Dissertations / Theses on the topic 'Engine turbocharging'

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 151-156).
Turbocharging can provide a cost-effective means for increasing the power output and fuel economy of an internal combustion engine. It is commonly used on multi-cylinder engines, but not on commercial single-cylinder engines due to the phase mismatch between the exhaust stroke (when the turbocharger is powered) and the intake stroke (when the engine requires the compressed air). This work explores overcoming the phase mismatch problem by adding an air capacitor: a volume added in series with the intake manifold between the turbocharger compressor and the engine intake. The function of the air capacitor is to buffer the output from the turbocharger compressor and deliver pressurized air during the intake stroke. This research focuses on demonstrating the feasibility of using an air capacitor to enable turbocharging single cylinder internal combustion engines. An analytical model of the system was created from first principles, which showed that the air capacitor turbocharging method could increase power output by up to 40% without heat transfer and up to 70% with heat transfer elements included in the intake manifold (such as an intercooler). An initial, proof-of-concept experiment was created using a generator as a dynamometer. With an air capacitor volume seven times the engine capacity, this setup was able to produce 29% more power compared to the same engine naturally aspirated. A numerical model was developed in Ricardo Wave to predict the performance of turbocharged single cylinder engines with air capacitors under different conditions. An experimental engine with accompanying dynamometer was constructed to demonstrate the effects of manifold sizing on engine performance and to experimentally validate the model. The experiment showed that the model was able to predict power output with an accuracy of 8% of peak power, fuel consumption within 7% error, air mass flow rates with 10% error, and manifold pressures within 7% error. The model was then combined with a simulated annealing optimization scheme in Matlab in order to conceptualize designs for the geometry and timings of single-cylinder turbocharged engines intended for different commercial applications. The optimization showed that adding an air capacitor and turbocharger to a 0.44L engine, with slight modifications to the valve and injector timings, could increase power by 88% compared to natural aspiration. By also modifying the bore and stroke, the turbocharged engine with an air capacitor could reduce fuel consumption by 8% compared to a naturally aspirated engine with equivalent peak power output.
by Michael Buchman.
Ph. D.

Growing concerns about interruption to oil supply and oil shortages have led to escalating global oil prices. In addition, increased public acceptance of the global warming problem has prompted car manufacturers to agree to carbon emission targets in many regions including most recently, the Californian standards. Other legislating bodies are sure to follow this lead with increasingly stringent targets. As a result of these issues, spark ignition engines in their current form will need significant improvements to meet future requirements. One technically feasible option is smaller capacity downsized engines with enhanced power that could be used in the near term to reduce both carbon emissions and fuel consumption in passenger vehicles.This research focuses on exploring the performance limits of a 0.43 liter spark ignited engine and defining its operating boundaries. Limiting factors such as combustion, gas exchange and component design are investigated to determine if they restrict small engine performance. The research gives direction to the development of smaller gasoline engines and establishes the extent to which they can contribute to future powertrain fuel consumption reduction whilst maintaining engine power at European intermediate class requirements.

This thesis reports original research on a novel internal combustion (IC) engine charge air system concept called Turbo-Discharging. Turbo-Discharging depressurises the IC engine exhaust system so that the engine gas exchange pumping work is reduced, thereby reducing fuel consumption and CO2 emissions. There is growing concern regarding the human impact on the climate, part of which is attributable to motor vehicles and transport. Recent legislation has led manufacturers to improve the fuel economy and thus reduce the quantity of CO2 generated by their vehicles. As this legislation becomes more stringent manufacturers are looking to new and developing technologies to help further improve the fuel conversion efficiency of their vehicles. Turbo-Discharging is such a technology which benefits from the fact it uses commonly available engine components in a novel system arrangement. Thermodynamic and one-dimensional gas dynamics models and experimental testing on a 1.4 litre four cylinder four-stroke spark ignition gasoline passenger car engine have shown Turbo-Discharging to be an engine fuel conversion efficiency and performance enhancing technology. This is due to the reduction in pumping work through decreased exhaust system pressure, and the improved gas exchange process resulting in reduced residual gas fraction. Due to these benefits, engine fuel conversion efficiency improvements of up to 4% have been measured and increased fuel conversion efficiency can be realised over the majority of the engine operating speed and load map. This investigation also identified a measured improvement in engine torque over the whole engine speed range with a peak increase of 12%. Modelling studies identified that both fuel conversion efficiency and torque can be improved further by optimisation of the Turbo-Discharging system hardware beyond the limitations of the experimental engine test. The model predicted brake specific fuel consumption improvements of up to 16% at peak engine load compared to the engine in naturally aspirated form, and this increased to up to 24% when constraints imposed on the experimental engine test were removed.

