Hvac Presentation
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Slide Content
HVAC Systems – Understanding HVAC Systems – Understanding
the basisthe basis
Table of ContentsTable of Contents
1.1.Introduction to HVAC SystemsIntroduction to HVAC Systems
2.2.HVAC System TypesHVAC System Types
3.3.HVAC Piping SystemHVAC Piping System
4.4.HVAC Air Distribution EquipmentsHVAC Air Distribution Equipments
5.5.Fans and PumpsFans and Pumps
6.6.HVAC Instrumentation and ControlHVAC Instrumentation and Control
7.7.HVAC System CommissioningHVAC System Commissioning
the basisthe basis
Table of ContentsTable of Contents
1.1.Introduction to HVAC SystemsIntroduction to HVAC Systems
2.2.HVAC System TypesHVAC System Types
3.3.HVAC Piping SystemHVAC Piping System
4.4.HVAC Air Distribution EquipmentsHVAC Air Distribution Equipments
5.5.Fans and PumpsFans and Pumps
6.6.HVAC Instrumentation and ControlHVAC Instrumentation and Control
7.7.HVAC System CommissioningHVAC System Commissioning
Introduction to HVAC SystemsIntroduction to HVAC Systems
This article introduces the heating, ventilating and air-conditioning This article introduces the heating, ventilating and air-conditioning
(HVAC) systems. The primary function of HVAC systems is to provide (HVAC) systems. The primary function of HVAC systems is to provide
healthy and comfortable interior conditions for occupants; well-healthy and comfortable interior conditions for occupants; well-
designed, efficient systems do this with minimal non-renewable designed, efficient systems do this with minimal non-renewable
energy and air, and water pollutant emissions.energy and air, and water pollutant emissions.
This article introduces the heating, ventilating and air-conditioning This article introduces the heating, ventilating and air-conditioning
(HVAC) systems. The primary function of HVAC systems is to provide (HVAC) systems. The primary function of HVAC systems is to provide
healthy and comfortable interior conditions for occupants; well-healthy and comfortable interior conditions for occupants; well-
designed, efficient systems do this with minimal non-renewable designed, efficient systems do this with minimal non-renewable
energy and air, and water pollutant emissions.energy and air, and water pollutant emissions.
Introduction to HVAC SystemsIntroduction to HVAC Systems
The purpose of The purpose of HVAC design HVAC design is both high indoor air quality and energy is both high indoor air quality and energy
efficiency. These dual considerations require an integrated design efficiency. These dual considerations require an integrated design
approach. Rigs heating, approach. Rigs heating,
ventilation, and air conditioning ventilation, and air conditioning
system (HVAC) creates a climate system (HVAC) creates a climate
that allows for maximum comfort by that allows for maximum comfort by
compensating for changing climatic compensating for changing climatic
conditions.conditions.
Though more costly to install and more complicated to operate, a chiller plant Though more costly to install and more complicated to operate, a chiller plant
offers a number of benefits over a large number of individual packaged offers a number of benefits over a large number of individual packaged
cooling units, including greater energy efficiency, better controllability, cooling units, including greater energy efficiency, better controllability,
cheaper overall maintenance, and longer life. Using a comprehensive cheaper overall maintenance, and longer life. Using a comprehensive
approach to building design, designers around the world have succeeded at approach to building design, designers around the world have succeeded at
creating highly efficient air-conditioning systems that provide excellent creating highly efficient air-conditioning systems that provide excellent
comfort at significant savings. comfort at significant savings.
The purpose of The purpose of HVAC design HVAC design is both high indoor air quality and energy is both high indoor air quality and energy
efficiency. These dual considerations require an integrated design efficiency. These dual considerations require an integrated design
approach. Rigs heating, approach. Rigs heating,
ventilation, and air conditioning ventilation, and air conditioning
system (HVAC) creates a climate system (HVAC) creates a climate
that allows for maximum comfort by that allows for maximum comfort by
compensating for changing climatic compensating for changing climatic
conditions.conditions.
Though more costly to install and more complicated to operate, a chiller plant Though more costly to install and more complicated to operate, a chiller plant
offers a number of benefits over a large number of individual packaged offers a number of benefits over a large number of individual packaged
cooling units, including greater energy efficiency, better controllability, cooling units, including greater energy efficiency, better controllability,
cheaper overall maintenance, and longer life. Using a comprehensive cheaper overall maintenance, and longer life. Using a comprehensive
approach to building design, designers around the world have succeeded at approach to building design, designers around the world have succeeded at
creating highly efficient air-conditioning systems that provide excellent creating highly efficient air-conditioning systems that provide excellent
comfort at significant savings. comfort at significant savings.
Introduction to HVAC SystemsIntroduction to HVAC Systems
Heating, ventilating and air-Heating, ventilating and air-
conditioning (HVAC) systems conditioning (HVAC) systems
reduce the environmental reduce the environmental
impact of rigs/buildings in several impact of rigs/buildings in several
key ways. The most important key ways. The most important
function of a HVAC systems is function of a HVAC systems is
to provide the rig/buildings occupants to provide the rig/buildings occupants
with healthy and comfortable interior with healthy and comfortable interior
conditions. A carefully designed, efficient conditions. A carefully designed, efficient
system can do this with minimal non-system can do this with minimal non-
renewable energy and air and water pollutant emissions to minimize the renewable energy and air and water pollutant emissions to minimize the
environmental impact. environmental impact.
Cooling equipment that avoids chlorofluorocarbons and hydro- Cooling equipment that avoids chlorofluorocarbons and hydro-
chlorofluorocarbons (CFCs and HCFCs) eliminates a major cause of chlorofluorocarbons (CFCs and HCFCs) eliminates a major cause of
damage to the ozone layer.damage to the ozone layer.
Heating, ventilating and air-Heating, ventilating and air-
conditioning (HVAC) systems conditioning (HVAC) systems
reduce the environmental reduce the environmental
impact of rigs/buildings in several impact of rigs/buildings in several
key ways. The most important key ways. The most important
function of a HVAC systems is function of a HVAC systems is
to provide the rig/buildings occupants to provide the rig/buildings occupants
with healthy and comfortable interior with healthy and comfortable interior
conditions. A carefully designed, efficient conditions. A carefully designed, efficient
system can do this with minimal non-system can do this with minimal non-
renewable energy and air and water pollutant emissions to minimize the renewable energy and air and water pollutant emissions to minimize the
environmental impact. environmental impact.
Cooling equipment that avoids chlorofluorocarbons and hydro- Cooling equipment that avoids chlorofluorocarbons and hydro-
chlorofluorocarbons (CFCs and HCFCs) eliminates a major cause of chlorofluorocarbons (CFCs and HCFCs) eliminates a major cause of
damage to the ozone layer.damage to the ozone layer.
Introduction to HVAC SystemsIntroduction to HVAC Systems
Even the best HVAC equipment and systems cannot compensate for a Even the best HVAC equipment and systems cannot compensate for a
faulty rig design. Problems of this type cause inherently high cooling and faulty rig design. Problems of this type cause inherently high cooling and
heating needs and consume unnecessary resources and should be heating needs and consume unnecessary resources and should be
corrected if possible. Conservation of non-renewable energy through an corrected if possible. Conservation of non-renewable energy through an
intelligent architectural design offers the greatest opportunity for savings. intelligent architectural design offers the greatest opportunity for savings.
The most important factors in these designs are careful control of solar gain, The most important factors in these designs are careful control of solar gain,
while taking advantage of passive heating, daylighting, natural ventilation while taking advantage of passive heating, daylighting, natural ventilation
and cooling. The critical factors in mechanical systems' energy consumption and cooling. The critical factors in mechanical systems' energy consumption
- and capital cost - are reducing the cooling and heating loads they must - and capital cost - are reducing the cooling and heating loads they must
handle.handle.
Even the best HVAC equipment and systems cannot compensate for a Even the best HVAC equipment and systems cannot compensate for a
faulty rig design. Problems of this type cause inherently high cooling and faulty rig design. Problems of this type cause inherently high cooling and
heating needs and consume unnecessary resources and should be heating needs and consume unnecessary resources and should be
corrected if possible. Conservation of non-renewable energy through an corrected if possible. Conservation of non-renewable energy through an
intelligent architectural design offers the greatest opportunity for savings. intelligent architectural design offers the greatest opportunity for savings.
