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Viewing 1 to 30 of 22048
2017-10-13
Technical Paper
2017-01-5017
Ronith Stanly, Gopakumar Parameswaran, R Rajkiran
Abstract Conventionally, influence of injector coking deposits has been studied using accelerated coking methods. For this work we used in-use vehicles fitted with Common Rail Direct injection (CRDi) injectors in “as-is where is” condition with considerable coked injector deposits. They were then cleaned with a commercial fuel system cleaning solution which did not require the removal of injectors; the influence of injector deposits on vehicular performance and spray field were studied. It was observed that the removal of coking deposits resulted in an increase in the peak power of the vehicle, a lower fuel injected quantity and lower fuel injection duration. It was also observed that the fuel system cleaning procedure resulted in better atomization of fuel spray, better uniformity of the multiple spray jets and an increase in the flow rate of the test injectors.
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
2017-01-2371
Hiroki Kambe, Naoto Mizobuchi, Eriko Matsumura
Abstract Diesel Particulate filter (DPF) is installed as after treatment device of exhaust gas in diesel engine, and collects the Particulate Matter (PM). However, as the operation time of engine increases, PM is accumulated in the DPF, resulting in deterioration of PM collection efficiency and increasing in pressure loss. Therefore, Post injection has been attracted attention as DPF regeneration method for burning and removing PM in DPF. However, Post injection causes oil dilution when fuel is injected at the middle to late stage of expansion stroke. Oil dilution are concerned to deteriorate the sliding property of piston and the thermal efficiency. For this reason, it is necessary to elucidate the mechanism and the behavior that spray impinges lubricating oil film. Therefore, in this study, we aimed to construct model of Computational Fluid Dynamics (CFD) that predicts amount of oil dilution which is concern for post injection in diesel engine, with high accuracy.
2017-10-08
Technical Paper
2017-01-2369
Prakash Arunachalam, Martin Tuner, Per Tunestal, Marcus Thern
Abstract Humid air motor (HAM) is an engine operated with humidified inlet charge. System simulations study on HAM showed the waste heat recovery potential over a conventional system. An HAM setup was constructed, to comprehend the potential benefits in real-time, the HAM setup was built around a 13-litre six cylinder Volvo diesel engine. The HAM engine process is explained in detail in this paper. Emission analysis is also performed for all three modes of operation. The experiments were carried out at part load operating point of the engine to understand the effects of humidified charge on combustion, efficiency, and emissions. Experiments were conducted without EGR, with EGR, and with humidified inlet charge. These three modes of operation provided the potential benefits of each system. Exhaust heat was used for partial humidification process. Results show that HAM operation, without compromising on efficiency, reduces NOx and soot significantly over the engine operated without EGR.
2017-10-08
Technical Paper
2017-01-2368
Wenji Song, Weiyong Tang, Bob Chen
Abstract The 4JB1 diesel engine originated from Isuzu has large share in the China light duty truck market. However, the tightened NOx emission target enforced by NS-V legislation compared with NS-IV regulatory standard is very challenging for this engine platform which originally adopted the DOC+POC catalyst layout. Furthermore, combustion characterization of this type engine leads to high soluble organic fraction (SOF) content in engine out particulates, which requires the catalysts in the exhaust after-treatment system (ATS) to deliver high SOF conversion efficiency in order to meet the regulation limit for particulate matters (PM). In this paper, an innovative exhaust catalyst layout with DOC+V-SCR is introduced. The front DOC is specially formulated with optimized PGM (Platinum Group Metal) loading which ensures effective SOF oxidation while keeping sulfuric acid and sulfate generation minimal.
