Fundamentals on HVAC Systems Presentation

8/9/2019 Fundamentals on HVAC Systems Presentation

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Fundamentals of HVAC

systems andDistrict Cooling

Objectives: The attendees may be able to gain a better understanding of fundamental of humanthermal comfort, Thermal heat gains in buildings, Climate and design conditions, Heat

gains from solar and other sources, ventilation principles, fan coil units, Air handlers, BMS,Refrigeration Plants and applications, benets of !istrict cooling and !CS system details"

Spea#er$ %abian &ayasuriyaMSc" '(ng"), C (ng", MC*BS(, M*(T, MASHRA(

Technical !irector(mirates !istrict Cooling +"+"C


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The body core temperature associated -ith a healthy human bodyis ./0C '12"3 0%) and in order to remain comfortable the bodyattempts to maintain thermal e4uilibrium -ith the surroundings"

Thermal balance bet-een the body and it5s surroundings occursby means of$

i" (vaporation

ii" Radiation

iii" Convection

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Thermal Comfort


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The environmental factors that in7uence the modes of heattransfer and hence, thermal comfort are$

i" !ry bulb temperature

ii" Relative humidity

iii" Air movement rateiv" Mean radiant temperature

T-o other 8personal5 factors are also in7uential, namely$

v" Activity level

vi" Clothing

.

Factors aecting Thermal Comfort


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Degree ofActivity

Total ate ofHeat

!mission forAdult "ale

#$att%

AverageValue of "ale

& Female#$att%

'ensible#$att%

(atent #$att%

Seated 9 19 39 .:

;al#ing 3: .: /9 99

!ancing 639 6.: 1: 3:

Sedentary;or#

3: .: /9 99

<

Ty)ical "etabolic ates of Human*eings


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Air =elocity'm>s)

:" :"6 :"69 :". :".9

!ry bulb

Temp" 0C

69 63"2 63"1 6/" 6/"6

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Air Velocity and Comfort


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*t is essential that the buildings be ad?usted to serve people" *tshould not be the people -ho are re4uired to be adopt to thebuildings"

Summer design temperature of 660C @ 6


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+oad assessment is carried out as part of the design and selectionof comfort air conditioning systems and e4uipment" *t is directlyrelated to the assessment of sensible and latent heat gains andlosses that occur -ithin the condition space"

;hen sensible heat gains occur -ithin a space their eDect is toincrease room air temperature"

;hereas latent gains increase the moisture content of room air"

/

(oad Assessment


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i" Solar gain through glaEing

ii" Transmission gains arising because of temperature diDerencesbet-een the room and the outdoor air temperature"

iii" Transmission gains due to outside surface temperature rise -iththe impact of solar radiation"

iv" *nltration of -arm humid airv" Room occupants

vi" (lectric lighting

vii" (lectrical e4uipment such as computing e4uipment andphotocopied"

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'ensible and (atent Heat ,ains


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Conduction

Heat Transfer by molecular motion in a material in direct contact Convection

Contact Bet-een 7uid in motion and a solid

adiationFo contact re4uired" Heat transfer by electromagnetic -aves

-nits & "easurements

Thermal conductivity '# or G) ;>m>:I

Thermal Resistance 'R) d> # in m. :I>; ' d Thic#ness )

Heat Transfer coeJcient or Thermal Transmittance ' ) >R ;atts > m./ :I

Steady state Heat Transfer (4uation 'Kne dimensional Heat 7o- ) L A T ;atts

A Area in m. 0 T Temperature diDerence in :I

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Heat Transfer "echanismsFundamentals


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Fundamentals on Conduction


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Heat ,ain Through Conduction


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Ventilation Heat ,ain Calculation

Heat gain due to ventilation 'Lv ) 4 m 'h ao @ h ai) ;atts4 m mass 7o- rate ' #g>sec")h ao (nthalpy of outdoor airh ai (nthalpy of indoor air

Simplied e4uation -ithout considering moisture in airLv 4 m C) 't ao @ t ai ) ;atts=olume 7o- rate in +itres >Sec" ' 4 v )Lv "6 4 v 't ao @ t ai ) @@@@@@@@@@@@@

Simplied Heat 7o- e4uation -ith number of air changesLv F=>. ;atts @@@@@@@@@@@@@ 6;here F number of air changes , = Room =olume in m.

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Heat ,ain due to Ventilation


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The Sun radiates energy as a blac# body having a surfacetemperature of 3::: : C over a spectrum of -ave length .:: N >m.s I 1 A area in m. ,T temperature in 3I

.

'olar adiation


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The impact of solar radiation varies upon the building location andorientation

*uilding 5alls: Colour of the surface Surface roughness Building material Sunlit area

*uilding oof Slope of the roof Roof material Colour of the roof Surface re7ectance

*uilding $indo5s : Sunlit area lass type , thic#ness and colour Re7ectance factor Shading coeJcient ' a property of glass )

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4m)act of 'olar adiation on a *uilding


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!egree hours or !egree days concept provides a measure toassess cooling energy demand hours based on the temperaturediDerence bet-een inside and outside of a building as related toperiod of time under consideration"

Example:

i" At eternal outdoor temperature 620C and indoor temperaturesetting at 6


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The need for ventilation $

%resh air re4uired for breathing

':"6 litres>sec") directly proportional to metabolic rate

!ilution of the orders present to a socially acceptable level '/"9litres>sec" )

MinimiEe the rise in air temperature in the presence of ecessivesensible heat gains

