who is aom australia?...published in airah ecolibrium article on kitchen exhaust design, march 2018...

Who is AOM Australia?

1

Air and Odour Management Australia

General Industry TrendsWhat to expect in the future of hospitality

2

General Industry TrendsWhat to expect in the future of hospitality

3

• Australia’s ‘foodie culture’ is expected to underpin revenue growth in the restaurants industry in the next five years to 2022.

• Food service delivery seen as an opportunity and a threat

• The evolution of Australia’s pubs from watering holes to gastronomy destinations is seeing publicans draw a growing proportion of revenue from food

• Overseas visitors are increasingly turning to Australia for holidays with arrivals increasing by 7.1% in the year to November 2017

• The lower exchange rate is also encouraging domestic travellers (domestic overnight visits increasing by 7.2% )

What is commercial kitchen exhaust?

4

Vapour / Grease vapour

ParticulateMatter (PM)Ultra Fine (<0.1 micron)

Fine (0.1-1 micron)Coarse (>1 micron)

VolatileOrganic

Compounds(VOCs)

hydrocarbons, alcohols, phenols, aldehydes,

ketones, n-alkanoic acid, n-alkenoic acids, carbonyls,

etc.

PolyaromaticHydrocarbon

(PAH), CO, CO2, NO2,

SO2

Heat + particles + gases

5

What is commercial kitchen exhaust?

Particle Matter profile during a heavy Type 4 cooking process

0.00E+00

2.00E+08

4.00E+08

6.00E+08

8.00E+08

1.00E+09

1.20E+09

190 210 230 250 270 290 310 330 350 370 390

Part

icle

co

nce

ntra

tion

(nu

mbe

r/m

3)

Cooking time (sec)

0.3 µm

0.5 µm

1.0 µm

Size (µm) Proportion

0.3 50.20%

0.5 43.80%

1 6.18%

5 0.24%

10 0.02%

25 0.01%

TOTAL PM CONCENTRATION

Particle (0.3,0.5, 1.0 µm) profile (without treatment)

Xia Zhong (University of Sydney), Sven Bolomey (AOM Australia), Commercial kitchen exhaust contaminant removal using combined treatment techniques and

filtration efficiency assessment with developing standardised testing protocol, AIRAH Presentation Future of HVAC 2018

6

What is commercial kitchen exhaust?Odour composition is complex, more than 65 VOC compounds were detected.

• More than 50% compounds can be smelled by panellists, but only ~25% compounds were effectively tied to an odour description.

• Other identified odours include: rancid, putrid, faecal, burnt fat, decay, burning protein, burning, plastic, basoline, petrol. These are not associated to compounds.

Corresponded compound from MS Concentration (μg/m3) Identified Odour Description

Acetone 82.7 Sweet, chemical

Pentadiene 54.1 Burning

Butanal 205.4 Chemical, solvent

Butanal 205.4 Solvent

Benzene 268.4 Solvent, sweet

Cyclohexene 34.4 Burning, rancid

Heptane 614 Solvent

Vinylcyclopentane 17.9 Solvent

Toluene 61.8 Solvent (Painting)

Trans-1-Butyl-2-methylcyclopropane 169.6 Continuation of burning to solvent

Hexanal 245.3 Rancid to grassy

2-Heptanone 50.7 Fruity

Heptanal 237.3 Milky

Phenol 391.8 Sweet

Octanal 79.5 Sweet, fruity

What are the potential impacts of commercial kitchen exhaust?Health Effects of Particle Matter

7

What are the potential impacts of commercial kitchen exhaust?Environmental Impact – Potential high local impact on urban air quality

8Nikhil Pubby (Monash University), Estimate the level of compliance for non-residential kitchen exhaust systems in Melbourne CBD and evaluating the causes and

effects of increasing air pollution due to these systems – Initial Finding, AIRAH Internship, 2019

CFD analysis of the discharge point effluent

What are the potential impacts of commercial kitchen exhaust?Environmental Impact – Potential high impact on urban air quality

9Published in AIRAH Ecolibrium article on Kitchen Exhaust Design, March 2018

“The average diesel engine truck on the road today would need to drive for 10 miles (16km)

on the freeway to put out the same mass of particles as a single charbroiled hamburger patty.”

