Download or read book The Effects of Engine Operational Parameters on the Auto ignition Chemistry of N Decane in a Compression Ignition Engine Environment written by Yulei Li and published by . This book was released on 2018 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: JP-8 is a jet fuel widely used by the U.S. military. The military has called for JP-8 to be used in all internal combustion applications, including compression ignition engines. To understand the combustion of JP-8 in these engines, an accepted procedure is to develop combustion models of simple mixtures of hydrocarbons, called surrogates, and their components. As part of a program to develop such models, the auto-ignition behavior of n-decane in a motored engine has been investigated. In-cylinder pressure was measured to indicate the overall reactivity behavior and quantify the effects of engine operational parameters on the auto-ignition of n-decane. Additionally, exhaust gas composition was analyzed by GC/MS to identify and measure stable intermediate species to deduce the key reaction pathways leading to auto-ignition. Furthermore, a new method that uses only pressure data was proposed and developed to identify the start of combustion. By applying this method, the in-cylinder conditions for pre-ignition point were used to predict the ignition of n-decane. Based on the in-cylinder conditions of pre-ignition point, a general pre-ignition limit line for n-decane was generated, taking dilution of residual gas, equivalence ratio, and compression ratio into account. This pre-ignition limit line will be useful for predicting the pre-ignition initiation during the oxidation of n-decane. Furthermore, it is a proof of the concept "pre-ignition limit line", which may be useful when generalized for all hydrocarbons. The measured species profiles from this study may be used in future work to develop detailed and reduced kinetic models for the auto-ignition and oxidation of JP-8 surrogate fuels.

Download or read book Experimental Investigation of Gasoline Compression Ignition Combustion in a Light Duty Diesel Engine written by and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to increased ignition delay and volatility, low temperature combustion (LTC) research utilizing gasoline fuel has experienced recent interest [1-3]. These characteristics improve air-fuel mixing prior to ignition allowing for reduced emissions of nitrogen oxides (NOx) and soot (or particulate matter, PM). Computational fluid dynamics (CFD) results at the University of Wisconsin-Madison's Engine Research Center (Ra et al. [4, 5]) have validated these attributes and established baseline operating parameters for a gasoline compression ignition (GCI) concept in a light-duty diesel engine over a large load range (3-16 bar net IMEP). In addition to validating these computational results, subsequent experiments at the Engine Research Center utilizing a single cylinder research engine based on a GM 1.9-liter diesel engine have progressed fundamental understanding of gasoline autoignition processes, and established the capability of critical controlling input parameters to better control GCI operation. The focus of this thesis can be divided into three segments: 1) establishment of operating requirements in the low-load operating limit, including operation sensitivities with respect to inlet temperature, and the capabilities of injection strategy to minimize NOx emissions while maintaining good cycle-to-cycle combustion stability; 2) development of novel three-injection strategies to extend the high load limit; and 3) having developed fundamental understanding of gasoline autoignition kinetics, and how changes in physical processes (e.g. engine speed effects, inlet pressure variation, and air-fuel mixture processes) affects operation, develop operating strategies to maintain robust engine operation. Collectively, experimental results have demonstrated the ability of GCI strategies to operate over a large load-speed range (3 bar to 17.8 bar net IMEP and 1300-2500 RPM, respectively) with low emissions (NOx and PM less than 1 g/kg-FI and 0.2 g/kg-FI, respectively), and low fuel consumption (gross indicated fuel consumption

