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Viewing 181 to 210 of 16604
2017-04-11
Journal Article
2017-01-9075
Rami Abousleiman, Osamah Rawashdeh, Romi Boimer
Abstract Growing concerns about the environment, energy dependency, and the unstable fuel prices have increased the sales of electric vehicles. Energy-efficient routing for electric vehicles requires novel algorithmic challenges because traditional routing algorithms are designed for fossil-fueled vehicles. Negative edge costs, battery power and capacity limits, vehicle parameters that are only available at query time, alongside the uncertainty make the task of electric vehicle routing a challenging problem. In this paper, we present a solution to the energy-efficient routing problem for electric vehicles using ant colony optimization. Simulation and real-world test results demonstrate savings in the energy consumption of electric vehicles when driven on the generated routes. Real-world test results revealed more than 9% improvements in the energy consumption of the electric vehicle when driven on the recommended route rather than the routes proposed by Google Maps and MapQuest.
2017-03-28
Technical Paper
2017-01-0686
Mohammed Jaasim Mubarak Ali, Francisco Hernandez Perez, S. Vedharaj, R. Vallinayagam, Robert Dibble, Hong Im
Abstract Pre-ignition in SI engine is a critical issue that needs addressing as it may lead to super knock event. It is widely accepted that pre-ignition event emanates from hot spot(s) that can be anywhere inside the combustion chamber. The location and timing of hotspot is expected to influence the knock intensity from a pre-ignition event. In this study, we study the effect of location and timing of hot spot inside the combustion chamber using numerical simulations. The simulation is performed using a three-dimensional computational fluid dynamics (CFD) code, CONVERGE™. We simulate 3-D engine geometry coupled with chemistry, turbulence and moving structures (valves, piston). G-equation model for flame tracking coupled with multi-zone model is utilized to capture auto-ignition (knock) and solve gas phase kinetics. A parametric study on the effect of hot spot timing and location inside the combustion chamber is performed.
2017-03-28
Technical Paper
2017-01-0682
Yuedong Chao, Haifeng Lu, Zongjie Hu, Jun Deng, Zhijun Wu, Liguang Li, Yuan Shen, Shuang Yuan
Abstract In this paper comparisons were made between the fuel economy improvement between a High Pressure loop (HP) water-cooled Exhaust Gas Recirculation (EGR) system and a Low Pressure loop (LP) water-cooled EGR system. Experiments were implemented on a 1.3-Litre turbocharged PFI gasoline engine in two pars. One was EGR rate as single operating point to compare the different effect of HP- and LP-EGR. The other was mini map from 1500rpm to 3000rpm and BMEP from 2bar to 14bar because of the relative narrow available range of HP-EGR system. In consideration of practical application of EGR system, the coolant used in this experiment was kept almost the same temperature as in real vehicles (88±3°C) instead of underground water temperature, besides a model was built to calculate constant volume ratio (CVR). The results indicated that the effect of HP-EGR was weaker than that of LP-EGR under the same EGR rate, which could be seen from change of combustion parameters.
2017-03-28
Technical Paper
2017-01-0690
Maziar Khosravi, Helmut Ruhland, Thomas Lorenz, Carsten Weber
Abstract The performance of boosted gasoline engines is limited at high loads by knock, stochastic Low Speed Pre-Ignition, and Megaknock. An investigation has been carried out on the occurrence of abnormal combustion and megaknock in a 1.6 L GTDI engine with the aim to determine the causes of such phenomena. A classification of abnormal combustion events and causes is presented in order to facilitate a consistent terminology. The experiments specifically focus on the effects of exhaust residual gas on occurrence of megaknock in multi-cylinder engines. The results showed that while a misfire will not lead to megaknock, a very late combustion in one cycle, in one cylinder may lead to megaknock in the following cycle in the same or adjacent cylinder. Additionally, a recently developed multi-zone model was used to analyze the role of residual gas on auto-ignition.
