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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" />
    <description></description>
    <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>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
    </image>
    <item>
      <title>The Technological Concept of a Self-Adjusting Segmented Ceramic
                    Sealing System for a Turboshaft Engine with Isochoric Combustion</title>
      <link>https://trid.trb.org/View/2656985</link>
      <description><![CDATA[
                
                The article presents self-adjusting segmented ceramic seals designed for a novel
                    turboshaft engine operating according to the Humphrey thermodynamic cycle. The
                    sealing system is an integral part of the developed engine concept, which
                    features rotating isochoric combustion chambers. The seals utilize centrifugal
                    force as the sealing force, enabling uniform sealing regardless of thermal
                    conditions and associated deformations. The sealing consists of segments with
                    adjustable dimensions in both circumferential and transverse directions. The
                    sealing elements should be made of Si3N4 ceramic,
                    characterized by high thermal resistance (1300°C) and low thermal expansion
                        (3.2•10-6/°C). The article presents three different variants of
                    sealing systems, differing in terms of the technological possibilities of their
                    manufacturing. Special treatments must be applied to ensure high machining
                    accuracy of the sealing elements. The proposed sealing system is a critical
                    point in the design of an engine with isochoric combustion chambers. Successful
                    sealing is key to the implementation of the Humphreys thermodynamic cycle, which
                    offers higher engine efficiency compared to classical turboshaft engines
                    available on the market. The article concludes with the presentation of a model
                    for experimental investigations, along with its thermal analysis.
            ]]></description>
      <pubDate>Fri, 23 Jan 2026 16:42:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/2656985</guid>
    </item>
    <item>
      <title>A Study on Combustion Process in Hydrogen/Hydrotreated Vegetable Oil
                    Dual-Fuel Operation Using Hydroxyl Radical Chemiluminescence</title>
      <link>https://trid.trb.org/View/2656983</link>
      <description><![CDATA[
                
                This study investigated the combustion processes in hydrogen dual-fuel operation
                    using hydrotreated vegetable oil (HVO) and diesel fuel as pilot fuels. The
                    visualizations of hydrogen dual-fuel combustion processes were conducted using
                    hydroxyl radical (OH*) chemiluminescence imaging in an optically accessible
                    rapid compression and expansion machine (RCEM), which can simulate a compression
                    and expansion stroke of a diesel engine. Pilot injection pressures of 40 and 80
                    MPa and injection quantities of 3, 6 mm3 for diesel fuel and to match
                    the injected energy, 3.14, 6.27 mm3 of HVO were tested. The total
                    excess air ratio was kept constant at 3.0. The RCEM was operated at a constant
                    speed of 900 rpm, with in-cylinder pressure at top dead center (TDC) set to
                    approximately 5.0 MPa. Results demonstrated that using HVO as pilot fuel,
                    compared to diesel fuel, led to shorter ignition delay and combustion duration.
                    OH* chemiluminescence imaging revealed that longer ignition delays observed with
                    diesel fuel resulted in pilot mixture ignition downstream near the piston bowl
                    wall, followed by flame propagation into the hydrogen–air mixture. In contrast,
                    the shorter ignition delays characteristic of HVO caused the pilot mixture to
                    ignite between the injector and the piston bowl wall, with subsequent flame
                    propagation into the hydrogen premixture.
            ]]></description>
      <pubDate>Fri, 23 Jan 2026 16:42:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/2656983</guid>
    </item>
    <item>
      <title>Tailpipe NOx Emissions Modeling of a Heavy-Duty Diesel Truck Using
                    Deep Learning Methods</title>
      <link>https://trid.trb.org/View/2656982</link>
      <description><![CDATA[
                
