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AirConditioningSystemDesign 1
CHAPTER I
Introduction
HVAC (heating, ventilation, and air conditioning) is the technology of indoor and
automotive environmental comfort. HVAC system design is a major sub discipline
of mechanical engineering, based on the principles of thermodynamics, fluid mechanics,
and heat transfer. Refrigeration is sometimes added to the field's abbreviation as
HVAC&R or HVACR, or ventilating is dropped as in HACR (such as the designation of
HACR-rated circuit breakers).
HVAC is important in the design of medium to large industrial and office buildings
such as skyscrapers and in marine environments such as aquariums, where safe
and healthy building conditions are regulated with respect to temperature and humidity,
using fresh air from outdoors (Wikipedia).
In our daily life situations, air-conditioning system place an important role. It serves
as a sense of relaxation, gives comfort to human bodies, regulates the temperature in
working places and many others. Generally speaking, air-conditioning system is the way
of conditioning the air insid e of a system to provide the necessary quality of air. This
research aims to provide the way of designing an air-conditioning system by the use of
duct system and the calculation on proper derivation of sizes in each duct to be able to
balance the flow of air.
Air conditioning generally is understood to mean the simultaneous control of
temperature, relative humidity, air motion, air distribution, and ventilation within an
enclosure. Air-conditioning system are used in theaters, churches, auditoriums, schools,
restaurants, offices, homes, etc., to produce of effect comfort for occupants by
maintaining a temperature and relative humidity which will lie in the so-called comfort
zone (Kent, 1895).
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AirConditioningSystemDesign 2
CHAPTER II
CALL CENTER AIR CONDITIONING SITE
Isometric View Layout
The Figure shows the plan of call center site where an air conditioning system is to be installed, the air conditioning site dimensions are needed for the computation of cooling load of the system.
Figure 2.1: Layout for Air Conditioning Area
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AirConditioningSystemDesign 3Top View Layout
Figure 2.2 shows the layout of the call center site in top view. The measurements in meters will be used for the surface area that is essential for calculating the heat loads in the walls.
Measurements in meters
Figure 2.2: Floor Layout of the Air Conditioning Site
-
AirConditioningSystemDesign 4Glass Door
The maindoor is made up of a double glass door with patch and fittings, opposite slide opening, it is made of tempered glass 9 millimeters thick to acquire higher heating resistance.
Figure 3.3: Glass Door Dimensions
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AirConditioningSystemDesign 5
CHAPTER III
COOLING LOAD CALCULATION
This chapter focuses on the cooling load computations that are present in the following area for application of air conditioning system. It includes heat transmissions on walls, windows and doors. Also the heat gain from the lightings, people, solar heat, appliances and many others. These values are needed for acquiring the appropriate capacity of an air conditioning unit.
I. Sensible Heat Loads
a. Thermal Transmission
These are the heat transferred through the structure due to temperature difference from the environment, from high temperature to low temperature for air conditioning system.
Exterior Walls
Table 3.1: Specification of Exterior Walls
Material Description , /
,/ Cement plaster 16 mm 1.39 Light weight aggregate
200 mm 0.38
Internal conductance
Surface emissivity of 0.9
0.120
Outside conductance
Heating season, 6.7 m/s
0.029
source: Refrigeration and Air Conditioning by: Stoecker pg.68
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AirConditioningSystemDesign 6
Figure 3.1: Wall insulation materials
Thermal Coefficient
10.02 0.12 1.390.0162 0.38
.
Ceiling Insulations
Table 3.2: Specification of Ceiling Insulations
source: Refrigeration and Air Conditioning by: Stoecker pg.68
Material Description /, /
,/ Gypsum board 16mm 1.39 Concrete (sand and gravel)
200 mm 0.18
Air Space 0.170 Internal conductance
Surface emissivity of 0.9
0.120
Outside conductance
Heating season, 6.7 m/s
0.029
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AirConditioningSystemDesign 7
Figure 3.2: Ceiling insulation materials
Thermal Coefficient
...... .
