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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>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Reduction mechanism of nitrogen oxides derived from post injection</title>
      <link>https://trid.trb.org/View/2630466</link>
      <description><![CDATA[It has been found that the concentration of NOₓ in exhaust gas is reduced by post-injection, which is used in the exhaust after-treatment system of diesel engines. In this paper, we investigate the mechanism of this using 0-dimensional chemical kinetic calculations and engine experiments in which the EGR rate is varied. As a result, it was found that ammonia is involved in the reduction of NOₓ, and that the generation of ammonia is related to the unburned hydrocarbons and carbon monoxide produced by the post-injection.]]></description>
      <pubDate>Mon, 09 Feb 2026 16:18:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2630466</guid>
    </item>
    <item>
      <title>Research on Abnormal Combustion in Hydrogen-Fueled Spark Ignition Engines</title>
      <link>https://trid.trb.org/View/2630447</link>
      <description><![CDATA[A knocking prediction model for combustion in hydrogen-fueled spark ignition engines was constructed and incorporated into a 1D simulation to understand the operating range of knocking and evaluate the factors affecting it, and the model was verified using engine measurement data. In the knock model, a database of the ignition delay time was constructed using detailed chemical reaction calculations that could independently consider the effects of the EGR ratio and NO concentration in the EGR gas on the ignition delay time. The results of validation using measurement data from an engine confirmed that it is possible to determine whether knocking occurs or not by using the threshold value of the in-cylinder combustion progress when the Livengood-Wu integral value equals one, considering the NO concentration in the EGR gas. In the combustion of hydrogen fuel, it was confirmed that the NO concentration in the EGR gas had a significant effect on the ignition delay time compared to PRF fuel, which simulates gasoline, and it was found that it is essential to take the NO concentration into account in the knock model.]]></description>
      <pubDate>Thu, 05 Feb 2026 11:52:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/2630447</guid>
    </item>
    <item>
      <title>A multi-fluid prediction model of anode gas recirculation ejector for real-time control of fuel cell vehicles under overall operating modes</title>
      <link>https://trid.trb.org/View/2652720</link>
      <description><![CDATA[The real-time control of the ejector-driven anode multi-fluid gas recirculation system (AGRS) is a challenging task under both critical and subcritical operating modes of proton exchange membrane fuel cell (PEMFC) for vehicles. In this paper, a concise performance prediction model for multi-fluid ejectors with a non-iterative solution is established under overall operating modes. The characteristic points (critical recirculation ratio ω[subscript ∗], critical back pressure p[subscript c∗], and reflux pressure p[subscript cb]) are expressed as three linear equations with six lumped parameters (k₁-k₆), which can be easily identified by the least squares method. Then, the subcritical recirculation ratio (ω[subscript sub]) is approximated as a quadratic function of p[subscript c] by integrating p[subscript c*], p[subscript cb], and ω[subscript *]. The feasibility and accuracy of the proposed model are validated using literature data, with additional H₂ testing result and comparison to traditional models. The model's real-time applicability is also examined. The relative errors of the p[subscript c*], p[subscript cb], and ω[subscript *] are less than -2.89%, 1.11%, and 1.60%, indicating the high prediction accuracy of the characteristic points. Besides, the average relative errors of the ωsub and outlet temperature (T[subscript c]) are 9.43% and 0.64%, respectively. The comparison results show that the proposed model outperforms the traditional models in structural characteristics and prediction accuracy under overall modes. Additionally, a formula of k₁-k₆ consists of two geometric variables (D[subscript nt] and D[subscript 3]) is derived, which is convenient to use in practice. Finally, the established ejector model is also integrated into AGRS, and its dynamic response is analyzed. The proposed model is helpful for the real-time control of the ejector-driven AGRS in fuel cell vehicles, and can provide guidance for the design and optimization of hydrogen ejectors.]]></description>
      <pubDate>Mon, 02 Feb 2026 09:31:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/2652720</guid>
    </item>
    <item>
      <title>Insights into the potential of EGR for reducing unregulated emissions and enhancing the performance of methanol-diesel RCCI engines at different altitudes</title>
