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Viewing 31 to 60 of 43980
2017-10-08
Technical Paper
2017-01-2255
Raul Payri, Jaime Gimeno, Santiago cardona, Sridhar Ayyapureddi
In this article, a prototype multi-hole diesel injector from a high-pressure common rail system is used in a high-pressure and high-temperature test rig capable of reaching 1100 Kelvin and 150 bars under different oxygen concentrations. A novel optical set-up capable of visualizing the soot cloud evolution from 30 to 85 millimeters from the nozzle exit with the high-speed color diffused back illumination technique is used thanks to the insertion of a high-pressure window in the injector holder opposite to the frontal window of the vessel. Experimental results show the reduction of soot formation with an increase in injection pressure, a reduction in chamber temperature, a reduction in oxygen concentration or a reduction in chamber density.
2017-10-08
Technical Paper
2017-01-2233
Gautam Kalghatgi, Kai Morganti, Ibrahim Algunaibet
Knock in spark ignition engines is stochastic in nature. It is caused by autoignition in hot spots in the unburned end-gas ahead of the expanding flame front. Knock onset in an engine cycle can be predicted using the Livengood-Wu integral if the variation of ignition delay with pressure and temperature as well as the pressure and temperature variation with crank angle are known. However knock intensity (KI) is determined by the evolution of the pressure wave following knock onset. In an earlier paper (SAE 2017-01-0689) we showed that KI can be approximated by KI = Z(Pko)(∂T/∂x)-2 where Z is a function of Pko, the pressure, and (∂T/∂x) is the temperature gradient in the hot spot at knock onset. Then, from experimental measurements of KI and Pko, using five different fuels, with the engine operating at boosted conditions, a probability density function for (∂T/∂x) was established.
2017-10-08
Technical Paper
2017-01-2268
Zhanming Chen, Long Wang, Tiancong Zhang, Qimeng Duan, Bo Yang
Liquefied natural gas (LNG) fuelled engines have been widely equipped on heavy duty vehicles both for fuel-economic and environmental protection concerns, however, they always suffer from deteriorated combustion performance and flame stability due to relatively low burning velocity of methane for lean mixture. In this paper, experimental study was conducted on a turbo-charged, spark-ignition, lean-burn LNG engine with methanol port injection. The combustion characteristics such as cylinder pressure traces, heat release rate (HRR), mass fraction burned (MFB), ignition delay, centroid of heat release, position of CA50 and CA90, as well as cyclic variation of peak pressure were analysed under light load (BMEP=0.3876MPa) with different methanol substitution rates (MSR=0%, 5.2%, 10.2%, 17.2%). The experimental results show that combustion phase advanced with increment of MSR due to faster burning velocity of methanol.
2017-10-08
Technical Paper
2017-01-2318
Xiaoxu Jia, Zhong Huang, Dehao Ju, Zhen Huang, Xing-cai Lu
Combustion instability often occurs inside the combustion chamber of aerospace engine. Almost every rocket engine using liquid fuel suffers combustion instability problem during R&D process. High frequency pressure oscillation inside the combustor, categorically those higher than 1kHz, can lead severe vibration to engine component and cause significant engine damage in a very short time. Dealing with this problem is one of the main subjects while developing rocket engine with superior stability and reliability. Fuel atomization and evaporation, one of the controlling processes of combustion rate, is an important mechanism of the combustion instability. To decrease and control the combustion instability, it challenges a deep understanding of the underlying mechanism of fuel atomization and evaporation process. In this paper, acoustic field was established to simulate the pressure fluctuation.
