bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Novel Air and EGR Emulation Facility for the Optimisation of the Powertrain Architecture
Authors: Orchard Simon , Ozturk Umud , Evans Nick , Duda Tomasz , Chappell Ed , Burke Richard 
Published: December 2019

Abstract
In this work, an external air and EGR emulation facility has been designed that can replicate a wide range of boosting and EGR delivery systems to a multi-cylinder engine platform. The facility works by removing the incumbent air path and replacing it with externally boosted fresh air that is conditioned using a transient flow and temperature controller. The facility also recycles the actual exhaust gases from the engine whilst removing the constraints of required pressure differences to drive this flow. The resulting system is able to control the boundary conditions of intake air flow - pressure and temperature, engine back-pressure and EGR flow rate independently.
Three testing approaches have been described that allow to obtain valuable data across a wide range of the engine map (based on an example of a 1.0L direct injection gasoline engine) also beyond its typical hardware related limits.
The facility is designed to be used as part of an engine design optimisation process. The facility generates data of the engine combustion system independently of the associated air path subsystems and excites the boundary conditions beyond those that would be expected from a specific air path design. The data is then used to populate 1D engine models which can be confidently used to predict the performance of a specific air path hardware combination and control strategy.
High Efficiency Diesel Engine Concept With Variable Valve Train and Cylinder Deactivation for Integration Into a Tractor
Authors: Thees Matthias , Buitkamp Thomas , Guenthner Michael , Pickel Peter 
Published: December 2019

Abstract
The objective of current research on internal combustion engines is to further reduce exhaust emissions while simultaneously reducing fuel consumption. The resulting measures often mean an increase in complexity of internal combustion engines, which on one hand increases production cost and on the other hand increases the susceptibility of the overall system to defects. It is therefore necessary to develop technologies which can generate an advantage for the consumer despite increasing complexity. Within the scope of the project “High Efficiency Diesel Engine Concept” (“Hocheffizientes Diesel-Motoren-Konzept” HDMK), funded by the Federal Ministry of Economic Affairs and Energy with TÜV Rheinland as project management organization (funding code: 19U15003A), two engine concepts were investigated and combined on a John Deere four-cylinder inline engine.
On the one hand, a new cylinder activation concept (“3/4-cylinder concept”) was implemented with the aim of reducing fuel consumption. On the other hand, a fully variable valve train was developed for this engine, which both improves the functionality of the 3/4-cylinder concept and can have a positive influence on exhaust emissions through internal exhaust gas recirculation.
A comparison of this engine concept with its series reference based on measurement data showed a fuel economy advantage of up to 5.2% in the low load field cycles of the DLG PowerMix. The maximum fuel consumption benefit in the low load engine regime exceeded 15% in some of the operating points.
As a final step, the engine was modified for the integration into an existing and working tractor, maintaining the available installation space of the powertrain.
Needle Displacement Visualization With Simultaneous Measurement of Injection Rate for CR Diesel Injector: A Novel Experimental Technique
Authors: Chiatti Giancarlo , Chiavola Ornella , Palmieri Fulvio 
Published: December 2019

Abstract
The control of combustion is a key topic for diesel engine development in terms of performance and pollutant emissions. The combustion process is piloted through the proper injection strategy, which depends on the features of the injection system. Mechanical-hydraulic models of high-pressure injection systems often support the accurate tuning of the injection strategy.
The higher is the accuracy in the modeling of the electro-injector behavior, the deeper is the role of the simulation. Under such a viewpoint, the validation of the models is undoubtedly fundamental.
One of the most crucial information characterizing the injector relies on the measurement of the needle displacement. Needle displacement affects rate, timing and quantity of injected fuel; it also influences the flow features within the nozzle, which are then reflected by the primary atomization process.
Needle is considered hardly-accessible due to the injector architecture itself, making difficult the measurement of displacement. Nevertheless, the problem has been handled in different ways and three measurement techniques have been proposed. On one side, there is the measurement based on eddy-current transducers; on the other side, there are two alternative procedures, based on the use of optical sensors. However, in all cases, the needle is traced indirectly, since the position of the control plunger of the needle is observed.
The current contribution presents a novel experimental technique for the measurement of needle displacement.
The method is based on the direct visualization of the needle, allowing for the detailed definition of its law of motion through digital imaging, when the injector is characterized on a test-rig under transient conditions.
The paper describes the details of the diagnostic scheme, the experimental facility and the digital imaging set-up. The main features and the capabilities of the method are discussed, in comparison with the other available techniques.
Two-Stage Lean-Burn Combustion Inside a Natural-Gas Spark-Ignition Engine With a Bowl-in-Piston Chamber
Authors: Liu Jinlong , Dumitrescu Cosmin E. 
Published: December 2019