                This study develops deep learning (DL) long–short-term memory (LSTM) models to
                    predict tailpipe nitrogen oxides (NOx) emissions using real-driving on-road data
                    from a heavy-duty Class 8 truck. The dataset comprises over 4 million data
                    points collected across 11,000 km of driving under diverse road, weather, and
                    load conditions. The effects of dataset size, model complexity, and input
                    feature set on model performance are investigated, with the largest training
                    dataset containing around 3.5 million data points and the most complex model
                    consisting of over 0.5 million parameters. Results show that a large and diverse
                    training dataset is essential for achieving accurate prediction of both
                    instantaneous and cumulative NOx emissions. Increasing model complexity only
                    enhances model performance to a certain extent, depending on the size of the
                    training dataset. The best-performing model developed in this study achieves an
                        R2 higher than 0.9 for instantaneous NOx emissions and less than
                    a 2% error for cumulative NOx emissions on the test data. Furthermore, the model
                    achieves an F1 score above 0.9 in determining whether NOx emissions comply with
                    emission standards. The developed DL tailpipe emission models in this study have
                    diverse applications based on the amount and type of available input data,
                    including engine and aftertreatment system control, diagnostics, and vehicle
                    system-level simulations. These applications collectively contribute to
                    minimizing NOx emissions of vehicles to meet stringent transportation emission
                    standards.
            ]]></description>
      <pubDate>Fri, 23 Jan 2026 16:42:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/2656982</guid>
    </item>
    <item>
      <title>Improving Late Pilot Injection Strategy in Dual-Fuel Diesel/Methane
                    Engines through Supercharging and Hydrogen Enrichment</title>
      <link>https://trid.trb.org/View/2656987</link>
      <description><![CDATA[
                
                In this study, a novel dual-fuel combustion strategy is investigated, employing
                    late pilot injection in diesel–methane engines to improve performance and reduce
                    emissions. The engine was first tested with conventional diesel and methane,
                    exploring a wide range of pilot injection timings, injection pressures, and
                    intake boost pressures. Subsequently, experiments were repeated using a
                    methane/hydrogen blend to assess the influence of hydrogen addition. Results
                    show that, when using only methane, delayed pilot injections have minimal
                    effects on engine performance. In naturally aspirated operation, unburned
                    hydrocarbons and carbon monoxide are reduced, while in supercharged conditions,
                    emissions increase; however, they remain within acceptable limits. Nitrogen
                    oxides and particulate matter reach their lowest levels with delayed injection.
                    Introducing hydrogen reduces engine performance and hydrocarbons and carbon
                    monoxide emissions; notably, it suppresses the typical nitrogen oxides increase
                    associated with hydrogen, while also lowering particulate matter. These findings
                    demonstrate that combining late pilot injections with hydrogen addition and
                    supercharging is a promising strategy for improving dual-fuel engine efficiency
                    and emissions, offering a potential pathway toward cleaner combustion.
            ]]></description>
      <pubDate>Fri, 23 Jan 2026 16:42:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/2656987</guid>
    </item>
    <item>
      <title>A Review of the Application and Research Progress of Turbulent Jet
                    Ignition Technology</title>
      <link>https://trid.trb.org/View/2639315</link>
      <description><![CDATA[
                
                For the sustainable development of human society, energy saving, emission
                    reduction, and carbon reduction are urgent challenges to be addressed in the
                    energy industry. As a power device for energy conversion in the transportation
                    sector, the internal combustion engine also needs to enhance its thermal
                    efficiency while cutting pollutant emissions. To meet the current stringent
                    requirements, lean combustion has been widely studied as an effective strategy.
                    However, the ignition difficulty resulting from lean burn needs to be addressed.
                    As a high-energy ignition system, the prechamber turbulent jet ignition can
                    accelerate in-cylinder combustion, thereby enhancing engine efficiency and
                    reducing emissions. Thus, it is considered a promising technology. This review
                    reveals efforts to apply prechamber ignition systems to optimize combustion in
                    the engine characterized by low-carbon fuels and low-emission features. First,
                    this article briefly introduces the evolution of the prechamber turbulent jet
                    ignition technology. Second, the ignition mechanism, the influence of fuel in
                    the prechamber and structure of prechamber on the combustion performance of the
                    spark ignition engine are emphatically introduced. The structural parameters
                    like nozzle diameter, nozzle orientation, nozzle number, and prechamber volume
                    have a significant effect on the in-cylinder combustion. This review summarizes
                    the research achievements regarding the structural parameters. Finally, this
                    study demonstrates the performance improvement of engines equipped with
                    turbulent jet ignition technology.
            ]]></description>
      <pubDate>Wed, 10 Dec 2025 16:07:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2639315</guid>
    </item>
    <item>
      <title>An Open-Source Solenoid Injector Driver Circuit for Fuel Injection
                    Research</title>
      <link>https://trid.trb.org/View/2631603</link>
      <description><![CDATA[
                
