Articoli di riviste: "Combustions"

1

Yang, Xiaojian, e Guoming G. Zhu. "A control-oriented hybrid combustion model of a homogeneous charge compression ignition capable spark ignition engine". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 226, n. 10 (31 maggio 2012): 1380–95. http://dx.doi.org/10.1177/0954407012443334.

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To implement the homogeneous charge compression ignition combustion mode in a spark ignition engine, it is necessary to have smooth mode transition between the spark ignition and homogeneous charge compression ignition combustions. The spark ignition–homogeneous charge compression ignition hybrid combustion mode modeled in this paper describes the combustion mode that starts with the spark ignition combustion and ends with the homogeneous charge compression ignition combustion. The main motivation of studying the hybrid combustion mode is that the percentage of the homogeneous charge compression ignition combustion is a good parameter for combustion mode transition control when the hybrid combustion mode is used during the transition. This paper presents a control oriented model of the spark ignition–homogeneous charge compression ignition hybrid combustion mode, where the spark ignition combustion phase is modeled under the two-zone assumption and the homogeneous charge compression ignition combustion phase under the one-zone assumption. Note that the spark ignition and homogeneous charge compression ignition combustions are special cases in this combustion model. The developed model is capable of simulating engine combustion over the entire operating range, and it was implemented in a real-time hardware-in-the-loop simulation environment. The simulation results were compared with those of the corresponding GT-Power model, and good correlations were found for both spark ignition and homogeneous charge compression ignition combustions.

2

McGeehin, J., G. S. Burr, G. Hodgins, S. J. Bennett, J. A. Robbins, N. Morehead e H. Markewich. "Stepped-Combustion 14C Dating of Bomb Carbon in Lake Sediment". Radiocarbon 46, n. 2 (2004): 893–900. http://dx.doi.org/10.1017/s0033822200035931.

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In this study, we applied a stepped-combustion approach to dating post-bomb lake sediment from north-central Mississippi. Samples were combusted at a low temperature (400 °) and then at 900 °. The CO2 was collected separately for both combustions and analyzed. The goal of this work was to develop a methodology to improve the accuracy of 14C dating of sediment by combusting at a lower temperature and reducing the amount of reworked carbon bound to clay minerals in the sample material. The 14C fraction modern results for the low and high temperature fractions of these sediments were compared with well-defined 137Cs determinations made on sediment taken from the same cores. Comparison of “bomb curves” for 14C and 137Cs indicate that low temperature combustion of sediment improved the accuracy of 14C dating of the sediment. However, fraction modern results for the low temperature fractions were depressed compared to atmospheric values for the same time frame, possibly the result of carbon mixing and the low sedimentation rate in the lake system.

3

MAEDA, Shinichi, Isshu YOSHIKI, Shoichiro KANNO, Keita TOMITA e Tetsuro OBARA. "Occurrence conditions for unsteady combustions in shock-induced combustions around spherical projectiles". Transactions of the JSME (in Japanese) 83, n. 852 (2017): 17–00019. http://dx.doi.org/10.1299/transjsme.17-00019.

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Wang, Jian Ying, e Xi Lin Dong. "Experimental Study on Radiant Heat of Market Shelf Fire Decayed by High-Pressure Water Mist System". Advanced Materials Research 518-523 (maggio 2012): 3699–702. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.3699.

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Experimental study on radiant heat of market shelf fire depressed by high-pressure water mist system was carried out. The experiment researched on typical burning parts and combustions of places like market, and chosen experimental combustion components. The results show that the concentrate spray of high-pressure water mist system can decay the radiant heat of fire shelf effectively. The higher the spray pressure of the system, the faster the decay rate of radiation heat.

5

Abbondanza, Marco, Nicolò Cavina, Enrico Corti, Davide Moro, Fabrizio Ponti e Vittorio Ravaglioli. "Development of a Combustion Delay Model in the Control of Innovative Combustions". E3S Web of Conferences 197 (2020): 06013. http://dx.doi.org/10.1051/e3sconf/202019706013.

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In modern internal combustion engines the research for innovative solutions aimed at the simultaneous reduction of engine-out pollutants and fuel consumption requires synergies from different application areas: the thermo-fluid dynamic design of the combustion chamber, the study and production of specific components for air and fuel supply, the development of sensors and related methods of analyzing their signals to control the combustion process. The most promising innovative combustion methodologies suitable to achieve high efficiency and low emissions, commonly named Low Temperature Combustions (LTC), usually require sophisticated techniques for the management of the combustion phase. With respect to the combustion angular position control, directly performed in traditional spark ignition engines through the ignition from the spark plug and in compression ignition engines by the timing of fuel injection, the ignition mechanisms of LTC combustions are characterized by a high sensitivity to the thermal conditions of the combustion chamber which greatly modifies the angular position of the combustion, mainly due to the combination of high ignition delays and lean homogeneous mixture. Once the hardware of the air and fuel supply systems has been defined, it is therefore essential to ensure the correct management of the combustion phase. In this paper a model for the estimation of the delay between the start of injection and the start of combustion is presented. The model has been developed analyzing the experimental data from a modified cylinder of a diesel engine, fueled with gasoline, while the other three cylinders were still running with Diesel fuel. This solution represents a first step that allows analyzing the behavior of the combustion of gasoline in a Diesel engine, with the final goal to inject gasoline in all the engine cylinders. In particular, the approach used is similar to the one already applied in a traditional turbocharged gasoline engine, where the goal was to estimate the time delay between the spark firing and the start of combustion, mainly to detect the presence of undesired pre-ignition due to the presence of hot spots related to slightly knocking conditions. As it is well known, the role of the pilot injection is to reduce the ignition delay of the main injection. However, to significantly accelerate the ignition of the fuel injected with the main injection, it is necessary to burn a sufficient quantity of the fuel injected by the pilot before the Top Dead Center position (TDC). The application of this model has to allow the implementation of a feed-forward control to stabilize the whole combustion process and achieve the best conversion efficiency from energy to work, taking into account the operational constraints that must be satisfied to guarantee the integrity of the engine and the compliance with the homologation rules.

6

Ozturk, Suat. "A Numerical Investigation on Emissions of Partially Premixed Shale Gas Combustion". International Journal of Heat and Technology 38, n. 3 (15 ottobre 2020): 745–51. http://dx.doi.org/10.18280/ijht.380319.

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The adiabatic, turbulent, and partially premixed combustions of several shale gases and air in a co-axial type combustor are computationally examined under the effects of different equivalence ratios, inlet temperatures, flow rates, humidity ratios, pressure, oxid inlet temperatures and flow rates, and swirl velocities in this study. Shale gases are extracted from Barnette, New Albany, Fayetteville, and Haynesville areas of USA. ANSYS software is used for numerical calculations of combustion. Results show that the maximum NO emissions for Barnette, New Albany, Fayetteville, and Haynesville shale gas occur at the equivalence ratio of 1.42, 1.41, 1.4, and 1.39. The rising fuel inlet temperature increase NO and reduces CO emissions after 300 K. The increasing humidity ratio causes NO and CO mass fractions to decrease. The ascending pressure raises NO up to 4 bar and lowers CO emissions. The increasing oxid flow rate abates the mass fractions of both NO and CO. The rising swirl velocity escalates NO up to 15 m/s and decreases CO emissions for all the shale gas combustions.

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Bird, M. I., L. K. Ayliffe, L. K. Fifield, C. S. M. Turney, R. G. Cresswell, T. T. Barrows e B. David. "Radiocarbon Dating of “Old” Charcoal Using a Wet Oxidation, Stepped-Combustion Procedure". Radiocarbon 41, n. 2 (1999): 127–40. http://dx.doi.org/10.1017/s0033822200019482.