University of California

“ In New York the emissions from char broilers contributed to more than 12,5% of PM2,5

attributable deaths annually in the period 2005-2007. This equates to 400 deaths per year.”

Department of Health and Mental Hygiene

What are the potential impacts of commercial kitchen exhaust?Safety Risk - Fire

10

“I believe there was a fire on the grill and it had gotten a bit bigger than they expected,” Mr Carrigg said

"The fire on Russell St was caused by a build-up of grease in the exhaust flue (…)”

What are the potential impacts of commercial kitchen exhaust?Safety Risk - Fire

11

• In a generalized scenario: abnormal event will take place on a cooking surface (where excessive heat and flames are present) to create a flare-up.

• The most common source of a flare-up is the ignition of cooking oil vapors that come in contact with flames or excess heat.

• This flare-up produces high reaching flames that contact and/or quickly heat the hood and filters.

• If the flare-up is intense enough or sustained over a sufficient period of time (approximately 2 minutes) the flame can ignite residual grease accumulations commonly found in the hood/duct area.

• Second the ignition of combustible materials (generally wood building materials or cardboard storage containers) that are too close to the radiant heat energy being emitted from the metal exhaust duct can cause the fire to propagate

Status of Commercial Kitchen Ventilation in the Australian HVAC SectorKey documents and initiatives

12

AS/NZS 1668.1:2015

The use of ventilation and air conditioning in buildings Fire and smoke control in buildings

AS 1668.2-2012/Amdt 2-2016

The use of Ventilation and Air-conditioning in buildings Mechanical ventilation in buildings

AIRAH: Increasing awareness of Commercial Kitchen Exhaust in overall HVAC Sector: Future of HVAC, Ecolibrium, Technical Bulletins, Technical Group

Building rating systems: Green Start “Emissions” for both Design & Construction And Building Performance

Status of Commercial Kitchen Ventilation in the International HVAC SectorUSA and Europe leading way forwards – Opportunities in Asia

13

USA• ASHRAE Standard Project Committee 154 - Ventilation for Commercial Cooking Operations• ASHRAE Standard 154-2003R, Ventilation for Commercial Cooking Operations (Revision)• National Fire Protection Association: NFPA 96 Standard for Ventilation Control and Fire

Protection of Commercial Cooking Operations• UL standards: On specific elements to Commercial Kitchen Ventilation (Filters, Exhaust hood,

Fan, etc.)

EuropeEuropean Standard applicable to all EU membersBS EN 16282-1:2017 - Equipment for commercial kitchens. Components for ventilation in commercial kitchens. General requirements including calculation method.

Asia: Application of UL Standards but no clean design standard

CKV Projects: An abundance of Stakeholders

14

Concept (DA)

Architect / BCA Review

BSE / Mechanical EngineerEquipment Supplier

Kitchen Contractor / Designer

Mechanical ContractorEquipment Supplier

Mechanical Contractor / Engineer / Equipment Supplier

Owner / End UserKitchen Staff

Cleaning CompaniesEquipment Supplier

Kitchen Designer

Kitchen Contractor

Design (ConstructionCertificate)

Install (Compliance Certificate)

Commissioning (Commissioning Certificate)

O&M / Service(ComplianceCertificate)

CouncilsPlanning Authorities

Councils

Building CertifierBuilding Certifier Building Certifier Building

Management

Main challenge – Working at Interface between Kitchen and Mechanical System

15

CKV Projects: A multitude of different ProjectsWith a multitude of different issues

Base Build DesignDesigning “blindly” with building constraints (star ratings, developer requirements).

Tenancy DesignSpecific exhaust system requirements which may be difficult to integrate into a building design.