Window Glass
Table 3.3: Specification of Window Glass
Material Description U, Single glass 6 mm, heat absorbing 5.9
source: Refrigeration and Air Conditioning by: Stoecker pg.69
Thermal Coefficient
. Doors
Table 3.4: Specification of Glass door
Material Description U, Tempered glass door 9 mm 5.7
source: http://www.aisglass.com/flat_tempered.asp#5
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AirConditioningSystemDesign 8
Figure 3.3: Glass door materials
Thermal Coefficient
.
Summary of Thermal Coefficients The summary of all the necessary thermal heat conductivity is tabulate in Table 3.5 for the computation of heat load.
Transmissions , Exterior walls 0.47 Ceiling insulation 1.91 Window glass 5.90 Glass door 5.70
Heat Gain on the Exterior
In the computation of heat load in the exterior sides, the following values are needed namely, thermal conductivity, ambient temperature, desired temperature and cross sectional area.
-
AirConditioningSystemDesign 9Temperature Standards
Table 3.6: Temperatures Standards for Design
Classification Temperature ( C ) (a) Ambient temperature 35 (b) Desired temperature 25
source: (a) http://mb.com.ph/node/357745/heat-wave-not-likely (b) Refrigeration and Air Conditioning by Stoecker and Jones pg.65
Transmission Dimensions
Figure 3.4 shows the diagram of the transmission blocks involve in thermal heat gain of the exterior sides. The orientation are presented base on its sides for computation purposes.
Figure 3.4: Transmission Diagram
Table 3.7: Dimension of Transmission Materials
Transmission Block Length, m Width, m Area ( m2 ) Wall A and C 30 6 180 Wall B and D 80 6 480 Ceiling 80 30 2400 Windows 3 2 6 Doors 3 1.5 4.5
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AirConditioningSystemDesign 10
Transmission Areas
Nomenclature: A ~ Area
Exterior Walls:
A exterior wall = A wall A + A wall B + A wall C + A wall D
A Wall A = 180 4(A window)
A Wall A = 156 m2
A Wall B = 480 4(A door)
A Wall B = 462 m2
A Wall C = 180 4(A window)
A Wall C = 156 m2
A Wall D = 480 8(A window) 2(A door)
A Wall D = 423 m2
A exterior wall = 156 m2 + 462 m2 + 156 m2 + 432 m2
A exterior wall = 1197 m2
Ceiling:
AC = 80 x 30
AC = 2400 m2
Windows:
A window = A window + no. of glasses
A window = 6 m2 x 16
A window = 96 m2
Doors:
Adoor = 2 x Adoor
Adoor = 6 x 4.5 m2
Adoor = 27 m2
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AirConditioningSystemDesign 11
Table 3.8: Summary of Transmission Areas
Transmissions Total Area ( m2 ) Exterior wall 1197 Ceiling 2400 Window glass 96 Glass Door 27
Heat Gain
For the computations of heat gain through external walls the following formula for Q will be used. The total value of heat load in the system will be used to acquire the appropriate capacity of an air conditioning unit.
Nomenclature: Q ~ Heat Gain, W
U ~ Overall thermal coefficient; W/m2 0C A ~ Area of the wall, ground floor, floor, or roof; m2 T ~ Thermal difference, 0C
Exterior Walls
1.7715 119735 25 21204.86 Ceiling
1.91 240035 25 45,840
Windows Glass
5.9 9635 25 5664
Glass Door
5.7 2735 25 1539
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AirConditioningSystemDesign 12Tabulated Exterior Heat Gain
Table 3.9: Heat Gain in the ExteriorTransmissions Heat Gain ( W )
Exterior Walls 21204.86 Ceiling 45840 Window Glass 5664 Glass Door 1539 Total 74247.86 Watts
b-1. Solar Load through Transparent Surface
In a transparent surface of a glass the heat load produce came from the solar radiance that passes through the transparency quality of the glass. The figure 3.5 shows the area of the sun light expose for a certain amount time and respective direction.
