Browse Topic: Single cylinder engines

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Regulated Intake Air Boosting and Engine Downspeeding as a Viable Solution for Performance Improvement and Emission Reduction of a Single-Cylinder Diesel Engine03-15-02-00098/16/2021
The present work proposes a viable approach to develop single-cylinder diesel engines for the future by implementing regulated intake air boosting (RIAB) and engine downspeeding (ED) along with the well-established low compression ratio (LCR) approach. The investigations were conducted in a mass-production light-duty single-cylinder diesel engine initially equipped with a naturally aspirated (NA) intake system. By lowering the compression ratio (CR) and implementing the intake air boosting (IAB) using a belt-driven supercharger, the maximum brake mean effective pressure (BMEP) of the engine could be increased by 50%. More importantly, the improved performance could be achieved without violating the peak firing pressure (PFP) limits. However, a significant penalty was observed in the brake-specific fuel consumption (BSFC) at low-load operating points due to the additional power consumption of the IAB system. Hence, RIAB was implemented to optimize the boost pressure with respect to engine load to simultaneously reduce the BSFC and oxides of nitrogen (NOx) and soot emissions. Further, the increased full-load performance of the engine was leveraged to implement the ED approach that could reduce the operating speeds of the engine by 37.8%. It was observed that the benefits of downspeeding a supercharged engine are significantly high due to the simultaneous reduction of the frictional losses of the base engine and the power consumption of the supercharger. Overall, by combining the above concepts and the proven LCR approach, significant benefits could be achieved in fuel economy and exhaust emissions that are quantified for the regulatory Modified Indian Drive Cycle (MIDC) using a one-dimensional tool. The obtained results show a net reduction of 77.8% and 39.5% in the soot and NOx emissions, respectively. Moreover, a significant benefit of 14.8% could be achieved in the fuel economy. Thus the proposed approach can be used to develop single-cylinder diesel engines for the future to improve vehicle performance and comply with stringent emission regulations.
Vikraman, V., Krishnasamy, Anand, Ramesh, A.
7.0.105 - Implementation and Evaluation of Predictive Concepts for Hybrid Electric Vehicle Fuel Economy ImprovementSAE-PP-002812/4/2021
In the era where governmental agencies are perennially pushing automobile OEMs for reducing harmful emissions and customers looking for vehicles with better fuel economy values, it is imperative on the manufacturers to implement new technologies to appease them. Of the many new technologies, the most promising ones are the new control strategies/algorithms which predictively access the road condition, weather, traffic situations and help automobile to function in the most efficient mode. These control strategies/algorithms are termed as “Predictive technologies”. The most common way to assess the benefit of such new technologies is to simulate the vehicle behavior in conjunction with the existing complex control strategies of Hybrid vehicles in simulation environment. Since such technology finalization is done at the start of a vehicle program, the simulation engineers face numerous challenges like, non-availability of exact vehicle specifications, need for quicker evaluations of new concepts, faster simulation time and scalable models for extending the scope of project. To overcome such difficulties of concept creators while working with new technologies, a simulation environment has been created that is capable of providing quick results for new concepts. This paper intends to further explain the methodology of creating a simulation environment for a state-of-the-art technology like “Predictive Control Strategies” in Hybrid Vehicles, simulation setup based on VB and MS Excel platform for simulating the vehicle dynamics and Fuel Economy of a Full Hybrid vehicle and how complex control strategies can be Integrated into MS Excel Platform for a quick simulation.
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7.0.104 - Managing Distributed Systems Development through Model-Based E/E-Architecture DesignSAE-PP-002802/4/2021
This paper sketches a model based E/E-architecture analysis and design process for the development of distributed in-vehicle systems. Together with a model based system development, the sketched analysis and design process results in a cost-effective E/E-architecture which fulfills all the requirements for the developed in-vehicle system. As an example scenario, the integration of a new feature into a car, which requires integrating a new distributed function into the existing E/E-architecture of the car, is shown.
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Lubricating Oil, Aircraft Piston Engine (Ashless Dispersant)J1899_202010 (Current)10/28/2020
This SAE Standard establishes the requirements for lubricating oils containing ashless dispersant additives to be used in four-stroke cycle, reciprocating piston aircraft engines. This document covers the same lubricating oil requirements as the former military specification MIL-L-22851. Users should consult their airframe or engine manufacturers manuals for the latest listing of acceptable lubricants.
E-38 Aviation Piston Engine Fuels and Lubricants
Lubricating Oils, Aircraft Piston Engine (Non-Dispersant Mineral Oil)J1966_202010 (Current)10/28/2020
This SAE Standard establishes the requirements for nondispersant, mineral lubricating oils to be used in four-stroke cycle piston aircraft engines. This document covers the same lubricating oil requirements as the former military specification MIL-L-6082. Users should consult their airframe or engine manufacturers manuals for the latest listing of acceptable lubricants.
E-38 Aviation Piston Engine Fuels and Lubricants
Review of Additive Manufacturing for Internal Combustion Engine Components03-13-05-00399/9/2020
With highway vehicles using over 20% of the total energy consumption in the United States, making strides in improving their fuel economy will positively influence the nation’s environmental impact. One methodology to accomplish this outcome is by reducing vehicle weight. In this regard, since the internal combustion (IC) engine is a major contributor to the mass of an automobile, it is an ideal area to target. Prior efforts in this area include using alternative materials (e.g., aluminum or magnesium) to decrease weight. Here, additive manufacturing (AM) is an appealing option due to its freedom from typical manufacturing constraints and the ability to produce highly optimized designs using nonconventional powertrain materials (e.g., titanium). The use of AM has the potential to increase reliability, improve performance, decrease production cost, and possibly minimize the number of parts. Since metal-based AM is a relatively new area of manufacturing for IC engines, its use has been largely limited to research, motorsport, and luxury vehicle activities. Given its potential, this effort provides a review and summary of AM work completed in this field including design optimization, prototyping, tooling and indirect manufacturing, part production, and remanufacturing and repair for IC engine components.
Gray, Jamee, Depcik, Christopher
Engine Oil Performance and Engine Service Classification (Other than “Energy Conserving” or “Resource Conserving”)J183_202007 (Current)7/29/2020
This SAE Standard outlines the engine oil performance categories and classifications developed through the efforts of the Alliance of Automobile Manufacturers (Alliance), American Petroleum Institute (API), the American Society for Testing and Materials (ASTM), the Engine Manufacturers Association (EMA), the International Lubricant Specification Advisory Committee (ILSAC), and SAE. The verbal descriptions by API and ASTM, along with prescribed test methods and limits, are shown for active categories in Table 1 and obsolete categories in Table A1. Appendix A is thus a historical documentation of the obsolete categories. For purposes of this document, active categories are defined as those (a) for which the required test equipment and test support materials, including reference engine oils and reference fuels, are readily available, or for which the Category Life Oversight Group has established equivalencies between unavailable tests and newer, available tests; (b) which ASTM or the test developer monitors precision for all tests; and (c) which are available for licensing by API EOLCS at time of writing. The current processes for initiating new classifications were developed through the cooperative efforts of the Alliance, API, ASTM, EMA, ILSAC, and SAE. New ILSAC classifications are developed using the procedure defined in API 1509 Annex C. New API “C” categories are added using the procedure defined in API 1509 Annex D. New API “S” categories are added by the API Lubricants Group.
Fuels and Lubricants TC 1 Engine Lubrication
Infrared/Visible Optical Diagnostics of RCCI Combustion with Dieseline in a Compression Ignition Engine2020-01-05574/14/2020
Compression ignition engines are widely used for transport and energy generation due to their high efficiency and low fuel consumption. To minimize the environmental impact of this technology, the pollutant emissions levels at the exhaust are strictly regulated. To reduce the after-treatment needs, alternative strategies as the low temperature combustion (LTC) concepts are being investigated recently. The reactivity controlled compression ignition (RCCI) uses two fuels (direct- and port- injected) with different reactivity to control the in-cylinder mixture reactivity by adjusting the proportion of both fuels. In spite of the proportion of the port-injected fuel is typically higher than the direct-injected one, the characteristics of the latter play a main role on the combustion process. Use of gasoline for direct injection is attractive to retard the start of combustion and to improve the air-fuel mixing process. In this work, the influence of the direct-injected fuel properties on RCCI combustion mode is studied in an optical compression ignition engine. Gasoline fuel is injected in the intake manifold while a blend of gasoline and diesel (a.k.a. dieseline) is directly injected into the cylinder. Non-conventional optical diagnostics in the visible and infrared spectra are applied for the direct investigation of the in-cylinder phenomena during the injection and the combustion processes. A low-luminosity, mainly kinetically controlled combustion mode has been observed.