      <link>https://trid.trb.org/View/2601734</link>
      <description><![CDATA[The unburned methanol and formaldehyde emission levels at low loads partly restrain methanol fuel application in diesel engines. Therefore, the potential of exhaust gas recirculation (EGR) for reducing unregulated emissions and enhancing the plateau adaptability of a methanol-diesel reactivity controlled compression ignition (RCCI) engine was investigated by changing the EGR ratio and altitude at different engine speed and load conditions. The results revealed that the altitude environment and EGR ratio exert notable impacts on the combustion behaviors and unregulated emissions of methanol-diesel RCCI engines. At A25 condition (25% engine load of 1400 rpm), the increase in EGR ratio and altitude reduces the excess air coefficient, improving the overly lean mixture quality in the cylinder and enhances combustion efficiency. At altitudes of 1000 and 2000 m, a concentrated heat release phenomenon is observed, with the peak heat release rate (HRR) increases as the EGR ratio increases, leading to improved thermal efficiency and fuel economy. Additionally, the combustion phase delay effect caused by changes in specific heat capacity due to increased EGR ratio is partially compensated by the combustion-promoting effect of the diesel-methanol mixture, resulting in little changes in the combustion phase with increasing EGR ratio under A25 condition. At B50 condition (50% engine load of 1800 rpm), the increase in EGR ratio continues to reduce the excess air coefficient. The cooling effect and increased specific heat capacity due to higher EGR ratio dominate, slowing down the combustion rate. A more noticeable combustion phase lag is observed under B50 condition. Regardless of the operating conditions, increases in EGR ratio and altitude effectively reduce unburned methanol emissions. Formaldehyde emissions are primarily related to exhaust temperature. At A25 condition, the lower exhaust temperature leads to a slight increase in formaldehyde emissions with increasing EGR ratio, while at B50 condition, formaldehyde emissions decrease with increasing EGR ratio. The rise in exhaust temperature due to increased altitude enhances the oxidation reaction of formaldehyde in the exhaust pipe, reducing formaldehyde emissions in both A25 and B50 conditions. Under A25 condition, at 1000 m with 40% EGR ratio, the brake thermal efficiency (BTE) is the highest, and fuel economy is optimal, the BTE is 35.95%, the equivalent specific fuel consumption (ESFC) is 235.65 g/(kW·h), the methanol emissions are 640.0 ppm, and formaldehyde emissions are 100.0 ppm. Under B50 condition, at 2000 m with 20% EGR ratio, the thermal efficiency is the highest, and fuel economy is optimal, the BTE is 38.09%, the ESFC is 222.40 g/(kW·h), the methanol emissions are 654.7 ppm, and formaldehyde emissions are 100.7 ppm.]]></description>
      <pubDate>Tue, 25 Nov 2025 15:02:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/2601734</guid>
    </item>
    <item>
      <title>Toward quantification of the information content in flow variables under cycle-to-cycle variations</title>
      <link>https://trid.trb.org/View/2601715</link>
      <description><![CDATA[Cycle-to-cycle variations (CCV) pose significant challenges to the performance and reliability of internal combustion engines (ICE). This study investigates the applicability of information entropy as a diagnostic tool to quantify and characterize CCV in ICE subject to exhaust gas recirculation (EGR). Particle image velocimetry (PIV) and flame imaging were used to measure the flow field and flame behavior. The concept of information entropy is related to flow and flame evolution by calculating the Shannon entropy of the turbulent kinetic energy and flow velocity components to assess their sensitivity to CCV. Shannon entropy was applied to the flow velocity components and the turbulent kinetic energy on the tumble plane, where the horizontal component was identified to correlate with high-speed (HC) and low-speed (LC) combustion cycles both, with and without EGR. The turbulent kinetic energy was found to be major driver of HC cycles without EGR, however, it plays a subordinate role with EGR. The conditional Shannon entropy was then applied to assess local fluctuation of the turbulent kinetic energy during ignition from cycle-to-cycle under the influence of the direction of the horizontal velocity component and the presence or absence of the flame, revealing the areas where turbulent kinetic energy fluctuates strongly between different cycles. The results have potential for both computational and experimental studies of ICE, since the use of information entropy as a diagnostic tool allows for early prediction of HC and LC cycles.]]></description>
      <pubDate>Mon, 24 Nov 2025 10:24:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2601715</guid>