Hotel DesignMajor projects with important exhaust requirements which may be difficult to integrate into developments

Different elements to commercial kitchen system design

Which we will look into further from a design perspective

16

1. Discharge point identification

2. Cooking Type constraints

4. Exhaust hood design

3. Filtration system design

7. Ducting design

6. Fan design

5. Balancing kitchen space

Discharge Point Identification

The main way to limit any potential Impacts

17





7. Ducting design

6. Fan design


18


Constraint : AS 1668.1-2015

Ducts should be vertical and take a direct route (or as short as possible) to the outside.

19

Discharge Point IdentificationConstraint : AS 1668.2-2012 defines requirements to discharge of commercial kitchen exhaust

• Airflow < 1000 l/s : not deemed objectionable

No constraints other than to not create a nuisance and respect minimum separation distances

• Airflow > 1000 l/s : deemed objectionable

Major constraints to discharge point though Engineered Solution allows for concessions as per C3.10.3

o Odour and smoke reduction through independent testing

o Calculation of Deemed Airflow Rate

o Routine testing and maintenance

20

Discharge Point IdentificationDifferent Options – No perfect solution

21


Advantages Disadvantages

• $$$

• Can be (very) difficult to implement particularly on large developments: long horizontal ducts, large air volumes, long distances.

• Spatial and access requirements

• Fully Compliant

• Does not require any form of filtration

1 – Vertical Discharge

Ideal for standard Apartment block / ground floor tenancies type of development

22


Advantages Disadvantage • Potential for nuisance at and above podium

level

• Might require filtration


• Potential to be fully Compliant (separation distances)

• Might not require any form of filtration

• Less distance to travel to discharge

2 – Podium Level Vertical Discharge

Often used in conjunction with filtration equipment in new developments with significant exhaust requirements (F&B tenancies) in lower floors

Example: http://www.aomaus.com.au/projects/east-village/

http://www.aomaus.com.au/projects/east-village/

23



• Non compliant – requires an Engineered Solution (filtration) to treat the exhaust

• Potential for nuisance

• Potentially easier and cheaper to implement than vertical discharge

• Often located so as to minimise potential nuisance of the kitchen exhaust

3 – High level horizontal discharge

Often used in new and retro fit developments to find a reasonable solution to discharging commercial kitchen exhaust whilst minimising the risk of nuisance.

Example: http://www.aomaus.com.au/projects/aom-project-w-hotel-brisbane/

http://www.aomaus.com.au/projects/aom-project-w-hotel-brisbane/

24



• Non compliant – requires an Engineered Solution (filtration) to treat the exhaust

• High potential for nuisance

• Regular maintenance

• Constraints to type of cooking in tenancies

• Potentially a lot easier and a lot cheaper to implement than vertical discharge

• Can be adapted to the requirements of the tenancy

4 – Low level horizontal discharge

Often used in retro fit developments with limited options to managing commercial kitchen exhaust. Discharge point location and filtration design are crucial elements to minimising the risk of nuisance.

Example: http://www.aomaus.com.au/projects/pacific-bondi-beach-development/

http://www.aomaus.com.au/projects/pacific-bondi-beach-development/

25



26



27


Distance to Intakes and Deemed Airflow Rates

• Deemed Airflow Rate = Actual Airflow Rate – (Fractional Efficiency x Actual Airflow Rate)

• Fractional Efficiency = Independent testing of odour filtration processes from commercial kitchen airstream.

Cooking Type Constraints

Impact of Cooking Types on overall system design

28





7. Ducting design

6. Fan design



AS1668.2-2012 Classification to cooking Types – leads to airflow calculations

29

• ASHRAE Standard uses similar classification: Light, Medium, Heavy, Extra Heavy Duty Equipment

• EU Standards: Airflows based on cooking equipment


Significant differences in exhaust contamination between cooking equipment

30Schrock, D.W., et al., A New Standard Method of Test for Determining the Grease Particulate Removal Efficiency of Filter Systems for Kitchen Ventilation.

ASHRAE Transactions, 2006.


