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Viewing 1 to 30 of 331
2017-09-04
Technical Paper
2017-24-0070
Stefano D'Ambrosio, Daniele Iemmolo, Alessandro Mancarella, Nicolò Salamone, Roberto Vitolo, Gilles Hardy
A precise estimation of the recirculated exhaust gas rate and oxygen concentration as well as a predictive evaluation of the possible EGR unbalance among cylinders are of paramount importance, especially if non-conventional combustion modes, which require high EGR flowrates, are implemented. In the present paper, starting from the equation related to convergent nozzles, the EGR mass flow-rate is modeled considering the pressure and the temperature upstream of the EGR control valve, as well as the pressure downstream of it. The restricted flow-area at the valve-seat passage and the discharge coefficient are carefully assessed as functions of the valve lift. Other models were fitted using parameters describing the engine working conditions as inputs, following a semi-physical and a purely statistical approach. The resulting models are then applied to estimate EGR rates to both conventional and non-conventional combustion conditions.
2017-09-04
Technical Paper
2017-24-0136
Kurtis James Irwin, Roy Douglas, Jonathan Stewart, Andrew Pedlow, Rose Mary Stalker, Andrew Woods
With emission legislations becoming ever more stringent there is an increased pressure on the after treatment systems and more specifically the three-way catalysts. With more recent developments in emission legislations, there is requirement for more complex after-treatment systems and understanding of the ageing process. With future legislation introducing independent inspection of emissions at any time under real world driving conditions throughout a vehicle life cycle this is going to increase the focus on understanding catalyst behaviour during any likely conditions throughout its lifetime and not just at the beginning and end. In recent years it has become a popular approach to use accelerated aging of the automotive catalysts for the development of new catalytic formulations and for homologation of new vehicle emissions.
2017-03-28
Journal Article
2017-01-1688
Hassene Jammoussi, Imad Makki
The usage of the universal exhaust gas oxygen (UEGO) sensor to control the air-fuel ratio (AFR) in gasoline engines allowed to significantly improve the efficiency of the combustion process and reduce tailpipe emissions. The diagnostics of this sensor is very important to ensure proper operation and indicate the need for service when the sensor fails to accurately determine the AFR upstream of the catalyst. California air resources board (CARB) has imposed several legislations around the operation of the UEGO sensor and particularly when specific faults would cause tailpipe emissions to exceed certain limits. In this paper, the possible sensor faults are reviewed, and a non-intrusive diagnostics monitor is proposed to detect, identify and estimate the magnitude of the fault present. This paper extends the approach in [4] where technical details are emphasized and algorithm improvements are discussed.
2017-03-28
Technical Paper
2017-01-0949
Makoto Ito, Mitsuru Sakimoto, Zhenzhou Su, Go Hayashita, Keiichiro Aoki
Abstract New 2A/F systems different from usual A/F-O2 systems are being developed to cope with strict regulation of exhaust gas. In the 2A/F systems, 2A/F sensors are equipped in front and rear of a three-way catalyst. The A/F-O2 systems are ideas which use a rear O2 to detect exhaust gas leaked from three-way catalyst early and feed back. On the other hand, the 2A/F systems are ideas which use a rear A/F sensor to detect nearly stoichiometric gas discharged from the three-way catalyst accurately, and to prevent leakage of exhaust gas from the three-way catalyst. Therefore, accurate detection of nearly stoichiometric gas by the rear A/F sensor is the most importrant for the 2A/F systems. In general, the A/F sensors can be classified into two types, so called, one-cell type and two-cell type. Because the one-cell type A/F sensors don’t have hysteresis, they have potential for higher accuracy.
