Journal articles: 'High pressure soot formation'

1

Karataş, Ahmet E., and Ömer L. Gülder. "Soot formation in high pressure laminar diffusion flames." Progress in Energy and Combustion Science 38, no. 6 (December 2012): 818–45. http://dx.doi.org/10.1016/j.pecs.2012.04.003.

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Bohm, H., M. Braun-Unkhoff, and P. Frank. "Investigations on initial soot formation at high pressures." Progress in Computational Fluid Dynamics, An International Journal 3, no. 2/3/4 (2003): 145. http://dx.doi.org/10.1504/pcfd.2003.003771.

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HU, D., M. BRAUN-UNKHOFF, and P. FRANK. "Modeling Study on Soot Formation at High Pressures." Combustion Science and Technology 149, no. 1-6 (December 1999): 79–94. http://dx.doi.org/10.1080/00102209908952100.

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D'ALESSIO, J., M. LAZZARO, P. MASSOLI, and V. MOCCIA. "Time Resolved Absorption Spectroscopy of Soot Formation Process in High Pressure, High Temperature Environment." Combustion Science and Technology 149, no. 1-6 (December 1999): 135–55. http://dx.doi.org/10.1080/00102209908952103.

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Braun-Unkhoff, M., A. Chrysostomou, P. Frank, E. Gutheil, R. Lückerath, and W. Stricker. "Experimental and numerical study on soot formation in laminar high-pressure flames." Symposium (International) on Combustion 27, no. 1 (January 1998): 1565–72. http://dx.doi.org/10.1016/s0082-0784(98)80565-1.

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CROOKES, R. J. "SOOT FORMATION AND OXIDATION AT HIGH PRESSURE IN A CONFINED SPRAY FLAME." Combustion Science and Technology 178, no. 8 (August 2006): 1491–510. http://dx.doi.org/10.1080/00102200600721289.

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Crookes, R. J., G. Sivalingam, and M. A. A. Nazha. "FACTORS INFLUENCING SOOT PARTICULATE FORMATION AND OXIDATION IN HIGH-PRESSURE SPRAY COMBUSTION." Clean Air: International Journal on Energy for a Clean Environment 5, no. 3 (2004): 267–80. http://dx.doi.org/10.1615/interjenercleanenv.v5.i3.50.

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Yen, May, Vinicio Magi, and John Abraham. "Modeling Soot Formation in Turbulent Jet Flames at Atmospheric and High-Pressure Conditions." Energy & Fuels 32, no. 8 (July 25, 2018): 8857–67. http://dx.doi.org/10.1021/acs.energyfuels.8b01946.

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Nakamura, Mariko, Daichi Nishioka, Jun Hayashi, and Fumiteru Akamatsu. "Soot formation, spray characteristics, and structure of jet spray flames under high pressure." Combustion and Flame 158, no. 8 (August 2011): 1615–23. http://dx.doi.org/10.1016/j.combustflame.2010.12.033.

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Edland, Rikard, Thomas Allgurén, Fredrik Normann, and Klas Andersson. "Formation of Soot in Oxygen-Enriched Turbulent Propane Flames at the Technical Scale." Energies 13, no. 1 (January 1, 2020): 191. http://dx.doi.org/10.3390/en13010191.

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Soot is an important component for heat transfer in combustion processes. However, it is also a harmful pollutant for humans, and strict emissions legislation motivates research on how to control soot formation and release. The formation of soot is known to be triggered by high temperature and high pressure during combustion, and it is also strongly influenced by the local stoichiometry. The current study investigates how the formation of soot is affected by increasing the oxygen concentration in the oxidizer, since this affects both the temperature profile and partial pressures of reactants. The oxygen-to-fuel ratio is kept constant, i.e., the total flow rate of the oxidizer decreases with increasing oxygen concentration. Propane is combusted (80 kWth) while applying oxygen-enriched air, and in-flame measurements of the temperature and gas concentrations are performed and combined with available soot measurements. The results show that increasing the oxygen concentration in the oxidizer from 21% to 27% slightly increases soot formation, due to higher temperatures or the lower momentum of the oxidizer. At 30% oxygen, however, soot formation increases by orders of magnitude. Detailed reaction modeling is performed and the increase in soot formation is captured by the model. Both the soot inception rates and surface growth rates are significantly increased by the changes in combustion conditions, with the increase in soot inception being the most important. Under atmospheric conditions, there is a distinct threshold for soot formation at around 1200 °C for equivalence ratios >3. The increase in temperature, and the slower mixing that results from the lower momentum of the oxidizer, have the potential to push the combustion conditions over this threshold when the oxygen concentration is increased.

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Sivaramakrishnan, R., Robert S. Tranter, and K. Brezinsky. "High Pressure Pyrolysis of Toluene. 2. Modeling Benzyl Decomposition and Formation of Soot Precursors." Journal of Physical Chemistry A 110, no. 30 (August 2006): 9400–9404. http://dx.doi.org/10.1021/jp0608224.

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Lockett, R. D. "Instabilities and soot formation in spherically expanding, high pressure, rich, iso-octane-air flames." Journal of Physics: Conference Series 45 (July 1, 2006): 154–60. http://dx.doi.org/10.1088/1742-6596/45/1/020.

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GRÜNEBERGER, Patrick, Bernhard JOCHAM, and Ernst WINKLHOFER. "Diesel combustion in high load situations: a visual analysis of mixture formation and air utilization." Combustion Engines 169, no. 2 (May 1, 2017): 3–6. http://dx.doi.org/10.19206/ce-2017-201.

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As fuel injection pressures keep rising, questions focus on additional benefits to be gained from the considerable efforts to achieve and handle the fuel pressure increments. The aim of fuel injection processes is to support the mixing of fuel molecules with oxygen. The steps towards this goal include fuel atomization, evaporation, heat transfer from air into the liquid or vaporized fuel together with transport of fuel for best air utilization. Engineering degrees of freedom include the parameters of the fuel injection system and handling of in-cylinder gas conditions. The paper describes basic high pressure flow processes, spray propagation, evaporation and combustion and the mixing of flame clouds with in-cylinder air for oxidation of high temperature soot particles. Experimental evidence of such processes is derived from laboratory flow tests as well as from optically accessed engines operated under conditions relevant for todays passenger car and heavy duty engines.

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Yang, Kang, Hirotaka Yamakawa, Keiya Nishida, Youichi Ogata, and Yusuke Nishioka. "Effect of split injection on mixture formation and combustion processes of diesel spray injected into two-dimensional piston cavity." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, no. 8 (September 19, 2017): 1121–36. http://dx.doi.org/10.1177/0954407017724246.