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We present results that validate a new wet oxidation, stepped-combustion procedure for dating “old” charcoal samples. An acid–base–wet oxidation (ABOX) pretreatment procedure has been developed that is used in place of the conventional acid-base-acid (ABA) pretreatment. Combustions and graphitizations are performed in a vacuum line that is insulated from the atmosphere by a second backing vacuum to eliminate the risk of atmospheric leakage into the line at any stage of the procedure. Combustions are performed at 3 temperatures (330 °, 630 ° and 850 °) with a graphite target produced from the CO2 evolved during each combustion step. In this way, the removal of any contamination can be monitored, and a high degree of confidence can be placed on the final age. The pretreatment, combustion, graphitization, and measurement blank for the procedure, based on the analysis of a “radiocarbon-dead” graphite, is 0.5 ± 0.5 μg C (1σ, n=14), equivalent to 0.04 ± 0.02 pMC or an “age” of approximately 60 ka for a 1 mg graphite target. Analyses of a “radiocarbon-dead” natural charcoal after ABOX pretreatment and stepped combustion suggest that the total blank (including contamination not removed by pretreatment) may be higher than for graphite, ranging up to 0.10 ± 0.02 pMC. Additional experiments confirm good agreement with accepted values for the international low-14C “New Kauri” standard (0.16–0.25 pMC). They also confirm excellent reproducibility, with 3 separate dates on different aliquots of a charcoal sample from Ngarrabullgan Cave (Queensland, Australia) ranging from 35.2 to 35.5 ka 14C BP. It is also demonstrated that the ABOX pretreatment, in conjunction with the new vacuum line described here, is able to remove contamination not removed by the conventional ABA pretreatment, suggesting that the technique can be used to produce reliable 14C dates on charcoal up to at least 50 ka.

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Sung, Yonmo, Seungtae Kim, Byunghwa Jang, Changyong Oh, Taeyun Jee, Soonil Park, Kwansic Park e Siyoul Chang. "Nitric Oxide Emission Reduction in Reheating Furnaces through Burner and Furnace Air-Staged Combustions". Energies 14, n. 6 (13 marzo 2021): 1599. http://dx.doi.org/10.3390/en14061599.

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In this study, a series of experiments were conducted on a testing facility and a real-scale furnace, for analyzing the nitric oxide (NO) emission reduction. The effects of the temperature, oxygen concentration, and amount of secondary combustion air were investigated in a single-burner combustion system. Additionally, the NO-reduction rate before and after combustion modifications in both the burner and furnace air-staged combustion were evaluated for a real-scale reheating furnace. The air-to-fuel equivalence ratio (λ) of individual combustion zones for the furnace was optimized for NO reduction without any incomplete combustion. The results indicated that the NO emission for controlling the λ of a single-zone decreased linearly with a decrease in the λ values in the individual firing tests (top-heat, bottom-heat, and bottom-soak zones). Moreover, the multi-zone control of the λ values for individual combustion zones was optimized at 1.13 (top-preheat), 1.0 (bottom-preheat), 1.0 (top-heat), 0.97 (bottom-heat), 1.0 (top-soak), and 0.97 (bottom-soak). In this firing condition, the modifications reduced the NO emissions by approximately 23%, as indicated by a comparison of the data obtained before and after the modifications. Thus, the combined application of burner and furnace air-staged combustions facilitated NO-emission reduction.

9

Li, Shou-Zhe, Yu-Long Niu, Shu-Li Cao, Jiao Zhang, Jialiang Zhang e Xuechen Li. "The effect of plasma discharge on methane diffusion combustion in air assisted by an atmospheric pressure microwave plasma torch". Journal of Physics D: Applied Physics 55, n. 23 (11 marzo 2022): 235203. http://dx.doi.org/10.1088/1361-6463/ac50cb.

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Abstract An atmospheric pressure air microwave plasma torch is employed to assist methane diffusion combustions using a combination of a combustor and burner. Experimentally, the effect of the air microwave plasma on combustion is investigated with respect to the flame morphology and the variation of gas components in the exhaust with the fuel equivalence ratio φ or the methane flow rate by comparing plasma-assisted combustion (PAC) and natural combustion (NC) without plasma application. The combustion degree of CH4 in PACs is found to be much enhanced in rich fuel combustion than in NC in both types of burners, which is measured by Fourier transformation infrared spectrometer (FTIR). In PACs, with the use of an air microwave plasma torch, the radicals originating from excitation, ionization, and dissociation of N2 and O2 and the high gas temperature induced in the plasma discharge play an important role in assisting the combustion.

10

Hesaaraki, Mahmoud, e Abdolrahman Razani. "Detonatlve travelling waves for combustions". Applicable Analysis 77, n. 3-4 (aprile 2001): 405–18. http://dx.doi.org/10.1080/00036810108840918.

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11

Lim, Xin Yi, Peter Yek Nai Yuh, Rock Keey Liew, Meng Choung Chiong, Cheng Tung Chong e Su Shiung Lam. "Biochar Waste Palm Shell for NO<sub>X</sub> Post-Emission Reduction in Biodiesel Combustion". Key Engineering Materials 914 (21 marzo 2022): 193–98. http://dx.doi.org/10.4028/p-6vk69g.

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Diesel combustions produce greenhouse and harmful gases bringing health hazards and negative impact to environment. This study produced biochar from waste palm shell and the biochar was further applied as fuel additive in biodiesel to reduce the nitric oxides emission. The biochar showed high fixed carbon content (85.8 wt%) and low ash content (2.0 wt%). Subsequently, the biodiesel post-combustion emission of NOX recorded a significant reduction up to 40.6% compared to without application of biochar. This study shows that the mixing of biochar in biodiesel is a potential approach to reduce the nitric oxide emission.

12

Silvagni, Giacomo, Vittorio Ravaglioli, Stefania Falfari, Fabrizio Ponti e Valerio Mariani. "Development of a Control-Oriented Ignition Delay Model for GCI Combustion". Energies 15, n. 17 (5 settembre 2022): 6470. http://dx.doi.org/10.3390/en15176470.

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Increasingly stringent pollutant emission limits and CO2 reduction policies are forcing the automotive industry toward cleaner and decarbonized mobility. The goal is to achieve carbon neutrality within 2050 and limit global warming to 2 °C (possibly 1.5 °C) with respect to pre-industrial levels as stated in both the European Green Deal and the Paris Agreement and further reiterated at the COP26. With the aim of simultaneously reducing both pollutants and CO2 emissions, a large amount of research is currently carried out on low-temperature highly efficient combustions (LTC). Among these advanced combustions, one of the most promising is Gasoline Compression Ignition (GCI), based on the spontaneous ignition of a gasoline-like fuel. Nevertheless, despite GCI proving to be effective in reducing both pollutants and CO2 emissions, GCI combustion controllability represents the main challenge that hinders the diffusion of this methodology for transportation. Several works in the literature demonstrated that to properly control GCI combustion, a multiple injections strategy is needed. The rise of pressure and temperature generated by the spontaneous ignition of small amounts of early-injected fuel reduces the ignition delay of the following main injection, responsible for the torque production of the engine. Since the combustion of the pre-injections is chemically driven, the ignition delay might be strongly affected by a slight variation in the engine control parameters and, consequently, lead to misfire or knocking. The goal of this work was to develop a control-oriented ignition delay model suitable to improve the GCI combustion stability through the proper management of the pilot injections. After a thorough analysis of the quantities affecting the ignition delay, this quantity was modeled as a function of both a thermodynamic and a chemical–physical index. The comparison between the measured and modeled ignition delay shows an accuracy compatible with the requirements for control purposes (the average root mean squared error between the measured and estimated start of combustion is close to 1.3 deg), over a wide range of operating conditions. As a result, the presented approach proved to be appropriate for the development of a model-based feed-forward contribution for a closed-loop combustion control strategy.

