Дисертації з теми "621.43.06:621.436"

Turbocharging systems are of high importance in the enhancement of engine power and efficiency. Faults in such systems may cause increased emissions levels beyond those set by legislation, and may also compromise fuel efficiency. This thesis investigates the application of system identification and vibration signal analysis techniques for the performance monitoring of turbocharged diesel engines by exploring turbocharger behaviour. The first technique is based on the use of system identification to build models representing the input and output relationship of an engine process. In this case, torque demand is the input, and the turbocharger speed is the output in a medium duty, turbocharged diesel engine. The proposition set here is that the model that can be derived does not have to reflect the complexity of the physical system. Hence, if simple models can be derived, any deviation from the model of normal operation, if adhering to some principles, could indicate the existence of a fault in a system. Dynamic linear auto-regressive moving averages with exogenous input (ARMAX) models were estimated to represent the relationship between input and output. The models have been used to demonstrate the capability of the proposed technique to diagnose faults.

This thesis describes the development of high efficiency turbochargers and turbogenerators to significantly increase the power to weight ratio and reduce both the fuel consumption and emissions from heavy duty diesel engines. A literature overview is provided for turbomachinery based exhaust energy recovery projects in the public domain. The technologies are discussed in detail and compared using real test data. The thesis describes some design issues that were experienced during engine testing one with a heat shield and one with a volute - and how finite element analysis was used to generate solutions and long term evolutions in the designs. A variable nozzle guide vane ring was designed but seizing of the mechanism occurred during testing. A low friction coating was shown to be the solution.

The main focus of this thesis is the investigation of nonlinear control designs on the airpath of a diesel engine equipped with exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT). This problem presents strong couplings between controlled variables and actuators, since both EGR and VGT flows are driven by gases in the exhaust manifold. An additional coupling arises from the common shaft of the compressor and the turbine. The multivariable, highly nonlinear dynamics of the system gives motivation for model-based nonlinear control. Firstly, an eighth order mean-value model of the diesel engine is derived. This is consequently used to perform closed-loop simulations and to tune the controller gains offline. To reduce the complexity of the controllers, a third-order mean-value is used to design the nonlinear controllers.

The work contained in this thesis presents a computational study on the effects of fuel stream perturbations in non-premixed flames in terms of pollutant formation (soot and NOx), including the application to a practical case scenario, such as direct injection diesel engine. The initial part of the work concentrates on the implementation in FLUENT of a soot model that is based on the Eddy Dissipation concept of Magnussen, which accounts for the effects of small scale turbulence in the formation and depletion of soot particles.

The term 'dual fuel' refers to a compression ignition engine where a small quantity of diesel fuel called the pilot is used to ignite a second gaseous fuel which is the primary energy source. The motivation to use dual fuel has traditionally been economic, as the primary fuel is often less expensive than the distillate fuel it replaces. However, some benefits in terms of the reduced emissions of smoke and oxides of nitrogen (NOx) can also be achieved. In this research, a small, direct injection diesel engine was converted to dual fuel operation. This engine is typical of those used in stationary power generation applications. A review of literature revealed that whilst performance and emissions trends were well established for indirect injection engines, little research had been conducted on a direct injection engine. In particular, this class of small, high speed industrial engine had been somewhat neglected, partly because they have been subject to less stringent emissions legislation than their automotive counterparts. By performing a detailed investigation ' into the errors and assumptions that have a bearing on the three zone technique, it was possible to challenge some previous assumptions regarding the dual fuel combustion process. Namely, the theory that the pilot bums in two separate initial stages was found to be a deficiency of previous analysis techniques and therefore incorrect. It was found that as the proportion of the gaseous fuel was increased, the combustion process retained similar characteristics and magnitudes of mass burned to diesel until all but the highest equivalence ratios. At this point, the premixed and diffusion burning periods merged, but continued to show a fundamental dependence on the pilot ignition and the combustion processes were never independent of the pilot. The range of equivalence ratios over which the transition between the two patterns occurs is firstly a function of the primary fuel, and secondly a function of the operating conditions (such as in cylinder temperature). It is proposed that the dual fuel combustion process is better described as a diesel combustion process with a modified diffusion burning period that results from the gaseous fuel concentration and type. By using this explanation, it was identified that the emissions characteristics of the engine could be modified through the use of a second fuel. The primary fuel can reduce the initial mass burning rates (to reduce NOx) and simultaneously elevated the diffusion burning rates (to reduce smoke emissions). This provides an alternative, beneficial means by which the classic diesel NOx-Particulate trade-off can be manipulated. Butane was found to be unsuitable for this type of engine, and propane consistently yielded the best performance and emissions trends. Additionally, it was found that the addition of small quantities of methane or propane can result in disproportionately large reductions in smoke and NOx without the penalty of increased carbon monoxide and unburned hydrocarbons.