Download or read book Autoignition and Emission Characteristics of Gaseous Fuel Direct injection Compression ignition Combustion written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Heavy-duty natural gas engines offer air pollution and energy diversity benefits. However, current homogeneous-charge lean-burn engines suffer from impaired efficiency and high unburned fuel emissions. Natural gas direct-injection engines offer the potential of diesel-like efficiencies, but require further research. To improve understanding of the autoignition and emission characteristics of natural gas direct-injection compression-ignition combustion, the effects of key operating parameters (including injection pressure, injection duration, and pre-combustion temperature) and gaseous fuel composition(including the effects of ethane, hydrogen and nitrogen addition) were studied. An experimental investigation was carried out on a shock tube facility. Ignition delay, ignition kernel location, and NOx emissions were measured. The results indicated that the addition of ethane to the fuel resulted in a decrease in ignition delay and a significant increase in NOx emissions. The addition of hydrogen to the fuel resulted in a decrease in ignition delay and a significant decrease in NOx emissions. Diluting the fuel with nitrogen resulted in an increase in ignition delay and a significant decrease in NOx emissions. Increasing pre-combustion temperature resulted in a significant reduction in ignition delay, and a significant increase in NOx emissions. Modest increase in injection pressure reduced the ignition delay; increasing injection pressure resulted in higher NOx emissions. The effects of ethane, hydrogen, and nitrogen addition on the ignition delay of methane were also successfully predicted by FlameMaster simulation. OH radical distribution in the flame was visualized utilizing Planar Laser Induced Fluorescence (PLIF). Single-shot OH-PLIF images revealed the stochastic nature of the autoignition process of non-premixed methane jets. Examination of the convergence of the ensemble-averaged OH-PLIF images showed that increasing the number of repeat experiments was the most.

Download or read book The Effect of Operating Variables on Compression Temperature in a Compression Ignition Engine written by Keh C. Tsao and published by . This book was released on 1961 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Investigation of Homogeneous Charge Compression Ignition Operating Range and Engine Performance with Different Fuels written by Tanet Aroonsrisopon and published by . This book was released on 2002 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Multiple Introduction of Fuel in Compression ignition Engines written by Chandra Prakash Gupta and published by . This book was released on 1964 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Chemical Kinetic Modelling of Autoignition Under Conditions Relevant to Knock in Spark Ignition Engines written by Hakan Serhad Soyhan and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The phenomenon called the ''engine knock'' is an abnonnal combustion mode inspark ignition (SI) engines. it might lead to very high peak pressure in the cylinderand serious damages in engines. Knock limits the compression ratio of the ~ngine. The higher compression ratiomeans the higher fuel conversion efficiency of the engine. it also means highercylinder pressure and thereby higher gas temperature which can cause knock becauseof shorter ignition delay time. Increasing compression ratio is the simplest strategyfor increasing the efficiency of combustion, so a more detailed understanding of theprocesses goveming knock is important.it is generally accepted that knock is initiated by autoignition in the unbumed gasmixture as a result of compression due to the f1ame front propagation and the piston movement. Auto ignition can be defined as spontaneous ignition of some part of thecharge in the cylinder. The autoignition is may cause an extremely rapid chemicalenergy release. it causes a high local pressure and propagation of pressure waveswith high amplitude across the combustion chamber. The rapid rise in pressure andthe vibration of the resultant pressure wave across the combustion chamber cause erosion of the piston, piston rings and head gaskets. Known measures to avoid theoccurrence of engine knock cause either environmental problems, for example theusage of MTBE or reduce the engine thennal efficiency , for example lowcompression ratio, high swirl or early ignition timing. Because of this, the occurrenceof knock was subject of continuous public and industrial research.A detailed investigation of the combustion processes in intemal combustion engines is necessary for the improvement of engine technology .Chemical kinetic model ofthe combustion process implemented into the computational f1uid dynamic sapplications for the prediction of gas f1ow in the combustion chamber provides anefficient tool in tenns of time and cost for the investigation and improvement of the combustion process.The software tools for the modeling of combustion