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Статті в журналах з теми "EGR dilution"
1
Wang, Li, Zhaoming Huang, Wang Tao, Kai Shen, and Weiguo Chen. "Economy and emission characteristics of the optimal dilution strategy in lean combustion based on GDI gasoline engine equipped with prechamber." Advances in Mechanical Engineering 13, no. 12 (December 2021): 168781402110381. http://dx.doi.org/10.1177/16878140211038100.
Повний текст джерелаАнотація:
EGR and excess-air dilution have been investigated in a 1.5 L four cylinders gasoline direct injection (GDI) turbocharged engine equipped with prechamber. The influences of the two different dilution technologies on the engine performance are explored. The results show that at 2400 rpm and 12 bar, EGR dilution can adopt more aggressive ignition advanced angle to achieve optimal combustion phasing. However, excess-air dilution has greater fuel economy than that of EGR dilution owing to larger in-cylinder polytropic exponent. As for prechamber, when dilution ratio is greater than 37.1%, the combustion phase is advanced, resulting in fuel economy improving. Meanwhile, only when the dilution ratio is under 36.2%, the HC emissions of excess-air dilution are lower than the original engine. With the increase of dilution ratio, the CO emissions decrease continuously. The NOX emissions of both dilution technologies are 11% of those of the original engine. Excess-air dilution has better fuel economy and very low CO emissions. EGR dilution can effectively reduce NOX emissions, but increase HC emissions. Compared with spark plug ignition, the pre chamber ignition has lower HC, CO emissions, and higher NO emissions. At part load, the pre-chamber ignition reduces NOX emissions to 49 ppm.
2
Sarangi, Asish K., Gordon P. McTaggart-Cowan, and Colin P. Garner. "The Impact of Fuel Injection Timing and Charge Dilution Rate on Low Temperature Combustion in a Compression Ignition Engine." Energies 16, no. 1 (December 23, 2022): 139. http://dx.doi.org/10.3390/en16010139.
Повний текст джерелаАнотація:
Using high charge dilution low temperature combustion (LTC) strategies in a diesel engine offers low emissions of nitrogen oxides (NOx). These strategies are limited to part-load conditions and involve high levels of charge dilution, typically achieved through the use of recirculated exhaust gases (EGR). The slow response of the gas handling system, compared to load demand and fuelling, can lead to conditions where dilution levels are higher or lower than expected, impacting emissions and combustion stability. This article reports on the sensitivity of high-dilution LTC to variations in EGR rate and fuel injection timing. Impacts on engine efficiency, combustion stability and emissions are assessed in a single-cylinder engine and compared to in-cylinder flame temperatures measured using a borescope-based two-colour pyrometer. The work focuses on low-load conditions (300 kPa gross indicated mean effective pressure) and includes an EGR sweep from conventional diesel mode to high-dilution LTC, and sensitivity studies investigating the effects of variations in charge dilution and fuel injection timing at the high-dilution LTC condition. Key findings from the study include that the peak flame temperature decreased from ~2580 K in conventional diesel combustion with no EGR to 1800 K in LTC with low-NOx, low-soot operation and an EGR rate of 57%. Increasing the EGR to 64% reduced flame temperatures to 1400 K but increased total hydrocarbon (THC) and carbon monoxide (CO) emissions by 30–50% and increased fuel consumption by 5–7%. Charge dilution was found to have a stronger effect on the combustion process than the diesel injection timing under these LTC conditions. Advancing fuel injection timings at increasing dilution kept combustion instability below 2.5%. Peak in-cylinder temperatures were maintained in the 2000–2100 K range, while THC and CO emissions were controlled by delaying the onset of bulk quenching. Very early injection (earlier than 24 °CA before top-dead-centre) resulted in spray impingement on the piston crown, resulting in degraded efficiency and higher emissions. The results of this study demonstrate the potential of fuel injection timing modification to accommodate variations in charge dilution rates while maintaining low NOx and PM emissions in a diesel engine using low-temperature combustion strategies at part loads.
3
Silva, M. F., P. T. Lacava, A. Penaranda, M. E. Sbampato, and L. R. L. R. Santos. "EXPERIMENTAL STUDY WITH DIFFERENT STRATEGIES AND AIR-DILUTION USING OPTICAL SI ENGINE FUELED WITH HYDRATED ETHANOL." Revista de Engenharia Térmica 21, no. 3 (February 8, 2023): 01. http://dx.doi.org/10.5380/reterm.v21i3.89663.
Повний текст джерелаАнотація:
Several dilution conditions techniques are used in internal combustion engines to increase fuel economy and reduce pollutant emissions, primarily nitrogen oxide (NOX), which are generated by the thermal pathway. Among the techniques, we can highlight air dilution (lean combustion) and exhaust gas recirculation (EGR). The control of these operations using different types of fuels and biofuels and their peculiarities, are of fundamental importance to remove the maximum efficiency from the process, generating the lowest level of emission and respecting the current legislation. Although several studies have achieved interesting results for reducing emissions and knocks thanks to the dilution of the air, it has been observed that the diluent without oxygen is more efficient. Although air dilution has a slightly lesser effect than EGR, this mode of operation can help to understand the dynamics of engine load dilution, mainly due to the complexity of EGR tests on research engines. Therefore, as a background, tests were carried out experimentally with air dilution in order to understand the behavior for the prediction of future tests with EGR. The tests were performed with hydrated ethanol and speeds of 1500 rpm and 2500 rpm. It was possible to observe that with increasing dilution, there is a gradual increase in the variability of the burn and its displacement to the region close to the inlet valve. It was observed that the dilution provided a decrease in the formation of NOX and CO and an increase in hydrocarbon emissions. Increased rotation due to increased turbulence causes changes in emission values.