Large 2-stroke marine diesel engines burn high sulphur content residual fuel. The sulphur converts to aqueous sulphuric acid, H2SO4, and condenses on the cylinder liner surface, where it causes corrosive attack when not neutralised by the high alkaline reserve in the lubricant. Cylinder liner wear and deposit formation are observed to reflect poor lubricant distribution, surface temperature and sulphur fuel content, which all influence acid concentration. Currently neglected by the industry, is the catalysing action of H2SO4 on lubricant degradation and the rheology of entrained droplets in the oil film, which was the motivation for this study. To understand the basic interaction of H2SO4 with the lubricant film, the Saturated hydrocarbon squalane, C30H62, was chosen as a simple model oil in addition to fully formulated lubricants and their corresponding API Group I base oils. Interfacial tension between oil and aqueous solutions of H2SO4 was measured. Contact angles of aqueous solutions of H2SO4 immersed in C30H62 on piston ring chrome coating compared to grey cast iron cylinder liner material were measured. Fully formulated lubricant and API Group I base oil was used pure and emulsified with H2SO4 to lubricate a piston ring/ cylinder contact on a Plint TE77 Tribometer. The main analytical techniques were the light microscope, SEM/EDX, XPS, FTIR, laser diffraction particle size characterisation, white-light-interferometer and viscometer. Inter facial tension measurements of aqueous H2SO4 against C30H62 reveal a close relationship with the dissociation of H2SO4, which is also reflected by the formation of bituminous emulsions with API Group I base oil when above 40% w/wH2SO4 and formation of solids when above 80% w/wH2SO4 and high temperatures of around 120–165°C or long storage times. For pure water, the contact angles were found to be large while they were small for concentrated sulphuric acid. Contact angles on chrome coating were bigger than on grey cast iron. Advancing contact angles were larger than static and receding contact angles, which was expected. During the TE77tests,the degradation temperature of the base oil was lowered when in contact with H2SO4 from 250 to 80°C for oxidation, from 300 to 170°C for nitration and from 300 to 120°C for deposit formation. Over all the appearance of the surfaces improved when sulphuric acid was added to both, the API Group I base oil and the fully formulated lubricant.

Over the last decade, the diesel engine has made dramatic progress in its performance and market penetration. However, in order to meet future emissions legislations, Nitrogen Oxide (NOx) and particulate matter (PM) emissions will need to be reduced simultaneously. Nowadays researchers are focused on different combustion modes like homogeneous charge compression ignition (HCCI) combustion and premixed charge compression ignition (PCCI) which have a great potential for both low soot and low NOx. In order to achieve these combustion modes, different injection strategies have been investigated. This study investigates the effects of split injection strategies with high levels of Exhaust Gas Recirculation (EGR) on combustion performance and emissions in a high speed direct injection optical diesel engine. The investigation is focused on the effects of split injections at different injection pressures, injection timings and dwell angles using base diesel and biodiesel fuels. The effect of fuel properties has been also investigated as an attempt to reduce regulated exhaust emissions in diesel engines. Performance, emissions and combustion characteristics have been examined for two different biodiesel fuels, namely BTL 50 and BTL 46. A Ricardo Hydra single cylinder optical engine was used in which conventional experimental methods like cylinder pressure data, heat release analysis and exhaust emissions analysis were applied. Optical techniques like direct spray and combustion visualization were applied by means of a high speed imaging system with a copper vapour laser illumination system. A high-speed two-colour system has been developed and implemented to obtain in-cylinder diesel combustion temperature and soot measurements to gain better understanding of the mixture formation and combustion processes. This investigation concludes that the split injection strategies show potential to achieve low emissions combustion.

This thesis describes work undertaken at the University of Brighton on a rapid compression machine based on a two-stroke diesel engine (Proteus) with an optical head to allow observation of the fuel spray. A long-tube, rate of injection rig was used to measure the injection rate of the fuel injection system. Quantification of cyclic variation and rate of injection were carried out for single and multiple-injection strategy. For multiple-injections, it was found that the injected mass of the first of the split was approximately 19% less than that of the single injection strategy for the same injection duration. The second split reduction was less than 4% in comparison to the single injection strategy. The transient response of the fuel injection equipment was characterised and compared with steady-state behaviour. The characteristics of the Proteus rig in terms of trapped air mass and transient incylinder temperature were investigated and quantified. The effect of in-cylinder temperature, density and pressure, as well as injection pressure on the characteristics of spray formation, for single and multi-hole nozzles were investigated using high speed video cameras. Cycle-to-cycle and hole-to-hole variations for multi-hole nozzles were investigated and attributed to uneven fuel pressure distribution round the needle seat, and subsequent cavitation phenomena. Simultaneous Planar Laser Induced Fluorescence (PLIF) and Mie scattering techniques were used to investigate spray formation and vapour propagation for multihole nozzles for single and multiple-injection strategy. The multiple injection work focused on the effect of dwell period between each injection. Two different modes of flow were identified. These are described as 'wake impingement' and 'cavity mode wake effect', resulting in increased tip velocity of the second split spray. The increase in tip velocity depended on dwell period and distance downstream of the nozzle exit. The maximum increase was calculated at 17 m/s. A spray pattern growth for the second of the split injections, the 'exceed type' was identified, resulting from an increase in tip penetration due to air entrainment of the first split and propagation into the cooler vapour phase from the first split. The effect of liquid core length near the nozzle exit was investigated using modified empirical correlations and the evolution of the discharge coefficient obtained from rate of injection measurements. The results showed increased injection pressure and increased in-cylinder gas pressure reduce both break-up length and break-up time. Penetration was modelled using conservation of mass and momentum of the injected fuel mass. The input to the numerical model was the measured transient rate of injection. The model traced the centre-of-mass of the spray and was validated against PLIF data for centre-of-mass. Overall, the same value of modelling parameters gave good agreement for single and split injection strategy.

