A Numerical Study Onfire Suppression of Water Mist in Microgravity

2014 ◽  
Vol 1016 ◽  
pp. 819-823
Author(s):  
Xue Han ◽  
Jun Qin ◽  
Jun Jun Tao ◽  
Ming Hui Feng
Keyword(s):  
Flow Rate ◽  
Numerical Study ◽  
Fire Suppression ◽  
Water Flow Rate ◽  
Simulation Method ◽  
Critical Value ◽  
Water Mist ◽  
Dominant Mechanism ◽  
Effect Of Water ◽  
Fire Extinguishing

Water mist technology has been developed and regarded as a promising substitute fire-extinguishing agent in spacecraft. In this paper, a numerical simulation method is introduced to investigate the effect of water mist size, velocity and flow rateon the fire suppressionefficiencyin microgravity. The fire extinguishing efficiency is better for the finer water mist in microgravity due to better heat transfer and more rapid vaporization. The evaporation cooling is the dominant mechanism of fire suppression in microgravity.As for the water mist velocity, the performance of fire suppression is affected slightly in microgravity. The results on the effect of water flow rate show that the flow rate should be higher than a critical value to suppress the fire effectively.

Experimental and Numerical Study on the Suppression of Pool Fire with Water Mist

2013 ◽  
Vol 790 ◽  
pp. 686-689
Author(s):  
Chen Jian ◽  
Xu Yan Ying ◽  
Wang Yan Sheng
Keyword(s):  
Systems Engineering ◽  
Numerical Study ◽  
Fire Suppression ◽  
Inhibitory Effect ◽  
Water Mist ◽  
Pool Fire ◽  
Optimized Design ◽  
Operating Pressure ◽  
Fire Extinguishing ◽  
Oil Pool

The objective of this work is to investigate the diesel analog pool fire with water mist .For this purpose, a series of water mist fire suppression experiment are carried out by changing the nozzle operating pressure, the source of fire power, opening and closing the exhaust fan to analyze the inhibitory effect of water mist to oil pool fire in the enclosed compartment of 5.0m × 5.0m × 3.0m. The results shows that extinguishing efficiency first increases and then decreases when the nozzle operating pressure increases from 8MPa to 12MPa, reaching the highest efficiency at 10MPa; increasing the power of the source of fire, the burning speed increases and the water mist fire extinguishing efficiency decreases; fresh oxygen coming in when smoke exhaust fan is turned on and water mist fire suppression efficiency decreases. Using FDS to simulate the water mist extinguishing oil pool fire, the predict temperature field and extinguishing time are basically consistent with the experimental results. In the actual applications of water mist fire suppression systems engineering, we can use the FDS field simulation methods to predict the characteristic parameters variation of the fire fighting fire temperature and component concentration, which is significant to the fire extinguishing system optimized design.

scholarly journals Experimental and Numerical Study of Water Mist Fire Suppression System Effectiveness on Shielded Fire

2018 ◽  
Vol 67 ◽  
pp. 04039
Author(s):  
Kuswantoro ◽  
Y.S. Nugroho
Keyword(s):  
Numerical Study ◽  
Fire Suppression ◽  
Water Flow Rate ◽  
Water Mist ◽  
Spray Nozzle ◽  
Wood Crib ◽  
Fine Spray ◽  
System Effectiveness ◽  
Suppression System ◽  
Fuel Source

This study aims to investigate the effectiveness of water mist on suppressing a shielded fire. Full-scale experiments are carried out in a partition room of (lxwxh) 2x2x2.5 m size. Five water mist nozzle which consist of two type nozzle was used, high flow (fogjet) nozzle installed at top center of the room and fine spray nozzle installed at each side of room at high 1.5 m from ground. The pressure of water mist system was maintained at 20 bar which correspond to 2.6 lpm of water flow rate. Wood crib of 6.5 x 6.5 x 6 cm size was used as the fuel source. The obstruction used as a fuel shield has table like form with 40 x 40 cm cover area and 0.5 m height. The location of fuel source and fuel shield was varied (1) fuel source and shield at centre of room, (2) fuel source at one side of shield and the shield at centre of room, (3) fuel source and shield at corner of room, and (4)) fuel source at one side of shield and the shield at corner of room. Numerical simulation using FDS 6.5.3 was also performed to validate the use of FDS and get better understanding of the phenomena. The results showed that water mist was able to extinguish the fire around 20 s, 16 s, 30 s, and 24 s for scenario 1, 2, 3 and 4 respectively. It is also observe that the mist distribution around the shield and cover area of the shield play a role on the capacity and time needed of water mist to extinguish the fire.