Figure 3.5: Solar Radiance in the Glass
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AirConditioningSystemDesign 13
Nomenclature: Q ~ Solar heat gain SHGF ~ Solar heat gain factor SC ~ Shading coefficient CLF ~ Cooling load factor A ~ Sunlit area ~ Wall azimuth angle ~ Solar altitude angle ~ Solar azimuth angle ~ Angle of aertical plane normal to the wall makes with south d ~ Depth recess of the window glass y ~ Depth of shadow cast horizontal projection above window x ~ Width of the shadow cast by vertical projection depth
Design Parameters
The design parameter shown in Table 3.10 provides the following design conditions for the computation of solar heat gain through the glass.
Table 3.10: Design Parameters for Solar Heat Gain
Variable Description Critical Date(a) April 20Location(b) 15N Latitude Critical Time(c) 3:00 pm Solar Altitude Angle, (c) 46 Solar Azimuth Angle, (c) 271 Wall Azimuth Angle, 32 Depth, d 97 mm
source: (a) http://newsinfo.inquirer.net (b) http://www.mapsofworld.com/lat_long/philippines-lat-long.html (c) Carrier Handbook of Air Conditioning System Design
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AirConditioningSystemDesign 14Window Glass Specification
Table 3.11: Specification of Window Glass
Variable Description Type Heat absorbingShading Translucent, Light
Venetian BlindsThickness 6 mm Dimension(L x W) 3m x 2m
source: Refrigeration and Air Conditioning by Stoecker and Jones pg.76
Shading from Side Reveal
tan 97tan 32 60.61
Shading from Top Reveal
tan cos
97 tan 46cos 32 118.44
Sunlit Area
2 0.118443 0.0.06061 .
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AirConditioningSystemDesign 15Solar Heat Gain Factor
Table 3.12: Tabulation of Solar Heat Gain Factors
source: Air Conditioning Principles and Systems by: Edward G. Pita
228
.
Shading Coefficient (Table 4-11, Stoecker, p.76)
. Cooling Load Factor (Table 4-12, Stoecker, p.77)
.
718.24 0.530.725.532 .
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AirConditioningSystemDesign 16b-2. Solar Load on Opaque Surfaces
The solar heat gain for an opaque wall is described as a portion of solar energy that is reflected and the remainder is absorbed. In the energy absorbed some is converted and some radiated to the outside. The remainder of the absorbed solar energy is transmitted to the inside by conduction and temporarily stored.
Solar Heat Gain through an Opaque Wall
Nomenclature: Qow ~ Solar heat gain through the opaque wall Uw ~ Heat transfer coefficient of the wall CLTD ~ Cooling load temperature difference A ~ Surface area t1 ~ Inside temperature t2 ~ Outside temperature
Table 3.13: Tabulation of Heat Gain through the Opaque Walls
Direction U ( )
CLTD Area (m2)
TemperatureInside (C)
Temperature outside (C)
Heat Gain (W)
A South 1.77 16 156 25 35 6074.64 B East 1.77 20 462 25 35 21261.24 C North 1.77 8 156 25 35 3865.68 D West 1.77 11 423 25 35 12728.07
Total 43929.63 source: Refrigeration and Air Conditioning by Stoecker and Jones pg.82
Total Solar Heat Gain through Opaque Walls
.
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AirConditioningSystemDesign 17
c. Heat Gain through Infiltration
The air infiltration is the unwanted entry of the outside air directly inside the building, resulting from natural forces, such as wind and buoyancy due to the temperature difference of the environment the in system.