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.05.03 – двигуни та енергетичні установки. – Національний технічний університет "Харківський політехнічний інститут". – Харків, 2017. Дисертація присвячена вибору і обґрунтуванню параметрів дизель-електричної станції з системою утилізації вторинної теплоти дизеля з використанням циклу Ренкіна, що використовує теплоту відпрацьованих газів та системи охолодження. В результаті аналізу особливостей перспективної енергетичної установки з двигуном Hyundai 25/33 для виробництва електричної енергії на заводі в Іраку розроблена технологічна схема комплексної системи утилізації вторинної теплоти дизель-електричної станції з додатковим отриманням електроенергії, теплоти для підігріву важкого палива, конденсації технічної води з відпрацьованих газів двигуна. Для утилізації вторинної теплоти двигуна Hyundai H25/33 запропоновано утилізаційний контур установки, який працює за органічним циклом Ренкіна (ОЦР). В якості робочого тіла в циклі Ренкіна доцільно використовувати воду системи охолодження двигуна. З використанням розробленої математичної моделі утилізаційного контуру дизель-електростанції виконане розрахунково-експериментальне дослідження впливу температури навколишнього середовища на показники ефективності утилізаційного контуру. При зміні температури навколишнього середовища від 0 ° С до 40 ° С кількість електроенергії, виробленої за циклом Ренкіна для двигуна Hyundai H25/33 збільшується до 10%. При роботі однієї когенераційної установки з двигуном Hyundai H25/33 та розробленим утилізаційним комплексом можна отримати на добу до 2300 кг конденсату водяної пари, що є дуже цінною в Іраку. На основі результатів дослідження було розроблено два варіанта технологічної схеми (проекти "А" та "Б") модернізації дизельних електростанцій компанії Hyundai Heavy Industries. Виконана техніко-економічна оцінка проектів за метод NPV показала, що після того, як обладнання утилізаційного контуру в повному обсязі буде введено у експлуатацію, максимально досяжний прибуток складе близько 1 406 219 дол. США/рік.
Dissertation for the degree of candidate of technical sciences in specialty 05.05.03 – engines and power plants. – National Technical University "Kharkiv Polytechnic Institute". – Kharkiv, 2017. The dissertation is devoted to the choice and substantiation of parameters of a diesel power plant with heat recovery system of recycling the secondary heat from diesel engine using the Rankin cycle, which uses the heat of exhaust gases and cooling water systems. As a result of the analysis of the features of a promising power plant with a Hyundai 25/33 engine for the production of electric power at a plant in Iraq, a technological scheme of a comprehensive system for recycling diesel fuel from an electric power station with the additional generation of electricity, heat for heating heavy fuel, condensing technical water from exhaust gases. As a working fluid in the Rankin cycle, it is advisable to use the hot water from the engine cooling system. Using the developed mathematical model of the distillation circuit of the diesel power plant, the design-experimental study of the influence of the ambient temperature on the indicators of the efficiency of heat recovery was performed. When the ambient temperature changes from 0 ° C to 40 ° C, the amount of electric energy generated by the Rankin cycle for the Hyundai H25 / 33 engine increases to 10%. With a single cogeneration unit with a Hyundai H25 / 33 engine and a recycling complex developed, it is possible to get up to 2300 kg of water vapor condensate per day, which is very valuable in Iraq. Based on the results of the study, two variants of the technological scheme (projects A and B) were developed for the modernization of Hyundai diesel power plants. The feasibility study for the NPV method has shown that after the full recovery equipment is put into operation, the maximum achievable profit will be about 1 406 219 $ /year.

Dissertation for the degree of candidate of technical sciences in specialty 05.05.03 – engines and power plants. – National Technical University "Kharkiv Polytechnic Institute". – Kharkiv, 2017. The dissertation is devoted to the choice and substantiation of parameters of a diesel power plant with heat recovery system of recycling the secondary heat from diesel engine using the Rankin cycle, which uses the heat of exhaust gases and cooling water systems. As a result of the analysis of the features of a promising power plant with a Hyundai 25/33 engine for the production of electric power at a plant in Iraq, a technological scheme of a comprehensive system for recycling diesel fuel from an electric power station with the additional generation of electricity, heat for heating heavy fuel, condensing technical water from exhaust gases. As a working fluid in the Rankin cycle, it is advisable to use the hot water from the engine cooling system. Using the developed mathematical model of the distillation circuit of the diesel power plant, the design-experimental study of the influence of the ambient temperature on the indicators of the efficiency of heat recovery was performed. When the ambient temperature changes from 0 ° C to 40 ° C, the amount of electric energy generated by the Rankin cycle for the Hyundai H25 / 33 engine increases to 10%. With a single cogeneration unit with a Hyundai H25 / 33 engine and a recycling complex developed, it is possible to get up to 2300 kg of water vapor condensate per day, which is very valuable in Iraq. Based on the results of the study, two variants of the technological scheme (projects A and B) were developed for the modernization of Hyundai diesel power plants. The feasibility study for the NPV method has shown that after the full recovery equipment is put into operation, the maximum achievable profit will be about 1 406 219 $ /year.
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.05.03 – двигуни та енергетичні установки. – Національний технічний університет "Харківський політехнічний інститут". – Харків, 2017. Дисертація присвячена вибору і обґрунтуванню параметрів дизель-електричної станції з системою утилізації вторинної теплоти дизеля з використанням циклу Ренкіна, що використовує теплоту відпрацьованих газів та системи охолодження. В результаті аналізу особливостей перспективної енергетичної установки з двигуном Hyundai 25/33 для виробництва електричної енергії на заводі в Іраку розроблена технологічна схема комплексної системи утилізації вторинної теплоти дизель-електричної станції з додатковим отриманням електроенергії, теплоти для підігріву важкого палива, конденсації технічної води з відпрацьованих газів двигуна. Для утилізації вторинної теплоти двигуна Hyundai H25/33 запропоновано утилізаційний контур установки, який працює за органічним циклом Ренкіна (ОЦР). В якості робочого тіла в циклі Ренкіна доцільно використовувати воду системи охолодження двигуна. З використанням розробленої математичної моделі утилізаційного контуру дизель-електростанції виконане розрахунково-експериментальне дослідження впливу температури навколишнього середовища на показники ефективності утилізаційного контуру. При зміні температури навколишнього середовища від 0 ° С до 40 ° С кількість електроенергії, виробленої за циклом Ренкіна для двигуна Hyundai H25/33 збільшується до 10%. При роботі однієї когенераційної установки з двигуном Hyundai H25/33 та розробленим утилізаційним комплексом можна отримати на добу до 2300 кг конденсату водяної пари, що є дуже цінною в Іраку. На основі результатів дослідження було розроблено два варіанта технологічної схеми (проекти "А" та "Б") модернізації дизельних електростанцій компанії Hyundai Heavy Industries. Виконана техніко-економічна оцінка проектів за метод NPV показала, що після того, як обладнання утилізаційного контуру в повному обсязі буде введено у експлуатацію, максимально досяжний прибуток складе близько 1 406 219 дол. США/рік.

