55
12.2.3.3 - Installation
The hydraulic supply for each desuperheater is delivered in
parallel.
The hydraulic connection on the desuperheater water inlet and
outlets must not generate any local mechanical stress on the
exchangers. If necessary, install flexible couplings.
Fit water flow rate balancing and control valves at the exchanger
outlet.
Balancing and control of the flow rates may be performed by
reading the pressure drop in the exchangers.
The pressure drop on each of these must be identical to the total
water flow rate given by the selection programme.
To adjust the balancing valves before starting up the system, refer
to the pressure drop curves below.
It is possible to fine-tune the water flow rate settings for each
desuperheater when the unit is running at full load by trying to
obtain water outlet temperatures which are strictly identical for
each of the circuits.
Desuperheater (plate heat exchanger pressure drop
curves)
1 Circuit with 1 compressor
2 Circuit with 2 compressors
3 Circuit with 3 compressors
4 Circuit with 4 compressors
Heat
e
xchanger
pr
essur
e
dr
op
, kP
a
1
10
100
0.1
1
10
Heat exchanger water flow rate, l/s
1
2
3
4
12.2.3.4 - Operation
The desuperheater water circuit pump (see standard diagram
– item 20, in the section on "Installation and operation of the
heat recovery with desuperheater option") can be operated
in conjunction with:
•
Start-up of the first unit compressor: terminal 37/38
•
Heating water requirement: output DO-01, terminal
491/492, on the EMM board.
A dedicated flow switch (item 29) can also be installed to
generate an alarm if there is a problem with the pump
(customer control system).
The volume of the desuperheater circuit water loop must be
as low as possible to be able to rapidly increase the temperature
during warm-up.
The minimum desuperheater water inlet temperature is 25°C.
This may require the use of a three-way valve (item 31), with
its controller and sensor controlling the minimum required
water inlet temperature.
It is essential for the desuperheater water loop to comprise a
valve and an expansion vessel which must be selected to take
the volume of the water loop and the maximum possible
temperature into account
(120°C), in the event that pump (item 20) stops running.
12.2.3.5 - Operating limits
Desuperheater
Minimum
Maximum
Entering water temperature at start-up
°C
25
(1)
75
Leaving water temperature during operation
°C
30
80
Air condenser
Minimum
Maximum
Outside operating temperature
°C
0
(2)
46
(1) The entering water temperature at start-up must not be lower than 25°C.
For installations with a lower temperature a three-way valve is necessary.
(2) The minimum outside temperature is 0°C; -20°C with the winter operation option.
12.2.3.6 - Control configuration with the desuperheater option
This configuration enables the user to enter a setpoint relating
to the minimum condensation temperature (default value =
30°C) to increase the heating capacity recovered for the
desuperheaters, if required.
In fact, the recovered heating capacity percentage in relation
to the total capacity released by the air-cooled exchanger
increase based on the saturated condensation temperature.
Refer to the control manual for adjustment of the minimum
saturated condensation temperature setpoint.
Other parameters directly affect the effective capacity
recovered from the desuperheater, which are mainly:
•
The unit's load rate, which governs whether it runs at full
load (100%) or at part load (depending on the number
of compressors the unit has per circuit).
•
The entering water temperature in the desuperheater,
depending on the unit's "Heating" or "Cooling" operating
modes:
-
in "Heating" mode, the entering water temperature
in the water type heat exchanger
-
in "Cooling" mode, the ambient temperature at the
air-cooled exchanger air inlet.
12.2.4 - Operation of 2 Master/Slave units (Option 58)
The customer must connect both units with a communication
bus using a 0.75 mm² twisted, shielded cable (contact the
manufacturer's Service for installation).
All parameters required for Master/Slave operation must be
configured by the Service configuration menu.
All remote controls of the Master/slave assembly (start/stop,
setpoint, load shedding, etc.) are managed by the unit
configured as the Master and must only be applied to the
Master unit.
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