19
The maximum chilled water flow is shown in the table on
the next page. If the system flow exceeds the maximum
value, it can be bypassed as shown in the diagram.
1 Evaporator
2 Bypass
Variable evaporator flow can be used in standard chillers.
The 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 litres
of water per kW instead of 2.5 l/kW.
Whichever the system, the water loop minimum capacity is
given by the formula:
Capacity = Cap (kW) x N Litres
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 can be 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.
Units with hydronic module incorporate an expansion
tank that limits the water volume. The table below gives
the maximum loop volume for pure water or ethylene
glycol with various system concentrations, as well as the
static pressures. If the maximum volume is insufficient,
compared to the minimum system water loop volume, an
additional expansion tank must be added to the system.
Pure water 2400 1600 1200 3960 2640 1980
10% ethylene glycol 1800 1200 900 2940 1960 1470
20% ethylene glycol 1320 880 660 2100 1400 1050
30% ethylene glycol 1080 720 540 1740 1160 870
40% ethylene glycol 900 600 450 1500 1000 750
30RB 162-262 “B” standard units
162 2.8 13.9
182 2.8 13.9
202 2.8 14.3
232 3 14.3
262 3.5 14.3
30RB 162-262 “B” with option 280 and 30RB 302-802
2.8 28.1
2.8 28.1
2.8 28.1
3 26.7
3.5 26.7
3.9 26.7
4.4 29.4
4.9 29.4
5.2 29.4
5.8 31.1
6.1 31.1
6.9 31.1
7.9 50.6
8.7 50.6
9.6 50.6
10.3 50.6
* The maximum ow rate corresponds to a pressure loss of 100 kPa (heat
exchanger without hydronic module).
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