This licentiate thesis deals mainly with modelling ofturbocharged SIengines. A model of a 4-cylinder engine was runin both steady state and transient conditions and the resultswere compared to measured data. Large differences betweenmeasurements and simulations were detected and the reasons forthis discrepancy were investigated. The investigation showedthat it was the turbocharger turbine model that performed in anon-optimal way. To cope with this, the turbine model containedparameters, which could be adjusted so that the model resultsmatched measured data. However, it was absolutely necessary tohave measured data to match against. It was thus concluded thatthe predictivity of the software tool was too poor to try topredict the performance of various boosting systems. Thereforemeans of improving the modelling procedure were investigated.To enable such an investigation a technique was developed tomeasure the instantaneous power output from, and efficiency of,the turbine when the turbocharger was used on the engine.

The project’s initial aim was to predict, throughsimulations, the best way to boost a downsized SI-engine with avery high boost-pressure demand. The first simulation run on astandard turbocharged engine showed that this could not be donewith any high accuracy. However, a literature study was madethat presents various different boosting techniques that canproduce higher boost pressure in a larger flow-range than asingle turbocharger, and in addition, with smallerboost-pressure lag.

Key words:boosting, turbocharging, supercharging,modelling, simulation, turbine, pulsating flow, unsteadyperformance, SI-engine, measurement accuracy

Engine boosting via turbocharging is a method to increase the engine power output with minimal or no increase in engine parasitic, frictional and pumping losses. Turbocharging in conjunction with engine down-sizing and down-speeding allows a reduction of engine fuel consumption, while maintaining a high engine power output. However, turbocharging introduces a lag in engine transient response, caused by the finite amount of time required by the turbocharger to accelerate, which has to be minimized. Electric turbocharger assistance consists of coupling an electric motor/generator to a standard turbocharger. The scope of the motor/generator is to increase the power available to accelerate the rotor assembly, so that the time to boost is reduced. The motor/generator could also be utilized to brake the turbocharger to control boost and avoid over-speeds, thus replacing the conventional waste-gate. Furthermore, electric assistance allows turbocompounding to be implemented. Turbocompounding improves the engine efficiency by utilizing the turbine and motor/generator to recuperate additional exhaust flow energy. In this thesis, the electric turbocharger assistance impact on the turbocharger and engine performance is studied. An electrically assisted turbocharger prototype has been developed by industrial partners and it has been tested by the author of this thesis. The performance of the turbocharger turbine and motor/generator has been characterized over the full speed range and the impact of the electric assistance on the turbine flow has been investigated experimentally. It has not been possible to characterize the turbine up to choking conditions, so the data has been extrapolated via a mean-line model. The performance data obtained has been utilized to generate a model of the assisted turbocharger, which has been coupled to a one-dimensional model of a non-highway 7-litre diesel engine. This model has been utilized to study the impact of electric turbocharger assistance on the engine transient performance. The electrical machine characterization revealed that the switched reluctance motor/generator operates efficiently up to a speed of 135,000 rev/min, making it one of the fastest running switched reluctance machines of this size. The peak machine efficiency is 93% (excluding the turbocharger bearing losses) and the maximum power output measured is 5.3 kW in generating mode and 4.3 kW in motoring mode. The motor/generator rotor aerodynamic drag loss has been calculated via computational fluid dynamics software and has been found to be 63 W at 140,000 rev/min. Via a novel experimental technique, it has been possible to characterize the turbocharger turbine down to an expansion ratio of 1.00. This experiment revealed that the mass flow rate drops to zero at an expansion ratio higher than unity and that below this critical pressure ratio the turbine flow is reversed. The characterization of the turbine during speed transients showed that the operating point on the performance map deviates from the quasi-steady line. This indicates that minor unsteady effects occur in the turbine and exhaust manifold flow. A further experiment revealed that the motor/generator torque oscillations have a negligible impact on the turbine performance. The engine simulations showed that the ideal electric assistance motoring power for this application is in the 5 to 10 kW range. A 5 kW machine reduces the engine speed drop, which occurs when the engine load is suddenly increased, by up to 83%, depending on the initial load and load step size, and reduces the time to recover the original speed by up to 86%. The simulations also revealed that electric assistance is more effective than the turbine variable geometry system in improving the engine transient response, but the variable geometry system is useful to optimize boost for engine specific fuel consumption over different engine loading conditions.

