Advanced Diesel Engines Research Articles

A numerical study on the effects of bowl and nozzle geometry on performances of an engine fueled with diesel or bio-diesel fuels

Abstract One of the most important trends for advanced diesel engines is downsizing, i.e., higher power density, which means more fuel is burned in a shorter period. In order to achieve rapid combustion for a high-power density diesel engine, the effects of bowl shape, diameter-to-depth ratio of bowl, and arrangement of nozzle holes on combustion and performance were investigated by CFD simulation. The effects of four bowl shapes, two of which were double-layer split bowls (DLSBs), as well as four diameter-to-depth ratios and three arrangements of nozzle holes were numerically assessed. The results show that the DLSB with a shallow dish-like structure yielded a remarkable effect of swirling flow by fuel splitting into upper- and lower-layer zones, which improved fuel–air mixing, shortened combustion duration, thus, resulting in high combustion efficiency and power density. Moreover, with the increase in diameter-to-depth ratio of the B type DLSB, the turbulent kinetic energy and the peak of pressure and heat release rate increased, further increasing power density. Finally, when the DLSB with a diameter-to-depth ratio of 2.0 is coupled with the staggered double-layer arrangement of nozzle holes, the in-cylinder mixtures became more uniform at both the circumferential and radial directions, and the combustion was considerably accelerated, achieving an optimum specific power of 122.6 kW·L−1. Meanwhile, there was a slight decrement for peak pressure and NOx emission, and smoke decreased by 49.1%, which revealed substantial improvement in reduction in mechanical load and emissions.

Life Cycle Cost Analysis of Ashore Marine Engine Room

This paper aims to present a method for comparing decision options for the ashore marine engine room. Based on the life cycle cost system, the life cycle stages are divided into design, acquisition, installation, operation, maintenance, and scrapping. A model of the life cycle cost of ashore marine engine room considering the time value of money was developed, and a calculation method for sensitivity analysis was developed. Regarding the actual case, the life cycle cost of the two options was estimated, the sensitivity of the cost of the two options was analyzed, and control recommendations were made. The results show that Option 2, with the highest initial investment, is the optimal solution, attributed to using an advanced two‐stroke diesel engine with reduced operation and maintenance costs. This will be useful for reference by maritime academies.

Study on Automatic Adaptation for Control-Oriented Model of Advanced Diesel Engine

Abstract To achieve high thermal efficiency and low emission in automobile engines, advanced combustion technologies using compression auto-ignition of premixtures have been studied, and model-based control has attracted attention for their practical applications. Although simplified physical models have been developed for model-based control, appropriate values for their model parameters vary depending on the operating conditions, engine driving environment, and engine aging. Herein, we studied an onboard adaptation method of model parameters in a heat release rate (HRR) model. This method adapts the model parameters using neural networks considering the operating conditions and can respond to the driving environment and the engine aging by training the neural networks onboard. Detailed studies were conducted regarding the training methods. Compared to when the model parameters were set as constants, this adaptation method significantly improved the prediction accuracy of the HRR model. Furthermore, control tests on an engine bench showed that this adaptation method also improved the model-based control accuracy of the HRR.

Real-time capable simulation of diesel combustion processes for HiL applications

The complexity of the development processes for advanced diesel engines has significantly increased during the last decades. A further increase is to be expected, due to more restrictive emission legislations and new certification cycles. This trend leads to a higher time exposure at engine test benches, thus resulting in higher costs. To counter this problem, virtual engine development strategies are being increasingly used. To calibrate the complete powertrain and various driving situations, model in the loop and hardware in the loop concepts have become more important. The main effort in this context is the development of very accurate but also real-time capable engine models. Besides the correct modeling of ambient condition and driver behavior, the simulation of the combustion process is a major objective. The main challenge of modeling a diesel combustion process is the description of mixture formation, self-ignition and combustion as precisely as possible. For this purpose, this article introduces a novel combustion simulation approach that is capable of predicting various combustion properties of a diesel process. This includes the calculation of crank angle resolved combustion traces, such as heat release and other thermodynamic in-cylinder states. Furthermore, various combustion characteristics, such as combustion phasing, maximum gradients and engine-out temperature, are available as simulation output. All calculations are based on a physical zero-dimensional heat release model. The resulting reduction of the calibration effort and the improved model robustness are the major benefits in comparison to conventional data-driven combustion models. The calibration parameters directly refer to geometric and thermodynamic properties of a given engine configuration. Main input variables to the model are the fuel injection profile and air path–related states such as exhaust gas recirculation rate and boost pressure. Thus, multiple injection event strategies or novel air path control structures for future engine control concepts can be analyzed.

