ventilation of enclosed car parks using jetfan systems for ...maacinfra.net/products-pdf/ductless...

Ventilation of Enclosed Car Parks Using Jetfan Systems

for pollution and smoke control

© Fläkt Woods

Why ventilate a car park?

• Pollution control (vehicle emissions)

• Smoke extract (in case of fire)

• Building regulations

© Fläkt Woods

Ductwork system

Duct

work

Lighting

Grilles

Hi-level

(50%)

Grilles

Lo-level

(50%)

© Fläkt Woods

Generally applied method ( Ducted System)

• 6 ACH - pollution

• 10 ACH - fire / smoke extract

• Extract ductwork system, high / low level grilles

(50%), changing to Jetfan systems

• Extract fans, 2 off 50% duty each

• HT operation 300°C / 60mins

• Supply air, via entrance, louvred inlet or fans

© Fläkt Woods

Limitations

• Ventilation rate not matched to demand (too high)• Limited monitoring of pollution (CO)

• System operating all the time• 50% of extract at low level (not effective)• 10 ACH rate arbitrary, no account of specific fire size• Ductwork / grilles add resistance• Increased fan speed, absorbed power, and noise levels• Reduction in rental space, obstruct view and appearance

© Fläkt Woods

Jetfan system

Car park

Jetfoil Fan

Lighting

© Fläkt Woods

Jetfan system solution• Remove ductwork, retain high level extract points

• Main HT rated extract fans (identify supply)• Position Jetfoil fans throughout the car park • Analyse complex air flows using Computational Fluid Dynamics (CFD)• Easier installation of services• Reduce obstructions and improve appearance• Increase space for parking / rental• Reduction in system resistance• Reduction in fan speed and noise level• Reduction in absorbed power (running cost)

© Fläkt Woods

Main fans (Extract System)

Silencers

FAN:

100JM(HT)

© Fläkt Woods

Jetfoil fans

CFD OF JET FAN SHOWING VELOCITY PROFILE

1.0/s

2.5m/s6.0m/s

2.5m/s

8.0m/s20.0m/s

1.0m/s

0.5m/s

0.5m/s

0.5m/s

0.5m/s

1.0m/s

10.0m/s

© Fläkt Woods

Standard car park Jetfan: -35JM.Jet/2/SP

455m

m

© Fläkt Woods

Low Profile car park Jetfan: -31JM.Jet/2/LP

350m

m

© Fläkt Woods

Installation - 35JM.Jet/2/SP

© Fläkt Woods

Isometric plan view

3D model of car park

Extract grilles (2 off)

Jetfoil fans

Inlet

(via ramp)

Inlet

(via louvred inlets)

© Fläkt Woods

Isometric plan view


Extract grilles

Jetfoil fans

Supply

grilles

© Fläkt Woods


© Fläkt Woods

Isometric plan view

Extract points

Entrance / exit

Park Street

Entrance / exit

Alison Street


© Fläkt Woods

Isometric plan viewLow level Jetfans

Henibique beamsLarge arch

Small archEntrance

/ exit

Specific project requirements

• Operate ventilation system on demand (CO detection)

• Check extract rate vs. smoke production• Select ventilation based on “design fire” (MW)

• Possible to use model fire using CFD• Smoke / heat control (reduce spread temperature)

• Link fan operation with CFD / detection systems (mode table)

© Fläkt Woods

CFD Analysis to assist in elimination of ‘dead-spots’

AFTERBEFORE

= Primary ‘dead-spots’

Smoke production

Qρ = Convective Rate of Heat OutputQρ = KQ

where Q = Total Rate of Heat Outputand K = Radiation Factor ( ≅ 0.2 to 0.35)

Radiation Losses

Replacement AirReplacement Air

© Fläkt Woods

Large volume undivided buildings

M = Rate of production of hot gasses (kg/sec)M = 0.19PY1.5

where P = Perimeter of the fire in metresand Y = Height of smoke layer in metres© Fläkt Woods

AC rate vs. smoke production

C a r p a rkS iz e(m 2 )

E x tra c t b a s e d o n 1 0 A C H (m 3 /s ) H ig h /lo w H ig h le v e l le v e l o n ly

S m o k e ra tep ro d u c tio n

(m 3 /s )

1 0 0 02 0 0 03 0 0 04 0 0 08 0 0 0

6 .91 3 .92 0 .82 7 .85 5 .6

3 .57 .0

1 0 .41 3 .92 7 .8

1 0 .61 0 .61 0 .61 0 .61 0 .6

Notes:-- Effect height of car park = 2.5m- Clear Layer under smoke = 1.75m- Fire size = 3MW - Radiation loss = 25% - Fire perimeter = 12m

© Fläkt Woods

Ducted system: -Extract grills every 10m, 100 off in total

Air speed Air quality

Extractgrilles

Inlet (Via ramp)

© Fläkt Woods

Air speed Air quality

Jetfans

Inlet (Via ramp)

Extract fans

Jetfans

Jetfan system: -16 off Jetfoil fans, extract fans located in wall on the RHS

© Fläkt Woods

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