Littérature scientifique sur le sujet « Scarico diesel »

Today, most motor fuels are made from non-renewable sources of petroleum origin. In connection with the environmental problems associated with the use of traditional motor fuels in motor vehicle engines, many countries are implementing strict requirements for the greening of motor vehicles.At the same time, vehicles with diesel engines are quite attractive in terms of consumption of alternative motor fuels. One of the ways to increase the environmental safety of vehicles with diesel engines is the complete or partial replacement of diesel fuel with alternative fuels. In this regard, research and development in the field of energy resource use in road transport has been significantly intensified, and new programs are being developed to expand the use of alternative fuels. The main focus of the researchers on improving environmental safety is the complete or partial replacement of diesel fuel with alternative fuels, which can be of petroleum or non-petroleum origin. Such fuels can be: liquefied petroleum gas, compressed natural gas and associated gases, diesel biofuel, alcohols and ethers, as well as hydrogen, etc.The article examines the problem of alternative types of fuel and the use of new energy sources in the search for more ecologically clean, cheap and less scarce fuel. To solve this problem, it is necessary to perform an analysis and determine the possibilities of increasing the environmental safety of motor vehicles with diesel engines when using different alternative fuels.The analysis carried out in the work showed that the considered fuels are promising with the proper organization of the work process of motor vehicle diesel engines. However, in a number of cases, for example, when using hydrogen, alcohols, it is necessary to significantly change the design of the engine, which requires significant costs. The use of alternative, more environmentally friendly motor fuels, such as compressed natural gas, diesel biofuel of vegetable or animal origin, etc., will allow to significantly expand the fuel base of motor vehicle diesels and does not require a significant change in their design.In further research, an important task is to develop a methodology for evaluating the use of alternative fuels, which will combine a complex of functional and mathematical models to determine the energy efficiency and environmental safety of vehicles with diesel engines when using alternative fuels both in their pure form and in the form of mixed fuels.

To predict the performance of a diesel engine, current practice relies on the use of black-box identification where numerous experiments must be carried out in order to obtain numerical values for model training. Although many diesel engine models based on artificial neural networks (ANNs) have already been developed, they have many drawbacks such as local minima, user burden on selection of optimal network structure, large training data size and poor generalization performance, making themselves difficult to be put into practice. This paper proposes to use extreme learning machine (ELM), which can overcome most of the aforementioned drawbacks, to model the emission characteristics and the brake-specific fuel consumption of the diesel engine under scarce and exponential sample data sets. The resulting ELM model is compared with those developed using popular ANNs such as radial basis function neural network (RBFNN) and advanced techniques such as support vector machine (SVM) and its variants, namely least squares support vector machine (LS-SVM) and relevance vector machine (RVM). Furthermore, some emission outputs of diesel engines suffer from the problem of exponentiality (i.e., the output y grows up exponentially along input x) that will deteriorate the prediction accuracy. A logarithmic transformation is therefore applied to preprocess and post-process the sample data sets in order to improve the prediction accuracy of the model. Evaluation results show that ELM with the logarithmic transformation is better than SVM, LS-SVM, RVM and RBFNN with/without the logarithmic transformation, regardless the model accuracy and training time.

Biodiesel are extracted from transesterification process of edible and non-edible oil of vegetable and animal fat. It can be used in the diesel engine either in the form of neat oil or as a mixture of diesel fuel in the form of blend. The properties of oil are compared with the characteristic required for the fuel of internal combustion engine and the properties fuel are compared with conventional diesel fuel. Use of bio-diesel in a conventional diesel engine results in substantial reduction in unburned hydrocarbon (UBHC), carbon monoxide (CO), particulate matters (PM) emission and oxide of nitrogen. The blends of biodiesel with small content in place of petroleum diesel can help in controlling air pollution and easing the pressure on scarce resources without significantly sacrificing engine power and economy.

Abstract The world has been experiencing a crisis of energy caused by the deterioration of scarce fossil fuel resources. The usage of fossil fuels, mainly liquid fuels is considered unsustainable due to resource depletion and the accumulation of pollutants. Natural gas has become a promising alternative fuel since it is highly abundant in the world, produces less emission, and gives similar engine performance compared to the existing liquid fuel, diesel, or gasoline. This paper presents various research regarding the engine performance characteristic of CNG. The studies reported that as compared to liquid-based fuel such as diesel oil or gasoline, CNG gives lower brake thermal efficiency (BTE) as compared to diesel fuel. However, the brake-specific fuel consumption (BSFC) of engine fueled with CNG is lower than diesel or gasoline fuel. In terms of exhaust gas temperature, CNG was always produced higher temperatures in comparison to gasoline. The maximum cylinder gas pressure of CNG was reported lower than diesel fuel operation. In general, the power produced by CNG combustion is a little bit lower than diesel fuel, this drawback of CNG fuel can be overcome by adding hydrogen fuel to CNG to increase produced power.