Wear Characteristics of Hybrid Al 6063 Matrix Composites Reinforced with Graphite and Fly Ash Particulates

As auto manufacturers strive to meet imposed fuel economy and emissions regulations while producing vehicles with the quality and features that consumer expect, the industry needs to rely on advancements made in the field of metal matrix composites. The efforts of combining or replacing metals with the use of advanced metal matrix composites (MMCs) not only reduce weight, but can also improve safety, reliability and efficiency. A hybrid MMC was developed for the cylinder liner of advanced diesel engines. Composites of Al-6063 aluminium alloy reinforced with, fly ash particulate containing 10% and graphite particulate containing 5, 10 and 15 % were produced by stir casting. The wear and frictional properties of the casted hybrid metal matrix composites were investigated by performing dry sliding wear test using a pin-on-disc wear tester. The investigation was done to find the influence of applied load, sliding speed and sliding distance on wear rate, as well as the coefficient of friction during wearing process. From the investigation, it is evident that wear resistance of Al-6063 is increased while adding the fly ash and graphite reinforcement content. The results were compared with the existing liner material. From this comparative study the Al-6063/fly ash/graphite hybrid metal matrix composite can be the considered as an alternative material for existing cylinder material.

Sparse-Lagrangian MMC simulations of an n-dodecane jet at engine-relevant conditions

Simulations are presented for the engine combustion network (ECN) n-dodecane spray A using the sparse-Lagrangian multiple mapping conditioning model for the reactive scalar field coupled with a large eddy simulation for the flow (MMC-LES). This is the first application of the MMC-LES to both transient and engine conditions and, in line with earlier simulations of the ECN flames, the fuel injection is modelled as a gas-jet. The model is evaluated initially for a baseline non-reacting case with ambient temperature of 900 K. Results for vapour penetration lengths and the radial profiles of mixture fraction show good agreement with experiments. The model is then applied to reacting cases, featuring transient ignition and combustion with a lifted flame base. A 106-species chemistry mechanism is employed. Simulations are performed at various ambient temperatures (800–1100 K) and various volume fractions of ambient oxygen (13–21%) that correspond to conditions in both conventional and advanced diesel engines. The trend towards decreasing ignition delay time and lift-off length with increasing ambient temperature and oxygen is predicted well. The quantitative agreement between the computed and experimental ignition delay times is satisfactory. The accuracy of lift-off length predictions is less accurate but comparable to the existing literature. Better results are obtained at the conditions with lower ambient temperatures and oxygen concentrations. This outcome is explored with a detailed analysis of heat release and scalar dissipation rates under various ambient temperature conditions. It is revealed that at high ambient temperatures, flame stabilisation occurs in a region with significant turbulence–chemistry interactions and close to the nozzle exit where the liquid phase would be expected to influence the flame.

Eco-optimisation of Goods Supply by Road Transport: From Logistic Requirements Via Freight Transport Cycles to Efficiency-maximised Vehicle Powertrains

Currently, only a small minority of commercial vehicles on the market are fitted with alternative powertrain systems, and they are mostly of the heavy-duty type. The “alternative” components required (in particular batteries) make these utility vehicles rather expensive for fleet operators. The return on investment seems to be still out of reach. Hence, it is necessary to cut down on operational costs. Given these facts, the starting point was to clarify the criteria of logistic services as needed by the customers. First and foremost this concerns the type of vehicle chosen for a given logistic task. Secondly, concern needs to be given to the factors which influence the dynamics of vehicle movements, such as the load factor in terms of the geographical sequence of the points of deliveries. Thirdly, the time windows available for delivery affect variations in the velocity dependent on the respective level of service of the traffic flow. This opens up some additional potential for optimisation aside from vehicle technology. Road network planning and traffic management can boost low-emission freight services by taking into consideration the performance of different powertrain systems.The object was to quantify effects of innovative powertrain technologies on freight transport fleets with respect to reducing energy consumption and CO2 equivalent emissions. We identified representative logistic services as framework conditions of their operations in correlation with vehicle classes (light, medium and heavy). The vehicles use routes from the outskirts to the core of a conurbation and vice versa. The roads used are defined in categories which allow estimates of their capacity to handle variable traffic flows depending on the time of the day. These boundary conditions were used for a comprehensive comparison (based on numerical simulations) of advanced powertrain systems for such commercial vehicles. Particularly, fuel types as well as electricity were taken into account along with some variation in gross vehicle weights and hybrid configurations.The investigations were carried out for 32 different powertrain architectures such as advanced diesel and CNG engines, also as baselines for different hybrid variants and even pure battery-powered commercial vehicles. The results should be of interest for fleet operators, and our interpretations regarding further energy and emission reductions in goods supply processes challenges the entire future system of logistics, traffic management, infrastructure planning and powertrain technologies.

