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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Quantitative Evaluation of AI Productivity and Quality in Design Processes: A Case Study on Engine Piston Diameter Calculation and 3D Modeling</title>
      <link>https://trid.trb.org/View/2437288</link>
      <description><![CDATA[Artificial Intelligence (AI) is currently regarded as the foremost technology for automating routine and repetitive tasks, leading to increased productivity. However, the quality of creative and design work with AI remains questionable. This paper presents a quantitative analysis of AI productivity through dynamic simulation and assesses the quality of AI results in the diameter calculation and construction of a 3D model of an engine piston as a case study. To evaluate productivity, the dynamic model segregates design tasks based on AI working hours. The quality of the formulation for calculating the engine piston diameter, derived from engine requirements, is compared with a standard formulation from a literature review. Additionally, the 3D model generated by AI is compared with a model created by human intelligence in Computer-Aided Design (CAD) software, reflecting the characteristics and properties of real engine pistons. While research on AI productivity is abundant, few studies address the quality and usefulness of AI-generated results. This study aims to evaluate these three aspects. As anticipated, the AI in a simulation model demonstrates a numerical increase in productivity as an enhancing variable. However, results for a design process involving mathematical formulation and 3D model construction lack utility without additional work. The findings lead the authors to conclude that AI in the design process can enhance productivity when used to suggest and predict design instructions, thereby saving time. Nevertheless, the AI's ability to create mathematical and 3D models is limited to simplified conditions, and further knowledge must be imparted to the AI to enable it to produce readily usable designed components.]]></description>
      <pubDate>Fri, 25 Oct 2024 14:46:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437288</guid>
    </item>
    <item>
      <title>Study of Particle Emissions Due to Brake Wear: Impact of Braking Profiles and Transport Efficiency of the Test System</title>
      <link>https://trid.trb.org/View/2437261</link>
      <description><![CDATA[Vehicular emissions represent the main responsible of the deterioration of air quality in the urban area. In the attempt to reduce both gaseous emissions and particulates from internal combustion engines, increasingly stricter regulations were introduced from European Union in the last years. These limits have led to the improvement of emissions-reduction technologies as well as the vehicle hybridization and electrification. In this scenario, vehicle emissions due to other sources rather than the propulsion systems, such as brakes and tires, have taken a significant weight. In this regard, European Commission has proposed the introduction in the next EURO 7 standard of the first-ever limit on the particles emitted by vehicle brakes. This study is devoted to improving the knowledge on the particle characteristics due to the brake wear by means of laboratory experiments thus providing support to the definition of the new standards. An experimental layout was realized consisting in a box where a brake for light duty applications was enclosed. Particles were measured in the size range from 5.6-560 nm and 0.3-10 μm through an EEPS and an OPS, respectively. A section of the standardized cycle for brake emissions and a properly realized profile characterized by intense braking were tested. The impact of the inlet air flow on the measure of the particles was also discussed. The experimental results highlighted the role of braking profiles on the physical characteristics, number and size, of the particle emissions. Low concentration and large diameter particles were emitted under urban driving conditions. On the other hand, hard braking increased the number of particles especially in the small size range.]]></description>
      <pubDate>Fri, 25 Oct 2024 14:46:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437261</guid>
    </item>
    <item>
      <title>Mitigating Thermal Stresses in Diesel Engine Pistons through Semitransparent Ceramic Coatings</title>
      <link>https://trid.trb.org/View/2437236</link>
