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Viewing 1 to 30 of 12085
2017-10-08
Technical Paper
2017-01-2335
Tiantian Yang, Tie Wang, Jing Qiao, Ji Gao, Yizhuo Feng, Dandan Sun
Abstract The F-T diesel made from coal by Fischer-Tropsch synthesis (F-T) can be used as a clean alternative fuel of diesel engine. To alleviate the drawback of high cost and low viscosity of F-T diesel, the Methanol-Biodiesel -F-T diesel multiple fuel (MBFT) was prepared by adding low-cost methanol and high-viscosity biodiesel as modifiers. Considering the immiscibility between alcohols and hydrocarbons, this paper carried out a series of stability tests and found that n-decanol was the optimum co-solvent of MBFT. The MBFTs blended by biodiesel with the volume fraction of 10% (10% vol.) and methanol with varying proportions of 0%, 5%, 10% and 15% vol. were denoted as M0, M5, M10 and M15, respectively. The increasing methanol proportion caused the increase of the oxygen content in the blended fuels and the reduction of heat value, surface tension and cetane number. The influence of methanol proportion on combustion characteristics of turbo-charging engine was studied.
2017-10-08
Technical Paper
2017-01-2332
Tamara Ottenwaelder, Stefan Pischinger
Abstract In order to reduce engine out CO2 emissions it is a main subject to find new alternative fuels out of renewable sources. For this paper, several fuels were selected which can be produced out of biomass or with hydrogen which is generated directly via electrolysis with electricity from renewable sources. All fuels are compared to conventional diesel fuel and two diesel surrogates. It is well known that there can be a large effect of fuel properties on mixture formation and combustion, which may result in a completely different engine performance compared to the operation with conventional diesel fuels. Mixture formation and ignition behavior can also largely affect the pollutant formation. The knowledge of the combustion behavior is also important to design new engine geometries or implement new calibrations for an existing engine. The fuel properties of the investigated fuels comprise a large range, for example in case of the derived cetane number, from below 30 up to 100.
2017-10-08
Technical Paper
2017-01-2330
Leonardo Israel Farfan-Cabrera, Ezequiel Gallardo, José Pérez-González
Abstract Flouroelastomers and silicone rubbers are commonly employed in static and dynamic seals for automotive applications. In order to prevent premature failures and leakages caused by swelling and/or changes in their mechanical properties, materials for seals are selected according to their compatibility with the environment and fluids involved in the engine operation. Thus, in particular, the use of new fuels and additives in automotive engines requires the assessment of compatibility with common sealing elastomers to prevent failures. Currently, Jatropha oil is being used as a renewable source of fuel in diesel engines for electricity production, transport or agricultural mechanization in various countries. It is used either as biodiesel or as straight vegetable oil (SVO) since it has good heating power and provide exhaust gas with almost no sulfur or aromatic polycyclic compounds. However, the compatibility of elastomers with this SVO has not been investigated yet.
2017-10-08
Technical Paper
2017-01-2331
Amar Deep, Naveen Kumar, Harveer Singh Pali
Abstract The use of alternative fuel has many advantages and the main ones are its renewability, biodegradability with better quality exhaust gas emission, which do not contribute to raise the level of carbon dioxide in the atmosphere. The use of non-edible vegetables oils as an alternative fuels for diesel engine is accelerated by the energy crisis due to depletion of resources and increase in environmental problems. In Asian countries like India, great need of edible oil as a food so cannot use these oils as alternative fuels for diesel engine. However there are many issues related to the use of vegetable oils in diesel engine that is high viscosity, low calorific value, high self-ignition temperature etc. Jatropha curcas has been promoted in India as a sustainable substitute to diesel fuel. This research prepared micro emulsions of ethanol and Jatropha vegetable oil in different ratio and find out the physico-chemical parameters to compare with mineral diesel oil.
2017-10-08
Technical Paper
2017-01-2351
Bernardo Tormos, Guillermo Miró, Leonardo Ramirez, Tomás Pérez
Abstract Low viscosity engine oils are considered a feasible solution for improving fuel economy in internal combustion engines (ICE). So, the aim of this study was to verify experimentally the performance of low viscosity engine oils regarding their degradation process and possible related engine wear, since the use of low viscosity engine oils could imply higher degradation rates and/or unwanted wear performance. Potential higher wear could result in a reduction in life cycle for the ICE, and higher degradation rates would be translated in a reduction of the oil drain period, both of them non-desired effects. In addition, currently limited data are available regarding “real-world” performance of low viscosity engine oils in a real service fleet.