Biodiesel plays a major role as one of the alternative fuel options in direct injection diesel engines for more than a decade. Though many feed stocks are employed for making biodiesel worldwide, biodiesel derived from domestically available non-edible feed stocks such as Jatropha curcas L. is the most promising alternative engine fuel option especially in developing countries. Since experimental analysis of the engine is pricey as well as more time consuming and laborious, a theoretical thermodynamic model is necessary to analyze the performance characteristics of jatropha biodiesel fueled diesel engine. There were many experimental studies of jatropha biodiesel fueled diesel engine reported in the literature, yet theoretical study of this biodiesel run diesel engine is scarce. This work presents a theoretical thermodynamic study of single cylinder four stroke direct injection diesel engine fueled with biodiesel derived from jatropha oil. The two zone thermodynamic model developed in the present study computes the in-cylinder pressure and temperature histories in addition to various performance parameters. The results of the model are validated with experimental values for a reasonable agreement. The variation of cylinder pressure with crank angle for various models are also compared and presented. The effects of injection timing, relative air fuel ratio and compression ratio on the engine performance characteristics for diesel and jatropha biodiesel fuels are then investigated and presented in the paper.

Escalation fuel consumption occurs in various regions of the world. However, world oil reserves decline from year to year so that it becomes scarce and causes oil prices to surge up. This problem can be solved by saving fuel consumption. One method of saving fuel is adding bio-additives from citronella oil as a sustainable resource to diesel fuels. Citronellal, citronellol and geraniol are the main components of citronella oil which can be used as fuel additives. This study aimed to evaluate the effect of citronella oil fractions as bio-additives to the performance of diesel engine. The research stages include: extraction of citronella oil, vacuum fractionation of citronella oil, physical chemical characterization of citronella oil and its fractions, formulation of bio-additive -fuel blending, characterization of blending, and evaluation of fuel efficiency. The effect of concentration of the bio-additives was examined towards three diesel fuels; dexlite, pertamina-dex, and biosolar. The results showed two main fractions of citronella oil; citronellal dominant component (FA) and citronellol-geraniol dominant components (FB). The concentration variation of bio-additives was 0.1–0.5%. Fuel consumption efficiency was tested using diesel engine at an engine speed of 2000 rpm and a load increment of 1000, 2000 and 3000 psi with 7 min running time. The fractions represented the different tendencies to enhance the fuel efficiency up to 46%, influenced by the mixture’s concentration. Generally, citronella oil and the fractions showed the potency as bio-additive to diesel fuels.

Zusammenfassung Zusammenfassung Bei demenziellen Erkrankungen können die sprachlichkommunikativen Fähigkeiten in variabler Art betroffen sein. Trotzdem fehlen im deutschsprachigen Raum geeignete Standardverfahren zur Diagnostik dieser kognitiven Kommunikationsstörungen. Diese Studie beschäftigt sich mit der Erprobung der Anwendbarkeit des MEC-Tests bei dieser Zielgruppe. 16 Patient*innen mit MCI oder leichtgradiger Demenz wurden mit der CERAD Batterie und mit dem MECTest getestet. Bei 94,1% war der MEC-Test durchführbar. Die Durchführungsdauer von durchschnittlich 72,7 Minuten stand nicht im Zusammenhang mit der CERAD. Die Durchführungsdauer unterschied sich zwischen Patienten mit neurodegenerativer vs. affektiver Genese. Jede/r Patient*in zeigte in durchschnittlich 9 Untertests einen Wert unter dem klinischen Trennwert. Die Leistung im MEC stand in Zusammenhang mit der CERAD. Insgesamt wurden sieben der 14 MEC-Untertests aufgrund von Bodeneffekten oder fehlenden Zusammenhängen mit der CERAD als ungeeignet für die Zielgruppe identifiziert. Zusammenfassend ließ sich eine Auswahl an Subtests des MEC-Testverfahren bei dieser Zielgruppe gut anwenden. Schlüsselwörter: Diagnostik, Demenz, Mild Cognitive Impairment (MCI), Logopädie/Sprachtherapie, kognitive Kommunikationsstörung Abstract Dementia is associated with language and communication deficits. However, standardized diagnostic instruments for the assessment of communication disorders for this population are scarce. Therefore, the present study explores whether the Montreal Evaluation of Communication (MEC) test can be applied to persons with dementia or mild cognitive impairment (MCI). Sixteen patients were tested with the (CERAD) and MEC tests. The MEC test could be completely administered in 94.1%. The average duration of 72.7 minutes was not correlated with the Consortium to Establish a Registry for Alzheimer's Disease CERAD score but differed between neurodegenerative vs. affective etiology. Patients showed language/communication deficits in 9 of the MEC sub-tests. Average performance on the MEC test was correlated with the CERAD score. Seven of the 14 MEC subtests were identified as unsuitable for dementia or MCI because of floor effects in performance or poor association with the CERAD. To conclude, the MEC test can be administered to patients with dementia or MCI, particularly a selection of a sub-set of 14 tests. Keywords: diagnostics, dementia, mild cognitive impairment (MCI), speech-language therapy, cognitive communication disorder