. Nomenclature: ~ Heat gain through infiltration, kW ~ Rate of infiltration air through opening doors
~ Outside temperature ~ Inside temperature
3600
680303600 1
4 1.23 4 35 25 49.2
d. Heat Emission from Occupants
The human has its heat and this heat is necessarily included for the computation of heat gain by the system. The more people a system possesses the more heat is being gain.
-
AirConditioningSystemDesign 18Nomenclature: ~ Heat gain per person ~ number of occupants ~ Cooling load factor per person
Table 3.14a: Design Conditions
Variable Description Type of Space Office Activity Office work Working time 12 hours Occupancy 10 m2/occupant
source: Refrigeration and Air Conditioning by Stoecker and Jones pg.73-74
Table 3.14b: Heat Emission from the Occupants
Heat Gain per Person, W
No. of Occupants
Cooling Load Factor
Heat Emission (Watts)
150 384 0.92 52992 source: Refrigeration and Air Conditioning by Stoecker and Jones pg.73
Total Heat Emission from the Occupant
e. Heat Gain from Electric Lights Lighting produces heat that is also calculated for the cooling load. A light level of
500-750 lux is usually sufficient, depending on the difficulty of the visual tasks done in the factory (Graham, 1984).
Nomenclature: ~ Lighting Capacity, Watts ~ Ballast Factor ~ Cooling Load Factor for Lighting ~ Number of lightings
Table 3.15: Lighting Material Specifications
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AirConditioningSystemDesign 19
Variable Description Lighting capacity 40 W Light level 750 Lux, Lumen/m Led light lumen 3050 lm Area 30m x 80m = 2400 m Ballast factor (a) 1.25 Cooling load factor (b) 1.0
Source: (a) Air conditioning principles and systems by Pita p. 137;
(b)http://www.amazon.com/dp/B002CZ15FK/ref=asc_df_B002CZ15FK2173156?smid=A2E4DH1S65
GTFP&tag=nextagusmp0403791-20&linkCode=asn&creative=395105&creativeASIN=B002CZ15FK
Table No. shows the specification of the lighting materials that is used with an
additional factor for lightings. Also the selected design of the light level is 750 lux. The lux (symbol: lx) is the SI derived unit of illuminance or illumination. It is equal to one lumen per square metre. Lux is the symbol for light level which is the basis of the design of the lighting load of the cold storage. ( Brillianz Company UK, 2006)
Total lumen = light level x area = 750 lumen/m x 2400 m = 1,800,000 lumen =
,,/ 590.16 590lamps
401.251.0590 f. Heat Gain from Appliances
The appliance also emits heat as it consumes the electricity to produce power. This heat gain is also essential for achieving the total heat gain in the system. The common appliance present in the system is the computers which has a common wattage of 300W as stated in ASHRAE 2011 and there is a computer in every cubicle.
. ) Power Consumption = 300 Watts (ASHRAE 2011)
No. of Appliances = (12)(2)(3)(2) = 144 cubicle + 4 units = 148 Computers
300148 2. Latent Heat Loads
-
AirConditioningSystemDesign 20a. Latent Heat from Infiltration Air
Nomenclature: ~ Rate of infiltration air, m3/s ~ Humidity ratio outdoor air ~ Humidity ratio indoor air
Table 3.16: Humidity Ratio Conditions Type Humidity Ratio (grains/lb)
Indoor 106.40 Outdoor 131.60
Source: Psychometric Tables and Charts by: Stoecker
0.68 0.68 35.315
0.68 6.45 35.315
60/ 131.6 106.40 234196/ b. Latent Heat from Occupants
Table 3.14b: Heat Emission from the Occupants
Heat Gain per Person, W
No. of Occupants
Cooling Load Factor
Heat Emission (Watts)
150 384 1 57600 source: Refrigeration and Air Conditioning by Stoecker and Jones pg.73
Total Latent Heat from Occupants
Total Cooling Load
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AirConditioningSystemDesign 21
74247.86 1515.66 43929.63 49200 52992 29500 44400 68632 57600
422017.15
422017.15 3516.7
CHAPTER IV
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AirConditioningSystemDesign 22
AIR DISTRIBUTION SYSTEM
This chapter is mainly about the methods of supplying appropriate air conditioning system for the building site, including the various computations for volume flow, mass flow and duct diameters. These values are relevant in providing an efficient distribution of air in the scope of the system.