Combustion simulation of a 1.9 L turbo-charged diesel engine with detailed chemical kinetics model

To meet stringent emission and fuel consumption requirements, many auto companies have been developing advanced diesel engines. As a key virtual design verification tool in the loop of engine development, CFD can provide a deep insight into the physical processes in the cylinders. In this paper, combustion simulation of a common rail injection diesel engine is presented. Here different combustion chambers are investigated. The SAGE detailed chemistry kinetics model with multi-zone algorithm is used for the combustion simulation. A bench test of the 1.9 L turbocharged diesel engine was performed to verify the calculation results. The swirl ratio, in-cylinder temperature and heat release rates for different combustion chamber shapes, different engine operation conditions are compared. The evolution of fuel injection, flames and emissions are also studied. The simulation results and test data show good correlation.

Effects of Real-Fluid Thermodynamics on High-Pressure Fuel Injection Processes

This paper first summarizes a new theoretical description that quantifies the ef fects of real-fluid thermodynamics on liquid fuel injection processes as a function of pressure at typical engine operating conditions. It then focuses on the implications this has on modeling such flows with emphasis on application of the Large Eddy Simulation (LES) technique. The theory explains and quantifies the major differences that occur in the jet dynamics compared to that described by classical spray theory in a manner consistent with experimental observations. In particular, the classical view of spray atomization as an appropriate model at some engine operating conditions is questionable. Instead, non-ideal real-fluid behavior must be taken into account using a multicomponent formulation that applies to hydrocarbon mixtures at high-pressure supercritical conditions. To highlight the implications and needs related to modeling, we present a series of studies using LES that focus on experiments being conducted in the high-pressure combustion vessel at Sandia National Laboratories. We extend LES studies performed previously to the Engine Combustion Network (www.sandia.gov/ECN) Spray-H and Spray-A injectors using n-heptane and n-dodecane as the respective fuels. The accompanying analysis reveals the structural characteristics associated with the inherent scalar mixing processes at conditions directly relevant to advanced Diesel engines.

Observer design for nonlinear parameter‐varying systems: Application to diesel engines

SummaryThis paper deals with the problem of designing a nonlinear observer for diesel engines. The goal is to estimate the masses entering the cylinders and the inlet and exhaust pressures. To achieve this, the considered model subject to disturbances contains linear parameter‐varying part and nonlinear part having a large Lipschitz constant. The H ∞ criterion is used to reject the disturbances. Besides, the modified mean value theorem is applied to express the nonlinear error dynamics as a convex combination of known matrices with time‐varying coefficients. The sufficient conditions are derived and given in terms of linear matrix inequality. The advantage of the proposed method is that it can be applied to a wider class of nonlinear systems, particulary our case: diesel engines. The proposed approach is tested and evaluated using an advanced diesel engine professional simulator AMEsim (LMS International, Leuven, Belgium). Copyright © 2014 John Wiley & Sons, Ltd.

A Control-Oriented Model for Dynamics From Fuel Injection Profile to Intake Gas Conditions in Diesel Engines

Fuel injection profile variations play a critical role in advanced combustion mode control for diesel engines and also possess control authorities on engine in-cylinder conditions (ICCs). In order to systematically utilize the active fueling control, in conjunction with air-path control, for transient operations of advanced multimode combustion diesel engines, this paper presents a physics-based, control-oriented model that describes the inherent dynamics from fuel injection profile variations to the intake gas conditions. To show the effectiveness of the developed control-oriented model, comparisons were made with the simulation results from a high-fidelity GT-Power computational engine model as well as the experimental data acquired on a medium-duty diesel engine during transient operations.

Control of diesel engine dual-loop EGR air-path systems by a singular perturbation method

This paper presents a singular perturbation based method for controlling the dual-loop exhaust gas recirculation (DL-EGR) air-path systems on advanced diesel engines. A DL-EGR air-path system, consisting of a high-pressure loop EGR (HPL-EGR) and a low-pressure loop EGR (LPL-EGR), has significantly different time-scales (fast and slow) due to the inherent difference in the HPL-EGR’s and LPL-EGR’s corresponding control volumes. Such a feature of the DL-EGR systems makes the cooperative control of intake manifold gas conditions challenging. By considering the DL-EGR air-path system as a singularly perturbed system, a composite control law was devised to achieve systematic control of the air-path conditions including gas pressure, temperature, and oxygen fraction in the intake manifold. The effectiveness of the control method is experimentally evaluated on a medium-duty diesel engine.