Abstract
The conversion of existing diesel engines to spark ignition (SI) operation by adding a low-pressure injector in the intake manifold for fuel delivery and replacing the original high-pressure fuel injector with a spark plug to initiate and control the combustion process can reduce U.S. dependence on petroleum imports and increase natural gas (NG) applications in heavy-duty transportation sectors. Since the conventional diesel combustion chamber (i.e., flat-head-and-bowl-in-piston-chamber) creates high turbulence, the converted NG SI engine can operate leaner with stable and repeatable combustion process. However, existing literatures point to a long late-combustion duration and increased unburned hydrocarbon emissions in such retrofitted engines that maintained the original combustion chamber. Consequently, the main objective of this paper was to report recent findings of NG combustion characteristics inside a bowl-in-piston combustion chamber that will add to the general understanding of the phenomena. The new results indicated that the premixed NG burn inside the bowl-in-piston combustion chamber will separate into a bowl-burn and a squish-burn processes in terms of burning location and timing. The slow burning event in the squish region explains the low slope of the burn rate towards the end of combustion in existing studies (hence the longer late-combustion period). In addition, the less-favorable conditions for the combustion in the squish region explained the increased carbon monoxide and unburned hydrocarbon emissions.
Effect of Fuel Injection Parameters on Performance and Emissions for High Efficiency Engines
Authors: Kumar Raj , Wang Yan , Vojtech Ryan , Cigler James 
Published: December 2019

Abstract
Future diesel engine legislations are focused on further improvements in green-house gas emissions, such as carbon dioxide while additionally pushing for lower NOx emissions levels. These are being achieved with a combination of base-engine, fuel-injection system, air-system and after-treatment system improvements. In this paper, the effect of one injection system characteristics, namely injector flow-rate was investigated on engine performance and emissions using both numerical and experimental techniques. The phenomenon of increasing injector flow was first numerically investigated using commercial code Converge. Two approaches to increasing injector flow-rate were investigated. The first approach was by increasing the injector nozzle hole size while keeping the number of holes constant. The second approach was to change the number of the holes while keeping the injector nozzle size fixed. These simulations led to procurement of injectors to validate the simulation trends. Engine tests were performed with Navistar’s 12.4 L multi-cylinder heavy-duty diesel engine. The identified nozzle flow rates included a 66% increase from that of the baseline case. All the engine tests were performed at the typical cruising condition for this engine, at a series of injection timing and injection pressure values. It was observed that the crank angle for 50% of the integrated total calculated heat release (CA50) for the fuel burned was the most important factor that influenced the brake-thermal efficiency (BTE) and different injectors had similar BTE at constant CA50. With regards to emission, at higher nozzle flow rates, the combustion showed a slightly higher propensity for soot and increased levels of carbon monoxide.
Investigation of the Electrical-to-Thermal Energy Transfer Efficiency of Different Discharge Strategies Through Electrical and Calorimetry Measurement
Authors: Zhu Hua , Yu Xiao , Yang Zhenyi , Liang Li , Zheng Ming 
Published: December 2019

Abstract
In this paper, the electrical-to-thermal energy transfer efficiency of the transistor coil ignition system for spark-ignition engines is investigated using both electrical and calorimetry measurements. The gap voltage and discharge current are measured to determine the electrical energy supplied to the spark gap. A pressure-rise calorimeter is used to estimate the thermal energy transferred from the plasma channel to the gas. Firstly, this paper studies the influences of spark gap size, electrode geometry and background pressure on the energy transfer efficiency. To further investigate the effectiveness of increasing breakdown energy on the energy transfer process, a direct-capacitor is paralleled to the spark gap to redistribute the spark energy in both breakdown and glow phases. The varying of the capacitance enables the investigation of the energy transfer efficiency under different breakdown energy level. Results show that the electrical-to-thermal energy transfer efficiency is strongly dependent on gap size, electrode geometry and background pressure. Increasing the breakdown discharge energy is beneficial for the electrical to thermal energy transfer process.
Optimization of Engine Efficiency for Diesel Engine Equipped With EGR-VGT and Aftertreatment Systems
Authors: Yang Kuo , Chen Pingen 
Published: December 2019

