A novel framework for enhancing marine dual fuel engines environmental and safety performance via digital twins

The Internet of Things (IoT) advent and digitalisation has enabled the effective application of the digital twins (DT) in various industries, including shipping, with expected benefits on the systems safety, efficiency and environmental footprint. The present research study establishes a novel framework that aims to optimise the marine DF engines performance-emissions trade-offs and enhance their safety, whilst delineating the involved interactions and their effect on the performance and safety. The framework employs a DT, which integrates a thermodynamic engine model along with control function and safety systems modelling. The DT was developed in GT-ISE© environment. Both the gas and diesel operating modes are investigated under steady state and transient conditions. The engine layout is modified to include Exhaust Gas Recirculation (EGR) and Air Bypass (ABP) systems for ensuring compliance with ‘Tier III’ emissions requirements. The optimal DF engine settings as well as the EGR/ABP systems settings for optimal engine efficiency and reduced emissions are identified in both gas and diesel modes, by employing a combination of optimisation techniques including multi-objective genetic algorithms (MOGA) and Design of Experiments (DoE) parametric runs. This study addresses safety by developing an intelligent engine monitoring and advanced faults/failure diagnostics systems, which evaluates the sensors measurements uncertainty. A Failure Mode Effects and Analysis (FMEA) is employed to identify the engine safety critical components, which are used to specify operating scenarios for detailed investigation with the developed DT. The integrated DT is further expanded, by establishing a Faulty Operation Simulator (FOS) to simulate the FMEA scenarios and assess the engine safety implications. Furthermore, an Engine Diagnostics System (EDS) is developed, which offers intelligent engine monitoring, advanced diagnostics and profound corrective actions. This is accomplished by developing and employing a Data-Driven (DD) model based on Neural Networks (NN), along with logic controls, all incorporated in the EDS. Lastly, the manufacturer’s and proposed engine control systems are combined to form an innovative Unified Digital System (UDS), which is also included in the DT. The analysis of marine (DF) engines with the use of an innovative DT, as presented herein, is paving the way towards smart shipping.The Internet of Things (IoT) advent and digitalisation has enabled the effective application of the digital twins (DT) in various industries, including shipping, with expected benefits on the systems safety, efficiency and environmental footprint. The present research study establishes a novel framework that aims to optimise the marine DF engines performance-emissions trade-offs and enhance their safety, whilst delineating the involved interactions and their effect on the performance and safety. The framework employs a DT, which integrates a thermodynamic engine model along with control function and safety systems modelling. The DT was developed in GT-ISE© environment. Both the gas and diesel operating modes are investigated under steady state and transient conditions. The engine layout is modified to include Exhaust Gas Recirculation (EGR) and Air Bypass (ABP) systems for ensuring compliance with ‘Tier III’ emissions requirements. The optimal DF engine settings as well as the EGR/ABP systems settings for optimal engine efficiency and reduced emissions are identified in both gas and diesel modes, by employing a combination of optimisation techniques including multi-objective genetic algorithms (MOGA) and Design of Experiments (DoE) parametric runs. This study addresses safety by developing an intelligent engine monitoring and advanced faults/failure diagnostics systems, which evaluates the sensors measurements uncertainty. A Failure Mode Effects and Analysis (FMEA) is employed to identify the engine safety critical components, which are used to specify operating scenarios for detailed investigation with the developed DT. The integrated DT is further expanded, by establishing a Faulty Operation Simulator (FOS) to simulate the FMEA scenarios and assess the engine safety implications. Furthermore, an Engine Diagnostics System (EDS) is developed, which offers intelligent engine monitoring, advanced diagnostics and profound corrective actions. This is accomplished by developing and employing a Data-Driven (DD) model based on Neural Networks (NN), along with logic controls, all incorporated in the EDS. Lastly, the manufacturer’s and proposed engine control systems are combined to form an innovative Unified Digital System (UDS), which is also included in the DT. The analysis of marine (DF) engines with the use of an innovative DT, as presented herein, is paving the way towards smart shipping

Modeling and experimental analysis of exhaust gas temperature and misfire in a converted-diesel homogeneous charge compression ignittion engine fuelled with ethanol