The most important factors in these designs are careful control of solar gain, The most important factors in these designs are careful control of solar gain,
while taking advantage of passive heating, daylighting, natural ventilation while taking advantage of passive heating, daylighting, natural ventilation
and cooling. The critical factors in mechanical systems' energy consumption and cooling. The critical factors in mechanical systems' energy consumption
- and capital cost - are reducing the cooling and heating loads they must - and capital cost - are reducing the cooling and heating loads they must
handle.handle.
HVAC System TypesHVAC System Types
Types of System Designs - There are several major heating, ventilating, and air Types of System Designs - There are several major heating, ventilating, and air
conditioning system types in wide spread use today. These are air systems, hydronic conditioning system types in wide spread use today. These are air systems, hydronic
and steam systems, and unitary type systems. Most systems in use today fall into one of and steam systems, and unitary type systems. Most systems in use today fall into one of
these categories, or are a combination or variation of them. Each type of system has these categories, or are a combination or variation of them. Each type of system has
advantages and disadvantages.advantages and disadvantages.
Air cooledAir cooled
- - Air cooledAir cooled Chillers Chillers
Types of System Designs - There are several major heating, ventilating, and air Types of System Designs - There are several major heating, ventilating, and air
conditioning system types in wide spread use today. These are air systems, hydronic conditioning system types in wide spread use today. These are air systems, hydronic
and steam systems, and unitary type systems. Most systems in use today fall into one of and steam systems, and unitary type systems. Most systems in use today fall into one of
these categories, or are a combination or variation of them. Each type of system has these categories, or are a combination or variation of them. Each type of system has
advantages and disadvantages.advantages and disadvantages.
Air cooledAir cooled
- - Air cooledAir cooled Chillers Chillers
Air Cooled Chiller AdvantagesAir Cooled Chiller Advantages
•Lower installed costLower installed cost
•Quicker availabilityQuicker availability
•No cooling tower or condenser pump requiredNo cooling tower or condenser pump required
•Less maintenanceLess maintenance
•No mechanical room requiredNo mechanical room required
•Lower installed costLower installed cost
•Quicker availabilityQuicker availability
•No cooling tower or condenser pump requiredNo cooling tower or condenser pump required
•Less maintenanceLess maintenance
•No mechanical room requiredNo mechanical room required
Water CooledWater Cooled
- Sea Water cooled Chillers- Sea Water cooled Chillers
- Fresh Water cooled Chillers- Fresh Water cooled Chillers
- Sea Water cooled Chillers- Sea Water cooled Chillers
- Fresh Water cooled Chillers- Fresh Water cooled Chillers
Water-Cooled Chiller advantagesWater-Cooled Chiller advantages
•Higher efficiencyHigher efficiency
•Custom selection in larger sizesCustom selection in larger sizes
•Large tonnage capabilitiesLarge tonnage capabilities
•Indoor Chiller locationIndoor Chiller location
•Longer lifeLonger life
•Higher efficiencyHigher efficiency
•Custom selection in larger sizesCustom selection in larger sizes
•Large tonnage capabilitiesLarge tonnage capabilities
•Indoor Chiller locationIndoor Chiller location
•Longer lifeLonger life
Purpose of an air handling systemPurpose of an air handling system
Air Handling
System
Room
With
Defined
Requirements
Supply
Air
Outlet
Air
Air Handling Systems
Air Handling
System
Room
With
Defined
Requirements
Supply
Air
Outlet
Air
Air Handling Systems
Objectives
In the following slides, we will study the components of
air handling systems in order to:
1. Become familiar with the components
2. Know their functions
3. Become aware of possible problems
In the following slides, we will study the components of
air handling systems in order to:
1. Become familiar with the components
2. Know their functions
3. Become aware of possible problems
+
Room/Cabin
Exhaust air treatment
Central air handling unit
Terminal air treatment
at production room level
Fresh air treatment
(make-up air)
Main subsystems
Room/Cabin
Exhaust air treatment
Central air handling unit
Terminal air treatment
at production room level
Fresh air treatment
(make-up air)
Main subsystems
FilterSilence
r
Terminal filter
Weather louvre
Control damper
FanFlow rate controller
Humidifier
Heating
coil
Cooling
coil
with
droplet
separator
Production Room
Overview components
+
Prefilter
Exhaust Air Grille
Heater
Secondary Filter
Re-circulated
air
r
Terminal filter
Weather louvre
Control damper
FanFlow rate controller
Humidifier
Heating
coil
Cooling
coil
with
droplet
separator
Production Room
Overview components
+
Prefilter
Exhaust Air Grille
Heater
Secondary Filter
Re-circulated
air
Weather Weather
louvrelouvre
SilencerSilencer
Flow rate Flow rate
controller controller
Control Control
damperdamper
To prevent insects, leaves, To prevent insects, leaves,
dirtdirt and rain and rain from entering from entering
To reduce noise caused by air To reduce noise caused by air
circulationcirculation
Automated adjustment of Automated adjustment of
volume of air (night and day, volume of air (night and day,
pressure control)pressure control)
Fixed adjustment of volume Fixed adjustment of volume
of airof air
Components (1)
louvrelouvre
SilencerSilencer
Flow rate Flow rate
controller controller
Control Control
damperdamper
To prevent insects, leaves, To prevent insects, leaves,
dirtdirt and rain and rain from entering from entering
To reduce noise caused by air To reduce noise caused by air
circulationcirculation
Automated adjustment of Automated adjustment of
volume of air (night and day, volume of air (night and day,
pressure control)pressure control)
Fixed adjustment of volume Fixed adjustment of volume
of airof air
Components (1)
Heating unitHeating unit
Cooling unit Cooling unit
/dehumidifier/dehumidifier
HumidifierHumidifier
FiltersFilters
DuctsDucts
ToTo heat heat the air to the proper the air to the proper
temperaturetemperature
To To cool cool the air to the the air to the requiredrequired
temperaturetemperature or to remove moisture or to remove moisture
from the airfrom the air
To bring the air to the properTo bring the air to the proper
humidity, if too lowhumidity, if too low
To eliminate particles of pre-To eliminate particles of pre-