Sequino, Luigi, Mancaruso, Ezio, Monsalve-Serrano, Javier, Garcia, Antonio
Evaluation of Trajectory Based Combustion Control for Electrical Free Piston Engine2020-01-11494/14/2020
Previously, the authors have proposed a novel strategy called trajectory based combustion control for the free piston engine (FPE) where the shape of the piston trajectory between top and bottom dead centers is used as a control input to modulate the chemical kinetics of the fuel-air mixture inside the combustion chamber. It has been shown that in case of a hydraulic free piston engine (HFPE), using active motion control, the piston inside the combustion chamber can be forced to track any desired trajectory, despite the absence of a crankshaft, providing reliable starting and stable operation. This allows the use of optimized piston trajectory for every operating point which minimizes fuel consumption and emissions. In this work, this concept is extended to an electrical free piston engine (EFPE) as a modular power source. A dynamic model of a linear electrical free piston engine unit has been developed which consists of a single phase linear generator driven by a single cylinder engine. The linear generator unit not only provides the required electromagnetic force to ensure precise trajectory tracking for the piston in the combustion chamber, but also efficiently extracts the combustion energy to charge the battery. The concept has been experimentally validated in a hardware-in-loop setup. The combustion data corresponding to a predetermined piston trajectory is obtained from a controlled trajectory rapid compression and expansion machine (CT-RCEM) and the dynamic model is used to evaluate the electrical output corresponding to the combustion data.
Nahin, Minal, Tripathi, Abhinav, Sun, Zongxuan
Experimental Interpretation of Compression Ignition In-Cylinder Flow Structures2020-01-07914/14/2020
Understanding and predicting in-cylinder flow structures that occur within compression-ignition engines is vital if further optimisation of combustion systems is to be achieved. To enable this prediction, fully validated computational models of the complex turbulent flow-fields generated during the intake and compression process are needed. However, generating, analysing and interpreting experimental data to achieve this validation remains a complex challenge due to the variability that occurs from cycle to cycle. The flow-velocity data gathered in this study, obtained from a single-cylinder CI engine with optical access using high-speed PIV, demonstrates that significantly different structures are generated over different cycles, resulting in the mean flow failing to adequately reflect the typical flow produced in-cylinder. Additionally, this high level of variability is shown by the work to impact the assessment of turbulence throughout the cycle, influencing the values often used to validate mathematical models. The original work in this paper analyses experimental PIV data from the single cylinder engine, to characterise the differences between individual cycles’ bulk flow structures and the resultant turbulent fields. The analysis approach presented uses proper orthogonal decomposition (POD) and spatial filtering to interpret the progression of the flow structures and energy throughout compression, giving an understanding of the actual flow structures that are most likely to be produced in the engine. This analysis of the data provides a meaningful understanding of the nature of the bulk flow variations and how the turbulent field develops over a given cycle, from the intake stroke to the end of compression.
Knight, Tristan, Long, Edward, Yuan, Ruoyang, Garner, Colin, Hargrave, Graham
Sustainable Mobility Using Fuels with Pathways to Low Emissions2020-01-03454/14/2020
Regulations around the globe are driving the adoption of alternative fuels and vehicles through the implementation of stricter standards aimed at reducing carbon footprint and criteria emissions such as nitrogen oxides (NOx), particulate matter (PM), and total hydrocarbon (THC) emissions. Low emission zones have been implemented across Europe which restrict access by some vehicles with the aim of improving the air quality. The Paris Agreement on climate change declared governments’ intentions to reduce greenhouse gas (GHG) emissions as outlined in each country’s nationally determined contribution. Providing affordable energy to support prosperity while reducing environmental impacts, including the risks of climate change, is the dual challenge for the energy and transport industries. Development and deployment of low-emission liquid fuels and complementary engine hardware optimization could provide options to meet air quality as well as proposed, ambitious greenhouse gas (GHG) reduction targets. To take advantage of these potential benefits, these fuels must be compatible with the existing fleet and comply with current fuel standards. This work represents a joint effort by Porsche and ExxonMobil Research & Engineering Company. The goal of this work is to evaluate the potential of low-emission fuels to improve tailpipe emissions from in-use and new vehicle fleets. In this study, a number of fuels with various qualities and low-emissions potential were tested for resulting criteria emissions (NOx, PM, THC). A research Porsche single cylinder engine, including advanced engine combustion design elements, was used for combustion and emissions analysis. The tests were done under stationary and dynamic load as well as under different temperature conditions. Significant reductions to criteria emissions were obtained with the new fuel formulations, when compared to an existing European market fuel. Reductions of more than 90% in particulate emissions, 10 to 20% in NOx emissions, and up to 30% in THC emissions were achieved. Additionally, vehicle test results on both, a 1996 993 and a 2016 991.2 Porsche Carrera, with some selected fuels are presented and compared. Emission reduction potential with the 993 (23 years old vehicle) were similar to the 991.2 by using the low emission formulations showing the potential of the fuels in legacy vehicles, not equipped with gasoline particulate filters (GPF), to comply with current emission regulations. Furthermore, these fuels can be formulated to be compliant with existing European fuel regulations.
Kulzer, André Casal, Deeg, Hans Peter, Villforth, Jonas, Schwarzenthal, Dietmar, Schilling, Max, Barrientos, Eduardo, Kanach, Brianne, Lindner, Matthew
Emissions Benefits of Group Hole Nozzle Injectors under Conventional Diesel Combustion Conditions2020-01-03024/14/2020
This work explores the effectiveness of common rail fuel injectors equipped with Grouped Hole Nozzles (GHNs) in aiding the mixing process and reducing particulate matter (PM) emissions of Conventional Diesel Combustion (CDC) engines, while maintaining manageable Oxides of Nitrogen (NOx) levels. Parallel (pGHN), converging (cGHN) and diverging (dGHN) - hole GHNs were studied and the results were compared to a conventional, single hole nozzle (SHN) with the same flow area. The study was conducted on a single cylinder medium-duty engine to isolate the effects of the combustion from multi-cylinder effects and the conditions were chosen to be representative of a typical mid-load operating point for an on-road diesel engine. The effects of injection pressure and the Start of Injection (SOI) timing were explored and the tradeoffs between these boundary conditions are examined by using a response surface fitting technique, to identify an optimum operating condition. It is found that the GHNs offer a significant PM benefit along with a negligible NOx effect and that the cGHN and dGHN nozzles give the best PM performance at two different conditions. Furthermore, it was observed that GHN effects are dominated by injection pressure effects as the injection pressure was increased, with the differences between GHNs and the SHN becoming negligible above 1500 bar. A strong dependence on the injection timing was also seen, with the differences between GHNs and SHN being strongest when the injection occurs at, and just after, top dead center, suggesting that an optimum between power, emissions and injection pressure can be attained through GHN use in the medium duty sector.
Babu, Aravindh, Staaden, Daniel, Kokjohn, Sage, Dempsey, Adam
A Study of Dynamic Combustion Control for High Efficiency Diesel Engine2020-01-02974/14/2020
The subject of this paper is to discuss the use of advanced combustion controls of direct injection diesel engines, to achieve simultaneous improvements in thermal efficiency while maintaining minimum pollutant emissions. In recent years, the emissions produced in the transportation sector are becoming increasingly scrutinized, leading to significantly strengthened emissions legislations with regard to NOx and CO2, especially under Real Driving Emission (RDE) conditions. Therefore, diesel combustion improvements are key to overcoming these challenges. This paper reports the following two innovative Diesel combustion control technologies to realize the objectives mentioned above. 1 Combustion improvement by accurate Combustion Rate Shaping (CRS), CRS enables direct control of in-cylinder pressure trace and heat release rate. A newly developed DENSO fuel delivery injector with strengthened solenoid magnetic force enables injection flexibility by fast opening and multiple close-coupled injections, resulting in a reduction in soot, nitro-oxides and fuel consumption. 2 Reduction of calibration effort by Closed Loop Combustion Control (CLCC) with only two control parameters, the target in-cylinder pressure trace is predetermined. The feedforward combustion model calculates the required injection fuel trace to achieve the target pressure trace. The resulting pressure is measured by a cylinder pressure sensor, which is used as feedback to control the target metric. Those technologies are key features for advanced engine performance. Multi-cylinder Diesel engine experiments confirmed lower in-cylinder temperature in the condition of advanced combustion timing toward Top Dead Center (TDC), and showed remarkable improvement of NOx - CO2 trade-off in transient driving cycle; Worldwide Harmonized Light vehicles Test Cycle (WLTC).
Kuronita, Tokuji, Sakai, Takuya, Queck, Dirk, Puts, Ron, Visser, Sebastian, Herrmann, Olaf, Nishijima, Yoshiaki
Investigation of Reynolds Stress Model for Complex Flow Using CONVERGE2020-01-11044/14/2020
The Reynolds stress turbulence model (RSM) has been developed to go beyond the Boussinesq hypothesis and to improve turbulence modeling of flows with significant mean streamline curvature and secondary flow. In this paper the RSM in commercial CFD software CONVERGE is tested for its performance and robustness when applying to complex flows. Several validation cases including flow over flat plate, vortex combustor, diesel engine spray and combustion were selected to test the RSM. The swirling flow in vortex combustor, non-reacting but vaporizing ECN Spray A (free jet) and Sandia small bore diesel engine case are used to demonstrate the benefits of the RSM over the widely used RNG k-epsilon model without model tuning. The vortex combustor case shows the RSM can provide good prediction for strong swirling flow. ECN spray A case was used to demonstrate that the RSM can accurately predict the liquid and vapor penetration lengths of a free jet under diesel engine conditions. Accurate spray-wall interaction is quite important for modern diesel engine combustion where piston bowls facilitate and rely on spray-wall interactions for better combustion efficiency and emission reduction. It is found that the RSM can improve the prediction of cylinder pressure compared to the RNG k-epsilon model using the small-bore diesel engine case. All test results show that the RSM is robust and its computational overhead compared to the RNG k-epsilon model ranges from 17% to 78% for test cases.