    </item>
    <item>
      <title>Mixing-Controlled Combustion of Ethanol Enabled by Prechamber Ignition (PC-MCC): A Preliminary Experimental Demonstration</title>
      <link>https://trid.trb.org/View/2604480</link>
      <description><![CDATA[This experimental study presents preliminary investigations of prechamber-enabled mixing-controlled combustion (PC-MCC) at −2 bar brake mean effective pressure (BMEP) and 2200 rpm with fuel-grade ethanol (E98). Experimental results are conducted on a prechamber retrofitted single-cylinder Caterpillar C9.3B test engine. First, a series of prechamber-only experiments were conducted with a motored engine to evaluate the salient combustion trends in response to relevant prechamber operating parameters. Under firing conditions, the prechamber operating strategy was assessed with respect to the impact on ignition assistance of direct-injected E98 and overall engine performance. The preliminary results indicate the jet-induced ignition process is robust and prompts diffusion combustion of E98 at diesel-like boundary conditions. The effect of external exhaust gas recirculation (EGR) on the residual tolerance of the prechamber combustion process was also investigated and showed stable combustion in both the main chamber and prechamber up to 30% EGR. Experiments were also conducted with the stock diesel engine for baseline comparison. At matched combustion phasing, mixing-controlled combustion of ethanol enabled by prechamber ignition was able to achieve heightened gross thermal efficiency while simultaneously reducing NOₓ and practically eliminating smoke emissions relative to diesel combustion. In addition, the covariance of load and standard deviation of combustion phasing was diesel-like and less than 2% and 1 CAD, respectively.]]></description>
      <pubDate>Thu, 20 Nov 2025 17:07:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/2604480</guid>
    </item>
    <item>
      <title>A study on misfire control using crank angular velocity combustion feedback considering in-cylinder gas properties</title>
      <link>https://trid.trb.org/View/2578900</link>
      <description><![CDATA[Internal combustion engines have been strongly required to improve thermal efficiency and utilize a variety of fuels derived from renewable energy sources to achieve carbon neutrality. In terms of engine development, the stable control of ignition and combustion is the primary challenge in adapting to diverse fuels for the recently emphasized premixed compression ignition combustion and super lean burn. In this study, a misfire index was used as a detector for a premixed type of diesel combustion engine. Combustion feedback control was performed to control the target value of EGR based on the difference between the misfire index and its target value. To apply crank angle velocity to feedback control, this study implemented corrections and limitations to the misfire index based on in-cylinder gas properties. This was made possible because, during misfire events, the in-cylinder pressure at top dead center (TDC) is not influenced by combustion pressure. Additionally, this research enabled model validation of the phenomena for the first time. A novel structure was also established to learn the EGR correction amount from the deviation of the misfire index, marking the first empirical demonstration of its effectiveness. This research not only presents control examples for misfire countermeasures, which are crucial for the development of engines capable of utilizing diverse fuels but also contributed to mass production and practical application.]]></description>
      <pubDate>Fri, 26 Sep 2025 13:39:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/2578900</guid>
    </item>
    <item>
      <title>Modeling of the turbulent burning velocity considering the effect of fuel composition in EGR condition</title>
      <link>https://trid.trb.org/View/2586831</link>
      <description><![CDATA[To reduce CO₂ emissions, it is essential to enhance the thermal efficiency of internal combustion engines and utilize carbon-neutral fuels. Recent studies have shown that blending fuels with oxygenated components can extend the lean operating limit. This extension is partly attributed to the increased turbulent burning velocity, as indicated by the shorter combustion duration observed with such fuels. Similarly, an increase in turbulent burning velocity may also help expand the Exhaust Gas Recirculation (EGR) limit. Therefore, identifying fuel compositions that can expand the lean or EGR limits by increasing turbulent burning velocity is crucial. Given the ongoing research into various carbon-neutral fuel candidates, internal combustion engines must achieve high thermal efficiency with any fuel type. It is also important to quickly understand the requirements for achieving high thermal efficiency with different fuels. The purpose of this study is to clarify the effect of