2017-03-28
Technical Paper
2017-01-0756
Zhenkuo Wu, Christopher Rutland, Zhiyu Han
Abstract Natural gas is a promising alternative fuel for internal combustion engines due to its rich reserves and low price, as well as good physical and chemical properties. Its low carbon structure and high octane number are beneficial for CO2 reduction and knock mitigation, respectively. Diesel and natural gas dual fuel combustion is a viable pathway to utilize natural gas in diesel engines. To achieve high efficiency and low emission combustion in a practical diesel engine over a wide range of operating conditions, understanding the performance responses to engine system parameter variations is needed. The controllability of two combustion strategies, diesel pilot ignition (DPI) and single injection reactivity controlled compression ignition (RCCI), were evaluated using the multi-dimension CFD simulation in this paper.
2017-03-28
Technical Paper
2017-01-0755
Karthik Nithyanandan, Yongli Gao, Han Wu, Chia-Fon Lee, Fushui Liu, Junhao Yan
Abstract Dual-fuel combustion combining a premixed charge of compressed natural gas (CNG) and a pilot injection of diesel fuel offer the potential to reduce diesel fuel consumption and drastically reduce soot emissions. In this study, dual-fuel combustion using methane ignited with a pilot injection of No. 2 diesel fuel, was studied in a single cylinder diesel engine with optical access. Experiments were performed at a CNG substitution rate of 70% CNG (based on energy) over a wide range of equivalence ratios of the premixed charge, as well as different diesel injection strategies (single and double injection). A color high-speed camera was used in order to identify and distinguish between lean-premixed methane combustion and diffusion combustion in dual-fuel combustion. The effect of multiple diesel injections is also investigated optically as a means to enhance flame propagation towards the center of the combustion chamber.
2017-03-28
Technical Paper
2017-01-0758
Yaopeng Li, Ming Jia, Yachao Chang, Guangfu Xu
Abstract Multi-dimensional models coupled with a reduced chemical mechanism were used to investigate the effect of fuel on exergy destruction fraction and sources in a reactivity controlled compression ignition (RCCI) engine. The exergy destruction due to chemical reaction (Deschem) makes the largest contribution to the total exergy destruction. Different from the obvious low temperature heat release (LTHR) behavior in gasoline/diesel RCCI, methanol has a negative effect on the LTHR of diesel, so the exergy destruction accumulation from LTHR to high temperature heat release (HTHR) can be avoided in methanol/diesel RCCI, contributing to the reduction of Deschem. Moreover, the combustion temperature in methanol/diesel RCCI is higher compared to gasoline/diesel RCCI, which is also beneficial to the lower exergy destruction fraction. Therefore, the exergy destruction of methanol/diesel RCCI is lower than that of gasoline/diesel RCCI at the same combustion phasing.
2017-03-28
Technical Paper
2017-01-0759
Rasmus Pettinen, Ossi Kaario, Martti Larmi
Abstract Dual-fuel technology is suggested as a solution for effectively utilizing alternative fuel types in the near future. Charge air mixed methane combined with a compression ignition engine utilizing a small diesel pilot injection seems to form a worthwhile compromise between good engine efficiency and low emission outcome. Problems concerning dual-fuel technology profitableness seems to be related to fully control the combustion in relation to lean conditions. Lean operating conditions solves the problems concerning pumping losses, but brings challenges in controlling the slow heat release of the premixed methane-air mixture. In the present work, a single cylinder ‘free parameter’ diesel engine was adapted for dual-fuel (diesel-methane) usage. A parameter study related to lambda window widening possibilities was carried out.
