scholarly journals Experimental and Numerical Study of Ignition and Flame Propagation for Methane–Air Mixtures in Small Vessels

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 998
Author(s):  
Maria Prodan ◽  
Emilian Ghicioi ◽  
Robert Laszlo ◽  
Irina Nalboc ◽  
Sonia Suvar ◽  
...  
Keyword(s):  
Flame Propagation ◽  
Numerical Study ◽  
Burning Velocity ◽  
Pressure Rise ◽  
Time History ◽  
Initial Pressure ◽  
Minimum Ignition Energy ◽  
Early Stages ◽  
Elementary Analysis ◽  
Pressure Time

Methane is one of the most common gaseous fuels that also exist in nature as the main part of the natural gas, the flammable part of biogas or as part of the reaction products from biomass pyrolysis. In this respect, the biogas and biomass installations are always subjected to explosion hazards due to methane. Simple methods for evaluating the explosion hazards are of great importance, at least in the preliminary stage. The paper describes such a method based on an elementary analysis of the cubic law of pressure rise during the early stages of flame propagation in a symmetrical cylindrical vessel of small volume (0.17 L). The pressure–time curves for lean, stoichiometric and rich methane–air mixtures were recorded and analyzed. From the early stages of pressure–time history, when the pressure increase is equal to or less than the initial pressure, normal burning velocities were evaluated and discussed. Qualitative experiments were performed in the presence of a radioactive source of 60Co in order to highlight its influence over the explosivity parameters, such as minimum ignition energy, maximum rate of pressure rise, maximum explosion pressure and normal burning velocity. The results are in agreement with the literature data.

scholarly journals 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 ◽  
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.

Destruction of Cryogenic Pressure Vessel and Piping by Shock Wave

2005 ◽  
Author(s):  
Toshiaki Watanabe ◽  
Kazumasa Ebihara ◽  
Kazuyuki Hokamoto ◽  
Shigeru Itoh
Keyword(s):  
Shock Wave ◽  
Pressure Vessel ◽  
Industrial Development ◽  
Pressure Rise ◽  
Time History ◽  
Cryogenic Fluids ◽  
Inner Pressure ◽  
Pressure Time ◽  
Medical Facilities ◽  
Lng Tank

In recent years, a use for cryogenic fluids as a coolant has been increasing because of the industrial development of low temperature technology. Therefore, the use of the cryogenic pressure vessel and piping become general. LNG-tank, LN2, O2-tank at food factory and medical facilities are given for example. In the cryogenic pressure vessel and piping, reducing the thermal insulation of that by initial small damage, leads to an internal pressure rise and occurring of flashing, and causing secondary crush of pressure vessel and piping also. Then, we conducted the experiment, which imitates crush when the pressure vessel and piping, which were filled with cryogenic temperature fluid, receive a shock wave. The inner pressure time history in such as this situation was measured, and safety of cryogenic pressure vessel and piping was considered.

Simplified Methodology for Analysis of Reflected Detonation and DDT: Part 1 — Elastic Analysis

2014 ◽  
Author(s):  
Thomas C. Ligon ◽  
David J. Gross ◽  
Stephen D. Ahnert ◽  
John C. Minichiello
Keyword(s):  
Initial Conditions ◽  
Time History ◽  
Initial Pressure ◽  
Propagation Distance ◽  
Element Model ◽  
Simplified Approach ◽  
Pressure Time ◽  
Unburned Fuel ◽  
Reflecting Surface ◽  
Peak Pressures