fuel composition on turbulent burning velocity under lean or EGR dilution conditions and to develop a model that accounts for these effects. The Markstein number, a dimensionless parameter indicating changes in burning velocity due to flame stretch, varies with fuel composition and is an important indicator under EGR conditions. Therefore, a modified model based on Peters’ model, which focuses on flame stretch and the Markstein number, was considered. To investigate the effect of fuel composition and verify the modified model, experiments were conducted using a Rapid Compression Machine (RCM) to measure the turbulent burning velocities of various fuels under EGR conditions. Ethanol-blended fuel and ETBE-blended fuel were used to clarify the impact of potential carbon-neutral fuel candidates on combustion and to assess the influence of the Markstein number. The comparison between the turbulent burning velocities obtained from the models and experiments confirmed that the modified model more accurately reproduced the experimental results than the base model. Using the modified model, the effect of fuel composition on turbulent burning velocity was further investigated. It was found that blending ethanol decreased the Lewis number, which in turn increased the turbulent burning velocity.]]></description>
      <pubDate>Fri, 26 Sep 2025 13:39:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2586831</guid>
    </item>
    <item>
      <title>LPV eBoost assisted pressure and EGR rate control of a diesel engine air charge system</title>
      <link>https://trid.trb.org/View/2586820</link>
      <description><![CDATA[Turbocharged engines often suffer from significant intake manifold pressure response delay due to so-called turbo-lag. Many technologies have been investigated to combat this phenomenon, and combinations of them are often utilized together. The addition of these technologies to already complicated modern engines presents a significant coordinated control challenge due to high system nonlinearity, especially with large operating ranges of engine speed and load. In this paper, a model-based gain-scheduling control strategy is developed, utilizing a constrained H₂ linear parameter-varying (LPV) control strategy, for the Ford 6.7L 8-cylinder diesel engine equipped with a variable geometry turbocharger (VGT), exhaust gas recirculation (EGR), and added eBoost along with a bypass valve. The nonlinear eBoost air charge system is described by an LPV model with two scheduling parameters, engine load and bypass valve position, for this study and LPV controllers are designed for the given operating range of these two parameters. Due to the computational limitation of the production-type control module, the LPV controller is implemented by interpolating LPV control gains solved offline at various grid points of the scheduling parameters to avoid matrix inverse calculation online. The LPV control strategy is validated in both simulation and experimental studies, indicating an up to 84% reduction in engine response time in terms of reaching target intake manifold (boost) pressure following a load step-up, compared with the production configuration (without eBoost and bypass valve) while maintaining the level of NOₓ emissions. The developed strategy is additionally compared to two previously developed control strategies: a dual-output proportional-integral-derivative (PID) strategy and a model-based linear quadratic tracking with integration (LQTI) strategy.]]></description>
      <pubDate>Fri, 26 Sep 2025 13:39:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2586820</guid>
    </item>
    <item>
      <title>The effect of embedded EGR pipe in diesel engine intake port on in-cylinder intake stratification</title>
      <link>https://trid.trb.org/View/2596684</link>
      <description><![CDATA[This study focuses on the design of an embedded Exhaust gas recirculation (EGR) pipe within the helical intake port of a diesel engine, adjusting the in-cylinder EGR stratification by changing the structural parameters of the EGR pipe, and examining its impact on engine combustion and emissions. The main focus is on the effect of EGR pipe angle B on in-cylinder EGR stratification. The degree of in-cylinder EGR gas stratification is used to evaluate the EGR stratification gradient and analyze the effects of different swirl ratios and EGR stratification on combustion. The study shows that introducing CO₂ through the EGR pipe can form an ideal radial stratification of rich outer and lean inner layers in the combustion chamber, with a maximum stratification degree of up to 13.2%. Comparative analysis of different swirl ratios and EGR gas introduction reveals that increasing the swirl ratio can significantly reduce soot emissions. Additionally, introducing 10% CO₂ through the embedded EGR pipe can significantly reduce NOx emissions.]]></description>