2017-03-28
Technical Paper
2017-01-0763
Ethan Faghani, Pooyan Kheirkhah, Christopher W.J. Mabson, Gordon McTaggart-Cowan, Patrick Kirchen, Steve Rogak
Abstract High-pressure direct-injection (HPDI) in heavy duty engines allows a natural gas (NG) engine to maintain diesel-like performance while deriving most of its power from NG. A small diesel pilot injection (5-10% of the fuel energy) is used to ignite the direct injected gas jet. The NG burns in a predominantly mixing-controlled combustion mode which can produce particulate matter (PM). Here we study the effect of injection strategies on emissions from a HPDI engine in two parts. Part-I investigated the effect of late post injection (LPI); the current paper (Part-II) reports on the effects of slightly premixed combustion (SPC) on emission and engine performance. In SPC operation, the diesel injection is delayed, allowing more premixing of the natural gas prior to ignition. PM reductions and tradeoffs involved with gas slightly premixed combustion was investigated in a single-cylinder version of a 6-cylinder, 15 liter HPDI engine.
2017-03-28
Technical Paper
2017-01-0764
Gabriele Di Blasio, Giacomo Belgiorno, Carlo Beatrice
Abstract The paper reports the results of an experimental campaign aimed to assess the impact of the compression ratio (CR) variation on the performance and pollutant emissions, including the particle size spectrum, of a single cylinder research engine (SCE), representatives of the engine architectures for automotive application, operated in dual-fuel methane-diesel mode. Three pistons with different bowl volumes corresponding to CR values of 16.5, 15.5 and 14.5 were adopted for the whole test campaign. The injection strategy was based on two injection pulses per cycle, as conventionally employed for diesel engines. The test methodology per each CR included the optimization of both 1st injection pulse quantity and intake air mass flow rate in order to lower as much as possible the unburned methane emissions (MHC).
2017-03-28
Technical Paper
2017-01-0769
Pierpaolo Napolitano, Chiara Guido, Carlo Beatrice, Nicola Del Giacomo
Abstract An increasing interest in the use of natural gas in CI engines is currently taking place, due to several reasons: it is cheaper than conventional Diesel fuel, permits a significant reduction of carbon dioxide and is intrinsically clean, being much less prone to soot formation. In this respect, the Dual Fuel concept has already proven to be a viable solution, industrially implemented for several applications in the heavy duty engines category. An experimental research activity was devoted to the analysis of the potentiality offered by the application of a Dual Fuel Diesel-CNG configuration on a light duty 2L Euro 5 automotive diesel engine, equipped with an advanced control system of the combustion. The experimental campaign foresaw to test the engine in dynamic and steady state conditions, comparing engine performance and emissions in conventional Diesel and Dual Fuel combustion modes.
2017-03-28
Technical Paper
2017-01-0776
Ulrich Kramer, Thomas Lorenz, Christian Hofmann, Helmut Ruhland, Rolf Klein, Carsten Weber
Abstract A fundamental requirement for natural gas (NG) and renewable methane (e.g. bio-methane or power-to-gas methane) as automotive fuel is reliable knock resistance; to enable optimization of dedicated NG engines with high compression ratio and high turbocharger boost (which enables considerable engine downsizing factors). In order to describe the knock resistance of NG, the Methane Number (MN) has been introduced. The lowest MN which generally can be found in any NG is 65, and the vast majority of NG (~ 99.8%) is delivered with a MN above 70. The MN of bio-methane and power-to-gas methane is usually far above 80. Thus, from an automotive point of view any methane fuel should at least provide a minimum Methane Number of 70 at any point of sale. But the European draft standard describing the automotive CNG fuel quality so far proposes a minimum MN limit of 65.
2017-03-28
Technical Paper
2017-01-0774
Ethan Faghani, Pooyan Kheirkhah, Christopher W.J. Mabson, Gordon McTaggart-Cowan, Patrick Kirchen, Steve Rogak
Abstract High-pressure direct-injection (HPDI) in heavy duty engines allows a natural gas (NG) engine to maintain diesel-like performance while deriving most of its power from NG. A small diesel pilot injection (5-10% of the fuel energy) is used to ignite the direct injected gas jet. The NG burns in a predominantly non-premixed combustion mode which can produce particulate matter (PM). Here we study the effect of injection strategies on emissions from a HPDI engine in two parts. Part-I will investigates the effect of late post injection (LPI) and Part II will study the effect of slightly premixed combustion (SPC) on emission and engine performance. PM reductions and tradeoffs involved with gas late post-injections (LPI) was investigated in a single-cylinder version of a 6-cylinder,15 liter HPDI engine. The post injection contains 10-25% of total fuel mass, and occurs after the main combustion event.