4
Atkins, M. J., and C. R. Koch. "The effect of fuel octane and dilutent on homogeneous charge compression ignition combustion." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 219, no. 5 (May 1, 2005): 665–75. http://dx.doi.org/10.1243/095440705x11202.
Повний текст джерелаАнотація:
This paper presents some experimental operating and combustion properties of homogeneous charge compression ignition (HCCI) combustion. HCCI operating range, start of combustion, burn duration, indicated mean effective pressure, indicated specific emissions, and indicated specific fuel consumption are evaluated as charge dilution and octane number are varied. Primary reference fuels with octane numbers of 20, 40, and 60 are used in this study. The autoignition properties of the air-fuel mixture are varied by changing the fuel octane number, percentage of exhaust gas recirculation (EGR), and air-fuel ratio, while holding the intake temperature, engine speed, and compression ratio constant. Results show that both the start of combustion and the burn duration are sensitive to mixture dilution (excess air or EGR). The fuel octane number is not an effective method of controlling the start of combustion or the burn duration but can be used to increase the load range of the HCCI engine. Both the NO x emissions and the indicated specific fuel consumption increase as the octane number is increased due to lower dilution and higher peak temperatures. Correct amounts of dilution are critical in controlling HCCI combustion. Separating dilution into EGR and excess air, it is found that a given amount of EGR is more effective at controlling the start of combustion and the burn duration than the same amount of excess air.
5
Pamminger, Michael, Buyu Wang, Carrie M. Hall, Ryan Vojtech, and Thomas Wallner. "The impact of water injection and exhaust gas recirculation on combustion and emissions in a heavy-duty compression ignition engine operated on diesel and gasoline." International Journal of Engine Research 21, no. 8 (January 8, 2019): 1555–73. http://dx.doi.org/10.1177/1468087418815290.
Повний текст джерелаАнотація:
Steady-state experiments were conducted on a 12.4L, six-cylinder heavy-duty engine to investigate the influence of port-injected water and dilution via exhaust gas recirculation (EGR) on combustion and emissions for diesel and gasoline operation. Adding a diluent to the combustion process reduces peak combustion temperatures and can reduce the reactivity of the charge, thereby increasing the ignition-delay and, allowing for more time to premix air and fuel. Experiments spanned water/fuel mass ratios up to 140mass% and exhaust gas recirculation ratios up to 20vol% for gasoline and diesel operation with different injection strategies. Diluting the combustion process with either water or EGR resulted in a significant reduction in nitrogen oxide emissions along with a reduction in brake thermal efficiency. The sensitivity of brake thermal efficiency to water and EGR varied among the fuels and injection strategies investigated. An efficiency breakdown revealed that water injection considerably reduced the wall heat transfer; however, a substantial increase in exhaust enthalpy offset the reduction in wall heat transfer and led to a reduction in brake thermal efficiency. Regular diesel operation with main and post injection exhibited a brake thermal efficiency of 45.8% and a 0.3% reduction at a water/fuel ratio of 120%. The engine operation with gasoline, early pilot, and main injection strategy showed a brake thermal efficiency of 45.0% at 0% water/fuel ratio, and a 1.2% decrease in brake thermal efficiency for a water/fuel ratio of 140%. Using EGR as a diluent reduced the brake thermal efficiency by 0.3% for diesel operation, comparing ratios of 0% and 20% EGR. However, a higher impact on brake thermal efficiency was seen for gasoline operation with early pilot and main injection strategy, with a reduction of about 0.8% comparing 0% and 20% EGR. Dilution by means of EGR exhibited a reduction in nitrogen oxide emissions up to 15 g/kWh; water injection showed only up to 10 g/kWh reduction for the EGR rates and water/fuel ratio investigated.
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Alger, Terrence, Raphael Gukelberger, and Jess Gingrich. "Impact of EGR Quality on the Total Inert Dilution Ratio." SAE International Journal of Engines 9, no. 2 (April 5, 2016): 796–806. http://dx.doi.org/10.4271/2016-01-0713.
Повний текст джерела
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Zhang, Zheng, and David M. Cohen. "Hypotonicity increases transcription, expression, and action ofEgr-1in murine renal medullary mIMCD3 cells." American Journal of Physiology-Renal Physiology 273, no. 5 (November 1, 1997): F837—F842. http://dx.doi.org/10.1152/ajprenal.1997.273.5.f837.