2017-10-08
Technical Paper
2017-01-2367
Ganesan Mahadevan, Sendilvelan Subramanian
Abstract Control of harmful emissions during cold start of the engine has become a challenging task over the years due to the ever increasing stringent emission norms. Positioning the catalytic converter closer to the exhaust manifold is an efficient way of achieving rapid light-off temperature. On the other hand, the resulting higher thermal loading under high-load engine operation may substantially cause thermal degradation and accelerate catalyst ageing. The objective of the present work is to reduce the light-off time of the catalyst and at the same time reduce the thermal degradation and ageing of the catalyst to the minimum possible extent by adopting an approach with Dynamic Catalytic Converter System (DCCS). The emission tests were conducted at the cold start of a 4 cylinder spark ignition engine with DCCS at different positions of the catalyst at no load conditions.
2017-10-08
Technical Paper
2017-01-2365
Murugesa Pandian M, Anand Krishnasamy
Abstract Reactivity controlled compression ignition (RCCI) is one of the most promising low temperature combustion (LTC) strategies to achieve higher thermal efficiencies along with ultra low oxides of nitrogen (NOx) and particulate matter emissions. Small single cylinder diesel engines of air-cooled type are finding increasing applications in the agriculture pump-set and small utility power generation owing to their lower cost and fuel economy advantages. In the present work, a small single cylinder diesel engine is initially operated under conventional combustion mode at rated speed, varying load conditions to establish the base line reference data. Then, the engine is modified to operate under RCCI combustion mode with a newly designed cylinder head to accommodate a high pressure, fully flexible electronically controlled direct diesel fuel injection system, a low pressure gasoline port fuel injection system and an intake air pre heater.
2017-10-08
Technical Paper
2017-01-2364
Jiaqiang Li, Yunshan Ge, Chao He, Jianwei Tan, Zihang Peng, Zidi Li, Wei Chen, Shijie Wang
Abstract Urea SCR technology is the most promising technique to reduce NOx emissions from heavy duty diesel engines. 32.5wt% aqueous urea solution is widely used as ammonia storage species for the urea SCR process. The thermolysis and hydrolysis of urea produces reducing agent ammonia and reduces NOx emissions to nitrogen and water. However, the application of urea SCR technology has many challenges at low temperature conditions, such as deposits formation in the exhaust pipe, lack deNOx performance at low temperature and freezing below -12°C. For preventing deposits formation, aqueous urea solution is hardly injected into exhaust gas stream at temperature below 200°C. The aqueous urea solution used as reducing agent precursor is the main obstacle for achieving high deNOx performances at low temperature conditions. This paper presents a solid SCR technology for control NOx emissions from heavy duty diesel engines.
2017-10-08
Technical Paper
2017-01-2363
Murugesa Pandian M, Anand Krishnasamy
Abstract Advanced low temperature combustion (LTC) modes are most promising to reduce green house gas emissions owing to fuel economy benefits apart from simultaneously reducing oxides of nitrogen (NOx) and particulate matter (PM) emissions from diesel engines. Various LTC strategies have been proposed so far and each of these LTC strategies have their own advantages and limitations interms of precise ignition control, achievable load range and higher unburned emissions. In the present work, a small single cylinder diesel engine is initially operated under conventional combustion mode at rated speed, varying load conditions to establish the base line reference data. Then, the engine is modified to operate under different LTC strategies including Homogenous Charge Compression Ignition (HCCI), Premixed Charge Compression Ignition (PCCI) and Reactivity Controlled Compression Ignition (RCCI).
2017-10-08
Technical Paper
2017-01-2361
David R. Lancaster
Abstract Virtually all developed countries regulate light-duty vehicle emissions and fuel consumption. Those regulations rely on different procedures and driving cycles in testing to different standards in different countries. As a result, it is often very difficult to compare the standards imposed by different countries. This paper utilizes publicly available data to compare the energy requirements of the chassis dynamometer driving cycles in common use throughout the world. It also examines the relative severity of the currently existing light duty vehicle CO2 standards, some of which are mass-based with a targeted fleet average, and some of which are individual vehicle targets based on footprint.
