Browse Topic: Cetane

Items (320)
Find
Oxidation of Soybean Biodiesel Fuel in Diesel Engine Oils04-12-03-001512/5/2019
Abstract During diesel engine operation, some fuel is entrained in engine oil, particularly as a consequence of strategies to regenerate NOx traps or particle filters. This “fuel dilution” of oil can adversely affect engine oil properties and performance. Compared to diesel fuel, biodiesel is more prone to fuel dilution and more susceptible to oxidation. Oxidation stability experiments were conducted at 160°C using a modified Rapid Small-Scale Oxidation Test (RSSOT) and a Rancimat instrument with 0, 5, 10, and 20 wt% biodiesel in four fully formulated engine oils, two partially formulated engine oils, and two base oils. These experiments showed decreasing oxidation stability with increasing biodiesel content. An exception was noted with the least stable oils (two base oils and one engine oil) in which 5 wt% biodiesel improved the oxidation stability relative to oil without biodiesel. Experiments with biodiesel distillation fractions identified this stability enhancement within the least volatile biodiesel fraction, consistent with natural antioxidants in the biodiesel. Omission of two engine oil additives, antioxidants and zinc dialkyldithiophosphates (ZDDP), led to an unexpected increase in oxidation stability (with and without biodiesel). Time-series oxidation experiments at 160°C with one of the fully formulated engine oils, with and without 20 wt% biodiesel, demonstrated that the biodiesel caused greater oxidation instability and extent of oxidation, greater formation of peroxides and reduction in total base number (TBN), increased ester content, and higher density. Kinematic viscosity increased with aging time and eventually surpassed that of the engine oil aged without biodiesel. With extended aging time, the fully formulated engine oil containing biodiesel “broke,” forming black tar-like materials with high viscosity.
Ball, James C., Anderson, James E., Duckworth, Jacob A., Uy, Dairene, Wallington, Timothy J.
Low- to High-Temperature Reaction Transition in a Small-Bore Optical Gasoline Compression Ignition (GCI) Engine03-12-05-00318/19/2019
Abstract This study shows the development of low-temperature and high-temperature reactions in a gasoline-fuelled compression ignition (GCI) engine realizing partially premixed combustion for high efficiency and low emissions. The focus is how the ignition occurs during the low- to high-temperature reaction transition and how it varies due to single- and double-injection strategies. In an optically accessible, single-cylinder small-bore diesel engine equipped with a common-rail fuel injection system, planar laser-induced fluorescence (PLIF) imaging of formaldehyde (HCHO-PLIF), hydroxyl (OH-PLIF), and fuel (fuel-PLIF) has been performed. This was complemented with high-speed imaging of combustion luminosity and chemiluminescence imaging of cool flame and OH*. The diagnostics were performed for two different fuels including conventional diesel as a reference case and then a kerosene-based jet fuel which is a low-ignition quality fuel with cetane number of 30, firstly with single near top dead center (TDC) injection and then a double-injection strategy implementing very early injection and late injection in the same engine. For diesel combustion, it is shown that the cool-flame and HCHO signals appear from the jet axis before spreading downstream towards the bowl wall. The OH radicals present in the high-temperature reaction zones also show a similar development pattern with distinctive reaction zones forming from the jet axis and then near the bowl wall for each nozzle hole. When the reactions occur near the bowl wall, the HCHO and OH radicals coexist. Later, the high-reaction zones merge with each other due to jet-wall and jet-jet interactions. In comparison, the single-injection GCI combustion shows HCHO signals appearing from the bowl-wall region due to extended ignition delay. The OH radicals develop out of this HCHO region and show a more sequential development pattern than diesel combustion. The single-injection GCI also involves multiple ignition kernels that progressively merge to form larger reaction zones. The double-injection GCI combustion has higher charge premixing than the other cases, and due to very early first injection, the mixture homogeneity is also much higher. This is evidenced by a higher consumption rate of HCHO and faster development of OH across the entire reaction zones, indicating faster low- to high-temperature reaction transition. These fundamental findings explain why GCI combustion generates less soot and NO than diesel combustion as well as how double-injection GCI combustion achieves better low-load stability than the single-injection.
Goyal, Harsh, Zhang, Yilong, Kook, Sanghoon, Kim, Kenneth S., Kweon, Chol-Bum
Screening of Potential Biomass-Derived Streams as Fuel Blendstocks for Mixing Controlled Compression Ignition Combustion2019-01-05704/2/2019
Mixing controlled compression ignition, i.e., diesel engines are efficient and are likely to continue to be the primary means for movement of goods for many years. Low-net-carbon biofuels have the potential to significantly reduce the carbon footprint of diesel combustion and could have advantageous properties for combustion, such as high cetane number and reduced engine-out particle and NOx emissions. We developed a list of over 400 potential biomass-derived diesel blendstocks and populated a database with the properties and characteristics of these materials. Fuel properties were determined by measurement, model prediction, or literature review. Screening criteria were developed to determine if a blendstock met the basic requirements for handling in the diesel distribution system and use as a blend with conventional diesel. Criteria included cetane number ≥40, flashpoint ≥52°C, and boiling point or T90 ≤338°C. Blendstocks needed to be soluble in diesel fuel, have a toxicity no worse than conventional diesel, not be corrosive, and be compatible with fuel system elastomers. Additionally, cloud point or freezing point below 0°C was required. Screening based on blendstock properties produced a list of 12 that were available as fuels or reagent chemicals or could be synthesized by biofuels production researchers. This group included alkanes, alcohols, esters, and ethers. These candidates were further examined for their impact fuel properties upon blending with a conventional diesel fuel. Blend properties included cetane number, lubricity, conductivity, oxidation stability, and viscosity. Results indicate that all 12 candidates can meet the basic requirements for diesel fuel blending, although in some cases would require additive treatment to meet requirements for lubricity, conductivity, and oxidation stability.
Fioroni, Gina, Fouts, Lisa, Luecke, Jon, Vardon, Derek, Huq, Nabila, Christensen, Earl, Huo, Xiangchen, Alleman, Teresa, McCormick, Robert, Kass, Michael, Polikarpov, Evgueni, Kukkadapu, Goutham, Whitesides, Russell A.
Combustion Characteristics of Cottonseed Biodiesel and Chicken Fat Biodiesel Mixture in a Multi-Cylinder Compression Ignition Engine2019-01-00151/15/2019
Although waste animal fats such as chicken fat are promising alternative energy sources, biodiesels produced from these type of feedstocks hardly satisfies the EN14214 biodiesel standards. In this study, biomixtures were prepared by blending cottonseed biodiesel and chicken rendering fat biodiesel which were produced via transesterification method. Biodiesels were blended with each other at 60/40, 50/50 and 30/70 volume ratios to produce CO60CH40, CO50CH50 and CO30CH70 fuels. First, fuel properties of the neat biodiesels and novel biomixtures were measured and compared to European biodiesel standards and diesel. Then, the engine performance, combustion characteristics and exhaust emissions of these novel biomixture fuels were measured in a three-cylinder indirect injection diesel engine under various engine loads and at constant speed of 1500 rpm. The fuel characterisation showed that CO60CH40 and CO50CH50 biomixtures met the European standards. The Brake Specific Energy Consumption (BSEC) and Brake Thermal Efficiency (BTE) of all biomixtures were comparable with CO100, CH100 and diesel at the full engine load. The combustion results revealed that the maximum in-cylinder pressure and energy release values of the CO50CH50 were 4.2% and 4.4% higher than the diesel at full engine load because of optimised fuel properties of biomixture such as molecular structure, viscosity, cetane number and iodine value. CO50CH50 had 2.9% reduced CO2 and comparable CO emission compared to diesel, which were also 5.6% and 13% lower than cottonseed biodiesel respectively. However, NO emission of CO50CH50 was found 3.8% and 5.8% higher than diesel and cottonseed biodiesel. A 6.5% reduction on NO emission was observed when CO60CH40 biomixture fuel was used instead of diesel. To conclude, this research showed that blending of cottonseed and chicken fat biodiesels is a promising approach to meet the EN14214 standards, improve in-cylinder pressure, optimise energy release and reduce exhaust emissions. Blending of different biodiesels will be tested as a future work.
Masera, K., Hossain, A. K.
Optical Diagnostics of Spray Characteristics and Soot Volume Fractions of n-Butanol, n-Octanol, Diesel, and Hydrotreated Vegetable Oil Blends in a Constant Volume Combustion Chamber2019-01-00191/15/2019
The effects of using n-butanol, n-octanol, fossil Diesel, hydrotreated vegetable oil (HVO), and blends of these fuels on spray penetration, flame and soot characteristics were investigated in a high-pressure high-temperature constant volume combustion chamber designed to mimic a heavy duty Diesel engine. Backlight illumination was used to capture liquid and vapor phase spray images with a high-speed camera. The flame lift-off length (LOL) and ignition delay were determined by analyzing OH* chemiluminescence images. Laser extinction diagnostics were used to measure the spatially and temporally resolved soot volume fraction. The spray experiments were performed by injecting fuels under non-combusting (623 K) and combusting (823 K) conditions at a fixed ambient air density of 26 kg/m3. A Scania 0.19 mm single straight hole injector and Scania XPI common rail fuel supply system were used to produce injection pressures of 120 MPa and 180 MPa. To evaluate the effect of cetane number (CN) variation on combustion processes and soot emissions, di-tertiary-butyl peroxide (DTBP) was added to one blend to modify its CN without greatly altering its composition. The different fuels exhibited similar vapor phase penetration, but their liquid phase penetration varied significantly with the fuels’ physical properties. HVO exhibited the longest steady state liquid penetration. A fuel has a longer ignition delay, resulting in a longer flame lift-off length and thus a lower soot optical thickness and soot volume fraction distribution. Compared to Diesel fuel, n-butanol blends and n-octanol produced much lower soot emissions because of their oxygen content, lower stoichiometric A/F ratio, and high latent heat of vaporization.