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.05.03 – двигуни та енергетичні установки. – Національний технічний університет "Харківський політехнічний інститут". – Харків, 2017. Дисертація присвячена вибору і обґрунтуванню параметрів дизель-електричної станції з системою утилізації вторинної теплоти дизеля з використанням циклу Ренкіна, що використовує теплоту відпрацьованих газів та системи охолодження. В результаті аналізу особливостей перспективної енергетичної установки з двигуном Hyundai 25/33 для виробництва електричної енергії на заводі в Іраку розроблена технологічна схема комплексної системи утилізації вторинної теплоти дизель-електричної станції з додатковим отриманням електроенергії, теплоти для підігріву важкого палива, конденсації технічної води з відпрацьованих газів двигуна. Для утилізації вторинної теплоти двигуна Hyundai H25/33 запропоновано утилізаційний контур установки, який працює за органічним циклом Ренкіна (ОЦР). В якості робочого тіла в циклі Ренкіна доцільно використовувати воду системи охолодження двигуна. З використанням розробленої математичної моделі утилізаційного контуру дизель-електростанції виконане розрахунково-експериментальне дослідження впливу температури навколишнього середовища на показники ефективності утилізаційного контуру. При зміні температури навколишнього середовища від 0 ° С до 40 ° С кількість електроенергії, виробленої за циклом Ренкіна для двигуна Hyundai H25/33 збільшується до 10%. При роботі однієї когенераційної установки з двигуном Hyundai H25/33 та розробленим утилізаційним комплексом можна отримати на добу до 2300 кг конденсату водяної пари, що є дуже цінною в Іраку. На основі результатів дослідження було розроблено два варіанта технологічної схеми (проекти "А" та "Б") модернізації дизельних електростанцій компанії Hyundai Heavy Industries. Виконана техніко-економічна оцінка проектів за метод NPV показала, що після того, як обладнання утилізаційного контуру в повному обсязі буде введено у експлуатацію, максимально досяжний прибуток складе близько 1 406 219 дол. США/рік.
Dissertation for the degree of candidate of technical sciences in specialty 05.05.03 – engines and power plants. – National Technical University "Kharkiv Polytechnic Institute". – Kharkiv, 2017. The dissertation is devoted to the choice and substantiation of parameters of a diesel power plant with heat recovery system of recycling the secondary heat from diesel engine using the Rankin cycle, which uses the heat of exhaust gases and cooling water systems. As a result of the analysis of the features of a promising power plant with a Hyundai 25/33 engine for the production of electric power at a plant in Iraq, a technological scheme of a comprehensive system for recycling diesel fuel from an electric power station with the additional generation of electricity, heat for heating heavy fuel, condensing technical water from exhaust gases. As a working fluid in the Rankin cycle, it is advisable to use the hot water from the engine cooling system. Using the developed mathematical model of the distillation circuit of the diesel power plant, the design-experimental study of the influence of the ambient temperature on the indicators of the efficiency of heat recovery was performed. When the ambient temperature changes from 0 ° C to 40 ° C, the amount of electric energy generated by the Rankin cycle for the Hyundai H25 / 33 engine increases to 10%. With a single cogeneration unit with a Hyundai H25 / 33 engine and a recycling complex developed, it is possible to get up to 2300 kg of water vapor condensate per day, which is very valuable in Iraq. Based on the results of the study, two variants of the technological scheme (projects A and B) were developed for the modernization of Hyundai diesel power plants. The feasibility study for the NPV method has shown that after the full recovery equipment is put into operation, the maximum achievable profit will be about 1 406 219 $ /year.