processes in combustion devicesrequire the reduction of the kinetic model to a limited number of species. Since the engine geometry is very complex, the performnnance of commercial software productsfor combustion device optimization decreases considerably if the number of species exceeds about 10. Consequently, a variety of methods in chemical kinetic modelingare needed to construct a reaction mechanism for a complex fuel such as PRF and toreduce it to a low number of capable species without a loss of information that mightbe important for the accuracy of the calculations. One method having the following steps is The generation of a ''detailed reaction mechanism'',The construction of the ''skeletal mechanism'',The final reduction of the reaction mechanism using Quasi Steady State Approximations (QSSA).This study concentrates on the construction of the problem oriented reduced mechanism. A method for automatic reduction of detailed kinetic to reduced mechanisms for complex fuels is proposed. The method is based on the simultaneoususe of sensitivity, reaction-f1ow and lifetime analyses. The sensitivity analysis detects species that the overall combustion process is sensitive on. Small in accuracies, in calculating these species, result in large errors in the characteristic behavior of the chernical scheme. Species, not relevant for the occurrence of autoignition in the end-gas, are defined as redundant. The automatic detection of there dundant species is done by means of an analysis of the reaction f1ows from and towards the most sensitive species, the fuel, the oxidizer and the final products. Theyare identified and eliminated for different pre-set levels of minimum reaction flow and sensitivity to generate a skeletal mechanism. The resulting skeletal mechanism is investigated with lifetime analysis to get the final reduced mechanism. A measure ofspecies lifetimes is taken from the diagonal elements of the Jacobian matrix of the chernical source terms. The species with the lifetime shorter than and mass-fractionIess than specified limits are assumed to be in steady state and selected for removalfrom the skeletal mechanism. The reduced mechanism is valid for the parameter range of initial and boundary values that the analysis has been performed for.The proposed reduction method is exemplified on a detailed reaction mechanism foriso-octane/n-heptane rnixtures. The gas-phase chernistry is analyzed in the end gas of an SI engine, using a two-zone model with conditions chosen relevant for engine knock. Comparing results obtained from the skeletal and the reduced mechanism swith results from the detailed mechanism shows the accuracy of the resulting mechanisms. it is shown that the error in the mechanisms increase with increasingpre-set Ievels of reduction. This is visualized by the help of the predicted crank angle degree at which auto ignition in the end gas of the engine occurs.The reduced mechanism is used for investigation of the modeling of the auto ignitionin the SI engines. The effects of engine operator parameters such as compression ratio, spark advance, fuel equivalence ratio and engine speed on autoignition onsettime have been studied.This work shows that it is possible to achieve a simplified reaction mechanism withgood agreement to the original mechanism by the reduction method. Fundamental knowledge about the detailed mechanism is not necessary to apply the method. Theprocedure used for reduction is fully automatic and provides a fast technique togenerate the problem oriented reduced mechanisms.

Download or read book Advances in Compression Ignition Natural Gas Diesel Dual Fuel Engines written by Hongsheng Guo and published by Frontiers Media SA. This book was released on 2021-03-23 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundamental Interactions in Gasoline Compression Ignition Engines with Fuel Stratification written by Benjamin Matthew Wolk and published by . This book was released on 2014 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transportation accounted for 28% of the total U.S. energy demand in 2011, with 93% of U.S. transportation energy coming from petroleum. The large impact of the transportation sector on global climate change necessitates more-efficient, cleaner-burning internal combustion engine operating strategies. One such strategy that has received substantial research attention in the last decade is Homogeneous Charge Compression Ignition (HCCI). Although the efficiency and emissions benefits of HCCI are well established, practical limits on the operating range of HCCI engines have inhibited their application in consumer vehicles. One such limit is