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Technical Paper
2007-10-30
Thet MYO, Eiji KINOSHITA, Hidenori TSURU, Kazunori HAMASAKI
The fuel properties, the diesel combustion and the exhaust emissions of palm kernel oil methyl ester (PKME) and a blend of 20% PKME with 80% JIS No.2 gas oil (PK-B20) were investigated. In this study, the fuel properties were measured by laboratory analyses and the engine experiments were carried out by using a single cylinder direct injection diesel engine. To make comparison between biodiesels and conventional diesel fuel, palm oil methyl ester (PME), coconut oil methyl ester (CME), and the gas oil (JIS No.2) were also used as test fuels. From the fuel property analyses and the engine experimental results; the pour point of PKME was -5°C which was the same as that of CME and the pour point of PK-B20 was -10°C, the brake thermal efficiency of PKME was the same as the other test fuels, the ignition ability of PKME was better than that of the gas oil and the exhaust emissions (CO, HC, NOx and smoke) from PKME were almost the same as those of CME and lower than those of the gas oil. Specifically, at 100% load condition, about 47% reduction in smoke emission was found in PKME compare to that of the gas oil.
Technical Paper
2007-10-30
Sundarapandian INDIA, Devaradjane INDIA
A theoretical model was developed to evaluate the performance, characteristics and combustion parameters of vegetable oil esters like Jatropha, Mahua and Neem oil and they are compared to diesel fuel. The predicted results of these fuels are compared with experimental result and also compared with the result of diesel fuel for the validity of the theoretical model. The combustion characteristics and performance parameters are predicted for different vegetable oil esters and for various injection timing. From the predicted results, it is found that the heat release and work done are reduced by about 4% for Jatropha, 6% for Mahua and 8% for Neem oil esters when compared to diesel. However, slight increase is observed for specific fuel consumption. The experimental work is carried out in a single cylinder computerized diesel engine test rig, which develops 5.2 kW at 1500 rpm and loaded by eddy current dynamometer at various Injection timing. The harmful pollutants such as HC, CO, NOX and smoke are reduced in the vegetable oil esters than that of diesel fuel.
Technical Paper
2007-10-30
Tatsuaki SUZUKI, Hiroaki YONETANI, Itaru FUKUTANI
Experiments of combustion observations and radical measurements in DME compression ignition engine were significant for the elucidation of DME combustion. There have been several reports on combustion observation studies of DME compression ignition engines. All of these reports were experimented with the same method observed due to the bottom view, and none of these studies was targeted on low pressure injection and/or small compression ignition engines. In this research, the combustion analysis of the small compression ignition engine with DME low pressure injection was attempted by the top view observation using the wide angle view engine scope. As a result, DME combustion using the ordinary diesel engine's piston chamber shape and material was observed. The production of the exhaust elements (OH, CHO, NO) was obtained to the time series on combustion process of the small compression ignition engine with DME low pressure injection.
Technical Paper
2007-10-30
Wouter DALHUIJSEN, Hans BOSMA, Menno MERTS, Lejo BUNING
Using blends of natural gas (NG) and hydrogen as an alternative to gasoline in Internal Combustion Engines (ICEs) has the potential of a major reduction in CO2 and other harmful emissions, besides giving insight into the use of gaseous biofuels, rich in methane and hydrogen, and offering a transition scenario towards a hydrogen economy. To investigate the consequences of using blends, the performance of a 240cc stationary ICE and a Yamaha Majesty YP125FI scooter, converted to run on a large variety of blends of hydrogen and NG, have been investigated at HAN University, Netherlands. The effect of the air-to-fuel ratio and the composition of the blend on the performance and the emissions have been studied. This paper gives insight into those effects. Main conclusions: With only minor modifications a large variety of blends can be used. By adding H2 to NG: CO2, CO, and HC emissions are reduced; NOx emission is increased; high λ is possible, which can eliminate high NOx; power and efficiency drop approximately 10%.
Technical Paper
2007-10-30
Manqun LIN, Bin JIA, Xicheng YAN, Shun ZHANG
Ethanol as oxygen additive has potential dangerous that might make poisonous organic compound exhaust more than that from pure gasoline fueled engines. This paper was concerned to methods research of sampling, separating and analysis of unconventional HC exhaust emission. Aimed at the difficult problem of formaldehyde measurement, author enriched formaldehyde by water and then measured by means of ultraviolet-visible spectrometer. The minimum measuring limits of formaldehyde was remarkably promoted to 0.02×10-6 (V/V). Furthermore, Solid-Phase Extraction Column which was pre-coated by dinitrophenylhydrazone (DNPH) was selected to catch aldehyde and ketone by chemical reaction which is so called ramification, and then measured by Liquid-chromatography. Up to now, more than 8 different organic have been determined. It was shown that formaldehyde as high toxicity exhaust emission was much more than that from gasoline fueled engine.
