Proceedings of the Combustion Institute最新文献

{"title":"On the inclusion of preferential diffusion effects for PAH tabulation in turbulent non-premixed ethylene/air sooting flames","authors":"Alexandre Coudray, Eleonore Riber, Bénédicte Cuenot","doi":"10.1016/j.proci.2024.105607","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105607","url":null,"abstract":"Soot is an unwelcome by-product of combustion that not only raises public health issues but also plays a role in climate change and, more practically, deteriorates engine performances. Although critical for the design of low-soot burners, the numerical prediction of soot phenomena remains a challenge. Among other, one major difficulty is linked to the numerous chemical species involved in the chemistry of gaseous soot precursors (PAHs). In this paper, an improved modeling methodology is proposed to describe PAHs, which relaxes standard assumptions on transport properties and number of PAHs, two aspects which play a major role on the PAH evolution. To do so, a hybrid method has been developed, coupling semi-detailed chemistry integration for the accurate flame structure description, with pre-tabulated quantities issued from prior simple calculations for gaseous soot precursors modeling. In addition the classical flamelet approach has been extended to account for non-unity Lewis numbers. The proposed modeling approach is first validated against laminar counter flow diffusion ethylene/air flames and then applied to a 3D turbulent non-premixed ethylene/air combustor operated at Cambridge University. Comparison with measurements confirm the validity of the approach for the prediction of PAH.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"17 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measuring methane destruction efficiency in gas flares with dual comb spectroscopy","authors":"Sean C. Coburn, Nicolas Harris, Elijah A. Miller, Stefan Droste, Kevin Knabe, Gregory B. Rieker","doi":"10.1016/j.proci.2024.105533","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105533","url":null,"abstract":"Gas flaring is used as an alternative to venting when waste gases cannot be captured from industrial processes such as oil and natural gas production, chemical processing, and waste management. In the oil and natural gas production sector alone, an estimated 3.5 % of total global natural gas production is flared. Survey studies have shown that the methane destruction efficiency (DE) of flares is lower than expected due to real-world conditions (weather and equipment malfunction) and estimate that improving flare efficiency is a 0.5 Tg/yr methane emissions reduction opportunity. Continuous monitoring of flare DE would provide the opportunity for feedback to lower emissions; however, there are currently no technologies used at scale that can provide such a measurement. Here we present a method for measuring the operational methane DE from flares by monitoring methane levels in flares using dual-frequency comb spectroscopy. This method leverages the temperature-dependent absorption fingerprint of methane to differentiate heated and ambient methane. We assess the capabilities of this technique through a set of laboratory-based experiments utilizing a partially premixed methane flame. We estimate the limit of detection (LOD) and sensitivity of the measurements for directly monitoring a flame, and monitoring a flame from a distance of 1 km in the presence of ambient methane. For our configuration, a targeted monitoring scenario (direct flame measurement) results in the ability to distinguish methane DE up to 99.9 %; whereas in the presence of a 1 km background methane signal, the approach is able to quantify methane DE to 97.5 %. These performance metrics could be improved through an updated high-temperature spectral absorption database for methane, however the current estimated performance could already substantially impact flare emissions by closing the gap between the flare design specifications and what research studies estimate from actual in-field performance.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"82 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine learning assisted characterisation and prediction of droplet distributions in a liquid jet in cross-flow","authors":"Giovanni Tretola, Paul McGinn, Daniel Fredrich, Konstantina Vogiatzaki","doi":"10.1016/j.proci.2024.105760","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105760","url":null,"abstract":"In this paper, an artificial neural network (ANN) is trained with large eddy simulation (LES) data to predict the droplet size distribution (DSD) from the primary atomisation of a liquid jet in gaseous cross-flow (JIC), in terms of the Weber number (), momentum flux ratio () and density ratio. The JIC is simulated considering three (250, 500, 1000), (1, 5, 10), and density ratios (10, 100, 1000), respectively. The accuracy of the simulations is enhanced by including the injector geometry as well. The training data are obtained using LES with a stochastic fields transported-probability density function (PDF) method. We initially provide a physical analysis of the droplet