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2017-03-28
Technical Paper
2017-01-0768
Sasikumar Nandagopal, Senthil Kumar Masimalai, Arul Selvan Subramaniyan, JaiKumar Mayakrishnan
Waste utilization is found to be challenging task all around the globe. Converting waste into useful form energy was found as a significant landmark in meeting the demand of world energy requirement. Thus an attempt was made in this study to make use of Waste Cooking Oil (WCO) which degrades both the environment and human health as fuel to operate compression ignition engine and investigate its performance, emission and combustion behavior. One time used cooking oil was collected from the hostel mess of author institution. In the first phase of the study, single cylinder water cooled diesel engine was developed as test engine and operated in a single mode with neat diesel and waste cooking oil as fuel. Test engine was operated under various load condition and the readings were observed. Same engine was modified in the second phase of the work to operate in duel fuel mode with a low reactive fuel like ethanol as primary fuel.
2017-03-28
Technical Paper
2017-01-0764
Gabriele Di Blasio, Giacomo Belgiorno, Carlo Beatrice
The paper reports the results of a wide experimental campaign aimed to assess the effects of the geometric compression ratio variation on the performance of light-duty diesel engines operated in dual-fuel NG-diesel mode in terms of fuel consumption, NVH and pollutant emissions. The single-cylinder research engine employed in the experimental campaign had a combustion system is representatives of a 2L automotive diesel engine for passenger cars. The test methodology was defined in order to analyse carefully the effects of the compression ratio, injection parameters and air throttling on the global performances and emissions, also in terms of emitted carbonaceous particles. Three pistons with different bowl volumes corresponding to compression ratio (CR) values of 16.5, 15.5 and 14.5 were selected for the whole test campaign.
2017-03-28
Technical Paper
2017-01-0769
Pierpaolo Napolitano, Chiara Guido, Carlo Beatrice, Nicola Del Giacomo
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 for carbon dioxide and is intrinsically cleaner, 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 high 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 test 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
2017-01-0766
Gary D. Neely, Radu Florea, Jason Miwa, Zainal Abidin
Although low diesel fuel prices have reduced the appeal of natural gas (NG) engines recently, the CO2 advantage and low NOX and PM potential of NG makes it well-suited for meeting future greenhouse gas (GHG) and potential lower NOX regulations for on-road medium and heavy-duty engines. However, traditional NG fueling strategies and/or poor air/fuel ratio control can result in significant levels of tailpipe methane (CH4) emissions which offset the CO2 advantage due to the high global warming potential of CH4. To address this issue, the unique co-direct injection capability of the Westport HPDI fuel system was leveraged to obtain a partially-premixed fuel charge by injecting NG during the compression stroke followed by diesel injection for ignition timing control. This combustion strategy, referred to as DI2, was shown to improve the brake thermal and combustion efficiencies over equivalent fumigated dual-fuel combustion modes in a previous publication.
2017-03-28
Technical Paper
2017-01-0762
Xiaoye Han, Prasad Divekar, Meiping Wang, Ming Zheng, Jimi Tjong, William De Ojeda
This work targets to implement heat release shaping control for improving the ethanol-diesel combustion performance by utilizing a dual-chamber piston bowl design. Unlike the conventional diesel diffusion combustion, new combustion strategies (e.g. dual-fuel combustion) tend to achieve clean combustion by burning a (partially) premixed cylinder charge. However, the rapid heat release from premixed combustion can result in excessive combustion noise and/or high pressure rise rates, which is one of the major barriers preventing these advanced combustion strategies to be fully applied over the entire engine operation map. In order to avoid the fast heat release, an innovative piston bowl design, which physically divides the combustion chamber into a central zone and a peripheral zone near the top dead center, is employed to assist the control of the ethanol-diesel combustion process via heat release shaping.
