The Study of Fire-extinguishing Process of Modelled Fire Seats

2021 ◽  
pp. 57-62
Author(s):  
V.N. Bordakov ◽  
Keyword(s):  
Flow Rate ◽  
Experimental Studies ◽  
Physical Modelling ◽  
Specific Flow Rate ◽  
Specific Flow ◽  
Acceptable Error ◽  
Fire Extinguishing ◽  
Fire Zone ◽  
Analysis Of Results ◽  
Fire Extinguishers

Test-fires to determine fire-extinguishers’ efficiency for extinguishing B class fires are conducted by operators equipped with working clothes, which does not comply with the requirements of physical modelling. This is why the ranks of extinguished modelled seats are significantly overestimated. The quantitative results of fire seats’ extinguishing can be comparatively evaluated in accordance with the value of specific flow rate of a fire-extinguishing agent. As it was detected, the specific flow rate of a fire-extinguishing agent does not actually depend on the rank of modelled fire seat when extinguished by an operator wearing thermal-protective clothes. At the same time, it is increasing along with the expansion of the fire zone scale in case the fire is extinguished without special protective clothes. Consequently, to increase the fire-extinguisher’s efficiency data reliability, the certifying tests should be conducted in conditions close to the real application conditions when the first person to firefight is not equipped with such special protective clothes. The experimental studies to determine the specific flow rate of a fire-extinguishing agent used modelled fire seats of various ranks. The analysis of results showed that the fire-extinguishers ensuring generation of drops of prevailing size more than 0,5 mm are required to extinguish the modelled sire seats. The degree of increasing flow rate for the fire-extinguishing agent to eliminate a fire and observation of a safe distance from the flame for an operator are conditioned by the scale of fire zone and affect the specific flow rate of agent required to ensure stable fire-extinguishing. Based on the results of extinguishing the fire seats «34В» or «55В», it is demonstrated that via using a correction factor it is possible, assuming an acceptable error, to evaluate the flow rate of fire-extinguishing agent to extinguish a modelled fire seat of any rank.

scholarly journals Intermittent Chaos in the CSTR Bray–Liebhafsky Oscillator-Specific Flow Rate Dependence

2020 ◽  
Vol 8 ◽  
Author(s):  
Itana Nuša Bubanja ◽  
Ana Ivanović-Šašić ◽  
Željko Čupić ◽  
Slobodan Anić ◽  
Ljiljana Kolar-Anić
Keyword(s):  
Flow Rate ◽  
Rate Dependence ◽  
Specific Flow Rate ◽  
Specific Flow ◽  
Intermittent Chaos

Involute Gear Pumps Versus Lobe Pumps: A Comparison

1997 ◽  
Vol 119 (4) ◽  
pp. 458-465 ◽  
Author(s):  
G. C. Mimmi ◽  
P. E. Pennacchi
Keyword(s):  
Optimum Design ◽  
Flow Rate ◽  
Design Parameters ◽  
Specific Flow Rate ◽  
Specific Flow ◽  
Positive Displacement ◽  
Involute Gear ◽  
Performance Indexes ◽  
Rotary Pumps ◽  
Gear Pumps

In previous studies we have considered several types of positive displacement rotary pumps and deeply analyzed the generation of the flow rate and the design limits. This has been done in order to evaluate the main performance indexes; one of which, the flow rate irregularity, is related to the possibility that the pump becomes a source of vibration and noise. A second index is the specific flow rate, related to the delivery capacity of the pump. In this paper, following our previous researches, we analyzed internal involute gear pumps and internal lobe pumps, that have similar operations but different performances. The design parameters and the way to optimize the performances are proposed for both cases. Finally a comparison is made between the two types of pumps with optimum design parameters.

scholarly journals Removal of arsenic from aqueous solution containing hexafluoroarsenate

2021 ◽  
pp. 6-9
Author(s):  
Helena Parschová ◽  
Eva Mištová
Keyword(s):  
Aqueous Solution ◽  
Flow Rate ◽  
High Selectivity ◽  
Arsenic Removal ◽  
Weak Base ◽  
Specific Flow Rate ◽  
Column Tests ◽  
Anion Exchangers ◽  
Specific Flow ◽  
Removal Of Arsenic

