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Viewing 1 to 30 of 5723
2015-01-01
Technical Paper
2014-01-9053
Tobias Breuninger, Jürgen Schmidt, Helmut Tschoeke, Martin Hese, Andreas Kufferath, Frank Altenschmidt
The spray-guided combustion process offers a high potential for fuel savings in gasoline engines in the part load range. In this connection, the injector and spark plug are arranged in close proximity to one another, as a result of which mixture formation is primarily shaped by the dynamics of the fuel spray. The mixture formation time is very short, so that at the time of ignition the velocity of flow is high and the fuel is still largely present in liquid form. The quality of mixture formation thus constitutes a key aspect of reliable ignition. In this article, the spray characteristics of an outward-opening piezo injector are examined using optical testing methods under pressure chamber conditions and the results obtained are correlated with ignition behaviour in-engine. The global spray formation is examined using high-speed visualisation methods, particularly with regard to cyclical fluctuations. In order to characterise the recirculation zone of the hollow cone spray that is relevant to the ignition behaviour, laser-optical measuring methods were used.
2014-11-11
Technical Paper
2014-32-0040
John Walters, Francois Brun
Abstract Stringent emissions legislation is being applied to small motorcycles and scooters around the world. This is forcing, gradually, the replacement of carburetors by electronic fuel injection (EFI) systems. The integration of this new technology creates new constraints on the engine and also on the vehicle. This study will provide an overview of these constraints and also technical solutions to reduce the impact on engine and vehicle. A special focus will be done on the fuel system, where the development of an advanced technology will be discussed in detail. This technology marks a break with the standard automotive fuel system architecture in order to fulfill the specific requirements of scooters and small motorcycles: low size, low weight, low energy demand, as well as simple integration. The discussion will disclose: the advantages and drawbacks of different fuel system architectures, the detailed description of the technology selected to achieve the requirements, the modelling approach used for the sizing and optimization of the design, and finally the performance achieved on the test bench.
2014-11-11
Technical Paper
2014-32-0041
Luigi Allocca, Alessandro Montanaro, Rita Di Gioia, Giovanni Bonandrini
Abstract In the next future, improvements of direct injection systems for spark-ignited engines are necessary for the potential reductions in fuel consumptions and exhaust emissions. The admission and spread of the fuel in the combustion chamber is strictly related to the injector design and performances, such as to the fuel and environmental pressure and temperature conditions. In this paper the spray characterization of a GDI injector under normal and flash-boiling injection conditions has been investigated. The paper is mainly focused both on the capability of the injection apparatus/temperatures controller system to realize flash-boiling conditions, and the diagnostic setup to catch the peculiarities of the spray behavior. The work aims reporting the spray characterization under normal and flash-boiling conditions. Flash-boiling is a phenomenon that occurs in certain engine conditions when the in-cylinder pressure is lower than the saturation pressure of the fuel, and leads to internal boiling and vapor bubbles creation near the nozzle exit.
2014-11-11
Technical Paper
2014-32-0125
Mohd Al-Hafiz Mohd Nawi, Yoshiyuki Kidoguchi, Misato Nakagiri, Naoya Uwa, Yuzuru Nada, Seiji Miyashiro
Abstract High boosting technology is commonly applied to diesel engines in recent years. Amid this trend, the study of spray behavior at ignition delay period still plays an important role in diesel combustion. This study focuses on the effect of ambient condition on diesel spray. The study investigates both macro-scale and micro-scale dynamic behaviors of diesel spray affected by ambient density and temperature at early stage of injection. A study via dual nano-spark shadowgraph method and rapid compression machine has been carried out to simulate real diesel engine combustion and to further understand the dynamics behavior of droplet evaporation and size distribution at early stage of mixture formation in the chamber. The micro-scale images captured reveal a shape variation of branch-like structures formed at the spray boundary. The evaporation of droplets is also captured clearly in macro- and micro scale photographs under the condition of high temperature ambient. Detailed observation and analysis of the images show that high ambient density affects the spray atomization at the upper stream of diesel spray at the early stage of injection.
