H.V.A.C building service in b.arch ciriculam

1
H.V.A.CHeating, Ventilating, and Air-Conditioning
K.KEDHEESWARAN M.Arch

TABLE OF CONTENTS
1. Basics of Thermodynamics
2. Types of Systems
3. Central Forced Air System
1. Air Handling Unit
4. Hot Water System
5. Zoned Control System
6. Radiant Heat
7. Heat Pump
8. HVAC Plans
9. Refrigerant
10. AC Systems
11. VCC,VAC…
12. Components of A/C
13. Cooling towers
14. Unit and measurement
15. Types and classification of A/C
16. Ducting,VAV etc.
17. AHU
18. Diffusers
19. Air curtain
K.KEDHEESWARAN M.Arch 2

THERMODYNAMICS
Thermodynamics is the study of energy interactions between systems and
the effect of these interactions on the system properties.
Energy transfer between systems takes place in the form of heat and/or
work. Thermodynamics deals with systems in equilibrium.
HEAT
Heat is energy transferred between a system and its surroundings by virtue
of a temperature difference only.
The different modes of heat transfer are: conduction, convection and
radiation.
Two forms of heat are relevant in air conditioning:
 Sensible heat
 Latent heat
Sensible heat
When an object is heated, its temperature rises as heat is added. The
increase in heat is called sensible heat. Similarly, when heat is removed from an object
and its temperature falls, the heat removed is also called sensible heat. Heat that
causes a change in temperature in an object is called sensible heat.
K.KEDHEESWARAN B.ArchK.KEDHEESWARAN M.Arch 3

Latent heat
All pure substances in nature are able to change their state. Solids can become
liquids (ice to water) and liquids can become gases (water to vapor) but changes such as
these require the addition or removal of heat. The heat that causes these changes is called
latent heat.
Latent heat however, does not affect the temperature of a substance - for
example, water remains at 100°C while boiling. The heat added to keep the water boiling
is latent heat. Heat that causes a change of state with no change in temperature is called
latent heat.
Appreciating this difference is fundamental to understanding why refrigerant is
used in cooling systems. It also explains why the terms 'total capacity' (sensible & latent
heat) and 'sensible capacity' are used to define a unit's cooling capacity. During the cooling
cycling, condensation forms within the unit due to the removal of latent heat from the air.
Sensible capacity is the capacity required to lower the temperature and latent capacity is
the capacity to remove the moisture from the air.
Specific heat (cp): Amount of heat required to raise the temperature of 1 gms of substance
1°C (BTU/lb)

The energy required in calories to completely convert one gram of water to steam
without increasing the temperature is called the latent heat of vaporization. It is called
latent heat because it does not increase the temperature.
Latent heat of fusion of ice is heat energy required in calories by one gram of ice
to completely convert itself into water without increase in temperature
What is a subcooled liquid?
LIQUID COOLER THAN THE CONDENSING SATURATION TEMPERATURE (125 degree
Fahrenheit) IS CALLED SUBCOOLED LIQUID
Refrigeration –
Cooling of an object and maintenance of its temp below that of surroundings
Thermal energy moves from left to right through five loops of heat transfer:
1)
Indoor air loop
2)
Chilled water
loop
3)
Refrigerant loop
4)
Condenser water
loop
5)
Cooling water
loop

What is air-conditioning?
Air-conditioning is defined as a process
which cools (or heats), cleans, circulates,
freshens air and controls its moisture content
simultaneously.

Terms, unit ,measurement for A/C system
Most of heard the word „TON‟ connection with heat load and AC capacity
The heat load quantity is expressed in two states British thermal unit (BTU)
and calories (Cal)
BTU- The quantity of heat need to raise the temperature of 1lb of water
by one degree Fahrenheit
Cal- The heat required to raised temperature of one
gram of water by one degree Celsius
1 Kw= .284345136 tons(central plants) (.3)
1 Ton Refrigeration = 12000 Btu/hr or 3000 K Cal/hr
*One Ton Refrigeration was
originally conceived to describe the
quantity of heat removed to freeze
1 Ton (1 American Short Ton is 2000
pounds) of water at 32°Fahrenheit
to ice at the same temperature in
24 hours.
**The air-conditioning engineer
uses the term ‘Ton Refrigeration’
(TR), popularly referred to as ‘Ton’,
when associated with refrigeration
and air-conditioning. We will use
the term ‘Ton’ or its abbreviation
‘TR’ in this book.

Heating, Ventilating, and Air-
Conditioning

Types of Systems
• Central Forced-Air Systems
• Hot Water Systems
• Zone Control Systems
• Radiant Heat

Central Forced Air System
• Most Common HVAC System
• Circulates air through or around heating and
cooling devices.
• A fan forces air into ducts
• Supply ducts transport conditioned air into
building through diffusers or supply registers
• Air is routed back to heating/cooling device
through return ducts

Air Handling Unit (AHU)
• Device used to condition and circulate air as
part of an HVAC system
• Large metal box containing a blower, heating
or cooling elements, filter, and sound
attenuators
• Connects to ductwork that distributes the
conditioned air through the building and
returns it to the AHU
Courtesy Eric Fisher

MAIN COMPONENTS
Casing-double-wall sheet-metal casing in which the insulation material
Fans-A double-inlet air foil, backward-inclined centrifugal fan is often
coils-coil are often used: water cooling coils, water heating coils, electric
heating coils, and water precooling coils.
Filters-Air filtration is an important component to achieve an acceptable indoor air
quality. In AHUs, earlier low-efficiency filters of the panel type are giving way to the
medium- and high-efficiency bag type and cartridge type of filters.
Humidifiers-To regulate and maintain the humidity
A typical AHU with unhoused plug/plenum return fan.