Recently, modeling and simulation of the diesel production process via Fischer Tropsch (FT) have been the subject of study by several re-searchers. However, studies involving the optimiza-tion of FT technology are scarce, principally pro-cesses involving Fixed Bed Reactors (FBR). The present work aims to simulate and optimize a multi-tubular FT FBR in which the goal is to maximize the diesel production. In this way, the modeling, simulation and optimization of FT process were proposed. The reactor model is based on the one-dimensional pseudo-homogeneous model in which mass and energy balances were taken into account. The resultant ordinary differential equation system was solved by the use of the Adams Moulton meth-od, while the Interior Point method was used for the optimization step. The algorithm was then imple-mented into the Scilab solver. Several case studies were performed, evidencing that the temperature of the cooling fluid and H2/CO ratio fluid significantly impacts the conversion of the reaction.

Progettazione di un motore Diesel 2 tempi sulla base commerciale di un TM100Kb a benzina di derivazione karting. Il motore è capace di 5kW di potenza ad un peso contenuto. La progettazione è orientata agli aspetti sia termodinamici che dinamici. Si effettua una serie di verifiche per capire l'efficienza e l'uso di componenti originali.

L'inquinamento atmosferico rimane un problema globale per il 21 °secolo, in quanto causa di malattie cardiovascolari e respiratorie. È urgente stabilire il reale impatto del particolato (PM) sulla salute umana includendo l'analisi delle fonti, la distribuzione delle dimensioni, la composizione fisico-chimica (P-chem) e i meccanismi tossicologici. L'aumento dei dati in vitro per stabilire i meccanismi di tossicità utilizzando linee cellulari umane esposte a specifici inquinanti atmosferici da fonti di emissione rigorosamente caratterizzate, potrebbe aiutare a validare approcci scientifici nella caratterizzazione dei rischi per la salute, che alla fine possono determinare azioni normative potenzialmente più efficaci per proteggere la salute pubblica. Lo scopo di questa tesi è stato quello di studiare gli effetti in vitro delle particelle emesse da diverse fonti di combustione utilizzando cellule polmonari umane, concentrandosi sulla relazione tra le caratteristiche P-chem del PM e i processi cellulari e molecolari che inducono la tossicità. Sono stati utilizzati modelli in vitro rappresentativi del sistema respiratorio umano per studiare la bio-interazione e gli effetti tossicologici delle particelle. Sono state confrontate diverse particelle derivate da combustione, con particolare attenzione alle particelle fini e ultrafini (UFPs), ovvero le particelle emesse allo scarico di veicoli di vecchia e nuova generazione diesel (DEP) e alle particelle emesse dalla combustione di biomassa solida per il riscaldamento residenziale. Le emissioni dei veicoli e delle stufe a biomasse, così come la raccolta del PM, sono state eseguite in collaborazione con INNOVHUB SSI (Area Combustibili), mentre la caratterizzazione P-chem e gli studi tossicologici sono stati effettuati presso il Dipartimento di Scienze della Terra e dell'Ambiente (DISAT) - Centro di ricerca POLARIS (Polveri in Ambiente e Rischio per la Salute) e presso l'Unità Consumer Products Safety del Centro Comune di Ricerca della Commissione Europea. I risultati di questo lavoro mostrano che testare diversi materiali campionati in condizioni realistiche consente di valutare come la tossicità delle particelle possa variare in relazione alla fonte. Questi dati suggeriscono che lo stress ossidativo e il rilascio di citochine infiammatorie sono eventi cruciali dopo l'esposizione a DEP, che possono anche portare all'attivazione dell’endotelio vascolare. Confrontando un veicolo diesel di vecchia generazione senza DPF (Diesel Particulate Filter) e uno di ultima generazione (o “Euro 6”) durante la rigenerazione del DPF abbiamo dimostrato che il DEP Euro 6 determina una minore risposta biologica, ed è caratterizzato da diversa composizione metallica e minore concentrazione di Idrocarburi Policiclici Aromatici (IPA) rispetto a quello emesso allo scarico del veicolo di vecchia generazione, sebbene le emissioni da Euro 6 