      <description><![CDATA[The current investigation delves into the thermal stresses encountered by internal combustion engine pistons during the combustion process and explores the impact of high heat transfer through metallic engine components. The study focuses on a thermal analysis of a diesel engine piston model, incorporating a semitransparent ceramic coating on its surface. The research simulates temperature profiles on both the top surface of the piston and its substrate. The model incorporates an internal heat source, its magnitude calculated based on the coating’s heat radiation absorbance values. The investigation considers Aluminum, and Titanium ceramic-based coatings with varying heat flow duration. Comparative analysis involves assessing the results of the numerical solution of the heat equation, incorporating the internal heat source function derived from experimentally measured absorbance values of the coatings’ material. Unlike prior studies that primarily relied on evaluating temperature profiles based on ceramic coating thermoconductivity properties, this research highlights the interaction of heat flux with defined optical properties (absorbance) in the coating, imparting semitransparency. This property leads to heat accumulation within the coating. Simulation outcomes indicate that the absorbance-driven internal heat source significantly reduces heat transfer to the substrate compared to considerations based solely on thermoconductivity properties. The study introduces a mathematical model validated through numerical solutions of a differential equation of a semitransparent heat-insulating coating. The findings demonstrate the coating’s ability to enhance heat reduction compared to coatings lacking heat radiation absorbance capabilities.]]></description>
      <pubDate>Wed, 23 Oct 2024 13:29:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437236</guid>
    </item>
    <item>
      <title>Optimizing Sustainable Energy Transition: A System Dynamics Approach for Biodiesel Integration in the Galapagos Islands</title>
      <link>https://trid.trb.org/View/2437234</link>
      <description><![CDATA[The Galapagos Islands have a protected marine reserve that currently gets most of its energy—over 80%—from fossil fuels like diesel. This reliance on fossil fuels is a significant issue because it impacts the environment and sustainability of the region. Understanding this heavy dependence is important for exploring alternatives that can provide cleaner energy. This paper introduces a new simulation model based on system dynamics to explore the effects of completely replacing fossil fuels with biodiesel as a short-term solution. The simulation uses current official data for the Galapagos Islands and connects different factors to calculate their effects all at once. The goal is to identify the social, economic, energy-related, and environmental factors that make biodiesel a better choice than the currently used fossil fuels. The authors aim to find a way to keep the energy supply stable, as it mainly depends on internal combustion engines, while also quickly providing cleaner and greener energy with the resources they already have. Biodiesel can completely replace fossil fuels as an immediate short-term solution in the Galapagos Islands, providing a viable and advantageous option for energy supply that optimizes economic, social, energetic, and environmental conditions. With an adoption rate of 0.003—meaning that 3 out of every 1,000 people who currently use diesel switch to biodiesel each year—it is possible to establish biodiesel as the main fuel over a period of 5 years. In addition to using biodiesel as the only fuel source, within 5 years, it could cost 31.7% less if locally produced compared to diesel based on international prices. By 2050, CO₂ emissions could drop from 8 million tons to 1 million tons. The simulation, using real data, shows that adopting biodiesel within the current infrastructure is both viable and beneficial. It optimizes economic, social, energy-related, and environmental factors. The authors recommend this approach before adopting new technologies that claim zero CO₂ emissions, as their potential environmental impacts are still unknown.]]></description>
      <pubDate>Wed, 23 Oct 2024 13:29:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437234</guid>
    </item>
    <item>
      <title>Active Cooling for the Thermal-Management of Batteries by Means of Pulsating Channel Flows</title>
      <link>https://trid.trb.org/View/2437232</link>
      <description><![CDATA[The ability of a pulsating flow to improve heat-exchange performances in active liquid cooling systems for batteries in electric vehicles is investigated using a numerical approach. Computations are performed using operating conditions and thermo-physical parameters of the indirect liquid cooling method in which the heat is transferred from the battery to a fluid flowing inside a metal plate equipped with internal flow channels. Improvement of the heat transfer with a pulsating flow corresponds to periodic unstable phase during the pulsation period and appear at specific moments of the period according to three main parameters: velocity, frequency, and pulsation amplitude. These unstable dynamics lead to vortices spanning the entire channel and thereby improves convective heat exchanges throughout the entire cooling system, and this without modifying the existing design. The pulsation enables to activate unstable resonant frequencies, which are identified as the driver for the heat-transfer improvement. Depending on the pulsation parameters, the numerical computations allows for identifying regimes where the mean heat transfer at the internal-channel wall is enhanced by at least a factor eight. In particular, we demonstrate a successful application using a direct-numerical simulation of the full-scale problem in two-dimensions and a large-eddy simulations in three-dimensions. Cooling efficiency enhancement with this pulsating liquid cooling concept could enable either downsizing the battery thermal management system for electric vehicles or target ultra-fast charge constraints.]]></description>
