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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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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <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>Compression Ratio and Intake Air Temperature Effect on the Fuel Flexibility of Compression Ignition Engine</title>
      <link>https://trid.trb.org/View/1653429</link>
      <description><![CDATA[The effect of compression ratio (CR) and intake air temperature on the combustion characteristics of fuels with different octane ratings were investigated on a single-cylinder heavy duty engine. The study focused on Primary Reference Fuels (PRFs) and commercial grade diesel with octane numbers ranging from 0 to 100. The engine was configured at a CR of 11.5:1, which is lower than typical heavy-duty compression ignition CI engines. This aims to compare the fuels’ burning regime with recently reported measurements at CR17:1. Experiments were performed at different intake air temperatures of 20 to 80 °C and net indicated mean effective pressure (IMEPNet) of 5 to 20 bar. The injection rates have been characterized to determine the hydraulic delay of the injector and thus define the actual ignition delay time. At low loads, diesel-like fuels were found to burn in partially premixed combustion (PPC) mode whereas high octane fuels did not ignite. At high loads, fuels combustion becomes diffusion driven regardless of their RON or MON values. The effect of intake air temperature on the combustion characteristics depended on the combination of the octane ratings and the engine load. At high loads, fuels with low octane numbers were insensitive to the change of the intake air temperature. The ignition delay time was short enough to maintain a diffusion driven combustion. At lower loads, it is more challenging to reach conditions where the combustion characteristics are invariant regardless of the fuel’s RON and MON values (Fuel Flexible). At the low tested compression ratio of 11.5:1, the extent of fuel flexibility is limited to only high loads (IMEPNet = 20 bar) whereas it is extended to intermediate loads (IMEPNet = 10 and 15 bar) at CR17:1.       ]]></description>
      <pubDate>Mon, 28 Oct 2019 10:30:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1653429</guid>
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    <item>
      <title>Combustion-Timing Control of Low-Temperature Gasoline Combustion (LTGC) Engines by Using Double Direct-Injections to Control Kinetic Rates</title>
      <link>https://trid.trb.org/View/1599033</link>
      <description><![CDATA[Low-temperature gasoline combustion (LTGC) engines can provide high efficiencies and extremely low NOx and particulate emissions, but controlling the combustion timing remains a challenge. This paper explores the potential of Partial Fuel Stratification (PFS) to provide fast control of CA50 in an LTGC engine. Two different compression ratios are used (CR=16:1 and 14:1) that provide high efficiencies and are compatible with mixed-mode SI-LTGC engines. The fuel used is a research grade E10 gasoline (RON 92, MON 85) representative of a regular-grade market gasoline found in the United States. The fuel was supplied with a gasoline-type direct injector (GDI) mounted centrally in the cylinder. To create the PFS, the GDI injector was pulsed twice each engine cycle. First, an injection early in the intake stroke delivered the majority of the fuel (70 - 80%), establishing the minimum equivalence ratio in the charge. Then, a second injection supplied the remainder of the fuel (20 - 30%) at a variable timing during the compression stroke, from 200° to 330°CA (0°CA = TDC-intake, 360°CA = TDC-compression) to provide controlled stratification. For both CRs, second DI timing sweeps were performed for a range of intake pressures from highly boosted to naturally aspirated conditions, allowing the CA50 control authority at each condition to be determined. By varying the late-DI timing, CA50 could be adjusted as much a 12°CA, from near the misfire limit (overly retarded CA50 with COV-IMEPg > 3%) to well beyond the acceptable knock/ringing limit (overly advanced CA50 with RI > 5 MW/m2). For different conditions, the amount of DI timing retard and CA50 advancement was limited by either engine knock, combustion instabilities, or high NOx emissions (NOx > 0.27 g/kWh). For most conditions, approximately 6-8°CA of CA50 control was possible with good stability and acceptable NOx emissions.       ]]></description>
      <pubDate>Thu, 19 Sep 2019 15:11:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/1599033</guid>
    </item>
    <item>
      <title>Using Chemical Kinetics to Understand Effects of Fuel Type and Compression Ratio on Knock-Mitigation Effectiveness of Various EGR Constituents</title>
      <link>https://trid.trb.org/View/1599017</link>
