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Viewing 1 to 30 of 5831
2015-04-14
Journal Article
2015-01-1177
Steven Mathison, Kiyoshi Handa, Timothy McGuire, Tyler Brown, Todd Goldstein, Michael Johnston
Abstract Appendix H of the SAE J2601 standard defines a development hydrogen fueling protocol named the MC Default Fill, which builds upon the foundation of the table based protocol, utilizing the same assumptions, boundary conditions, and process limits as the current standard. The MC Default Fill facilitates the following beyond the table based protocol: 1) the potential to provide faster, more consistent fueling times for fuel cell electric vehicle customers, and 2) the ability to continuously and dynamically adjust to a wide range of dispenser fuel delivery temperatures, allowing for more flexibility in station design. Computer simulations and laboratory bench tests were previously conducted and documented, validating the function and operation of the protocol.
2015-04-14
Technical Paper
2015-01-1163
Gabriel Elias, Stephen Samuel, Alessandro Picarelli
Abstract This study details the investigation into the hybridization of engine ancillary systems for 2014+ Le Mans LMP1-H vehicles. This was conducted in order to counteract the new strict fuel-limiting requirements governing the powertrain system employed in this type of vehicle. Dymola 1D vehicle simulation software was used to construct a rectilinear vehicle model with a map based 3.8L V8 engine and its associated ancillary systems, including oil pumps, water pump and fuel pump as well as a full kinetic energy recovery system (ERS). Appropriate validation strategy was implemented to validate the model. A validated model was used to study the difference in fuel consumption for the conventional ancillary drive off of the internal combustion engine in various situational tests and a hybrid-electric drive for driving engine ancillaries.
2015-04-14
Technical Paper
2015-01-0672
Douglas Marriott, Takeshi Ohtomo, Tohru Wako
Abstract Predicting sloshing noise as early as possible during the design process has become an increasingly desired simulation for fuel tank suppliers as the demand for quieter vehicles increase. Simulating early on in the design process enables suppliers to build products directly to customer specifications, at a lower cost and shorter timeframe. The procedure to accurately and efficiently analyze complete sloshing noise behavior has to date not been fully established. Current methods rely on indirect noise deduction based on specific positions from Fluid-Structure Interaction (FSI) analyses or uncoupled fluid analysis with separate structural and acoustic analyses. In this paper, we introduce a technique to analyze the fully coupled sloshing noise generated in the fuel tank of an automobile. The technique takes advantage of combining an explicit coupled Lagrangian and Eulerian solver with an acoustics solver.
2015-04-14
Journal Article
2015-01-0521
Yong-Yuan Ku, Ta-Wei Tang, Ko Wei Lin, Steven Chan
With the development of world economy, the shortage in the supply of oil energy as well as the greenhouse effect have become a public concern around the world. The application of biodiesel on vehicle transportation has become the focus of development in many countries. Biodiesel, Fatty Acid Methyl Esters (FAME), is made during the process of transesterification of the animal and vegetable oils. Compared with fossil diesel, biodiesel has some characteristics, such as organic acid, higher water saturation, and oxygen content. From the results of the literatures [1] to [5], it showed that biodiesel would cause the inflation of some plastic and flexible products and the corrosion of metal materials. Metal fuel tanks have the characteristics of high flammability, high impact resistance, and good workability and are often used in commercial vehicles. The corrosion of metal materials is a natural chemical change and it can be influenced by the environment.
2015-04-14
Technical Paper
2015-01-1350
Peng Liu, Liyun Fan, De Xu, Xiuzhen Ma, Enzhe Song
Abstract High-speed solenoid valve (HSV) is one of the most critical components of electronic control fuel system for diesel engine, whose dynamic response characteristics have a direct impact on the key performance indicators of diesel engine. For the improvement of dynamic response speed of HSV, a design method of multi-objective optimization based on response surface methodology and genetic algorithm (GA) is employed. Firstly, the finite element model (FEM) of HSV was developed and verified. Secondly, the second order polynomial response surface model (RSM) of the electromagnetic force was constructed by the method of optimal latin hypercube design along with the FEM of HSV, taking the key structural parameters of armature and iron core as variables. Then the multi-objective optimization mathematical model (MOMM) of HSV based on RSM was analyzed and established, taking the electromagnetic force and the mass of armature as objectives.