2017-10-08
Technical Paper
2017-01-2354
Dave Horstman, John Sparrow
Abstract Due to recent legislation on CO2 emissions, Heavy Duty engine and vehicle manufacturers and their suppliers have had an increased interest in improving vehicle fuel economy. Many aspects are being investigated including vehicle aerodynamics, tire rolling resistance, waste heat recovery, engine fuel efficiency, and others. Crankcase oils offer a cost-effective mechanism to reduce engine friction and increase engine fuel efficiency. The potential gains realized by optimized fuel-efficient oils are relatively small, usually less than 3%. Therefore, in order to develop these oils, formulators must have a robust, repeatable, and realistic test method for differentiation. To serve Light Duty (LD) engines, this need has been partially satisfied by the development of what became the Sequence VI engine test for gasoline passenger car oils in the early 1990’s.
2017-10-08
Technical Paper
2017-01-2349
Sarita Seth, Swamy Maloth, Prashant Kumar, Bhuvenesh Tyagi, Lokesh Kumar, Rajendra Mahapatra, Sarita Garg, Deepak Saxena, R Suresh, SSV Ramakumar
Abstract Automobile OEMs are looking for improving fuel economy[1,2] of their vehicles by reducing weight, rolling resistance and improving engine and transmission efficiency apart from the aerodynamic design. Fuel economy may be improved by using appropriate low viscosity [3] and use of friction reducers (FRs)[4,5] in the engine oils. The concept of high viscosity index [6] is being used for achieving right viscosity at required operating temperatures. In this paper performance properties of High Viscosity Index engine oils have been compared with conventional VI engine oils. Efforts have been made to check the key differentiation in oil properties w.r.t. low temperature fluidity, high temperature high shear viscosity/deposits, friction behavior, oxidation performance in bench tribological /engine/chassis dyno tests which finally lead to oil performance assessment.
2017-10-08
Technical Paper
2017-01-2350
Chalermwut Wongtaewan, Umaporn Wongjareonpanit, Komkrit Sivara, Ken Hashimoto, Yoichiro Nakamura
Abstract In Thailand, most heavy-duty trucks were equipped with diesel engine, while a small portion was equipped with compressed natural gas (CNG) engine. However, in the past few years the number of CNG fuel trucks in Thailand has increased significantly due to the cheaper cost of CNG. In general, the emphasis of heavy-duty diesel engine oil performance is on piston cleanliness and soot handling properties, while thermal and anti-oxidation properties are most critical for CNG engine oil performance. For truck fleet owners who operate both types of trucks, using the inappropriate oil that is not fit-for-purpose can adversely affect engine performance and reduce engine service lifespan under prolonged usage. A novel CNG/diesel engine oil was developed to meet both JASO DH-2 heavy-duty diesel engine oil performance and CNG engine oil performance. The candidate formulation was proved adequately fit for practical use regarding to thermal and anti-oxidation properties.
2017-10-08
Technical Paper
2017-01-2344
Robert Taylor, Hua Hu, Carl Stow, Tony Davenport, Robert Mainwaring, Scott Rappaport, Sarah Remmert
Abstract It is anticipated that worldwide energy demand will approximately double by 2050, whilst at the same time, CO2 emissions need to be halved. Therefore, there is increasing pressure to improve the efficiency of all machines, with great focus on improving the fuel efficiency of passenger cars. The use of downsized, boosted, gasoline engines, can lead to exceptional fuel economy, and on a well-to-wheels basis, can give similar CO2 emissions to electric vehicles (depending, of course, on how the electricity is generated). In this paper, the development of a low weight concept car is reported. The car is equipped with a three-cylinder 0.66 litre gasoline engine, and has achieved over 100 miles per imperial gallon, in real world driving conditions.
