Table of Contents
Advertisement
10.7.6 - Installation
The water supply of each desuperheater is arranged in parallel.
The water connections on the desuperheater water inlets and outlets
must not cause any mechanical local constraint at the heat exchangers.
If necessary, install flexible connection sleeves.
Install water flow control and balancing valves at the heat exchanger
outlet. Water flow control and balancing can be done by reading
the pressure drop in the heat exchangers. This pressure drop must
be identical on all of them with the total water flow rate given by
the "Electronic catalogue" selection program.
Refer to the pressure drop curves below to perform the adjustment
of the balancing valves before starting up the installation. It is
possible to fine-tune the variable water flow control for each
desuperheater when the unit is running at full load, attempting to
obtain outlet water temperatures which are completely identical
on each circuit.
Desuperheater
(plate heat exchanger pressure drop curves)
Heat exchanger water flow rate, l/s
1
Circuit with 1 compressor
2
Circuit with 2 compressors
Operation of the pump (see typical diagram - item 20 of chapter
10.7.5) of the desuperheater water circuit can be linked to:
1-
The start-up of the first compressor of the unit : terminal
block 37/38
2-
The heat water need : Output DO-01 terminal block
n°491/492 of the EMM board (option 156)
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 so that the temperature can increase rapidly when the
unit is started up. The minimum entering water temperature at the
desuperheater is 25°C. A three-way valve (item 31) may be
necessary with a controller, as the sensor controlling the minimum
temperature requires water at the inlet.
The desuperheater water loop must include a damage limitation
accessory in case of a fire and an expansion tank. When selecting
these, consider the water loop volume and the maximum
temperature (120°C) when pump operation is stopped (item 20).
54
1
2
3
3
Circuit with 3 compressors
4
Circuit with 4 compressors
1
10.7.7 - Operating range
Cooling mode
Water heat exchanger (evaporator)
Entering water temperature at start-up*
Leaving water temperature during operation
Entering water temperature at shut-down
Desuperheater
Entering water temperature at start-up**
Leaving water temperature during operation
Entering water temperature at shut-down
Air heat exchanger (condenser)
Entering air temperature***
Available static pressure
Heating mode
Water heat exchanger (condenser)
Entering water temperature at start-up
Leaving water temperature during operation
Entering water temperature at shut-down
Desuperheater
Entering water temperature at start-up**
Leaving water temperature during operation
Entering water temperature at shut-down
Air heat exchanger (evaporator)
Entering air temperature
Available static pressure
Note: Do not exceed the maximum operating temperature.
*
For an application that requires operation below 6.8°C, contact Carrier.
**
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.
*** For operation down to -20°C the unit must be equipped with option 28 (winter operation).
In addition the unit must either be equipped with the frost protection option or the water
loop must be protected by the installer by adding a frost protection solution.
Maximum outside temperatures: During storage and transport of the 30RQM/30RQP
units the minimum and maximum temperatures must not exceed -20°C and +48°C. It is
recommended to observe these temperatures during transport by container.
10.7.8 - Control configuration with the desuperheater option
This configuration allows the user to enter a setpoint that is
relative to the minimum condensing temperature (default =
4
30°C) to increase the heating capacity reclaimed at the
desuperheaters, if required. The percentage of the reclaimed
heating capacity compared with the total capacity rejected by
the air heat exchanger increases in proportion to the saturated
condensing temperature.
For the control of the setpoint of the minimum saturated
condensing temperature please refer to the Pro-Dialog control
manual for the 30RQM/30RQP units.
Other parameters directly affecting the effective capacity
reclaimed at the desuperheater are principally:
10
•
The unit load rates, that decide whether the unit
operates at full load (100%) or part load (depending on
the number of compressors per unit circuit).
•
The water entering temperature in the desuperheater and
depending on the unit heating or cooling opera-ting mode:
-
In heating mode the water heat exchanger entering
water temperature
-
In cooling mode the air heat exchanger entering air
temperature.
Minimum
Maximum
°C
6.8*
30
°C
5
15
°C
-
60
°C
25
60
°C
30
80
°C
3
60
°C
0
46
Pa
0
0
Minimum
Maximum
°C
8
45
°C
20
50
°C
3
60
°C
25
60
°C
30
80
°C
3
60
°C
-10
35
Pa
0
0
Advertisement
Table of Contents
