Basics of HVAC

By Kamaal Ahamed
BASICS OF HVAC

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What is HVAC ?
 H-Heating
 V-Ventilation
 AC-Air conditioning

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What is TR (Ton of refrigeration )
1 TR is defined as the heat removal rate so as to freeze 1 ton (2000 lb) of water at 0°C
into ice at 0°C in twenty-four hours
1 TR =12000 BTU/HR, or 3.5 KW

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What we are going to learn?
 Function of HVAC.
 Basic operation cycle .
 Classification of AC system.
 Various AC system.
 Types of compressor.
 Type of chillers.
 Fans.
 Cooling Towers.
 AHU
 Maglev chiller etc.

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Function of air conditioning
 Control of air temperature
 Control of moisture
 Proper air movement
 Air quality

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Typical refrigeration cycle
12
3
4

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Types of compressors
Centrifugal Compressor
Reciprocating Compressor
Screw compressor
Scroll
compressor

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Cooling Tower
Range – 5 Deg C
Approach -2.77deg C
Efficiency –Range /(range +approach)

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Chilled water based Centralized air conditioning system

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Type of air conditioners

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Ducting accessories

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Air filters
Group of filters Trapped particles Class Efficiency
Filters for coarse particles
(>10 micron)
Insects,Textile fibres, Fluff,
Sand, Pollen, Cement dust
G2
G3
G4
90%
Filters for small particles
(from 1 to 10 micron)
Spores,
Fluff,
Cement dust,
Bacteria,
Dust from the ambient air
F5 M5 F6 M6
80%
Filters for small particles
(from 1 to 10 micron)
Tobacco smoke,
Metal oxide fumes
F7
F8
F9
95%
Filters type EPA for particles
smaller than 1 micron to .03
Micron
Bacteria,
Viruses,
Tobacco smoke,
Metal oxide
fumes, Microbes
E 10
E 11
99.9%
99.97%
Filters type HEPA 0.01 to
0.0001
Microbes E12 99.99%
Filters type HEPA Microbes, Aerosols H13 99.99%
Filters type НEPA
Filters type ULPA
Aerosols H14
U15
U16
U17

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Raised floor Hot and cold aisles
Raised floor and hot and cold aisles

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Cold aisle containment and hot aisle containment

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Centrifugal fans/blower

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Fan efficiency curve

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Comparison curve volume control method

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Maglev chiller
Magnetic levitation (maglev) or magnetic suspension is a method by which an object
is suspended with no support other than magnetic fields Magnetic force is used to
counteract the effects of the gravitational acceleration and any other accelerations.

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Permanent magnet and induction motor efficiency curve

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Comparison b/w maglev and traditional chillers

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Variation of KW/TR with ECWT

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1.Coefficient of performance
COP = kW refrigeration effect
kW input
2. Energy efficiency ratio
EER = Btu/h refrigeration effect
Watt input
3. Power per Ton
‘
kW/Ton = kW input
Tons refrigeration effect
Parameters of AC performance

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Heat load design conditions
OUTSIDE DESIGN CONDITIONS
STATE & STATION LATITUDE
(Deg. N)
ALTITUDE
(Mts.)
SUMMER °C MONSOON °C WINTER °C RELATIVE
HUMIDITY
%DB WB DB WB DB WB
Mumbai,
Maharashtra
18.54 11 35 28.3 29.4 27.8 18.3 14.4 60
INSIDE DESIGN CONDITIONS
TEMPERATURE 24 Degree Celsius + 2 Deg.C
RELATIVE HUMIDITY 55% + 5%. (Not Exceeding 60%)
OCCUPANCY 100 Sq.ft Per Person.
COMPUTER LOAD 150 W Per Computer
FRESH AIR 5 CFM per Person & 0.06 Cfm/Sq.ft. + 30% Extra above
ASHRAE 90.1 Standard.
LIGHTING LOAD 0.8 Watts/Sq. Ft – Assuming LED Lights.

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Evap. Temp
(0C)
Cond.
Temp
(0C)
Refrigeration
Capacity* (tons)
Specific Power
Consumption
(kW/ton)
Increase in
kW/Ton
(%)
Normal 7.2 40.5 17.0 0.69 -
Dirty condenser 7.2 46.1 15.6 0.84 20.4
Dirty evaporator 1.7 40.5 13.8 0.82 18.3
Dirty condenser
and evaporator
1.7 46.1 12.7 0.96 38.7
Effect of Poor Maintenance on Compressor Power Consumption

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 Output kW= 400*0.9 (PF)=360 kw,
 Input kW=Output kW/UPS Eff %=360/0.94=382.98 kW,
 Heat loss(load)=Input-output=382.98–360=22.98 kW,
 Now since 3.514 kW=1 TR,
 Hence 22.98 kW=22.98/3.514=6.54 TR
 Note:- This capacity of cooling load is only for UPS. Don't forget to consider/add
Note : cooling load of enclosure/room as well in addition to this. This can be done using
thumb rule of 1TR/10 sqm of room.
UPS room AC design
400 KVA UPS

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Server room AC heat load calculation
• Room Area BTU = Length (m) x Width (m) x 337
• South Window BTU = South Facing window Length (m) x Width (m) x 870
• North Window BTU = North Facing windows Length (m) x Width (m) x 165
• If there are no blinds on the windows multiply the result(s) by 1.5.
• Windows BTU = South Window(s) BTU + North Window(s) BTU
• Total Occupant BTU = Number of occupants x 400
• Equipment BTU = Total wattage for all equipment x 3.5
• Lighting BTU = Total wattage for all lighting x 4.25
Room Area BTU + Windows BTU + Total Occupant BTU + Equipment BTU + Lighting BTU =
Total Heat Load

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HVAC standard
• ASHRAE Standard 90.1 -Energy efficiency requires such chillers to have a minimum efficiency
between 0.577 – 0.634 kW/ton efficiency with an average part-load efficiency (IPLV) of 0.54 -
0.78.
• ASHRAE Standard 62.1-2019- Ventilation
• ASHRAE Standard 55-Thermal comfort
• ASHRAE 52.1, 52.2 (MERV Ratings)
• (SMACNA) Sheet Metal and Air Conditioning Contractors’ National Association – Duct

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HVAC is committed to :
Providing maximum comfort for Human being
To satisfy the industrial need

Basics of HVAC

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