2017-10-08
Technical Paper
2017-01-2338
Muhammad Saqib Akhtar, Shuaishuai Sun, Xiao Ma, Yitao Shen, Shi-Jin Shuai, Zhi Wang
Abstract Natural gas is one of the promising alternative fuels due to the low cost, worldwide availability, high knock resistance and low carbon content. Ignition quality is a key factor influencing the combustion performance in natural gas engines. In this study, the effect of pre-chamber geometry on the ignition process and flame propagation was studied under varied initial mixture temperatures and equivalence ratios. The pre-chambers with orifices in different shapes (circular and slit) were investigated. Schlieren method was adopted to acquire the flame propagation. The results show that under the same cross-section area, the slit pre-chamber can accelerate the flame propagation in the early stages. In the most of the cases, the penetration length of the flame jet and flame area development are higher in the early stages of combustion.
2017-10-08
Technical Paper
2017-01-2339
Pi-qiang Tan, Yuan Li
Abstract With increasingly severe atmospheric environmental problems, diesel car emissions have attracted broad attention for its main contribution to air pollutant. Alternative fuels become a hot research point in vehicle for rapidly consuming of fossil oil resources. Biodiesel and GTL (gas to liquid) fuels are two typical alternative fuels for diesel fuel. Low blend ratio (≤10%) biodiesel and GTL fuels can be used in a diesel engine without modifying the engine’s configuration. It is important to investigate the difference of low blend ratio biodiesel and GTL fuels used in the same diesel car and to find the optimum one. Gaseous and particle emissions from a light duty diesel car with B10 (10% biodiesel from cooking oil +90% diesel, v/v) and G10 (10% GTL fuel +90% diesel, v/v) was investigated. It was equipped with high pressure common rail system, cooled EGR and DOC and was tested on a chassis dynamometer under NEDC mode.
2017-10-08
Technical Paper
2017-01-2340
Shashank Mishra, Anand Krishnasamy
Abstract Biodiesel is a renewable, carbon neutral alternative fuel to diesel for compression ignition engine applications. Biodiesel could be produced from a large variety of feedstocks including vegetable oils, animal fats, algae, etc. and thus, vary significantly in their composition, fuel properties and thereby, engine characteristics. In the present work, the effects of biodiesel compositional variations on engine characteristics are captured using a multi-linear regression model incorporated with two new biodiesel composition based parameters, viz. straight chain saturation factor (SCSF) and modified degree of unsaturation (DUm). For this purpose, biodiesel produced from seven vegetable oils having significantly different compositions are tested in a single cylinder diesel engine at varying loads and injection timings. The regression model is formulated using 35 measured data points and is validated with 15 other data points which are not used for formulation.
2017-10-08
Technical Paper
2017-01-2355
Yungwan Kwak, Christopher Cleveland
Abstract Due to its simplicity and fuel economy benefit, continuously variable transmission (CVT) technology has gained a lot of attention in recent years. Market penetration of CVT technology is increasing rapidly compared to step-type automatic transmission technology. OEMs, Tier 1 suppliers, and lubricant suppliers are working to further improve the fuel economy benefit of CVTs. As a lubricant supplier, we want to understand the effects of fluid properties on CVT fuel economy (FE). We have formulated fluids that had KV100 ranges from 2-4 cSt to 7-9 cSt with various types and viscosities of base oils. Wide ranges of viscosity indexes, steel-on-steel friction, and other properties were tested. Full vehicle fuel economy tests were performed in a temperature controlled environment with a robotic driver. The test revealed that there was more than 3% overall FE variation compared to a reference fluid.
2017-10-08
Technical Paper
2017-01-2390
Hongxue Zhao, Daliang Jing, Yinhui Wang, Shi-jin Shuai, Changle PANG
Abstract In this paper, the impacts of Aromatic and Olefin on the formation of poly-aromatic hydrocarbons (PAHs) in the gasoline direct injection (GDI) engine were experimentally and numerically investigated. The objective of this study is to describe the formation process of the soot precursors including one ring to four ring aromatics (A1-A4). In order to better understand the effects of the fuel properties on the formations of PAHs. Three types of fuels, namely base gasoline, gasoline with higher aromatics content, and gasoline with higher olefin content were experimentally studied. At the same time, these aspects were also numerically investigated in the CHEMKIN code by using premixed laminar flame model and surrogated fuels. The results show that higher aromatics content in gasoline will lead to much higher PAHs formation. Similar trend was also found in the gasoline with higher olefin content.
