Commercial Kitchen

Commercial Kitchen Ventilation

Slide 1 14.9.2004

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How can we define a Professional Kitchen ? IT’S A UNIQUE SPACE WHERE : • Meals are prepared (Hot and cold kitchen)

• Dishes and equipment are washed

• Foodstuff is stored Slide 2 14.9.2004

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Why do we need a ventilation system in commercial kitchens ? TO ENSURE THE MOST PLEASANT WORKING ENVIRONNEMENT 1. Remove immediately excess heat 2. Remove particules of grease , odours, exhaust gases ... 3. Remove moisture

4. Renew the air to refresh the working place and replace exhausted air Slide 3 14.9.2004

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Where do the heat loads generated in a commercial kitchen come from ? Mainly from COOKING PROCESS’ and 1. Convective COOKING EQUIPMENT. Heat 1. Convective heat => can be captured by a hood. (totally or partly depending on hood efficiency) 2. Radiated heat => can not be captured by any hood. 3. Other : • heat transfer through windows, walls, ceiling • occupants • lights • other appliances Slide 4 14.9.2004

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2. Radiated Heat

How are exhaust rates calculated in a commercial kitchen ? • •

EXHAUST AIR FLOW (Qve) rate is DIRECTLY related to : quantity of CONVECTIVE HEAT (Qvc) generated by the cooking equipment EFFICIENCY (Heff) of the hood system Qve

IT’S A HEAT LOAD BASED DESIGN !!!

Qvc = Output of Cooking Equipment Qvc = Qvc1 + Qvc2 + Qvcn Qve = H.eff x Qvc

Qvc1

Qvc2

This means : That design methods not based on cooking appliances (m3/h/m, m3/h/m², m3/h/meal, face velocity) can not provide accurate results. Cooking equipment Slide 5 14.9.2004

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Qvc3

How convective heat loads are calculated for each piece of cooking equipment ? •

According VDI 2052* standard

Qs,k = P ⋅ Qs ⋅ b ⋅ϕ

Convective Heat Flow (W)

Appliance Input Power

*Verein Deutscher Ingenieure Slide 6 14.9.2004

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Simultaneous Factor

Convective Fraction of the total amount of heat release (0,5) Appliance Sensible Factor

VDI Standard (continued) Exhaust Flow

Convective Heat Flow

Hydraulic Diameter

Reduction Factor

1/ 3 = ⋅ Vth k Qs ,k ⋅ ( z + 1.7 ⋅ d hydr ) ⋅ r

Height Above Appliance

Slide 7 14.9.2004

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Supply ventilation also affects the exhaust flow required

What are the strengths and weaknesses of VDI ? C • •

•

Accounts for convective plume from cooking appliance. Accounts for different ventilation strategies (e.g. mixing versus displacement). Neutral method not coming from a hood manufacture.

D •

Slide 8 14.9.2004

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Does not account for differences in hood design and hood efficiency between different manufacturers

How to measure hood efficiency ? SPILLING

CAPTURING

ASTM 1704 HEAT GAIN CURVE – GENERIC EXAMPLE CAPTURE & CONTAINMENT

Heat Gain CONVECTIVE

RADIANT

Slide 9 14.9.2004

Exhaust rates

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RADIANT

How can we define hood efficiency ? Exhaust only hoods (traditional system) If excess heat and impurities are not captured by the hood and are spread to the occupied zone. The hood effciency is not good. Not a comfortable working area. Common Solution Increase exhaust air flow (Qve) to guarantee front velocity especially in Critical Zone. Higher dilution of room air to remove load. Higher energy consumption. Slide 10 14.9.2004

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Qvc / Heff = Qve

?

Qve Exhaust only hood

CRITICAL ZONE

Qvc

Short Cycle system, 50 to 70% Induction Designed first in the USA when high exhaust rate followed exclusively the model codes. Large volumes of untreated air is supplied directly in the hood (50 to 70% of exhaust air).

Qvc + Qvi = Qve

!

Qvi

Qve

High air flow rates to guarantee acceptable efficiency and to exhaust ”short circuit” air. Thermal Plume (Qvc) is disturbed and big problems occur during winter time.

Qvc Inefficiency and poor working conditions. System not advocated any more in Europe and USA. Slide 11 14.9.2004

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HALTON Capture Jet Hoods = High Efficiency Capture Jet technology designed by HALTON in 80’s to prevent spillage at low exhaust rates.

Qvc + Qcj = Qve

Qcj

Qve

Use of high velocity Capture Jets to increase face velocity of the hood with lower air flow. Capture Jets push the thermal plume towards the filters without interfering with the convective flow.