Повний текст джерелаАнотація:
In cells of the murine renal inner medullary collecting duct (mIMCD3) cell line, acute hypotonic shock (50% dilution of medium with sterile water but not with sterile 150 mM NaCl) increased Egr-1 mRNA abundance 2.5-fold at 6 h, as determined by Northern analysis. This increase was accompanied by increased Egr-1 transcription, as quantitated by luciferase reporter gene assay. Increased transcription was dose dependent, additive with other Egr-1 transcriptional activators, and occurred in the absence of overt cytotoxicy, as quantitated via a fluorometric viability assay. In addition, hypotonic stress increased Egr-1 protein abundance, which was accompanied by augmented Egr-1-specific DNA binding ability, as measured via electrophoretic mobility shift assay. Increased DNA binding was further associated with increased transactivation by Egr-1, demonstrated through transient transfection of mIMCD3 cells with a luciferase reporter gene driven by tandem repeats of the Egr-1 DNA consensus sequence. Taken together, these data indicate that hypotonic stress activates Egr-1 transcription, translation, DNA binding, and transactivation in renal medullary cells. This phenomenon might play a role in the acquisition of the adaptive phenotype in response to hypotonic stress in cells of the renal medulla in vivo.
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Zhao, Y., Z. Wang, G. J. Xu, and M. D. Li. "Impact of EGR on the surface functional groups of diesel engine particles based on NEXAFS." RSC Advances 6, no. 62 (2016): 57363–70. http://dx.doi.org/10.1039/c6ra08165g.
Повний текст джерелаАнотація:
The thermal, dilution and chemical effects of EGR result in relatively significant changes in the formation environment, in the physical and chemical reactions of particles and in the functional groups of the matter that constitutes the particles.
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Allenby, S., W.-C. Chang, A. Megaritis, and M. L. Wyszyński. "Hydrogen enrichment: A way to maintain combustion stability in a natural gas fuelled engine with exhaust gas recirculation, the potential of fuel reforming." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 215, no. 3 (March 1, 2001): 405–18. http://dx.doi.org/10.1243/0954407011525737.
Повний текст джерелаАнотація:
An experimental study was carried out to evaluate the potential of hydrogen enrichment to increase the tolerance of a stoichiometrically fuelled natural gas engine to high levels of dilution by exhaust gas recirculation (EGR). This provides significant gains in terms of exhaust emissions without the rapid reduction in combustion stability typically seen when applying EGR to a methane-fuelled engine. Presented results give the envelope of benefits from hydrogen enrichment. In parallel, the performance of a catalytic exhaust gas reforming reactor was investigated in order that it could be used as an onboard source of hydrogen-rich EGR. It was shown that sufficient hydrogen was generated with currently available prototype catalysts to allow the engine, at the operating points considered, to tolerate up to 25 per cent EGR, while maintaining a coefficient of variability of indicated mean effective pressure below 5 per cent. This level of EGR gives a reduction in NO emissions greater than 80 per cent in all test cases.
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Yoo, Heecheong, Bum Park, Honghyun Cho, and Jungsoo Park. "Performance Optimization of a Diesel Engine with a Two-Stage Turbocharging System and Dual-Loop EGR Using Multi-Objective Pareto Optimization Based on Diesel Cycle Simulation." Energies 12, no. 22 (November 6, 2019): 4223. http://dx.doi.org/10.3390/en12224223.
Повний текст джерелаАнотація:
The effects of an electric supercharger (eS) and a dual-loop exhaust gas recirculation (EGR) system on a passenger car’s diesel engine’s emissions and fuel efficiency under various worldwide harmonized light-duty vehicles test procedure (WLTP) reference operation points were investigated using a one-dimensional engine cycle simulation, called GT-Power. After heavy EGR application, the in-cylinder pressure and temperature declined due to a dilution effect. As eS power and rpm increased, the brake-specific fuel consumption (BSFC) decreased because the effects of the air flow rate increased. However, it was unavoidable that nitrogen oxide (NOx) emissions also increased due to the higher in-cylinder pressure and temperature. To induce more EGR to the intake system, a dual-loop EGR system was applied with eS at different low-pressure EGR (LP-EGR) fractions (0, 0.25, 0.5, 0.75, and 1.0). Under these conditions, a design of experiment (DoE) procedure was carried out and response surface plots of the BSFC and brake-specific NOx (BSNOx) were prepared. A multi-objective Pareto optimization method was used to improve the trade-off in results between the BSFC and BSNOx. Through optimization, optimal Pareto fronts were obtained, which suggested design parameters for eS power and rpm to control the engine under various LP fraction conditions.
Дисертації з теми "EGR dilution"
1
Gruselle, Catherine. "Etude du développement d’une flamme soumise à un gradient de concentration : Rôle de la stratification et des EGR." Thesis, Rouen, INSA, 2014. http://www.theses.fr/2014ISAM0003/document.