2017-03-28
Technical Paper
2017-01-0960
Pankaj Kumar, Imad Makki
Abstract Traditionally, a three-way catalyst (TWC) is controlled to a set heated exhaust gas oxygen (HEGO) sensor voltage (typically placed after the monitored catalyst) that corresponds to optimal catalyst efficiency. This limits the control action, as we rely on emissions breakthrough at the HEGO sensor to infer the state of catalyst. In order to robustly meet the super ultra-low emission regulations, a more precise TWC control around the oxidation level of catalyst is desirable. In this work, we developed a comprehensive set of models to predict the oxygen storage capacity using measured in-vehicle signals only. This is accomplished by developing three models; the first model is a linear in parameter regression model to predict the feed gas emissions from measured signals like engine speed and air-to-fuel ratio (A/F). The second model is a low-dimensional physics based model of the three-way catalyst to predict the exhaust emissions and oxidation state of the catalyst.
2016-10-17
Technical Paper
2016-01-2227
Nik Muhammad Hafiz, Mohd Radzi Abu Mansor, Wan Mohd Faizal Wan Mahmood, Masahiro Shioji
Abstract Hydrogen fuel is a potential energy source for vehicles in the future. The emission of this fuel complies with the stringent policies issued by the International Energy Agency (IEA). Researchers have nominated the hydrogen compression ignition engine in an argon atmosphere as one of the ways to enhance power output and volumetric efficiency in the midst of pre-ignition and knock problems. Since this type of research is still in the initial stage, numerical studies have become the best method for researchers to obtain data on hydrogen fuel combustion in an argon-oxygen atmosphere. The purpose of this study was to validate the simulation results with the experimental data, investigate the combustion characteristics of hydrogen fuel in an argon-oxygen atmosphere, and to study the effects of the initial temperature and injection pressure on the combustion process. In this research, CONVERGE CFD software was used for the simulation process.
2016-09-27
Technical Paper
2016-01-8082
Kaushik Saha, Ahmed Abdul Moiz, Anita Ramirez, Sibendu Som, Munidhar Biruduganti, Michael Bima, Patrick Powell
Abstract The medium and heavy duty vehicle industry has fostered an increase in emissions research with the aim of reducing NOx while maintaining power output and thermal efficiency. This research describes a proof-of-concept numerical study conducted on a Caterpillar single-cylinder research engine. The target of the study is to reduce NOx by taking a unique approach to combustion air handling and utilizing enriched nitrogen and oxygen gas streams provided by Air Separation Membranes. A large set of test cases were initially carried out for closed-cycle situations to determine an appropriate set of operating conditions that are conducive for NOx reduction and gas diffusion properties. Several parameters - experimental and numerical, were considered. Experimental aspects, such as engine RPM, fuel injection pressure, start of injection, spray inclusion angle, and valve timings were considered for the parametric study.
2016-04-05
Technical Paper
2016-01-0612
Rohit Koli, Konstantinos Siokos, Robert Prucka, Shyam Jade, Jason Schwanke
Abstract Low-pressure cooled EGR (LP-cEGR) systems can provide significant improvements in spark-ignition engine efficiency and knock resistance. However, open-loop control of these systems is challenging due to low pressure differentials and the presence of pulsating flow at the EGR valve. This research describes a control structure for Low-pressure cooled EGR systems using closed loop feedback control along with internal model control. A Smith Predictor based PID controller is utilized in combination with an intake oxygen sensor for feedback control of EGR fraction. Gas transport delays are considered as dead-time delays and a Smith Predictor is one of the conventional methods to address stability concerns of such systems. However, this approach requires a plant model of the air-path from the EGR valve to the sensor.
2016-04-05
Technical Paper
2016-01-1070
Gopichandra Surnilla, Richard Soltis, James Hilditch, Christopher House, Timothy Clark, Matthew Gerhart
Abstract Traditional EGR measurement systems using delta pressure over a fixed orifice such as a DPFE sensor (Delta Pressure Feedback for EGR), have limitations in the ability to measure EGR accurately. Also, the pressure drop that results from the orifice may not be acceptable in some applications. To measure the EGR accurately and without any pressure loss, a new measurement system was developed that uses an oxygen sensor in the intake air. In this paper, the technology of using an oxygen sensor to measure the EGR concentration is discussed. The paper details the EGR measurement principle with an oxygen sensor and the associated mathematical relations of translating the oxygen measurement to EGR measurement. Factors affecting the EGR measurement such as the air/fuel ratio of the EGR, intake air pressure, and diffusion effects of the EGR constituents are discussed in detail. Compensation mechanisms are explained and associated results shown.