• May need to supply heating, cooling, or both
• A furnace generates heat
–Fuel oil or natural gas
–Electric heating elements
–Heat pump
• A refrigeration system absorbs heat
–Air conditioner
–Heat pump

• Smaller air handlers may contain a fuel-burning
heater or a refrigeration evaporator placed directly in
the air stream
• Large commercial air handling units contain coils that
circulate water
– Boiler provides hot water or steam
– Chiller provides chilled water
©iStockphoto.com©iStockphoto.com

Wikimedia
1. Supply duct
2. Fan compartment
3. Flexible connection
4. Heating and/or cooling coil
5. Filter compartment
6. Return and fresh air duct
Typical AHU components:
A typical AHU with unhoused plug/plenum return fan.

Type of air-handling units
(AHUs):
(a) horizontal, draw-through unit;
(b) vertical draw-throughunit;
(c) blow-through unit, multizone
AHU;
(d ) makeup air AHU, custom-built,
rooftop unit.

Hot Water System
• Water heated in boiler and circulated through
pipes to radiators
• Requires plumbing rather than ductwork
©iStockphoto.com

Zone Control System
• One heater and one thermostat per room
• No ductwork
• Often used in hotel rooms

Radiant Heat
• Supply heat directly to the floor, wall, or ceiling
• Hot water pipes or electric heating element runs
through building component
• Dependent on radiant heat
– Heat transferred from hot surface to people and
objects
Wikimedia

Heat Pump (HP)
• A machine or device that moves heat from one
location (the source) to another location (the
mechanical work)
• Can produce heating or cooling by reversing the
direction of heat flow
• Can be used in:
– Forced Air System
– Hot Water System
– Radiant Heat System
wikimedia

HVAC Plans
Image Courtesy Novus ArchitectsK.KEDHEESWARAN M.Arch 21

HVAC (Mechanical) Plans
Image Courtesy Novus ArchitectsK.KEDHEESWARAN M.Arch 22

HVAC Mechanical Plans
Image Courtesy Novus Architects

Designation of refrigerants:
Figure 26.1 shows the classification of fluids used as refrigerants in vapour compression
refrigeration systems. Since a large number of refrigerants have been developed over the
years for a wide variety of applications, a numbering system has been adopted to
designate various refrigerants. From the number one can get some useful information
about the type of refrigerant, its chemical composition, molecular weight etc. All the
refrigerants are designated by R followed by a unique number.
i) Fully saturated, halogenated compounds: These refrigerants are derivatives of
alkanes (CnH2n+2) such as methane (CH4), ethane (C2H6). These
refrigerants are designated by R XYZ, where:
X+1 indicates the number of Carbon (C) atoms
Y-1 indicates number of Hydrogen (H) atoms, and
Z indicates number of Fluorine (F) atoms
Ex: R 22
X = 0 ⇒ No. of Carbon atoms = 0+1 = 1 ⇒ derivative of methane (CH4)
Y = 2 ⇒ No. of Hydrogen atoms = 2-1 = 1
Z = 2 ⇒ No. of Fluorine atoms = 2
The balance = 4 – no. of (H+F) atoms = 4-1-2 = 1 ⇒ No. of Chlorine atoms = 1
∴The chemical formula of R 22 = CHClF2

ii) Inorganic refrigerants: These are designated by number 7 followed by the molecular
weight of the refrigerant (rounded-off).
Ex.: Ammonia: Molecular weight is 17, ∴ the designation is R 717
Carbon dioxide: Molecular weight is 44, ∴ the designation is R 744
Water: Molecular weight is 18, ∴ the designation is R 718
iii) Mixtures: Azeotropic mixtures are designated by 500 series, where as zeotropic
refrigerants (e.g. non-azeotropic mixtures) are designated by 400 series.
Azeotropic mixtures:
R 500: Mixture of R 12 (73.8 %) and R 152a (26.2%)
Zeotropic mixtures:
R404A : Mixture of R 125 (44%), R 143a (52%) and R 134a (4%)
R407A : Mixture of R 32 (20%), R 125 (40%) and R 134a (40%)
iv) Hydrocarbons:
Propane (C3H8) : R 290
n-butane (C4H10) : R 600
iso-butane (C4H10) : R 600a

