Upload
others
View
3
Download
0
Embed Size (px)
Citation preview
NUMERICAL INVESTIGATION OF SMOKE MANAGEMENT & CONTROL IN ATRIUM”
By
M. M.S. Ahmed, E. E. Khalil , M. M.A.Hassan and
H. O. Haridy
Cairo University, Cairo-Egypt
Presented by Prof.Dr.Essam E Khalil , ASHRAE Fellow, Director at Large
International Conference ENERGY in BUILDINGS 2017 - CYPRUS
Thursday May 4, 2017 - Limassol, Cyprus
OUTLINE
1. Introduction.
2. Literature review.
3. Objective.
4. Governing equations.
5. FDS Validation.
6. Grid sensitivity analysis.
7. Results.
8. Conclusions.
9. Recommendation for future works
2
Atrium :
An opening connecting two or more stories other than enclosed stairways which is closed at the top and not defined as mall
3 Dubai's Burj Al Arab, atrium
Wednesday, May 10, 2017
Hazard of atrium fires
Fire in atrium generates :
• Smoke at high temp.
• Smoke reduces visibility needed for escaping.
• Toxic gases endangers people life.
4
Hazard of atrium fires. Tenability criteria in building fires,Society of Fire Safety
Wednesday, May 10, 2017
Exposure to heat
Exposures to temperatures above 250°F (121°C) can result in skin pain and burns, and exposures to temperatures below this temperature can result in heat stroke (hyperthermia).
5
Heat tolerance for humans, with low air movement. SFPE Handbook
Wednesday, May 10, 2017
Exposure to toxic gases
In building fires, the most common asphyxiant is carbon monoxide (CO) and, to a lesser extent, hydrogen cyanide (HCN) which is more toxic.
6
Tolerance to CO and HCN. SFPE Handbook
Wednesday, May 10, 2017
Visibility
Criteria for visibility have been suggested ranging from 13 to 46 ft (4 to 14 m) (Jin 2008).
7
Walking speed versus visibility. SFPE Hand book
Wednesday, May 10, 2017
Smoke layer
The accumulated thickness of smoke below a physical or thermal barrier.
8
Smoke layer Klote, ASHRAE Journal, June 2012 .
Wednesday, May 10, 2017
Smoke management system
Smoke filling
9
The smoke management system must maintain the base of the smoke layer above the design height. Lougheed, Considerations in the Design of Smoke Management Systems for Atrium
Wednesday, May 10, 2017
Smoke exhaust
10
The smoke management system must maintain the base of the smoke layer above the design height. Lougheed, Considerations in the Design of Smoke Management Systems for Atrium
Plug-holing
11
Plugholing phenomenon Lougheed, Considerations in the Design of Smoke Management Systems for Atriums .
Plug-holing is a phenomenon where air below the smoke layer is pulled through the smoke layer into the smoke exhaust.
Wednesday, May 10, 2017
• Doheim,et al [16] ,used FDS to study the effect of atrium shape on natural smoke ventilation, Three fire simulations were performed for three atria with the same area (225 m2),the same height (18m) ,the same volume and different configurations.
Schematic diagrams for the atrium configurations [16].
• It was concluded that the rectangular configuration contributes better to smoke
ventilation design than square and triangular configurations by maintaining a clear height for longer time
• the triangular prism configuration is the most critical shape among the three configurations regarding smoke ventilation by having the highest soot mass fraction concentration and the highest temperature
12
2.LITERATURE REVIEW
Wednesday, May 10, 2017
Effect of fire location
13
Cases to study effect of fire location
Qin et al (2008) used FDS to study the effect of gravity venting on smoke layer height and plume temperature, Also study the effect of fire source location on smoke layer height
Atrium geometry
It was concluded that : • Descent of the smoke layer is faster in the case of fire at the center of the atrium.
• Highest plume temperature when fire source is located at the center of the atrium and
the lowest temperature when fire source at the corner of the atrium. Wednesday, May 10, 2017
14
El Banhawy (2007) used CFD to investigate smoke extraction with rooftop exhaust fans and side wall exhaust fans.
Atrium model
• It was concluded that side wall exhaust fans near the roof had proved to be more efficient than rooftop exhaust fans in terms of extracting smoke without plug-holing.
Wednesday, May 10, 2017
15
Stair Model for a single floor – Isometric View
Complete stairwell model
Khalil (2009) used CFD to investigate the effect of leakage area from doors on stairwell pressurization.
Wednesday, May 10, 2017
Pressure Difference Contours for Cases A,B,C,D at v=2.52 m/s.