2016-04-05
Technical Paper
2016-01-0971
Stefano Sabatini, Irfan Kil, Travis Hamilton, Jeff Wuttke, Luis Del Rio, Michael Smith, Zoran Filipi, Mark A. Hoffman, Simona Onori
Abstract The Three Way Catalyst (TWC) is an effective pollutant conversion system widely used in current production vehicles to satisfy emissions regulations. A TWC’s conversion efficiency degrades over time due to chemical and/or thermal mechanisms causing the catalyst to age. This reduction in conversion efficiency must be accounted for to ensure full useful life emissions compliance. This paper presents an experimental study of the aging impact on TWC performance. Four TWCs differentiated by their age, given in terms of miles driven, were tested. It is shown that the dynamics of oxygen storage are substantially affected by aging of the TWC. A previously developed physics-based oxygen storage model [1] is subsequently used to incorporate the effect of aging on the total Oxygen Storage Capacity (OSC). Parameter identification results for the different age catalysts show that total oxygen storage capacity decreases substantially with aging and is insensitive to operating conditions.
2016-04-05
Journal Article
2016-01-1265
Senthilkumar Masimalai, Sasikumar Nandagopal
Abstract This work aims at studying the combined effect of oxygen enrichment and emulsification techniques on engine performance behavior of a compression ignition engine fuelled with WCO (waste cooking oil) as fuel. Used sunflower oil collected from a restaurant was chosen as fuel. A single cylinder, water cooled, agricultural oriented, diesel engine was used for the experiments. Initially tests were performed using neat diesel and neat WCO as fuels. Performance, emission, and combustion parameters were obtained. In the second phase of work, WCO was converted into its emulsion by emulsification process using water and ethanol and tested. In the third phase, the engine intake system was modified to admit excess oxygen along with air to test the engine with WCO and WCO emulsion as fuels under oxygen enriched environment. A comparative study was made at 100% and 40% of the maximum load (i.e. 3.7 kW power output) at the rated engine speed of 1500 rpm.
2016-04-05
Technical Paper
2016-01-0739
Senthilkumar Masimalai, Sasikumar Nandagopal, Venkatesan Kuppusamy
Abstract This paper aims at studying the effect of oxygen enriched combustion on performance, emission and combustion characteristics of a diesel engine using the blend of Pyro oil obtained from pyrolysis of cashew nut shell and conventional diesel as fuel. A single cylinder water-cooled, diesel engine was used. The intake system of the engine was modified to accommodate excess oxygen in the incoming air. A separate oxygen cylinder was used for storing pure oxygen and supplying it along with intake air. Base line data was generated using diesel as fuel. Subsequently experiments were repeated with the blend of 40% of Cashew nut shell oil and 60% diesel by volume (called CSO40D60) at different oxygen concentrations such as 21%, 22% 23%, 24% and 25%. Engine performance, emission and combustion parameters were obtained at different power outputs and analyzed.
2015-09-01
Technical Paper
2015-01-2020
Takashi Okada, Satoshi Teramoto, Nobuo Furuta
In 1991, linear O2 sensors for lean-burn control were introduced in production vehicles for the first time in the world. Since then, the linear O2 sensors have been used mainly for the precise λ control. Recently requirements for Oxygen sensors have become increasingly stringent in the trends of tighter vehicle EM control requirements and lower fuel consumption. In response to these trends, NGK SPARK PLUG CO., LTD. has developed a new generation linear O2 sensor, which has a high water toughness and requires less power consumption.