2017-10-08
Technical Paper
2017-01-2462
Ruipeng Zhang, Kaichuang Meng
The powertrain of the separated axle hybrid electric dump truck was analyzed, and the vehicle dynamics model was established. Considering the switch among different drive modes during the process of driving, a driving force coordinated allocation control strategy was applied. The control strategy adopts hierarchical structure, the upper layer determines power take-off mode of the vehicle, the middle layer calculates the drive torque of each axle according to its axle load, the lower layer uses PID algorithm to avoid the slip of the drive axle. Control model is established according to the control strategy, combined with the established vehicle dynamic model, co-simulation was conducted. The simulation results show that the driving force coordinated control strategy can adapt to the full load climbing condition and low adhesion road condition, realize the reasonable distribution of driving force and make full use of the ground adhesion.
2017-10-08
Technical Paper
2017-01-2346
Hong Liu, Jiajia Jin, Hongyu Li, Kazuo Yamamori, Toyoharu Kaneko, Minoru Yamashita, Liping Zhang
According to the Toyota gasoline engine oil requirements, this paper describes that the low viscosity engine oil of 0W-16 has been developed jointly by Sinopec and Toyota,which also conforms to the Toyota specification. As we know, the development of low viscosity gasoline engine oils should not only focus on fuel economy improvement, but shear stability and low speed pre-ignition (LSPI) prevention property should be taken into consideration. The main elements content in the formulation was determined according to the results of Toyota’s previous LSPI research and the initial 0W-16 engine oil had passed Toyota LSPI test. Based on all above, viscosity index improver (VII) with better friction reduction property was selected by the Mini-traction Machine (MTM) and the High-frequency Reciprocating Rig (HFRR) tests.
2017-10-08
Technical Paper
2017-01-2424
Shemin zhang, Huaping Li, Tao Chen, Nan Jiang, Xinzhen Tan, Limei Deng, Qingsong Xia, Paul Kapus, Mingtang Ma, Wei Li, Junqiang Zhang, Qingjun Ma, Yong Xia
In recent years, more attentions have been paid to stringent legislation on fuel and emissions. Turbocharged downsizing DI engine is playing an increasing vital role in OEM’s powertrain strategies. Dongfeng Motor (DFM) has developed a new type of 1.0-liter 3 cylinder TGDI gasoline engine to meet the requirements of China 4th stage fuel consumption regulations and the China 6 emission standards. In this paper, the concepts of DFM 3-cylinder 1.0TGDI gasoline engine are explored to meet the powerful performance (torque 190Nm/1500-4500rpm and power 95kW/5500rpm), excellent part-load BSFC and NVH targets to ensure the drivers could enjoy the powerful output in quiet and comfortable environment without concerning about the fuel cost and pollution. The combustion system with side-mounted 6-hole direct injector and 200bar injection pressure has been optimized by CFD simulation and transparent engine investigation.
2017-10-08
Technical Paper
2017-01-2375
Akihiro Niwa, Shogo Sakatani, Eriko Matsumura, Takaaki Kitamura
Diesel engine has low carbon emissions and high fuel efficiency. However, diesel engine needs to reduce both Nitrogen Oxide (NOx) and Particulate matters (PM). To meet the demand of strict exhaust gas regulation, after-treatment device is required. Therefore, urea SCR (Selective Catalytic Reduction) system is used to clean NOx in diesel engine exhaust gas. In urea SCR system, it is necessary to inject the urea water solution upstream the SCR catalyst. And, it can reduce NOx applying the generated ammonia (NH3) by urea thermolysis and isocyanic acid (HNCO) hydrolysis. In this study, it focused on urea SCR system. The spray behavior injected in tail-pipe can be divided into the regime of a free spray, an impingement spray, an evaporation of liquid film and a separation droplets, and an urea water solution dispersion. Also, in each region, after evaporation of H2O in urea water solution completely, NH3 is generated by urea thermolysis and HNCO hydrolysis.
