Mitsubishi Electric PUMY-P112VKM4 Technical & Service Manual page 14

DATA
4
4-1. SELECTION OF COOLING/HEATING UNITS
<Cooling>
Outdoor Design Dry Bulb Temperature
Total Cooling Load
Room1
Indoor Design Dry Bulb Temperature
Indoor Design Wet Bulb Temperature
Cooling Load
Room2
Indoor Design Dry Bulb Temperature
Indoor Design Wet Bulb Temperature
Cooling Load
<Other>
Indoor/Outdoor Equivalent Piping Length
Capacity of indoor unit
P•FY series Model Number
for indoor unit
Model
Capacity
M series Model Number
S series for indoor unit
P series
Model
Capacity
1. Cooling Calculation
(1) Temporary Selection of Indoor Units
Room1
PEFY-P50
Room2
PEFY-P71
(2) Total Indoor Units Capacity
P50 + P71 = P121
(3) Selection of Outdoor Unit
The P125 outdoor unit is selected as total indoor units capacity is P121
PUMY-P125
(4) Total Indoor Units Capacity Correction Calculation
Room1
Indoor Design Wet Bulb Temperature Correction (20ºC)
Room2
Indoor Design Wet Bulb Temperature Correction (18ºC)
Total Indoor Units Capacity (CTi)
CTi = Σ (Indoor Unit Rating × Indoor Design Temperature Correction)
= 5.6 × 1.03 + 8.0 × 0.94
= 13.3 kW
(5) Outdoor Unit Correction Calculation
Outdoor Design Dry Bulb Temperature Correction (45ºC)
Piping Length Correction (60 m)
Total Outdoor Unit Capacity (CTo)
CTo = Outdoor Rating × Outdoor Design Temperature Correction × Piping Length Correction
= 14.0 × 0.86 × 0.90
= 10.8 kW
(6) Determination of Maximum System Capacity
Comparison of Capacity between Total Indoor Units Capacity (CTi) and Total Outdoor Unit Capacity (CTo)
CTi = 13.3 > CTo = 10.8, thus, select CTo.
CTx = CTo = 10.8 kW
(7) Comparison with Essential Load
Against the essential load 10.8 kW, the maximum system capacity is 10.8 kW: Proper outdoor units have been selected.
(8) Calculation of Maximum Indoor Unit Capacity of Each Room
CTx = CTo, thus, calculate by the calculation below
Room1
Maximum Capacity × Room1 Capacity after the Temperature Correction/(Room1,2 Total Capacity after the Temperature Correction)
= 10.8 × (5.6 × 1.03)/(5.6 × 1.03 + 8.0 × 0.94)
= 4.7 kW
Room2
Maximum Capacity × Room2 Capacity after the Temperature Correction/(Room1,2 Total Capacity after the Temperature Correction)
= 10.8 × (8.0 × 0.94)/(5.6 × 1.03 + 8.0 × 0.94)
= 6.1 kW
Note: If CTx = CTi, please refer to the <Heating> section to calculate the Maximum Indoor Unit Capacity of Each Room.
Go on to the heating trial calculation since the selected units fulfill the cooling loads of Room 1, 2.
OCH673D
Design Condition
Model 10 Model 15 Model 20 Model 25 Model 32 Model 40 Model 50 Model 63 Model 71 Model 80 Model 100 Model 125 Model 140
1.2 1.7 2.2 2.8
Model 15 Model 18 Model 20 Model 22 Model 25 Model 35 Model 42 Model 50 Model 60 Model 71 Model 80 Model 100
1.5 1.8 2.0 2.2
5.6 kW (Rated)
8.0 kW (Rated)
14.0 kW
OK: fulfills the load 4.6 kW
OK: fulfills the load 6.0 kW
45ºC
10.6 kW
27ºC
20ºC
4.6 kW
24ºC
18ºC
6.0 kW
60 m
3.6 4.5 5.6 7.1
2.5 3.5 4.2 5.0
1.03 (Refer to Figure 1)
0.94 (Refer to Figure 1)
0.86 (Refer to Figure 2)
0.90 (Refer to Figure 3)
14
8.0 9.0 11.2 14.0
6.0 7.1 8.0 10.0
1.2
1.0
0.8
0.6
0.4
15 16 17 18 19 20 21
Indoor Temperature [°CW.B.]
Figure 1 Indoor unit temperature correction
To be used to correct indoor unit only
1.3
1.2
1.00
1.1
0.95
1.0
0.9
0.90
0.8
0.85
0.7
0.6 0.80
0.5
0.75
0.4
0.3 0.70
0.2
0.65
-5.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0
Outdoor Temperature [°C D.B.]
0.60
Figure 2 Outdoor unit temperature correction
0.55
To be used to correct outdoor unit
0.50
0 20 40 60 80 100 120
Piping equivalent length (m)
1.00
0.95
0.90
0.85
0.80
0.75
0.70
0.65
0.60
0.55
0.50
0 20 40 60 80 100 120
Piping equivalent length (m)
Figure 3 Correction of refrigerant piping length
Unit: kW
16.0
22 23 24
Indoor Temperature
Total capacity of indoor unit
6.3
19°C W.B
9.4
12.5
16.2
50.0 52.0
40.0 45.0
only
140 160 180
Total capacity of indoor unit
7.0
10.5
14.0
18.2
140 160 180