2017-03-28
Technical Paper
2017-01-0771
Prasad Divekar, Xiaoye Han, Qingyuan Tan, Usman Asad, Tadanori Yanai, Xiang Chen, Jimi Tjong, Ming Zheng
Diesel engines suffer from the oxides of nitrogen (NOx) versus smoke trade-off, wherein the application of EGR for NOx reduction often results in an increase in the smoke emissions. By implementing the ethanol-diesel dual-fuel combustion, the smoke penalty associated with the use of EGR can be suppressed when high ethanol fractions are used. However, at low load levels, the increased carbon monoxide (CO) and unburnt hydrocarbon (HC) emissions contribute to a large reduction in the thermal efficiency in the dual-fuel mode. In this work, tests are conducted on a high compression ratio, single cylinder dual-fuel engine, that incorporates the direct-injection of diesel and port-injection of ethanol. Engine load levels are identified, at which, diesel combustion is more efficient than the dual-fuel combustion while attaining low NOx and smoke emissions.
2017-03-28
Technical Paper
2017-01-0761
Christopher W. Gross, Rolf Reitz
In an attempt to increase efficiency and lower critical and highly regulated emissions (i.e., NOx, PM and CO2) many advanced combustion strategies have been investigated. Most of the current strategies fall into the category of low temperature combustion (LTC), which allow emissions mandates to be met in-cylinder along with anticipated reduction in cost and complexity. These strategies, such as homogeneous charge compression ignition (HCCI), premixed charge compression ignition (PCCI), partially premixed combustion (PPC) and reactivity controlled compression ignition (RCCI), use early injection timings, resulting in a highly lean charge with increased specific heat ratios to improve thermal efficiency and reduce PM emissions. Lower combustion temperatures also avoid the activation of NOx formation reactions.
2017-03-28
Technical Paper
2017-01-0653
Francesco Catapano, Silvana Di Iorio, Ludovica Luise, Paolo Sementa, Bianca Maria Vaglieco
Ethanol is one of the most suitable alternative fuel for spark-ignition (SI) engines. Its properties such as the higher evaporation heat and octane number as well as the larger oxygen content allow to obtain positive effect on engine performance and on particle formation and emissions. This paper aims to analyze the effect of different methods of ethanol fueling on in-cylinder soot formation and exhaust emissions in a small displacement spark ignition engine. The engine was fueled with gasoline and ethanol. In particular, the ethanol was both blended with gasoline (E30) and dual fueled (EDF). In this latter case, ethanol was direct injected and gasoline was injected into the intake duct. For both the injection configurations, the same percentage of ethanol was supplied: 30%v/v ethanol in gasoline. The GPFI and GDI configurations were also performed as base case. The experimental investigation was carried out in 4-stroke small single cylinder engine.
2017-03-28
Technical Paper
2017-01-0759
Rasmus Pettinen, Ossi Kaario, Martti Larmi
Unstable oil markets combined with the alarming statistics of continuously growing emission problems causes anxiety among many nations. The greatest dilemma lies in the answer about how to rationally overcome the dependency of fossil based energy sources. The truth seems to be found on utilizing renewable energy generating low emissions. Methane is suggested as one of the worthwhile solutions for substituting crude-oil based fuels. Methane as a fuel combined with modern engine technology seems to open possibilities solving the above mentioned problems. Charge air mixed methane combined with a compression ignition engine utilizing a small diesel pilot injection seems to form a profitable 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.
2017-03-28
Technical Paper
2017-01-0756
Zhenkuo Wu, Christopher Rutland, Zhiyu Han
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 CO¬¬2 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
2017-01-0843
Jose Pastor, Jose M Garcia-Oliver, Antonio Garcia, Varun Reddy Nareddy
Recent researches have shown that the use of highly premixed dual fuel combustion reduces pollutant emissions and fuel consumption in CI engines. The most common strategy for dual fueling is to use two injection systems. Port fuel injection for low reactivity fuel and DI for high reactivity fuel. This strategy implies some severe shortcomings for its real implementation in passenger cars such as the use of two fuel tanks. In this sense, the use of a single injection system for dual fueling could solve this drawback trying to maintain pollutant and efficiency benefits. Nonetheless, when single injection system is used, the spray characteristics become an essential issue. In this work the fundamental characteristics of dual-fuel sprays with a single injection system under evaporating engine-like conditions are presented.
