Abstract: A refrigeration apparatus uses supercritical range refrigerant, and includes a multi-stage compression mechanism, a heat source-side heat exchanger, a usage-side heat exchanger, a switching mechanism switchable between cooling and heating operation states, and a second-stage injection tube. The second-stage injection tube branches off refrigerant, which has radiated heat in the heat source-side heat exchanger or the usage-side heat exchanger, and returns the refrigerant to the second-stage compression element. Refrigerant is prevented from returning to the second-stage compression element through the second-stage injection tube at least during a beginning of a reverse cycle defrosting operation, which is performed to defrost the heat source-side heat exchanger by switching the switching mechanism to the cooling operation state.

Abstract: A refrigeration apparatus includes a compression mechanism, a heat source-side heat exchanger, a usage-side heat exchanger, a switching mechanism and an intermediate heat exchanger. Refrigerant discharged from a first-stage compression element is sequentially compressed by a second-stage compression element. Each of the heat source-side heat exchanger and the usage-side heat exchanger functions an evaporator or radiator. The switching mechanism is configured to switch between a cooling operation state and a heating operation state. The intermediate heat exchanger is configured to cool refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element when the switching mechanism has been set to the cooling operation state, and to evaporate refrigerant whose heat is radiated in the usage-side heat exchanger when the switching mechanism has been set to the heating operation state.

Abstract: A refrigeration apparatus includes a compression mechanism, a heat source-side heat exchanger, a usage-side heat exchanger and an intercooler. The compression mechanism has compression elements arranged so that refrigerant discharged from a first-stage compression element is sequentially compressed by a second-stage compression element. The intercooler is connected to an intermediate refrigerant tube arranged and configured to draw refrigerant discharged from the first-stage compression element into the second-stage compression element. The intercooler is arranged and configured to cool the refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element.

Abstract: A refrigeration apparatus includes a compression mechanism, a heat source-side heat exchanger, a usage-side heat exchanger, an intercooler, an intercooler bypass tube and an intake return tube. The compression mechanism has a plurality of compression elements configured so that refrigerant discharged from a first-stage compression element is sequentially compressed by a second-stage compression element. The intercooler is connected to an intermediate refrigerant tube configured to draw refrigerant discharged from the first-stage compression element into the second-stage compression element to cool the refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element. The intercooler bypass tube is connected to the intermediate refrigerant tube so as to bypass the intercooler.

Abstract: An air-conditioning apparatus uses carbon dioxide as a refrigerant, and includes comprises a two-stage-compression-type compression mechanism, a heat source-side heat exchanger, an expansion mechanism, a usage-side heat exchanger, and an intercooler. The intercooler uses air as a heat source. The intercooler is configured and arranged to cool refrigerant flowing through an intermediate refrigerant tube that draws refrigerant discharged from the first-stage compression element into the second-stage compression element. The intercooler is integrated with the heat source-side heat exchanger to form an integrated heat exchanger, with the intercooler disposed in an upper part of the integrated heat exchanger.

Abstract: A refrigerant circuit (11) includes an oil separator (60) configured to separate oil from high pressure refrigerant, and an oil feed circuit (70) configured to feed the oil separated in the oil separator (60) to a compression mechanism (20) so as to cool the refrigerant in the course of a compression phase of the compression mechanism (20). The oil feed circuit (70) includes a recovery mechanism (40) configured to recover energy of the oil separated in the oil separator (60). In the compression mechanism (20), the refrigerant is cooled by the oil, thereby reducing power of the compression mechanism (20). Simultaneously, in the recovery mechanism (40), power required to increase pressure of the oil in the compression mechanism (20) is recovered.

Abstract: A refrigeration apparatus uses a refrigerant that operates in a region including critical processes, and includes a compression mechanism having first and second compressors, a heat-source-side heat exchanger, an expansion mechanism, a utilization-side heat exchanger, an intercooler, and an intermediate refrigerant pipe. The first compressor has a first low-pressure compression element and a first high-pressure compression element to increase pressure of refrigerant more than the first low-pressure compression element. The second compressor has a second low-pressure compression element and a second high-pressure compression element to increase pressure of refrigerant more than the second low-pressure compression element. The intermediate refrigerant pipe causes refrigerant discharged by the first and second low-pressure compression elements to pass through the intercooler and be sucked into first and second high-pressure the compression elements.