      <pubDate>Wed, 23 Oct 2024 13:29:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437232</guid>
    </item>
    <item>
      <title>Sleek dual Extended Kalman Filter for Battery State of Charge and State of Health Estimation in Electric Vehicle Applications</title>
      <link>https://trid.trb.org/View/2437222</link>
      <description><![CDATA[Accurate battery state estimation is crucial for the performance, safety, and durability of electric vehicle (EV) battery management systems (BMS). The model-based dual extended Kalman filter (DEKF) has been widely used for concurrent state of charge (SOC) and state of health (SOH) estimation. However, tuning the process and measurement covariance matrices of the DEKF is challenging and typically done through a trial and error process. In this work, a sleek version of the standard DEKF is formulated relying on a second-order equivalent circuit battery model (ECM) to estimate the SOC and SOH of EV batteries. The proposed sleek DEKF estimates the capacity fading of the battery. The main advantage of the proposed formulation is the significant reduction in tuning effort. On the other hand, to account for the non-negligible resistance increase over battery lifespan, the ohmic resistance is here formulated as a function of the state of charge and available capacity. Finally, the effectiveness of the proposed method is demonstrated over laboratory data reproducing real-world driving scenarios. The results show that the proposed DEKF obtains high accuracy, comparable to the standard DEKF.]]></description>
      <pubDate>Wed, 23 Oct 2024 13:29:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437222</guid>
    </item>
    <item>
      <title>Risk Analysis for Electric Vehicle Investments: Beta Trends and Monte Carlo Insights</title>
      <link>https://trid.trb.org/View/2437224</link>
      <description><![CDATA[The electric vehicle (EV) industry is seeing a significant increase in global investments. However, it faces major challenges, especially the shortage and rising costs of key raw materials needed for battery production. This situation creates higher economic risks for investors. This paper evaluates the risks of investing in the EV industry, considering current supply chain issues related to finding raw materials, manufacturing, and selling. The evaluation uses the beta coefficient, which measures how much an individual stock’s price is expected to fluctuate compared to the overall stock market. To examine the beta coefficient’s variability, a Monte Carlo simulation is used to calculate its changes, providing insights into the volatility of assets in the EV industry relative to market conditions. The simulation is repeated multiple times until consistent results are obtained. The main goal of this study is to offer a forward-looking tool to help with investment decisions in the production of electric vehicles. This method goes beyond traditional profitability measures by including considerations of uncertainty, risk factors, and variables. These factors, though inherently uncertain and unable to be assigned specific values, are defined within a range of probabilities. The simulation results, expressed in terms of probability, show that the beta coefficient for the EV automotive sector is riskier than the reference value. By providing a detailed perspective on risk assessment, this study aims to help investors make informed and well-grounded decisions, enhancing their understanding of the challenges and opportunities in the evolving EV investment landscape.]]></description>
      <pubDate>Wed, 23 Oct 2024 13:29:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437224</guid>
    </item>
    <item>
      <title>Advanced Engineering Tools and Methodologies to Develop Fuel-Efficient and Zero-Impact H2 Engines for On- and Off-Highway Installations</title>
      <link>https://trid.trb.org/View/2437212</link>