Refrigerant Application ISSUES
R 11(CFC) Large air conditioning systems
Industrial heat pumps .As foam
blowing agent
-
R 12 (CFC) Domestic refrigerators,
Small air conditioners,
Water coolers ,Small cold
storages
-
R 22 (HCFC) Air conditioning systems
Cold storages
-
R 134 a (HFC) Used as replacement for R 12 in
domestic refrigerators, water
coolers, automobile A/Cs etc.
●Immiscible in mineral oils
●Highly hygroscopic
R 717 (NH3) Cold storages, Ice plants
Food processing Frozen food
cabinets
●Toxic and flammable
●Incompatible with copper
● Highly efficient
● Inexpensive and available
R 744 (CO2) Cold storages, Air conditioning
systems, Simultaneous cooling
and heating (Trans critical cycle)
●Very low critical temperature
●Eco-friendly
● Inexpensive and available

AC options / combinations:
AC Systems
• Air Conditioning (for comfort / machine)
• Split air conditioners
• Fan coil units in a larger system
• Air handling units in a larger system
• Small capacity modular units of direct expansion type (50 Tons
of Refrigeration)
• Centralized chilled water plants with chilled water as a
secondary coolant (50 – 250 TR)
• Brine plants with brines as lower temperature, secondary
coolant (>250 TR)
Refrigeration systems for industrial processes

• Bank of units off-site with common
• Chilled water pumps
• Condenser water pumps
• Cooling towers
• More levels of refrigeration/AC, e.g.
• Comfort air conditioning (20-25 oC)
• Chilled water system (8 – 10 oC)
• Brine system (< 0 oC)
Refrigeration at large companies
Types of Refrigeration
• Vapour Compression Refrigeration (VCR): uses
mechanical energy
• Vapour Absorption Refrigeration (VAR): uses
thermal energy
• Thermo Electric Refrigeration system. (TER)
Refrigeration systems

Vapour Compression Refrigeration
• Highly compressed fluids tend to get colder when allowed to expand
• If pressure high enough
• Compressed air hotter than source of cooling
• Expanded gas cooler than desired cold temperature
Two advantages
• Lot of heat can be removed (lot of thermal energy to change liquid to
vapour)
• Heat transfer rate remains high (temperature of working fluid much lower
than what is being cooled)
This is the most important system from the point of commercial &
domestic utility & most practical form of refrigeration.
The working fluid refrigerant used in this refrigeration system readily
evaporates & condenses or changes alternatively between the vapour &
liquid phases without leaving the refrigerating plant

During evaporation it absorbs heat from the cold body or in condensing or
cooling it rejects heat to the external hot body .
The heat absorbed from cold body during evaporation is used as its latent heat
for converting it from liquid to vapour. Thus a cooling effect is created in working fluid.
This system of refrigeration thus act as latent heat pump since its pump its
latent heat from the cold body or brine & rejects it or deliver it to the external hot body or
the cooling medium.
According to the law of thermodynamics , this can be done only on the
expenditure of energy which is supplied to the system in the form of electrical energy
driving the compressor.
Each cycle of operation consists of the four fundamental changes of state
or processes:-
 Expansion
Vaporisation
Compression
Condensation

31
Refrigeration cycle
Condenser
Evaporator
High Pressure
Side
Low
Pressure
Side
Compressor
Expansion
Device
1
2
3
4

32
Type of Refrigeration
Refrigeration cycle
Low pressure liquid refrigerant in
evaporator absorbs heat and
changes to a gas
Condenser
Evaporator
High
Pressure
Side
Low
Pressure
Side
Compressor
Expansion
Device
1 2
3
4

33
Refrigeration cycle
The superheated vapour enters the
compressor where its pressure is
raised
Condenser
Evaporator
High
Pressure
Side
Low
Pressure
Side
Compressor
Expansion
Device
1 2
3
4

Type of refrigerant
• Refrigerant determined by the required cooling temperature
• Chlorinated fluorocarbons (CFCs) or freons: R-11, R-12, R-21, R-22 and R-
502
Components of Vapour Compression Systems
Compressor
Condenser
Receiver
Expansion Valve
Evaporator

Compressor
The low pressure & temp. refrigerant from evaporator is drawn into the
compressor through the inlet or suction valve , where it is compressed to a high
pressure & temp.
The high pressure & temp vapour refrigerant is discharged into the
condenser through the delivery or discharge valve.
Condenser
The condenser or the cooler consists of coils of pipe in which the high pressure
& temp. vapour refrigerant is cooled & condensed.
The refrigerant while passing through the condenser, rejects its latent heat to
surrounding condensing medium which is normally air or water.
Thus hot refrigerant vapour received from compressor is converted into liquid form in
condenser.
Receiver
The condensed liquid refrigerant from the condenser is stored in a vessel,
known as receiver, from where it is supplied to the expansion valve or refrigerant
control valve.
Expansion Valve
The function of this valve is to allow the liquid refrigerant under high pressure &
temp. to pass at a controlled rate after reducing its pressure & temp.
some of liquid refrigerant evaporates as it passes through the expansion valve,
but the greater portion is vaporised in the evaporator at the low pressure & temp.