Arsenic removal from aqueous solutions containing hexafluoroarsenate or arsenate by strong and weak base anion exchangers was studied by dynamic column tests that were carried out using solution containing arsenic and accompanying anions (chlorides, sulfates and fluorides). The specific flow rate of solution was 6 BV/h. Desorption of arsenic was carried out by 1 mol/L NaOH or 2 mol/L KSCN. All the studied anion exchangers performed well in the absence of accompanying anions. In the presence of chlorides and sulfates, studied exchangers showed high selectivity towards hexafluoroarsenate.

scholarly journals A NOVEL DESIGN OF THE ROOTS BLOWER

2019 ◽  
Vol 57 (2) ◽  
pp. 249 ◽  
Author(s):  
Tran Ngoc Tien ◽  
Nguyen Hong Thai
Keyword(s):  
Flow Rate ◽  
Volumetric Efficiency ◽  
Specific Flow Rate ◽  
Specific Flow ◽  
Rotor Profile ◽  
Profile Design ◽  
Novel Design

This paper reports a novel curve developed from non - circular gearing theory, which can be applied in rotor profile design of the two - lobe Roots blower. The formulas for calculating the volumetric efficiency and specific flow rate of the blower have also been established. To evaluate this type of the Roots blower, the volumetric efficiency and specific flow rate are being compared with those parameters of the two traditional designs and one recent variant.

scholarly journals Determining the main regularities in the process of mineral fertilizer granule encapsulation in the fluidized bed apparatus

2021 ◽  
Vol 4 (6(112)) ◽  
pp. 23-32
Author(s):  
Ruslan Ostroha ◽  
Mykola Yukhymenko ◽  
Jozef Bocko ◽  
Artem Artyukhov ◽  
Jan Krmela
Keyword(s):  
Fluidized Bed ◽  
Flow Rate ◽  
Mineral Fertilizer ◽  
Specific Flow Rate ◽  
Technological Parameters ◽  
Specific Flow ◽  
Multi Stage ◽  
Hard Shell ◽  
Encapsulation Process ◽  
Kinetics Of

This paper has substantiated the expediency and prospects of obtaining organomineral fertilizers by encapsulating mineral granules with an organic suspension in fluidized bed apparatuses. An overview of existing approaches to the mathematical description of the kinetics of granule growth in granulation processes in fluidized bed apparatuses is presented. A mathematical model of the kinetics of the formation of a hard shell around granules in a fluidized bed has been built. It shows that the kinetics depend on the size of the retour particles, the specific flow rate of the suspension, the density of the suspension and granules, and the time of the process. Equations have been derived for determining the thickness of the hard shell and the specific flow rate of the suspension for individual granulation stages in a multi-stage granulator of the fluidized layer. Analytically, graphical dependences were built, which showed an increase in the thickness of the hard shell due to an increase in the specific flow rate of the suspension, the diameter of the retour particles, and the time of the encapsulation process. The equations make it possible to determine the rational regime and technological parameters of the encapsulation process in order to obtain a coating of the predefined thickness at the surface of the granules. This ensures that a quality product is obtained, with a granulometric composition in a narrower range of particle size. To obtain granules of 2.5–4 mm in size, it is necessary to carry out the process in three- or four-stage granulators of the fluidized bed at specific suspension consumption of (10–20)∙10-4 kg/(kg∙s.). It is shown that with uniform growing of granules with a constant increase in the thickness of the shell in multistage granulators, the suspension consumption decreases by 2‒3 times from the first stage to the subsequent ones. This approach reduces the operating and energy costs of the process.

The flow rate and the hold-up of solids under the counter-current flow of liquid phase in a vibrating plate column

1983 ◽  
Vol 48 (2) ◽  
pp. 439-448
Author(s):  
Eva Klašková ◽  
Vladimír Rod
Keyword(s):  
Flow Rate ◽  
Current Flow ◽  
Perforated Plate ◽  
Terminal Velocity ◽  
Continuous Phase ◽  
Specific Flow Rate ◽  
Specific Flow ◽  
Counter Current Flow ◽  
Counter Current ◽  
Plate Column

Flow rates and mean hold-ups of solids have been measured under the counter-current flow of water in a 50 mm in diameter vibrating perforated plate column. Experimental data have been described by a mathematical model expressing the specific flow rate of solids in dependence on the hold-up, terminal velocity of the particles, porosity of the plate, specific flow rate of the continuous phase and the frequency and amplitude of plate vibrations. It has been found that for systems exhibiting low particle terminal velocity the pumping effect of the plates may increase the flow rate of the dispersed phase to a value corresponding to the flow in the empty column.