durante la rigenerazione del DPF siano caratterizzate da un maggior numero di particelle in modalità nucleazione. Il DEP emesso da un veicolo diesel di vecchia generazione si è confermato essere un componente molto pericoloso del PM urbano, anche rispetto alle particelle derivate dalla combustione (CDPs) di legna. Tuttavia, non si devono escludere possibili conseguenze sulla salute umana derivanti dall'esposizione cronica alle CDPs da biomassa. Inoltre, sono stati valutati anche gli effetti della co-esposizione di nanoparticelle di ossido di metallo (NPs), rappresentative dell’inquinamento non combustivo in miscela con DEP. La co-esposizione con DEP può ridurre la tossicità delle NPs o aumentarla. Questo risultato indica che è necessario valutare la possibile interazione di diverse particelle pericolose presenti in atmosfera e la tossicità derivante dagli effetti della loro miscela.
Due to cardiovascular and respiratory diseases, air pollution remains a global issue for the 21st century. There is an urgent need to establish the real impact of Particulate Matter (PM) on human health by including the analysis of sources, size distribution, physico-chemical (P-chem) composition, and toxicological mechanisms. Increasing in vitro data for establishing pathways of toxicity in human cell lines exposed to specific air pollutants from rigorously characterized emission sources, could help to improve scientifically sound approaches in health risk characterizations, which finally may result in regulatory actions potentially more effective to protect public health. The aim of this thesis was to study the in vitro effects of particles emitted from different combustion sources using human lung cells, focusing on the relationship between the PM P-chem attributes and the cellular and molecular pathways that drive the toxicity. In vitro models, representative of the human respiratory system, were used to study the bio-interaction and toxicological effects of particles. Different exhaust particles were compared, with special emphasis on fine and ultrafine Particles (UFPs), namely Diesel exhaust particles (DEPs) from old and new generation vehicles and on particles emitted from the combustion of solid biomass fuels for residential heating. The emissions from vehicles and biomass-propelled stoves, as well as the PM collection, were performed in collaboration with INNOVHUB SSI (Fuels Department), while the P-chem characterization and toxicological studies were carried out in the Department of Earth and Environmental Sciences (DISAT)- POLARIS research centre (Polveri in Ambiente e Rischio per la Salute) and at the Consumer Products Safety Unit of the European Commission's Joint Research Centre. The results of this work show that testing different material sampled in realistic conditions allows evaluating how the toxicity of particles may vary in relation to the source. These data suggest that oxidative stress and inflammatory cytokines releases are crucial events after DEP exposure, which can also lead to vascular endothelial activation. Comparing an old generation diesel vehicle without DPF (Diesel Particulate Filter) and last generation (or “Euro 6”) one during regeneration of DPF, we proved that Euro 6 is less powerful in activating the biological response, and it is characterized by different metal composition and less concentration of Polycyclic Aromatic Hydrocarbons (PAHs) than the old generation engine, although the exhaust emission from Euro 6 during DPF regeneration is characterized by a higher number of nucleation-mode particles. DEP emitted from an old generation diesel vehicle was confirmed as a very hazardous component of the urban PM, even when compared to Combustion derived particles (CDPs) from wood burning. However, the possible consequences on human health from chronic exposure to the wood CDPs should not be excluded. Moreover, the co-exposure effects of Metal Oxide Nanoparticles (NPs), representative of non-exhaust sources, and DEP were also evaluated. The co-exposure with DEP can either reduce the toxicity of NPs or enhance it. This finding indicates that the possible interaction of different hazardous airborne particles and the toxicity deriving from the mixture effects should be evaluated.