Figure 4.1: 3D Ducting Layout
A. Duct Sizing
In duct sizing there are many options or methods for the design of duct. The most accurate in the two methods is the equal friction method where the friction in the main duct follows all throughout the latter part of the duct system which is the same.
Table 4.1: Design Conditions for Duct Sizing
Variable Description Main duct velocity (a) 4 7 m/s Main branch velocity 3 6 m/s Density of Air (b) 1.18425 kg/m3Sensible heat gain 295.78515 kW Temperature of room 25C Temperature of supply air 35C
source: (a) http://www.engineeringtoolbox.com/equal-friction-method-d_1028.html (b) Refrigeration and Air Conditioning by: Stoecker and Jones
Determination of Volume Flow Rates:
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AirConditioningSystemDesign 23
.
Nomenclature: ~ Volume flow rate, m3/s ~ Total sensible heat gain, kW ~ Density of air, kg/m3
295.785151.184251.006235 25
. Main Duct Dimensions
The main ducts are the ventilation mechanism that holds the total air volume flow of the whole system. It is the key in finding the appropriate machine capacity of the fans to be able to supply the whole air conditioned area.
Nomenclature: A ~ Cross sectional area of duct Q ~ Volume flow rate of air ~ Average velocity, (5.5 m/s for average speed)
Using two main ducts for the system with equal performance we arrive
24.822
12.41
12.415.5
2.26
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AirConditioningSystemDesign 24
4
42.26
. Equivalent square duct dimensions
1.61 . .
For the orientation of diffusers, one main duct is composed of 20 diffusers that are placed proportionally with each other. Considering two main ducts are to be used in the design for a total number of 40 diffusers to ventilate the system.
12.4120
0.6205/ 2 12.41 20.6205 . /
The formula for computing the next duct dimension is the same as the calculations above, the rest of the values follows. In addition, to acquire the various volumes of the duct assume the same friction losses in each resized duct and use the friction loss chart for their values. (Carrier Air Conditioning System Design p.190)
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AirConditioningSystemDesign 25Duct Sizing Dimensions
In the sizing of the ducts the tabulated values in Table 4.2 are essential for providing the right volume flow of air to maintain comfort cooling from the occupants.
Figure 4.2: Friction Loss Chart
The Friction Loss Chart shown in Figure 4.2 is a useful Chart in getting the velocity in the equal friction method. It is a three way process of acquiring variables. Specifically air volume flow, velocity and diameter of duct
-
AirConditioningSystemDesign 26
Table 4.2: Tabulated Duct Dimensions
Duct Air Volume Flow m3/s
Velocity m/s
Duct Diameter, m
Rectangular Length, m
Rectangular height, m
A 12.410 5.691 1.666 1.5 1.454 B 11.169 5.640 1.588 1.5 1.320 C 9.928 5.488 1.518 1.5 1.206 D 8.687 5.335 1.440 1.5 1.085 E 7.446 5.030 1.373 1.5 0.987 F 6.205 4.929 1.266 1 1.259 G 4.964 4.573 1.176 1 1.085 H 3.773 4.319 1.055 1 0.874 I 2.482 3.963 0.893 1 0.626 J 1.241 3.252 0.697 1 0.382
Main Branch Dimension
For the computation in sizing of ducts for the main branches consider same air volume flow in each diffuser. Tabulated values of the dimension in each branch are shown in Table 4.3.
Nomenclature: ~ Air volume flow for the branch ~ Velocity of the branch
1.2414.5
0.275
40.275
.
