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Abstract The ASTM D130 was first issued in 1922 as a tentative standard for the detection of corrosive sulfur in gasoline. A clean copper strip was immersed in a sample of gasoline for three hours at 50°C with any corrosion or discoloration taken to indicate the presence of corrosive sulfur. Since that time, the method has undergone many revisions and has been applied to many petroleum products. Today, the ASTM D130 standard is the leading method used to determine the corrosiveness of various fuels, lubricants, and other hydrocarbon-based solutions to copper. The end-of-test strips are ranked using the ASTM Copper Strip Corrosion Standard Adjunct, a colored reproduction of copper strips characteristic of various degrees of sulfur-induced tarnish and corrosion, first introduced in 1954. This pragmatic approach to assessing potential corrosion concerns with copper hardware has served various industries well for a century.

Abstract In recent years, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigations. With this solution, in fact, it is possible to simultaneously reduce NOx raw emissions and fuel consumption due to decreased heat losses, higher thermodynamic efficiency, and enhanced knock resistance. However, the real applicability of this technique is strongly limited by the increase in cyclic variation and the occurrence of misfire, which are typical for the combustion of homogeneous lean air/fuel mixtures. The employment of a Pre-Chamber (PC), in which the combustion begins before proceeding in the main combustion chamber, has already shown the capability of significantly extending the lean-burn limit. In this work, the potential of an ultralean PC SI engine for a decisive improvement of the thermal efficiency is presented by means of numerical and experimental analyses.

Abstract This article presents an investigation of energy transfer, flame propagation, and emissions formation mechanisms in a four-cylinder, downsized and boosted, spark ignition engine fuelled by either directly injected compressed natural gas (DI CNG) or gasoline (GDI). Three different charge preparation strategies are examined for both fuels: stoichiometric engine operation without external dilution, stoichiometric operation with external exhaust gas recirculation (EGR), and lean burn. In this work, experiments and engine modelling are first used to analyze the energy transfer throughout the engine system. This analysis shows that an early start of fuel injection (SOI) improves fuel efficiency through lower unburned fuel energy at low loads with stoichiometric DI CNG operation.

Abstract The article compares the accuracy of different exhaust gas recirculation (EGR) correction factor models under engine conditions. The effect of EGR on the laminar burning velocity of a EURO VI E10 specification gasoline (10% Ethanol content by volume) has been back calculated from engine pressure trace data, using the Leeds University Spark Ignition Engine Data Analysis (LUSIEDA) reverse thermodynamic code. The engine pressure data ranges from 5% to 25% EGR (by mass) with the running conditions, such as spark advance and pressure at intake valve closure, changed to maintain a constant engine load of 0.79 MPa gross mean effective pressure (GMEP). Based on the experimental data, a correlation is suggested on how the laminar burning velocity reduces with increasing EGR mass fraction.

Abstract The article presents a concept of a new turbine engine in the field of pressure gain combustion (PGC). The engine operates according to the Humphrey thermodynamic cycle, where pressure increase was obtained in a combustion chamber closed with a valve. The intake mushroom valve and exhaust swing valve were designed for self-acting. They operate as a result of gas pressure and centrifugal force. The engine consists of two rotating combustion chambers and a counterrotating radial turbine, in both of which mechanical power was generated. The gas flow in the mobile valve system, combustion process, gas expansion, and torque generation were analyzed by means of Computational Fluid Dynamics (CFD) analysis. The investigated engine concept is characterized by significant energy efficiency.

Abstract A pre-chamber ignition system has the potential to reduce the burn duration of lean-burn gasoline engine combustion and can achieve a reduced knock occurrence from the distributed ignition sources. Pre-chamber ignition produces high-velocity turbulent jets, and these jets often reach sonic velocity and produce shock waves inside the combustion chamber. These shock waves make knock detection difficult with a conventional surface-mounted acoustic knock sensor. This article discusses how an acoustic knock sensor works with a pre-chamber ignition and evaluates different cylinder pressure-based knock detection strategies and proposes a method that eliminates the influence of jet-induced oscillations on knock detection.

Abstract Deep learning (DL)-based approaches enable unprecedented control paradigms for propulsion systems, utilizing recent advances in high-performance computing infrastructure connected to modern vehicles. These approaches can be employed to optimize diesel aftertreatment control systems targeting the reduction of emissions. The optimization of the Trapped Soot Load (TSL) reduction in the Diesel Particulate Filter (DPF) is such an example. As part of the diesel aftertreatment system, the DPF stores the soot particles resulting from the combustion process in the engine. Periodically, the stored soot is oxidized during a DPF regeneration event. The efficiency of such a regeneration influences the fuel economy, and potentially the service interval of the vehicle. The quality of a regeneration depends on the operating conditions of the DPF, the engine, and the ability to complete the regeneration event.