Aim of this diploma thesis is the modification of naturally aspirated engine for Formula Student competition to turbocharged version. Modification which were made are based on the issue knowledge and calculations. The input data were obtained from 3D scanning and measurements, at the school laboratories. All 3D models were created in Pro / Engineer. Input data for the computional analysis was developed in Lotus Engine Simulation. Computational analysis was performed in ANSYS by finite element method. Calculations had to simulate a piston behavior at the critical situations where the engine is under the maxiumum load.

Aim of this diploma thesis is the turbocharger design calculation for single cylinder SI engine for Formula Student. This thesis includes a mathematical model of the engine, which is created in the Lotus Engine Simulation. This model applies for tuning the regulation of turbocharger charging pressure. Lotus uses the turbine waste gate valve for this regulation. The results of the simulation are the charging pressure,lengths of the intake manifold and etc. These parameters ensure the optimal engine qualities. The knowlege and results of the simulations are summarized at the conclusion.

Driven 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.

Governments across the world are implementing legislation for ever more strict limits for vehicle emissions; combined with customer expectations for growing levels of performance and equipment, automotive manufacturers face a significant challenge. With the aim of meeting this challenge, downsizing is an established trend in passenger car engine development. However, since downsizing is commonly achieved through pressure charging (turbocharging, for example), the associated benefits in improved fuel economy and emissions are often obtained at the expense of engine dynamic response, and, consequently, vehicle driveability. This thesis presents predominantly simulation-based research into a novel combined charging system comprising a conventional turbocharger used in conjunction with a declutchable supercharger driven through a CVT. An initial investigation using this system in place of a variable geometry turbocharger on an already downsized passenger car diesel engine demonstrated greatly increased low speed torque as well as improved dynamic response. A downsizing project that involved replacing a naturally aspirated gasoline engine with a highly boosted engine with 40% of the original displacement formed the basis for more extensive investigations. Although it was unable to produce the low speed transient response of the naturally aspirated engine, in tip-in tests the CVT-supercharger system was shown to achieve the target torque much quicker than an equivalent system with a fixed supercharger drive ratio. However, balancing this with good fuel efficiency for the initial part load period was a complex trade-off. In vehicle acceleration simulations the CVT-supercharger system did not outperform the fixed drive ratio configuration, but on the CVT system the boost limit was reached at an early stage during the transients. Thus there may be potential to include an ‘over-boost’ facility, allowing boost pressure to temporarily exceed normal steady state limits in order to improve transient performance and bring it closer to that of the baseline vehicle. It is suggested that the CVT-supercharger provides the best flexibility for calibration and compromise between performance and fuel efficiency, perhaps incorporating different user-selectable modes (such as ‘economy’ and ‘sport’ modes).

The aim of this thesis is the description and performance of four-stroke internal combustion engine, an analysis of the options and finding the most effective treatment for a given engine type. In the next section the author deals with computational design turbochargers, chosen for the turbocharged engine modification. Next chapter of work is a design calculation for the choice of the turbocharger, is then constructed a mathematical model of a given engine in the Lotus Engine Simulation software and final results are presented.

Diplomová práce je zaměřena na výběr pohonné jednotky pro Formuli Student, sestavení spolehlivého výpočtového modelu za využití pokročilého testování. Dále se zaměřuje na přípravu vhodných podmínek pro testování, samotné testování a následnou kalibraci řídicí jednotky pro validaci simulací a také pro efektivní a spolehlivé řízení motoru v náročných závodních podmínkách. Je zároveň součástí komplexního projektu, který se zabývá celkovým vývojem přeplňovaného jednoválcového motoru pro tým TU Brno Racing.

