kongress kgh december 2018 beograd serbiaair change rates & ventilation air change rates denote...

KONGRESS KGH – DECEMBER 2018

BEOGRAD SERBIA

SIMON HARTLES – EXPORT DIRECTOR COOL-SPACE EVAPORATIVE COOLING

CONTENTS

PART 1: FUNCTIONALITY OF EVAPORATIVE COOLING: HOW IT WORKS IN PRINCIPLE

NATURAL COOLING

HOW IT WORKS IN PRACTICE HOW IT IS RECREATED IN PRACTICE

COOLING EFFECT AND HUMIDITY

EXPECTATION OF PERFORMANCE

ENERGY IMPACT CONSUMPTION OF ELECTRICITY & WATER

Cf. AIR CONDITIONING

CONTENTS

PART 2: DESIGNING A SYSTEM REQUIREMENTS OF VENTILATION

FIXED COOLING

PORTABLE COOLING

PART 3: APPLICATIONS APPROPRIATE USES

APPLICATION EXAMPLES

INAPPROPRIATE USES

LEGIONELLA RISK

PART 4: QUESTIONS

PART ONE

EVAPORATIVE COOLING: DEFINITION

AND FUNCTIONALITY

NATURE’S COOLING SOLUTION

34℃ (DB) INLAND

ON THE SEA

IT’S 22℃

WHAT’S HAPPENING?

WATER VAPOUR IN AIR

Wind / Breeze

SUSPENDED WATER VAPOUR DISPLACES HEAT

35.0 ℃ DB

21.0℃ WB

ATHENS, GREECE

Summer Peak ave

Resultant temp 22.0℃

90% RH

PORTABLE EVAPORATIVE COOLER

HOW IT WORKS

• The fan draws

hot air in

HOW IT WORKS

• Hot dry air is

drawn through

the thick moist

Media pad

HOW IT WORKS

Water evaporates

through the

passing air –

displacing heat

HOW IT WORKS

• Result is a mist

less discharge –

cooling people

and spaces

COOLING EFFECT - BEOGRAD

33.7 ℃ DB

21.2℃ WB

BEOGRAD, SERBIA

Summer Peak ave

85% RH

Resultant temp 23.0℃

COOLING CALCULATION DRY BULB TEMPERATURE (DB): 33.7 ℃

WET BULB TEMPERATURE (WB): 21.2 ℃

PAD EFFICIENCY 85%

DISCHARGE TEMP = DB–0.85(DB-WB)

RESULT = 23.0℃ DISCHARGE TEMP.

COOLING EFFECT - BEOGRAD

33.7°C to

23.0°C = 10.7°C

cooler

10°C Cooling in Beograd

HOW MUCH DOES IT COOL?

EVAPORATION CALCULATION CALCULATE MOISTURE CONTENT OF AIR:

MEASURE FROM PSYCHROMETRIC CHART:

DB 33℃ / WB 21℃ = 10.8 g/KG OF DRY AIR

DB 23℃ / WB 21℃ = 15 g/KG OF DRY AIR

INCREASE IN MOISTURE 4.2 g/KG OF DRY AIR (IM)

M³/H x (g/1000 IM) x (KG of 1 m³ AIR) x (KG/L WATER)

16,600 M³/H x 0.0042 x 1.293 x 1 = 89

89 LITRES PER HOUR EVAPORATION RATE

ENVIRONMENTAL IMPACT• NO CFCs OR HFCs

• AIR, WATER SINGLE PHASE ELECTRICITY• < 6 AMPS

• 4 WATTS

• ELECTRICITY 8 KWH PER YEAR

• EQUIVALENT COOLING POWER KW• Heat lost = 0.28 m3/s x 1.005 kJ/(kg

K)[absorption] x 1.205 kg/m3 x (delta T) K (actually C) [density]

• FOR 16,500 M³/H AND 10℃ ∆T= 55 KW COOLING

• HOW MUCH WOULD A 55 KW DX AIRCON SYSTEM COST TO RUN?

