Water Mist Suppression of PMMA Boundary Layer Combustion - A Comparison of NanoMist and Spray Nozzle Performance

Concept of the water mist spray in CKV system is to clean the gas filter at kitchen hood. This research aims to analyze the behavior and flow characteristics of water mist spray produced by spray nozzle. A computational fluid dynamics (CFD) model with k-epsilon turbulence method is a simulation tool for the characterization of sprays. The fluid flow for case1, case 2 and case 3 have the same pattern type of graph. Changes have seen in fluid flow pressure and velocity. The value of fluid flow pressure was decreasing from the first point at water inlet until to the last point at nozzle orifice. The total pressure values for case 1, case 2, and case 3 are 99.997 kPa, 199.991 kPa and 299.992 kPa respectively. The highest velocity is recorded at the liquid tip of the nozzle which is about 144.15 m/s for case 3. In the other hand, the highest value of fluid flow pressure was recorded at the water inlet part.

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The Effect of Water Mist Cooling of Casting Die on the Solidification, Microstructure and Properties of AlSi20 Alloy

Archives of Metallurgy and Materials ◽

10.1515/amm-2017-0026 ◽

2017 ◽

Vol 62 (1) ◽

pp. 187-194 ◽

Cited By ~ 1

Author(s):

R. Władysiak ◽

A. Kozuń ◽

T. Pacyniak

Keyword(s):

Boundary Layer ◽

Primary Silicon ◽

Water Mist ◽

Research Station ◽

Hardness Distribution ◽

The Core ◽

Eutectic Si ◽

Mist Cooling ◽

Computer Controlled ◽

Silicon Particles

Abstract Unmodified AlSi20 alloy were casted at the research station, allowing for sequential multipoint cooling using a dedicated computer- controlled program. This method allows for the formation of the microstructure of hypereutectic AlSi20 alloy and also increases hardness. Primary silicon dendrites were found in the microstructure of cooled samples. Based on these dendrites, the formation of primary silicon particles is explained. Cooling of casting die with a water mist stream causes changes in solidification, which leads to expansion of the boundary layer with columnar crystals and shrinkage of the core zone with equiaxed crystals. It also causes more regular hardness distribution around pre-eutectic Si crystals, which can lead to tensile strength and machinability improvement.

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

E3S Web of Conferences ◽

10.1051/e3sconf/20186704039 ◽

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.

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