22
401
501-551
651
701
851
901
0
10
20
30
40
10 20 30 40 50 60 70 80 90 100 110 120 130
Pressure drop, kPa
Water flow rate, L/s
Pressure drop, kPa
3
Legend:
1 401
2 501
3 551
4 651
5 701
6 851
7 901
Variable evaporator ow can be used as standard with
30XAV-ZE chillers. The chillers maintain a constant
leaving water temperature under all ow conditions. For
this to happen, the ow rate must be higher than the
minimum ow given in the table of permissible ow rates
and must not vary by more than 10% per minute.
If the ow rate changes more rapidly, the system should
contain a minimum of 6.5 litres of water per kW instead of
3.25 l/kW.
The ow can also be controlled by the unit through option
299 : Variable Water Flow Control. This option allows the
unit to control an external pump in order to maintain a
constant inlet/outlet temperature difference, a constant
outlet pressure or an unoccupied mode.
6.5 - System minimum water volume
Whichever the system, the water loop minimum capacity is
given by the formula:
Capacity = 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 and accurate
temperature control.
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 bafed in order to ensure proper mixing
of the liquid (water or brine). Refer to the examples below.
Mauvais
Bon
Mauvais
Bon
30XAV-ZE
Dual pass Single pass
Minimum Maximum Minimum Maximum
401
7.1 51.5 17 57.6
501
8.9 63.1 21 69.1
551
8.9 63.1 21 80.6
651
11.2 73.1 25.5 92.1
701
12.4 82.2 28.3 109.4
851
13.1 93.9 31.1 120.9
901
15.4 95.5 34.2 132.5
* Standard evaporator and coolant = water
6.7 - Evaporator pressure drop curve
4 5 6 7
Note: Standard evaporator and coolant = water
Bad
Bad
Good
Good
Sizes 401 to 901
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