PM and VOCs concentrations vary importantly between commercial kitchen equipment and food sources5: type of equipment, cooking method, cooking temperature, type of food, fat content.

31

CookingHamburger Auto-

ChargrillHamburger Under-

ChargrillSteak Under-

chargrillChicken Under-

ChargrillHamburger

GriddleChickenGriddle

PM (mg/kg) 448815026

(250 g/burger – 200 burgers – 50 kg meat x 15 = 0.75kg PM)

7821 7202 Nq nq

VOCs (mg/kg) 7.24 30.48 22.57 27.90 2.61 9.51

5: MacDonald et al., 2003, Emissions from Charbroiling and Grilling of Chicken and Beef. Journal of the Air & Waste Management Association, 53:2, 185-194

nq: not qualified. Data missing in the test.

32


Chargrill and Solid Fuel – Extra Heavy Duty Equipment that is the most difficult to manage

0.00E+00

2.00E+08

4.00E+08

6.00E+08

8.00E+08

1.00E+09

0 50 100 150 200 250 300 350 400

Part

icle

co

nce

ntra

tion

(n

um

ber/

m3

)

Cooking time (sec)

Particle (0.3 µm) profile

Without treatment

HCF + Double ESP treatment




AS1668.2-2012 requirements related to Solid Fuel Exhaust

33


Example of a wood fired pizza oven discharging horizontally without any treatment

34

Project Audit after significant local complaints underlined that in additional to non compliance to AS1668.2-2012, the discharge was non compliant to Environmental Protection Act 1994 which requires discharges to be: • below 5ou for odour and staying • below 15ppm for carbon monoxide. (i.e. 6 ppm rise over ambient). • capture any of the BTEX group (i.e. benzene, toluene, ethylbenzene, and xylenes – chemicals found in

solvents or petrochemical situations).


AOM Engineering Bulletin 0006 Commercial kitchen ventilation of solid fuel appliances

35

Filtration System Design

Current state of filtration system design

36





7. Ducting design

6. Fan design


37


AS 1668.1-2015 defines requirements to filtration of commercial kitchen exhaust

1.6 System Objective Systems designed in accordance with this Standard are intended, for a single fire event, to achieve the following (….) (e) Restrict the initiation of fire within ductwork. (f) Restrict the spread of fire and smoke within ductwork.

6.2.9 Flame and Spark ArrestanceWhere the length of an exhaust duct within the building exceeds 10 m and where an exposed flame or embers may be present as part of the cooking process, devices that prevent the spread of flames in accordance with UL 1046 shall be incorporated into kitchen exhaust hoods (or filtration systems).

UL 1046 provides the following key statements with regards to the above: Construction 6 General6.2 Parts of grease filters that are exposed to cooking effluent shall be constructed of non-combustible materials.

38


AOM Engineering Bulletin 0003 Grease filtration required to be made non combustible materials

• When in doubt, use filtration equipment (in hood or in duct) made of non combustible material as per UL1046 / AS 1530.

• Filters are to precipitate grease as opposed to holding grease to restrict the spread of fire in the duct work.

39

Filtration System DesignAS1668.2-2012 - Mechanical ventilation in buildingsFiltration System Design Overall Objective: Remove the Particle Matter to mitigate Odour.

“

“

40


Three main scenarios related to location of discharge point and risk of nuisance

1. First scenario: “Do nothing” - General Tendency - moving away from this approach• Compliant to Australian Standards

2. Second scenario: “Voluntary Treatment” – Filtering Particle Matter• Compliant to Australia Standards

• Objective to decrease air quality impact: highly contaminated / high discharge airflow

