scholarly journals Temperature effect on explosion parameters of hydrogen-air deflagrations in presence of water vapor

2016 ◽  
Vol 7 (3) ◽  
pp. 39-44
Author(s):  
Marcin Grabarczyk ◽  
Mateusz Żbikowski ◽  
Łukasz Mężyk ◽  
Andrzej Teodorczyk
Keyword(s):  
Water Vapor ◽  
Initial Temperature ◽  
Volume Fraction ◽  
Initial Conditions ◽  
Initial Pressure ◽  
High Water ◽  
Maximum Pressure ◽  
Explosion Pressure ◽  
Maximum Explosion Pressure ◽  
And Shifts

Results of investigation of hydrogen-air deflagrations phenomenon in closed vessel in various initial temperatures and volume fraction of water vapor are presented in following paper. Tests were performed in apparatus which construction complies with EN 15967 recommendations—20-litre sphere. Studied parameters were explosion pressure (Pex) and maximum explosion pressure (Pmax). Defining the influence of the initial conditions (temperature and amount of water vapor) on the maximum pressure of the hydrogen-air deflagration in a constant volume was the main aim. Initial temperatures were equal to 373K, 398K and 413K. Initial pressure was ambient (0.1 MPa). Hydrogen volume fraction differed from 15% to 80%, while humidity volume fraction from 0% to 20%. Ignition source was placed in geometrical center of testing chamber and provided energy between 10-20J from burnout of fuse wire with accordance to abovementioned standard. Common features of all experimentally obtained results were discussed. Maximum explosion pressure (Pmax) decreases with increasing the initial temperature. Furthermore, addition of the water vapor for constant initial temperature decreases value of Pmax and shifts the maximum peak to the direction of lean mixtures. Data provided in paper can be useful in assessment of explosion risk of industry installations working with hydrogen-air atmospheres with high water vapor addition.

scholarly journals The dissociation of carbon dioxide at high temperatures

1927 ◽  
Vol 115 (771) ◽  
pp. 318-333 ◽  
Keyword(s):  
Carbon Dioxide ◽  
High Temperatures ◽  
Combustion Engine ◽  
Initial Pressure ◽  
Simple Relation ◽  
Maximum Temperature ◽  
Maximum Pressure ◽  
Complete Combustion ◽  
Explosion Pressure ◽  
Rich Mixture

The power of an internal combustion engine is greatest when operating with a “rich” mixture, that is to say, with a mixture which contains more fuel than is necessary for complete combustion. Similarly, it is found that if mixtures of carbon monoxide and air in varying proportions are exploded in a closed bomb at constant initial temperature and pressure, the explosion pressure is greatest when the ratio CO/O 2 is greater than 2. These phenomena are known to be connected with the dissociation of carbon dioxide at high temperatures, for if there were no dissociation we should expect the explosion pressure to be greatest when CO/O 2 = 2. No attention appears, however, to have been paid to the position of the maximum. It can be shown in the following way that there is a very simple relation between the composition of the mixture giving maximum pressure on explosion, and the dissociation of carbon dioxide at the maximum explosion temperature. Let the initial composition be represented by the expression 2 (1 + a ) CO + O 2 + b N 2 (Total mols = 3 + 2 a + b ), and let P i , T i represent the initial pressure and temperature; P e the maximum pressure observed after explosion, and T e the corresponding maximum temperature.

The Effects of Initial Conditions on the Composition of the On-Board Fuel Reformation Chamber in an HCCI Engine

2015 ◽  
Vol 733 ◽  
pp. 219-224
Author(s):  
Chun Hua Zhang ◽  
Le Xue
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Initial Temperature ◽  
Initial Conditions ◽  
Initial Pressure ◽  
Compression Ignition ◽  
Fuel Reforming ◽  
Hcci Engine ◽  
Main Species ◽  
Fuel Reformation ◽  
Homogeneous Charge

Based on the CHEMKIN software, a model of the reforming chamber was built to simulate the on-board fuel reforming process in a Homogeneous Charge Compression Ignition (HCCI) engine. The effects of the initial pressure and temperature of the chamber on the reformed gas were studied. The results show that the main species in the reformed gas are H2 and CO. This paper investigated the effect of initial temperature on the reformed gas, in order to get the optimum initial temperature. Under the optimum initial temperature (1300 K), some important conclusions have been drawn by changing initial pressures of the chamber. Initial pressure may have great effect on other species, but has a small effect on mole fractions of H2 and CO. By comparing the concentrations of H2 and CO between low and high initial pressures under the optimum initial temperature, it can be concluded that H2 and CO are still the main species in the reformed gas.