determined dimensions and/or determined dimensions and/or
micro-organismsmicro-organisms
To transport the airTo transport the air
Components (2)
Cooling unit Cooling unit
/dehumidifier/dehumidifier
HumidifierHumidifier
FiltersFilters
DuctsDucts
ToTo heat heat the air to the proper the air to the proper
temperaturetemperature
To To cool cool the air to the the air to the requiredrequired
temperaturetemperature or to remove moisture or to remove moisture
from the airfrom the air
To bring the air to the properTo bring the air to the proper
humidity, if too lowhumidity, if too low
To eliminate particles of pre-To eliminate particles of pre-
determined dimensions and/or determined dimensions and/or
micro-organismsmicro-organisms
To transport the airTo transport the air
Components (2)
+
Production Room
Exhaust
air
Return air
(re-circulated)
Fresh air
(make-up air)
Supply
air
Air types
Production Room
Exhaust
air
Return air
(re-circulated)
Fresh air
(make-up air)
Supply
air
Air types
Filter classesFilter classes
Dust filters
Standard Aerosol
FineCoarse ULPAHEPA
10 µ m > Dp > 1 µ mDp > 10 µ m Dp < 1 µ m
F5 - F9G1 - G4 U 14- 17H 11 - 13
EN 1822 StandardEN 779 Standard
Dust filters
Standard Aerosol
FineCoarse ULPAHEPA
10 µ m > Dp > 1 µ mDp > 10 µ m Dp < 1 µ m
F5 - F9G1 - G4 U 14- 17H 11 - 13
EN 1822 StandardEN 779 Standard
Primary panel Primary panel
filterfilter
Secondary Secondary
filterfilter
HEPA or tertiaary filter
filterfilter
Secondary Secondary
filterfilter
HEPA or tertiaary filter
Duct heatersDuct heaters Room Heters Room Heters
SilensersSilensers
SilensersSilensers
Volume control damperVolume control damper
De-humidification
Filter Pressure
Gauges
AHU with fan
Variable Speed
Controller
Humid room air
Air heater
Regeneration air
Humid room air
Adsorber wheel Dry air
FireFire DampersDampers
De-humidification
Filter Pressure
Gauges
AHU with fan
Variable Speed
Controller
Humid room air
Air heater
Regeneration air
Humid room air
Adsorber wheel Dry air
FireFire DampersDampers
Annex 1, 17.26
Regulation of room pressureRegulation of room pressure – pressure – pressure
differentials conceptdifferentials concept
Room pressure
gauges
Room pressure indication panel
Regulation of room pressureRegulation of room pressure – pressure – pressure
differentials conceptdifferentials concept
Room pressure
gauges
Room pressure indication panel
Pressure cascade injectablesPressure cascade injectables
PProtection from micro-organisms and rotection from micro-organisms and
particlesparticles
N o t e : D i r e c t i o n o f d o o r o p e n i n g r e l a t i v e t o r o o m p r e s s u r e
1 5 P a
0 P a
A i r
L o c k
3 0 P a P a s s a g eD
C
A
B
D
L F
A i r L o c kA i r L o c k
4 5 P a
R o o m 3 R o o m 2 R o o m 1
4 5 P a6 0 P a3 0 P a
PProtection from micro-organisms and rotection from micro-organisms and
particlesparticles
N o t e : D i r e c t i o n o f d o o r o p e n i n g r e l a t i v e t o r o o m p r e s s u r e
1 5 P a
0 P a
A i r
L o c k
3 0 P a P a s s a g eD
C
A
B
D
L F
A i r L o c kA i r L o c k
4 5 P a
R o o m 3 R o o m 2 R o o m 1
4 5 P a6 0 P a3 0 P a
Pressure cascade solids
Protection from cross-contamination
Note : Direction of door opening relative to room pressure 15 Pa
15 Pa15 P a
E30 PaPassage 0 PaAirLock
Room 3 Room 2 Room 115 Pa
Air LockAir Lock
N o t e : D i r e c t i o n o f d o o r o p e n i n g r e l a t i v e t o r o o m p r e s s u r e
1 5 P a
1 5 P a1 5 P a
E
3 0 P a
P a s s a g e
0 P a
A i r
L o c k
R o o m 3 R o o m 2 R o o m 1
1 5 P a
A i r L o c kA i r L o c k
Protection from cross-contamination
Note : Direction of door opening relative to room pressure 15 Pa
15 Pa15 P a
E30 PaPassage 0 PaAirLock
Room 3 Room 2 Room 115 Pa
Air LockAir Lock
N o t e : D i r e c t i o n o f d o o r o p e n i n g r e l a t i v e t o r o o m p r e s s u r e
1 5 P a
1 5 P a1 5 P a
E
3 0 P a
P a s s a g e
0 P a
A i r
L o c k
R o o m 3 R o o m 2 R o o m 1
1 5 P a
A i r L o c kA i r L o c k
Fan Coil UnitFan Coil Unit
Self Contain Unit Self Contain Unit
HVAC Air Distribution EquipmentsHVAC Air Distribution Equipments
DiffusersDiffusers
4 Way Diffusers4 Way Diffusers Two Way Diffusers One Way DiffuserTwo Way Diffusers One Way Diffuser
Round DiffusersRound Diffusers
DiffusersDiffusers
4 Way Diffusers4 Way Diffusers Two Way Diffusers One Way DiffuserTwo Way Diffusers One Way Diffuser
Round DiffusersRound Diffusers
Cabin UnitsCabin Units
Return / Exhaust GrillesReturn / Exhaust Grilles
ContentsContents
Fan DesignFan Design
Fan PerformanceFan Performance
Fan-duct SystemsFan-duct Systems
Duct ConstructionDuct Construction
Air Duct DesignAir Duct Design
Fans and Pumps
Fan DesignFan Design
Fan PerformanceFan Performance
Fan-duct SystemsFan-duct Systems
Duct ConstructionDuct Construction
Air Duct DesignAir Duct Design
Fans and Pumps
Fan DesignFan Design
Common types of fansCommon types of fans
Centrifugal fansCentrifugal fans: radial, forward curved, air : radial, forward curved, air
foil (backward curved), backward inclined, foil (backward curved), backward inclined,
tubular, roof ventilatortubular, roof ventilator
Axial fansAxial fans: propeller, tube-axial, vane-axial: propeller, tube-axial, vane-axial
Fan arrangementsFan arrangements
Motor location, air discharge orientation, drive Motor location, air discharge orientation, drive
train type (direct drive or pulley drive)train type (direct drive or pulley drive)
Centrifugal: single width single inlet (SWSI), Centrifugal: single width single inlet (SWSI),
double width double inlet (DWDI)double width double inlet (DWDI)
Common types of fansCommon types of fans
Centrifugal fansCentrifugal fans: radial, forward curved, air : radial, forward curved, air
foil (backward curved), backward inclined, foil (backward curved), backward inclined,
tubular, roof ventilatortubular, roof ventilator
Axial fansAxial fans: propeller, tube-axial, vane-axial: propeller, tube-axial, vane-axial
Fan arrangementsFan arrangements
Motor location, air discharge orientation, drive Motor location, air discharge orientation, drive
train type (direct drive or pulley drive)train type (direct drive or pulley drive)
Centrifugal: single width single inlet (SWSI), Centrifugal: single width single inlet (SWSI),
double width double inlet (DWDI)double width double inlet (DWDI)
Centrifugal and axial fan components
AXIAL FANS CENTRIFUGAL FANS
AXIAL FANS CENTRIFUGAL FANS
Propeller
Tube-axial
Tube-vane
AXIAL FANS
Tube-axial
Tube-vane
AXIAL FANS
Tubular centrifugal fan Centrifugal roof ventilator
CENTRIFUGAL FANS
(* Note the airflow paths and impeller design.)
CENTRIFUGAL FANS
(* Note the airflow paths and impeller design.)