Zhang, Tankai, Andersson, Mats, Munch, Karin, Denbratt, Ingemar
Comparison of Long-Chain Alcohol Blends, HVO and Diesel on Spray Characteristics, Ignition and Soot Formation2019-01-00181/15/2019
Spray characteristics of fossil Diesel fuel, hydrotreated vegetable oil (HVO) and two oxygenated fuel blends were studied to elucidate the combustion process. The fuels were studied in an optically accessible high-pressure/high-temperature chamber under non-combusting (623 K, 4.69 MPa) and combusting (823 K, 6.04 MPa) conditions. The fuel blends contained the long-chain alcohol 2-ethylhexanol (EH), HVO and either 20 vol.% Diesel or 7 vol.% rapeseed methyl ester (RME) and were designed to have a Diesel-like cetane number (CN). Injection pressures were set to 120 MPa and 180 MPa and the gas density was held constant at 26 kg/m3. Under non-combusting conditions, shadow imaging revealed the penetration length of the liquid and vapor phase of the spray. Under combusting conditions, the lift-off length and soot volume fraction were measured by simultaneously recording time-resolved two-dimensional laser extinction, flame luminosity and OH* chemiluminescence images. The ignition delay and start of soot formation were also recorded. Under non-combusting conditions at both injection pressures, the liquid penetration length was higher for the blends and HVO compared to Diesel, whereas the vapor penetration length was similar for all fuels. Under combusting conditions, the liquid penetration length of all the tested fuels was similar. Despite different CNs, the ignition delay was similar for Diesel and HVO. The EH blends had an increased ignition delay compared to Diesel, despite having the same CN. The lift-off length was found to be highest for the blend containing the highest share of EH. In agreement with previously published scaling relations, the lift-off length increased with increasing injection pressure. The soot volume fraction was found to be lower for the blends, in agreement with engine studies.
Preuss, Josefine Kim, Munch, Karin, Andersson, Mats, Denbratt, Ingemar
An Optical Study on the Combustion of Gasoline/PODEn Blends in a Constant Volume Vessel2018-01-17489/10/2018
Polyoxymethylene dimethyl ethers (PODEn) have high cetane number, high oxygen content and high volatility, therefore can be added to gasoline to optimize the performance and soot emission of Gasoline Compression Ignition (GCI) combustion. High speed imaging was used to investigate the spray and combustion process of gasoline/PODEn blends (PODEn volume fraction 0%-30%) under various ambient conditions and injection strategies in a constant volume vessel. Results showed that with an increase of PODEn proportion from 10% to 30%, liquid-phase penetration of the spray increased slightly, ignition delay decreased from 3.8 ms to 2.0 ms and flame lift off length decreased 29.4%, causing a significant increase of the flame luminance. For blends with 20% PODEn, when ambient temperature decreased from 893 K to 823 K, the ignition delay increased 1.3 ms and the flame luminance got lower. When increasing the injection pressure, the liquid phase length and the ignition delay got a little longer and the flame luminance and flame duration decreased. Long spray results showed that soot formed in higher PODEn flames oxidized earlier and quicker. The parameter changes that can extend the ignition delay all gave rise to the decrease of flame luminance because of the increase of the proportion of premixed combustion.
Ma, Yue, Cui, Longxi, Ma, Xiao, Wang, Zhi, Shuai, Shi-Jin
POMDME as an Alternative Pilot Fuel for Dual-Fuel Engines: Optical Study in a RCEM and Application in an Automotive Size Dual-Fuel Diesel Engine2018-01-17349/10/2018
Dual-fuel natural gas engines are seen as an attractive solution for simultaneous reduction of pollutant and CO2 emissions while maintaining high engine thermal efficiency. However, engines of this type exhibit a tradeoff between misfire as well as high UHC emissions for small pilot injection amounts and higher emissions of soot and NOX for operation strategies with higher pilot fuel proportion. The aim of this study was to investigate POMDME as an alternative pilot fuel having the potential to mitigate the emissions tradeoff, enabling smokeless combustion due to high degree of oxygenation, and being less prone to misfire due to its higher cetane number. Furthermore, POMDME can be synthetized carbon neutrally. First, characteristics of POMDME ignition in methane/air mixture and the transition into premixed flame propagation were investigated optically in a rapid compression-expansion machine (RCEM) by employing Schlieren and OH* chemiluminescence imaging. A single-hole coaxial injector mounted at the cylinder periphery was used to admit POMDME or n-dodecane as the reference pilot fuel. In the second stage, POMDME was applied as a pilot-fuel in a VW 2 l 4-cylinder industrial Diesel engine modified for dual-fuel operation. Engine performance with POMDME and EN590 Diesel pilot-fuels was compared. In the RCEM, in air, dodecane and POMDME exhibit similar ignition delay times. In methane/air mixtures, ignition of both pilot fuels was deferred with increasing methane content, with stronger influence on POMDME than on dodecane. Indication of pilot-fuel over-mixing was observed for the shortest considered POMDME injections. In the engine experiment, while keeping the total combustion equivalence ratio constant, POMDME was found to have shorter ignition delays than Diesel fuel, attributed to its higher cetane number. At constant engine load using POMDME instead of Diesel pilot fuel, stable operation with lower pilot-fuel energy and mass input was possible along with soot mass reduction to close to zero.
Srna, Aleš, Barro, Christophe, Herrmann, Kai, Möri, Fabio, Hutter, Richard, Boulouchos, Konstantinos
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.
Characterization of Hydroprocessed Used Cooking Oils as High Cetane Number Blending Component for Automotive Diesel2018-01-17459/10/2018
Renewable substitutes for transportation fuels have had an important role in the recent years. Hydrotreated vegetable oils (HVO) are produced from two stage hydrotreating process of vegetable oils. The second stage of this hydroteating process is used to convert normal paraffins to isoparaffins in order to improve cold flow properties of these fuels. As this stage is a high energy consuming process, it is of interest to investigate the characteristics and the usability of the first stage of hydrotreatment of lipids. This paper examines the properties of alternative fuel derived from the hydrotreatment of used cooking oil (UCO). Used cooking oil is a difficult feedstock for biodiesel production. The hydrotreating of UCO converts triglycerides mainly into normal paraffins within the diesel fuel range. The hydrotreated UCO (HUCO) has an excellent cetane number and cetane index (>90), but very poor cold flow properties. As the amount of the produced HUCO is limited, the main idea is to use it in blends with petroleum diesel fuel. For this reason, the HUCO was blended with ultra-low diesel fuel (ULSD) and low cetane number high aromatic middle distillate. The results showed that ternary blends of these fuels can produce fuel that meets the specifications set by EN 590 standard, mainly summer grade fuel, as the poor cold flow properties of the HUCO affect negatively the cold flow properties of the blend. The lubricity of the HUCO does not meet EN 590 standards, but the blends have improved lubricating characteristics, within specification limits.
Karonis, Dimitrios, Zahos Siagos, Iraklis, Bezergianni, Stella
Diesel Fuel Improvers and Their Effect on Microbial Stability of Diesel/Biodiesel Blends2018-01-17519/10/2018
Additives that enhance properties, such as cetane number or cold flow, are introduced in diesel-biodiesel blends in order to upgrade its performance as well as to aid its handling and distribution. Furthermore, in order to protect the engine and fuel operating system equipment, diesel fuel may be treated with corrosion inhibitors and detergents. However, additives could also have an impact on other parameters beyond those that they are intended to boost. In the present study the effect of diesel fuel improvers on fuel’s microbial stability is examined. An additive-free ultra low sulfur diesel (ULSD) was blended with Soybean Fatty Acid Methyl Esters (FAME) and the resulting blend was treated separately with a series of commercially available diesel fuel additives. Specific products belonging to the groups of cold-flow improvers, cetane improvers, metal deactivators and corrosion inhibitors were employed and were added both at the recommended treating rate as well as in a range of concentrations (1000, 250 and 500 ppm). Following to this, the impact of those agents on microbial proliferation in diesel fuel was studied under certain testing protocols for detecting and evaluating substances that could inhibit fuel biodeterioration. Overall, the results demonstrate that certain additives primarily added to diesel fuel in order to improve its performance contain substances that are non-supportive to bacterial proliferation.
Tsesmeli, Chrysovalanti, Dodos, George S., Zannikos, Fanourios
Effects of Different Injection Strategies and EGR on Partially Premixed Combustion2018-01-17989/10/2018
Premixed Charge Compression Ignition concepts are promising to reduce NOx and soot simultaneously and keeping a high thermal efficiency. Partially premixed combustion is a single fuel variant of this new combustion concepts applying a fuel with a low cetane number to achieve the necessary long ignition delay. In this study, multiple injection strategies are studied in the partially premixed combustion approach to reach stable combustion and ultra-low NOx and soot emission at 15.5 bar gross indicated mean effective pressure. Three different injection strategies (single injection, pilot-main injection, main-post injection) are experimentally investigated on a heavy duty compression ignition engine. A fuel blend (70 vol% n-butanol and 30 vol% n-heptane) was tested. The effects of different pilot and post-injection timing, as well as Exhaust-gas Recirculation rate on different injection strategies investigated. All the measurements were performed at the same load, combustion phasing, lambda and engine speed. The results show that all three injection strategies produced ultra-low soot emission, while less NOx emission was noticed for pilot-main injection because of less diffusion combustion mode. Pilot-main injection strategy decreases the maximum pressure rise rate effectively compared to single injection. For pilot-main injection at 15.5 bar gross indicated mean effective pressure, when 24.3% (pilot/total fuel mass ratio) of fuel injected at −30 crank angle after top dead center in the pilot and the rest injected in the main with 45% EGR rate, 48.97% gross indicated efficiency is achieved. In addition, ultra-low soot (0.19 ppm) and NOx (0.327 g/kWh) emissions are achieved respectively without using after treatment.