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.

scholarly journals AlN Production in Co-Flow Filtration Mode at Low Pressures

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5482
Author(s):  
Nikolay Evseev ◽  
Pavel Nikitin ◽  
Mansur Ziatdinov ◽  
Ilya Zhukov ◽  
Alexei Vakutin
Keyword(s):  
Aluminum Nitride ◽  
Flow Rate ◽  
Energy Efficient ◽  
Gas Mixture ◽  
Combustion Mode ◽  
Specific Flow Rate ◽  
Specific Flow ◽  
Argon Mixture ◽  
Flow Filtration ◽  
Low Pressures

In this work, the process for obtaining aluminum nitride in the combustion mode of co-flow filtration of a nitrogen–argon mixture was investigated. The combustion of granules consisting of aluminum and aluminum nitride as an inert diluent was studied under conditions of co-current filtration in a flow of nitrogen and a nitrogen–argon mixture in the range of a specific flow rate of 1.5–5.0 cm3/(s∙cm2). It was found that the specific flow rate of the gas mixture and the amount of argon in the nitrogen–argon mixture had a significant effect on the rate and the temperature of combustion. The structure and phase composition of the synthesis products were studied. The maximum achieved yield of the AlN phase was 95 wt.%. Moreover, this method is energy efficient and allows the production of metal nitrides without the use of high-pressure reactors.

scholarly journals A Harmony Search Algorithm for the Reproduction of Experimental Data in the Social Force Model

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Osama Moh'd Alia ◽  
Mohammed Mahmod Shuaib
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Harmony Search ◽  
Force Model ◽  
Social Force ◽  
Specific Flow Rate ◽  
Social Force Model ◽  
Specific Flow ◽  
The Social ◽  
Density Relation

Crowd dynamics is a discipline dealing with the management and flow of crowds in congested places and circumstances. Pedestrian congestion is a pressing issue where crowd dynamics models can be applied. The reproduction of experimental data (velocity-density relation and specific flow rate) is a major component for the validation and calibration of such models. In the social force model, researchers have proposed various techniques to adjust essential parameters governing the repulsive social force, which is an effort at reproducing such experimental data. Despite that and various other efforts, the optimal reproduction of the real life data is unachievable. In this paper, a harmony search-based technique called HS-SFM is proposed to overcome the difficulties of the calibration process for SFM, where the fundamental diagram of velocity-density relation and the specific flow rate are reproduced in conformance with the related empirical data. The improvisation process of HS is modified by incorporating the global best particle concept from particle swarm optimization (PSO) to increase the convergence rate and overcome the high computational demands of HS-SFM. Simulation results have shown HS-FSM’s ability to produce near optimal SFM parameter values, which makes it possible for SFM to almost reproduce the related empirical data.

Involute Gear Pumps Versus Lobe Pumps: A Comparison

1996 ◽  
Author(s):  
Giovanni C. Mimmi ◽  
Paolo E. Pennacchi ◽  
Carlo G. Savi
Keyword(s):  
Optimum Design ◽  
Flow Rate ◽  
Design Parameters ◽  
Specific Flow Rate ◽  
Specific Flow ◽  
Positive Displacement ◽  
Involute Gear ◽  
Performance Indexes ◽  
Rotary Pumps ◽  
Gear Pumps

Abstract In previous studies we have considered several types of positive displacement rotary pumps and deeply analyzed the generation of the flow rate and the design limits. This has been done in order to evaluate the main performance indexes: one of these, the flow rate irregularity, is related to the possibility that the pump becomes a source of vibration and noise. A second index is the specific flow rate, related to the delivery capacity of the pump. In this paper, following our previous researches, we analyze internal involute gear pumps and internal lobe pumps, that have similar way to operate but different performances. The design parameters and the way to optimize the performances are summarized for both cases. Finally a comparison between the two types of pumps is proposed, along with some optimum design cases.

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