An experimental investigation of post-start cold idling behaviour has been carried out on a modern single-cylinder HPCR DI light duty diesel engine with a low compression ratio of 15.5:1 at temperatures between 10 and -20°C. The trend toward lower compression ratios from more common values of around 22:1 a few years ago has resulted in lower compression pressures and temperatures, which negatively affects cold idle operation. Improvements in cycle-by-cycle stability of indicated work output through fuel injection strategy and glow plug temperature changes have been explored. This is important to improve NVH and the consumer’s perception of vehicle quality. The key effects on heat release characteristics have been identified and the associated impact on stability discussed. High speed imaging of ignition in a combustion bomb has been used to aid interpretation of engine results. Up to four pilot injections placed in advance of the main have been used. Shorter separation between pilots and pilot-to-main improves stability independent of the number of pilot injections and extends the range of main injection timings to meet target stability of 10% or lower at -20°C. Increasing the number of pilot injections was effective in stabilising combustion at all investigated soak temperatures at fuelling levels producing indicated work required to match friction and ancillary demands. Stability can be susceptible to deterioration at moderate soak temperatures because fuelling demand is relatively low. If a high number of pilot injections are to be avoided to reduce potential wear, then increasing main injection quantity is an effective method to stabilise combustion for a lower pilot number strategy but any increase above target load has to be harnessed by additional ancillary devices. Very high glow plug temperatures of up to 1200°C were examined using a smaller diameter tip ceramic type design. Stable combustion cannot be achieved through higher glow plug temperatures alone. A temperature of 1000°C, which can be achieved using a low voltage metallic type, is adequate to stabilise combustion when combined with a triple-pilot strategy at sub-zero temperatures. The best stability is achieved using 1200°C, which can only be achieved using a more expensive ceramic type, in combination with a triple-pilot strategy producing the desirable target of ~5% or below; the effects are not mutually exclusive. At high glow plug temperatures and using three or four pilot injections, stability improved with warmer soak temperatures. At -5°C, stability was relatively poor when one or two pilots were used irrespective of glow plug temperature. A high premixed contribution to main combustion is associated with improved stability. Minimum threshold values are necessary to stabilise combustion: ~25 J/° at -20°C, ~20 J/° at -5°C and only ~10 J/° at 10°C. A higher number of pilot injections raises pilot induced combustion and improves mixture distribution. These effects subsequently increase the premixed combustion and help sustain a strong main development with less variability. This benefit is maximised when using hotter glow plug temperatures raising IMEPg magnitude and reducing variation.

This thesis describes research undertaken to establish the advantages and disadvantages of using high pressure common rail fuel injection systems with multiple injection capabilities. The areas covered are detailed as follows. Oscillations in the rail pressure due to the opening of the injector can affect the quantity of fuel injected in subsequent injection events. The source of these oscillations has been investigated. A method of damping or reducing the oscillations has been defined and was applied. This successfully reduced the level of unpredictability of the quantity of injected fuel in subsequent injection events. A relationship between needle lift, injection pressure and the quantity of fuel injected was established. The effects of fuel injection parameters (main injection timing, split main separation and ratio) and engine operating parameters (boost pressure and EGR level) on emissions formations and fuel economy have been investigated at five operating points. Design of Experiments techniques were applied to investigate the effect of variables on pollutant emissions and fuel consumption. The sensitivity and linearity of responses to parameter changes have been analysed to assess the extent to which linear extrapolations will describe changes in smoke number (FSN) and oxides of nitrogen (NOx); and which parameters are the least constricting when it comes to adjustments of parameter settings on the FSN-NOx map. Comparing results for split main and single injection strategies at the five operating conditions shows that split main injection can be exploited to reduce NOx or FSN values at all conditions and both NOx and FSN simultaneously at high load conditions. The influence of changing engine speed and brake mean effective pressure (BMEP) on FSN and NOx emissions with given fixed values of parameter settings has been investigated. This established how much of the operating map could be covered by discrete calibration settings. Finally the variation in parameter settings required to maintain fixed FSN and NOx values across the operating map, near the optimum trade-off on the FSN-NOx map, was analysed. Combining the information gained from the individual investigations carried out highlighted some techniques that can be used to simplify the calibration task across the operating map, while also reducing the amount of experimental testing required.

Дисертація присвячена вивченню особливостей процесів сумішоутворення і згоряння у форсованих дизелях та вибору раціональних параметрів характеристик вприскування палива і форми камери згоряння. Об'єктом дослідження є процеси сумішоутворення та згоряння в судових і тепловозних дизелях типу ЧН25/27, ЧН25/34, ЧН26/34, ЧН26/27 і ЧН32/32. Розглянуті специфіка і особливості процесів сумішоутворення і згоряння у форсованих дизелях. Виявлені основні причини зниження швидкостей випаровування і згоряння збільшених циклових порцій палива і визначені методи і способи узгодження характеристик вприскування палива і форми камери згоряння. Розроблені математична модель циклу дизеля, комплекс програмного забезпечення для розрахунку робочого процесу, в тому числі, характеристик вприскування палива, розподілу палива в струмені та камері згоряння, характеристик сумішоутворення і згоряння. Виконані розрахунково-експериментальні дослідження для погодження характеристик вприскування палива і камер згоряння, які дозволили обгрунтовано вибрати раціональні параметри паливної апаратури, характеристик вприскування палива і форми камери згоряння, що забезпечили зниження експлуатаційної витрати палива в досліджених дизелях на 1,5-3%.
Dissertation is devoted to the study of features of processes formations of working mixture and combustion in the forced diesels and choice of rational parameters of descriptions of injection of fuel and form of combustion chamber. It is a research object judicial Ships and diesel engines diesels of dimension: 25/27, 25/34, 26/34, 26/27 and 32/32. A specific and features of processes of formations of working mixture and combustion is considered in the forced diesels. The found out the principal reasons of decline of speeds of evaporation and combustion of megascopic cyclic portions is fuels and certain methods and methods of concordance of descriptions of injection of fuel and form of combustion chamber. Developed mathematical model of cycle of diesel, complex of software for the calculation of working process, in that number, descriptions of injection of fuel, division of fuel in a stream and combustion, descriptions of formations of working mixture and combustion chamber. Executed calculation-experimental researches for the concordance of descriptions of injection of fuel and chambers combustions, which allowed grounded to choose the rational parameters of fuel apparatus, descriptions of injection of fuel and form of combustion chamber, which provided the decline of operating cost of fuel in the explored diesels on 1,5-3%.