Evaporator
An evaporator consists of coils of pipes in which the liquid vapour refrigerant
at low pressure & temp. is evaporated & changed into vapour refrigerant at low
pressure & temp.
During evaporation process, the liquid vapour refrigerant absorbs its latent
heat of vaporization from the medium which is to be cooled.
COOLING TOWERS
A cooling tower is a device in which recirculating condenser water from a condenser
or cooling coils is evaporatively cooled by contact with atmospheric air.
The location of the fan corresponding to the fill and to the flow arrangements of air
and water, currently widely used mechanical draft cooling towers for HVAC&R can be classified
into the following categories:
 Counterflow induced-draft
 Crossflow induced-draft
 Counterflow forced-draft

COMPRESSORS
Types
• Sealed scroll compressor
• Sealed rotary compressor
• Sealed reciprocating

Sealed Reciprocating Compressors: These compressors typically
have one or two pistons mounted on the crank shaft extension of
the motor. As the motor turns the crank shaft, the piston moves up
and down in the cylinder. On the top of the cylinder is mounted a
valve plate assembly with a suction and discharge valve. Each time
the piston moves down, the suction valve opens and the gas is
sucked into the cylinder. Then the piston moves up, the gas is
pushed against the discharge valve which opens to let the
compressed gas out. These compressors are available from very
small fractional ton capacities up to 10 ton units.
Sealed Scroll Compressors: Scroll compressors are a recent innovation. They are
inherently more efficient and are capable of producing power savings. Consequently
they have become very popular in recent years. Scroll compressors use two
interlocked spiral-shaped members which enclose the refrigerant gas in pockets
between them. One of the spiral-shaped members is fixed and the other rotates
causing the refrigerant to he squeezed into ever decreasing pockets until it reaches
the center from where it is discharged. These compressor are currently available in
small capacities of up to 14 tons. The advantages include high reliability, kw
maintenance, low noise and vibration, arid high efficiency.

CAPACITY - 2 TON
Sealed Rotary Compressors:
The Rotary compressor has a turning rotor
eccentric to the cylinder housing, and blades which slide
to form a continuous seal for the refrigerant gas. At the
beginning of the stroke a volume of refrigerant gas
enters the chamber. As the stroke progresses the nature
of eccentricity squeezes the gas thereby compressing it.

The military to test the performance of high-efficiency particulate air (HEPA) filter.
The removal or collection of dust particles in air filtration is performed by various combinations
of the following mechanisms.
Inertial impaction. A sudden change in direction causes a collision between the dust particles,
and fibrous media.
Straining. If the filter spaces are smaller than the size of the dust particles, the particles are
trapped.
Diffusion. For very fine dust particles, Brownian movement causes the particles to settle.
Interception. Dust particles may follow the airstream, contact the fibrous media, and remain
there.
Electrostatic effects. Particles and the filter medium are charged to collect the dust in the
airstream.
FILTER
Coarse Air Filters- Coarse air filters are often used
to remove coarse dusts (5 to 80 Чm) such as
standing dust on surfaces, pollen, and textile fibres.
(a) panel filter; (b) pleated filter; (c) extended
surface (bag type); (d ) rotary filter; (e) automatic
renewable rolling filter.

(a) panel filter; (b)
pleated filter; (c) extended
surface (bag type); (d ) rotary
filter; (e) automatic renewable
rolling filter.
Low-Efficiency Air Filters
Remove dusts
between 3 and 10 Чm, such
as spores, molds, hairspray,
cement, and other solid
particles.
Medium-Efficiency Air Filters To remove dusts of size 1 to 3 Чm such as
welding fumes, Legionella bacteria and coal dusts. They
are often bag and box filters with pleated mat to extend
surface area, and are made of synthetic fibres

HIGH-EFFICIENCY AIR FILTERS
 Used to remove particles of 0.3 to 1 Чm such as bacteria, viruses, cooking oil
fumes, tobacco smoke, and other smoke
 The filter media are often made of glass fibres of submicrometer and
micrometre diameter
Ultrahigh-efficiency filters include high-efficiency particulate air (HEPA) filters,
ultralow penetration air (ULPA) filters, and gaseous adsorbers and chemisorbers
ULTRAHIGH-EFFICIENCY AIR FILTERS
ELEC TRONI C AI R CLEANERS
(ULPA)
An electronic air cleaner uses the
attraction between particles of opposite
charges

CLASSIFICATION OF ACS
A/C
Central Non-central
Ductable A/C
Central A/C Window A/C Split A/C
Air cooled
Ducted split
Floor mounted
pack. Unit
1.Air cooled
2.Water cooled
Duct able A/C
2.Variable
refrigerant flow
1.DX system
3.Chilled water system
Central A/C

1.DX system 3.Chilled water system
Vapour
compression
unit
Vapour
absorption unit
Water/air cooled reciprocating unit
Centrifugal water cooled unit
Screw type air/water cooled
Direct fired
Hot fired
Stem fired
Split A/C
Floor ,wall, ceiling
Ceiling-concealed,exposed,semi-concealed
Floor mounted
Split A/C

Air and Water cooled A/Cs
Heat from space area is transfer to cold refrigerant
Air cooled A/Cs

W
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Central plant
Chilled Water System: Where refrigerant and water inter
action takes place the system is called a Chilled Water
System. The refrigerant in the shell (or tube, depending on
the design) of a shell & tube heat exchanger, evaporates by
picking up the heat from the water which is in the other
portion of the heat exchanger. This chilled water is then
circulated to various water-air heat exchangers called Fan Coil
Units/Air Handling Units. The system is also preferred where
multiple zones are to be cooled like a hotel or hospital.