Technical Paper
2007-10-30
Tetsuya OHIRA, Kenji NAKAGAWA, Kimikata YAMANE, Hiroshi KAWANABE, Masahiro SHIOJI
In an attempt to grab potential issues with a hydrogen direct injection lean burn engine to have similar power output to a gasoline-fuelled engine, emission characteristics of a hydrogen engine was investigated. It is demonstrated that low NOx emission can be achievable without any catalytic converter. Two major issues, however, have been recognized, that is, combustion instability at low load conditions and too low temperature of exhaust gas to get enough boosting pressure. Hydrogen concentration heterogeneous of the mixture was focused in the CFD and visualization study. Hydrogen jet design of an injector could contribute to improvement of mixing.
Technical Paper
2007-10-30
Chunming Hu, Na Liu, Wei Li, Xijuan Song
Exhaust Gas Recirculation (EGR) is an extensively applied approach for the engine emission control, which is the most effective for reducing NOX emissions. However, as increasing EGR rate, the burning velocity of LPG mixture will be slow that it impacts the complete combustion and combustion stability. The effects of EGR on the rapid lean-burning and NOX emissions of the LPG engine with EFI is introduced in this paper. Test data showed that the dual-spark plug ignition-based rapid burning system could increase the combustion rate of LPG mixture, and improve the rapid burning process of the LPG engine with EGR. Meanwhile, the excess air rate Φa limits of LPG lean-burning will be largely extended within the whole effective range of EGR rate. At the equivalent running conditions of LPG engine, largely extended EGR rate could restrain the formation of NOX emissions by the high combustion temperature. As a result, due to the increases in burning velocity and heat efficiency, the LPG engine could realize the Φa limits in lean-burning process with a higher EGR rate.
Technical Paper
2008-04-14
Gerd Gaiser, Patrick Mucha, Björn Damson, Josef Rudelt
Active engine-based measures are currently used to assist the exhaust aftertreatment. This paper presents the current predevelopment of a system for active exhaust aftertreatment of diesel engines which enables exhaust aftertreatment to be decoupled from engine-based measures. At the heart of the system, the Fuel Processor is the active component which is used to combust, reactively evaporate or partially oxidise the fuel, as required. Active catalytic converter heating, active particulate filter regeneration or heating of a SCR catalytic converter are possible without engine-based measures.
Technical Paper
2008-04-14
Nobumoto Ohashi, Koichiro Nakatani, Takamitsu Asanuma, Takao Fukuma, Hiroyuki Matsubara, Yuichi Sobue, Masao Watanabe
Diesel particulate and NOx reduction system (DPNR) is an effective technology for the diesel after-treatment system, which can reduce particulate matter (PM) and nitrogen oxides (NOx) simultaneously. The DPNR has been developed under the Toyota D-CAT (Diesel Clean Advanced Technology) concept. Further improvement of the DPNR is hoped for cleaner air in the future. This paper reviews the results of our study to improve the NOx purification performance on the DPNR. The NOx reduction performance of the catalysts deteriorates due to thermal deterioration and sulfur poisoning. In order to improve the thermal resistance of the catalysts, the suppression of precious metal sintering in the catalyst has been studied. As a result, higher catalytic activity after aging especially under lower temperature conditions was obtained. On the other hands, improvement of desulfurization performance is one of the key technologies in order to keep the high NOx reduction capability of the catalyst. Keeping high and uniform catalyst bed temperature has accelerated the sulfur desorption from the storage material.
Technical Paper
2008-04-14
Ryo Hasegawa, Ichiro Sakata, Hiromichi Yanagihara, Marcus Aldén, Bengt Johansson
The structure of HCCI (homogeneous charge compression ignition) combustion flames was quantitatively analyzed by measuring the two-dimensional gas temperature distribution using phosphor thermometry. It was found from the relation between a turbulent Reynolds number and Karlovitz number that, when compared with the flame propagation in an S.I. engine, HCCI combustion has a wider flame structure with respect to the turbulence scale. As a result of our experimentation for the influence of low temperature reaction (LTR) using two types of fuel, it was also confirmed that different types of fuel produce different histories of flame kernel structure.