2017-10-08
Technical Paper
2017-01-2382
Tul Suthiprasert, Sirichai Jirawongnuson, Ekathai Wirojsakunchai, Tanet Aroonsrisopon, Krisada Wannatong, Atsawin Salee
Abstract The diesel dual fuel engine emits CH4 in the exhaust gas. This makes the exhaust gas more difficult to treat comparing to the exhaust gas from the conventional engine since CH4 requires high exhaust temperature to oxidize. In addition, another parameter such as exhaust flow rate, specie concentrations, especially CO, C3H8, and H2O have tremendous impact on Diesel Oxidation Catalyst performance on reducing CH4. This research is aimed to propose a kinetic model based on Langmuir Hinshelwood mechanisms that includes several terms such as CH4, C3H8, CO, O2, and H2O concentrations in order to gain a better understanding on the catalytic reaction and to provide a simulation with an accurate prediction. The model’s kinetic parameters are determined from the experiment by using synthetic gas. The composition of synthetic gas is simulated to be similar to the real exhaust gas from diesel dual fuel engines.
2017-10-08
Technical Paper
2017-01-2186
Lukas Urban, Michael Grill, Sebastian Hann, Michael Bargende
Abstract Engine Knock is a stochastic phenomenon that occurs during the regular combustion of spark ignition (SI) engines and limits its efficiency. Knock is triggered by an autoignition of local “hot spots” in the unburned zone, ahead of the flame front. Regarding chemical kinetics, the temperature and pressure history as well as the knock resistance of the fuel are the main driver for the autoignition process. In this paper, a new knock modeling approach for natural gas blends is presented. It is based on a kinetic fit for the ignition delay times that has been derived from chemical kinetics simulations. The knock model is coupled with an enhanced burn rate model that was modified for Methane-based fuels. The two newly developed models are incorporated in a predictive 0D/1D simulation tool that provides a cost-effective method for the development of natural gas powered SI engines.
2017-10-08
Technical Paper
2017-01-2188
Bruno S. Soriano, Edward S. Richardson, Stephanie Schlatter, Yuri M. Wright
Abstract Dual-fuel combustion is an attractive approach for utilizing alternative fuels such as natural gas in compression-ignition internal combustion engines. In this approach, pilot injection of a more reactive fuel provides a source of ignition for the premixed natural gas/air. The overall performance combines the high efficiency of a compression-ignition engine with the relatively low emissions associated with natural gas. However the combustion phenomena occurring in dual-fuel engines present a challenge for existing turbulent combustion models because, 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 formulation 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
Abstract CFD simulations of reacting flows are fundamental investigation tools used to predict combustion behaviour and pollutants formation in modern internal combustion engines. Focusing on spark-ignited units, most of the flamelet-based combustion models adopted in current simulations use the fuel/air/residual laminar flame propagation speed as a background to predict the turbulent flame speed. This, in turn, is a fundamental requirement to model the effective burn rate. A consolidated approach in engine combustion simulations relies on the adoption of empirical correlations for laminar flame speed, which are derived from fitting of combustion experiments. However, these last are conducted at pressure and temperature ranges largely different from those encountered in engines: for this reason, correlation extrapolation at engine conditions is inevitably accepted. As a consequence, relevant differences between proposed correlations emerge even for the same fuel and conditions.
2017-10-08
Technical Paper
2017-01-2195
Mei Wang, Xianyin Leng, Zhixia He, Shengli Wei, Liang Chen, Yu Jin
Abstract The spark-ignited pre-chamber stratified combustion system is one of the most effective ways of expanding lean-burn ability and improving the performance of a natural gas engine. For these pre-chamber engines, the geometrical structure of orifices between the pre- and main chamber plays a significant role on the gas flow and flame propagation behaviors. The present study aims to investigate the effects of orifice number and diameter on combustion characteristics of a Shengdong T190 natural gas engine through CFD simulation. Various geometrical structures for the pre-chamber orifices were designed, offering variations in the number of orifices (4 to 8), and in the diameter of orifices (1.6mm to 2.9mm). A non-dimensional parameter β was employed to characterize the relative flow area of the orifices in the design. CFD simulations of combustion processes for these designs were carried out using a simplified chemical reaction kinetic mechanism for methane.