Liu, Zhenping, Wijeyakulasuriya, Sameera, Mashayekh, Alireza, Chai, Xiaochuan
Performance of a Printed Bimetallic (Stainless Steel and Bronze) Engine Head Operating under Stoichiometric and Lean Spark Ignited (SI) Combustion of Natural Gas2020-01-07704/14/2020
Additive manufacturing was used to fabricate a head for an automotive-scale single-cylinder engine operating on natural gas. The head was consisted of a bimetallic composition of stainless steel and bronze. The engine performance using the bimetallic head was compared against the stock cast iron head. The heads were tested at two speeds (1200 and 1800 rpm), two brake mean effective pressures (6 and 10 bar), and two equivalence ratios (0.7 and 1.0). The bimetallic head showed good durability over the test and produced equivalent efficiencies, exhaust temperatures, and heat rejection to the coolant to the stock head. Higher combustion temperatures and advanced combustion phasing resulted from use with the bimetallic head. The implication is that with optimization of the valve timing, an efficiency benefit may be realized with the bimetallic head.
Kass, Michael, Biruduganti, Munidhar, Kaul, Brian, Storey, John, Longman, Douglas, Elliott, Amelia, Siddel, Derek
Effects on Cycle-to-Cycle Variations and Knocking Combustion of Turbulent Jet Ignition (TJI) with a Small Volume Pre-Chamber2020-01-11194/14/2020
Turbulent jet ignition (TJI) has the advantages of improving burning rates and expanding lean burn limitations of gasoline engines. Based on a single cylinder engine, combustion process with different ignition methods, including single spark ignition, twin spark ignition, one-hole TJI and seven-hole TJI, are studied in this work. Experiments are carried out under conditions with different air/fuel equivalence ratios and different engine loads. Results show that the cycle-to-cycle variations of TJI combustion, which is evaluated by coefficient of variations (CoV) of IMEP and CoV of peak pressure, are obviously reduced due to the fast burning rate induced by the jet flame, and one-hole TJI combustion has the best combustion stability, especially for reducing the CoV of peak pressure. Furthermore, under full-load conditions, pressure oscillations are observed in TJI combustion, and the intensity distribution is different from that in SI combustion, which means that the roots causing the pressure oscillations of TJI and SI are different. Pressure oscillations in TJI combustion are caused by the local fast burning rate of the hot jets, while the pressure oscillations of SI are caused by end-gas auto-ignition, which randomly happens during combustion. Under TJI knock condition, excellent combustion stability and great auto-ignition consistency can still be achieved. Considering these features of TJI combustion, a new combustion concept, jet induced compression ignition (JICI), and a different ignition method, spark combined jet ignition (SCJI), are proposed in order to organize combustion with high efficiency, stability and controllability.
Hua, Jianxiong, Zhou, Lei, Gao, Qiang, Feng, Zhonghui
Use of Butanol Blend Fuels on Diesel Engines - Effects on Combustion and Emissions2020-01-03334/14/2020
Butanol, a four-carbon alcohol, is considered in the last years as an interesting alternative fuel, both for Diesel and for gasoline application. Its advantages for engine operation are: good miscibility with gasoline and diesel fuels, higher calorific value than ethanol, lower hygroscopicity, lower corrosivity and possibility of replacing aviation fuels. Like ethanol, butanol can be produced as a biomass-based renewable fuel or from fossil sources. In the research project, DiBut (Diesel and butanol) addition of butanol to Diesel fuel was investigated from the points of view of engine combustion and of influences on exhaust aftertreatment systems and emissions. One investigated engine (E1) was with emission class “EU Stage 3A” for construction machines, another one, engine (E2) was HD Euro VI. The most important findings are: with higher butanol content, there is a lower heat value of the fuel and there is lower torque at full load. With Bu30 the conversion rates of CO and HC in the oxidation catalyst (DOC) are slightly lower, light-off temperatures are a little higher and NO2 production is lower. The PM-emissions with Bu30 are lower, so the soot loading of DPF takes a longer time. No impacts of Bu30 on NOx reduction rates of the SCR-system and on the non-legislated gaseous emission components were found. The operation of engine (E1) with Bu30 (30% vol butanol in fuel) was instable at lower part load due to the lower Cetane Number of the blend fuel. The electronic control system of the engine (E2) compensated very well the varying properties of fuels up to Bu30. For both investigated engines, the butanol rate (Bu30) can be considered as a limit for a problem-free engine starting and operation.
Engelmann, Danilo, Czerwinski, Jan, Nauroy lng, Hervé, Comte, Pierre, Hüssy lng, Andreas
CO2 Neutral Heavy-Duty Engine Concept with RCCI Combustion Using Seaweed-based Fuels2020-01-08084/14/2020
This paper focusses on the application of bioalcohols (ethanol and butanol) derived from seaweed in Heavy-Duty (HD) Compression Ignition (CI) combustion engines. Seaweed-based fuels do not claim land and are not in competition with the food chain. Currently, the application of high octane bioalcohols is limited to Spark Ignition (SI) engines. The Reactivity Controlled Compression Ignition (RCCI) combustion concept allows the use of these low carbon fuels in CI engines which have higher efficiencies associated with them than SI engines. This contributes to the reduction of tailpipe CO2 emissions as required by (future) legislation and reducing fuel consumption, i.e. Total-Cost-of-Ownership (TCO). Furthermore, it opens the HD transport market for these low carbon bioalcohol fuels from a novel sustainable biomass source. In this paper, both the production of seaweed-based fuels and the application of these fuels in CI engines is discussed. Ethanol and butanol are considered as the most viable fuels derived from seaweed. The potential of these fuels has been evaluated for the dual-fuel RCCI mode regarding efficiency and NOx emissions. The operating conditions that have been varied are mainly the fuel blend ratio (BR), fuel injection timing, and EGR rate on both a HD single-cylinder and on a HD multi-cylinder engine. The results for E85/diesel-RCCI demonstrate that CI engine-like efficiencies are feasible. The gross Indicated Thermal Efficiency (ITE) reaches up to 52% and 46.5% using E85 in a single-cylinder and a multi-cylinder engine, respectively. The first results using biomass based butanol show greater difficulty in realizing targeted efficiencies on the multi-cylinder engine due to the higher fuel reactivity and higher boiling temperature than ethanol. The gross ITE reaches up to 51.6% and 38.5% using butanol in a single-cylinder and a multi-cylinder engine, respectively. The demonstrated potential of seaweed-based fuels is an important driver for upscaling the production process of these fuels. Furthermore, future development activities will focus on improving the brake thermal efficiency of the RCCI engine running on seaweed-based fuels. Improving the low reactivity fuel-air mixture preparation will be key to achieve this.
Seykens, Xander, Bekdemir, Cemil, Han, Jinlin, Willems, Robbert, Van Hal, Jaap
Measurement of Fuel Distribution in a Small PFI Spark-Ignition Engine Using Tracer PLIF2020-01-07864/14/2020
The distribution of fuel-air mixture inside the engine cylinder strongly influences the combustion process. Planar laser-induced fluorescence (PLIF) is commonly used for fuel distribution measurement, however, it is mostly reported on moderate- to large-sized engines. In the present work, PLIF is applied to measure the fuel distribution inside the cylinder of a small, four-stroke, port-fuel-injection (PFI), spark-ignition engine with displacement volume of 110 cm3. Iso-octane was used as the base fuel, and 3-pentanone (15% by volume) was added as a fluorescent tracer in the base fuel. The effect of equivalence ratio, considering ϕ = 1.2, 1.0, and 0.8, on in-cylinder fuel distribution was studied with low throttle opening of 25% at 1200 rpm. PLIF images were recorded at different crank angle degrees during both intake and compression strokes over a swirl measurement plane located at the TDC position. It was found that the fuel stratification was present from intake to even late compression. Also, no significant change in fuel distribution patterns was noted at different crank angle degrees for a given operating condition. Instantaneous PLIF images of the fuel distribution at 330 CAD during compression also showed a considerable variation from one cycle to the next. As expected, the fluorescence signal intensity was increased with the increase in equivalence ratio. Results also showed that the fuel distribution was much more noticeable near the diametrically opposite location to the spark plug on the tested engine, and continued to exist till late compression (i.e. 330 CAD).
Garg, Shubham, Mittal, Mayank, Sahu, Srikrishna, Lakshminarasimhan, V
Is the “K Value” of an Engine Truly Fuel Independent?2020-01-06154/14/2020
The octane appetite of an engine is frequently characterised by the so-called K value. It is usually assumed that K is dependent only on the thermodynamic conditions in the engine when knock occurs. In this work we test this hypothesis: further analysis was conducted on experimental results from SAE 2019-01-0035 in which a matrix of fuels was tested in a single cylinder engine. The fuels consisted of a relatively small number of components, thereby simplifying the analysis of the chemical kinetic proprieties. Through dividing the original fuel matrix into subsets, it was possible to explore the variation of K value with fuel properties. It was found that K value tends to increase slightly with RON. The explanation for this finding is that higher RON leads to advanced ignition timing (i.e. closer to MBT conditions) and advanced ignition timing results in faster combustion because of the higher pressures and temperatures reached in the thermodynamic trajectory. The Livengood-Wu integral can be employed to show that for higher octane fuels, knock onset occurs at a higher temperature and pressure. Thus, the fuel octane quality can impact the thermodynamic trajectory in the engine.