Direct Expansion (DX) system:
In this system, air is cooled and conditioned in the plant
room. This treated air is then pumped to various parts of the
building. The air returning from the air-conditioned area is sucked
through a coil-fin arrangement by a fan. Refrigerant inside the coil
picks up heat from this air and evaporates. The cold air is then
pumped back to the air-conditioned space. In DX plants the place
where this heat exchange takes place is called an Air Handling Unit
(AHU). This type of system typically uses ducting passing
through the structure to various parts of the building to be
conditioned.

PACKAGED UNITS
A packaged unit (PU) is a unitary, self-contained air conditioner. It is also
the primary equipment of a unitary packaged system.
A packaged unit can be either enclosed in a single package or split into two
units: an indoor air handler and an outdoor condensing unit.
Many packaged units now use scroll compressors instead of reciprocating
compressors.
 Rooftop Packaged Units
 Indoor Packaged Units
 Split Packaged Units
A typical indoor packaged unit.
A typical split packaged unit.

Ductable Package A/Cs
Floor mounted package units
These are shaped like cupboards and are typically placed in a
small enclosure adjacent to the conditioned area. Inside this „cupboard‟ like
enclosure is housed the Compressor, Evaporator and the Evaporator blower.
Currently in India these units come in capacities from 5 to 16.5 Ton
Machines. Higher capacities (20 Tons and above) can be expected ……
Air-cooled Ductable Splits
The indoor portion of these units are located above the false ceiling and connected to
the ducting.
Consequently they do not occupy floor space.
Currently in India they are available in 3, 5, 7.5 & 8.3 Ton capacities. Since the indoor
unit is located above the false ceiling the space available limits the
capacity to 8.3 Tons per unit.

PACKAGE CHILLERS
It is typically mounted on frames, compressor shell tube heat exchangers
Depending on compressors
Screw, reciprocating, centrifugal compressors

C H I L L E D B E A M S Y S T E M

1. A chilled beam is a type of convection HVAC system designed to heat or
cool large buildings such as commercial buildings, schools, universities,
dry labs, and hospitals.
2. A chilled beam primarily gives off its
cooling effect through convection by using
water to remove heat from a room.
3. Pipes of water are passed through a
"beam" (a heat exchanger) suspended a
short distance from the ceiling of a room.
4. As the beam chills the air around it, the air
becomes denser and falls to the floor.
5. It is replaced by warmer air moving up
from below, causing a constant flow of
convection and cooling the room.
COMPONENTS OF CHILLED BEAM SYSTEM
1. Passive chilled beam system:
• Coil
• Fin-tube-heat exchanger
2. Active chilled beam system:
• Coil
• Fin-tube-heat exchanger
• Nozzle
• Air plenum

2
TYPES OF CHILLED BEAM SYSTEM
1. There are two types of chilled beam system:
i. Passive chilled beam system
ii. Active chilled beam system
1
2. Common to each of the system, is a cooling coil which provides radiant
cooling via circulated cool water.
3. Chilled beams can be either recessed in the ceiling or exposed below
the ceiling.
4. Multi-Service Chilled Beams are also available.
Multi service chilled beam system

PASSIVE CHILLED BEAM SYSTEM ACTIVE CHILLED BEAM SYSTEM
Heat transfer of passive beams occurs mainly by
natural convection with a minor part by radiation.
Active beams contain a supply air plenum making
heat transfer more effective due to forced
convection
Warm room air in contact with the cooled surface
of the heat exchanger flows downwards through
the beam into the room.
Primary air is supplied directly into the plenum
where it exits via nozzles along its length
Passive chilled beams are not connected to the
ventilation system and can be positioned fully
exposed, recessed within a suspended ceiling or
above a perforated ceiling.
Air leaving the nozzles induces room air through
the heat exchanger
Supply air can be introduced either from high or
low level.
The mixture of supply air and induced air is
introduced into the room through the longitudinal
slots along both sides of the beam.
Primary air supply arrangements need to be
designed carefully in order not to interfere with
the operation of passive chilled beam.
With greater heat transfer between the secondary
room air and the heat exchanger active beams are
better suited to spaces with higher loads than
static beams
When the primary air is supplied using ceiling
diffusers, the air jet should not obstruct the
convective flow of chilled beam.
Depending on requirements, available space and
beam positioning, it is possible to supply air in one
or two directions.
In some cases where this could be exploited is to
prevent downdraught from a beam, the capacity
reduction of chilled beam should be taken into
account
The active chilled beam operation is based on
induction.
The induction rate varies between 1:3 and 1:5
depending on the model

ACTIVE CHILLED BEAMS
PASSIVE CHILLED BEAMS
CHILLED BEAM SYSTEM VS CONVENTIONAL SYSTEM
VS

ADVANTAGES
Less supply air
• Smaller ductwork
• Smaller AHU
• Less complicated AHU
controls
• Less complicated
terminal unit controls
• No cooling coil
condensate
1. Simple to design and control.
• Constant volume supply
air system
Smaller ductwork.
Reduces ceiling space
Less mechanical space.
Reduced mechanical room size
Reduced mechanical shaft size
Lower construction cost.
Reduced floor to floor height lowers exterior wall cost
Size of chilled beams installed in ceilings lowers ceiling system cost
Reduced mechanical and shaft floor area lowers floor, roof and wall
cost