In uno scenario climatico sempre più preoccupante e nel panorama di una nuova crisi energetica, la ricerca tecnologica spinge nella direzione di metodi per aumentare l’efficienza dei sistemi energetici. Ad oggi, un motore alternativo a combustione interna converte in energia meccanica e/o elettrica il 30-45% dell’ energia disponibile nel carburante. Il resto è scartato sotto forma di calore, nella maggior parte nei gas esausti e nell’acqua di raffreddamento. Prendendo in esame un veicolo pesante, il 30% dell’energia disponibile al carburante è persa nei gas esausti. Oltre questo, i veicoli pesanti sono responsabili del 5.6% delle emissioni totali di gas ad effetto serra nell’UE. L’energia di scarto può essere recuperata tramite le tecniche di recupero di energia (Waste Heat Recovery). Obiettivo di questo lavoro di tesi è uno studio di modellazione termodinamica di un ciclo ORC (Organic Rankine Cycle) per il recupero di calore di scarto da un motore Diesel per applicazioni heavy-duty. Per valutare il potenziale del calore contenuto nei gas esausti, le condizioni operative di un reale motore Diesel pesante sono state utilizzate per definire le condizioni al contorno. Un modello GT-Power di tale motore è stato precedentemente sviluppato ed integrato, in questo studio, con un modello di sistema di post-trattamento dei gas esasusti in uscita dal turbocompressore. I tre componenti del PT (DOC, DPF, SCR), calibrati da lavori precedenti, sono stati utilizzati per lo scopo di questa tesi. Successivamente è stato modellato il ciclo ORC analizzando il comportamento e le performance di esso utilizzando tre fluidi organici diversi: due appartenenti alla famiglia dei refrigeranti (R245fa e R123) e un silossano MDM. I risultati ottenuti dalle simulazioni hanno evidenziato come è possibile arrivare ad una riduzione rispettivamente del 1.5%, 1.6% e 0.8% del BSFC del motore calcolati in un punto operativo stazionario a 2400 RPM per i tre fluidi considerati.

Each year policymakers around the world must make hard decisions about how to allocate scarce health care resources. Given the scarcity of many life-saving interventions, making allocation decisions entails determining who lives and who dies. One relevant aspect of such allocation decisions concerns the relative importance of death at different ages. The purpose of this chapter is to explore this issue by examining three age-specific allocation principles and their underlying moral foundations: a youngest first principle, prioritizing infants; a children first principle, prioritizing children; and a young adults first principle, prioritizing adolescents and young adults. My claim is that a youngest first principle can draw support from the Deprivation Account, a children first principle can draw support from a gradualist view, and a young adult first principle can draw support from the Complete Lives Account. I conclude, tentatively, that gradualism and children first allocation should be our favored choice.

Oil exploration in Brazil is mainly held by offshore platforms which require the supply of several products, including diesel to maintain its engines. One strategy to supply diesel to the platforms is to keep a vessel filled with diesel nearby the exploration basin. An empty boat leaves the port and goes directly to this vessel, then it is loaded with diesel. After that, it makes a trip to supply the platforms and when the boat is empty, it returns to the vessel to be reloaded with more diesel going to another trip. Based on this description, this paper proposes a mathematical model based on the Vehicle Routing Problem with Intermediate Replenishment Facilities (VRPIRF) to solve the problem. The purpose of the model is to plan the routes for the boats to meet the diesel requests of the platform. Given the fact that in the literature, papers about the VRPIRF are scarce and papers about the VRPIRF applied to offshore platforms were not found in the published papers, this paper is important to contribute with the evolution of this class of problem, bringing also a solution for a real application that is very important for the oil and gas business. The mathematical model was tested using the CPLEX 12.6. In order to assess the mathematical model, tests were done with data from the major Brazilian oil and gas company and several strategies were tested.DOI: http://dx.doi.org/10.4995/CIT2016.2016.2217

The use of biodiesel substantially reduces particulate matter (PM), hydrocarbon (HC) and carbon monoxide (CO) emissions, slightly reduces power output; increases fuel consumption and marginally increases oxides of nitrogen (NOx) emission in an unmodified common rail direct injection (CRDI) diesel engine. Lower blends of biodiesel demonstrated lower emissions, while easing pressure on scarce petroleum resources, without significantly sacrificing engine power output and fuel economy. However due to adverse health effects of smaller size particulate matter (PM) emitted by internal combustion (IC) engines, most recent emission legislations restrict the PM mass emissions in addition to total particle numbers emitted. It is an overwhelming argument that usage of biodiesel leads to reduction in PM mass emissions. In this paper, experimental results of PM emissions using Karanja biodiesel blends (KB20 and KB40) in a modern CRDI transportation engine (maximum fuel injection pressure of 1600 bar) have been reported. This study also explores comparative effect of varying engine speed and load on PM emissions for biodiesel blends vis-à-vis baseline mineral diesel. Particulate size-number distribution, particle size-surface area distribution and total particulate number concentrations were experimentally determined under varying engine operating conditions and compared with baseline mineral diesel. KB20 showed highest particulate number concentration upto 80% rated engine loads, however at rated load, KB40 emitted highest number of particulates.