Han, Jinlin, Wang, Shuli, Somers, Bart
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
A Fuel Sensitive Ignition Delay Model for Direct Injection Diesel Engine Operating under EGR Diluted Conditions2018-01-02314/3/2018
This empirical work investigates the impacts of thermodynamic parameters, such as pressure and temperature, and fuel properties, such as fuel Cetane number and aromatic contents on ignition delay in diesel engines. Systematic tests are conducted on a single-cylinder research engine to evaluate the ignition delay changes due to the fuel property differences at low, medium and high engine loads under different EGR dilution ratios. The test fuels offer a range of Cetane numbers from 28 to 54.2 and aromatic contents volume ratios from 19.4% to 46.6%. The experimental results of ignition delays are used to derive an ignition delay model modified from Arrhenius’ expression. Following the same format of Arrhenius’ equation, the model incorporates the pressure and temperature effects, and further includes the impacts of intake oxygen concentration, fuel Cetane number and aromatic contents volume ratio on the ignition delay. The model is verified by results obtained under different engine loads and with different fuels. It is shown from the results that the inclusion of oxygen concentration improves the accuracy in predicting the ignition delays in the EGR diluted conditions. The inclusion of Cetane number and aromatic contents in the ignition delay model improves the adaptivity of the model, so that it can be used to predict the ignition delay of different fuels with improved accuracy.
Yang, Zhenyi, Han, Xiaoye, Yu, Shui, Yu, Xiao, Wang, Meiping, Zheng, Ming, Ting, David
Measurement of Engine Vibrations with a Fuel Blend of Recycled Lubricating Oil and Diesel Oil2017-01-233310/8/2017
Aiming for cleaner and more efficient energy from the internal combustion engines makes necessary to ensure the special conditions for exploitation of alternative fuels. The engine vibrations are primarily understood as effects of mechanical failures, but they are also a subject of the fuel combustion effects. These effects depend on the fuel type and its ability to complete the combustion process. The vibrations of a diesel engine were measured and analyzed with a frequency spectrum calculated with fast Fourier transforms. The engine was operated with a fuel blend of 10 % recycled lubricating oil with 90% diesel fuel as well as with neat diesel. It was found that the engine operation with this fuel blend has a lower vibration level in comparison with the use of neat diesel fuel. The goal of this research is to determine the properties of the fuel blend, which provide more stability to the engine by means of vibrations reduction. The fuel properties that influence the engine stability are the flash point, the cetane number and the heat value. Improvements of these properties allow keeping of the engine performance with better stability during its operation at different speeds. Testing of the engine performance by means of vibrations analysis is a powerful tool to determine engine behavior from the functional and endurance point of view. Vibrations measurements of the diesel run on different fuel types and properties make possible to choose and determine the fuel properties that bring higher stability to the engine.
Gutierrez, Marcos, Castillo, Andres, Iniguez, Juan, Reyes, Gorky
Lubricity of Diesel Fuel Hydrocarbons and Surrogate Fuels2017-01-229210/8/2017
The aim of this study is to investigate the lubricity of hydrocarbons that constitute components of petroleum diesel fuel. A number of typical hydrocarbon compounds were selected as representative of the group types of alkanes (paraffins), cycloalkanes (naphthenes) and aromatics, similar to those that are present in diesel fuel. The lubricity of these substances was examined in a High Frequency Reciprocating Rig (HFRR) apparatus according to the ISO 12156-1 standard method. Thereafter, a series of diesel surrogate fuel were prepared from the above substances based on literature data for diesel fuel composition and on the previously obtained results. These model fuels were assessed regarding their lubricating performance in order to evaluate how each individual component can affect the lubricity of the final fuel. In addition to this, commercial, additive-free diesel fuel samples were analyzed per the previously mentioned procedure and were used as reference fuels for a comparative assessment.
Dodos, George S., Vassileiou, Florentia, Karonis, Dimitrios
A Mathematical Model for the Vapour Composition and Flammability of Gasoline - Diesel Mixtures in a Fuel Tank2017-01-240710/8/2017
Low Temperature Combustion using compression ignition may provide high efficiency combined with low emissions of oxides of nitrogen and soot. This process is facilitated by fuels with lower cetane number than standard diesel fuel. Mixtures of gasoline and diesel (“dieseline”) may be one way of achieving this, but a practical concern is the flammability of the headspace vapours in the vehicle fuel tank. Gasoline is much more volatile than diesel so, at most ambient temperatures, the headspace vapours in the tank are too rich to burn. A gasoline/diesel mixture in a fuel tank therefore can result in a flammable headspace, particularly at cold ambient temperatures. A mathematical model is presented that predicts the flammability of the headspace vapours in a tank containing mixtures of gasoline and diesel fuel. Fourteen hydrocarbons and ethanol represent the volatile components. Heavier components are treated as non-volatile diluents in the liquid phase. The non-ideality of the blends of hydrocarbons and ethanol is accounted for using activity coefficients. Predictions for dry vapour pressure equivalent (DVPE), vapour phase composition and flammability are compared to experimental data for 12 mixtures of 4 base gasolines, some containing alcohol, a single diesel fuel and various quantities of additional ethanol. A 5% fuel tank fill level and a total tank pressure of 1 atmosphere were used. The model predicted DVPE for both base gasolines and dieseline blends that were within 2-4% of measured values. Predicted upper temperature limits of flammability were consistently 5-10°C higher than measured in this apparatus. The discrepancy was attributed mainly to the impact of downward flame propagation in this apparatus, compared to upward propagation used in flammability data found in the literature and used in the model.
Bardon, Michael, Pucher, Greg, Gardiner, David, Ariztegui, Javier, Cracknell, Roger, Hamje, Heather, Pellegrini, Leonardo, Rickeard, David
Effects of Biofuels on the Mixture Formation and Ignition Process in Diesel-Like Jets2017-01-233210/8/2017
In order to reduce engine out CO2 emissions it is a main subject to find new alternative fuels out of renewable sources. For this paper, several fuels were selected which can be produced out of biomass or with hydrogen which is generated directly via electrolysis with electricity from renewable sources. All fuels are compared to conventional diesel fuel and two diesel surrogates. It is well known that there can be a large effect of fuel properties on mixture formation and combustion, which may result in a completely different engine performance compared to the operation with conventional diesel fuels. Mixture formation and ignition behavior can also largely affect the pollutant formation. The knowledge of the combustion behavior is also important to design new engine geometries or implement new calibrations for an existing engine. The fuel properties of the investigated fuels comprise a large range, for example in case of the derived cetane number, from below 30 up to 100. In the study described here, different optical diagnostic methods are used simultaneously to monitor the behavior of these fuels. Measurements have been taken in a high pressure vessel at in-cylinder conditions representative for modern diesel engines. To investigate ignition and lift-off length of the fuel jets, high-speed detection of OH*-radicals was applied. In case of mixture formation analysis, Mie scattering measurement technique was used to detect the liquid penetration length and for the gas-phase, a shadowgraphy method was used. For both measurement techniques, a high speed camera was set up. By combining these optical measurement techniques, different amounts of premixed combustion have been observed for the different fuels. This can affect strongly the pollutant formation. Adding oxygen to a fuel increases the lift-off-length significantly at the same ignition delay time. Especially, the investigated fuel OME 3,4,5 seems to be a good alternative candidate regarding its sooting tendency.
Ottenwaelder, Tamara, Pischinger, Stefan
Influence of the Methanol Proportion on the Combustion Characteristics of Methanol-Biodiesel -F-T Diesel Blended Fuel2017-01-233510/8/2017
The F-T diesel made from coal by Fischer-Tropsch synthesis (F-T) can be used as a clean alternative fuel of diesel engine. To alleviate the drawback of high cost and low viscosity of F-T diesel, the Methanol-Biodiesel -F-T diesel multiple fuel (MBFT) was prepared by adding low-cost methanol and high-viscosity biodiesel as modifiers. Considering the immiscibility between alcohols and hydrocarbons, this paper carried out a series of stability tests and found that n-decanol was the optimum co-solvent of MBFT. The MBFTs blended by biodiesel with the volume fraction of 10% (10% vol.) and methanol with varying proportions of 0%, 5%, 10% and 15% vol. were denoted as M0, M5, M10 and M15, respectively. The increasing methanol proportion caused the increase of the oxygen content in the blended fuels and the reduction of heat value, surface tension and cetane number. The influence of methanol proportion on combustion characteristics of turbo-charging engine was studied. The study indicates that with the increase of the proportion of methanol, the ignition delay period of MBFT is prolonged 17.3∼37.1% while the normal combustion period and post combustion period is shortened 7.5∼16.0% and 28.3%∼49.0%, respectively; the peak value of heat release rate is increased 8.3%∼32.7% and the peak value phase is delayed 20.8%∼51.6%, the peak value of pressure rise rate also presents this trend. The combustion pressure oscillation amplitude increases 10.8%∼60.0% with the increase of methanol ratio, and the peak value phase of pressure oscillation is delayed 23.5%∼134.6%.
Yang, Tiantian, Wang, Tie, Qiao, Jing, Gao, Ji, Feng, Yizhuo, Sun, Dandan
Development of Surrogate Model for Oxygenated Wide-Distillation Fuel with Polyoxymethylene Dimethyl Ether2017-01-233610/8/2017
Polyoxymethylene Dimethyl Ether (PODEn) is a promising green additive to diesel fuel, owing to the unique chemical structure (CH3O[CH2O]nCH3, n≥2) and high cetane number. Together with the general wide-distillation fuel (WDF), which has an attractive potential to reduce the cost of production of vehicle fuel, the oxygenated WDF with PODEn can help achieve a high efficiency and low emissions of soot, NOx, HC, and CO simultaneously. In this paper, the first detailed reaction mechanism (225 species, 1082 reactions) which can describe the ignition characteristics of PODE1 and PODE3 at low temperature was developed. To validate this mechanism, rapid compression machine (RCM) was used to conduct the quasi-homogeneous experiments to measure the ignition delay time at various effective temperatures (600 K - 1000 K) for four different PODE1/O2/N2/Ar mixture (ϕ=0.25, O2:Ar=1:5; ϕ=0.5, O2:Ar:N2 = 1:2.5:2.5; ϕ=1.0, O2:Ar:N2 = 1:2.5:2.5; ϕ=1.0, O2:Ar:N2 = 1:5:5) and two different effective pressures (10 bar, 19 bar). Homogeneous Charge Compression Ignition (HCCI) experiments fueled with PODEn (n=1-4) mixture, in which the mass fraction of PODE3 is about 88.9% were also conducted in a naturally aspirated single-cylinder HCCI research engine at 1600 r/min, 0.4 charge-mass equivalence ratio, and 42% exhaust gas recirculation (EGR) to take the real engine working condition into consideration. Good agreement was achieved in the comparison of the experimental data and the simulation results utilizing our newly developed mechanism for PODE1 and PODE3. Considering the fact that PODEn is more frequently used as a blending component in diesel engine, a reduced multi-component mechanism (354 species, 943 reactions) for oxygenated WDF with PODEn (covering surrogates like PODE3, n-heptane, iso-octane, etc.) was developed and then validated with Direct-Injection Compression Ignition (DICI) engine experiments fueled with oxygenated WDF (gasoline/diesel/PODEn mixture) at 1600 r/min, 0.8 MPa indicated mean effective pressure (IMEP), and 25% EGR. This surrogate model will contribute to the design of oxygenated WDF by blending PODEn, and to the prediction of the combustion and emission characteristics of engines using oxygenated WDF.