Повний текст джерелаАнотація:
La combustion stratifiée, qui consiste à brûler un mélange carburant/oxydant inhomogène, et la combustion diluée, consistant à ajouter une quantité limitée de gaz brûlés, sont deux technologies utilisées dans les moteurs à piston pour réduire leur consommation. Cette thèse est dédiée à l’étude de l’allumage dans ces deux types de milieux en régimes laminaire et turbulent. Un nouveau schéma cinétique pour la combustion propane/air a été dérivé et combiné à deux approches de modélisation différentes : la chimie complexe et une approche de chimie tabulée de type FPI. Dans le cas laminaire, les deux approches de modélisation donnent des résultats similaires et un modèle simple a mis en évidence l’importance de la dynamique des gaz frais et des gaz brûlés sur le développement du noyau. Dans le cas turbulent, plusieurs techniques d’analyse ont montré la dépendance de la vitesse absolue de la flamme au champ de vitesse moyen et la décorrélation des fluctuations locales de richesseStratified combustion, which consists in burning an inhomogeneous fuel/air mixture, and diluted combustion, which consists in adding a limited quantity of burnt gases, are two technologies used in internal combustion engines to reduce fuel consumption. This Ph.D is devoted to the study of ignition in these two types of combustion in laminar and turbulent regimes. A new kinetic scheme for propane/air combustion has been derived and combined to two modeling approaches: finite-rate chemistry and an FPI tabulated chemistry approach. In the laminar case, both approaches give similar results and a simplified model has highlighted the importance of fresh and burnt gases dynamics on the kernel development. In the turbulent case, several techniques of analysis have shown the dependency of absolute flame speed on the mean fluid velocity and the lack of correlation to the local equivalence ratio
2
Gruselle, Catherine. "Etude du développement d'une flamme soumise à un gradient de concentration : Rôle de la stratification et des EGR." Phd thesis, INSA de Rouen, 2014. http://tel.archives-ouvertes.fr/tel-01005306.
Повний текст джерелаАнотація:
La combustion stratifiée, qui consiste à brûler un mélange carburant/oxydant inhomogène, et la combustion diluée, consistant à ajouter une quantité limitée de gaz brûlés, sont deux technologies utilisées dans les moteurs à piston pour réduire leur consommation. Cette thèse est dédiée à l'étude de l'allumage dans ces deux types de milieux en régimes laminaire et turbulent. Un nouveau schéma cinétique pour la combustion propane/air a été dérivé et combiné à deux approches de modélisation différentes : la chimie complexe et une approche de chimie tabulée de type FPI. Dans le cas laminaire, les deux approches de modélisation donnent des résultats similaires et un modèle simple a mis en évidence l'importance de la dynamique des gaz frais et des gaz brûlés sur le développement du noyau. Dans le cas turbulent, plusieurs techniques d'analyse ont montré la dépendance de la vitesse absolue de la flamme au champ de vitesse moyen et la décorrélation des fluctuations locales de richesse.
3
Xu, Boyang. "Compréhension et modélisation de flammes d'essence à fortes charges et fortes dilutions." Thesis, Institut polytechnique de Paris, 2019. http://www.theses.fr/2019IPPAE003.
Повний текст джерелаАнотація:
La réduction des émissions de CO2 et de polluants est un des enjeux essentiels pour faire face aux problèmes liés au changement climatique. Dans le secteur des transports, la technologie de recirculation des gaz d’échappement (EGR) est souvent utilisée dans les moteurs turbo-compressés à allumage commandé pour réduire la consommation de carburant, inhiber les risques de cliquetis et réduire les émissions de NOx. Cependant, des taux d’EGR élevés restent difficiles à atteindre car ils réduisent le dégagement de chaleur et la stabilité du moteur. L'augmentation du niveau de turbulence et la mise en oeuvre de systèmes à allumage commandé avancés n’apportant pas d'améliorations suffisantes dans des conditions aussi extrêmes, la chimie de la combustion pour les très hautes dilutions suscite un intérêt croissant. Le présent travail vise à comprendre la chimie de combustion des flammes prémélangées essence/air très diluées et à établir un mécanisme cinétique détaillé par modélisation multi-échelle afin de prévoir les caractéristiques de combustion avec une précision suffisante dans des conditions de forte dilution.Ce travail adopte une approche de modélisation multi-échelle et cible la vitesse de flamme laminaire (SL) d'un substitut d'essence, appelé TRFE et qui est constitué d'isooctane, de n-heptane, de toluène et d'éthanol. Pour la modélisation à l’échelle microscopique, la réaction entre le cétène et le radical hydroxyle, qui pourrait être importante pour la SL dans des conditions très diluées, est étudiée théoriquement à l'aide de méthodes de structure électronique ab initio pour la surface d'énergie potentielle (PES) et Rice -- Ramsperger -- Kassel -- Marcus Theory couplé à l'équation maîtresse (RRKM / ME) pour les coefficients de vitesse. Des PES détaillées sont obtenues, les voies dominantes sont identifiées et leurs coefficients de vitesse phénoménologiques sont dérivés pour être utilisés dans la modélisation de la combustion. Pour la modélisation à l'échelle macroscopique, les paramètres cinétiques, thermodynamiques et de transport importants pour la vitesse de la flamme laminaire dans des conditions très diluées sont d'abord identifiés à l'aide d'une analyse de sensibilité réalisée sur une version initiale du mécanisme TRFE de départ. Les réactions sensibles impliquent principalement HO2, les espèces C2 - C3 et des radicaux issus du carburant. Le mécanisme initial, via un travail spécifique à chacun des