Cracknell, Roger, Kassai, Masaharu, Shiraishi, Taisuke, Festa, Andrea, Gail, Sandro, Aradi, Allen, Shibuya, Masahiko
The Potential of Gasoline Fueled Pre Chamber Ignition Combined with Elevated Compression Ratio2020-01-02794/14/2020
Pre-chamber ignition is a method to simultaneously increase the thermal efficiency and to meet ever more stringent emission regulations at the same time. In this study, a single cylinder research engine is equipped with a tailored pre-chamber ignition system and operated at two different compression ratios, namely 10.5 and 14.2. While most studies on gasoline pre-chamber ignition employ port fuel injection, in this work, the main fuel quantity is introduced by side direct injection into the combustion chamber to fully exploit the knock mitigation effect. Different pre-chamber design variants are evaluated considering both unfueled and gasoline-fueled operation. As for the latter, the influence of the fuel amount supplied to the pre-chamber is discussed. Due to its principle, the pre-chamber ignition system increases combustion speeds by generating enhanced in-cylinder turbulence and multiple ignition sites. This property proves to be an effective measure to mitigate knocking effects. It is shown that less spark retard compared to conventional spark ignition allows to exploit the efficiency benefit of elevated compression ratios also in high load operation for stoichiometric mixtures. Furthermore, auxiliary fueling of the pre-chamber enables ultra-lean combustion (λ=2.0) with very low NOx emission levels. Apart from decreased throttling losses lean burn assists to further suppress knocking in case of elevated compression ratios. Finally, it is demonstrated that the combination of ultra-lean combustion and elevated compression ratio leads to a significant improvement of the indicated efficiency with peak values of about 43 %. Higher PN emissions in low load and increased heat losses remain challenges of the used pre-chamber ignition system.
Stadler, Andreas, Sauerland, Henning, Härtl, Martin, Wachtmeister, Georg
A Real-Time Capable and Modular Modeling Concept for Virtual SI Engine Development2020-01-05774/14/2020
Spark Ignited (SI) combustions engines in combination with different degrees of hybridization are expected to play a major role in future vehicle propulsion. Due to the combustion principle and the related thermodynamic efficiency, it is especially challenging to meet future CO2 targets. The layout and optimization of the overall system requires novel methods in the development process which feature a seamless transition between real and virtual prototypes. Herein, engine models need to predict the entire engine operating range in steady-state and transient conditions and must respond to all relevant control inputs. In addition, the model must feature true real-time capability. This work presents a holistic and modular modeling framework, which considers all relevant processes in the complex chain of physical effects in SI combustion. The basis is a crank-resolved cylinder model which describes gas exchange and compression to determine the thermodynamic state and turbulence conditions at spark-advance. Ignition and flame front combustion are modeled by a mechanistic, quasi-dimensional combustion model with a detailed consideration of combustion chamber geometry for flame-wall interaction. Cycle-to-cycle variations are imposed in a semi-empirical manner in order to provide realistic boundary conditions for the thermo-chemical knock model. The models are validated against engine measurements for a passenger car sized TGDI engine in a wide range of operating conditions covering the entire engine map. Emphasis is put on comparing pressure and heat release traces, not only for the mean cycle, but for the range of stochastic variations of 100 measured cycles. The validation results confirm a good level of agreement between measured and simulated results. To demonstrate capabilities of the proposed modeling concept, a model-based optimization is performed in a computational study, aiming at an optimization of engine efficiency under knocking constraints. The study examines two motoric measures, namely water injection and variable compression ratio. Finally, the optimized model runs in a transient drivecycle simulation. The test is performed on a HiL system to prove the model’s real-time capability.
Poetsch, Christoph, Wurzenberger, Johann, Katrasnik, Tomaz
Impact of Multiple Injection Strategies on Performance and Emissions of Methanol PPC under Low Load Operation2020-01-05564/14/2020
There is growing global interest in using renewable alcohols to reduce the greenhouse gases and the reliance on conventional fossil fuels. Recent studies show that methanol combined with partially premixed combustion provide clear performance and emission benefits compared to conventional diesel diffusion combustion. Nonetheless, high unburned hydrocarbon (HC) and carbon monoxide (CO) emissions can be stated as the main PPC drawback in light load condition when using high octane fuel such as Methanol with single injection strategy. Thus, the present experimental study has been carried out to investigate the influence of multiple injection strategies on the performance and emissions with methanol fuel in partially premixed combustion. Specifically, the main objective is to reduce HC, CO and simultaneously increase the gross indicated efficiency compared to single injection strategy. The work was performed with a single cylinder heavy duty engine, operated at 4 bar gross indicated mean effective pressure, and an engine speed of 1200 rpm. Double and triple injections were implemented with varying dwells, injection timings and fuel mass proportions. The experimental results were analyzed with a merit function to select the optimal injection strategy. Concerning emissions, the constraints for the merit function were based on the EURO VI limits, while the highest gross indicated efficiency for single injection was used to define the performance constraint. The results revealed that with proper dwell and mass proportion, multiple injection strategies can improve the gross indicated efficiency and reduce the emissions compare to single injection strategy.
Aziz, Amir, Garcia, Antonio, Pinto Dos Santos, Clarisse, Tuner, Martin
Nonlinear Identification Modeling for PCCI Engine Emissions Prediction Using Unsupervised Learning and Neural Networks2020-01-05584/14/2020
Premixed charged compression ignition (PCCI) is an advanced combustion strategy, which has the potential to achieve ultra-low nitrogen oxide and soot emissions at high thermal efficiencies. PCCI combustion is characterized by a complex nonlinear chemical-physical process, which indicates that a physical description involves significant development times and also high computation cost. This paper presents a method to use cylinder pressure data and engine operations parameters for prediction of PCCI engine emissions by unsupervised learning and nonlinear identification techniques. The proposed method first uses principal component analysis (PCA) to reduce the dimension of the cylinder-pressure data. Based on the PCA analysis, a multi-input multi-out model was developed for nitrogen oxide and soot emission prediction by multi-layer perceptron (MLP) neural network. Before the training process, a second principal component analysis was done to reduce the input dimension with hyper-parameters thereby reducing memory requirements of the models. The algorithm is applied to an experimental data set from a single-cylinder light-duty engine with piezo injection system. By comparing the model predictions with experimental results, it is shown that the neural network coupling with the unsupervised learning method can successfully capture the nonlinear relationship between the state parameters and the emissions of PCCI combustion system.
Pan, Wang, Korkmaz, Metin, Beeckmann, Joachim, Pitsch, Heinz
Analysis of In-Cylinder Flow and Cycle-to-Cycle Flow Variations in a Small Spark-Ignition Engine at Different Throttle Openings2020-01-07934/14/2020
Flow variations from one cycle to the next significantly influence the mixture formation and combustion processes in engines. Therefore, it is important to understand the fluid motion and its cycle-to-cycle variations (CCVs) inside the engine cylinder. Researchers have generally investigated the cycle-to-cycle flow variations in moderate- to large-sized engines. In the present work, we have performed the flow measurement and analysis in a small spark-ignition engine. Experiments are conducted in an optically accessible, single-cylinder, port-fuel-injection engine with displacement volume of 110 cm3 at different throttle openings (i.e. 50% and WOT) using particle image velocimetry. Images are captured at different crank angle positions during both intake and compression strokes over a tumble measurement plane, bisecting the intake and exhaust valves and passing through the cylinder axis. The histograms of vorticity are used as a metric for the quantification of cycle-to-cycle flow variations. It is found that for wide-open (i.e. 100%) throttle, cycle-to-cycle variations first increased from 76 CAD (after TDC of intake) to a maximum value at about 118 CAD, and then decreased during the late intake and early compression to a minimum at about 232 CAD for measured crank angle degrees. Results also showed that cycle-to-cycle variations for 50% and wide-open throttle conditions were comparable for all measured CADs. This similarity between 50% and WOT conditions based on histograms of vorticity was found to be consistent with turbulent kinetic energy (TKE) results. In addition, CFD simulations are also performed using CONVERGE software, and a great resemblance is observed between CFD simulations and experimental results for both 50% and WOT conditions.
Alam, Afaque, Mittal, Mayank, Lakshminarasimhan, V
Smart Spark Plug for Proper Combustion Timing in Gasoline Engines and Detection of Misfire and Knock2020-01-07904/14/2020
Internal combustion engines are required to achieve production goals of better fuel economy, improved fuel economy and reduced emissions in order to meet the current and future stringent standards. To achieve these goals, it is essential to control the combustion process using an in-cylinder combustion sensor and a system that produces a feedback signal to the ECU. This paper presents a system based on combustion ionization that includes a newly developed smart spark plug capable of sensing the whole combustion process. A unique feature of the smart spark plug system is its ability to sense the early stages of combustion and produce a complete ion current signal that accurately identifies and can be used for the control of the start of combustion. This is not the case for the conventional spark plug where the start of combustion cannot be determined from the ion current signal because its early part is distorted or completely overshadowed by the strong electromagnetic field produced by the spark ignition system. In addition to its ability to detect and control the start of combustion, the new system can detect other combustion related problems such as misfire and knock. The paper describes the construction of the smart spark plug and compares its ion current signal with that produced by the conventional spark plug. The new system, developed and patented by IC LLC, can be applied in current production spark ignition engines as well as for the development of future advanced concepts engines.
Assaad, Kamal, Henein, Naeim A.