      <description><![CDATA[Exhaust gas recirculation (EGR) can be used to mitigate knock in SI engines. However, experiments have shown that the effectiveness of various EGR constituents to suppress knock varies with fuel type and compression ratio (CR). To understand some of the underlying mechanisms by which fuel composition, octane sensitivity (S), and CR affect the knock-mitigation effectiveness of EGR constituents, the current paper presents results from a chemical-kinetics modeling study. The numerical study was conducted with CHEMKIN, imposing experimentally acquired pressure traces on a closed reactor model. Simulated conditions include combinations of three RON-98 (Research Octane Number) fuels with two octane sensitivities and distinctive compositions, three EGR diluents, and two CRs (12:1 and 10:1). The experimental results point to the important role of thermal stratification in the end-gas to smooth peak heat-release rate (HRR) and prevent acoustic noise. To model the effects of thermal stratification due to heat-transfer losses to the combustion-chamber walls, the initial temperature at the start of the CHEMKIN simulation was successively reduced below the adiabatic core temperature while observing changes in end-gas heat release and its effect on the reactant temperature.The results reveal that knock-prone conditions generally exhibit an increased amount of heat release in the colder temperature zones, thus counteracting the HRR-smoothing effect of the naturally occurring thermal stratification. This detrimental effect becomes more pronounced for the low-S fuel due to its significant Negative Temperature Coefficient (NTC) autoignition characteristics. This explains the generally reduced effectiveness of dilution for the low-S fuel, and higher knock intensity for the cycles with autoignition.]]></description>
      <pubDate>Wed, 18 Sep 2019 17:16:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1599017</guid>
    </item>
    <item>
      <title>HCCI Octane Number Scale in a Pressure-Temperature Diagram</title>
      <link>https://trid.trb.org/View/1598862</link>
      <description><![CDATA[A new approach for investigating combustion behavior of practical fuels under homogeneous charge compression ignition (HCCI) conditions was developed with the help of a cooperative fuel research (CFR) engine. The method uses a set of two pressure-temperature diagrams and two charts, each with an octane number scale based on primary reference fuels (PRF), created from experimental results by sweeping the intake temperature. The two pressure-temperature diagrams report conditions leading to the start of the low temperature combustion and the start of the main combustion, respectively. Additional two charts -- required compression ratio and fraction of low temperature heat release charts -- describe global combustion behavior and the importance of the low temperature combustion. Each diagram and chart, together with their respective octane number scale, allow to examine the combustion behavior of practical fuels by comparing their combustion behavior with those of the PRFs. Finally, octane numbers representing the various combustion behaviors of a practical fuel can be rated. Application of the method with two low-octane number surrogate fuels led to the following main results. The required compression ratio chart provides a quick description of the combustion behavior. The pressure-temperature diagrams indicate the ease with which a fuel ignites under low temperature combustion and main combustion regimes. An extra pressure-temperature diagram reports start and end of the negative temperature coefficient regime and highlights that this regime is independent of the fuel. Accordingly, each combustion regime is clearly defined in the pressure-temperature diagram. The fraction of low temperature heat release finally indicates how low temperature combustion vanishes. Finally, octane numbers for each practical fuel were rated from each diagram and chart. Rated octane numbers suggest that a single PRF cannot reflect the entire combustion behavior of a practical fuel; but multiple PRFs are required for HCCI combustion.       ]]></description>
      <pubDate>Tue, 03 Sep 2019 09:12:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/1598862</guid>
    </item>
    <item>
      <title>Effects of Compression Ratio and Water Vapor Induction on the Achievable Load Limits of a Light Duty Diesel Engine Operated in HCCI Mode</title>
      <link>https://trid.trb.org/View/1598859</link>
      <description><![CDATA[Among the various Low Temperature Combustion (LTC) strategies, Homogeneous Charge Compression Ignition (HCCI) is most promising to achieve near zero oxides of nitrogen (NOx) and particulate matter emissions owing to higher degree of homogeneity and elimination of diffusion phase combustion. However, one of its major limitations include a very narrow operating load range owing to misfire at low loads and knocking at high loads. Implementing HCCI in small light duty air cooled diesel engines pose challenges to eliminate misfire and knocking problems owing to lower power output and air cooled operation, respectively. In the present work, experimental investigations are done in HCCI mode in one such light duty production diesel engine most widely used in agricultural water pumping applications. An external mixture preparation based diesel HCCI is implemented in the test engine by utilizing a high-pressure port fuel injection system, a fuel vaporizer and an air preheater. With an existing compression ratio of 17.5, the engine could not be operated beyond 20% of rated BMEP owing to severe knocking. The existing bowl shaped piston is modified into a flat piston which is justified by the fact that fuel-air