Browse Topic: Ethanol

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Breathalyzer Detects MarijuanaTBMG-359712/1/2020
As recreational marijuana legalization becomes more widespread in the U.S., so has concern about what that means for enforcing driving-under-the-influence (DUI) laws. Unlike a breathalyzer used to detect alcohol, police do not have a device that can be used in the field to determine if a driver is under the influence of marijuana.
Testing of Elastomer Icephobic Coatings in the AIWT: Lessons Learned2019-01-19946/10/2019
A study has been conducted into icephobic properties of some highly durable “off-the-shelf” elastomer materials using a rotating ice adhesion test rig installed in the NRC’s Altitude Icing Wind Tunnel. This enabled the formation of ice at environmental conditions similar to those experienced during in-flight icing encounters. Initially, the tests indicated some very positive results with ice adhesion shear stress as low as 8KPa. On further examination, however, it became apparent that the test preparation process, in which the samples were cleaned with an ethanol alcohol solution, influenced the results due to absorption and prolonged retention of the cleaning fluid. The uptake of the ethanol alcohol solution by the elastomer was found to be a function of the surface temperature and remained absorbed into the coating during the ice accretion process changing the characteristics of the coating in such a way that led to a reduction in the ice/surface bond strength.
Orchard, David, Chevrette, Gislain, Maillard, Damien, Khoun, Lolei
Stretchable Interlaced-Nanowire Film for Ultraviolet Photodetectors with High Response SpeedTBMG-345886/1/2019
Stretchable electronics, which can be stretched, deformed and wrapped onto nonplanar curved surfaces, have attracted much attraction due to their potential applications in wearable electronics, implantable biomedical devices, and artificial electronic skin. So far, many types of stretchable electronic devices have been developed including stretchable transistors, light-emitting diodes (LEDs), supercapacitors, photodetectors and sensors. Ultraviolet (UV) photodetectors have wide applications in crime investigation, biological analysis, fire monitoring, UV irradiation detection and many other applications as well.
Heat of Vaporization and Species Evolution during Gasoline Evaporation Measured by DSC/TGA/MS for Blends of C1 to C4 Alcohols in Commercial Gasoline Blendstocks2019-01-00141/15/2019
Evaporative cooling of the fuel-air charge by fuel evaporation is an important feature of direct-injection spark-ignition engines that improves fuel knock resistance and reduces pumping losses at intermediate load, but in some cases, may increase fine particle emissions. We have reported on experimental approaches for measuring both total heat of vaporization and examination of the evaporative heat effect as a function of fraction evaporated for gasolines and ethanol blends. In this paper, we extend this work to include other low-molecular-weight alcohols and present results on species evolution during fuel evaporation by coupling a mass spectrometer to our differential scanning calorimetry/thermogravimetric analysis instrument. The alcohols examined were methanol, ethanol, 1-propanol, isopropanol, 2-butanol, and isobutanol at 10 volume percent, 20 volume percent, and 30 volume percent. The results show that total heat of vaporization of the alcohol gasoline blends is in line with the decreasing heat of vaporization in kilojoules per kilogram with increasing alcohol carbon number, as expected. Mass spectrometer results show that methanol fully evaporates at significantly lower fraction evaporated relative to other alcohols even though it is present at higher molar concentration at a fixed volumetric concentration. Certain alcohols, especially methanol and ethanol, can suppress the evaporation of aromatic compounds such as cumene during the evaporation process in some samples. While the use of mass spectrometry to analyze the composition of the evolving gas mixture provided useful results for a relatively simple research gasoline (FACE B), additional research is required to practically apply this methodology to more complex commercial gasolines.
Fioroni, Gina M., Christensen, Earl, Fouts, Lisa, McCormick, Robert
Estimation of the Fuel Efficiency Potential of Six Gasoline Blendstocks Identified by the U.S. Department of Energy’s Co-Optimization of Fuels and Engines Program2019-01-00171/15/2019
Six blendstocks identified by the Co-Optimization of Fuels & Engines Program were used to prepare fuel blends using a fixed blendstock for oxygenate blending and a target RON of 97. The blendstocks included ethanol, n-propanol, isopropanol, isobutanol, diisobutylene, and a bioreformate surrogate. The blends were analyzed and used to establish interaction factors for a non-linear molar blending model that was used to predict RON and MON of volumetric blends of the blendstocks up to 35 vol%. Projections of efficiency increase, volumetric fuel economy increase, and tailpipe CO2 emissions decrease were produced using two different estimation techniques to evaluate the potential benefits of the blendstocks. Ethanol was projected to provide the greatest benefits in efficiency and tailpipe CO2 emissions, but at intermediate levels of volumetric fuel economy increase over a smaller range of blends than other blendstocks. A bioreformate surrogate blendstock was projected to provide the greatest increase in volumetric fuel economy and the lowest increase in efficiency. Tailpipe CO2 emissions for blends of the bioreformate surrogate were higher at all blend levels compared to the baseline E10 fuel.
Sluder, C. Scott
Integrated AHP and WED Based Approach to Select Optimal Combination of Operating Parameters on Spark Ignition Engine2019-01-00251/15/2019
The influence of operating parameters on the performance of spark ignition engine has attracted the interest of engine manufacturers and researchers. In this instance, selection of optimum criteria of operating parameters based on experimental results is expressed as a multi attribute decision making (MADM) problem. In this study, a mathematical model which is an integration of Analytic hierarchy process (AHP) and Weighted Euclidean distance based approach (WED) is proposed to select optimal combination of operating parameters. The parameters chosen are compression ratio (6,7,8,9), fuel blends (E10, E20, E30, E40) and load (25%, 50%, 75%, 100%). Consistency check of weights of attributes was carried out by AHP and the weighted distance of attributes from the most and least favorable situations was evaluated using WED. Optimum criteria with the combination of compression ratio of 8, fuel blend of E20 at load of 100% was found to be optimum. The results of proposed mathematical model were compared with another MCDM tool, Graph theory matrix approach. The proposed model allows the decision maker to analyze and evaluate the weights of attributes logically and systematically to make decision.
Geetha, Narayanan Kannaiyan, Pappula, Bridjesh
Influences of Butanol Blends on Combustion and Emissions of a Small SI Engine2018-32-005810/30/2018
In the general efforts to replace the fossil fuels in transportation by renewable fuels the bioalcohols are an important alternative. The global share of Bioethanol used for transportation is continuously increasing. Butanol, a four-carbon alcohol, is considered in the last years as an interesting alternative fuel, both for Diesel and for Gasoline application. Its advantages for engine operation are: good miscibility with gasoline and diesel fuels, higher calorific value than Ethanol, lower hygroscopicity, lower corrosivity and possibility of replacing aviation fuels. In the present work research with different nButanol portions in gasoline (BuXX)* was performed on the 2-cylinder SI engine with variations of several parameters on engine dynamometer. At different steady state operating points were varied: spark timing (αz), air excess factor (λ) and EGR-rate. Furthermore, the conversion rates and light-off of a 3-way-catalyst were investigated. As research tools the combustion pressure indication and the exhaust gas analysis were used. In the steady state operation, it was found that Bu-blends generally reduce the emissions of CO, HC, NOx in untreated exhaust gas and have a very little influence on catalytic conversion rates of the 3-way-catalyst. At lower engine part load, “Bu” shortens the inflammation lag and reduces the cyclic dispersion of combustion. Nevertheless, this advantage disappears at higher engine loads and with higher “Bu” portions. The present paper shows some examples of the most important results.
Czerwinski, Jan, Güdel, Martin, Engelmann, Danilo, Pechout, Martin
Waste Frying Oil Conversion to Biodiesel in Presence of Advanced Alumina Heterogeneous Catalyst2018-01-17509/10/2018
This paper reports experimental conversion of spent vegetable oil with bio-ethanol to long chain biodiesel fuel in presence of a new developed solid K3PO4 heterogeneous catalyst. Examined catalyst was synthesized following dipping impregnation of γ-Al2O3 solid support in an aqueous solution of potassium phosphate tri-basic K3PO4. K3PO4/γ-Al2O3 catalyst samples were distinguished based on their percentage loadings of K3PO4 (CK3PO4) and averaged particle size (dp). Produced catalyst samples were characterized in terms of their textural and surface properties using nitrogen adsorption-desorption isotherms and carbon dioxide & ammonia temperature programmed desorption techniques respectively. While the liquid phase of the product was analyzed using a GC-Mass spectroscopy technique. Ethanolysis runs were carried out following surface response methodology, central composite design (CCD). Parameters including catalyst percentage loading (CK3PO4), catalyst particle size (dp) as well as catalyst reactor weight (cat) were simulated the design factors. While percentage of ethyl ester yield (EEY%) was used as design response. Experimental results revealed an optimal measured EEY% of 92% achieved at 15:1 reactants molar ratio, 70 °C reaction temperature, 1000r.min−1 agitation speed, 25% percentage loading, 115 μm catalyst average particle size and 10 g/200 ml of catalyst weight in the reaction mixture. A high accuracy mathematical model was established for predicting the examined EEY% response results in terms of the above indicated operating parameters. Optimal EEY% of 95.43% was predicted under same operating conditions. The used catalyst was approved to be highly active, reliable and steady available solid heterogeneous catalyst that may promote the future of a more environmentally friendly biodiesel fuel.