Internal combustion engines developments are driven by emissions reduction and energetic efficiency increase. To reach the next standards, downsized/downspeeded engines are required to reduce fuel consumption and CO2 emissions. These techniques place an important demand on the charging system and force the introduction of multistage boosting architectures. With many possible arrangements and large number of parameter to optimize, these architectures present higher complexity than current systems. The objective of this thesis has thus been to investigate the potential of two-stage boosting architectures to establish, for the particular case of passenger car downsized/downspeeded Diesel engines, the most efficient solutions for achieving the forthcoming CO2 emissions targets. To respond to this objective, an exhaustive literature review of all existing solutions has first been performed to determinate the most promising two-stage boosting architectures. Then, a new matching methodology has been defined to optimize the architectures with, on the one hand the development of a new turbine characteristic maps representation allowing straight forward matching calculations and, on the other hand, the development of a complete 0D engine model able to predict, within a reduced computational time, the behavior of any boosting architecture in both steady state and transient operating conditions. Finally, a large parametric study has been carried out to analyze and compare the different architectures on the same base engines, to characterize the impacts of thermo-mechanical limits and turbocharger size on engine performance, and to quantify for different engine development options their potential improvements in term of fuel consumption, maximum power and fun to drive. As main contributions, the thesis provides new modeling tools for efficient matching calculations and synthesizes the main trends in advanced boosting systems to guide future passenger car Diesel engine develop
Varnier ., ON. (2012). Trends and Limits of Two-Stage Boosting Systems for Automotive Diesel Engines [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/16880
Palancia

Ce travail s'inscrit dans le cadre d'un partenariat entre Honeywell Turbo Technologies et le département d'Aérodynamique, Energétique et Propulsion de l'ISAE. En réponse à des objectifs industriels d'amélioration des étages turbine des systèmes de suralimentation automobile, deux axes d'étude sont dégagés: le diagnostique et l'amélioration des étages de turbine à géométrie variable utilisés dans la suralimentation des moteurs Diesel, et l'évaluation d'une turbine axiale spécifiquement conçue pour la suralimentation des moteurs essence. La première partie traite de l'influence des paramètres permettant de réaliser le couplage avec le moteur. Cette étude, basée sur une double analyse, permet d'identifier les enjeux du point de vue des performances de l'étage turbine mais aussi leur intégration dans la performance globale du moteur. Nous traitons ensuite des contraintes d'intégration imposées par le fonctionnement optimal de la boucle de suralimentation. En réponse aux problématiques soulevées, une procédure d'optimisation, basée sur une approche théorique, des étages turbine est présentée. Celle-ci permet de dégager des conclusions fortes sur la spécificité des étages à géométrie variable qui sont finalement déclinées dans un contexte industriel. Une synthèse bibliographique des règles de dimensionnement des turbines axiales débute la seconde partie. Cette architecture de machine, disposant d'une faible inertie et d'une grande compacité, semble toute indiquée pour répondre à la problématique de suralimentation des moteurs essence. La conception a nécessité une étude spécifique des différents critères de design car la géométrie axiale est atypique dans cette gamme de débit. Des résultats de simulations numériques permettent d'évaluer le potentiel aérodynamique de cet étage. Enfin, celle-ci est confrontée à l'étage de turbine radiale actuellement utilisé afin d'évaluer son potentiel dans le cadre du couplage moteur
This work results from a partnership between Honeywell Turbo Technologies and the département d'Aérodynamique, Energétique et Propulsion of the ISAE. The main industrial goal are improving turbine stages of boosting systems. The problem is tacked through two thematics : the optimization of variable geometry radial turbine used for boosting systems of gasoline engines. The first part deals with the influence of parameters used for matching are first discussed. This study, based on double analysis, is used to identfy the stakes of turbine stage performance but also take global engine performances into account. Contraints ipmposed by peripheral systems such as cooling systems or catalytic converter are then traited. This leads to an optimization process based on theorical approach wich allows to conclude on radial turbine stage characteristics. Finally, we turn in information about industrialization. The second part begin with a literature survey of axial turbine stage design method. This type of machine, with low inertia and high compacity, can be relevant for boosting systems of gasoline engines. Design needs a specific study on criterion parameters because it is unsual to encounter axial turbines with such small diameters. CFD results give aerodynamics performances of axial stage. Then, comparison of turbocharger with engine matching between radial and axial stages is proposed