      <description><![CDATA[The worldwide markets around the globe endure far from meeting the originally arranged primary objective outlined under the Paris Agreement on climate change in 2015: mitigating greenhouse gas (GHG) emissions to retain global average temperature rise to well below 2°C by 2100 and making every effort to stay below a 1.5°C elevation of the average temperature. Today’s emissions are rebounding from an intermediate decline during the economic downturn related to the implications coming from Covid-19 pandemic. To get back on track with the realization of the targets of the Paris Agreement, research suggests that GHG emissions should be reduced by approx. 50% by 2030 on a guiding trajectory to reach net zero by around mid-century. Although these objectives are all averaged global targets, every sector and country/market need to participate, especially prosperous and more developed countries bear in general the higher responsibility to act. In 2020 direct tailpipe emissions from transport represented around 8 GtC02e, or approx. 15% of overall GHG emissions. This number elevates to nearly 10 GtC02e, if indirect emissions from electricity and fuel supply are added, accumulating to a total amount of roughly 18%. Following the latest tendency, direct and indirect emissions in transport could reach above 11 GtCOeq by 2050. Roughly 3/4 of transport emissions are related to land-based passenger and freight road transport. Emissions from aviation and marine transport account for the remaining 24% of the 2020 emissions. Efficiency enhancement and fuel change, including electrification, allow scaled emissions mitigation in the central scenario, and sustained action will be needed to ensure that by 2030 emissions are reduced by roughly 27% from 2020 levels. Reductions are foreseen to reach nearly 78% by 2050. When indirect emissions are included, transportation provides the opportunity to eliminate around 9.4 GtCOeq of emissions by 2050 (7 GtC02eq direct and 2.4 GtC02eq indirect), or around 13% of total mitigation. In this context, carbon neutrality imposes substantial changes in the energy mix. Hydrogen (H2) is in this mainstream scenario considered to take a key role as a carbon-free and versatile energy carrier. Combustion of hydrogen in an ICE offers the potential to accelerate the introduction of carbon-neutral mobility in the short to medium term at competitive cost due to the utilization of well-proven and mature technology elements. Given the high technological maturity of internal combustion engines (ICEs), there is an increasing interest in ICEs powered by hydrogen as a CO2-free solution for all kinds of vehicles and applications, incl. racing. Depending on the application functional parameters differ in the ranking between power output, efficiency, and reliability, besides the efforts for the conversion for changing the fuel type. The major intention and aim of this paper is given by the identification and description of the major modification and adaptation needs for the conversion of a classical Diesel engine towards hydrogen operation in order to pave the fast way forward to carbon-neutral propulsion systems in the mobility sector. The detailed content of this publication displays the necessary engineering steps and provides an orientation for the utilization of an advanced toolchain to successfully convert existing mature engines straightforward and effectively into high-efficiency H2 operation with ultra-low tailpipe emission behavior according to the targeted specifications, incl. high performance attributes. It is especially foreseen to pinpoint the major hurdles and obstacles during the engine conversion process from conventional fuel usage to hydrogen operation. The paper closes with a compiling overview and examples of realized achievements, before summarizing the intention and motivation for the publication.]]></description>
      <pubDate>Wed, 23 Oct 2024 13:29:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437212</guid>
    </item>
    <item>
      <title>Numerical and Experimental Analysis of Dual Fuel Hydrogen/Diesel Combustion at Varying Engine Speed on a Single Cylinder Engine</title>
      <link>https://trid.trb.org/View/2437260</link>
      <description><![CDATA[In this study, dual fuel combustion process has been investigated numerically and experimentally in a single cylinder research engine. Two engine speeds have been investigated (1500 and 2000 rpm) at fixed BMEP of 5 bar for both engine speeds. For each engine speed two operating points have tested with and without EGR (Exhaust Gas Recirculation). The hydrogen has been injected in the intake manifold in front of the tumble intake port inlet and a small amount of diesel fuel has been introduced directly in the cylinder through two injections strategy: one pilot injection occurring Before Top Dead Center (BTDC) and one main occurring around the Top Dead Center (TDC). The dual-fuel combustion model in GT-SUITE has been used first to calibrate the combustion model by using the Three Pressure Analysis (TPA) model. This step allows the calibration of the combustion model to predict in-cylinder combustion processes. Simulations have been performed at varying mass distribution of injected diesel fuel during pilot and main injections at fixed start of pilot injection (SOIp).For both engine speeds it was found that the model predicts well the in-cylinder pressure traces, the ignition delays, the heat release rates and NOx emissions. The simulated results at varying mass distribution of injected diesel fuel between the pilot injection and the main injection, have shown that the distribution has no effect on the ignition delay times. This distribution mainly controls the combustion duration and NOx emissions. Indeed, when the amount of diesel pilot injection is increased the NOx emissions are increased by around two for all engine operations. As expected, when a small amount of EGR is used the NOx emissions are lower compared to the operations without EGR. This first step of parametric analysis of DF combustion shows that further investigations are required into the dual-fuel (H2 /diesel) combustion to optimize engine performances and emissions.]]></description>