• Objective to decrease risk: grease and fire

Example: http://www.aomaus.com.au/projects/spice-temple-rockpool-group/

3. Third scenario : “Compulsory Treatment”- Filtering Particle Matter and removing Odour• Non Compliant discharge

• Objective is to meet the requirements of AS1668.2-2012 Concessions

Example: http://www.aomaus.com.au/projects/ribs-burgers/

http://www.aomaus.com.au/projects/spice-temple-rockpool-group/

http://www.aomaus.com.au/projects/ribs-burgers/

41


AOM Engineering Bulletin 0004 Cooking types and filtration needs

42

Advantage Disadvantage

• Risk of over engineering - increased capital $

• Potential to under engineer

• Cost of the servicing can be high $


• Filtration located far from the source of contaminants (plant room design)

• Clear Responsibility

• Filtration equipment outlives the tenant

• Maintenance is included in building works

Equipping filtration systems within the base build design


43

Advantage Disadvantage

• Difficult to implement (tenant push back $)

• Potential for multiple systems

• Maintenance depends on the tenants

• Is flexible with changing tenants

• Exhaust and treatment design specific to tenancy cooking

• Treatment close to source

• Specific design relates to cheaper capital cost

• Is flexible with changing tenants

Imposing filtration systems at the tenancy level


Ultimately it is the building owner that holds the regulatory responsibility for fire safety at the premises.

44


Potential Efficiencies to filtration equipment

0.00E+00

2.00E+08

4.00E+08

6.00E+08

8.00E+08

1.00E+09

0 50 100 150 200 250 300 350 400

Part

icle

co

nce

ntra

tion

(n

um

ber/

m3

)

Cooking time (sec)

Particle (0.3 µm) profile

Without treatment

HCF + Double ESP treatment

45


Potential Efficiencies to filtration equipment

Filtration efficiency (%)

0.3 µm 0.5 µm 1.0 µm 5.0 µm 10.0 µm 25.0 µm

HCF 14.1 28.3 29.2 38.9 59.9 80.0

HCF + UV 18.1 30.5 30.6 41.6 58.2 78.1

HCF + ESP 79.9 98.7 98.11 82.5 96.1 100

HCF + Double ESP 88.1 98.2 97.29 82.9 100 100

HCF + ESP + AC 86.8 98.4 97.62 94.3 100 100



46

Filtration System DesignBeware of standardised equipment supplier specifications not necessarily adapted to commercial kitchen exhaust.

USEPA Method 5

Determination of Particulate Matter Emissions from Stationary

Sources

ASHRAE 52.2-2017

Method of Testing General Ventilation Air-Cleaning Devices for

Removal Efficiency by Particle Size

ASTM F1605-95

Standard Test Method for Performance of Double-sided Griddles

No current testing protocol adapted to commercial kitchen exhaust

47

Filtration System DesignVOCs removal assessment

Total VOCs removal

AC 89% vs. Ozone 92%

• Research testing showed that both ozone injection and activated carbon have a significant impact on VOCs, that compose odour.

• This is in line with independent testing carried out on specific projects.

48

Filtration System DesignBeware of the rise of the Ali Baba filtration system – no after sales, no servicing, no performance certification

49

Filtration System DesignA well designed Filtration System is only as good as the maintenance of the system

• Maintenance of filtration systems come at a cost which should be included into design phase Cost Estimates.

• Cost should include additional parts and labour.

• Certain suppliers can provide an upfront estimate / fixed quote for first year of servicing with added advantages such as warranty extensions, bank of spare filters, etc.

Movement towards remote monitoring of Filtration Plants as opposed to current fixed maintenance regimes as well as increased accessibility of Autowash systems.

50


Particle Matter Filtration - Major conclusions

• PM discharges from commercial kitchen exhaust are significant and can significantly contribute to urban air pollution.

• Concentration of contaminants depend on the cooking equipment used.

• Electrostatic precipitators are the best adapted equipment for high efficiency filtration of commercial kitchen exhaust.

• UV treatment showed no significant impact to particle removal – further testing is required to understand the impact of UV treatment.

AS1668.2-2012 calls for a reduction of contamination

51

Filtration System DesignOdour Mitigation - Major conclusions

• Odour composition is complex, forming different types of sensorial impacts.

• Testing showed that both ozone injection and activated carbon have a significant impact on VOCs that compose odour.

