Carrier AquaForce 30XB series - Evaporator Water Flow Rate

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6.4-Variableowevaporator
Variable evaporator ow can be used in standard 30XB chillers.
The chillers maintain a constant leaving water temperature under
all ow conditions. For this to happen, the minimum 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.
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
bafed in order to ensure proper mixing of the liquid (water or
brine). Refer to the examples below.
Connection to a buffer tank
Bad
Bad
Good
Good
6.6 - Maximum system water volume
Units with hydraulic 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 insufcient, compared to the minimum system water
loop volume, an additional expansion tank must be added to the
system.
30XB & XBP Sizes 250 to 450 500
Static pressure bar 1 2 2,5 1 2 2,5
Pure water l 2400 1600 1200 3960 2640 1980
10% EG l 1800 1200 900 2940 1960 1470
20% EG l 1320 880 660 2100 1400 1050
30% EG l 1080 720 540 1740 1160 870
40% EG l 900 600 450 1500 1000 750
EG : Ethylene Glycol
6.7-Evaporatorwaterowrate
30XB & 30XBP Minimum flow rate
(1)
(l/s) Maximum flow rate
(2)
(l/s)
250 3,6 37,5
300 4,0 40,5
350 4,3 40,5
400 5,3 34,1
450 6,0 36,9
500 6,7 42,0
600 8,1 45,0
700 8,9 56,1
750 9,6 59,1
800 10,4 67,1
850 11,0 67,1
900 11,8 73,9
1000 13,1 83,9
1100 15,1 87,8
1200 16,4 126,5
1300 17,5 92,9
1400 16,4 132,1
1500 18,8 107,4
1550 19,9 109,4
1700 22,0 107,4
(1) Minimum ow rate for maximum allowable water temperature difference conditions
(10K) under Eurovent conditions
(2) Maximum ow rate for a pressure drop of 100 kPa in the exchanger”
6 - APPLICATION DATA