Experimental and Numerical Study of Flame Propagation of Biofuels/Oxidizers/Inert Mixtures (Volume II)

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Environmental and Green Processes".

Deadline for manuscript submissions: 5 November 2024 | Viewed by 4424

Special Issue Editor

Institute of Physical Chemistry, Romanian Academy, 202 Spl. Independentei, 060021 Bucharest, Romania
Interests: combustion of liquid and gaseous fuels; explosion risk; explosion protection; safety; explosion parameters; flame propagation; chemical kinetics; ignition
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

You are invited to contribute to a Special Issue of Processes on “Experimental and Numerical Study of Flame Propagation of Biofuels/Oxidizers/Inert Mixtures”. Biofuels have recently attracted increased attention for applications in energy generation and transportation.

The flame propagation of fuels/oxidizers/inert mixtures is studied in order to estimate their normal burning velocity, which is considered to be a fundamental property of a fuels/oxidizers/inert mixtures, depending on the fuel type, oxidizer type, equivalence ratio, pressure, temperature and mass fraction of any gases, with a significant impact on many aspects of combustion. The laminar burning velocity is a key property of flammable gaseous mixtures characterizing the fuel reactivity in the presence of an oxidizer, which provides meaningful information regarding the reactivity and the exothermicity of the system. It is a most useful parameter for the safe design of equipment and processes. The normal burning velocities are also used for predicting the emissions and performance of internal and external combustion systems. In basic research, the laminar burning velocity is a key parameter for validating models of combustion wave propagation, which take detailed chemical kinetics into account.

This Special Issue aims to present high-quality research studies addressing challenges in the broad area of the flame propagation of biofuels/oxidizers/inert mixtures. Recent research involving experimental and numerical studies of the burning velocities of biofuels/oxidizers/inert mixtures is highly encouraged, but other relevant topics are also of interest.

Dr. Maria Mitu
Guest Editor

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Keywords

  • combustion of fuels
  • explosion
  • biofuels
  • explosion parameters
  • burning velocities
  • simulations

Published Papers (4 papers)