L’hybridation électrique de la chaîne de traction automobile est l’une des solutions adoptées pour respecter les règlementations futures sur ses émissions. La stratégie de supervision de la chaîne de traction hybride répartit la puissance produite par le moteur à combustion interne et la machine électrique. Elle répond habituellement à un problème d’optimisation où l’objectif est de réduire la consommation de carburant mais nécessite à présent d’y ajouter les émissions polluantes. La chaîne de dépollution, placée à l’échappement du moteur, permet de diminuer la quantité de polluants émise dans l’atmosphère. Cependant, elle n’est efficace qu’à partir d’un seuil de température, et dépend de la chaleur apportée par les gaz d’échappement du moteur thermique. La première partie de ce travail est donc consacrée à la modélisation de la consommation énergétique et des émissions polluantes de la chaine de traction hybride. La modélisation de l’efficacité de la chaîne de dépollution est réalisée selon deux contextes. Le modèle zéro-dimensionnel est adapté aux contraintes de calcul de la commande optimale. Le modèle unidimensionnel associé à un estimateur d’état permet d’être embarqué et calculé en temps réel. À partir de ces travaux, la seconde partie de cette thèse déduit des stratégies de supervision à l’aide de la théorie de la commande optimale. Dans un premier cas, le principe de Bellman permet de calculer la commande optimale d’un véhicule hybride Diesel selon des critères de supervision ayant plus ou moins connaissance de l’efficacité de la chaîne de dépollution des émissions de NOX. Dans un second cas, une stratégie issue du Principe du Minimum de Pontryagin, embarquée sur un véhicule hybride essence, fonctionnant en temps réel et calibrée selon deux paramètres est proposée. L’ensemble de ces travaux est validé expérimentalement au banc moteur et montre une réduction significative des émissions polluantes pour une faible pénalité de carburant
Powertrain hybridization is a solution that has been adopted in order to conform to future standards for emissions regulations. The supervisory strategy of the hybrid powertrain divides the power emitted between the internal combustion engine and the electric machine. In past studies, this strategy has typically responded to an optimization problem with the objective of reducing consumption. However, in addition to this, it is now necessary to take pollutant emissions into account as well. The after-treatment system, placed in the exhaust of the engine, is able to reduce pollutants emitted into the atmosphere. It is efficient from a certain temperature threshold, and the temperature of the system is dependent on the heat brought by the exhaust gas of the engine. The first part of this dissertation is aimed at modelling the energy consumption and pollutant emissions of the hybrid powertrain. The efficiency model of the after-treatment system is adapted for use in two different contexts. The zero-dimensional model conforms to the constraints of the optimal control calculation. The one-dimensional model associated with a state estimator can be embedded in a vehicle and calculated in real time. From this work, the second part of this dissertation deduces supervisory strategies from the optimal control theory. On the one hand, Bellman’s principle is used to calculate the optimal control of a Diesel hybrid vehicle using different supervisory criteria, each having more or less information about the after-treatment system efficiency over NOX emissions. On the other hand, a strategy from Pontryagin’s minimum principle, embedded in a gasoline hybrid vehicle, running in real time and calibrated with two parameters, is proposed. The whole of this work is validated experimentally on an engine test bed and shows a significant reduction in pollutant emissions for a slight fuel consumption penalty