I jämförelse med sina föregångare, har moderna lastbilsmotorer genomgått en betydandeutveckling och har utvecklats till effektiva kraftmaskiner med låga utsläpp genom införandet avavancerade avgasbehandlingssystem. Trots att de framsteg som gjorts under utvecklingen av lastbilsmotorer har varit betydande, så framhäver de framtida förväntningarna vad gällerprestanda, bränsleförbrukning och emissioner behovet av snabba samt storskaliga förbättringar av dessa parametrar för att förbränningsmotorn ska fortsätta att vara konkurrenskraftig och hållbar. Utmaningen i att uppfylla dessa till synes enkla krav är den invecklade, ogynnsammabalansgång som måste göras mellan parametrarna. Förbränningsmotorns kärna är förbränningsprocessen, som i sin tur är kopplad till motorns luftbehandlings- och bränsleregleringssystem. I denna studie undersöks Millercykeln som en potentiell lösning till att nå de motstridiga kraven för framtida lastbilsmotorer, framförallt med fokus på potentialen att förbättra prestandan samtidigt som NOx-emissionerna hålls på konstantnivå. Traditionellt har utvärderingen av Millercykeln utförts på encylindriga forskningsmotorer, vilket också har utgjort utgångspunkten i denna studie. Även om studier på flercylindriga simuleringsmodeller och forskningsmotorer har gjorts med konstanta inställningar för Millercykeln, så utförs de inte i samband med undersökningar av encylindriga motorer. Dessutom så möts inte kraven från insugssystemet på samma sätt mellan de olika motorkonfigurationerna. Denna studie undersöker och jämför potentialen för ökad prestanda med Miller-cykeln mellan encylindrig och flercylindrig motorkonfiguration för en lastbilsmotor med ett tvåstegs turboladdningssystem, som representerar ett realistiskt insugssystem som möjliggör implementeringen av Millercykeln. För att undersöka motorprestationen så används i denna studie den kommersiella mjukvaran GT-Power. Ytterligare resultat från studien innefattar kvantifiering av prestandakraven för ett högeffektivt tvåstegs turboladdningssystem och dess inverkan på temperaturen i inloppet till avgasbehandlings-systemet. En kvalitativ förståelse av betydelsen av interaktionen mellan cylindrar och effekten på cylinder-cylinder variationer med Millercykel utfördes också i simuleringar med flercylindrig motorkonfiguration. Studien utvärderade Millertiming inom ett intervall på -90 till +90 graders vev vinkel från utgångsvinkeln för stängning av insugsventilen. Utvärderingen utfördes vid systemjämvikt vid en fullastpunkt (1000RPM), där basfallet för både encylindrig och flercylindrig motor för utvärdering av Millercykeln var det välkända fallet med konstant specifik NOx. Ett ytterligare fall framhäver NOx-reduktionspotentialen med Miller vid konstant EGR-flöde på en encylindrig konfiguration. Fallen med ökad prestation realiserades genom att öka lufttillförseln, bränslemängden och det geometriska kompressionsförhållandet. Maximal prestandaökning observerades i fallet med ökad bränslemängd, och endast i detta fall utvärderades även konfigurationen med fler cylindrar för jämförelse av prestationsförbättringen med en encylindrig motsvarighet med Millertiming. Den flercylindriga motorn innefattade EGR som en lågtryckskrets, och medan detta antagande förenklade i avseende på modellering och kontroll, så var det till fördel för konfigurationen meden flercylindrig motor (jämfört med encylindrig) på grund av reducerade pumpförluster. Som påföljd gjordes en jämförande undersökning med encylinder-modellen med motsvarande mottryck för flercylinder-modellen inställt som gränsvärde. Resultaten visar att encylindermodellen representerar medelvärdet för cylindrarna i flercylinder-motorn när lämpligagränsvillkor tillämpas som kontrollparametrar. Studien ger en grund för jämförelse av Millertiming på encylindrig samt flercylindriga konfigurationer, samtidigt som kraven på insugssystemet fastställs och utgör en utgångspunkt föratt utvärdera Millercykeln och bestämma insugssystemets krav för hela motorns arbetsområde.