2017-03-28
Technical Paper
2017-01-0720
Omar Ramadan, Luc Menard, David Gardiner, Aaron Wilcox, Gary Webster
Abstract This paper is a continuation of work previously discussed in SAE 2014-01-0179 [1] and SAE 2015-01-0805 [2], which was intended to improve the capability and precision of the Ignition Quality Tester (IQT™) and associated ASTM D6890 [3]/CEN EN 15195 [4]/EI IP 498 [5] Test Methods. The results presented in those two papers indicated how the new generation of IQT™ with the TALM Precision Package upgrade can markedly improve the precision of the ASTM D6890, CEN EN 15195 and EI IP 498 Derived Cetane Number (DCN) test methods. This paper will evaluate the performance of the upgraded instruments over the past 21 months of their participation in ASTM’s National Fuel Exchange Group (NEG) diesel fuel exchange program.
2017-03-28
Technical Paper
2017-01-0726
Muhammad Waqas, Nimal Naser, Mani Sarathy, Jeroen Feijs, Kai Morganti, Gustav Nyrenstedt, Bengt Johansson
Abstract Gasoline-ethanol-methanol (GEM) blends, with constant stoichiometric air-to-fuel ratio (iso-stoichiometric blending rule) and equivalent to binary gasoline-ethanol blends (E2, E5, E10 and E15 in % vol.), were defined to investigate the effect of methanol and combined mixtures of ethanol and methanol when blended with three FACE (Fuels for Advanced Combustion Engines) Gasolines, I, J and A corresponding to RON 70.2, 73.8 and 83.9, respectively, and their corresponding Primary Reference Fuels (PRFs). A Cooperative Fuel Research (CFR) engine was used under Spark Ignition and Homogeneous Charge Compression Ignited modes. An ignition quality tester was utilized in the Compression Ignition mode. One of the promising properties of GEM blends, which are derived using the iso-stoichiometric blending rule, is that they maintain a constant octane number, which has led to the introduction of methanol as a drop-in fuel to supplement bio-derived ethanol.
2017-03-28
Technical Paper
2017-01-0727
Ida Truedsson, Christine Rousselle, Fabrice Foucher
Abstract The transportation sector adds to the greenhouse gas emissions worldwide. One way to decrease this impact from transportation is by using renewable fuels. Ethanol is a readily available blend component which can be produced from bio blend­stock, currently used blended with gasoline from low to high concentrations. This study focuses on a high octane (RON=97) gasoline blended with 0, 20, and 50, volume % of ethanol, respectively. The high ethanol blended gasoline was used in a light duty engine originally designed for diesel combustion. Due to the high octane rating and high ignition resistance of the fuel it required high intake temperatures of 443 K and higher to achieve stable combustion in in homogeneously charged compression ignition (HCCI) combustion operation at low load. To enable combustion with lower intake temperatures more commonly used in commercial vehicles, ozone was injected with the intake air as an ignition improver.
2017-03-28
Technical Paper
2017-01-0733
Mario Martins, Ivanir Fischer, Franciel Gusberti, Rafael Sari, Macklini Dalla Nora
Abstract Ethanol with high levels of hydration is a low cost fuel that offers the potential to replace fossil fuels and contribute to lower carbon dioxide (CO2) emissions. However, it presents several ignition challenges depending on the hydration level and ambient temperature. Advanced combustion concepts such as homogeneous charge compression ignition (HCCI) have shown to be very tolerant to the water content in the fuel due to their non-flame propagating nature. Moreover, HCCI tends to increase engine efficiency while reducing oxides of nitrogen (NOx) emissions. In this sense, the present research demonstrates the operation of a 3-cylinder power generator engine in which two cylinders operate on conventional diesel combustion (CDC) and provide recycled exhaust gas (EGR) for the last cylinder running on wet ethanol HCCI combustion. At low engine loads the cylinders operating on CDC provide high oxygen content EGR for the dedicated HCCI cylinder.