Abstract
Engine efficiency improvement is very critical for medium to heavy-duty vehicles to reduce Diesel fuel consumption and enhance U.S. energy security. The tradeoff between engine efficiency and NOx emissions is an intrinsic property that prevents modern Diesel engines, which are generally equipped with exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT), from achieving the optimal engine efficiency while meeting the stringent NOx emission standards. The addition of urea-based selective catalytic reduction (SCR) systems to modern Diesel engine aftertreatment systems alleviate the burden of NOx emission control on Diesel engines, which in return creates extra freedom for optimizing Diesel engine efficiency. This paper proposes two model-based approaches to locate the optimal operating point of EGR and VGT in the air-path loop to maximize the indicated efficiency of turbocharged diesel engine. Simulation results demonstrated that the engine brake specific fuel consumption (BSFC) can be reduced by up to 1.6% through optimization of EGR and VGT, compared to a baseline EGR-VGT control which considers both NOx emissions and engine efficiency on engine side. The overall equivalent BSFCs are 1.8% higher with optimized EGR and VGT control than with the baseline control. In addition, the influence of reducing EGR valve opening on the non-minimum phase behavior of the air path loop is also analyzed. Simulation results showed slightly stronger non-minimum phase behaviors when EGR is fully closed.
Numerical Investigation of Fuel Property Effects on Mixed-Mode Combustion in a Spark-Ignition Engine
Authors: Xu Chao , Pal Pinaki , Ren Xiao , Som Sibendu , Sjöberg Magnus , Van Dam Noah , Wu Yunchao , Lu Tianfeng , McNenly Matthew 
Published: December 2019

Abstract
In the present study, mixed-mode combustion of an E30 fuel in a direct-injection spark-ignition engine is numerically investigated at a fuel-lean operating condition using multidimensional computational fluid dynamics (CFD). A fuel surrogate matching Research Octane Number (RON) and Motor Octane Number (MON) of E30 is first developed using neural network based non-linear regression model. To enable efficient 3D engine simulations, a 164-species skeletal reaction mechanism incorporating NOx chemistry is reduced from a detailed chemical kinetic model. A hybrid approach that incorporates the G-equation model for tracking turbulent flame front, and the multi-zone well-stirred reactor model for predicting auto-ignition in the end gas, is employed to account for turbulent combustion interactions in the engine cylinder. Predicted in-cylinder pressure and heat release rate traces agree well with experimental measurements. The proposed modelling approach also captures moderated cyclic variability. Two different types of combustion cycles, corresponding to purely deflagrative and mixed-mode combustion, are observed. In contrast to the purely deflagrative cycles, mixed-mode combustion cycles feature early flame propagation followed by end-gas auto-ignition, leading to two distinctive peaks in heat release rate traces. The positive correlation between mixed-mode combustion cycles and early flame propagation is well captured by simulations. With the validated numerical setup, effects of NOx chemistry on mixed-mode combustion predictions are investigated. NOx chemistry is found to promote auto-ignition through residual gas recirculation, while the deflagrative flame propagation phase remains largely unaffected. Local sensitivity analysis is then performed to understand effects of physical and chemical properties of the fuel, i.e., heat of evaporation (HoV) and laminar flame speed (SL). An increased HoV tends to suppress end-gas auto-ignition due to increased vaporization cooling, while the impact of HoV on flame propagation is insignificant. In contrast, an increased SL is found to significantly promote both flame propagation and auto-ignition. The promoting effect of SL on auto-ignition is not a direct chemical effect; it is rather caused by an advancement of the combustion phasing, which increases compression heating of the end gas.
Effect of Fuel Chemical and Physical Properties on Spray and Ignition Characteristics Under Heavy-Duty Diesel Engine Conditions
Authors: Tang Meng , Pei Yuanjiang , Zhang Yu , Traver Michael , Naber Jeffrey 
Published: December 2019

Abstract
Spray combustion in compression ignition (CI) engines is a complex physical-chemical phenomenon. The differences in key fuel properties between gasoline range fuels and diesel, including the distillation temperature ranges and fuel reactivity, affect spray formation and combustion. To understand the impact of these fuel effects, this study aims at a thorough computational investigation involving variations in both the fuel physical and chemical properties. Physical properties include latent heat of vaporization, specific heat capacity, density, vapor pressure, viscosity, and surface tension. These properties were individually perturbed between gasoline and diesel. Chemical properties were represented by different fuel reactivity, including PRF0 and PRF60. The model was validated against diesel and RON60 gasoline spray experiments performed in a constant-volume combustion chamber. The physical and chemical properties were modeled separately to isolate the effect of a single parameter that is often difficult to single out in experimental investigations. Sprays under non-reacting and reacting conditions were then simulated to understand the physical processes that lead to ignition and thus the fuel reactivity effects on the subsequent processes. The investigation covered low to high temperature combustion and different exhaust gas recirculation (EGR) levels. Simulation results suggested that the chemical property dominated the ignition process, whereas the physical properties had more influence on the atomization and vaporization process. Also, there was a complex interaction between physical and chemical parameters on spray ignition depending on the operating conditions, which provide insights on tailoring fuel properties for different CI applications.
Assessing Fuel Property Effects on Cavitation and Erosion Propensity Using a Computational Fuel Screening Tool
Authors: Magnotti Gina M. , Som Sibendu 
Published: December 2019

