icme presentation
TRANSCRIPT
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STUDY OF TRANSIENT HEAT TRANSFEROF A SOLID WITH PROTECTIVE FABRIC
UNDER HOT AIR JET IMPINGEMENT
MA Islam, AA Rezwan, S Hossain and AKMN Islam
Dept. of Mechanical Engineering
Bangladesh University of Engineering & Technology
Dhaka, Bangladesh
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Outline
Motivation
Background of the Study
Methodology
Mathematical Model
Experimental Setup
Results
Comparison with the Standards
Further Improvement
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Motivation
Fire Fighters against the Inferno
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Background
The most frequent injuries that the firefighters and alsothe employees working in many hazardous chemicalenvironment suffers are burns
The most obvious reason for their burn injuries is thehigh heat flux exposures
The present study focuses on the measurement of heatflux on a surface that can be imitated as a skin for ahigh heat flux exposure with a protective fabric support
How far can we prevent the fire burn wound?
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Skin
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Skin Burn Injuries
BurnInjuries
LayerInvolved
Appearance Texture Sensation Time toHealing
First
DegreeEpidermis Redness Dry Painful
1 week
or less
Second
DegreeDermis
Red with
clear blisterMoist Painful
2-3
weeks
Third
Degree
Extend
through
entire
Dermis
Stiff and
white /
brown
Dry,Leathery
PainlessRequires
excision
Fourth
Degree
Extends
through
skin,
subcutane
ous tissue
Charred
with escharDry Painless
Requires
excision
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Methodology
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Thermocouple
Position
Schematic Diagram of the Experiment
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Mathematical Model
Semi- Infinite Solid Model
1
Boundary Condition T(x,0) = Ti
|=0
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Mathematical Model
The solution for the case
, 2
4
1erf
2
On the surface (x = 0) this equation reduces to
2
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Mathematical Model
Newtons law of cooling is used to calculate
the local heat transfer coefficient, h.
( (0,))
Nusselt Number
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Experimental Setup
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Experimental Setup: Heater Section
Cut-way View of Heater SectionICME 11-TH-04220 December 2011
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Experimental Setup: Fabric Holder
Connection
with the PicoSystem
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Fabric Holder
Assembly
(Wooden
Frame)
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Experimental ConditionParameters Values
Jet Velocity (m/s)
Temperature (C)
Nozzle Dia (mm)
l/dr/d
19, 15
125
25.4
2, 4, 6-4.5 ~ 4.5
Environment Temp. (C) 25 ~ 32
Protective FabricAluminized glass fiber withvapor absorbent stitched with
Kevlar fiber (NAFFCO)
Base Plate Hardboard (Massonite)ICME 11-TH-04220 December 2011
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Protective Fabric
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Brand: NAFFCO
Model: KA 800 (PO 300)
Aluminized glass fiber with vapor
absorbent stitched with Kevlar fiber
Exposed Surface
Inner Surface
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20
40
60
80
100
0 20 40 60 80 100 120 140 160 180 200
Temperature
(C)
Time (sec)
4.5
31.5
Center
-1.5
-3
-4.5
20
40
60
80
100
0 20 40 60 80 100 120 140 160 180 200
Temperat
ure(C)
Time (sec)
4.5
3
1.5
Center
-1.5
-3
-4.5
l/d = 2V = 19m/s
Without
FR Fabric
l/d = 2
V = 19m/sWithout
FR Fabric
Temperature Variation with Time
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0
0.5
1
1.5
2
2.5
3
3.5
4
0 30 60 90 120 150 180
SurfaceHeatFlux,
q(kW/m)
Time, t (sec)
Surface Heat Flux variation with Time
for different l/d Position
l/d=2
l/d=4
l/d=6
l/d=2 wf
l/d=4 wf
l/d=6 wf
V = 15 m/s
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0
0.5
1
1.5
2
2.5
3
3.5
4
0 30 60 90 120 150 180
SurfaceHeatFlux,
q(kW/m)
Time, t (sec)
Surface Heat Flux variation with Time
for different Velocity
V=15 m/s
V=19 m/s
Dashed Line: With FR Suit
Solid Line: Without FR Suit
l/d = 2
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0
0.5
1
1.5
2
2.5
3
3.5
4
0 30 60 90 120 150 180
Su
rfaceHeatFlux,q(kW/m)
Time, t (sec)
Surface Heat Flux variation with Time
for different Velocity
V=15 m/s
V=19 m/s
Dashed Line: With FR Suit
Solid Line: Without FR Suit
l/d = 6
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0
5
10
15
20
25
30
35
40
45
-4.50 -3.00 -1.50 0.00 1.50 3.00 4.50
Nu
r/d
Nusselt Number variation across Radial Position
for different Exposure Time
t=30s
t=65s
t=180s
l/d = 4
V = 19 m/s
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0
5
10
15
20
25
30
35
40
45
-4.50 -3.00 -1.50 0.00 1.50 3.00 4.50
Nu
r/d
Nusselt Number variation across Radial Position
for different l/d Position
l/d=2
l/d=4
l/d=6
Time = 65s
V = 19 m/s
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THE SAFETY COMPARISON
How far can we prevent the fire burn
wound?
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0
5
10
15
20
25
30
0 10 20 30 40 50
HeatFlux(kW/m)
Exposure Time (sec)
Human Tissue Tolerance to Pain Sensation
Stoll Criterion Without FR With FR
*Stoll, A. M. and Chianta, M. A. Method and Rating System for evaluations of Thermal Protection Aerospace Medicine,
Vol. 40, 1969
*ASTM Standard: F1060-05 Standard Test Method for Thermal Protective Performance of Materials for Protective Clothingfor Hot Surface Contact
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l/d = 2
V = 19 m/s
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0
5
10
15
2025
30
35
4045
50
0 5 10 15 20 25 30
HeatFlux(kW/m)
Exposure Time (sec)
Human Tissue Tolerance to Second Degree Burn
Stoll Criterion Without FR With FR
*Stoll, A. M. and Chianta, M. A. Method and Rating System for evaluations of Thermal Protection Aerospace Medicine,
Vol. 40, 1969
*ASTM Standard: F1060-05 Standard Test Method for Thermal Protective Performance of Materials for Protective Clothingfor Hot Surface Contact
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l/d = 2
V = 19 m/s
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Related Work
1. Lee, S., Park, C., Kulkarni, D., Tamanna, S., Knox, T.,2010, Heat and Mass Transfer in a Permeable Fabric
System under Hot Air Jet Impingement, Proc. Int.Heat Transfer Conf. (IHTC14)
2. Anguiano, R. M., 2006, Transient Heat Transferthrough Thin Fibrous Layer, M.Sc. Thesis, University
of Alberta, Emonton, Albarta, Canada
3. Torvi, D. A., 1997, Heat Transfer in Thin Fibrous
Materials Under High Heat Flux Conditions, Ph.DThesis, University of Alberta, Calgary, Alberta
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Future Work
Develop a model for computational technique
and validate the simulated result for the
improvement of protective fiber
Study the heat & mass transfer of the fire
resistive fabric under Steam Exposure
Study the heat transfer of the fire resistive
fabric under diffusion flame using different
flammable liquid
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Thank You