6. Less maintenance; almost no maintenance required.
• No moving parts
• No filters to maintain
• Most manufacturers units are easily serviced through the removable
room air inlet grille
• Requires minimal cleaning. Typically remains dust and dirt free.
7. Increased comfort.
• Individual room temperature control is achieved at minimal
additional cost
• System noise is lower due to lower velocity and pressure drop of
the constant volume system and no VAV boxes
• Better control of space humidity levels
• More uniform space temperature is achieved
• Occupants are less likely to feel cold drafts
9. Higher efficiency.
• Up to 30% reduction in energy use
• Reduced fan energy
• Ideal application for energy recovery
• Higher design chilled water temperature
10. LEED points.
• An additional 8 – 10 LEED points can be
achieved.

1. Not well known in our industry.
2. Higher construction cost compared to VAV.
• Chilled beams may cost up to 15% more than
conventional VAV systems and are manufactured
primarily overseas; they can be hard to obtain,
contributing to high costs.
3. Many engineers aren't very familiar with this technology.
4. Dew point concerns, building must have good control of humidity
to prevent condensation on chilled beam surface.
5. Affects traditional ceiling appearance.
Chilled beams are larger than
traditional ceiling diffusers.
Can present challenges for lighting coordination.
6. Positioning chilled beams isn't easy.
DISADVANTAGES

District cooling system(DCS)
District Cooling Systems (DCS) is a system which distribute chilled water
or other media, usually provided from a dedicated cooling plant, to multiple buildings
for air conditioning or other uses.
OR
District Cooling System (DCS) can be defined as centralized production
and distribution of chilled water from a cooling plant to residential, commercial and
industrial facilities trough a network of underground pipes.
DCS means the centralized
production and distribution of cooling
energy. Chilled water is delivered via
an underground insulated pipeline to
office, industrial and residential
buildings to cool the indoor air of the
buildings within a district.

HOW DISTRICT COOLING WORKS?
1. Chilled water is produced in a central plant and distributed via a system of
pipes that can run underground, on the surface or over rooftops.
2. Inside the buildings, these transmission pipes are normally connected to a
conventional air handling unit or fan coil that allows the water to chill the air
passing through.
3. This means multiple chiller units placed locally are no longer required.
4. Once the required thermal energy has been extracted from the cold water,
this water is returned to the central plant to be re-chilled and re-circulated
through the closed-loop piping system.
5. This cooling system is more flexible and also operates with higher efficiency
under all load conditions than traditional chillers.
ADVANTAGES OF DISTRICT COOLING SYSTEM
1. Improve efficiency of energy
2. Protect environment
3. Save space
4. Improve urban view
5. Re-use the heat from exhaust system
6. Prevent disaster
7. Reduce manpower for operation
and maintenance

1
2 3
4
District cooling system(DCS)
1. Cold water from the bottom of the sea is used to cool down the DCS (district cooling
system) water that circulates in a closed loop.
The sea water is then returned to the sea.
2. The heat in the warmer water in the DCS return pipe can be recovered to the DH
system via heat pumps.
By this simultaneous heating and cooling all energy in the cooling system will be
recovered.
3. During the nights when there is excess capacity from free or waste cooling production
the storage is used.
4. The low temperature in the DCS system is transferred to the internal system in the
connected buildings.
The internal systems are then distributing the cooling capacity within the buildings.

DISTRICT COOLING SYSTEM VS CONVENTIONAL REFRIGERANT SYSTEM
TYPE OF REFRIGERANTS FOR DCP
• Brine, and propylene-glycol are the famous
examples used in DCP.
• Known as “secondary cooling media”, it is not
really a refrigerant.
• This type of heat transfer media is used for
delivering cool temperature from air conditioner
evaporator, to cooling coils.
• These are used in very large air conditioning
system, or “district cooling”.
• The reasons are, to keep the maintenance cost,
safety risk, and compressor breakdown, low.

TYPE OF REFRIGERANTS FOR DCP
• Brine, and propylene-glycol are the famous examples used in DCP.
• Known as “secondary cooling media”, it is not really a refrigerant.
• This type of heat transfer media is used for delivering cool temperature from air
conditioner evaporator, to cooling coils.
• These are used in very large air conditioning system, or “district cooling”.
• The reasons are, to keep the maintenance cost, safety risk, and compressor
breakdown, low.
DCS IN MALAYSIA
Since 1997, chilled water and electricity have
been supplied to airport facilities from the Chiller
Plant.
Shinryo Corp. contracted with 35,000 RT
designed chilled water capacity.
Current installed capacity consists of 12 nos.
2500 RT double effect steam absorption chillers.
 
 
1. Kuala Lumpur International Airport

Air distribution system
Air distribution design essentially consists of:
DUCTING that routes cooled air across the building to
the spaces requiring airconditioning,
GRILLES AND DIFFUSERS that disperse the cooled air in
planned manner into the airconditioned room,
RETURN AIR DUCTS that recycle the cooled air, and
FRESH AIR INTAKE DAMPERS that add fresh air as required.