!ealing -ith high humidity or condensation

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Ventilation in *uildings


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Fatural =entilation is the air 7o- through a building resulting fromthe provision of specied routes such as$

• Kperable -indo-s

• !oors

• Shafts• !ucts

• To-ers

6:


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Avoid noise and traJc fumes from busy roads Consider Security

Consider *nsects

!ra- cooler air from a shaded side of a building to maimise thecooling

Cross ventilation Buoyancy driven ventilation

Atrium ventilation

Chimney ventilation

;ind to-er ventilation

6


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$ind To5er TechniBue


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Air conditioning systems can be simply classied as follo-s$ nitary system

All air systems

Air -ater systems

nitary systems

Self contained room air conditioners

Split systems

;ater loop air conditioning heat pumps

All Air systems

Constant volume single ducted systems !ual duct system 'for heating Q cooling)

MultiEone system

=ariable air volume system"

6.

Air Conditioning 'ystems


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Air N ;ater systems$

%an coil systems

*nduction unit systems

Chilled beam and displacement ventilation systems"

6<

Air Conditioning 'ystems


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Ty)ical Air Conditioning !Bui)mentange


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Ty)ical Air Conditioning !Bui)mentange


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!istrict Cooling is a system in -hich chilled -ater is distributed inpipes from a central cooling plant to buildings for space coolingand process cooling"

*t contain three ma?or elements$ the cooling source, distributionsystem and customer installations"

Cooling sources$ =apor, compression chillers, absorption chillers" !istribution system$ Chilled -ater pumps and buried piping

net-or#

Customer installation$ Tie@in connection (nergy Transfer Station'(TS) ie" Heat (changer connected -ith secondary pumps fordistribution of chilled -ater to fan coil units Q AH5s"

Conventional chilled -ater supply temperature$ Bet-een


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Kther advantages are as follo-s$@ (nvironment@friendly

The plant design and e4uipment selection utiliEe an innovativetechnology -ith minimal impact on the environment"

+o-er carbon foot print

Promotes healthier living

The system helps to create a -or#ing environment that is safer

and healthier for people"

ses energy more eJciently

*t maimiEes eJciency and minimiEes -astage"

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ADVA


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@3 T!CH


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nderstanding the Pro?ect$@ Plot areas

@ +and use Q building classication

@ Population Q gro-th

@ !evelopment phasing

@ Building codes Q permits@ (nvironmental regulations

@ Cooling demand estimates N s4" mts per ton

@ tility plots Q areas

@ Piping net-or# corridors

@ Access to nearest Po-er, ;ater Q Se-age source@ eological site investigations Q site instructions

@ Kther utilities inter@phasing etc"

.

F!A'4*4(4T9 'T-D9


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.@3 F4


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Business Plan@ Business ro-th

@ Mar#et analysis

@ Sensitivity analysis

@ Critical issues Q strategic analysis

@ Strengths, -ea#ness, opportunities, threats 'S;KT)@ Ris# analysis, ris# management, and ris# mitigation

@ Ma?or challenges

..

F!A'4*4(4T9 'T-D9


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.<

!conomics: com)arison 5ithalternative

Capital costs'Cape)

*mpact on cost Redundancy

Thermal Storage

Capital Cost per ton

!istribution System Connection

Kverall

(nergy sage

;ater Consumption

Kverall

!iversity %actor

Kpe costs Maintenance


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!conomic characteristics of districtcooling

Ca)eE

O)eE

Ca)ital4ntensive

Attractiveto

'trongredictableCash Flo5s

Ty)ical eturns

Attractiveto

roject 4

!Buity 4

3 = 8

= .3 8

(enders

4nvestors

Debt

!Buity


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Time Assessment

Availability of Bul# (lectrical Po-er Supply to the developmentand the time constrains to build H"= Po-er substations > +ocalAuthority Po-er Supply"

*nfrastructure piping net-or# construction"

T!' #Treated euent se5age%

;ater supply to development

(ocal Authority

Building Permit

.3

%easibility Study


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is6 Assessment

+o-er than pro?ected load

+o-er energy sales > revenue generation

Reduced building occupancies

Timely permits from tility companies for Po-er and ;ater ;eather variations

./

%easibility Study


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A@ "echanical

" Centrifugal Chillers

6" Condenser -ater Pumps

." Chilled ;ater Primary Pumps

%ire Pumps

" Blo- !o-n Storage Tan#

6" Thermal Storage Tan#s

.2

!istrict Cooling Plant (4uipment


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*@ !lectrical

" #= S-itchgear '.". #= if applicable)

6" #= Capacitor ban#s

." #= >


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C@ Control 'ystems

" Building Management System 'BMS) or CMS 'Plant ControlManagement System)"

6" P+C System for data control

." System !ata server


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Ty)es of *T- "eters:A" (lectromechanical meters

B" Magnetic meters

C" ltrasonic meters

Communication modes for data collection:" !ata bus cables

6" %iber Kptic Cable

." Radio Receiver > SM


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Ty)ical District Cooling lant*uilding


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Cooling To5erCooling To5er Fan &

"otor


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Ty)ical Thermal 'torageTan6 Thermal 'torage Tan6


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Air Cooled Chiller

$ater Cooled Chiller"odule


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Fan Coil -nit AH- -nit


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"otor Control Center 6V '5itchgear

9:


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C@CO


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THA

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Fundamentals on HVAC Systems Presentation