Indonesia Coal Explosive Characteristic of Pulverized Coal in Experiment

2011 ◽  
Vol 418-420 ◽  
pp. 706-711
Author(s):  
Jia Hu Li ◽  
Li Bao Yin
Keyword(s):  
Pulverized Coal ◽  
Maximum Pressure ◽  
Explosion Pressure ◽  
Maximum Explosion Pressure

In this paper, the explosion experiments of Indonesia pulverized coal cloud are carried out. The pressure histories are recorded. The maximum pressure, the maximum pressure rising rates and the explosion time are analysed based on the pressure histories. The experiment results indicate that with the increase of pulverized coal concentration, the maximum explosion pressure and maximum pressure rising rate at first increases, then decreases, and the explosion time is contrary to that.

scholarly journals The Effect of Initial Conditions on the Laminar Burning Characteristics of Natural Gas Diluted by CO2

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2892 ◽  
Author(s):  
Zhiqiang Han ◽  
Zhennan Zhu ◽  
Peng Wang ◽  
Kun Liang ◽  
Zinong Zuo ◽  
...  
Keyword(s):  
Natural Gas ◽  
Dilution Rate ◽  
Initial Temperature ◽  
Initial Conditions ◽  
Burning Velocity ◽  
Initial Pressure ◽  
Chemical Kinetic ◽  
Laminar Burning Velocity ◽  
Flame Instability ◽  
Highly Correlated

The initial conditions such as temperature, pressure and dilution rate can have an effect on the laminar burning velocity of natural gas. It is acknowledged that there is an equivalent effect on the laminar burning velocity between any two initial conditions. The effects of initial temperatures (323 K–423 K), initial pressures (0.1 MPa–0.3 MPa) and dilution rate (0–16%, CO2 as diluent gas) on the laminar burning velocity and the flame instability were investigated at a series of equivalence ratios (0.7–1.2) in a constant volume chamber. A chemical kinetic simulation was also conducted to calculate the laminar burning velocity and essential radicals’ concentrations under the same initial conditions. The results show that the laminar burning velocity of natural gas increases with initial temperature but decreases with initial pressure and dilution rate. The maximum concentrations of H, O and OH increase with initial temperature but decrease with initial pressure and dilution rate. Laminar burning velocity is highly correlated with the sum of the maximum concentration of H and OH.

scholarly journals Influence of acetylene on methane–air explosion characteristics in a confined chamber

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jinzhang Jia ◽  
Jinchao Zhu ◽  
Wenxing Niu ◽  
Jing Zhang
Keyword(s):  
Free Radicals ◽  
Volume Fraction ◽  
Pressure Rise ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Maximum Pressure ◽  
Mixed Gas ◽  
Explosion Pressure ◽  
Combustion Modes ◽  
The Impact

AbstractTo study the impact of acetylene on methane explosions, the safe operation of coal mines should be ensured. In this paper, a 20 L spherical tank was used to study the explosive characteristics of acetylene–methane–air mixture. In addition, the GRI-Mech3.0 mechanism was used to study the chemical kinetic mechanism for the mixed gas, and the effect of adding acetylene on the sensitivity of methane and the yield of free radicals was analysed. The results show that acetylene can expand the scope for methane explosion, lower the lower explosion limit, and increase the risk of explosion. Acetylene increases the maximum explosion pressure, laminar combustion rate and maximum pressure rise rate for the methane–air mixture while shortening the combustion time. Three combustion modes for the acetylene–methane–air mixture were determined: methane-dominated, transitional and acetylene-dominated combustion modes. Chemical kinetic analysis for the mixed gas shows that as the volume fraction of acetylene increases, the generation rate for key free radicals (H*, O* and OH*) gradually increases, thereby increasing the intensity of the explosive reaction. The results from this research will help formulate measures to prevent coal mine explosion accidents.