2015-04-14
Technical Paper
2015-01-0895
Senthilkumar Masimalai, Venkatesan Kuppusamy, Jaikumar Mayakrishnan
Abstract This paper aims at studying the effect of oxygen enriched combustion on performance, emission and combustion characteristics of a diesel engine using waste cooking oil (WCO) derived from palm oil as fuel. A single cylinder water-cooled, direct injection diesel engine was used. The intake system of the engine was modified to accommodate excess oxygen in the incoming air. Base data was generated using diesel as fuel. Subsequently experiments were repeated with WCO for different oxygen concentrations such as 21% (WCO+21%O2), 23% (WCO+23%O2), 24% (WCO+24%O2) and 25% (WCO+25%O2) by volume. Engine performance, emission and combustion parameters were obtained at different power outputs and analyzed. Results showed reduced brake thermal efficiency, higher smoke, hydrocarbon and carbon monoxide emissions with WCO+21%O2 as compared to diesel at all power outputs.
2015-04-14
Technical Paper
2015-01-0874
Mateos Kassa, Carrie Hall, Andrew Ickes, Thomas Wallner
Abstract Recent developments in advanced combustion engines have demonstrated the potential increases in efficiency and reductions in emissions through low temperature combustion (LTC). These combustion modes often rely on high exhaust gas recirculation (EGR), early fuel injection systems, and in some cases a combination of fuels with different reactivities. Despite the advantages of LTC, such operations are highly sensitive to the in-cylinder pre-combustion conditions and face significant challenges in multi-cylinder operation due to cylinder-to-cylinder variations of the combustion process. The cause of cylinder-to-cylinder variations is strongly tied to non-uniform trapped mass. In particular, in-cylinder oxygen concentration plays a critical role in the combustion process of each cylinder and can be leveraged to predict combustion characteristics and to develop control algorithms that mitigate cylinder-to-cylinder variation.
2015-04-14
Journal Article
2015-01-0869
Ningsheng Qiao, Chandrasekar Krishnamurthy, Nicholas Moore
Air-fuel ratio cylinder imbalance is a condition where the air-fuel ratio in one or more cylinders is different than the other cylinders. When air-fuel ratio cylinder imbalance occurs in one or more cylinders the fuel delivery system is unable to maintain a proper vehicle emission level. It is required for on-board diagnostics to detect air-fuel ratio cylinder imbalance levels which cause the fuel delivery system to be unable to maintain vehicle emissions at or below 1.5 times of any of the applicable FTP (Federal Test Procedure) emission standards. Currently California Air Resources Board (CARB) only requires on-board diagnostics to detect exhaust bank specific air-fuel ratio cylinder imbalance. In the near future CARB will require on-board diagnostics to detect cylinder specific air-fuel ratio cylinder imbalance. This paper presents a non-intrusive approach on determining single cylinder air-fuel ratio imbalance identification (ID) with an oxygen sensor.
2015-04-14
Journal Article
2015-01-0400
Lei Zhou, Zhen Lu, Zhuyin Ren, Tianfeng Lu, K.H Luo
Abstract Detailed chemical kinetics is essential for accurate prediction of combustion performance as well as emissions in practical combustion engines. However, implementation of that is challenging. In this work, dynamic adaptive chemistry (DAC) is integrated into large eddy simulations (LES) of an n-heptane spray flame in a constant volume chamber (CVC) with realistic application conditions. DAC accelerates the time integration of the governing ordinary differential equations (ODEs) for chemical kinetics through the use of locally (spatially and temporally) valid skeletal mechanisms. Instantaneous flame structures and global combustion characteristics such as ignition delay time, flame lift-off length (LOL) and emissions are investigated to assess the effect of DAC on LES-DAC results. The study reveals that in LES-DAC simulations, the auto-ignition time and LOL obtain a well agreement with experiment data under different oxygen concentrations.
