Abstract: The low-side pressure of a refrigeration cycle and the refrigerant temperature at the exit of a gas cooler under reference operating conditions are employed as a reference low pressure and a reference refrigerant temperature, respectively, and the high-side pressure of the refrigeration cycle at which the COP of the refrigeration cycle reaches a maximum value under the reference operating conditions is employed as a reference high pressure.

Abstract: A positive displacement expander includes a volume change mechanism (90) for changing the volume of a first fluid chamber (72) of an expansion mechanism (60). The expansion mechanism (60) includes a first rotary mechanism (70) and a second rotary mechanism (80) each having a cylinder (71, 81) containing a rotor (75, 85). The first fluid chamber (72) of the first rotary mechanism (70) and a second fluid chamber (82) of the second rotary mechanism (80) are in fluid communication with each other to form an actuation chamber (66). Meanwhile, the first fluid chamber (72) of the first rotary mechanism (70) is smaller than the second fluid chamber (82) of the second rotary mechanism (80). The volume change mechanism (90) includes an auxiliary chamber (93) fluidly communicating with the first fluid chamber (72) and an auxiliary piston (92) for changing the volume of the auxiliary chamber (93). The auxiliary chamber (93) is in fluid communication with the first fluid chamber (72) of the first rotary mechanism (70).

Abstract: The upper and lower end surfaces (67b, 67c) of a rotary piston (67) are formed with annular seal grooves (91) extending along the annular end surfaces (67b, 67c), and an annular lip seal (92) is fitted in each of the seal grooves (91). Thereby, the lubricating oil fed from oil feed grooves (49) in the shaft (40) rarely flows from between the upper and lower end surfaces (67b, 67c) of the rotary piston (67) and front and rear heads (61, 62) and into the fluid chamber (65) of a cylinder (63), so that shortage of lubricating oil is eliminated.

Abstract: A refrigerant circuit (10) of a refrigeration apparatus is filled up with carbon dioxide as a refrigerant. In the refrigerant circuit (10), a first compressor (21) and a second compressor (22) are arranged in parallel. The first compressor (21) is connected to both an expander (23) and a first electric motor (31), and is driven by both of the expander (23) and the first electric motor (31). On the other hand, the second compressor (22) is connected only to a second electric motor (32), and is driven by the second electric motor (32). In addition, the refrigerant circuit (10) is provided with a bypass line (40) which bypasses the expander (23). The bypass line (40) is provided with a bypass valve (41). And, the capacity of the second compressor (22) and the valve opening of the bypass valve (41) are regulated so that the COP of the refrigeration apparatus is improved after enabling the refrigeration apparatus to operate properly in any operation conditions.

Abstract: In a compression/expansion unit (30) serving as a fluid machine, both a compression mechanism (50) and an expansion mechanism (60) are housed in a single casing (31). An oil supply passageway (90) is formed in a shaft (40) by which the compression mechanism (50) and the expansion mechanism (60) are coupled together. Refrigeration oil accumulated in the bottom of the casing (31) is drawn up into the oil supply passageway (90) end is supplied to the compression mechanism (50) and to the expansion mechanism (60). Surplus refrigeration oil, which is supplied to neither of the compression and expansion mechanisms (50) and (60), is discharged out of the terminating end of the oil supply passageway (90) which opens at the upper end of the shaft (40). Thereafter, the surplus refrigeration oil flows into an oil return pipe (102) from a lead-out hole (101) and is returned back towards a second space (39).

Abstract: Disclosed is a displacement type expansion machine. In the displacement type expansion machine, a communicating passage (72) for allowing fluid communication between an expansion-process intermediate position and an outflow position in an expansion chamber (62) is provided thereby to allow the fluid at the outflow side to return to the expansion chamber (62). Such arrangement prevents the pressure of the expansion chamber (62) from being lowered to an excessive extent in predetermined operating conditions, thereby avoiding the drop in power recovery efficiency.

Abstract: A first and a second expansion and compression machine (30, 40) having different volume ratios (Vc/Ve) are connected in parallel to a refrigerant circuit (10) of a refrigeration apparatus. Expanders (31, 41) of the expansion and compression machines (30, 40) are connected in parallel. Compressors (32, 42) of the expansion and compression machines (30, 40) are also connected in parallel. Upon variation in the operating condition of the refrigeration apparatus, the ratio of rotation speed between the expansion and compression machines (30, 40) is controlled by a controller (60). This, as a result, allows the refrigeration apparatus to operate at a COP close to an ideal condition.