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AirConditioningSystemDesign 27Equivalent Rectangular Dimensions
0.275 .
Table 4.4: Main Branch Dimensions
Branch Air Volume Flow
Diameter
Rectangular Length
Rectangular height
A1 1.241 0.592 0.524 0.524 A2 1.241 0.592 0.524 0.524 B1 1.241 0.592 0.524 0.524 B2 1.241 0.592 0.524 0.524 C1 1.241 0.592 0.524 0.524 C2 1.241 0.592 0.524 0.524 D1 1.241 0.592 0.524 0.524 D2 1.241 0.592 0.524 0.524 E1 1.241 0.592 0.524 0.524 E2 1.241 0.592 0.524 0.524 F1 1.241 0.592 0.524 0.524 F2 1.241 0.592 0.524 0.524 G1 1.241 0.592 0.524 0.524 G2 1.241 0.592 0.524 0.524 H1 1.241 0.592 0.524 0.524 H2 1.241 0.592 0.524 0.524 I1 1.241 0.592 0.524 0.524 I2 1.241 0.592 0.524 0.524 J1 1.241 0.592 0.524 0.524 J2 1.241 0.592 0.524 0.524
B. Pressure Losses
The pressure losses are the opposing force that is cause by friction. Friction is a mechanism that resists or opposes the direction of the force, these values are needed to acquire the total pressure loss in the system which is an essential variable in computing the machine capacity of an air handling unit.
-
AirConditioningSystemDesign 281. Converging Duct System
Converging air duct has a gradual decrease in size or dimensions.
Nomenclature: ~ Pressure loss, pa ~ Velocity of air at point 2, m/s ~ Cross sectional area at point 1, m2 ~ Cross sectional area at point 2, m2 ~ Density of Air, kg/m3
1.1845.640
2 2.1801.810
1
. The rest of the system follows and the values are tabulated in Table 4.5.
Table 4.5: Tabulation of pressure losses in duct
Duct Density (kg/m3)
Velocity (m/s)
Diameter (m)
Area A(m)
Area B(m)
Pressure loss(Pa)
AB 1.184 5.691 1.666 2.180 1.981 18.835 BC 1.184 5.640 1.588 1.981 1.810 17.834 CD 1.184 5.488 1.518 1.810 1.629 16.853 DE 1.184 5.335 1.440 1.629 1.481 14.981 EF 1.184 5.030 1.373 1.481 1.259 14.386 FG 1.184 4.929 1.266 1.259 1.086 12.383 GH 1.184 4.573 1.176 1.086 0.874 11.045 HI 1.184 4.319 1.055 0.874 0.626 9.300 IJ 1.184 3.963 0.893 0.626 0.275 6.653
Total 115.617
-
AirConditioningSystemDesign 292. Pressure Drop for Sudden Contraction
When the duct size is abruptly reduced in the direction of flow in a duct section a sudden contraction occurs. The flow of patterns consists of a separation of the fluid from the wall upon entering the reduced sectional area.
Nomenclature: ~ Contraction Coefficient
1.1845.640
2 0.010
. The rest of the values follow and the tabulation for pressure drop for sudden contraction is shown in Table 4.6.
Table 4.6: Tabulation of Pressure Drop For Sudden Contraction
Duct Velocity m/s
Density kG/m3
Area 1 m2
Area 2 m2
Cc Pressure Loss (Pa)
A 5.691 1.184 2.180 1.981 0.909 0.193 B 5.640 1.184 1.981 1.810 0.914 0.168 C 5.488 1.184 1.810 1.629 0.900 0.220 D 5.335 1.184 1.629 1.481 0.909 0.168 E 5.030 1.184 1.481 1.259 0.850 0.466 F 4.929 1.184 1.259 1.086 0.863 0.365 G 4.573 1.184 1.086 0.874 0.805 0.728 H 4.319 1.184 0.874 0.626 0.716 1.733 I 3.963 1.184 0.626 0.382 0.610 3.793 J 3.252 1.184 0.382 0.275 0.720 0.948
Total 8.782 Pa
3. Turns or Elbows
Most common elbows used in duct system are 90 degree turn which accumulates pressure losses as the air pass through.