16
(B) (A) (C) (D)
Model leakage area = 0.029 m2
Case A : Increase of leakage area by 12.7 %. Case B : Increase of leakage area by 25 %. Case C : decrease of leakage area by 12 %. Case d : decrease of leakage area by 25 %.
It was concluded that :
• For the same volume flow rate in, the pressurization of the stairwell is less than the theoretical pressurization value.
• Increasing the flow rate by 20% covers the friction losses.
• CFD predictions shows that for leakage area increase of 10%, the system is capable of pressurization, for a leakage increase of 20%, the system capable of maintaining positive pressure but without the acceptable minimum difference.
17 Wednesday, May 10, 2017
3.OBJECTIVE OF PRESENT WORK
• Explore The use of FDS Simulation as a Design Tool of smoke management system.
• Simulating fire and smoke management system in a real atrium in Dar Al Handasah building ,Smart village, Egypt.
• Investigate the effect of make up air inlets configuration on smoke layer and tenability conditions.
• Investigate the effect of increasing spacing between fans on plug-holing phenomenon.
18 Wednesday, May 10, 2017
4.GOVERNING EQUATIONS
19 FDS Technical reference guide , NIST.
Wednesday, May 10, 2017
5.VALIDATION
20 Schematic diagram of the PolyU /USTC atrium[20].
Full-scale experimental tests are difficult to be carried out. So the validation for FDS is carried out using experiments done by Chow and cui [20] on PolyU / USTC atrium.
Wednesday, May 10, 2017
21
Out View of the PolyU / USTC Atrium
Wednesday, May 10, 2017
FDS Simulation
22
Fire area (m2)
Measured HRR (KW)
Simulation grid size
Number of cells
Experiment 1 0.28 248 0.12 x 0.13 x 0.13 3240000
Experiment 2 0.785 393 0.15 x 0.15 x 0.15 2172000
Experiment 3 4 1560 0.16 x 0.16 x 0.16 1740480
Validation cases
Wednesday, May 10, 2017
Experiment 1
23
90; 22
165; 17
250; 12
330; 7
465; 2 0
5
10
15
20
25
30
35
40
45
0 100 200 300 400 500
Smo
ke la
yer
he
igh
t (m
)
Time (sec)
FDS
EXPERIMENTAL
Εκθετική (FDS)
Absolute average error = 14 %
Wednesday, May 10, 2017
45; 22
75; 17
120; 12
195; 7
300; 2
0
5
10
15
20
25
30
35
0 50 100 150 200 250 300
Smo
ke la
yer
he
igh
t (m
)
Time (sec)
FDS
EXPERIMENTAL
Εκθετική (FDS)
Experiment 2
Absolute average error = 18 %
24 Wednesday, May 10, 2017
Experiment 3
25
0
5
10
15
20
25
30
35
40
0 50 100 150 200
Σειρά1
Σειρά2
Εκθετική (Σειρά1)
Absolute average error = 15 %
Wednesday, May 10, 2017
Present study Real atrium in Dar Al Handasah in smart village
26
Out view of Dar Al Handasah building Wednesday, May 10, 2017
27
Inside view of the atrium Wednesday, May 10, 2017
Model description
28
Plan view of atrium Atrium isometric
Wednesday, May 10, 2017
6.GRID SENSITIVITY ANALYSIS
29
Ambient temperature
(K)
Fire heat release rate
(MW)
Fire ramp up time (Sec)
Ventilation
297 5 330 All doors & windows are
closed leaving air gap of 0.2 m for make up air
Cell size Number of cells
Case 1 0.4 x 0.4 x 0.4 m 240000
Case 2 0.3 x 0.3 x 0.3 m
600000
Case 3 0.2 x 0.2 x 0.2 m
1085000
Boundary conditions
Wednesday, May 10, 2017
Smoke layer height at 1
30
0
5
10
15
20
25
30
0 100 200 300 400 500 600
Smo
ke la
yer
he
igh
t (m
)
Time (Sec)
240000 Cell
600000 Cell
1085000 Cell
Wednesday, May 10, 2017
Smoke layer height at 2
31
0
5
10
15
20
25
30
0 100 200 300 400 500 600
Smo
ke la
yer
he
igh
t (m
)
Time (Sec)
240000 Cell
600000 Cell
1085000 Cell
Wednesday, May 10, 2017
Smoke layer height at 3
32
0
5
10
15
20
25
30
0 100 200 300 400 500 600
Smo
ke la
yer
he
igh
t (m
)
Time (Sec)
240000 Cell
600000 Cell
1085000 Cell
Wednesday, May 10, 2017
Smoke layer height at 4
33
0
5
10
15
20
25
30
0 100 200 300 400 500 600
Smo
ke la
yer
he
igh
t (m
)
Time (Sec)
240000 Cell
600000 Cell
1085000 Cell
Wednesday, May 10, 2017
Visibility variation at height of 22.25 m using different grid size
34
0
5
10
15
20
25
30
35
0 100 200 300 400 500 600
Vis
ibili
ty (
m)
Time (Sec)
240000 Cell
600000 Cell
1085000 Cell
Wednesday, May 10, 2017
Temperature variation at height of 22.25 m using different grid size
35
0
20
40
60
80
100
120
0 100 200 300 400 500 600
Tem
pe
ratu
re (
oC
)
Time (Sec)
240000 Cell
600000 Cell
1085000 Cell
Wednesday, May 10, 2017
CO Concentration variation at height of 22.25 m using different grid size
36
0
5
10
15
20
25
0 100 200 300 400 500 600
CO
Vo
lum
e f
ract
ion
(p
pm
)
Time (Sec)
240000 Cell
600000 Cell
1085000 Cell
• there is no significant difference between case 2 and case3. Based on the grid sensitivity analysis case 2 is chosen for present study to save time.