DCS COMPONENTS
• A typical DCS comprises the following components:
1. Central Chiller Plant
– generate chilled water for cooling purposes
2. Distribution Network
–distribute chilled water to buildings
3. User Station
–interface with buildings' own air-conditioning
circuits.

1. Central Chiller Plant
– Chilled water is typically generated at the central
chiller plant by compressor driven chillers, absorption
chillers or other sources like ambient cooling or “free
cooling” from deep lakes, rivers, aquifers or oceans.
– Groups of large and energy-efficient water-cooled
chillers are usually installed in a central chiller plant
to take advantage of the economy of scale and the
cooling demand diversity between different buildings
within a district.
– Sea water condensers or fresh water cooling towers
can be utilized to reject waste heat from the central
chillers. K.KEDHEESWARAN M.Arch 71

2. Distribution Network
– District chilled water is distributed from the cooling
source(s) to the user stations through supply pipes
and is returned after extracting heat from the
building‟s secondary chilled water systems.
– Pumps distribute the chilled water by creating a
pressure differential between the supply and return
lines.

3. User Station
– The interface between the district cooling system and the
building cooling system is commonly referred to as user station.
– The user station usually comprise of air handling units, heat
exchanger and chilled water piping in the building.
– A user station is required in each user's building to connect the
DCS distributed chilled water pipe to the building.
– Inside the user station, devices called heat exchangers are
installed to transfer heat between the chilled water supply of
DCS and the air-conditioning system of the user building.
– The user station could be designed for direct or indirect
connection to the district cooling distribution system.
– With direct connection, the district cooling water is distributed
within the building directly to terminal equipment such as air
handling and fan coil units, induction units, etc.
– An indirect connection utilizes one or multiple heat exchangers
in between the district system and the building system.

A.Mechanical
1. Centrifugal Chillers
2. Condenser water Pumps
3. Chilled Water Primary Pumps
4. Chilled Water Secondary Pumps
5. Cooling Towers
6. Make up water pumps for Cooling Towers
7. Chemical Dosing system for Cooling Towers
8. Chemical Dosing system for chilled water network
9. R.O Plant for blow down water re-claim
10. Water Storage Tank for Cooling Towers / Fire Pumps
11. Blow Down Storage Tank
12. Thermal Storage Tanks
DISTRICT COOLING PLANT EQUIPMENT

B. Electrical
1. 11 kV Switchgear (3.3 kV if applicable)
2. 11kV Capacitor banks
3. 11 kV / 400 Ton Transformers (11 kV / 3.3 kV
Transformers if applicable)
4. H.V Cables and containment systems
5. UPS / Battery Charger for 11 kV vacuum circuit
breakers
6. L.V Switchgear
7. Motor control centres
8. L.V capacitor banks

C. Control Systems
1. Building Management System (BMS) or CMS (Plant
Control Management System).
2. PLC System for data control
3. System Data server
4. Operator work stations
5. Energy work station

Cooling Tower Cooling Tower Fan & Motor

Typical Thermal Storage Tank Thermal Storage Tank

Air Cooled Chiller Water Cooled Chiller Module

Fan Coil Unit AHU Unit

Motor Control Center 11kV Switchgear

CONTROL SYSTEMS
Control System SCADA System Projector Screen

HEAT EXCHANGER (HE)
• HE are used to transfer heat from one medium to
another, such as from steam to hot water, or from
water at a higher temperature to water at a lower
temperature.
• Two basic types of HE :
– Shell and tube type
– Plate type

1. SHELL-AND-TUBE TYPE (STT)
– The STT of HE consists of a bundle of tubes in the
shell.
– Primary medium is either steam or water, which
flows in the shell.
– Secondary medium is always water, which flows
through the tubes.
– The tubes are partitioned to allow single or multiple
passes to increase the temperature and the heat
transfer.
HEAT EXCHANGER (HE)

2. PLATE TYPE (PT)
– PT HE composed of multiple, thin, slightly separated plates that have
very large surface areas and fluid flow passages for heat transfer.
– This stacked-plate arrangement can be more effective, in a given
space, than the STT.
– Advances in gasket and brazing technology have made the plate-type
heat exchanger increasingly practical.
– Large HE of this type are called plate-and-frame; when used in open
loops, these heat exchangers are normally of the gasket type to allow
periodic disassembly, cleaning, and inspection.
– There are many types of permanently bonded plate heat exchangers,
such as dip-brazed and vacuum-brazed plate varieties, and they are
often specified for closed-loop applications such as refrigeration.
– PT HE also differ in the types of plates that are used, and in the
configurations of those plates.
– Some plates may be stamped with "chevron" or other patterns, where
others may have machined fins and/or grooves.
HEAT EXCHANGER (HE)

SHELL-AND-TUBE TYPE (STT)