He, Tanjin, Liu, Hao-ye, Wang, Yingdi, Wang, Boyuan, Liu, Hui, Wang, Zhi
Combustion Optimization of a Multi-Cylinder CI Engine Running with a Low RON Gasoline Fuel Considering Different Air Loop and After-Treatment Configurations2017-01-226410/8/2017
Recent work has demonstrated the potential of gasoline-like fuels to reduce NOx and particulate emissions when used in compression ignition engines. In this context, low research octane number (RON) gasoline, a refinery stream derived from the atmospheric crude oil distillation process, has been identified as a highly valuable fuel. In addition, thanks to its higher H/C ratio and energy content compared to diesel, CO2 benefits are also expected when used in such engines. In previous studies, different cetane number (CN) fuels have been evaluated and a CN 35 fuel has been selected. The assessment and the choice of the required engine hardware adapted to this fuel, such as the compression ratio, bowl pattern and nozzle design have been performed on a single cylinder compression-ignition engine. The purpose of this paper is to assess different air-path and after treatment system (ATS) definitions to maximize the potential of a low-RON gasoline fuel running on a multi-cylinder compression ignition engine. Low pressure (LP) and high pressure (HP) EGR were evaluated to fulfill Euro 6d standard with and without NOx after-treatment system. The CO2 benefits were estimated thanks to a specific Design of Experiment (DoE) methodology developed by IFPEN. The results were computed through the combination of 16 hot and cold operating points whereas 0D models were used to generate the ATS efficiencies. Meet the Euro 6 NOx regulation on WLTC without NOx ATS is possible with a complex LP+HP EGR air-path. Nevertheless, a greater CO2 potential was identified with HP EGR system combined with SCR. Once put into practice, Euro 6 regulation was met with a reduction of almost 7% of CO2 on WLTC. Noise levels were comparable to a Euro 5 diesel reference engine.
Won, Hyun Woo, Bouet, Alexandre, Kermani, Joseph, Duffour, Florence, Dosda, Simon
Simarouba Biodiesel Blends as an Alternative Fuel for Compression Ignition Engine and Its Optimization Using Multiple Regression Analysis on CI Engine Performance (BTE) and Emissions (CO 2 , HC) Characteristics2017-01-21369/19/2017
The objective of this work is to optimize the operating parameters of the Direct Injection Single Cylinder (5.2 kw) CI engine with respect to Brake Thermal Efficiency (BTE), Hydrocarbons (HC) and Carbon dioxide (CO2). For this investigation, we used Simarouba Biodiesel as an alternate fuel for diesel fuel which possesses low cetane number which is not sufficient to operate existing diesel engine. However, this could be combined with the diesel fuel in the form of blends. For this investigation four levels and four parameters were selected viz. Injection Pressure (IP), Fuel Fraction (FF), Compression Ratio (CR) and Injection Timing (Before TDC). Taguchi Method is used for minimizing the number of experiments and Multiple Regression Analysis is used to find the optimum condition. Three outputs variables such as; Brake Thermal Efficiency (BTE), content of HC particles and CO2 in the emission are measured and considered its influence on CI Engine performance. The test was carried out at full load condition and the optimized condition are found such as; 18:1 Compression Ratio, 250 bar Injection Pressure, 22° Injection Timing and 20% Fuel Fraction. The optimized condition gives better performance than diesel, HC emission is nearly similar as that for diesel fueled engine but CO2 slightly increases.
Sayyad, Almuddin Rustum, Salunke, Pratik, Jadhav, Sangram
Laser-Induced Incandescence Measurements of Tailor-Made Fuels in an Optical Single-Cylinder Diesel Engine2017-01-07113/28/2017
The influence of two oxygenated tailor-made fuels on soot formation and oxidation in an optical single cylinder research diesel engine has been studied. For the investigation a planar laser-induced incandescence (PLII) measurement technique was applied to the engine in order to detect and evaluate the planar soot distribution for the two bio fuels within a laser light sheet. Furthermore the OH* chemiluminescence and broad band soot luminosity was visualized by high speed imaging to compare the ignition and combustion behavior of tested fuels: Two C8 oxygenates, di-n-butylether (DNBE) and 1-octanol. Both fuels have the same molecular formula but differ in their molecular structure. DNBE ignites fast and burns mostly diffusive while 1-octanol has a low cetane number and therefore it has a longer ignition delay but a more homogeneous mixture at time of ignition. The two bio fuels were finally compared to conventional diesel fuel. The heat release reactions after ignition by means of the OH* chemiluminescence showed the fast igniting behavior of DNBE, with soot formation being delayed. The soot formation for DNBE was very similar to that of conventional diesel fuel. However, the amount of soot formed is lower and starts oxidizing earlier in the cycle according to the PLII signal. The OH* chemiluminescence signal of 1-octanol on the other hand shows a rapid burn out in the combustion chamber. Due to the homogenous mixture, hardly any soot formation takes place.
Klein, Daniel, Pischinger, Stefan
Emission Performance of Low Cetane Naphtha as Drop-In Fuel on a Multi-Cylinder Heavy-Duty Diesel Engine and Aftertreatment System2017-01-10003/28/2017
Greenhouse gas regulations and global economic growth are expected to drive a future demand shift towards diesel fuel in the transportation sector. This may create a market opportunity for cost-effective fuels in the light distillate range if they can be burned as efficiently and cleanly as diesel fuel. In this study, the emission performance of a low cetane number, low research octane number naphtha (CN 34, RON 56) was examined on a production 6-cylinder heavy-duty on-highway truck engine and aftertreatment system. Using only production hardware, both the engine-out and tailpipe emissions were examined during the heavy-duty emission testing cycles using naphtha and ultra-low-sulfur diesel (ULSD) fuels. Without any modifications to the hardware and software, the tailpipe emissions were comparable when using either naphtha or ULSD on the heavy duty test cycles. Overall lower CO2 emissions and fuel consumption were measured for naphtha due in part to its higher heating value and higher hydrogen to carbon ratio. Engine-out and tailpipe NOx emissions were lower for naphtha, and measured PM emissions were also lower due to naphtha’s higher volatility and lower aromatic content compared to ULSD. To help assess the potential impact on diesel particulate filter design and operation, engine-out PM samples were collected and characterized at a steady-state mid-speed, mid-load operating point. A significant reduction in elemental carbon in PM samples was observed for naphtha fuel, and similar oxidation rates and peak oxidation temperatures were measured for the PM from both fuels.
Lee, Jong, Zhang, Yu, Tzanetakis, Tom, Traver, Michael, Moses-DeBusk, Melanie, Storey, John, Partridge, William, Lance, Michael
Effects of Fuel Chemistry and Spray Properties on Particulate Size Distributions from Dual-Fuel Combustion Strategies2017-01-10053/28/2017
The effect of direct-injected fuel on particle size distributions (PSDs) of particulate matter emitted from dual-fuel combustion strategies was investigated. The PSD data were acquired from a light-duty single-cylinder diesel engine operated using conventional diesel combustion (CDC) and two diesel/natural gas dual-fuel combustion strategies. Three different direct-injection (DI) fuels (diesel, 2,6,10-trimethyldodecane, and a primary reference fuel blend) and two different injector nozzles were studied. The DI fuels were chosen to have similar energy and ignition characteristics (heat of combustion and cetane number) but different physical and chemical properties (volatility, aromatics %, viscosity, density). The two nozzles (with different orifice diameter and spray angle) allowed a wide range in DI fuel quantity for the dual-fuel combustion strategies. The results suggest that the physical and chemical properties of the DI fuel may have a strong impact on PSD distribution shape and accumulation-mode particle concentration for CDC and natural gas combustion with a diesel-pilot-injection strategy. For diesel/natural gas RCCI combustion the PSD was found to be insensitive to the DI fuel when using two-stage dilution with a volatile particle remover. The DI fuel quantity was found to slightly affect the PSD magnitude for dual-fuel combustion strategies.
Zhang, Yizhou, Ghandhi, Jaal, Rothamer, David
Performance Evaluation of the Ignition Quality Testers Equipped with TALM Precision Package (TALM-IQT™) Participating in the ASTM NEG Cetane Number Fuel Exchange Program2017-01-07203/28/2017
This paper is a continuation of work previously discussed in SAE 2014-01-0179 [1] and SAE 2015-01-0805 [2], which was intended to improve the capability and precision of the Ignition Quality Tester (IQT™) and associated ASTM D6890 [3]/CEN EN 15195 [4]/EI IP 498 [5] Test Methods. The results presented in those two papers indicated how the new generation of IQT™ with the TALM Precision Package upgrade can markedly improve the precision of the ASTM D6890, CEN EN 15195 and EI IP 498 Derived Cetane Number (DCN) test methods. This paper will evaluate the performance of the upgraded instruments over the past 21 months of their participation in ASTM’s National Fuel Exchange Group (NEG) diesel fuel exchange program. It will also present a comparison of the published precision of the ASTM Cetane Number (CN) and Derived Cetane Number (DCN) standard test methods that participated meaningfully in the ASTM NEG diesel fuel exchange program (ASTM D613 [6]/CEN EN ISO 5165 [7]/EI IP 41 [8] and ASTM D6890 [3]). In addition, it will present and discuss a comparison between the precision of these ASTM standard methods, the mini Inter-Laboratory Study presented in SAE 2015-01-0805 [2] and the recent test results from the ASTM NEG fuel exchange program (real world data). The real world results extracted from the NEG fuel exchange program’s monthly reports strongly support the findings of the two previous SAE papers. This paper shows that the D6890/EN 15195/IP 498 instruments equipped with the TALM Precision Package have clearly demonstrated a marked improvement in precision of the ASTM D6890 and CEN EN 15195 Test Methods.