This paper introduces a simplified approach for analyzing local elastic hoop response of piping to reflected gaseous detonations and deflagration-to-detonation transitions (DDT). A consequence associated with gaseous explosions is the potential for DDT to occur near the end of a closed pipe or gas pocket. As an accelerating deflagration flame approaches a closed end, the unburned fuel ahead of the flame front is compressed to an elevated initial pressure. This process is often referred to as pressure piling or pre-compression, and the combination of detonation reflection with the elevated initial pressure, can produce extremely high peak pressures and large values of impulse. In this paper, the event where DDT occurs immediately ahead of the reflecting surface is referred to as a reflected-DDT (R-DDT). In addition to gas mixture and initial conditions, the peak pressure and shape of the pressure time-history associated with a reflected detonation or DDT is a function of the detonation propagation distance prior to reflection and the relative distance between the ignition location, the DDT location, and the reflecting surface. An empirical pressure time-history has been developed using pressure data from approximately 190 explosion tests using hydrogen and nitrous oxide mixtures in 2-inch and 4-inch pipe to describe events ranging from fully-developed reflected detonations to R-DDTs. The empirical model of the pressure time-history was validated by comparing measured elastic hoop strains to finite-element model predictions using the pressure time-history model. Part 2 of this paper compares the methodology to plastic response data.

Destruction of Cryogenic Pressure Vessel and Piping by Shock Wave

2006 ◽  
Vol 129 (1) ◽  
pp. 38-42
Author(s):  
Toshiaki Watanabe ◽  
Kazuyuki Hokamoto ◽  
Shigeru Itoh
Keyword(s):  
Shock Wave ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Food Processing ◽  
Pressure Rise ◽  
Time History ◽  
Industrial Applications ◽  
Cryogenic Fluids ◽  
Pressure Time ◽  
Lng Tank

In recent years, the usage of cryogenic fluids as coolant are gaining more attention due to their capability to fulfill the requirements of today’s advancing low temperature industrial applications. As a result, the use of a cryogenic pressure vessel and piping in LNG-tank, LN2, O2 tank for food processing applications and medical applications are becoming more important. In a cryogenic pressure vessel and piping, the reduction of thermal insulation by a small initial damage leads to an internal pressure rise and occurrence of flashing, which leads to a secondary crush of the vessel. In this study, a shock wave was applied to a pressure vessel and piping filled with cryogenic fluid and various observations were made. The internal pressure time history was measured and the safety of the cryogenic pressure vessel and piping was considered.

Influence of Ambient Conditions on Laminar Burning Velocity, Ignition and Flame Extinction for Ethanol-Air Mixtures

2012 ◽  
Author(s):  
Daniel de la Rosa ◽  
Andrew P. Crayford ◽  
Philip J. Bowen ◽  
Agustin Valera-Medina
Keyword(s):  
Flame Propagation ◽  
High Speed ◽  
Initial Conditions ◽  
Burning Velocity ◽  
Experimental Studies ◽  
Initial Pressure ◽  
Ambient Conditions ◽  
Discharge System ◽  
Stretch Rate ◽  
Nonlinear Trends

Experimental studies of laminar ethanol - air gaseous flames have been undertaken in a large (34 l) cylindrical constant volume combustion bomb to investigate combustion fundamentals at varying ambient conditions. This vessel has been designed to minimise the influence of boundary walls, hence extending the quasi steady pressure region over which meaningful data may be obtained. Gaseous homogeneous mixtures are achieved by injecting liquid ethanol into the bomb which pre-vaporises prior to ignition. Initial pressure and equivalence ratio are predetermined using partial pressure methodology. Flame propagation is recorded utilising high-speed Schlieren photography, and low ignition energies were achieved via a variable discharge system enabling the sensitive early stages of flame propagation and extinction limits to be studied. Data is presented in terms of flame speed against stretch rate from which Markstein lengths and laminar burning velocities are derived for a variety of different initial conditions. The effect of ignition energy, initial pressure (from sub-atmospheric to elevated pressure) along with the effect of increasing initial temperature is studied. Results are discussed in terms of those of previous workers, and compared with predictions from detailed chemical kinetic schemes. Nonlinear trends witnessed during early stage flame propagation are further investigated as a suitable method for deriving extinction stretch rate.