2015-04-14
Technical Paper
2015-01-1270
Philip Anderson, Mohammed Aslam, Partab Jeswani
Abstract In the current state of the art automotive fuel pumps there is only one channel on each side of the impeller. For high flow and pressure applications the size of such pumps becomes excessive. In order to reduce the size to a manageable level it may be necessary to have two or more channels on each side. But the problem with a multichannel pump is that the peak efficiency of each channel happens at a different operating point and the overall pump efficiency may not be that good. This problem can be overcome by synchronizing the channels. In a synchronous pump the channel diameter and cross sectional area of channels are such that the peak efficiency happens at the same operating point and the overall pump efficiency is improved. In this paper we derive the governing equations for flow, pressure and efficiency and layout a methodology for synchronizing the channels.
2015-04-14
Technical Paper
2015-01-1267
Jae-Cheon Lee, Hao Liu, Yoo-Jeong Noh, Hyun Myung Shin, Yong Nam Shin, Myung Kweon Kang
Abstract A high-pressure fuel pump in a GDI (Gasoline Direct Injection) engine has been increasingly applied on passenger vehicles because of its high fuel efficiency and reduction of exhaust emissions. The design specifications of principal components of GDI high-pressure pump should be validated prior to the manufacturing. This study presents the analytical results of the specifications for the design of a GDI pump of Motonic Co. by using computational model based simulation. The results are largely divided into two parts. First, cam-follower dynamics with the proper design of cam profile, and second, the discharge flow performance of the pump in consideration of the characteristics of inlet control valve.
2015-04-14
Technical Paper
2015-01-1273
Shunsuke Aritomi, Hiroyasu Kuniyoshi, Kenichirou Tokuo, Satoshi Usui, Atsuji Saito, Yuta Saso
Abstract A recent trend in high-pressure gasoline pumps is increasing the outlet pressure. One of the most important topics for increasing this pressure is improving volumetric efficiency. Therefore, the purpose of this research is to quantify the breakdown of efficiency loss factors and to suggest a new design for improving volumetric efficiency. Authors developed a method of quantifying the efficiency loss breakdown of high-pressure gasoline pumps by using 1D fluid pressure simulation results and conducting evaluation experiments regarding sensitivity. Authors separated pump movement into three phases; suction, compression, and delivery. Authors then investigated the loss factors in each phase. As a result, authors obtained an equation for predicting the final output volume. The equation consists of a limit output volume and other types of leakage volumes.
2015-04-14
Technical Paper
2015-01-1264
Junseok Chang, Yoann Viollet, Abdullah Alzubail, Amir Faizal Naidu Abdul-Manan, Abdullah Al Arfaj
Abstract This paper explores the potential for reducing transport-related greenhouse gas (GHG) emissions by introducing high-efficiency spark-ignition engines with a dual-fuel injection system to customize the octane of the fuels based on real-time engine requirements. It is assumed that a vehicle was equipped with two fuel tanks and two injection systems; one port fuel injection and one direct injection line separately. Each tank carried low octane and high octane fuel so that real-time octane blending was occurred in the combustion chamber when needed (Octane On-Demand: OOD). A refinery naphtha was selected for low octane fuel (RON=61), because of its similarity to gasoline properties but a less processed, easier to produce without changing a refinery configuration. Three oxygenates were used for high octane knock-resistant fuels in a direct injection line: methanol, MTBE, and ETBE.
2015-04-14
Journal Article
2015-01-1727
Francesco Balduzzi, Giovanni Vichi, Luca Romani, Giovanni Ferrara, Paolo Trassi, Jacopo Fiaschi, Federico Tozzi
Abstract High specific fuel consumption and pollutant emissions are the main drawbacks of the small crankcase-scavenged two-stroke engine. The symmetrical port timing combined with a carburetor or an indirect injection system leads to a lower scavenging efficiency than a four-stroke engine and to the short-circuit of fresh air-fuel mixture. The use of fuel supply systems as the indirect injection and the carburetor is the standard solution for small two-stroke engine equipment, due to the necessity of reducing the complexity, weight, overall dimensions and costs. This paper presents the results of a detailed study on the application of an innovative Low Pressure Direct Injection system (LPDI) on an existing 300 cm3 cylinder formerly equipped with a carburetor. The proposed solution is characterized by two injectors working at 5 bar of injection pressure.