-
AirConditioningSystemDesign 30
For Geometric Factor refer to (Refrigeration and Air Conditioning by: Stoecker and Jones
. .
.
. .
4. Friction Loss
As the air travels through the duct system there is a corresponding pressure drop opposing force in a unit of length which is needed to get the total pressure drop.
Nomenclature: ~ Length of duct, m ~ Pressure drop per meter, Pa/m ~ 1.0 Pa/m (Carrier Handbook of Air Conditioning)
121/
Table 4.7: Tabulation of Friction Loss in a Length of Duct
Duct Length (m)
Pressure Drop (Pa)
A 12.723 12.723 B 4.232 4.232 C 5.000 5.000 D 5.000 5.000 E 10.000 10.000 F 13.000 13.000 G 5.000 5.000 H 5.000 5.000 I 5.000 5.000 J 3.986 3.986
Total 68.941 Pa
-
AirConditioningSystemDesign 31Total Pressure Drop
115.617Pa 8.782Pa 79.12 68.941Pa
. A total of 272.46 Pa of pressure drops in one main duct. Consider two main ducts in the system with equal specification and measurements.
-
AirConditioningSystemDesign 32
CHAPTER V
AIR CONDITIONING SYSTEM
This chapter provides the necessary specification mechanism that is appropriate to the air conditioning system to ba applied. The machineries must be compatible and reliable to make the system a comfort air conditioning area.
A. CHILLER
A chiller is a machine also known as a heat exchanger which removes the heat from a liquid by vapor compression or absorption refrigeration cycle to main the comfort temperature of air desired. In the Air Conditioning System it is appropriate to choose two chillers with same specification to provide the corresponding cooling load that the system requires. So when the other chiller is malfunctioning. The other chiller is still operating.
Table 5.1: Water Cooled Chiller Source source: http://www.aquaair.net/HighCapacityChillerSystems.pdf
-
AirConditioningSystemDesign 33Chiller unit specification OM60-4VIHD Cooling Capacity
60 tons [ 720,000 BTU/H ] [ 180,000 KCAL/H ] at 45/ F ( 7.2/ C ) leaving water temperature and 55/ F ( 12.8/ C ) returning water temperature. Chiller unit flow rate will be approximately 180 gpm. Condenser flow rate ( each ) is to be approximately 60 gpm entering at a maximum temperature of 90/ F ( 32/ C ). All ratings are at a fouling factor of 0.0005. Heating Capacity `54 Kw [ 184,410 BTU/H ] [ 46,103 KCAL/H ] of total heating capacity at 120/ F ( 48.9/ C) leaving water temperature and 100/ F ( 37.8/ C ) returning water temperature. Construction & Ratings
The chiller unit shall be constructed in accordance with ARI Standard 590-86 and shall comply with all applicable NEC and ASME codes for water cooled chillers. Compressors
The chiller unit will have four, 15 ton Bitzer semi-hermetic compressors. Each compressor will be equipped with suction and discharge valves. Input voltage to the compressor motor will be 208-3-60. Power consumption of each compressor is approximately 14.1 kW each. Refrigerant to be used is R-22 . Capacity Control
Chiller unit capacity control will be achieved through the use of four variable frequency drive ( VFD ) units, one for each compressor. The VFD will vary the compressor motor speed from a maximum of 100% of capacity to a minimum of 70%. The VFD requires an input power supply of 208-3-60. The maximum output power will be 208-3-60 to the compressor motor. The VFD output will be regulated by a 4-20ma signal to the VFD from the PLC. The VFD voltage/frequency output will be varied based upon chilled water outlet temperature. The VFD will also control the compressor motor so that there is no current inrush, during starting, above the motor's standard running amperage. Cooler