Technical Paper
2008-04-14
Yong Sun, Rolf D. Reitz
Homogeneous Charge Compression Ignition (HCCI) combustion is being considered as a practical solution for diesel engines due to its high efficiency and low NOx and PM emissions. However, for diesel HCCI operation, there are still several problems that need to be solved. One is the spay-wall impingement issue associated with early injection, and a further problem is the extension of HCCI operation from low load to higher engine loads. In this study, a combination of Adaptive Injection Strategies (AIS) and a Two-Stage Combustion (TSC) strategy are proposed to solve the aforementioned problems. A multi-dimensional Computational Fluid Dynamics (CFD) code with detailed chemistry, the KIVA-CHEMKIN-GA code, was employed in this study, where Genetic Algorithms (GA) were used to optimize heavy-duty diesel engine operating parameters. The TSC concept was applied to optimize the combustion process at high speed (1737 rev/min) and medium load (57% load). Two combustion modes are combined in this concept.
Technical Paper
2008-04-14
William de Ojeda, Phil Zoldak, Raul Espinosa, Raj Kumar
A production V-8 engine was redesigned to run on low temperature combustion (LTC) with conventional Diesel fuel. Two fuel injection strategies were used to attain reduction in soot and NOx; a) early premixed injection strategy: fuel injected early during the compression stroke and b) late premixed injection strategy: fuel injected close to TDC with heavy EGR. The early premixed injection strategy yielded low NOx and soot but struggled to vaporize the fuel as noted in unburned hydrocarbons readings. The late premixed injection strategy introduced the fuel at higher in-cylinder temperatures and densities, improving the fuel's vaporization and limited the unburned hydrocarbon and carbon monoxide. The use of high EGR and high injection pressure for late premixed injection strategy provided sufficiently long ignition delay that resulted in partially premixed cylinder charge before combustion, and thereby prevented high soot, even in presence of high EGR. The engine operation was enhanced by a specially designed controller to balance all engine cylinders with the aide of in-cylinder pressure transducers.
Technical Paper
2008-04-14
Zhihua Li, Hui Xie, Hua Zhao
In this research, numerical simulation using Star-CD is performed to investigate the mixing process of a single-cylinder experimental gasoline engine equipped with 4VVAS (4 Variable Valve System). Different engine operating conditions are studied with respect to valve parameters, including EVC (Exhaust Valve Closing), IVO (Intake Valve Opening), and IVL (Intake Valve Lift). The definitions of RGF (Residual Gas Fraction)/temperature statistical distribution and inhomogeneity are proposed and quantified, on which the influences of the aforementioned valve parameters are analyzed. Results reveal that, the distribution of in-cylinder residuals varies with valve parameter combinations. Intake valve timing has a greater effect on the in-cylinder distribution and inhomogeneity of residuals than intake valve lift. Earlier IVO leads to lower RGF inhomogeneity around TDC. Different combinations of valve management parameters can result in distinct stratification patterns of residuals in the position and shape of the local high-RGF region.
Technical Paper
2008-04-14
Tsuyoshi Matsuda, Hiroki Wada, Toshiya Kono, Takeshi Nakamura, Tomonori Urushihara
Since the stable operating region of a gasoline-fueled HCCI engine is limited to the part load condition, a mode change between SI and HCCI combustion is required, which poses an issue due to the difference in combustion characteristics. This report focuses on the combustion characteristics in the transitional range. The combustion mode in the transitional range is investigated by varying the internal EGR rate, intake air pressure, and spark advance timing in steady-state experiments. In this parametric study, stable SI-CI combustion is observed. This indicates that the combustion mode transition is possible without misfiring or knocking, regardless of the speed of variable valve mechanism which includes VVA, VVEL, VTEC, VVL and so on, though the response of intake air pressure still remains as a subject to be examined in the actual application.
Technical Paper
2008-04-14
Mingfa Yao, Haifeng Liu, Bo Zhang, Zunqin Zheng
The influence of boost pressure (Pin) and fuel chemistry on combustion characteristics and performance of homogeneous charge compression ignition (HCCI) engine was experimentally investigated. The tests were carried out in a modified four-cylinder direct injection diesel engine. Four fuels were used during the experiments: 90-octane, 93-octane and 97-octane primary reference fuel (PRF) blend and a commercial gasoline. The boost pressure conditions were set to give 0.1, 0.15 and 0.2MPa of absolute pressure. The results indicate that, with the increase of boost pressure, the start of combustion (SOC) advances, and the cylinder pressure increases. The effects of PRF octane number on SOC are weakened as the boost pressure increased. But the difference of SOC between gasoline and PRF is enlarged with the increase of boost pressure. The successful HCCI operating range is extended to the upper and lower load as the boost pressure increased. The maximum achievable load of gasoline is higher than that of PRF with the cases of supercharging.