Dissertação de mestrado integrado em Engenharia de Materiais
Com o presente trabalho pretendeu-se estudar à escala laboratorial a viabilidade técnica da produção de biodiesel a partir de microalgas, particularmente as microalgas Chlorella Ermersonii (C.E.) e Botryococcus Braunii (B.B.). Para tal foram estudadas e avaliadas as várias etapas que integram o processo de produção nomeadamente o cultivo e o crescimento das microalgas e a extração do óleo por distintas metodologias e técnicas com vista à sua posterior transformação em biodiesel. Os resultados indicam uma extração máxima de 4% de óleo utilizando a Chlorella Ermersonii (C.E.) e 2,5% utilizando a Botryococcus Braunii (B.B.). Devido à reduzida percentagem de óleo obtido nos processos de extração estudados para ambas as espécies de microalgas, não foi possível realizar os ensaios de produção de biodiesel pelo método de transesterificação, conforme foi preconizado nos objetivos da presente dissertação. Paralelamente, foi realizado um estudo relativo à possibilidade de obtenção de óleo e posterior produção de biodiesel quer a partir de algas marinhas da orla costeira da zona Norte de Portugal (Sargaço e Bodelha) quer a partir de oleaginosas, semente de girassol, de amendoim e de abóbora. A produção de biodiesel a partir de óleos alimentares usados e óleos virgens foi igualmente levada a cabo no âmbito do trabalho, por processo de transesterificação básica utilizando o metanol (álcool) e o hidróxido de sódio (catalisador), tendo-se efetuado a sua caracterização e avaliação do cumprimento dos requisitos, de acordo com a norma EN14214. Os resultados obtidos no presente trabalho permitiram concluir que o sistema de cultura semi-aberta das microalgas não se revela eficaz, ao contrário do fotobioreactor o qual assegura as condições operatórias necessárias ao aumento da biomassa. Apesar de as microalgas apresentarem um teor em óleo superior a 40%, a principal limitação da sua utilização como matéria-prima prende-se com as dificuldades técnicas associadas à extração do óleo. Foi assim impossível obter biodiesel a partir destas, considerando os meios técnicos disponíveis no CVR. Relativamente às algas marinhas, nomeadamente o sargaço, pode constituir uma potencial matéria-prima para a produção de biodiesel, tendo sido possível extrair 26% de óleo por extração química, com hexano. Resultados inferiores foram obtidos para a espécie bodelha. Para os óleos alimentares usados e óleos virgens, o rendimento de transformação em biodiesel foi elevado, como evidenciado pelos parâmetros de qualidade. No entanto, os procedimentos experimentais não permitiram a obtenção de óleo virgem diretamente a partir de sementes oleaginosas.
In this work we intended to study laboratory-scale technical feasibility of biodiesel production from microalgae, particularly Chlorella ermersonii (C.E.) and Botryococcus braunii (BB). To achieve project goals, we proceed to study and evaluate the various steps that comprise the process of production, including growing of microalgae and extraction of the oil by different methodologies and techniques, for the further transformation into biodiesel. The results obtained indicate a maximum of 4% extraction of oil using Chlorella ermersonii (C.E) and 2.5% using Botryococcus braunii (B.B.). Due to the small percentage of oil obtained in the extraction processes studied for both species of microalgae, it was not possible to perform tests of biodiesel production trhough the transesterification method, as indicated in the objectives of this dissertation. In parallel, it was studied the possibility of obtaining oil for subsequent production of biodiesel from marine algae from the shoreline in the North of Portugal (Bodelha and Sargasso) either from oilseeds, sunflower seed, peanut and Pumpkin. The production of biodiesel from used cooking oil and virgin oils was also carried out in the work, in both cases, was produced using a basic transesterification process using methanol (alcohol) and sodium hydroxide (catalyst), and the characterization and assessment of compliance in accordance with standard EN14214. The results obtained in this study indicate that the semi-open culture system of microalgae revealed to be not effective, unlike in fotobioreactor, which ensures the operating conditions required to increase the biomass production. Although the present microalgae obtained an oil content exceeding 40%, the major limitation for their use as raw material for production of biodiesel, relates to the technical difficulties associated with oil extraction. It was thus impossible to obtain biodiesel from microalgae, considering the technical means available in the CVR. For the marine algae, in particular Sargasso, it can be a potential feedstock for biodiesel production, being possible to extract 26% of this type of algae oil, using a chemical extraction method, with hexane. Lower results were obtained for the species Bodelha. For cooking oils and as well for virgin oils, the transformation into biodiesel yield was higher, as evidenced by the quality parameters shown. However, the experimental procedures do not allow the production of crude oil directly from the oleaginous seeds.

Dissertação de mestrado integrado em Engenharia Mecânica
O objetivo deste trabalho passa por comparar as prestações de um motor diesel, para um mesmo limite legal de fumos, quando alimentado por gasóleo e biodiesel. Ainda, pretende-se comparar os resultados obtidos, em binário, potência, consumo e rendimento, entre os vários combustíveis utilizados. Inicialmente, é realizada uma análise à literatura, onde se estuda a combustão, sistemas de injeção, e parâmetros de desempenho do motor. Ainda, é feito um estudo a vários combustíveis, entre eles o gasóleo, o biodiesel e o bioóleo, e à forma como estes podem afetar a performance do motor. Entre as propriedades dos combustíveis é abordado o índice de cetano, o poder calorífico, massa volúmica, compressibilidade, lubricidade, entre outros. No que diz respeito à componente prática do trabalho, é feita uma instalação experimental, na qual se cria uma bancada de testes para o motor Peugeot adquirido, juntamente com todos os tipos de ligações necessárias: circuito do líquido de arrefecimento, instalação elétrica do motor e restantes componentes. Numa fase posterior, são apresentados procedimentos para a calibração do freio dinamométrico, procedimentos para testes de lubricidade, de atrito e de viscosidade. O trabalho culmina com os testes do motor em duas fases distintas: motor limitado eletronicamente e motor desbloqueado. Posteriormente é feita a respetiva análise de resultados, tendo em conta os diversos combustíveis utilizados para teste com o motor (gasóleo e três referências distintas de biodiesel). Relatam-se, também, alguns processos de reparação e modificação de alguns componentes do motor.
The objective of this work is to compare the performance of a diesel engine, in the same legal smoke limit, when fueled by diesel and biodiesel. Furthermore, it is intended to compare the results obtained, in torque, power, consumption and efficiency, between the multiple fuels utilized. Initially, a literature survey is made, where the combustion is studied, along with injection systems, and parameters of the engine’s performance. Also, a study is made on different fuels, such as diesel, biodiesel and biooil, and the way how these can affect engine performance. Some of the fuel properties mentioned include the cetane number, heat value, density, compressibility, lubricity, etc. When it comes to practical component of the work, an experimental installation is made, where a test stand for the Peugeot engine is created, as well as all its the connections needed: coolant fluid circuit, electrical circuit. At a later stage, procedures are presented for the calibration of the dynamometer break, for the lubricity tests, for the friction tests and viscosity tests. This work culminates with the tests with the engine in two distinct phases: electronically blocked engine and unblocked engine. Afterwards, a result analysis is made, considering the multiple fuels used (diesel and three different biodieseis as well as its characteristics. It’s also reported some of the reparations and modifications made to components of the engine.