Modern heavy-duty engines have undergone considerable development over their predecessors and have evolved into efficient performance machines with a reducing emission footprint through the incorporation of advanced aftertreatment systems. Although, the progress achieved in heavy-duty engine development has been significant, the future expectation from heavy-duty engines in terms of performance, fuel consumption and emissions stresses the need for rapid large-scale improvements of these metrics to keep the combustion engine competitive and sustainable. The challenges in resolving these apparently straightforward demands are the intricate unfavourable trade-off that exists among the target metrics. The core of the combustion engine lies in the combustion process which is inherently linked to the air handling and fuel regulating systems of the engine. This study explores adopting the Miller cycle as a potential solution to the conflicting demands placed on future heavy-duty engines with an emphasis on the performance enhancement potential while keeping the specific NOX emission consistent. Traditionally, evaluation of the Miller cycle is performed on single-cylinder research engines and formed the starting point in this study. While studies on full-engine simulation models and test engines with fixed Miller timing have been evaluated, they appear to be performed in isolation of the favoured single-cylinder approach. Additionally, the charging system requirements are not consistently addressed between the two approaches. This study investigates and contrasts the performance enhancement potential of the Miller cycle on single-cylinder and serial enginemodels of a heavy-duty engine along with a two-stage turbocharging system to represent a realistic charging system that enables implementation of Miller timing. The commercial engine performance prediction tool GT-Power was used in this study. Additional outcomes of the study included quantifying the performance demands of a high efficiency two-stage turbocharging system and its impact on the inlet temperature of the exhaust aftertreatment system. A qualitative understanding of the significance of cylinder interaction effects on cylinder-cylinder variations with Miller timing was also performed on the serial engine cases. The study evaluated Miller timing within a range of -90 to +90 CAD from the baseline intake valve close angle. The evaluation was performed at steady-state operation of the engine at one full load point (1000RPM) wherein both the single-cylinder and serial engine Miller evaluation included a base case which characterises the Miller effect for constant specific NOX. An additional case highlights the NOX reduction potential with Miller for a constant EGR rate on the single-cylinder configuration. The performance enhancement cases were realised by increasingthe air mass, fuel mass and the geometric compression ratio. Maximum performance increase was observed in the increased fuel mass case and only this case was evaluated on the serial engine for contrasting single-cylinder and serial engine performance enhancement with Miller timing. The serial engine incorporated EGR as a low-pressure circuit and while this simplified modelling and controller considerations, it led to biasing of results in favour of the serial engine configuration (over the single-cylinder) due to reduced pumping loss. A subsequent comparison case was evaluated on the single-cylinder model with backpressure settings from the serial engine model. The results show that the single-cylinder model is representative of the cylinder averaged responses of the serial engine when appropriate boundary conditions are imposed as controller targets. The study provides a basis for contrasting Miller timing on single-cylinder and serial configurations while determining the charging system requirements and presents a starting point to evaluate Miller timing and determine air system demands over the entire engine operating range.