Technical Paper
2008-04-14
Fumihiko Toyoda, Yukimori Kobayashi, Yoshinori Miura, Yojiro Koga
In the development of automotive engines, reduction of fuel economy is one of very important issues. We focused on reduction in oil pump friction which accounts for 10% of engine friction to enhance fuel economy. As a result, oil pressure was reduced at excessive areas by variable discharge by maintaining required oil pressure for the engine. By that we have succeeded in developing a variable discharge oil pump which can reduce friction by 33% at frequently-used engine speed range.
Technical Paper
2008-04-14
Dongsoo Shim, Hyenwoo Jung, Seungi Kim, Junghwan Lim, Yongseo Hwang
The most popular issues nowadays in the automotive industry include reduction of environmental impacts by emission materials from automobiles as well as improvement of fuel economy. This paper deals with development of a ¡mild-hybrid¡ system for a city bus as an effort to increase fuel economy in a relatively reasonable expense. Three different technical tactics are employed; an engine is shut down at an engine idle state, a vehicle kinetic energy when the bus is decelerated is re-saved to a battery in the form of electricity, and finally the radiator cooling fan is operated by an electric motor using the saved electric energy with an optimal speed control. It has been demonstrated through the driving tests in a specific city mode, ¡Suwon city mode¡, that an average fuel economy is improved more than 12%, and the system can be a feasible choice in a city bus running in a city mode experiencing many stop and go¡s.
Technical Paper
2008-04-14
Saurabh Mahapatra, Tom Egel, Raahul Hassan, Rohit Shenoy, Michael Carone
In this paper, we show how Model-Based Design can be applied in the development of a hybrid electric vehicle system. The paper explains how Model-Based Design begins with defining the design requirements that can be traced throughout the development process. This leads to the development of component models of the physical system, such as the power distribution system and mechanical driveline. We also show the development of an energy management strategy for several modes of operation including the full electric, hybrid, and combustion engine modes. Finally, we show how an integrated environment facilitates the combination of various subsystems and enables engineers to verify that overall performance meets the desired requirements.
Technical Paper
2008-04-14
Steven Boyd, Douglas J. Nelson
For a hybrid electric vehicle (HEV) with an internal combustion engine, simply operating the engine in its regions of high efficiency does not guarantee the most fuel efficient operational strategy. This paper defines an operational strategy for a HEV through calculating individual powertrain component losses and comparing those losses across possible operational modes. The results of these calculations define how the vehicle can decrease fuel consumption while maintaining low vehicle emissions. The results presented are meant only to define a literal strategy; that is, an understanding as to why the vehicle should operate in a certain way given driver demands, vehicle speed, and powertrain limitations.
Technical Paper
2008-04-14
Andrew Barr, Alireza Veshagh
Hybrid vehicles provide the most viable medium term solution to meet the demands of the automotive marketplace. Currently electric hybrids dominate the marketplace but mechanical hybrid systems, including flywheel, pneumatic and hydraulic systems all have the potential to compete with electrical systems. This paper provides an overview of a mechanical hybrid project created by the University of Warwick. The aim of the project is to assess alternative hybrid powertrains, in particular pneumatic, hydraulic and flywheel systems. This paper provides a description of a simulation tool to investigate and evaluate the mechanical alternatives to electric hybrid vehicles and the results from two fuel economy case studies using the simulation tool: 2.6 ton SUV and 17 ton bus applications. The paper also outlines a feasibility study of the mechanical hybrid options, including a cost benefit analysis of the different systems. Finally the paper provides an overview of the Warwick FIVT (flywheel and infinitely variable transmission) transmission, an innovative hybrid transmission concept, and details the future work for the project.
Technical Paper
2008-04-14
Anita Chaudhari, Alexandros Plianos, Richard Stobart
This paper presents a control system design strategy for a novel fuel cell - internal combustion engine hybrid power system. Dynamic control oriented models of the system components are developed. The transient behavior of the system components is investigated in order to determine control parameters and set-points. The analysis presented here is the first step towards development of a controller for this complex system. The results indicate various possibilities for control design and development. A control strategy is discussed to achieve system performance optimization.
