1 A I R C O N D I T I O N I N G S Y S T E M MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008 UTM FKM FKM UNIVERSITI TEKNOLOGI MALAYSIA UNIVERSITI TEKNOLOGI MALAYSIA DR. MAZLAN ABDUL WAHID http://www.fkm.utm.my/~mazlan SAB 2032 SAB 2032 Mechanical and Electrical System Mechanical and Electrical System A I R C O N D I T I O N I N G S Y S T E M MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008 UTM FKM FKM UNIVERSITI TEKNOLOGI MALAYSIA UNIVERSITI TEKNOLOGI MALAYSIA AIR SIDE SYSTEM
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DR. MAZLAN ABDUL WAHIDhttp://www.fkm.utm.my/~mazlan
SAB 2032SAB 2032
Mechanical and Electrical SystemMechanical and Electrical System
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AIR SIDE SYSTEM
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Content
� Major Components of Ventilation and Air Conditioning System
� Ventilation System Schematic
� Air Conditioning System: Air-air, Air-water, All-water system
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Split Air Conditioning (SAC) System and Central Air ConditioningSystem(CAC)
1) Split type air conditioning unit allows flexible hours operation. For example, if only a room at one floor of the whole b uilding required air conditioning, it requires the running of the chille r plant that is not energy efficient;
2) SAC does not involve chilled water pipe. It would be hazardous for CAC with flooding attributed by a leaking joint of chilled water pipe;
3) SAC allow individual control on indoor temperature comparing with the case of adopting air handling unit serving zones;
4) It would be a localized problem if only one of the SAC is found out of order. If one of the chiller out of two is found out of or der, all of the floors would suffer from a rise in temperature in a hot summer d ay;
5) SAC requires no water treatment cost as for chilled water pipes and condenser water pipes;
6) SAC requires place for accommodation of outdoor units that is always a difficulty in modern building with curtain walls on all facades;
7) CAC allows the pretreated primary air and use of thermal wheel for recovery of energy from exhaust air.
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•Major Components Ventilation of Air Conditioning Systems
•1) Louvre
•2) Duct work – rectangular, round, flat oval and flexible
•9) Air Handling Unit (AHU) and Primary Air Unit (PAU)
•10) Air filters
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LouvreLouvreLouvreLouvre fixed at wallfixed at wallfixed at wallfixed at wall
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Rectangular Ducts
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Rectangular Ducts••They could be fabricated on-site.
•The joints of rectangular ducts have a comparatively greater percentage of air leakage than factory-fabricated spiral-seamed round ducts and flat oval ducts••Unsealed rectangular ducts : air leakage from 15 to 20 percent of the supply volume flow rate. ••The ratio of the long side (length or width) to the short side (length or width) in a rectangular duct is called the aspect ratio .••To prevent vibration of the duct wall by the pulsating airflow, transverse joints and longitudinal seam reinforcements are required in ferrous metal ducts.
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Round Ducts
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Round Ducts
For a specified cross-sectional area and mean air velocity, a round duct has less fluid resistanceagainst airflow than rectangular and flat oval ducts.
Round ducts also have better rigidity and strength.
The spiral- and longitude-seamedround ducts used in commercial buildings are usually factory-fabricated to improve the quality and sealing of the ductwork.
The pressure losses can be calculatedmore precisely than for rectangular ducts, and result in a better balanced system.
Air leakage can be maintained at about 3 percent as a result of well-sealed seams and joints.
Round ducts have much smaller radiated noisebreakout from the duct than rectangular and flat oval ducts.
The main disadvantage of round ducts is the greater spacerequired under the beam for installation.
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Flat Oval Ducts
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Flat Oval Ducts
� Flat oval ducts have a cross-sectional shapebetween rectangular and round.
� They share the advantages of both the round and the rectangular duct with less large-scale air turbulenceand a small depth of spacerequired during installation.
� Flat oval ducts are quicker to install and have lower air leakagebecause of the factory fabrication.
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Flexible Ducts
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Flexible Ducts
� Flexible ducts are often usedto connect the main duct or the diffusers to the terminal box.
� Their flexibility and ease of removalallow allocation and relocation of the terminal devices.
� Flexible ducts are usually made ofmultiple-ply polyester film reinforced by a helical steel wire core or corrugated aluminum spiral strips.
� The duct is ofteninsulatedby a fiberglass blanket 25 to 50 mm thick.
� The outer surfaceof the flexible duct is usually covered with aluminum foil or other types of vapor barriers to prevent the permeation of water vapor into the insulation layer.
� The flexible duct should be as short as possible, and its length should be fully extended to minimize flow resistance.
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Duct Insulation
� Duct insulation is mounted or inner-lined to reduce heat loss and heat gainas well as to prevent the condensationon the outer surface of the duct.
� It is usually in the form of duct wrap (outer surface), duct inner liner, or fiberglass duct boards.
� Duct liner provides both thermal insulation and sound attenuation.
� The thickness of an insulation layeris based on economical analysis.
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Ventilation Fan - one
Axial Fan
� Increase of air static pressure is created by the conversion of velocity pressure to static pressure
� Direction of airflow is parallel to the axle of the fan.
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Centrifugal fan
� Increase of air static pressure is created by the conversion of velocity pressure to static pressure.
� Air is radially discharged from the impeller and turns 90° from its inlet to its outlet.
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Split Dampers.
� A split damper is also a single-blade damper.
� It is a piece of movable sheet metal
� It is usually installed at the Y connection of a rectangular duct system
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Oppose Blade Damper
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Opposed-Blade Dampers
� It is a type of multi-blades damper that is often rectangular.
� The damper blades may be made ofgalvanized steel, aluminum alloy, or stainless-steel sheets.
� Rubber or spring sealscan be provided at the fully closed position to control the air leakage rating
� The bearing used for supporting the blade axle should be made of a corrosion-resistant material such as copper alloy.
� Lever linkagesare used to open and close the damper blades.
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Silencer
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SILENCERS
� Silencer reduces the sound power levelof a fan to a required level.
� Inside the rectangular casing are a number of flat splitters, depending on the width of the silencer.
� Thesesplitters direct the airflow into small sound-attenuating passages.
� The splitter is made from an envelope containing sound-attenuating material, such as fiberglass or mineral wool, with protected non eroding facing.
� Splitters often have around instead of a flat nose, to reduce their airflow resistance.
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Grilles and Registers
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Grilles and Registers
� A grille or grill is an outlet for supply air or an inlet for return air or exhaust air.
� A register is a grille with a volume control damper (to adjust the volume flow).
� A single-deflection grille consists of a frame and one set of adjustable vanes (either vertical or horizontal vanes) to deflect the airstream.
� A double-deflection register is able to deflect the airstream both horizontally and vertically.
� Extruded aluminum vanes, steel frames, steel dampers with a baked enamel finish.
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Slot Diffuser
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Slot Diffusers
� A slot diffuser consists of a plenum box with single or multipleslots and air deflecting vanes.
� Air discharged from a slot diffuser can be projected horizontally or vertically.
� With multiple slots, air can be horizontally discharged either left or right, or a combination of both, or one slot can discharge vertically while another discharges horizontally.
� The function of the plenum box is to distribute the air more evenly at the slot.
� The plenum box is insulated internally.
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Ceiling Diffusers
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Ceiling Diffusers
� A ceiling diffuser consists of a series of concentric rings or inner cones made up of vanes arranged in fixed directions and an outer shell or frame
� Ceiling diffusers can be round, square, or rectangular.
� Square diffusers are most widely used.
� Supply air is discharged through the concentric air passages or directional passages in one, two, three, or in all directions by using different types of inner cone and vanes.
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Fan Coil Units
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Fan-Coil Units
� A fan-coil unit, is a terminal unit installed directly inside the conditioned space
� It includes
�A small motor driven centrifugal fan
�A finned coil,
�A filter,
�An outer casing, and
�Controls.
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Air Handling Unit
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Primary Air Unit
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Roof Top Air Handling Unit
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Air Handling Unit(AHU)/ Primary Air Unit(PAU )
Casings
(1) Double-wall sheet-metal casing in which the insulation material is sandwiched between two sheet-metal panels
(2) Single sheet-metal panel with inner insulation layer and perforated metal liners
� Problem of exposing insulating materials (e.g. glass fibers) :wet and collect dirt, microbial growth and erosion over time.
� Advantage of exposing insulating materials : attenuate the fan noise
18
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
AHU/PAU Fan
� A double-inlet airfoil, backward-inclined centrifugal fan
� Centrifugal fan has higher fan total pressure for its higher efficiency and lower noise.
AHU/PAU Coils
� Coils : water cooling coils, water heating coils, electricheating coils, and etc
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
AHU/PAU-Filters
� Air filtration is an important component to achieve an acceptable indoor air quality.
� Low-efficiency filters of the panel type as pre-filter
� Medium- and high-efficiency bag type for filtering the air
� Carbon-activated gaseous absorption filters for removal of objectionable odors
AHU- Outdoor Air and Mixing Plenum
An outdoor air intake and mixing plenum includes an outdoor air intake, a mixing plenum and connection with return air duct.
19
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Weight arrestance
Dust Spot Di-OtylPhthalate DOP
Particle size of test dust
Large particles in atmospheric dust
Atmospheric dust 0.3μmparticles
Means to determine dust concentration
Precision Balance Change in light transmission
Particle count
Application Low efficiency filter
Medium efficiency filter
High efficiency filter
Test Method for Filters with different efficiency
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Low Efficiency Filter
�Dust spot efficiency lower than 30%�Panel type�Dimension 500mm x 500mm
�Filter media�Corrugated metal wire mesh �Dry and reusable-nylon�Dry and disposable – Glass fibre mats
20
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Medium Efficiency Filter
�Filter efficiency between 30% to 95%�Extended surfaces such as pleated mats or bags are used to
�Increase surface area of the filter media �Increase air velocity flowing through the filter me dia
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
High Efficiency Particulate Air FilterPrinciple of operation � It remove dust particle by filtration of the passing air;
Construction:� The filter media is glass fibre of submicrometer diameter that is
formed into pleated paper mats (dry and disposable).� The performance of filter media is measured by alpha value which
is a function of penetration in % and pressure drop (mm).� Typical size of filter is 600mm x 600mm x 300mm� Surface filter media area may be 50 times of the face area
21
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
High Efficiency Particulate Air Filter (Cont’d)
Application: meet the requirement of di-octyl phthalate (DOP) 99.97% efficiency for dust particle ≧0.3μm� Clean room� Clean space for microelectronic industry� Pharmaceutical industry� Precision manufacturing industry� Operating theatre in hospital
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Electronic air cleaner
Principles of operation� When traveling in the air stream of the ionizing field, positively
charged dust particles are attracted and attached to the ground plates.
� Dust particles agglomerate at the ground plates.� Ground plates’ dust particles glow to such sizes that they are blown
off and carried away by the air stream.
Application:
�� Atmospheric dust
� Cigarettes smoke
22
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
�
Electronic air cleaner(cont’d)A high DC potential of 1.2kV is applied to the ionizing field. � Positive ions generated from the ionizer wire charge the dust particles. � After passing the ionizing section, dust particles come to a collecting section.� This section consists of several plates alternatively grounded and insulated. � A strong electric field is produced by a DC potential of 6KV is applied to these
plates. Dust particles become positively charged which are attracted and attached to the ground plates.
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Activated carbon filterPrinciples of operation:� Removal by absorption. � Activated carbon has porous surface.� Gas molecules diffuse into the microspores or macro spores of
activated carbon, bond to these surfaces and come i n contact with the carbon granules.
� Reactivation or regeneration required for activated carbon at the end of its life
Construction� Activated carbon is in the form of granules or pell ets.� Activated carbon is placed in special tray� This special tray slides easily into position to fo rm activated
carbon beds� These activated carbon beds are sealed into the cel l housing by
facing plates.� Low efficiency filter is placed as pre-filter
Application: l Refuse storage room ventilation: removal of object ionable odour
and irritating vapour of gaseous airborne particles 3nm to 6nm in size
23
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Activated carbon filter
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Ventilation System – Supply Only
24
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Air Conditioning Systems – air side system
The classification of the air side systems could be as follows: -
�All air systems
�Air-water systems
�All-water systems
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air SystemSingle-zone or multi-zone systems
Single-zone system� Space temperature, relative humidity, and volume flow rate
are controlled directly by the coils, humidifiers, and inlet vanes or ac inverter in the air-handling unit or packaged unit.
� Constant Air Volume and Variable Air Volume System
Multi-zone system� Zone temperature or zone supply volume flow rate is
controlled by terminals. Reheat is used to control the temperature and or relative humidity
25
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air systemSingle-duct or dual-duct systems
Single-duct system� Conditioned air is supplied to the conditioned
space by a single supply duct. � Constant Air Volume and Variable Air Volume
System
Dual-duct system� Conditioned air is supplied to the conditioned
space in the perimeter zone through two supply ducts:
� a warm air duct and a cold air duct. � In the interior zone, only a cold air duct is
needed.� Constant Air Volume and Variable Air Volume
Systems
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air systemConstant Air Volume (CAV) or variable-air-volume systems(VAV)
CAV systemTemperature of supply air is modulated to match the variation of space load during part-load operation.