      <pubDate>Wed, 24 Sep 2025 15:31:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2596684</guid>
    </item>
    <item>
      <title>Assessing the influence of EGR on diesel pilot ignition combustion with methane/hydrogen blends in a single-cylinder compression ignition engine</title>
      <link>https://trid.trb.org/View/2566046</link>
      <description><![CDATA[This paper experimentally investigates the impact of EGR on the combustion performance and emissions of methane/hydrogen blends for the diesel pilot ignition (DPI) combustion strategy. Different speed/load cases were evaluated on a single-cylinder compression ignition engine for hydrogen energy shares ranging from 0% to 20%. As hydrogen was added to the premixed mixture, the combustion phasing (CA50) was held constant by either adjusting the pilot start of injection (SOI) timing or using EGR at constant intake pressure (varying premixed equivalence ratio). The experimental results show that the use of EGR at constant intake pressure with methane/hydrogen blends leads to lower unburned hydrocarbon (UHC), carbon-monoxide (CO), and nitric oxide (NO) emissions when compared to the methane-only baseline. Adiabatic flame temperature calculations were used to help explain the observed engine out nitric oxides (NOₓ) emissions trends. The UHC emissions, however, were significantly higher than the baseline split-injection diesel case due to incomplete combustion and crevice effects. Combustion efficiency improved without a thermal efficiency reduction with hydrogen addition, suggesting that substitution with hydrogen can be beneficial for dual-fuel compression ignition strategies that utilize natural gas. The decay rate for CH₄ and H₂ was more than linear, which is attributed to the chemical effects of hydrogen addition and EGR.]]></description>
      <pubDate>Tue, 26 Aug 2025 15:34:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/2566046</guid>
    </item>
    <item>
      <title>Experimental Evaluation of Purge Strategies in the Recirculation Path of a PEM Fuel Cell System</title>
      <link>https://trid.trb.org/View/2571727</link>
      <description><![CDATA[PEM fuel cell technology plays a vital role in realizing an emission-free mobility and, depending on the considered use case, offers significant advantages over battery electric solutions as well as hydrogen combustion engines. When high performance over a longer period of time as well as short refueling times are key requirements, fuel cell powertrains show their core strengths. However, the adaption of fuel cells in the mobility sector strongly depends on their efficiency which directly relates to the vehicle’s fuel consumption, range and ultimately cost to operate. Therefore, the influence on efficiency and power of different purge strategies used to operate PEM fuel cells is experimentally investigated and compared. A concentration-dependent purge strategy is developed and examined in reference to a charge-dependent strategy. The measurements are carried out on a fuel cell system test bench which corresponds to a fully functional fuel cell system including all commonly used peripheral components. In the range investigated, both purge strategies show similar values regarding the analyzed utilization coefficients and power. However, for the maximum fuel cell current examined, the concentration-dependent purge strategy achieved slightly higher utilization coefficients while showing a minimally lower power output. Taking this into account, further research regarding the optimization of concentration-dependent purge strategies appears promising. For the time being, the decision between using a charge-dependent or a concentration-dependent purge strategy foremost relies on the presence of a suitable hydrogen concentration sensor.]]></description>
      <pubDate>Mon, 21 Jul 2025 08:55:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/2571727</guid>
    </item>
    <item>
      <title>Combustion and Emissions Improvement of Engine Idling Via Advanced Ignition Strategies</title>
      <link>https://trid.trb.org/View/2539437</link>
      <description><![CDATA[During engine idling, the low engine speed, typically from 600 rpm to 800 rpm, together with the low throttle opening angle, makes it challenging for a proper fuel air mixing process. The uneven intake charge distribution and high portion of internal EGR because of the inefficient gas exchange process further make the air fuel ratio unstable, which is challenging for a robust ignition and combustion process. In this paper, the challenge of achieving proper combustion phasing while maintaining acceptable combustion stability is investigated, and a specially designed common-coil pack was utilized to improve engine idling performance by supplying prolonged ignition duration and elevated discharge current amplitude. The common-coil pack, which comprises three parallel connected ignition coils, was shared by all 4 cylinders of the engine. The ignition strategy shows the capability to advance the combustion phasing for higher IMEP output, while maintaining the combustion stability, and reduce engine out emissions.]]></description>