      <pubDate>Tue, 01 Oct 2024 14:49:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437260</guid>
    </item>
    <item>
      <title>Deep Reinforcement Learning Based Application of Exhaust Gas Aftertreatment Control Using the Example of a Hydrogen Engine</title>
      <link>https://trid.trb.org/View/2437251</link>
      <description><![CDATA[Growing environmental concerns drive the increasing need for a more climate-friendly mobility and pose a challenge for the development of future powertrains. Hydrogen engines represent a suitable alternative for the heavy-duty segment. However, typical operation includes dynamic conditions and the requirement for high loads that produce the highest NOx emissions. These emissions must be reduced below the legal limits through selective catalytic reduction (SCR). The application of such a control system is time-intensive and requires extensive domain knowledge.We propose that almost human-like control strategies can be achieved for this virtual application with less time and expert knowledge by using Deep Reinforcement Learning. A proximal policy optimization (PPO) -based agent is trained to control the injection of Diesel exhaust fluid (DEF) and compared with the performance of a manually tuned controller. The performance is evaluated based on the restrictive emission limits of a possible EURO7-framework and DEF consumption. Applied to a standardized driving cycle (WHTC) and compared with the conventional application, the agent reaches similar emission values with a equally high DEF consumption. In addition, a long short-term memory (LSTM) network is trained to substitute the 1D-SCR-model and then used to train a PPO-based agent. The results of the agent interacting with the conventional 1D-model are compared to the results with the LSTM-network as environment.The results demonstrate, that the control of an exhaust gas aftertreatment system using Reinforcement Learning is very satisfactory. Further work is required to refine the proposed methodology into a fully-fledged tool for application in powertrain development.]]></description>
      <pubDate>Tue, 01 Oct 2024 14:49:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437251</guid>
    </item>
    <item>
      <title>Performance Analysis of Hydrogen Combustion under Ultra Lean Conditions in a Spark Ignition Research Engine Using a Barrier Discharge Igniter</title>
      <link>https://trid.trb.org/View/2437249</link>
      <description><![CDATA[The global push to minimize carbon emissions and the imposition of more rigorous regulations on emissions are driving an increased exploration of cleaner powertrains for transportation. Hydrogen fuel applications in internal combustion engines are gaining prominence due to their zero carbon emissions and favorable combustion characteristics, particularly in terms of thermal efficiency. However, conventional Spark-Ignition (SI) engines are facing challenges in meeting performance expectations while complying with strict pollutant-emission regulations. These challenges arise from the engine's difficulty in handling advanced combustion strategies, such as lean mixtures, attributed to factors like low ignition energy and abnormal combustion events.To address these issues, the Barrier Discharge Igniter (BDI) stands out for its capability to generate non-equilibrium Low-Temperature Plasma (LTP), a strong promoter of ignition through kinetic, thermal, and transport effects. Its surface discharge also facilitates combustion promotion across a wide area, overcoming the limitations of conventional spark systems. The research outlined in this study involves conducting experiments that integrate hydrogen (H2) with LTP discharge. Tests were carried out using a single-cylinder research engine by varying the air-fuel mixture and maintaining the same load condition and the same engine speed. Results from the application of BDI, revealed an acceleration in the evolution of the flame front when compared to conventional spark methods. This effect extended the lean stable limit of the engine, leading to reduction in the fuel consumption and emissions and improvements in the delivered power close to the engine lean stable limit. Additionally, adjustment of BDI control parameters played a crucial role in enhancing igniter performance, contributing significantly to a more comprehensive understanding of the innovative approach presented in this study.]]></description>