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Research

20 pages, 19277 KiB  
Article
Study on Oxy-Methane Flame Stability in a Cylindrical Porous Medium Burner
by Mingjian Liao, Zhu He, Xiong Liang, Tat Leung Chan, Yawei Li and Xuecheng Xu
Processes 2023, 11(7), 2182; https://doi.org/10.3390/pr11072182 - 21 Jul 2023
Cited by 1 | Viewed by 891
Abstract
Combustion in a porous medium can be beneficial for enhancing reaction rate and temperature uniformity. Therefore, considering the combination with oxy-fuel combustion can address some shortcomings in oxy-fuel burners, a cylindrical two-layer porous burner model is established based on OpenFOAM in this paper. [...] Read more.
Combustion in a porous medium can be beneficial for enhancing reaction rate and temperature uniformity. Therefore, considering the combination with oxy-fuel combustion can address some shortcomings in oxy-fuel burners, a cylindrical two-layer porous burner model is established based on OpenFOAM in this paper. A two-temperature equation model is adopted for the simulation of the heat transfer process. The CH4 skeletal kinetic mechanism is adopted for complex chemistry integration based on OpenSMOKE++. Corresponding experimental methods were used for complementary studies. The walls of the burner are wrapped with three types of thermal insulation materials to present different levels of heat loss. The results show that considering the convection and radiative heat loss of the burner wall, the temperature near the wall is reduced by more than 300 K compared to the adiabatic condition. As a result, the flame propagation speed and CO oxidation rate slowed down. The stable range will be destructively narrowed by more than 50%, and CO emissions will increase by more than 10 times. These defects will be aggravated by increasing the diameter of the burner. It is observed that when the diameter of the burner increases from the initial 5 cm to 10 cm, the effect of heat loss on the stable range is insignificant. Full article
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13 pages, 1579 KiB  
Article
Flammability Properties of the Pyrolysis Gas Generated from Willow Wood
by Maria Mitu, Domnina Razus, Dorin Boldor and Cosmin Marculescu
Processes 2023, 11(7), 2103; https://doi.org/10.3390/pr11072103 - 14 Jul 2023
Cited by 3 | Viewed by 1000
Abstract
Willow wood presents a real interest for biomass pyrolysis due to its fast growth, renewability, and high energy density. Following the pyrolysis of willow wood in an inert atmosphere, a multi-fuel gaseous mixture was obtained, with the following composition (by volume): 38.20% CO/21.87% [...] Read more.
Willow wood presents a real interest for biomass pyrolysis due to its fast growth, renewability, and high energy density. Following the pyrolysis of willow wood in an inert atmosphere, a multi-fuel gaseous mixture was obtained, with the following composition (by volume): 38.20% CO/21.87% H2/17.44% CH4/1.15% O2/17.15% CO2/4.19% N2. The propagation of laminar premixed flames in these multifuel mixtures with air was investigated numerically for initial temperatures from 298 to 500 K, initial pressures from 1 to 20 bar, and fuel equivalence ratios between 0.60 and 2.00. The combustion of these gaseous mixtures as free laminar premixed flames was simulated by means of the INSFLA package and an extended reaction mechanism with 592 elementary reactions and 53 species. The modelling of the gas-phase combustion delivered several important parameters: the laminar burning velocities, Su, the maximum flame temperatures, Tfl,max, the flame front thicknesses, dfl, and the peak concentrations of the main reaction intermediates. The obtained parameters, discussed in correlation with the initial pressure and temperature, afforded the determination of the overall activation parameters of multifuel oxidation with air. Full article
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11 pages, 1076 KiB  
Article
Experimental Study on Gas Explosion Propagation in Porous Metal Materials
by Zhenzhen Jia and Qing Ye
Processes 2023, 11(7), 2081; https://doi.org/10.3390/pr11072081 - 12 Jul 2023
Cited by 1 | Viewed by 882
Abstract
Serious damage and large losses often result from gas explosions in coal mining. However, porous metal materials can suppress a gas explosion and its propagation. Therefore, a gas explosion and its propagation suppression characteristics of porous metal materials are analyzed theoretically. According to [...] Read more.
Serious damage and large losses often result from gas explosions in coal mining. However, porous metal materials can suppress a gas explosion and its propagation. Therefore, a gas explosion and its propagation suppression characteristics of porous metal materials are analyzed theoretically. According to the propagation characteristics of a gas explosion in duct, a gas-explosion experiment system with porous metal material (steel wire mesh) is constructed in this paper, and the propagations of explosion wave and flame in porous metal materials are experimentally studied. The study results show that the flame propagation velocity and overpressure of explosion wave are related to the length and layer number of porous metal materials. When the gas explosion propagates a certain distance in porous metal materials, the flame and explosion wave begin to be attenuated. The longer the length of porous metal material is, the better the attenuation effect is. At the same time, the more layer numbers, the better the attenuation effect is. In this experiment, the maximum decreases of explosion wave overpressure and flame propagation velocity are 84% and 91%, respectively. The attenuation of the explosion wave overpressure and the flame propagation velocity has synchronism and correspondence during gas explosion propagation in porous metal materials. The experimental results show the porous metal material has a good suppression effect on gas explosion propagation. The study results can provide an experimental basis for the development of gas explosion propagation suppression technology and devices, and have a great practical significance for the prevention and control of a gas explosion disaster. Full article
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19 pages, 14095 KiB  
Article
Influence of Wall Heat Effect on Gas Explosion and Its Propagation
by Zhenzhen Jia, Qing Ye and Zhuohua Yang
Processes 2023, 11(5), 1326; https://doi.org/10.3390/pr11051326 - 25 Apr 2023
Cited by 1 | Viewed by 1290
Abstract
The gas explosion process in pipes is often accompanied by an intense wall heat effect. A considerable part of the explosion energy is dissipated, and the process of gas explosion and its propagationis affected. In order to study the influence of wall heat [...] Read more.
The gas explosion process in pipes is often accompanied by an intense wall heat effect. A considerable part of the explosion energy is dissipated, and the process of gas explosion and its propagationis affected. In order to study the influence of wall heat effect on gas explosion and its propagation, numerical models of gas explosion in pipes with different adiabatic degrees were established by ANSYS/LS-DYNA. The propagation process of gas explosion in pipes under the influence of the wall heat effect was numerically simulated and analyzed, and the thermal stress and temperature distribution of pipes with different adiabatic degrees were studied. The results show that with a decrease in pipe insulation, the wall heat effect increases, the heat loss of gas explosion increases, and the overpressurizationof the shock wave, the explosion intensity, and the thermal stress of the pipe wall are significantly reduced. The results indicate that the wall heat effect can weaken the gas explosion and its propagation. At the same time, it is found that the influence of the wall heat effect on the initiation section is greater than that on other positions of the pipe. With the decrease in the heat effect of the pipe wall, the heat loss of the wall decreases, the temperature difference between the inner and outer wall surfaces expands, and the total energy released by the gas explosion increases. The released energy is used to heat and compress the unburned gas, resulting in a more intense explosion reaction and a substantial increase in the temperature of the explosive gas. Therefore, it can be seen that the wall heat effect has an important influence on the gas explosion and its propagation. The influence of wall adiabatic condition on gas explosion with a higher combustion level is greater than the influence on gas explosion with low combustion levels. Full article
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