Technical Paper
2008-04-14
Paolino Tona, Stéphane Venturi, Richard Tilagone
Compressed natural gas (CNG) is considered as one of the most promising alternative fuels for transportation due to its ability to reduce greenhouse gas emissions and its abundance. More specifically, CNG has a considerable potential when used as a dedicated fuel on a downsized turbo-charged SI engine for a small urban vehicle. This approach can be profitably extended by adding a small secondary (electrical) power source to the CNG engine, thus hybridizing the powertrain. This is why IFP has developed a mild-hybrid CNG prototype vehicle based on a MCC smart car equipped with a starter-alternator and ultra-capacitors (the StARS system). This solution offers some interesting functions such as “Stop'n'Start”, regenerative braking, torque boosting and engine assistance, and yields significant benefits in terms of fuel economy, reduced exhaust emissions and better driveability. The unfolding of this project, named VEHGAN, has involved interesting and challenging issues from an engine control point of view, such as coping with distinctive features of natural gas engines, mastering the automatic manual transmission (AMT) control system and integrating a new power source, with its new functions, into the torque-oriented engine control structure.
Technical Paper
2008-04-14
Thomas Wallner, Scott A. Miers
Early in 2007 President Bush announced in his State of the Union Address a plan to off-set 20% of gasoline with alternative fuels in the next ten years. Ethanol, due to its excellent fuel properties for example, high octane number, renewable character, etc., appears to be a favorable alternative fuel from an engine perspective. Replacing gasoline with ethanol without any additional measures results in unacceptable disadvantages mainly in terms of vehicle range. This paper summarizes combustion studies performed with gasoline as well as blends of gasoline and ethanol. These tests were performed on a modern, 4-cylinder spark ignition engine with direct fuel injection and exhaust gas recirculation. To evaluate the influence of blending on the combustion behavior the engine was operated on the base gasoline calibration. Cylinder pressure data taken during the testing allowed for detailed analysis of rates of heat release and combustion stability. The different fuels are compared in terms of combustion behavior, engine efficiency, as well as regulated emissions.
Technical Paper
2008-04-14
S. Chuepeng, H. M. Xu, A. Tsolakis, M. L. Wyszynski, P. Price, R. Stone, J. C. Hartland, J. Qiao
Increasing biodiesel content in mineral diesel is being promoted considerably for road transportation in Europe. With positive benefits in terms of net CO2 emissions, biofuels with compatible properties to those of conventional diesel are increasingly being used in combustion engines. In comparison to standard diesel fuel, the near zero sulphur content and low levels of aromatic compounds in biodiesel fuel can have a profound effect not only on combustion characteristics but on engine-out emissions as well. This paper presents analysis of particulate matter (PM) emissions from a turbo-charged, common rail direct injection (DI) V6 Jaguar engine operating with an RME (rapeseed methyl ester) biodiesel blended with ultra low sulphur diesel (ULSD) fuel (B30 - 30% of RME by volume). Three different engine load and speed conditions were selected for the test and no modifications were made to the engine hardware or engine management system (EMS) calibration. In this work specific total particulate mass was measured at each operating point and, in addition, thermo-gravimetric analysis (TGA) was used to determine mass fractions of the volatile PM.
Technical Paper
2008-04-14
Hu Li, Amanda Lea-Langton, Gordon E. Andrews, Mark Thompson, Clifford Musungo
Rape oil, as used in fresh cooking oil (FCO), and the methyl ester derived from waste cooking oil (WCOB100) were tested as 100% biofuels (B100) on a heavy duty DI diesel engine under steady state conditions. The exhaust emissions were measured and compared to those for conventional low sulphur (<50ppm) diesel fuel. The engine used was a 6 cylinder, turbocharged, intercooled Perkins Euro2 Phaser Engine, fitted with an oxidation catalyst. The engine out gaseous emissions results for WCOB100 showed a large decrease in CO and HC emissions, but a small increase in NOx emissions compared to diesel. However, for FCO the CO and HC increased relative to WCOB100 and CO was higher than for diesel, indicating deterioration in fuel/air mixing. The particulate matter (PM) emissions for WCOB100 were similar to those for diesel at the 23kw condition, but greatly reduced at 47kw. The FCO produced higher engine out PM at both power conditions due to a higher volatile organic fraction (VOF). FCO was found to have the highest number of nuclei mode particles from the engine, but the greatest reduction across the oxidation catalyst.
