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ARE U COMFORTABLE ?WHAT WE SAY ABOUT
DISCOMFORT ?
WHAT AIR CONDITIONING
ENGINEER DOES ?
It is too warm The air is cooled
It is too cold The air is warmed
ARE U COMFORTABLE ?WHAT WE SAY ABOUT
DISCOMFORT ?
WHAT AIR CONDITIONING
ENGINEER DOES ?
It is too humid Excess moisture in the air is removed
It is too stuffyThe conditioned air is circulated gently
ARE U COMFORTABLE ?WHAT WE SAY ABOUT
DISCOMFORT ?
WHAT AIR CONDITIONING
ENGINEER DOES ?
It is dusty or smoky The air is filtered
There is an unpleasant odour The bad air is exhausted and fresh air is taken
The air is stale The air is mixed with fresh outside air.
MOST OF THE AIRCONDITIONING IS ABOUT REMOVING HEAT.
THERE ARE TWO TYPES OF HEAT:
Sensible Heat
Latent Heat
Airconditioning is defined as a process which cools ( or heats),
cleans, circulates, freshens air and controls its moisture content
simultaneously.
WHAT IS AIRCONDITIONING ?
HOW IS COOLING MADE POSSIBLE ?
CONCEPT OF HUMIDITY AND RELATIVE HUMIDITY, HEAT AND SPECIFIC HEAT.
EQUIPMENT USED TO PRODUCE COOLING
1 Ton Refrigeration ( Or 1TR) = 12000 Btu/hr
or 3000 K Cal/hr
AIRCONDITIONING CAPACITY- THE ‘TON’
TYPE OF AIRCONDITIONING SYSTEM
AIRCONDITIONING BRANCHES
CENTRAL
AIRCONDITIOING SYSTEMNON-CENTRAL
AIRCONDITIONING
SYSTEM
CHILLED
WATER
SYSTEM
DX
SYSTEM
VARIABLE
REFRIGERANT
FLOW SYSTEM
NON DUCTED
PRODUCTS
NON DUCTED PRODUCT
WINDOW
AIRCONDITIONERS
SPLIT
AIRCONDITIONERS
Floor
mountedWall mounted Ceiling
mounted
Exposed type Concealed
type
Semi
concealed
(cassette type)
DUCTED PRODUCT ( DX SYSTEM)
PACKAGED
AIRCONDITIONERS
CEILING
SUSPENDED
UNIT
FLOOR
MOUNTED
PACKAGED
AC.
AIRCOOLED WATER
COOLED
TYPICAL PACKAGED AC LAYOUT
(THREE DIMENSIONAL)
TYPICAL DUCTABLE AC LAYOUT
(THREE DIMENSIONAL)
CENTRAL PLANT
VARIABLE
REFRIGERANT
FLOW
SYSTEMS
DX
SYSTEMS
CHILLED
WATER
SYSTEMS
VAPOUR
COMPRESSION
UNIT
VAPOUR
ABSORPTION
UNITS.
RECP.
UNITS, AIR
& WATER
COOLED
CENTRIFUG
AL UNITS,
WATER
COOLED
ONLY
SCREW
UNIT AIR
& WATER
COOLED
DIRCET
FIRED
HOT
WATER
FIRED
STEAM
FIRED
SINGLE &
2 STAGE
Type of Compressor used in Window, Split and Packaged Airconditioners.
HERMATICALLY SEALED COMPRESSOR
RECEIPROCATING
COMPRESSOR
SCROLL
COMPRESSOR
ROTARY
COMPRESSOR
NON CENTRAL AC PRODUCTS
Window Acs
High wall splits
NON CENTRAL AC PRODUCTS
Floor mounted splits
Ceiling –mounted (exposed) splits
NON CENTRAL AC PRODUCTS
Ceiling –mounted (concealed) splits
Ceiling-mounted (semi-concealed,
or Cassette) splits
WINDOW ACs
Inexpensive
Easy to install
Each room can operate its Ac independently
Simple, low-cost, service and maintenance
Running costs are low
MERITS :
WINDOW ACs
Tonnages are limited ( 1 to 2TR typically)
Noisier (than other types of Acs)
A window is required, and blocked, by the AC
No constant fresh air circulation
DEMERITS :
Keeping the above attributes in view, Window Acs are useful in :
Homes
Small office executive cabins
Small shops
SOME OF THESE OPTIONS ARE :
Rotary compressors : Less noisy and more efficient.
