scholarly journals NUMERICAL SIMULATION ON THE EFFECT OF CONCENTRATION ON PREMIXED CH4/CO2/AIR EXPLOSION CHARACTERISTICS

2019 ◽  
Vol 5 (1) ◽  
pp. 39-47
Author(s):  
Nur Aqidah Muhammad Harinder Khan ◽  
Siti Zubaidah Sulaiman ◽  
Izirwan Izhab ◽  
Siti Kholijah Abdul Mudalip ◽  
Rohaida Che Man ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Maximum Rate ◽  
Pressure Rise ◽  
Spherical Vessel ◽  
Explosion Pressure ◽  
Flame Acceleration ◽  
Explosion Overpressure ◽  
Pressure Development ◽  
Air Explosion ◽  
Rich Mixtures

In this study, a numerical simulation on the premixed CH4/CO2/Air (methane/carbon dioxide/air) mixture explosion characteristics was conducted by using the Flame Acceleration Simulator (FLACs) software. The domain used in the 20 L spherical vessel with 0.808 m diameter. The effect of various equivalence ratios on the explosion characteristics such as the explosion pressure, Pex, maximum explosion overpressure, Pmax, the maximum rate of the pressure rise, (dP/dt)max and gas deflagration index, KG, were studied. For this purpose, the mixture concentrations range from equivalence ratio (ER) 0.8 to 1.5 (9.6 to 18% vol/vol) were considered. From this study, the explosion pressure, Pex, maximum explosion overpressure, Pmax, and the maximum rate of pressure rise, (dP/dt)max, at various ER was the maximum at a slightly rich concentration (ER=1.2). At lean and rich mixtures, the Pex, Pmax, (dP/dt)max and KG decreases. It can be said that, at ER=1.2, the role of thermal-diffusive instability and its effect on the flame speed during the pressure development process had causes the diffused methane, CH4, to react further into the flame front, which significantly increases the mixture mass burning rate and flame was also found to propagates the fastest at ER=1.2 due to the incompletecombustion process caused by the insufficient and excess CH4 present in the lean and rich mixtures. The CH4/CO2/air mixtures studied in this study were also found to have the highest level of hazard potential when exploded.

The Explosion Severity of Biogas(CH4-CO2)/Air Mixtures in a Closed Vessel

2019 ◽  
Vol 964 ◽  
pp. 33-39
Author(s):  
Nur Aqidah Muhammad Harinder Khan ◽  
Siti Zubaidah Sulaiman ◽  
Izirwan Izhab ◽  
Siti Kholijah Abdul Mudalip ◽  
Rohaida Che Man ◽  
...  
Keyword(s):  
Maximum Rate ◽  
Equivalence Ratio ◽  
Pressure Rise ◽  
Flammability Limit ◽  
Flammability Limits ◽  
Spherical Vessel ◽  
Suppression Effect ◽  
Explosion Overpressure ◽  
Deflagration Index ◽  
Lower Flammability Limit

Biogas which consists of methane (CH4) and carbon dioxide (CO2) could explode when diluted to a certain degree with air in the presence of ignition source. The maximum explosion overpressure (Pmax), the maximum rate of pressure rise (dP/dt)max, flammability limits, and deflagration index are the most important explosion severities parameters to characterize the risk of explosion. In this research paper, the effect of equivalence ratio (ER) of biogas/air mixtures and the effect of CO2 concentrations presence in biogas were studied in a 20 L spherical vessel. The values of Pmax and (dP/dt)max of biogas/air mixtures were more severe at ER 1.2. At various CO2 content, Pmax and (dP/dt)max of biogas/air mixtures were the least affected at 45% vol/vol of CO2. On the other hand, deflagration index (KG) of biogas/air mixtures trend was the most severe at 35% vol/vol of CO2 content despite the lowest Pmax and (dP/dt)max at 45% vol/vol of CO2 content. The lowest values in Pmax and (dP/dt)max were due to the diffusivity properties of CH4 that had surpassed the CO2 suppression effect. Furthermore, the presence of CO2 in biogas/air mixtures had increased the upper flammability limit and lower flammability limit of biogas.

scholarly journals Explosion Characteristics of Propanol Isomer–Air Mixtures

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1574 ◽  
Author(s):  
Jan Skřínský ◽  
Tadeáš Ochodek
Keyword(s):  
Maximum Rate ◽  
Pressure Rise ◽  
Spherical Vessel ◽  
Explosion Pressure ◽  
Pressure Time ◽  
Vessel Volume ◽  
Deflagration Index ◽  
Pressure Maximum ◽  
Series Of Experiments ◽  
Effects Of Temperature