                Common rail, high-pressure electronic fuel injection is one of the primary
                    technologies enabling high-efficiency and low emissions in modern diesel
                    engines. Most fuel injectors utilize an actively controlled solenoid valve to
                    actuate a needle that modulates the fuel supply into the combustion chamber. The
                    electrical drive circuit for the injector requires extensive development costs,
                    and thus, most designs are proprietary in nature, making it difficult to perform
                    academic studies of the fuel injection processes. This research presents an
                    injector driver circuit to control one or more solenoid injectors simultaneously
                    for research-based injector development efforts. The electrical circuit was
                    computationally modeled and optimized iteratively, and then, electronic hardware
                    was developed to demonstrate control of a Bosch CRIN3 solenoid diesel injector
                    as proof of concept. In addition, the injector performance was quantified by the
                    fuel rate of injection (ROI) profiles obtained in a test rig utilizing the
                    momentum flux method. Results show that the electronic control inputs do not
                    affect the initial fuel ROI profile, which is impacted mainly by the injector
                    geometry and associated fluid dynamics effects.
            ]]></description>
      <pubDate>Wed, 26 Nov 2025 14:13:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2631603</guid>
    </item>
    <item>
      <title>A Comprehensive Study on the Effect of Compression Ratio and Pilot
                    Injection Strategy on Alcohol Compression Ignition</title>
      <link>https://trid.trb.org/View/2631605</link>
      <description><![CDATA[
                
                Achieving compression ignition (CI) with ethanol, a renewable fuel, comes with
                    challenges because of its much lower cetane number compared to diesel.
                    Additionally, ethanol’s high cooling potential and high volatility compared to
                    diesel also offer challenges and opportunities to achieving robust,
                    high-efficiency CI. Increasing the compression ratio (CR) and expanding the
                    injection strategy beyond a conventional close-coupled pilot-main diesel
                    injection strategy can help overcome these challenges.
                This work experimentally tested ethanol CI with several different injection
                    strategies with CRs ranging from 16.3 to 22.3. The results showed that in
                    homogeneous charge CI (HCCI), increasing the CR improved thermal efficiency but
                    incurred a combustion efficiency penalty. In any CI concept, increasing the CR
                    lowered the required intake temperature to achieve ignition. Using close-coupled
                    pilot injections is an effective way to achieve ethanol CI, but it was also
                    shown that HCCI-like intake stroke “pilot” injections offer a new avenue of
                    ethanol CI. With a 25% pilot injection during the intake stroke, stable ethanol
                    CI was achieved at 6 bar IMEPg with an intake temperature of 330 K using a CR of
                    20.0. There was a ~1 percentage point thermal efficiency benefit and ~50%
                    reduction in NOx, though there was also a 1 percentage point combustion
                    efficiency penalty. At lower loads, it was more beneficial to run with more fuel
                    in the intake stroke pilot.
                Finally, experiments showed that the NOx emissions decreased from 5.75 g/kWh to
                    3.43 g/kWh at 6 bar IMEPg by increasing the CR from 16.3 to 20.0 and reducing
                    the intake temperature by 60 K. Even with matched intake temperature, the
                    engine-out NOx was 4.57 g/kWh with a CR of 20.0. CFD simulations showed that
                    this was due to the higher CR having a more rapid expansion process, cooling the
                    diffusion flames more rapidly.
            ]]></description>
      <pubDate>Wed, 26 Nov 2025 10:45:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/2631605</guid>
    </item>
    <item>
      <title>Effect of Fuel Injection Strategies on Performance, Combustion, and
                    Emission Characteristics of Diesel–Diethyl Ether–Fueled Compression Ignition
                    Engine</title>
      <link>https://trid.trb.org/View/2631610</link>
      <description><![CDATA[
                