Characterization of the effect of fatty ester composition on the ignition behavior of biodiesel fuel sprays

The effect of fatty ester composition on the combustion behavior of biodiesel fuel sprays is investigated for soy-based methyl esters, canola-based methyl esters and canola-based butyl esters. The purpose of this study is to aid fuel engineering efforts by identifying molecular structure features of biodiesel which can influence the compression ignition process during direct biodiesel utilization in diesel engines. Combustion behavior is classified through ignition delays and maximum apparent heat release rates measured in a rapid compression machine, and these measurements have been taken at the low temperatures (676–815K) and reduced oxygen concentrations (12% and 18%) corresponding to the low temperature combustion regime of advanced diesel engines. Ignition delay measurements show that the appearance of first heat release from the fuels is decreasingly sensitive to oxygen concentration as the reaction zone temperature is increased. Growth in the ester alkoxy chain length from one to four carbon atoms had minimal effect on the ignition delay. For tests in 12% oxygen, the increased polyunsaturated of soy methyl esters relative to canola methyl esters leads to longer ignition delays. This is not observed using 18% oxygen where physical transport processes are more important. The canola butyl esters exhibited the largest peak values for heat release rates, with the distinction becoming clear at reaction zone temperatures above 750K. Normalization on ignition delay and input energy bases indicates that variation of the maximum apparent heat release rates among the fuels is primarily due to unique mixing times and fuel heating values.

Fault Tolerant Control of Internal Combustion Engine subject to Intake Manifold Leakage

In this paper, a new FTC strategy of the diesel engine air path subject to intake manifold leakage described by Takagi-Sugeno model is presented. The proposed FTC design scheme integrates the state estimation, the leakage identification and the state feedback control law, to guaranty the stabilization of the faulty plant. State vector and leakage are estimated by an adaptive observer. The gains of the adaptive observer and feedback control law are obtained by solving a linear matrix inequality derived from the Lyapunov theory. The effectiveness and performances of the proposed approach are illustrated using the professional advanced diesel engine simulator AMEsim(LMS) platform in co-simulation with SIMULINK software.

Multi-Functional Reactor for Advanced Diesel Engine Emission Control

Advanced Diesel engine technologies employ Low Temperature Combustion (LTC) to offer substantial advantages to the reduction of NOx and Particulate Matter (PM) emissions but will most probably not succeed to make the application of Diesel Particulate Filters (DPFs) dispensable in the future. In this work the research and development efforts for the realization of a Multi-Functional catalyst Reactor (MFR) for the exhaust of the upcoming diesel engines is presented. This work is based on recent advances in catalytic nano-structured materials synthesis and coating techniques. Different gaseous and soot oxidation catalytic functionalities have been carefully distributed in the filter substrate microstructure and a novel filter design has been applied to enable internal heat recovery capability by the implementation of heat exchange between the outlet and the inlet to the filter flow paths. MFR prototypes, suitable for the abatement of both gaseous and PM emissions of the LTC engine operation, have been realized. The evaluation results of the MFR performance under both conventional and advanced combustion engine operating conditions are presented.

Physically based volumetric efficiency model for diesel engines utilizing variable intake valve actuation

Advanced diesel engine architectures employing flexible valve trains enable emissions reductions and fuel economy improvements. Flexibility in the valve train allows engine designers to optimize the gas exchange process in a manner similar to how common rail fuel injection systems enable optimization of the fuel injection process. Modulating valve timings directly impacts the volumetric efficiency of the engine since it directly controls how much mass is trapped in the cylinders. In fact, it will be shown that the control authority of valve timing modulation over volumetric efficiency, that is, the range of volumetric efficiencies achievable due to modulation of the valve timing, is three times larger than the range achievable by modulation of other engine actuators such as the exhaust gas recirculation valve or the variable geometry turbocharger. Traditional empirical or regression-based models for volumetric efficiency, while suitable for conventional valve trains, are therefore challenged by flexible valve trains. The added complexity and additional empirical data needed for wide valve timing ranges limit the usefulness of these methods. A simple physically based volumetric efficiency model was developed to address these challenges. The model captures the major physical processes occurring over the intake stroke, and is applicable to both conventional and flexible intake valve trains. The model inputs include temperature and pressure in both the intake and exhaust manifolds, intake and exhaust valve event timings, engine cylinder bore, stroke, connecting rod lengths, engine speed, and effective compression ratio. The model is physically based, requires no regression tuning parameters, is generalizable to other engine platforms, and has been experimentally validated using an advanced multi-cylinder diesel engine equipped with a fully flexible variable intake valve actuation system. Experimental data were collected over a wide range of the operating space of the engine and augmented with air handling actuator and intake valve timing sweeps to maximize the range of conditions used to thoroughly experimentally validate the model for a total of 286 operating conditions. The physically based volumetric efficiency model will be shown to predict the experimentally calculated volumetric efficiency to within 5 per cent for all cases with a root mean square error of less than 2.5 per cent for the entire dataset. The physical model developed differs from previous physical modelling work through the novel application of effective compression ratio, incorporation of no tuning parameters, and extensive validation on a unique engine test bed with fully flexible intake valve actuation.