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The objective of this study is to obtain an enhanced understanding of the effect of split injection on mixture formation and combustion processes of diesel spray. A two-dimensional (2D) piston cavity of the same shape as that used in a small-bore diesel engine was employed to form the impinging spray flame. The fuel was injected into a high pressure, high temperature constant volume vessel through a single-hole nozzle with a hole diameter of 0.11 mm. The injection process comprised a pre-injection followed by the main injection. The main injection was carried out either as a single injection of injection pressure 100 MPa (Pre+S100), or by two types of split injection of injection pressure 160 MPa. The latter two types were defined by mass fraction ratios 1:1 and 3:1 (Pre+D160_1-1, Pre+D160_3-1). In order to observe the spray mixture formation process, the tracer laser absorption scattering (LAS) techique was adopted. Tracer LAS fuel with 97.5 vol% of n-tridecane and 2.5 vol% of 1-methylnaphthalene (α-MN) was employed. The spatial distributions of the vapor and liquid phases and the spray mixture formation characteristics in the 2D piston cavity for the three injection strategies were investigated. The diesel spray combustion and soot formation processes were studied using a high-speed video camera. The flame structure and soot formation process were examined using two-color pyrometry. The experimental results revealed that the split-injection vapor distribution was significantly more homogeneous than that of the single injection. The main injection fuel caught up with the pre-injection fuel and provided the spray tip with substantial additional momentum, enabling it to advance further. A high soot concentration and low temperatures appeared near the cavity wall region under the three injection strategies. The soot reduction rate for split injection was higher than that for single injection. The second main injection caught up with the previous injection’s flame, which deteriorated the combustion and resulted in higher soot generation. The effect of split injection on the process of soot evolution finished at the same time as that of single injection.

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LOCKETT, R., and R. WOOLLEY. "Instabilities and soot formation in high-pressure, rich, iso-octane–air explosion flames1. Dynamical structure." Combustion and Flame 151, no. 4 (December 2007): 601–22. http://dx.doi.org/10.1016/j.combustflame.2007.08.004.

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16

BAE, Myurng-hoan, Takeyuki KAMIMOTO, and Haruki KOBAYASHI. "A study on soot formation in premixed combustion at high pressures." Transactions of the Japan Society of Mechanical Engineers Series B 54, no. 508 (1988): 3542–46. http://dx.doi.org/10.1299/kikaib.54.3542.

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17

Zhao, Zhihao, Xiucheng Zhu, Jeffrey Naber, and Seong-Young Lee. "Assessment of impinged flame structure in high-pressure direct diesel injection." International Journal of Engine Research 21, no. 2 (July 1, 2019): 391–405. http://dx.doi.org/10.1177/1468087419859788.

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Spray impingement often occurs during cold-start in direct-injection diesel engines, affecting the subsequent combustion process by altering the local flow condition. This work has investigated the impinged flame structure by examining local expansion distance and planar curvature of the boundary in details. The experiments were carried out in a constant volume combustion chamber. The injection pressure and ambient density were varied from 120 to 180 MPa and 14.8 to 30.0 kg/m3 under non-vaporizing conditions, respectively. For reacting conditions, the injection pressure and ambient density were fixed at 150 MPa and 22.8 kg/m3 but with different ambient temperatures from 800 to 1000 K. Unlike orthogonal spray impingement, the profile of expansion distance along the radial direction at the 60° impinging angle is non-uniform but the profile is comparable between the non-vaporizing and reacting conditions under the same injection pressure and ambient density. With the help of Intensity-aXial-Time method, the most intensive soot luminosity region and Mie scattering intensity region are identified and the region has been found to be along the impinged spray axial direction. Outmost boundary of an impinged flame is found to have wrinkles attributed to air entrainment. The temporal level of flame wrinkles is higher in reacting conditions than in non-vaporizing conditions. The scatter distribution of the boundary curvature and near-field soot formation illustrates an inverted “S” shape correlation with time. High flame luminosity is found to be formed in concave regions while less soot is formed in convex regions. This inverted S-shape is a new finding of the state relationship at the solid–liquid–gas impinged flame propagation. Finally, heat flux measurement through the plate is examined.

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18

Kim, H. J., B. W. Ryu, and C. S. Lee. "Modelling for investigation of combustion and emission characteristics in a high-speed direct-injection diesel engine with light duty under various operating conditions." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 222, no. 11 (November 1, 2008): 2159–70. http://dx.doi.org/10.1243/09544070jauto882.

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A numerical study was conducted to investigate combustion and emission characteristics in a high-speed direct-injection engine with a common-rail injection system under various operating conditions. In order to analyse the combustion characteristics, several models were used in this study. They were the renormalization group k– ε model, the hybrid Kelvin—Helmholtz (wave) and the Rayleigh—Taylor model, the shell auto-ignition model, and the laminar and turbulent characteristic timescale combustion model. The prediction of exhaust emissions was conducted using nitrogen oxide NO x formation with an extended Zel'dovich mechanism and Hiroyasu soot formation with the Nagle—Strickland-Constable oxidation model respectively. Experimental combustion and emission characteristics were compared with calculated results under various operating conditions, such as injection timing, injection pressure, fuel mass, and engine speed. The calculated results show similar patterns to the experimental results in the cylinder pressure and the rate of heat release. In the emissions characteristics, NO x emission decreased as injection timing was retarded and the NO x and soot amounts increased with the increase in the injected fuel mass. The calculated soot trends for various injection timings showed different patterns from the experimental trends as the injection timing were retarded.

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19

Razak, Muhammad F. A., Fatemeh Salehi, and Muhammad A. Chishty. "An Analysis of Turbulent Mixing Effects on the Soot Formation in High Pressure n-dodecane Sprays." Flow, Turbulence and Combustion 103, no. 3 (June 14, 2019): 605–24. http://dx.doi.org/10.1007/s10494-019-00045-9.

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20

Yun, H., and R. D. Reitz. "Combustion optimization in the low-temperature diesel combustion regime." International Journal of Engine Research 6, no. 5 (October 1, 2005): 513–24. http://dx.doi.org/10.1243/146808705x30576.