at high load, where the pressure rise rate in the combustion chamber becomes excessively large. Fuel stratification is a potential strategy for reducing the maximum pressure rise rate in HCCI engines. The aim is to introduce reactivity gradients through fuel stratification to promote sequential auto-ignition rather than a bulk-ignition, as in the homogeneous case. A gasoline-fueled compression ignition engine with fuel stratification is termed a Gasoline Compression Ignition (GCI) engine. Although a reasonable amount of experimental research has been performed for fuel stratification in GCI engines, a clear understanding of how the fundamental in-cylinder processes of fuel spray evaporation, mixing, and heat release contribute to the observed phenomena is lacking. Of particular interest is gasoline's pressure sensitive low-temperature chemistry and how it impacts the sequential auto-ignition of the stratified charge. In order to computationally study GCI with fuel stratification using three-dimensional computational fluid dynamics (CFD) and chemical kinetics, two reduced mechanisms have been developed. The reduced mechanisms were developed from a large, detailed mechanism with about 1400 species for a 4-component gasoline surrogate. The two versions of the reduced mechanism developed in this work are: (1) a 96-species version and (2) a 98-species version including nitric oxide formation reactions. Development of reduced mechanisms is necessary because the detailed mechanism is computationally prohibitive in three-dimensional CFD and chemical kinetics simulations. Simulations of Partial Fuel Stratification (PFS), a GCI strategy, have been performed using CONVERGE with the 96-species reduced mechanism developed in this work for a 4-component gasoline surrogate. Comparison is made to experimental data from the Sandia HCCI/GCI engine at a compression ratio 14:1 at intake pressures of 1 bar and 2 bar. Analysis of the heat release and temperature in the different equivalence ratio regions reveals that sequential auto-ignition of the stratified charge occurs in order of increasing equivalence ratio for 1 bar intake pressure and in order of decreasing equivalence ratio for 2 bar intake pressure. Increased low- and intermediate-temperature heat release with increasing equivalence ratio at 2 bar intake pressure compensates for decreased temperatures in higher-equivalence ratio regions due to evaporative cooling from the liquid fuel spray and decreased compression heating from lower values of the ratio of specific heats. The presence of low- and intermediate-temperature heat release at 2 bar intake pressure alters the temperature distribution of the mixture stratification before hot-ignition, promoting the desired sequential auto-ignition. At 1 bar intake pressure, the sequential auto-ignition occurs in the reverse order compared to 2 bar intake pressure and too fast for useful reduction of the maximum pressure rise rate compared to HCCI. Additionally, the premixed portion of the charge auto-ignites before the highest-equivalence ratio regions. Conversely, at 2 bar intake pressure, the premixed portion of the charge auto-ignites last, after the higher-equivalence ratio regions. More importantly, the sequential auto-ignition occurs over a longer time period for 2 bar intake pressure than at 1 bar intake pressure such that a sizable reduction in the maximum pressure rise rate compared to HCCI can be achieved.

Download or read book Fuel Property Effects on Engine Combustion Processes Final Report written by and published by . This book was released on 1995 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: A major obstacle to improving spark ignition engine efficiency is the limitations on compression ratio imposed by tendency of hydrocarbon fuels to knock (autoignite). A research program investigated the knock problem in spark ignition engines. Objective was to understand low and intermediate temperature chemistry of combustion processes relevant to autoignition and knock and to determine fuel property effects. Experiments were conducted in an optically and physically accessible research engine, static reactor, and an atmospheric pressure flow reactor (APFR). Chemical kinetic models were developed for prediction of species evolution and autoignition behavior. The work provided insight into low and intermediate temperature chemistry prior to autoignition of n-butane, iso-butane, n-pentane, 1-pentene, n-heptane, iso-octane and some binary blends. Study of effects of ethers (MTBE, ETBE, TAME and DIPE) and alcohols (methanol and ethanol) on the oxidation and autoignition of primary reference fuel (PRF) blends.