2015-04-14
Technical Paper
2015-01-0389
Zhichao Zhao, Zhengxin Xu, Jingping Liu, Mianzhi Wang, Chia-Fon Lee, Wayne Chang, Jie Hou
Abstract A multi-step acetone-butanol-ethanol (ABE) phenomenological soot model was proposed and implemented into KIVA-3V Release 2 code. Experiments were conducted in an optical constant volume combustion chamber to investigate the combustion and soot emission characteristics under the conditions of 1000 K initial temperature with various oxygen concentrations (21%, 16%, 11%). Multi-dimensional computational fluid dynamics (CFD) simulations were conducted in conjunction under the same operation conditions. The predicted soot mass traces showed good agreement with experimental data. As ambient oxygen decreased from 21% to 11%, ignition delay retarded and the distribution of temperature became more homogenous. Compared to 21% ambient oxygen, the peak value of total soot mass at 16% oxygen concentration was higher due to the suppressed soot oxidation mechanism.
2015-01-14
Technical Paper
2015-26-0102
Dhaval Dhruv, Sribathy Thirumavalavan, Manoj Kumar Thangamaniraj, Vinodhkumar Vellaichamy
Abstract To meet OBD norms for exhaust gas oxygen sensor component, there are various methods developed to monitor health of the same in engine management system. Here a new diagnosis strategy for exhaust gas oxygen sensor response is proposed, mainly applicable for start-stop vehicles. This diagnosis strategy is executed during the change in engine running state to stop state due to start-stop feature. In general, before the engine stop is triggered, the lambda in the engine can be rich or lean; then when engine is stopped, fuel injection is cut-off and only air passes through. Due to inertia of engine rotation after fuel cut-off, this air is still passed across oxygen sensor in exhaust path. So here if lambda before fuel cut-off is maintained rich, then rich to lean (i.e. air) transition is realized by oxygen sensor. These are transitions where the oxygen sensor response is evaluated having the coordination with start-stop module.
2014-11-11
Technical Paper
2014-32-0143
Ken Fosaaen
Abstract Global concerns over pollution have led to increasingly strict emissions legislation targeting small engines, which currently pollute at a much greater level than modern multi-cylinder automotive engines. Closed-loop control may be required to meet many future legislation requirements; however, such systems can be impractical due to high added component costs. A necessary component for closed-loop engine control is an oxygen sensor. Existing automotive oxygen sensors are too large, require too much power, and are far too expensive to be suitable for the vast majority of the global small engine applications; therefore, some manufacturers have developed smaller and/or unheated versions based on their existing sensors to meet this emerging need. The ability to miniaturize resistive based sensors well below that of traditional Nernst (zirconia based) oxygen sensors affords the opportunity to meet future emissions standards with less of an impact on cost.
2014-11-11
Technical Paper
2014-32-0137
Ken Fosaaen
Abstract Global concerns over pollution have led to increasingly strict emissions legislation targeting small engines, which currently pollute at a much greater level than modern multi-cylinder automotive engines. Closed-loop control may be required to meet many future legislation requirements; however, such systems can be impractical due to high added component costs. A necessary component for closed-loop engine control is an oxygen sensor. Existing automotive oxygen sensors are too large, require too much power, and are far too expensive to be suitable for the vast majority of the global small engine applications; therefore, some manufacturers have developed smaller and/or unheated versions based on their existing sensors to meet this emerging need. The ability to miniaturize resistive based sensors well below that of traditional Nernst (zirconia based) oxygen sensors affords the opportunity to meet future emissions standards with less of an impact on cost.