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A microgenetic algorithm (μGA) code was applied to optimize experimentally an HSDI single-cylinder diesel engine equipped with a common rail fuel-injection system in order to reduce NOx, soot, and b.s.f.c. simultaneously. Four control factors were used, namely, start-of-injection (SOI) timing, intake boost pressure level, cooled exhaust gas recirculation (EGR) rate, and fuel-injection pressure. The search space was designed to be within the experimental capabilities of the engine and control system. The engine testing was done at 1550 r/min, and 25 per cent load. The optimum results showed significant improvements for the NOx and soot emissions. Through analysis of the combustion characteristics, the mechanisms of emission reduction were revealed. The optimum featured a long ignition delay due to retarded SOI timing, and low combustion temperatures as a result of high EGR rates. The resulting long time for mixing and low temperatures helps suppress soot formation. To explore further the effect of mixing on emissions in the low-temperature combustion regime, factors that enhance turbulent mixing rates, including the use of high injection pressures and post injections were examined. The results show that optimal post injections are useful further to reduce emissions when they feature a short injection pulse with an optimal dwell time between injections.

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21

Pastor, José V., José M. García-Oliver, Carlos Micó, Alba A. García-Carrero, and Arantzazu Gómez. "Experimental Study of the Effect of Hydrotreated Vegetable Oil and Oxymethylene Ethers on Main Spray and Combustion Characteristics under Engine Combustion Network Spray A Conditions." Applied Sciences 10, no. 16 (August 7, 2020): 5460. http://dx.doi.org/10.3390/app10165460.

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The stringent emission regulations have motivated the development of cleaner fuels as diesel surrogates. However, their different physical-chemical properties make the study of their behavior in compression ignition engines essential. In this sense, optical techniques are a very effective tool for determining the spray evolution and combustion characteristics occurring in the combustion chamber. In this work, quantitative parameters describing the evolution of diesel-like sprays such as liquid length, spray penetration, ignition delay, lift-off length and flame penetration as well as the soot formation were tested in a constant high pressure and high temperature installation using schlieren, OH∗ chemiluminescence and diffused back-illumination extinction imaging techniques. Boundary conditions such as rail pressure, chamber density and temperature were defined using guidelines from the Engine Combustion Network (ECN). Two paraffinic fuels (dodecane and a renewable hydrotreated vegetable oil (HVO)) and two oxygenated fuels (methylal identified as OME1 and a blend of oxymethylene ethers, identified as OMEx) were tested and compared to a conventional diesel fuel used as reference. Results showed that paraffinic fuels and OMEx sprays have similar behavior in terms of global combustion metrics. In the case of OME1, a shorter liquid length, but longer ignition delay time and flame lift-off length were observed. However, in terms of soot formation, a big difference between paraffinic and oxygenated fuels could be appreciated. While paraffinic fuels did not show any significant decrease of soot formation when compared to diesel fuel, soot formed by OME1 and OMEx was below the detection threshold in all tested conditions.

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NISHIOKA, Daichi, Mariko NAKAMURA, Jun HAYASHI, and Fumiteru AKAMATSU. "An Experimental Study of Coaxial Jet Spray Flame Structure and Soot Formation under High Pressure(Thermal Engineering)." Transactions of the Japan Society of Mechanical Engineers Series B 76, no. 768 (2010): 1297–304. http://dx.doi.org/10.1299/kikaib.76.768_1297.

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23

Patel, Chetankumar, Camille Hespel, Tung Lam Nguyen, Fabrice Foucher, and Christine Mounaïm-Rousselle. "Effect of exhaust gas recirculation composition on soot in ECN spray A conditions." Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 75 (2020): 34. http://dx.doi.org/10.2516/ogst/2020028.

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Due to its strong impact on health, particulate matter is increasingly regulated by government emission standards for vehicles. As one of the sources of particulate matter is the soot produced by internal combustion engines, it remains a challenge to improve advanced combustion modes to reduce it. There is still, however, some lack of understanding about the formation and oxidation processes of soot, especially in “realistic” conditions, such as for example at high temperature and pressure conditions with or without the presence of exhaust gases. The objective of this study is to investigate soot formation in the case of n-Dodecane spray flames at conventional Diesel engine conditions generated in the New One Shot Engine by using diffused back-illumination extinction with different CO2 and water vapour contents. It was found that CO2 addition reduces the soot mass fraction if its volumetric concentration in ambient mixtures is at least 4.5% while 1% of water is sufficient to significantly reduce the soot mass fraction. The impact of the ambient mixture obtained in ECN spray A pre-burn vessels was also investigated to assess the accuracy against soot measurements available in the literature.

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Hassouni, K., F. Mohasseb, F. Bénédic, G. Lombardi, and A. Gicquel. "Formation of soot particles in Ar/H2/CH4 microwave discharges during nanocrystalline diamond deposition: A modeling approach." Pure and Applied Chemistry 78, no. 6 (January 1, 2006): 1127–45. http://dx.doi.org/10.1351/pac200678061127.

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Homogenous mechanism of soot formation in moderate-pressure Ar/CH4/H2 microwave discharges was analyzed with the help of kinetics modeling of the thermally nonequilibrium plasmas. Two main reaction mechanisms based on either neutral molecular growth and condensation reaction nucleation process were considered. These mechanisms were incorporated in a numerical model that solves for the plasma species and energy equations under a quasi-uniform plasma assumption. This enabled us to estimate the plasma species density and temperature along with the nucleation rate at different discharge conditions. The results showed that soot particles might form at significant density values by both neutral and ionic mechanisms. Their formation mainly takes place at the discharge edges where the temperature level favors the development of large molecular edifices. Simulations showed that the formation of soot is unlikely to happen in the bulk of the discharge where the gas temperature is high and the large molecular hydrocarbon (HC) cannot form at significant concentrations.

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25

Balthasar, M., F. Mauss, M. Pfitzner, and A. Mack. "Implementation and Validation of a New Soot Model and Application to Aeroengine Combustors." Journal of Engineering for Gas Turbines and Power 124, no. 1 (October 1, 2000): 66–74. http://dx.doi.org/10.1115/1.1377596.