Combustion System Development in GAC Turbocharged Miller GDI Engine with 0.5L/Cylinder2020-01-08384/14/2020
GAC Group has set up two modular engine families, G and GS, for various vehicle classes equipping demands. G family engines, which have already gone through three generations, target for the higher torque and power, the lower fuel consumption and the future strict emission standards. For the latest generation, new technologies were added to achieve the development goals based on the previous modular engines. For example, miller combustion cycle with increased compression ratio is introduced in the newer engine combustion system. Additional key technologies such as 350 bar injection system and high tumble intake ports are also applied. The combustion system development, which established on the GAC Combustion Controlling System (GCCS), was facilitated by integrated use of advanced optical measurements and computational fluid dynamics for improving the in-cylinder flow, fuel sprays and the interaction between them. This paper presents the analytical work done to develop the combustion systems. A higher tumble intake port design enhances the motion in intake process, the well-organized in-cylinder flow may bend over the sprays and keep them from interacting with the cylinder. The redesigned spray structure and piston bowl could do good for a reasonable mixture formation, which decreases the soot and HC emissions, especially for the cold-start conditions. Results from engine test bench experiments show that all of the new generation of the 0.5L/cylinder turbocharged DI gasoline engines can meet the strict legislation for nearest or some considerable time to come.
Li, Yuhuai, Chen, Hong, Du, Jiakun, Wu, Jian, Zhan, Wenfeng, Wu, Guangquan, Lin, Sicong, Shao, Fake
Experimental and Numerical Assessment of Active Pre-chamber Ignition in Heavy Duty Natural Gas Stationary Engine2020-01-08194/14/2020
Gas engines (fuelled with CNG, LNG or Biogas) for generation of power and heat are, to this date, taking up larger shares of the market with respect to diesel engines. In order to meet the limit imposed by the TA-Luft regulations on stationary engines, lean combustion represents a viable solution for achieving lower emissions as well as efficiency levels comparable with diesel engines. Leaner mixtures however affect the combustion stability as the flame propagation velocity and consequently heat release rate are slowed down. As a strategy to deliver higher ignition energy, an active pre-chamber may be used. This work focuses on assessing the performance of a pre-chamber combustion configuration in a stationary heavy-duty engine for power generation, operating at different loads, air-to-fuel ratios and spark timings. The engine was originally a 6-cylinder compression ignition engine which is here employed as a single cylinder engine and then suitably modified to host the pre-chamber (with its natural gas injection system and spark plug) with a new bowl piston to decrease compression ratio. A 0D model is built to make a thermodynamic analysis to characterize the local conditions in the pre-chamber before spark timing (temperature, pressure and composition), based on a compressible nozzle equation for the mass transfer between the chambers and a simplified Woschni model for the pre-chamber’s heat transfer. A mathematical expression was found to describe the relationship between the local conditions and the early stage of the combustion. Experimental results showed the beneficial effect of spark delay and mixture leaning for the reduction of NOx emissions, while CO, unburned hydrocarbons and engine performance see improvement with lower air-to-fuel ratios and spark advance.
Onofrio, Gessica, Li, Changle, Garcia Valladolid, Pablo, De La Morena, Joaquin, Garcia, Antonio, Tunestal, Per, Beatrice, Carlo
Assessment of the Ignition System Requirement on Diluted Mixture Spark Engines2020-01-11164/14/2020
In order to face the new challenges, spark ignition engines are evolving by following some strategies and technologies. Among them, alternative combustion processes based on the dilution of the homogeneous mixture, either with fresh air or with Exhaust Gas Recirculation (EGR), are being explored. In a higher or lower extent, these changes modify in-cylinder thermodynamic conditions during the engine operation (pressure, temperature and gas composition) thus conditioning the spark ignition system requirements that will have to evolve to become more reliable and powerful. In this framework, an experimental study on the effect of the key in-cylinder conditions on the ignition system performance has been carried out in a single-cylinder spark-ignition (SI) research engine. The study includes EGR, lambda and energizing time sweeps to assess the behavior of the engine in different operating conditions. Furthermore, various Insulated-Gate Bipolar Transistors (IGBT) and spark plugs have been tested to assess the influence of these components on the ignition process at high diluted mixtures. Conclusions show that diluted mixtures (with EGR or lambda), even though they require more spark energy to achieve a stable combustion, have up to 4% benefit on indicated efficiency, providing that the combustion propagates adequately. However, at high diluted conditions the combustion is compromised, so two different approaches were explored to improve it. Whilst it was checked that increasing the clamping value of the IGBT does not necessarily imply a better combustion in all scenarios, the increment of the electrodes gap of the spark plug would require higher clamping voltage at the IGBT, and it would have a slight benefit on efficiency providing that the rest of components, in particular the coil, are adequate.
Molina, Santiago, Martin, Jaime, Novella, Ricardo, Gomez-Soriano, Josep, Padilla, Jose
Spatial Correlation and Length Scale Analysis of the Near-Wall Flow and Temperature Distribution of an Internal Combustion Engine2020-01-11064/14/2020
Accurate predictions of in-cylinder heat transfer processes of internal combustion engines (ICEs) require a comprehensive understanding of the boundary layer development in the near-wall region (NWR). To add to the understanding of this NWR, this study uses experimental data of near-wall measurements collected in the transparent combustion chamber (TCC-III) engine via Particle Image Velocimetry (PIV) and toluene Planar Laser Induced Fluorescence (PLIF) thermometry. These near-wall flow and temperature distributions were compared with large-eddy simulations (LES) and 3-D conjugate heat transfer (CHT) modeling with a commercial CFD code (CONVERGE). The implementation of the conjugate heat transfer model enables capturing the variability in wall heat transfer as observed in the measurements. The results of this study is based on the analysis of ensemble averaged, standard deviation, PDFs of the fluctuating values, the spatial correlation of the velocity and temperature fluctuations, and their integral length scales. The LES CHT results do not compare well with the near-wall experimental velocity and temperature fields, which could be due to many factors including the wall models used in the study. The simulations are able to capture the trend of the spatial correlations, but not their magnitude. LES results show that length scales of velocity and temperature, and their spatial distribution, change significantly throughout the engine cycle, which directly affects the thermal gradients at the wall and therefore overall engine heat transfer.
Wu, Angela, Alzuabi, Mohammad K., Sick, Volker
Experimental Investigation of the Influence of Ignition System Parameters on Combustion in a Rapid Compression-Expansion Machine2020-01-11224/14/2020
Lean burn combustion concepts with high mean effective pressures are being pursued for large gas engines in order to meet future stringent emission limits while maintaining high engine efficiencies. Since severe boundary conditions for the ignition process are encountered with these combustion concepts, the processes of spark ignition and flame initiation are important topics of applied research, which aims to avoid misfiring and to keep cycle-to-cycle combustion variability within reasonable limits. This paper focuses on the fundamental investigation of early flame kernel development using different ignition system settings. The investigations are carried out on a rapid compression-expansion machine in which the spark ignition process can be observed under engine-like pressure and excess air ratio conditions while low flow velocities are maintained. The schlieren setup for high-speed optical investigations of the area of the spark plug electrodes is described and a suitable post-processing routine is introduced. The influence of different spark current durations on early flame kernel formation is investigated using a modulated capacitive discharge ignition (MCDI) system. The outcomes reveal that a short spark current duration results in a slower increase and higher standard deviation of the flame area during the early phase of combustion. Moreover, stable flame initiation appears to require a minimum spark current duration. The methodology introduced in this paper will be applied in detailed investigations of other spark plug geometries and ignition settings in order to shed more light on the ignition of lean mixtures.
Kiesling, Constantin, Pirker, Gerhard, Tilz, Anton, Oppl, Thomas, Nickl, Andreas, Wimmer, Andreas, Meyer, Georg
Optical Diagnostics of Isooctane and n-Heptane Isobaric Combustion2020-01-11264/14/2020
Isobaric combustion has demonstrated a great potential to reach high thermodynamic efficiency in the advanced Double Compression Expansion Engine (DCEE) concept. It appears as one of few viable choices for applications with high-pressure combustion. At these conditions, releasing heat at a constant pressure minimizes the peak in-cylinder pressure and, hence, mitigates excessive mechanical stress on the engine. This study focuses on the effect of fuels on the multiple-injection isobaric combustion. A single-cylinder heavy-duty engine was utilized to test and compare the isobaric combustion with pure isooctane and n-heptane fuels. The engine was equipped with an optical piston to allow a bottom-view of the combustion chamber. The interactions of multiple injections and the combustion behavior were studied using high-speed acquisition of chemiluminescence. The examined isobaric cases have a peak pressure of 70 bar. For cases with high soot luminosity, a short band-pass filter was used to avoid image saturation. Fuels with short ignition delay time such as n-heptane are usually used for isobaric applications as they offer good controllability of injections. However, the study herein demonstrates that isobaric combustion can be achieved even with high octane number fuels such as isooctane. The dwell time between injections is much larger for isooctane, which allows enhanced mixing of the fuel jets with air and thus a partially premixed combustion behavior. The high-speed imaging demonstrated evidence of flame extinguishing during the sequential injection of n-heptane. This contributes to the staging of the heat release rate.
