Mitsubishi Electric PUMY-P250YBM2-BS, Technical & Service Manual

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11
TCH091
4 DATA
4-1. SELECTION OF COOLING/HEATING UNITS
Capacity of indoor unit Unit: kW
P•FY Series Model Number for
indoor unit
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
Model
200
Model
250
Model
Capacity
1.2 1.7 2.2 2.8 3.6 4.5 5.6 7.1 8.0 9.0 11.2 14.0 16.0 22.4 28.0
M Series
S Series
P Series
Model Number for
indoor unit
Model
15
Model
18
Model
20
Model
22
Model
25
Model
35
Model
42
Model
50
Model
60
Model
71
Model
100
─ ─ ─ ─
Model
Capacity
1.5 1.8 2.0 2.2 2.5 3.5 4.2 5.0 6.0 7.1 10.0 ─ ─ ─ ─
1. Cooling Calculation
(1) Temporary Selection of Indoor Units
Room1, Room2
PEFY-P50 5.6 kW (Rated)
Room3, Room4
PEFY-P71 8.0 kW (Rated)
(2) Total Indoor Units Capacity
P50 + P50 + P71 + P71 = P242
(3) Selection of Outdoor Unit
The P250 outdoor unit is selected as total indoor units capacity is P242
PUMY-P250YBM2
28.0 kW
(4) Total Indoor Units Capacity Correction Calculation
Room1, Room2
Indoor Design Wet Bulb Temperature Correction (20ºC) 1.03 (Refer to Figure 1)
Room3, Room4
Indoor Design Wet Bulb Temperature Correction (18ºC) 0.94 (Refer to Figure 1)
Total Indoor Units Capacity (CTi)
CTi = Σ (Indoor Unit Rating × Indoor Design Temperature Correction)
= 5.6×1.03 + 5.6×1.03 + 8.0×0.94 + 8.0×0.94
= 26.6 kW
(5) Outdoor Unit Correction Calculation
Outdoor Design Dry Bulb Temperature Correction (39ºC) 0.94 (Refer to Figure 2)
Piping Length Correction (20 m) 0.97 (Refer to Figure 3)
Total Outdoor Unit Capacity (CTo)
CTo = Outdoor Rating × Outdoor Design Temperature Correction × Piping Length Correction
= 28.0 × 0.94 × 0.97
= 25.5 kW
(6) Determination of Maximum System Capacity
Comparison of Capacity between Total Indoor Units Capacity (CTi) and Total Outdoor Unit Capacity (CTo)
CTi = 26.6 > CTo = 25.5, thus, select CTo.
CTx = CTo = 25.5 kW
(7) Comparison with Essential Load
Against the essential load 25.0kW, the maximum system capacity is 25.5 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, 2
Maximum Capacity × Room1, or 2 Capacity after the Temperature Correction/(Room1 to 4 Total Capacity after the Temperature
Correction)
= 25.5 × (5.6 × 1.03)/(5.6 × 1.03 × 2 + 8.0 × 0.94 × 2)
= 5.5 kW OK: fulfills the load 5.4 kW
Room3, 4
Maximum Capacity × Room3 or 4 Capacity after the Temperature Correction/(Room1 to 4 Total Capacity after the Temperature
Correction)
= 25.5 × (8.0 × 0.94)/(5.6 × 1.03 × 2 + 8.0 × 0.94 × 2)
= 7.2 kW
OK: fulfills the load 7.1 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 to 4.
<Cooling>
Design Condition
Outdoor Design Dry Bulb Temperature
Total Cooling Load
Room1, Room2
Indoor Design Dry Bulb Temperature
Indoor Design Wet Bulb Temperature
Cooling Load
Room3, Room4
Indoor Design Dry Bulb Temperature
Indoor Design Wet Bulb Temperature
Cooling Load
<Other>
Indoor/Outdoor Equivalent Piping Length
39ºC
25.0 kW
27ºC
20ºC
5.4 kW
24ºC
18ºC
7.1 kW
20 m
Figure 1 Indoor unit temperature correction
To be used to correct indoor unit only
Figure 2 Outdoor unit temperature correction
To be used to correct outdoor unit only
Figure 3 Correction of refrigerant piping length
Ratio of cooling capacity
Indoor Temperature [°C W.B.]
15 16 17 18 19 20 21 22 23 24
0.4
0.6
0.8
1.0
1.2
Ratio of cooling capacity
Outdoor Temperature [°C D.B.]
Indoor temperature
-15 -10 -5 0 5 10 15 20 25 30 35 40 45 50
0.3
0.5
0.7
0.9
1.1
1.3
19°C W.B
Capacity ratio
21.0
14.0
28.0
36.4
Piping equivalent length (m)
Total capacity of indoor unit
0 20 40 60 80 100 120 140 160 180
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00