2017-03-28
Technical Paper
2017-01-0767
Jayant Kumar Arora, Mahdi Shahbakhti
Real-time control of Reactivity Controlled Compression Ignition (RCCI) during engine load and speed transient operation is challenging, since RCCI combustion phasing depends on fuel reactivity gradients and nonlinear thermo-kinetic reactions. This paper designs and implements a real-time closed-loop combustion controller to maintain an optimum combustion phasing during RCCI engine transient operation. New algorithms for real-time In-cylinder pressure analysis and combustion phasing calculations are developed and embedded on a Field Programmable Gate Array (FPGA) to compute RCCI combustion and performance metrics on cycle-by-cycle basis. This cycle-by-cycle data is then used as a feedback to the combustion controller, which is implemented on a real-time processor.
2017-03-28
Technical Paper
2017-01-0760
Menghan Li, Xiangyu Meng, Jie HOU, Suya Gao, Chia-Fon Lee, Guoxiang Li
Butanol, which is a renewable biofuel, has been regarded as a promising alternative fuel for internal combustion engines. When blended with diesel and applied to pilot ignited natural gas engines, butanol has the capability to achieve low soot emissions without sacrifice on thermal efficiency. However, high blend ratio of butanol is limited by its longer ignition delay caused by the higher latent heat and lower octane number, which restricts the further reduction of soot emissions. In this paper, the potential of increasing butanol blend ratio by adding hot EGR is investigated. 3D CFD model based on a detailed kinetic mechanism is built and validated by experimental results of natural gas engine ignited by Diesel-Butanol blends. The effects of hot EGR is then revealed by the simulation results of the combustion process, heat release traces and also the emissions under different diesel-butanol blend ratios.
2017-03-28
Technical Paper
2017-01-0757
Jeffrey Hwang, Xuesong Li, William Northrop
Many dual fuel technologies have been proposed for diesel engines. Implementing dual fuel modes can lead to emissions reductions or increased efficiency through using partially premixed combustion and fuel reactivity control. All dual fuel systems have the practical disadvantage that a secondary fuel storage and delivery system must be included. Reforming the primary diesel to a less reactive vaporized fuel on-board has potential to overcome this key disadvantage. Most previous research regarding on-board fuel reforming has been focused on producing significant quantities of hydrogen. However, only partially reforming the primary fuel is sufficient to vaporize and create a less volatile fuel that can be fumigated into the engine intake. At lower conversion efficiency and higher equivalence ratio, reforming reactors retain higher percentage of the inlet fuel’s heating value thus allowing for greater overall engine system efficiency.
2017-03-28
Technical Paper
2017-01-0772
ShyamSundar Pasunurthi, Ravichandra Jupudi, Sameera Wijeyakulasuriya, Sreenivasa Rao Gubba, Hong Im, Mohammed Jaasim Mubarak Ali, Roy Primus, Adam Klingbeil, Charles Finney
The standard capability of engine experimental studies is that ensemble averaged quantities like in-cylinder pressure and emissions are reported and the cycle to cycle variation (CCV) of indicated mean effective pressure (IMEP) is captured from many consecutive combustion cycles for each test condition. However, obtaining 3D spatial distribution of all the relevant quantities from such experiments is a challenging task. Computational Fluid Dynamics (CFD) simulations of engine flow and combustion can be used effectively to visualize such 3D spatial distributions. A dual fuel engine is considered in the current study, with port injected natural gas (NG) and direct injected diesel pilot for ignition. Multiple 3D CFD simulations are performed in series like in the experiments to investigate the potential of high fidelity RANS simulations coupled with detailed chemistry, to accurately predict the CCV. Measured valve lift profiles are used to specify the valve movements in the simulations.
