Refrigeration apparatus
A compressor unit of a refrigerant circuit includes a compressor, an oil separator, an oil return pipe, an oil return valve, and a discharge temperature sensor. A refrigeration apparatus includes a controller. The controller performs a detection operation. The detection operation is an operation of decreasing the opening degree of the oil return valve and detecting whether or not gas refrigerant is flowing through the oil return pipe based on a change in the measured value by the discharge temperature sensor after the decreasing of the opening degree of the oil return valve as compared to the measured value by the discharge temperature sensor before the decreasing of the opening degree of the oil return valve.
1 . A refrigeration apparatus including a refrigerant circuit having a compressor unit and configured to perform a refrigeration cycle,
the compressor unit having a compressor with a compression mechanism configured to compress and discharge refrigerant, an oil separator configured to separate refrigerating machine oil from a gas refrigerant discharged from the compressor, an oil return pipe connecting the oil separator to a suction pipe of the compressor, an oil return valve provided for the oil return pipe, and a discharge temperature sensor configured to measure a temperature of the gas refrigerant discharged from the compression mechanism,
the refrigeration apparatus comprising:
a controller configured to perform a detection operation of decreasing an opening degree of the oil return valve and detecting whether or not gas refrigerant is flowing through the oil return pipe based on a change in a measured value by the discharge temperature sensor after the decreasing of the opening degree of the oil return valve as compared to a measured value by the discharge temperature sensor before the decreasing of the opening degree of the oil return valve.
2 . The refrigeration apparatus of claim 1 , wherein
the detection operation performed by the controller includes an operation of determining that the gas refrigerant is flowing through the oil return pipe when a first condition is satisfied, and
the first condition is a condition that the measured value by the discharge temperature sensor after the decreasing of the opening degree of the oil return valve is smaller, by a predetermined value or more, than the measured value by the discharge temperature sensor before the decreasing of the opening degree of the oil return valve.
3 . The refrigeration apparatus of claim 2 , wherein
the controller keeps the opening degree of the oil return valve at the opening degree after the decreasing or further decreasing of the opening degree of the oil return valve when the first condition is satisfied in the detection operation.
4 . The refrigeration apparatus of claim 1 , wherein
the detection operation performed by the controller includes an operation of determining that the gas refrigerant is flowing through the oil return pipe when a second condition is not satisfied, and
the second condition is a condition that the measured value by the discharge temperature sensor after the decreasing of the opening degree of the oil return valve is greater, by a predetermined value or more, than the measured value by the discharge temperature sensor before the decreasing of the opening degree of the oil return valve.
5 . The refrigeration apparatus of claim 4 , wherein
the controller returns the opening degree of the oil return valve to the opening degree before the decreasing or increasing of the opening degree of the oil return valve as compared to the opening degree before the decreasing when the second condition is satisfied in the detection operation.
6 . The refrigeration apparatus of claim 1 , wherein
the compressor has an electric motor configured to drive the compression mechanism, and a casing housing the compression mechanism and the electric motor, and
the discharge temperature sensor measures a temperature of gas refrigerant discharged from the compression mechanism into an internal space of the casing before passing by the electric motor.
7 . The refrigeration apparatus of claim 1 , wherein
the compressor unit of the refrigerant circuit includes a plurality of compressor units, and
the controller performs the detection operation for each of the plurality of compressor units.
8 . The refrigeration apparatus of claim 7 , wherein
the plurality of compressor units provided for the refrigerant circuit includes a first compressor unit and a second compressor unit, and
the controller performs a transfer operation of transferring refrigerating machine oil from the first compressor unit to the second compressor unit when the controller determines, in the detection operation, that the gas refrigerant is flowing through the oil return pipe only in the second compressor unit out of the first compressor unit and the second compressor unit.
9 . The refrigeration apparatus of claim 8 , wherein
the controller performs, as the transfer operation, an operation of increasing a rotational speed of a compressor of the first compressor unit and decreasing a rotational speed of a compressor of the second compressor unit.
10 . The refrigeration apparatus of claim 1 , wherein
when the controller determines that the gas refrigerant is flowing through the oil return pipe in the detection operation in a case where a rotational speed of the compressor is a predetermined value or more, the controller performs a recovery operation of returning refrigerating machine oil staying outside the compressor unit to the compressor unit.
11 . The refrigeration apparatus of claim 1 , wherein
the controller
performs a recovery operation of returning refrigerating machine oil staying outside the compressor unit to the compressor unit when a predetermined recovery condition is satisfied, and
does not perform the recovery operation even if the recovery condition is satisfied when it is not determined in the detection operation that the gas refrigerant is flowing through the oil return pipe when a rotational speed of the compressor is a predetermined value or less.