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Raison, R. J., P. K. Khanna e P. V. Woods. "Mechanisms of element transfer to the atmosphere during vegetation fires". Canadian Journal of Forest Research 15, n. 1 (1 febbraio 1985): 132–40. http://dx.doi.org/10.1139/x85-022.

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Published data and newly presented evidence demonstrate that the proportion of N or P lost from plant material during combustion under a wide range of conditions increases linearly with percentage loss of fuel weight during combustion. For N the correlation is strong, and the slope (β) of the regression line approaches unity for combustions under field or simulated-field conditions, but reduces to 0.78 for materials combusted in a muffle furnace. Almost all of the losses of N are due to volatilization. The relationship for P is less well defined, and β is lower (0.56 for field studies; about 0.2 for simulated-field or laboratory combustions). Calcium is not volatilized at the temperatures generated in most vegetation fires, thus increases in the ratio of Ca to other elements during combustion (i.e., higher ratios in burnt residue) indicate nonparticulate transfer of elements to the atmosphere. Increased ratios for Ca to N, P, K, Mg, Mn, and B were demonstrated for several components of eucalypt litter fuels, especially where the degree of combustion was high. The positive relationship between increase in Ca:element ratio and percentage element loss in nonparticulate form during combustion, is of Mitscherlich form so that initial increases in the ratio represent proportionally most element loss. Partitioning of the transfer of elements from the litter and understory to the atmosphere measured during low-intensity fires in three eucalypt forest communities demonstrated a low particulate contribution (and thus a high nonparticulate transfer) for N, K, P, and B. Particulate contributions to elemental transfers are less where combustion is more complete, resulting in formation and transport of fine grey ash which has a high Ca:element ratio. Of particular ecological importance is the significant transfer of P by nonparticulate mechanisms, because such P is likely to be permanently lost from burnt sites and natural rates of P replacement are usually very slow. Fine grey or white ash is highly nutrient enriched (e.g., up to 50-fold for P compared with concentrations in unburnt fuel), and hence its transport from the site in the smoke column, or subsequently by either wind or water, can result in substantial export of nutrients.

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Lalovic, Milisav, Zarko Radovic e Nada Jaukovic. "Characteristics of heat flow in recuperative heat exchangers". Chemical Industry 59, n. 9-10 (2005): 270–74. http://dx.doi.org/10.2298/hemind0510270l.

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A simplified model of heat flow in cross-flow tube recuperative heat exchangers (recuperators) was presented in this paper. One of the purposes of this investigation was to analyze changes in the values of some parameters of heat transfer in recuperators during combustion air preheating. The logarithmic mean temperature (Atm) and overall heat transfer coefficient (U), are two basic parameters of heat flow, while the total heated area surface (A) is assumed to be constant. The results, presented as graphs and in the form of mathematical expressions, were obtained by analytical methods and using experimental data. The conditions of gaseous fuel combustions were defined by the heat value of gaseous fuel Qd = 9263.894 J.m-3, excess air ratio ?= 1.10, content of oxygen in combustion air ?(O2) = 26%Vol, the preheating temperature of combustion air (cold fluid outlet temperature) tco = 100-500?C, the inlet temperature of combustion products (hot fluid inlet temperature) thi = 600-1100?C.

15

Hou, Shuhn-Shyurng, Chiao-Yu Chiang e Ta-Hui Lin. "Oxy-Fuel Combustion Characteristics of Pulverized Coal under O2/Recirculated Flue Gas Atmospheres". Applied Sciences 10, n. 4 (17 febbraio 2020): 1362. http://dx.doi.org/10.3390/app10041362.

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Oxy-fuel combustion is an effective technology for carbon capture and storage (CCS). Oxy-combustion for coal-fired power stations is a promising technology by which to diminish CO2 emissions. Unfortunately, little attention has been paid to the oxy-combustion characteristics affected by the combustion atmosphere. This paper is aimed at investigating the oxy-fuel combustion characteristics of Australian coal in a 0.3 MWth furnace. In particular, the influences of various oxygen flow rates and recirculated flue gas (RFG) on heating performance and pollutant emissions are examined in O2/RFG environments. The results show that with increases in the secondary RFG flow rate, the temperatures in the radiative and convective sections decrease and increase, respectively. At a lower oxygen flow rate, burning Australian coal emits lower residual oxygen and NO concentrations. In the flue gas, a high CO2 concentration of up to 94.8% can be achieved. Compared to air combustion, NO emissions are dramatically reduced up to 74% for Australian coal under oxy-combustion. Note that the high CO2 concentrations in the flue gas under oxy-coal combustions suggest great potential for reducing CO2 emissions through carbon capture and storage.

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Ťažký, Martin, Lenka Bodnárová e Rudolf Hela. "Physico-Mechanical Properties of Lightweight Concrete with Fluidized Bed Combustion Fly Ash Based Light Weight Aggregate". Materials Science Forum 908 (ottobre 2017): 106–10. http://dx.doi.org/10.4028/www.scientific.net/msf.908.106.

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Increasingly we see today among the conventional high temperature fly ash also with the production of fly ash from fluidized bed combustion. These fluidized bed combustions fly ashes, however, have little used this area, mainly for their chemical composition and morphology. Current efforts are directed towards the development of new technological processes and building materials that would allow the use of this industrial waste and its qualities. One possible way of fluidized bed combustion fly ash’s utilizing in construction industries the production of cold balled lightweight aggregate. Production of this material is economically advantageous and enables processing of large volumes of raw materials. This paper describes possibilities of using this aggregate for production of lightweight construction concrete and consequent testing of durability and resistance to various types of aggressive environment. For these lightweight structural concretes, will be verified in their thermal-technical parameters.

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Ordou, Niloofar, e Igor E. Agranovski. "Contribution of Fine Particles to Air Emission at Different Phases of Biomass Burning". Atmosphere 10, n. 5 (16 maggio 2019): 278. http://dx.doi.org/10.3390/atmos10050278.

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Particle size distribution in biomass smoke was observed for different burning phases, including flaming and smouldering, during the combustion of nine common Australian vegetation representatives. Smoke particles generated during the smouldering phase of combustions were found to be coarser as compared to flaming aerosols for all hard species. In contrast, for leafy species, this trend was inversed. In addition, the combustion process was investigated over the entire duration of burning by acquiring data with one second time resolution for all nine species. Particles were separately characterised in two categories: fine particles with dominating diffusion properties measurable with diffusion-based instruments (Dp < 200 nm), and coarse particles with dominating inertia (Dp > 200 nm). It was found that fine particles contribute to more than 90 percent of the total fresh smoke particles for all investigated species.

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Suardi, Mirnah, Norazwan Azman, Dahrum Samsudin, Norani Mansor e Amir Khalid. "Analysis of Emulsified Renewable Fuel Injector in Burner Combustion: An Overview". Applied Mechanics and Materials 773-774 (luglio 2015): 565–69. http://dx.doi.org/10.4028/www.scientific.net/amm.773-774.565.