Al Ramadan, Abdullah S., Nyrenstedt, Gustav, Ben Houidi, Moez, Johansson, Bengt
A Novel Design of Engine Misfire Detection System Suitable for Small Capacity S.I. Engine for Two Wheeled Vehicle2020-01-02674/14/2020
As per the OBD II regulations, it is essential to detect and monitor the misfire event in an I.C. engine. Misfiring of an I.C. engine affects the quality of combustion and degrades the performance of catalyst convertor which can lead to an increase of emissions. Misfire event can be categorized as partial or complete, based on amount of combustion occurred during that particular engine cycle. Most of the production engine for non-two wheeler vehicle identifies misfire by monitoring angular acceleration of the engine crank-shaft. However, single cylinder engine with lower capacity (less than 300 cubic centimeter) provides challenges to identify misfire due to low mechanical inertia of the I.C. engine using the same approach. The problem of misfire identification for this category of I.C. engine turn out to be more challenging due to presence of various load disturbances on the powertrain. Ion current sensing is one of the alternate method to detect misfire, which received good attention during the last decade of the previous century. When the air-fuel mixture ignites inside the I.C. engine cylinder, air particles get ionize. By applying a suitable high-voltage on spark plug, it is possible to measure the ion current as the amount of ion current reflects the level of ionization of air fuel mixture. The ion current measurement system presented in this paper is implemented in a production vehicle ignition system for two wheeled vehicles. The vehicle ignition system is unique due to the shorted terminals of high & low voltage sides. Due to the shorted primary and secondary connection, it is challenging to implement ion current measurement system using available research work. The proposed novel design of ion current measurement system accommodates the above constraint. The ion current signal is captured during normal combustion event as well as by creating misfire in the combustion. There are significant changes observed in the ion current signal with and without misfire. The information extracted from the ion current signal is utilized to detect the misfire. The proposed design is analyzed with suitable 1D theoretical model of the ignition system.
Bagade, Monika Jayprakash, Das, Himadri Bhushan, Raveendranath Sr, Arjun, Jabez Dhinagar, S
Combustion System Optimization of a Light-Duty GCI Engine Using CFD and Machine Learning2020-01-13134/14/2020
In this study, the combustion system of a light-duty compression ignition engine running on a market gasoline fuel with Research Octane Number (RON) of 91 was optimized using computational fluid dynamics (CFD) and Machine Learning (ML). This work was focused on optimizing the piston bowl geometry at two compression ratios (CR) (17 and 18:1) and this exercise was carried out at full-load conditions (20 bar indicated mean effective pressure, IMEP). First, a limited manual piston design optimization was performed for CR 17:1, where a couple of pistons were designed and tested. Thereafter, a CFD design of experiments (DoE) optimization was performed where CAESES, a commercial software tool, was used to automatically perturb key bowl design parameters and CONVERGE software was utilized to perform the CFD simulations. At each compression ratio, 128 piston bowl designs were evaluated. Subsequently, a Machine Learning-Grid Gradient Algorithm (ML-GGA) approach was developed to further optimize the piston bowl design. This extensive optimization exercise yielded significant improvements in the engine performance and emissions compared to the baseline piston bowl designs. Up to 15% savings in indicated specific fuel consumption (ISFC) were obtained. Similarly, the optimized piston bowl geometries produced significantly lower emissions compared to the baseline. Emissions reductions up to 90% were obtained from this optimization exercise. The performances of the optimized piston bowl geometries were further validated at different operating conditions at the high-load point and at part-load conditions (6 bar IMEP) and compared with those of the baseline designs. The dependence of the engine performance on the piston bowl geometry at part-loads was lower than that at high-loads because injections normally occurred earlier (-60 to -20 CAD after top dead center (aTDC)) where minimal interactions between the spray and piston were anticipated. The interactions between late injections (-3 to 3 CAD aTDC) and piston geometry at high-loads significantly affected, fuel-air mixing, droplet breakup, combustion and emissions. It was also observed that heat losses, dictated by the interactions between the flame and piston surface, significantly affected the performance of the engine.
Badra, Jihad, khaled, Fethi, Sim, Jaeheon, Pei, Yuanjiang, Viollet, Yoann, Pal, Pinaki, Futterer, Carsten, Brenner, Mattia, Som, Sibendu, Farooq, Aamir, Chang, Junseok
Dimensional Optimization of Key Parameters Using DoE Technique to Achieve Better NO X Emission Values in Mass Production of Single Cylinder Small Diesel Engines for 3 Wheeler Applications2020-01-13564/14/2020
Oxides of Nitrogen (NOx) emissions are considered as among the most harmful emissions globally having a direct influence on human beings and the environment. This work deals with a strategy to arrive at achieving lower NOx values consistently in mass production of single cylinder automotive diesel engines meeting BS IV Emission standards using the DoE technique for dimensional optimization of critical parameters. Catalytic converters and particulate filters are mostly used as after - treatment devices for compression Ignition (CI) engines for bringing down the limits (Values) of the pollutants from the tail pipes. But the real ingenuity lies in achieving the same effect through optimization of in - cylinder combustion. Optimization of the critical factors like Nozzle Tip Protrusion (NTP), Static Injection Timing (SIT), Bumping Clearance (BC) and Swirl Number (SN) are considered as the most important engine design parameters for ensuring the optimum combustion which help release of minimal harmful pollutants. In this work, a standard L9 Orthogonal Array (OA) table was used in designing experiments for a study of the interactive model between the said factors and their levels to achieve consistently lower NOx emission values. The design specification of NTP considering the tolerance limit was set between 3.0 mm to 3.30 mm and similarly SIT, BC and Swirl value were set between 0.19 mm to 0.27mm, 0.65mm to 0.75 mm and 2700 rpm to 2800 rpm respectively. Tests were conducted on the basis of standard OA table and the corresponding NOx emissions were measured. It is found that, NTP of 3.2 mm, SIT of 0.19 mm, BC of 0.70 mm and Swirl Rate of 2775 rpm were seen yielding the least NOx emissions. Statistical observations showed the above mentioned combination exhibiting a reduction of NOX achieved with respect to the design specification as 22% and the variation of NOx between engines as 1.1%.
Ramalingam, Jaganathan, B, Prabakaran, Nandagopal, Sasikumar, Venkatesan, Hariram, Mayakrishnan, Jaikumar
A Holistic Approach to Develop a Common Rail Single Cylinder Diesel Engine for Bharat Stage VI Emission Legislation2020-01-13574/14/2020
The upcoming Bharat Stage VI (BS VI) emission legislation has put enormous pressure on the future of small diesel engines which are widely used in the Indian market. The present work investigates the emission reduction potential of a common rail direct injection single cylinder diesel engine by adopting a holistic approach of lowering the compression ratio, boosting the intake air and down-speeding the engine. Experimental investigations were conducted across the entire operating map of a mass-production, light-duty diesel engine to examine the benefits of the proposed approach and the results are quantified for the modified Indian drive cycle (MIDC). By reducing the compression ratio from 18:1 to 14:1, the oxides of nitrogen (NOx) and soot emissions are reduced by 40% and 75% respectively. However, a significant penalty in fuel economy, unburned hydrocarbon (HC) and carbon monoxide (CO) emissions are observed with the reduced compression ratio. Intake air boosting using a mechanically driven supercharger could overcome the penalty in HC and CO emissions. However, the mechanical frictional losses of the supercharger resulted in a further penalty in the fuel economy. The reduced cylinder pressure due to lower compression ratio and the increased air availability due to intake air boosting could be utilized to improve the full-load performance of the engine by 28%. Further, the advantage of improved engine performance was utilized to down-speed the engine by optimizing the transmission gear ratios without compromising the acceleration performance of the vehicle. Overall, with this holistic approach, soot emission could be reduced by a significant margin of 83% whereas the NOx emission is reduced by 5.8%. Moreover, the HC and CO emissions could be reduced by 17.6% and 30.9% respectively. Furthermore, the fuel economy at the vehicle-level could be improved by 5.4% while improving the in-gear acceleration performance by 9%. Thus, the proposed approach is found to be extremely beneficial to develop small, light-duty diesel engines with compliance on future emission regulations. The reasons behind the observed benefits are explained in detail based on the measured in-cylinder pressure and calculated heat release data.
Vellandi, Vikraman, Ramesh, A., Krishnasamy, Anand
Stability of Flowing Combustion in Adaptive Cycle Engines2020-01-02964/14/2020
In an Adaptive Cycle Engine (ACE), thermodynamics favors combustion starting while the compressed, premixed air and fuel are still flowing into the cylinder through the transfer valve. Since the flow velocity is typically high and is predicted to reach sonic conditions by the time the transfer valve closes, the flame might be subjected to extensive stretch, thus leading to aerodynamic quenching. It is also unclear whether a single spark, or even a succession of sparks, will be sufficient to achieve complete combustion. Given that the first ACE prototype is still being built, this issue is addressed by numerical simulation using the G-equation model, which accounts for the effect of flame stretching, over a 3D domain representing a flat-piston ACE cylinder, both with inward- and outward-opening valves. A k-epsilon turbulence model was used for the highly turbulent flow field. It was found that the flame would suffer local blow-off under most operating conditions, but the blow-off is never complete so that the regions affected are later re-ignited by the remaining parts of the flame, and combustion is completed eventually. The interplay of blow-off and re-ignition causes a delay in the overall combustion process, which has been quantified into a modified set of parameters for a Wiebe equation model, applicable to ACEs with premixed charge via port injection, and other engines where combustion might begin before the valves are fully closed.