mixing has minimal or negligible role in HCCI combustion. In order to examine the effects of compression ratio on the achievable load range in HCCI, the geometric compression ratio is reduced in incremental steps from 17.5 to 11.5 with an interval of 2.5 by reducing the piston crown thickness. However, the compression ratio could not be reduced below 11.5 with the existing piston design. The results obtained show that the load range could be extended up to 57% by reducing the compression ratio to 11.5 without utilizing exhaust gas recirculation. It is also intended to examine the effects of water vapor induction on the achievable load range in HCCI. For this purpose, 20 ultrasonic atomizers with 1.7 MHz vibration frequency are utilized to produce water vapor which is inducted along with diesel vapor and air during the engine suction stroke. The homogeneous mixture of diesel vapor, water vapor and air is ignited during the engine compression stroke at a fixed compression ratio of 15. The water vapor concentration is varied from 0.8 mg/cycle to 2.4 mg/cycle by using a control valve. The results obtained shows that the load range could be extended up to 50% in HCCI by utilizing water vapor induction. At a fixed load condition, water vapor induction reduces NOx and smoke emissions, while unburned emissions are higher compared to the results obtained with reducing compression ratio because of lower temperatures and displacement of intake oxygen. Overall, the present work shows that either by reducing the geometric compression ratio or by utilizing water vapor induction, there is a greater potential to increase the load range of diesel HCCI engines.       ]]></description>
      <pubDate>Fri, 30 Aug 2019 13:02:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1598859</guid>
    </item>
    <item>
      <title>A Path towards High Efficiency Using Argon in an HCCI Engine</title>
      <link>https://trid.trb.org/View/1598849</link>
      <description><![CDATA[Argon replacing Nitrogen has been examined as a novel engine cycle reaching higher efficiency. Experiments were carried out under Homogeneous Charge Compression Ignition (HCCI) conditions using a single cylinder variable compression ratio Cooperative Fuel Research (CFR) engine. Isooctane has been used as the fuel for this study. All the parameters were kept fixed but the compression ratio to make the combustion phasing constant. Typical engine outputs and emissions were compared to conventional cycles with both air and synthetic air. It has been found that the compression ratio of the engine must be significantly reduced while using Argon due to its higher specific heat ratio. The resulting in-cylinder pressure was lower but combustion remains aggressive. However, greater in-cylinder temperatures were reached. To an end, Argon allows gains in fuel efficiency, in unburned hydrocarbon and carbon monoxide, as well as in indicated efficiency.       ]]></description>
      <pubDate>Wed, 28 Aug 2019 17:17:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/1598849</guid>
    </item>
    <item>
      <title>Effects of Single versus Two-Stage Heat Release on the Load Limits of HCCI Using Primary Reference Fuels</title>
      <link>https://trid.trb.org/View/1598848</link>
      <description><![CDATA[Homogeneous Charge Compression Ignition (HCCI) enables combustion with high efficiency and low emissions. Control over the combustion process and its narrow operating range are still the biggest challenges associated with HCCI. To expand the operable load ranges of HCCI, this paper explores the effects of single versus two-stage ignition fuels by studying the Primary Reference Fuels (PRF) in a variable compression ratio Cooperative Fuel Research (CFR) engine. The PRF fuels, iso-octane and n-heptane, are blended together at various concentrations to create fuel blends with different autoignition characteristics. Experiments were conducted using these PRF blends to explore the extent to which the load range can be extended with two-stage ignition fuels at various compression ratios and intake temperatures. The reactivity of the PRF blends increases with the fraction of n-heptane and so does the amount of low temperature heat release (LTHR).         Since the low PRF number fuels have a higher reactivity, they can be autoignited at very low compression ratios while maintaining comparable combustion phasing and equivalence ratios. At the lower compression ratios, the low load limits were found to be extended while maintaining high combustion efficiencies. Additionally, lower peak pressures and pressure rise rates were achieved at low PRF number fuels as a result of its two-stage heat release, which can be used to reach higher loads. In addition, the energy released from the LTHR can be used to delay the CA50 combustion phasing (i.e., the crank angle timing where 50% of the energy has been released) beyond what is possible with a single-stage ignition fuel, which allows further high load extension. However, using lower compression ratios has a negative impact on the thermal efficiency. The effects of the extended load, single- and two-stage heat release, combustion phasing, and equivalence ratios on combustion efficiency, thermal efficiencies, and combustion durations were also explored.       ]]></description>