      <pubDate>Tue, 01 Oct 2024 14:49:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437249</guid>
    </item>
    <item>
      <title>Novel Chemical Kinetics Mechanism for Robust Simulation of Multi-Component Fuel Blends in Engine Conditions</title>
      <link>https://trid.trb.org/View/2437246</link>
      <description><![CDATA[Ammonia, with its significant hydrogen content, offers a practical alternative to pure hydrogen in marine applications and is easier to store due to its higher volumetric energy density. While Ammonia's resistance to auto-ignition makes it suitable for high-compression ratio engines using pre-mixed charge, its low flame speed poses challenges. Innovative combustion strategies, such as dual-fuel and reactivity-controlled compression ignition (RCCI), leverage secondary high-reactivity fuels like diesel to enhance Ammonia combustion. To address the challenges posed by Ammonia's low flame speed, blending with hydrogen or natural gas (NG) in the low reactivity portion of the fuel mixture is an effective approach. For combustion simulation in engines, it is crucial to develop a chemical kinetics mechanism that accommodates all participating fuels: diesel, Ammonia, hydrogen, and NG. This study aims to propose a kinetics mechanism applicable for the combustion of these fuels together. The mechanism is tailored for engine conditions, including high pressures and temperatures, and diverse chemical species concentrations. To render the mechanism suitable for computationally efficient 3-D Computational Fluid Dynamics (CFD) simulations, it is reduced and contains 82 species and 636 reactions, with N-heptane serving as the surrogate for diesel fuel. The mechanism is tuned using optimization methods to match available experimental data on ignition delay time (IDT) for N-heptane. The prediction of IDT and laminar burning velocity values by the mechanism is validated with available experimental data. Additionally, 3-D CFD and quasi-dimensional multi-zone engine simulations are conducted using the new mechanism to verify engine operating parameters against available experimental data.]]></description>
      <pubDate>Tue, 01 Oct 2024 14:49:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437246</guid>
    </item>
    <item>
      <title>Dual Injection Concept and Lean Burn Characteristics with Methanol on a SI-Engine</title>
      <link>https://trid.trb.org/View/2437245</link>
      <description><![CDATA[The research for sustainable alternative fuels for combustion engines was driven by the urgency to meet future emission regulation norms and mitigate climate change and dependency on fossil fuels. In this context, methanol emerges as a promising candidate due to its potential for greenhouse gas-neutral production methods and its advantageous characteristics for employment in SI engines. Adverse effects, such as elevated emissions due to incomplete combustion along with liner impingement and oil dilution as a consequence of the high injected fuel mass and the large enthalpy of vaporization, can be improved by a dual injection concept.The tests were conducted on a single-cylinder research engine derived from a common passenger vehicle engine. The exhaust gas composition was measured with an FTIR-analyzer employing a methanol-specific evaluation method, standard exhaust gas analyzers, and a solid particle counter system with 10 and 23 μm cut-off sizes. The ratio of DI mass to total mass injected in one cycle (xDI) was varied at low-, mid-, and high-load operation points at 2000 rpm and stoichiometric conditions. Further investigations for lean-burn concepts with a variation of xDI were carried out and evaluated based on variables such as engine performance, efficiency, and emissions.The measurements show a strong charge cooling effect for DI, thereby reducing NOx, although this effect saturates at a mid-load. By splitting the injected fuel mass, an xDI of 30 % shows the highest reduction in NOx at high-load and a reduction of unburned fuel in the exhaust gas of up to 62 %. Particle measurements indicate the interaction of methanol with the liner for both PFI and DI, leading to increased particle emissions. For high-load and dual injection with xDI = 30 % and 50 %, these emissions are found on a level one magnitude lower than compared to DI operation. Lean burn operation with dual injection shows the extension of the lean burn limit at certain points. However, the potential efficiency increase is diminished by undesirable combustion characteristics with prolonged burn durations.]]></description>
      <pubDate>Tue, 01 Oct 2024 14:49:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437245</guid>
    </item>
    <item>
      <title>Gas Exchange Optimization for a Passive Pre-Chamber Ignition System</title>
      <link>https://trid.trb.org/View/2437244</link>
