The Experts below are selected from a list of 47199 Experts worldwide ranked by ideXlab platform
Bangquan He - One of the best experts on this subject based on the ideXlab platform.
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spark ignition natural Gas Engines a review
Energy Conversion and Management, 2007Co-Authors: Bangquan HeAbstract:Natural Gas is a promising alternative fuel to meet strict engine emission regulations in many countries. Natural Gas Engines can operate at lean burn and stoichiometric conditions with different combustion and emission characteristics. In this paper, the operating envelope, fuel economy, emissions, cycle-to-cycle variations in indicated mean effective pressure and strategies to achieve stable combustion of lean burn natural Gas Engines are highlighted. Stoichiometric natural Gas Engines are briefly reviewed. To keep the output power and torque of natural Gas Engines comparable to those of their Gasoline or Diesel counterparts, high boost pressure should be used. High activity catalyst for methane oxidation and lean deNOx system or three way catalyst with precise air–fuel ratio control strategies should be developed to meet future stringent emission standards. 2006 Elsevier Ltd. All rights reserved.
Berk Demirgok - One of the best experts on this subject based on the ideXlab platform.
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Natural Gas vehicles in heavy-duty transportation-A review
Energy Policy, 2018Co-Authors: Arvind Thiruvengadam, Marc Besch, Vishnu Padmanaban, Saroj Pradhan, Berk DemirgokAbstract:Abstract In comparison to legacy engine technology, natural Gas vehicles have become cleaner and more efficient. Improved fueling infrastructure has supported the growth of natural Gas vehicles in the heavy-duty sector. The heavy-duty transportation industry greatly favors the use of diesel engine technology compared to alternative fuel strategies. Local regulations and economic incentives, however, have helped to spur adoption of natural Gas vehicles in certain heavy-duty vocations. Studies have shown lower distance-specific oxides of nitrogen (NOx) emissions from the stoichiometric three-way catalyst (TWC) equipped natural Gas Engines compared to diesel Engines equipped with diesel particulate filters (DPF) and selective catalytic reduction (SCR). This review details the progress in natural Gas engine technology, presents changes to emissions rate due to technology advancements, and compares natural Gas engine emissions to those of modern diesel Engines.
Andreas Wimmer - One of the best experts on this subject based on the ideXlab platform.
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development and validation of 3d cfd injection and combustion models for dual fuel combustion in diesel ignited large Gas Engines
Energies, 2018Co-Authors: Lucas Eder, Gerhard Pirker, Marko Ban, Milan Vujanovic, Peter Priesching, Andreas WimmerAbstract:This paper focuses on improving the 3D-Computational Fluid Dynamics (CFD) modeling of diesel ignited Gas Engines, with an emphasis on injection and combustion modeling. The challenges of modeling are stated and possible solutions are provided. A specific approach for modeling injection is proposed that improves the modeling of the ballistic region of the needle lift. Experimental results from an inert spray chamber are used for model validation. Two-stage ignition methods are described along with improvements in ignition delay modeling of the diesel ignited Gas engine. The improved models are used in the Extended Coherent Flame Model with the 3 Zones approach (ECFM-3Z). The predictive capability of the models is investigated using data from single cylinder engine (SCE) tests conducted at the Large Engines Competence Center (LEC). The results are discussed and further steps for development are identified.
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sustainable power generation with large Gas Engines
Energy Conversion and Management, 2017Co-Authors: Gerhard Pirker, Andreas WimmerAbstract:Abstract Large Gas Engines will play a significant role in distributed power generation for the energy supply of the future. The lower amount of carbon in natural Gas in comparison with other fossil fuels can be used to bridge the gap between a carbon‐based and a carbon‐free energy supply. The main objective of this paper is to provide an overview of the technological challenges the next generation of Gas Engines will face. Improvements in robustness and dynamic behavior will allow Gas Engines to meet the high transient requirements for the future power supply. The great fluctuations in Gas quality anticipated with grid Gas and liquefied natural Gas impose high demands on both the transient behavior and the knock resistance of the engine. Technologies that enhance fuel flexibility by enabling sustainable power and heat generation using hydrogen‐rich synGas from biomass and the efficient use of waste Gases will be key. The most important technological components that maximize power output and efficiency as well as transient operation at very low emission levels are discussed. An advanced development methodology is applied in order to deal with the requirements presented by the technological challenges. The main future goals of Gas engine development will be described by use of examples to illustrate the application of the methodology. In summary, the research and technological developments presented in this paper will support the transition from conventional to carbon‐free fuel for reliable and sustainable power generation that meets future requirements for large Gas Engines.
B Korb - One of the best experts on this subject based on the ideXlab platform.