Abstract Thermoelectric devices (TEDs) allow direct electric and thermal energy mutual conversion. Because of the absence of working fluids and moving components, they can be used where it is not possible to refer to conventional technologies. In automotive applications, TEDs can give support in air conditioning and internal combustion engine (ICE) thermal heat recovery, contributing to increase the overall vehicle efficiency. Phenomena taking place in these devices are of a different nature and involve electric, thermal, and thermoelectric aspects, being highly influenced by materials’ characteristics and by system geometry. With the aim to offer a design tool, a TED mathematical model is presented in this article. The proposed model is based on a distributed parameter approach and has been conceived to consider heat transfer actual conditions. It accurately describes thermal energy production and removal terms due to Peltier and Joule effects.

Abstract The cold crank-start stage, including the first three engine cycles, is responsible for a significant amount of the cold-start phase emissions in a Gasoline Direct Injection (GDI) engine. The engine crank-start is highly transient due to substantial engine speed changes, Manifold Absolute Pressure (MAP) dynamics, and in-cylinder temperatures. Combustion characteristics change depending on control inputs variations, including throttle angle and spark timing. Fuel injection strategy, timing, and vaporization dynamics are other parameters causing cold-start first cycles analysis to be more complex. Hybrid Electric Vehicles (HEVs) provide elevated cranking speed, enabling technologies such as cam phasing to adjust the valve timing and throttling, and increased fuel injection pressure from the first firings.

Abstract Linear internal combustion engine-linear generator integrated system (LICELGIS) is an innovative energy conversion device with the ability of converting mechanical energy into electrical energy, which allows it to be a range extender for hybrid vehicles. This article presents a fundamental analysis for the steady-state operation of the LICELGIS, concentrating on electromagnetic force and motion characteristics. Simple assumptions are made to represent ideal gases instantaneous heat release and rejection. Based on assumptions, sensitivity analysis is carried out for key factors of electromagnetic force. The theoretical velocity model in mathematics is derived from analyzing the LICELGIS theory model. It shows that fuel injection quantity and stroke length are the most sensitive factors in key parameters. The piston velocity around the top dead center (TDC) changes greater than that at any other position, which is caused by the combustion process.

Abstract Mechanical friction simulations offer a valuable tool in the development of internal combustion engines for the evaluation of optimization studies in terms of time efficiency. However, system modeling and evaluation of model performance may be highly complex. A high number of interacting submodels and parameters as well as a limited model transparency contribute to uncertainties in the modeling process. In particular, model calibration and validation are complicated by the unknown effect of parameters on the model output. This article presents an advanced and model-independent methodology for identifying sensitive parameters of engine friction. This allows the user to investigate an unlimited number of parameters of a model whose structure and properties are prior unknown.

Abstract Performing an uncertainty analysis for complex measurement tasks, such as those found in engine research, presents unique challenges. Also, because of the excessive computational costs, modeling-based approaches, such as a Monte Carlo approach, may not be practical. This work provides a traditional statistical approach to uncertainty analysis that incorporates the uncertainty tree, which is a graphical tool for complex uncertainty analysis. Approaches to calculate the required sensitivities are discussed, including issues associated with numerical differentiation, numerical integration, and post-processing. Trimming of the uncertainty tree to remove insignificant contributions is discussed. The article concludes with a best practices guide in the Appendix to uncertainty propagation in experimental engine combustion post-processing, which includes suggested post-processing techniques and down-selected functional relationships for uncertainty propagation.

Abstract One of the key factors for accurate mass burn fraction and energy conversion point calculations is the accuracy of the compression ratio. The method presented in this article suggests a workflow that can be applied to determine or correct the compression ratio estimated geometrically or measured using liquid displacement. It is derived using the observation that, in a motored engine, the heat losses are symmetrical about a certain crank angle, which allows for the derivation of an expression for the clearance volume [1]. In this article, a workflow is implemented in real time, in a current production engine indicating system. The goal is to improve measurement data quality and stability for the energy conversion points calculated during measurement procedures. Experimental and simulation data is presented to highlight the benefits and improvement that can be achieved, especially at the start of combustion.

Abstract Turbocharging can provide a low cost means for increasing the power output and fuel economy of an internal combustion engine. Currently, turbocharging is common in multi-cylinder engines, but due to the inconsistent nature of intake air flow, it is not commonly used in single-cylinder engines. In this article, we propose a novel method for turbocharging single-cylinder, four-stroke engines. Our method adds an air capacitor-an additional volume in series with the intake manifold, between the turbocharger compressor and the engine intake-to buffer the output from the turbocharger compressor and deliver pressurized air during the intake stroke. We analyzed the theoretical feasibility of air capacitor-based turbocharging for a single-cylinder engine, focusing on fill time, optimal volume, density gain, and thermal effects due to adiabatic compression of the intake air.