sous-mécanismes, est mis à jour à l'aide des paramètres cinétiques les plus récents issus de la littérature. Enfin, un mécanisme détaillé adapté aux calculs de vitesse de flamme laminaire dans des conditions de forte dilution est validé. Une corrélation mathématique de SL est établie pour l'utilisation dans des simulations numériques de la dynamique des fluides (CFD)Reducing CO2 and pollutant emission is the essential challenge when dealing with climate change problems. In the transport sector, exhaust gas recirculation (EGR) technology is often used in turbocharged gasoline spark ignition (SI) engines to increase fuel economy, inhibit knock tendency, and reduce NOx emissions. However, high EGR ratios are still difficult to achieve, as they result in reduced heat release and engine stability. As increasing turbulence level and advance spark ignition systems could not bring sufficient improvements at such extreme conditions, growing interest is cast onto the combustion chemistry under high dilution. The present work aims to understand the combustion chemistry of highly-diluted gasoline premixed flames and to establish a detailed kinetic mechanism by multi-scale modeling to predict combustion characteristics with sufficient accuracy at highly-diluted conditions.This work adopts a multi-scale modeling approach, and targets on the laminar flame speed (SL) of a gasoline surrogate, which is named toluene reference fuel with ethanol addition (TRFE) and consist of isooctane, n-heptane, toluene, and ethanol. For micro-scale modeling, the reaction between ketene and hydroxyl radical, which might be important to the SL at highly-diluted conditions, is studied theoretically using ab initio electronic structure methods for the potential energy surface (PES) and Rice–Ramsperger–Kassel–Marcus Theory coupled with Master Equation (RRKM/ME) for the rate coefficients. Detailed PES is obtained, dominant pathways are identified, and their phenomenological rate coefficients are derived to be utilized in combustion modeling. For macro-scale modeling, firstly, important kinetic, thermodynamic, and transport parameters to the laminar flame speed at highly-diluted conditions, are firstly identified using sensitivity analysis based on a starting mechanism. Sensitive reactions are found to mostly involve HO2, C2--C3 species and fuel radicals. Secondly, in the sub-mechanisms where these reactions lies, diluted flames of the corresponding fuels are studied and chemical detail of the dilution effects are explored. The starting mechanism is updated by state-of-the-art kinetics parameters found in the literature for each sub-mechanisms. Finally, a detailed mechanism suitable for laminar flame speed calculations at highly-diluted conditions is established after validation. A mathematical SL correlation is generated for the use in computational fluid dynamic (CFD) simulations
4
Tang, Karen Sze-Hang. "The effects of pH and dilution pretreatments and removal of water-soluble components on the functional properties of spray-dried egg yolk powder." Thesis, 2000. http://hdl.handle.net/2429/10982.
Повний текст джерелаАнотація:
Spray-drying increases shelf-life and convenience of egg yolk, but may induce damage
to its functional properties. The objectives of this study were to investigate the functional
properties of spray-dried yolk powders as a function of different pH (3 to 9) and dilution (2- to
10-fold) pre treatments, and to study the impact of spray-drying on functional properties of yolk
pellet, the fraction remaining after removal of water-soluble components.
Protein solubility and emulsifying properties (Emulsifying Activity Index and Emulsion
Stability Index) were considered. Pre-drying pH and dilution had significant effects on protein
solubility of the spray-dried powders (p < 0.0001). Protein solubilities of liquid and spray-dried
yolk were ~ 70 % and 50 %, respectively. Highest solubility (> 60 %) was obtained when predrying
pH was between 5.5 to 9 and dilution between 4- to 9-fold, while emulsions of the yolk
powders were most stable when pre-drying pH was between 8.0 to 10.0 and dilution between 2-
to 4-fold. Based on the protein functionality test results, the best pretreatment condition would
be pH 8.5 with 6 times dilution and the worst condition would be pH 3.0 with 6 times dilution.
Pellet powder was relatively insoluble (25 % protein solubility) and its emulsion was less stable.
Interestingly, liquid pellet gave better emulsion stabilization than commercial liquid yolk.
Freeze-drying produced dried yolk with better emulsion stability than spray-drying.
However, duration of storage and batch-to-batch variation of commercial yolk might have
influenced the results.
Differential Scanning Calorimetry showed similar thermograms for yolk powder with
best pretreatment conditions, liquid yolk and spray-dried yolk control (T[sub d] ~ 80°C). Almost no
denaturation peak was detected for pellet samples or yolk powder with the worst pretreatment
conditions. Results showed that water-soluble fraction of yolk was the main contributor to the
thermal behavior of yolk, and freeze-dried yolk samples were more labile to heat denaturation
when reconstituted at pH 3 than at higher pHs.
The Raman spectra of yolk samples were dominated by vibrational bands of the lipid
components, and therefore possible differences in lipoprotein structure as a function of spray
drying could not be detected.
Тези доповідей конференцій з теми "EGR dilution"
1
Dumitrescu, Cosmin E., W. Stuart Neill, Hongsheng Guo, and Wallace L. Chippior. "Dilution Effects on Partially-Premixed Combustion of an Ultra-Low Sulphur Diesel Fuel Under Low-Load Operation." In ASME 2012 Internal Combustion Engine Division Spring Technical Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ices2012-81236.