2014-11-11
Technical Paper
2014-32-0134
Giovanni Bonandrini, Rita Di Gioia, Luca Venturoli, Domenico Papaleo, Lucio Postrioti, Leonardo Zappalà
Abstract Diesel engine technology is continuously focused on higher performances and lower emission levels. Reduced costs and lower fuel consumption are key factors in engine development too, in particular for small diesel engine, both for on-road and non-road application. In order to fulfill emission legislation requirements, improve engine performance and reduce fuel consumption, nowadays the common rail injection system with electronic actuation is widely used in diesel engines. Nevertheless, conventional common rail system cost is quite high, mainly due to the complex indirect actuation of the injector, and the injector backflow leads to inefficiencies in the injection system. In this work an analysis of a medium pressure injection system for small diesel engines is presented, focusing on the achievable engine performances and emissions. The new injection system makes use of an innovative solenoid directly actuated injector (DDI) with a lower maximum rail pressure in respect with conventional common rail systems.
2014-11-11
Technical Paper
2014-32-0059
Antonio Agresta, Francesca Di Puccio, Paola Forte, Gabriele Benigni
Abstract NVH simulations for an automotive component industry represent a convenient mean to compare different solutions and make decisions on design choices based on the predictions of the component vibro-acoustic behavior. This paper presents the vibro-acoustic characterization and comparison of two fuel rail assemblies (FRAs) by mean of simulations in Ansys Workbench & LMS Virtual.Lab. These simulations required a preliminary finite element (FE) modal analysis on the FRAs. To verify the reliability of the FE models, an experimental modal analysis was performed on one of the two fuel rails in free-free condition. The correlation between FE and test models highlighted some differences: a sensitivity study proved that the differences depend on the modeling of some brazed joints. The results of the following NVH simulations were checked by performing an acoustic impact test on the two FRAs in free-free condition inside an anechoic chamber. The comparison between the test and FE results proved that only a tuned FE model provides reliable results.
2014-11-11
Technical Paper
2014-32-0062
Jonathan Tenenbaum, Michael Shapiro, Leonid Tartakovsky
Abstract The paper presents an analytical two-dimensional model of two-phase turbulent jets with focus on fuel sprays in internal combustion engines. The developed model allows prediction of the fuel spray parameters including local fuel concentration and mixture velocity. The model proposed in this paper is based on the single-phase steady-state laminar axisymmetric jet flow field solution by Schlichting. This solution is amended to include transport of the discontinuous fuel phase in a stagnant air in the limit of a dilute fuel concentration. This two-phase jet flow model admits a closed form analytical solution for the fuel concentration distribution. This solution is then applied to turbulent jet flow as per the approach described by Schlichting and in other studies, and used to predict point-wise properties of fuel sprays in internal combustion engines. The results of model simulations are compared with the available experimental data. It was found that the analytical model predicts satisfactorily spray properties without additional assumptions or fitting coefficient.
2014-11-11
Technical Paper
2014-32-0124
Keiya Nishida, Kuichun LI, Takeru Matsuo, Daisuke Shimo, Wu Zhang
Abstract Spray characteristics under very small injection amount injected by the hole-type nozzle for a D.I. Diesel engine were investigated using the spray test rig consisting a high-pressure and high-temperature constant volume vessel with optical accesses and a common rail injection system. The Laser Absorption Scattering (LAS) technique was used to visualize the liquid and vapor phase distributions in the evaporating spray. In the very small injection amount condition of the evaporating and free (no wall impingement) spray, the both spray tip penetration and spray angle are larger than those of the non-evaporating free spray. This tendency contradicts the previous observation of the diesel spray with large injection amount and the quasi steady state momentum theory. In the case of the spray impinging on a 2-dimensional piston cavity wall, the spray tip penetration of the evaporating spray is larger than that of the non-evaporating spray. Discussion was made on the mechanisms behind these spray behaviors.
2014-11-11
Technical Paper
2014-32-0072
Kenta Sugimoto
Abstract Cost reduction is an important development goal for small motorcycles (1). As a way to reduce costs, we have developed an electronically controlled fuel injection (hereafter FI) system without a throttle position sensor (hereafter TPS). Ordinarily, the high throttle range is controlled and computed by TPS, and the low throttle range by manifold pressure sensor (hereafter MPS). The intake airflow is estimated with consistent high precision regardless of the engine load, and the basic fuel injection is executed accordingly. Also, transient correction monitors the size of TPS changes, to inject fuel immediately when a TPS change equal to or greater than a threshold value is detected. In our development, we replaced these functions with control by MPS. For calculation of basic fuel injection quantity by MPS, we carried on the conventional method. However, MPS transient correction control had some aspects with poor tracking. Thus, we constructed a new form of transient correction control, securing the following points.