scholarly journals Effect of Water Flow on Underwater Wet Welded A36 Steel

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 682
Author(s):  
Eko Surojo ◽  
Aziz Harya Gumilang ◽  
Triyono Triyono ◽  
Aditya Rio Prabowo ◽  
Eko Prasetya Budiana ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Water Flow ◽  
Flow Rate ◽  
Water Flow Rate ◽  
Physical And Mechanical Properties ◽  
Shielded Metal Arc Welding ◽  
Effect Of Water ◽  
Bending Effect ◽  
Metal Arc Welding ◽  
A36 Steel

Underwater wet welding (UWW) combined with the shielded metal arc welding (SMAW) method has proven to be an effective way of permanently joining metals that can be performed in water. This research was conducted to determine the effect of water flow rate on the physical and mechanical properties (tensile, hardness, toughness, and bending effect) of underwater welded bead on A36 steel plate. The control variables used were a welding speed of 4 mm/s, a current of 120 A, electrode E7018 with a diameter of 4 mm, and freshwater. The results show that variations in water flow affected defects, microstructure, and mechanical properties of underwater welds. These defects include spatter, porosity, and undercut, which occur in all underwater welding results. The presence of flow and an increased flow rate causes differences in the microstructure, increased porosity on the weld metal, and undercut on the UWW specimen. An increase in water flow rate causes the acicular ferrite microstructure to appear greater, and the heat-affected zone (HAZ) will form finer grains. The best mechanical properties are achieved by welding with the highest flow rate, with a tensile strength of 534.1 MPa, 3.6% elongation, a Vickers microhardness in the HAZ area of 424 HV, and an impact strength of 1.47 J/mm2.

scholarly journals Effects of Discharge Area and Atomizing Gas Type in Full Cone Twin-Fluid Atomizer on Extinguishing Performance of Heptane Pool Fire under Two Heat Release Rate Conditions in an Enclosed Chamber

2021 ◽  
Vol 11 (7) ◽  
pp. 3247
Author(s):  
Dong Hwan Kim ◽  
Chi Young Lee ◽  
Chang Bo Oh
Keyword(s):  
Heat Release ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Water Mist ◽  
Pool Fire ◽  
Sauter Mean Diameter ◽  
Discharge Area ◽  
Fire Extinguishing ◽  
Enclosed Chamber

In this study, the effects of discharge area and atomizing gas type in a twin-fluid atomizer on heptane pool fire-extinguishing performance were investigated under the heat release rate conditions of 1.17 and 5.23 kW in an enclosed chamber. Large and small full cone twin-fluid atomizers were prepared. Nitrogen and air were used as atomizing gases. With respect to the droplet size of water mist, as the water and air flow rates decreased and increased, respectively, the Sauter mean diameter (SMD) of the water mist decreased. The SMD of large and small atomizers were in the range of approximately 12–60 and 12–49 μm, respectively. With respect to the discharge area effect, the small atomizer exhibited a shorter extinguishing time, lower peak surface temperature, and higher minimum oxygen concentration than the large atomizer. Furthermore, it was observed that the effect of the discharge area on fire-extinguishing performance is dominant under certain flow rate conditions. With respect to the atomizing gas type effect, nitrogen and air appeared to exhibit nearly similar extinguishing times, peak surface temperatures, and minimum oxygen concentrations under most flow rate conditions. Based on the present and previous studies, it was revealed that the effect of atomizing gas type on fire-extinguishing performance is dependent on the relative positions of the discharged flow and fire source.

Numerical Simulation and Experimental Study on Water Mist Fire Suppression for Cooking Fog Discharge Pipe

2014 ◽  
Vol 915-916 ◽  
pp. 356-361
Author(s):  
Zheng Wen Xie
Keyword(s):  
Design Method ◽  
Fire Suppression ◽  
Orthogonal Design ◽  
Water Mist ◽  
Simulation Software ◽  
Droplet Radius ◽  
Test Analysis ◽  
Injection Angle ◽  
Fire Extinguishing ◽  
Flow Quantity

FDS simulation software was used to establish the full size lampblack physics model of single wind pipe, using the orthogonal design method design of analog calculation conditions, research in the nozzle pressure, the droplet radius, nozzle, flow quantity and injection angle parameters under different conditions of water mist fire extinguishing effect. Based on a full-scale combustion and water mist fire extinguishing experiment, the water mist fire suppression was observed and test analysis etc, to better understand the flue water mist fire extinguishing feasibility, provides the theory basis for the design of efficient, reliable flue fire extinguishing system.