Повний текст джерелаАнотація:
Dilution of partially-premixed combustion (PPC) using different combinations of excess air (λ>1) and exhaust gas recirculation (EGR) was investigated in a single-cylinder, heavy-duty diesel engine equipped with common-rail fuel injection. The experiments were limited to a single fuel injection event using ultra-low sulphur diesel fuel at a low engine load (∼3 bar BMEP) and engine speeds of 900 and 1350 rpm. The start of injection was varied to optimize the combustion performance and emissions. The experimental results show that increasing air dilution at constant EGR reduced BSFC slightly. CO and HC emissions decreased significantly due to the increased oxygen concentration, but NOx and soot emissions increased. For a given level of charge dilution, there was an optimal EGR rate to minimize BSFC. NOx emissions decreased significantly as the proportion of dilution by EGR was increased, but CO and HC emissions increased due to the reduced in-cylinder temperature and oxygen concentration, which increased the combustion duration.
2
Chinnathambi, Prasanna, Joohan Kim, Riccardo Scarcelli, Sibendu Som, Ashish Shah, Munidhar S. Biruduganti, and Douglas E. Longman. "A Numerical Study on the Effects of EGR Dilution in a Pre-Chamber Ignited Natural Gas Engine." In ASME 2021 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/icef2021-67836.
Повний текст джерелаАнотація:
Abstract Lean burn natural gas engines offer low particulate emissions than diesel counterparts and provides higher efficiency when compared to stoichiometric operation. However, with the lean burn strategy, three-way catalysts (TWC) compatibility is lost due to the oxidized exhaust stream. In comparison, the exhaust gas recirculation (EGR) dilution strategy can maintain compatibility with emission after-treatment systems. The maximum tolerated EGR levels are limited by the combustion stability degradation resulting from unfavorable mixture gas composition. Prechamber spark ignition (PCSI) systems, known to increase dilution tolerance in SI engines under lean conditions, was evaluated as a means to improve EGR dilution tolerance. Scavenging of residuals within the pre-chamber is typically a concern with these systems and as such studies on these systems working with various levels of EGR ratios are rare. In this work, an unscavenged (or unfueled, or passive) PCSI system installed in a medium-duty natural gas engine is modeled using CONVERGE CFD code. Simulation results are compared against the experimental data in terms of in-cylinder pressure and heat release rates from low to high (10% to 22%) EGR levels. The prediction capability of two combustion models, a multi-zone well-stirred reactor model and a flamelet-based combustion model, i.e. G-equation, are compared and evaluated under these conditions within the RANS framework. The G-equation model predictions agreed well with experiments up to 18.8% EGR dilution level. In comparison, the MZ-WSR model predicted slow prechamber combustion at all dilution levels which influenced the main chamber combustion phasing.
3
Khairallah, Hassan A., and Umit O. Koylu. "A Computational Study of In-Cylinder NOx Reduction Strategies for a Compression-Ignition Engine Fueled With Diesel/Hydrogen Mixtures." In ASME 2015 9th International Conference on Energy Sustainability collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/es2015-49098.
Повний текст джерелаАнотація:
Considerable efforts have been made to introduce alternative fuels for use in conventional diesel and gasoline engines. There is significant interest in adding hydrogen to a diesel engine to reduce emissions and improve efficiency. However, the main challenge associated with the use of hydrogen in diesel engines is high nitrogen oxide (NOX) emissions. In the present study, a reduced chemical kinetics mechanism, consisting of 52 reactions and 29 chemical species for n-heptane fuel combustion, was incorporated with detailed chemical kinetics consisting of 29 reactions for hydrogen as well as additional nitrogen oxidation. This reaction mechanism was coupled with 3-D advanced CFD software to investigate the performance and emission characteristics of a diesel-hydrogen dual-fuel engine. Computational results showed good agreements with the experimental results for brake thermal efficiency, CO2, CO, and NOX emissions. The model was then employed to examine the effects of exhaust gas recirculation (EGR) and N2 dilution on NOX emissions. The computational results quantified the reduction in NOX emissions with EGR and N2 dilution, and a more remarkable reduction was found with 30% N2 dilution. However, in terms of the N2 dilution, a general decreasing trend was observed for both NOX and CO2 emissions, while CO emissions increased. In relation to the EGR, the NOX emissions decreased while CO2 and CO emissions significantly increased. Additionally, the results showed that the indicated mean effective pressure (IMEP) and indicated power decreased as the N2 dilution increased. The same trend was observed for the EGR but the reduction was less compared to that of the N2 dilution.
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Serrano, José Ramón, Jaime Martín Díaz, Josep Gomez-Soriano, and Rodrigo Raggi. "Exploring the Oxy-Fuel Combustion in Spark-Ignition Engines for Future Clean Powerplants." In ASME 2022 ICE Forward Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icef2022-89167.