Ignition Characteristics of Diesel and Canola Biodiesel Sprays in the Low-Temperature Combustion Regime

The objective of this work is to investigate the spray ignition characteristics of diesel and canola-derived biodiesel in a rapid compression machine at the low temperatures (676–816 K) and reduced oxygen concentrations (12 and 18%) that are used in low-temperature combustion strategies of advanced diesel engines. A method for testing ignition delay times and apparent heat release rates at a series of temperatures is developed and characterized, whereby a given temperature is attained prior to the fuel spray by altering the charge cooling time after the end of compression. A single-zone heat release model is formulated and used with the experimental pressure data to calculate two unique ignition delay periods. For diesel, the total ignition delays measured with this approach are found to correlate very well with diesel ignition delay data published in the literature. When the first ignition delay period is compared, which approximates the initial time of heat release after the start of injection, it is no...

Surrogate Model Development for Fuels for Advanced Combustion Engines

The fuels used in internal-combustion engines are complex mixtures of a multitude of different types of hydrocarbon species. Attempting numerical simulations of combustion of real fuels with all of the hydrocarbon species included is highly unrealistic. Thus, a surrogate model approach is generally adopted, which involves choosing a few representative hydrocarbon species whose overall behavior mimics the characteristics of the target fuel. The present study proposes surrogate models for the nine fuels for advanced combustion engines (FACE) that have been developed for studying low-emission, high-efficiency advanced diesel engine concepts. The surrogate compositions for the fuels are arrived at by simulating their distillation profiles to within a maximum absolute error of ∼4% using a discrete multi-component (DMC) fuel model that has been incorporated in the multi-dimensional computational fluid dynamics (CFD) code, KIVA-ERC-CHEMKIN. The simulated surrogate compositions cover the range and measured concen...

Low NOx and Low Smoke Operation of a Diesel Engine Using Gasolinelike Fuels

Much of the technology in advanced diesel engines, such as high injection pressures, is aimed at overcoming the short ignition delay of conventional diesel fuels to promote premixed combustion in order to reduce NOx and smoke. Previous work in a 2 l single-cylinder diesel engine with a compression ratio of 14 has demonstrated that gasoline fuel, because of its high ignition delay, is very beneficial for premixed compression-ignition compared with a conventional diesel fuel. We have now done similar studies in a smaller—0.537 l—single-cylinder diesel engine with a compression ratio of 15.8. The engine was run on three fuels of very different auto-ignition quality—a typical European diesel fuel with a cetane number (CN) of 56, a typical European gasoline of 95 RON and 85 MON with an estimated CN of 16 and another gasoline of 84 RON and 78 MON (estimated CN of 21). The previous results with gasoline were obtained only at 1200 rpm—here we compare the fuels also at 2000 rpm and 3000 rpm. At 1200 rpm, at low loads (∼4 bars indicated mean effective pressure (IMEP)) when smoke is negligible, NOx levels below 0.4 g/kWh can be easily attained with gasoline without using exhaust gas recirculation (EGR), while this is not possible with the 56 CN European diesel. At these loads, the maximum pressure-rise rate is also significantly lower for gasoline. At 2000 rpm, with 2 bars absolute intake pressure, NOx can be reduced below 0.4 g/kW h with negligible smoke (FSN<0.1) with gasoline between 10 bars and 12 bars IMEP using sufficient EGR, while this is not possible with the diesel fuel. At 3000 rpm, with the intake pressure at 2.4 bars absolute, NOx of 0.4 g/kW h with negligible smoke was attainable with gasoline at 13 bars IMEP. Hydrocarbon and CO emissions are higher for gasoline and will require after-treatment. High peak heat release rates can be alleviated using multiple injections. Large amounts of gasoline, unlike diesel, can be injected very early in the cycle without causing heat release during the compression stroke and this enables the heat release profile to be shaped.

Combustion and Fuel Technologies of Advanced Diesel Engine

Combustion and Fuel Technologies of Advanced Diesel Engine