Qvc Efficiency is higher and air flow rates 35% lower compared to exhaust only hood system. Supply/make up air is reduced as well. Technological and energy efficient system. Slide 12 14.9.2004

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20 l/s/m is about 10% Capture Jet Air

Capture Jet Demonstration

Slide 13 14.9.2004

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Demonstration n°1 : Tracer Gas Study Qcj

Qve me eff =

260ºC

eff %

70 %

83 %

Exhaust only Qcj=0 Qve=600 m3/h

mtg

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me mt g

84 %

90 %

Capture jet

Qcj=0 Qcj=60 m3/h 3 Qve=1000 m /h Qve=600 m3/h

Qcj=100 m3/h Qve=1000 m3/h

Demonstration n°2 : Computer Modeling (CFD*)

KVI with Capture Jets OFF (same as hood exhaust only) (Surface Temperature : 315°C)

*Computational Fluid Dynamics Slide 15 14.9.2004

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KVI with Capture Jets ON (Surface Temperature : 315°C)

Demonstration n°3 : Schlieren Thermal Imaging • • •

Visualizes changes in air density More sensitive than visualizing smoke Quickly see impact of design changes

KVI with Capture Jets OFF (same as hood exhaust only) (Appliance : 315°C)

KVI with Capture Jets ON (Appliance : 315°C) Slide 16 14.9.2004

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Schlieren Thermal Imaging Video : KVL case study

Slide 17 14.9.2004

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Demonstration n°4 : ASTM F1704 KVL laboratory test to measure how much heat is released into the kitchen : Full Load cooking conditions

SPILLING

CAPTURING

HOOD TYPE EXHAUST RATE CAPTURE AIR TOTAL EXHAUST Capture Jet 620 m3/h (172 l/s) 37 m3/h (10,2 l/s) 657 m3/h (182 l/s) No Capture Jet 850 m3/h (236 l/s) 0 m3/h 850 m3/h (236 l/s) Test set up using a electric Griddle (17,1 KW)

Idle conditions (non-cooking) HOOD TYPE EXHAUST RATE CAPTURE AIR TOTAL EXHAUST Capture Jet 510 m3/h (142 l/s) 37 m3/h (10,2 l/s) 547 m3/h (152 l/s) No Capture Jet 1037 m3/h (288 l/s) 0 m3/h 1037 m3/h (288 l/s) Test set up using an electric Griddle (17,1 KW)

Heat Gain

CAPTURE & CONTAINMENT CONVECTIVE RADIANT RADIANT

Exhaust rates

”Under the full-load cooking scenario, the capture jet technology reduced the airflow required for complete capture and containment by 27% and for the idle (non-cooking) situation, the jet reduced C&C by 51%.” Slide 18 14.9.2004

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Demonstration n°4 (continued) : ASTM F1704 KVI Laboratory test to measure how much heat is released into the kitchen : HOOD TYPE EXHAUST RATE Capture Jet 1530 m3/h Exhaust Only 2210 m3/h

CAPTURE AIR 90 m3/h 0 m3/h

TOTAL EXHAUST DUCT T° RISE HEAT GAIN 1620 m3/h 24°C 998 W 2210 m3/h 17,5°C 980 W

Test set up using an under fired charbroiler, 600 F surface temperature

Equivalent heat gain, but capture jet hoods use 30% less exhaust air to do the same job.

Slide 19 14.9.2004

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Demonstration n°5 : EDF* Heat gain for different hood systems 3000

Heat Gain (W)

2500

2000 50% induction 10 % capture jet

1500

Exhaust hood only 1000

500

0 3 700

4 200

4 800

5 300

3

Exhaust rate (m /h)

” the 50% induction hood creates a lot of turbulences in the thermal flow especially when extract rate increases. The efficiency is even worse than a traditional exhaust only hood ” Independent test made by Electricité De France Slide 20 14.9.2004

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Demonstration n°5 (continued) : EDF Capture efficiency benefit Capture efficiency benefit (%)

60 40 20 0 -20 50% induction

-40

10% induction

-60 -80 -100 -120 -140 3 200

3 700

4 200

4 800

5 300

Exhaust rate (m 3/h)

” The test shows that performances of the hood is depending very much on the % of induction air. If it’s too high (50%, 70%), turbulences prevent the hood from having a good efficiency. If it’s about 10%, efficiency can be improved by 20 to 50%, that means an equivalent reduction of extract rates.” ”Performances are not coming from the fact we are supplying untreated air, but from a better capture efficiency of the hood”. Slide 21 14.9.2004

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KSA Multi Cyclone Grease Filter Halton Patented Design • • • • • •

Uses cyclonic effect to improve filtration efficiency Non-clogging design Low and constant pressure drop Easy to clean All stainless steel 93% to 98% efficient on particules between 5 and 10 microns

ƒ

ƒ ‚

Slide 22 14.9.2004

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•

KSA filter : The Cyclonic Effect !