2015-04-14
Technical Paper
2015-01-1730
Luca Romani, Giovanni Vichi, Giovanni Ferrara, Francesco Balduzzi, Paolo Trassi, Jacopo Fiaschi, Federico Tozzi
Abstract High specific fuel consumption and pollutant emissions are the main drawbacks of the small crankcase-scavenged two-stroke engine. The symmetrical port timing combined with a carburetor or an indirect injection system leads to a lower scavenging efficiency than a four-stroke engine and to the short-circuit of fresh air-fuel mixture. The use of fuel supply systems as the indirect injection and the carburetor is the standard solution for small two-stroke engine equipment, due to the necessity of reducing the complexity, weight, overall dimensions and costs. This paper presents the results of a detailed study on the application of an innovative Low Pressure Direct Injection system (LPDI) on an existing 300 cm3 cylinder formerly equipped with a carburetor. The proposed solution is characterized by two injectors working at 5 bar of injection pressure.
2015-04-14
Technical Paper
2015-01-1731
Yanxiang Yang, Bingqian Tan, Changwen Liu, Ping Zhang, Daguang Xi
A pump-end control technology for pump-nozzle fuel supply unit, in which the pump is driven and controlled electrically for pressurizing and metering the fuel fed into an engine, is studied. The unit is composed of a solenoid driven plunger pump, a high-pressure fuel tube, and an auto-open nozzle, and only the pump is propelled by PWM power from an ECU. To achieve a higher metering accuracy, a metering theory deciding the fuel discharging rate was developed by studying the system using a physical-mathematical model. The developed so called T3 theory makes the fuel supply unit with excellent metering consistency under various conditions, which can meet the requirement of fuel supply unit application to small engine management system. The study reveals that an electrically characterized variable, T3, which is associated with the net output energy, can directly results in a mass discharge.
2015-04-14
Technical Paper
2015-01-1647
Matthieu Lecompte, Stephane Raux, Jerome Cherel, Vivien Delpech
Abstract Euro VI standards for heavy duty vehicles require the use of a DPF in order to comply with the particulate matter emission limit. Although passive regeneration of soot by NO2, promoted by a DOC located upstream the DPF, is preferred, the use of an active regeneration might be required whenever the soot mass trapped in the DPF increases. Some manufacturers made the choice of having a fuel injection in the exhaust system in order to generate an exothermic reaction in the DOC that helps to regenerate the particulate filter. This dedicated circuit avoids the use of in-cylinder post-injection which may induce oil dilution by diesel. The DPF regeneration is efficient and the DOC works durably if the exhaust diesel spray is completely vaporized before entering the DOC and is thoroughly mixed with the exhaust gases. However, ensuring complete evaporation and an optimum mixture distribution in the exhaust line is challenging.
2015-04-14
Technical Paper
2015-01-0949
Mathis Bode, Tobias Falkenstein, Vincent Le Chenadec, Seongwon Kang, Heinz Pitsch, Toshiyuki Arima, Hiroyoshi Taniguchi
Abstract Compared to conventional injection techniques, Gasoline Direct Injection (GDI) has a lot of advantages such as increased fuel efficiency, high power output and low emission levels, which can be more accurately controlled. Therefore, this technique is an important topic of today's injection system research. Although the operating conditions of GDI injectors are simpler from a numerical point of view because of smaller Reynolds and Weber numbers compared to Diesel injection systems, accurate simulations of the breakup in the vicinity of the nozzle are very challenging. Combined with the complications of experimental techniques that could be applied inside the nozzle and at the nozzle exit, this is the reason for the lack of understanding the primary breakup behavior of current GDI injectors.
2015-04-14
Technical Paper
2015-01-0946
Yongjin Jung, Julien Manin, Scott Skeen, Lyle M Pickett
Abstract The mixing field of sprays injected into high temperature and pressure environments has been observed to be tightly connected to spreading angle, therefore linking vaporization and combustion processes to the angular dispersion of the spray. Visualization of the Engine Combustion Network three-hole, Spray B diesel injector shows substantial variation in near-field spreading angle with respect to time compared to past measurements of the single-hole, Spray A injector. The source of these variations originating inside the nozzle, and the implications on mixing, evaporation, and combustion of the diesel plume, need to be understood. In this study, we characterize the ECN-target plume for a Spray B injector (Serial # 211201), which already benefits from extensive and detailed internal measurements of nozzle geometry and needle movement, while comparing to the single-hole Spray A with the same type of detailed geometry and understanding.