• However, odour is a sensorial attribute that differs between people. Current sensorial testing is complex to implement and does not allow for monitoring (AC efficiencies decrease significantly over time).

• Need to better link sensorial and chemical testing protocols.

AS1668.2-2012 states that odour mitigation is the key parameter to designing a non compliant discharge point.

Exhaust hood design

With a multitude of different issues

52





7. Ducting design

6. Fan design


Exhaust hood design

AS1668.2-2012 Constraints to hood design (Appendix E)

53

• E3.4.1 Sloping All surfaces of the hoods exposed to the appliance being ventilated shall be sloped at an angle not greater than 40 degrees from the vertical, unless the design and performance of the hoods prevent the formation of condensate on such surfaces.

• Minimum hood heights when designing hoods based on standards are:

➢ Hood over woks or ovens: 920 mm

➢ Hood over grills, stove, etc: 700 mm

Exhaust hood design

Hood Type 7 Proprietary Equipment

54

Exhaust hood design

Example of Proprietary Hood airflow calculations that significantly reduce the exhaust requirements.

55

• Standard hood calculation method for Type 4 cooking:

Hood 2: 375 x 1.2 x (4.3+4.3+2.3+2.3) = 6,120 l/s

No. Cooking Process Type

Hood Type Dimensions (mm) Exhaust Air Flow Rate

(L/s)

Make up Air Flow Rate

(L/s)

1 5 – High Grease / High Heat

4 – Island 4,850 x 2,700 6,795 6,150

2 4 – High Grease / Med. Heat

4 – Island 4,400 x 2,400 6,120 5,600


4 – Island 4,400 x 2,700 6,390 5,750


4 – Island 4,400 x 2,700 6,390 5,750

5 3 – High Grease / Low Heat

3 – Sidewall 4,400 x 1,350(1500)

1,620 1,490


4 – Island 7,800 x 1,900 8,730 7,900

• Standard hood calculation method for Type 2 and Type 4 cooking:

Hood 2:

Type 4: 375 x 1.2 x (4.3+1.15+1.15) = 2,970 l/s

Type 2: 190 x 1.2 x (4.3+1.15+1.15) = 1,500 l/s

Total: 4,470 l/s

Exhaust hood designExample of Proprietary Hood airflow calculations that significantly reduce the exhaust requirements – yet consider condensation risk of the given equipment

56

Kitchen Exhaust Hood airflow calculation based on AS1668.2-2012 Section 3.6

Project 3663 WA Kitchen Galley Hood 2

Qs

MJ kW(as per

table A1)L B H

Qsk (W) =

0.5 x P x Qs(W/kW)

1 Tilting kettles Not given (80L) 35 100 0.813 0.641 1.016 1750 441

2 Tilting kettles Not given (80L) 35 100 0.813 0.641 1.016 1750 441

3 Griddle Waldorf GP8900G-L5 80 22.2 330 0.9 0.85 0.915 3663 588

4 Griddle Waldorf GP8900G-L5 80 22.2 330 0.9 0.85 0.915 3663 588

5 Fryer Waldorf FN8118G 90 23.3 90 0.522 0.864 1.13 1048.5 1030

k z

Hydraulic

diameter

(m)

(dhydr)

reduction

factor (r)

simultanei

ty factor

(ϕ )

(z + 1,7 x

dhydr)Vth

Displacement

factora. Vth final

Steam

Production

check (Vabl)

Constan

t

Height

to hood

(m)

2 x L x B

/(L + B)

island

hood

as per

table A2m3/h As per table 4 m3/h m3/h

18 0.984 0.72 1 0.7 2.20 566.15 1.2 679.38 1500.63

18 0.984 0.72 1 0.7 2.20 566.15 1.2 679.38 1500.63

18 1.085 0.87 1 0.7 2.57 937.32 1.2 1124.78 1269.10

18 1.085 0.87 1 0.7 2.57 937.32 1.2 1124.78 1269.10

18 0.87 0.65 1 0.7 1.98 398.41 1.2 478.09 2333.24

Totals 4086.43 7872.69

Airflow (l/s) 1135.12 2186.86

Final applied airflow* 2734

Ccooking line specifications

P Equipment dimensions (m)

