2
2
- 20
Design of Mini Multiset
2. System Design
Checking of limit density
Density limit is determined on the basis of the size of a
room using an indoor unit of minimum capacity. For
instance, when an indoor unit is used in a room (floor
area 7.43 m
2
×
ceiling height 2.7 m = room volume
20.06 m
3
), the graph at right shows that the minimum
room volume should be 14.1 m
3
(floor area 5.2 m
2
) for
refrigerant of 4.238 kg. Accordingly, openings such as
louvers are required for this room.
<Determination by calculation>
Overall refrigerant charge amount for the air conditioner: kg
(Minimum room volume for indoor unit: m
3
)
=
4.238 (kg) + 3.5 (kg)
= 0.39 (kg/m
3
)
≥
0.3 (kg/m
3
)
20.06 (m
3
)
Therefore, openings such as louvers are required for
this room.
●
Obtain charge amount for each tubing size
Note that the charge amounts per 1 meter are different for each liquid tubing size.
ø9.52
→
LA + LB + LC + LD
: 65 m
×
0.056 kg/m = 3.64 kg
ø6.35
→
1
+
2
+
3
+
4
+
5
: 23 m
×
0.026 kg/m = 0.598 kg
Total
4.238 kg
Additional refrigerant charge amount is 4.238 kg.
Be sure to check the limit densi-
ty for the room in which the
indoor unit is installed.
CAUTION
●
Example of each tubing length
Main tubing
Distribution joint tubing
LA = 40 m
Indoor side
LB = 5 m
1
= 5 m
4
= 6 m
LC = 5 m
2
= 5 m
5
= 5 m
LD = 15 m
3
= 2 m
LN
L1
L2
LC
LB
LA
Main tube of unit
1st branch
model
7
model
9
model
12
model
16
model
18
Unit distribution tube
1
2
3
n–1
n
Example:
40
35
30
25
20
15
10
5
0
108.0
94.5
81.0
67.5
54.0
40.5
27.0
13.5
0
10
20
30
Total amount of refrigerant
Min. indoor floor area
(when the ceiling is 2.7 m high)
m
2
kg
Range below the
density limit
of 0.3 kg/m
3
(countermeasures
not needed)
Range above
the density limit
of 0.3 kg/m
3
(countermeasures
needed)
m
3