2017-03-28
Technical Paper
2017-01-0734
Eshan Singh, Muhammad Waqas, Bengt Johansson, Mani Sarathy
Abstract The blending of ethanol with primary reference fuel (PRF) mixtures comprising n-heptane and iso-octane is known to exhibit a non-linear octane response; however, the underlying chemistry and intermolecular interactions are poorly understood. Well-designed experiments and numerical simulations are required to understand these blending effects and the chemical kinetic phenomenon responsible for them. To this end, HCCI engine experiments were previously performed at four different conditions of intake temperature and engine speed for various PRF/ethanol mixtures. Transfer functions were developed in the HCCI engine to relate PRF mixture composition to autoignition tendency at various compression ratios. The HCCI blending octane number (BON) was determined for mixtures of 2-20 vol % ethanol with PRF70. In the present work, the experimental conditions were considered to perform zero-dimensional HCCI engine simulations with detailed chemical kinetics for ethanol/PRF blends.
2017-03-28
Technical Paper
2017-01-0738
Akhilendra Pratap Singh, Avinash Kumar Agarwal
Abstract Premixed charge compression ignition (PCCI) combustion is an advanced combustion technique, which has the potential to be operated by alternative fuels such as alcohols. PCCI combustion emits lower oxides of nitrogen (NOx) and particulate matter (PM) and results thermal efficiency similar to conventional compression ignition (CI) engines. Due to extremely high heat release rate (HRR), PCCI combustion cannot be used at higher engine loads, which make it difficult to be employed in production grade engines. This study focused on development of an advanced combustion engine, which can operate in both combustion modes such as CI combustion as well as PCCI combustion mode. This Hybrid combustion system was controlled by an open engine control unit (ECU), which varied the fuel injection parameters for mode switching between CI and PCCI combustion modes.
2017-03-28
Technical Paper
2017-01-0740
Yu Zhang, Yuanjiang Pei, Nayan Engineer, Kukwon Cho, David Cleary
Abstract The current study utilized 3-D computational fluid dynamics (CFD) combustion analysis to guide the development of a viable full load range combustion strategy in a light-duty gasoline compression ignition (GCI) engine. A higher reactivity gasoline that has a research octane number (RON) of 70 was used for the combustion strategy development. The engine has a geometric compression ratio of 14.5 with a piston bowl designed to accommodate different combustion strategies and injector spray patterns. Detailed combustion optimization was focused on 6 and 18 bar gross indicated mean effective pressure (IMEPg) at 1500 rpm through a Design of Experiments approach. Two different strategies were investigated: (a) a late triggering fuel injection with a wide spray angle (combustion strategy #1); and (b) an early triggering fuel injection with a narrow spray angle (combustion strategy #2).
2017-03-28
Technical Paper
2017-01-1702
Piyush Aggarwal, Bo Chen, Jason Harper
Abstract The increased market share of electric vehicles and renewable energy resources have raised concerns about their impact on the current electrical distribution grid. To achieve sustainable and stable power distribution, a lot of effort has been made to implement smart grids. This paper addresses Demand Response (DR) load control in a smart grid using Internet of Things (IoT) technology. A smart grid is a networked electrical grid which includes a variety of components and sub-systems, including renewable energy resources, controllable loads, smart meters, and automation devices. An IoT approach is a good fit for the control and energy management of smart grids. Although there are various commercial systems available for smart grid control, the systems based on open sources are limited. In this study, we adopt an open source development platform named Node-RED to integrate DR capabilities in a smart grid for DR load control. The DR system employs the OpenADR standard.