Dual-fuel reactivity-controlled compression ignition (RCCI) combustion using port injection of a less reactive fuel and early-cycle direct injection of a more reactive fuel has been shown to yield both high thermal efficiency and low NOX and soot emissions over a wide engine operating range. Conventional and alternative fuels such as gasoline, natural gas and E85 as the lower reactivity fuel in RCCI have been studied by many researchers; however, published experimental investigations of hydrous ethanol use in RCCI are scarce. Making greater use of hydrous ethanol in internal combustion engines has the potential to dramatically improve the economics and life cycle carbon dioxide emissions of using bio-ethanol. In this work, an experimental investigation was conducted using 150 proof hydrous ethanol as the low reactivity fuel and commercially-available diesel as the high reactivity fuel in an RCCI combustion mode at various load conditions. A modified single-cylinder diesel engine was used for the experiments. Based on previous studies on RCCI combustion by other researchers, early-cycle split-injection strategy of diesel fuel was used to create an in-cylinder fuel reactivity distribution to maintain high thermal efficiency and low NOX and soot emissions. At each load condition, timing and mass fraction of the first diesel injection was held constant, while timing of the second diesel injection was swept over a range where stable combustion could be maintained. Since hydrous ethanol is highly resistant to auto-ignition and has large heat of vaporization, intake air heating was needed to obtain stable operations of the engine. The study shows that 150 proof hydrous ethanol can be used as the low reactivity fuel in RCCI through 8.6 bar IMEP and with ethanol energy fraction up to 75% while achieving simultaneously low levels of NOX and soot emissions. With increasing engine load, less intake heating is needed and EGR is required to maintain low NOX emissions. Future work will look at stability of hydrous ethanol RCCI at higher engine load.

Access to electricity is a key necessity in today’s World for economic growth and improvements in quality of life. However, the global challenge is addressing the so-called Energy Trilemma: how to provide secure, affordable electricity while minimizing the impact of power generation on the environment. The rapid growth in power generation from intermittent renewable sources, such as wind and photovoltaics, to address the environmental aspect has created additional challenges to meet the security of supply and affordable electricity aspects of this trilemma. Fossil fuels play a major role in supporting intermittent renewable power generation, rapidly providing the security of supply needed and ensuring grid stability. Globally diesel or other fuel oils are frequently used as the primary fuel or back-up fuel for fossil-fueled power generation plants at all scales, from a few kiloWatts to hundreds of MegaWatts, and helps provide millions of people with secure electricity supplies. But diesel is a high polluting fuel, emitting high levels of carbon dioxide (CO2) per unit of fuel input compared to natural gas, as well as high levels of combustion contaminants that are potentially hazardous to the local environment and human health. Additionally, diesel can be a high cost fuel in many countries, with imports consuming significant portions of sometimes scarce foreign currency reserves. Most observers consider that natural gas is the ‘fuel of choice’ for fossil power generation due to its reduced CO2 emissions compared to coal and diesel. However, access to gas supplies cannot be guaranteed even with the increased availability of Liquefied Natural Gas (LNG) and Compressed Natural Gas (CNG). Additionally where natural gas is available, operators may opt for an interruptible gas supply contract which offers a lower tariff than a firm gas supply contract, therefore there is a need for a back-up fuel to ensure continuous power supplies. While traditionally diesel or Heavy Fuel Oil (HFO) has been used as fuel where gas is not available or as a back-up fuel, propane offers a cleaner and potentially lower cost alternative. This paper compares the potential economic, operational and environmental benefits of using propane as a fuel for gas turbine-based power plants or cogeneration plants.

In light of the potential of butanol as an alternative fuel for blending with petroleum fuels such as gasoline, diesel or Jet A, experimental data regarding the burning characteristics of these blends are required in order to better understand their combustion process. In this study, freely-falling droplets of butanol, Jet A, and their mixtures (10, 20 and 50% butanol by volume) were examined in a combustion chamber which provides representative conditions of real flames, both in terms of temperature and oxygen availability. The combustion characteristics reported here include evolution of droplet sizes, burning rates, soot measurements, and the occurrence of microexplosions and soot shells. Results show that the evolution of droplet diameter for butanol, Jet A and their blends are very similar, regardless of the obvious compositional differences. Sooting behaviors are found to be quite different, with a clear reduction in the sooting propensity as the butanol content in the fuel increases. These results are consistent with a previous study in a gas turbine showing similar performance among Jet A and its blends with butanol, suggesting that such mixtures are promising alternative fuels with very similar combustion characteristics to Jet A, but with much less propensity to soot. Moreover, this study provides new results on the combustion properties of Jet A/butanol blends, for which very scarce data exist in the open literature.