      <pubDate>Wed, 28 Aug 2019 17:17:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/1598848</guid>
    </item>
    <item>
      <title>Evaluating the reactivity controlled compression ignition operating range limits in a high-compression ratio medium-duty diesel engine fueled with biodiesel and ethanol</title>
      <link>https://trid.trb.org/View/1625484</link>
      <description><![CDATA[This work investigates the load limits of reactivity controlled compression ignition combustion, a dual-fuel concept which combines port fuel injection of low-reactivity fuels with direct injection of diesel fuel, in a medium-duty diesel engine. The experiments were conducted in a single-cylinder diesel engine derived from the multi-cylinder production engine. In this sense, the stock turbocharger and exhaust gas recirculation systems were replaced by an external compressor and dedicated low-pressure exhaust gas recirculation loop, respectively. Additionally, a port fuel injector was installed in the intake manifold to allow gasoline injection. First, this article presents some results highlighting the effect of the exhaust gas recirculation rate, gasoline fraction, diesel start of injection, diesel injection strategy and intake temperature on the emissions, performance and combustion development in a representative operating condition: 1200?r/min and 6.5?bar indicated mean effective pressure (25% load). Later, with the aim of showing the reactivity controlled compression ignition potential, the best results in terms of performance and emissions at 25% load are compared against the multi-cylinder diesel engine from 950 to 2200?r/min. Reactivity controlled compression ignition engine tests were developed taking into account limitations in nitrogen oxides (NOx) and soot emissions, in-cylinder pressure and maximum pressure rise rate. Finally, keeping the same constraints for testing, the load limits of reactivity controlled compression ignition concept are evaluated for all the engine speeds. Results suggest that reactivity controlled compression ignition allows fulfilling EURO VI limits for NOx and soot emissions without using selective catalytic reduction and diesel particulate filter aftertreatment systems at 25% load at all the engines speeds, providing better indicated efficiency than conventional diesel operation in most operating points. In addition, the maximum engine load that ensured the aforementioned constraints was around 35% for all the engine speeds, with a maximum indicated mean effective pressure of 8.8?bar at 2200?r/min. In this case, a strong reduction in carbon monoxide (CO) and unburned hydrocarbon (HC) emissions compared to the cases of 25% load was achieved at all the engine speeds.]]></description>
      <pubDate>Fri, 16 Aug 2019 15:51:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1625484</guid>
    </item>
    <item>
      <title>Quantification of knock benefits from reformate and cooled exhaust gas recirculation using a Livengood–Wu approach with detailed chemical kinetics</title>
      <link>https://trid.trb.org/View/1625426</link>
      <description><![CDATA[In this work, a simple methodology was implemented to predict the onset of knock in spark-ignition engines and quantify the benefits of two practical knock mitigation strategies: cooled exhaust gas recirculation and syngas blending. Based on the results of this study, both cooled exhaust gas recirculation and the presence of syngas constituents in the end-gas substantially improved the knock-limited compression ratio of the engine. At constant load, 25% exhaust gas recirculation increased the knock-limited compression ratio from 9.0 to 10.8:1 (0.07 compression ratio per 1% exhaust gas recirculation) due to lower end-gas temperature and reactant (fuel and oxygen) concentrations. At exhaust gas recirculation rates above 43%, higher intake temperature outweighed the benefits of lower end-gas reactant concentration. At constant intake temperature, cooled exhaust gas recirculation was significantly more effective at all exhaust gas recirculation rates (0.10 compression ratio per 1% exhaust gas recirculation), and no diminishing returns or optimum was observed. Both hydrogen and carbon monoxide were also predicted to improve knock by reducing end-gas reactivity, likely through the conversion of high-reactivity hydroxy-radicals to less reactive peroxy-radicals. Hydrogen increased the knock-limited compression ratio by 1.1 per volume percent added at constant energy content. Carbon monoxide was less effective, increasing the knock-limited compression ratio by 0.38 per volume percent added. Combining 25% cooled exhaust gas recirculation with reformate produced from rich combustion at an equivalence ratio of 1.3 resulted in a predicted increase in the knock-limited compression ratio of 3.5, which agreed well with the published experimental engine data. The results show the extent to which syngas blending and cooled exhaust gas recirculation each contribute separately to knock mitigation and demonstrate that both can be effective knock mitigation strategies. Together, these solutions have the potential to increase the compression ratio and efficiency of spark-ignition engines.]]></description>
      <pubDate>Wed, 24 Jul 2019 14:39:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/1625426</guid>
    </item>