Tamilselvam, Prashanth, Ruiz, Francisco
Development of a 3D-CFD Model for a Full Optical High-Pressure Dual-Fuel Engine03-13-02-00171/27/2020
In times of ever stricter exhaust emission regulations, the importance of alternative combustion processes in internal combustion engines continues to grow. One approach to create a combustion progress which produces low CO2, soot, and methane emissions is the “High-Pressure Dual-Fuel” (HPDF)-combustion. Here, the direct-injected methane is ignited by a small amount of pilot-diesel and burns in a diffusive combustion mode. This study describes the development of a three-dimensional computational fluid dynamics (3D-CFD) model for the HPDF-combustion. A Reynolds-Averaged Navier-Stokes (RANS) approach with k-epsilon modelling for turbulence was chosen for the calculation of the flow field. The pilot fuel injection is implemented by using Lagrangian Particle Methods, whereas the gas injection is a mass flow boundary which is derived from measurements of the injector. The model is validated using data from a fully optically accessible single-cylinder research engine. The flow field is compared with particle image velocimetry (PIV) data taken before the start of injection (SOI). Concerning pilot injection, a grid convergence study is conducted and an optimization is developed to reduce computational costs. The penetration length of the liquid fuel spray is validated against Mie-scattering images which are taken during the “Pilot-Diesel-only” experiments in the fully optical single-cylinder research engine. The ignition and combustion is modeled via detailed chemistry, which is solved using the commercial Software CONVERGE and the SAGE chemistry solver. The flame liftoff length of the pilot-diesel and the ignition and combustion of the underexpanded gas jets are validated using high-speed imaging of flame luminosity and OH* chemiluminescence. It can be shown that the used n-heptane mechanism is capable of correctly reproducing the trends in the ignition and combustion process.
Frankl, Stephanie, Gleis, Stephan
Intermittent Injection for a Two-Stroke Direct Injection Engine2019-32-05241/24/2020
Cycle-to-cycle variation is one of the main factors for high fuel consumption and emissions of a two-stroke engine during the low-load and low-speed running. The increase of residual gas ratio due to the lower delivered amount of fresh scavenging air leads to a lower flame front speed and, therefore, to a slow combustion or even misfiring. The consequence is a very high level of unburnt hydrocarbons, since a large amount of fuel does not take part in the combustion process. The use of a direct injection system allows a more flexible management of the injection of fuel over subsequent engine cycles. Under a low-load condition, the low request in terms of brake mean effective pressure (BMEP) can be achieved by performing a load control based on an intermittent injection, thus reducing the need for intake throttling and avoiding the loss of fresh fuel resulting from cycles without combustion. In more detail, the supply of fuel to the combustion chamber can be skipped for one or more cycles, thus performing a number of consecutive scavenging cycles with only fresh air. As a result, the fresh air is less diluted by the residual gas and the combustion efficiency increases. This paper presents the results of a preliminary experimental activity on the use of an intermittent injection strategy with a Low Pressure Direct Injection (LPDI) system. In more detail, the effect of skipping one cycle - thus operating the two-stroke engine in a four-stroke-like mode - was investigated at part load conditions by considering four BMEP levels (i.e. from 1.0 bar to 2.5 bar). The benefits of such strategy were evaluated at the test bench and compared with the performance of the standard operation mode. In particular, the cycle-to-cycle variation was drastically reduced and the combustion misfire was avoided with the intermittent injection, thus leading to a strong reduction of both hydrocarbon emissions and brake specific fuel consumption.
Balduzzi, Francesco, Romani, Luca, Bosi, Lorenzo, Ferrara, Giovanni
Combustion Characteristic of Offset Orifice Nozzle under Multi Pulse Ultrahigh Pressure Injection and PCCI Combustion Conditions2019-32-05221/24/2020
CI engines provide higher thermal efficiency compared to other internal combustion engines. On the other hand large amounts of smoke and NOx are produced during combustion. Smoke and NOx can be reduced by applying Premixed Charge Compression Ignition (PCCI) combustion. Unfortunately, the problems of PCCI combustion include unstable start of combustion and limited operating range. The multi-pulse ultrahigh pressure injection allows fuel to control PCCI combustion. The objective of offset orifice nozzle is to improve mixture formation and shorten spray penetration in order to increase thermal efficiency and control PCCI combustion. The offset orifice nozzle was designed by shift orifice aliment from into the sac center to edge of sac follow swirl direction. Counter bore design was applied to offset orifice nozzle in order to keep the constant orifice length as standard nozzle. This paper investigates the effect of nozzle orifice design on combustion characteristics under multi pulse ultra high pressure injection and PCCI combustion conditions. The experiments were carried out on a single cylinder engine at 0.55 MPa gross IMEP at 1,750 rpm. The injection pulses were 3 pulses equally mass main injection at 150, 200, 250, 300 and 350 MPa injection pressure. In case of standard nozzle orifice, 1st, 2nd pulse are PCCI followed by diffusive combustion in every injection pressure. For offset orifice nozzle orifice at 150 and 200 MPa 1st, 2nd pulse are also PCCI combustion. However when injection pressure is over 200 MPa, the 2nd pulse of rate of heat release become diffusive combustion. The offset orifice nozzle resulted in increased thermal efficiency, NOx and smoke. However significant differences between the smoke of offset orifice nozzle and standard nozzle were not found under injection pressure 300 and 350 MPa. The offset orifice nozzle also resulted in decrease CO and THC.
Ewphun, Pop-Paul, Otake, Miku, Nagasawa, Tsuyoshi, Kosaka, Hidenori, Sato, Susumu
Simulation Analysis of the Scavenging Process of a Uniflow and Loop Scavenging Concept2019-32-05491/24/2020
The two-stroke engine, as a today unconventional concept in automotive applications, has a great potential for a relaunch in the fast-growing market of Plugin Hybrid Electric Vehicle (PHEV) or Range Extender Electric Vehicle (REX) [2, 3, 4, 8, 9]. An efficient scavenging to remove the in-cylinder burnt gases and to fill the cylinder with fresh charge, performed at the same time is one of the major challenges, as losses of fresh air and fuel towards the exhaust line should be avoided when operating a lambda = 1 concept necessary for a 3-way catalyst aftertreatment system. A prior study [1] of different gas exchange designs for two-stroke engines concludes that two possible concepts cover this purpose. In this paper, 3D-CFD simulation is used to compare these two different scavenging concepts, a uniflow and a loop scavenging type with control elements for the gas exchange process. As boundary conditions, it is assumed that both concept types have nearly the same displacement, are used with an external scavenging blower and have a lubrication system like a conventional oil sump similar to a four-stroke engine. Additionally, a high-pressure direct injection fuel system is applied to guarantee oil- and fuel-free air for the scavenging process. To compare these different two-stroke scavenging concepts, this study focuses on the scavenging and compression phase using 3D-CFD simulation in order to evaluate the scavenging characteristics and the in-cylinder charge motion. The goal of this study is to prepare a basis for discussion of the best configuration, which will be designed, built and tested on the engine test-bench.
Sturm, Stefan, Lang, Michael, Schmidt, Stephan
Bosch On Board Diagnostic solutions for Motorcycles2019-32-05131/24/2020
EU OBD legislation requirements will bring new challenges for motorcycle engine control from 2020 and 2024 respectively. This paper gives a perspective on the Bosch solutions for On Board Monitoring functions to implement the legislation requirements. Specifically the approach and validation results for the monitor for Secondary Air Injection (SAI) will be highlighted. OBD is well established e.g. for passenger car systems in worldwide markets with Bosch solutions covering different system configurations and legislation requirements. While a large portion of the required OBD monitors for motorcycles can be carried over from passenger car solutions with modifications and enhancements where needed, some specific monitors had to be developed from scratch. These new monitors are required for subsystems and components which do not exist in the passenger car environment, e.g. a controlled valve between the intake manifold and engine outlet of the motorcycle to implement secondary air injection. Special focus of this presentation is on the OBD monitoring of the secondary air injection control valve, where robustness is a challenge given the boundary conditions of only binary lambda sensors available in the systems. Challenges are detection of the actual functioning of the secondary air valve with the binary downstream lambda sensor under real world operating conditions and completion of the diagnostic in the WMTC and on the road. A proof of the chosen conceptual approach is given by the implementation into series software and by validation test results on a 1-cylinder motorcycle. Measurements show, that a malfunction will be detected both in the WMTC and during normal driving.
Jessen, H., Kushal, A., Sabu, A., Hande, S., Tappe, M.
Friction Reduction of an All-aluminum Cylinder for Motorcycles by a Mirror Finished Bore with Dimples2019-32-05301/24/2020
In recent years, the demand for fuel economy of small engines has been increasing for further improvement of product competitiveness. As a solution for this issue, a lot of developments on reduction of friction losses of engine components have been actively performed by engine manufacturers, especially the friction loss between the cylinder bores and pistons or piston rings is main issue to solve because these frictions highly contribute to the fuel economy for the small engines. In this study, focusing on the effect of the texture of the all-aluminum cylinder bore on friction loss, we verified the friction loss of all-aluminum cylinders having several kinds of surface textures by a floating liner method. For the evaluation, we prepared cylinders which have the texture of the following three types, 1) plateau type (having conventional cross-hatches), 2) mirror finished type (having no cross-hatches and no irregular surface characteristics), 3) dimple type (most of part is mirror finished but small dimples are given at a limited part). As a result of the evaluation, it was confirmed that FMEP of mirror type was 14.1% lower and dimple type (optimized for low friction) was 19.5% lower than plateau type. In addition, when comparing FMEP for each crank angle, it was revealed that mirror type was effective evenly in all strokes of intake, compression, expansion, and exhaust, and the dimple showed a large effect particularly on the expansion stroke.