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The modeling of soot formation and oxidation under industrially relevant conditions has made significant progress in recent years. Simplified models introducing a small number of transport equations into a CFD code have been used with some success in research configurations simulating a reciprocating diesel engine. Soot formation and oxidation in the turbulent flow is calculated on the basis of a laminar flamelet library model. The gas phase reactions are modeled with a detailed mechanism for the combustion of heptane containing 89 species and 855 reactions developed by Frenklach and Warnatz and revised by Mauss. The soot model is divided into gas phase reactions, the growth of polycyclic aromatic hydrocarbons (PAH) and the processes of particle inception, heterogeneous surface growth, oxidation, and condensation. The first two are modeled within the laminar flamelet chemistry, while the soot model deals with the soot particle processes. The time scales of soot formation are assumed to be much larger than the turbulent time scales. Therefore rates of soot formation are tabulated in the flamelet libraries rather than the soot volume fraction itself. The different rates of soot formation, e.g., particle inception, surface growth, fragmentation, and oxidation, computed on the basis of a detailed soot model, are calculated in the mixture fraction/scalar dissipation rate space and further simplified by fitting them to simple analytical functions. A transport equation for the mean soot mass fraction is solved in the CFD code. The mean rate in this transport equation is closed with the help of presumed probability density functions for the mixture fraction and the scalar dissipation rate. Heat loss due to radiation can be taken into account by including a heat loss parameter in the flamelet calculations describing the change of enthalpy due to radiation, but was not used for the results reported here. The soot model was integrated into an existing commercial CFD code as a post-processing module to existing combustion CFD flow fields and is very robust with high convergence rates. The model is validated with laboratory flame data and using a realistic three-dimensional BMW Rolls-Royce combustor configuration, where test data at high pressure are available. Good agreement between experiment and simulation is achieved for laboratory flames, whereas soot is overpredicted for the aeroengine combustor configuration by 1–2 orders of magnitude.

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Kong, Song-Charng, Yong Sun, and Rolf D. Rietz. "Modeling Diesel Spray Flame Liftoff, Sooting Tendency, and NOx Emissions Using Detailed Chemistry With Phenomenological Soot Model." Journal of Engineering for Gas Turbines and Power 129, no. 1 (December 15, 2005): 245–51. http://dx.doi.org/10.1115/1.2181596.

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A detailed chemistry-based CFD model was developed to simulate the diesel spray combustion and emission process. A reaction mechanism of n-heptane is coupled with a reduced NOx mechanism to simulate diesel fuel oxidation and NOx formation. The soot emission process is simulated by a phenomenological soot model that uses a competing formation and oxidation rate formulation. The model is applied to predict the diesel spray lift-off length and its sooting tendency under high temperature and pressure conditions with good agreement with experiments of Sandia. Various nozzle diameters and chamber conditions were investigated. The model successfully predicts that the sooting tendency is reduced as the nozzle diameter is reduced and/or the initial chamber gas temperature is decreased, as observed by the experiments. The model is also applied to simulate diesel engine combustion under premixed charge compression ignition (PCCI) conditions. Trends of heat release rate, NOx, and soot emissions with respect to EGR levels and start-of-injection timings are also well predicted. Both experiments and models reveal that soot emissions peak when the start of injection (SOI) occurs close to TDC. The model indicates that low soot emission at early SOI is due to better oxidation while low soot emission at late SOI is due to less formation. Since NOx emissions decrease monotonically with injection retardation, a late injection scheme can be utilized for simultaneous soot and NOx reduction for the engine conditions investigated in this study.

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27

Tang, Yuanzhi, Diming Lou, Chengguan Wang, Piqiang Tan, Zhiyuan Hu, Yunhua Zhang, and Liang Fang. "Joint Study of Impingement Combustion Simulation and Diesel Visualization Experiment of Variable Injection Pressure in Constant Volume Vessel." Energies 13, no. 23 (November 25, 2020): 6210. http://dx.doi.org/10.3390/en13236210.

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In this paper, the visualization experiments of spray, ignition, and combustion of diesel under variable injection pressure (from 90 to 130 MPa) were studied by using a constant volume vessel and impinging combustion plate system. With the development of the down-sizing of diesel engines, the wall impinging combustion without liquid spray collision will be the research focus in the diesel engine combustion process. The flame natural luminosity in the experiment represents the soot formation of diesel combustion. Besides, the detailed information of diesel spray mixing combustion was obtained by using the CFD (Computational Fluid Dynamics) simulation of alternative fuels in CONVERGE™. The specific conclusions are as follows. The high velocity of the spray under the higher injection pressure could reduce the low-mixing area near the impinging wall by entraining more air. Under higher injection pressure in simulation, the gas diffused more extensively, and more heat was released after combustion. Therefore, a large amount of soot formed in the early stage of combustion and then oxidized in high-temperature regions, which agreed with the conclusions in the experiments. Under the influence of the superposition of image pixels of the flame, the change of soot generation with injection pressure is smaller than the actual value, so the visualization experiment can be used as the basis of combustion prediction.

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28

Demazeau, Gérard, Hubert Huppertz, José A. Alonso, Rainer Pöttgen, Emilio Moran, and J. Paul Attfield. "Materials Chemistry under High Pressures – Some Recent Aspects." Zeitschrift für Naturforschung B 61, no. 12 (December 1, 2006): 1457–70. http://dx.doi.org/10.1515/znb-2006-1201.

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Among the thermodynamic parameters governing the preparation of novel materials, temperature (T) and pressure (p) play an important role. In Materials Chemistry, the synthesis of materials needs energy in order to enhance the diffusion of atoms to the equilibrium positions required by the specific structure and to induce the formation of chemical bonds. The comparison of the energy conveyed by both parameters (p and T) underlines that high pressures can be associated - in liquid or solid media - with soft processes. Consequently this paper describes the main factors induced by the parameter pressure that are able to support new structural forms or generate novel materials. Two different approaches are presented: (i) for a given composition with characteristic chemical bonds, high pressures can induce structural transformations, (ii) high pressures lead to the formation of novel materials from different precursors through the formation of new chemical bonds.

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29

Aneggi, Eleonora, and Alessandro Trovarelli. "Potential of Ceria-Zirconia-Based Materials in Carbon Soot Oxidation for Gasoline Particulate Filters." Catalysts 10, no. 7 (July 9, 2020): 768. http://dx.doi.org/10.3390/catal10070768.

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ZrO2 and Ce0.8Zr0.2O2 mixed oxides were prepared and tested in the oxidation of carbon soot at different oxygen partial pressures and degrees of catalyst/soot contact to investigate their activity under typical gasoline direct injection (GDI) operating conditions. Under reductive atmospheres, generation of oxygen vacancies occurs in Ce0.8Zr0.2O2, while no reduction is observed on ZrO2. Both materials can oxidize carbon under high oxygen partial pressures; however, at low oxygen partial pressures, the presence of carbon can contribute to the reduction of the catalyst and formation of oxygen vacancies, which can then be used for soot oxidation, increasing the overall performance. This mechanism is more efficient in Ce0.8Zr0.2O2 than ZrO2, and depends heavily on the interaction and the degree of contact between soot and catalyst. Thus, the ability to form oxygen vacancies at lower temperatures is particularly helpful to oxidize soot at low oxygen partial pressures, and with higher CO2 selectivity under conditions typically found in GDI engine exhaust gases.