2014-11-11
Technical Paper
2014-32-0069
Ken Fosaaen
Abstract Global concerns over pollution have led to increasingly strict emissions legislation targeting small engines, which currently pollute at a much greater level than modern multi-cylinder automotive engines. Closed-loop control may be required to meet many future legislation requirements; however, such systems can be impractical due to high added component costs. A necessary component for closed-loop engine control is an oxygen sensor. Existing automotive oxygen sensors are too large, require too much power, and are far too expensive to be suitable for the vast majority of the global small engine applications; therefore, some manufacturers have developed smaller and/or unheated versions based on their existing sensors to meet this emerging need. The ability to miniaturize resistive based sensors well below that of traditional Nernst (zirconia based) oxygen sensors affords the opportunity to meet future emissions standards with less of an impact on cost.
2014-10-13
Journal Article
2014-01-2642
Masaki Kuribayashi, Yuta Mizutani, Yutaro Ishizuka, Natsuki Taki, Tetsuya Aizawa
Abstract For better understanding of soot formation and oxidation processes in diesel combustion, effects of ambient oxygen concentration on in-flame diesel soot particle properties including concentration, size, number density and morphology were investigated in a constant volume combustion vessel via simultaneous LII (Laser-Induced Incandescence) / LS (Laser Scattering) imaging techniques and TEM (Transmission Electron Microscopy) analysis. An analysis of LII and LS images yielded 2-dimensional distribution images of concentration, size and number density of soot particles in diesel spray flame, based on a practical assumption that LII and LS signals are proportional to the soot particle size to the power of 3 and 6, respectively.
2014-04-01
Technical Paper
2014-01-1177
Paul B. Dickinson, Kieran Hegarty, Nick Collings, Tashiv Ramsander
Abstract The control of NOX emissions by exhaust gas recirculation (EGR) is of widespread application. However, despite dramatic improvements in all aspects of engine control, the subtle mixing processes that determine the cylinder-to-cylinder distribution of the recirculated gas often results in a mal-distribution that is still an issue for the engine designer and calibrator. In this paper we demonstrate the application of a relatively straightforward technique for the measurement of the absolute and relative dilution quantity in both steady state and transient operation. This was achieved by the use of oxygen sensors based on standard UEGO (universal exhaust gas oxygen) sensors but packaged so as to give good frequency response (∼ 10 ms time constant) and be completely insensitivity to the sample pressure and temperature. Measurements can be made at almost any location of interest, for example exhaust and inlet manifolds as well as EGR path(s), with virtually no flow disturbance.
2014-04-01
Journal Article
2014-01-1188
James P. Szybist, Richard R. Steeper, Derek Splitter, Vickey B. Kalaskar, Josh Pihl, Charles Daw
Fuel injection into the negative valve overlap (NVO) period is a common method for controlling combustion phasing in homogeneous charge compression ignition (HCCI) and other forms of advanced combustion. When fuel is injected into O2-deficient NVO conditions, a portion of the fuel can be converted to products containing significant levels of H2 and CO. Additionally, other short chain hydrocarbons are produced by means of thermal cracking, water-gas shift, and partial oxidation reactions. The present study experimentally investigates the fuel reforming chemistry that occurs during NVO. To this end, two very different experimental facilities are utilized and their results are compared. One facility is located at Oak Ridge National Laboratory, which uses a custom research engine cycle developed to isolate the NVO event from main combustion, allowing a steady stream of NVO reformate to be exhausted from the engine and chemically analyzed.
2013-10-15
Technical Paper
2013-32-9065
Yameogo Amadou, Chang-Tai Wu, Yu-Cheng Jiang, Jau-Huai Lu
Use of catalyst in engines has entailed a radical increase in the importance of misfire detection. When a misfire occurs, hydrocarbon emissions will increase and the unburned fuel can damage the catalyst by overheating. On-Board Diagnostics II (OBDII) regulations are still not applied to motorcycle or moped yet. However its application is under discussion in European Union. In Taiwan, OBD is scheduled to be implemented soon. Many strategies of misfire detection have been developed, including variation in engine shaft angular speed, spark plug voltage, cylinder pressure, oxygen sensor signal, knowledge based expert system, and neural networks. WE propose a new method to use the real time signals of a wide band oxygen sensor to detect misfire where, misfire was induced on purpose with a misfire generator. The sensor and the misfire trigger signals were recorded simultaneously.