2017-10-08
Technical Paper
2017-01-2256
Muhammad Umer Waqas, Kai Morganti, Jean-Baptiste MASURIER, Bengt Johansson
Future internal combustion engines demand higher efficiency, progression towards is limited by antiknock quality of present fuels and energy economics in octane enhancement. A possible solution is Octane-on-Demand, that uses a combination of high and low octane fuels in separated tanks to generate fuels of the required octane rating according to demand. Methanol, a RON 109 fuel was selected as the high octane fuel and five low octane fuels were used as base fuel. These were FACE (Fuels for Advanced Combustion Engines) gasolines, more specifically FACE I, J and A and their primary reference fuels (iso-octane/n-heptane). Experiments were conducted with a modified Cooperative Fuel Research (CFR) engine. For SI combustion mode the CFR operated at RON and MON conditions. The engine i.e. also operated in HCCI mode to get the auto ignition properties at lean conditions (λ=3).
2017-10-08
Technical Paper
2017-01-2186
Lukas Urban, Michael Grill, Sebastian Hann, Michael Bargende
The development of IC engines is a complex process where 0D/1D-simulation tools became more important in the past few years. Different designs can be investigated in very early stages of the development process without the expensive buildup of prototypes and it is possible to get reliable results with passable effort. The quality of the overall simulation results depends on the quality of the sub-models. Simulation of the combustion process in natural-gas SI engines relies on predictive models for burn rates and knock. Existing knock models for gasoline fuels are based on a time-integrated ignition delay, using a fitted Arrhenius equation. Within a research project an enhanced knock-model approach for methane based fuels was developed. Chemical kinetics models were used to calculate the auto-ignition times for various temperatures, pressures and air-fuel-ratios (AFR).
2017-10-08
Technical Paper
2017-01-2446
Pengchuan Wang, Nikolaos Katopodes, Yuji Fujii
Wet clutch packs are the key component for gear shifting in the step-ratio automatic transmission system. They are coupled or de-coupled to alter gear ratios based on driver’s demand and vehicle operating conditions. The frictional interfaces between clutch plates are lubricated with automatic transmission fluid (ATF) for both thermal and friction management. In a 10-speed transmission, there may be as many as 6 clutch packs. Under any driving conditions, 2 to 3 clutch packs are typically open, shearing ATF and contributing to energy loss. There is an opportunity to improve fuel economy by reducing this viscous drag. One main factor that directly affects clutch drag is the clearance between rotating plates. The axial position of clutch plates changes continually at every instance. It is empirically known that not only the total clearance, but also its distribution between the plates affects the viscous drag.
2017-10-08
Technical Paper
2017-01-2366
Wenzheng Xia, Yi Zheng, Xiaokun He, Dongxia Yang, Huifang Shao, Joesph Remias, Joseph Roos, Yinhui Wang
Because of the increased use of gasoline direct engine (GDI) in automobile industry, there is a significant need to control particulates from GDI engines based on emission regulations. One potential technical approach is the utilization of a gasoline particulate filter (GPF). The successful adoption of this emission control technology needs to take many aspects into consideration and requires a system approach for optimization. This study conducted research to investigate the impact of vehicle driving cycles, fuel properties, catalyst coating on the performance of GPF. It was found that driving cycle has significant impact on particulate emission. Fuel quality still plays a role in particulate emissions, and can affect the GPF performance. Catalyzed GPF is preferred for soot regeneration, especially for the case that the vehicle operation is dominated by congested city driving condition, i.e. low operating temperatures. The details of the study are presented in the paper.
2017-10-08
Technical Paper
2017-01-2266
Bin Yang, Hu Wang, Mingfa Yao, Zunqing Zheng, Jialin Liu, Naifeng Ma, Qiping Wang, Haien zha, Peng Chen
Gasoline partially premixed combustion shows the potential to achieve clean and high efficiency combustion. Injection strategies show significant influence on in-cylinder air flow and in-cylinder concentration distribution before auto-ignition, which can significantly affect the combustion characteristics and emissions. This study explored the effects of various injection strategies, including port fuel injection (PFI), single direct injection (DI), double direct injection (DIP+DIM) and port fuel injection coupled with a direct injection (PFI+DIM) on the combustion characteristics and emissions on a modified single cylinder heavy duty diesel engine fueled with 92# gasoline. The results showed that CA5 and CA50 of DIP+DIM are more sensitive to injection timing than PFI+DIM and single direct injection strategy, partially due to the effects of DIP on mixture stratification and low temperature reaction of gasoline.