The Experimental Study on the Fire Suppression Effectiveness of Water Mist with the FeCl2 Additives

2013 ◽  
Vol 790 ◽  
pp. 53-56
Author(s):  
Chen Jian ◽  
Xu Yan Ying ◽  
Wang Na
Keyword(s):  
Experimental Study ◽  
Fire Suppression ◽  
Water Mist ◽  
Experimental Results ◽  
Additive Concentration ◽  
Experimental Conditions ◽  
Fire Source ◽  
Fire Extinguishing ◽  
Nozzle Position

This paper presents an experimental study of fire suppression effectiveness with water mist containing FeCl2 additives.The investigation focuses on suppression effectiveness under various FeCl2 additives concentrations,working pressures and nozzle different height above the fire source . The experimental results show that: there is a significant impact on fire suppression effectiveness when adding FeCl2 to water mist. There is an optimum additive concentration of extinguishing fire, corresponding to the shortest extinguishing time, the least amount of water, the highest efficiency of extinguishing fire. The nozzle working pressures and nozzle position have effect on the performance of the water mist extinguishing: the greater the pressure is, the shorter water mist fire extinguishing time is. Under the same experimental conditions, the closer the water mist nozzles are to the oil pan, the shorter extinguishing time is.

scholarly journals Effects of water flow rate and surface cover plant density on the growth of duckweed (Lemna minor L.)

2020 ◽  
Vol 5 (2) ◽  
pp. 98
Author(s):  
Renata Caprina Samantha Mahadewi Hutabarat ◽  
Didik Indradewa
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Plant Density ◽  
Lemna Minor ◽  
Water Flow Rate ◽  
Organic Fertilizers ◽  
Growth And Yield ◽  
Surface Cover ◽  
Agriculture Sector ◽  
Effect Of Water

Globally, agriculture sector is facing unprecedented challenges in producing fertilizers and increasing the amount of fertilizer production without having negative impact on the environment. Thus, the organic fertilizers are needed to be produced as they do not give any damages to the environment. Duckweed plant has a lot of potentials that can be used in the agriculture sector. This plant can breed in approximately 16-48 hours by splitting. The water needs and its breeding speed ability are the basis for conducting this research. The research objective was to determine the effect of water flow rate and surface cover plant density on the growth and yield of duckweed plants. This research was conducted in November–December 2018 in Cangkringan District, Sleman, Special Region of Yogyakarta, Indonesia. The experiment was arranged in a split plot design. The main plot was irrigation water flow rate, consisting of two levels, namely large water flow rate (0.336 L.second-1) and small water flow rate (0.085 L.second-1). The subplot was the density of the duckweed plant surface cover, consisting of 10%, 20%, 40% and 60%. The results of this study indicated there was no effect of water flow rate on the plant growth, yield, and yield quality of duckweed plants. The C/N ratio of the duckweed plants fulfilled the requirement to be used as green manure.

Physical Scaling of Fire Suppression by Water Mist

2001 ◽  
Author(s):  
G. Su ◽  
J. G. Quintiere ◽  
N. Schultz
Keyword(s):  
Heat Flux ◽  
Fire Suppression ◽  
Water Flow Rate ◽  
Water Mist ◽  
Full Scale ◽  
Scale Model ◽  
Safety Committee ◽  
Pressure Water ◽  
Full Scale Tests ◽  
Final Answer

Abstract The objective of the project is to develop water mist extinguishments design by scaling. The report describes the requirement and criteria of scaling fire, scale model, and the results of suppression for a developing water mist system design. The Maritime Safety Committee Draft Circular, MSC 914 is used as a basis test to evaluate a water mist design. A series of three full-scale tests related to MSC 914 were performed: fire only, fire with steel trailers, and fire with steel trailers and combustible commodities. A simulation was accordingly studied. Then, a scaled water mist design was tested in the scale model to find the characteristics needed for suppression in terms of pressure, water flow rate, droplet size, and the spray momentum. Based on these characteristics, a candidate nozzle will be selected for the full-scale MSC 914 test. The results so far show that the water mist system can effectively suppress the fire in scaled MSC 914 model. The full-scale MSC 914 is scheduled for September 2001. Therefore, the final answer is still pending until then. Scaling results are confirmed for temperatures, heat flux and flow for the MSC 914 fire without water add in.

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