Striving to maintain the concentration of CO2 in the Earth's atmosphere at a level that guarantees blocking the development of the greenhouse effect, results in the need to introduce "new" energy carriers to be used in vehicles. Undoubtedly, such an energy carrier is "green" hydrogen (obtained from renewable resources). The concept is not new. It was developed since the 1930s. Today, it is gaining a new momentum as the need to reduce CO2 emissions is obvious. However, obtaining energy from renewable resources has its limitations. For example, a solar farm needs a lot of space. Therefore, it is advisable to assess the operational hydrogen consumption, especially in the long-term operation of vehicles. This will allow to evaluate the general demand for a given type of fuel for the planned fleet. The paper presents a method of assessing the cumulative fuel consumption (in this case hydrogen) necessary to obtain the assumed vehicle service life.
The increasing demand for higher power densities of the Internal Combustion engine (ICE) requires higher peak cylinder pressures to improve efficiency and fuel economy. This drives higher in-cylinder temperatures which result in the piston, in particular those made of aluminium, operating at temperatures close to material limits. To address this requires analytical tools that accurately predict piston temperatures to prevent over-design or potential failure of the piston component. These tools need to predict the heat flow from combustion through the piston and rings to the surrounding structure, whilst including the contribution of cooling due to piston cooling jets, which is the focus of this study. This paper presents new analytical methods for predicting the thermal boundary conditions on the under-crown of the piston that have a piston cooling jet, using both Computational Fluid Dynamics (CFD) and semi-empirical correlations.
The environmental impact of heavy-duty vehicles powered by natural gas is considered to be lower than that of equivalent Diesel-powered vehicles. Consequently, the share of vehicles using either compressed natural gas (CNG) or liquified natural gas (LNG) is increasing and their emission characteristics need to be addressed in more detail. Since the functionality of most Euro VI-compliant engines is based upon stoichiometric combustion strategy (air-fuel ratio), the aftertreatment system (ATS) might be limited to an efficient three-way catalyst. With ever-increasing prices on PGMs over the past few years, three-way catalyst products have been exposed to wild fluctuations in cost that have had great impacts on their affordability. Given that stoichiometric operation is the most widely used calibration for HD natural gas engines, the trade-off between efficiency, calibration and PGM cost must be constantly re-evaluated.
Pollution is a major concern in India, Government has moved to BS-VI emission norms in 2020 across the country directly from BS-IV skipping BS-V. Exhaust emissions are the non-useable gaseous waste products produced during the combustion process. "Exhaust gas" is the standard term used to describe the waste gas from internal combustion engines. In addition to harmless products such as water vapor, carbon dioxide and nitrogen, engine exhaust also contains pollutants, which are harmful to humanity and the environment: carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxide (NOx). Exhaust emission can be controlled broadly into two category, 1) Before Combustion: Air fuel control equipment. 2) After combustion: After treatment equipment. In these both areas, much of work has been done so far to achieve BS-VI emissions. However, one spot left out, meeting of these two categories is combustion chamber.
Formula One (F1) is considered to be the forefront of innovation for the automotive and motorsport industry. One of the key provisions has been towards the inclusion of the Energy Recovery System (ERS) since 2014 in F1 regulations. ERS comprises Motor Generator Unit-Heat (MGU-H), Motor Generator Unit-Kinetic (MGU-K) and an Energy Storage (ES). This has not only converted the conventional powertrain into a hybrid power-split device, but also imposed constraints on the fuel energy available, energy recovered and deployed by MGU-K, and charge stored in ES, along with various other parameters. Although the objective for a F1 race is to minimize lap-time, it is obvious that there is no unique control path or decision to meet this objective. This builds up needs to optimally control the power-split and energy of the system.
Meeting strict current and future emissions legislation necessitates development of computational tools capable of predicting the behaviour of combustion and emissions with accuracy sufficient to make correct design decisions while keeping computational cost of the simulations amenable for large-scale design space exploration. While detailed kinetics modelling is increasingly seen as a necessity for accurate simulations, the computational cost can be often prohibitive, prompting interest in simplified approaches allowing fast simulation of reduced mechanisms at coarse grid resolutions appropriate for internal combustion engine simulations in design context. In this study we present a simplified Well-stirred Reactor implementation coupled with 3D CFD Ricardo VECTIS solver and investigate accuracy of this approach when combined with a single-parameter combustion calibration based on bulk reaction rate tuning for ECN n-dodecane Spray A benchmark.
The conversion to sustainable fuels, like hydrogen and biofuels, in the internal combustion engines requires enhancing the efficiency of these engines in order to maximize the benefit achieved by this conversion. Regardless the type of the fuel, great development possibilities are seen in reducing the friction of the piston group. Analyzing the cylinder liner deformation is essential to understand the behavior of the piston rings - cylinder liner (PRCL) coupling in the hot operation state. This paper describes the liner deformation at the hot operation state over the liner depth for different operational point. To do so, a validated mathematical model based on a physical model of a terminal cylinder in an internal combustion engine is introduced. The validated mathematical model is then simulated using FEM software to numerically calculate liner deformations at different operational conditions.