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30

Morris, D. E., K. K. Singh, and A. P. B. Sinha. "A novel stable solid formed by C60 + oxygen at high P(O2)." Journal of Materials Research 8, no. 9 (September 1993): 2273–76. http://dx.doi.org/10.1557/jmr.1993.2273.

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We report the formation of a novel solid form of carbon + oxygen. Exposure of C60 to high oxygen pressure [P(O2) ≍ 100 MPa] for several days at slightly above ambient temperature results in absorption of significant amounts of oxygen (up to ∼48% by weight after 3 days). X-ray diffraction measurements showed that the C60 pellets had become amorphous. Although part of the added weight is slowly lost in flowing oxygen at ambient pressure and temperature, most remains up to at least 100 °C. Heating in flowing He at 200 °C brought the weight back to near the original value. The reaction appears to be specific to C60 since the amorphous outgassed material had lost the capacity to absorb oxygen at high P(O2), and the oxygen absorption effect was absent in powdered graphite and in commercial amorphous carbon. The Raman spectrum differs from those of C60, soot, amorphous carbon, graphite, and diamond.

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31

Wang, Xiangang, Zuohua Huang, Wu Zhang, Olawole Abiola Kuti, and Keiya Nishida. "Effects of ultra-high injection pressure and micro-hole nozzle on flame structure and soot formation of impinging diesel spray." Applied Energy 88, no. 5 (May 2011): 1620–28. http://dx.doi.org/10.1016/j.apenergy.2010.11.035.

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32

Wang, X. K., X. W. Lin, M. Mesleh, M. F. Jarrold, V. P. Dravid, J. B. Ketterson, and R. P. H. Chang. "The effect of hydrogen on the formation of carbon nanotubes and fullerenes." Journal of Materials Research 10, no. 8 (August 1995): 1977–83. http://dx.doi.org/10.1557/jmr.1995.1977.

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A novel method to synthesize “clean” carbon nanotubes with relatively high yield in a hydrogen arc discharge has been developed. The quality and yield of the tubes depend sensitively on the gas pressure in the arc discharge. Sharp, open-ended nanotubes with clear lattice fringes at the edges and empty interiors have been observed. The existence of these frozen-open-ended tubes as part of nanotube-bundles provides evidence for an open-ended growth model for nanotubes. Using time of flight mass spectrometry, it was found that fullerenes, such as C60 and C70, are almost absent from the soot collected in the hydrogen arc discharge. The effect of hydrogen on the formation of fullerenes, both in the laboratory and in space, will be discussed.

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33

Wissink, Martin, and Rolf Reitz. "The role of the diffusion-limited injection in direct dual fuel stratification." International Journal of Engine Research 18, no. 4 (August 20, 2016): 351–65. http://dx.doi.org/10.1177/1468087416661867.

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Low-temperature combustion offers an attractive combination of high thermal efficiency and low NO x and soot formation at moderate engine load. However, the kinetically-controlled nature of low-temperature combustion yields little authority over the rate of heat release, resulting in a tradeoff between load, noise, and thermal efficiency. While several single-fuel strategies have achieved full-load operation through the use of equivalence ratio stratification, they uniformly require retarded combustion phasing to maintain reasonable noise levels, which comes at the expense of thermal efficiency and combustion stability. Previous work has shown that control over heat release can be greatly improved by combining reactivity stratification in the premixed charge with a diffusion-limited injection that occurs after low-temperature heat release, in a strategy called direct dual fuel stratification. While the previous work has shown how the heat release control offered by direct dual fuel stratification differs from other strategies and how it is enabled by the reactivity stratification created by using two fuels, this paper investigates the effects of the diffusion-limited injection. In particular, the influence of fuel selection and the pressure, timing, and duration of the diffusion-limited injection are examined. Diffusion-limited injection fuel type had a large impact on soot formation, but no appreciable effect on performance or other emissions. Increasing injection pressure was observed to decrease filter smoke number exponentially while improving combustion efficiency. The timing and duration of the diffusion-limited injection offered precise control over the heat release event, but the operating space was limited by a tradeoff between NO x and soot.

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Nakakita, K., K. Akihama, W. Weissman, and J. T. Farrell. "Effect of the hydrocarbon molecular structure in diesel fuel on the in-cylinder soot formation and exhaust emissions." International Journal of Engine Research 6, no. 3 (June 1, 2005): 187–205. http://dx.doi.org/10.1243/146808705x7400.

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Evaluations of diesel fuel effects on combustion and exhaust emissions in single-cylinder direct-injection diesel engines led to the unexpected result that a Swedish ‘class 1’ fuel generated more particulate matter (PM) than a fuel denoted ‘improved’, even though ‘class 1’ fuel had much lower distillation temperatures, aromatic concentration, sulphur level, and density than the ‘improved’ fuel. Little differences were observed in the combustion characteristics between these fuels, but detailed compositional analyses showed that ‘class 1’ fuel contains higher levels of cyclic and/or branched paraffins. Subsequent investigations in a laboratory flow reactor showed that ‘class 1’ fuel produces more soot precursors such as benzene and acetylene than the ‘improved’ fuel. In addition, experiments in a low-pressure laminar flame apparatus and shock tube with model (single-molecule) paraffin fuels showed that isoparaffins and cycloparaffins generate more soot precursors and soot than n-paraffins do. These results strongly suggested that the effect of molecular structure on exhaust PM formation should be more carefully examined. Therefore, a new series of investigations were performed to examine exhaust emissions and combustion characteristics in single-cylinder engines, with well-characterized test fuels having carefully controlled molecular composition and conventional distillation characteristics and cetane numbers (CNs). These investigations revealed the following. Firstly, under low and medium loads, cycloparaffins (naphthenes) have a higher PM formation tendency than isoparaffins and n-paraffins. Under high-load conditions, however, the paraffin molecular structure has a very small effect. Secondly, a highly n-paraffinic fuel does not yield PM reductions as high as expected, due to its high CN and corresponding shorter ignition lag, which initiates combustion under a state of insufficient fuel-air mixing. This finding was corroborated by laser-induced incandescence analyses. Thirdly, the lowest PM emissions were observed with a paraffinic fuel containing 55 per cent isoparaffins and 39 per cent n-paraffins. Fourthly, aromatics give higher soot and PM levels than paraffins do at high and medium load conditions. Smaller differences are observed at lower speeds and loads. Fifthly, the best fit to the PM emissions was obtained with an equation containing the regression variables CN, aromatic rings, and naphthene rings. This expression of the fuel effects in chemical terms allows well-to-wheel analyses of refining and vehicle impacts resulting from molecularly based fuel changes.

