Precision Air Conditioning
SmartCool
TM
– D
Precision Air Conditioning
21
Installation, Maintenance and Commissioning Manual :6877419 02/2013
Liquid Sub Cooling
The degree of liquid sub cooling required to prevent flashing of liquid refrigerant can be calculated by
the following method.
Given the following as an example:
•
Refrigerant R410A
•
Condensing temperature (54.4°C)
•
Liquid lift 20m
•
Piping friction loss 0.21 bar
•
Losses through valves and fittings 0.5 Bar
1.
Determine the pressure drop due to pipe friction = 0.21 Bar
2.
Pressure drop due to valves and fittings = 0.5 Bar
3.
Pressure loss due to liquid lift = height x 0.115 = 20 x 0.115 = 2.3 bar
Note:- At normal liquid temperatures the static pressure loss due to elevation at the top of a liquid lift
0.115 bar/m
Therefore:- Total pressure loss in liquid line = 3.01bar
Condensing pressure @ Condensing temperature (54.4°C) = 34 Bar
Total pressure loss in liquid line = 3.01 Bar
Nett pressure at Expansion valve = 34 - 3.01 = 30.99 bar
Saturation temperature at the Nett pressure at expansion valve (30.99 bar) = 52°C
(from Refrigerant tables)
Sub cooling required
= Condensing temperature — Saturation temperature at the Nett pressure at expansion valve
= 54.4 - 52 = 2.4 °C
Therefore liquid sub cooling required to prevent liquid flashing = 2.4 °C
Packaged Unit Pre-Charged Refrigerant Volumes
Indoor unit
kg / circuit
HGRH kg / circuit
Indoor unit
kg / circuit
HGRH kg / circuit
SC19D055-W2W2
5.75
5.90
SC19D033-W2F0
5.68
5.83
SC19D070-W2W2
7.32
7.47
SC19D038-W2F0
7.25
7.40
SC19D080-W2W2
7.32
7.47
SC19D045-W2F0
7.25
7.40
SC25D080-W2W2
8.51
8.70
SC19D064-W2F0
9.60
9.81
SC25D090-W2W2
10.85
11.07
SC19D070-W2F0
9.61
9.81
SC25D100-W2W2
10.85
11.07
SC19D076-W2F0
9.61
9.82
SC31D100-W2W2
12.04
12.30
SC25D045-W2F0
8.44
8.63
SC31D120-W2W2
12.04
12.30
SC25D050-W2F0
10.78
11.00
SC31D130-W2W2
12.04
12.31
SC25D055-W2F0
10.78
11.00
SC19D033-W2C0
5.68
5.83
SC25D067-W2F0
10.79
11.04
SC19D038-W2C0
7.25
7.40
SC25D073-W2F0
10.79
11.04
SC19D045-W2C0
7.25
7.40
SC25D080-W2F0
10.80
11.04
SC19D064-W2C0
9.60
9.81
SC31D055-W2F0
11.96
12.23
SC19D070-W2C0
9.61
9.81
SC31D065-W2F0
11.97
12.23
SC19D076-W2C0
9.61
9.82
SC31D075-W2F0
11.97
12.23
SC25D045-W2C0
8.44
8.63
SC31D077-W2F0
11.97
12.26
SC25D050-W2C0
10.78
11.00
SC31D080-W2F0
11.98
12.27
SC25D055-W2C0
10.78
11.00
SC31D083-W2F0
11.98
12.27
SC25D067-W2C0
10.79
11.04
SC25D073-W2C0
10.79
11.04
SC25D080-W2C0
10.80
11.04
SC31D055-W2C0
11.96
12.23
SC31D065-W2C0
11.97
12.23
SC31D075-W2C0
11.97
12.23
SC31D077-W2C0
11.97
12.26
SC31D080-W2C0
11.98
12.27
SC31D083-W2C0
11.98
12.27
(1)Fitted with optional hot gas re-heat
Ins
ta
lla
tion
