6. JetVent Impulse Ventilation for Carparks V4.5

8/13/2019 6. JetVent Impulse Ventilation for Carparks V4.5

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Fifth level

Impulse Ventilation for Car ParksA Practical Guide for Selection & Application


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Why Should We Consider The Use of

Impulse/Induction Ventilation?

Capital cost savings can be found through reduced car

park height and less site excavation.

Slab penetrations can be reduced. Less, or no need for

plant rooms, ducting and plenums, allowing more space

for parking etc.

The car park is too large to ventilate naturally.

More effective dilution of contaminants within car park

environment than required by the Standards.


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Typical Ducted System Installation

32 min., +60m visibility


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Typical Impulse Fan Installation



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So What Is Impulse/Induction

Ventilation? The use of Jet fans to

move and to mix the airwithin an entire space.

Pollutants are efficientlydiluted throughout the

entire volume or space.

Fresh air is introducedand exhaust air removedfor closed car parks vianatural or mechanical

means.

No ductwork network forsupply & exhaust air.

Conventional ducted system

Impulse system


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Fifth level

How Does An Impulse/Induction

System Work?


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Examples of Impulse/Induction fan

Installations

Axial

Centrifugal

Multi-

Flow


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Impulse/Induction Ventilation

Schemes

There Are Three Arrangements That We Can Use:

Linear Flow

Circular mixing / flow

Assisted natural flow / augmented (part) ductedsystem


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Linear Flow


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Circular Mixing


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Assisted System


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Fan Arrangement - Best Practice

Fans Discharge Parallel To Beams Fans Discharge Perpendicular To

Most Effective Beams Less Effective


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Watch Out For Obstructions

Obstruction Too Close Obstruction Out Of The Way

Always ensure that best practice is followed with respect

to site coordination between trades to avoid unnecessaryclashes between fans, pipe work, signage and any otherobstructions.


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Examples of Clashing Between

Services


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Fan Sizing and Quantities

Based on 5N per 100m2 floor area, minimum total fan thrust = car park floor area x 5N/100m2

= 1920m2 x 5N/100m2

= 96N

Minimum thrust criteria can be achieved with 4 x JISU-CPC-50N fans on low speed (operating thrust 25N),

total fan thrust= 25N x 4= 100N


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Thrust Ratings & Throw Distance

Fan spacings are recommended guidelines for

fans in series

Maximum coverage relate to distances from fan

where air speed >1m/s

Width of coverage taken to be 20m Generically


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Thrust Rating Vs Noise Levels


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Axial Impulse FanMax. Thrust 50N (High Speed) 12N (Low Speed)

(Based upon JVU-CPA-400, 400 dia. 2/4pole motor,

423mm height).


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Centrifugal Induction FanThrust 100N (High Speed) 50N (Low Speed)

(Based upon JISU-CPC-100N with VSD, 320mm height).


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Overhead Height Requirements


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Control Options

Jet Fans suit individual switching

CO Sensors and control logic required forbest efficiency

Fans 2 Speed, VSD Speed Controlled

or EC Motored

Typically CO sensors control a zone of

400m2

Energy Saving Opportunity


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Control Versus CO Contamination

(Two Zones)


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Ducted System ResponseAt Part Occupancy


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Impulse System ResponseAt Part Occupancy


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Impulse Control System - Overview


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Two-Speed Control


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Analogue Variable Speed Control

T i l C t l


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ExpansionBoards for >2

CO sensorsper controllerJetVentZone

Controllers

VSDs

Sinusoidal Filters

(external rotor motors)

Typical Controls

Cabinet (Analogue)

24Volt AC

Transformer

3 Ph.

Isolators


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JIU CPCEC 55N Digital EC FanElectronicallyCommutated motors

Thrust 55N (High Speed) 35N (at 65 dBA)

(365 mm height - currently)


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Wiring arrangement for EC

Digital Induction fan


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BCA Ventilation Legislative

Requirements

This system is an alternative solution under theBCA, as opposed to a Deemed-to-satisfy ductedsystem

Relevant performance requirements are in terms ofCO Concentration 100/60/30ppm - peak, 1hr Avg &8hr Avg requirements

Systems are validated by either proof ofperformance (usually CFD) or using expert

judgement


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CFD Modelling

Expertise available via specialized consultancies

Useful to validate performance, AS1668.2 requirements

Analysis done on PHOENICS, FLUENT and other codes

CFD Plot with Velocity Vectors, Scale in m/s

CFD Plot of CO Concentration Levels, Scale in ppm


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Velocity PlotsDucted System


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Velocity PlotsImpulse System


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Induction Fan Smoke Test

System viewed in SE Asia, designed to BS7346-7:2006

Systems designed to BS7346-7:2006, usuallycommissioned with Hot/Cold Smoke tests, rather thanCFD for Fire Brigades.

Gives a visual indication of how well the system works.

Car park smoke logged prior to fan operation.

Fans started and smoke production ceased at 0 minutes.

A ducted system typically clears to 30m visibility in30-40min.


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Start, Approx 8.0m visibility

Smoke Clearance & Visibility Test


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+5 min., 12m visibility

8 min., 16m visibility

12 min., 24m visibility 15 min., 32m visibility



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Third level Fourth level Fifth level

Smoke / Fire Requirements

AS1668.1:1998 (Clause 5.5) states:Car park ventilation systems are not required as smokecontrol systems and the requirements of section 4 arenot applicable.

Exhaust fans not temperature rated, but go into fullspeed if fire is detected

Supply fans and Impulse fans shut down in the event of

smoke intake

Full manual overrides for attending Fire Brigade


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Case StudyIKEA Harvey Norman


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Project summary

Located in Springvale approx. 20km South East ofMelbourne CBD

71,000 m2 of bulky goods retail space. LargestHomemaker Centre in southern hemisphere

Car park floor areaapprox. 100,000m2

2800 car spaces over 2 levels

Semi enclosed upper and lowerlevels


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Fan details

94 x Fans installed on both floors

A special JIU-CPCEC-92N modeldeveloped specifically for this project

Onboard isolation, electronicprotection and speed control on thefan itself


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Case StudyIkea Harvey Norman

3D layout lower & upper levels


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CFD analysis

Airflow Pollution

C S


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Cost savings

Electrical installation simplified due to onboard isolatorsand speed control (Reduction in wiring)

Reduction in the size and number of mechanical

switchboards due to the deletion of external variablespeed control and active line filtration

Ducting and shaft risers removed, no visual obstructions

C

C St d IKEA H N


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Theresult

Cli k di M i l l


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Conclusion

Impulse/Induction Ventilation offers the client acommercially viable alternative option to the traditional1668 Car park ventilation design

The system offers simplified building design and a

reduction in construction cost Simplified electrical and mechanical installation

This system is approved as an alternative solution underBCA. CFD analysis best to confirm designs and provideproof of performance

Energy Savings / Demand Control

Documents

6. JetVent Impulse Ventilation for Carparks V4.5