2017-03-28
Technical Paper
2017-01-0770
Tongyang Gao, Shui Yu, Hua Zhu, Tie Li, Jimi Tjong, Graham Reader, Ming Zheng
The combustion of dual-fuel engines usually uses a pilot flame to burn out a background fuel inside a cylinder of high compression. The background fuel can be either a gaseous fuel or a volatile liquid fuel, commonly with low reactivity to prevent the premature combustion and engine knocking; whereas the pilot flame is normally set off with the direct injection of a liquid fuel of adequate reactivity that is suitable for deterministic auto-ignition under a high compression ratio. In this work, the directly injected butanol is used to generate the pilot flame, while the intake port injected ethanol or butanol is employed as the background fuel. Compared with the conventional diesel-only combustion, dual-fuel operations not only broader the fuel applicability, but also enhance the potential for clean combustion, in high efficiency engines. The amount of the background fuel and the scheduling of fuel direct injection are investigated through extensive laboratory experiments.
2017-03-28
Technical Paper
2017-01-0755
Karthik Nithyanandan, Yongli Gao, Han Wu, Chia-Fon Lee, Fushui Liu, Junhao Yan
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
2017-01-1281
Rajesh Kumar, Olivier Laget, Guillaume Pilla, Guillaume Bourhis, Roland Dauphin, Loic de Francqueville, Jean-Pascal Solari
Reduction of CO2 emissions is becoming one of the great challenges for future gasoline engines. The aim of the current research program (OOD: Octane On Demand) is to use the octane number as a tuning parameter to simultaneously make the engine more efficient and reduce CO2 emissions. The idea is to prevent knock occurrence by adapting the fuel RON injected in the combustion chamber. Thus, the engine cycle efficiency is increased by keeping combustion phasing at its optimum. This is achieved by a dual fuel injection strategy, involving a low-RON base fuel (Naphtha or Low RON cost effective fuel) and a high-RON octane booster (ethanol). The ratio of fuel quantity on each injector is adapted at each engine cycle to fit the RON requirement as a function of engine operating conditions. A first part of the project, described in SAE paper 2016-01-2164, was dedicated to the understanding of mixture preparation resulting from different dual-fuel injection strategies.
2017-03-28
Technical Paper
2017-01-0568
Valentina Fraioli, Carlo Beatrice, Gabriele Di Blasio, Giacomo Belgiorno, Marianna Migliaccio
Abstract The adoption of gaseous fuels for Light Duty (LD) engines is considered a promising solution to efficiently reduce greenhouse gases emissions and diversify fuels supplies, while keeping pollutants production within the limits. In this respect, the Dual Fuel (DF) concept has already proven to be, generally speaking, a viable solution, industrially implemented for several applications in the Heavy-Duty (HD) engines category. Despite this, some issues still require a technological solution, preventing the commercialization of DF engines in wider automotive fields, including the release of high amounts of unburned species, possibility of engine knock, chance of thermal efficiency reduction. In this framework, numerical simulation can be a useful tool, not only to better understand specific characteristics of DF combustion, but also to explore specific geometrical modifications and engine calibrations capable to adapt current LD architectures to this concept.
2017-03-28
Journal Article
2017-01-0754
Hu Wang, Laihui Tong, Zunqing Zheng, Mingfa Yao
The dual-fuel RCCI combustion could achieve high efficiency and low emissions over a wide range of operating conditions. However, further high load extension is limited by the excessive pressure rise rate and soot emission. PODE, as a novel diesel alternative fuel, has the capability to achieve stoichiometric smoke-free RCCI combustion due to its high oxygen content and unique molecule structure. In this study, experimental investigations on high load extension of gasoline/PODE RCCI operation were conducted using the late intake valve closing (LIVC) strategy and intake boosting in a single-cylinder, heavy-duty diesel engine. The experimental results show that the upper load can be effectively extended through boosting and LIVC with gasoline/PODE stoichiometric operation. With the retarding of LIVC timing, higher boosting pressure and lower EGR ratio were required to maintain sufficient available oxygen.