      <pubDate>Thu, 05 Jun 2025 11:59:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2539437</guid>
    </item>
    <item>
      <title>DME-to-Propane Mixture Effects on a Light Duty Compression Ignition Engine</title>
      <link>https://trid.trb.org/View/2539408</link>
      <description><![CDATA[Fuels that can be produced in a sustainable manner are of high interest because they can provide an essential step toward net zero emissions vehicles. This study examines the combustion of two such fuels, Dimethyl Ether (DME) and propane, in a compression ignition, 4-cylinder, 2.2L engine running with mixtures of DME-to-Propane ranging of 100%-0%, 85%-15%, 75%-25%, and 65%-35% by weight. Testing was conducted at 2000rpm - 100Nm, an important representative point in the FTP certification cycle. For each fuel mixture, conditions tested include sweeps of boost, EGR and injection pressure. Tests are mainly conducted at a constant combustion timing with CA10 of -1 deg with respect to TDC, with an engine controller combustion feedback system based on in-cylinder sampling of pressure. Trends of NOx, HC, and CO are similar for the range of DME-to-propane, from 100%-0% to 75%-25%. Boost and injection pressures had the most notable impact on the heat release traces. Higher boost, from stoichiometric to lean resulted in approximately a 3-5% increase on cycle efficiency. Fuel injection pressures resulted in about 1% gain per 200bar. Results also illustrated that EGR is effective in reducing NOx but causes notable degradation of cycle efficiency. The emissions for DME-propane mixtures with 65%-35% had a different trend, with CO and HC exceeding the runs with lower propane content by 2 to 3-fold. As propane content increases, the pressure rise rates become higher, and with 65%-35% mixtures, rates easily exceed 12bar/deg. The increased rise rates correlate with early injection timings but the rates can be reduced, with higher boost and lower injection pressures. The result of the approach, however, leads to lower thermal efficiencies, decreasing efficiency by over 5% between neat DME and the highest propane ratios.]]></description>
      <pubDate>Thu, 05 Jun 2025 11:59:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2539408</guid>
    </item>
    <item>
      <title>Fuel Composition Effects on Combustion Characteristics of a Low-Temperature Gasoline Combustion Engine</title>
      <link>https://trid.trb.org/View/2539406</link>
      <description><![CDATA[Low Temperature Gasoline Combustion (LTGC) in compression ignition engines is controlled by chemical kinetics and the autoignition reactivity of the fuel-air mixture, which are heavily influenced by the composition of the fuel. To investigate fuel-engine interactions, experiments were performed on a single-cylinder LTGC engine at various operating conditions with three premium-grade gasoline-like fuels with nominally the same octane rating but with high aromatic (HA), high cycloalkane (HCA) and high ethanol (E30 - 30%vol) contents, respectively. At fully-premixed naturally aspirated conditions, E30 showed the highest autoignition reactivity followed by HCA and HA. However, reactivity differences became less relevant when direct-injecting the fuel because of the vaporization cooling effect on the in-cylinder reactivity, which compensated for differences in fuel’s chemistry. Intake pressure sweeps demonstrated that the autoignition reactivity of E30 had the highest sensitivity to pressure, whereas HCA was the least sensitive likely due to the radical-scavenging activity of cyclo-pentane, a major component of HCA. Exhaust gas recirculation (EGR) addition was required to maintain stable engine operation at high intake pressures, with E30 requiring the highest EGR rate followed by HA and HCA. Only HA showed low temperature heat release at high intake pressures, and HA was also found to have the highest φ-sensitivity among all the fuels likely because of the stronger low temperature chemistry of this fuel. A combination of these two factors aided in extending stable engine operating limits for HA by maintaining engine stability at retarded combustion phasing. Interestingly, the optimum fuel composition changes depending on the engine operating conditions, with high ethanol content being desired at naturally aspirated conditions due to the lower intake heating requirement, high cyclo-alkane content being desired at high pressures due to the lower EGR requirement, and high aromatic content being desired at high loads due to the higher combustion stability and φ-sensitivity.]]></description>
      <pubDate>Thu, 05 Jun 2025 11:59:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2539406</guid>
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