                This experimental study compared a blend of diesel–DEE (DEE 40% v/v in diesel)
                    with baseline diesel. This experimental study assesses different fuel injection
                    strategies for controlling the in-cylinder charge stratification, such as
                    single, double, and triple injections. The peak in-cylinder pressure under the
                    partially premixed combustion mode was higher than conventional diesel
                    combustion. Higher in-cylinder pressure with increasing dwell time was observed
                    under triple injections. Retarding pilot injections increased the peak
                    in-cylinder pressure. Conventional diesel combustion mode exhibited the highest
                    brake thermal efficiency and lowest emissions with all injection strategies. A
                    longer dwell time of 12° CA showed higher brake thermal efficiency, nitric
                    oxide, and carbon monoxide emissions, whereas hydrocarbon emissions were lower
                    compared to a shorter dwell time of 6° CA. Hydrocarbon and carbon monoxide
                    emissions increased, but nitric oxide and brake thermal efficiency were reduced
                    by advancing pilot injections. The diesel–DEE blend exhibited slightly lower
                    brake thermal efficiency than baseline diesel at all injection strategies,
                    except for the conventional diesel combustion mode. Diesel–DEE blend exhibited
                    higher hydrocarbon and carbon monoxide emissions than baseline diesel, but
                    nitric oxide emissions were lower.
            ]]></description>
      <pubDate>Wed, 26 Nov 2025 10:45:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/2631610</guid>
    </item>
    <item>
      <title>Numerical Simulation and Optimization of Engine Cooling System Based
                    on One-Dimensional and Three-Dimensional Coupling Analysis
                    Method</title>
      <link>https://trid.trb.org/View/2623798</link>
      <description><![CDATA[
                
                The design of motorcycle engine cooling systems is often hampered by a trade-off
                    between computational efficiency and simulation accuracy, making optimized
                    design iterative and costly. A streamlined, coupled 1D–3D methodology, validated
                    across diverse engine configurations, is needed to address this challenge. This
                    study develops and validates an iterative simulation framework to efficiently
                    optimize cooling systems for various motorcycle engines. The 1D system model
                    defines the performance targets, while 3D CFD analysis enables detailed
                    component optimization (water jackets, radiator airflow); an iterative process
                    ensures the target fulfillment. The 1D–3D coupling analysis methodology is
                    applied to single-, two-, and four-cylinder engines. Results show that the
                    coolant flow velocity within the water jackets are sufficient to ensure
                    effective heat removal of engines and confirms the rational layout design of
                    water jackets. The radiator inlet coolant temperature for the original design of
                    those three engines cooling are 109°C, 107°C, 103°C, respectively. Optimizations
                    (fan shroud redesign, impeller width increase, airflow outlet redesign, air
                    guiding device, radiator shield, wind shielding area reduction, cover removal)
                    are made to increase the radiator airflow velocity by 34.92%, 12%, 7.5%,
                    respectively, and successfully reduces the radiator inlet temperatures below the
                    100°C target (from 109°C to 99°C, 107°C to 100°C, and 103.8°C to 99.2°C,
                    respectively), with results validated experimentally. The deviation between
                    simulation and experiments is below 7%, confirming the overall reliability and
                    accuracy of the simulation model. The study provides a validated, scalable
                    framework for optimizing motorcycle engine cooling systems, balancing accuracy
                    with efficiency. Its applicability to the cases presented suggests potential for
                    broader use in hybrid and electric powertrain thermal management.
            ]]></description>
      <pubDate>Thu, 13 Nov 2025 16:13:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2623798</guid>
    </item>
    <item>
      <title>Assessing Engine Dynamics, Fuel Efficiency, and Emission
                    Characteristics with HHO-Enriched Fuel: A System-Level Evaluation of a
                    HydroBoost™ Technology</title>
      <link>https://trid.trb.org/View/2623794</link>
      <description><![CDATA[
                