Download or read book Isolation of Fuel Property and Boundary Condition Effects on Low Load Gasoline Compression Ignition GCI written by John Andrew Roberts and published by . This book was released on 2018 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gasoline compression ignition (GCI) combustion is a promising solution to address increasingly stringent efficiency and emissions regulations imposed on the internal combustion engine. However, the high resistance to auto-ignition of modern market gasoline makes low load compression ignition operation difficult. The most comprehensive work focused on low load GCI operation has been performed on multi-cylinder research engines where it is difficult to decouple effects of the combustion event from air-handling and system level parameters (e.g., intake pressurization and exhaust gas recirculation (EGR)). Further, most research has focused on technology applications (e.g., use of variable valve actuation or supercharging) rather than fundamental effects, making identification of influential factors difficult. Accordingly, there is a need for detailed investigations focused on isolating the critical parameters that can be used to enable low load GCI operation. A full factorial parametric study was completed to isolate the effects of intake temperature, EGR rate, and fuel reactivity on low load performance. A minimum intake pressure metric was used to compare these parameters. This allowed combustion phasing and load to be held constant while isolating the experiment from fuel injection effects. The effort showed that increasing intake temperature yields a linear reduction in the minimum intake pressure required for stable operation. Adding a small amount of diesel fuel to gasoline improved combustion stability with minimal need for energy addition through intake pressurization. The minimum intake pressure requirement also showed very good correlation with the measured research octane number of the fuel. However, increasing the fuel reactivity with diesel fuel, caused NOx emissions to increase. Response model analysis was used to determine the intake conditions required to maintain NOx levels that may not require lean NOx after treatment. The combination of diesel fuel blending and EGR allowed NOx levels to be reduced to near zero values with the minimum intake pressurization required. A detailed investigation into the effects of EGR showed that, for a given fuel, there is a maximum EGR rate that allows for stable operation, which effectively constrains the minimum NOx prior to aftertreatment. Accordingly, a method that enables the variation of the fuel reactivity on demand is an ideal solution to address low load stability issues. Metal engine experiments conducted on a single cylinder medium-duty research engine allowed for the investigation of this strategy. The fuels used for this study were 87 octane gasoline (primary fuel stream) and diesel fuel (reactivity enhancer). Initial tests demonstrated load extension down to idle conditions with only 20% diesel by mass, which reduced to 0% at loads above 3 bar indicated mean effective pressure (IMEPg). Engine performance over a mode weighted drive cycle was completed based on work by the Ad-Hoc fuels committee [1] to demonstrate the performance of various levels of fuel blending for five primary modes of operation encompassing low load to high load. Lastly, several simulated transient drive cycle were analyzed to investigate the consumption rate of the reactivity enhancer. A response model was fit to the experimental data and exercised over the load based drive cycle. Results showed that the diesel consumption could be reduced to additive levels over a 10k mile oil change interval, lower than typical diesel exhaust fluid (DEF) consumption levels, which presents a pathway to a full-time GCI engine. Experimental efforts used a minimum intake pressure metric to evaluate the auto-ignition quality of seven fuels, including two pump fuels and five FACE gasolines in a GCI engine. The results showed that research octane number (RON) trends well with the intake pressure required to achieve a desired ignition delay at low-temperature conditions, which are representative of a boosted GCI engine. At higher temperature intake conditions poor correlation is observed between RON and intake pressure requirement. Effects of octane sensitivity were dominated by the general reactivity of fuel as characterized by RON. The Octane Index and K-factors were regressed for each operating condition, and good correlation was seen between the Octane Index and the intake pressure requirement. Main effects analysis of the impact of general properties of the fuel (RON, motor octane number (MON), and sensitivity (S)) on the intake pressure requirement showed that RON was the only statistically significant parameter. Analysis of the main effects of fuel composition on intake pressure requirement showed some trends, but none were statistically significant. This indicates that the auto-ignition quality of the fuel is not characterized by variations in any single species. Analysis of the stable start-of-injection (SOI) timing injection window showed that both RON and sensitivity describe stability at low temperatures. In general, a fuel with a higher RON will have a smaller stable SOI window than a lower RON fuel. Additionally, fuels with the same RON and different sensitivities will behave differently. Analysis showed that, for a given RON, a low sensitivity fuel would tend to have a wider operating window than a high sensitivity fuel. Analysis of the heat release for the experimental cases showed that this is due to the presence of low-temperature chemistry. Fuels that suppress low-temperature chemistry did not show low-temperature heat release (LTHR) and had a narrower stability window. At high temperatures, LTHR was suppressed for all fuels, as the temperature in the jet exceeded the ceiling temperature for low-temperature oxidation.

Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2540 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Perspective on the Range of Gasoline Compression Ignition Combustion Strategies for High Engine Efficiency and Low NOx and Soot Emissions written by and published by . This book was released on 2016 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many research studies have shown that low temperature combustion in compression ignition engines has the ability to yield ultra-low NOx and soot emissions while maintaining high thermal efficiency. To achieve low temperature combustion, sufficient mixing time between the fuel and air in a globally dilute environment is required, thereby avoiding fuel-rich regions and reducing peak combustion temperatures, which significantly reduces soot and NOx formation, respectively. It has been demonstrated that achieving low temperature combustion with diesel fuel over a wide range of conditions is difficult because of its properties, namely, low volatility and high chemical reactivity. On the contrary, gasoline has a high volatility and low chemical reactivity, meaning it is easier to achieve the amount of premixing time required prior to autoignition to achieve low temperature combustion. In order to achieve low temperature combustion while meeting other constraints, such as low pressure rise rates and maintaining control over the timing of combustion, in-cylinder fuel stratification has been widely investigated for gasoline low temperature combustion engines. The level of fuel stratification is, in reality, a continuum ranging from fully premixed (i.e. homogeneous charge of fuel and air) to heavily stratified, heterogeneous operation, such as diesel combustion. However, to illustrate the impact of fuel stratification on gasoline compression ignition, the authors have identified three representative operating strategies: partial, moderate, and heavy fuel stratification. Thus, this article provides an overview and perspective of the current research efforts to develop engine operating strategies for achieving gasoline low temperature combustion in a compression ignition engine via fuel stratification. In this paper, computational fluid dynamics modeling of the in-cylinder processes during the closed valve portion of the cycle was used to illustrate the opportunities and challenges associated with the various fuel stratification levels.

Download or read book Fuel Effects in Homogeneous Charge Compression Ignition HCCI Engines written by John Phillip Angelos and published by . This book was released on 2009 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: (cont.) Developing an understanding of what causes an HCCI engine to misfire allows for estimation of how fuel chemistry and engine operating conditions affect the LLL. The underlying physics of a misfire were studied with an HCCI simulation tool (MITES), which used detailed chemical kinetics to model the combustion process. MITES was used to establish the minimum ignition temperature (Tmisfire) and full-cycle, steady-state temperature (Tss) for a fuel as a function of residual fraction. Comparison of Tmisfire and Tss near the misfire limit showed that Tss approaches Tmisfire quite closely (to within ~ 14 K), suggesting that the primary cause of a misfire is insufficient thermal energy needed to sustain combustion for multiple cycles. With this relationship, the effects of engine speed and fuel chemistry on the LLL were examined. Reducing the engine speed caused a reduction in T, which allowed fuel chemistry effects to be more apparent. This effect was also observed experimentally with 2 primary reference fuels (PRFs): PRF60 and PRF90. At 1000 RPM, PRF60 obtained a substantially lower (~30%) LLL than PRF90, but at speeds >/= 1500 RPM, fuel ignitability had no effect on the LLL. Fuel chemistry was shown to influence the LLL by increasing both Tmisfire and Tss for more auto-ignition resistant fuels. However, the extent to which fuel chemistry affects these temperatures may not be equivalent. Therefore, the relative movement of each temperature determines the extent to which fuel chemistry impacts the LLL.

Download or read book Effects of Increased Intake Pressure on Homogeneous Charge Compression Ignition HCCI of Gasoline and Ethanol in a Four cylinder Engine written by Robert Vern Mills and published by . This book was released on 2007 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Fuel impingement surface Temperature on Noise Smoke and Power of a Compression ignition Engine written by Lawrence Richard Daniel and published by . This book was released on 1958 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Turbulence chemistry Interactions in Direct injection Compression ignition Engines written by Hedan Zhang and published by . This book was released on 2012 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: