32
11.1.6 - Control configuration with the desuperheater option
This configuration allows the user to enter a setpoint that is
relative to the minimum condensing temperature (default =
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 condenser increases in
proportion to the saturated condensing temperature.
For the control of the setpoint of the minimum saturated
condensing temperature please refet to the Pro-Dialog control
manual for the 30RQ units.
Other parameters directly affecting the effective capacity
reclaimed at the desuperheater are principally:
•
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 operating mode:
-
in heating mode the water heat exchanger entering
water temperature
-
in cooling mode the condenser entering air
temperature.
Coefficient of the heating capacity reclaimed at the
desuperheater based on the entering water
temperature at the desuperheater and the condenser
entering air temperature
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
40
45
50
55
60
A
B
C
Desuperheater (entering water temperature,°C
Coef
ficient of the r
eclaimed heating capacoty
A
Entering air temperature = 45 °C
B
Entering air temperature = 35 °C
C
Entering air temperature = 20 °C
11.2 - Option 241
During transport in a closed container the refrigerant charge
must be transferred to the air heat exchanger. This prevents that
the pressure in the water heat exchanger reaches the valve
calibration pressure during transport (if this happened, the
charge would be evacuated to the atmosphere and the unit
would be empty when it arrives on site).
For this reason the charge is transferred to and stored in the air
heat exchanger, and the liquid and discharge line valves are
closed.
The following precautions must be taken during installation:
1. Ensure that there is sufficient water flow in the water
heat exchanger.
2. Energise the unit.
3. Open the liquid line valves.
4. Open the EXV to return the charge to the water heat
exchanger; pressure equalisation must be verified by a
quick test procedure.
5. Open the discharge line valve.
Nominal conditions corresponding to coefficient = 1
Evaporator entering/leaving temperature = 12/7°C
Desuperheater entering/leaving temperature = 50/60°C
Condenser entering air temperature = 35°C (curve B)
