Efficiency of heterogeneous inhibition of active flame centers by fire extinguishing powder particles under non-stationary interaction conditions

2020 ◽  
pp. 63-70
Author(s):  
Анатолий Ильич Кицак
Keyword(s):  
Inhibition Efficiency ◽  
Interaction Time ◽  
Maximum Effect ◽  
Stationary Mode ◽  
Active Centers ◽  
Fire Extinguishing ◽  
Active Particles ◽  
Powder Particles ◽  
Stationary Conditions ◽  
Inhibition Reaction

Предложена модель механизма гетерогенного ингибирования активных центров пламени частицами огнетушащего порошка общего назначения при нестационарном взаимодействии. Проведена оценка эффективности гетерогенного ингибирования активных центров пламени частицами огнетушащего порошка в нестационарном режиме их взаимодействия. Полученные результаты могут быть использованы для оптимизации условий и режимов подачи огнетушащего порошка в зону горения в целях достижения максимального эффекта тушения пожара. The relevance of the work is due to the need to improve the efficiency of powder fire extinguishing systems. The aim of this work is to evaluate the effectiveness of the mechanism of heterogeneous inhibition of active flame centers by particles of fire extinguishing powder under non-stationary conditions of interaction. It was achieved by the method of theoretical modeling. There are obtained theoretical dependences of the reaction rate of heterogeneous inhibition of active flame centers by fire extinguishing powder particles on their dispersed and dynamic characteristics under non-stationary conditions of active particles interaction with the inhibitor surface. The efficiency of heterogeneous inhibition of active flame centers by fire extinguishing powder particles in a non-stationary mode of their interaction was evaluated. Fire fighting with fire extinguishing powder under non-stationary conditions is more effective the smaller the effective size of powder particles, the effective duration of the inhibition reaction and the longer the interaction time of powder particles with active flame centres. It was established that inhibition efficiency depends either on the kinetic parameters of active centers and disperse characteristics of the powder particles or on the ratio of interaction time of powder particles with the active centers as well as the characteristic duration of inhibition reaction. The results obtained allow optimizing the conditions and modes of fire extinguishing powder supply to the combustion zone in order to achieve the maximum effect of fire extinguishing.

scholarly journals Efficiency of fire extinguishing with general purpose fire extinguishing powder in case of non-stationary interaction of its particles with burning material

2020 ◽  
Vol 65 (4) ◽  
pp. 476-486
Author(s):  
A. I. Kitsak
Keyword(s):  
Heat Transfer ◽  
Combustion Zone ◽  
General Purpose ◽  
Active Centers ◽  
Theoretical Dependence ◽  
Fire Extinguishing ◽  
Exchange Processes ◽  
Powder Particles ◽  
Stationary Conditions ◽  
Inhibition Reaction

Evaluation of the effectiveness of fire extinguishing by jet systems of powder fire extinguishing in conditions of non-stationary heat exchange processes and heterogeneous inhibition of active flame centers by powder particles was the aim of the work. The theoretical dependence of the amount of heat, absorbed by the particles of fire extinguishing powder, and the reaction rate of heterogeneous active centers of flame, inhibiting them, in non-stationary conditions of heat transfer, as well as inhibition reaction for fire extinguishing ink jet systems were obtained. The extinguishing of a flame with a fire extinguishing powder under non-stationary conditions is more effective, the smaller is the effective size of the powder particles, the longer is their stay in the combustion zone, and the shorter are the characteristic times of heat transfer and inhibition reaction. Comparison of the estimates of the characteristic duration of heat transfer and inhibition reaction for widely used fire extinguishing powders has shown a large inertia of the thermal mechanism of fire extinguishing, which greatly reduces its effectiveness at high speeds of powder particles in the combustion zone.

scholarly journals Modeling of the mechanism of heterogeneous inhibition of the active flame centers of a jet burning system by fire extinguishing powder particles