Murase, Yuta, Kumagai, Hideya
Design and Development of a High-Efficiency Single Cylinder Natural Gas-Fueled Jet Ignition Engine2019-32-05651/24/2020
The current energy climate has created a push toward reducing consumption of fossil fuels and lowering emissions output in power generation applications. Combined with the desire for a more distributed energy grid, there is currently a need for small displacement, high efficiency engines for use in stationary power generation. An enabling technology for achieving high efficiencies with spark ignited engines for such applications is the use of jet ignition which enables ultra-lean (λ > ~1.6) combustion via air dilution. This paper provides a comprehensive review of the development of a 390cc, high efficiency single cylinder natural gas-fueled jet ignition engine operating ultra-lean. The engine was developed as part of the Department of Energy’s Advanced Research Projects Agency–Energy (DOE ARPA-E) GENSETS program. Design choices for minimizing friction are highlighted as well as test results showing further friction reduction through downspeeding. Extensive hardware optimization of the combustion system has been performed and results are presented for air-flow path optimization and the jet igniter. The efficiency benefits related to enleanment and downspeeding are analyzed using an efficiency loss breakdown based on the First Law of Thermodynamics. Through optimization efforts a peak brake thermal efficiency in excess of 34% was achieved, representing an increase of greater than 20% over the current state-of-the-industry for comparably sized CNG engines.
Peters, Nathan, Subramanyam, Sai Krishna Pothuraju, Bunce, Michael, Blaxill, Hugh, Pihl, Josh, Moses-Debusk, Melanie, Vishwanathan, Gokul, Tew, David
Analysis of Cycle-to-Cycle Variation in a Port Injection Gasoline Engine by Simultaneous Measurement of Time Resolved PIV and PLIF2019-32-05521/24/2020
Cycle-to-cycle variation (CCV) of combustion in low load operation is a factor that may cause various problems in engine operation. Variable valve timing and variable ignition timing are commonly used as a means to reduce this variation. However, due to mountability and cost constraints, these methods are not feasible for use in motorcycle engines. Therefore, development of an engine with minimal CCV without utilizing complicated mechanisms or electronic control is required. CCV of combustion may be caused by fluctuations in in-cylinder flow, air-fuel mixture, temperature, residual gas and ignition energy. In this study, the relationship between CCV of combustion, in-cylinder flow fluctuation and air-fuel mixture fluctuation was the primary focus. In order to evaluate in-cylinder flow fluctuation, Time Resolved Particle Image Velocimetry (TR-PIV) technique was utilized. In addition, Planar Laser Induced Fluorescence (PLIF) technique was used to measure spatial distribution of the mixture. These two visualization techniques were used together to measure continuous combustion cycles. The fluctuation of net IMEP can be explained by the fluctuation of Turbulence Kinetic Energy (TKE) and fuel concentration. In most cycles, net IMEP was correlated with TKE. In the remaining cycles, net IMEP was correlated with fuel concentration. The contribution of each factor towards net IMEP is to be discussed. It has been also confirmed that TKE fluctuation is caused by fluctuation in the tumble vortex structure, as shown in the authors' previous study [2] [13].
HARAMIISHI, Santa, WATANABE, Takahiro, IIDA, Minoru, HOKIMOTO, Satoshi, KUBOYAMA, Tatsuya, MORIYOSHI, Yasuo
Evaluation of On-board Heat Loss Prediction Model and Polytropic Index Prediction Model for CI Engines Using Measurements of Combustion Chamber Wall Heat Flux2019-32-05431/24/2020
Diesel engines need to optimize the fuel injection timing and quantity of each cycle in the transient operation to increase the thermal efficiency and reduce the exhaust gas emissions through the precise combustion control. The heat transfer from the working gas in the combustion chamber to the chamber wall is a crucial factor to predict the gas temperature in the combustion chamber to optimize the timing and quantity of fuel injection. Therefore, the authors developed both the heat loss and the polytropic index prediction models with the low calculation load and high accuracy. In addition, for the calculation of the heat loss and the polytropic index, the wall heat transfer model was also developed, which was derived from the continuity equation and the energy equation. The present study used a single cylinder diesel engine under the condition of engine speed of 1200 and 1500 rpm, and measured the local wall temperature and the local heat flux of the combustion chamber. The measured data were compared with the prediction results of the heat loss and the polytropic index and evaluated the prediction accuracy of those models. The average relative errors for the heat loss and the polytropic index prediction models were evaluated to be 6.6% and 0.3%, respectively.
Ichiyanagi, Mitsuhisa, Liu, Zhiyuan, Chen, Haoyu, Asano, Koki, Otsubo, Koki, Yilmaz, Emir, Suzuki, Takashi
Influence of Zn, Mo, P, S-contained Engine Oil Additives on Abnormal Combustion in a Spark Ignition Engine2019-32-05861/24/2020
A Spark Ignition Engine has some kinds of problem to be solved over many years, one of them is abnormal combustion; Low-speed pre-ignition (LSPI) under low-speed, high-load driving conditions for vehicle, and pre-ignition under longterm operation without cleaning a combustion chamber for gas cogeneration. As a cause for abnormal combustion, engine oil droplets diluted by liquid fuel and peeled combustion deposits delivered from engine oil are proposed. In this study, experiments were conducted focusing on engine oil additives having different chemical structure and abnormal combustion behavior. A four-stroke side-valve single cylinder engine that allowed in-cylinder visualization of the combustion flame was used in the experiments. The experimental results showed that the influence of DTC additive on abnormal combustion is small and the zinc component contained in the DTP additives had the effect of advancing the autoignition timing.
Izako, Takuya, Iijima, Akira, Kusumoto, Tatsuya, Utaka, Toshimasa
Reduction of a diesel engine NO emissions using the exhaust gas recirculation technique2019-36-00671/13/2020
This paper analyses the effects of the application of the exhaust gas recirculation (EGR) technique in a stationary, single cylinder engine aiming to reduce the emissions of nitrogen oxides (NOx). The engine was operated with diesel oil containing 8% biodiesel (B8) for different load and EGR rates. The engine emissions of carbon monoxide (CO), carbon dioxide (CO2) and nitric oxide (NO) operating without the EGR system were compared with the operation with EGR rates of 15% and 25%. The results revealed that the increase in the EGR rate increased the exhaust gas temperature, the engine specific fuel consumption and the CO and CO2 emissions, but with reduction of up to 72% of NO emissions, when using 25% of EGR rate.
de Oliveira, Alex, Bernardes, Alexandre Pinheiro, Ferreira, Flávio
Design and optimization of the intake system of a Formula SAE race engine2019-36-02531/13/2020
Several motorsport competitions impose restrictions on intake systems to limit maximum engine power. Since the restriction interferes with the efficiency of the intake system as a whole, it is necessary to study ways to minimize the negative effect of changes in engine performance. In practice, the regulation imposes restrictions to the inlet air which motivates the search for the minimum pressure loss in the restrictor while maintaining an equal volumetric efficiency between the cylinders. This way, it is necessary to tune the duct lengths and diameters, and plenum volume to obtain the maximum volumetric efficiency in the most required speeds. Formula SAE competition imposes an intake system restriction of 20 mm or 19 mm diameter (for gasoline or ethanol fueled engines, respectively). Thus, to reduce pressure loss in the imposed restriction orifice, a system with a convergent divergent duct forming a venturi tube was used. This venturi was designed to maximize its discharge coefficient to increase engine volumetric efficiency. Considering that the focus of motorsport competitions is performance, this paper presents a method to minimize intake system restriction which interfere on engine performance. GT-Suite software was used to create an engine thermodynamic model, with focus on the optimization tool for DoE (Design os Experiment). The results of this study showed a considerable increase on the volumetric efficiency between 6000 rpm and 10000 rpm for the proposed four cylinder 0.6 liter engine. Consequently, increase on torque and power were also obtained. Thus, the maximum torque developed in chassis dynamometer reached 5.8kgfm and the maximum power in 76HP, which represents an increase of 1.8% on torque and 22.21% on power compared to the previous designed intake system.
Carvalho, Pedro, Piccini, Alexandre, Goulart, Aleff, Balbom, Felipe, Müller, Alice, Lanzanova, Thompson, Martins, Mario
Study on Characteristics of Combined PCCI and Conventional Diesel Combustion2019-01-216912/19/2019
The main objective of this study is to evaluate the characteristics of combustion that combine premixed charge compression ignition (PCCI)-based combustion with conventional mixing controlled combustion. In this type of combustion, it is supposed that the combustion duration is shortened due to the synchronization of the timing of two types of combustions. In addition, the cooling loss caused by spray impingement is expected to decrease by the reduction of the proportion of mixing controlled combustion. In this study, the effect of injection pressure, injection timing, and split injection on thermal efficiency and emissions were investigated in order to determine the appropriate injection parameters for PCCI-based combustion to realize the proposed combustion concept.
Bao, Zhichao, Pan, Weikang, Yokoyama, Takuji, Hirayama, Kazuki, Horibe, Naoto, Kawanabe, Hiroshi, Ishiyama, Takuji
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