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The use of energy and natural resources being increase due to the growth of economy and world population. One of the natural resources is being consumed heavily is diesel for transportation and burner combustion. However, the major product results from the combustions of diesel are NOx and PM emissions. This review paper focuses on the influences of the emulsified renewable biodiesel fuel such as crude palm oil and waste cooking oil with the concept fuel-air-water internally rapid mixing injector for the open burner system. Water is introduced directly into the combustion field. The concept of rapid mixing from biodiesel and water are controlling of the combustion process in order to minimize the emissions. The water content in the emulsified biodiesel fuels effectively in the reduction of NOx emissions especially the high blending biodiesel. Moreover, emulsion technology significantly reduced particulate matter (PM) emissions as compared to the standard biodiesel fuel combustion. The parameters include equivalent ratio, water content in biodiesel-water, and spray characteristics such as spray penetration, spray angle and spray area.

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Le Corre, O. "Abnormal Combustions in Internal Combustion Engines: Review on the Latest Patents Eliminating Knock Conditions". Recent Patents on Engineering 4, n. 2 (1 giugno 2010): 122–28. http://dx.doi.org/10.2174/187221210791233407.

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Corti, Enrico, Claudio Forte, Gian Marco Bianchi e Davide Moro. "Relating Knocking Combustions Effects to Measurable Data". SAE International Journal of Engines 8, n. 5 (6 settembre 2015): 2133–44. http://dx.doi.org/10.4271/2015-24-2429.

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Burtscher, H., A. Schmidt-Ott e H. C. Siegmann. "Monitoring Particulate Emissions from Combustions by Photoemission". Aerosol Science and Technology 8, n. 2 (gennaio 1988): 125–32. http://dx.doi.org/10.1080/02786828808959177.

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Yu, Xin, Zhen Cao, JiangBo Peng, Yang Yu, Guang Chang, Yufei Ma, XiaoHui Li, Chaobo Yang e ZhiQiang Wang. "Statistical Analysis of Flame Oscillation Characterization of Oxy-Fuel in Heavy Oil Boiler Using OH Planar Laser-Induced Fluorescence". Journal of Spectroscopy 2019 (2 luglio 2019): 1–10. http://dx.doi.org/10.1155/2019/7085232.

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The present work investigated the flame structures and oscillations of oxy-fuel combustions in a heavy oil boiler using OH planar laser-induced fluorescence imaging. Combustion instabilities, such as flame oscillation and combustion fluctuation, can assess the performance of an industrial burner in the boiler. The peak position variation in OH concentration was associated with the change of the reaction zone that corresponded with the fluctuation of the heat-release zone in the combustion chamber, which provides a valuable reference for the design of the combustion chamber. The experimental results suggest that the phenomenon of stratified flame combustion is related to the characteristic of flame oscillation. The substitution of N2 with CO2 will not significantly influence the flame oscillation frequency but increases the number of flame surface. As O2 concentration increased in the O2/CO2 atmosphere, the phenomenon of stratified flame combustion disappeared, and the flame presented an island-like structure. The bimodal oscillation of the combustion center was demonstrated by means of the probability density method; CO2 played a role in the extension of the combustion center. The combustion fluctuation of inner regions was quantitatively described; CO2 could maintain interregional stabilization to some extent. Compared with traditional measurement methods, PLIF technology has great advantages in evaluating burner performance and optimizing the design of the combustion chamber.

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Bashir, Ahsan, Saiful A. Zulkifli, Abd Rashid Abd Aziz e Ezrann ZZ Abidin. "Impact of Combustion Variance on Sustainability of Free-Piston Linear Generator during Steady-State Generation". Energies 14, n. 14 (6 luglio 2021): 4081. http://dx.doi.org/10.3390/en14144081.

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A free-piston linear generator (FPLG) has a number of advantages compared to a traditional crank-slider internal combustion engine, including better thermal and mechanical efficiencies, different fuel compatibility, and a higher power-to-weight ratio. For electric vehicle propulsion and generation of portable power, an FPLG is a very attractive alternative source of energy. This paper presents the development of an FPLG simulation model using MATLAB-Simulink and investigates the impact of combustion variance on its operation. Results provided insight into various characteristics of system behavior through variation of structural dimension and operational parameters. In steady-state operation with fixed electrical load and fixed ignition for combustion, it was found that consecutively low combustion pressures can easily lead to engine stoppage, pointing to the significance of control for continuous operation. Due to the absence of the moment of inertia and flywheel character of the rotating engine, a linear engine-generator is subject to ceased operation even after two consecutively low combustions under 10% variance. This will not be a fundamental problem in an ordinary crank-slider engine-generator, but in a linear engine-generator, control measure will be necessary to ensure sustained operation.

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Luo, Xiao-San, Weijie Huang, Guofeng Shen, Yuting Pang, Mingwei Tang, Weijun Li, Zhen Zhao et al. "Source differences in the components and cytotoxicity of PM_2.5 from automobile exhaust, coal combustion, and biomass burning contributing to urban aerosol toxicity". Atmospheric Chemistry and Physics 24, n. 2 (30 gennaio 2024): 1345–60. http://dx.doi.org/10.5194/acp-24-1345-2024.

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Abstract. Although air quality guidelines generally use the atmospheric concentration of fine particulate matter (PM2.5) as a metric for air pollution evaluation and management, the fact cannot be ignored that different particle toxicities are unequal and significantly related to their sources and chemical compositions. Therefore, judging the most harmful source and identifying the toxic component would be helpful for optimizing air quality standards and prioritizing targeted PM2.5 control strategies to protect public health more effectively. Since the combustions of fuels, including oil, coal, and biomass, are the main anthropogenic sources of environmental PM2.5, their discrepant contributions to health risks of mixed ambient aerosol pollution dominated by the respective emission intensity and unequal toxicity of chemical components need to be identified. In order to quantify the differences between these combustion primary emissions, 10 types of PM2.5 from each typical source group, i.e., vehicle exhaust, coal combustion, and plant biomass (domestic biofuel) burning, were collected for comparative study with toxicological mechanisms. In total, 30 types of individual combustion samples were intercompared with representative urban ambient air PM2.5 samples, whose chemical characteristics and biological effects were investigated by component analysis (carbon, metals, soluble ions) and in vitro toxicity assays (cell viability, oxidative stress, inflammatory response) of human lung adenocarcinoma epithelial cells (A549). Carbonaceous fractions were plenteous in automobile exhaust and biomass burning, while heavy metals were more plentiful in PM2.5 from coal combustion and automobile exhaust. The overall ranking of mass-normalized cytotoxicity for source-specific PM2.5 was automobile exhaust > coal combustion > domestic plant biomass burning > ambient urban air, possibly with differential toxicity triggers, and showed that the carbonaceous fractions (organic carbon, OC; elemental carbon, EC) and redox-active transition metals (V, Ni, Cr) assisted by water-soluble ions (Ca2+, Mg2+, F−, Cl−) might play important roles in inducing cellular reactive organic species (ROS) production, causing oxidative stress and inflammation, resulting in cell injury and apoptosis, and thus damaging human health. Coupled with the source apportionment results of typical urban ambient air PM2.5 in eastern China, reducing toxic PM2.5 from these anthropogenic combustions will be greatly beneficial to public health. In addition to the air pollution control measures that have been implemented, like strengthening the vehicle emission standards, switching energy from coal to gas and electricity, and controlling the open incineration of agricultural straws, further methods could be considered, especially by preferentially reducing the diesel exhaust, lessening the coal combustion by replacement with low-ash clean coals, and depressing the rural crop straw biomass burning emissions.

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Tian, Hua, Jingchen Cui, Tianhao Yang, Yao Fu, Jiangping Tian e Wuqiang Long. "Experimental Research on Controllability and Emissions of Jet-Controlled Compression Ignition Engine". Energies 12, n. 15 (31 luglio 2019): 2936. http://dx.doi.org/10.3390/en12152936.

