Compressor floodback protection system
A climate-control system may include a compressor, a condenser, an evaporator, a first sensor, a second sensor, a third sensor, and a control module. The compressor may include a motor and a compression mechanism. The condenser receives compressed working fluid from the compressor. The evaporator is in fluid communication with the compressor and disposed downstream of the condenser and upstream of the compressor. The first sensor may detect an electrical operating parameter of the motor. The second sensor may detect a discharge temperature of working fluid discharged by the compression mechanism. The third sensor may detect a suction temperature of working fluid between the evaporator and the compression mechanism. The control module is in communication with the first, second and third sensors and may determine whether a refrigerant floodback condition is occurring in the compressor based on data received from the first, second and third sensors.
1. A system comprising:
a compressor having a shell, a compression mechanism disposed within the shell, and a motor driving the compression mechanism;
a first heat exchanger receiving compressed working fluid from the compressor;
a second heat exchanger in fluid communication with the compressor and the first heat exchanger;
a first sensor detecting a parameter indicative of a temperature of working fluid within the first heat exchanger;
a second sensor detecting a discharge temperature of fluid discharged from the compressor;
a third sensor detecting a suction temperature of fluid upstream of the compression mechanism and downstream of the first and second heat exchangers;
a fourth sensor detecting an oil temperature of oil in a sump defined by the shell; and
processing circuitry in communication with the first, second, third and fourth sensors and determining whether a refrigerant floodback condition is occurring and a severity of the refrigerant floodback condition based on data received from the first, second, third and fourth sensors.
2. The system of claim 1 , wherein the first sensor is a current sensor that measures a current of the motor.
3. The system of claim 1 , wherein the first sensor is a pressure sensor measuring a pressure of working fluid at a location along a high-pressure side of the system.
4. The system of claim 1 , wherein the only measured data used to detect the refrigerant floodback condition is data measured by the first, second and third sensors.
5. The system of claim 4 , wherein the processing circuitry determines whether a refrigerant floodback condition has occurred based on a comparison between a calculated discharge-superheat-value and a predetermined discharge-superheat-threshold.
6. The system of claim 5 , wherein the severity of the refrigerant floodback condition is determined based on a level of oil dilution in an oil sump disposed within the shell of the compressor.
7. The system of claim 6 , wherein the level of oil dilution is calculated using the equation:
log
10
(
P
)
=
a
1
+
a
2
T
+
a
3
T
2
+
log
10
(
ω
)
(
a
4
+
a
5
T
+
a
6
T
2
)
+
log
10
2
(
ω
)
(
a
7
+
a
8
T
+
a
9
T
2
)
,
wherein P is a pressure of gas immediately above an oil level in the oil sump within the compressor; wherein ω is the level of oil dilution; wherein T is a temperature of the oil in the oil sump; and wherein a 1 through a 9 are constants.
8. The system of claim 7 , wherein the severity of the refrigerant floodback condition is determined based on a comparison of the level of oil dilution and a dilution limit value.
9. The system of claim 8 , wherein the dilution limit value is determined based on a calculated condensing temperature and a calculated evaporating temperature.
10. The system of claim 9 , wherein the pressure (P) of gas immediately above the oil level is determined based on the suction temperature measured by the third sensor.
11. The system of claim 10 , wherein the processing circuitry issues a fault warning or a fault trip in response to determining the severity of the refrigerant floodback condition.
12. The system of claim 11 , wherein the compressor is a low-side scroll compressor.