2021 ◽  
Vol 66 (2) ◽  
pp. 250-256
Author(s):  
A. I. Kitsak
Keyword(s):  
Convective Motion ◽  
Combustion Products ◽  
Convective Transport ◽  
Fire Extinguishing ◽  
Hazardous Chemical ◽  
Active Particles ◽  
Molecular Transfer ◽  
Flame Suppression ◽  
Powder Particles ◽  
Kinetics Of

The relevance of the work is due to the lack of a physical interpretation of the process of extinguishing jet burning systems with fire extinguishing powders, which is important for ensuring effective fire extinguishing at gas and oil complexes and hazardous chemical industries. A mathematical model of the reaction kinetics of heterogeneous inhibition of active flame centers of a jet burning system by fire extinguishing powder particles in an unsteady mode is considered in the approximation of a purely molecular transfer of matter in the reaction zone. The regularities of the mechanism of heterogeneous inhibition of the active flame centers by the particles of the extinguishing powder under conditions when the active particles of the combustion products participate not only in diffuse, but also in convective transport are established. It is shown, that the convective motion of the active flame centers increases the reaction rate of heterogeneous inhibition of their particles of the extinguishing agent. The results obtained allow us to optimize the conditions for the supply of fire extinguishing powder to the jet burning medium for effective flame suppression.

scholarly journals Distribution of fire extinguishing powder fractions in simulated non-stationary gas stream

2020 ◽  
Vol 28 (6) ◽  
pp. 80-88
Author(s):  
A. S. Polyakov ◽  
D. F. Kozhevin ◽  
A. S. Konstantinova
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Fractional Composition ◽  
Chemical Properties ◽  
Fire Extinguisher ◽  
Fire Extinguishing ◽  
Powder Samples ◽  
Powder Particles ◽  
Physical And Chemical ◽  
Flow Cross

Introduction. The article presents the regularities of particles distribution of fire extinguishing powder fractions in the cross sections of the simulated unregulated non-stationary gas stream. The distance from the fire extinguisher cut which the stream is most stable in terms of the content of fire extinguishing powder particles is determined. There are works in which the physical and chemical properties of fire-extinguishing powders are considered, the movement of powder particles in the stream is modeled, the influence of the fractional composition of the powder on its fire-extinguishing capacity is determined. At the same time distribution of powder fractions during its movement in gas-powder stream is not considered. The purpose of the present work is to find ways to improve the efficiency of powder extinguishers by controlling the distribution of powder fractions in a non-stationary gas stream.Materials and methods. Experimental study installation consists of coordinate table oriented perpendicular to gas-powder stream direction. The table is equipped with collectors that allow to collect powder samples at control points of flow cross-section. Food sodium chloride (further — salt) was used in the experiment. Its characteristics correspond to GOST R 53280.4–2009 and allow to apply it as a model. The coordinate table was installed sequentially at a distance of 500, 750, 1000 and 1250 mm from the fire extinguisher cut. Next, a shot of salt with a known fractional composition was supplied with a fire extinguisher model to a coordinate table and the retained powder samples were taken. The mass and fractional composition of the samples collected by each collector were then determined. Stability of the particle distribution in the gas stream by statistical analysis (by Fischer’s criterion) was measured for their content.Conclusions. Regularities of different fire extinguishing powder fractions distribution in cross section of non-regulated non-stationary gas stream are established and analytically described. These regularities can be used in finding ways to regulate fire extinguishing powder fractions during fire extinguishing. The most representative and stable in accuracy (correctness and precision) results of powder fractions content in the section of non-stationary gas stream at a distance of 1000 mm from the fire extinguisher cut. This should be taken into account in further research.