2017-10-08
Technical Paper
2017-01-2267
Erik Svensson, Lianhao Yin, Per Tunestal, Martin Tuner
The concept of Partially Premixed Combustion (PPC) in engines has shown to achieve very high gross indicated efficiencies, but at the expense of gas exchange efficiencies. Most of the experimental research on PPC has been conducted on compression ignition engines designed to operate on diesel fuel and relatively high exhaust temperatures. The PPC concept on the other hand relies on dilution with high exhaust gas recirculation (EGR) rates to slow down the combustion which results in low exhaust temperatures, but also high mass flows over cylinder, valves, ports and manifolds. A careful design of the gas exchange system, EGR and charge air coolers is therefore of utter importance. Experiments were performed on a heavy-duty, compression ignition engine using a fuel consisting of 80 percent 89 RON gasoline and 20 percent n-heptane. A wide range of engine speeds and loads were run using a long route EGR system.
2017-10-08
Technical Paper
2017-01-2277
Xiao Peng, Han Wu, Chia-Fon Lee, Qianbo sun, Fushui Liu
Methanol has been regarded as a potential transportation fuel due to its advanced combustion characteristics and flexible source. However, it is suffering from misfire and high HC emissions problems under cold start and low load conditions either on methanol SI engine or on methanol/diesel dual fuel engine. Hydrogen is a potential addition that can enhance the combustion of methanol due to its high flammability and combustion stability. In the current work, the effect of hydrogen ratio on the laminar flame characteristics of hydrogen-methanol-air mixture under varied equivalence ratios was investigated on a constant volume combustion chamber system coupled with a schlieren setup. A high-speed camera, set at 512X512 pixel and 10000 fps, was used to record the instantaneous images of the flame front during propagating.
2017-10-08
Technical Paper
2017-01-2283
Anand Prabu kalaivanan, Gnanasekaran sakthivel
Electronic Fuel Injection Systems have revolutionised Fuel Delivery and Ignition timing in the past two decades and have reduced the Fuel Consumption and Exhaust Emissions, ultimately enhancing the Economy and Ecological awareness of the engines. But the ignition/injection timing that commands the combustion is mapped to a fixed predefined table which is best suited during the stock test conditions. However continuous real time adjustments by monitoring the combustion characteristics prove to be highly efficient and be immune to varying fuel quality, lack of transient performance and wear related compression losses. Addressing Fuel Quality Issues: For developing countries, Automobile Manufacturers have been Tuning the Ignition/Injection timing Map assuming the worst possible fuel quality. Conventional knock control system focus on engine protection only and doesn't contribute much in improving thermal efficiency.
2017-10-08
Technical Paper
2017-01-2281
Lang Jiang, Zhe Kang, Zhehao Zhang, Zhijun Wu, Jun Deng, Zongjie Hu, Liguang Li
It is a widely consensus that the ambient temperature direct water injection can be utilized to reduce nitric oxides emissions in both diesel and gasoline engine. Since the proposal of water injection technology, there are many researches studying the effect of different direct water injection strategies on nitric oxides emissions and engine performance which generally lead to lower nitric oxides emissions while combustion efficiency deteriorated. The present work aimed at optimizing diesel engine combustion efficiency with the decrement of nitric oxides emissions using optimized water injection strategy. The engine has been modified based on a two cylinder mechanical pump diesel engine into common rail diesel engine with capability in direct water injection. The direct water injection system is designed and manufactured independently, an air-fluid booster is utilized to establish the water injection pressure up to 40MPa.