Al-Zaini, Essam O., Abdullah, Ali A., Adesina, Adesoji
Dual Fuel Injection (DI + PFI) for Knock and EGR Dilution Limit Extension in a Boosted SI Engine2018-01-17359/10/2018
Combined direct and port fuel injection (i.e., dual injection) in spark ignition engines is of increasing interest due to the advantages for fuel flexibility and the individual merits of each system for improving engine performance and reducing engine-out emissions. Greater understanding of the impact of dual injection will enable deriving the maximum benefit from the two injection systems. This study investigates the effects of dual injection on combustion, especially knock propensity and tolerance to exhaust gas recirculation (EGR) dilution at different levels of EGR. A baseline for comparison with dual injection results was made using direct injection fueling only. A splash blended E20 fuel was used for the direct injection only tests. For the dual injection tests, gasoline, representing 80% by volume of the total fuel, was injected using the direct injector, and ethanol, representing 20% by volume of the total fuel, was injected using the port fuel injector. EGR mass fraction was varied from 0% to 21%, under boosted intake air pressure of 1.25 bar for both injection strategies. The results showed dual injection was beneficial to shorten the burn duration and improve combustion stability. Dual injection was more sensitive to knock than direct injection primarily due to increased unburned gas temperature. The overall thermal efficiency for the two injection types was comparable. The particulate matter emissions from dual injection showed slightly lower values, and the gaseous emissions showed lower total hydrocarbons and similar nitrogen oxides compared with only using direct injection of E20.
Han, Taehoon, Lavoie, George, Wooldridge, Margaret, Boehman, André
Effects of Injection Rate Profiles on Auto-Ignition in Ignition Quality Tester2018-01-16959/10/2018
Ignition quality tester (IQT) is a standard experimental device to determine ignition delay time of liquid fuels in a controlled environment in the absence of gas exchange. The process involves fuel injection, spray breakup, evaporation and mixing, which is followed by auto-ignition. In this study, three-dimensional computational fluid dynamics (CFD) is used for prediction of auto-ignition characteristics of diethyl ether (DEE) and ethanol. In particular, the sensitivity of the ignition behavior to different injection rate profiles is investigated. Fluctuant rate profile derived from needle lift data from experiments performs better than square rate profile in ignition delay predictions. DEE, when used with fluctuant injection rate profile resulted in faster ignition, while for ethanol the situation was reversed. The contrasting results are attributed to the difference in local mixing. The fluctuant injection profile yields larger spray velocity variations promoting fuel evaporation and local turbulent mixing. The suitable ignition conditions were reached earlier for DEE with fluctuant injection profile, whereas ethanol exhibits pseudo-homogeneous mixing due to its lower cetane number. Ignition was faster for square rate profile due to ignition in end tube for ethanol. The fluctuant injection leads to a better homogeneity for ethanol due to longer time available for mixing. The nature of heat release rate, auto-ignition and combustion were altered by the fluctuant injection rate profile when compared to square rate injection profile.
Luo, Yueqi, Mubarak Ali, Mohammed Jaasim, Huang, Zhen, Im, Hong
Experimental Investigation on the Stabilizing Effect of n-Butanol on Diesel-Bioethanol Blends2018-01-17449/10/2018
In accordance to the current environmental policy of the European Union by 2020, 10% of the transport fuel in every country comes from renewable sources such as biofuels. One of the most popular biofuels, (bio) ethanol is a probable suitable candidate for addition in diesel fuel because of its cleaner combustion and the ability to reduce emissions of gaseous pollutants. However, its use presents some important problems, attributed mainly to its incompatibility with diesel fuel during mixing due to the difference in the polarity. For this reason, substances that act as stabilizers of these mixtures are used, one of the most suitable being butanol. This substance is compatible with diesel fuel and ethanol, acting as a chemical bridge between the two, but also exhibits positive combustion behavior, as it is also an oxygenate that can be produced from renewable sources as well. The aim of this work was to investigate the behavior of diesel-ethanol mixtures using butanol as co-solvent. Different ultra low sulfur diesel (ULSD) samples, as well as a renewable paraffinic fuel derived from hydrotreatment of vegetable oils (HVO) were used as base fuels for the preparation of diesel - ethanol blends, with the addition of n-butanol as co-solvent. The main idea was to produce stable blends that can be used as fuel in diesel engines. The results showed that the production of stable diesel - bioethanol - butanol ternary blends is feasible. The amount of butanol that is required depends on the composition of the main fuel, with the aromatic content of the base fuel to be a critical parameter. Oxidation stability of the stable ternary blends was also evaluated in a Rapid Small Scale Oxidation Test unit, while other properties, such as ignition quality, were also measured. The results showed that the addition of the two oxygenates affect the oxidative characteristics of the base fuel, whereas a decrease in cetane number was observed.
Karonis, Dimitrios, Zahos Siagos, Iraklis, Pavlopoulos, Spyridon, Dodos, George S.
Combustion Characteristics of PRF and TSF Ethanol Blends with RON 98 in an Instrumented CFR Engine2018-01-16729/10/2018
The CFR F1 engine is the standard testing apparatus used for rating the research octane number (RON) of gasoline fuels. Unlike the motor octane number (MON) method, where the intake port temperature after the carburetor is controlled by an electric heater, the mixture temperature can vary during the RON test due to the heat of vaporization (HoV) of the fuel. Ethanol is receiving increasing attention as a high octane and high HoV fuel component. This work presents an analysis of the combustion characteristics during the RON rating of ethanol fuel blends according to the standard ASTM D2699 method, highlighting the effects of ethanol concentration and base fuel composition. All fuels were blended to a constant RON of 98. Ethanol levels varied from 0 to 50 vol% and the base fuels were surrogate blends composed of primary reference fuels (PRF), toluene standardization fuels (TSF), and a four component gasoline surrogate. These were compared against two full boiling range gasolines, also having a RON of 98. Through the use of detailed cylinder pressure analyses, this paper provides insights into the combustion behavior of various RON 98 fuels which are commonly not captured by the standard RON knock rating method. Ethanol was found to significantly reduce the pressure transducer based knock intensity of PRF fuel blends up to a level of 30 vol%, despite all fuels having the same RON. Meanwhile, the knock intensity of the equivalent TSF fuel blends was found to be relatively insensitive to ethanol concentration. For ethanol concentrations beyond 30 vol%, the pressure transducer based knock intensity behavior did not appear to be affected by the base fuel composition.
Hoth, Alexander, Kolodziej, Christopher P., Rockstroh, Toby, Wallner, Thomas
Critical Analysis of PM Index and Other Fuel Indices: Impact of Gasoline Fuel Volatility and Chemical Composition2018-01-17419/10/2018
Among the challenges for the future facing the development of gasoline engines, one of the most important is the reduction of particles emissions. This study proposes a critical and objective evaluation of the influence of fuel characteristics on gasoline particles emission through the use of Fuel Particle Indices. For this, a selected fuel matrix composed of 22 fuels was built presenting different volatility and chemical composition (content in total aromatics, heavy cuts and ethanol). To represent the fuel sooting tendency, seven Fuel Particle Indices were selected based on a literature review, namely, Particulate Matter Index (PMI), Particulate Number index (PNI), Threshold Sooting index (TSI), Smoke point (SP), Oxygen Extended Sooting Index (OESI), Simplified index 1 and 2 (sPMI 1, sPMI 2). These indices were computed on the fuel matrix and compared on the basis of three main axes. First, the sensitivity to fuel variation. Second, the agreement with engine particles emissions measured on vehicle on three vehicles. Third, the ease to compute with respect to the data availability in the European standard EN228. The comparison of fuel particles indices revealed different sensitivities to fuel variation: PMI, sPMI 1 and sPMI 2 represent well the effects of heavy aromatics, PNI is highly sensitive to the DVPE whereas SP, OESI and TSI were found well representative of the total aromatic content but represent weakly the effect of heavy aromatics. The comparison of the fuel particles indices with engine data indicates a good agreement of all indices, except for PNI. Finally, sPMI 1, sPMI 2 and calculated SP were found to be much easier to compute because they need simple data as input. This work highlights the importance of fuel quality on the reduction of particles emissions and suggests relevant Fuel Particles Indices that allow to capture fuel variation.
Ben Amara, Arij, Tahtouh, Toni, Ubrich, Elisabeth, Starck, Laurie, Moriya, Hidenori, IIda, Yutaka, KOJI, Nagata
Effects of Bio-Alcohol Fuel Blends on the Aging of Engine Lubricating Oil2018-01-17469/10/2018
Bio-alcohol fuel blends will gain in importance for future mobility. The driving force is the necessary reduction of greenhouse gases and harmful exhaust gas components. The new fuels offer advantages in engine combustion and resulting exhaust emissions because of the short-chained molecules and resulting low C/H ratio as well as the higher oxygen content. The aim of the project is a systematic analysis and evaluation of the effects of two bio-alcohol blends on the lubrication oil ageing of a gasoline-driven Euro 6 passenger car engine. For this reason a test engine was operated with three different fuels: a fossil gasoline (E0) without bio-alcohol components, a blend containing 30% vol ethanol (E30) and a blend containing 15% vol methanol (M15). During the engine test, gas of the cylinder charge and blow-by has been sampled and analyzed by ion chromatography regarding short-chained organic and inorganic acids. Based on these results the acid entries in lubricating oil were determined. In addition to the acid entries the entry of fuel into the lubricating oil were determined and compared for different engine operation points and test fuels. The causes of the fuel entries are discussed, based on the different fuel compositions and the resulting properties of bio-alcohol fuel blends. The results of the project provide detailed insights in the influence of the bio-alcohol fuel blends lubricity and aging of engine lubricating oil. This knowledge is prerequisite for a successful introduction of fuels with higher amounts of bio-alcohol in the market to meet the target for carbon dioxide reduction in the future mobility sector.