2017-03-28
Journal Article
2017-01-1005
Yizhou Zhang, Jaal Ghandhi, David Rothamer
Measurements of the particle size distribution (PSD) provide important insight into the nature of particulate matter (PM) and its sources as stricter PM emission regulations (both mass & number based) are being implemented. A previous study by the authors suggested a link between the change in PSD shape and changing amounts of direct-injected fuel. In this study, the effect of direct-injected fuel on the PSDs from dual-fuel combustion strategies is investigated in greater depth. The PSD data were measured using a scanning mobility particle sizer (SMPS) and acquired in a light-duty single cylinder diesel engine operated using conventional diesel combustion (CDC) and two diesel/natural gas dual-fuel combustion strategies. Three different direct-injection (DI) fuels (diesel, 2,6,10-trimethyldodecane (farnesane), and a primary research fuel (PRF) blend) and two different injector nozzles were used in this study.
2017-03-28
Journal Article
2017-01-0517
Ivan Taritas, Darko Kozarac, Momir Sjeric, Miguel Sierra Aznar, David Vuilleumier, Reinhard Tatschl
Abstract This paper presents a newly developed quasi-dimensional multi-zone dual fuel combustion model, which has been integrated within the commercial engine system simulation framework. Model is based on the modified Multi-Zone Combustion Model and Fractal Combustion Model. Modified Multi-Zone Combustion Model handles the part of the combustion process that is governed by the mixing-controlled combustion, while the modified Fractal Combustion Model handles the part that is governed by the flame propagation through the combustion chamber. The developed quasi-dimensional dual fuel combustion model features phenomenological description of spray processes, i.e. liquid spray break-up, fresh charge entrainment, droplet heat-up and evaporation process. In order to capture the chemical effects on the ignition delay, special ignition delay table has been made.
2017-03-28
Technical Paper
2017-01-0544
Philipp Mayr, Gerhard Pirker, Andreas Wimmer, Markus Krenn
It is critical for gas and dual fuel engines to have improved transient characteristics in order for them to be able to compete with diesel engines. Testing of transient behavior as well as of different control strategies for the multicylinder engine (MCE) should already be done on the single cylinder engine (SCE) test bed during the development process. This paper presents tools and algorithms that transfer transient MCE behavior to the SCE test bed. A methodology is developed for a two-stage turbocharged gas engine and includes both simulation and measurements. Simple and fast models and algorithms are created that are able to provide the boundary conditions (e.g., boost pressure and exhaust back pressure) of a multicylinder engine in transient operation in real time for use on the SCE test bed. The main models of the methodology are discussed in detail.
2016-10-25
Technical Paper
2016-36-0287
Johnys George, Rogério Onoda, Edson Luciano Duque
Abstract In internal combustion engines, mainly the Brazilian flex fuel versions, the compression ratio is an important factor to ensure its correct operation, and especially to ensure that the end customer gets a vehicle with net power within the calculated and specified limits by Product Engineering. An inadequate compression ratio can greatly affect the engine performance and, in the same proportion, affect the end customer satisfaction, reliability and loyalty to the brand. The methodology to be presented in this work is based on the 3D virtual simulation software developed by Dimensional Control Systems Inc., the 3DCS® v.7, where through random combinations of dimensional variations of each component involved in the system it is possible to calculate the nominal compression ratio and the variation limits, simulate statistical values that actually happen in real life, and obtain a ranking of the contribution percentage of each variable to the total variation in compression ratio.
2016-10-17
Technical Paper
2016-01-2304
Kohei Kuzuoka, Junichi Kamio, Kohtaro Hashimoto
Abstract Compression ignition combustion with a lean mixture has high potential in terms of high theoretical thermal efficiency and low NOx emission characteristics due to low combustion temperatures. In particular, a Dual-Fuel concept is proposed to achieve high ignition timing controllability and an extended operation range. This concept controls ignition timing by adjusting the fraction of two fuels with different ignition characteristics. However, a rapid combustion process after initial ignition cannot be avoided due to the homogenous nature of the fuel mixture, because the combustion process depends entirely on the high reaction rate of thermal ignition. In this study, the effect of mixture stratification in the cylinder on the combustion process after ignition based on the Dual-Fuel concept was investigated.