Acridine as Effective Corrosion Inhibitor for Hot Dipped Coatings on Steels in Diluted HCl Solution

2009 ◽  
Vol 79-82 ◽  
pp. 1035-1038 ◽  
Author(s):  
Hong Ju ◽  
Tian Shu Peng ◽  
Yan Li
Keyword(s):  
Quantum Chemistry ◽  
Inhibition Efficiency ◽  
Electrochemical Measurement ◽  
Al Alloy ◽  
Quantum Chemistry Calculation ◽  
Active Centers ◽  
Coating Surface ◽  
Good Ability ◽  
Calculation Results ◽  
Chemistry Calculation

The environmental and health hazards associated with chromium-containing solution have aroused wide public concern, so attempts have been made to find alternatives for metal finishing. In the present paper, inhibition effect of acridine on corrosion of hot dipped Zn and Zn-Al alloy coatings on steels in diluted hydrochloric acid was investigated using weight loss test, electrochemical measurement, and quantum chemistry analysis. The results showed that inhibition efficiency increased with inhibitor concentration, and the highest inhibition efficiency was up to 99%. And acridine adsorbed on coating surface by chemisorption. Quantum chemistry calculation results indicated that acridine possesses planar structure with a number of active centers, and showed a good ability of electron exchange with the coating surface.

Coulostatic-Based Research on Corrosion Inhibition Mechanism of Three Inhibitors for Hot Dipped Coating Steels

2012 ◽  
Vol 229-231 ◽  
pp. 87-90
Author(s):  
Hong Ju ◽  
Yan Li
Keyword(s):  
Corrosion Inhibition ◽  
Active Sites ◽  
Inhibition Efficiency ◽  
Corrosion Current ◽  
Inhibition Mechanism ◽  
Inhibitor Concentration ◽  
Active Centers ◽  
Anodic Reaction ◽  
Tafel Slope ◽  
Inhibition Concentration

The corrosion inhibition mechanism of three inhibitors for hot dipped coating steels in HCl acid was studied by coulostatic method. The results showed that the anodic Tafel slope ba and cathodic Tafel slope bc significantly increased with increasing of corrosion inhibitor concentration. While the corrosion current density Icorr decreases with the corrosion inhibition concentration increasing. And the inhibition efficiency increased with the inhibitor concentration. The inhibiting action of these compounds were attributed to blocking of the electrode surface by adsorption through its active centers. The three inhibitors were both mixed inhibitors, and reacted as good inhibition by the adsorption of the active sites in the cathodic reaction and the anodic reaction of corrosion process.

scholarly journals Effect of cell-substrate interaction time and shearing force on adhesion of L1210 cells to collagen and glass

1984 ◽  
Vol 66 (1) ◽  
pp. 321-333
Author(s):  
H.M. Kowalczynska ◽  
M. Nowak
Keyword(s):  
Effective Interaction ◽  
Interaction Time ◽  
Serum Free Medium ◽  
Free Medium ◽  
Shearing Force ◽  
Serum Free ◽  
Substrate Interaction ◽  
L1210 Cells ◽  
Cell Substrate ◽  
Stationary Conditions

The early adhesive interaction of living cells with substrates was examined. L1210 cells were allowed to interact with collagen or glass in serum-containing medium (time of cell-substrate interaction, tint, under stationary conditions, was within 2–25 min) or in serum-free medium (tint was 5 s-15 min). The relative number A of cells adhering under stationary conditions, and remaining adherent to the substrate despite experiencing a shearing force F, was determined. The following was found for cells adherent to collagen and glass, both in the presence and absence of serum in the medium. The number A increases with the value of tint and tends to reach a plateau. The plateau value depends on adhesion conditions (presence or absence of serum). When adhesion occurred in serum-containing medium (F congruent to 0.1 X 10(−13)N), function A(tint) increased up to 15 min. The plateau values were in the ratio of 2:1 for cells adherent to collagen and glass, respectively. When adhesion took place in serum-free medium, the function A(tint) increased within the first 20 or 130s for cells adhering to glass or collagen, respectively. The value of A(tint) increased up to the effective interaction time, teff int, i.e. the time after which a plateau was reached at 100% adhesion. This meant that after tint greater than or equal to teff int all cells were in adhesion with glass and collagen despite the application of the greatest shearing force, F congruent to 2 X 10(−9)N. The values of teff int for cells adherent to collagen and glass were in the ratio of 6:1, respectively. The value of A decreases with the value of F for cells adherent to substrate in the absence of serum when tint less than teff int. The function A(F) for cells adherent to collagen and glass in the presence of serum, but not in the absence of serum, can be described by the equation: A = a/square root F + c, where a and c = constant greater than 0. The values of a were in the ratio of 2:1 for cells adherent to collagen and glass, respectively. The Brownian motion of cells interacting with both substrates in the absence of serum ceased. The times during which cell motion persisted for cells interacting with collagen and glass, respectively, were in the ratio of 2.5:1.