Electronic thermostats : Switch the AC on and off more
precisely. Saving power and
cooling to the right temperature.
Remote controls : Allow you to control your AC
from where you are ( in bed or at
your work- table), thus allowing
constant control and increased
efficiency.
Sleep function : Saves power and provides better
comfort.
MINI-SPLIT ACS ( ALSO CALLED HIWALL AC’S)
MERITS :
Quieter than Window ACs
Available in larger tonnages (even upto 5TR in Turbo Splits)
Do not require, or block, a window
May be used as ‘multiple’ units to cool 2 or 3 adjacent rooms
May suit the interiors better.
May be found aesthetically better suited
MINIS-SPLIT ACS
DEMERITS :
Costlier than Window ACs
Require space outside the room for the outdoor unit.
Some piping and cabling necessary.
Do not provide for fresh air intake.
Keeping the above attributes in view, Split Acs are useful in :
Senior executive cabins
Professionally positioned small or mid-sized showrooms.
Up-market homes
Small clinics, ATMs, etc.
Saturated Air
Dew point temperature
Dry Bulb temperature
Wet Bulb temperature
Standard Air
Atmospheric pressure
Specific Density
Specific Volume
Relative Humidity
Specific Humidity
Specific Heat
Sensible Heat
Latent Heat
Total Heat
TERMINOLOGIES USED IN AC
AIR DISTRIBUTION SYSTEM
AIR DISTRIBUTION SYSTEM
CIRCULATION FAN
AIR CONDITIONING APPARATUS
SUPPLY AIR DUCT
SUPPLY AIR OUTLETS
RETURN AIR PASSAGE ( OR DUCT,
WHENEVER REQUIRED )
RETURN AIR GRILLES
FRESH AIR INTAKES
AIR CLEANING FILTERS
CONTROLLING DAMPERS
AIR DISTRIBUTION SYSTEM
AIR DISTRIBUTION SYSTEM
AIR DISTRIBUTION SYSTEM
HEAT LOAD (COOLING LOAD)
CONSTITUENT OF HEAT LOAD:
External Load Internal Load Other Load
EXTERNAL LOAD
Heat gain by Conduction ( Through walls, roof, windows etc.)
Solar Heat gain
Through Ventilation & infiltration.INTERNAL LOAD
People Light Appliances & equipments.
OTHER LOADThese are the system generated heat sources such as :
Supply/Return air duct leakage and heat gain.
Heat gain from fan motor
Sensible heat load components
Latent heat load components
HEAT LOAD COMPONENT ( BEYOND CONTROL OF HVAC ENGINEER)
Orientation of Building
Design ambient conditions during Summer/ Winter/ Monsoon
Type of Construction.
Colour & texture of outside surface of the building.
Location of insulation, if provided.
SALIENT FEATURE OF BMS ( BUILDING MANAGEMENT SYSTEM)* Automatic operation.
*Optimized equalization.
* Load Rolling/ Sequencing.
* Finger tip information on :
Operation parameters.
Energy usage
Maintenance records
Breakdown history.
Running Cost control
System interface with other utilities.
A BMS is considered a strategic investment as it can result in life
long savings.
ARCHITECT - HVAC ENGINEER’S DIALOGUE FOR GOOD ENGINEERING PRACTICE.
•Plant Room space in basement with adequate height of 4.3 to 4.9mt for water cooled
system.
* Open space on terrace or ground floor level for Air-cooled Chiller.
* Clear height available above false ceiling for running duct work.
* Space available for installing AHU near shaft.
* Accessible space above false ceiling for AC area.
* Or passages for monitoring split unit coolers.
* Accessible space for condensing unit.
* Possibility of locating fresh air intakes above false ceiling level for split units.
* Space for shafts to carry chilled water and condenser water pipes.
* Availability of drain lines to facilitate drainage from split unit coolers.