Homogeneous charge compression ignition (HCCI) and the exploitation of ethanol as an alternative fuel is one way to explore new frontiers of internal combustion engines with an objective towards maintaining its sustainability. Here, a 0.3 liter singlecylinder direct-injection diesel engine was converted to operate on the alternative mode with the inclusion of ethanol fuelling and intake air preheating systems. The main HCCI engines parameters such as indicated mean effective pressure, maximum in-cylinder pressure, heat release, in-cylinder temperature and combustion parameters, start of combustion, 50% of mass fuel burnt (CA50) and burn duration were acquired for 100 operating conditions. They were used to study the effect of varying input parameters such as equivalence ratio and intake air temperature on exhaust gas emission, temperature and ethanol combustion, experimentally and numerically. The study primarily focused on HCCI exhaust gas temperature and understanding and detecting misfire in an ethanol fuelled HCCI engine, thus highlighting the advantages and drawbacks of using ethanol fuelled HCCI. The analysis of experimental data was used to understand how misfire affects HCCI engine operation. A model-based misfire detection technique was developed for HCCI engines and the validity of the obtained model was then verified with experimental data for a wide range of misfire and normal operating conditions. The misfire detection is computationally efficient and it can be readily used to detect misfire in HCCI engine. The results of the misfire detection model are very promising from the viewpoints of further controlling and improving combustion in HCCI engines

Ion current sensing for controlled auto ignition in internal combustion engines

Envirom-nental pollution is a subject that needs urgent addressing. Since the internal combustion engine has its fair share of accountability on this, research on techniques for increasing engine efficiency and emissions is necessary. Controlled Auto Ignition is a promising combustion mode, which increases fuel efficiency while also reducing NOx emissions to negligible levels. This Thesis concentrates on the implementation of this mode through experimental research, on an engine equipped with a fully variable valvetrain. Investigation of the operational window, emissions, fuel consumption, thermodynamic efficiency is carried out and ways to improve on these are discussed. The governing consideration, however, is the control method for this rather intricate combustion mode. As such, experimental data acquisition and analysis of ion current under the whole operating spectrum, from spark ignition to full autoignition is made. It is found that the expected gains in fuel consumption and emissions are realized. In addition, ion current proves to be a very powerful and cost effective tool for engine monitoring, diagnosis and control. The author concludes that Controlled Auto Ignition is a viable proposition for mass production engine designs and that ion current, although not absolutely vital for engine control, considerably increases engine control thus allowing for greater operating window under autoignition, without compromising reliability or cost.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Investigation of combustion and performance characteristics of CAI combustion engine with positive and negative valve overlap

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.In the first part of studies, Controlled Auto-Ignition (CAI) combustion was investigated in a Ricardo E6 single cylinder, four stroke gasoline engine. CAI combustion is achieved by employing positive valve overlap configuration in combination with various compression ratios and intake air temperature strategies. The CAI operational region is limited by engine load due to knock and partial burned boundaries. The combustion characteristics and emissions are studied in order to understand the major advantages and drawbacks of CAI combustion with positive valve overlap. The enlargement of the CAI operational region is obtained by boosting intake air and external EGR. The lean-boosted operation elevators the range of CAI combustion to the higher load region, and the use of external EGR allows the engine to operation with CAI combustion in the mid range of region between boosted and N/A CAI operational range. The results are analyzed and combustion characteristics, performance and emissions are investigated. A Ricardo Hydra single cylinder, four stroke optical gasoline engine with optical access is then experimented to investigate CAI combustion through negative valve overlap configuration and an intake heater. The effects of direct fuel injection timings spark timings and air/fuel ratio are studied by means of simultaneous incylinder heat release study and direct visualization, chemiluminescence techniques which uses full, OH radical and CHO species. Both heat release analysis and chemiluminescence results have identified the pressure of minor combustion during the NVO period. Both the charge cooling and local air/fuel ratio effects are also investigated by varying the quantity of direct air injection

Experimental study of a Miller cycle based approach for an efficient boosted downsized gasoline Di engine