2013-09-08
Technical Paper
2013-24-0056
Jianxi Zhou, Stephane Richard, Christine Mounaïm-Rousselle, Fabrice Foucher
In the present study, experiments were carried out in a single-cylinder downsized SI engine with different rates of oxygen (15% to 27% by volume in the total mixture of intake gases except fuel) and equivalence ratios (from 0.45 to 1). Therefore, the oxygen volume fraction is due to oxygen enrichment or nitrogen dilution. The study of the impact of controlling oxygen concentration on the combustion characteristics and emissions was performed at 1400 rpm, at several loads (Indicated Mean Effective Pressure (IMEP) from 400 to 1000 kPa). For each operation point, the spark advance and the intake pressure were adjusted simultaneously in order to maintain the load and obtain a minimum value of indicated Specific Fuel Consumption (SFC). The effect of oxygen concentration on the engine combustion characteristics was simulated by using the commercial software AMESim, with the combustion model developed by IFP-EN, and an adapted algorithm was used to avoid residual gas calibration.
2013-04-08
Journal Article
2013-01-0901
Emre Cenker, Gilles Bruneaux, Lyle Pickett, Christof Schulz
Within the Engine Combustion Network (ECN) spray combustion research frame, simultaneous line-of-sight laser extinction measurements and laser-induced incandescence (LII) imaging were performed to derive the soot volume fraction (fv). Experiments are conducted at engine-relevant high-temperature and high-pressure conditions in a constant-volume pre-combustion type vessel. The target condition, called "Spray A," uses well-defined ambient (900 K, 60 bar, 22.8 kg/m₃, 15% oxygen) and injector conditions (common rail, 1500 bar, KS1.5/86 nozzle, 0.090 mm orifice diameter, n-dodecane, 363 K). Extinction measurements are used to calibrate LII images for quantitative soot distribution measurements at cross sections intersecting the spray axis. LII images are taken after the start of injection where quasi-stationary combustion is already established.
2013-04-08
Technical Paper
2013-01-0899
Hideyuki Ogawa, Gen Shibata, Xueming Jin, Toshiyuki Hirose, Naoki Kono
Low NOx and soot free premixed diesel combustion can be realized by increasing ignition delays in low oxygen atmospheres, as well as the combustion here also depends on fuel ignitability. In this report single intermittent spray combustion with primary reference fuels and a normal heptane-toluene blend fuel under several oxygen concentrations in a constant volume combustion vessel was analyzed with high-speed color video and pressure data. Temperature and KL factor distributions are displayed with a 2-D two-color method. The results show that premixing is promoted with a decrease in oxygen concentration, and the local high temperature regions, above 2200 K, as well as the duration of their appearance decreases with the oxygen concentration. With normal heptane, mild premixed diesel combustion can be realized at 15 vol% oxygen and there is little luminous flame.
2013-04-08
Technical Paper
2013-01-0895
Yingying Lu, Wenbin Yu, Yiqiang Pei, Wanhua Su
In this study, experimental and simulation investigations on the roles of charge density (ρtdc), temperature (Τtdc) at the top dead center and oxygen concentration (φO2) on the combustion paths, emissions and thermal efficiency of a high load operation diesel engine were conducted. Experimental engine was a modified single-cylinder engine equipped with variable mechanisms of boost, exhaust gas recirculation (EGR) and intake valve closing timing (IVCT) to regulate the Ptdc, φO2 and Τtdc. Simulations of engine combustion processes were performed with an ECFM-3Z combustion model. The results revealed that higher Ptdc, leading to lower overall fuel/oxygen equivalence ratio (Φm), enhanced the rate of mixing and chemical reaction and benefited improvement of the thermal efficiency.
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