Prehn, Sascha, Vogel, Christine, Buchholz, Bert
A Computational Study of Lean Limit Extension of Alcohol HCCI Engines2018-01-16799/10/2018
The purpose of present numerical study was to extend the operating range of alcohol (methanol and ethanol) fueled Homogeneous Charge Compression Ignition (HCCI) engine under low load conditions. Ignition of pure methanol and ethanol under HCCI mode of operation requires high intake temperatures and misfires at low loads are common in HCCI engines. Three methods have been adapted to optimize the use of methanol and ethanol for HCCI operation without increasing the intake temperature. First, blending methanol and ethanol with ignition improver, namely di-methyl ether (DME) and di-ethyl ether (DEE), was used to increase the cetane number and ignitability of premixed charge. Second, based on the blended fuels, the spark assistance was used to reduce required intake temperature for auto-ignition. Third, DME and DEE were directly injected to methanol and ethanol operated HCCI engine, in the form of Reactivity Controlled Compression Ignition (RCCI) combustion. Negligible improvement in reducing intake temperature was observed in spark-assisted HCCI combustion due to the slow flame propagation speed under the lean premixed condition with blended fuels. In all three methods, it was found that RCCI combustion was more effective at reducing the required intake temperature compared to HCCI and spark assisted combustion, in spite of the fact that they are operated at same lambda (3.3) operating conditions.
Zhou, Qiyan, Mubarak Ali, Mohammed Jaasim, Mohan, Balaji, Lu, Xing-Cai, Im, Hong
Crank-Angle Resolved Exergy Analysis of Ethanol Fueled HCCI Engine Using Newly Reduced Ethanol Oxidation Mechanism2018-01-16839/10/2018
Ethanol fuelled homogenous charge compression ignition engine (HCCI) offers a better alternative to tackle the problems of achieving higher engine efficiency and lower emissions. Numerical simulations were carried out for a HCCI engine fueled with ethanol by stochastic reactor model using newly developed reduced ethanol oxidation mechanism consists of 47 species and 272 reactions. Reduced mechanism used in this study is validated by measured engine cylinder pressure curves and measured ignition delays in constant volume reactors in the previous study. Simulations are conducted for engine speeds ranging from 1000 to 3000 rpm at different intake temperatures (range 365-465 K) by varying the air-fuel ratio. Parametric study for combustion and emission characteristics is conducted and engine maps are developed at most efficient inlet temperatures. The HCCI operating range is defined using combustion efficiency (>85%) and maximum pressure rise rate (<5 MPa/ms). Areas of operation where excessive exergy destruction occurred were recognized using analyses of availability losses from exhaust, heat transfer, unburnt species and destruction due to combustion using engine operating maps. Availability destruction due to combustion is found to be maximum at high engine loads and high engine speeds. The maxima of losses of availability due to heat transfer and unburnt species are observed at low engine speeds and loads. In contrast to the mentioned losses, exhaust based loss of availability has its vertex at the highest achieved engine loads.
Maurya, Rakesh Kumar, Jaggi, Parth, Saxena, Mohit Raj
Blending Octane Number of 1-Butanol and Iso-Octane with Low Octane Fuels in HCCI Combustion Mode2018-01-16819/10/2018
Due to their physical and chemical properties, alcohols such as ethanol and methanol when blended with gasoline provide high anti-knock quality and hence efficient engines. However, there are few promising properties of 1-butanol similar to conventional gasoline which make it a favorable choice for internal combustion engines. Previously the author showed that by blending ethanol and methanol with low octane fuels, non-linear increase in the HCCI fuel number occurs in HCCI combustion mode. Very few studies have been conducted on the use of 1-butanol in HCCI combustion mode, therefore for this work, 1-butanol with a RON 96 was selected as the high octane fuel. Three low octane fuels with octane number close to 70 were used as a base fuel. Two of the low octane fuels are Fuels for Advanced Combustion Engines (FACE gasolines), more specifically FACE I and FACE J and also primary reference fuel (PRF 70) were selected. In addition, iso-octane, which has a different chemical structure than 1-butanol but an octane number (100) close to 1-butanol, was also selected as high octane fuel. A Cooperative Fuel Research (CFR) engine was used to conduct the experiments in HCCI combustion mode. HCCI fuel number was used for the octane rating similar to RON and MON in SI engine. 1-butanol and iso-octane were added in volume percentage 0, 5, 10, 15 and 20% to each of the base fuels. It was found that the increase of HCCI fuel number of 1-butanol was not linear with percentage added. For most of the operating conditions, non-linear synergistic blending behavior was observed when 1-butanol was blended with the three base fuels. The base fuel composition played a significant role for the blending octane number of 1-butanol. A weaker octane enhancement effect was observed when iso-octane was blended with the three base fuels.
Waqas, Muhammad Umer, Mohammed, Abdulrahman, Masurier, Jean-Baptiste, Johansson, Bengt
Evaluation of aluminum containers suitability for storage of fuel samples2018-36-03229/3/2018
In order to guarantee the effectiveness of enforcement action, Brazilian National Petroleum Agency (ANP) has published Resolution n°9/2007, which establishes the sampling of two liters of fuel, one being a test sample and another as a control sample. In this way, it is essential that the container used for this purpose maintains the physical-chemical parameters of the sample. In an attempt to evaluate possible alternatives to the current container used by ANP, this work deals with the application of aluminum bottle containers for the storage of the ethanol fuel, E27 gasohol and B10 and B15 diesel fuel blends. Approximately 15 liters of each fuel, except diesel fuel blends, were sampled on retail stations. B10 and B15 diesel fuel blends were formulated from diesel and biodiesel obtained on distribution base, being thoroughly homogenized and portioned on one-liter aluminum containers. Three samples of each fuel were used to characterize the fuel in the beginning of the work. For each condition (ambient, 30 °C and 40 °C), three samples of each fuel were kept for 60 days and other three were analyzed as control samples, which were stored at 0 °C also for 60 days. The samples had their main parameters analyzed using the standard methodologies established in the respective specifications and the results analyzed according to the limits specified by ANP. Ethanol fuel samples had presented no significative variation on the parameters analyzed, when they were compared with the characterization samples. E27 gasohol samples had shown differences in density, ethanol, olefin, saturated and aromatic content, while diesel fuel samples had presented variations on water content, oxidation stability and lubricity. With respect to the temperature, it was possible to identify trends in most of the parameters that presented variations.
Temistocles, Jacqueline Cristine Tolentino, Garcia, Fillipe Augusto da Costa, Figueiredo, Igor Freitas, de Oliveira, Nayara Leocádio, Karashima, Thiago Machado, de Paiva, Victor Santos, Skrobot, Vinícius Leandro
A High(er)-Definition Nose Sensor Could Improve Sensors that SniffTBMG-290146/1/2018
Sensors that sniff out chemicals in the air to warn us about everything from fires to carbon monoxide to drunk drivers to explosive devices hidden in luggage have improved so much that they can even detect diseases on a person’s breath. Researchers from Drexel University and the Korea Advanced Institute of Science and Technology have made a discovery that could make our best “chemical noses” even more sensitive.
Tiny Tooth-Mounted Sensors Track Food IntakeTBMG-289135/1/2018
Monitoring in real time what happens in and around our bodies can be invaluable in the context of healthcare or clinical studies, but not so easy to do. That could soon change thanks to new, miniaturized sensors developed by researchers at the Tufts University School of Engineering that, when mounted directly on a tooth and communicating wirelessly with a mobile device, can transmit information on glucose, salt, and alcohol intake. In research published in the journal Advanced Materials, researchers note that future adaptations of these sensors could enable the detection and recording of a wide range of nutrients, chemicals, and physiological states.
Effects of Ethanol Evaporative Cooling on Particulate Number Emissions in GDI Engines2018-01-03604/3/2018
The spark ignition engine particulate number (PN) emissions have been correlated to a particulate matter index (PMI) in the literature. The PMI value addresses the fuel effect on PN emission through the individual fuel species reactivity and vapor pressure. The latter quantity is used to account for the propensity of the non-volatile fuel components to survive to the later part of the combustion event as wall liquid films, which serve as sources for particulate emission. The PMI, however, does not encompass the suppression of vaporization by the evaporative cooling of fuel components, such as ethanol, that have high latent heat of vaporization. This paper assesses this evaporative cooling effect on PN emissions by measurements in a GDI engine operating with a base gasoline which does not contain oxygenate, with a blend of the gasoline and ethanol, and with a blend of the gasoline, ethanol, and a hydrocarbon additive so that the blend has the same PMI as the original gasoline. As such, the dilution and the evaporative cooling effects of the ethanol could be separated. Measurements have also been done with methanol and MTBE. The results show that evaporative cooling effect can significantly change the PN emission. The extent of the change, however, depends on the details of the operating condition such as injection timing, engine coolant temperature, and load.
Chen, Yu, Zhang, Yihao, Cheng, Wai K.
Study of Gasoline Particulate Matter Index with Refinery Blends2018-01-03544/3/2018
Gasoline direct injection (GDI) engines can help meet future fuel economy standards but will also make future proposed particulate matter (PM) emissions targets challenging to meet. This is mainly due to the fundamental change in the combustion process in GDI engines compared to conventional port fuel injection (PFI) engines. Auto manufacturers have linked PM emissions to gasoline formulations. Researchers at the Honda Motor Company proposed the particulate matter index (PMI) as a measure for gasoline sooting tendency. In this paper, 59 gasoline blend stocks from seven refineries were collected in order to study the compositional effect of real refinery streams on gasoline PMI. 580 gasoline blends were made from the 59 blend stocks. No traditional metrics of fuel quality were found to correlate well with the PMI. Reformate and FCC Naphtha contribute most significantly to the PMI of gasoline. Based on the refinery modeling assumptions presented in this paper, it is shown that a decrease in PMI from 1.5 to 1.35 shrinks the gasoline pool by 10%; a decrease in PMI from 1.5 to 1.0 yields a reduction of 30%. Since reformate is the primary incremental octane supply in a refinery, increasing the base octane from 87 [R + M]/2 E10 to 95 RON E10 results in a 10% increase in PMI, while an increase from 87 [R + M]/2 E10 to 98 RON E10 results in a 30% increase.
Shi, Yu, Cortes-Morales, Angel, Taylor, Bradley
Investigation of Combustion Knock Distribution in a Boosted Methane-Gasoline Blended Fueled SI Engine2018-01-02154/3/2018
The characteristics of combustion knock metrics over a number of engine cycles can be an essential reference for knock detection and control in internal combustion engines. In a Spark-Ignition (SI) engine, the stochastic nature of combustion knock has been shown to follow a log-normal distribution. However, this has been derived from experiments done with gasoline only and applicability of log-normal distribution to dual-fuel combustion knock has not been explored. To evaluate the effectiveness and accuracy of log-normal distributed knock model for methane-gasoline blended fuel, a sweep of methane-gasoline blend ratio was conducted at two different engine speeds. Experimental investigation was conducted on a single cylinder prototype SI engine equipped with two fuel systems: a direct injection (DI) system for gasoline and a port fuel injection (PFI) system for methane. The experiments were conducted at 1500 rpm and 2000 rpm, 12.0 bar net indicated mean effective pressure wherein the engine was boosted using compressed air. E10 gasoline and methane were used in this study. The results from blending two fuels show that the log-normal distribution provides a good fit to the measured distribution and captures the knock characteristics. The independency of log-normal distribution to the knock distribution at different spark timings was examined. The distribution parameters (log normal mean (μ) and standard deviation (σ)) show a linear correlation with the spark timing from knock borderline (BD) to 1.75° crank angle retarded. A μ and σ fit based log-normal (calculation-based log-normal) distribution model was proposed. The coefficients of multiple determination (CoMD) for the calculation-based log-normal model are all above 0.8 over the tested conditions. The validation of calculation-based log-normal was also conducted for all blending ratios and speeds.
Yang, Zhuyong, Rao, Sandesh, Wang, Yanyu, Harsulkar, Jaideep, Ansari, Ehsan, Miganakallu Narasimhamurthy, Niranjan, Dice, Paul, Naber, Jeffrey, Lonari, Yashodeep, Szwaja, Stanislaw
Early Pilot Injection Strategies for Reactivity Control in Diesel-ethanol Dual Fuel Combustion2018-01-02654/3/2018
This paper examines the diesel-ethanol dual fuel combustion at medium engine loads on a single-cylinder research diesel engine with a compression ratio of 16.5:1. The effect of exhaust gas recirculation (EGR) and ethanol energy ratio was investigated for the dual fuel combustion to achieve simultaneously ultra-low NOx and soot emissions. A medium ethanol ratio of about 0.6 was found suitable to meet the requirements for mixing enhancement and ignition control, which resulted in the lowest NOx and soot emissions among the tested ethanol ratios. A double-pilot injection strategy was found competent to lower the pressure rise rate owing to the reduced fuel quantity in the close-to-TDC injection. The advancement of pilot injection timing tended to reduce the CO and THC emissions, which is deemed beneficial for high EGR operations. The reactivity mutual-modulation between the diesel pilot and the background ethanol mixture was identified. The experiments confirmed that the background ethanol mixture could delay the ignition of the diesel pilot. The background ethanol can suppress the low-temperature heat release of the diesel pilot. With the close-to-TDC pilot as a reliable ignition source, the combustion phasing was controlled by the reactivity modulation of the cylinder charge through coordinated adjustment of the fuel quantity of the early injection diesel pilot and the port injection ethanol.
Yu, Shui, Dev, Shouvik, Yang, Zhenyi, Leblanc, Simon, Yu, Xiao, Han, Xiaoye, Li, Tie, Zheng, Ming
Benefits of Pd Doped Zeolites for Cold Start HC/NOx Emission Reductions for Gasoline and E85 Fueled Vehicles2018-01-09484/3/2018
In the development of HC traps (HCT) for reducing vehicle cold start hydrocarbon (HC)/nitrogen oxide (NOx) emissions, zeolite-based adsorbent materials were studied as key components for the capture and release of the main gasoline-type HC/NOx species in the vehicle exhaust gas. Typical zeolite materials capture and release certain HC and NOx species at low temperatures (<200°C), which is lower than the light-off temperature of a typical three-way catalyst (TWC) (≥250°C). Therefore, a zeolite alone is not effective in enhancing cold start HC/NOx emission control. We have found that a small amount of Pd (<0.5 wt%) dispersed in the zeolite (i.e., BEA) can significantly increase the conversion efficiency of certain HC/NOx species by increasing their release temperature. Pd was also found to modify the adsorption process from pure physisorption to chemisorption and may have played a role in the transformation of the adsorbed HCs to higher molecular weight species. Both these processes led to desorption at higher temperatures and more efficient conversion. Laboratory studies on BEA zeolite, with and without Pd, are described. These studies show the benefits of Pd-zeolite on the capture and release of HC/NOx species such as ethanol, ethylene, propylene, and toluene. It was also observed that the benefit of Pd in the zeolite was not stable under high-temperature rich conditions. This indicates a possible limitation for the application of Pd-beta in stoichiometric engine exhaust. A base metal was also added to the Pd-zeolite that stabilized emissions trapping after high-temperature rich aging conditions. Parallel vehicle emission test results also confirmed the benefits of the base metal-stabilized Pd-BEA zeolite in reducing cold start HC emissions.
Xu, Lifeng, Lupescu, Jason, Ura, Justin, Harwell, Amy, Paxton, William A., Nunan, John, Alltizer, Chad
Passive Hydrocarbon Trap to Enable SULEV-30 Tailpipe Emissions from a Flex-Fuel Vehicle on E85 Fuel2018-01-09444/3/2018
Future LEV-III tailpipe (TP) emission regulations pose an enormous challenge forcing the fleet average of light-duty vehicles produced in the 2025 model year to perform at the super ultralow emission vehicle (SULEV-30) certification levels (versus less than 20% produced today). To achieve SULEV-30, regulated TP emissions of non-methane organic gas (NMOG) hydrocarbons (HCs) and oxygenates plus oxides of nitrogen (NOx) must be below a combined 30 mg/mi (18.6 mg/km) standard as measured on the federal emissions certification cycle (FTP-75). However, when flex-fuel vehicles use E85 fuel instead of gasoline, NMOG emissions at cold start are nearly doubled, before the catalytic converter is active. Passive HC traps (HCTs) are a potential solution to reduce TP NMOG emissions. The conventional HCT design was modified by changing the zeolite chemistry so as to improve HC retention coupled with more efficient combustion during the desorption phase. Increased trapping efficiently was achieved by (a) modifying the acidic properties of the zeolite, (b) inclusion of Pd in order to more efficiently trap alkenes and NOx, and (c) the introduction of a new redox function that promoted HC combustion prior to the full desorption phase of the trap. A 2.0 L direct-injection Ford Focus with E85 fuel, utilizing the newly designed HCT developed by Ford and Umicore and having a significantly reduced platinum group metal (PGM) loading of only 0.53 g/L, was able to lower NMOG emissions by about 60% compared to the baseline underbody three-way catalyst (TWC). This in turn achieved combined NMOG + NOx emissions at an average of 19 mg/mi (11.8 mg/km), just below the SULEV-20 limit. The new trap formulation not only improved HC storage and conversion efficiency but substantially decreased the PGM content in line with current LEV-II partial zero-emission vehicle (PZEV) underbody loadings and will ensure continued sales of future flex-fuel vehicles.
Lupescu, Jason, Xu, Lifeng, Nunan, John, Alltizer, Chad
Measured and Predicted Vapor Liquid Equilibrium of Ethanol-Gasoline Fuels with Insight on the Influence of Azeotrope Interactions on Aromatic Species Enrichment and Particulate Matter Formation in Spark Ignition Engines2018-01-03614/3/2018
A relationship has been observed between increasing ethanol content in gasoline and increased particulate matter (PM) emissions from direct injection spark ignition (DISI) vehicles. The fundamental cause of this observation is not well understood. One potential explanation is that increased evaporative cooling as a result of ethanol’s high HOV may slow evaporation and prevent sufficient reactant mixing resulting in the combustion of localized fuel rich regions within the cylinder. In addition, it is well known that ethanol when blended in gasoline forms positive azeotropes which can alter the liquid/vapor composition during the vaporization process. In fact, it was shown recently through a numerical study that these interactions can retain the aromatic species within the liquid phase impeding the in-cylinder mixing of these compounds, which would accentuate PM formation upon combustion. To better understand the role of the azeotrope interactions on the vapor/liquid composition evolution of the fuel, distillations were performed using the Advanced Distillation Curve apparatus on carefully selected samples consisting of gasoline blended with ethanol and heavy aromatic and oxygenated compounds with varying vapor pressures, including cumene, p-cymene, 4-tertbutyl toluene, anisole, and 4-methyl anisole. Samples collected during the distillation indicate an enrichment of the heavy aromatic or oxygenated additive with an increase in initial ethanol concentration from E0 to E30. A recently developed distillation and droplet evaporation model is used to explore the influence of dilution effects versus azeotrope interactions on the aromatic species enrichment. The results suggest that HOV-cooling effects as well as aromatic species enrichment behaviors should be considered in future development of predictive indices to forecast the PM potential of fuels containing oxygenated compounds with comparatively high HOV.
Burke, Stephen, Rhoads, Robert, Ratcliff, Matthew, McCormick, Robert, Windom, Bret
Fuel Effects on Particulate Matter Emissions Variability from a Gasoline Direct Injection Engine2018-01-03554/3/2018
Particulate matter emissions from gasoline direct injection engines are a concern due to the health effects associated with ultrafine particles. This experimental study investigated sources of particulate matter emissions variability observed in previous tests and also examined the effect of ethanol content in gasoline on particle number (PN) concentrations and particle mass (PM) emissions. FTIR measurements of gas phase hydrocarbon emissions provided evidence that changes in fuel composition were responsible for the variability. Exhaust emissions of toluene and ethanol correlated positively with emitted PN concentrations, while emissions of isobutylene correlated negatively. Exhaust emissions of toluene and isobutylene were interpreted as markers of gasoline aromatic content and gasoline volatility respectively. Tests conducted with gasoline containing added toluene (10%) supported this hypothesis and led to the overall conclusion that the emissions variability observed in PN concentrations can be attributed to changes in the composition of the pump gasoline being used. Tests conducted with gasoline containing added ethanol (10% and 30%) found that increasing ethanol fuel content increased emitted PN concentrations at steady-state operation.
Ramos, Manuel J.M.G., Wallace, James S.
Effects of Heat of Vaporization and Octane Sensitivity on Knock-Limited Spark Ignition Engine Performance2018-01-02184/3/2018
Knock-limited loads for a set of surrogate gasolines all having nominal 100 research octane number (RON), approximately 11 octane sensitivity (S), and a heat of vaporization (HOV) range of 390 to 595 kJ/kg at 25°C were investigated. A single-cylinder spark-ignition engine derived from a General Motors Ecotec direct injection (DI) engine was used to perform load sweeps at a fixed intake air temperature (IAT) of 50 °C, as well as knock-limited load measurements across a range of IATs up to 90 °C. Both DI and pre-vaporized fuel (supplied by a fuel injector mounted far upstream of the intake valves and heated intake runner walls) experiments were performed to separate the chemical and thermal effects of the fuels’ knock resistance. The DI load sweeps at 50°C intake air temperature showed no effect of HOV on the knock-limited performance. The data suggest that HOV acts as a thermal contributor to S under the conditions studied. Measurement of knock-limited loads from the IAT sweeps for DI at late combustion phasing showed that a 40 vol% ethanol (E40) blend provided additional knock resistance at the highest temperatures, compared to a 20 vol% ethanol blend and hydrocarbon fuel with similar RON and S. Using the pre-vaporized fuel system, all the high S fuels produced nearly identical knock-limited loads at each temperature across the range of IATs studied. For these fuels RON ranged from 99.2 to 101.1 and S ranged from 9.4 to 12.2, with E40 having the lowest RON and highest S. The higher knock-limited loads for E40 at the highest IATs examined were consistent with the slightly higher S for this fuel, and the lower engine operating condition K values arising from use of this fuel. The study highlights how fuel HOV can affect the temperature at intake valve closing, and consequently the pressure-temperature history of the end gas leading to more negative values of K, thereby enhancing the effect of S on knock resistance.
Ratcliff, Matthew A., Burton, Jonathan, Sindler, Petr, Christensen, Earl, Fouts, Lisa, McCormick, Robert L.
Real World Performance of an Onboard Gasoline/Ethanol Separation System to Enable Knock Suppression Using an Octane-On-Demand Fuel System2018-01-08794/3/2018
Higher compression ratio and turbocharging, with engine downsizing can enable significant gains in fuel economy but require engine operating conditions that cause engine knock under high load. Engine knock can be avoided by supplying higher-octane fuel under such high load conditions. This study builds on previous MIT papers investigating Octane-On-Demand (OOD) to enable a higher efficiency, higher-boost higher compression-ratio engine. The high-octane fuel for OOD can be obtained through On-Board-Separation (OBS) of alcohol blended gasoline. Fuel from the primary fuel tank filled with commercially available gasoline that contains 10% by volume ethanol (E10) is separated by an organic membrane pervaporation process that produces a 30 to 90% ethanol fuel blend for use when high octane is needed. In addition to previous work, this paper combines modeling of the OBS system with passenger car and medium-duty truck fuel consumption and octane requirements for various driving cycles. Medium duty driving cycles were included; HHDDT cruise mode for long-haul heavy truck cruising and HTUF 4 for delivery truck duty. Commercial vehicle modeling was done under unloaded, half and fully loaded conditions. Additionally, for the first time, transient separator performance and effective separation limits were included in the evaluation. Separator start-up, and membrane selectivity decrease achievable real-world fuel economy from what can be achieved with two separate tanks: one with gasoline, the other with ethanol. However, using the fuel separation system, the reduction in fuel economy is modest compared to a two tank system with pure ethanol while the need to fill a second tank is removed. Fuel efficiency gains compared to equivalent-performance current engines, including real world limitations ranged from 17.5-30% with commercial gasoline that includes 10% ethanol as base fuel.
Kasseris, Emmanuel, Heywood, John B., Seitz, Scott, Kolakaluri, Ravi
Blending Octane Number of Toluene with Gasoline-like and PRF Fuels in HCCI Combustion Mode2018-01-12464/3/2018
Future internal combustion engines demand higher efficiency but progression towards this is limited by the phenomenon called knock. A possible solution for reaching high efficiency is Octane-on-Demand (OoD), which allows to customize the antiknock quality of a fuel through blending of high-octane fuel with a low octane fuel. Previous studies on Octane-on-Demand highlighted efficiency benefits depending on the combination of low octane fuel with high octane booster. The author recently published works with ethanol and methanol as high-octane fuels. The results of this work showed that the composition and octane number of the low octane fuel is significant for the blending octane number of both ethanol and methanol. This work focuses on toluene as the high octane fuel (RON 120). Aromatics offers anti-knock quality and with high octane number than alcohols, this work will address if toluene can provide higher octane enhancement. Our aim is to investigate the impact of three gasoline-like fuels and two Primary Reference Fuels (PRFs). More specifically, fuels are FACE (Fuels for Advanced Combustion Engines) I, FACE J, FACE A, PRF 70 and PRF 84. A CFR engine was used to conduct the experiments in HCCI mode. For this combustion mode, the engine operated at four specific conditions based on RON and MON conditions. The octane numbers corresponding to four HCCI numbers were obtained for toluene concentration of 0, 2, 5, 10, 15 and 20%. Results show that the blending octane number of toluene varies non-linearly and linearly with the increase in toluene concentration depending on the base fuel, experimental conditions and the concentration of toluene. As a result, the blending octane number can range from close to 150 with a small fraction of toluene to a number closer to that of toluene, 120, with larger fractions.
Waqas, Muhammad Umer, Masurier, Jean-Baptiste, Sarathy, Mani, Johansson, Bengt
Influence of Considering Non-Ideal Thermodynamics on Droplet Evaporation and Spray Formation (for Gasoline Direct Injection Engine Conditions) Using VSB2 Spray Model2018-01-01814/3/2018
This work utilizes previously developed VSB2 (VSB2 Stochastic Blob and Bubble) multicomponent fuel spray model to study significance of using non-ideal thermodynamics for droplet evaporation under direct injection engine like operating conditions. Non-ideal thermodynamics is used to account for vapor-liquid equilibrium arising from evaporation of multicomponent fuel droplets. In specific, the evaporation of ethanol/iso-octane blend is studied in this work. Two compositions of the blend are tested, E-10 and E-85 respectively (the number denotes percentage of ethanol in blend). The VSB2 spray model is implemented into OpenFoam CFD code which is used to study evaporation of the blend in constant volume combustion vessel. Liquid and vapor penetration lengths for the E-10 case are calculated and compared with the experiment. The simulation results show reasonable agreement with the experiment. Simulation is performed with two methods- ideal and non-ideal thermodynamics respectively. For liquid penetration, the two methods show a small but evident difference. For vapor penetration, there is no significant difference. Radial fuel vapor mass fraction distribution (for both components) is obtained from simulation and compared for E-10 and E-85 cases. It is seen that for E-85 case, the difference in predictions between ideal and non-ideal thermodynamics case is significantly higher than that of E10 case. It is therefore inferred that ideal thermodynamics is not sufficient to predict vapor liquid equilibrium, especially for higher ethanol content in the blend.
Pandian Muthuramalingam, Vignesh, Karlsson, Anders
Effect of High Frequency Acoustic Field on Atomization Behavior of Ethanol and Kerosene2017-01-231810/8/2017
Combustion instability often occurs inside the combustion chamber of aero engine. Fuel atomization and evaporation, one of the controlling processes of combustion rate, is an important mechanism of the combustion instability. To tackle combustion instability, it challenges a deep understanding of the underlying mechanism of fuel atomization and evaporation. In this paper, acoustic field was established to simulate the pressure oscillation. Transient spray images of ethanol and kerosene were recorded using high-speed camera. The obtained images were processed by MATLAB to extract and analyze the related data. Spatial fuel atomization characteristics was analytically examined by multi-threshold image method to analyze the effect of the high frequency acoustic field on the fuel break-up and disintegration. The results show that the half spray cone angle on the side with speaker is suppressed by the presence of the imposed acoustic field compared with the case without speaker. Statistically, the half spray angle of kerosene with right speaker under the acoustic frequency of 9 kHz is 18.97% larger than that with left speaker. For ethanol, the difference is 11.90%. Also, it turns out the frequency of the acoustic field influences the spray angle variation during the injection process. There is a decline of the spray cone angle at the early stage of the injection. However, the watersheds for the transformation were not the same for kerosene and ethanol.
Jia, Xiaoxu, Huang, Zhong, Ju, Dehao, Huang, Zhen, Lu, Xing-cai
Experimental and Kinetic Analyses of Thermochemical Fuel Reforming (TFR) with Alcohol Enrichment in Plug Flow Reactor: a Verification of In-Cylinder TFR2017-01-227810/8/2017
In-cylinder thermochemical fuel reforming (TFR) in spark ignition natural gas engine was developed to reveal that thermochemical fuel reforming could increase H2 and CO concentration in reformed gas, leading to an increase of thermal efficiency and engine performance. Moreover, ethanol enrichment has been proved to have great potential to optimize TFR performance. In order to explain TFR phenomenon chemically, methane oxidation experiments were conducted in a laminar flow reactor with addition of ethanol and methanol at equivalent ratios of 1.5, 1.7, 1.9 and 2.1 from 948K to 1098K at atmospheric pressure. Experimental results showed that methanol have great ability to facilitate the oxidation of methane than that of ethanol. Meanwhile, the degree of methane conversion became more significantly as the equivalent ratio increased. Kinetic analysis of oxidation of methane with alcohol enrichment in a plug flow model was also conducted in this study. There was good agreement between experimental and computational results. The oxidation of methanol or ethanol released plenty of radicals such as H, OH and HO2, which further reacted with CH4 more intensively in fuel rich condition. Rate of production and sensitivity analyses showed that methanol could produce more reactive radicals, which were involved in a series of initial oxidation reactions of methane. It indicated that methanol have great potential to improve in-cylinder TFR performance.
Deng, Zhiwei, Li, Ang, Zhu, Lei, Huang, Zhen
Evaluation of the Stability and Ignition Quality of Diesel-Biodiesel-Butanol Blends2017-01-232010/8/2017
FAME is the most common renewable component of conventional automotive diesel. Despite the advantages, biodiesel is more susceptible to oxidative deterioration and due to its chemical composition as well as its higher affinity to water, is considered to be a favorable substrate for microorganisms. On the other hand, apart from biodiesel, alcohols are considered to be promising substitutes to conventional diesel fuel because they can offer higher oxygen concentration leading to better combustion characteristics and lower exhaust emissions. More specifically, n-butanol is a renewable alcohol demonstrating better blending capabilities and properties when it is added to diesel fuel, as its composition is closer to conventional fuel, when compared ethanol to for example. Taking into consideration the alleged disinfectant properties of alcohols, it would be interesting to examine also the microbial stability of blends containing n-butanol in various concentrations. Based on the aforementioned, the aim of this study is to investigate the effect of n-butanol in diesel/ biodiesel blends on fuel quality characteristics (ignition quality, lubricity) while the oxidation and microbial stability is also assessed. Blends of automotive diesel with a commercial FAME up to 20% v/v and n-butanol at concentrations of 5% and 10% v/v were prepared. The microbial stability of diesel/biodiesel/n-butanol blends was assessed and compared to diesel-biodiesel ones by preparing and storing laboratory-scale contaminated microcosms. Overall, ULSD/FAME/n-butanol ternary blends demonstrated high blending stability while density, viscosity, CFPP and sulfur content have not been substantially affected. The poor lubricity of n-butanol and ULSD was compensated by the presence of FAME. N-butanol contributed in increasing the stability - either oxidation or microbial - of the ternary blends compared to the respective binary B7 and B20 blends. Nevertheless, FAME and n-butanol have poor ignition quality characteristics, which resulted in a significant decrease of the DCN of the base fuel.
Dodos, George S., Tsesmeli, Chrysovalanti E., Zahos-Siagos, Iraklis, Tyrovola, Theodora, Karonis, Dimitrios, Zannikos, Fanourios
Numerical Investigations on the Combustion Characteristics of N-Heptane Spray under Premixed Ethanol and Iso-Octane Atmosphere in a Combustion Vessel2017-01-226910/8/2017
Based on a composed PRF/ethanol/PAH mechanism, simulations were conducted to investigate the combustion characteristics of n-heptane spray under premixed ethanol/air and iso-octane/air atmosphere in a combustion vessel. The effects of premixed ethanol and iso-octane on ignition delay, important soot precursors and soot volume fraction of n-heptane spray were studied. Also, simulated results with and without considering the cooling effects of premixed fuel vaporization were compared. When the cooling effect of premixed fuel vaporization was not considered, simulations showed that premixed ethanol could increase the ignition delay of n-heptane spray at ambient temperatures below 850K. However, premixed iso-octane showed little inhibition effect on ignition of n-heptane spray. Also, it was found that both premixed ethanol and iso-octane contributed to faster ignition under high ambient temperatures. The soot volume fraction and soot precursor concentration were significantly reduced under premixed ethanol atmosphere at 800K. For cases under premixed iso-octane atmosphere, the soot volume fraction was increased under all the simulated ambient temperatures. When the cooling effect of premixed fuel vaporization was considered, simulations showed that premixed ethanol could retard the ignition of n-heptane spray even at initial ambient temperature of 1000K. Also, the soot volume fraction was significantly reduced under premixed ethanol atmosphere at 850K. However, under premixed iso-octane atmosphere, the simulated results with and without considering the cooling effect of iso-octane vaporization show smaller difference. Therefore, the simulations show that the high vaporization heat of ethanol also has an obvious effect on soot reduction of dual-fuel combustion.
Dong, Shijun, Cheng, Xiaobei, Ou, Biao, Yang, Can, Wang, Zhaowen, Pan, Fumin
Study of Performance and Emissions Parameters of Single Cylinder Diesel Engine Fuelled with Micro Emulsion of Jatropha Oil and Ethanol2017-01-233110/8/2017
The use of alternative fuel has many advantages and the main ones are its renewability, biodegradability with better quality exhaust gas emission, which do not contribute to raise the level of carbon dioxide in the atmosphere. The use of non-edible vegetables oils as an alternative fuels for diesel engine is accelerated by the energy crisis due to depletion of resources and increase in environmental problems. In Asian countries like India, great need of edible oil as a food so cannot use these oils as alternative fuels for diesel engine. However there are many issues related to the use of vegetable oils in diesel engine that is high viscosity, low calorific value, high self-ignition temperature etc. Jatropha curcas has been promoted in India as a sustainable substitute to diesel fuel. This research prepared micro emulsions of ethanol and Jatropha vegetable oil in different ratio and find out the physico-chemical parameters to compare with mineral diesel oil. Also compare the performance and emissions characteristics of single cylinder, air cool diesel engine fuelled with micro emulsion of Jatropha vegetable oil with different percentage of ethanol and diesel fuels separately. It has been found that at part load condition the brake thermal efficiency and brake specific energy consumption of blends of jatropha oil and ethanol is insignificant. Basic HC, CO emissions and smoke opacity were reduced at part load condition. However, there was a decrease in NOx in case of jatropha oil and ethanol at full load condition.
Deep, Amar, Kumar, Naveen, Pali, Harveer Singh
Blending Octane Number of Ethanol on a Volume and Molar Basis in SI and HCCI Combustion Modes2017-01-225610/8/2017
The blending behavior of ethanol in five different hydrocarbon base fuels with octane numbers of approximately 70 and 84 was examined under Spark-Ignited (SI) and Homogeneous Charge Compression Ignited (HCCI) operating conditions. The Blending octane number (BON) was used to characterize the blending behavior on both a volume and molar basis. Previous studies have shown that the blending behavior of ethanol generally follows several well-established rules. In particular, non-linear blending effects are generally observed on a volume basis (i.e. BON > RON or MON of pure ethanol; 108 and 89, respectively), while linear blending effects are generally observed on a molar basis (i.e. BON = RON or MON of pure ethanol). This work firstly demonstrates that the non-linear volumetric blending effects traditionally observed under SI operating conditions are also observed under HCCI operating conditions. In keeping with previous studies, the degree of this non-linearity is shown to be a function of the base fuel composition and octane number. By contrast, the molar blending approach is shown to behave differently depending on the chosen combustion mode, with some non-linearity observed under HCCI operating conditions (i.e. BON ≠ RON or MON of pure ethanol). This suggests that the well-established blending rules for SI operating conditions may not always be relevant to other combustion modes that operate with globally lean or diluted air-fuel mixtures. This has implications for the design of future fuel specifications.
Waqas, Muhammad Umer, Morganti, Kai, Masurier, Jean-Baptiste, Johansson, Bengt
Effect of Spark Timing on Performance and Emissions of a Small Spark Ignition Engine with Dual Ethanol Fuel Injection2017-01-223010/8/2017
Ethanol as a renewable fuel has been used widely in vehicles. Dual fuel injection is one of the new techniques in development for increasing the engine’s thermal efficiency and reducing the pollutant emissions. This study reports experimental investigation to the dual ethanol fuel injection with a focus on the effect of spark timing on the engine performance at different volumetric ratios of ethanol directly injected to ethanol port injected. Experiments were conducted on a single cylinder 250cc spark ignition engine at two engine loads and 3500 RPM. The spark timing was varied from 15 to 42 CAD bTDC at the light load and from 15 to 32 CAD bTDC at the medium load, while the volumetric ratio of direct injection (DI%) was varied from 0% to 100%. Experimental results showed that DI100%, the best indicated mean effective pressure (IMEP) and thermal efficiency occurred at around 30 CAD bTDC at the light load and 23 CAD bTDC at the medium load, which were the minimum spark advance for the best torque (MBT). At MBT spark timing, the IMEP at DI56% and light engine load was 8.28% greater than that at 15 CAD bTDC which was the original spark timing set by the manufacturer, and the combustion duration (CA10-90%) was 41.8% shorter. These results were attributed to the improved combustion phase associated with the increased combustion pressure and temperature when the spark timing was advanced. However, the indicated specific hydrocarbon and carbon monoxide emissions increased with advanced spark timing and increased DI ratio. These could be caused by local rich mixture formed by fuel impinged to the chamber walls and the ethanol’s cooling effect associated with the direct injection. On the other hand, because of the charge cooling effect of DI, the indicated specific nitric oxide emission decreased with increased DI ratio. At MBT timing and light load, the indicated specific nitric oxide emission decreased by 37.53% at DI56% and 67.39% at DI100% compared to port injection only.
