Experimental Study and Kinetic Modeling of Laminar Flame Propagation in Premixed Stoichiometric n-butane-air Mixture

The laminar burning velocities and propagation speeds of stoichiometric n-butane-air mixture were obtained for outwardly propagating spherical flames by measurements of pressure rise during the early stage of propagation in a spherical vessel. The experiments were carried out at various initial pressures within 0.3 and 1.2 bar, and various initial temperatures within 298 and 423 K. The experimental laminar burning velocities were compared with those provided by the detailed kinetic modelling based on Warnatz mechanism for combustion of C1-C4 hydrocarbons, using INSFLA package. The baric and thermal coefficients of laminar burning velocities, calculated from their dependence on initial temperature and pressure, were compared with coefficients characteristic for other fuel-air mixtures. The overall activation parameters (reaction order and activation energy) are reported and discussed in comparison with similar data characteristic for alkane-air flames.

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Laminar Burning Velocities of Hydrogen-Blended Methane–Air and Natural Gas–Air Mixtures, Calculated from the Early Stage of p(t) Records in a Spherical Vessel

Energies ◽

10.3390/en14227556 ◽

2021 ◽

Vol 14 (22) ◽

pp. 7556

Author(s):

Maria Mitu ◽

Domnina Razus ◽

Volkmar Schroeder

Keyword(s):

Natural Gas ◽

Initial Conditions ◽

Numerical Study ◽

Early Stage ◽

Linear Trend ◽

Burning Velocity ◽

Pressure Rise ◽

Spherical Vessel ◽

Practical Applications ◽

Hydrogen Addition

The flammable hydrogen-blended methane–air and natural gas–air mixtures raise specific safety and environmental issues in the industry and transportation; therefore, their explosion characteristics such as the explosion limits, explosion pressures, and rates of pressure rise have significant importance from a safety point of view. At the same time, the laminar burning velocities are the most useful parameters for practical applications and in basic studies for the validation of reaction mechanisms and modeling turbulent combustion. In the present study, an experimental and numerical study of the effect of hydrogen addition on the laminar burning velocity (LBV) of methane–air and natural gas–air mixtures was conducted, using mixtures with equivalence ratios within 0.90 and 1.30 and various hydrogen fractions rH within 0.0 and 0.5. The experiments were performed in a 14 L spherical vessel with central ignition at ambient initial conditions. The LBVs were calculated from p(t) data, determined in accordance with EN 15967, by using only the early stage of flame propagation. The results show that hydrogen addition determines an increase in LBV for all examined binary flammable mixtures. The LBV variation versus the fraction of added hydrogen, rH, follows a linear trend only at moderate hydrogen fractions. The further increase in rH results in a stronger variation in LBV, as shown by both experimental and computed LBVs. Hydrogen addition significantly changes the thermal diffusivity of flammable CH4–air or NG–air mixtures, the rate of heat release, and the concentration of active radical species in the flame front and contribute, thus, to LBV variation.

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Inert Gas Influence on Propagation Velocity of Methane-air Laminar Flames

Revista de Chimie ◽

10.37358/rc.18.1.6073 ◽

2018 ◽

Vol 69 (1) ◽

pp. 196-200 ◽

Cited By ~ 7

Author(s):

Maria Mitu ◽

Venera Giurcan ◽

Domnina Razus ◽

Dumitru Oancea

Keyword(s):

Experimental Data ◽

Kinetic Modeling ◽

Early Stage ◽

Pressure Rise ◽

Laminar Flames ◽

Inert Gas ◽

Spherical Vessel ◽

Pressure Time ◽

Expansion Coefficients ◽

Propagation Velocities

The flame propagation in methane-air mixtures diluted by inert additives (He, Ar, N2, CO2) was studied by means of pressure-time records of laminar deflagrations occurring in a spherical vessel with central ignition. Experiments were made using mixtures with various equivalence ratios between 0.610 and 1.310 and various inert concentrations between 5 and 25 vol%, at various initial pressures between 50 and 200 kPa. Examination of pressure-time records in the early stage of explosions delivered the normal burning velocities Su via the coefficients of the cubic law of pressure rise, using a previously described procedure. The propagation velocities (or the flame speed) were calculated from the normal burning velocities using the expansion coefficients of the unburnt gas during the isobaric combustion. The propagation velocities of examined systems obtained from experimental data were examined against the propagation velocities obtained from kinetic modeling of methane-air-inert combustion by means of 1D COSILAB package using the GRI 3.0 mechanism.

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On the accuracy of laminar flame speeds measured from outwardly propagating spherical flames: Methane/air at normal temperature and pressure

Combustion and Flame ◽

10.1016/j.combustflame.2015.02.012 ◽

2015 ◽

Vol 162 (6) ◽

pp. 2442-2453 ◽

Cited By ~ 135

Author(s):

Zheng Chen

Keyword(s):

Laminar Flame ◽

Spherical Flames ◽

Temperature And Pressure

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Temperature and pressure influence on maximum rates of pressure rise during explosions of propane–air mixtures in a spherical vessel

Journal of Hazardous Materials ◽

10.1016/j.jhazmat.2011.04.018 ◽

2011 ◽

Vol 190 (1-3) ◽

pp. 891-896 ◽

Cited By ~ 46

Author(s):

D. Razus ◽

V. Brinzea ◽

M. Mitu ◽

C. Movileanu ◽

D. Oancea

Keyword(s):

Pressure Rise ◽

Spherical Vessel ◽

Temperature And Pressure

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Numerical predictions for laminar flame propagation in confined ozone/oxygen mixtures - Influence of initial temperature and pressure

10.2514/6.1979-292 ◽

1979 ◽

Author(s):

D. KOOKER

Keyword(s):

Flame Propagation ◽

Initial Temperature ◽

Laminar Flame ◽

Numerical Predictions ◽

Temperature And Pressure

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Degradation Kinetic Modelling of Ascorbic Acid from Orange Juice

Proceedings ◽

10.3390/foods_2020-07693 ◽

2020 ◽

Vol 70 (1) ◽

pp. 55

Author(s):

Alina Soceanu ◽

Nicoleta Matei ◽

Simona Dobrinas ◽

Viorica Popescu

Keyword(s):

Ascorbic Acid ◽

Vitamin C ◽

Orange Juice ◽

Storage Temperature ◽

Kinetic Modelling ◽

Activation Parameters ◽

Graphical Analysis ◽

State Theory ◽

Activation Process ◽

Degradation Kinetic

Vitamin C or ascorbic acid is a basic nutrient, a highly effective antioxidant, widely used as food additive. Therefore, quality control in food industry demands ascorbic acid determination methods. The purpose of this study was to determine vitamin C in natural orange juices by spectrometric and voltammetric methods. Another goal was to determine the kinetic and thermodynamics activation parameters for ascorbic acid degradation in orange juices over time and at different temperatures. It was observed that during storage, ascorbic acid concentrations in orange juices were gradually decreased with time at a rate depending on storage temperature and type of orange juice. The reaction order was determined through integrated graphical analysis where the dependences of ln ct/c0 as a function of time reveals the high values for R2, indicating that the kinetics of the degradation of AA follows first order reaction at both studied temperatures. For studied samples the loss of ascorbic acid was varied between 4.33% and 9.13%. Enthalpy variation (ΔH) and entropy variation (ΔS) of activation process were obtained from the Eyring–Polany model based on transition state theory. The values of activation energy ranged between 7289.24 kJmol−1 and 15689.54 kJmol−1.

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