Laminar flame speeds and ignition delay times of methane–air mixtures at elevated temperatures and pressures

Hu, Erjiang; Li, Xiaotian; Meng, Xin; Chen, Yizhen; Cheng, Yu; Xie, Yongliang; Huang, Zuohua

doi:10.1016/j.fuel.2015.05.010

Cited by 221 publications

(72 citation statements)

References 38 publications

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“…CONVERGE uses an innovative modified cut-cell Cartesian method for grid generation with the possibility of adding local refinement and adaptive mesh resolution (AMR). 40,41 As shown in Figure 2, the ignition delay predictions of n-heptane are in good agreement against shock tube experimental data at medium and high temperature. The nheptane is used to simulate the oxidation behavior of diesel, whereas natural gas is represented by methane.…”

Section: Numerical Simulation Modelsupporting

confidence: 69%

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Effects of injection strategies on low‐speed marine engines using the dual fuel of high‐pressure direct‐injection natural gas and diesel

Liu

Wang

et al. 2019

Energy Science & Engineering

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Pilot‐ignited high‐pressure direct‐injection (HPDI) natural gas engines have drawn much attention since being proposed, as these engines can maintain high performance and lead to clean combustion compared with conventional diesel engines. This prospective concept is not only used in vehicle engines but also used in large‐scale marine engines. In this study, the effects of injection strategies of dual fuels on combustion characteristics and emissions were investigated using the computational fluid dynamics (CFD) code CONVERGE coupled with a reduced n‐heptane/methane mechanism. The results showed that the effects of absolute injection timing (AIT) on the combustion characteristics and emissions are similar to those of traditional diesel engines. As the AIT varies from advanced by 4°CA to retarded by 4°CA, the peak values of the in‐cylinder pressure and temperature decrease gradually. However, a conventional trade‐off between NOx and soot/CO/HC/ISFC emissions can also be observed as the AIT is retarded. In contrast, relative injection timing (RIT) has more complicated impacts on the combustion and emissions characteristics. The in‐cylinder temperature distribution and concentration stratification change as the gas jet initially interacts with the pilot flame. The effects of the gas injection timing on the combustion characteristics and indicated specific fuel consumption are also similar to those of the AIT, but the emissions are quite different. The pilot injection timing shows minimal influence on the main combustion process. Better performance can be obtained with partially premixed combustion with a slightly late injection timing compared with that of the original (ORG) base case.

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Section: Numerical Simulation Modelsupporting

confidence: 69%

“…Ignition delay predications using the present reduced mechanism were compared with shock tube experimental data. 40,41 As shown in Figure 2, the ignition delay predictions of n-heptane are in good agreement against shock tube experimental data at medium and high temperature.…”

Section: Numerical Simulation Modelsupporting

confidence: 69%

Effects of injection strategies on low‐speed marine engines using the dual fuel of high‐pressure direct‐injection natural gas and diesel

Liu

Wang

et al. 2019

Energy Science & Engineering

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“…The laminar flame front can be divided into two regions: a preheat zone where the unburned mixture temperature increases through conduction, and a reaction zone where the exothermic chemical reactions take place [9]. The fuel attributes defines the premixed laminar combustions fundamental burning properties, defining its diffusivity, exothermicity, and reactivity [10]. Also, the laminar flame characteristics are dependent on the environment temperature, pressure and equivalence ratio.…”