Ducting
Ducts are usually galvanized sheet steel, aluminum
sheets or stainless steel sheets, shaped into rectangular
boxes or round tubes. They are used to distribute the cool
air from the Air Handling Unit (AHU), uniformly throughout
the building to be airconditioned. They start at the AHU, or
the packaged airconditioner, and travel to the spaces to be
conditioned carrying the cool air.
Criteria. Typical recommended velocities are:
Residences: 3 m/s to 5 m/s
Theatres: 4 to 6.5 m/s
Restaurants: 7.5 m/s to 10 m/s
If nothing is specified, then a velocity of 5 to 8 m/s is used for
main ducts and a velocity of 4 to 6 m/s is used for the branches.
The allowable air velocities can be as high as 30 m/s in ships
and aircrafts to reduce the space requirement. x

SHAPES OF AIR DUCT
1.Rectangular
• More easily fabricated on site, air leakage
2.Round
• Less fluid resistance, better rigidity/strength
3.Flat oval
4. Flexible
• Multiple-ply polyester film w/ metal wire or strips
1
2
3
4

OPTIMAL AIR DUCT DESIGN
• Optimal duct system layout, space available
• Satisfactory system balance
• Acceptable sound level
• Optimum energy loss and initial cost
• Install only necessary balancing devices (dampers)
• Fire codes, duct construction & insulation

V.A.V (Variable Air Volume)
The simplest VAV system incorporates one supply duct that, when in cooling
mode, distributes approximately 55 °F (13 °C) supply air. Because the supply air
temperature, in this simplest of VAV systems, is constant, the air flow rate must vary to
meet the rising and falling heat gains or losses within the thermal zone served.
There are two primary advantages to VAV systems over constant-volume
systems.
 The fan capacity control, especially with modern electronic variable-speed
drives, reduces the energy consumed by fans, which can be a substantial part of the
total cooling energy requirements of a building.
 Dehumidification is greater with VAV systems than it is with constant-volume system,
which modulate the discharge air temperature to attain part load cooling capacity.
A VAV terminal unit, often called a VAV box, is the
zone-level flow control device. It is basically a quality,
calibrated air damper with an automatic actuator. The VAV
terminal unit is connected to either a local or a central control
system.
Historically, pneumatic control was commonplace,
but electronic direct digital control systems are popular
especially for mid-to-large size applications. Hybrid control,
for example having pneumatic actuators with digital data
collection, is popular as well.

DIFFUSERS

Light Troffer-Diffuser:
A light troffer-diffuser combines a fluorescent light troffer and
a slot diffuser. The slot can be used either as supply air outlet or return
air inlet. Light troffer-diffusers offer the following advantages:
a) The luminous efficiency of fluorescent lamps can be increased by
maintaining lower air temperature in the light troffer
b) An integrated layout of light troffer, diffuser and return slots can be
formed on suspended ceilings
c) Improved aesthetics

Air conditioning system and its
Applications
• Centralized systems- types – Packed air conditioning- window air
conditioning- Air conditioning systems for various types of buildings.

AIR CURTAIN
An air door or air curtain is a device used for separating two spaces from each
other, usually at the exterior entrance.
Normally the opening is an entrance to a building, or opening between two space
conditioned at different temperatures.
They can be intended to help keep flying insects out by creating forceful turbulence.
It helps keep out outside air, reducing infiltration though the opening. They can
also be used to avoid cold drafts by mixing in warm air heated by the air curtain.

AIR CURTAIN - COMPONENTS

Ventilation
The term ventilation is used to
mean the free passage of air in a
structure. In other words, the
removal of all vitiated air from a
building and its replacement with
fresh air is known as Ventilation.
Factors Affecting Ventilation:
Air Changes
Humidity
Quality of Air
Temperature
Use of Building.
The systems of ventilation may broadly
be classified into two categories:
1. Natural Ventilation
2. Mechanical Ventilation
Following are the Five methods of
Aritifical Ventilation:
1. Exhaust Fan
2. Supply System
3. Combination of exhaust and
supply systems.
4. Plenum Process
5. Air-conditioning.
human comfortK.KEDHEESWARAN M.Arch 98

Summer Air-Conditioning
Filter Dehumidifier Reheating
In summer, the outside air is hot and hence, the process of air-conditioning involves
filtering, dehumidification and reheating. The temperature of inside air will be lower
than that of outside air and will be economical to recirculate a part of the room air.
Recirculated Air
Fresh Air
Conditioned Air

Winter Air-Conditioning
human comfort
Filter HumidifierPreheating
In summer, the outside air is cool and hence, the process of air-conditioning involves
filtering, preheating and humidification. The temperature of inside air will be higher
than that of outside air and will be economical to recirculate a part of the room air.
Recirculated Air
Fresh Air
Conditioned Air

•
Type LG Air Conditioners Samsung Air Conditioners
Window AC
Rs. 11,000
Rs. 14,000 to 14,400
Rs. 15,700 to 18,400
Rs. 22,000.
---
Rs. 15,100 to 16,000.
Rs. 17,200 to 20,300.
Rs. 21,200.
0.75 Ton
1.0 Ton
1.5 Ton
2.0 Ton
Split AC
Rs. 15,000
Rs. 19,400 to 23,500
Rs. 25,000 to 31,000
Rs. 27,500 to 49,000
---
Rs. 20,700 to 25,800
Rs. 24,800 to 32,000
Rs. 30,100 to 30,200
0.75 Ton
1.0 Ton
1.5 Ton
2.0 Ton
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