distributions observed. We find that for lower density ratios, the resulting spray is mostly dominated by , influencing the main mechanisms governing the break-up process, which change the DSD shape. This dual mechanism is not present when increasing the density ratio. In the second part of the work, we build an ANN model (based on a multi-layered perceptron) using the DSDs from the LES as a train-and-test dataset, to predict at the end the full DSD for the JIC given as input the three non-dimensional parameters. The DSD from the trained ANN is found to be a good fit for the range investigated, predicting both the stochastic nature and change in shape of the droplet populations upon varying the input parameters. The developed model is intended to enhance future simulations of secondary atomisation in Eulerian-Lagrangian frameworks by providing the initial DSDs.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"1 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of reaction progress on the laminar flame speed of gasoline/air mixtures under engine-relevant conditions","authors":"Haruki Tajima, Takuya Tomidokoro, Takeshi Yokomori","doi":"10.1016/j.proci.2024.105734","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105734","url":null,"abstract":"Understanding flame propagation in a gasoline/air mixture with reaction progress is necessary to understand flame propagation in the cylinder and improve the combustion performance in spark-ignition engines. In this study, numerical simulations were performed to discuss the mechanisms of laminar flame speed evolution of flames propagating in gasoline/air mixtures with reaction progress. The simulation was conducted for stoichiometric and fuel-lean mixtures under high temperature and pressure conditions considering the in-cylinder condition of spark-ignition engines. Two reactors in Ansys Chemkin-Pro software were coupled. The first reactor simulates a homogeneous, adiabatic, isochoric reaction progress for a finite designated time. The pressure increase in the reaction progress period was taken into account as observed in practical engines. Then, the output of the first reactor was used as the inlet condition of the second reactor, which simulates a steady one-dimensional planar flame propagation. As a result, the laminar flame speed increased despite the pressure increase caused by the reaction progress in the first reactor. However, the rate of change in the laminar flame speed with respect to the reaction progress varied depending on the conditions, and a greater rate of increase was observed in fuel-lean conditions than in stoichiometric conditions. Also, the trend was related to low temperature chemistry. A comparative study was conducted to examine the thermal, pressure, and chemical effects of reaction progress on the laminar flame speed, and the temperature increase by reaction progress had the dominant increase effect, while pressure increase and reduced chemical enthalpy by chemical composition change had negative impacts on flame propagation. Furthermore, sensitivity analysis was conducted to investigate how the reaction in the flame changes as a result of reaction progress. The results indicate that the increase in pressure and compositional change influenced the flame chemistry and resulting changes in the laminar flame speed, and the equivalence ratio had a significant impact on the trend of sensitivity.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"14 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142180281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of primary volatiles during fast pyrolysis of waste tyre in a wire mesh reactor","authors":"Md Maksudur Rahman, Yun Yu, Hongwei Wu","doi":"10.1016/j.proci.2024.105587","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105587","url":null,"abstract":"This study investigates the formation of primary volatiles obtained from fast pyrolysis of waste tyre using a wire mesh reactor (WMR) at a temperature of 300‒600 °C and a heating rate of 1000 °C/s. The unique design of WMR allows the collection of primary volatiles with minimized secondary reactions in the vapour phase. Using a recently developed method, this study successfully quantified all major products in the primary volatiles (condensed as oil product) by gas chromatography-mass spectrometry (GC‒MS). The waste tyre pyrolysis can start at a low temperature of ∼250 °C, and the char yield reduces but the oil yield increases with pyrolysis temperature and holding time. At 600 °C, the char yield rapidly reaches a stable value of ∼35 % due to the presence of carbon black in the waste tyre. The oil yield at a holding time of 100 s increases from ∼20 % at 350 °C to a maximum of ∼47 % at 600 °C. The oil products mainly include limonene, isoprene, toluene, ethylbenzene, and p-xylene. Among these major products, limonene has the highest selectivity of ∼60‒65 % depending on the pyrolysis conditions, while isoprene, p-xylene, ethylbenzene, and toluene contribute to ∼9‒13 %, ∼7‒10 %, ∼6‒8 %, ∼6‒8 % of the oil products, respectively. The total selectivity of the quantified compounds in the oil products is about ∼94‒97 %, indicating that almost all compounds in the oil products are quantified. During pyrolysis, limonene and isoprene are mainly produced from natural rubber, while aromatic products such as toluene, p-xylene and ethylbenzene are more likely produced from synthetic rubber. The tyre sample exhibits melting behaviour at ≥400 °C, forming a molten liquid phase that may promote the secondary reactions of isoprene to form limonene via monomer recombination. Overall, these results provide new insights into the primary pyrolysis mechanism of waste tyre.