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Abstract Exhaust manifolds are one of the most important components on the engine assembly, which is mounted on engine cylinder head. Exhaust manifolds connect exhaust ports of cylinders to the turbine for turbocharged diesel engine therefore they play a significant role in the performance of engine system. Exhaust manifolds are subjected to very harsh thermal loads; extreme heating under very high temperatures and cooling under low temperatures. Therefore designing a durable exhaust manifold is a challenging task. Computer aided engineering (CAE) is an effective tool to drive an exhaust manifold design at the early stage of engine development. Thus advanced CAE methodologies are required for the accurate prediction of temperature distribution. However, at the end of the development process, for the design verification purposes, various tests have to be carried out in engine dynamometer cells under severe operating conditions.

Abstract To reduce fuel consumption and carbon dioxide (CO2) emissions from mobile air conditioning (A/C) systems, “U.S. Light-Duty Vehicle Greenhouse Gas Emissions and Corporate Average Fuel Economy Standards” identified solar/thermal technologies such as solar control glazings, solar reflective paint, and active and passive cabin ventilation in an off-cycle credit menu. National Renewable Energy Laboratory (NREL) researchers developed a sophisticated analysis process to calculate U.S. light-duty A/C fuel use that was used to assess the impact of these technologies, leveraging thermal and vehicle simulation analysis tools developed under previous U.S. Department of Energy projects. Representative U.S. light-duty driving behaviors and weighting factors including time-of-day of travel, trip duration, and time between trips were characterized and integrated into the analysis.

Abstract Although ground grading is one of the most common tasks that hydraulic excavators perform in typical work sites, proper grading is not easy for less-skilled operators as it requires coordinated manipulation of multiple hydraulic cylinders. In order to help alleviate this difficulty, automated grading systems are considered as an effective alternative to manual operations of hydraulic excavators. In this article, a sliding mode controller design is presented for automated grading control of a hydraulic excavator. First, an excavator manipulator model is developed in Simulink by using SimMechanics and SimHydraulics toolboxes. Then, a sliding mode controller is designed to control the manipulator to trace a predefined trajectory for a grading task. For a comparison study, a PI controller is used to control the manipulator to perform a grading task following the same desired trajectory and the performance is compared with those obtained by the sliding mode controller.

Abstract This article serves as a proof-of-concept and feasibility analysis regarding a variable compression ratio (VCR) engine design utilizing an exhaust valve opening during the compression stroke to vary the compression ratio instead of the traditional method of changing the cylinder or piston geometry patented by Ford, Mercedes-Benz, Nissan, Peugeot, Gomecsys, et al. [1]. In this concept, an additional exhaust valve opening was used to reduce the virtual compression ratio of the engine, without geometric changes. A computational fluid dynamic model in ANSYS Forte was used to simulate a single-cylinder, cold flow, four-stroke, direct injection engine cycle. In this model, the engine was simulated at a compression ratio of 10:1. Then, the model was modified to a compression ratio of 17:1. Then, an additional valve opening at the end of the compression stroke was added to the 17:1 high compression model.

Abstract Regulations limiting GreenHouse Gases (GHG) from Heavy-Duty (HD) commercial vehicles in the United States (US) and European Union will phase in between the 2024 and 2030 model years. These mandates require efficiency improvements at both the engine and vehicle levels, with the most stringent reductions required in the heaviest vehicles used for long-haul applications. At the same time, a 90% reduction in oxides of nitrogen (NOx) will be required as part of new regulations from the California Air Resources Board. Any technologies applied to improve engine efficiency must therefore not come at the expense of increased NOx emissions. Research into advanced engine architectures and components has identified improved turbomachine efficiency as one of the largest potential contributors to engine efficiency improvement. However this comes at the cost of a reduced capability to drive high-pressure Exhaust Gas Recirculation (EGR).

Abstract The article describes the results achieved in developing a new diesel combustion system for passenger car application that, while capable of high power density, delivers excellent fuel economy through a combination of mechanical and thermodynamic efficiencies improvement. The project stemmed from the idea that, by leveraging the high fuel injection pressure of last generation common rail systems, it is possible to reduce the engine peak firing pressure (pfp) with great benefits on reciprocating and rotating components’ light-weighting and friction for high-speed light-duty engines, while keeping the power density at competitive levels. To this aim, an advanced injection system concept capable of injection pressure greater than 2500 bar was coupled to a prototype engine featuring newly developed combustion system. Then, the matching among these features has been thoroughly experimentally examined.