Study cases Name Condition
Case 1 No mechanical exhaust
Case 2
Ventilation with 5 rooftop exhaust fans (each 30 m3/s), Make up air through three opening doors (each
26.1 m2 ) and three operable windows (each 9 m2
Lowest surface of operable windows at height of 11.7 m.
Case 3 Ventilation with 5 rooftop exhaust fans (each 30 m3/s), Make up air through three opening doors (each
26.1 m2 )
Case 4
Ventilation with 5 rooftop exhaust fans (each 30 m3/s), Make up air through three opening doors (each
26.1 m2) and three operable windows (each 9 m2
,Lowest surface of operable windows at height of 18.7 m.
Case 5 Same as case 4 with changing exhaust fan location.
Case 6
Ventilation with 5 rooftop exhaust fans (each 30 m3/s), Make up air through three opening doors (each
26.1 m2) ,three operable windows (each 9 m2
Lowest surface of operable windows at height of 11.7 m and opposed doors opening at each floor
Case 7 Same as case 4 with increasing the spacing between fans.
Case 8 Simulation case for atrium evacuation,500 persons.
37
Name Condition
Case 1 No mechanical exhaust
Case 2
Ventilation with 5 rooftop exhaust fans (each 30 m3/s), Make up air through three opening doors (each
26.1 m2 ) and three operable windows (each 9 m2
Lowest surface of operable windows at height of 11.7 m.
Case 3 Ventilation with 5 rooftop exhaust fans (each 30 m3/s), Make up air through three opening doors (each
26.1 m2 )
Case 4
Ventilation with 5 rooftop exhaust fans (each 30 m3/s), Make up air through three opening doors (each
26.1 m2) and three operable windows (each 9 m2
,Lowest surface of operable windows at height of 18.7 m.
Case 5 Same as case 4 with changing exhaust fan location.
Case 6
Ventilation with 5 rooftop exhaust fans (each 30 m3/s), Make up air through three opening doors (each
26.1 m2) ,three operable windows (each 9 m2
Lowest surface of operable windows at height of 11.7 m and opposed doors opening at each floor
Case 7 Same as case 4 with increasing the spacing between fans.
Case 8 Simulation case for atrium evacuation,500 persons.
Study cases
38
Case 1
39
Pressure distribution
40 Wednesday, May 10, 2017
Case 2
41 Wednesday, May 10, 2017
Case 3
42 Wednesday, May 10, 2017
Case 4
43 Wednesday, May 10, 2017
Case 5
44 Wednesday, May 10, 2017
Case 6
45 Wednesday, May 10, 2017
Atrium evacuation
46 Wednesday, May 10, 2017
7.RESULTS Effect of Exhaust fan
0
5
10
15
20
25
30
0 100 200 300 400 500 600
Smo
ke la
yer
he
igh
t (m
)
Time (Sec)
CASE 1
CASE 2
47
Smoke layer height at point 2
0
10
20
30
40
50
60
70
80
0 100 200 300 400 500 600
Tem
pe
ratu
re (
oC
) Time (sec)
Case 1
Case 2
Temperature at point A
Comparison between case 1 & case2 Case 1 : no vent Case 2 : 5 fans located at the roof with total exhaust flow rate 150 m3/sec
Wednesday, May 10, 2017
0
5
10
15
20
25
30
35
0 100 200 300 400 500 600
Vis
ibili
ty (
m)
Time (sec)
Case 1
Case 2
0
2
4
6
8
10
12
0 100 200 300 400 500 600
CO
Vo
lum
e f
ract
ion
(p
pm
)
Time (sec)
Case 1
Case 2
Carbon monoxide volume fraction at point A Visibility at point A
From the previous figures, it can be noted the effect of using exhaust fans on • Smoke layer is kept at a higher level. • Lower temperature at human level. • Increase visibility. • Reduce carbon monoxide concentration at human level.