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Senda, J., and H. G. Fujimoto. "Multidimensional Modeling of Impinging Sprays on the Wall in Diesel Engines." Applied Mechanics Reviews 52, no. 4 (April 1, 1999): 119–38. http://dx.doi.org/10.1115/1.3098930.

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This article summarizes model analysis of the dispersion process of a Diesel spray on the wall surface in order to simulate the spray-wall interaction process in Diesel engines. The mixture formation process near the wall of the piston cavity affects the combustion process and the hydrocarbon or soot formation process through the quenching of the mixture and flame at the wall surface. In particular, mixture burning occurs mainly near the cavity wall through the whole combustion period in the case of high pressure fuel injection. In this article, representative modeling approaches on spray-wall interaction process including the film flow formation are summarized briefly. Then, our models of spray impingement for low/high-temperature models including the process of fuel film formation, film breakup, wall-drop/film heat transfer, and droplet breakup owing to the solid-liquid interface boiling are introduced with the comparison of experimental results. This review article includes 83 references.

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Liu, Yongfeng, Jianwei Yang, Jianmin Sun, Aihua Zhu, and Qinghui Zhou. "A Phenomenological Model for Prediction Auto-Ignition and Soot Formation of Turbulent Diffusion Combustion in a High Pressure Common Rail Diesel Engine." Energies 4, no. 6 (June 3, 2011): 894–912. http://dx.doi.org/10.3390/en4060894.

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Corcione, F. E., S. S. Merola, and B. M. Vaglieco. "Evaluation of temporal and spatial distribution of nanometric particles in a diesel engine by broadband optical techniques." International Journal of Engine Research 3, no. 2 (April 1, 2002): 93–101. http://dx.doi.org/10.1243/14680870260127882.

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In the last few years, there has been an increasing concern about the emissions of ultrafine particles in the atmosphere. A detailed study of the formation and oxidation of these particles in the environment of the diesel engine cylinder presents many experimental difficulties due to the high temperatures, pressures and extremely reactive intermediate species. To allow investigation of the different phases of the diesel combustion process, high temporal and spatial resolution optical techniques were applied in the optically accessible chamber of a diesel engine at fixed engine speed and air-fuel ratio. Simultaneous extinction, scattering and flame chemiluminescence measurements from the ultraviolet to the visible region were carried out in order to study the diesel combustion process from the soot inception to the formation of soot particles, through the growth of their precursors. These species were characterized as carbonaceous nanometric structures and their sizes were evaluated by the Mie theory.

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Riesmeier, E., S. Honnet, and N. Peters. "Flamelet Modeling of Pollutant Formation in a Gas Turbine Combustion Chamber Using Detailed Chemistry for a Kerosene Model Fuel." Journal of Engineering for Gas Turbines and Power 126, no. 4 (October 1, 2004): 899–905. http://dx.doi.org/10.1115/1.1787507.

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Combustion and pollutant formation in a gas turbine combustion chamber is investigated numerically using the Eulerian particle flamelet model. The code solving the unsteady flamelet equations is coupled to an unstructured computational fluid dynamics (CFD) code providing solutions for the flow and mixture field from which the flamelet parameters can be extracted. Flamelets are initialized in the fuel-rich region close to the fuel injectors of the combustor. They are represented by marker particles that are convected through the flow field. Each flamelet takes a different pathway through the combustor, leading to different histories for the flamelet parameters. Equations for the probability of finding a flamelet at a certain position and time are additionally solved in the CFD code. To model the chemical properties of kerosene, a detailed reaction mechanism for a mixture of n-decane and 1,2,4-trimethylbenzene is used. It includes a detailed NOx submechanism and the buildup of polycyclic aromatic hydrocarbons up to four aromatic rings. The kinetically based soot model describes the formation of soot particles by inception, further growth by coagulation, and condensation as well as surface growth and oxidation. Simulation results are compared to experimental data obtained on a high-pressure rig. The influence of the model on pollutant formation is shown, and the effect of the number of flamelets on the model is investigated.

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Shavelkina, Marina B., Ravil Kh Amirov, Tatyana I. Borodina, Viktor I. Kiselev, Tatiana B. Shatalova, and Kamille S. Rabadanov. "FORMATION OF NANO STRUCTURES IN RESULT OF HOMOGENOUS NUCLEATION OF CARBON OBTAINED IN THERMAL PLASMA UNDER ATMOSPHERIC PRESSURE." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 59, no. 8 (July 17, 2018): 27. http://dx.doi.org/10.6060/tcct.20165908.34y.

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Thermal plasma processing of carbon sources using a plasma jet with high heat capacity is one of the most promising methods for the synthesis of new materials. This paper describes the low-temperature deposition of carbon nanomaterials by remote plasma-enhanced chemical vapor deposition (PECVD) in the absence of catalysts. The remote PECVD process differs from conventional and direct PECVD process in two ways: (a) only a subset of the process reactants and/or diluents are directly plasma excited; and (b) thin film deposition takes place on a substrate that is outside of the plasma glow region. In conventional CVD methods, carbon is produced from the decomposition of carbon sources such as hydrocarbons, carbon monoxide, alcohols, and so on, over a metal catalyst. The unavoidable metal species remaining in carbon nanomaterials would lead to obvious disadvantages for property characterization and application exploration. Despite sustained efforts, it is still an intractable problem to remove metal catalysts completely from carbon nanomaterials samples without introducing defects and contaminations. Good reactor design allowed to overcome problems of chemical and structural purity, and poor process robustness in terms of phase composition of product from run to run. For the synthesis of graphene materials, carbon black, carbon nanotubes, nanowires we used the thermal plasma generator which is a high current divergent anode-channel DC plasma torch. The experiment involved a simultaneous input of hydrocarbons (methane, propane, butane, acetylene) with the plasma forming gas (helium, argon, nitrogen) into the plasma torch, wherein heating and decompositions occurred in the plasma jet and in the region of the arc discharge, followed by condensation of the synthesis product on metallic surfaces. The deposition rate was varied with distance from the plasma. Consumption of carbon source, plasma forming gas and plasma torch power were changed independently from each other. For the experimental conditions the electric power of plasma torch was set up to 40 kW. Regularities of formation of carbon thread-like nanostructures and graphene in the course of hydrocarbons pyrolysis in thermal plasma without participation of catalytic particles were studied by means of electron microscopy, X-ray diffraction, IR-spectrometry and thermogravimetry. Depending on the pyrolytic synthesis parameters, different proportions of crystal carbon and soot may be obtained. It has been demonstrated that the phase composition is varied by hydrocarbons flow rate, plasma forming gas pressure and dc plasma torch power. It has been established through the experiments that carbon nucleation is volumetric and proceeds according to the model of explosive soot formation.