Στο πλαίσιο της παρούσας διπλωματικής εργασίας έγινε μια εκτεταμένη διερεύνηση μέσω προσομοίωσης της συμπεριφοράς ενός συστήματος αποτελούμενο από μηχανή Diesel , σύγχρονη μηχανή εκτύπων πόλων ως γεννήτρια και ασύγχρονη μηχανή δακτυλιοφόρου δρομέα ως κινητήρα. Παρουσιάστηκαν όλες οι τεχνικές που χρησιμοποιούνται στην μοντελοποίηση ενός τέτοιου συστήματος στο περιβάλλον του προγράμματος SIMULINK του MATLAB. Διερευνήθηκαν όλα τα φαινόμενα που λαμβάνουν χώρα κατά την εκκίνηση ενός τέτοιου συστήματος καθώς και οι πιο χαρακτηριστικοί τύποι βραχυκυκλωμάτων που μπορούν να παρουσιαστούν κατά την λειτουργία ενός τέτοιου συστήματος, τόσο κατά την μεταβατική κατάσταση λειτουργίας (Transient state), όσο και κατά την μόνιμη κατάσταση λειτουργίας (Steady state). Ακόμη μελετήθηκε η συμπεριφορά του συστήματος κατά την παύση της λειτουργίας του.
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Dissertação de mestrado integrado em Engenharia Mecânica
Este trabalho tem por objetivo testar o funcionamento de um motor diesel, quando alimentado com biocombustível (biodiesel e/ou outros), de modo a verificar as suas características em termos de potência, consumos, e de emissões gasosas no funcionamento do motor, e do veículo. Num estudo inicial sobre o estado da arte, após uma breve descrição do processo de produção, são analisadas as principais características dos combustíveis bem como o efeito da sua utilização no motor, designadamente no seu desempenho, nos consumos, a compatibilidade com sistemas auxiliares, e emissões poluentes. O biodiesel apresenta menor poder calorífico do que o gasóleo, pelo que ao usar-se os mesmos parâmetros de injeção usados com gasóleo, o resultado é a obtenção de menor binário e menor potência. No entanto, dado que o biodiesel tem maior índice de cetano, o motor poderá apresentar maior rendimento térmico. Uma parte importante deste trabalho é a sua componente prática. Para a realização dos testes foi necessário proceder à adaptação do laboratório, e bastante trabalho em torno de vários motores e diferentes equipamentos. Apesar desta investigação se centrar num tipo de motor diesel, concretamente em motores de 4 cilindros, foi necessário intervir em motores a gasolina (Opel de 4 cilindros, e BMW tricilíndrico) e num motor diesel monocilíndrico (Yanmar), com o qual se efetuou o estudo, mercê das alterações ao objetivo inicial, decorrentes de restrições de vária ordem, que se verificaram no decorrer do projeto. No que concerne ao estudo propriamente dito, são, neste documento, apresentados os resultados obtidos com gasóleo, biodiesel e misturas binárias B25, B50 e B75. Numa análise aos diversos parâmetros estudados, quando comparado com o gasóleo, o B100 apresenta menor binário e menor potência, revelando consumos específicos ligeiramente inferiores aos do gasóleo, em quase todas as velocidades de rotação. Todavia, em termos de rendimento médio o B100 apresenta um rendimento superior ao do gasóleo, sendo o B25 o combustível que apresenta melhores resultados. Quanto às emissões de escape, todos os combustíveis apresentaram valores que excedem o limite de trabalho do equipamento utilizado na medição, e portanto o limite legal, o que poderá sugerir problemas no funcionamento do motor.
This work aims to test the operation of a diesel engine, when fueled with biofuels (biodiesel and/or others), in order to check their characteristics in terms of power, consumption and emissions, in the operation of the engine and of the vehicle. A detailed State of the art study was made. It included not only a brief description of the process of biofuel production and main characteristics, but also the effect of their use in the engine, namely in its performance, consumption, compatibility with auxiliary systems, and pollutant emissions. The biodiesel has lower calorific value than the diesel fuel. When using the same parameters used with diesel fuel injection, the result is obtaining less torque and less power. However, since the biodiesel has higher cetane number, the engine normally displays a greater thermal efficiency. The main part of this work was the experimental comparison of standard Diesel and Biodiesel fuels. To accomplish the tests it was necessary to previously adapt the lab, and a lot of work around different engines and different equipment had to be done. Despite this investigation being focused on a specific type of diesel engine, 4-cylinder engine in particular, in order to accomplish the present work it was necessary to intervene in gasoline engines (4 cylinder Opel and 3 cylinder BMW) and a single-cylinder diesel engine (Yanmar). So, it was necessary to redirect the object of the study defined in the initial goal, due to various types of external constraints, which have occurred during the project. With regard to the study itself, in this document the results obtained with diesel, biodiesel and binary mixtures, B50 and B25 B75 is presented. Considering various parameters studied, when compared with the diesel, the B100 presents lower torque and power, revealing specific consumptions slightly lower than those of diesel, in nearly the whole rotation speed range. However, in average terms, the B100 presents a higher efficiency than diesel, with the B25 fuel showing the best results. With regard to exhaust emissions, all fuels showed a value that exceeds the limit of the equipment used in the measurement, which suggests problems in the operation of the engine.