There is currently a sustained interest in biofuels as they represent a potential alternative to petroleum derived fuels. Biofuels are likely to help decrease greenhouse gases emissions and the dependence on oil resources. Biodiesels are Fatty Acid Methyl Esters (FAMEs) that are mainly derived from vegetable oils; their compositions depend from the parent vegetables: rapeseed (“RME”), soybean (“SME”), sunflower, palm etc. A fraction of biodiesel has also an animal origin (“tallow”). A key factor for the use of biofuels in gas turbines is their Emissions Indices (NOx, CO, VOC, PM) in comparison with those of conventional “petroleum gasoils”. While biodiesels reduce carbon-containing pollutants, experimental data from diesel engines show a slight increase in NOx. The literature relating to gas turbines is very scarce. Two recent, independent field tests carried out in Europe (RME) and in the USA (SME) showed slightly lower NOx while a lab test on a microturbine showed the opposite effect. To clarify the NOx index of biodiesels in gas turbines, a study has been undertaken, taking gasoil and natural gas (NG) as reference fuels. In this study, a calculation of the flame temperature developed by the 3 classes of fuels has been performed and the effect of their respective compositions has been investigated. The five FAMEs studied were RME, SME and methyl esters of sunflower, palm and tallow; these are representative of most widespread vegetable and animal oil bases worldwide. The software THERGAS has been used to calculate the enthalpy and free energy properties of the fuels and GASEQ for the flame temperature (Tf), acknowledging the fact that “thermal NOx” represents the predominant form of NOx in gas turbines. To complete the approach to structural effects, we have modeled two NG compositions (rich and weak gas) and three types of gasoil using variable blends of eleven linear/branched/cyclic molecules. The results are consistent with the two recent field tests and show that the FAMEs lie close to petroleum gasoils and higher than NG in terms of NOx emission. The composition of the biodiesel and regular diesel fuel influences their combustion heat: methyl esters with double bonds see a slight increase of their Tf and their NOx index while that of gasoil is sensitive to the aromatic content.

An electric compressor and an electrically assisted turbocharger have been applied to a 2.0L Gasoline and a 2.2L Diesel engine 1D wave dynamic models. A novel approach is presented for evaluating transient response using swept frequency sine wave functions and Fourier Transforms. The maximum electrical power was limited to 6% of the maximum engine power (12kW and 5kW respectively). The systems were evaluated under steady state and transient conditions. Steady state simulations showed improved Brake Mean Effective Pressure (BMEP) at low engine speeds (below 2500rpm) but electric power demand was lower (3kW vs 8kW) when the electric compressor was on the high pressure side of the turbocharger. This was due to the surge limitation of the turbocharger compressor. The electrically assisted turbocharger offered little opportunity to increase low speed BMEP as it was constrained by compressor map width. Re-matching the turbo could address this but also compromise high engine speeds. BMEP frequency analysis was conducted in the region of 0.01–2Hz. This was repeated at fixed engine speeds between 1000rpm and 2000rpm. Spectral analysis of the simulated response showed that the non-assisted turbocharger could not follow the target for frequencies above 0.1Hz whereas the electrically-assisted device showed no appreciable drop in performance. When assessing the electric power consumption with the excitation frequency, a linear trend was observed at engine speeds below 1500rpm but more complex behavior was apparent above this speed where BMEP levels are high but exhaust energy was scarce.