Ramadan, Omar, Menard, Luc, Gardiner, David, Wilcox, Aaron, Webster, Gary
A Study on the Effects of Cetane Number on the Energy Balance between Differently Sized Engines2017-01-08053/28/2017
This paper investigates the effect of the cetane number (CN) of a diesel fuel on the energy balance between a light duty (1.9L) and medium duty (4.5L) diesel engine. The two engines have a similar stroke to bore (S/B) ratio, and all other control parameters including: geometric compression ratio, cylinder number, stroke, and combustion chamber, have been kept the same, meaning that only the displacement changes between the engine platforms. Two Coordinating Research Council (CRC) diesel fuels for advanced combustion engines (FACE) were studied. The two fuels were selected to have a similar distillation profile and aromatic content, but varying CN. The effects on the energy balance of the engines were considered at two operating conditions; a “low load” condition of 1500 rev/min (RPM) and nominally 1.88 bar brake mean effective pressure (BMEP), and a “medium load” condition of 1500 RPM and 5.65 BMEP. Results were recorded at the same crank angle 50% burn (CA50) condition to decouple fuel effects from engine effects. The results show that the CN of the fuel impacts the distribution of supplied fuel energy in both engine systems. At the low load condition, a decrease in the fractional cylinder heat transfer is seen for the medium duty engine as CN increases. In general, the sensitivity of the engines to CN is found to increase as engine load increases. At the medium load condition, the observed differences in the fractional heat transfer are larger, and this is especially true for the medium duty engine. This in turn balances the tradeoff between the changes in mixture temperatures and combustion durations. Moreover, as the CN increases, the energy lost to the exhaust increases for both engines at the medium load condition. This is in contrast to the low load condition, where increasing the CN increases the energy in the exhaust of the medium duty engine, but decreases the energy in the exhaust of the light duty engine. Finally, at the low load condition, a higher CN consistently increases the brake fuel efficiency of both engines. This is in contrast, to the medium load condition, where increasing the CN of the fuel increases the brake fuel efficiency of the light duty engine, but causes a slight decrease in the brake fuel efficiency of the medium duty engine.
Li, Jue, Bera, Tushar K., Parkes, Michael, Jacobs, Timothy J.
Derived Cetane Number, Distillation and Ignition Delay Properties of Diesel and Jet Fuels Containing Blended Synthetic Paraffinic Mixtures2016-01-907610/24/2016
Aviation turbine fuel and diesel fuel were blended with synthetic paraffins produced via two pathways and the combustion properties measured. Both aviation and diesel fuel containing synthetics produced from the fermentation of sugars, had a linear response to blending with decreasing ignition delay times from 5.05 - 3.52 ms for F-34 and 3.84 - 3.52 ms for F-76. For the same fuels blended with synthetics produced from the fermentation of alcohols, ignition delay times were increased out to 18.66 ms. The derived cetane number of the blends followed an inversely similar trend. Additionally, simulated distillation using ASTM D2887 at high synthetic paraffinic kerosene blend ratios resulted in the recovery temperatures being incorrectly reported. In this case, higher recovery volumes were at lower temperatures than earlier recovery points i.e. T90< T50, for SIP-SPK.
Abanteriba, Sylvester, Yildirim, Ulas, Webster, Renee, Evans, David, Rawson, Paul
Effects of Nozzle Geometry on the Characteristics of an Evaporating Diesel Spray2016-01-219710/17/2016
The effects of nozzle geometry on diesel spray characteristics were studied in a spray chamber under evaporating conditions using three single-hole nozzles, one cylindrical and two convergent, designated N1 (outlet diameter 140 μm, k-factor 0), N2 (outlet diameter 140 μm, k-factor 2) and N3 (outlet diameter 136 μm, k-factor 2). Spray experiments were performed with each nozzle at two constant gas densities (15 and 30 kg/m3) and an ambient temperature (673 K) at which evaporation occurs, with injection pressures ranging from 800 to 1600 bar. A light absorption and scattering method using visible and UV light was implemented, and shadow images of liquid and vapor phase fuel were recorded with high-speed video cameras. The cylindrical nozzle N1 yielded larger local vapor cone angles than the convergent nozzles N2 and N3 at both gas densities, and the difference became larger as the injection pressure increased. The vapor phase penetration values for nozzle N1 and N3 were quite similar and always lower than those for N2. This is consistent with the impingement measurements, which showed that the momentum flux of nozzle N1 was only slightly greater than that of nozzle N3, while that of nozzle N2 was substantially greater. The vapor volume fractions measured along the spray’s center line were well explained by the one-dimensional transient diesel jet model, indicating that diesel spray vaporization is controlled by turbulent fuel-air mixing.
Du, Chengjun, Andersson, Mats, Andersson, Sven
Advanced Fuel Formulation Approach using Blends of Paraffinic and Oxygenated Biofuels: Analysis of Emission Reduction Potential in a High Efficiency Diesel Combustion System2016-01-217910/17/2016
This work is a continuation of earlier results presented by the authors. In the current investigations the biofuels hydrogenated vegetable oil (HVO) and 1-octanol are investigated as pure components and compared to EN 590 Diesel. In a final step both biofuels are blended together in an appropriate ratio to tailor the fuels properties in order to obtain an optimal fuel for a clean combustion. The results of pure HVO indicate a significant reduction in CO-, HC- and combustion noise emissions at constant NOX levels. With regard to soot emissions, at higher part loads, the aromatic free, paraffinic composition of HVO showed a significant reduction compared to EN 590 petroleum Diesel fuel. But at lower loads the high cetane number leads to shorter ignition delays and therefore, ignition under richer conditions. These circumstances cause slightly increased soot emissions due to the current engine calibration and could easily be compensated by an optimized engine calibration. 1-octanol was identified by the cluster of excellence “Tailor-Made Fuels from Biomass (TMFB)” as a promising alternative biofuel which is virtually showing no soot emission. At low loads the HC- and CO emissions are lower compared to Diesel as well but at higher loads the CO emissions surpass the ones of Diesel fuel. However, due to the relatively low cetane number of 1-octanol, the sound emissions are the highest of the investigated fuels. By blending of HVO and 1-octanol the beneficial features of both fuels could be combined, while their individual drawbacks could be reduced. With the addition of 1-octanol, the higher soot emissions of HVO at low loads without an optimized calibration were reduced by more than 50 %. The soot emissions decreased due to the oxygen content of 1-octanol and the lower cetane number of the blend compared to neat HVO. In addition, much lower HC- and CO emissions were achieved, which are nearly half of petroleum based Diesel fuel. Also, the advantages of HVO in terms of combustion noise emissions are still maintained in the range of 3 dB less than baseline Diesel operation at lower part loads. The blending of a novel biofuel candidate (1-octanol) with an advanced commercially available biofuel (HVO) is a potential key step towards a soot- and NOx-free Diesel combustion.
Zubel, Marius, Bhardwaj, Om Parkash, Heuser, Benedikt, Holderbaum, Bastian, Doerr, Sebastian, Nuottimäki, Jukka
Naphtha Fuel on a Light Duty Single Cylinder Compression Ignition Engine with Two Different Compression Ratios2016-01-230210/17/2016
Gasoline-like fuels have been recently identified as good candidates to reduce NOX and particulate emissions when used in compression-ignition (CI) engines. In this context, straight-run naphtha, a refinery stream directly derived from the atmospheric crude oil distillation process, was identified as a highly valuable fuel. In addition, thanks to its higher H/C ratio and energy content (LHV) compared to diesel, CO2 benefits are also expected when using naphtha in such engines. In a previous study, wide ranges of Cetane Number naphtha fuels (CN 20 to 35) were evaluated to optimize CI combustion, with different bowls and nozzle designs. CN 35 naphtha fuel has been selected for its better robustness and lower HC and CO emissions. The purpose of the current study is to investigate the potential of CN 35 naphtha fuel on a light duty single-cylinder compression-ignition engine as well as the minimum required hardware modifications needed to properly run this fuel. Two different compression ratios: CR16 (stock piston) and CR17.5 were evaluated. The hydraulic flow rate of the nozzle was increased for naphtha to compensate for its lower fuel density vs. diesel. After optimization of the injection strategy, the results were compared to those obtained with a reference diesel fuel. Basic thermodynamic investigations in single injection without EGR confirm that CN 35 naphtha is more resistant to auto-ignition than diesel. This leads to a longer air-fuel premixing duration, particularly at low load operation, enabling lower soot emissions. Increasing load and then in-cylinder pressure and temperature tends to significantly decrease the low CN impact. By the optimization of combustion modes at NOX target, the premixed combustion with naphtha leads to better fuel consumption and lower particulate emissions than diesel, for the same levels of noise. Moreover, global CO2 emissions are reduced by approximately 7% compared to diesel. Compared to CR17.5, CR16 enables an earlier combustion phasing, as well as a higher degree of fuel stratification. This enables to limit HC and CO emissions at low loads and a better fuel consumption with CR16.