This diploma thesis deals with valve train design of turbocharged engine used in Formula Student category race car. Based on thermodynamic model, a proper valve timing was chosen to achieve maximum power at high engine speed. A kinematic model was used to compute final cam profiles and CAD model was created.

This master thesis summarizes the basic knowledge in the field of turbocharging of internal combustion piston engines. It also focuses on the analysis of some properties of multistage turbocharging, especially for diesel engines. Using analytical relationships, a model in the form of a web application has been created, which describes the cooperation of a turbocharger or turbochargers with an internal combustion engine. With the help of this model, some two-stage supercharging options for the selected engine have been then proposed.

The aim of this diploma thesis is supercharging of SI engines and design influence on performance. The main objective of this thesis is to propose appropriate modifications on AR67203 engine of Alfa Romeo 155Q4 personal vehicle in order to achieve significantly better performance parameters and a constant torque in the widest possible speed range. That is why I analyze design and modifications that affect the overall engine performance and their appropriate application to the selected engine. An important point of this thesis is the right choice of turbocharger, in order to have an effective cooperation with a modified engine. The calculation study and the simulation in Lotus Engine Simulation software serve this purpose. I also give information about ECU programming. The results, as well as a practical output in the form of measured performance parameters of modified engine, are evaluated at the end.

The work described in this thesis aims to conduct a systematic study of the two stage turbocharging system to improve the Diesel engine transient performance as well as NOX and CO2 emissions with a focus on the improved turbocharger matching and the control of the charging system, through the use of high fidelity engine models backed by experimental results. To perform the analytical study, commercial 1D simulation software has been used in the process of system characterisation and control strategy design. To validate the analytical results, a two stage turbocharging system was installed on a production diesel engine and tested on a transient engine test bench. The test results were then used to further calibrate the 1D engine/turbocharger model. Several other technologies were also investigated in simulation to explore their potential to further improve the system. Unlike most studies in the literature, this project focused on the system benefit of the engine and turbochargers, instead of conducting optimisation solely at the component level. The engine global parameters, such as the engine fuel consumption, emission levels and the transient response were the main parameters to be considered and were also best suited to the strengths of the 1D simulation method. The interactive use of both the analytical and experimental methods was also a strong point of this study. A novel control strategy for the system was proposed and demonstrated in the simulation. Experiments confirmed the validity of this control strategy and provided data for further model calibration. The comparison of the test results of the baseline engine to those obtained with the two stage turbocharged engine system verified the benefits of the novel turbocharging arrangement and control scheme. Transient response (T1090) was improved, with a 50% faster torque rise at 1000 rpm; the fuel consumption over the NEDC was 4% lower and NOx emissions over the NEDC were 28% lower. In the meantime, the study also revealed shortcomings of the system, such as the lack of EGR control at low speed, low load condition and a mid-speed fuel consumption deterioration of 13% on average at 3000 rpm due to excessive back pressure. With a novel 1D model corroborated using test results, exploratory simulation was done to rectify the aforementioned shortcomings and to further improve the system. Simulation results showed that by implementing VGT and ball bearing technology in the high pressure stage of the two stage system, the EGR controllability at low speed was regained and the excessive back pressure at high speed was improved. Consequently, the fuel consumption was only increased by 1.3% compared to the baseline NEDC operation and the transient response was on par with the original two stage system, with only 0.05s slower in torque rise at 1000 rpm, and still 48% faster than the baseline VGT system. Furthermore, the NOx emission can be expected to be greatly improved in the upcoming more intensive drive cycles compared to the NEDC cycle, with simulation showing NEDC NOX emissions dropped by 1%, comparing to a substantial reduction of 11% in WLTC.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 95-97).
This thesis presents a method for turbocharging single cylinder four stroke internal combustion engines, a model used to evaluate it, an experimental setup used to test it, and the findings of this experiment. A turbocharged engine has better fuel economy, cost efficiency, and power density than an equivalently sized, naturally aspirated engine. Most multi-cylinder diesel engines are turbocharged for this reason. However, due to the timing mismatch between the exhaust stroke, when the turbocharger is powered, and the intake stroke, when the engine intakes air, turbocharging is not used in commercial single cylinder engines. Single cylinder engines are ubiquitous in developing world off grid power applications such as tractors, generators, and water pumps due to their low cost. Turbocharging these engines could give users a lower cost and more fuel efficient engine. The proposed solution is to add an air capacitor, in the form of a large volume intake manifold, in between the turbocharger compressor and the engine intake to smooth out the flow.
by Michael Rafael Buchman.
S.M.

La diminution de la cylindrée ou le downsizing du moteur est potentiellement l'une des stratégies les plus efficaces pour améliorer la consommation de carburant et diminuer les émissions polluantes. Dans le domaine de la suralimentation, la simulation est limitée par les caractéristiques de fonctionnement des turbines fournies par les constructeurs. Une extrapolation précise et fiable des cartographies turbine est donc l’objectif de cette thèse. Une étude expérimentale sur une turbine radiale d’un turbocompresseur est effectuée avec différentes techniques pour mesurer la cartographie turbine la plus large possible. Les mesures sont effectuées sur un banc turbocompresseur classique avec différentes températures d'entrée turbine. Puis une technique de gavage en entrée et en sortie compresseur est testée. Le compresseur est ensuite remplacé par un autre compresseur à roue inversée qui peut aider la turbine à tourner et même l’entrainer. Les débits les plus faibles et même les débits négatifs sont mesurés. Un banc turbine électromécanique a également été développé, mais n’a pas pu donner de résultats satisfaisants à cause de problèmes techniques mais des évolutions à venir restent prometteuses. Les diverses techniques expérimentales testées ont aussi permis de mesurer le rendement isentropique de la turbine et le rendement mécanique du turbocompresseur. Finalement, plusieurs modèles d’extrapolation des courbes caractéristiques turbine ont été testés et confrontés aux résultats expérimentaux
Engine downsizing is potentially one of the most effective strategies being explored to improve fuel economy and reduce emissions. In the field of turbocharging,simulation is limited by the operating characteristics of turbines supplied by the manufacturers. An accurate and precise extrapolation of the turbine performance maps is the main aim of this study. An experimental study was done on a radial turbine of a turbocharger with different techniques to measure the wider turbine performance map possible. Measurements were done on a classic turbocharger test bench with different turbine inlet temperatures. Then air was blown to the compressor inlet and exit: it is the compressor “gavage”. The compressor is then replaced with another one with are versed rotor: this compressor can help the turbine turn and even drive it itself. The lowest mass flow rates are measured even the negative ones. An electromechanical turbine test bench was developed but did not work correctly because of technical problems but future developments are promising. The various experimental techniques used allowed also the measurement of the turbine isentropic efficiency and the turbocharger mechanical efficiency. Finally, many extrapolation models of the turbine performance maps were tested and compared to the experimental results