Abstract Addition of hydrogen to hydrocarbons in premixed turbulent combustion is of technological interest due to their increased reactivity, flame stability and extended lean extinction limits. However, such flames are a challenge to reaction modelling, especially as the strong preferential diffusion effects modify the physical processes, which are of importance even for highly turbulent high-pressure conditions. In the present work, Reynolds-averaged Navier-Stokes (RANS) modelling is carried out to investigate pressure and hydrogen content on methane/hydrogen/air flames.

Abstract Federal Aviation Administration (FAA)’s 20 years of research and development with 200 unleaded blends and full-scale engine tests on 45 high-octane unleaded blends has not found a “drop-in” unleaded replacement for aviation gasoline (AVGAS) 100 low lead (100LL) fuel. In this study, analysis of compatibility via optimization of Lycoming O-320 engine fuelled with RON 97, RON 98, RON 100, and AVGAS was conducted using the Response Surface Methodology (RSM). Test fuels were compositionally characterized based on Gas Chromatography (GC) analysis and were categorized based on types of Hydrocarbon (HC). Basic fuel properties of fuels in this research were analyzed and recorded. For optimization analysis, engine speed and fuel were considered as the input parameters.

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 An in-cylinder combustion analysis and a computational fluid dynamics (CFD) coolant flow analysis were performed using AVL FIRE software, which provided the heat transfer boundary conditions (HTBCs) to the temperature field calculation of the cylinder head. Based on the measured material performance parameters such as stress-strain curve under different temperatures and E-N curve, creep, and oxidation data material performance, the cylinder head-gasket-cylinder block finite element analysis (FEA) was performed. According to the temperature field calculation results, the maximum temperature of the cylinder head is 200°C that is within the limit of ALU material. The temperature of the water is more than 21.1°C below the critical burnout point temperature. The high-cycle fatigue (HCF) and thermal-mechanical fatigue (TMF) analysis of the cylinder head were performed by FEMFAT software.

Abstract Direct dual fuel stratification (DDFS) strategy benefits the advantages of the RCCI and PPC strategies simultaneously. DDFS has improved control over the heat release rate, by injecting a considerable amount of fuel near TDC, compared to RCCI. In addition, the third injection (near TDC) is diffusion-limited. Consequently, piston bowl geometry directly affects the formation of emissions. The modified piston geometry was developed and optimized for RCCI by previous scholars. Since all DDFS experimental tests were performed with the modified piston profile, the other piston profiles need to be investigated for this strategy. In this article, first, a comparative study between the three conventional piston profiles, including the modified, stock, and scaled pistons, was performed. Afterward, the gasoline injector position was shifted to the head cylinder center for the stock piston. NOX emissions were improved; however, soot was increased slightly.

Abstract Diesel engines include systems for cooling, lubrication, and fuel injection and contain a variety of components. A malfunction in any of the engine systems or the presence of any faulty element influences engine performance and deteriorates its components. This research is concerned with the untimely appearance of vital cracks in the liners of a turbocharged heavy-duty Diesel engine. To find the root causes for premature failure, rigorous examinations through visual observations, material characterization, and metallographic investigations are performed. These include Scanning Electron Microscope (SEM) and Energy-Dispersive Spectroscopy (EDS), fracture mechanics analysis, and performance examination, which are also followed by Finite Element Moldings. To find the proper remedy to resolve the problem, drawing a precise and reliable picture of the engine’s operating conditions is required.

Abstract Cavitation erosion caused by high-frequency vibrating walls can appear in the cooling circuit of internal combustion engines along the liners. The vibrations caused by the mechanical forces acting on the crank drive can lead to temporary regions of low pressure in the coolant with local vapor formation, and vapor collapse close to the liner walls leads to erosion damage, which can strongly reduce the lifetime of the entire engine. The experimental investigation of this phenomenon is so time consuming and expensive, which it is usually not feasible during the design phase. Therefore, numerical tools for erosion damage prediction should be preferred. This study presents a numerical workflow for the prediction of cavitation erosion damages by coupling a three-dimensional (3D) Multi-Body-Dynamic (MBD) simulation tool with a 3D Computational Fluid Dynamics (CFD) solver.

Abstract HVAC systems of passenger cars and especially their air purification performance got more and more in focus during the last years. One reason is the overall increased attention to air quality and its effect on human health. Recently, the WHO further tightened the recommended values for many pollutants. This will likely intensify the trend to more complex systems for improving the air purification functionalities. But, up to now there is no standard method for air purification performance testing. Existing standards cover the vehicle cabin air quality only regarding material emissions. Several studies address assessing the performance of air purification functionalities in most cases by real driving tests typically performed in urban areas. This approach results in proper values for the basic efficiency of single systems.