Won, Hyun Woo, Bouet, Alexandre, Duffour, Florence, Francqueville, Loic
Effect of Diesel Properties on Emissions and Fuel Consumption from Euro 4, 5 and 6 European Passenger Cars2016-01-224610/17/2016
Certain diesel fuel specification properties are considered to be environmental parameters according to the European Fuels Quality Directive (FQD, 2009/EC/30) and previous regulations. These limits included in the EN 590 specification were derived from the European Programme on Emissions, Fuels and Engine Technologies (EPEFE) which was carried out in the 1990’s on diesel vehicles meeting Euro 2 emissions standards. These limits could potentially constrain FAME blending levels higher than 7% v/v. In addition, no significant work has been conducted since to investigate whether relaxing these limits would give rise to performance or emissions debits or fuel consumption benefits in more modern vehicles. The objective of this test programme was to evaluate the impact of specific diesel properties on emissions and fuel consumption in Euro 4, Euro 5 and Euro 6 light-duty diesel vehicle technologies. The tests were conducted in two driving cycles, the New European Driving Cycle (NEDC) and the Worldwide harmonised Light duty Test Cycle (WLTC), which is considered closer to real driving and is going to be the new type approval test in the near future. Apart from FAME content, properties studied were Poly-Aromatic Hydrocarbon (PAH) content, density, and cetane number. Results of emissions testing will be presented and discussed including effects of the above fuel properties on particulates, NOx emissions, fuel consumption, energy consumption and CO2 emissions.
Williams, Rod, Hamje, Heather, Rickeard, David J, Bartsch, Thomas, Fittavolini, Corrado, Van de Heijning, Paul, Lehto, Kalle, Gunter, Garry, Ariztegui Cortijo, Javier, Zemroch, Peter J, Samaras, Zissis, Dimaratos, Athanasios
Experimental and Numerical Investigation of Ethanol/Diethyl Ether Mixtures in a CI Engine2016-01-218010/17/2016
The auto-ignition characteristics of diethyl ether (DEE)/ethanol mixtures are investigated in compression ignition (CI) engines both numerically and experimentally. While DEE has a higher derived cetane number (DCN) of 139, ethanol exhibits poor ignition characteristics with a DCN of 8. DEE was used as an ignition promoter for the operation of ethanol in a CI engine. Mixtures of DEE and ethanol (DE), i.e., DE75 (75% DEE + 25% ethanol), DE50 (50% DEE + 50% ethanol) and DE25 (25% DEE + 75% ethanol), were tested in a CI engine. While DE75 and DE50 auto-ignited at an inlet air pressure of 1.5 bar, DE25 failed to auto-ignite even at boosted pressure of 2 bar. The peak in-cylinder pressure for diesel and DE75 were comparable, while DE50 showed reduced peak in-cylinder pressure with delayed start of combustion (SOC). Numerical simulations were conducted to study the engine combustion characteristics of DE mixture. A comprehensive detailed chemical kinetic model was created to represent the combustion of DE mixtures. The detailed mechanism was then reduced using standard direct relation graph (DRG-X) method and coupled with 3D CFD code, CONVERGE, to simulate the experimental data. The simulation results showed that the effects of physical properties on DE50 combustion are negligible. Simulations of DE50 mixture revealed that the combustion is nearly homogenous, while diesel (n-heptane used as a surrogate) and DE75 showed similar combustion behavior with flame liftoff and diffusion controlled combustion. Diesel exhibited auto-ignition at an equivalence ratio of 2, while DE75 and DE50 showed auto-ignition in the equivalence ratio range of 1-1.5 and 0-1, respectively. The experiments and numerical simulations demonstrate how the high reactivity of DEE supports the auto-ignition of ethanol, while ethanol acts as a radical scavenger.
Sivasankaralingam, Vedharaj, Raman, Vallinayagam, Mubarak Ali, Mohammed Jaasim, Alfazazi, Adamu, Lu, Tianfeng, Im, Hong, Sarathy, S. Mani, Dibble, Robert
A Comparison of the Properties and Cold Flow Performance of ‘Summer’ and ‘Winter’ GTL Diesel2016-01-90745/18/2016
Gas to Liquids (GTL) diesel has been produced commercially for several years. GTL diesel is known for its excellent properties, including zero aromatics, near zero sulphur and a high cetane number. Most of the GTL diesel produced by commercial plants is utilised as a blend component, especially in blends up to 20%. In these applications, the cold flow properties are potentially less critical, as the cold flow properties of the blend will mostly be determined by the petroleum-derived component. In certain markets, however, it is possible that GTL diesel can be used as a neat diesel, therefore requiring good cold flow properties. An advantage of GTL technology is that the cold flow properties of GTL diesel can be tailored to meet the climatic requirements of a specific geographical area. In the current study, GTL diesel samples with cold flow properties ranging from ‘summer type’ to ‘winter type’ and varying intermediate cold flow qualities were evaluated. In line with expectations, it was shown that increasing the degree of isomerisation will improve the cold flow properties of the GTL diesel, whilst the other bulk properties such as density, cetane and viscosity of the fuels are not significantly altered. It is also shown that the excellent cold flow properties of these ‘winter type’ GTL fuels translate into excellent operability performance.
Wilken, Celeste, de Goede, Stefan, Viljoen, Carl
Extension of the Phenomenological 3-Arrhenius Auto-Ignition Model for Six Surrogate Automotive Fuels2016-01-07554/5/2016
An existing three-stage ignition delay model which has seen successful application to Primary Reference Fuels (PRFs) has been extended to six surrogate fuels which constitute potential candidates for future Homogeneous Charge Compression Ignition (HCCI) engines. The fuels include petroleum-derived and oxygenated components and can be divided into low, intermediate and high cetane number groups. A new methodology to obtain the model parameters is presented which relies jointly on simulation and experimental data: in a first step, constant volume adiabatic reactor simulations using chemical kinetic mechanisms are performed to generate ignition delays for a very wide range of conditions, namely variations in equivalence ratio, Exhaust Gas Recirculation (EGR), pressure and temperature. Based on this “virtual shock tube” data the 3-Arrhenius parameters for low- and high-temperature ignition delay and Negative Temperature Coefficient (NTC) regimes are determined by means of a genetic algorithm. In a second step, the parameterized 3-Arrhenius model is assessed by means of experimental auto-ignition delay data from a Rapid Compression Expansion Machine (RCEM). This data revealed a systematic over prediction of the low and high temperature ignition delays. A refinement of the pre-exponential parameters of the low and high ignition delay terms was carried out resulting in excellent agreement over a large range of operating conditions between model and measurements for all six fuels. The approach proposed in this study hence combines 1) the efficient generation of ‘numerical’ ignition delay data for surrogate fuels at different pressure, temperature, equivalence ratio and EGR levels for which the variations span much larger ranges than typically available from experiments, 2) the rapid parameterization of this dataset by means of genetic algorithms to derive “initial estimates” for the three-stage ignition model parameters, for which in 3) the final values are determined by retuning the pre-exponential parameters of the low and high ignition delay terms based on a wide range of measurements in a RCEM. To conclude the new methodology has successfully extended the application of the 3-Arrhenius model to Toluene Reference Fuels (TRFs), longer-chain alkanes and oxygenated fuels. The efficiency and robustness of the new methodology compared to the traditional usage of exclusively experimental data for model parameterization considerably extends its applicability to auto-ignition modeling for a variety of fuels. This will allow for broader use of such models for different fuels for HCCI engine calibration and control.
Blomberg, Christopher Kim, Mitakos, Dimitrios, Bardi, Michele, Boulouchos, Konstantinos, Wright, Yuri M., Vandersickel, Annelies
A Technical Evaluation of New Renewable Jet and Diesel Fuels Operated in Neat Form in Multiple Diesel Engines2016-01-08294/5/2016
The US Navy is in the process of evaluating Catalytic Hydrothermal Conversion Jet fuel (CHCJ-5) for inclusion in the JP-5 specification, MIL-DTL-5624, and evaluating Catalytic Hydrothermal Conversion Diesel fuel (CHCD-76) for inclusion in the F-76 specification, MILDTL-16884. CHC fuels are produced from renewable feedstocks such as triglycerides, plant oils, and fatty acids. A Catalytic Hydrothermolysis process chemically converts these feedstocks into a mixture of paraffins, cycloparaffins, aromatics, olefins, and organic acids. The resulting mixture is then hydroprocessed and fractionated to produce a kerosene (or diesel) product having a distillation profile comparable to traditional petroleum derived fuels. The end product is a fuel that is able to meet the jet (or diesel) chemical and physical MIL-SPEC requirements without blending with conventional petroleum fuels. Detailed physical and chemical characterizations are presented showing these new renewable fuels in neat form have similar properties as compared to their natural petroleum counterparts (JP-5 and F-76). Engine testing was performed using three highly instrumented engines (Waukesha, Yanmar and AM General). CHCJ-5 was compared to the combustion performance of JP-5, while CHCD-76 was compared to conventional diesel NATO F-76. Engine data from this testing was processed to compare the fuels on the basis of relative combustion metric changes. The results of this testing and analysis show that, in general, ignition delay is similar to or slightly shorter than the base fuel. Combustion phasing shifts are quite small, with the maximum rate of heat release showing a modest decrease with the CHC fuels due to their moderately higher cetane values. Overall, both CHC fuels have combustion changes that fall within Navy acceptance standards. Engine operation (including cold starting) with these new renewable neat fuels was similar to the base natural petroleum fuels with no concerns noted.
McDaniel, Andrew, Dickerson, Terrence, Luning-Prak, Dianne, Hamilton, Len, Cowart, Jim
A Comparison of Worldwide Fuels and their Effects on Combustion under Constant Volume Vessel Conditions2015-01-19199/1/2015
Worldwide diesel fuels differ in their composition and therefore in thermo-physical properties. Some of these properties are known to have little effect on the combustion process. Others, like the cetane number, have dramatic influence on the combustion formation and thus on the heat release rate and more important the formation of soot and NOx. In an experiment series various commercially available fuel types, like EN 590 [1], ASTM D975 [2] and JIS K 2204 [3], have been compared to alternative diesel fuels such as FAME, GtL and premium diesel fuel with increased cetane number. A specially designed research injector was used in order to provide full optical access to one single fuel jet injected and combusted in a constant volume vessel. First, the liquid fuel phase propagation has been investigated by means of Mie-scattering and the liquid penetration depth and the spray cone angle have been evaluated. Here, the fuels with a higher amount of low volatile components, such as high alkanes, show increased liquid penetration depth. The focus in this measurement series is set on the ignition and combustion behavior. A set of two cameras has been applied to investigate the integral flame signal, dominated by the black body radiation, and the chemical luminescence of both, the OH* and CH* radical. To acquire these combustion radicals, band pass filters were used. The combustion behavior of the different fuels differs strongly, not only in ignition delay, but also in the combustion propagation, which is in indicator for the heat release rate. It was not always possible to build a link between the ignition delay and the cetane number. Especially the FAME-diesel fuels show a shortened ignition delay but a lower maximum heat release rate. High cetane number fuels show a high gradient in heat release rate.