Drive arrangements and motor positions
Single- and double-width centrifugal fans
Fan PerformanceFan Performance
Major parametersMajor parameters
Fan volume flow rate (mFan volume flow rate (m
33
/s or l/s), /s or l/s), VV
ff
Fan total pressure Fan total pressure ΔΔpp
tftf, fan velocity pressure , fan velocity pressure
pp
vfvf & fan static pressure & fan static pressure ΔΔpp
sf sf (Pa)(Pa)
Fan power & efficiencyFan power & efficiency
•Fan power or air power (W) = Fan power or air power (W) = ΔΔpp
tftf x x VV
ff
•Fan power input on the fan shaft (brake Fan power input on the fan shaft (brake
horsepower), horsepower), PP
ff
•Fan total efficiency: Fan total efficiency: ηη
tt = = ΔΔpp
tftf x x VV
f f / / PP
ff
Combined aerodynamic, volumetric & mechanical Combined aerodynamic, volumetric & mechanical
efficienciesefficiencies
•Fan static efficiency: Fan static efficiency: ηη
ss = = ΔΔpp
sfsf x x VV
f f / / PP
ff
•Air temp. increase through fan, Air temp. increase through fan, ΔΔTT
ff = = ΔΔpp
tftf /( /(ρρcc
papaηη
tt))
Major parametersMajor parameters
Fan volume flow rate (mFan volume flow rate (m
33
/s or l/s), /s or l/s), VV
ff
Fan total pressure Fan total pressure ΔΔpp
tftf, fan velocity pressure , fan velocity pressure
pp
vfvf & fan static pressure & fan static pressure ΔΔpp
sf sf (Pa)(Pa)
Fan power & efficiencyFan power & efficiency
•Fan power or air power (W) = Fan power or air power (W) = ΔΔpp
tftf x x VV
ff
•Fan power input on the fan shaft (brake Fan power input on the fan shaft (brake
horsepower), horsepower), PP
ff
•Fan total efficiency: Fan total efficiency: ηη
tt = = ΔΔpp
tftf x x VV
f f / / PP
ff
Combined aerodynamic, volumetric & mechanical Combined aerodynamic, volumetric & mechanical
efficienciesefficiencies
•Fan static efficiency: Fan static efficiency: ηη
ss = = ΔΔpp
sfsf x x VV
f f / / PP
ff
•Air temp. increase through fan, Air temp. increase through fan, ΔΔTT
ff = = ΔΔpp
tftf /( /(ρρcc
papaηη
tt))
Fan performance curves
Total pressure
Static pressure
Fan total efficiency
Fan static efficiency
Fan power input
Velocity pressure
Volume flow rate
Total pressure
Static pressure
Fan total efficiency
Fan static efficiency
Fan power input
Velocity pressure
Volume flow rate
Typical fan performance curve
Fan PerformanceFan Performance
Fan LawsFan Laws
Speed (Speed (nn))
Volume flow (Volume flow (VV))
Total pressure loss Total pressure loss
((ΔΔpp ))
Air density (Air density (ρρ))
For air systems that For air systems that
are geometrically & are geometrically &
dynamically similar: dynamically similar:
(D = impeller (D = impeller
diameter)diameter)
c.f.: pump lawsc.f.: pump laws
Fan LawsFan Laws
Speed (Speed (nn))
Volume flow (Volume flow (VV))
Total pressure loss Total pressure loss
((ΔΔpp ))
Air density (Air density (ρρ))
For air systems that For air systems that
are geometrically & are geometrically &
dynamically similar: dynamically similar:
(D = impeller (D = impeller
diameter)diameter)
c.f.: pump lawsc.f.: pump laws
Velocity triangle at the blade inlet and outlet of a centrifugal fan
CENTRIFUGAL FANS
CENTRIFUGAL FANS
Fan PerformanceFan Performance
Major issues causing energy losses to a Major issues causing energy losses to a
centrifugal fan:centrifugal fan:
Circulatory flow between the bladesCirculatory flow between the blades
Air leakage at the inletAir leakage at the inlet
Friction between fluid particles and the bladeFriction between fluid particles and the blade
Energy loss at the entranceEnergy loss at the entrance
Partially filled passagePartially filled passage
Major issues causing energy losses to a Major issues causing energy losses to a
centrifugal fan:centrifugal fan:
Circulatory flow between the bladesCirculatory flow between the blades
Air leakage at the inletAir leakage at the inlet
Friction between fluid particles and the bladeFriction between fluid particles and the blade
Energy loss at the entranceEnergy loss at the entrance
Partially filled passagePartially filled passage
Operating characteristics for a backward-curved centrifugal fan
Total efficiency
curves for
centrifugal fans
curves for
centrifugal fans
Fan power curves for centrifugal fans with same impeller diameter
Fan pressure curves for centrifugal fans with same impeller diameter
Velocity triangles for a vane-axial fan
AXIAL FANS
AXIAL FANS
Fan pressure curves for axial fans with same impeller diameter
Fan efficiency curves for axial fans with same impeller diameter
Fan power curves for axial fans with same impeller diameter
Performance
curves for
controllable-
pitch vane-axial
fans
curves for
controllable-
pitch vane-axial
fans
Fan-duct SystemsFan-duct Systems
Duct pressure changes (c.f. atm Duct pressure changes (c.f. atm
pressure)pressure)
Static pressure (SP)Static pressure (SP)
Velocity pressure (VP) = Velocity pressure (VP) = ρρVV
2 2
/ 2 g/ 2 g
Total pressure (TP) = SP + VPTotal pressure (TP) = SP + VP
Fan: a pumping deviceFan: a pumping device
Fan (total) pressure = pressure difference Fan (total) pressure = pressure difference
between fan inlet and fan dischargebetween fan inlet and fan discharge
At fan suction/inlet, SP = negative (c.f. At fan suction/inlet, SP = negative (c.f.
atmospheric); at discharge, SP = positiveatmospheric); at discharge, SP = positive
Duct pressure changes (c.f. atm Duct pressure changes (c.f. atm
pressure)pressure)
Static pressure (SP)Static pressure (SP)
Velocity pressure (VP) = Velocity pressure (VP) = ρρVV
2 2
/ 2 g/ 2 g
Total pressure (TP) = SP + VPTotal pressure (TP) = SP + VP
Fan: a pumping deviceFan: a pumping device
Fan (total) pressure = pressure difference Fan (total) pressure = pressure difference
between fan inlet and fan dischargebetween fan inlet and fan discharge
At fan suction/inlet, SP = negative (c.f. At fan suction/inlet, SP = negative (c.f.
atmospheric); at discharge, SP = positiveatmospheric); at discharge, SP = positive
Fan-duct SystemsFan-duct Systems
Pressure characteristicsPressure characteristics
SP and VP are mutually convertible (↑or↓)SP and VP are mutually convertible (↑or↓)
TP always decreases in the direction of TP always decreases in the direction of
airflowairflow
For constant-area straight duct sectionsFor constant-area straight duct sections
•Velocity and VP are constantVelocity and VP are constant
•TP change = SP changeTP change = SP change
When duct cross-sectional areas are reducedWhen duct cross-sectional areas are reduced
•Velocity and VP increaseVelocity and VP increase
•Absolute value of both TP and SP decreaseAbsolute value of both TP and SP decrease
•Dynamic losses from elbow, dampers, etc.Dynamic losses from elbow, dampers, etc.
Pressure characteristicsPressure characteristics
SP and VP are mutually convertible (↑or↓)SP and VP are mutually convertible (↑or↓)
TP always decreases in the direction of TP always decreases in the direction of
airflowairflow
For constant-area straight duct sectionsFor constant-area straight duct sections
•Velocity and VP are constantVelocity and VP are constant
•TP change = SP changeTP change = SP change
When duct cross-sectional areas are reducedWhen duct cross-sectional areas are reduced
•Velocity and VP increaseVelocity and VP increase
•Absolute value of both TP and SP decreaseAbsolute value of both TP and SP decrease
•Dynamic losses from elbow, dampers, etc.Dynamic losses from elbow, dampers, etc.
Fan-duct SystemsFan-duct Systems
Fan-duct systemsFan-duct systems
Flow resistance Flow resistance RR, pressure drop , pressure drop ΔΔpp and and
volume flow rate volume flow rate VV
Duct sections in series:Duct sections in series:
Duct sections in parallel:Duct sections in parallel:
2
VRp
×=D
o
ns
RRRR +++=
21
np
RRRR
1111
21
+++=
Fan-duct systemsFan-duct systems
Flow resistance Flow resistance RR, pressure drop , pressure drop ΔΔpp and and
volume flow rate volume flow rate VV
Duct sections in series:Duct sections in series:
Duct sections in parallel:Duct sections in parallel:
2
VRp
×=D
o
ns
RRRR +++=
21
np
RRRR
1111
21
+++=
Fan-duct SystemsFan-duct Systems
Fan-duct systemsFan-duct systems
TerminologyTerminology
•Primary air (conditioned air or makeup air)Primary air (conditioned air or makeup air)
•Secondary air (induced space air, plenum air, or Secondary air (induced space air, plenum air, or
recirculating air)recirculating air)
•Transfer air (indoor air that moves from an Transfer air (indoor air that moves from an
adjacent area)adjacent area)
System curve: volume flow vs pressure lossSystem curve: volume flow vs pressure loss