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Senyut, V. T. "Sintering of composite materials for tool appointment, based on impact diamonds, under high pressure and temperatures." Proceedings of the National Academy of Sciences of Belarus, Physical-Technical Series 66, no. 1 (April 2, 2021): 47–57. http://dx.doi.org/10.29235/1561-8358-2021-66-1-47-57.

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The article presents the results of a study of composite materials based on diamond-lonsdaleite abrasive (DLA) and various binders (Fe–Ti mechanocomposite, silicon carbide SiC). A metal-matrix composite material with a multimodal nano- and microlevel structure, characterized by increased adhesion of diamond grains to the binder, is obtained on the basis of impact diamonds and a Fe–Ti nano-mechanical composite. It is shown that the use of impact diamonds in comparison with synthetic diamonds makes it possible to reduce the pressure of thermobaric treatment by 30–50 % at the same sintering temperatures. The use of Fe–Ti–DLA composites in the process of magnetic-abrasive polishing (MAP) makes it possible to increase the removal rate of material based on silicon by 1.5–2 times and reduce the processing time by 30 % compared to ferroabrasive powder (FAP) based on synthetic diamonds. The effect of adding of silicon carbide on the process of obtaining a superhard composite material impact diamond – SiC is investigated. It is found that adding of SiC helps to reduce the defectiveness of the material and increase the homogeneity of its structure in comparison with the material without adding of a binder. In this case, an increase in the content of SiC and Si also leads to an inversion of the structure type of the superhard composite from polycrystalline to matrix. It is found that the additional use of amorphous soot and boron affects the refinement of the matrix structure of the composite material due to the formation of boron carbide and secondary finely dispersed silicon carbide.

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Liu, Fei, Jun Song Chen, and Kai Wen Li. "Experimental Analysis of Mechanical Properties of High Organic Soft Clay at Different Depths." Advanced Materials Research 1056 (October 2014): 52–57. http://dx.doi.org/10.4028/www.scientific.net/amr.1056.52.

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In this study, with regard to the differences of formation stage and physicochemical properties for different high organic soft clay layers, a series of laboratory tests have been carried out to evaluate the mechanical properties of high organic soft clay in Northeast China. The conventional high-pressure consolidation and strain-controlled triaxial shear tests have been carried out to measure the compression and shear strength of high organic soft clay which formed in different ages. Furthermore, the comparisons of stress-strain relations between undisturbed and remoulded high organic soft clay samples under the confining pressure of 300kPa reveal the significant differences in compression and shear strengths of high organic soft clay at different depths, which can be interpreted by the differences in the degree of decomposition of the soil. The test results show that the degree of decomposition of high organic soft clay greatly depend on its formation stage at different depths, which is deemed to determine the mechanical properties. This study will provide a good guide to civil engineers on the constructions of the foundation.

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Kim, Ho Young, Jun Cong Ge, and Nag Jung Choi. "Effects of Fuel Injection Pressure on Combustion and Emission Characteristics under Low Speed Conditions in a Diesel Engine Fueled with Palm Oil Biodiesel." Energies 12, no. 17 (August 24, 2019): 3264. http://dx.doi.org/10.3390/en12173264.

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In this study, the effect of injection pressure on combustion and emission characteristics was evaluated on a common rail direct injection diesel engine fueled with palm oil biodiesel. Recently, many studies have been conducted to utilize biodiesel produced from various sources to prevent environmental pollution and the depletion of petroleum resources. The oxygen content and high cetane number of biodiesel can reduce the production of exhaust pollutants by improving the combustion, but its high viscosity deteriorates the atomization of the injected fuel. Particularly at low engine speed conditions like idle, poor atomization and low airflow in the cylinder deteriorates the combustion efficiency. Increasing the fuel injection pressure is one of the effective methods to improve the atomization of biodiesel without mechanical modification of the current diesel engine. In this study, combustion characteristics and emission levels of pollutants were measured by varying the fuel injection pressure applying palm oil biodiesel. As a result, it was confirmed that increasing the injection pressure to apply palm oil biodiesel at low engine speed can reduce ignition delay and improve combustion efficiency so that nitrogen oxides (NOx) is increased but soot formation is reduced. Carbon monoxide (CO) and hydrocarbon (HC) are slightly reduced but these are increased again when using 100% palm oil biodiesel. The increased NOx due to increased injection pressure can be reduced by applying exhaust gas recirculation (EGR).

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Nishida, Keiya, Jingyu Zhu, Xianyin Leng, and Zhixia He. "Effects of micro-hole nozzle and ultra-high injection pressure on air entrainment, liquid penetration, flame lift-off and soot formation of diesel spray flame." International Journal of Engine Research 18, no. 1-2 (February 2017): 51–65. http://dx.doi.org/10.1177/1468087416688805.

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Böhm, H., H. Jander, and D. Tanke. "PAH growth and soot formation in the pyrolysis of acetylene and benzene at high temperatures and pressures: Modeling and experiment." Symposium (International) on Combustion 27, no. 1 (January 1998): 1605–12. http://dx.doi.org/10.1016/s0082-0784(98)80570-5.

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Yang, Dong Bo, Liu Li, and Luo Lin. "Experiment Research of the Influence of Bio-Diesel on the Number and Size Distribution of PM Emissions of Diesel Engine." Advanced Materials Research 953-954 (June 2014): 1325–31. http://dx.doi.org/10.4028/www.scientific.net/amr.953-954.1325.