2015-04-14
Technical Paper
2015-01-0948
Le (Emma) Zhao, Ahmed Abdul Moiz, Jeffrey Naber, Seong-Young Lee, Sam Barros, William Atkinson
Abstract High-speed spray-to-spray liquid impingement could be an effective phenomenon for the spray propagation and droplet vaporization. To achieve higher vaporization efficiency, impingement from two-hole nozzles is analyzed in this paper. This paper focuses on investigating vaporization mechanism as a function of the impingement location and the collision breakup process provided by two-hole impinging jet nozzles. CFD (Computational Fluid Dynamics) is adopted to do simulation. Lagrangian model is used to predict jet-to-jet impingement and droplet breakup conditions while KH-RT breakup and O'Rourke collision models are implemented for the simulation. The paper includes three parts: First, a single spray injected into an initially quiescent constant volume chamber using the Lagrangian approach is simulated to identify the breakup region, which will be considered as a reference to study two-hole impinging jet nozzles.
2015-04-14
Technical Paper
2015-01-0944
Maryam Moulai, Ronald Grover, Scott Parrish, David Schmidt
Abstract A computational and experimental study was performed to characterize the flow within a gasoline injector and the ensuing sprays. The computations included the effects of turbulence, cavitation, flash-boiling, compressibility, and the presence of non-condensible gases. The flow domain corresponded to the Engine Combustion Network's Spray G, an eight-hole counterbore injector operating in a variety of conditions. First, a rate tube method was used to measure the rate of injection, which was then used to define inlet boundary conditions for simulation. Correspondingly, injection under submerged conditions was simulated for direct comparison with experimental measurements of discharge coefficient. Next, the internal flow and external spray into pressurized nitrogen were simulated under the base spray G conditions. Finally, injection under flashing conditions was simulated, where the ambient pressure was below the vapor pressure of the fuel.
2015-04-14
Technical Paper
2015-01-0942
Vikram Singh, Anshul Koli
Abstract This research presents the simulation of the jet behavior of gasoline ethanol blends in a quiescent chamber using the Lattice Boltzmann method. The fuel is taken as different mixtures of gasoline and ethanol, and the properties, such as density, viscosity and surface tension, are varied accordingly in the Lattice Boltzmann model. The variations in jet structure and instabilities are modeled according to the velocity of fuel injection, the composition of the gasoline-ethanol blend and the property of the surrounding mixture. The model implemented for the interaction of the two fluids; air and fuel, is the Shan Chen model. The accuracy of the model is confirmed using a static drop test at different curvatures for the two fluids as well as observing the evolution of merging droplets. This is the first time that the study of different fuels in done using the Shan Chen model.
2015-04-14
Technical Paper
2015-01-0940
Yun Bai, Liyun Fan, Xiuzhen Ma, Enzhe Song, Xin Yan
Abstract Electronic in-line pump system (EIPS) is an electronic controlled fuel injection system which meets China's emission regulations. In this paper, a numerical model of EIPS was developed in AMESim for the purpose of creating a tool for simulation experiments. Experiments were conducted at the same model conditions to validate the model. The results are quite encouraging and in agreement with model predictions which imply that the model can accurately predict the dynamic injection characteristics of EIPS. The design of experiments was performed using a 2-level-5-factor face-centered central composite design (FCCD) method in order to study the interactive effect of factors on fuel injection quantity fluctuation (FIQF). The factors studied were supply fuel pressure, cam linear velocity, control valve lift, needle spring pretightening force and nozzle flow coefficient.
2015-04-14
Technical Paper
2015-01-0950
Jonas Galle, Roel Verschaeren, Sebastian Verhelst
Abstract The need for simulation tools for the internal combustion engine is becoming more and more important due to the complex engine design and increasingly strict emission regulation. One needs accurate and fast models, but fuels consist of a complex mixture of different molecules which cannot realistically be handled in computations. Simplifications are required and are realized using fuel surrogates. The main goal of this work is to show that the choice of the surrogates is of importance if simplified models are used and that the performance strongly depends upon the sensitivity of the fuel properties that refer to the main model hypotheses. This paper starts with an overview of surrogates for diesel and bio-diesel as well as the motivation for choosing them. Next, a phenomenological model for vaporizing fuel-sprays is implemented to assess how well-known surrogates for diesel and bio-diesel affect the obtained results.