System operating pointSystem operating point
Fan-duct systemsFan-duct systems
TerminologyTerminology
•Primary air (conditioned air or makeup air)Primary air (conditioned air or makeup air)
•Secondary air (induced space air, plenum air, or Secondary air (induced space air, plenum air, or
recirculating air)recirculating air)
•Transfer air (indoor air that moves from an Transfer air (indoor air that moves from an
adjacent area)adjacent area)
System curve: volume flow vs pressure lossSystem curve: volume flow vs pressure loss
System operating pointSystem operating point
Fan-duct SystemsFan-duct Systems
System effect System effect ΔΔpp
tsts
Its additional total pressure loss caused by Its additional total pressure loss caused by
uneven or non-uniform velocity profile at the uneven or non-uniform velocity profile at the
fan inlet, or at duct fittings after fan outletfan inlet, or at duct fittings after fan outlet
Due to the actual inlet and outlet connections Due to the actual inlet and outlet connections
as compared with the total pressure loss of the as compared with the total pressure loss of the
fan test unit during laboratory ratingsfan test unit during laboratory ratings
Inlet Outlet
System effect System effect ΔΔpp
tsts
Its additional total pressure loss caused by Its additional total pressure loss caused by
uneven or non-uniform velocity profile at the uneven or non-uniform velocity profile at the
fan inlet, or at duct fittings after fan outletfan inlet, or at duct fittings after fan outlet
Due to the actual inlet and outlet connections Due to the actual inlet and outlet connections
as compared with the total pressure loss of the as compared with the total pressure loss of the
fan test unit during laboratory ratingsfan test unit during laboratory ratings
Inlet Outlet
Fan system operating point & system effect
Fan-duct SystemsFan-duct Systems
Modulation of air systemsModulation of air systems
Constant volume systemConstant volume system
•Volume flow rate remains constantVolume flow rate remains constant
•Supply temperature is raised during part loadSupply temperature is raised during part load
Variable-air-volume (VAV) systemVariable-air-volume (VAV) system
•Volume flow rate is reduced to match part load Volume flow rate is reduced to match part load
operationoperation
•Modulation curveModulation curve
Modulation of air systemsModulation of air systems
Constant volume systemConstant volume system
•Volume flow rate remains constantVolume flow rate remains constant
•Supply temperature is raised during part loadSupply temperature is raised during part load
Variable-air-volume (VAV) systemVariable-air-volume (VAV) system
•Volume flow rate is reduced to match part load Volume flow rate is reduced to match part load
operationoperation
•Modulation curveModulation curve
Fan modulation curve
Fan-duct SystemsFan-duct Systems
Fan modulation methodsFan modulation methods
DamperDamper (vary the opening of the air flow (vary the opening of the air flow
passage)passage)
•Waste energyWaste energy
Inlet vanesInlet vanes (opening & angle of inlet vanes) (opening & angle of inlet vanes)
•Low cost; less efficient than following typesLow cost; less efficient than following types
Inlet coneInlet cone (peripheral area of fan impeller) (peripheral area of fan impeller)
•Inexpensive; for backward curved centrifugal fanInexpensive; for backward curved centrifugal fan
Blade pitchBlade pitch (blade angle of axial fan) (blade angle of axial fan)
Fan speedFan speed (using adjustable frequency (using adjustable frequency
drives)drives)
•Most energy-efficient; but usually cost moreMost energy-efficient; but usually cost more
Fan modulation methodsFan modulation methods
DamperDamper (vary the opening of the air flow (vary the opening of the air flow
passage)passage)
•Waste energyWaste energy
Inlet vanesInlet vanes (opening & angle of inlet vanes) (opening & angle of inlet vanes)
•Low cost; less efficient than following typesLow cost; less efficient than following types
Inlet coneInlet cone (peripheral area of fan impeller) (peripheral area of fan impeller)
•Inexpensive; for backward curved centrifugal fanInexpensive; for backward curved centrifugal fan
Blade pitchBlade pitch (blade angle of axial fan) (blade angle of axial fan)
Fan speedFan speed (using adjustable frequency (using adjustable frequency
drives)drives)
•Most energy-efficient; but usually cost moreMost energy-efficient; but usually cost more
Damper, inlet vanes & fan speed modulation
Inlet vane
modulation
modulation
Fan speed
modulation using
AC inverter
modulation using
AC inverter
Fan-duct SystemsFan-duct Systems
Fan surgeFan surge (in centrifugal fan) (in centrifugal fan)
Occurs when air volume flow is not sufficient to Occurs when air volume flow is not sufficient to
sustain the static pressure difference between sustain the static pressure difference between
discharge & suctiondischarge & suction
•Discharge pressure is reduced momentarilyDischarge pressure is reduced momentarily
•Volume flow & pressure fluctuationsVolume flow & pressure fluctuations
•Create noise & vibrationCreate noise & vibration
Surge region: shall avoid operation in itSurge region: shall avoid operation in it
Fan stallFan stall (in axial fans) (in axial fans)
When smooth air flow suddenly breaks & pressure When smooth air flow suddenly breaks & pressure
difference across the blades decreasesdifference across the blades decreases
The fan loses pressure capability drasticallyThe fan loses pressure capability drastically
Fan surgeFan surge (in centrifugal fan) (in centrifugal fan)
Occurs when air volume flow is not sufficient to Occurs when air volume flow is not sufficient to
sustain the static pressure difference between sustain the static pressure difference between
discharge & suctiondischarge & suction
•Discharge pressure is reduced momentarilyDischarge pressure is reduced momentarily
•Volume flow & pressure fluctuationsVolume flow & pressure fluctuations
•Create noise & vibrationCreate noise & vibration
Surge region: shall avoid operation in itSurge region: shall avoid operation in it
Fan stallFan stall (in axial fans) (in axial fans)
When smooth air flow suddenly breaks & pressure When smooth air flow suddenly breaks & pressure
difference across the blades decreasesdifference across the blades decreases
The fan loses pressure capability drasticallyThe fan loses pressure capability drastically
Stall and stall region of an axial fan
Fan-duct SystemsFan-duct Systems
Fan selectionFan selection
Select fan type + determine fan sizeSelect fan type + determine fan size
Important factors:Important factors:
•Pressure-volume flow operating characteristicsPressure-volume flow operating characteristics
•Fan capacity modulationFan capacity modulation
•Fan efficiencyFan efficiency
•Sound power levelSound power level
•Airflow directionAirflow direction
•Initial costInitial cost
Fan selectionFan selection
Select fan type + determine fan sizeSelect fan type + determine fan size
Important factors:Important factors:
•Pressure-volume flow operating characteristicsPressure-volume flow operating characteristics
•Fan capacity modulationFan capacity modulation
•Fan efficiencyFan efficiency
•Sound power levelSound power level
•Airflow directionAirflow direction
•Initial costInitial cost
Duct ConstructionDuct Construction
Types of air ductTypes of air duct
Supply air ductSupply air duct
Return air ductReturn air duct
Outdoor air ductOutdoor air duct
Exhaust airExhaust air
Duct sectionsDuct sections
Header or main duct (trunk)Header or main duct (trunk)
Branch duct or runoutBranch duct or runout
Types of air ductTypes of air duct
Supply air ductSupply air duct
Return air ductReturn air duct
Outdoor air ductOutdoor air duct
Exhaust airExhaust air
Duct sectionsDuct sections
Header or main duct (trunk)Header or main duct (trunk)
Branch duct or runoutBranch duct or runout
Duct ConstructionDuct Construction
Duct systemsDuct systems
Max. pressure difference (between air inside Max. pressure difference (between air inside
the duct and the ambient air)the duct and the ambient air)
•125, 250, 500, 750, 1000, 1500, 2500 Pa125, 250, 500, 750, 1000, 1500, 2500 Pa
Commercial buildingsCommercial buildings
•Low-pressure duct system: ≤ 500 Pa, max 12 m/sLow-pressure duct system: ≤ 500 Pa, max 12 m/s
•Medium-pressure system: 500-1500 Pa, max 17.5 Medium-pressure system: 500-1500 Pa, max 17.5
m/sm/s
Residential buildings: 125 Pa or 250 PaResidential buildings: 125 Pa or 250 Pa