2017-10-08
Technical Paper
2017-01-2393
E. Robert Fanick, Svitlana Kroll
Abstract Semi-volatile organic compounds (SVOC) are a group of compounds in engine exhaust that either form during combustion or are part of the fuel and lubricating oil. Since these compounds occur at very low concentrations in diesel engine exhaust, the methods for sampling, handling, and analyzing these compounds are critical to obtaining good results. An improved dilute exhaust sampling method was used for sampling and analyzing SVOC in engine exhaust, and this method was performed during transient engine operation. A total of 22 different SVOC were measured using a 2012 medium-duty diesel engine. This engine was equipped with a stock diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a selective catalytic reduction (SCR) catalyst in series. Exhaust concentrations for SVOC were compared both with and without exhaust aftertreatment. Concentrations for the engine-out SVOC were significantly higher than with the aftertreatment present.
2017-10-08
Technical Paper
2017-01-2394
Ning Xu, Di-ming Lou, Ji-yao Liu, Piqiang Tan, Zhiyuan Hu
Abstract The range-extended electric transit bus (REEbus) equipped with the auxiliary power unit (APU) using high efficient diesel engine as power source can reduce the cost of power battery and is an ideal transitional powertrain architecture to the pure electric drive. Based on chassis tests of a 12m long REEbus, fuel consumption and emission characteristics during Charge-Sustaining (CS) stage effected by temperature of the REEbus are researched. The APU of REEbus starts to work around just one point with best efficiency and lower emission when the state of charge (SOC) is too low and stop when the SOC is high, which aims to lower fuel consumption. As a result, even during CS stage, the fuel consumption of REEbus is only 22.84 L/100km. Also almost all emissions decrease dramatically and the NOx emission is only 0.68g/km, but the ultrafine-particle number increases owing to better combustion.
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
2017-01-2391
Daisy Thomas, Hu Li, Xin Wang, Bin Song, Yunshan Ge, Wenlin Yu, Karl Ropkins
Abstract The drive characteristics and gaseous emissions of legislated Real Driving Emissions (RDE) test data from 8 different spark ignition vehicles were compared to data from corresponding Worldwide harmonized Light vehicles Test Cycle (WLTC) tests. The effect of the official RDE exclusion of cold start and idling on the RDE test, and the effect of the use of the moving averaging window (MAW) analysis technique, were simultaneously investigated. Specific attention was paid to differences in drive characteristics of the three different driving modes and the effect this had on the distance-based CO2, CO and NOx emission factors for each. The average velocity of the RDE tests was marginally greater than the WLTC tests, while the average acceleration was smaller. The CO2 emission appeared on average 4% lower under the RDE tests compared to the WLTC tests, while the CO was 60% lower.
2017-10-08
Technical Paper
2017-01-2388
Ahmad Khalfan, Gordon Andrews, Hu Li
Abstract The emissions from vehicles in real world driving are of current concern, as they are often higher than on legislated test cycles and this may explain why air quality in cities has not improved in proportion to the reduction in automotive emissions. This has led to the Real Driving Emissions (RDE) legislation in Europe. RDE involves journeys of about 90km with roughly equal proportion of urban, rural and motorway driving. However, air quality exceedances occur in cities with urban congested traffic driving as the main source of the emissions that deteriorate the air quality. Thus, the emissions measured on RDE journeys may not be relevant to air quality in cities. A Temet FTIR and Horiba exhaust flow measurement system was used for the mass emissions measurements in a Euro 4 SI vehicle. A 5km urban journey on a very congested road was undertaken 29 times at various times so that different traffic congestion was encountered.
2017-10-08
Technical Paper
2017-01-2384
Ijhar H. Rusli, Svetlana Aleksandrova, Humberto Medina, Stephen F. Benjamin
Abstract In aftertreatment system design, flow uniformity is of paramount importance as it affects aftertreatment device conversion efficiency and durability. The major trend of downsizing engines using turbochargers means the effect of the turbine residual swirl on the flow needs to be considered. In this paper, this effect has been investigated experimentally and numerically. A swirling flow rig with a moving-block swirl generator was used to generate swirling flow in a sudden expansion diffuser with a wash-coated diesel oxidation catalyst (DOC) downstream. Hot-wire anemometry (HWA) was used to measure the axial and tangential velocities of the swirling flow upstream of the diffuser expansion and the axial velocity downstream the monolith. With no swirl, the flow in the catalyst monolith is highly non-uniform with maximum velocities near the diffuser axis. At high swirl levels, the flow is also highly nonuniform with the highest velocities near the diffuser wall.
