Specifications
19
Variable flow evaporator
Variable evaporator flow can be used in standard 30HXC and 30GX
chillers. The chillers maintain a constant leaving water temperature
under all flow conditions. For this to happen, the minimum 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.
System minimum water volume
Whichever the system, the water loop minimum capacity is given
by the formula :
Capacity = Cap (kW) x N Liters
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 baffled in order to ensure proper mixing of the liquid
(water or brine). Refer to the examples below.
NOTE
The compressor must not restart more than 6 times in an hour.
BAD
GOOD BAD GOOD
Cooler flow rate (l/s)
30HXC Min.* Max.**
075-085 6.6 26.2
095 6.7 27.0
105 9.1 36.2
115-125 9.3 37.0
135-145 11.2 44.7
160-170 14.1 56.3
185 16.4 65.5
215 17.0 67.9
250-280 21.0 84.0
300 22.2 88.7
315-370 26.8 107.2
Condenser flow rate (l/s)
30HXC Min.* Max.**
Closed loop Open loop
075-095 2.5 7.5 29.9
105 2.9 8.8 35.0
115 3.1 9.3 37.2
125 3.2 9.7 38.8
135-145 3.8 11.4 45.6
160 4.6 13.8 55.3
170 4.9 14.9 59.8
185 5.3 16.0 64.0
215-280 7.2 21.5 86.2
300-370 7.9 23.6 94.5
30GX Min.* Max.**
080-090 5.8 21.0
105-115 6.3 26.5
125-135 7.4 31.8
150 9.1 36.0
160-175 10.8 41.9
205 12.4 46.0
225 14.5 54.0
250-265 16.5 60.0
280-300 18.0 66.0
325-350 21.0 72.0
* Based on a water velocity of 0.9 m/s.
** Based on a water velocity of 3.6 m/s.
* Based on a water velocity of 0.3 m/s in a closed loop and 0.9 m/s in an open loop.
** Based on a water velocity of 3.6 m/s.