2017-03-28
Technical Paper
2017-01-1701
Sagar Mody, Thomas Steffen
Abstract The goal of grid friendly charging is to avoid putting additional load on the electricity grid when it is heavily loaded already, and to reduce the cost of charging to the consumer. In a smart metering system, Day Ahead tariff (DA) prices are announced in advance for the next day. This information can be used for a simple optimization control, to select to charge at cheapest times. However, the balance of supply and demand is not fully known in advance and the Real-Time Prices (RTP) are therefore likely to be different at times. There is always a risk of a sudden price change, hence adding a stochastic element to the optimization in turn requiring dynamic control to achieve optimal time selection. A stochastic dynamic program (SDP) controller which takes this problem into account has been made and proven by simulation in a previous paper.
2017-03-28
Technical Paper
2017-01-1700
Rebekah L. Houser, Willett Kempton, Rodney McGee, Fouad Kiamilev, Nick Waite
Abstract Electric vehicles (EVs) hold the potential to greatly shape the way the electric power grid functions. As a load, EVs can be managed to prevent overloads on the electric power system. EVs with bidirectional power flow (V2G) can provide a wide range of services, including load balancing, and can be used to increase integration of renewable resources into electric power markets. Realizing the potential of EVs requires more advanced communication than the technology that is in wide use. Common charging standards do not include a means for an EV to send key vehicle characteristics such as maximum charge rate or battery capacity to a charging station and thus to the grid.
2017-03-28
Technical Paper
2017-01-1731
Manida Tongroon, Amornpoth Suebwong, Mongkont Kananont, Jirasak Aunchaisri, Nuwong Chollacoop
Abstract Derived from palm Fatty Acid Methyl Ester (FAME), high quality biodiesel called H-FAME has been introduced in order to increase its percentage blended with diesel. Due to monoenen-rich FAME by partial hydrogenation process, H-FAME is superior oxidation and thermal stability. In the current study, the effects of 20 percent of high quality biodiesel blended with diesel (B20) on the compatibility of polymeric engine parts have been investigated by means of the immersion test. Pure diesel has also test as the reference. Following SAE J1748 in conjunction with ASTM D471, selected commercial engine parts such as fuel hose and tank were immersed in the test fuels. In addition, Viton fluoroelastomers, neoprene and nitrile butadiene rubber (NBR) were also soaked for comparison. Apparent percent weight increase was used to indicate the change of the engine parts after exposed to the test fuels.
2017-03-28
Technical Paper
2017-01-0382
Oscar Hernandez Cervantes, Antonio Espiritu Santo Rincon
Abstract The development of an automatic control system for a towing dynamometer used for testing is described in this paper. The process involved the deployment of new power electronics circuit boards, a TELMA retarder, instrumentation and a human machine interface (HMI) achieved through an open source platform. The purpose of this platform is to have a low cost system that allows further function development, data acquisition and communication with other devices. This system is intended as a novel solution that will allow closed loop and automated tests integrated with PCM data for engine calibration. It is projected to be part of a flexible calibration system with direct communication to the interfaces used during development (ATI, ETAS), which will be used to achieve lean test and development schedules.
2017-03-28
Technical Paper
2017-01-0654
Haiqiao Wei, Dengquan Feng, Mingzhang pan, JiaYing PAN
Abstract Combustion characteristics of neat 2-methylfuran (MF), 10% and 20% volumetric fraction 2-methylfuran gasoline blends were experimentally investigated in a single cylinder spark ignition engine, and the results were benchmarked against that of the research on octane number 97 neat gasoline. The investigation focused on the performance of cyclic variation of MF and its blends, and the effects of spark ignition timing, compression ratio, and exhaust gas recirculation (EGR) were studied. Experiments were conducted at the engine speed of 1500 rpm, and loads between 7 and 11 bar indicated mean effective pressure (IMEP) with using stoichiometric air-fuel ratio mixture. Index of the coefficient of variation of IMEP (COVIMEP) was used to evaluate the combustion stability of the tested fuels. The results show that neat MF and MF gasoline blended fuels have superior combustion stability compared with gasoline.