Technical Paper
2008-04-14
Kyle L. Fujdala, Timothy J. Truex, John B. Nicholas, Jonathan W. Woo
Euro IV-V and US 2007-2010 emission control regulations, combined with changing engine-out emission characteristics of advanced diesel combustion systems result in different performance and durability requirements for diesel oxidation catalysts depending upon specific platforms and regulation levels. A rational catalyst design approach has been utilized to develop a series of catalysts with performance, durability, and PGM utilization characteristics to meet different system requirements. Promoted-Pt catalysts with 40 °C lower CO light-off temperatures and improved thermal durability compared to Pt-only formulations have been developed for use in applications with low exhaust temperatures. The promoted-Pt catalysts also provide tunable NO oxidation activity, which is important for NO/NO2 control (SCR) and areas where excessive NO2 emissions are of concern. Results are presented for a Pt/Pd formulation that provides major improvements in thermal durability compared to Pt-only formulations for use in high temperature environments (e.g., active regeneration systems).
Technical Paper
2008-04-14
Zongjie Hu, Zhijun Wu, Liguang Li, Guanghai Gao
In this study, a spray hot-impingement system was set up to analyze the spray characteristics when spray impinged onto a flat hot surface by high-speed photography technology. The angle between spray axis and normal line of the flat surface could be changed, and the surface temperature could exceed 400°C. The influences of surface temperature and heating power on spray atomization were investigated too. At atmospheric pressure, when the wall temperature was 340∼380°C, the impinging diesel spray was well atomized. In this experiment, the wall heating power could be set at 1∼25 Wcm-2. When the heating power was about 1.6 Wcm-2, the impinging spray atomized well, and when it was about 10.1 Wcm-2 the spray atomized better though the heating power requirement should be high. The angle (α) between nozzle hole axis and wall normal line apparently affected wall jet velocity Then a segment of steel tube was fixed between the intake manifold and cylinder head in a direct injection natural aspirated diesel engine.
Technical Paper
2008-04-14
Hiroyuki Ohtsubo, Tohru Nakazono, Takayuki Shirouzu, Koji Yamane, Kiyoshi Kawasaki
In this study, it was attempted to operate the 4-cycle multi cylinder natural gas engine introduced PCCI combustion system without electric heater for intake air heating. In experiment, by optimization of the compression ratio and in addition to the control of spark ignition timing, the engine could be operated using only intake air heating with coolant water. The results showed that the suppression of the auto-ignition timing variations among cylinders owing to the independent spark timing control of each cylinder leads to the improvement of engine output, fuel economy and exhaust emissions. Furthermore, this paper describes the engine starting and corresponding change of engine load on electric demand on generator. The stable operation could be achieved by using spark ignition, controlling of excess air ratio and intake air temperature during change the engine load from idle to rated power. Those controls made an adaptation to the rapid change of the engine load with changing combustion modes by using intake air heating with coolant water instead of the electric heater.
Technical Paper
2008-04-14
H. H. Song, C. F. Edwards
In-cylinder pre-processing (or recompression reaction) of direct-injected fuel during the negative valve overlap period of a retention-strategy HCCI engine is investigated for extension of the low-load limit of operation. Experimental studies of three variables (compression ratio, pilot injection timing, and pilot injection amount) were conducted in order to optimize the effects of recompression reaction by changing the sensible and chemical energy environment during recompression. The results from compression ratio variation show that there exist optimum values of equivalence ratio and extent of recompression reaction, which expand the low-load operating region. The pilot injection timing variation demonstrates good controllability of the extent of recompression reaction by effectively changing the in-cylinder residence time of the pilot-injected fuel. Higher extent of recompression reaction results in advanced main combustion timing, which exhibits better stability but slightly reduced efficiency due to enhanced heat transfer.
Technical Paper
2008-04-14
Yu Jiang, Michal Furmanczyk, Samuel Lowry, Dengfu Zhang, Chin-Yuan Perng
Due to complexities of interaction among gears and crescent-shaped island, a crescent oil pump is one of the most difficult auto components to model using three dimensional Computational Fluid Dynamics(CFD) method. This paper will present a novel approach to address the challenges inherent in crescent oil pump modeling. The new approach is incorporated into the commercial pump design tool PumpLinx from Simerics, Inc.. The new method is applied to simulate a production crescent oil pump with inlet/outlet ports, inner/outer gears, irregular shaped crescent island and tip leakages. The pump performance curve, cavitation effects and pressure ripples are studied using this tool and will be presented in this paper. The results from the simulations are compared to the experiment data with excellent agreement. The present study shows that the proposed computational model is very accurate and robust and can be used as a reliable crescent pump design tool.
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