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"59 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142180282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comprehensive effect of the coal rank and particle size on ammonia/coal stream ignition","authors":"Peng Ma, Qian Huang, Ziqiu Wu, Tong Si, Zhou Lv, Shuiqing Li","doi":"10.1016/j.proci.2024.105464","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105464","url":null,"abstract":"Co-firing green ammonia and coal in power plants is expected as an attractive method to phase down coal power. During the co-firing process, the ignition and combustion of pulverized coal particles are comprehensively affected by coal rank and particle size. However, the influences of coal rank and particle size on ammonia/coal stream ignition are unknown. In this study, the coal ignition process of different coal ranks (lignite, sub-bituminous, bituminous, and anthracite) and particle sizes (ranging from 63 to 120 µm) were investigated using a novel two-stage flat flame burner at various co-firing ratios. Multi-optical methods, including CH and NH chemiluminescence and high-speed backlight videography, were used to characterize the ignition process. Co-firing ammonia in the hot gas environment has both positive and negative effects on subsequent pulverized coal combustion. The positive effect is the elevated ambience temperature, while the negative effect is the consumption of oxygen in the reaction zone due to the ammonia reaction. Due to the positive effect, co-firing with ammonia in hot gas environment can induce the transition of the ignition mode. For high rank coal (e.g., anthracite) and large coal particles, the ignition mode transitions from heterogeneous ignition dominance to hetero-homogeneous joint ignition dominance. In contrast, For low-rank coal and small coal particles, co-firing ammonia further enhances the homogenous ignition and combustion. These findings contributes to the further application of the ammonia-coal co-firing technology.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"5 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Grid resolution considerations for simulating non-ideal cellular detonations","authors":"Patrick A. Meagher, Xinyu Zhao","doi":"10.1016/j.proci.2024.105412","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105412","url":null,"abstract":"3D high-fidelity simulations of non-ideal detonations in narrow channels are conducted in this study to assess the numerical resolution requirement for capturing both viscous and thermal wall losses. 3D simulations are complimented with auxiliary 2D simulations of the narrow dimension of the channel. A comprehensive convergence study, with grid resolutions ranging from 11 to 357 cells per ZND induction length was performed. A brief scale analysis was performed using Mirels’ boundary layer solution, which provides a framework for estimating the resolution requirements for a non-ideal detonation simulation. The impact of grid resolution and boundary condition was quantitatively assessed through measurement of the average detonation wave speed, analysis of average boundary layer profiles, and comparison of the effective local volumetric momentum and heat loss terms. By filtering Mirels’ solution, the loss terms from simulation were accurately recreated. This provides a mechanism to predict the error in detonation wave speed based on grid resolution. Using the filtered Mirels’ model, a simulation resolution criterion is proposed, requiring the grid resolution to be at least the momentum thickness evaluated at one induction length after the lead shock.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"16 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142180283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On local displacement speeds, their correlations with flame-front quantities, and their temporal evolution measured in turbulent premixed flames","authors":"Aaron W. Skiba, Campbell D. Carter, Stephen D. Hammack, James F. Driscoll","doi":"10.1016/j.proci.2024.105542","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105542","url":null,"abstract":"This study reports measurements of two-dimensional (2D) local displacement speeds ( ▪ ), curvature ( ▪ ), and tangential strain rate ( ▪ ) extracted from premixed flames subjected to turbulent Karlovitz and Reynolds numbers ranging from 2.1–23 and 1500–3500, respectively. Such measurements were facilitated through joint implementation of OH PLIF and stereoscopic PIV at 20kHz. Deriving these quantities from OH-PLIF-based flame edges permitted, to our knowledge, the