compressor is represented using maps, measured for one set of inlet conditions and corrections are then applied to scale the performance to other inlet condition.
Abstract: Turbo performance is represented using maps, measured for one set of inlet conditions. Corrections are then applied to scale the performance to other inlet conditions. A turbo compressor for automo ...
TL;DR: In this paper, the authors present a model for controlling multiple actuators under various environment conditions, such as wind, rain, fog, and fog, in a diesel engine with good operational control.
Abstract: Diesel engines exhibit highly efficient, environmentally sound performance under good operational control; however, because of the demand of controlling multiple actuators under various environment...
TL;DR: In this paper, the entire ignition process is investigated with a special focus on interactions of consecutive pulses, and three methods are combined: energy transfer measurements from laser pulse to plasma with hig...
Abstract: Leaner burning and downsizing are two concepts pursued by engine developers to reduce fuel consumption and emissions. Both approaches lead to increasing challenges concerning ignition, as these concepts are typically associated with an increase in flow velocity and degree of turbulence as well as raised pressure at the moment of ignition. In this context, the use of miniaturized passively Q-switched laser spark plugs with pulse train ignition is considered as a promising alternative to conventional spark plugs.However, the application of these passively Q-switched laser spark plugs inevitably leads to the question of optimum pulse train parameters. For a better understanding, this study deals with improved flame formation by passively Q-switched laser pulse train ignition under engine-like conditions. The entire ignition process is investigated with a special focus on interactions of consecutive pulses. Therefore, three methods are combined: energy transfer measurements from laser pulse to plasma with hig...
TL;DR: In this article, a dual-fuel reactivity controlled compression ignition and gasoline compression ignition combustion were performed using a novel adaptive dual fuel injector capable of direct injecting both gasoline and diesel fuel in a single cycle.
Abstract: Computational optimizations of dual-fuel reactivity controlled compression ignition combustion and gasoline compression ignition combustion were performed using a novel adaptive dual-fuel injector capable of direct injecting both gasoline and diesel fuel in a single cycle. Optimization used the Engine Research Center KIVA code coupled with a multiobjective genetic algorithm. Model validation was performed by comparing simulation results to conventional diesel, reactivity controlled compression ignition, and gasoline compression ignition combustion, and the validated model was used to develop an optimum reactivity controlled compression ignition–gasoline compression ignition combustion strategy. The reactivity controlled compression ignition optimization results showed that by direct injecting gasoline and diesel fuel, the gasoline quantity can be held at a high percentage across the range of loads considered. In this study, the mode weighted gasoline percentage was 91%. At the lightest load point, direct ...
TL;DR: In this paper, fuel injection into residuals and the resulting exhaust-fuel reactions appear to be an effective method for enhancing mixture reactivity in residual effected homogeneous charge compression, which is an effective way to enhance mixture reactionivity.
Abstract: Fuel injection into retained residuals and the resulting exhaust-fuel reactions appear to be an effective method for enhancing mixture reactivity in residual effected homogeneous charge compression...
TL;DR: In this paper, the friction power losses of a turbo-charged heavy-duty diesel engine of the 13 litre class were investigated both by fired engine tests as well as by pressurized motoring tests.
Abstract: The friction power losses of a turbo-charged heavy-duty diesel engine of the 13 litre class are investigated both by fired engine tests as well as by pressurized motoring tests. During pressurized ...
TL;DR: In this paper, a numerical study is conducted to investigate the effects of fuel injection parameters, such as the injection pressure and spray cone angle, on the overall combustion efficiency and CO/NOx emissions.
Abstract: With the objective of enhancing the effectiveness of late fuel injection strategy in extending the low-load limit of homogeneous charge compression ignition engines, a numerical study is conducted to investigate the effects of fuel injection parameters, such as the injection pressure and spray cone angle, on the overall combustion efficiency and CO/NOx emissions. Closed-cycle engine simulations are performed incorporating detailed iso-octane reaction kinetics and combustion submodel based on the spray-interactive flamelet approach. Extensive parametric studies are conducted to provide a detailed map of the combustion efficiency and emission performance. In general, it is found that the in-cylinder charge stratification can be reduced by both an increased injection pressure and a wider spray cone angle, resulting in substantially lower NOx emissions and reasonably high combustion efficiency simultaneously. The present study demonstrates that an optimal adjustment of the two fuel injection parameters can re...
TL;DR: In this article, a simulation process for spark ignition gasoline engines is proposed, based on a zero-dimensional spark ignition stochastic reactor model and three-dimensional computational fluid dynamics of the cold in-cylinder flow.
Abstract: A simulation process for spark ignition gasoline engines is proposed. The process is based on a zero-dimensional spark ignition stochastic reactor model and three-dimensional computational fluid dynamics of the cold in-cylinder flow. The cold flow simulations are carried out to analyse changes in the turbulent kinetic energy and its dissipation. From this analysis, the volume-averaged turbulent mixing time can be estimated that is a main input parameter for the spark ignition stochastic reactor model. The spark ignition stochastic reactor model is used to simulate combustion progress and to analyse auto-ignition tendency in the end-gas zone based on the detailed reaction kinetics. The presented engineering process bridges the gap between three-dimensional and zero-dimensional models and is applicable to various engine concepts, such as, port-injected and direct injection engines, with single and multiple spark plug technology. The modelling enables predicting combustion effects and estimating the risk of ...