Industrial duct system: Industrial duct system: ΔΔP can be higherP can be higher
Duct systemsDuct systems
Max. pressure difference (between air inside Max. pressure difference (between air inside
the duct and the ambient air)the duct and the ambient air)
•125, 250, 500, 750, 1000, 1500, 2500 Pa125, 250, 500, 750, 1000, 1500, 2500 Pa
Commercial buildingsCommercial buildings
•Low-pressure duct system: ≤ 500 Pa, max 12 m/sLow-pressure duct system: ≤ 500 Pa, max 12 m/s
•Medium-pressure system: 500-1500 Pa, max 17.5 Medium-pressure system: 500-1500 Pa, max 17.5
m/sm/s
Residential buildings: 125 Pa or 250 PaResidential buildings: 125 Pa or 250 Pa
Industrial duct system: Industrial duct system: ΔΔP can be higherP can be higher
Duct ConstructionDuct Construction
Duct material: e.g. UL (Underwriters’ Duct material: e.g. UL (Underwriters’
Laboratory) standardLaboratory) standard
Class 0: zero flame spread, zero smoke Class 0: zero flame spread, zero smoke
developeddeveloped
•Iron, galvanized steel, aluminum, concrete, Iron, galvanized steel, aluminum, concrete,
masonry, clay tilemasonry, clay tile
Class 1: flame spread ≤ 25, smoke Class 1: flame spread ≤ 25, smoke
developed ≤ 50developed ≤ 50
•Fiberglass, many flexible ductsFiberglass, many flexible ducts
Class 2: flame spread ≤ 50, smoke Class 2: flame spread ≤ 50, smoke
developed ≤ 100developed ≤ 100
Duct material: e.g. UL (Underwriters’ Duct material: e.g. UL (Underwriters’
Laboratory) standardLaboratory) standard
Class 0: zero flame spread, zero smoke Class 0: zero flame spread, zero smoke
developeddeveloped
•Iron, galvanized steel, aluminum, concrete, Iron, galvanized steel, aluminum, concrete,
masonry, clay tilemasonry, clay tile
Class 1: flame spread ≤ 25, smoke Class 1: flame spread ≤ 25, smoke
developed ≤ 50developed ≤ 50
•Fiberglass, many flexible ductsFiberglass, many flexible ducts
Class 2: flame spread ≤ 50, smoke Class 2: flame spread ≤ 50, smoke
developed ≤ 100developed ≤ 100
Duct ConstructionDuct Construction
Shapes of air ductShapes of air duct
RectangularRectangular
•More easily fabricated on site, air leakageMore easily fabricated on site, air leakage
RoundRound
•Less fluid resistance, better rigidity/strengthLess fluid resistance, better rigidity/strength
Flat ovalFlat oval
FlexibleFlexible
•Multiple-ply polyester film w/ metal wire or stripsMultiple-ply polyester film w/ metal wire or strips
SMACNA (Sheet Metal and Air SMACNA (Sheet Metal and Air
Conditioning Contractors’ National Conditioning Contractors’ National
Association) standardsAssociation) standards
Shapes of air ductShapes of air duct
RectangularRectangular
•More easily fabricated on site, air leakageMore easily fabricated on site, air leakage
RoundRound
•Less fluid resistance, better rigidity/strengthLess fluid resistance, better rigidity/strength
Flat ovalFlat oval
FlexibleFlexible
•Multiple-ply polyester film w/ metal wire or stripsMultiple-ply polyester film w/ metal wire or strips
SMACNA (Sheet Metal and Air SMACNA (Sheet Metal and Air
Conditioning Contractors’ National Conditioning Contractors’ National
Association) standardsAssociation) standards
Rectangular duct Round duct w/ spiral seam
Flat oval duct Flexible duct
(Source: Wang, S. K., 2001. Handbook of Air Conditioning and Refrigeration)
Flat oval duct Flexible duct
(Source: Wang, S. K., 2001. Handbook of Air Conditioning and Refrigeration)
Transverse joint reinforcement
(Source: Wang, S. K., 2001. Handbook of Air Conditioning and Refrigeration)
(Source: Wang, S. K., 2001. Handbook of Air Conditioning and Refrigeration)
Duct ConstructionDuct Construction
Duct specificationDuct specification
Sheet gauge and thickness of duct materialSheet gauge and thickness of duct material
Traverse joints & longitudinal seam Traverse joints & longitudinal seam
reinforcementsreinforcements
Duct hangers & their spacingDuct hangers & their spacing
Tapes & adhesive closuresTapes & adhesive closures
Fire spread and smoke developedFire spread and smoke developed
Site-fabricated or factory-/pre-fabricatedSite-fabricated or factory-/pre-fabricated
Duct specificationDuct specification
Sheet gauge and thickness of duct materialSheet gauge and thickness of duct material
Traverse joints & longitudinal seam Traverse joints & longitudinal seam
reinforcementsreinforcements
Duct hangers & their spacingDuct hangers & their spacing
Tapes & adhesive closuresTapes & adhesive closures
Fire spread and smoke developedFire spread and smoke developed
Site-fabricated or factory-/pre-fabricatedSite-fabricated or factory-/pre-fabricated
Duct ConstructionDuct Construction
Duct heat gain or lossDuct heat gain or loss
Temperature rise or dropTemperature rise or drop
Duct insulation (mounted or inner-lined)Duct insulation (mounted or inner-lined)
•Reduce heat gain/loss, prevent condensation, Reduce heat gain/loss, prevent condensation,
sound attentuationsound attentuation
•Minimum & recommended thicknessMinimum & recommended thickness
See ASHRAE standard or local codesSee ASHRAE standard or local codes
Temperature rise curvesTemperature rise curves
•Depends on air velocity, duct dimensions & Depends on air velocity, duct dimensions &
insulationinsulation
Duct heat gain or lossDuct heat gain or loss
Temperature rise or dropTemperature rise or drop
Duct insulation (mounted or inner-lined)Duct insulation (mounted or inner-lined)
•Reduce heat gain/loss, prevent condensation, Reduce heat gain/loss, prevent condensation,
sound attentuationsound attentuation
•Minimum & recommended thicknessMinimum & recommended thickness
See ASHRAE standard or local codesSee ASHRAE standard or local codes
Temperature rise curvesTemperature rise curves
•Depends on air velocity, duct dimensions & Depends on air velocity, duct dimensions &
insulationinsulation
Temperature rise from duct heat gain
(Source: Wang, S. K., 2001. Handbook of Air Conditioning and Refrigeration)
(Source: Wang, S. K., 2001. Handbook of Air Conditioning and Refrigeration)
Duct ConstructionDuct Construction
Frictional lossesFrictional losses
Darcey-Weisbach EquationDarcey-Weisbach Equation
•HH
ff = friction head loss, or = friction head loss, or ΔΔpp
ff = pressure loss = pressure loss
•ff = friction factor (dimensionless) = friction factor (dimensionless)
•LL = length of duct or pipe (m) = length of duct or pipe (m)
•DD = diameter of duct or pipe (m) = diameter of duct or pipe (m)
•vv = mean air velocity in duct (m/s) = mean air velocity in duct (m/s)
Frictional lossesFrictional losses
Darcey-Weisbach EquationDarcey-Weisbach Equation
•HH
ff = friction head loss, or = friction head loss, or ΔΔpp
ff = pressure loss = pressure loss
•ff = friction factor (dimensionless) = friction factor (dimensionless)
•LL = length of duct or pipe (m) = length of duct or pipe (m)
•DD = diameter of duct or pipe (m) = diameter of duct or pipe (m)
•vv = mean air velocity in duct (m/s) = mean air velocity in duct (m/s)
Mode of airflow when air passes over and around
surface protuberances of the duct wall
δ >ε
δ <ε
surface protuberances of the duct wall
δ >ε
δ <ε
Duct ConstructionDuct Construction
Duct friction chartDuct friction chart
Colebrook formulaColebrook formula
Roughness & temperature correctionsRoughness & temperature corrections
ΔΔpp
ff = = KK
srsr KK
TT KK
elelΔΔpp
f,cf,c
•KK
sr sr = correction factor for surface roughness= correction factor for surface roughness
•KK
T T = correction factor for air temperature= correction factor for air temperature
•KK
el el = correction factor for elevation= correction factor for elevation
Duct friction chartDuct friction chart
Colebrook formulaColebrook formula
Roughness & temperature correctionsRoughness & temperature corrections
ΔΔpp
ff = = KK
srsr KK
TT KK
elelΔΔpp
f,cf,c
•KK
sr sr = correction factor for surface roughness= correction factor for surface roughness
•KK
T T = correction factor for air temperature= correction factor for air temperature
•KK
el el = correction factor for elevation= correction factor for elevation
Friction chart for round duct
Duct ConstructionDuct Construction
Circular equivalentCircular equivalent
Hydraulic diameter, Hydraulic diameter, DD
hh = 4 = 4 AA / / PP
•AA = area (mm = area (mm
22
); ); PP = perimeter (mm) = perimeter (mm)
Rectangular duct:Rectangular duct:
Flat oval duct:Flat oval duct:
Circular equivalentCircular equivalent
Hydraulic diameter, Hydraulic diameter, DD
hh = 4 = 4 AA / / PP
•AA = area (mm = area (mm
22
); ); PP = perimeter (mm) = perimeter (mm)
Rectangular duct:Rectangular duct:
Flat oval duct:Flat oval duct:
Duct ConstructionDuct Construction
Dynamic lossesDynamic losses
Result from flow disturbances caused by duct-Result from flow disturbances caused by duct-
mounted equipment and fittingsmounted equipment and fittings
•Change airflow path’s direction and/or areaChange airflow path’s direction and/or area
•Flow separation & eddies/disturbancesFlow separation & eddies/disturbances
In dynamic similarity (same Reynolds number In dynamic similarity (same Reynolds number
& geometrically similar duct fittings), dynamic & geometrically similar duct fittings), dynamic
loss is proportional to their velocity pressureloss is proportional to their velocity pressure
Dynamic lossesDynamic losses
Result from flow disturbances caused by duct-Result from flow disturbances caused by duct-
mounted equipment and fittingsmounted equipment and fittings
•Change airflow path’s direction and/or areaChange airflow path’s direction and/or area
•Flow separation & eddies/disturbancesFlow separation & eddies/disturbances
In dynamic similarity (same Reynolds number In dynamic similarity (same Reynolds number
& geometrically similar duct fittings), dynamic & geometrically similar duct fittings), dynamic
loss is proportional to their velocity pressureloss is proportional to their velocity pressure
Duct ConstructionDuct Construction
Local or dynamic loss coefficientLocal or dynamic loss coefficient
Ratio of total pressure loss to velocity Ratio of total pressure loss to velocity
pressurepressure
Local or dynamic loss coefficientLocal or dynamic loss coefficient
Ratio of total pressure loss to velocity Ratio of total pressure loss to velocity
pressurepressure
Duct ConstructionDuct Construction
Duct fittingsDuct fittings
ElbowsElbows
Converging or diverging tees and wyesConverging or diverging tees and wyes
Entrances and exitsEntrances and exits
Enlargements and contractionsEnlargements and contractions
Means to reduce dynamic lossesMeans to reduce dynamic losses
Turning angle, splitter vanesTurning angle, splitter vanes
ASHRAE duct fitting databaseASHRAE duct fitting database
Fitting loss coefficientsFitting loss coefficients
Duct fittingsDuct fittings
ElbowsElbows
Converging or diverging tees and wyesConverging or diverging tees and wyes
Entrances and exitsEntrances and exits
Enlargements and contractionsEnlargements and contractions
Means to reduce dynamic lossesMeans to reduce dynamic losses
Turning angle, splitter vanesTurning angle, splitter vanes
ASHRAE duct fitting databaseASHRAE duct fitting database
Fitting loss coefficientsFitting loss coefficients
Region of eddies and
turbulences in a round elbow
5-piece 90
o
round elbow
turbulences in a round elbow
5-piece 90
o
round elbow
Rectangular elbow, smooth radius, 2 splitter vanes
Mitered elbow and its secondary flow
Mitered elbow and its secondary flow
Airflow through a
rectangular converging
or diverging wye
rectangular converging
or diverging wye
Entrance Exit
Abrupt enlargement Sudden contraction
Duct ConstructionDuct Construction
Flow resistance, Flow resistance, RR
Total pressure loss Total pressure loss ΔΔpp
tt at a specific volume flow at a specific volume flow
rate rate VV
Flow resistance in series:Flow resistance in series:
Flow resistance in parallel:Flow resistance in parallel:
2
VRp
t
×=D
ns RRRR +++=
21
np
RRRR
1111
21
+++=
Flow resistance, Flow resistance, RR
Total pressure loss Total pressure loss ΔΔpp
tt at a specific volume flow at a specific volume flow
rate rate VV
Flow resistance in series:Flow resistance in series:
Flow resistance in parallel:Flow resistance in parallel:
2
VRp
t
×=D
ns RRRR +++=
21
np
RRRR
1111
21
+++=
Total pressure loss and flow resistance of a round duct section
Flow resistance in series
Flow resistance in parallel
Flow resistance in parallel
Flow resistance for a Y connection
Air Duct DesignAir Duct Design
Optimal air duct designOptimal air duct design
Optimal duct system layout, space availableOptimal duct system layout, space available
Satisfactory system balanceSatisfactory system balance
Acceptable sound levelAcceptable sound level
Optimum energy loss and initial costOptimum energy loss and initial cost
Install only necessary balancing devices Install only necessary balancing devices
(dampers)(dampers)
Fire codes, duct construction & insulationFire codes, duct construction & insulation
Require comprehensive analysis & care for Require comprehensive analysis & care for
different transport functionsdifferent transport functions
Optimal air duct designOptimal air duct design
Optimal duct system layout, space availableOptimal duct system layout, space available
Satisfactory system balanceSatisfactory system balance
Acceptable sound levelAcceptable sound level
Optimum energy loss and initial costOptimum energy loss and initial cost
Install only necessary balancing devices Install only necessary balancing devices
(dampers)(dampers)
Fire codes, duct construction & insulationFire codes, duct construction & insulation
Require comprehensive analysis & care for Require comprehensive analysis & care for
different transport functionsdifferent transport functions
Flow characteristics of a supply duct system
Air Duct DesignAir Duct Design
Design velocityDesign velocity
Constraints: space available, beam depthConstraints: space available, beam depth
Typical guidelines:Typical guidelines:
•Main ducts: air flow usually ≤ 15 m/s; air flow noise Main ducts: air flow usually ≤ 15 m/s; air flow noise
must be checkedmust be checked
•With more demanding noise criteria (e.g. hotels), With more demanding noise criteria (e.g. hotels),
max. air velocity: main duct ≤ 10-12.5 m/s, return max. air velocity: main duct ≤ 10-12.5 m/s, return
main duct ≤ 8 m/s, branch ducts ≤ 6 m/smain duct ≤ 8 m/s, branch ducts ≤ 6 m/s
Face velocities for air-handling system Face velocities for air-handling system
componentscomponents
Design velocityDesign velocity
Constraints: space available, beam depthConstraints: space available, beam depth
Typical guidelines:Typical guidelines:
•Main ducts: air flow usually ≤ 15 m/s; air flow noise Main ducts: air flow usually ≤ 15 m/s; air flow noise
must be checkedmust be checked
•With more demanding noise criteria (e.g. hotels), With more demanding noise criteria (e.g. hotels),
max. air velocity: main duct ≤ 10-12.5 m/s, return max. air velocity: main duct ≤ 10-12.5 m/s, return
main duct ≤ 8 m/s, branch ducts ≤ 6 m/smain duct ≤ 8 m/s, branch ducts ≤ 6 m/s
Face velocities for air-handling system Face velocities for air-handling system
componentscomponents
Air Duct DesignAir Duct Design
Reduce dynamic losses of the critical pathReduce dynamic losses of the critical path
Maintain optimum air velocity through duct Maintain optimum air velocity through duct
fittingsfittings
Emphasize reduction of dynamic losses Emphasize reduction of dynamic losses
nearer to the fan outlet or inlet (high air nearer to the fan outlet or inlet (high air
velocity)velocity)
Proper use of splitter vanesProper use of splitter vanes
Set 2 duct fittings as far apart as possibleSet 2 duct fittings as far apart as possible
Air duct leakageAir duct leakage
Duct leakage classificationDuct leakage classification
•AISI, SMACNA, ASHRAE standards AISI, SMACNA, ASHRAE standards
Reduce dynamic losses of the critical pathReduce dynamic losses of the critical path
Maintain optimum air velocity through duct Maintain optimum air velocity through duct
fittingsfittings
Emphasize reduction of dynamic losses Emphasize reduction of dynamic losses
nearer to the fan outlet or inlet (high air nearer to the fan outlet or inlet (high air
velocity)velocity)
Proper use of splitter vanesProper use of splitter vanes
Set 2 duct fittings as far apart as possibleSet 2 duct fittings as far apart as possible
Air duct leakageAir duct leakage
Duct leakage classificationDuct leakage classification
•AISI, SMACNA, ASHRAE standards AISI, SMACNA, ASHRAE standards
Air Duct DesignAir Duct Design
Fire protectionFire protection
Duct material selectionDuct material selection
Vertical ducts (using masonry, concrete or Vertical ducts (using masonry, concrete or
clay)clay)
When ducts pass through floors & wallsWhen ducts pass through floors & walls
Use of fire dampersUse of fire dampers
Filling the gaps between ducts & bldg Filling the gaps between ducts & bldg
structurestructure
Duct systems for industrial applicationsDuct systems for industrial applications
Any other fire precautions?Any other fire precautions?