2014-11-11
Technical Paper
2014-32-0073
Horizon Walker Gitano, Ray Chim, Jian Loh
Abstract Recent concern over air quality has lead to increasingly stringent emissions regulations on ever smaller displacement engines, resulting in the application of Electronic Fuel Injection (EFI) to the 100cc-200cc class 2-wheelers in many countries. In the pursuit of ever smaller and less expensive EFI systems a number of unique technologies are being explored, including resistive type oxygen sensors. In this paper we investigate the application of a prototype resistive oxygen sensor to a small motorcycle EFI system. Measurements of the exhaust system temperatures, and Air/Fuel Ratio (AFR) and resistive sensor response are carried out, and compared to the standard zirconia oxygen sensor to create an estimate of the sensor's in-use performance. Motorcycle performance data are compared using both a standard zirconia switching type oxygen sensor, and the new resistive type oxygen sensor to control the air/fuel ratio. Results indicate that the resistive type oxygen sensor is capable of allowing the EFI controller to successfully control the vehicle's AFR in all operating modes with a significantly faster “light off” time, and lower overall current draw when compared to the standard heated zirconia sensor.
2014-11-11
Technical Paper
2014-32-0075
Kazuyoshi Shimatani
Abstract Various sensors including throttle position sensors (TPS), manifold pressure sensors (MPS), crank angle sensors, engine temperature sensors, and oxygen sensors are mounted in electronically controlled fuel injection (FI) systems to accurately regulate the air-fuel ratio according to the operating state and operating environment. Among these vehicle-mounted sensors, TPS has functions for detecting a fully-closed throttle and estimating intake air volume by the amount of throttle opening. Currently, we have conducted a study on transferring TPS functions into the MPS (manifold pressure sensor) in order to eliminate the TPS. Here we report on detecting a fully-closed throttle for achieving fuel cut control (FCC) and idle speed control (ISC) in fuel injection systems. We contrived a means for fully-closed throttle detection during ISC and controlling changes in the bypass opening during FCC in order to accurately judge each fully-closed throttle state via the manifold pressure. A factor in causing fluctuations in manifold pressure in a fully-closed throttle state are changes in the engine RPM (also referred to as engine speed) and changes in the degree of opening of the bypass (hereafter simply bypass opening).
2014-11-11
Technical Paper
2014-32-0083
Akihiko Azetsu, Hiroomi Hagio
Abstract The objective of this study is to understand the fundamental spray combustion characteristics of FAME mixed with diesel oil. To examine the phenomena in detail, diesel spray flame formed in a constant volume high pressure vessel was visualized and the flame temperature and the KL factor were analyzed by two color method of luminous flame. The FAMEs examined in this study are PME, RME and CME, and compared with the combustion characteristics of diesel oil. From the systematic experiments, it is confirmed that the ignition delay and combustion period of bio diesel fuels are almost equivalent with those of diesel oil. The flame temperature decreased slightly with the bio fuel. Furthermore the total KL factor, a measure of the amount of soot in flame, decreased drastically by using the bio diesel fuel in the order of the mass fraction of oxygen in the molecule.
2014-11-01
Technical Paper
2014-01-9079
Yongming Bao, Qing Nian Chan, Sanghoon Kook, Evatt Hawkes
Abstract The spray development of ethanol, gasoline and iso-octane has been studied in an optically accessible, spark-ignition direct-injection (SIDI) engine. The focus is on how fuel properties impact temporal and spatial evolution of sprays at realistic ambient conditions. Two optical facilities were used: (1) a constant-flow spray chamber simulating cold-start conditions and (2) a single-cylinder SIDI engine running at normal, warmed-up operating conditions. In these optical facilities, high-speed Mie-scattering imaging is performed to measure penetrations of spray plumes at various injection pressures of 4, 7, 11 and 15 MPa. The results show that the effect of fuel type on the tip penetration length of the sprays depends on the injection conditions and the level of fuel jet atomisation and droplet breakup. It is observed that at 4 MPa injection pressure, the tip penetration length of ethanol sprays is shorter than that of gasoline sprays, likely due to lower injection velocity and increased nozzle loss associated with higher density and increased viscosity of ethanol, respectively.