2017-03-28
Technical Paper
2017-01-0661
Michael Pamminger, James Sevik, Riccardo Scarcelli, Thomas Wallner, Carrie Hall
Abstract Natural Gas (NG) is an alternative fuel which has attracted a lot of attention recently, in particular in the US due to shale gas availability. The higher hydrogen-to-carbon (H/C) ratio, compared to gasoline, allows for decreasing carbon dioxide emissions throughout the entire engine map. Furthermore, the high knock resistance of NG allows increasing the efficiency at high engine loads compared to fuels with lower knock resistance. NG direct injection (DI) allows for fuel to be added after intake valve closing (IVC) resulting in an increase in power density compared to an injection before IVC. Steady-state engine tests were performed on a single-cylinder research engine equipped with gasoline (E10) port-fuel injection (PFI) and NG DI to allow for in-cylinder blending of both fuels. Knock investigations were performed at two discrete compression ratios (CR), 10.5 and 12.5.
2017-03-28
Technical Paper
2017-01-0655
Mohammadmohsen Moslemin Koupaie, Alasdair Cairns, Hassan vafamehr, Thompson Lanzanova
Abstract This work was concerned with study of the in-cylinder flow field and flame development in a spark ignition research engine equipped with Bowditch piston optical access. High-speed natural light (chemiluminescence) imaging and simultaneous in-cylinder pressure data measurement and analysis were used to understand the fundamentals of flame propagation for a variety of ethanol fuels blended with either gasoline or iso-octane. PIV was undertaken on the same engine in a motoring operation at a horizontal imaging plane close to TDC (10 mm below the fire face) throughout the compression stroke (30°,40°,90° and 180°bTDC) for a low load engine operating condition at 1500rpm/0.5 bar inlet plenum pressure. Up to 1500 cycles were considered to determine the ensemble average flow-field and turbulent kinetic energy. Finally, comparisons were made between the flame and flow experiments to understand the apparent interactions.
2017-03-28
Technical Paper
2017-01-0664
Mohd Asif, Karl Giles, Andrew Lewis, Sam Akehurst, Niall Turner
Abstract The causes of engine knock are well understood but it is important to be able to relate these causes to the effects of controllable engine parameters. This study attempts to quantify the effects of a portion of the available engine parameters on the knock behavior of a 60% downsized, DISI engine running at approximately 23 bar BMEP. The engines response to three levels of coolant flow rate, coolant temperature and exhaust back pressure were investigated independently. Within the tested ranges, very little change in the knock limited spark advance (KLSA) was observed. The effects of valve timing on scavenge flow and blow through (the flow of fresh air straight into the exhaust system during the valve overlap period) were investigated at two conditions; at fixed inlet/exhaust manifold pressures, and at fixed engine torque. For both conditions, a matrix of 8 intake/exhaust cam combinations was tested, resulting in a wide range of valve overlap conditions (from 37 to -53°CA).
2017-03-28
Technical Paper
2017-01-0665
Hassan vafamehr, Alasdair Cairns, Mohammadmohsen Moslemin Koupaie
Abstract The experimental work was concerned with improving understanding of the competing effects of the latent heat of vaporization and auto-ignition delay times of different ethanol blended fuels during heaving knocking combustion. The unique single cylinder SI engine employed included full bore overhead optical access capable of withstanding unusually high in-cylinder pressures. Heavy knock was deliberately induced under moderate loads using inlet air heating and a primary reference fuel blend of reduced octane rating. High-speed chemiluminescence imaging and simultaneous in-cylinder pressure data measurement were used to evaluate the combustion events. Under normal operation the engine was operated under port fuel injection with a stoichiometric air-fuel mixture. Multiple centered auto-ignition events were regularly observed, with knock intensities of up to ~40bar. Additional excess fuel of varied blend was then introduced directly into the end-gas in short transient bursts.
Viewing 181 to 210 of 16604