2015-04-14
Technical Paper
2015-01-0929
Petter Dahlander, Daniele Iemmolo, Yifei Tong
Abstract Time-resolved mass injection rates of an outward opening piezo-actuated and a solenoid actuated multi-hole GDI injector were measured to investigate (1) the influence of both hardware and software settings and (2) the influence on the injection rates from a wide range of operational parameters and (3) discuss limitations and issues with this measurement technique. The varied operating parameters were fuel pressure, back-pressure, electrical pulse width, single/double injection and injection frequency. The varied hardware/software parameters were injector protrusion, upstream fuel pressure condition and the cut-off frequency of the software's low-pass filter. Signal quality was found to be dependent on both hardware and software settings, especially the cut-off frequency of the low-pass filter. Measurements with high signal quality were not possible for back-pressures lower than 0.5 MPa.
2015-04-14
Technical Paper
2015-01-0926
Tianyun Li, Min Xu, David Hung, Shengqi Wu, Siqi Cheng
Abstract Comparing with port-fuel-injection (PFI) engine, the fuel sprays in spark-ignition direct-injection (SIDI) engines play more important roles since they significantly influence the combustion stability, engine efficiency as well as emission formations. In order to design higher efficiency and cleaner engines, further research is needed to understand and optimize the fuel spray atomization and vaporization. This paper investigates the atomization and evaporation of n-pentane, gasoline and surrogate fuels sprays under realistic SIDI engine conditions. An optical diagnostic technique combining high-speed Mie scattering and Schlieren imaging has been applied to study the characteristics of liquid and vapor phases inside a constant volume chamber under various operating conditions. The effects of ambient temperature, fuel temperature, and fuel type on spray atomization and vaporization are analyzed by quantitative comparisons of spray characteristics.
2015-04-14
Technical Paper
2015-01-0927
Luca Marchitto, Gerardo Valentino, Simona Merola, Cinzia Tornatore
Abstract The use of alcohols as alternative to gasoline for fuelling spark-ignition (SI) engines is widespread. Growing interest is paid for n-butanol because of its characteristics that are similar to gasoline. If compared with other alcohols, n-butanol has higher energy content and miscibility with gasoline, lower hygroscope and corrosive properties making it an attractive solution for gasoline replacement. Even if several studies have been conduced to characterize the n-butanol combustion within Spark Ignition engines, few data are available on atomization and spray behavior. This paper reports the results of an experimental investigation to characterize the velocity vector field of two fuel-sprays injected by a 6-hole nozzle for Direct Injection Spark Ignition (DISI) engine. 2D Mie-scattering and Particle Image Velocimetry (PIV) measurements were carried out in an optically accessible vessel at ambient temperature and pressure.
2015-04-14
Technical Paper
2015-01-0924
Joseph Camm, Richard Stone, Martin Davy, David Richardson
Abstract A model for the evaporation of a multi-component fuel droplet is presented that takes account of temperature dependent fuel and vapour properties, evolving droplet internal temperature distribution and composition, and enhancement to heat and mass transfer due to droplet motion. The effect on the internal droplet mixing of non-ideal fluid diffusion is accounted for. Activity coefficients for vapour-liquid equilibrium and diffusion coefficients are determined using the UNIFAC method. Both well-mixed droplet evaporation (assuming infinite liquid mass diffusivity) and liquid diffusion-controlled droplet evaporation (iteratively solving the multi-component diffusion equation) have been considered.
2015-04-14
Technical Paper
2015-01-0925
Erik Elmtoft, A. S. (Ed) Cheng, Nick Killingsworth, Russell Whitesides
Abstract Injection spray dynamics is known to be of great importance when modeling turbulent multi-phase flows in diesel engines. Two key aspects of spray dynamics are liquid breakup and penetration, both of which are affected by the initial sizes of the injected droplets. In the current study, injection of liquid n-heptane is characterized with initial droplet sizes with diameters on the order of 0.10 - 0.25 nozzle diameters. This is done for a Reynolds Averaged Navier-Stokes (RANS) RNG k-ε turbulence model with a minimum grid size of 125 μm and for a Large Eddy Simulations (LES) viscosity turbulence model with a minimum grid size of 62.5 μm. The results of both turbulence models are validated against non-reacting experimental data from the Engine Combustion Network (ECN). The results show that the injected droplet sizes have a significant impact on both liquid and vapor penetration lengths.