Vogel, Thomas, Riess, Sebastian, Wensing, Michael
Combustion and Noise Characteristics in a Diesel Engine with Hydrogen Addition and Pilot Injection2015-01-19229/1/2015
We experimentally investigated effects of pilot diesel-fuel injection on ignition timing variation and noise reduction in a diesel engine with hydrogen addition to the intake pipe. The pilot diesel-fuel injection suppressed ignition timing variation which was significant under hydrogen addition conditions. The heat release by the pilot diesel-fuel injection stably acted as an ignition source of the hydrogen-air mixture. The maximum in-cylinder pressure rise rate increased with the hydrogen fraction. However, the sound pressure level attained minimum around a specific hydrogen fraction.
Sakane, Ryota, Fujimura, Toshiki, Seo, Takehiko, Mikami, Masato
Ignition Quality Effects on Lift-Off Stabilization of Synthetic Fuels2015-01-07924/14/2015
The ignition and flame stabilization characteristics of two synthetic fuels, having significantly different cetane numbers, are investigated in a constant volume combustion vessel over a range of ambient conditions representative of a compression ignition engine operating at variable loads. The synthetic fuel with a cetane number of 63 (S-1) is characterized by ignition delays that are only moderately longer than n-dodecane (cetane number of 87) over a range of ambient conditions. By comparison, the synthetic fuel with a cetane number of 17 (S-2) requires temperatures approximately 300 K higher to achieve the same ignition delays. The much different ignition characteristics and operating temperature range present a scenario where the lift-off stabilization may be substantially different. At temperatures below 1000 K, the S-2 fuel undergoes a long transient stabilization phase during which the lift-off location moves as much as 15 mm upstream (i.e., toward the injector orifice) after the ignition of the first flame kernel. This behavior is much different than S-1, n-dodecane, or with conventional diesel, in which past research shows that the lift-off location stabilizes very close to the ignition location shortly after the premixed burn. The longer ignition delays for S-2 frequently result in fuel-lean mixtures at the ignition location where the spray becomes over-mixed (i.e., too fuel-lean) and the high-temperature ignition event is noticeably less robust (i.e., smaller and less intense ignition kernels) as observed by high-speed chemiluminescence imaging. High-speed chemiluminescence imaging and pressure measurements show strong evidence of cool-flame (i.e., first-stage or low-temperature) reactions prior to high-temperature ignition for S-1 while they are less evident for S-2.
Lequien, Guillaume, Skeen, Scott, Manin, Julien, Pickett, Lyle M, Andersson, Oivind
Cetane Number Determination by Advanced Fuel Ignition Delay Analysis in a New Constant Volume Combustion Chamber2015-01-07984/14/2015
A new constant volume combustion chamber (CVCC) apparatus is presented that calculates the cetane number (CN) of fuels from their ignition delay by means of a primary reference fuel calibration. It offers the benefits of low fuel consumption, suitability for non-lubricating substances, accurate and fast measurements and a calibration by primary reference fuels (PRF). The injection system is derived from a modern common-rail passenger car engine. The apparatus is capable of fuel injection pressures up to 1200 bar and requires only 40 ml of the test fuel. The constant volume combustion chamber can be heated up to 1000 K and pressurized up to 50 bar. Sample selection is fully automated for independent operation and low levels of operator involvement. Capillary tubes employed in the sampling system can be heated to allow the measurement of highly viscous fuels. For primary reference fuel calibration, ignition delay times of six mixtures with defined CN in the range of 35 to 70 are measured and correlated to their CN using a mathematical best fit curve. First tests showed good correlation with conventionally determined engine CN for several diesel fuels. Methanol and ethanol with a CN below 20 were measured using a special low-CN calibration and higher chamber temperature and pressure. Two oxygenates with a high CN above 100 were measured after mixing with a low-CN primary reference fuel. This blending CN method allows extrapolating the CN for samples above the calibrated measurement range.
Seidenspinner, Philipp, Härtl, Martin, Wilharm, Thomas, Wachtmeister, Georg
Ignition Quality Tester (IQT™) Precision Improvements from Using the Totally Automated Laboratory Model (TALM) Technology: Technology Update, Part-2: Mini Inter-Laboratory Study Using the IQT™-TALM2015-01-08054/14/2015
This paper presents the results of a mini Inter-Laboratory Study (mILS) that is a continuation of earlier work, published in SAE paper number 2014-01-0179 [1]. This work was aimed to improve the capability, precision, and durability of the Ignition Quality Tester (IQT™) and ASTM D6890 [2]/EN15195 [3] Test Methods. The mILS was performed to determine how much the TALM IQT™ Precision Package would improve the precision of four IQT™s, relative to a larger number of IQT™s participating in two separate Fuel Exchange Programs (FEPs). Two of the IQT™s were located at AET and the other two were located at two different external laboratories. All four IQT™s were equipped with the TALM Precision Package. Nine fuel samples from the two FEPs with reference DCN values from 33 to 82 were selected for testing. The parameters investigated were: 1) The difference between the average DCN values of the fuel samples and their reference values. 2) The difference between the average standard deviation of DCN values of the fuel samples and their reference values. 3) Effect of mILS results on D6890 method reproducibility and comparison with other Cetane standard test methods. An overall improvement of 63% in the average standard deviation of DCN values was found relative to the reference values reported in the ASTM NEG and the EI CS FEPs. When the mILS results were compared with the average standard deviation of CN reference values reported in the same FEP, the overall improvement was 73%. Over the DCN range of 33 to 70, the mILS results indicate a 53% to 71% improvement in reproducibility compared to the reproducibility published in EN 15195-14 [4]. These results provide an indication of how the addition of the TALM Precision Package to an IQT™ can markedly improve the precision of the IQT™.
Ramadan, Omar, Webster, Gary, Menard, Luc, Wilcox, Aaron, Webster, Charlie, Larocque, Jim
Numerical Study of RCCI and HCCI Combustion Processes Using Gasoline, Diesel, iso-Butanol and DTBP Cetane Improver2015-01-08504/14/2015
Reactivity Controlled Compression Ignition (RCCI) has been shown to be an attractive concept to achieve clean and high efficiency combustion. RCCI can be realized by applying two fuels with different reactivities, e.g., diesel and gasoline. This motivates the idea of using a single low reactivity fuel and direct injection (DI) of the same fuel blended with a small amount of cetane improver to achieve RCCI combustion. In the current study, numerical investigation was conducted to simulate RCCI and HCCI combustion and emissions with various fuels, including gasoline/diesel, iso-butanol/diesel and iso-butanol/iso-butanol+di-tert-butyl peroxide (DTBP) cetane improver. A reduced Primary Reference Fuel (PRF)-iso-butanol-DTBP mechanism was formulated and coupled with the KIVA computational fluid dynamic (CFD) code to predict the combustion and emissions of these fuels under different operating conditions in a heavy duty diesel engine. The results show that RCCI combustion is achievable by applying a single low reactivity fuel combined with small amount of DTBP cetane improver over wide operating conditions, and that the performance of the iso-butanol-DTBP fuel is comparable to that of gasoline-diesel and iso-butanol-diesel fuels. However, due to the low reactivity of iso-butanol, a relatively high amount of DTBP is needed to enhance the reactivity of the DI iso-butanol+DTBP mixture. The simulations were extended to also model homogeneous charge compression ignition (HCCI) combustion under similar operating conditions with the various fuels. Comparisons between HCCI and RCCI show that although comparable performance can be obtained with HCCI under low to medium load conditions, RCCI shows advantages under higher load conditions.
Wang, Hu, DelVescovo, Dan, Yao, Mingfa, Reitz, Rolf D.
Characterization of Reactivity Controlled Compression Ignition (RCCI) Using Premixed Gasoline and Direct-Injected Gasoline with a Cetane Improver on a Multi-Cylinder Engine2015-01-08554/14/2015
The focus of the present study was to characterize Reactivity Controlled Compression Ignition (RCCI) using a single-fuel approach of gasoline and gasoline mixed with a commercially available cetane improver on a multi-cylinder engine. RCCI was achieved by port-injecting a certification grade 96 research octane gasoline and direct-injecting the same gasoline mixed with various levels of a cetane improver, 2-ethylhexyl nitrate (EHN). The EHN volume percentages investigated in the direct-injected fuel were 10, 5, and 2.5%. The combustion phasing controllability and emissions of the different fueling combinations were characterized at 2300 rpm and 4.2 bar brake mean effective pressure over a variety of parametric investigations including direct injection timing, premixed gasoline percentage, and intake temperature. Comparisons were made to gasoline/diesel RCCI operation on the same engine platform at nominally the same operating condition. The experiments were conducted on a modern four cylinder light-duty diesel engine that was modified with a port-fuel injection system while maintaining the stock direct injection fuel system. The pistons were modified for highly premixed operation and feature an open shallow bowl design. The results indicate that the authority to control the combustion phasing through the fuel delivery strategy (e.g., direct injection timing or premixed gasoline percentage) is not a strong function of the EHN concentration in the direct-injected fuel. It was also observed that NOx emissions are a strong function of the global EHN concentration in-cylinder and the combustion phasing. In general, NOx emissions are significantly elevated for gasoline/gasoline+EHN operation compared with gasoline/diesel RCCI operation at a given operating condition.
Dempsey, Adam B., Curran, Scott, Reitz, Rolf D.