    <item>
      <title>Maximum efficiencies for internal combustion engines: Thermodynamic limitations</title>
      <link>https://trid.trb.org/View/1625384</link>
      <description><![CDATA[The thermodynamic limitation for the maximum efficiencies of internal combustion engines is an important consideration for the design and development of future engines. Knowing these limits helps direct resources to those areas with the most potential for improvements. Using an engine cycle simulation which includes the first and second laws of thermodynamics, this study has determined the fundamental thermodynamics that are responsible for these limits. This work has considered an automotive engine and has quantified the maximum efficiencies starting with the most ideal conditions. These ideal conditions included no heat losses, no mechanical friction, lean operation, and short burn durations. Then, each of these idealizations is removed in a step-by-step fashion until a configuration that represents current engines is obtained. During this process, a systematic thermodynamic evaluation was completed to determine the fundamental reasons for the limitations of the maximum efficiencies. For the most ideal assumptions, for compression ratios of 20 and 30, the thermal efficiencies were 62.5% and 66.9%, respectively. These limits are largely a result of the combustion irreversibilities. As each of the idealizations is relaxed, the thermal efficiencies continue to decrease. High compression ratios are identified as an important aspect for high-efficiency engines. Cylinder heat transfer was found to be one of the largest impediments to high efficiency. Reducing cylinder heat transfer, however, is difficult and may not result in much direct increases of piston work due to decreases of the ratio of specific heats. Throughout this work, the importance of high values of the ratio of specific heats was identified as important for achieving high thermal efficiencies. Depending on the selection of constraints, different values may be given for the maximum thermal efficiency. These constraints include the allowed values for compression ratio, heat transfer, friction, stoichiometry, cylinder pressure, and pressure rise rate.]]></description>
      <pubDate>Mon, 22 Jul 2019 20:01:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1625384</guid>
    </item>
    <item>
      <title>Effect of Hot EGR on Ignition, Combustion Characteristics and Thermal Efficiency of Alcohol Fuels in a Small DI Engine with High Compression Ratio</title>
      <link>https://trid.trb.org/View/1623154</link>
      <description><![CDATA[This study deals with the development of controlled-ignition technology for high performance compression ignition alcohol engine. The objective of this study is to make clear the effect of hot EGR on ignition, combustion characteristics and thermal efficiency of alcohol fuels in a small DI diesel engine with high compression ratio. Ignition and combustion characteristics of four kinds of alcohol fuels (Ethanol, Propanol, Butanol and Pentanol) were experimentally investigated. Experiments were carried out within the range of 1200 rpm to 1600 rpm in engine operating speed with changing hot EGR ratio under high compression ratio (ε=23).]]></description>
      <pubDate>Mon, 22 Jul 2019 20:01:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/1623154</guid>
    </item>
    <item>
      <title>Numerical study of knock occurrence in an internal combustion engine using VVT strategy and different compression ratios</title>
      <link>https://trid.trb.org/View/1595212</link>
      <description><![CDATA[The adoption of high compression ratios when designing an internal combustion engine is often used to improve thermal efficiency. However, compression ratio cannot be enhanced indefinitely since elevated pressures and temperatures inside the combustion chamber may cause knock. In view of this issue, it is important to have an accurate knowledge about the conditions in which the probability of knock occurrence is high to preserve engine integrity and achieve the best performance. In addition, if numerical tools are available for this type of analysis, time and experimentation costs can be avoided. Based on this idea, this paper presents a numerical tridimensional study of knock occurrence in a spark ignition three-cylinder engine operating with different compression ratios and late intake valve closing. By means of this analysis, it was possible to represent the knock phenomenon and evaluate its main causes, as well as investigate flow patterns, mixture formation, and combustion process, besides the effect of spark advance on knock occurrence.       ]]></description>
      <pubDate>Wed, 10 Jul 2019 15:17:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/1595212</guid>
    </item>
    <item>
      <title>Effect of compression ratio, nozzle opening pressure, engine load, and butanol addition on nanoparticle emissions from a non-road diesel engine</title>
      <link>https://trid.trb.org/View/1605837</link>