2017-10-08
Technical Paper
2017-01-2197
Vignesh Pandian Muthuramalingam, Anders Karlsson
Abstract Owing to increased interest in blended fuels for automotive applications, a great deal of understanding is sought for the behavior of multicomponent fuel sprays. This sets a new requirement on spray model since the volatility of the fuel components in a blend can vary substantially. It calls for careful solution to implement the differential evaporation process concerning thermodynamic equilibrium while maintaining a robust solution. This work presents the Volvo Stochastic Blob and Bubble (VSB2) spray model for multicomponent fuels. A direct numerical method is used to calculate the evaporation of multicomponent fuel droplets. The multicomponent fuel model is implemented into OpenFoam CFD code and the case simulated is a constant volume combustion vessel. The CFD code is used to calculate liquid penetration length for surrogate diesel (n-dodecane)-gasoline (iso-octane) blend and the result is compared with experimental data.
2017-10-08
Technical Paper
2017-01-2191
Yachao Chang, Ming Jia, Yanzhi Zhang, Yaopeng Li, Weiwei Fan, MaoZhao Xie
Abstract Dimethyl ether (DME) attracts increasing attentions in recent years, because it can reduce the carbon monoxide (CO), unburned hydrocarbon (HC), and soot emissions for engines as the transportation fuel or the fuel additive. In this paper, a reduced DME oxidation mechanism is developed using the decoupling methodology. The rate constants of the fuel-related reactions are optimized using the non-dominated sorting genetic algorithm II (NSGA-II) to reproduce the ignition delay times in shock tubes and major species concentrations in jet-stirred reactors (JSR) over low-to-high temperatures. In NSGA-II, the range of the rate constants was considered to ensure the reliability of the optimized mechanism. Moreover, an improved objective function was proposed to maintain the faithfulness of the optimized mechanism to the original reaction mechanism, and a new method was presented to determine the optimal solution from the Pareto front.
2017-10-08
Technical Paper
2017-01-2192
Shenghui Zhong, Zhijun Peng, Yu Li, Hailin Li, Fan Zhang
Abstract A 3-D DNS (Three-Dimensional Direct Numerical Simulation) study with detailed chemical kinetic mechanism of methane has been performed to investigate the characteristics of turbulent premixed oxy-fuel combustion in the condition relevant to Spark Ignition (SI) engines. First, 1-D (one-dimensional) laminar freely propagating premixed flame is examined to show a consistent combustion temperature for different dilution cases, such that 73% H2O and 66% CO2 dilution ratios are adopted in the following 3-D DNS cases. Four 3-D DNS cases with various turbulence intensities are conducted. It is found that dilution agents can reduce the overall flame temperature but with an enhancement of density weighted flame speed. CO2 dilution case shows the lowest flame speed both in turbulent and laminar cases.
2017-10-08
Technical Paper
2017-01-2194
Mateusz Pucilowski, Mehdi Jangi, Sam Shamun, Martin Tuner, Xue-Song Bai
Abstract Heavy-duty direct injection compression ignition (DICI) engine running on methanol is studied at a high compression ratio (CR) of 27. The fuel is injected with a common-rail injector close to the top-dead-center (TDC) with two injection pressures of 800 bar and 1600 bar. Numerical simulations using Reynold Averaged Navier Stokes (RANS), Lagrangian Particle Tracking (LPT), and Well-Stirred-Reactor (WSR) models are employed to investigate local conditions of injection and combustion process to identify the mechanism behind the trend of increasing nitrogen oxides (NOx) emissions at higher injection pressures found in the experiments. It is shown that the numerical simulations successfully replicate the change of ignition delay time and capture variation of NOx emissions.
2017-10-08
Technical Paper
2017-01-2193
Andreas Nygren, Anders Karlsson
Abstract 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
2017-01-2208
Tao Liu, Ziwang Lu, Guangyu Tian
Abstract To further explore the potential of fuel economy for hybrid electric vehicle (HEV), a methodology of demand power optimization is proposed. The fuel consumption depends not only on the EMS, but also on the way to operate vehicle. A control strategy to adjust driver’s demand before power splitting is necessary. To get accurate and reliable control strategy, two aspects are the most important. First, a rigorous and organized modeling approach is a base to describe complicated powertrain system of HEV. The energetic macroscopic representation (EMR) is a graphical synthetic description of electromechanical conversion system based on energy flow. A powertrain architecture of HEV is described explicitly via the EMR. Second, the effectiveness of EMS and the reasonability of driving operations are vital.