Numerical study of the effects of laminar flame speed on flame dynamics in the early stages of flame propagation in two-dimensional half open tubes

2021 ◽  
Vol 46 (1) ◽  
pp. 1288-1301
Author(s):  
Haoxin Deng ◽  
Zhifeng Yao ◽  
Guoyan Chen ◽  
Xiaoping Wen ◽  
Fahui Wang ◽  
...  
Keyword(s):  
Flame Propagation ◽  
Laminar Flame ◽  
Numerical Study ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Two Dimensional ◽  
Early Stages ◽  
Flame Dynamics

scholarly journals Deflagration Characteristics of N2-Diluted CH4-N2O Mixtures in the Course of the Incipient Stage of Flame Propagation

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5918
Author(s):  
Maria Mitu ◽  
Codina Movileanu ◽  
Venera Giurcan
Keyword(s):  
Flame Propagation ◽  
Pressure Rise ◽  
Initial Pressure ◽  
Time Intervals ◽  
Industrial Plants ◽  
Incipient Stage ◽  
Cubic Law ◽  
Mass Fractions ◽  
Main Component ◽  
Short Time

In this study, experimental measurements in a spherical combustion bomb were performed in order to investigate the flame propagation in N2-diluted CH4-N2O mixtures with stoichiometric equivalence ratio, at several initial pressures (0.5–1.75 bar) and ambient initial temperatures. Methane was chosen as a test-fuel, since it is the main component of natural gas, a fuel often used as a substitute to gasoline in engines with internal combustion and industrial plants. The method approached in this study is based on a simple examination of the cubic law of pressure rise during the early (incipient) period of flame propagation. The incipient stage defined by a pressure rise equal or smaller than the initial pressure, was divided into short time intervals. The burnt mass fractions (obtained using three different Equations) and flame radii at various moments of the flame propagation in the course of the incipient stage were calculated. The cubic law coefficients and corresponding laminar burning velocities at considered time intervals were also reported.

Laminar Flame Speed Measurements of Hydrogen/Natural Gas Mixtures for Gas Turbine Applications

2021 ◽  
Author(s):  
Gihun Kim ◽  
Ritesh Ghorpade ◽  
Subith S. Vasu
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Nox Reduction ◽  
Pressure Rise ◽  
Initial Pressure ◽  
Chemical Kinetic ◽  
Experimental Conditions ◽  
Fuel Blend

Abstract Due to the increasingly challenging carbon emission reduction targets, hydrogen-containing fuel combustion is gaining the energy community’s attention, as highlighted recently in the U.S. Department of Energy’s (DOE) Hydrogen Program Plan [1]. Though fundamental and applied research of hydrogen-containing fuels has been a topic of research for several decades, there are knowledge-gaps and unexplored fuel blend combustion characteristics at conditions relevant to modern gas turbine combustors. Hydrogen will be burned directly or as mixtures with natural gas (NG) and/or ammonia (NH3) in these devices. Fundamental research on the combustion of hydrogen (H2) containing fuels is still essential, especially to overcome or accurately predict challenges such as nitrogen oxides (NOx) reduction and flashback and develop fuel flexible combustors for a prosperous hydrogen economy. We focused our investigation on a natural gas and hydrogen mixture. Measurements of laminar burning velocity (LBV) are necessary for these fuels to understand their applicability in the turbines and other engines. In this study, the maximum rate of pressure rise and LBV of methane (CH4), CH4/H2, natural gas, and natural gas/H2 mixture were measured in synthetic air. The experimental conditions were at an initial pressure of 1 atm and an initial temperature of 300 K. A realistic natural gas composition from the field was used in this study and consisted of CH4 and other alkanes. The experimental data were compared with simulations carried out with detailed chemical kinetic mechanisms.

Numerical study of pressure and composition influence on laminar flame propagation in nitrogen-diluted H2-O2 mixtures

2020 ◽  
Vol 65 (6) ◽  
pp. 529-537
Author(s):  
Domnina RAZUS ◽  
◽  
Maria MITU ◽  
Venera GIURCAN ◽  
Codina MOVILEANU ◽  
...  
Keyword(s):  
Flame Propagation ◽  
Laminar Flame ◽  
Numerical Study
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