      <description><![CDATA[Currently, diesel engines are more preferred over gasoline engines due to their higher torque output and fuel economy. However, diesel engines confront major challenge of meeting the future stringent emission norms (especially soot particle emissions) while maintaining the same fuel economy. In this study, nanosize range soot particle emission characteristics of a stationary (non-road) diesel engine have been experimentally investigated. Experiments are conducted at a constant speed of 1500 rpm for three compression ratios and nozzle opening pressures at different engine loads. In-cylinder pressure history for 2000 consecutive engine cycles is recorded and averaged data is used for analysis of combustion characteristics. An electrical mobility-based fast particle sizer is used for analyzing particle size and mass distributions of engine exhaust particles at different test conditions. Soot particle distribution from 5 to 1000 nm was recorded. Results show that total particle concentration decreases with an increase in engine operating loads. Moreover, the addition of butanol in the diesel fuel leads to the reduction in soot particle concentration. Regression analysis was also conducted to derive a correlation between combustion parameters and particle number emissions for different compression ratios. Regression analysis shows a strong correlation between cylinder pressure-based combustion parameters and particle number emission.]]></description>
      <pubDate>Thu, 27 Jun 2019 14:54:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/1605837</guid>
    </item>
    <item>
      <title>Effect of diesel-methanol-nitromethane blends combustion on VCR stationary CI engine performance and exhaust emissions</title>
      <link>https://trid.trb.org/View/1604586</link>
      <description><![CDATA[The continuous rise in cost of fossil fuels and environmental pollution has attracted research in the area of clean alternative fuels for improving the performance and emission of internal combustion engines. In the present work, methanol and nitromethane were treated as a biofuel and investigations have been made to evaluate the feasibility of replacing diesel with a suitable diesel-methanol-nitromethane blend. For this, experimental investigations were carried out on a VCR diesel engine using diesel-methanol-nitromethane blends to determine the most favorable blending ratio and engine operating parameters for enhancing performance and reduce emissions. The best results of performance and emissions were observed with D-M5-NM2.5 blend (diesel 92.5%, methanol 5%, nitromethane 2.5%) at standard engine parameters. The improvement in engine performance (13% increment in BTE and 19.5% decrement in BSFC) and reduction in emission (smoke 26.47%, NOₓ 21.66%, and CO 14.28%) was found using D-M5-NM2.5 blend as compared to pure diesel at full load condition; however, HC emission was slightly increased by 10.71%. To find out the best suitable value of CR for D-M5-NM2.5 blend, experiments were further performed on different compression ratios by which higher compression ratio of 19.5 was found better under similar operating conditions. By increasing CR from 18.5 (standard) to 19.5, improvement in engine performance (BTE increased 3.8% and BSFC decreased 3.4%) and reduction in emission (smoke 10%, CO 16.67%, and HC 61.29%) were observed using D-M5-NM2.5 blend; however, NOₓ was found to be on slightly higher side with tolerable increment of 6.38%.]]></description>
      <pubDate>Thu, 27 Jun 2019 14:53:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1604586</guid>
    </item>
    <item>
      <title>Study on transient emission spikes reduction of a heavy-duty diesel engine equipped with a variable intake valve closing timing mechanism and a two-stage turbocharger</title>
      <link>https://trid.trb.org/View/1606567</link>
      <description><![CDATA[The overall performance and emission during a speed/torque versus time transient cycle are investigated in a heavy-duty truck engine equipped with an intake valve closing timing mechanism and a two-stage turbocharger system (high-pressure turbine is variable geometry turbine). The performance discrepancy analysis between steady-state and transient operation is completed based on a fairly optimized steady-state baseline. The result shows that during the transient operation, the transient NOₓ emission can track the steady-state baselines much better than particle matter, and the cumulative NOₓ in transients is even lower than the cumulative NOₓ of the steady-state baselines, while the rising particle matter emissions mainly due to appearance in particle matter emission spikes during the cycle. And the transient particle matter spikes appeared almost in two typical transient conditions: sharp acceleration from idling and abrupt load transients. The instantaneous equivalence ratio (Φ) is found to be the main physical factor governing particle matter spikes formation in transients. Particle matter spikes become prominent when Φ cannot track the steady-state baseline well or Φ rises over a critical value of 0.8. The control strategy of intake valve closing timing mechanism-variable geometry turbine-exhaust gas recirculation to bridge the gap of Φ between the steady-state and the transients has been established, which effectively cut down the emission spikes, reducing particle matter emissions by 32.9% with almost no change in NOₓ.]]></description>
      <pubDate>Thu, 27 Jun 2019 14:53:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1606567</guid>
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