ERGONOMIC IMPACT

PART TWO

DESIGNING A SYSTEM

AIR CHANGE RATES & VENTILATION

EVAPORATIVE COOLING REQUIRES VENTILATION

TYPES OF VENTILATION IN A BUILDING:

NATURAL

OPEN WINDOWS/ DOORS, STACK EFFECT, WIND IMPACT

MECHANICAL

FAN INPUT/EXTRACT AXIAL OR DUCTED

BOTH MECHANICAL & NATURAL

AIR CHANGE RATES & VENTILATION

AIR CHANGE RATES DENOTE AS ACH AIR CHANGE RATE PER HOUR

NATURAL VENTILATION OPEN WINDOWS/ DOORS, STACK EFFECT, WIND IMPACT

RULE OF THUMB:

0.5 AIR CHANGES/HR IS USED FOR TIGHT (SEALED) BUILDINGS

1/HR FOR MODERATE

2/HR FOR LOOSE ONES (OLD OR WITH ALL WINDOS AND DOORS OPEN)

MECHANICAL FAN INPUT/EXTRACT AXIAL OR DUCTED

DETERMINED BY SYSTEM PERFORMNACE

AIR CHANGE RATES & VENTILATION

AIR CHANGE RATES & VENTILATION

SOURCE: CIBSE GUIDE: FROM NUAIRE GUIDE TO VENTILATION 2011 REF. 671552

DESIGN FOR A FACTORY FULL COVERAGE:

TAKE VOLUME OF THE BUILDING X RECOMMENDED AIR CHANGE RATE

EXAMPLE: FACTORY: 100M X 30M X 7M = 21,000M³

RECOMMENDED ACH: 8

VENTILATION REQUIREMENT = 168,000 M³/H

COVERAGE CONSIDERATION RE QUANTITY OF COOLERS TOTAL VENTILATION/APPLIANCE AIR VOLUME

E.G. 168,000M³/H / 18,000 M³/H = 9 UNITS

USE FIXED THROUGH THE ROOF EVAPORATIVE COOLER

DESIGN FOR A FACTORY FIXED COOLERS

DUCTED OR PLENUM HEADS TO DISTRIBUTE AIR INTO

SPACE AT LOW LEVEL

DESIGN FOR A FACTORY

FULL COVERAGE NOT ALWAYS REQUIRED SPOT COOLING ONLY

INSTALLATION COSTS CAN BE PROHIBITIVE

PHYSICAL INSTALLATION OF FIXED COOLERS CAN BE IMPRACTICAL BE AWARE OF PROCESSES WITHIN THE BUILDING

CONSIDER USING PORTABLE COOLERS

DESIGN FOR A FACTORY

PORTABLE COOLERS APPLIED BY RECOMMENDED

AREA COVERAGE – RE FROM MANUFACTURERS

EXAMPLE BY APPLIANCE:

45,000 M³/H: 600 M²

16,500 M³/H: 300 M²

5,000 M³/H: 100 M²

DESIGN FOR A FACTORY

PORTABLE COOLERS – KEY CONSIDERATIONS:

CHECK VENTILATION RATE:

KEEP ALL AVAILABLE WINDOWS /DOORS OPEN

∴ ASSUME NATURAL VENTILATION RATE OF 2 X ACH

EXAMPLE TO COOL FACTORY 100M X 30M X 7M

AREA OF 1500M ONLY

IN THIS AREA X 8 ACH – 84,000 M³/H

DESIGN FOR A FACTORY

PORTABLE COOLERS – KEY CONSIDERATIONS:

EXAMPLE TO COOL FACTORY 100M X 30M X 7M

AREA OF 1500M ONLY

IN THIS AREA X 8 ACH – 84,000 M³/H

TO KEEP COMFORT HUMIDITY < 60% RH IN SPACE

IDEAL TO HAVE FRESH AIR AT AROUND 40% MIN OF TOTAL

ACH

NATURAL VENTILATION IN THIS EXAMPLE IS 42,000M²/H

50%

DESIGN FOR A FACTORY

PORTABLE COOLERS – KEY CONSIDERATIONS:

EXAMPLE TO COOL FACTORY 100M X 30M X 7M

AREA OF 1500M ONLY

IN THIS AREA X 8 ACH = 84,000 M³/H

DIVIDE REQUIRE ACH BY APPLIANCE RATING E.G.