Abstract: A refrigeration apparatus uses a refrigerant that operates in a supercritical range. The refrigeration apparatus includes a compression mechanism, a heat source-side heat exchanger, an expansion mechanism, a usage-side heat exchanger, a switching mechanism, an intercooler, a bypass tube, and an injection tube. The switching mechanism is configured to switch between cooling and heating operation states. When the switching mechanism is switched to the cooling operation state to allow refrigerant to flow to the heat source-side heat exchanger and a reverse cycle defrosting operation for defrosting the heat source-side heat exchanger is performed, the refrigerant is caused to flow to the heat source-side heat exchanger, the intercooler and the injection tube. After the defrosting of the intercooler is detected as being complete, the bypass tube is used so as to ensure that the refrigerant does not flow to the intercooler and the injection valve is controlled so that the opening degree is increased.

Abstract: A refrigeration apparatus uses a refrigerant that operates in a supercritical range. The refrigeration apparatus includes a compression mechanism, a heat source-side heat exchanger, an expansion mechanism, a usage-side heat exchanger, a switching mechanism, an intercooler which functions as a cooler of refrigerant discharged from a first-stage compression element of the compression mechanism and drawn into a second-stage compression element of the compression mechanism, and an intercooler bypass tube. The switching mechanism is configured to switch between cooling and heating operation states in which refrigerant is circulated differently. When a defrosting operation for defrosting the heat source-side heat exchanger is performed, refrigerant flows to the heat source-side heat exchanger and the intercooler. After defrosting of the intercooler is detected as being complete, the intercooler bypass tube is used to ensure that the refrigerant does not flow to the intercooler.

Abstract: A refrigeration apparatus uses a refrigerant that operates in a supercritical range, and includes a compression mechanism, a heat source-side heat exchanger, an expansion mechanism, a usage-side heat exchanger, an intercooler and an intermediate oil separation mechanism. The compression mechanism has a plurality of compression elements, and is configured and arranged so that refrigerant discharged from a first-stage compression element is sequentially compressed by a second-stage compression element. The intercooler is configured and arranged to cool refrigerant flowing through an intermediate refrigerant tube that draws refrigerant discharged from the first-stage compression element into the second-stage compression element. The intermediate oil separation mechanism is configured and arranged to separate a refrigeration oil from the refrigerant discharged from the first-stage compression element.

Abstract: A refrigeration device includes a compression mechanism, a radiator, a first expansion mechanism, a second expansion mechanism, an evaporator, a first internal heat exchanger, a branch pipe, a third expansion mechanism, and a second internal heat exchanger. The first internal heat exchanger causes heat to be exchanged between refrigerant that flows from the radiator to the inflow side of the first expansion mechanism, and refrigerant that flows from the evaporator to the compression mechanism. The branch pipe branches from a third refrigerant pipe for connecting the radiator and the second expansion mechanism, and merges with the second refrigerant pipe. A third expansion mechanism is provided to the branch pipe. The second internal heat exchanger causes heat to be exchanged between refrigerant that flows out from the first expansion mechanism, and refrigerant that flows out from the third expansion mechanism.

Abstract: A refrigeration system comprises a refrigerant circuit (10) in which a compressor (21), an outdoor heat exchanger (24) and an indoor heat exchanger (33) are connected to operate on a refrigeration cycle, and an oil recovery container (40) connected to the suction side of the compressor (21), and carries out a recovery operation for circulating refrigerant through the refrigerant circuit (10) to recover oil into the recovery container (40). The refrigeration system further comprises: a compressor control section (50) for stepwise increasing the operating capacity of the compressor (21) in an initial stage of the recovery operation so that the refrigerant temperature in the low pressure side of the refrigerant circuit (10) reaches or exceeds a predetermined value; and a fan control section (70) for continuously driving an indoor fan (33a) at least during a time period when the compressor (21) is driven.

Abstract: A refrigeration system (10) includes: a refrigerant circuit (15) including a low-pressure stage compressor (21) variable in displacement and a high-pressure stage compressor (31) variable in displacement and operating in a two-stage compression refrigeration cycle; and a controller (100) for controlling the operation of the refrigeration system (10). The controller (100) includes a first control section (101) and a second control section (102). The first control section (101) controls the operating capacity of the low-pressure stage compressor (21) to adapt to the load of the refrigeration capacity.

Abstract: A refrigerant circuit (15) is provided with a low-pressure stage oil separator (26) for separating refrigerating machine oil out of refrigerant discharged from a low-pressure stage compressor (21) and returning it to the suction side of the low-pressure stage compressor (21), and a high-pressure stage oil separator (36) for separating refrigerating machine oil out of refrigerant discharged from a high-pressure stage compressor (31) and returning it to the suction side of the high-pressure stage compressor (31). The efficiency of oil separation of the low-pressure stage oil separator (26) is set lower than that of the high-pressure stage oil separator (36).