2016-10-17
Technical Paper
2016-01-2305
Ireneusz Pielecha, Krzysztof Wislocki, Wojciech Cieslik, Przemyslaw Borowski, Wojciech Bueschke, Maciej Skowron
Abstract The paper presents the thermodynamic analysis of the engine supplied with small and large diesel fuel doses while increasing natural gas quantity. The paper presents changes in the combustion process thermodynamic indexes and changes in the exhaust gas emissions for dynamically increased share of the gaseous fuel. The cylinder pressure history was subject to thermodynamic analysis, . based on which the mean indicated pressure, the heat release rate, the quantity of heat released as well as the pressure rate increase after self-ignition were determined. These parameters were also referred to the subsequent engine operation cycles by specifying the scope of the change per cycle. The relationship between the engine load and the start, the center and the end of combustion while increasing the gas amount supplied to the cylinder was indicated.
2016-10-17
Technical Paper
2016-01-2312
Mateos Kassa, Carrie Hall, Andrew Ickes, Thomas Wallner
Abstract This study examines the dynamics and control of an engine operated with late intake valve closure (LIVC) timings in a dual-fuel combustion mode. The engine features a fuel delivery system in which diesel is direct-injected and natural gas is port-injected. Despite the benefits of LIVC and dual-fuel strategy, combining these two techniques resulted in efficiency losses due to the variability of the combustion process across cylinders. The difference in power production across cylinders ranges from 9% at an IVC of 570°ATDC* to 38% at an IVC of 620 °ATDC and indicates an increasingly uneven fuel distribution as the intake valve remains open longer in the compression stroke. This paper describes an approach for controlling the amount of fuel injected into each cylinders’ port of an inline six- cylinder heavy-duty dual-fuel engine to minimize the variations in fuel distribution across cylinder.
2016-10-17
Technical Paper
2016-01-2169
Carrie M. Hall, James Sevik, Michael Pamminger, Thomas Wallner
Abstract The high octane rating and more plentiful domestic supply of natural gas make it an excellent alternative to gasoline. Recent studies have shown that using natural gas in dual fuel engines provides one possible strategy for leveraging the advantages of both natural gas and gasoline. In particular, such engines been able to improve overall engine efficiencies and load capacity when they leverage direct injection of the natural gas fuel. While the benefits of these engine concepts are still being explored, differences in fuel composition, combustion process and in-cylinder mixing could lead to dramatically different emissions which can substantially impact the effectiveness of the engine’s exhaust aftertreatment system. In order to explore this topic, this study examined the variations in speciated hydrocarbon emissions which occur for different fuel blends of E10 and compressed natural gas and for different fuel injection strategies on a spark-ignition engine.
2016-10-17
Technical Paper
2016-01-2306
Hideyuki Ogawa, Gen Shibata, Jun Goto, Lin Jiang
Abstract The engine performance and the exhaust gas emissions in a dual fuel compression ignition engine with natural gas as the main fuel and a small quantity of pilot injection of diesel fuel with the ultra-high injection pressure of 250 MPa as an ignition source were investigated at 0.3 MPa and 0.8 MPa IMEP. With increasing injection pressure the unburned loss decreases and the thermal efficiency improves at both IMEP conditions. At the 0.3 MPa IMEP the THC and CO emissions are significantly reduced when maintaining the equivalence ratio of natural gas with decreasing the volumetric efficiency by intake gas throttling, but the NOx emissions increase and excessive intake gas throttling results in a decrease in the indicated thermal efficiency. Under the 250 MPa pilot injection condition simultaneous reductions in the NOx, THC, and CO emissions can be established with maintaining the equivalence ratio of natural gas by intake gas throttling.
2016-10-17
Technical Paper
2016-01-2308
Fridolin Unfug
Abstract Strict emission regulations and the need of higher efficiency of future dual fuel engines require an optimized combustion process. For getting a better understanding of the in-cylinder combustion process optical investigations represent a powerful tool. For medium speed dual fuel engines, optical investigations are pretty rare respectively not available. Especially the avoiding of knock events within the combustion process is a key development topic to realize high engine load and high engine efficiency. For the investigations a fully flexible dual fuel test engine was used. The engine is operated with a natural gas / air cylinder charge which is ignited by a small micro pilot diesel injection within the gas mode.
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