16,500M³/H = 5 UNITS

CHECK COVERAGE PER UNIT AT 300M² = 1500M²/H

DESIGN FOR A FACTORY

PORTABLE COOLERS – KEY CONSIDERATIONS:

POSITION COOLERS BY OPEN WINDOWS AND DOOR

BI-DIRECTIONAL BLOWING IF POSSIBLE

ALLOW 1 M BEHIND UNIT CLEARANCE

BEWARE OBSTRUCTIONS

Design Considerations

PART THREE

APPLICATIONS IN PRACTICE

AUTO WORK SHOPS

FACTORIES

AVIATION HANGARS

WAREHOUSES

CONSTRUCTION SITES

RESTAURANT AND TERRACES

HOTEL GARDENS

MARQUEES

OUTDOOR EVENTS

SPORTS TRAINING CENTRES

EQUINE BARNS

EVAPORATIVE CANNOT BE USED IN: AREAS THAT REQUIRE NO HUMIDITY

DATA CENTRES ETC.

CLEAN ROOM AREAS THAT PRECLUDE DUST MOVEMENT

AREAS THAT REQUIRE TEMPERATURE CONTROL TO 0.5℃ SET POINT

WEATHER INFLUENCES TEMP ACHEIVED

AREAS OR BUILDINGS THAT ARE SEALED; HAVE NO WINDOWS, DOORS OR VENTILATION SYSTEM

IS THERE A RISK OF LEGIONELLA? SOURCE: ASHRAE JOURNAL (USA) 1995

EVAPORATIVE COOLERS POSE LITTLE RISK WITH LEGIONELLA SPREAD :

LEGIONELLA BECOME ACTIVE IN STANDING WATER BETWEEN 37°C AND 41°C

WATER IN AN EVAPORATIVE COOLER RARELY EXCEEDS 24℃ AND IF BEING CONNECTED TO A MAINS FEED, WATER IN COOLERS WILL RARELY EXCEED 20℃.

IS THERE A RISK OF LEGIONELLA? SOURCE: ASHRAE JOURNAL (USA) 1995

UNITS SHOULD BE RUN DRY EVERYDAY AS AN EXTRA

PRECAUTION. REPLENISHING WATER REGULARLY

THEREFORE IS A GOOD THING

USING A BIOCIDE IS AN EXTRA PRECAUTION

RECOMMEND THE USE OF REFRESH™ TABLETS FROM

RECTORSEAL

IS THERE A RISK OF LEGIONELLA? SOURCE: ASHRAE JOURNAL (USA) 1995

LEGIONELLA REQUIRE AN AEROSOL OF BETWEEN 1

AND 5 MICRONS TO BE CARRIED AND PENETRATE

INTO THE LUNGS.

THE DROPLET PRODUCED BY MEDIA TYPE COOLERS ARE

FAR LARGER AND THEREFORE CANNOT PHYSICALLY

CARRY THE LEGIONELLA BACTERIA

IS THERE A RISK OF LEGIONELLA? SOURCE: ASHRAE JOURNAL (USA) 1995

THE THREAT IS NEGLIGIBLE BASED ON THE ABOVE.

ALTHOUGH GOOD PRACTICE IS ALWAYS THAT

STANDING WATER IS AVOIDED IN VERY HOT

CONDITIONS.

PART FOUR

QUESTIONS?

REFERENCES• CVB2/16 CIBSE GUIDE B2: VENTILATION AND DUCTWORK 2016.

• NUAIRE GUIDE TO VENTILATION. SEPTEMBER 2011 DOC REF. 671552.

• PAUL R. PUCKORIOUS, PATRICIA T. THOMAS & ROBERT L.

AUSPURGER;

• ”WHY EVAPORATIVE COOLERS HAVE NOT CASUED LEGIONNAIRES

DISEASE”. ASHRAE JOURNAL (USA) 1995.