Fire protectionFire protection
Duct material selectionDuct material selection
Vertical ducts (using masonry, concrete or Vertical ducts (using masonry, concrete or
clay)clay)
When ducts pass through floors & wallsWhen ducts pass through floors & walls
Use of fire dampersUse of fire dampers
Filling the gaps between ducts & bldg Filling the gaps between ducts & bldg
structurestructure
Duct systems for industrial applicationsDuct systems for industrial applications
Any other fire precautions?Any other fire precautions?
Air Duct DesignAir Duct Design
Design procedure (computer-aided or manual)Design procedure (computer-aided or manual)
Verify local codes & material availabilityVerify local codes & material availability
Preliminary duct layoutPreliminary duct layout
Divide into consecutive duct sectionsDivide into consecutive duct sections
Minimise local loss coefficients of duct fittingsMinimise local loss coefficients of duct fittings
Select duct sizing methodsSelect duct sizing methods
Critical total pressure loss of tentative critical pathCritical total pressure loss of tentative critical path
Size branch ducts & balance total pressure at Size branch ducts & balance total pressure at
junctionsjunctions
Adjust supply flow rates according to duct heat gainAdjust supply flow rates according to duct heat gain
Resize duct sections, recalculate & balance parallel Resize duct sections, recalculate & balance parallel
pathspaths
Check sound level & add necessary attenuationCheck sound level & add necessary attenuation
Design procedure (computer-aided or manual)Design procedure (computer-aided or manual)
Verify local codes & material availabilityVerify local codes & material availability
Preliminary duct layoutPreliminary duct layout
Divide into consecutive duct sectionsDivide into consecutive duct sections
Minimise local loss coefficients of duct fittingsMinimise local loss coefficients of duct fittings
Select duct sizing methodsSelect duct sizing methods
Critical total pressure loss of tentative critical pathCritical total pressure loss of tentative critical path
Size branch ducts & balance total pressure at Size branch ducts & balance total pressure at
junctionsjunctions
Adjust supply flow rates according to duct heat gainAdjust supply flow rates according to duct heat gain
Resize duct sections, recalculate & balance parallel Resize duct sections, recalculate & balance parallel
pathspaths
Check sound level & add necessary attenuationCheck sound level & add necessary attenuation
Air Duct DesignAir Duct Design
Duct layoutDuct layout
Symmetric layout is easier to balanceSymmetric layout is easier to balance
•Smaller main duct & shorter design pathSmaller main duct & shorter design path
For VAV systems, duct looping allows feed For VAV systems, duct looping allows feed
from opposite directionfrom opposite direction
•Optimise transporting capacity (balance points Optimise transporting capacity (balance points
often follow the sun’s position)often follow the sun’s position)
•Result in smaller main ductResult in smaller main duct
Compare alternative layouts & reduce fittingsCompare alternative layouts & reduce fittings
For exposed ducts, appearance & integration For exposed ducts, appearance & integration
with the structure is importantwith the structure is important
Duct layoutDuct layout
Symmetric layout is easier to balanceSymmetric layout is easier to balance
•Smaller main duct & shorter design pathSmaller main duct & shorter design path
For VAV systems, duct looping allows feed For VAV systems, duct looping allows feed
from opposite directionfrom opposite direction
•Optimise transporting capacity (balance points Optimise transporting capacity (balance points
often follow the sun’s position)often follow the sun’s position)
•Result in smaller main ductResult in smaller main duct
Compare alternative layouts & reduce fittingsCompare alternative layouts & reduce fittings
For exposed ducts, appearance & integration For exposed ducts, appearance & integration
with the structure is importantwith the structure is important
Typical supply duct system with symmetric layout & looping
Air Duct DesignAir Duct Design
Duct linerDuct liner
Lined internally on inner surface of duct wallLined internally on inner surface of duct wall
Mainly used for noise attenuation & insulationMainly used for noise attenuation & insulation
Fiberglass blanket or boardsFiberglass blanket or boards
Duct cleaningDuct cleaning
Prevent accumulation of dirt & debrisPrevent accumulation of dirt & debris
Agitation device to loosen the dirt & debrisAgitation device to loosen the dirt & debris
Duct vacuum to extract loosened debrisDuct vacuum to extract loosened debris
Sealing of access openingsSealing of access openings
Duct linerDuct liner
Lined internally on inner surface of duct wallLined internally on inner surface of duct wall
Mainly used for noise attenuation & insulationMainly used for noise attenuation & insulation
Fiberglass blanket or boardsFiberglass blanket or boards
Duct cleaningDuct cleaning
Prevent accumulation of dirt & debrisPrevent accumulation of dirt & debris
Agitation device to loosen the dirt & debrisAgitation device to loosen the dirt & debris
Duct vacuum to extract loosened debrisDuct vacuum to extract loosened debris
Sealing of access openingsSealing of access openings
Duct breakout noise
HVAC Piping SystemHVAC Piping System
HVAC Instrumentation and ControlHVAC Instrumentation and Control
HVAC System CommissioningHVAC System Commissioning
The key elements of commissioning include:The key elements of commissioning include:
Installation checks.Installation checks. Check installed equipment to ensure that all associated Check installed equipment to ensure that all associated
components and accessories are in place.components and accessories are in place.
Operational checks.Operational checks. Verify and document that systems are performing as expected, Verify and document that systems are performing as expected,
and that all sensors and other system control devices are properly calibrated.and that all sensors and other system control devices are properly calibrated.
Documentation.Documentation. Confirm that all required documentation has been provided, such as Confirm that all required documentation has been provided, such as
a statement of the design intent and operating protocols for all building systems. a statement of the design intent and operating protocols for all building systems.
O&M manuals and training.O&M manuals and training. Prepare comprehensive operation and maintenance Prepare comprehensive operation and maintenance
(O&M) manuals, and provide training for rig operations staff.(O&M) manuals, and provide training for rig operations staff.
Ongoing monitoring.Ongoing monitoring. Conduct periodic monitoring after the school is occupied to Conduct periodic monitoring after the school is occupied to
ensure that equipment and systems continue to perform according to design intent. ensure that equipment and systems continue to perform according to design intent.
Correctly implemented, commissioning is extremely cost-effective, and should Correctly implemented, commissioning is extremely cost-effective, and should
improve the delivery process, increase systems reliability, improve energy improve the delivery process, increase systems reliability, improve energy
performance, ensure good indoor environmental quality, and improve operation and performance, ensure good indoor environmental quality, and improve operation and
maintenance of the facility.maintenance of the facility.
The key elements of commissioning include:The key elements of commissioning include:
Installation checks.Installation checks. Check installed equipment to ensure that all associated Check installed equipment to ensure that all associated
components and accessories are in place.components and accessories are in place.
Operational checks.Operational checks. Verify and document that systems are performing as expected, Verify and document that systems are performing as expected,
and that all sensors and other system control devices are properly calibrated.and that all sensors and other system control devices are properly calibrated.
Documentation.Documentation. Confirm that all required documentation has been provided, such as Confirm that all required documentation has been provided, such as
a statement of the design intent and operating protocols for all building systems. a statement of the design intent and operating protocols for all building systems.
O&M manuals and training.O&M manuals and training. Prepare comprehensive operation and maintenance Prepare comprehensive operation and maintenance
(O&M) manuals, and provide training for rig operations staff.(O&M) manuals, and provide training for rig operations staff.
Ongoing monitoring.Ongoing monitoring. Conduct periodic monitoring after the school is occupied to Conduct periodic monitoring after the school is occupied to
ensure that equipment and systems continue to perform according to design intent. ensure that equipment and systems continue to perform according to design intent.
Correctly implemented, commissioning is extremely cost-effective, and should Correctly implemented, commissioning is extremely cost-effective, and should
improve the delivery process, increase systems reliability, improve energy improve the delivery process, increase systems reliability, improve energy
performance, ensure good indoor environmental quality, and improve operation and performance, ensure good indoor environmental quality, and improve operation and
maintenance of the facility.maintenance of the facility.
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