Carrier Aquaforce 30XAS Series, Инструкции по установке, эксплуатации и обслуживанию

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6 - APPLICATION DATA
6.4 - Variable flow evaporator
Variable evaporator flow can be used in standard 30XAS chillers.
The chillers maintain a constant leaving water tem-perature 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.
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 baffled 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 insufficient, compared to the minimum system water
loop volume, an additional expansion tank must be added to the
system.
30XAS 242-482
Static pressure bar 1 2
Maximum water loop volume
l
Pure water 2400 1600
Ethylene glycol 10% 1800 1200
Ethylene glycol 20% 1320 880
Ethylene glycol 30% 1080 720
Ethylene glycol 40% 900 600
6.7 - Evaporator water flow rate
30XAS
Evaporator water flow rate, l/s
Min, flow rate Max, flow rate
(1)
242 3,2 30,7
282 3,7 30,7
342 4,4 30,7
442 5,8 41,0
482 6,5 41,0
(1) The maximum water flow rate corresponds to a pressure drop of 100 kPa.
6.8 - Evaporator pressure drop curve
Water flow rate, l/s
Pressure
drop,
kPa
Legend
1 30XAS 242-342
2 30XAS 442-482