48
Effect of make up air velocity
49
Smoke layer height at point 2
0
5
10
15
20
25
30
0 100 200 300 400 500 600
Smo
ke la
yer
he
igh
t (m
)
Time (Sec)
v = 1 m/s
V = 1.7 m/s
10
15
20
25
30
35
0 200 400 600
Vis
ibili
ty (
m)
Time (Sec)
V = 1 m/s
V = 1.7 m/s
Visibility at point A
From the above figures, it can be noted that the effect of increasing make up air velocity by reducing make up air inlet area make the smoke layer descend to a lower level and reduce visibility at human level.
Effect of make up air inlet height
0
5
10
15
20
25
30
0 100 200 300 400 500 600
Smo
ke la
yer
he
igh
t (m
)
Time (Sec)
Case 2
Case 4
50
Smoke layer height at point 3
The above figure shows the effect of increasing the level at which make up air enters the atrium. Case 2 : lowest surface of operable windows at 11.7 m Case 4 : lowest surface of operable windows at 18.7 m
-10
0
10
20
30
40
50
60
0 100 200 300 400 500 600
Flo
w r
ate
(m
3 /se
c)
Time (Sec)
Door 2
Window 2
51
-10
0
10
20
30
40
50
60
0 100 200 300 400 500 600
Flo
w r
ate
(m
3 /se
c)
Time (Sec)
Door 2
Window 2
Flow through openings -Case 4 Flow through openings -Case 2
From the above figures ,it is noted that :increasing make up air inlet height increase air flow rate through the door which increase make up air velocity and reduce the flow rate entering from the window due to neutral pressure plan may descend below the window
Effect of opposed opening doors
15
17
19
21
23
25
27
29
31
33
0 100 200 300 400 500 600
Vis
ibili
ty (
m)
Time (Sec)
Case 2
Case 6
52
0
5
10
15
20
25
30
0 100 200 300 400 500 600
Smo
ke la
yer
he
igh
t (m
)
Time (Sec)
Case 2
Case 6
Smoke layer height at point 3 Visibility at point A
From the above figures ,it is noted that smoke layer height slightly increase and visibility distance increase at human level. From simulation ,it can be noted that air enters from communicating space in to atrium at lower level ,However at the last floor smoke flow from atrium to the communicating space.
Plug-holing
53
Spacing between fans = 5 m Spacing between fans = 6.3 m
Wednesday, May 10, 2017
distance between fans 2.8 d
Visibility contours at X = 8.5 m after 407 sec
54
distance between fans 3.5 d
Wednesday, May 10, 2017
Visibility contours at X = 8.5 m after 442 sec
55
distance between fans 2.8 d distance between fans 3.5 d
Wednesday, May 10, 2017
Visibility contours at X = 8.5 m after 460 sec
56
distance between fans 2.8 d distance between fans 3.5 d
Wednesday, May 10, 2017
8.CONCLUSIONS
• FDS is a powerful tool that can simulate smoke spread this was clear when comparing validation model with experimental data.
• The present research has highlighted the importance of smoke management in atrium during fires within the atrium
• increasing make up air velocity has adverse effect on smoke layer
height and tenability conditions at human level.
• increasing make up air inlet height 25 % of atrium height increase the smoke layer depth 20 % of atrium height.
• Increasing distance between exhaust fans reduce plug-holing phenomenon and enhance tenability conditions at human level.
57 Wednesday, May 10, 2017
9.RECOMMENDATIONS FOR
FUTURE WORK
• Considering relatively large fires of higher heat release rate (up to 25 MW).
• Study the effect of pressurizing stairwell related to the atrium to prevent smoke spread to stairs.
• Study the effect of mechanical make-up air supply on smoke layer and tenability conditions.
• Study the effect of sprinkler on fire heat release rate.
58 Wednesday, May 10, 2017
THANK YOU
Wednesday, May 10, 2017 59