Performance and Emissions of Lignin and Cellulose Based Oxygenated Fuels in a Compression-Ignition Engine2015-01-09104/14/2015
Lignocellulosic biomass consists of (hemi-) cellulose and lignin. Accordingly, an integrated biorefinery will seek to valorize both streams into higher value fuels and chemicals. To this end, this study evaluated the overall combustion performance of both cellulose- and lignin derivatives, namely the high cetane number (CN) di-n-butyl ether (DnBE) and low CN anisole, respectively. Said compounds were blended both separately and together with EN590 diesel. Experiments were conducted in a single cylinder compression ignition engine, which has been optimized for improved combustion characteristics with respect to low emission levels and at the same time high fuel efficiency. The selected operating conditions have been adopted from previous “Tailor-Made Fuels from Biomass (TMFB)” work. Although particulate matter emissions benefitted from the combination of anisole and DnBE, overall performance, including also indicated efficiency, load ignitability, as well as unburnt hydrocarbon and carbon monoxide emissions, was best for the diesel blend with the lowest anisole concentration of 10% and a CN of 45. Furthermore, the results suggested that CN has more impact than fuel oxygen content, with lower CN leading to improved overall performance. This improvement, however, appeared to have an optimum for CN's in the range of 37-45. A further reduction to 30.5 or increase to 56 generally decreased overall performance.
Zhou, Lei, Heuser, Benedikt, Boot, Michael, Kremer, Florian, Pischinger, Stefan
Investigation of the Effect of Compression Ratio on the Combustion Behavior and Emission Performance of HVO Blended Diesel Fuels in a Single-Cylinder Light-Duty Diesel Engine2015-01-08984/14/2015
Hydrotreated vegetable oil (HVO) is a renewable high quality paraffinic diesel that can be obtained by the hydrotreating of a wide range of biomass feedstocks, including vegetable oils, animal fats, waste oils, greases and algal oils. HVO can be used as a drop-in fuel with beneficial effects for the engine and the environment. The main objective of this study was to explore the potential of HVO as a candidate bio blendstock for new experimental formulations of diesel fuel to be used in advanced combustion systems at different compression ratios and at high EGR rates in order to conform to the Euro 6 NOx emission standard. The experiments were carried out in a single-cylinder research engine at three steady-state operating conditions and at three compression ratios (CR) by changing the piston. The set of fuels comprised a commercial EN590-compliant diesel fuel and four experimental fuels formulated ad hoc to investigate the effect of natural cetane provided by the HVO in comparison with artificial cetane. The fuel quality has proved to affect the specific fuel consumption, the maximum pressure gradient and the regulated emissions at all the tested CR. The use of high-cetane number HVO blends reduced the HC and CO emissions derived from incomplete combustion at all operating conditions, while the effect on PM emissions was dependent on the combustion mode, whether conventional diesel combustion or premixed charge combustion ignition (PCCI). The comparison of results obtained with the HVO blends and the base fuel treated with the cetane improver suggests that the cetane number was the single most influent factor on engine performance.
Pellegrini, Leonardo, Beatrice, Carlo, Di Blasio, Gabriele
A Study of Supercharged HCCI Combustion Using Blended Fuels of Propane and DME2014-32-000511/11/2014
Homogeneous Charge Compression Ignition (HCCI) has attracted a great deal of interest as a combustion system for internal combustion engines because it achieves high efficiency and clean exhaust emissions. However, HCCI combustion has several issues that remain to be solved. For example, it is difficult to control engine operation because there is no physical means of inducing ignition. Another issue is the rapid rate of heat release because ignition of the mixture occurs simultaneously at multiple places in the cylinder. The results of previous investigations have shown that the use of a blended fuel of DME and propane was observed that the overall combustion process was delayed, with that combustion became steep when injected propane much. This study focused on expanding the region of stable engine operation and improving thermal efficiency by using supercharging and blended fuels. The purpose of using supercharging were in order to moderated combustion. In addition, the purpose of using blended gaseous fuels were find out effective use of gaseous fuels. Low-carbon gaseous fuels with clean emissions were used as the test fuels. The specific fuels used were dimethyl ether (DME, cetane number of 55 or higher) that exhibits pronounced low-temperature oxidation reactions. Propane (cetane number of 5) that does not exhibits low-temperature reaction readily and that is a principal component of liquefied petroleum gas. A spectroscopic measurement technique was used to investigate the combustion in detail by obtain the light emission spectra of the combustion flame. The characteristics of the reaction products were investigated by analyzing the exhaust gas components using Fourier transform infrared spectroscopy. The results shows that the quantity of DME and propane ratio injected determines the ignition timing, the engine load level can be adjusted by means of the quantity of propane injected to achieve ignition near top dead center. In addition, combustion became moderate by supercharging.
Mochizuki, Keisuke, Shima, Takahiro, Suzuki, Hirotaka, Ishikawa, Yoshihiro, Iijima, Akira, Yoshida, Koji, Shoji, Hideo
Diesel Combustion Characteristics of Palm Oil Methyl Ester with 1-Butanol2014-32-008511/11/2014
In order to reduce the smoke emission of PME/1-butanol blend by increasing the 1-butanol content, PME/1-butanol blend is tested using a DI diesel engine with jerk-type fuel injection pump. With PME/1-butanol blend, there is no problem on the start-ability and stability of the engine operation up to 60 mass% of 1-butanol. On the other hand, with gas oil/1-butanol blend, there is no problem on those up to 40 mass% of 1-butanol. The PME/1-butanol blend has longer ignition delay compared with PME due to the low cetane number of 1-butanol. With increasing 1-butanol content, the smoke emissions of PME/1-butanol blend decrease although the HC and CO emissions increase due to the longer ignition delay. From the experimental results, it is concluded that when considering the ignitability, the brake thermal efficiency and the exhaust emissions, the available maximum 1-butanol mixing ratio for PME/1-butanol blend is 50 mass%, which is 10 % higher than that for the gas oil/1-butanol blend, 40 mass%. Furthermore, to improve the ignitability of PME/1-butanol blend, by adding 1 mass% 2EHN to PME/1-butanol blend, the HC and CO emissions decrease due to the ignitability improvement and the available 1-butanol mixing ratio increases up to 60 mass% expect for low load condition.
Otaka, Takeshi, Fushimi, Kazuyo, Kinoshita, Eiji, Yoshimoto, Yasufumi
Exhaust Gas Emissions from Heavy-Duty Engines and Passenger Cars with Different After-Treatment Systems Running on Hydrotreated Vegetable Oil (HVO)2014-01-282710/13/2014
One political and economic aim in Europe is to increase the use of renewable energy resources. In the transport sector, up to 10 % of fossil diesel fuel should be replaced by biogenic fuels by 2020. This also means a reduction in crude oil dependency. In the area of diesel fuel, fatty acid methyl esters are introduced since over 20 years as biodiesel. However, biodiesel can lead to an increase of engine oil dilution in passenger cars with diesel particulate filters. During the regeneration of the particulate filters, there is an entry of fuel components in the engine oil. While most of the diesel fuel (DF) evaporates from the engine oil, biodiesel remains in the oil and can cause sludge formation in the engine. A promising approach to reduce this problem is the use of a new type of biogenic fuel, called hydrotreated vegetable oil (HVO). This is also produced from vegetable oil or animal fat. Like biodiesel, HVO is free of sulfur and any aromatics. HVO has a higher cetane number in comparison with biodiesel and most diesel fuels. The impact on regulated and non-regulated emissions of HVO was tested using two heavy-duty engines as well as on a fleet of eleven passenger cars of the emission standards Euro 3 to Euro 6. The cars and engines were equipped with different exhaust gas after-treatment systems. As reference for the biogenic fuels CRC reference diesel fuels were used. In the heavy-duty engine tests, less emissions of regulated components were found for HVO compared to reference diesel fuel. But for passenger cars, that positive emission trend could not be verified because an increase of nitrogen oxides emission in the range of 5 % to 14 % was recorded. Also, the exhaust gases of HVO showed less mutagenic effects than diesel fuel tested by salmonellae cultures.
Götz, Kristin, Singer, Anja, Schröder, Olaf, Pabst, Christoph, Munack, Axel, Bünger, Jürgen, Krahl, Jürgen
Effects of Oxygenated Fuels on Combustion and Soot Formation/Oxidation Processes2014-01-265710/13/2014
The Leaner Lifted-Flame Combustion (LLFC) strategy offers a possible alternative to low temperature combustion or other globally lean, premixed operation strategies to reduce soot directly in the flame, while maintaining mixing-controlled combustion. Adjustments to fuel properties, especially fuel oxygenation, have been reported to have potentially beneficial effects for LLFC applications. Six fuels were selected or blended based on cetane number, oxygen content, molecular structure, and the presence of an aromatic hydrocarbon. The experiments compared different fuel blends made of n-hexadecane, n-dodecane, methyl decanoate, tri-propylene glycol monomethyl ether (TPGME), as well as m-xylene. Several optical diagnostics have been used simultaneously to monitor the ignition, combustion and soot formation/oxidation processes from spray flames in a constant-volume combustion vessel. Ignition delay times, lift-off lengths and soot KL extinction levels for the six fuels have been measured at in-cylinder conditions relevant to modern diesel engines. The results show that blending an alkane with an oxygenated fuel of similar cetane number has no noticeable impact on ignition delay while only slightly affecting lift-off length, with longer flame stabilization distance for blends with higher oxygen content. Longer ignition delays and lift-off lengths were observed when m-xylene was added to an oxygenated blend. Methyl decanoate showed both longer ignition delays and longer lift-off lengths than the other fuels, consistent with its lower cetane number. These experiments show that there is no direct linear relationship between ignition and flame stabilization when burning fuels with different chemical compositions. Blends using TPGME as oxygenated component achieved lower soot levels compared to methyl decanoate, with the best performance as soot is concerned being achieved with a 50/50 blend of TPGME and n-hexadecane. Aromatic hydrocarbons (here m-xylene), rather than paraffinic hydrocarbons, blended with an oxygenated fuel can negate the benefit of oxygenation with regard to a reduction in soot levels, despite producing longer lift-off lengths.
Manin, Julien, Skeen, Scott, Pickett, Lyle, Kurtz, Eric, Anderson, James E.
Items per page:
1 – 50 of 320