                In the present work, the effect of HHO addition to gasoline was investigated
                    using HHO produced via the HydroBoost™ electrolysis technology—a system
                    specifically designed to overcome the limitations of conventional electrolysis
                    methods, such as electrode degradation, low efficiency, and safety concerns.
                    Engine performance, fuel behavior, and emission characteristics were evaluated
                    both with and without HHO enrichment. A comprehensive four-phase testing
                    protocol was adopted to simulate various real-world driving conditions. Through
                    a multi-parameter assessment—including fuel economy (FE), engine response under
                    different load conditions, fuel savings accounting for parasitic load, total
                    volatile organic compounds (TVOC), and greenhouse gas (GHG) emissions—it was
                    demonstrated that HHO addition significantly enhances both the performance and
                    emission characteristics of a gasoline-powered internal combustion engine.
                    Statistical significance of these parameters was assessed across four phases,
                    with five of the seven parameters found to be significant. Combustion
                    enhancement leads to reduced fuel mass consumption and improved energy
                    utilization, demonstrating an overall improvement in system efficiency, while
                    maintaining mass balance. These findings are particularly important as they
                    validate the real-world viability of using HHO produced from an improved and
                    safer electrolysis system.
            ]]></description>
      <pubDate>Thu, 13 Nov 2025 16:13:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2623794</guid>
    </item>
    <item>
      <title>Characterization of High-Power Cold-Start Emissions Part 2: Impact of
                    Hybrid Topologies and Powertrain Sizing on Tailpipe Emissions
                    Performance</title>
      <link>https://trid.trb.org/View/2614406</link>
      <description><![CDATA[
                
                The current work is the second installment of a two-part study designed to
                    understand the impact of high-power cold-start events for plug-in electric
                    vehicles (PHEVs) on tailpipe emissions. In part 1, tailpipe emissions and
                    powertrain signals of a modern PHEV measured over three drive cycles identified
                    that high-power cold-start events generated the highest amounts of gaseous and
                    particulate emissions. The trends in emissions data and powertrain performance
                    were specific to the P2-type hybrid topology used in the study. In this second
                    part of the study, the effects of different PHEV hardware configurations are
                    determined. Specifically, the tailpipe emissions of three production plug-in
                    hybrid vehicles, operated over the US06 drive cycle, are characterized. The
                    approach compared the tailpipe emissions of the test vehicles on the basis of
                    the hybrid topologies and corresponding engine operational characteristics
                    during a high-power cold-start event. Analysis of test results showed
                    differences in the engine startup strategy for different hybrid configurations.
                    Time-resolved tailpipe emissions of CO, NOx, total unburned hydrocarbons (THC),
                    and particulates varied depending on the engine load during the cold-start. The
                    likelihood of experiencing a high-power cold-start on the US06 was dependent on
                    powertrain characteristics including e-motor size and battery state of charge.
                    The results are discussed in detail in terms of the specific regulated air
                    pollutants and the impact of the startup strategy implemented. Lastly, vehicle
                    dynamics including drag and inertia forces were found to be much lower for the
                    smaller power-split hybrid test vehicle, which reduced its propensity to
                    experience a high-power cold-start event. The findings provide insights on how
                    to manage high-power cold-start events in relation to the type of hybrid
                    configuration utilized as well as their capability to meet upcoming emissions
                    targets.
            ]]></description>
      <pubDate>Mon, 27 Oct 2025 17:07:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2614406</guid>
    </item>
    <item>
      <title>Characterization of High-Power Cold-Start Emissions Part 1: Analysis
                    of a Modern Plug-In Hybrid Electric Vehicle Tailpipe Emissions</title>
      <link>https://trid.trb.org/View/2614405</link>
      <description><![CDATA[
                