2017-10-08
Technical Paper
2017-01-2383
Guoyang Wang, Jun Zhang, Bo Yang, Chuandong Li, Shi-Jin Shuai, Shi Yin, Meng Jian
Abstract Urea selective catalytic reduction (SCR) is a key technology for heavy-duty diesel engines to meet the increasingly stringent nitric oxides (NOx) emission limits of regulations. The urea water solution injection control is critical for urea SCR systems to achieve high NOx conversion efficiency while keeping the ammonia (NH3) slip at a required level. In general, an open loop control strategy is sufficient for SCR systems to satisfy Euro IV and Euro V NOx emission limits. However, for Euro VI emission regulation, advanced control strategy is essential for SCR systems due to its more tightened NOx emission limit and more severe test procedure compared to Euro IV and Euro V. This work proposed an approach to achieve model based closed loop control for SCR systems to meet the Euro VI NOx emission limits. A chemical kinetic model of the SCR catalyst was established and validated to estimate the ammonia storage in the SCR catalyst.
2017-10-08
Technical Paper
2017-01-2381
Kristian Hentelä, Ossi Kaario, Vikram Garaniya, Laurie Goldsworthy, Martti Larmi
In the present study, a new approach for modelling emissions of coke particles or cenospheres from large diesel engines using HFO (Heavy fuel oil) was studied. The model used is based on a multicomponent droplet mass transfer and properties model that uses a continuous thermodynamics approach to model the complex composition of the HFO fuel and the resulting evaporation behavior of the fuel droplets. Cenospheres are modelled as the residue left in the fuel droplets towards the end of the simulation. The mass-transfer and fuel properties models were implemented into a cylinder section model based on the Wärtsilä W20 engine in the CFD-code Star CD v.4.24. Different submodels and corresponding parameters were tuned to match experimental data of cylinder pressures available from Wärtsilä for the studied cases. The results obtained from the present model were compared to experimental results found in the literature.
2017-10-08
Technical Paper
2017-01-2376
Nic Van Vuuren, Phil Armitage
Abstract Selective Catalytic Reduction (SCR) diesel exhaust aftertreatment systems are virtually indispensable to meet NOx emissions limits worldwide. These systems generate the NH3 reductant by injecting aqueous urea solution (AUS-32/AdBlue®/DEF) into the exhaust for the SCR NOx reduction reactions. Understanding the AUS-32 injector spray performance is critical to proper optimization of the SCR system. Specifically, better knowledge is required of the formation of near-nozzle deposits that have been observed on existing underfloor SCR systems. The current work presents in-situ time lapse imaging of an underfloor mounted AUS-32 exhaust-mounted urea dosing unit. The operating conditions under examination are representative of low-load low speed urban driving interspersed with high temperature exposures typical of periodic DPF regeneration.
2017-10-08
Technical Paper
2017-01-2373
Jun Kaniyu, Shogo Sakatani, Eriko Matsumura, Takaaki Kitamura
Abstract Diesel Particulate Filter (DPF) is a very effective aftertreatment device to limit particulate emissions from diesel engines. As the amount of soot collected in the DPF increases, the pressure loss increases. Therefore, DPF regeneration needs to be performed. Injected fuel into the exhaust line upstream of the Diesel Oxidation Catalyst (DOC), hydrocarbons are oxidized on the DOC, which increases the exhaust gas temperature at the DPF inlet. It is also necessary that the injected fuel is completely vaporized before entering the DOC, and uniformly mixed with the exhaust gases in order to make the DOC work efficiency. However, ensuring complete evaporation and an optimum mixture distribution in the exhaust line are challenging. Therefore, it is important that the fuel spray feature is grasped to perform DPF regeneration effectively. The purpose of this study is the constructing a simulation model.