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonDriven by the strict fuel consumption and CO2 legislations in Europe and many countries, various technologies have been developed to improve the fuel economy of conventional internal combustion engines. Gasoline engine downsizing has become a popular and effective approach to reduce fleet CO2 emissions of passenger cars. This is typically achieved in the form of boosted direct injection gasoline engines equipped with variable valve timing devices. Downsized gasoline engines reduce vehicle fuel consumption by making engine operate more at higher load to reduce pumping losses and also through reducing total engine friction losses. However, their compression ratio (CR) and efficiency are constrained by knocking combustion as well as the low speed pre-ignition phenomena. Miller cycle is typically achieved in an engine with reduced effective CR through Early Intake Valve Closure (EIVC) or Later Intake Valve Closure (LIVC). This technology has been adopted on modern gasoline engines to reduce in-cylinder charge temperature and enable a higher geometric CR to be used for better fuel economy. The present work investigated the effectiveness and underlying process of a Miller cycle based approach for improving fuel consumption of a boosted downsized gasoline engine. A single cylinder direct injection gasoline engine and the testing facilities were set up and used for extensive engine experiments. Both EIVC and LIVC approaches were tested and compared to the conventional Otto cycle operation with a standard cam profile. Synergy between Miller cycle valve timings and different valve overlap period was analysed. Two pistons with different CRs were used in the Miller cycle engine testing to enable its full potential to be evaluated. The experimental study was carried out in a large engine operation area from idle to up to 4000rpm and 25.6bar NIMEP to determine the optimal Miller cycle strategy for improved engine fuel economy in real applications. In addition, the increased exhaust back pressure and friction losses corresponding to real world boosting devices were calculated to evaluate Miller cycle benefits at high loads in a production engine. The results have shown that EIVC combined with high CR can offer up to 11% reduction of fuel consumption in a downsized gasoline engine with simple setup and control strategy. At the end, this thesis presents an Miller cycle based approach for maximising fuel conversion efficiency of a gasoline engine by combining three-stage cam profiles switching and two-stage variable compression ratio

Stochastic Analysis and Control of EGR-Diluted Combustion in Spark Ignition Engines at Nominal and Misfire-Limited Conditions

Worldwide regulations on greenhouse gas emissions demand a reduction in fuel consumption from the transportation sector. This reduction requires incremental improvements in engine and powertrain efficiency. Feedback combustion control under diluted conditions with exhaust gas recirculation (EGR) has the potential to improve the overall efficiency of spark-ignition engines by optimizing combustion efficiency, reducing heat transfer losses, and reducing pumping losses at medium loads. This control problem requires the coordinated action of the EGR valve and the spark advance. However, cycle-to-cycle variability in the combustion process limits the closed-loop system performance. Moreover, the input-to-output coupling between the actuators and measured combustion features need to be addressed in the control design to avoid undesired combustion events such as knock, partially burned cycles, and misfires. Therefore, the combustion control problem at high EGR-diluted conditions is a constrained multivariable stochastic control problem. This dissertation focuses on the control of the spark advance and the EGR valve in order to maximize the EGR benefits while maintaining stable combustion during steady state and load transients. For a fixed engine speed/load condition, a two-input two-output discrete-time dynamic system was derived from system identification in order to use model-based control techniques. In particular, a linear quadratic Gaussian (LQG) controller was designed and experimentally tested for controlling spark and EGR valve. Such a controller was able to achieve an optimal combustion shape that maximizes EGR benefits and proved to be superior compared to traditional proportional-integral (PI) control strategies. An analytic solution for the amount of variability that the LQG controller contributes during closed-loop operation was derived, which can be used to modify the combustion targets to avoid misfire events. Given that sporadic misfires can occur when the control targets high levels of EGR, a stochastic controller based on the likelihood ratio test has been proposed to adjust the likelihood of misfires. When the engine speed is fixed and the load demand is controlled by the driver, the feedback combustion controller needs to react to such disturbance and maintain an optimal phasing. A physics-based model derived from manifold filling dynamics was coupled with a simple combustion model to formulate a three-input two-output dynamic system that considers not only the impact of the EGR valve and spark advance on the combustion, but also considers throttle tip-in and tip-out commands. The retuned LQG controller was experimentally tested and successfully maintained optimal phasing and maximized EGR levels during tip-in commands. However, during throttle tip-outs the system transitions through conditions where misfires occur. An explicit reference governor was designed to slow down the tip-out commands in order to avoid fast transitions that drive the system over the misfire limit. Given the inability to model misfires accurately, the reference governor was enhanced with model-free learning which enabled it to avoid misfires over time. Experimental results showed that successful misfire avoidance can be achieved in exchange for a slower tip-out response. It is suggested that such combustion control strategies can be paired with modern mild or full hybrid powertrain architectures to fully utilize the advantages of combustion control at high dilution levels.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/153464/1/bryanpm_1.pd

Ultralean combustion in general aviation piston engines

The role of ultralean combustion in achieving fuel economy in general aviation piston engines was investigated. The aircraft internal combustion engine was reviewed with regard to general aviation requirements, engine thermodynamics and systems. Factors affecting fuel economy such as those connected with an ideal leanout to near the gasoline lean flammability limit (ultralean operation) were analyzed. A Lycoming T10-541E engine was tested in that program (both in the test cell and in flight). Test results indicate that hydrogen addition is not necessary to operate the engine ultralean. A 17 percent improvement in fuel economy was demonstrated in flight with the Beechcraft Duke B60 by simply leaning the engine at constant cruiser power and adjusting the ignition for best timing. No detonation was encountered, and a 25,000 ft ceiling was available. Engine roughness was shown to be the limiting factor in the leanout