first experimental assessment of their statistical correlations. Namely, joint PDFs (JPDFs) and conditional mean (CM) profiles of ▪ and ▪ indicate that ▪ tends to decrease as the magnitude of ▪ increases. JPDFs and CM profiles of ▪ and ▪ exhibit a strong negative correlation and demonstrate that density weighted values of ▪ ( ▪ , where and represent the density within the reactants and at the iso-contours selected to define the flame front, respectively) exceed three times the un-stretched laminar flame speed () when ▪0. Global averages of ▪ extracted near the bases of flames were 20%–30% less than ; yet, such values increased with axial distance (). These findings are all consistent with prior direct numerical simulation (DNS) studies, particularly those of burner-stabilized flames. Beyond enabling correlations of the aforementioned quantities, the employed diagnostics, coupled with a unique flame-edge-point tracking algorithm, enabled statistical assessment of their temporal evolution. Specifically, deriving a normalized time (01) based on when two flame-edge-points merged allowed assessment of quantities conditioned on the flame-edge-points proceeding that merger. Such analysis revealed that, on average, the lives of flame-edge-points fall into two epochs: (1) for 0.8, ▪ slowly decreases as increases and ▪; and (2) when 0.8, ▪ sharply increases to values exceeding and there is a marked rise in the decay rate of ▪ . These trends are consistent with recent DNS studies and support implementing a -based -model capable of predicting its extreme characteristics as flame-edge-points approach annihilation.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"62 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An experimental marker of thermo-diffusive instability in hydrogen-enriched flames","authors":"Oussama Chaib, Simone Hochgreb, Isaac Boxx","doi":"10.1016/j.proci.2024.105763","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105763","url":null,"abstract":"The structure of hydrogen-enriched methane-air flames in a Bunsen burner at low turbulence is investigated using OH planar laser-induced fluorescence (PLIF). Three flames are investigated at identical unstretched laminar flame speeds and turbulence conditions, while hydrogen enrichment is varied up to 70% by volume. An increase in global flame consumption speed is recorded with hydrogen addition, and is attributed to both an increase in flame surface area and fluctuations in stoichiometry along the flame surface as a result of differential diffusion. These fluctuations are found to be well-captured by the gradient of OH-PLIF intensity along the flame front and it is hence identified as a promising experimentally-accessible marker of thermo-diffusive instability. Its correlation with curvature is hereby examined for the first time experimentally. No correlations are found in absence of hydrogen, while increasingly positive correlations are recorded with hydrogen enrichment, consistent with the behavior of local fuel consumption in direct numerical simulations (DNS) of lean hydrogen-air flames. This highlights the potential of OH intensity gradient magnitudes as a marker of thermo-diffusive instability, and a potential surrogate for local fuel consumption speed which is inaccessible experimentally.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"84 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142180284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Theoretical and experimental characterization of CO2 CPP fs CARS for high-temperature and high-pressure diagnostics","authors":"Mingming Gu, Ziqiao Chang, Aman Satija, Shengming Yin, Shaojie Wang, Fei Qi, Robert P. Lucht","doi":"10.1016/j.proci.2024.105737","DOIUrl":"https://doi.org/10.1016/j.proci.2024.105737","url":null,"abstract":"We presented a theoretical model designed to account for collisional line-mixing (LM) effects in order to provide an accurate characterization of femtosecond (fs) coherent anti-Stokes Raman scattering (CARS) spectroscopy for CO under high-temperature and high-pressure conditions. Numerical simulations revealed that the closely spaced rotational transitions within each CO vibrational manifold induced significant collisional line-mixing. This phenomenon led to a narrowing of the bandwidth of the entire vibrational manifold, partially offsetting the collisional broadening effects. Theoretical derivations further suggested that, for a relatively short probe delay (4-9 ps), a high-pressure CO chirped probe pulse (CPP) fs CARS spectrum could be precisely modeled by utilizing transition information extracted from atmospheric pressures. This proposition was substantiated through experimental measurements conducted in an atmospheric-pressure laminar flame over a temperature range of 300-1922 K, as well as in a high-pressure and high-temperature gas cell (HPHTC) at pressures up to 69 atm and preset temperatures reaching 805 K. The results indicated that CO CPP fs CARS held promise as an ideal diagnostic tool for high-pressure environments.","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"306 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}