Modeling the reliability of decision-making in the management structure of fire and rescue units in large fires

2020 ◽  
Vol 89 ◽  
pp. 43-52
Author(s):  
A. V. Maslov ◽  
◽  
A. V. Surovegin ◽  
D. V. Tarakanov ◽  
M. O. Bakanov ◽  
...  
Keyword(s):  
Decision Making ◽  
Growth Rate ◽  
Control System ◽  
Work Experience ◽  
Training Model ◽  
Maximum Effect ◽  
Operational Experience ◽  
Probability Of Error ◽  
Fire Extinguishing ◽  
Large Fires

Introduction. The specifics of extinguishing fires in buildings and open spaces on the territory of the Russian Federation determines that a fire that has taken on a scale that allows it to be attributed to a large one is extinguished with the help of the forces and means of several fire and rescue units. In this case, a developed structure of the control system is created in order to improve the quality of management of a large number of fire and rescue units of different subordination. Goals and objectives. The purpose of the study is to analyze the structure of the control system created at large fires requiring the a significant number of fire and rescue units. To achieve the goal, it is necessary to solve the following tasks: 1) to identify the dependence of the dynamics of reliability of decision making on the experience of the operational work of fire and rescue garrison officials who perform the duties of the fire extinguishing driver.; 2) to determine the stage of accumulation of operational experience at which information, methodological and analytical support will bring maximum effect to potential fire extinguishing managers. Methods. To build the dependence of work experience and the probability of error when directing forces and means on fires, the Hala training model was used. Results and its discussion. An increase in the growth rate of decision reliability in a potential fire extinguishing supervisor is observed at the interval of operational work from 0 to 4 years, after which the growth rate decreases. Conclusions. In the characteristic dependence of the reliability of decision making on the experience of the operational work of the official performing the duties of the fire extinguishing manager, at the stage of exponential growth, the maximum effect of the positive change in the operational work experience on increasing the values of the reliability of decision making occurs. Key words: fire extinguishing, control structure, decision-making reliability.

Experimental Studies of the Electrical Breakdown of Fire Extinguishing Powders

2021 ◽  
pp. 49-55
Author(s):  
A.V. Popov ◽  
◽  
A.V. Kazakov ◽  
D.V. Bukhtoyarov ◽  
S.Yu. Khatuntseva ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Breakdown Voltage ◽  
Electrical Breakdown ◽  
Experimental Studies ◽  
Electrical Strength ◽  
Monoammonium Phosphate ◽  
Electrical Field ◽  
Fire Extinguishing ◽  
Powder Particles ◽  
Fire Extinguishers