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
2017-01-2182
Xikai Liu, Xingyu Liang, Yonge Wu, Yuesen Wang
Abstract According to the study of the soot emission in the combustion of 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 in combustion process by using CHEMKIN PRO in different pressure of 13.5 atm and 42 atm, initial temperatures of 600k and equivalence ratio of 0.5 and 1.0.Then,compare the simulated results with the experiment data, the mechanisms used in the simulation were Lawrence Livermore National Laboratory (LLNL) detail mechanism and the State Key Laboratory of Engine (SKLE) mechanism.
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
2017-01-2200
Peter Priesching, Mijo Tvrdojevic, Ferry Tap, Casper Meijer
Abstract Turbulent combustion modeling in a RANS or LES context imposes the challenge of closing the chemical reaction rate on the sub-grid level. 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 (TCI - turbulence-chemistry interaction). In this work, an advanced combustion model based on tabulated chemistry is applied for 3D CFD (computational fluid dynamics) modeling of Diesel engine cases. The combustion model is based on the FGM (Flamelet Generated Manifold) 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
2017-01-2207
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
2017-01-2216
Yumin Fu
Abstract This study presents the development of sensor less rough road detection by using frequency analysis of instantaneous crankshaft rotation speed signal. Combustion diagnosis (misfire detection) is enforced by OBD requirement. Eliminating rough road’s effect on misfire detection is critical for getting robust diagnosis result, especially for crankshaft rotation speed based misfire detection. Although some kind of sensor is often used to identify vehicle driving on rough road, sensor less rough road detection method is still attractive for OEM to reduce cost and some approaches have been developed in past years for the aim [1] [2] [3]. This paper presents a new rough road detection approach based on crankshaft rotation speed frequency domain analysis. It firstly collects the signal from vehicle driving with misfire on public road and without misfire on rough road. Fluctuation exists in crankshaft rotation speed under such condition.
2017-10-08
Technical Paper
2017-01-2227
Wei Guan, Vinícius Pedrozo, Hua Zhao, Zhibo Ban, Tiejian Lin
Abstract In order to meet increasingly stringent emissions standards and lower the fuel consumption of heavy-duty (HD) vehicles, significant efforts have been made to develop high efficiency and clean diesel engines and aftertreatment systems. However, a trade-off between the actual engine efficiency and nitrogen oxides (NOx) emission remains to minimize the operational costs. In addition, the conversion efficiency of the diesel aftertreatment system decreases rapidly with lower exhaust gas temperatures (EGT), which occurs at low load operations. Thus, it is necessary to investigate the optimum combustion and engine control strategies that can lower the vehicle’s running costs by maintaining low engine-out NOx emissions while increasing the conversion efficiency of the NOx aftertreament system through higher EGTs.
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
2017-01-2232
Liming Cao, Ho Teng, Ruigang Miao, Xuwei Luo, Tingjun Hu, Xianlong Huang
Abstract The present paper is Part III of an investigation on the influences of the late intake valve closing (LIVC) and the early intake valve closing (EIVC) on the engine fuel consumptions at different loads and speeds. The investigation was conducted with two 1.5L turbo-charged gasoline direct injection (TGDI) engines, one with a low-lift intake cam (the Miller engine) and the other with a high-lift intake cam (the Atkinson engine). This paper focuses on the influence of the intake-valve-closing timing on the fuel economy with and without exhaust gas recirculation (EGR). It was found that the Miller engine had a lower friction than the Atkinson engine; however, the impact of the difference in engine frictions on the fuel economy was mainly for low-speed operations. Across the engine speed range, the Miller engine had longer combustion durations than the Atkinson engine as a result of the impact of EIVC on the cylinder charge motion.
Viewing 1 to 30 of 22048