2015-04-14
Technical Paper
2015-01-0922
Giancarlo Chiatti, Ornella Chiavola, Matteo Palazzoni, Fulvio Palmieri
Abstract Relatively recent investigations, basing on experiments as well as on modeling, have highlighted that the needle displacement in common-rail diesel injectors is affected by radial components. The effects of such “off-axis” needle displacement on fuel flow features have been so far investigated within the nozzle, only. The objective of this work is to extend the attention towards the formation of fuel sprays, when needle off-axis condition is encountered. In such a viewpoint, the development of each fuel spray has been modeled taking into account the hole-to-hole variations induced by the needle misalignment. The investigation has been carried out basing on 3D-CFD campaigns, in AVL FIRE environment. The modeling of diesel nozzle flow has been interfaced to the spray simulation, initializing the break-up model on the basis of the transient flow conditions (fuel velocity, turbulence and vapor fraction) at each hole outlet section.
2015-04-14
Technical Paper
2015-01-0923
Mohamed Chouak, Alexandre Mousseau, Damien Reveillon, Louis Dufresne, Patrice Seers
Abstract The transient characteristics of the internal flow dominate all the ensuing processes: spray, fuel-air mixture formation as well as combustion and pollutants formation. Therefore, it is crucial to understand the dynamics of the injectors' internal flow. The objective of this work is to study all transient effects that may impact the internal flow of a single hole injector under different conditions. Since the numerical investigation of such a complex flow is hampered by several factors for the real operating conditions-namely the turbulence, the cavitation and the needle motion-this work is divided into two parts. In the first part, only the effects of turbulence and cavitation are considered through the study of the effects of the fuel properties as well as the injection conditions at the fully open needle position. The impact of these effects is studied by means of the Reynolds and the cavitation number.
2015-04-14
Technical Paper
2015-01-0938
Prashanth Karra, Thomas Rogers, Petros Lappas
Abstract The air entrainment process of a compressed natural gas transient fuel jet was investigated in a constant-volume chamber using Schlieren and particle image velocimetry (PIV) techniques. A new method of calculating air entrainment around a gaseous fuel jet is proposed using Schlieren and PIV imaging techniques. This method offers an alternative to calculation of an alternative to calculation of entrainment using LIF technique in gaseous fuel jets. Several Jet-ambient pressure ratios were tested. In each test, nitrogen was used to fill the chamber as an air surrogate before the jet of natural gas was injected. Schlieren high speed videography and PIV experiments were performed at the same conditions. Schlieren mask images were used to accurately identify the jet boundary which was then superimposed onto a PIV image. Vectors adjacent to the Schlieren mask in the PIV image were used to calculate the spatial distribution of the air entrainment at the jet boundary.
2015-04-14
Technical Paper
2015-01-0939
Daliang Jing, Shi-Jin Shuai, Zhi Wang, Yanfei Li, Hongming Xu
Abstract The design and optimization of a modern spray-guided gasoline direct injection engine require a thorough understanding of the fuel spray characteristics and atomization process. The fuel spray Computational Fluid Dynamics (CFD) modeling technology can be an effective means to study and predict spray characteristics, and as a consequence, to drastically reduce experimental work during the engine development process. For this reason, an accurate numerical simulation of the spray evolution process is imperative. Different models based on aerodynamically-induced breakup mechanism have been implemented to simulate spray atomization process in earlier studies, and the effect of turbulence from the injector nozzle is recently being concerned increasingly by engine researchers. In this study, a turbulence-induced primary breakup model coupled with aerodynamic instability is developed.
2015-04-14
Technical Paper
2015-01-0937
Philip Zoldak, Joel John Joseph, William Shelley, Jaclyn Johnson, Jeffrey Naber
Abstract The increased availability of natural gas (NG) in the United States (US) and its relatively low cost compared to diesel fuel has heightened interest in the conversion of medium duty (MD) and heavy duty (HD) diesel engines to NG fuel and combustion systems (compressed or liquefied). The intention is to realize fuel cost savings and reduce harmful emissions, while maintaining or improving overall vehicle fuel economy. This is a potential path to help the US achieve energy diversity and reduce dependence on crude oil. Traditionally, port-injected, premixed NG spark-ignited combustion systems have been used for medium and heavy duty engines with widespread use in the US and Europe. But this technology exhibits poor cycle efficiency and is load limited due to knock phenomenon. Direct Injection of NG during the compression stroke promises to deliver improved thermal efficiency by avoiding premixing and extending the lean limits which helps to extend the knock limit.
Viewing 1 to 30 of 5831