      <description><![CDATA[Increasing ignition energy by replacing standard spark igniters with pre-chambers is an established combustion accelerator. With rapid combustion on the one hand, mixture dilution can be extended while maintaining the combustion stability at adequate levels. On the other hand, accelerated combustion reduces the need for knock-induced spark retarding, thus facilitating emission reduction and increases in efficiency simultaneously. A newly developed pre-chamber ignition system is introduced in this work. The influence of the system on combustion is investigated in a single-cylinder research engine. The findings can support the development of future ignition technology for passenger-vehicle-sized engines.There are two basic configurations of pre-chamber igniters: the first is known as passive pre-chamber, the second as scavenged pre-chamber. The first configuration can be realized as a simple replacement for standard spark plugs. While additional costs are minimized, the air-fuel ratio inside the pre-chamber cannot be influenced independently of the main chamber. Consequently, the major challenge for passive pre-chamber igniters is operating in engine map areas suffering from deteriorated pre-chamber gas exchange at low engine load, for example. The second configuration allows precise air-fuel ratio control inside the pre-chamber to circumvent those issues by employing a dedicated pre-chamber injector. However, the overall system cost and complexity increase drastically.Solving these issues is decisive for potential series applications. Geometrical design and adapted valve timing are considered remedies in this publication. As preparation for experimental investigations at a single-cylinder testbench, 3D-CFD simulations were employed to determine promising pre-chamber geometries in the first place. Different pre-chamber geometries have subsequently been investigated with an engine testbench to validate the findings from the simulations. Analysis of the pressure traces in the main and pre-chamber provide insight into the quality of pre-chamber gas exchange and combustion initiation. Adaptive valve actuation strategies supported the pre-chamber gas exchange, consequently leading to optimized engine behavior.]]></description>
      <pubDate>Tue, 01 Oct 2024 14:49:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437244</guid>
    </item>
    <item>
      <title>Enhancing Homogeneity and Combustion Efficiency in Gas Engines: A Novel Approach through Swirl-Inducing Air Intake Pipe Modifications</title>
      <link>https://trid.trb.org/View/2437243</link>
      <description><![CDATA[The lack of a homogeneous air-fuel mixture in internal combustion engines is a major cause of pollutant emissions, such as carbon monoxide (CO) and hydrocarbons (HC). This paper focuses on the design, simulation, and testing of a modified air intake pipe for a gas engine, incorporating deflectors to induce a swirl effect in the air-fuel mixture. To determine the optimal configuration for the deflectors and the diameter of the air intake pipe, several Computational Fluid Dynamics (CFD) simulations were conducted. The best results were then tested on a real gas engine. The primary objective of this study is to offer a solution for increasing the homogeneity level of the air-fuel mixture in gas engines, without requiring significant changes to engine components. In this case, achieving this goal involves only relatively small modifications to the air intake pipe. The results indicate that the swirl effect effectively enhances the homogeneity of the air-fuel mixture by generating higher turbulence along the air intake path. Critical to the success of the modification is the maintenance of the original pressure drop along the pipe. To compensate for the restriction caused by the deflector in the cross-sectional area of the air intake pipe, it is necessary to increase the diameter of the pipe. The most challenging aspect was achieving a reduction in CO and HC emissions due to the deflectors, rather than solely relying on the increased diameter of the air intake pipe. Importantly, the goal was to maintain engine power without a corresponding increase in fuel consumption. Contrary to the common belief that any device disrupting the free flow through the air intake pipe causes pressure losses, our findings suggest that the right configuration of pipe diameter, along with the appropriate number and positioning of deflectors, can yield better results than maintaining an unrestricted airflow. In summary, our work presents a device intended for implementation in the air intake pipe of gas engines, inducing a swirl in the air-fuel mixture without creating pressure losses compared to the original engine condition. This modification successfully reduces CO and HC levels, serving as an indicator of improved combustion resulting from a more homogeneous air-fuel mixture.]]></description>
      <pubDate>Tue, 01 Oct 2024 14:49:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437243</guid>
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