19
6.7 -
Variable flow evaporator
Variable evaporator flow can be used. The pump drive can be
managed by unit control (0/10V output on terminal 90+ / 90-) The
controlled flow rate must be higher than the minimum flow given
in the table of permissible flow rates and must not vary by more
than 10% per minute.
If the flow rate changes more rapidly, the system should contain
a minimum of 6.5 liters of water per kW instead of 3.25 l/kW.
6.8 -
System minimum water volume
Whichever the system, the water loop minimum volume is given
by the formula:
Volume = Cap (kW) x N litres
Application
N
Normal air conditioning
3,25
Process type cooling
6,5
where Cap is the nominal system cooling capacity (kW) at the
nominal operating conditions of the installation.
This volume is necessary for stable operation. It is often necessary
to add a buffer water tank to the circuit in order to achieve the
required volume. The tank must itself be internally baffled in order
to ensure proper mixing of the liquid (water or brine). Refer to the
examples below.
Conection to buffer tank
Bad
Good
Bad
Good
6.9 -
Evaporator pressure drop curves
Units with two evaporator passes (standard):
30XW-PZE / 30XWHPZE
10
20
30
40
50
60
70
80
90
100
110
120
0
10
20
30
40
50
60
70
80
90 100 110 120
4
2
1
3
5
Pressure drop, kPa
Water flow rate, l/s
Legend
1
301
4
801, 901
2
401, 451
5
1001, 1101
3
551, 601, 651
Units with one evaporator pass (option 100C):
30XW-PZE / 30XWHPZE
4
2
1
3
5
3
6
9
12
15
18
21
24
27
30
33
36
0
10
20
30
40
50
60
70
80
90 100 110 120
Pressure drop, kPa
Water flow rate, l/s
Legend
1
301
4
801, 901
2
401, 451
5
1001, 1101
3
551, 601, 651
6.10 -
Condenser pressure drop curves
Units with two condenser passes (standard):
30XW-PZE / 30XWHPZE
10
20
30
40
50
60
70
80
90
100
110
120
0 10 20 30 40 50 60 70 80 90 100 110 120
4
2
1
3
5
Pressure drop, kPa
Water flow rate, l/s
Legend
1
301
4
801, 901
2
401, 451
5
1001, 1101
3
551, 601, 651
Units with one condenser pass (option 100C):
30XW-PZE / 30XWHPZE
3
6
9
12
15
18
21
24
27
30
33
36
0
10
20
30
40
50
60
70
80
90
100 110
4
2
1
3
5
Pressure drop, kPa
Water flow rate, l/s
Legend
1
301
4
801, 901
2
401, 451
5
1001, 1101
3
551, 601, 651
6 - APPLICATION DATA