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Abstract In the context of the CO2 challenge, oxy-fuel combustion in internal combustion engines (OFC-ICE) arises as a promising technology for carbon capture and almost zero-NOx solutions. Although the literature shows some experimental and theoretical works on OFC-ICE, there is a lack of systematic studies dealing with dilution strategies or where non-synthetic EGR is used. Using a combination of 0D-1D and CFD modeling and experimental measurements, dilution with oxygen (λ > 1) and real EGR in a single-cylinder spark-ignition OFC-ICE is here assessed, considering thermo-mechanical limitations and knocking. Results show that an EGR strategy is more appropriate than O2 dilution. A slightly poor mixture near stoichiometric conditions, with EGR rates around 70%, reduces NOx more than 99%, and CO and uHC up to 90% with respect to the conventional ICE. It is concluded that OFC-ICE has a lower knocking propensity, thus allowing to increase the compression ratio to partially compensate for the expected efficiency diminution to about 4 percentage points.
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Xu, Min, Grant Chen, Chao Daniels, and Mike Dong. "Numerical Study on Swirl-Type High-Dilution Stratified EGR Combustion System." In CEC/SAE Spring Fuels & Lubricants Meeting & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2000. http://dx.doi.org/10.4271/2000-01-1949.
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Singh, Aditya Prakash, Gordon Patrick McTaggart-Cowan, and Patrick Kirchen. "Air Fuel Dilution in a Pilot Ignited Direct Injection Natural Gas Engine: Pollutants, Performance, and System Level Considerations." In ASME 2019 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/icef2019-7200.
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Abstract Dilution of natural gas fuel with air for use in a pilot ignited direct injection natural gas engine was investigated to evaluate the impact of this strategy on emissions and engine performance. A representative heavy-duty mode (mid to high-load at medium speed) was considered and the equivalence ratio (Φ) and exhaust gas recirculation (EGR) rates were varied from this representative mode. Air dilution resulted in a significant reduction in several pollutants: 90 to 97% reductions in black carbon particulate matter, 45 to 95% reductions in carbon monoxide, 68 to 85% reductions in total unburnt hydrocarbons. NOx emissions were found to increase by between 1.5 and 2.5x, depending on Φ and EGR, for a fixed combustion phasing. Beyond the emissions improvements, the gross indicated thermal efficiency increased by 2.5 percentage points at both high and low EGR rates. At higher EGR rates, this improvement was due to improved combustion efficiency, while the mechanism for efficiency improvement at lower EGR rates was unclear. The application of air-fuel dilution requires compressed air (> 300 bar) to mix with natural gas at high pressures. A system level analysis considered the compression power required by an industrial 3-stage reciprocating compressor and indicated that the gross indicated thermal efficiency improvements could compensate for the compression requirements for engine operation at high Φ.
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Dal Forno Chuahy, Flavio, Derek Splitter, Martin Wissink, and Vicente Boronat Colomer. "EGR Dilution and Fuel Property Effects on High-Efficiency Spark-Ignition Flames." In SAE WCX Digital Summit. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2021. http://dx.doi.org/10.4271/2021-01-0483.
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Maugham, R. D., N. D. Vaughan, C. J. Brace, and S. W. Murray. "Preliminary Investigation of Dilution Strategies to Control Engine Torque During Transient Events." In ASME 2001 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-ice-428.
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Abstract A continuously variable transmission (CVT) allows a powertrain controller the freedom to develop a required output power at a range of engine torque and speed conditions. This flexibility can be used to maximise fuel efficiency. Due to low frictional and pumping losses a gasoline engine’s fuel efficiency is maximised at low speed, high torque conditions. However due to the reduced torque margin available, controlling a gasoline engine in this region compromises transient vehicle response. Dilution torque control, using EGR or lean burn, has the potential to maintain the economy gains available using a CVT powertrain whilst improving a vehicle’s driveability. This paper introduces preliminary work that has been undertaken to investigate the potential of charge dilution to control steady state engine torque. A test rig has been developed based around an engine fitted with variable cam phasing and an external EGR system. The paper contains a discussion of initial results of a lean dilution test program used to demonstrate the principle.
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Glewen, William, Chris Hoops, Joel Hiltner, and Michael Flory. "Comparative Analysis of EGR and Air Dilution in Spark-Ignited Natural Gas Engines." In ASME 2017 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icef2017-3608.
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Industrial natural gas engines are used in a wide range of applications, each with unique requirements in terms of power density, initial cost, thermal efficiency, and other factors. As a result of these requirements, distinct engine designs have evolved to serve various applications. Heavy-duty spark-ignited engines can generally be divided into two broad categories based on their charge characteristics and method of emissions control. Stoichiometric engines are widely used in applications where first cost, absolute emissions and relative engine simplicity are more important than fuel consumption. In most of the developed world, stoichiometric engines are equipped with a three-way catalyst to control emissions of nitrogen oxides (NOx) as well as products of incomplete combustion and raw unburned fuel. Dilution of the charge mixture with excess air reduces the peak combustion gas temperature and associated heat rejection. As a result, lean burn engines are generally able to achieve higher efficiency and power density without inducing excessive component temperatures or end gas knock. NOx formation is mitigated by the reduced gas temperatures, such that most regulatory standards can currently be met in-cylinder. Significant obstacles exist to meeting more stringent future emissions regulations in this manner, however. Another possible strategy is to dilute the charge mixture with recirculated exhaust gas. This offers similar benefits as air dilution while maintaining the ability to use a three-way catalyst for emissions after-treatment. While similar principles apply in either case, the choice of diluent can have a significant impact on knock resistance, emissions formation, thermal efficiency, and other parameters of importance to engine developers and operators. This work aimed to examine the unique characteristics of EGR and air dilution from a thermodynamic and combustion perspective. A combination of cycle simulation tools and experimental data from a single-cylinder test engine was applied to demonstrate the impact of diluent properties on a fundamental level, and to illustrate departures from idealized behavior and practical considerations specific to the development of combustion systems for spark-ignited natural gas engines.