                The California Air Resources Board (CARB) and the United States Environmental
                    Protection Agency (US EPA) have recently introduced targets for tailpipe
                    emissions during high-power cold-start conditions for plug-in hybrid electric
                    vehicles (PHEVs). However, the performance characteristics of hybrid powertrains
                    and the effectiveness of cold-start strategies in PHEVs are not well known. In
                    this two-part study, the performance of a production PHEV is examined with the
                    objective of quantifying the impact of high-power cold-start events on overall
                    tailpipe emissions. High temporal fidelity data of powertrain performance and
                    tailpipe emissions generated during cold-start events for various driving
                    conditions are presented for the first time. The selected P2 hybrid vehicle was
                    tested using (i) the European Real Driving Emissions (RDE) test, (ii) the US06
                    (Supplemental Federal Test Procedure), and (iii) a custom drive cycle developed
                    for this study. Results show that driving conditions leading to the events vary
                    significantly between the drive cycles. Demand for high vehicle speed and/or
                    high traction power triggered cold-start events despite the high battery state
                    of charge. The results are discussed in detail in terms of the specific
                    regulated air pollutants and powertrain performance monitored in the 50-seconds
                    window following each cold-start event. In the companion study, tailpipe
                    emissions characteristics and engine start strategies are compared across
                    multiple hybrid topologies during a high-power cold-start event. The results
                    from both studies provide valuable new information to enable design of hybrid
                    powertrains for future PHEVs that meet the upcoming cold-start emissions
                    regulations.
            ]]></description>
      <pubDate>Mon, 27 Oct 2025 17:07:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2614405</guid>
    </item>
    <item>
      <title>An Investigation into the Impact of Cylinder Count on the Efficiency
                    of Opposed Piston Two-Stroke Compression Ignition Engines</title>
      <link>https://trid.trb.org/View/2608392</link>
      <description><![CDATA[
                
                The gas exchange process of opposed piston two-stroke (OP2S) diesel engines is
                    primarily driven by the pressure differential between the intake and exhaust,
                    making them susceptible to cylinder-to-cylinder crosstalk, and therefore to
                    cylinder count. This study examined how cylinder count influences brake
                    efficiency in OP2S engines. Using an experimentally validated 1D engine model,
                    three architectures, ranging from two to four cylinders, were created and
                    simulated across their full operating ranges. To isolate the impact of cylinder
                    count, all configurations employed identical cylinder and port geometries, and
                    identical but scaled electrically assisted turbocharger based airpaths. The
                    engines were also controlled to consistent trapped conditions at a given
                    operating condition, resulting in comparable closed-cycle efficiencies.
                    Comparisons were then made using both scaled electrified airpaths and by
                    assuming isentropic airpath work, to assess the impact of airpath efficiency on
                    the results. With electrified airpaths, the two- and four-cylinder architectures
                    had approximately 4.1%rel and 2.2%rel lower brake
                    efficiencies, respectively, than the three-cylinder configuration on average.
                    Additionally, the three-cylinder engine was found to be less sensitive than the
                    other architectures to airpath efficiency, as on a per-cylinder basis it had up
                    to a 17% lower power requirement for the turbocharger compressor, and recovered
                    up to 3% less energy from the turbocharger turbine. These trends were also
                    present when assuming isentropic airpath work, with the magnitude of the
                    efficiency penalty of the two- and four-cylinder architectures reducing to
                        0.8%rel and 0.6%rel, respectively due to the lower
                    overall magnitude of airpath power requirements. In all cases, the dominant
                    contributor to the above results was the differing scavenging characteristics of
                    the engines due to cylinder-to-cylinder interactions, demonstrating that
                    cylinder count has a measurable impact on OP2S efficiency, and should be a key
                    factor in designing an efficient OP2S engine.
            ]]></description>
      <pubDate>Thu, 16 Oct 2025 12:01:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/2608392</guid>
    </item>
    <item>
      <title>Reconstruction of Density Fields of Category L-Vehicles’ Exhaust
                    Plumes for Optimizing Remote Emission Sensing and Engine
                    Performance</title>
      <link>https://trid.trb.org/View/2608391</link>
      <description><![CDATA[
                