Opposed-Piston 2-Stroke (OP-2S) engines have the potential to achieve higher thermal efficiency than a conventional diesel engine. The uniflow scavenging process is difficult to control over a wider range of speed and loads due to its sensitivity to pressure dynamics, port timings, and port design. Specifically, the angle of the intake ports can be used to generate swirl which has implications for open and closed cycle effects. This study proposes an analysis of the effects of port angle on the in-cylinder flow distribution and combustion performance using computational fluid dynamics of an opposed-piston two-stroke engine. Large Eddy Simulations (LES) was used to model turbulence given its ability to predict in-cylinder mixing and cyclic variability. A three-cylinder model was validated to experimental data collected by Achates Power and the grid was verified using an LES quality approach proposed by Pope et al.
Stochastic Preignition (SPI) is something that has been a significant impact to companies developing turbocharged direct injection spark ignited engines over the last 20 years. It is becoming clearer what fuel properties are related to the cause of SPI, whether directly with fuel preparation in the cylinder, or mechanisms related to the deposit build up Which contributes to follow on SPI events. The purpose of the paper is to provide a literature review about the fuel properties of interest, giving special attention to compounds from the fuel and fuel additives that can contribute to the deposit build up in engines. In addition, a review of those market fuel properties will be presented which demonstrate potential areas of concern around the globe.
The maritime transport sector is at the forefront of the main sources for GHG. fuel conversion from heavy fuel oil (HFO) to LNG-based fuel, of which the main component is methane, is considered as a suitable and practical solution for that purpose. Meanwhile, the GHG reduction is limited to 27% from HFO which is not enough to fulfill the future near-zero carbon level. The vast majority of LBGEs adopt the pre-combustion chamber (PC) configuration that can promote premixture combustion in the main combustion chamber (MC) thanks to torch flame ejection from nozzle holes of the PC. However, the PC is sometimes specified as a starting point of the pre-ignition phenomenon that is a major obstacle for LBGEs to improve their thermal efficiency, and too strong ejection may result in a misfire of the premixture in the MC and in a large cyclic variation of the MC combustion.
The current work utilizes computational fluid dynamics to unravel the jet-flow and turbulence-chemistry interactions for different pistons in a pre-chamber combustion engine fueled with methane. Previous works identified that the interaction of the jets with the main chamber flow and piston wall are key aspects for the local turbulent flame speed and overall burning duration. The combustion process is modeled with the G-Equation model; the laminar flame speed was tabulated from a methane oxidation mechanism reduced from the GRI 3.0 and the turbulent flame speed was computed using Peters’ correlation. The simulations were run for a full cycle, starting at the exhaust valve opening. A homogeneous charge of methane is considered at the intake port, maintaining a global λ = 1.8, while 3% of total energy fuel is added through the pre-chamber. To evaluate further aspects of jet-piston interaction, an additional case with jets aiming at different angles within the main chamber was assessed.
Interaction between a diesel spray and piston plays a significant role in overall combustion and emissions performance in compression-ignition engines. For combustion systems that rely on spray-piston interaction strongly, such as a stepped-lip piston, it is essential to design the lip feature with respective to spray targeting and the following charge motion. In this study, a numerical campaign using computational fluid dynamics (CFD) simulation was carried out to optimize a stepped-lip combustion system at a 22:1 compression ratio (CR) for both performance and emissions. This is substantial step up in CR from stock value of 17:1 for the same engine platform. A machine learning model was used to identify the best combination of features from a design space involving hundreds of potential piston designs and injector nozzle configurations.
OTA (over the air) updates help automotive manufacturers to reduce vehicle warranty and recall costs. Vehicle recall is expensive, and many automotive manufacturers have implemented OTA updates. Updating parameters for connected vehicles can be challenging when dealing with thousands of vehicles across different regions. For example, how does the manufacturer prioritise which vehicles need updating? Environmental and geographical factors affect degradation rates and vehicle in hotter regions or congested cities may degrade faster. For EVs, updating the BMS (battery management system) parameters requires careful analysis prior to the update being deployed to maximise impact and reduce the likelihood of adverse behaviour being introduced. The analysis overhead increases with the number of vehicles. This is because it requires simulating and optimisation of the fleet BMS calibration in a digital twin environment.
Gasoline compression ignition is a promising strategy to achieve high thermal efficiency and low emissions with limited modifications to the conventional diesel engine hardware. It is a partially premixed concept which derives its superiority from higher volatility and longer ignition delay of gasoline-like fuels combined with higher compression ratio typical of diesel engines. In this work, the influence of injection strategy on combustion and engine performance is investigated. Different injection strategies covering early pilot and late pilot injection strategy as well as a combination of port-fuel and direct injection are studied to understand their impact on combustion and performance of the engine. Additionally, a comparison of these injection strategies at different compression ratios, 17 and 20.5 and the effect on combustion is provided.
The major challenge for developing a gearbox for an electric hyper cars is to confine it within a tight design space whilst carrying enormous power density and torque. This unique situation poses a design challenge for fatigue failures. The intent of the paper is to develop analytical methodology to estimate the fatigue life using FKM approach with 97.5 percentage survival probability for the given duty cycle. Case hardened materials are common in powertrain engineering for shafts and gears and FKM provides with adequate material information to estimate the utilisation. A method is derived from FKM guideline to estimate component fatigue limit for constant amplitude with mean stress correction based on the material fatigue limit. Stress gradient and stress concentration factor is accounted to estimate variable amplitude fatigue strength of the component. A Miner elementary approach is used to evaluate the cumulative damage of the duty cycle.