2014-10-13
Technical Paper
2014-01-2560
Jacek Andrzej Czarnigowski
Abstract The paper presents the results of experiments on the effects of supply pressure and supply voltage on the pulse gas injector opening time. Two characteristics have been investigated into: the opening lag time and the time of opening. The injector's opening lag was defined as the time between the occurrence of a control signal and the moment of the valve's starting to move. The injector's time of opening was defined as the time of the valve element's movement from the closed to the fully open position. The analysis covered 6 injector types differing in the design of the valve element and the coil. The injectors types were representative of designs most popular in the market: piston and plate injectors calibrated by means of the piston stroke or the outlet diameter. The experiments were conducted in a bespoke test bed, and compressed air was used in lieu of gas fuel. The paper presents the test bed and discusses the method of determining the moment of the valve element's starting to move and stopping.
2014-10-13
Technical Paper
2014-01-2565
Harun Mohamed Ismail, Hoon Kiat Ng, Suyin Gan, Tommaso Lucchini
Abstract Modeling the combustion process of a diesel-biodiesel fuel spray in a 3-dimensional (3D) computational fluid dynamics (CFD) domain remains challenging and time-consuming despite the recent advancement in computing technologies. Accurate representation of the in-cylinder processes is essential for CFD studies to provide invaluable insights into these events, which are typically limited when using conventional experimental measurement techniques. This is especially true for emerging new fuels such as biodiesels since fundamental understanding of these fuels under combusting environment is still largely unknown. The reported work here is dedicated to evaluating the Adaptive Local Mesh Refinement (ALMR) approach in OpenFOAM® for improved simulation of reacting biodiesel fuel spray. An in-house model for thermo-physical and transport properties is integrated to the code, along with a chemical mechanism comprising 113 species and 399 reactions. Simulation results are compared against data from the Chalmers High-Pressure-High-Temperature Constant-Volume Combustion Chamber (HPHT-CVCC) experimental test-bed studies in terms of liquid-droplet penetration length, vapour penetration length and spray temporal distribution.
2014-10-13
Technical Paper
2014-01-2556
Hiroshi Tashima, Daisuke Tsuru
Abstract The discrete multi-component model for residual heavy fuel oil (HFO), developed in the mid-2000s, proved to be a simple but practical approximation in reproduction of the combustion process of HFO sprays on a couple of CFD simulation codes. The model succeeded in providing qualitative explanation about the spray and flame progression of HFO inside constant-volume chambers (CVC), but its practical use is still underway because of its higher calculation costs. Two-component HFO model, which was introduced relatively recently, separates every spray droplet virtually into two smaller droplets of each component to calculate their evaporation process separately. The model showed good agreement with the observation results on the various HFO spray behaviors in some visualized CVCs (VCVCs). However, all the above examinations were done only qualitatively not quantitatively since the heat releases measured in the visualizing-oriented chambers of large internal volume were difficult to detect accurately.
2014-10-13
Technical Paper
2014-01-2577
Arash Hamzehloo, Pavlos Aleiferis
Abstract International obligations to reduce carbon dioxide emissions and requirements to strengthen security of fuel supply, indicate a need to diversify towards the use of cleaner and more sustainable fuels. Hydrogen has been recommended as an encouraging gaseous fuel for future road transportation since with reasonable modifications it can be burned in conventional internal combustion engines without producing carbon-based tailpipe emissions. Direct injection of hydrogen into the combustion chamber can be more preferable than port fuel injection since it offers advantages of higher volumetric efficiency and can eliminate abnormal combustion phenomena such as backfiring. The current work applied a fully implicit computational methodology along with the Reynolds-Averaged Navier-Stokes (RANS) approach to study the mixture formation and combustion in a direct-injection spark-ignition engine with hydrogen fuelling. Hydrogen was issued into the combustion chamber by a six-hole side-mounted injector.
2014-10-13
Technical Paper
2014-01-2571
Nicolò Frapolli, Michele Bolla, Konstantinos Boulouchos, Yuri M. Wright
Abstract In this study, numerical simulations of in-cylinder processes associated to fuel post-injection in a diesel engine operated at Low Temperature Combustion (LTC) have been performed. An extended Conditional Moment Closure (CMC) model capable of accounting for an arbitrary number of subsequent injections has been employed: instead of a three-feed system, the problem has been described as a sequential two-feed system, using the total mixture fraction as the conditioning scalar. A reduced n-heptane chemical mechanism coupled with a two-equation soot model is employed. Numerical results have been validated with measurements from the optically accessible heavy-duty diesel engine installed at Sandia National Laboratories by comparing apparent heat release rate (AHRR) and in-cylinder soot mass evolutions for three different start of main injection, and a wide range of post injection dwell times. Good agreement with the experimental results is reported for the AHRR, while qualitative reproduction of in-cylinder soot mass evolutions have been obtained, the computed soot mass is considerably underestimated.