The unit is equipped with four plate style heat exchangers, each of 15 tons capacity. Each plate heat exchanger has a single water and refrigerant circuit. Construction of the unit is of #316 stainless steel. The material used to braze the plates together is copper. Maximum test pressure for both circuits is 635 psig. Each plate will be individually insulated with 1/2" thick closed cell insulation. Condenser The unit is equipped with four shell and tube marine condensers. The shell is constructed of ASME spec SA-53 steel pipe. Shells are shot blasted and cleaned before assembly. Tubes are high performance enhanced surface seamless 90/10 Cupro-Nickel tubes to ASME spec SB-359. Tubes are roller expanded into double grooved tubesheets
-
AirConditioningSystemDesign 34to assure tight joints. Tubesheets are 90/10 Cupro-Nickel to ASME spec SB-171 Alloy 706. Tube supports are quality steel plug welded to the shell. Heads are cast bronze with integral pass partitions, ASME spec SB-62. Gaskets are die-cut providing effective sealing between tubesheets and machined heads. The refrigerant side is constructed and tested in accordance with Section VIII, Division 1 of ASME Code for unfired pressure vessels. Shell side design pressure ( refrigerant side ) is 350 psig at 250/ F. Tube side ( water side ) is 150 psig at 150/ F. Every condenser is tested per ASME Code prior to shipment. Seawater connections are 2" Class 150 PVC schedule 80 flanges. Water flow to the condenser will be regulated by a compressor discharge pressure actuated water regulating valve. A pressure relief valve ( set for 350 psig ) on the shell is standard. Immersion Heater Elements
The unit is equipped with a three stage, 18 element, 54 Kw 5" flange style immersion heating element. The heater elements are rated at full wattage on 208-3-60 power input. The elements are constructed of copper with a maximum watt density of 50 watts per square inch. The element heater tank will be constructed of steel pipe to ASME specifications. All welds will be by MIG welding procedure. The tank will be equipped with a 5" 150lb ANSI raised face welding neck flange to accept the 5" flange style immersion heater. The tank design rating pressure is 150 psig at 200/ Fahrenheit. The tank will be equipped with a ASME water pressure relief valve. Refrigerant Circuit
Each of the four refrigerant circuits shall include a discharge line check valve, liquid line ball valve, replaceable core liquid line filter drier with access fitting for refrigerant charging, combination moisture indicator and sight glass, liquid line solenoid and thermal expansion valve. All suction lines will be covered with a minimum of 1/2" closed cell insulation.
Control Panel / Electrical Box
The unit will have a NEMA 12 type enclosure for all of the electrical components. The chiller unit will be controlled by a programmable logic controller ( PLC ). The user interface for this PLC will consist of a touch screen mounted on the front of the electrical box. B. HVAC FANS
-
AirConditioningSystemDesign 35 The capacity For an HVAC is determine by the volume flow rate of air which is 12.4m3/s and the total pressure Drop it can handle. By choosing the right specification for ducts fan will help provide the appropriate air flow in the system until to the outermost part.
Figure 5.2: Centrifugal Ventilation Fan, HVAC
source: http://www.tradezz.com/buy_10365340_ChaoYue2-26-Low.htm
Table 5.1: Specification of Centrifugal Ventilation Fan
Model Capacity Wattage Speed Static Pressure ChaoYue2-134
825~62205 m3/h
2.2~410 kW
960~2900 rpm
557~1570 Pa
source: http://www.tradezz.com/buy_10365340_ChaoYue2-26-Low.htm
Other specification: Low noise High pressure Large air flow capacity
High Efficiency Specifically designed for
supplying air The product brand ChaoYue2-134 can be an option for its specifications meets the standards for the air conditioning system design of the project this values will be useful to maintain comfort air condition inside the building.