27
7.4 - Variable flow evaporator
Variable evaporator flow can be used in standard 30HXC 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 litres of water per kW instead of 3.25 l/kW.
7.5 - 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
baffled in order to ensure proper mixing of the liquid (water or
brine). Refer to the examples below.
7.6 - Cooler flow rate (l/s)
30HXC
Min.* (closed loop)
Max.**
080-090
5.2
20.8
100
6.5
25.9
110
7.4
29.6
120-130
8.3
33.4
140-155
9.4
37.8
175-190
11.5
45.9
200
14.1
56.3
230
16.3
65.2
260-285
18.3
73.4
310
20.9
83.7
345-375
23.0
91.9
* Based on a water velocity of 0.9 m/s.
** Based on a water velocity of 3.6 m/s.
7.7 - Condenser flow rate (l/s)
30HXC
Min.*
Max.**
Closed loop
Open loop
080-110
2.3
7.0
28.2
120-130
3.1
9.3
37.1
140-155
3.7
11.1
44.5
175-190
4.3
13.0
51.9
200
4.9
14.8
59.2
230-285
6.7
20.1
80.4
310-375
8.0
24.0
95.9
* 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.
Bad
Bad
Good
Good
NOTE: The compressor must not restart more than 6 times in an
hour.
Содержание 30HXC Series
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