2014-10-13
Technical Paper
2014-01-2590
Yuanzhe Zhong, Sahil Sane
Abstract Electronic controls in internal combustion engines require an in-cylinder combustion sensor to produce a feedback signal to the ECU (Engine Control Unit). Recent research indicated that the ion current sensor has many advantages over the pressure transducer, related mainly to lower cost. Modified glow plugs in diesel engines, and fuel injectors in both gasoline and diesel engines can be utilized as ion current sensors without the addition any part or drilling holes in the cylinder head needed for the pressure transducer. Multi sensing fuel injector (MSFI) system is a new technique which instruments the fuel injector with an electric circuit to perform multiple sensing tasks including functioning as an ion sensor in addition to its primary task of delivering the fuel into the cylinder. It is necessary to fundamentally understand MSFI system. In this study the author will firstly explore the influence of piston motion (as one side of variable capacitance) on the ion sensor signal through modeling and simulation, and then look into the origin of the MSFI signal of fuel injection; and finally the author will look at how to analyze MSFI signal to duplicate the injection command profile for on-board diagnostics (OBD).
2014-10-13
Technical Paper
2014-01-2673
Amine Labreche, Fabrice Foucher, Christine Rousselle
Abstract In this work, the first injection of gasoline was maintained at 30 CAD Before TDC and the second one was swept between 10 CAD Before TDC to 5 CAD After TDC, in order to demonstrate the ideal positioning of the second injection. The results showed that when it was placed near TDC, low emissions, acceptable noise and acceptable efficiencies could be obtained. The effect of EGR, simulated by N2 addition, was also studied. As expected, globally the effect of the EGR rate was to delay the combustion phasing and to decrease NOx emissions. The optimal EGR dilution rate was found to be 30% with respect to the cycle-to-cycle variation criterion (< 5%). Increasing the dilution rate increased HC, CO and PM emissions, due to a considerable delay in combustion phasing caused by the reduction in the fuel reaction rate and the in-cylinder lack of oxygen when the EGR rate reached 30%. The impact of the fuel mass distribution between the two injections was also considered. This experiment showed that splitting the fuel mass equally between the injections is not the optimal solution.
2014-10-13
Technical Paper
2014-01-2681
Zufeng Bao, Xiaobei Cheng, Liang Qiu, Xingcun Luan
The performance of Partially Premixed Combustion (PPC) relies heavily on the proper mixing between the injected fuel and the in-cylinder gas mixture. This pre-mixing aims to eliminate over-rich regions where the mixture forms soot, and at the same time to avoid the NOX formation region by lowering the combustion temperature by introduction of a large amount of EGR The main effort of this paper focuses on investigating the characteristic of PPC combustion and a suitable injection strategy for achieving the PPC combustion mode. Two injection strategies (i.e. double and single injection) were investigated on a four-cylinder heavy-duty diesel engine operating at low, medium and high load conditions. Injection timing, injection pressure, the pilot-main interval, the pilot injected fuel mass, the ratio between the two pilot injection pulses for the double pilot injection as well as the comparison of single injection mode and multi-injection mode in acquiring PPC was swept to study the combustion behavior in terms of combustion heat release, combustion phase, emissions and different efficiencies.
2014-10-13
Technical Paper
2014-01-2680
Martin Tuner, Thomas Johansson, Hans Aulin, Per Tunestal, Bengt Johansson, William Cannella
This work investigates the performance potential of an engine running with partially premixed combustion (PPC) using commercial diesel engine hardware. The engine was a 2.01 SAAB (GM) VGT turbocharged diesel engine and three different fuels were run - RON 70 gasoline, RON 95 Gasoline and MK1 diesel. With the standard hardware an operating range for PPC from idle at 1000 rpm up to a peak load of 1000 kPa IMEPnet at 3000 rpm while maintaining a peak pressure rise rate (PPRR) below 7 bar/CAD was possible with either RON 70 gasoline and MK1 diesel. Relaxing the PPRR requirements, a peak load of 1800 kPa was possible, limited by the standard boosting system. With RON 95 gasoline it was not possible to operate the engine below 400 kPa. Low pressure EGR routing was beneficial for efficiency and combined with a split injection strategy using the maximum possible injection pressure of 1450 bar a peak gross indicated efficiency of above 51% was recorded. The split injection strategy showed in general higher efficiency and did lead to noticeable smoother engine operation with a reduction of combustion noise.