Thermally induced airflow Vth (m3/h) = k x (Qsk)1/3 x (z + 1,7 x dhydr)5/3 x r x ϕ Final airflow

Convective Share Steam Equipment Specifications

Exhaust hood design

Example of Proprietary Hood airflow calculations that DO NOT reduce the exhaust requirements – BECAUSE the calculations considers condensation risk of the given equipment

57

• Specified hood dimensions: 9000 (l) x 1650 (w) x 600 (h) mm

• Type 3 cooking: 190 x 1.1 x (8.9+1.55+1.55) = 2,300 l/s

Note: height of the hood is not feasible with a standard hood

Exhaust hood design

Example of Proprietary Hood airflow calculations that DO NOT reduce the exhaust requirements – BECAUSE the calculations considers condensation risk of the given equipment

58

Kitchen Exhaust Hood airflow calculation based on AS1668.2-2012 Section 3.6

Project Hood 1 3993 WA Koodaideri Village

Qs

MJ kW(as per

table A1)L B H

Qsk (W) =

0.5 x P x Qs(W/kW)

1 Combi Oven CTR SCC5S201 E 36 180 0.879 0.791 1.7 3240 265

2 Griddle GP8120E-LS 57 30 350 1.2 0.85 0.915 5250 588

2 Griddle GP8120E-LS 57 30 350 1.2 0.85 0.915 5250 588

3 Fryer FRE24DL 140 21 90 0.61 0.8 1.12 945 1030

3 Fryer FRE24DL 140 21 90 0.61 0.8 1.12 945 1030

3 Fryer FRE24DL 140 21 90 0.61 0.8 1.12 945 1030

3 Fryer FRE24DL 140 21 90 0.61 0.8 1.12 945 1030

k z

Hydraulic

diameter

(m)

(dhydr)

reduction

factor (r)

simultanei

ty factor

(ϕ )

(z + 1,7 x

dhydr)Vth

Displacement

factora. Vth final

Steam

Production

check (Vabl)

ConstantHeight to

hood (m)

2 x L x B

/(L + B)

island

hood

as per

table A2m3/h As per table 4 m3/h m3/h

18 0.3 0.83 0.63 0.7 1.72 288.77 1.2 346.53 927.50

18 1.085 1.00 0.63 0.7 2.78 756.78 1.2 908.13 1715.00

18 1.085 1.00 0.63 0.7 2.78 756.78 1.2 908.13 1715.00

18 0.88 0.69 0.63 0.7 2.06 259.11 1.2 310.93 2102.92

18 0.88 0.69 0.63 0.7 2.06 259.11 1.2 310.93 2102.92

18 0.88 0.69 0.63 0.7 2.06 259.11 1.2 310.93 2102.92

18 0.88 0.69 0.63 0.7 2.06 259.11 1.2 310.93 2102.92

Totals 3406.50 12769.17

Airflow (l/s) 946.25 3546.99

Final applied airflow* 3500

Ccooking line specifications

Final airflowThermally induced airflow Vth (m3/h) = k x (Qsk)1/3 x (z + 1,7 x dhydr)5/3 x r x ϕ

Convective Share Steam Equipment Specifications

P Equipment dimensions (m)

Exhaust hood design

Advantages to Performance Hoods

59

• More flexibility in the design (dimensions) of the exhaust hood.

• Integrated Make Up Air systems which improve capture of exhaust and facilitate overall balancing of kitchen space.

• Higher quality finishing including LED lights, high efficiency in hood grease filters.

• In light of their design, generally allow for additional filtration to be located within the exhaust hood: UV systems, Electrostatic Precipitators.

• Better management of exhaust airflows with overall tendency being a decrease in exhaust rates.