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experimental and numerical investigations of charge motion and combustion in lean burn natural Gas Engines
Combustion and Flame, 2020Co-Authors: B Korb, K Kuppa, Friedrich Dinkelacker, H Nguyen, Georg WachtmeisterAbstract:Abstract It is important to understand the lean-burn combustion process of large-bore natural Gas Engines and influences on it in order to improve next generations of Gas Engines to meet the increasing requirements for high efficiencies and low emissions. The investigations in this study focus on the ignition and early flame propagation phase using optical experiments on a single-cylinder research engine, since both phases highly influence the subsequent main-combustion. Scavenged prechambers with different operating conditions and a tangential and radial nozzle alignment as well as unscavenged prechamber and direct spark plug ignition are compared. Beside the phenomenology of the ignition system itself, the interaction of the main-chamber charge motion and the ignition system is important to understand. Therefore, different valve timings (conventional timings and Miller cycle) as well as a low and high turbulence setup are subject of the study. Numerical simulations of the cold flow are used to understand the charge motion and mixture formation in the prechamber as well as in the main-chamber. The experiments depict an enhancement of the first flame propagation phase using a scavenged prechamber due to hot turbulent jets emerging from the nozzles. Furthermore, an influence of the nozzle geometry and the boundary conditions on the jet development and on the early flame propagation is observed. It is seen by the optical measurements that cycle-to-cycle variations can originate from the hot turbulent jets and its influence on the ignition of the main-chamber charge. Further, the optical measurements show that a low in-cylinder swirl and turbulence due to Miller cycle has an impact on the interaction between the in-cylinder charge motion and the jets. A comparison between high turbulence and low turbulence in-cylinder flows on the combustion is carried out. It is shown that the scavenged prechamber can compensate the lack of turbulence in the main-chamber. Hence, the scavenged prechamber enhances the flame propagation due to induced turbulence in the main-chamber and larger flame front surfaces generated by penetrating flame torches.
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influence of hydrogen addition on the operating range emissions and efficiency in lean burn natural Gas Engines at high specific loads
Fuel, 2016Co-Authors: B Korb, S Kawauchi, G WachtmeisterAbstract:Abstract Power to Gas has attracted much attention as a solution to handle the electricity overproduced from renewable energy. This overproduced electricity can be converted into H 2 and injected into the existing natural Gas grid. Therefore, efficient and safe usage of H 2 enriched natural (HNG) Gas is a key issue to spread Power to Gas further. In this paper, the influences of H 2 addition on the engine combustion process is discussed, focusing on large-bore lean burn Gas Engines operated at high specific loads. The experimental setup consists of a single cylinder research Gas engine with a displacement of 4.77 L . The results show a big influence of the addition of H 2 on the operating range and emissions even with small amounts of H 2 . The misfire limit extends to the leaner side, while knocking must be prevented by a later ignition timing (IGT). Pre-ignition phenomena are limiting the operating range at richer conditions with rising H 2 amounts. While NO x emissions increase, unburned hydrocarbon (THC) and formaldehyde (HCHO) emissions decrease due to an enhanced combustion. This and the leaner operating conditions, which can overcompensate the actual NO x increase, facilitate a higher efficiency, which is discussed based on a detailed loss analysis.
Konstantinos Boulouchos - One of the best experts on this subject based on the ideXlab platform.
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fundamental aspects of jet ignition for natural Gas Engines
SAE International journal of engines, 2017Co-Authors: E Mastorakos, Patton M Allison, Andrea Giusti, Pedro M De Oliveira, Sotiris Benekos, Yuri M Wright, Christos E Frouzakis, Konstantinos BoulouchosAbstract:© 2017 SAE International. Large-bore natural Gas Engines may use pre-chamber ignition. Despite extensive research in engine environments, the exact nature of the jet, as it exits the pre-chamber orifice, is not thoroughly understood and this leads to uncertainty in the design of such systems. In this work, a specially-designed rig comprising a quartz pre-chamber fit with an orifice and a turbulent flowing mixture outside the pre-chamber was used to study the pre-chamber flame, the jet, and the subsequent premixed flame initiation mechanism by OH* and CH* chemiluminescence. Ethylene and methane were used. The experimental results are supplemented by LES and 0D modelling, providing insights into the mass flow rate evolution at the orifice and into the nature of the fluid there. Both LES and experiment suggest that for large orifice diameters, the flow that exits the orifice is composed of a column of hot products surrounded by an annulus of unburnt pre-chamber fluid. At the interface between these layers, a cylindrical reaction zone is formed that propagates in the main chamber in the axial direction assisted by convection in the jet, but with limited propagation in the cross-stream direction. For small orifice diameters, this cylinder is too thin, and the stretch rates are too high, for a vigorous reaction zone to escape the pre-chamber, making the subsequent ignition more difficult. The methane jet flame is much weaker than the one from ethylene, consistent with the lower flame speed of methane that suggests curvature-induced quenching at the nozzle and by turbulent stretch further downstream. The velocity of the jet is too high for the ambient turbulence to influence the jet, although the latter will affect the probability of initiating the main premixed flame. The experimental and modelling results are consistent with ongoing Direct Numerical Simulations at ETH Zurich.