The method for determining the breakdown voltage in the air suspension of fire extinguishing powder, simplified and more appropriate to the actual conditions of such powders use is proposed and tested. Experimental studies of the electrical breakdown of fire extinguishing powders in an alternating electrical field — homogeneous and non-homogeneous are presented. Double effect of fire extinguishing powders on the breakdown in a homogeneous electrical field in comparison with air is established. The first option: powders to a small extent complicate the breakdown (increase the breakdown voltage), which is due to the high electrical strength of solid dielectrics. The second option: powders slightly facilitate the breakdown. Presumably, this is due to the abnormally high polarizability of one of the components — monoammonium phosphate (ferroelectric). Due to the avalanche-like polarization caused by the ferroelectric, the uniformity of the field is disturbed, which reduces its electrical strength. In an inhomogeneous electric field, the breakdown voltage was about one third lower than in a homogeneous one, and exactly corresponds to the breakdown voltage of the air. In a homogeneous field between the electrodes the «bridges» of powder particles containing monoammonium phosphate appeared and continued to hang even after the breakdown. An unexpected phenomenon was revealed: a relatively weak dependence of the breakdown voltage on the presence of moisture in the extinguishing powder. It is advisable to continue research in this area. The main conclusion: fire extinguishing non-conductive powder does not participate in the electrical breakdown that goes through the air between the powder particles. In view of this, the voltage of 1 kV seems an anachronistic one, at which the use of powder fire extinguishers is allowed, while for carbon dioxide fire extinguishers this figure is 10 times higher (though the electrical strength of carbon dioxide is 0.9 of the air electrical strength). Since the air electrical strength depends on the external conditions (temperature, pressure, humidity, distance between the electrodes), it is proposed to enter relative values for the assessment of the extinguishing powder electrical strength, for example, the ratio of the breakdown voltage to the breakdown voltage in the air.

INHIBITORY EFFECT AND ADSORPTION CHARACTERISTICS OF 2,3-DIAMINONAPHTHALENE AT ALUMINUM/HYDROCHLORIC ACID INTERFACE: EXPERIMENTAL AND THEORETICAL STUDY

2008 ◽  
Vol 15 (06) ◽  
pp. 903-910 ◽  
Author(s):  
I. B. OBOT ◽  
N. O. OBI-EGBEDI
Keyword(s):  
Molecular Orbital ◽  
Inhibition Efficiency ◽  
Inhibitory Effect ◽  
Mulliken Charge ◽  
Chemical Calculation ◽  
Active Centers ◽  
Langmuir Adsorption ◽  
Highest Occupied Molecular Orbital ◽  
Calculation Results ◽  
Lowest Unoccupied Molecular Orbital

The inhibitive effect of 2,3-diaminonaphthalene (2,3-DAN) for corrosion of aluminum in 1 M HCl was investigated using hydrogen evolution technique at 30 and 40°C. Quantum chemical calculation results showed that 2,3-DAN molecule possessed planar structure with a number of active centers, which aided the adsorption process. The Mulliken charge density, the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) were found mainly focused around nitrogen atoms and the cyclic of the benzene as well. The presence of 2,3-DAN molecules in the corrosive medium (1 M HCl solution) inhibits the corrosion process of aluminum and as the concentration of 2,3-DAN increases the inhibition efficiency also increases but decreases with rise in temperature. The corrosion inhibition of 2,3-DAN was discussed in terms of blocking of the Al surface by adsorption of the molecules of the inhibitor at the active centers. It was found that the adsorption of 2,3-DAN onto the Al surface followed the Langmuir adsorption isotherm and 2,3-DAN adsorbed on Al surface probably by physisorption. The proposed physisorption mechanism was supported by the calculated values of Ea, Q ads , and ΔG ads .

scholarly journals Influence of Surfactants on Copper-CNTs Electrodeposition

2021 ◽  
Vol 15 (1) ◽  
pp. 125-131
Author(s):  
Iryna Roslyk ◽  
◽  
Ganna Stovpchenkoko ◽  
Galyna Galchenko ◽  
◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Corrosion Resistance ◽  
Cationic Surfactant ◽  
Ultrasonic Treatment ◽  
Composite Powder ◽  
Maximum Effect ◽  
Different Types ◽  
Powder Particles

Influence of different types of surfactants on electrodeposition of copper- and carbon-bearing (graphite, carbon nanotubes (CNTs)) composite powder has been experimentally investigated. The size of powder particles decreased, and corrosion resistance increased when surfactants were added. Addition of cationic surfactant CTAB to the electrolyte with simultaneous ultrasonic treatment for CNTs dispersion gives maximum effect.

Sign in / Sign up

Export Citation Format

Share Document