Experimental studies of performance and emissions in a 2/4-stroke engine

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityDirect Injection (DI) gasoline engines are staging a come-back because of its potential for improved fuel economy through principally the engine down-sizing by boosting, stratified charge combustion and Controlled Auto Ignition (CAI) at part load operations. The problem with the Spark Ignition (SI) engine is its inherent low part-load efficiency. This arises due to the pumping loses that occur when the throttle closes or partially opens. One way of decreasing the pumping losses is to operate the engine lean or by adding residual gases. It is not possible to operate the engine unthrottled with a very lean or diluted mixture at low loads due to misfire. However, the load can also be controlled by changing the valve timing. This reduce the pumping loses and hence increase the efficiency. 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. This causes a significant increase in Particulate Matter (PM) emissions from direct injection gasoline engines compared to the conventional port fuel injection gasoline engines, which are of major concern because of its health implications. In the meantime, depleting reserves of fossil fuels and the increasing environmental pollution caused by burning of fossil fuels, have paved the way for fuel diversification. Cleaner and renewable fuel is being introduced worldwide. The use of ethanol as an alternative transportation fuel shows promise for several reasons. While ethanol can be produced from several types of biomass, it offers properties such as high octane number, higher oxygen content and high heat of evaporation, which make it a most attractive alternative fuel, in particular for the direct injection gasoline engine. In this research, a single cylinder camless engine equipped with an electro-hydraulic valve train system has been used to study and compare different engine operation modes in the SI and CAI combustion. The fuel consumption, gaseous and particulate emissions of gasoline and its mixture with ethanol (E15 and E85) were measured and analysed at the same engine operating condition. The heat release analysis and performance characteristics of CAI and SI combustion were carried out by the in-cylinder pressure measurement. The effect of load and valve timings on the gaseous and Particulate Matter (PM) emissions was investigated for both 4-stroke SI and CAI combustion. Within the achieved CAI operational ranges, particle emissions were found to be dominated by smaller particles (<50nm). Hotter charge and better mixing are the main parameters affecting the soot particles in the exhaust irrespective of the combustion modes and valve timings. At part-load conditions investigated, it was found that the CAI combustion produced the lowest NOx emissions of 0.4g/KWh in all fuel blends and lower fuel consumption 223g/KWh with improved combustion efficiency of 94.7% in ethanol fuel E15 and E85. The positive valve overlap was found to produce lowest fuel consumption of 222.8 g/KWh in all fuel blend and respond better to ethanol fuel in E15 and E85 with improved indicated efficiency of 40.5% compared to the other modes investigated. The early intake valve throttled SI operation led to a moderate improvement in the fuel consumption of 243.5g/KWh over the throttled SI operation but it was characterised by the slowest combustion and highest CO (33.5g/KWh) and HC (16.8g/KWh) emissions . Less and smaller particles numbers were detected for Early Intake Valve Closure (EIVC) from the combustion of E0 and E15 (4.0E+07#/cm3 less than 50nm in diameter) fuel blends. The particulate emission results showed that soot was the dominant particles in the exhaust, which could be reduced by leaner mixture combustion .Tertiary Education Trust Fund and University of Portharcourt Nigeri