Numerical simulation of the influence of water vapor on gas explosions in a high-pressure environment

2020 ◽  
Author(s):  
Li Zou ◽  
Xin Yi ◽  
Haitao Li ◽  
Xixi Liu ◽  
Jun Deng
Keyword(s):  
High Pressure ◽  
Water Vapor ◽  
Vital Role ◽  
Water Vapor Content ◽  
Explosion Pressure ◽  
Maximum Explosion Pressure ◽  
Gas Explosions ◽  
Influence Of Water ◽  
Dry Conditions ◽  
High Pressure Environment

Abstract Gas explosion seriously threaten the employees security and restrict the safe production of coal mines. Therefore, it is particularly essential to investigate the prevention and control of gas explosions. In this study, a two-dimensional numerical model of a spherical explosion tank was developed to explore the effects of water vapor on gas explosions in a high-pressure environment. Explosion parameters of 10% gas, 1 MPa pressure, and water vapor contents varying from 0% to 8% were simulated using FLUENT software. The results show that the maximum explosion pressure and temperature of the premixed gas gradually decrease with increasing water vapor content, i.e., when the water vapor content is increased from 0% to 8%, the maximum explosion pressure and temperature of the gas mixture decreases from 2.52 MPa and 2092 K under dry conditions to 1.62 MPa and 1714 K with 8% water vapor. The attenuation amplitude is also reduced upon the addition of steam. Water vapor in premixed gas therefore plays a vital role in suppressing gas explosions.

Experimental Study of Explosion Pressure Characteristics of Methane under High Temperature Conditions

2014 ◽  
Vol 687-691 ◽  
pp. 148-152 ◽  
Author(s):  
Run Zhi Li ◽  
Rong Jun Si ◽  
Yan Song Zhang
Keyword(s):  
Environmental Temperature ◽  
Pressure Rise ◽  
Test System ◽  
Coal Bed ◽  
Maximum Pressure ◽  
Explosion Pressure ◽  
Pressure Rise Rate ◽  
Maximum Explosion Pressure ◽  
Rise Rate ◽  
Pressure Characteristics

Methane explosion pressure characteristics under the condition of different temperatures (25°C-200 °C) were studied by the special environment 20L explosion characteristics test system. By the experimental results, in the case of other conditions unchanged, with the increase of environmental temperature, the maximum explosion pressure of the optimum explosion concentration decrease, the maximum explosion pressure and the reciprocal of environmental temperature show linear attenuation law, the maximum pressure rise rate is not influenced by environmental temperature basically; Outside the scope of explosion limits at normal temperature and pressure, with the increase of environmental temperature, no explosion methane-air mixture are explosive gradually, the maximum explosion pressure and maximum pressure rise rate are in the relationship of different exponential growth with the increase of ambient temperature. The conclusions provide an important theoretical basis for prevent mine gas explosion accidents and coal bed methane safely use.

Effect of Hydrogen Addition into Methane-Air Mixture on Combustion Pressure

2012 ◽  
Vol 433-440 ◽  
pp. 166-171
Author(s):  
Xiao Lei Bai ◽  
Anna Zheng ◽  
Na Sun ◽  
Hong Guang Zhang ◽  
Xue Jiao Han
Keyword(s):  
Maximum Rate ◽  
Initial Temperature ◽  
Initial Conditions ◽  
Pressure Rise ◽  
Initial Pressure ◽  
Flame Propagation Velocity ◽  
Appearance Time ◽  
Blend Ratio ◽  
Combustion Pressure ◽  
Hydrogen Addition

To get the effect of hydrogen addition under different initial pressures, different initial temperatures and different initial equivalence ratios on combustion pressure, relevant tests of methane-hydrogen-air mixture have been carried out in constant volume combustion bomb. The results showed that higher initial temperature and lower initial pressure is helpful to get higher flame propagation velocity while other initial conditions keep invariable; as hydrogen blend ratio increases, both maximum combustion pressure and maximum rate of pressure rise increase, with the appearance time obviously earlier and cycle-to-cycle variation obviously lower.

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