2017-10-08
Technical Paper
2017-01-2207
Nobunori Okui
Abstract Next-generation vehicles which include the Electric Vehicles, the Hybrid Electric Vehicles and the Plug-in Hybrid Electric Vehicles are researched and expected to reduce carbon dioxide (CO2) emission in the future. In order to reduce the emissions of the heavy-duty diesel plug-in hybrid electric vehicles (PHEV), it is necessary to provide the high exhaust-gas temperature and to keep the exhaust-gas aftertreatment system effective. The engine starting condition of the PHEV is cold, and the engine start and stop is repeated. And, the engine load of the PHEV is assisted by the electric motor. Therefore, the exhaust-gas aftertreatment system of the PHEV is not able to get the enough high exhaust-gas temperature. And, the warm-up of the exhaust-gas aftertreatment system for the PHEV is spent the long time. So, it is worried about a bad effect on the emission characteristics of the PHEV.
2017-10-08
Technical Paper
2017-01-2224
Paul Freeland, Gareth Jones, Rong-Sheih Chen, Liang-Wei Huang, Marwan El-Kassem, Roland Kaiser
Abstract The paper outlines the fuel consumption benefits available from de-throttling technologies that can help to bring gasoline engine efficiency on a par with that of diesel engines. The paper shows the relative efficiency improvements offered by a fully-variable intake valve lift system in conjunction with wide-range cam phasers, which also incorporate the facility to provide zero valve lift to enable cylinder deactivation. Testbed results recorded with a prototype concept engine show the degree to which early intake valve closing, valve overlap and cylinder deactivation can work together, and the limitations of this synergy at different operating conditions.
2017-10-08
Technical Paper
2017-01-2236
Mateos Kassa, Carrie Hall, Fabien Vidal-Naquet, Thomas Leroy
Abstract In this study, the impact of the intake valve timing on knock propensity is investigated on a dual-fuel engine which leverages a low octane fuel and a high octane fuel to adjust the fuel mixture’s research octane rating (RON) based on operating point. Variations in the intake valve timing have a direct impact on residual gas concentrations due to valve overlap, and also affect the compression pressure and temperature by altering the effective compression ratio (eCR). In this study, it is shown that the fuel RON requirement for a non-knocking condition at a fixed operating point can vary significantly solely due to variations of the intake valve timing. At 2000 rpm and 6 bar IMEP, the fuel RON requirement ranges from 80 to 90 as a function of the intake valve timing, and the valve timing can change the RON requirement from 98 to 104 at 2000 rpm and 14 bar IMEP.
2017-10-08
Technical Paper
2017-01-2235
Ting Liu, Fuyuan Zhang, Yuedong Chao, Zongjie Hu, Liguang Li
Abstract In order to investigate the impacts of recirculated exhaust gas temperature on gasoline engine combustion and emissions, an experimental study has been conducted on a turbocharged PFI gasoline engine. The engine was equipped with a high pressure cooled EGR system, in which different EGR temperatures were realized by using different EGR coolants. The engine ran at 2000 r/min and 3000 r/min, and the BMEP varied from 0.2MPa to 1.0MPa with the step of 0.2MPa. At each case, there were three conditions: 0% EGR, 10% LT-EGR, 10% HT-EGR. The results indicated that LT-EGR had a longer combustion duration compared with HT-EGR. When BMEP was 1.0 MPa, CA50 of HT-EGR advanced about 5oCA. However, CA50 of LT-EGR could still keep steady and in appropriate range, which guaranteed good combustion efficiency. Besides, LT-EGR had lower exhaust gas temperature, which could help to suppress knock. And its lower exhaust gas temperature could reduce heat loss.
2017-10-08
Technical Paper
2017-01-2234
David Vuilleumier, Magnus Sjöberg
Abstract Fundamental engine research is primarily conducted under steady-state conditions, in order to better describe boundary conditions which influence the studied phenomena. However, light-duty automobiles are operated, and tested, under heavily transient conditions. This mismatch between studied conditions and in-use conditions is deemed acceptable due to the fundamental knowledge gained from steady-state experiments. Nonetheless, it is useful to characterize the conditions encountered during transient operation and determine if the governing phenomena are unduly influenced by the differences between steady-state and transient operation, and further, whether transient behavior can be reasonably extrapolated from steady-state behavior. The transient operation mode used in this study consists of 20 fired cycles followed by 80 motored cycles, operating on a continuous basis.
Viewing 1 to 30 of 12085