However the exhaust hoods need to prove performance to a tested standard and clearly be able to justify specified exhaust rates – otherwise, they are simply an expensive box.

Balancing kitchen space

Creating a perfect commercial kitchen working space

60





7. Ducting design

6. Fan design



General Make Up Air Strategies

61

• Minimise the exhaust requirements.

• Standard practice - 80% of the exhaust air value to be replaced within the kitchen spaceo In or close to the exhaust hood: 60%o A/C of kitchen space: 20%o Transfer air: Balance of 20%

• Displacement ventilation systems as opposed to mixing ventilation to be used in the vicinity of the exhaust hood.

• Increased use of Transfer Air (up to 50%) in order to recycle used conditioned air as MUA, thus also improving the working conditions in the kitchen.


In hood MUA solutions: methods with limited scope

62

• Replacement air introduced directly into the hood cavity of kitchen exhaust hoods shall not exceed 10% of the hood exhaust airflow rate.

• Air curtain is a “risky design option” and it is recommended limiting the percentage to a maximum of 20% of MUA.


In hood MUA solutions

63

• It is vital that front face MUA be limited in velocity, be provided in a horizontal direction and be delivered uniformly through the front face of the hood.

• Potential for up to 80% of MUA.


Displacement diffusers

64

• Supplying make up air through displacement diffuser at a good distance away from the hood.

• Similar to low velocity “transfer air” from the dining room

• Diffusers require floor /wall space which is difficult in a commercial kitchen.

• Terminal velocity and edge of the hood capture area should not exceed 0.25 m/s

Fan Design

Where Commercial Kitchen Ventilation Design can work towards Energy Efficiency

65





7. Ducting design

6. Fan design


Fan Design

Demand Control Kitchen Ventilation

66

If a kitchen/dining facility has a total kitchen hood exhaust airflow rate greater than 5,000 cfm then it shall have one of the following:

a) At least 50% of all replacement air is transfer air that would otherwise be exhausted.

b) Demand ventilation system(s) on at least 75% of the exhaust air. Such systems shall be capable of at least 50% reduction in exhaust and replacement air system airflow rates(…)

Fan Design

Demand ventilation system(s) – Can achieve up to 50% Energy Savings

67http://www.wbdg.org/FFC/ARMYCOE/TECHNOTE/technote21.pdf

• Manual system with a single-phase 2-speed motor (high or low)

• Automated system with a single-phase 2-speed motor (high or low)

• Control System for 3-phase motors with variable speed (temperature sensors)

• Advanced Control System (temperature and optic sensors)

Ducting Design

Main elements allowing for demand ventilation systems

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7. Ducting design

6. Fan design


Ducting Design

Maximum Velocity through ducting

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• Horizontal ducting generally designed to around 7.5 m/s velocity.

• NFPA 96 Code changed to 2.54 m/s as minimum design velocity – allowing for Demand Control Ventilation

• Three key actions to grease deposition in ducts.

1. Gravitational settling

2. Turbulent deposition

3. Thermophoresis

Ducting Design

Designing to standards versus designing to maintain

70

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Final Thoughts - From Design to Supply / Install to Maintenance

Designing and Installing a performant Commercial Kitchen Ventilation System requires that all different elements are fully integrated.

• Decreasing local impacts:

o A well designed discharge point is a function of airflow (exhaust hood), cooking type and implemented filtration equipment.

• Optimising system performance:

o A well comfortable workplace and energy efficient commercial kitchen is a function of exhaust hood performance in a well balanced space and fan selection / duct design.

• Decreasing risk:

o A system that decreases grease accumulation and allows for effective maintenance is a function of exhaust hood, specified filtration systems and duct design.

Full system design should be undertaken by the Mechanical Engineer and Supplied / Commissioned by the Mechanical Contractor.

Thank YouSven Bolomey

1300 903 788

[email protected]

www.aomaus.com.au

aom_australia

Air and Odour Management

airandodourmanagement

who is aom australia?...published in airah ecolibrium article on kitchen exhaust design, march 2018...

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