Section: Premixed Combustionmentioning

confidence: 99%

Dual-Fuel Combustion Characterization on Lean Conditions and High Loads

Pettinen

Kaario

Larmi

2017

SAE Technical Paper Series

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Unstable oil markets combined with the alarming statistics of continuously growing emission problems causes anxiety among many nations. The greatest dilemma lies in the answer about how to rationally overcome the dependency of fossil based energy sources. The truth seems to be found on utilizing renewable energy generating low emissions. Methane is suggested as one of the worthwhile solutions for substituting crude-oil based fuels. Methane as a fuel combined with modern engine technology seems to open possibilities solving the above mentioned problems.Dual-fuel technology is suggested as a solution for effectively utilizing alternative fuels in the near future. Charge air mixed methane combined with a compression ignition engine utilizing a small diesel pilot injection seems to form a worthwhile compromise between good engine efficiency and low emission outcome. Problems concerning dual-fuel technology profitableness seems to be related to fully control the combustion in relation to lean conditions. Lean operating conditions solves the problems concerning pumping losses, but brings challenges in controlling the slow heat release of the premixed methane.A study concerning lean operation dual-fuel combustion was executed. In the thesis, a single cylinder 'free parameter' diesel engine was adapted for dual-fuel (diesel-methane) usage. A parameter research related to lambda window widening possibilities was carried out. The main variables studied were diesel pilot injection timing and pressure, diesel substitution rate and the relation between combustion characteristics and charge air temperature.Diesel pilot injection parameter optimization seems to affect less on combustion quality compared to the benefits from increasing the charge mass reactivity through preheating the charge air. Improvements in combustion quality were noted in all lean condition tests in the diesel substitution rate scale 0 -70%. However, significant variation in combustion characteristics were noted through the whole substitution rate range. Remarkable accomplishments in combustion behavior were experienced in the misfire boundary conditions in a form of premixed mixture ignition in the end gas region (PREMIER).Keywords dual-fuel, methane fuel, combustion character TiivistelmäÖljymarkkinoiden epävarmat ennusteet sekä jatkuvasti kohoavat päästöt aiheuttavat maailmanlaajuista huolta tulevaisuuden kannalta. Suurimmat kysymykset ongelmatilanteeseen liittyvät fossiilisten raakaöljyjen korvaamismahdollisuuksiin. Ratkaisu vaikuttaisi löytyvän uusiutuvista, matalia päästöarvoja tuottavista energianlähteistä. Yhdeksi kannattavaksi raakaöljyn korvaajaksi on ehdotettu metaanikaasua. Ennusteet metaanikaasun eduista yhdistettynä modernien polttomoottorien kanssa enteilevät mahdollisuuksia ongelmien ratkaisemiseksi.Dual-fuel-teknologia on esitetty hyväksi moottorityypiksi hyödyntämään uusiutuvia energianlähteitä. Imuilmaan esisekoitettu metaanikaasu yhdistettynä puristussytytteisen polttomoottorin kanssa, jossa polttoaine-seoksen syttymistä sekä p...

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“…[2,3] It can be used to validate combustionr eaction mechanismsand represents an importantinput parameter for the numerical modelingo fc ombustion processes. [4,5] Amongt he different experimental configurationsfor measuring this quantity,t he freely expanding spherical flame within an enclosed explosion vessel has been widelyu sed for measuring flame speed and has been confirmed to be an elegant tool, not only because its setup is relatively simpleb ut also because it can be appliedt op articular thermodynamic conditions such as elevated pressure and temperature [6][7][8][9][10][11][12] and mixture conditions near extinction,w hich is of significant importance for practical applications.T he spherically expanding flame is not stabilized by solid walls,w hich would otherwise influence the burningb ehaviorb ym eans of heat loss to walls,s uch as in the Bunsen-type burner or the heat-flux burner usedf or the measurement of flame speed. [13] Moreover, the setup can be operated for laminar or turbulent conditionsb yu sing fans.…”

Section: Introductionmentioning

confidence: 99%

Impact of Infinite Thin Flame Approach on the Evaluation of Flame Speed using Spherically Expanding Flames

et al. 2017

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Combustion is an important part of most current and future overall energy‐conversion systems, especially if using renewable fuels in energy‐storage concepts. Therefore, the laminar flame speed, which is a key parameter for the design of combustion systems, needs to be known for a growing multitude of different thermodynamic conditions and fuels. The spherically expanding flame method is one of the few techniques that enables the flame speed to be measured under particular conditions such as elevated pressure and temperature as well as under turbulent conditions, which are important for energy‐conversion applications. The radius of a spherically propagating flame is tracked and used for evaluation of the flame speed. Usually, the flame is assumed to be infinitely thin. To assess the influence of this assumption, direct numerical simulations were conducted for the experimental setup and compared with measurements and correlations from the literature. The flame speed determined by the consumption rate of fuel, which takes a finite thickness of the flame into account, was found to be always larger than the flame speed computed by assuming an infinitely thin flame. The difference between these flame speeds was observed to be as large as approximately 10–20 % in the evaluation range of the measured flame radii, which decreases with growing flame radius. This gives rise to the discrepancies in the flame speeds obtained from different measurement methods. An analytical estimation for this difference was developed as a function of the flame radius, which showed quantitatively good agreement with the simulation results and may be used for experimental validations of the flame speed. Both premixed H2/air and CH4/air flames with equivalence ratios ranging from lean to rich conditions were studied.

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Laminar flame speeds and ignition delay times of methane–air mixtures at elevated temperatures and pressures

Cited by 221 publications

References 38 publications

Effects of injection strategies on low‐speed marine engines using the dual fuel of high‐pressure direct‐injection natural gas and diesel

Effects of injection strategies on low‐speed marine engines using the dual fuel of high‐pressure direct‐injection natural gas and diesel

Dual-Fuel Combustion Characterization on Lean Conditions and High Loads

Impact of Infinite Thin Flame Approach on the Evaluation of Flame Speed using Spherically Expanding Flames

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