Fuel effects in homogeneous charge compression ignition (HCCI) engines

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2009.Includes bibliographical references (p. 209-217).Homogenous-charge, compression-ignition (HCCI) combustion is a new method of burning fuel in internal combustion (IC) engines. In an HCCI engine, the fuel and air are premixed prior to combustion, like in a spark-ignition (SI) engine. However, rather than using a spark to initiate combustion, the mixture is ignited through compression only, as in a compression-ignition (CI) engine; this makes combustion in HCCI engines much more sensitive to fuel chemistry than in traditional IC engines. The union of SI- and CI-technologies gives HCCI engines substantial efficiency and emissions advantages. However, one major challenge preventing significant commercialization of HCCI technology is its small operating range compared to traditional IC engines. This project examined the effects of fuel chemistry on the size of the HCCI operating region, with an emphasis on the low-load limit (LLL) of HCCI operability. If commercialized, HCCI engines will have to operate using standard commercial fuels. Therefore investigating the impact of fuel chemistry variations in commercial gasolines on the HCCI operability limits is critical to determining the fate of HCCI commercialization. To examine these effects, the operating ranges of 12 gasolines were mapped in a naturally-aspirated, single-cylinder HCCI engine, which used negative valve overlap to induce HCCI combustion. The fuels were blended from commercial refinery streams to span the range of market-typical variability in aromatic, ethanol, and olefin concentrations, RON, and volatility. The results indicated that all fuels achieved nearly equal operating ranges. The LLL of HCCI operability was completely insensitive to fuel chemistry, within experimental measurement error. The high-load limit showed minor fuel effects, but the trends in fuel performance were not consistent across all the speeds studied. These results suggest that fuel sensitivity is not an obstacle to auto-makers and/or fuel companies to introducing HCCI technology.(cont.) Developing an understanding of what causes an HCCI engine to misfire allows for estimation of how fuel chemistry and engine operating conditions affect the LLL. The underlying physics of a misfire were studied with an HCCI simulation tool (MITES), which used detailed chemical kinetics to model the combustion process. MITES was used to establish the minimum ignition temperature (Tmisfire) and full-cycle, steady-state temperature (Tss) for a fuel as a function of residual fraction. Comparison of Tmisfire and Tss near the misfire limit showed that Tss approaches Tmisfire quite closely (to within ~ 14 K), suggesting that the primary cause of a misfire is insufficient thermal energy needed to sustain combustion for multiple cycles. With this relationship, the effects of engine speed and fuel chemistry on the LLL were examined. Reducing the engine speed caused a reduction in T, which allowed fuel chemistry effects to be more apparent. This effect was also observed experimentally with 2 primary reference fuels (PRFs): PRF60 and PRF90. At 1000 RPM, PRF60 obtained a substantially lower (~30%) LLL than PRF90, but at speeds >/= 1500 RPM, fuel ignitability had no effect on the LLL. Fuel chemistry was shown to influence the LLL by increasing both Tmisfire and Tss for more auto-ignition resistant fuels. However, the extent to which fuel chemistry affects these temperatures may not be equivalent. Therefore, the relative movement of each temperature determines the extent to which fuel chemistry impacts the LLL.by John P. Angelos.Ph.D

New approaches for optical and microoptical diagnostics in IC engines

The development of modern engine concepts like spray-guided spark-ignition direct injection (SG-SIDI) or homogeneous charge compression ignition (HCCI) requires fast, non-invasive in-situ diagnostics methods. Hence, laser-based optical diagnostics are essential for internal combustion (IC) engine research. Within this work, microoptical systems that enable the ap-plication of optical diagnostics methods on unmodified production-line engines or engines with micro-invasive optical access were designed, characterized and realized in a joint project collaborating with the Institut für Technische Optik (ITO) at the University of Stuttgart. These microoptical systems include a fiber-optic spark-plug sensor and an endoscopic UV imaging system. The used optical diagnostics are based on laser-induced fluorescence (LIF) of the fuel tracers toluene and 3-pentanone. The respective total fluorescence signal and its spectral dis-tribution yield information about temperature, pressure and mixture composition (i.e. fuel/air-equivalence ratios). The fiber-optic spark plug is designed to perform LIF measure-ments in a defined small probe volume (~2 mm³) close to the spark gap. Its ignition function is fully maintained. With the spark-plug sensor fuel LIF was measured in a commercial IC en-gine. The hybrid UV endoscope (combining refractive and diffractive optical elements) has an about ten times better light collection efficiency than a commercial UV endoscope with simul-taneous high spatial resolution over a broadband spectral range. Its performance is demon-strated in various experiments. Microoptics for the generation of lightsheets and excitation beam patterns are also presented. For a quantitative application of tracer-LIF diagnostics a comprehensive knowledge of the photophysical properties of the used tracers is essential. As a contribution to this photophysical characterization, within this work, tracer-LIF lifetimes were measured via TCSPC (time-correlated single-photon counting) with unprecedented time resolution. The measured bi-exponential decay for toluene LIF could validate the prevailing model. Before the microoptical systems were finished, two experiments in optical single-cylinder engines were conducted with commercial lenses and a simple commercial fiber-optic spark plug. In an air-guided system the fuel distribution and its temporal evolution close to the spark gap were measured with 3-pentanone-LIF and CN* spark-emission spectroscopy simultaneously. In a spray-guided SIDI engine the interaction between the fuel spray and the spark was measured and the spray induced stretching of the spark was observed