2014-10-13
Technical Paper
2014-01-2655
Qing-yao Hu, Di-ming Lou, Pi-qiang Tan, Zhi-yuan Hu, Yidong Fang
Abstract As a type of alternative fuel, biodiesel has advantages in reducing greenhouse gases and ensuring energy security. Compared with petroleum diesel, biodiesel has different lower calorific value, oxygen content and octane number that would raise problems when the unoptimized common rail diesel engine is fueled with biodiesel or its petroleum diesel blends. Among these problems, decreasing full load torque output and increasing NOx and BSFC are significantly important. Fuel injection parameter calibration and optimization experiments are carried out in an in-line 6-cylinder 8.82 liter turbocharged and intercooled common rail diesel, which is equipped with Denso ECD-U2 fuel injection system, SCR (Selective catalytic reduction) and DPF (diesel particulate filter). To avoid after-treatment apparatus' coupling influence and re-calibration, emission measure point is set in front of catalysts. The experiment adopts B20 biodiesel as test fuel. Firstly, this study re-calibrates the full load fuel injection quantity, makes full load torque output recovered to original status (unadjusted engine fueled with petroleum diesel) when a diesel engine is fueled with B20.
2014-10-13
Technical Paper
2014-01-2660
Jacek Hunicz, Pawel Kordos, Piotr Ignaciuk
Abstract A single cylinder research engine with negative valve overlap (NVO) and direct gasoline injection was run in a homogeneous charge compression ignition (HCCI) mode. The split fuel injection technique was used, where the first injection was applied during exhaust re-compression, while the second injection was applied at the beginning of main compression. The quantities of the fuel injected at the two timings were varied from the whole fuel injection during NVO to the whole fuel injection during the main compression event. These split fuel ratio sweeps were repeated both for a stoichiometric mixture and for a slightly lean mixture. In the study, NVO reactions were assessed via analysis of the exhaust-fuel mixture composition after the NVO period and referred to the main event combustion. The results showed that fuel injection during NVO resulted in the production of substantial quantities of auto-ignition promoting species, such as acetylene and formaldehyde. The quantities of species in the NVO mixture were affected by both the quantity of fuel injected during NVO and main event air excess ratio.
2014-10-13
Technical Paper
2014-01-2721
Robert H. Barbour, Robert Quigley, Avtar Panesar
Abstract Diesel powered vehicles have grown in popularity over the last 15 years due to the introduction of advanced, high pressure, direct injection fuel systems that enable improved emissions, power and a more desirable driving experience. However, such vehicles only perform optimally when the fuel system is in a clean condition. When deposits form inside the injector nozzle holes, a measurable deterioration in power is observed. The CEC F-98-08 Peugeot DW10 engine test was introduced in 2008 in order to evaluate the nozzle fouling propensity of fuels and the beneficial effect of deposit control additives. Papers have been published demonstrating such effects, in particular the propensity of zinc and biodiesel contaminants to cause injector fouling and the performance of additives in both deposit control (keep clean) and removal (clean-up) modes. While running such tests with an advanced, proprietary deposit control additive, both the fuel flow (kg/hr) and engine power (kW) measured with the additised fuel were higher than the corresponding measurements made at the start of test with clean injectors running on base fuel.
2014-10-13
Technical Paper
2014-01-2699
Moritz Schumacher, Michael Wensing
Abstract Hydrogen engines represent an economic alternative to fuel cells for future energy scenarios based on Liquid Organic Hydrogen Carriers (LOHC). This scenario incorporates LOHCs to store hydrogen from fluctuating renewable energy sources and deliver it to decentralised power generation units. Hydrogen engines were deeply investigated in the past decade and the results show efficiencies similar to CI engines. Due to the low energy density and tendency towards pre-ignition of hydrogen, the key element to reach high efficiency and a safe operation is a direct injection of the hydrogen. Because high injection pressure is not available in practical applications or would reduce the possible driving range, a low injection pressure is favourable. The low density leads to large flow cross sections inside the injector, similar to CNG direct injectors. So far, some research CNG and hydrogen low pressure direct injectors were investigated, but no commercial injector is available. The objective of this work is the development of a low pressure hydrogen direct injector, with the ability to run unlubricated in neat hydrogen and meeting the necessary flow rate for a stationary engine generating 7.5 kW per cylinder at 1500 rpm.