Abstract
To advance compression ignition combustion strategies, researchers have evaluated fuel property effects and their impact on achieving higher efficiencies and lower emissions levels relative to current capabilities. Within the Department of Energy’s Co-Optima initiative, there has been a recent focus on understanding the influence of fuel properties on fuel injection performance. To help identify candidate fuels that can meet desired injector performance metrics, a computational fuel screening tool is under development that can link fuel properties with the tendency of a given fuel to cavitate and lead to cavitation-induced erosion. In the initial development of this tool, five liquid fuel properties were selected to represent candidate fuels, namely density, viscosity, vapor pressure, surface tension, and heat of vaporization. A design of experiments methodology was employed to generate a set of pseudo-fuel cases, which can represent the main effects and interactions among the fuel properties and be related to cavitation erosion predictions. Large eddy simulations were performed using a mixture modeling approach to predict the cavitation and erosion propensity of these pseudo-fuels in terms of the mean fuel vapor mole fraction and stored impact energy from repeated cloud collapse events. The low order regression models generated from this study revealed the importance of liquid fuel density on cavitation formation, whereas liquid viscosity was found to have a strong negative correlation with erosion severity. The surrogate models were then used in the fuel screening tool to rank the cavitation and erosion tendency of four candidate single-component fuels: methyl decanoate, iso-octane, ethanol and n-dodecane. While the fuel screening tool was not able to quantitatively predict the cavitation and erosion response metrics, the tool was able to accurately rank the relative cavitation and erosion propensity of the four fuels. Overall, ethanol and iso-octane were observed to produce the highest levels of cavitation and erosion, respectively.
Experimental Investigation and Thermodynamic Modelling of an RCCI Engine With Gasoline and Ethanol As Pilot Fuels
Authors: Mishra Chinmaya , Subbarao P. M. V. 
Published: December 2019

Abstract
Reactivity controlled compression ignition (RCCI) is an emerging premix low temperature combustion philosophy. Contemporary understanding suggests that RCCI concept with a premix high octane (low reactivity) fuel and direct injected high cetane (high reactivity) fuel ensures in-cylinder stratification of equivalence ratio as well as fuel reactivity. This stratification of reactivity coupled with partial premixing ensures simultaneous reduction of oxides of nitrogen and smoke. Furthermore, the induced delay in combustion phasing and high compression ratio ensures diffusive flames away from piston surface resulting in higher thermal efficiency. In the present work, an experimental investigation was carried out using port injected gasoline and anhydrous ethanol as low reactivity pilot fuels and direct injected diesel as high reactivity main fuel under various energy share. A comparative study of both the pilot fuels were carried out in terms of engine performance, emission and in-cylinder behavior in both representative and statistical perspective.
Overcoming Turbocharger Limitations for Low BMEP Two-Stroke Large Bore Gas Engines: A Technical Analysis and Case Study
Authors: Toema Mohamed , Watts Paul , Mathews Hans , Beshouri Greg 
Published: December 2019

Abstract
This paper reviews the unique challenges of implementing emissions upgrade on low Brake Mean Effective Pressure (BMEP) natural gas engines. A large population of the low BMEP gas engines are still utilized in natural gas compressor stations nationwide. Reducing NOx emissions of these engines requires leaner air-to-fuel ratio operation. The typical engine upgrade utilizing a “pure” turbocharged approach is a challenge for low BMEP engines due to poor overall efficiencies of turbochargers at relatively low pressure ratios needed. Previous papers have reported on the use of pure turbocharging and noted performance deficiencies. Other papers have dealt with turbocharging in series with the reciprocating scavenger. Neither approach proved successful, as the units either had a very limited turn down, or suffered fuel efficiency penalties that can no longer be tolerated, given today concerns for Green House Gas emissions.
Current strict emission regulations and the need of pipeline companies to utilize their low BMEP engine fleet, necessitates revisiting of the low BMEP upgrade challenge. One of the main merits of these low BMEP units is the operation flexibility. They provide pipeline companies the ability to accommodate wide range of gas demand.
This paper first offers a thermodynamic analysis to demonstrate that the exhaust energy of the low BMEP engine is not sufficient to properly match the required compression energy of the turbocharger compressor wheel for a broad operating range. This means the required boost pressure can’t be achieved with a self-sustaining Turbo across a “normal” operating range. The paper then offers a technical analysis of the various viable options to upgrade low BMEP engines. Using a Cooper GMV-TF, a very common engine type in this class as a benchmark, several options are investigated, starting from a series turbocharging with the exiting on engine blower/piston scavenger to supercharging with electrical motor driven blower. It also investigates the option of using an external gas burner in the exhaust stream. The paper closes with a successful case study using electric driven blower in two different compressor station sites.