                Air pollution is a significant long-term public health issue, with on-road
                    traffic emissions being a primary contributor, especially in urban areas. Remote
                    emission sensing (RES) is an innovative method for large-scale monitoring of
                    vehicle emissions. It not only enables accurate detection of pollutants from
                    vehicles under real-world driving conditions but also offers actionable insights
                    to optimize engine performance. The point sampling-based RES technique involves
                    sampling the vehicle exhaust plume along the roadside with a sampling line and
                    using exhaust analyzers. In this method, the sampling line is placed alongside
                    the road for sample extraction. Thus, the sampling position and knowledge
                    regarding the spread of the exhaust plumes are crucial. Other modern RES systems
                    utilize laser absorption spectroscopy to measure the pollutants in vehicle
                    exhaust. For accurate absorption measurements, the laser’s height must align
                    with the height of the exhaust plume, and the absorption length must be known.
                    In this work, we present a gas density Schlieren imaging sensor (GDSIS) system
                    designed to visually capture, quantitatively analyze, and reconstruct the
                    density fields of exhaust plumes from category L-vehicles. By analyzing the
                    density fields, we can pinpoint the location of the highest density within the
                    exhaust plume. This information indicates the ideal height for positioning
                    sampling lines and lasers used in RES systems. Identifying this ideal height can
                    enhance the efficiency and capture rate of RES systems while also helping to
                    detect engine inefficiencies that can negatively affect performance and increase
                    emissions. Moreover, emission patterns can inform engine calibration or
                    maintenance schedules, which helps optimize fuel consumption and engine
                    response. The performance of the GDSIS system in both laboratory settings with
                    controlled gas flows and on the road with L-vehicles during emissions
                    measurement campaigns is evaluated.
            ]]></description>
      <pubDate>Tue, 14 Oct 2025 10:33:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/2608391</guid>
    </item>
    <item>
      <title>Experimental and Numerical Insights on Emissions Control with a
                    Diesel Oxidation Catalyst in Reactivity-Controlled Compression Ignition
                    Combustion Conditions</title>
      <link>https://trid.trb.org/View/2600365</link>
      <description><![CDATA[
                
                Reactivity-controlled compression ignition (RCCI), a low-temperature combustion
                    strategy, reduces oxides of nitrogen (NOx) and soot simultaneously;
                    however, high concentrations of carbon monoxide (CO) and total hydrocarbons
                    (THC) and low exhaust gas temperatures pose a significant challenge for the
                    catalytic control of tailpipe CO and THC. Diesel oxidation catalyst (DOC) is
                    generally used in compression ignition (CI) engines for CO, THC, and nitric
                    oxide (NO) oxidation. This work provides a new understanding of the performance
                    characteristics of a DOC in the RCCI combustion strategy with various
                    gasoline–diesel fuel premix ratios ranging from ~46% to ~70% at steady-state
                    operating conditions. Experimental insights from the RCCI strategy prompt
                    considerations of both CO and THC oxidations and THC trap functionalities in the
                    1D transient model of the DOC. It is observed that an increase in the fuel
                    premix ratio from 50% to 70% in RCCI shifts the CO and THC oxidation
                    characteristics curves by up to 10°C toward low exhaust gas temperatures. The
                    evolution of the catalyst surface temperature with exhaust gas temperature
                    reveals distinct stages of heat transfer, indicating a progressive shift of
                    oxidation reactions from the back to the front side of the DOC channel.
                    Furthermore, axial variations of the oxidation characteristics of the DOC reveal
                    that CO oxidizes over a narrow length of the DOC as compared to THC.
                    Additionally, a nondimensional analysis is carried out to identify
                    kinetic-controlled and mass transfer–controlled regimes of CO and THC
                    oxidations, indicating that both CO and THC are in kinetic-controlled regimes at
                    exhaust gas temperatures lower than 192°C, and transitioning into a mass
                    transfer–controlled regime above this temperature.
            ]]></description>
      <pubDate>Tue, 16 Sep 2025 11:08:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2600365</guid>
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