This paper describes a series of experiments performed to study the explosion characteristics of propanol isomer (1-propanol and 2-propanol)–air binary mixtures. The experiments were conducted in two different experimental arrangements—a 0.02 m3 oil-heated spherical vessel and a 1.00 m3 electro-heated spherical vessel—for different equivalence ratios between 0.3 and 1.7, and initial temperatures of 50, 100, and 150 °C. More than 150 pressure–time curves were recorded. The effects of temperature and test vessel volume on various explosion characteristics, such as the maximum explosion pressure, maximum rate of pressure rise, deflagration index, and the lower and upper explosion limits were investigated and the results were further compared with the results available in literature for other alcohols, namely methanol, ethanol, 1-butanol, and 1-pentanol. The most important results from evaluated experiments are the values of deflagration index 89–98 bar·m/s for 2-propanol and 105–108 bar·m/s for 1-propanol/2-propanol–air mixtures. These values are used to describe the effect of isomer blends on a deflagration process and to rate the effects of an explosion.

Numerical Simulation on the Influence of Flammable Gas Concentration on Explosion Peak Pressure

2014 ◽  
Vol 1010-1012 ◽  
pp. 1531-1534
Author(s):  
Xiao Feng Ma
Keyword(s):  
Numerical Simulation ◽  
Peak Pressure ◽  
Gas Concentration ◽  
Explosion Pressure ◽  
Flammable Gas ◽  
Explosion Overpressure ◽  
Fluent Software

This paper simulates the alternation of the maximum explosion overpressure on the different condition of the concentration based on the fluent software. The results show the maximum explosion overpressure increases in the earlier stage and then decreases in the later stage because of the different flammable gas concentration: the maximum explosion overpressure enhanced in 6% gas concentration and drops in 12% gas concentration; it augments in 6% gas concentration and drops in 12% gas concentration with the joining of the hydrogen; the explosion pressure peaked just at the 9% concentration of the flammable gas.

Pressure and flow propagation rule beyond original premixed area of methane-air in tunnel

2014 ◽  
Vol 24 (8) ◽  
pp. 1626-1635 ◽  
Author(s):  
Qi Zhang ◽  
Qiuju Ma
Keyword(s):  
Numerical Simulation ◽  
Flame Propagation ◽  
Volume Fraction ◽  
Ignition Point ◽  
Content Type ◽  
Explosion Overpressure ◽  
Air Explosion ◽  
Propagation Rule ◽  
Flow Propagation ◽  
Propagation Rules

Purpose – Whether a fire can be initiated in an explosion accident depends on the explosion and deflagration process. In the methane-air explosion in a tunnel, the flame accelerates from the ignition point. However, where it begins to decelerate is not clear. The purpose of this paper is to examine the explosion overpressure, flow and flame propagation beyond the premixed area of methane-air in a tunnel. Design/methodology/approach – The numerical simulation was used to study the explosion processes of methane-air mixtures in a tunnel. Based on the numerical simulation and its analysis, the explosion overpressure, flow and flame propagation rules beyond the premixed area were demonstrated for a methane-air explosion. Findings – The peak overpressure of methane-air mixture explosion was observed to reach its maximum beyond the original premixed area of methane-air. The hazardous effects beyond the premixed area may be stronger than those within the premixed area for a methane-air explosion in a tunnel. Under the conditions of this study, the ratio between the length of combustion area (40 m) and that of original premixed area (28 m) reaches 1.43. Originality/value – Little attention has been devoted to investigating the explosion overpressure, flow and flam propagations beyond the original premixed area of methane-air in a tunnel. Based on the numerical simulation and the analysis, the propagation rule of overpressure wave and flow inside and outside the space occupied by methane/air mixture at the volume fraction of 9.5 percent in a tunnel were obtained in this work.

scholarly journals Determination of the Explosion Characteristics of Wheat Flour

2017 ◽  
Vol 25 (40) ◽  
pp. 9-16
Author(s):  
Richard Kuracina ◽  
Zuzana Szabová ◽  
Denisa Pangrácová ◽  
Karol Balog
Keyword(s):  
Wheat Flour ◽  
Maximum Rate ◽  
Pressure Rise ◽  
Explosion Pressure ◽  
Maximum Explosion Pressure ◽  
Dust Clouds ◽  
Maximum Value ◽  
Flour Dust ◽  
Explosion Limit

Abstract The article deals with the measurement of explosion characteristics of wheat flour. The measurements were carried out according to STN EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds, the maximum rate of explosion pressure rise according to STN EN 14034-2+A1:2012 Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds and LEL according to STN EN 14034-3+A1:2011 Determination of explosion characteristics of dust clouds: Determination of the lower explosion limit LEL of dust clouds. The testing of explosions of wheat flour dust clouds showed that the maximum value of the pressure was reached at the concentrations of 600 g/m3 and its value is 8.32 bar/s. The fastest increase of pressure was observed at the concentration of 750 g/m3 and its value was 54.2 bar/s.

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