الفهرس 
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Abstract
The present work objective laid out for this study is to investigate the fire
extinguishment mechanisms and effects for the water mist with various constant
droplet sizes and flux density inside an enclosure through numerical simulation
using PYROSIM.
The model designed for this study is an enclosed compartment of 4.0m *
4.0 m *2.3 m with a square hole of .38 m on the top. A rectangular methanol and
benzene fuel pan set on the center of the room floor and five water mist nozzle
are installed at 1.8 m above the floor. The ceiling gas temperature is measured
with five thermocouples located at 1.8 m above the floor. The model used in this
study validated against the previous experimental work of Kim and Ryou[43]
and the predicted results are in good agreement with experimental data for
temperature field. The following conclusions can be drawn.
1- For 50 μm through 250 μm droplet size, The fire extinguishing time
decreases with the decreasing of droplet size since the evaporation cooling
of surrounding gas and the reduction of oxygen concentration around fire
plume are the dominant factors in fire extinguishment.
2- The extinguishing time for methanol fire with water mist with droplet sizes
50, 100, 150, 200, 250 μm is 11, 25, 25, 70, 145 second respectively.
3- The extinguishment time for Benzene fire with water mist with droplet
sizes 50, 100, 150, 200, 250 is 14, 52, 58, 176, 689 second respectively
4- Both 100 and 150 μm droplet sizes in methanol fire have almost the same
efficiency in extinguishing the fire.