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Nazari, Shima, Anna Stefanopoulou, Rani Kiwan, and Vasilios Tsourapas. "A Coordinated Boost Control in a Twincharged Spark Ignition Engine With High External Dilution." In ASME 2016 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/dscc2016-9691.
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This paper proposes a novel master-slave control strategy for coordination of throttle, wastegate and supercharger actuators in an electrically twincharged engine in order to guarantee efficient boost control during transients, while at steady state a throttle-wastegate coordination provides minimum engine backpressure hence engine efficiency elevation. The benefits and challenges associated with Low Pressure Exhaust Gas Recirculation (LP-EGR) in a baseline turbocharged engine, including improved engine efficiency, mainly due to better combustion phasing, and sluggish engine response to a torque demand due to slowed down air path dynamics were studied and quantified in [1]. Hence in this paper an electrical Eaton TVS roots type supercharger at high pressure side of the turbocharger compressor (TC compressor) is added to the baseline turbocharged engine and the performance of the proposed controller in the presence of LP-EGR, which is a more demanding condition, is evaluated and compared to the turbocharged engine. One dimensional (1D) crankangle resolved engine simulations show that the proposed master-slave control strategy can effectively improve the transient response of the twincharged engine, making it comparable to naturally aspirated engines, while the consumed electrical energy during transients can be recovered from the decreased fuel consumption due to LP-EGR conditions at steady state in approximately 1 second. Finally, a simple controller is developed to bypass the TC compressor and maximize the engine feeding charge during the transients in order to avoid TC compressor choking and achieve faster response.
Звіти організацій з теми "EGR dilution"
1
Keating, Edward, and Charles Gough. The Application of High Energy Ignition and Boosting/Mixing Technology to Increase Fuel Economy in Spark Ignition Gasoline Engines by Increasing EGR Dilution Capability. Office of Scientific and Technical Information (OSTI), July 2015. http://dx.doi.org/10.2172/1253155.
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Jorgensen, Frieda, John Rodgers, Daisy Duncan, Joanna Lawes, Charles Byrne, and Craig Swift. Levels and trends of antimicrobial resistance in Campylobacter spp. from chicken in the UK. Food Standards Agency, September 2022. http://dx.doi.org/10.46756/sci.fsa.dud728.
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Campylobacter spp. are the most common bacterial cause of foodborne illness in the UK, with chicken considered to be the most important vehicle of transmission for this organism. It is estimated there are 500,000 cases of campylobacteriosis in the UK annually, with Campylobacter jejuni (C. jejuni) and Campylobacter coli (C. coli) accounting for approximately 91% and 8 % of infections, respectively. Although severe infection in humans is uncommon, treatment is seldom needed for human infection but usually involves the administration of a macrolide (e.g., azithromycin) or a fluoroquinolone (e.g., ciprofloxacin). An increased rate of resistance in Campylobacter in chicken to such antimicrobials could limit effective treatment options for human infections and it is therefore important to monitor changes in rates of resistance over time. In this report we analysed trends in antimicrobial resistance (AMR) in C. jejuni and C. coli isolated from chicken in the UK. The chicken samples were from chicken reared for meat (ie. broiler chicken as opposed to layer chicken (ie. egg-laying chicken)) and included chicken sampled at slaughterhouses as well as from retail stores in the UK. Datasets included AMR results from retail surveys of Campylobacter spp. on chicken sampled in the UK from various projects in the time period from 2001 to 2020. In the retail surveys, samples were obtained from stores including major and minor retail stores throughout the UK (in proportion to the population size of each nation) and Campylobacter spp. testing was performed using standard methods with the majority of isolates obtained from direct culture on standard media (mCCDA). Data from national scale surveys of broiler chicken, sampling caecal contents and carcase neckskins at slaughterhouses, undertaken by APHA in 2007/2008, and between 2012 and 2018 were also included in the study. In the APHA-led surveys, Campylobacter were isolated using standard culture methods (culture onto mCCDA) and antimicrobial susceptibility testing was performed by a standard microbroth dilution method to determine the minimum inhibitory concentration (MIC) of isolates. Care was taken when comparing data from different studies as there had been changes to the threshold used to determine if an isolate was susceptible or resistant to an antimicrobial in a small number of scenarios. Harmonised thresholds (using epidemiological cut-off (ECOFF) values) were employed to assess AMR with appropriate adjustments made where required to allow meaningful comparisons of resistance prevalence over time. Data from additional isolates where resistance to antimicrobials were predicted from genome sequence data were also considered.