2014-10-13
Technical Paper
2014-01-2706
Haiqiang Liu, Lin Lu, Zhongjun Wang
Emission reduction and efficiency increase of two-stroke marine diesel engine depends on fuel injection, which affects in-cylinder combustion. This paper presents injection strategies varied results from simulation based on AVL BOOST and the experimental results and its validity was confirmed by actual measurements in a two-stroke engine during shop testing, which reveals the affect on performance and emission, as well as the corresponding concept analysis. This simulation enabled a more thorough investigation into engine performance features. In particular it provided a detailed examination of how changes in injection strategies impacted the combustion and ultimately engine performance. These results are summarized and based on these results, optimal injection strategies settings are suggested for balancing engine performance and NOx emissions.
2014-10-13
Technical Paper
2014-01-2708
Antonino La Rocca, David MacMillan, Paul Shayler, Michael Murphy, Ian Pegg
Abstract Cold idle operation of a modern design light duty diesel engine and the effect of multiple pilot injections on stability were investigated. The investigation was initially carried out experimentally at 1000rpm and at −20°C. Benefits of mixture preparation were initially explored by a heat release analysis. Kiva 3v was then used to model the effect of multiple pilots on in-cylinder mixture distribution. A 60° sector of mesh was used taking advantage of rotational symmetry. The combustion system and injector arrangements mimic the HPCR diesel engine used in the experimental investigation. The CFD analysis covers evolutions from intake valve closing to start of combustion. The number of injections was varied from 1 to 4, but the total fuel injected was kept constant at 17mm3/stroke. Start of main injection timing was fixed at 7.5°BTDC. The experimental study shows that increasing the number of pilots improves stability and leads to fuel preparation resulting in higher initial peak rate of heat release.
2014-10-13
Technical Paper
2014-01-2754
Yanfei Li, Hengjie Guo, Jian-Xin Wang, Hongming Xu
Abstract n-butanol has been recognized as a promising alternative fuel for gasoline and may potentially overcome the drawbacks of methanol and ethanol, e.g. higher energy density. In this paper, the spray characteristics of gasoline and n-butanol have been investigated using a high pressure direct injection injector. High speed imaging and Phase Doppler Particle Analyzer (PDPA) techniques were used to study the spray penetration and the droplet atomization process. The tests were carried out in a high pressure constant volume vessel over a range of injection pressure from 60 to 150 bar and ambient pressure from 1 to 5 bar. The results show that gasoline has a longer penetration length than that of n-butanol in most test conditions due to the relatively small density and viscosity of gasoline; n-butanol has larger SMD due to its higher viscosity. The increase in ambient pressure leads to the reduction in SMD by 42% for gasoline and by 37% for n-butanol. Based on the development of droplet velocity, it is found that the strong interaction between fuel jets could change the fuel distribution in the region close to the nozzle and this may be the joint effect of cavitation inside the nozzle and the vacuum near the nozzle caused by the high-speed fuel jets.
2014-10-13
Technical Paper
2014-01-2750
Tianyou Wang, Xiangzan Meng, Xiaochao Song, Ming Jia
Abstract It has been recognized that density, viscosity, surface tension, and volatility of liquid fuel are of great importance on the atomization and vaporization characteristics of biodiesel spray. This paper presents a comprehensive physical property prediction of biodiesel fuel for spray modeling with most recently developed property prediction models. The temperature-dependent properties of a soy methyl ester (SME) biodiesel were well predicted by the updated prediction methods. Then, the physical properties of the SME biodiesel were added into the KIVA-3V fuel library. By using the well predicted fuel properties, the spray behaviors of SME were successfully simulated by the KIVA-3V code under late-cycle post-injection, conventional diesel injection, and early-injection engine-relevant conditions. The simulation results agree reasonably well with the available experimental liquid penetrations under conditions of various ambient densities and temperatures. The different properties between diesel and SME fuels have pronounced effect on their different spray behaviors under the late-cycle post-injection conditions.
Viewing 1 to 30 of 5723