Many investigations are currently carried out in order to reduce CO2 emissions in power generation. Among alternative fuels to natural gas and gasoil in gas turbine applications, dimethyl ether (DME; formula: CH3-O-CH3) represents a possible candidate in the next years. This chemical compound can be produced from natural gas or coal/biomass gasification. DME is a good substitute for gasoil in diesel engine. Its Lower Heating Value is close to that of ethanol but it offers some advantages compared to alcohols in terms of stability and miscibility with hydrocarbons. While numerous studies have been devoted to the combustion of DME in diesel engines, results are scarce as far as boilers and gas turbines are concerned. Some safety aspects must be addressed before feeding a combustion device with DME because of its low flash point (as low as −83°C), its low auto-ignition temperature and large domain of explosivity in air. As far as emissions are concerned, the existing literature shows that in non premixed flames, DME produces less NOx than ethane taken as parent molecular structure, based on an equivalent heat input to the burner. During a field test performed in a gas turbine, a change-over from methane to DME led to a higher fuel nozzle temperature but to a lower exhaust gas temperature. NOx emissions decreased over the whole range of heat input studied but a dramatic increase of CO emissions was observed. This work aims to study the combustion behavior of DME in gas turbine conditions with the help of a detailed kinetic modeling. Several important combustion parameters, such as the auto-ignition temperature (AIT), ignition delay times, laminar burning velocities of premixed flames, adiabatic flame temperatures, and the formation of pollutants like CO and NOx have been investigated. These data have been compared with those calculated in the case of methane combustion. The model was built starting from a well validated mechanism taken from the literature and already used to predict the behavior of other alternative fuels. In flame conditions, DME forms formaldehyde as the major intermediate, the consumption of which leads in few steps to CO then CO2. The lower amount of CH2 radicals in comparison with methane flames seems to decrease the possibility of prompt-NO formation. This paper covers the low temperature oxidation chemistry of DME which is necessary to properly predict ignition temperatures and auto-ignition delay times that are important parameters for safety.

Gasoline Direct Injection (GDI) systems have become a rapidly developing technology taking up a considerableand rapidly growing share in the Gasoline Engine market due to the thermodynamic advantages of direct injection. The process of spray formation and propagation from a fuel injector is very crucial in optimizing the air-fuel mixture of DI engines. Previous studies have shown that the presence of some cavitation in high-pressure fuel nozzles can lead to better atomization of the fluid. However, under some very specific circumstances, high levels of cavitation can also delay the atomization process; spray stabilization due to hydraulic flip is the most well-known example. Therefore, a better understanding of cavitation behavior is of vital importance for further optimization of next generation fuel injectors.In contrast to the abundance of investigations conducted on the inner flow and cavitation patterns of diesel injectors, corresponding in-depth research on the inner flow of gasoline direct-injection nozzles is still relatively scarce. In this study, the results of an experiment performed on real-size GDI injector nozzles made of acrylic glass are presented. The inner flow of the nozzle is visualized using a high-power pulsed laser, a long-distance microscope and a high- speed camera. The ambiguity of dark areas on the images, which may represent cavitation regions as well as ambient air drawn into the nozzle holes, is resolved by injecting the fuel both into a fuel or gas filled environment. In addition, the influence of backpressure on the transient flow characteristics of the internal flow is investigated. In good agreement with observations made in previous studies, higher backpressure levels decrease the amount of cavitation inside the nozzles. Due to the high temporal and spatial resolution of the experiment, the transient cavitation behavior during the opening, quasi-steady and closing phases of the injector needle motion can be analyzed. For example, it is found that cavitation patterns oscillate with a characteristic frequency that depends on the backpressure. The link between cavitation and air drawn into the nozzle at the beginning of injection is alsorevealed.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4639

Abstract Huge power consumers provide many opportunities for huge savings. Floating rig saving 8000 liters of diesel per day? Saving 17 tonnes of CO2 per day? Those numbers are now realistic figures and not some far away dream. Reducing emissions, the industry cannot escape from taking this message to heart and so the search for the right technology, specifically for the Oil industry, has started. In fact the search started quite a while ago and many companies have used their scarce R&D budgets to develop the solution that helps the industry achieve its goals. Budgets for developing ‘green’ technologies during an all-time low in the industry, with as bonus a global pandemic on top of it, has been challenging. But isn't it that in hard times the creative minds step up to come with the best ideas? If pressure makes diamonds, then developing ideas into products without proper budgets and resources, must have led to some breakthrough technology to save the earth. Together with our customers, NOV certainly has risen to the challenge and now has a wide range of technologies that provide a solution to a part of the puzzle. Combined these solution show the complete picture of what is possible. So what was the approach? As with many technical challenges, there is not a single solution providing the answer, so when focusing on the issue at hand; ‘how can we help reduce emissions on drilling rigs’, NOV took on a big challenge and approached it at a granular level; breaking down the problem into smaller problems, then breaking down the smaller problems in manageable challenges. To start this all, that in order to reduce emissions, you need to know what causes these emission, where do they come from and how are they affected by location, type of operation, equipment used, people operating the drilling equipment, etc, etc. To tackle the problem three major areas are focused on; what are the consumers for the drilling package (consumption), how efficient are these consumers being operated and what technology can be applied to lower fuel consumption