Abstract Two new misfire detection indexes for single-cylinder motorcycle engines—dubbed gap distance (GD) and gap slope (GS)—are proposed in this study. GD and GS quantify the change in engine angular acceleration using the tooth time measured by the crankshaft position sensor (CKPS). GD is defined as the product of the spacing distance I (the distance from the top dead center at the explosion stroke [TDC2] to the engine speed trend line parallel to the engine speed axis) and spacing distance II (the distance from the bottom dead center at the expansion stroke [BDC2] to the engine speed trend line parallel to the engine speed axis). GS is defined as the difference between the two slopes between the engine speed inclination line and the engine speed trend line. Here the engine speed trend line connects two engine speeds at the top dead center at the intake stroke (TDC1) of the current and subsequent cycles.

Abstract A modular, stationary IC engine blow rig for differential and integral flow field measurements using particle image velocimetry (PIV) has been developed. Unlike conventional PIV blow rigs, the given design is capable of operating under near-reality charge air conditions, that is, highly pressurized, hot intake air supply at high flow rates. Its conceptual flexibility as well as peripheral infrastructure allow for comprehensive and wide-ranging flow field analysis. Because of a modular architecture, it is neither confined to a specific cylinder head design nor limited solely to the application of PIV for differential flow field analysis. It also already accounts for direct inlet flow determination through an additional PIV access point upstream of the cylinder head. The inlet and outlet ducts have been designed with regular shapes and smooth walls, such that a digital twin-type CFD model of the blow rig is conveniently feasible.

Abstract Three-dimensional patterns representing crosshatched plateau-honed cylinder bores based on two-dimensional Fast Fourier Transform (FFT) of measured surfaces were generated and used to calculate pressure flow, shear-driven flow, and shear stress factors. Later, the flow and shear stress factors obtained by numerical simulations for various surface patterns were used to calculate lubricant film thickness and friction force between piston ring and cylinder bore contact in typical diesel engine conditions using a mixed lubrication model. The effects of various crosshatch honing angles, such as 30°, 45°, and 60°, and texture heights on engine friction losses, wear, and oil consumption were discussed in detail. It is observed from numerical results that lower lubricant film thickness values are generated with higher honing angles, particularly in mixed lubrication regime where lubricant film thickness is close to the roughness level, mainly due to lower resistance to pressure flow.

Abstract The following work presents a new concept for optical accessibility of a single-cylinder medium-speed large-bore marine engine from the concept development to the implementation and feasibility investigation in a test bench observing the flame chemiluminescence of dual-fuel (DF) combustion. The design’s feasibility is verified using conjugated heat transfer (CHT) and finite element method (FEM) simulation during the whole design process presented herein. Assumptions made for the simulation, e.g., of the mount between the optical component and the steel engine parts, are evaluated in pretesting setups presented and described as follows. The optical access is made to withstand steady-state full-load operating conditions and is proofed so. The optical access is designed for an engine with a bore of 350 mm and a stroke of 440 mm.

Abstract Stratified lean combustion has proven to be a promising approach for further increasing the thermal efficiency of gasoline direct injection engines in low load conditions. In this work, a new injection strategy for stratified operation mode is introduced. A side and a central-mounted solenoid multi-hole injector are simultaneously operated in a single-cylinder engine. Thermodynamic investigations show that this concept leads to improved stability, faster combustion, reduced particle number emissions, and lower fuel consumption levels compared to using only one injector. Experiments at an optical engine and three-dimensional computational fluid dynamics (CFD) simulations explain the improvements by a more compact mixture and reduced piston wetting with two injectors. Finally, the application of external EGR in combination with the above concept allows NOx emissions to be effectively kept at a low level while maintaining a stable operation.

Abstract Realizing the potential of the gasoline direct injection (GDI) concept lies in effectively stratifying the charge at different engine operating conditions. This is generally obtained by properly directing the air and fuel through carefully oriented intake port(s) and fuel spray and appropriately changing injection parameters. However, robust methods of charge stratification are essential to extend the lean operating range, particularly in small GDI engines. In this work, a novel piston shape was developed for a 200 cm3, single-cylinder, four-stroke gasoline engine to attain charge stratification. Stratification of charge is achieved even when the fuel was injected early in the intake stroke by a specially shaped wedge on the piston crown that produced twin vortices during compression and physically separated the charge into two sides in the combustion chamber.