2017-10-08
Technical Paper
2017-01-2288
Tianyuan Zhou, Changsheng Yao, Fuyuan Yang
Low temperature combustion (LTC) is an advanced combustion mode, which can achieve low emissions of NOx and PM simultaneously, and keep relatively high thermal efficiency at the same time. However, one of the major challenges for LTC is the cold condition. In cold conditions, stable compression ignition is hard to realize, while thermal efficiency and emissions deteriorate, especially for gasoline or fuel with high octane number. This study presents using pressure sensor glow plugs (PSG) to realize Glow plug assisted compression ignition (GA-CI) at cold conditions. Further, a glow plug control unit (GPCU) is developed, a closed-loop power feedback control algorithm is introduced based on GPCU. In the experiment, engine coolant temperature is swept. Experimental results show that GA-CI has earlier combustion phases, larger combustion duration and higher in-cylinder pressure. And misfire is avoided, cycle-to-cycle variations are greatly reduced.
2017-10-08
Technical Paper
2017-01-2285
Eric Randolph, Raphael Gukelberger, Terrence Alger, Thomas Briggs, Christopher Chadwell, Antonio Bosquez Jr
The primary focus of this investigation was to determine the hydrogen reformation, efficiency and knock mitigation benefits of methanol-fueled Dedicated EGR operation, when compared to other EGR types. A 2.0 L turbocharged port fuel injected engine was operated with internal EGR, low-pressure loop (LPL) EGR and Dedicated EGR (D-EGR®) configurations. The internal, LPL-EGR, and D-EGR configurations were operated on neat methanol to display the relative benefit of D-EGR over other EGR types, while the DEGR configuration was also tested on high octane gasoline to highlight the differences and benefits to D-EGR operation of methanol compared to gasoline. Additional sub-tasks of the work were to investigate combustion stability, ignition energy requirements and burn rates. It was found that methanol did not increase its H2 yield rate for a given D-EGR cylinder equivalence ratio, even though the H:C ratio of methanol is over twice typical gasoline.
2017-10-08
Technical Paper
2017-01-2304
Hui Ding, Frank Husmeier, Jayesh Gudekar, Amol Bobade, Deepak Patil
This paper discusses the holistic approach of simulating a low pressure pump (LPP) including test stand flow dynamics. The simulation includes all lines, valves, filters, and tank of the test stand providing realistic test operating in the simulation. The capability to capture all line dynamics enables a robust design against resonances and delivers high-quality performance data. Comparison with actual test data agrees very well giving us confidence in the prediction capability of PumpLinx. Despite the large spatial extent of the test stand, PumpLinx is able to generate a feasible mesh resulting in acceptable turn-around times. The ability to still model small gaps and clearance of the LPP very efficiently enables inclusion of realistic tolerances as experienced on hardware. This allows us to translate simulation results for limit sample runs without procurement of hardware reducing development time and cost.
2017-10-08
Technical Paper
2017-01-2289
Chunze Cen, Han Wu, Chia-Fon Lee, Shuxin Hao, Fushui Liu, Yikai Li
Droplets impacting onto the heated surface is a typical phenomenon either in CI engines or in GDI SI engines, which is regarded significant for their air-fuel mixing. Meanwhile, alcohols including ethanol and butanol, has been widely studied as internal combustion engine alternative fuels due to their excellent properties. In this paper, under different component ratio conditions, the ethanol-butanol droplet impacting onto the heated aluminum surface has been studied experimentally. The falling height of the droplets were set at 5cm. A high-speed camera, set at 512×512pixels, 5000 fps and 20 μs of exposure time,was used to visualize the droplet behavior impinging onto the hot aluminum surface. The impact regimes of the binary droplet were identified. The result showed that the Leidenfrost temperature of droplets was affected by the ratio of ethanol to butanol. The higher the content of butanol in the droplet, the higher the Leidenfrost temperature.
