38
bearing then return to suction port of rotors through internal oil channel of compressor shell. All the two oil flow
mixed with refrigerant gas through rotors discharge back to oil separator. In cooling mode, the minority oil
accumulated in refrigerant liquid of evaporator go back to the bottom cavity of compressor through oil return
solenoid valve of oil return pipe; or in heating mode, the oil in the coil returns back to the compressor with
refrigerant suction gas while the oil return solenoid valve closed.
Oil supply check valve is a pressure activated valve. When the compressor operates, the discharge pressure
generated opens the check valve to allow the oil flow. When the compressor stops, the check valve is closed to
isolate the oil in oil separator from compressor.
Receiver
The receiver used to temporally store larger volume of refrigerant liquid in coil before mode switch from defrost
back to heating in order to avoid refrigerant liquid slugging to compressor that may cause the compressor
damage. Refer to
, the receiver solenoid valve status.
Table 7 Receiver solenoid valve status
Compressor running
Cooling mode (including
warmup, defrost)
Heating mode
Fill valve
Closed (de-energized)
Closed (de-energized)
Discharge valve
Open (de-energized)
Closed (energized)
Compressor stopped
Cooling shutdown
Heating shutdown
Fill valve
Closed (de-energized)
Closed (de-energized)
Discharge valve
Open (de-energized)
Closed (energized)
Partial Heat Recovery Option
The partial heat recovery is comprised of an auxiliary BPHE heat exchanger installed in the discharge line
between the oil separator and the reversing valve. The heat exchanger cools compressor discharge gas and
rejects the energy to a separate water loop for hot water applications. The unit can simultaneously produce chilled
and hot water. The heating capacity is driven by the cooling demand on the unit, the condensing temperature and
the flow rate through the heat exchanger.
The partial heat recovery includes:
• Brazed plate heat exchanger (BPHE)
•• Piping between the heat exchanger(s)
• Insulation of the heat exchanger(s) and water pipe
• Heater on partial heat recovery heat exchanger(s) and water pipe
Note
: UC800 does not monitor, implement and display any partial heat recovery mode and status. The partial
heat recovery controller should be designed and installed by user on field.
RTXC XE Operating Map
Cooling mode:
Water side heat exchanger (evaporator)
Min temperature (°C)
Max temperature (°C)
Entering water temperature (startup)
-
45
Leaving water temperature (running)
5
18
Air side heat exchanger (condenser)
Min temperature (°C)
Max temperature (°C)