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A comparative study has been done on a diesel engine, which was equipped with high pressure common rail system. Diesel, soybean oil methyl ester and waste cooking oil methyl ester were test to analyze the influence of bio-diesel on the number and size distribution of PM emissions. The results showed that bio-diesel can significantly reduce the dry soot emission due to the containing of oxygen and the advantage of components, which results the decrease of accumulation particle emissions and total weight emissions. The size distribution of bio-diesel PM emissions becomes unimodal. The density and viscosity of bio-diesel are greater than that of diesel, which results in a significant increase of the number of nucleation particles due to the disadvantages of injection and mixture formation.

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Hu, Deng, Zhaoxia Huang, Jialiang Huang, Tao Deng, Zi Xiao Ye, and Jinyu Fan. "Emission Character Study on temperature Combustion Performance of Electronic Controlled Diesel Engine Mixed with Butanol." E3S Web of Conferences 118 (2019): 02028. http://dx.doi.org/10.1051/e3sconf/201911802028.

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In this paper, through the electromechanical control modification of 4190 ZLC-2 diesel, the electronic fuel injection model is established by AMESim simulation software, and the high pressure circulation model of butanol/diesel dual fuel engine is established by AVL-FIRE software, the appropriate initial parameters module and corresponding boundary conditions are set. At the condition of low-temperature combustion through exhaust gas recirculation (EGR), in the optimization scheme studying the influence of butan blending ratio and EGR rate on diesel engine emissions. The result shows that the addition of butanol can improve the low temperature combustion, reducing the formation of CO and soot. The introduction of EGR can achieve low temperature combustion and significantly reduce NO emissions. The optimal parameter set for parameter matching is obtained: B20/EGR12.5 %.

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YOKOTA, Haruyuki, Takeyuki KAMIMOTO, and Haruki KOBAYASHI. "A study of diesel spray and flame by an image processing technique. (1st. Rep. Effects of high pressure injection on spray characteristics and soot formation process)." Transactions of the Japan Society of Mechanical Engineers Series B 54, no. 499 (1988): 741–48. http://dx.doi.org/10.1299/kikaib.54.741.

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Singh, Ajaypal, and Hosahalli Ramaswamy. "Effect of High Pressure Processing on Color and Textural Properties of Eggs." Journal of Food Research 2, no. 4 (June 19, 2013): 11. http://dx.doi.org/10.5539/jfr.v2n4p11.

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Effect of high pressure processing (HPP) on physicochemical characteristics like color and texture of whole liquid egg (WLE), egg white (EW) and egg yolk (EY) were evaluated. A full factorial design involving several pressure levels (600-900 MPa) and treatment time (0-15 min) was employed for this study and the high pressure treatment were given in a temperature and pressure controlled pilot scale HP unit. HPP caused significant changes in various physic-chemical properties in various egg components. Use of pressure levels > 600 MPa resulted in formation of solid gels for all components of eggs. Pressure induced gels were soft and highly elastic. Hardness and cohesiveness of all egg components were found to increase (p < 0.05) with increase in treatment intensity, and increase in EY was higher than in other egg components. The springiness of WLE increased with pressure and treatment time and were higher than in EW and EY. Color changes as indicated by the total color difference (?E) showed a significant (p < 0.05) increase with an increase in pressure level and treatment time.

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Majid, Naeimavi, Khazali Fereydoon, Abdideh Mohammad, and Zohreh Saadati. "Experimental Study of the Contamination Effects of Gachsaran Formation Fluid on the Heavy-weight Drilling Fluid." Open Petroleum Engineering Journal 11, no. 1 (October 30, 2018): 107–17. http://dx.doi.org/10.2174/1874834101811010107.

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Introduction:Gachsaran Formation is the cap rock of Asmari oil reservoir located in southwestern of Iran. The formation consists of halite, anhydrite, and tachyhydrite, The most important feature of this formation is the presence of high-pressure fluid.Method:Drilling companies have to use heavy-weighted mud to drill the high-pressure formation. Sometimes the weight of drilling fluid is used, up to 2.65(gr/cm3). Although heavy-weight mud prevents formation fluid to flow into the well, it is difficult to maintain and control its properties. If the hydrostatic pressure is insufficient, the formation connate fluid penetrates into the drilling mud and contaminates it.Result:The study found that the symptoms of this contamination lead to an increase in calcium, magnesium, carbonates, and bicarbonates levels, as well as a decrease in pH. The drilling fluid rheology also affected by the contamination.Discussion:Then, method of curing this event is discussed. Prevention, the best treatment for this event was introduced. It was also found that, as soon as contamination signs appear, immediately increase the drilling fluid weight as much as possible, and then adjust the pH between 10.5 and 11.5. The maintain method described is continued until section drilling ends.

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Zubel, Marius, Tamara Ottenwälder, Benedikt Heuser, and Stefan Pischinger. "Combustion system optimization for dimethyl ether using a genetic algorithm." International Journal of Engine Research 22, no. 1 (May 24, 2019): 22–38. http://dx.doi.org/10.1177/1468087419851577.

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Dimethyl ether is a gaseous fuel which can easily be liquefied under moderate pressures. Its high reactivity makes it suitable for combustion in a compression ignition engine, and due to the high oxygen content, its combustion is virtually free of soot. The high oxygen content and low density of dimethyl ether lead to a lower volumetric heating value compared to Diesel fuel. Therefore, the hydraulic flow rates of the injectors have to be increased with larger nozzle holes. The influence of larger nozzle holes on the dimethyl ether spray formation and ignition are presented in this article. Experimental investigations were conducted at a constant-pressure vessel with optical access and with a single-cylinder research engine. Subsequently, a numerical optimization of the piston bowl and injector nozzle has been carried out. A very fast air/fuel mixture formation with dimethyl ether was observed, which leads to a lean combustion with small nozzle diameters. With increasing nozzle diameters, the combustion moves toward stoichiometric conditions and with very large diameters to rich combustion conditions. The ignition delay for small diameters is mostly dominated by the lean mixture, and for large diameters, the ignition delay is strongly influenced by cooling effects. For the optimization, the oxidation potential number was maximized, which proved suitable to simultaneously increase efficiency and reduce emissions. A conventional ω-shaped bowl and a step bowl have been optimized, and large bowl diameters were found to be beneficial for dimethyl ether combustion. Furthermore, nozzle diameters around 150 µm showed the most promising results. Compared to the dimethyl ether reference, the simulations with the optimized ω-shaped bowl showed a power increase of 2.7%. Experimentally, the optimized ω-shaped bowl in combination with the reference injector showed an efficiency increase by more than 1% at 2000 r/min full load compared to the dimethyl ether reference.

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Journal articles on the topic 'High pressure soot formation'

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