VAV systemSupply volume flow rate is modulated to maintain a predetermined space temperature as space load varies.Fan powdered and Fan powdered VAV with reheat are other options
26
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air System, Single duct, Constant Air Volume
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air System, Single duct, Constant Air with Reheat System
(Multi-zone if one or more duct tee off and each with a reheat coil)
27
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air, Single Duct, Constant Air Volume with BYPASS
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air, Single Duct, Variable Air Volume SystemAll-air, Single Duct, Variable Air Volume System
28
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air, Single Duct, Variable Air Volume with Reheat Coil
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air, Dual Duct, Constant Air Volume System
29
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air, Dual Duct, Variable Volume System
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
)( srpas
rss ttc
qV
−=
ρ�
Supply Air Flow Rate Determination
sV�
sρsρ
= Volume supply flow rate
= density of air
qrs = sensible heat gain
Cpa = specific heat of supply air
tr = return air temperature
ts = supply air temperature
30
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
For a given sensible heat gain,
� CAV system keeping same volume flow and varies the supply air temperature
� VAV system keeping the same supply air temperature and varies the flow rate
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air System, CAV system
Typical Schematic diagram
Return fan for large system only
31
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IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air system, typical operation cycle
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air, Constant Air Volume, Multi-zone with reheat
32
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IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Multizone – reheat
� Reheating is a process in which air is reheat after it has been cooled
� Reheating is a simultaneous cooling and heating process in an air conditioning cycle
Multizone, Constant Volume System with Reheat
� During summer mode, outdoor air is mixed with recirculating air.The mixture flows through the filter and is then cooled and humidified at the cooling coil and discharged from the AHU at supply fan outlet.
� After absorbing the duct heat gain, the conditioned air enters the reheating coil.
� Assume only one heating coil is energized so as to maintain the air temperature while the other is not.
� Return air from both spaces is mixed together and returned to AHU with some exhausts out to outside
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Multizone, Constant Volume System with Reheat
Supply flow rate equals summation of the flow to all the zones
tr is replaced by Trm
Where a1 zoneat rate flow mass1 =am�
1 zoneat eTemperatur1 =rT
33
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
VAV system – Single Zone
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All-air system – VAV system
A single-zone VAV system
A VAV system that varies the air volume flow rates supplied to and returned from a single-zone conditioned space to maintain a predetermined space parameter at reduced load and to conserve fan power.
Conditioned spaces in buildings are primarily divided into two categories:
� Perimeter zone, where there are external wall, roofs, and windows and space load varies depending on solar heat,outdoor-indoor temperature difference and internal load; and
� Interior zone where space loads are mainly internal loads. In an interior zone, the air system often operates at cooling mode in both summer and winter
34
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
VAV Box
A variable-air-volume box or a cooling VAV box is a terminal device in which the supply volume flow rate is modulated by varying the opening of the air passage by means of a single-blade butter-fly damper
The pneumatic or direct digital control of an air valve
A pneumatic control VAV box has a faster response actuator and a lower initial cost than those of a DDC VAV box.
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
VAV Box
35
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
� In a pressure-dependent VAV box, the variation of the duct static pressure at the inlet of the VAV box caused by the opening and closing of the dampers connected to the same main supply duct influences the modulation of its supply volume flow rate.
� When the pressure at the inlet varies, the airflow often oscillates. Pressure-dependent VAV boxes are least expensive. They are used when the duct static pressure is more stable and in places where there is no need for maximum and minimum limit control.
Duct Static Pressure.
Pressure-dependent VAV box.
Pressure-independent VAV box
� A pressure-independent VAV box modulates its supply volume flow rate regardless of the variation of duct static pressure at its inlet.
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Inlet guide vanes or frequency drive
For flow control
36
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
VAV system – Flow rate control
� Either Inlet guide vane or frequency drive would control the flow rate of supply air
� A pressure sensor to be mounted at duct for feeding signal for the controller to control the flow rate of the VAV system
� A words of precaution – At reduced flow condition, the reduced air may also cause increase in carbon dioxide concentration.
� The minimum of supply air rate (against the standard value) should be considered, say 30% of the design flow rate.
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Air –water system: Fan Coil Unit & Primary Air Unit
37
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Air –water system: Fan Coil Unit & Primary Air Unit
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
All –water system: Fan Coil Unit only
38
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Two Pipe System
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Four pipes system
39
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
Warn air is only used for offsetting winter heat load
Non-changeover 2-pipe system:
AAAAAAAA
IIIIIIII
RRRRRRRR
CCCCCCCC
OOOOOOOO
NNNNNNNN
DDDDDDDD
IIIIIIII
TTTTTTTT
IIIIIIII
OOOOOOOO
NNNNNNNN
IIIIIIII
NNNNNNNN
GGGGGGGG
SSSSSSSS
YYYYYYYY
SSSSSSSS
TTTTTTTT
EEEEEEEE
MMMMMMMM
MECHANICAL AND ELECTRICAL SYSTEM - Mazlan 2008
UTM
FKMFKM
UNIVERSITI TEKNOLOGI MALAYSIAUNIVERSITI TEKNOLOGI MALAYSIA
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