Al-Muhsen, Nizar F.O., Hong, Guang
Validation of the VSB2 Spray Model for Ethanol under Diesel like Conditions2017-01-219310/8/2017
When developing new combustion concepts, CFD simulations is a powerful tool. The modeling of spray formation is a challenging but important part when it comes to CFD modelling of non-premixed combustion. There is a large difference in the accuracy and robustness among different spray models and their implementation in different CFD codes. In the work presented in this paper a spray model, designated as VSB2 has been implemented in OpenFOAM. VSB2 differ from traditional spray models by replacing the Lagrangian parcels with stochastic blobs. The stochastic blobs consists of a droplet size distribution rather than equal sized droplets, as is the case with the traditional parcel. The VSB2 model has previously been thoroughly validated for spray formation and combustion of n-heptane. The aim of this study was to validate the VSB2 spray model for ethanol spray formation and combustion as a step in modelling dual-fuel combustion with alcohol and diesel. This was done by comparing spray penetration with data obtained from experiments with ethanol in a high-temperature high pressure spray chamber. The spray turbulence interaction is also investigated by the usage of different turbulence models. The study showed that the VSB2 model can be used to predict the formation of an ethanol spray. It was also concluded that the standard k - ε performed better than the realizable k - ε model, and that it is necessary to fix the turbulent length scale in the injector cell to produce accurate results.
Nygren, Andreas, Karlsson, Anders
Investigating the Impact of Ethanol on the Lubricity of Gasoline and on the Lubricity Improvers Efficiency2017-01-229710/8/2017
As it is the case for Diesel engines, the Gasoline Direct Injection engines are using higher and higher injection pressures. The state of the art gasoline Direct Injection (GDI) engines are currently using injection pressures as high as 500 bar. A lot of work is also currently ongoing on Gasoline Compression Ignition (GCI) engines which use even higher injection pressures (above 1 000 bar). A high injection pressure means that a high pressure pump has to be used and so, proper lubricity has to be brought by the fuel. In the mean time the use of biofuels is increasing and several studies have shown the positive impact of ethanol on the energy consumption of gasoline engines mainly thru an octane number effect. For all these reasons, it seems important to evaluate the impact of ethanol on the lubricity of gasoline as well as on the response of lubricity additives that may be required in a medium-term future to provide gasoline enough lubricity to ensure the operability of these new engines. This paper determines how ethanol affects the lubricity (verified thru a modified version of the standard High Frequency Reciprocating Rig test procedure) of various formulations of gasoline using either a high amount of aromatics (typical of a refinery with reforming capacities) or a low amount of aromatics (typical of a refinery equipped with alkylation capacities). It also focuses on how the main lubricity improvers (acid-type or ester-based) used for treating Diesel fuels can help to increase the lubricity of such formulations of gasoline. The main outcomes show that the ethanol tends to enhance the lubricity of the fuel. But at the same time it also decreases the ability of lubricity additives to improve the lubricity. In addition, these effects seem linked to the composition of the gasoline with possibly a lower impact when large amount of aromatics are present.
Dubois, Thomas, Abiad, Lidwine, Caine, Pauline
Effects of Fuel Injection Events of Ethanol and Gasoline Blends on Boosted Direct-Injection Engine Performance2017-01-223810/8/2017
Numerous studies have demonstrated the benefits of ethanol in increasing the thermal efficiency of gasoline-fueled spark ignition engines via the higher enthalpy of vaporization and higher knock resistance of ethanol compared with gasoline. This study expands on previous work by considering a split fuel injection strategy with a boosted direct injection spark ignition engine fueled with E0 (100% by volume reference grade gasoline; with research octane number = 91 and motor octane number = 83), E100 (100% by volume anhydrous ethanol), and various splash-blends of the two fuels. Experiments were performed using a production 3-cylinder Ford Ecoboost engine where two cylinders were de-activated to create a single-cylinder engine with a displacement of 0.33 L. The engine was operated over a range of loads with boosted intake manifold absolute pressure (MAP) from 1 bar to 1.5 bar. The fuel injection timing of single fuel injection events was varied at MAP = 1 bar using different blend ratios (E0, E30, E50, E85 and E100) to identify the range of injection timing corresponding to maximum thermal efficiency for each fuel blend. The results indicated knock limited operation for E0 at MAP higher than 1 bar (boosted), whereas none of the ethanol blends was knock-limited even at the highest MAP tested. A split fuel injection strategy with 50% of the fuel mass in each of two injection events was investigated for the range of MAP conditions studied. The different fuel blends showed little sensitivity to the split injection strategy, which indicated fuel air mixing did not significantly affect combustion at the conditions studied. The highest gross indicated thermal efficiencies (GITE) of 38.4% were achieved with E85 and E100 at 1.1 and 1.2 bar MAP for an absolute improvement of 4% compared with baseline gasoline for the same intake pressures. The improvement in GITE scaled with the fraction of ethanol in the fuel blend. GT-Power simulations were used to evaluate the contributions of the enthalpy of vaporization and cooling effects on GITE. Comparison of the simulation results with the experimental data indicates the benefit of increasing GITE with increasing ethanol in the fuel blend is due to enthalpy of vaporization accounting (e.g. of liquid versus gas-phase fuel) and cooling effects on thermodynamic properties such as the ratio of specific heats.
Singh, Ripudaman, Burch, Travis, Lavoie, George, Wooldridge, Margaret, Fatouraie, Mohammad
Correlation between Simulated Volume Fraction Burned Using a Quasi-Dimensional Model and Flame Area Measured in an Optically Accessible SI Engine2017-01-05453/28/2017
Multi-fuel operation is one of the main topics of investigative research in the field of internal combustion engines. Spark ignition (SI) power units are relatively easily adaptable to alternative liquid-as well as gaseous-fuels, with mixture preparation being the main modification required. Numerical simulations are used on an ever wider scale in engine research in order to reduce costs associated with experimental investigations. In this sense, quasi-dimensional models provide acceptable accuracy with reduced computational efforts. Within this context, the present study puts under scrutiny the assumption of spherical flame propagation and how calibration of a two-zone combustion simulation is affected when changing fuel type. A quasi-dimensional model was calibrated based on measured in-cylinder pressure, and numerical results related to the two-zone volumes were compared to recorded flame imaging. Gasoline, ethanol, methane and hydrogen were used as fuels and the aforementioned comparison was performed for each case. In order to identify the influence of specific properties, intake pressure, air-fuel ratio and spark timing were kept constant for al fuel types. Overall the spherical flame assumption was found to ensure acceptable results and the correlation between turbulence intensity and flame propagation emphasized the importance of proper description of localized scales at which chemical reactions occur behind the flame front.
Irimescu, Adrian, Di Iorio, Silvana, Merola, Simona Silvia, Sementa, Paolo, Vaglieco, Bianca Maria
Most Recent Discussion of the Performance and Emissions Produced by a Stratified Torch Ignition Prototype Engine Fuelled by a Blend of Ethanol and Gasoline2017-01-06443/28/2017
In a torch ignition engine system the combustion starts in a prechamber, where the pressure increase pushes the combustion jet flames through calibrated nozzles to be precisely targeted into the main combustion chamber. The paper presents the layout of the prototype engine and the developed fuel injection system. It continues with a detailed description of the performance of the torch ignition engine running on a gasoline/ethanol blend for different mixture stratification levels as well as engine speeds and loads. Also detailed analyses of specific fuel consumption, thermal and combustion efficiency, specific emissions of CO2 and the main combustion parameters are carried out. A supplementary decrease in NOX emissions was obtained by use of Brazilian pure hydrated fuel. The paper concludes presenting the main results obtained in this work, which show significant increase of the torch ignition engine performance in comparison with the commercial baseline engine.
Pontoppidan, Michael, baeta, Adm José
Compatibility of Fuel System Elastomers with Bio-Blendstock Fuel Candidates Using Hansen Solubility Analysis2017-01-08023/28/2017
The compatibility of key fuel system infrastructure elastomers with promising bio-blendstock fuel candidates was examined using Hansen solubility analysis. Thirty-four candidate fuels were evaluated in this study including multiple alcohols, esters, ethers, ketones, alkenes and one alkane. These compounds were evaluated as neat molecules and as blends with the gasoline surrogate, dodecane and a mix of dodecane and 10% ethanol (E10D). The elastomer materials were fluorocarbon, acrylonitrile butadiene rubber (NBR), styrene butadiene (SBR), neoprene, polyurethane and silicone. These materials have been rigorously studied with other fuel types, and their measured volume change results were found to correspond well with their predicted solubility levels. The alcohols showed probable compatibility with fluorocarbon and polyurethane, but are not likely to be compatible at low blend levels with NBR and SBR. Low and mid-range blends are also considered incompatible with silicone, as are mid-range blends with neoprene. The alkane fuel candidate is likely compatible with fluorocarbon, polyurethane, NBR and SBR at most blend levels, but low to mid-range blends are not likely compatible with silicone. Neoprene showed compatibility only with mid-range blends of the alkane. The alkene and aromatics exhibited similar compatibility. They showed good compatibility with fluorocarbon, neoprene and polyurethane, but not with silicone, NBR, and SBR. For the esters, compatibility varied depending on the ester type. Generally, these fuels were compatible with fluorocarbon and polyurethane, but not with silicone. Low blend levels are likely to be compatible with neoprene, but considerable uncertainty is noted for NBR and SBR. Ethers were generally compatible with fluorocarbon and at low blend levels with neoprene and polyurethane. They were most incompatible with silicone, NBR, and SBR. The ketones were the one fuel type that showed some incompatibility with fluorocarbon, especially at high blend levels. Incompatibilities were also noted for silicone, neoprene and polyurethane. However, ketones are likely compatible with NBR and SBR at high blend levels.