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Low-temperature combustions (LTCs), such as homogeneous charge compression ignition (HCCI), could achieve high thermal efficiency and low engine emissions by combining the advantages of spark-ignited (SI) engines and compression-ignited (CI) engines. Robust control of the ignition timing, however, still remains a hurdle to practical use. A novel technology of jet-controlled compression ignition (JCCI) was proposed to solve the issue. JCCI combustion phasing was controlled by hot jet formed from pre-chamber spark-ignited combustion. Experiments were done on a modified high-speed marine engine for JCCI characteristics research. The JCCI principle was verified by operating the engine individually in the mode of JCCI and in the mode of no pre-chamber jet under low- and medium-load working conditions. Effects of pre-chamber spark timing and intake charge temperature on JCCI process were tested. It was proven that the combustion phasing of the JCCI engine was closely related to the pre-chamber spark timing. A 20 °C temperature change of intake charge only caused a 2° crank angle change of the start of combustion. Extremely low nitrogen oxides (NOx) emission was achieved by JCCI combustion while keeping high thermal efficiency. The JCCI could be a promising technology for dual-fuel marine engines.

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Nicoletti, Giovanni, Roberto Bruno, Natale Arcuri e Gerardo Nicoletti. "Real Costs Assessment of Solar-Hydrogen and Some Fossil Fuels by means of a Combustion Analysis". Journal of Combustion 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/6527510.

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In order to compare solar-hydrogen and the most used fossil fuels, the evaluation of the “external” costs related to their use is required. These costs involve the environmental damage produced by the combustion reactions, the health problems caused by air pollution, the damage to land from fuel mining, and the environmental degradation linked to the global warming, the acid rains, and the water pollution. For each fuel, the global cost is determined as sum of the market price and of the correspondent external costs. In order to obtain a quantitative comparison, the quality of the different combustion reactions and the efficiency of the technologies employed in the specific application sector have to be considered adequately. At this purpose, an entropic index that considers the degree of irreversibility produced during the combustion process and the degradation of surroundings is introduced. Additionally, an environmental index that measures the pollutants released during the combustions is proposed. The combination of these indexes and the efficiency of the several technologies employed in four energy sectors have allowed the evaluation of the total costs, highlighting an economic scenario from which the real advantages concerning the exploitation of different energy carrier are determined.

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Mahmoudzadeh Andwari, Amin, Apostolos Pesyridis, Vahid Esfahanian e Mohd Said. "Combustion and Emission Enhancement of a Spark Ignition Two-Stroke Cycle Engine Utilizing Internal and External Exhaust Gas Recirculation Approach at Low-Load Operation". Energies 12, n. 4 (15 febbraio 2019): 609. http://dx.doi.org/10.3390/en12040609.

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Two-stroke cycle engines have always been prominent due to their distinctive advantage incorporating high power-to-weight ratio, however the drawbacks are poor combustion efficiency, fuel short-circuiting and excessive emission of uHC and CO. These problems are apparent at low-load and speed regions and are the major obstacle to their global acceptance. The deficiencies can be addressed by increasing the in-cylinder average charge temperature employing Exhaust Gas Recirculation (EGR). An experimental study is conducted to investigate the influence of utilizing EGR techniques, including Internal and External EGR, on combustion misfiring occurrence, combustion stability and exhaust emissions using a single cylinder two-stroke SI engine at idling, low and mid-load conditions. From the results, it is observed since the average in-cylinder charge temperature is increased, due to utilizing EGRs, engine’s low and mid-load irregular combustions (misfire) and exhaust emissions are remarkably supressed and almost all of misfire cycles eliminated depending on the percentage of EGRs. In terms of combustion stability, it is agreed in general the application of EGRs improves the cyclic variation of IMEP, Pmax and CA10 compared to conventional operation. However, applying Ex-EGR compared to In-EGR will deteriorate cyclic variability of IMEP and CA10.

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DABILGOU, Téré, Oumar SANOGO, S. Augustin Zongo, Tizane Daho, Belkacem Zeghmati, Jean KOULIDIATI e Antoine BERE. "Modélisation thermodynamique de combustion mono-zone de biodiesels dans un moteur diesel et estimation théorique des émissions potentielles". Journal de Physique de la SOAPHYS 2, n. 1a (13 febbraio 2021): C20A10–1—C20A10–10. http://dx.doi.org/10.46411/jpsoaphys.2020.01.10.

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Dans le présent travail, un modèle thermodynamique de combustion à zone unique pour le carburant diesel et le biodiesel a été mis en oeuvre pour prédire la pression du cylindre afin de mieux comprendre la combustion caractéristique des différents carburants testés dans un moteur diesel et d’analyser les performances caractéristiques d'un même moteur fonctionnant avec différents types de carburants. Il s’est agi également d’évaluer les émissions potentielles de ces carburants lors de leurs combustions dans le moteur diesel. L'évaluation du modèle est faite en fonction de la complexité temporelle, de la complexité spatiale et de la précision de la prédiction à l'aide du programme informatique développé sous MATLAB. Les résultats du présent modèle montrent que les évolutions de la pression du cylindre ainsi que la température du cylindre ont été reproduites avec une bonne précision. En outre, la comparaison entre les paramètres de performance simulés et expérimentaux du moteur a montré une bonne concordance. Les resultatas montrent également des réductions des émissions polluantes avec l’utilisation des carburants alternatifs comparés au diesel.

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Lloyd Spetz, A., J. Huotari, C. Bur, R. Bjorklund, J. Lappalainen, H. Jantunen, A. Schütze e M. Andersson. "Chemical sensor systems for emission control from combustions". Sensors and Actuators B: Chemical 187 (ottobre 2013): 184–90. http://dx.doi.org/10.1016/j.snb.2012.10.078.

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Desbordes, D., L. Hamada e C. Guerraud. "Supersonic H2-air combustions behind oblique shock waves". Shock Waves 4, n. 6 (aprile 1995): 339–45. http://dx.doi.org/10.1007/bf01413876.

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Wibowo, Wusana Agung, Ari Diana Susanti e Paryanto Paryanto. "Characterization and Combustion Kinetics of Binderless and Bindered Dry Cow Dung Bio-Pellets". Equilibrium Journal of Chemical Engineering 8, n. 1 (28 gennaio 2024): 19. http://dx.doi.org/10.20961/equilibrium.v8i1.83645.

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The effect of molasses addition as a binder in the manufacturing of cow dung bio-pellets on their characteristics and combustion kinetics have been studied. The bio-pellets characterization included the physical and mechanical properties as well as the proximate analysis and calorific values. Thermogravimetric analysis (TGA) was carried out using a macro-TGA apparatus under a non-isothermal conditions and an oxidative atmosphere to study the thermal decomposition characteristics. Then, the first order Coast and Redfern method was used to determined the kinetic parameters of bio-pellets combustion. It was found that the ash content of bio-pellets were tended to decreased, while the volatile matter and fixed carbon were tended to increase with the addition of molasses. Nevertheless, the density, the axial compressive strength and the calorific values of bindered bio-pellets were decreased due to the higher amounts of water in the raw mixtures. Thermogravimetric analysis provided an information that the combustions of cow dung bio-pellets took place in three stages of decompositions The bindered bio-pellet began to decompose at lower temperatures than the binderless bio-pellet with a higher weight loss percentage. According to the comprehensive combustion characteristic index (S), the combustion performance of both binderless and bindered bio-pellets were similar. The addition of molasses as a binder tended to reduce the ignition temperature and activation energy for all stages of bio-pellets combustion.

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Cerný, Vit, e Šárka Keprdová. "Usability of Fly Ashes from Czech Republic for Sintered Artificial Aggregate". Advanced Materials Research 887-888 (febbraio 2014): 805–8. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.805.

