Fujitsu AOU48RLXFZ - Page 25

2. MODEL SELECTION
EXAMPLE 2

(When the connecting capacity for indoor unit is 100% or less)
Branch
box
Branch
box
Outdoor unit
Indoor unit 1 Indoor unit 2 Indoor unit 3 Indoor unit 4
Room 1 Room 2 Room 3 Room 4
Main Piping length, L1=32.8ft. (10m) Branch Piping length, L1=32.8ft. (10m)
Design conditions

Design temperature
●
Indoor : 75°F DB / 63°F WB (23.9°C DB / 17.2°C WB)
Outdoor : 86°F DB (30°C DB)
Pipe length
●
Main piping length : L1=32.8ft. (10m)
Branch piping length : L2=32.8ft. (10m)
Operation mode: Cooling
●
Selection of indoor unit

Room 1 Room 2 Room 3 Room 4
Remark
A-1 Cooling heat load Btu 8000 8000 11000 11000
A-2 Indoor unit models
ASU9 ASU9 ASU12 ASU12
A-3 Rated capacity (TC
in
)
r
Btu 9000 9000 12000 12000
Cooling
A-4 Total rated capacity ∑(TC
in
)
r
Btu 9000 x 2 + 12000 x 2 = 42000
Sum of A-3
A-5
Connecting indoor unit
capacity (Cp)
42000 / 48000 = 87.5%
(80%≤Cp≤130%)
A-6
Capacity change rate by
suction temperature of
indoor unit
46.1 / 48.0 = 0.960
See Fig.1
A-7
Total capacity at design
temperature ∑(TC
in
)
d
Btu 42000 x 0.960 = 40320
(A-4) x (A-6)
Calculate the Maximum capacity of outdoor unit

Remark
B-1 Outdoor unit model AOU48RLXFZ
B-2 Rated capacity (TC
out
)
r
Btu 48000
Cooling
B-3 Capacity change rate by temperature conditions 47.4 / 48.0 = 0.988
See Fig.1
B-5 Compensation coefficient of pipe length 0.98 x 0.942 = 0.923
See 5-1.
B-6 Maximum capacity of outdoor unit (TC
out
)
c
Btu 48000 x 0.988 x 0.923 = 43770
(B-2) x (B-3) x (B-5)
Decide system capacity

Remark
C-1 System capacity Btu 40320
Smaller one of (A-7)
and (B-6)
Calculate actual capacity of each indoor unit

Room 1 Room 2 Room 3 Room 4
Remark
Actual capacity of each indoor
unit
Btu 8640 8640 11520 11520
(A-3) x (C-1) / (A-4)
Actual capacity of all indoor units is larger than cooling heat load of each room.
- (02 - 06) -
MODEL SELECTION MODEL SELECTION