Slide 23 14.9.2004

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What about other conventional filters ? BAFFLE FILTER

• • •

•

MESH FILTER

• • •

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Higher pressure drop (125-150 Pa) Lower grease extraction efficiency Higher noise level

Low pressure drop when clean, but when dirty pressure drop increases quickly Difficult to wash Risk of fire when grease collected in the filter Short life cycle

T.A.B. Test & Balance Ports

KVF-3000(E)

2001.02

qv(dpm) E a k

0

1

2

79.00 70.30 52.00

2

300

1 0

200 100

pm [Pa]

50 30 20 10

• EASE OF BALANCING

5

200

300

500

qv [l/s]

• FIELD SYSTEM FOR BALANCING AIR FLOW RATES Slide 25 14.9.2004

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1000

Make-up Air with Mixing Ventilation (CFD)

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Make-up Air with Displacement Ventilation (CFD) •

Slide 27 14.9.2004

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According to new VDI 1999, mixing ventilation system requires 15 to 20% higher exhaust rate than displacement system for the same efficiency.

Make-up Air : Select the Best System ! Low velocity

Mixing

•

Low supply velocity (8m/s).

•

Based on natural convection effect.

•

Grilles or ceiling diffusers.

•

Displacement unit can be included in the hood = KVF or in cupboards.

•

•

No mixing between new air and room air, but room air is displaced from the occupied zone to the hood.

Purpose is to mix new air with room air as much as possible.

•

Thermal plume is disturbed especially when supply units are close to the hood => SPILLAGE.

•

Thermal plume is not disturbed => SlideASSIST 28 14.9.2004 THE CAPTURE.

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Thermal Comfort, Productivity and Kitchen Ventilation *

Results from a study conducted in Finland

100

Productivity, %

90 80 70 60 50 40

Recommendations: T = 26 – 27 °C HR = 65 % 45 dB (A)

30 20 22

23

24

25

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27

Room Temperature, °C

With bad system : •The temperature can increase •Employees can feel more uncomfortable •This can affect both efficiency of staff and turnover Slide 29 14.9.2004

26

28

30

32

How to measure thermal comfort in a professional kitchen ? •Utilizes a breathing thermal mannequin •Measures skin temperature and power to maintain temperature. •Mean thermal vote calculated at 25 body locations.

Slide 30 14.9.2004

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Satisfaction Measurement Exhaust only hood

V = 0 m/s

Hood with low velocity local supply

20% people satisfied

Hood with low velocity local supply directed downwards

V = 0,1 m/s

25% people satisfied

Hood with low velocity supply + Personal air supply Nozzle

80% people satisfied

V = 0,25 m/s

50% people satisfied

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V = 0,40 m/s

IDEAS: Integrated Design, Exhaust and Supply •

• • • • • •

Slide 32 14.9.2004

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From 100 kWh energy consumption in a kitchen, 56 kWh are for heating of make-up air (Electricité de France) 31% of restaurants expenses are for wages and salaries 5 to 10% of restaurants expenses are for energy bills A 2 °C temperature increase can decrease productivity 10% Improved thermal comfort through integrated design approach Improved indoor air quality = higher retention of valuable employees Reduced training cost due to higher retention

Halton HELP: Hood Engineering & Layout program • • • •

Slide 33 14.9.2004

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Heat load based design on kitchen exhaust. Effect of air distribution type factored for hood performance. Accounts for non hooded equipment. Energy savings and improved I.A.Q.

Factor Effect of Air Distribution System Mixing ventilation

Displacement ventilation

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Halton HELP : Changing your perspective

Slide 35 14.9.2004

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Halton HEAT : Halton Energy Analysis Tool •

•

• •

Slide 36 14.9.2004

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Evaluate first cost and operating cost between Capture Jet and competing systems. Calculate “true” exhaust rate for competing systems. Evaluate environmental impact. Determine R.O.I.

Halton HEAT : Annual Costs Comparison Capture Jet hoods have a short pay-back time

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Halton HEAT : Saving Report

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KVI : Capture Jet Canopy

UK: Tesco store in Woodford Green

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KVF : Capture Jet Canopy, Supply and Exhaust

France: LEP Chenevard

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KVL : Capture Jet Backself Hood

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Air Conditioning Ceiling with Capture Jet

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Air Conditioning Ceiling with Capture Jet

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KWF : Capture Jet Water Wash Hood with Supply Air

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KWI : Capture Jet Water Wash Hood

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KVV: Steam or Condensate Canopy

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Reference List : Some Among the Others ...

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UK: Tesco Store in Woodford Green

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Ventilated Ceiling : KCE

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France: Centre AFPA -Douai-

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Steam Canopy : KVV

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France: School -Lycée Allende, Béthune-

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Capture Jet + Supply : KVF

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Ventilated Ceiling : KCE

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UK: Tesco Store in Woodford Green

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USA: Tennessee Mountain in New York

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UK: Tesco Store in Wokingham -

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Capture Jet + Supply : KVF

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Ventilated ceiling : KCE

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Rolland-Garros Stadium - France KVF, KVI, KVV

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Lycée Armentières - France KCF, KVF

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Hotel Restaurant La Chartreuse France - KVF

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School Canteen - France KCF

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Ventilated Ceiling KCF –Hong Kong -

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