The thesis deals with the current situation in the construction of tractors, particularly engines and accessories. The work includes a methodology for measuring tractor rigs in traffic as well as methodology for plough/plow kits measuring. The measured values were tabulated, graphically presented and analysed. The thesis provides an overview of the issue of the combustion engine load placed on the engine by working conditions in transport, during primary soil tillage with different modes of operation of the tractor set. The thesis aim is to find out the practical effect of the engine load on the monitored parameters and to indicate possibilities for achieving higher efficiency in tractor units with minimum fuel performance

Les travaux de cette thèse s’inscrivent dans le cadre de la mise en place d’une méthodologie innovante de gestion thermique globale des véhicules automobiles. Ils portent plus particulièrement sur l’analyse de la réduction des émissions de polluants et l’amélioration des performances énergétiques d’un moteur à combustion, notamment dans les charges partielles ou en régime transitoire. Le premier objectif vise la mise en évidence de l’effet de la température d’admission sur le fonctionnement du moteur. Le deuxième objectif est relatif à la prédiction de l’apparition des phénomènes de condensation inhérents aux procédés de recirculation des gaz d’échappement à l’admission moteur. Enfin le troisième objectif est la modélisation et la mise en œuvre d’un circuit d’eau refroidit par la boucle de climatisation dont la fonction est de sous refroidir les gaz d’admission du moteur. Le premier chapitre est consacré à la présentation du système thermique véhicule et de la démarche de conception en V adoptée dans ce travail. Dans le second chapitre, et après avoir mis en évidence les effets d’un sous refroidissement des gaz admission sur le rendement thermodynamique du moteur, on montre à l’aide d’une étude technologique et numérique de la boucle de climatisation qu’il est possible d’opérer ce refroidissement par un système embarqué capable de se régénérer thermiquement lors d’un freinage. Le troisième chapitre est dédié à la modélisation du système à l’aide d’une modélisation énergétique centrée sur l’utilisation du langage bond graph. Le dernier chapitre est dédié au volet expérimental afin de valider d’une part le modèle de condensation et d’autres part un démonstrateur d’hybridation thermique et ses stratégies de pilotage
The work of this thesis is part of the development of an innovative methodology in the field of global thermal management for motor vehicles. It focuses specifically on the analysis of the reduction of pollutant emissions and improving energy efficiency of a combustion engine, especially in partial load or transient operation. The first objective is to analyze the effect of inlet temperature on the engine performance. The second objective relates to the prediction of the condensation processes inherent to exhaust gas recirculation into the engine intake. Finally, the third objective is the modeling and implementation of a water circuit cooled by the air conditioning loop and whose function is to cool the gases in at the engine intake.The first chapter is devoted to the presentation of the vehicle thermal management system and the design process adopted in this work. In the second chapter, after having shown the effects of intake gas cooling on the thermodynamic efficiency of the engine, it is shown with a numerical and technological study of the air conditioning loop that is possible to operate an onboard cooling system that is capable of regenerating heat when braking. The third chapter focuses on system modeling using an energy modeling focuses on the use of bond graph language. The final chapter is dedicated to the experimental part with the objective of validating the model of gas condensation and a demonstrator of thermal hybridation and its control strategies