2017-10-08
Technical Paper
2017-01-2297
Thomas Dubois, Lidwine ABIAD, Pauline CAINE
As it is the case for Diesel engines, the Gasoline Direct Injection engines are using higher and higher injection pressures. The state of the art GDI engines are currently using injection pressure as high as 500 bar. A lot of work is also currently ongoing on Gasoline Compression Ignition (GCI) engines which use even higher injection pressure (above 1 000 bar). A high injection pressure means that a high pressure pump has to be used and so, proper lubricity has to be brought by the fuel. In the mean time the use of biofuels is increasing and several studies have shown the positive impact of ethanol on the fuel consumption of gasoline engines mainly thru an octane number effect. For all these reasons, it seems important to evaluate the impact of ethanol on the lubricity of gasoline as well as on the response of lubricity additives that may be required in a medium-term future to provide gasoline enough lubricity to ensure the operability of these new engines.
2017-10-08
Technical Paper
2017-01-2182
Xikai Liu, Xingyu Liang, Yonge Wu
According to the study of the soot emission in marine diesel, ,a new reduced mechanism for n-heptane was constructed to describe the combustion process in diesel engine by using sensitivity analysis.Furthermore,verifying the ignition delay time,the laminar flame speed,the flame propagation distance and species profiles in combustion process by using Chemkin Pro in different pressure(13.5atm and 42 atm),initial temperatures and equivalence ratio(0.5 and 1.0).Then,compare the simulated result with the experiment data and the simulated result by using LLNL(lawrence livermore national laboratory)detail mechanism and SKLE(state key laboratory of engine)mechanism.It is demonstrated that the reduced mechanism can not describe the ignition delay time in low temperature.And then,the reduced mechanism was adjusted and optimized to make it more close to the experiment data,and the reduced mechanism were able to predict ignition delay time,laminar flame speed,flame propagation distance and species profiles.The final reduced n-heptane mechanism are more compact compare with the current detailed mechanisms in literature.Thus,this reduced n-heptane mechanism can reduce the pressure of calculation and save the calculation time.
2017-10-08
Technical Paper
2017-01-2188
Bruno S. Soriano, Edward S. Richardson, Stephanie Schlatter, Yuri M. Wright
Dual-fuel combustion is an attractive approach for utilising alternative fuels such as natural gas in compression-ignition internal combustion engines. In this concept, a more reactive fuel is injected in order to provide a source of ignition for the premixed natural gas/air, combining the high efficiency of a compression-ignition engine with the relatively low emissions associated with natural gas. The flame modes present in dual-fuel engines impose a challenge for existing turbulent combustion models. Following ignition, flame propagates through a partially-reacted and inhomogeneous mixture of the two fuels. The objective of this study is to test a new modelling approach that combines the ability of the Conditional Moment Closure (CMC) approach to describe autoignition of fuel sprays with the ability of the G-equation approach to describe the subsequent flame propagation.
2017-10-08
Technical Paper
2017-01-2190
Alessandro D'Adamo, Marco Del Pecchia, Sebastiano Breda, Fabio Berni, Stefano Fontanesi, Jens Prager
CFD simulations of reacting flows are fundamental investigation tools used to predict combustion behaviour and pollutants formation in modern spark-ignition internal combustion engines. Most of the flamelet-based combustion models adopted in current simulations use the fuel/air/residual laminar flame speed as a background to predict the turbulent flame speed. This in turn is a fundamental requirement to model the effective burn rate. The consolidated approach in engine combustion simulations relies on the adoption of empirical correlations for laminar flame speed, which are derived from fitting activity of combustion experiments. However, these last are conducted at largely different pressure and temperature ranges from those encountered in engines: for this reason, correlation extrapolation at engine conditions is inevitably accepted and relevant differences between proposed correlations emerge even for the same fuel and conditions.