Abstract Vehicle interior air quality is usually determined by the levels of in-cabin air pollutants, such as particulate matter (PM), gaseous air pollution (volatile organic compounds [VOCs], oxides of nitrogen [NOx], and carbon monoxide [CO]), and carbon dioxide [CO2], which reflect the freshness of indoor air. Nowadays, cabin air filters play a key role in preventing outdoor air pollutants transporting inside vehicles; hence, in-cabin air quality can be strongly associated with the filtration performance of cabin air cleaning solutions. However, challenges are existing in a standard method for assessing the performance of a cabin air filter in real-life driving conditions. This study is to develop a low-cost mobile test method for monitoring in-vehicle PM and CO2 and evaluating the performances of cabin air filters while driving the vehicles. The results reveal that certain boundary conditions are important to have a proper method for evaluating the particle removal efficiency.

Abstract This work presents a numerical study of the performance and nitrogen oxides (NOx) emissions of a conventional ethanol engine converted to work as a flex-fuel nonconventional architecture: the Split-Cycle Engine (SCE). For this study, the conventional engine fueled with hydrous ethanol was modeled and validated with data from experimental tests. Then the model was converted to operate as an SCE with two compressors and two expanders and simulated with a progressive downsizing of the compressors of the SCE. When the swept volume of the compressors was reduced to 87% of that of the expanders, the thermal conversion efficiency increased by 3.3%. Because of this, the downsized SCE was submitted to simulation runs using two different fuels: hydrous ethanol (H100) and an indolene-ethanol blend (H85). The results of the simulations were compared to the experimental results of the conventional engine.

Abstract Gasoline compression ignition (GCI) is a family of combustion strategies that can be used to achieve low emissions and fuel consumption in medium- and heavy-duty applications while taking advantage of projected cost advantages of gasoline over diesel fuel in the future. In particular, high fuel stratification GCI (HFS-GCI) has been shown to have CDC-like thermal efficiency and combustion control by utilizing near-TDC injection timings to achieve a principally mixing-controlled combustion event. The stability of HFS-GCI combustion at low loads has been shown to be the principal challenge to its implementation in production applications and in this study, a novel class of cylinder deactivation strategies to achieve stable HFS-GCI combustion down to no-load (0 kW brake power) is proposed and studied. 1D simulations were carried out in GT-POWER and coupled experiments were carried out in a single-cylinder medium-duty test cell with an on-road 87AKI gasoline fuel.

Abstract The influence of the intake valve lift of two Miller cycles on the in-cylinder flow field inside a DISI engine is studied experimentally since changes of the engine flow field directly affect the turbulent mixing and the combustion process. For the analysis of the impact of the valve timing on the general flow field topology and on the large-scale flow structures, high-speed stereo-scopic particle-image velocimetry measurements are conducted in the tumble plane and the cross-tumble plane. The direct comparison to a standard Otto intake valve lift curve reveals evidently different impacts on the flow field for both Miller cam shafts. A Miller cycle that features late intake valve closing shows a flow field comparable to the standard Otto valve timing and a tumble vortex of strong intensity can be identified.

Abstract One of the most promising techniques to reduce carbon dioxide (CO2) emissions of future combustion engines is the use of waste heat from exhaust gas with a Rankine cycle. The target of this study was to investigate the influence of engine operating parameters such as ignition timing, coolant temperature and injection parameters on the efficiency and performance of Rankine based waste heat recovery systems (WHR). This was done to gain basic knowledge about the influences of the engine operating parameters which helps to explain the system behavior under different operating conditions and second to identify the operating parameters with the highest overall system efficiency which can be used to highlight the impact of changes in engine application on the car. These first of a kind tests were performed on a state-of-the-art gasoline engine equipped with a prototype Rankine-system.

Abstract Fluid mechanical design of the cylinder charge motion is an important part of an engine development. In the present contribution an intake port geometry is proposed that can be used as a test case for intake port flow simulations. The objective is to fill the gap between generic test cases, such as the backward facing step or the sudden expansion, and simulations of proprietary intake ports, which are barely accessible in the community. For the intake geometry measurement data was generated on a flow-through test bench and a wall-modeled LES-simulation using a hybrid RANS/LES approach for near-wall regions was conducted. The objective is to generate and analyze a reference flow case. Since mesh convergence studies are too costly for scale resolving approaches only one simulation was done, but on a very fine and mostly block-structured numerical mesh to achieve minimal numerical dissipation.