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Artificial sintered aggregate produced by self-firing is one of the few building materials, which can be produced with only fly ash. If the character of the fly ash is optimal, no other additions are needed. However, not every fly ash has optimal composition. Quality of fly ash then influences composition of the mix, technological parameters and quality of produced aggregate. Parameters influence the process of self-firing, strength of granules during the phases of drying process, ignition and burning under given underpressure on an agglomerating bed. This often influences correct setting of proportion of combustion material and reduces quality of aggregate. The paper evaluates fly ash produced in the Czech Republic by both high temperature and fluidized bed combustions. Their granulometry, specific surface, bulk weight, structure, chemical composition and behavior at higher temperatures up to the melting point are evaluated.

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STELMASIAK, Zdzisław. "Analysis of a chosen combustion parameters of dual fuel SI engine fuelled with alcohol and gasoline". Combustion Engines 137, n. 2 (1 maggio 2009): 26–36. http://dx.doi.org/10.19206/ce-117190.

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The paper presents comparison of a selected combustion parameters of dual fuel, spark ignited engine run on gasoline and methyl alcohol. To the testing was used a four cylinder Fiat 1100 MPI engine with multipoint injection of gasoline and alcohol to area of inlet valve. Preliminary tests of the engine pointed at significant differences of its performance when the engine was run on alcohol only and on gasoline only [1]. In connection with it an indicator tests were performed in order to determine, on their base, a differences present in runs of combustions of the both fuels. The paper presents comparison of maximal pressure, rate of pressure rise, average temperature of working medium, heat release rate, total angle of combustion and indicated efficiency. These parameters were analyzed both in function of crankshaft rotation angle as well as engine load. Obtained results show at different course of methanol combustion comparing to gasoline. Run of methanol combustion is more rapid, what leads to growth of engine efficiency and increase of maximal cylinder pressures. Growth of working medium temperatures during combustion, what can lead to growth of thermal load of the engine, can be included to disadvantageous phenomena. Performed tests point at necessity of engine tuning modification during feeding with methanol, what would enable to take full benefits of advantageous properties of that fuel. Simultaneously, optimization tests have enabled to restrict disadvantageous effects of combustion of methanol.

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Iqbal, Muhammad Yousaf, Tie Wang, Guoxing Li e Wahab Ali. "Combustion Parametric Investigations of Methanol-Based RCCI Internal Combustion Engine and Comparison with the Conventional Dual Fuel Mode". European Journal of Theoretical and Applied Sciences 1, n. 5 (1 settembre 2023): 951–61. http://dx.doi.org/10.59324/ejtas.2023.1(5).82.

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Reactivity-controlled compression ignition (RCCI) is an advanced combustion mode. Its uses two fuels with different physical and chemical properties to form a combustible mixture with active stratification. RCCI can flexibly control the combustion process by changing the concentration and activity of the combustible mixture. It can also reduce the emission of NOx and particulate matter in the engine without significantly reducing the thermal efficiency. Among various fuel combinations, methanol as an oxygen-containing fuel, has a high latent heat of vaporization, which is conducive to reducing combustion temperature and achieving low-temperature combustion. This experimental study explores the potential of Methanol-Diesel Reactivity Controlled Compression Ignition (RCCI) in achieving low emissions and high thermal efficiency and compares this with the conventional dual fuel mode. Low-temperature combustions such as Reactivity Controlled Compression Ignition (RCCI) have been shown to be a promising way to reduce pollutants at the exhaust, i.e. NOx and soot emissions. and increase the thermal efficiency of future engines. The methanol to diesel energy share (MDES) could be enhanced to 56% in the RCCI mode with proper setting of the injection parameters from 45% in the dual fuel mode. A higher quantity in the second diesel pulse that occurred close to TDC led to higher thermal efficiency and good combustion stability. Engines working in a dual-fuel mode need special conditions to ignite an air-fuel mixture without a spark plug in a good moment with high combustion efficiency.

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Sadiq, Muhammad Munir, Kiyonori Suzuki e Matthew R. Hill. "Towards energy efficient separations with metal organic frameworks". Chemical Communications 54, n. 23 (2018): 2825–37. http://dx.doi.org/10.1039/c8cc00331a.

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The huge energy requirement for industrial separations of chemical mixtures has necessitated the need for the development of energy efficient and alternative separation techniques in order to mitigate the negative environmental impacts associated with greenhouse gas emissions from fossil fuel combustions for energy generation.

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S, Jacob, e Karikalan L. "Optimization of Combustion Characteristics of Diesel Engine Fueled by Biofuels and Its Diesel Blends with Additive Titanium Dioxide Nano-Particles". International Journal of Heat and Technology 39, n. 6 (31 dicembre 2021): 1973–78. http://dx.doi.org/10.18280/ijht.390636.

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The fuel crisis throughout the world made many countries to be aware of their vulnerability to oil shortages. So many researches are still in progress and focus on the growth of bio fuel usage. In this regard, alternative fuels and the drivetrain play a major rule in critical emission issues. However, at the same time, enormous and vast number of vehicles have started to claim and place their heavy demand for alternative sources of fuel. Of course, gasoline and diesel, the conventional fuels will become scarce and much costlier. With a present known reserves and steep rise of demand and rate of consumption, hope of crude oil import is not going to last long. The CFD investigation is to find the combustion characteristics of the BioFuel with the various compositions of mixing with diesel, the Kirloskar IC Engine is taken for this research and the results of pressure, velocity, turbulence kinetic energy, temperature gradients, fuel combustions, oxidizers volume fractions also obtained from the CFD analysis results. CFD Analysis of Biodiesel combustion done in ANSYS Fluent. Software modeling of IC Engine done in CATIA V5 Software. Jatropha Methyl Ester (JME) and Mahua Methyl Ester (MME) are used for this research. Combustion characteristics in addition to emission parameters are assessed then a conclusion can be drawn.

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Mohd Nordin, Mohd Hafiz B., Mohd Khair B. Hassan, Azura B. Che Soh e Mohd Amran B. Mohd Radzi. "Hardware-in-Loop of Fault Detection System for Air-Fuel Ratio Control". Applied Mechanics and Materials 663 (ottobre 2014): 233–37. http://dx.doi.org/10.4028/www.scientific.net/amm.663.233.

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Hardware-In-Loop (HIL) is a technique for control engineering testing which consists of two design parts, a real hardware design and a computer simulation design. In this paper, input signals can be obtained from the sensors while the output results of the engine combustions are generated from simulation based on mathematical model. The controller for Air-Fuel Ratio (AFR) is built to the hardware. Basically, testing using this method can reduce the cost and time-to-market in the development process. Once the real time simulation results satisfy the desired result, the design will be burned into the hardware controller and hence the system will be tested again. Both simulation and hardware results are then being compared. The main purpose for the HIL system is to develop new control algorithms as well as to control the effect of errors from sensors and engine combustion.

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L. da Silva, R., M. M. Vieira e S. X. De Brito Jr. "TWO-STROKE ENGINE BEHAVIOR (SMALL CHAINSAW) OPERATING WITH NON-COMMERCIAL FUEL BLENDS AND DIVERSE LUBRICATION". Revista de Engenharia Térmica 14, n. 2 (31 dicembre 2015): 23. http://dx.doi.org/10.5380/reterm.v14i2.62128.