Kass, Michael D., West, Brian H.
Energy Analysis of Low-Load Low-Temperature Gasoline Combustion with Auxiliary-Fueled Negative Valve Overlap2017-01-07293/28/2017
In-cylinder reforming of injected fuel during an auxiliary negative valve overlap (NVO) period can be used to optimize main-cycle auto-ignition phasing for low-load Low-Temperature Gasoline Combustion (LTGC), where highly dilute mixtures can lead to poor combustion stability. When mixed with fresh intake charge and fuel, these reformate streams can alter overall charge reactivity characteristics. The central issue remains large parasitic heat losses from the retention and compression of hot exhaust gases along with modest pumping losses that result from mixing hot NVO-period gases with the cooler intake charge. Accurate determination of total cycle energy utilization is complicated by the fact that NVO-period retained fuel energy is consumed during the subsequent main combustion period. For the present study, a full-cycle energy analysis was performed for a single-cylinder research engine undergoing LTGC with varying NVO auxiliary fueling rates and injection timing. A custom alternate-fire sequence with 9 pre-conditioning cycles was used to generate a common exhaust temperature and composition boundary condition for a cycle-of-interest, with performance metrics recorded for each custom cycle. The NVO-period reformate stream and main-period exhaust stream of the cycles-of-interest were separately collected, with sample analysis by gas chromatography used to identify the retained and exhausted fuel energy in the respective periods. To facilitate gas sample analysis, experiments were performed using a 5-component gasoline surrogate (iso-octane, n-heptane, ethanol, 1-hexene, and toluene) that matched the molecular composition, 50% boiling point, and ignition characteristics of a research gasoline. The highest total cycle thermodynamic efficiencies occurred when auxiliary injection timings were early enough to allow sufficient residence time for slow reforming reactions to take place, but late enough to prevent significant fuel spray crevice quench. Increasing the fraction of total fuel energy injected into the NVO-period was also found to increase total cycle thermal efficiencies, in part due to a modest reduction in NVO-period heat loss from a combination of fuel-spray charge cooling and endothermic fuel decomposition by pyrolysis. The effect was most pronounced at the lowest loads where larger charge mass reformate fractions increased overall specific heat ratios and main-period combustion phasing advanced closer to top dead center. These effects improved both expansion efficiency and combustion stability.
Ekoto, Isaac, Wolk, Benjamin, Northrop, William
Experimental Investigation of Fuel Film Characteristics of Ethanol Impinging Spray at Ultra-Low Temperature2017-01-08513/28/2017
Increasing the injection pressure in DISI engine is an efficient way to obtain finer droplets but it will also potentially cause spray impingement on the cylinder wall and piston. Consequently, the fuel film sticking on the wall can dramatically increase the soot emission of the engine especially in a cold start condition. On the other hand, ethanol is widely used as an alternative fuel in DI engine due to its sustainable nature and high octane number. In this study, the fuel film characteristics of single-plume ethanol impinging spray was investigated. The experiments were performed under ultra-low fuel/plate temperature to simulate the cold start condition in cold areas. A low temperature thermostatic bath combined with specially designed heat exchangers were used to achieve ultra-low temperature for both the impinging plate and the fuel. Laser induced fluorescence (LIF) technique was employed to measure the thickness of fuel film deposited on the impinging plate. Rhodamine 6G was resolved into ethanol as the tracer, which can be excited by 532 nm laser and fluorescence at 560-590 nm. A low speed imaging system was used to capture the film characteristics. The LIF signal was converted to film thickness following a known height calibration approach. It was found that, with the decrease of plate temperature, the average film became thicker and the adhered mass increased although the wetted area became smaller due to the larger viscosity. Moreover, lower fuel temperature leads to thicker film and more adhered mass. The wetted areas are close to each other under different fuel temperatures.
Pan, Hujie, Xu, Min, Hung, David, Lv, Huijia, Dong, Xue, Kuo, Tang-Wei, Grover, Ronald O., Parrish, Scott E.
Distillation-based Droplet Modeling of Non-Ideal Oxygenated Gasoline Blends: Investigating the Role of Droplet Evaporation on PM Emissions2017-01-05813/28/2017
In some studies, a relationship has been observed between increasing ethanol content in gasoline and increased particulate matter (PM) emissions from vehicles equipped with spark ignition engines. The fundamental cause of the PM increase seen for moderate ethanol concentrations is not well understood. Ethanol features a greater heat of vaporization (HOV) than gasoline and also influences vaporization by altering the liquid and vapor composition throughout the distillation process. A droplet vaporization model was developed to explore ethanol’s effect on the evaporation of aromatic compounds known to be PM precursors. The evolving droplet composition is modeled as a distillation process, with non-ideal interactions between oxygenates and hydrocarbons accounted for using UNIFAC group contribution theory. Predicted composition and distillation curves were validated by experiments. Detailed hydrocarbon analysis was applied to fuel samples and to distillate fractions, and used as input for the initial droplet composition. With composition calculated throughout the distillation, the changing HOV and other physical properties can be found using reference data. The droplet can thus be modeled in terms of energy transfer, which in turn provides the transient mass transfer, droplet temperature, and droplet diameter. Model predictions suggest that non-ideal vapor-liquid equilibrium along with an increase in HOV can alter the droplet composition evolution. Results predict that the presence of ethanol causes enrichment of the higher boiling fractions (T90+) in the aromatic components as well as lengthens the droplet lifetime. A simulation of the evaporation process in a transient environment as experienced within an engine cylinder predicts a decrease in mixing time of the heaviest fractions of the fuel prior to spark initiation, possibly explaining observations linking ethanol to PM.
Burke, Stephen C., Ratcliff, Matthew, McCormick, Robert, Rhoads, Robert, Windom, Bret
Significance of RON, MON, and LTHR for Knock Limits of Compositionally Dissimilar Gasoline Fuels in a DISI Engine2017-01-06623/28/2017
Spark-ignition (SI) engine efficiency is typically limited by fuel auto-ignition resistance, which is described in practice by the Research Octane Number (RON) and the Motor Octane Number (MON). The goal of this work is to assess whether fuel properties (i.e. RON, MON, and heat of vaporization) are sufficient to describe the antiknock behavior of varying gasoline formulations in modern engines. To this end, the auto-ignition resistance of three compositionally dissimilar gasoline-like fuels with identical RON values and varying or non-varying MON values were evaluated in a modern, prototype, 12:1 compression ratio, high-swirl (by nature of intake valve deactivation), directly injected spark ignition (DISI) engine at 1400 RPM. The three gasolines are an alkylate blend (RON=98, MON=97), a blend with high aromatic content (RON=98, MON=88), and a blend of 30% ethanol by volume with a gasoline BOB (RON=98, MON=87; see Table 2 for details). The preliminary findings of this work are that RON and MON, when coupled with latent heat of vaporization information, are sufficient to describe the auto-ignition resistance of a fuel to a degree such that knock-limited combustion phasing shows no measurable differences. While the tested fuels yielded no inconsistencies between their ratings (RON and MON) and properties (latent heat of vaporization) and their performance in a DISI engine, measurable differences were found among the three tested fuels. Specifically, the manner in which the fuels obtained knock-resistance varied, be it through thermal tolerance, charge cooling, or lack of charge-heating Low-Temperature Heat Release (LTHR). In addition, the fuels’ knock-limited combustion phasing responses to variations in intake pressure and intake temperature varied with their thermal tolerance and tendency towards LTHR. Yet these dissimilar behaviors combine to produce similar anti-knock qualities and engine performance for naturally-aspirated operation.
Vuilleumier, David, Sjöberg, Magnus
Influence of Ethanol Blends on Low Speed Pre-Ignition in Turbocharged, Direct-Injection Gasoline Engines2017-01-06873/28/2017
Modern combustion engines must meet increasingly higher requirements concerning emission standards, fuel economy, performance characteristics and comfort. Especially fuel consumption and the related CO2 emissions were moved into public focus within the last years. One possibility to meet those requirements is downsizing. Engine downsizing is intended to achieve a reduction of fuel consumption through measures that allow reducing displacement while simultaneously keeping or increasing power and torque output. However, to reach that goal, downsized engines need high brake mean effective pressure levels which are well in excess of 20bar. When targeting these high output levels at low engine speeds, undesired combustion events with high cylinder peak pressures can occur that can severely damage the engine. These phenomena, typically called low speed pre-ignition (LSPI), set currently an undesired limit to downsizing. This study analyzes the influence of ethanol fuel content on low speed pre-ignition events in a direct-injection turbo charged gasoline engine with a homogeneous (λ = 1) common rail high pressure injection system, side mounted multi-hole injectors and dual variable valve timing. All experiments were conducted on a steady state engine test bench with intake air, coolant, oil and fuel conditioning to be able to separate fuel effects from boundary condition influences. In addition, the engine was equipped with a prototype engine controller that allows to negate the influence of control algorithms on combustion. Four ethanol fuels containing different levels of ethanol were blended using the same base fuel and denatured ethanol. The investigated blends included E10, E20, E30 and E50 fuels. Subsequently, test runs were performed to understand the impact of different ethanol blends on occurrence, number and pressure characteristics of LSPI.
Haenel, Patrick, Kleeberg, Henning, de Bruijn, Rob, Tomazic, Dean
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