Abstract: Disposed is a contaminant recovery receptacle (40) which is connected, through an inflow pipe (42) and an outflow pipe (43), to the suction side of a compressor (21). The inflow pipe (42) has an exit end which opens towards the inner bottom of the recovery receptacle (40). The outflow pipe (43) has an entrance end which is situated above the exit end of the inflow pipe (42) in the recovery receptacle (40). Firstly, a preliminary operation is carried out which causes refrigerant to circulate in a refrigerant circuit (10) for a predetermined length of time so that gas-liquid two-phase refrigerant flows into the recovery receptacle (40). Thereafter, a recovery operation is carried out, which causes refrigerant to circulate in the refrigerant circuit (10) so that gas refrigerant flows into the recovery receptacle (40). As a result, contaminants are recovered in the recovery receptacle (40).

Abstract: After a refrigerant circuit (10) is formed by connecting a user side circuit (12) and a heat source side circuit (11) by means of a communication pipe (45), a compressor (21) is driven to circulate refrigerant in the refrigerant circuit (10) in a communication pipe cleaning step. Circulation of the refrigerant in the refrigerant circuit (10) peels off oxide which has been deposited on the inner face of the communication pipe (45) by brazing in the communication pipe forming step. The peeled oxide is forced to flow by the refrigerant to be collected on the upstream side of the compressor (21) in the heat source side circuit (11).

Abstract: The capacity of a compressor (21) in cleaning operation is set based on a Froude number Fr. The Froude number Fr expresses a ratio of an inertial force of a gas refrigerant flowing through a gas side communication pipe (70) to a gravity working on a liquid in the gas side communication pipe (70). The capacity of the compressor (21) in the cleaning operation is set so that the Froude number Fr is larger than 1, whereby the inertial force of the gas refrigerant flowing through the gas side communication pipe (70) becomes larger than the gravity working on the liquid in the gas side communication pipe (70) which contains mineral oil and foreign matters. In this connection, the liquid containing the mineral oil and the foreign matters is pushed up by the gas refrigerant even in a perpendicularly extending portion of the gas side communication pipe (70).

Abstract: A refrigeration apparatus is provided with a vapor compression type refrigerant circuit. With this apparatus, reliability from the standpoint of the pipe cleaning mode of the apparatus is improved. The air conditioning system has a main refrigerant circuit that has a compressor, a heat-source-side heat exchanger, and a user-side heat exchanger. The air conditioning system also has a contaminant collecting device provided on the intake side of the compressor (21). The contaminant collecting device is equipped with a contaminant collecting container, an inlet pipe, an outlet pipe, and a main opening/closing device. The contaminant collecting container separates contaminants from refrigerant flowing in the intake gas pipe toward the compressor when the refrigerant is directed through it. The inlet and outlet pipes are each provided with a return preventing shape for preventing contaminants that have accumulated inside the pipes from returning to the intake gas pipe.

Abstract: A refrigeration system comprises a refrigerant circuit (10) in which a compressor (21), an outdoor heat exchanger (24) and an indoor heat exchanger (33) are connected to operate on a refrigeration cycle, and an oil recovery container (40) connected to the suction side of the compressor (21), and carries out a recovery operation for circulating refrigerant through the refrigerant circuit (10) to recover oil into the recovery container (40). The refrigeration system further comprises: a compressor control section (50) for stepwise increasing the operating capacity of the compressor (21) in an initial stage of the recovery operation so that the refrigerant temperature in the low pressure side of the refrigerant circuit (10) reaches or exceeds a predetermined value; and a fan control section (70) for continuously driving an indoor fan (33a) at least during a time period when the compressor (21) is driven.

Abstract: Disposed is a contaminant recovery receptacle (40) which is connected, through an inflow pipe (42) and an outflow pipe (43), to the suction side of a compressor (21). The inflow pipe (42) has an exit end which opens towards the inner bottom of the recovery receptacle (40). The outflow pipe (43) has an entrance end which is situated above the exit end of the inflow pipe (42) in the recovery receptacle (40). Firstly, a preliminary operation is carried out which causes refrigerant to circulate in a refrigerant circuit (10) for a predetermined length of time so that gas-liquid two-phase refrigerant flows into the recovery receptacle (40). Thereafter, a recovery operation is carried out, which causes refrigerant to circulate in the refrigerant circuit (10) so that gas refrigerant flows into the recovery receptacle (40). As a result, contaminants are recovered in the recovery receptacle (40).