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The paper presents results for experimental tests in a two-stroke internal combustions engine operating on commercial fuel (gasoline and ethanol blends), with different proportions in mineral oil for lubrication purposes. Appropriate instrumentation was used to carry out the measurement of the quantities of interest, namely fuel consumption (g/s), angular velocity (rpm) and emissions (CO2 and NOx). The methodology was based on regulations from INMETRO (motor vehicles energy conversion efficiency) and ABNT (testing of internal combustion engines). Results obtained are analyzed and discussed for the fuel consumption versus angular velocity (g/s x rpm) for each combination fuel blend and lubricating oil (quantities). Main findings are that fuel consumption increases non linearly as angular velocity increases and as lubrication lowers, while emissions decreases as angular velocity increases. Lowest fuel consumption and emissions occurred, respectively, for A25/L1:25 and A25/L1:50 (commercial fuel and standard lubrication).

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Ding, Su, Yunping Xu, Yinghui Wang, Xinyu Zhang, Liang Zhao, Jiaping Ruan e Weichao Wu. "Spatial and Temporal Variability of Polycyclic Aromatic Hydrocarbons in Sediments from Yellow River-Dominated Margin". Scientific World Journal 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/654183.

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Polycyclic aromatic hydrocarbons (PAHs) were analyzed for surface sediments and a sediment core from the Yellow River-dominated margin. The concentration of 16 USEPA priority PAHs in surface sediments ranged from 5.6 to 175.4 ng g−1dry weight sediment (dws) with a mean of 49.1 ng g−1 dws. From 1930 to 2011, the distribution of PAHs (37.2 to 210.6 ng g−1 dws) was consistent with the socioeconomic development of China. The PAHs’ concentration peaked in 1964 and 1986, corresponding to the rapid economic growth in China (1958–1965) and the initiation of the “Reform and Open” policy in 1978, respectively. The applications of molecular diagnostic ratios and principal component analysis suggest that PAHs are predominantly produced by the coal and biomass combustion, whereas the contribution of petroleum combustions slightly increased after the 1970s, synchronous with an increasing usage of oil and gas in China.

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Breitung, W. "Conservative estimates for dynamic containment loads from hydrogen combustions". Nuclear Engineering and Design 140, n. 1 (aprile 1993): 95–109. http://dx.doi.org/10.1016/0029-5493(93)90193-d.

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Silvagni, Giacomo, Davide Moro, Vittorio Ravaglioli, Fabrizio Ponti, Enrico Corti, Alessandro Brusa, Nicoló Cavina, Abhinandhan Narayanan, Kalyan K. Srinivasan e Sundar R. Krishnan. "Analysis of the Vibrational Behavior of dual-fuel RCCI combustion in a Heavy-Duty Compression Ignited Engine fueled with Diesel-NG at Low Load". Journal of Physics: Conference Series 2648, n. 1 (1 dicembre 2023): 012077. http://dx.doi.org/10.1088/1742-6596/2648/1/012077.

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Abstract In the field of internal combustion engines, the Low Temperature Combustions (LTC) appear to have the potential to reduce the formation of both soot and nitrogen oxides. One of the most promising LTC is Reactivity Controlled Compression Ignition (RCCI) which is based on the combustion of a lean low reactivity fuel-air mixture generated in the intake manifold and autoignited by small injections of high reactivity fuel introduced at high pressure in the combustion chamber. By the combination of net-zero natural gas and biodiesel, such LTC methodology might represent a suitable solution moving toward zero-emissions in transportation sector. Despite the potential to reduce pollutant emissions, Low Temperature Combustion strategies face a challenge in controlling the angular position where the combustion takes place which can be overcome by a proper management of the high-pressure injections. One potentially interesting application is related to trucks, mainly because they have long periods of idling, since emissions can be drastically reduced by means LTC. A single cylinder research engine for heavy duty application is operated under steady state conditions at low load and speed to analyze the possibility of controlling the engine behavior in dual fuel RCCI mode. The results indicate that the combustion mode switches from the dual-stage to gaussian within a narrow angular range. A further advance of the start of injection can generate misfires and significant variations in typical combustion indexes, while a delayed start of injection can cause impulsive combustion that rises the cylinder temperature and results in high-frequency pressure oscillations inside the combustion chamber. These oscillations are related to the combustion chamber typical resonance frequency, and if relevant in amplitude and persist for a long time, they might generate a potential source of failures.

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Pham, Van Chien, Jae-Hyuk Choi, Beom-Seok Rho, Jun-Soo Kim, Kyunam Park, Sang-Kyun Park, Van Vang Le e Won-Ju Lee. "A Numerical Study on the Combustion Process and Emission Characteristics of a Natural Gas-Diesel Dual-Fuel Marine Engine at Full Load". Energies 14, n. 5 (1 marzo 2021): 1342. http://dx.doi.org/10.3390/en14051342.

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This paper presents research on the combustion and emission characteristics of a four-stroke Natural gas–Diesel dual-fuel marine engine at full load. The AVL FIRE R2018a (AVL List GmbH, Graz, Austria) simulation software was used to conduct three-dimensional simulations of the combustion process and emission formations inside the engine cylinder in both diesel and dual-fuel mode to analyze the in-cylinder pressure, temperature, and emission characteristics. The simulation results were then compared and showed a good agreement with the measured values reported in the engine’s shop test technical data. The simulation results showed reductions in the in-cylinder pressure and temperature peaks by 1.7% and 6.75%, while NO, soot, CO, and CO2 emissions were reduced up to 96%, 96%, 86%, and 15.9%, respectively, in the dual-fuel mode in comparison with the diesel mode. The results also show better and more uniform combustion at the late stage of the combustions inside the cylinder when operating the engine in the dual-fuel mode. Analyzing the emission characteristics and the engine performance when the injection timing varies shows that, operating the engine in the dual-fuel mode with an injection timing of 12 crank angle degrees before the top dead center is the best solution to reduce emissions while keeping the optimal engine power.

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Huda, Quamrul, David Lyder, Marty Collins, Dave Schroeder, Dan K. Thompson, Ginny Marshall, Alberto J. Leon, Ken Hidalgo e Masum Hossain. "Study of Fuel-Smoke Dynamics in a Prescribed Fire of Boreal Black Spruce Forest through Field-Deployable Micro Sensor Systems". Fire 3, n. 3 (12 luglio 2020): 30. http://dx.doi.org/10.3390/fire3030030.

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Understanding the combustion dynamics of fuels, and the generation and propagation of smoke in a wildland fire, can inform short-range and long-range pollutant transport models, and help address and mitigate air quality concerns in communities. Smoldering smoke can cause health issues in nearby valley bottoms, and can create hazardous road conditions due to low-visibility. We studied near-field smoke dynamics in a prescribed fire of 3.4 hectares of land in a boreal black spruce forest in central Alberta. Smoke generated from the fire was monitored through a network of five field-deployable micro sensor systems. Sensors were placed within 500–1000 m of the fire area at various angles in downwind. Smoke generated from flaming and smoldering combustions showed distinct characteristics. The propagation rates of flaming and smoldering smoke, based on the fine particulate (PM2.5) component, were 0.8 and 0.2 m/s, respectively. The flaming smoke was characterized by sharp rise of PM2.5 in air with concentrations of up to 940 µg/m3, followed by an exponential decay with a half-life of ~10 min. Smoldering combustion related smoke contributed to PM2.5 concentrations above 1000 µg/m3 with slower decay half-life of ~18 min. PM2.5 emissions from the burn area during flaming and smoldering phases, integrated over the combustion duration of 2.5 h, were ~15 and ~16 kilograms, respectively, as estimated by our mass balance model.

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Teodosio, Luigi, Fabio Berni, Alfredo Lanotte e Enrica Malfi. "1D/3D simulation procedure to investigate the potential of a lean burn hydrogen fuelled engine". Journal of Physics: Conference Series 2385, n. 1 (1 dicembre 2022): 012085. http://dx.doi.org/10.1088/1742-6596/2385/1/012085.