2017-10-08
Technical Paper
2017-01-2193
Andreas Nygren, Anders Karlsson
When developing new combustion concepts, CFD simulations is a powerful tool. The modeling of spray formation is a challenging but important part when it comes to CFD modelling of non-premixed combustion. There is a large difference in the accuracy and robustness among different spray models and their implementation in different CFD codes. In the work presented in this paper a spray model, designated as VSB2 has been implemented in OpenFOAM. VSB2 differ from traditional spray models by replacing the Lagrangian parcels with stochastic blobs. The stochastic blobs consists of a droplet size distribution rather than equal sized droplets, as is the case with the traditional parcel. The VSB2 model has previously been thoroughly validated for spray formation and combustion of n-heptane. The aim of this study was to validate the VSB2 spray model for ethanol spray formation and combustion as a step in modelling dual-fuel combustion with alcohol and diesel.
2017-10-08
Technical Paper
2017-01-2200
Peter Priesching, Mijo Tvrdojevic, Ferry Tap PhD, Casper Meijer
Turbulent combustion modeling in a RANS or LES context imposes the challenge of closing the chemical reaction rate on the sub-grid level. Many turbulent combustion models exist in literature. Such turbulent models have as their two main ingredients sources from chemical reactions and turbulence-chemistry interaction. The various combustion models then differ mainly by how the chemistry is calculated (level of detail, canonical flame model) and on the other hand how turbulence is assumed to affect the reaction rate on the sub-grid level (turbulence-chemistry interaction - TCI). In this work, an advanced combustion model based on tabulated chemistry is applied for 3D CFD modeling of Diesel engine cases. The combustion model is based on the Flamelet Generated Manifold (FGM) chemistry reduction technique. The underlying chemistry tabulation process uses auto-ignition trajectories of homogeneous fuel/air mixtures, which are computed with detailed chemical reaction mechanisms.
2017-10-08
Technical Paper
2017-01-2192
Shenghui Zhong, Zhijun Peng, Yu Li, Hailin Li, Fan ZHANG
A 3D DNS (Three-dimensional direct numerical simulation) study with detailed chemical kinetic mechanism of methane has been performed to investigate the characteristic of turbulent premixed oxy-fuel combustion relevant to traditional spark ignition (SI) engine conditions. H2O and CO2 are adopted as the dilution agents in oxy-fuel combustion. In order to keep a consistent temperature profile compared with those of air-fired cases, 73% and 66% of H2O and CO2 in oxidizer by volume ratio are used. At first, laminar premixed flames are conducted to study the effect of the dilution molar fraction on the process of flame propagation. It is found that decreasing the dilution molar fraction will increase the flame propagation speed in both H2O and CO2 dilution cases, and there exists a temperature limitation because of chemical equilibrium.
2017-10-08
Technical Paper
2017-01-2229
Byeongsoek Lee, Heechang Oh, SeungKook Han, SooHyung Woo, JinWook Son
There are two way to improve engine thermal efficiency. One is to improve the theoretical thermal efficiency by increasing the compression ratio and specific heat ratio. The other is to reduce various engine losses like friction, pumping, heat loss. For the development of Ultra High Efficiency, We designed the new 2.0L NA GDI engine based on HMC's Nu 2.0L GDI engine. We conducted various parameter studies related to gasoline combustion characteristic, such as compression ratio, ignition system, intake port design, cam duration, Cooled EGR, etc. As a result, we achieved the maximum thermal efficiency up to 42%(~200g/kWh) in stoichiometric AFR. This paper described the ways and possibilities to improve the maximum thermal efficiency.
2017-10-08
Technical Paper
2017-01-2232
Ho Teng
Atkinson cycle realized with a late intake valve closing (LIVC) and Miller cycle achieved with an early intake valve closing (EIVC) have been recognized as effective approaches for improving the gasoline engine fuel economy. In both Atkinson and Miller cycles, the engine can be designed with a higher geometric compression ratio for increasing the expansion work and the effective compression ratio is governed by the intake valve close (IVC) timing for the knock control. Duration of the intake event and IVC timing affect not only the pumping loss during the gas exchange, but also have strong influences on the friction torques of the intake cams and the turbulence intensities for the in-cylinder charge motion. The latter governs duration of combustion and EGR tolerance, both of which have impacts on the engine thermal efficiency.
Viewing 31 to 60 of 43980