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Abstract In recent years hydrogen, especially the one generated by renewable energy, is gaining increasing attention as a clean fuel to support the future mobility towards efficient and low emission solutions for propulsion systems. In this scenario, the present work deals with the virtual conversion of a single-cylinder Diesel engine, conceived for marine applications, into a hydrogen Spark Ignition (SI) unit. A simulation methodology is adopted, combining 1D and 3D Computational Fluid Dynamics (CFD) methods. First, experiments are realized on the original Diesel engine mounted on a test bench, collecting main performance indicators and emissions. A complete 1D engine model (GT-Power™) is developed and validated against measurements. Then, a 3D model of the cylinder (STAR-CD) is set-up and the related combustion outcomes are compared both with 1D and experimental results, showing an overall good agreement. In the second stage, the Diesel unit is converted into a port-injected hydrogen SI engine; the 3D model is re-arranged and utilized to reproduce pre-mixed hydrogen combustions under ultra-lean air/fuel (A/F) mixtures. Also, the 1D model is partly modified and coupled to an advanced combustion sub-model integrated with fast tabulated chemical kinetics to predict the knock. In particular, 1D combustion evolution is calibrated against the results of 3D CFD hydrogen combustion simulation. Finally, the calibrated 1D model is applied to investigate the advantages of ultra-lean hydrogen combustion in terms of efficiency, NO, and unburned H2 formation at medium/high loads.

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Li, Jun, Meilin Zhu, Chang Geng, Yingjie Yuan, Zewei Fu, Shu Yan, Rou Feng et al. "A Molecular Understanding of the Flame Retardant Mechanism of Zinc Stannate/Polypropylene Composites via ReaxFF Simulations". Inorganics 11, n. 6 (27 maggio 2023): 233. http://dx.doi.org/10.3390/inorganics11060233.

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As an important new flame retardant, zinc stannate (ZS) shows wide application prospects due to its many advantages. However, the flame retardant mechanism of composites made with polymer combined with ZS is still unclear. In particular, there is a lack of molecular level description of the micro-scale flame retardant mechanism. The combustion mechanism through molecular simulation technology has become an important research paradigm in the field of fire, which can provide new insights for the development of new materials. This work studied the flame retardant mechanism of composites consistent with polypropylene (PP) and ZS using reactive force field molecular dynamics (ReaxFF MD) simulations. A new force field incorporating Sn/Zn/C/H/O components for ZS/PP composites combustion reactions was developed. Twenty different ZS/PP composites were analyzed for their combustion reactions at various temperatures. To investigate the flame retarding mechanism of ZS in composites, the evolutions of reactants, products, and reaction intermediates at the molecular scale were collected. It was revealed that the combustion temperature controlled the degree of oxidation by regulating the consumption of molecular oxygen during PP cracking. An increased combustion temperature reduced the oxygen consumption rate and overall oxygen consumption. As the PP component of composites exceeded 56%, oxygen consumption increased. Evolutions for carbon-containing intermediates and the products in combustions of PP/ZS composites were analyzed. The small carbon-based fragments were more likely to be produced for composites with low PP contents at high temperatures. These results are beneficial to design ZS/PP composites as flame retardant materials.

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Zhu, Denghao, Jun Deng, Jinqiu Wang, Shuo Wang, Hongyu Zhang, Jakob Andert e Liguang Li. "Development and Application of Ion Current/Cylinder Pressure Cooperative Combustion Diagnosis and Control System". Energies 13, n. 21 (29 ottobre 2020): 5656. http://dx.doi.org/10.3390/en13215656.

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The application of advanced technologies for engine efficiency improvement and emissions reduction also increase the occurrence possibility of abnormal combustions such as incomplete combustion, misfire, knock or pre-ignition. Novel promising combustion modes, which are basically dominated by chemical reaction kinetics show a major difficulty in combustion control. The challenge in precise combustion control is hard to overcome by the traditional engine map-based control method because it cannot monitor the combustion state of each cycle, hence, real-time cycle-resolved in-cylinder combustion diagnosis and control are required. In the past, cylinder pressure and ion current sensors, as the two most commonly used sensors for in-cylinder combustion diagnosis and control, have enjoyed a seemingly competitive relationship, so all related researches only use one of the sensors. However, these two sensors have their own unique features. In this study, the idea is to combine the information obtained from both sensors. At first, two kinds of ion current detection system are comprehensively introduced and compared at the hardware level and signal level. The most promising variant (the DC-Power ion current detection system) is selected for the subsequent experiments. Then, the concept of ion current/cylinder pressure cooperative combustion diagnosis and control system is illustrated and implemented on the engine prototyping control unit. One application case of employing this system for homogenous charge compression ignition abnormal combustion control and its stability improvement is introduced. The results show that a combination of ion current and cylinder pressure signals can provide richer and also necessary information for combustion control. Finally, ion current and cylinder pressure signals are employed as inputs of artificial neural network (ANN) models for combustion prediction. The results show that the combustion prediction performance is better when the inputs are a combination of both signals, instead of using only one of them. This offline analysis proves the feasibility of using an ANN-based model whose inputs are a combination of ion current and pressure signals for better prediction accuracy.

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Yang, Xiao, Zhihong He, Lei Zhao, Shikui Dong e Heping Tan. "Effect of Channel Diameter on the Combustion and Thermal Behavior of a Hydrogen/Air Premixed Flame in a Swirl Micro-Combustor". Energies 12, n. 20 (10 ottobre 2019): 3821. http://dx.doi.org/10.3390/en12203821.

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Abstract (sommario):

Improving the flame stability and thermal behavior of the micro-combustor (MC) are major challenges in microscale combustion. In this paper, the micro combustions of an H2/air premixed flame in a swirl MC with various channel diameters (Din = 2, 3, 4 mm) were analyzed based on an established three-dimensional numerical model. The effects of hydrogen mass flow rate, thermal conductivity of walls, and the preferential transport of species were investigated. The results indicated that the flame type was characterized by the presence of two recirculation zones. The flame was anchored by the recirculation zones, and the anchoring location of the flame root was the starting position of the recirculation zones. The recirculation zones had a larger distribution of local equivalence ratio, especially in the proximity of the flame root, indicating the formation of a radical pool. The combustion efficiency increased with an increasing Din due to the longer residence time of the reactants. Furthermore, the MC with Din = 2 mm obtained the highest outer wall temperature distribution. However, the MC with Din = 4 mm had a better uniformity of outer wall temperature and large emitter efficiency due to the larger radiation surface. An increase in thermal conductivity boosts the thermal performance of combustion efficiency, emitter efficiency, and wall temperature uniformity. But there is a critical point of thermal conductivity that can increase the thermal performance. The above results can offer us significant guidance for designing MC with high thermal performance.

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Din, Shamzani Affendy Mohd, Nik Nurul-Hidayah Nik Yahya, Rashidi Othman e Alias Abdullah. "Influence of Coal-Fired Power Plant Combustions Toward Neighbourhood Residents". Advanced Science Letters 23, n. 7 (1 luglio 2017): 6114–17. http://dx.doi.org/10.1166/asl.2017.9217.

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49

Zhang, Jinzhuan. "Study on Ignition Capability of Overload Wire to Adjacent Combustions". Procedia Engineering 45 (2012): 628–32. http://dx.doi.org/10.1016/j.proeng.2012.08.213.

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Cao, B., P. Zhang, X. Zheng, C. Xu e J. Gao. "Numerical Simulation of Hydrodynamics and Coke Combustions in FCC Regenerator". Petroleum Science and Technology 26, n. 3 (19 febbraio 2008): 256–69. http://dx.doi.org/10.1080/10916460500527104.

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