Abstract: In an air conditioner (10), a refrigerant adjustment tank (14) is disposed in a refrigerant circuit (11). The refrigerant adjustment tank (14) is disposed just after an expander (16). In the refrigerant circuit (11), a liquid injection line (31) and a gas injection line (33) are arranged. When a liquid side control valve (32) is placed in the open state, liquid refrigerant in the refrigerant adjustment tank (14) is supplied through the liquid injection line (31) to the suction side of a compressor (15). On the other hand, when a gas side control valve (34) is placed in the open state, gas refrigerant in the refrigerant adjustment tank (14) is supplied through the gas injection line (33) to the suction side of the compressor (15).

Abstract: A refrigeration system includes an internal heat exchanger (23) capable of controlling the temperature of refrigerant flowing towards an expander (12). Upon change of the operating conditions, the internal heat exchanger (23) controls the temperature of the refrigerant to control the specific volume or the flow rate of the refrigerant, thereby eliminating imbalance between the flow rate through a compressor (11) and the flow rate through the expander (12). In a cooling operation in which the refrigerant circulation amount is larger than in a heating operation, the cooling capacity of the internal heat exchanger (23) is enhanced as compared to that in the heating operation, thereby increasing the flow rate of refrigerant into the expander (12) without part of the refrigerant bypassing the expander (12). This prevents the COP of the refrigeration system from being deteriorated.

Abstract: An outdoor heat exchanger (23), an indoor heat exchanger (24), a compression/expansion unit (30), and other circuit components are connected in a refrigerant circuit (20). The compression/expansion unit (30) includes a compression mechanism (50), an electric motor (45), and an expansion mechanism (60). In addition, the refrigerant circuit (20) has an injection pipeline (26). When an injection valve (27) is opened, a portion of high pressure refrigerant after heat dissipation flows into the injection pipeline (26) and is introduced into an expansion chamber (66) of the expansion mechanism (60) in the process of expansion. In the expansion mechanism (60), power is recovered from both high pressure refrigerant introduced into the expansion chamber (66) from an inflow port (34) and high pressure refrigerant introduced into the expansion chamber (66) from the injection pipeline (26).

Abstract: Two rotary mechanism parts (70, 80) are provided in a rotary expander (60). The first rotary mechanism part (70) is smaller in displacement volume than the second rotary mechanism part (80). A first low-pressure chamber (74) of the first rotary mechanism part (70) and a second high-pressure chamber (83) of the second rotary mechanism part (80) are fluidly connected together by a communicating passageway (64), thereby forming a single expansion chamber (66). High-pressure refrigerant introduced into the first rotary mechanism part (70) expands in the expansion chamber (66). An injection passageway (37) is fluidly connected to the communicating passageway (64). When an motor-operated valve (90) is placed in the open state, high-pressure refrigerant is introduced into the expansion chamber (66) also from the injection passageway (37). This makes it possible to inhibit the drop in power recovery efficiency, even in the condition that causes the actual expansion ratio to fall below the design expansion ratio.

Abstract: A rotary type expander (60) is provided with two rotary mechanism parts (70, 80). These two rotary mechanism parts (79, 80) differ from each other in displacement volume. The outflow side of the first rotary mechanism part (70) of small displacement volume is fluidly connected to the inflow side of the second rotary mechanism part (80) of large displacement volume. In addition, the process in which the volume of a first low-pressure chamber (74) in the first rotary mechanism part (70) decreases is in synch with the process in which the volume of a second high-pressure chamber (83) in the second rotary mechanism part (80) increases. Refrigerant at high pressure is first introduced into a first high-pressure chamber (73) of the first rotary mechanism part (70). Thereafter, this high-pressure refrigerant passes through a communicating passage (64) and then flows by way of the first low-pressure chamber (74) into the second high-pressure chamber (83) while expanding.

Abstract: Disclosed is a displacement type expansion machine. In the displacement type expansion machine, a communicating passage (72) for allowing fluid communication between an expansion-process intermediate position and an outflow position in an expansion chamber (62) is provided thereby to allow the fluid at the outflow side to return to the expansion chamber (62). Such arrangement prevents the pressure of the expansion chamber (62) from being lowered to an excessive extent in predetermined operating conditions, thereby avoiding the drop in power recovery efficiency.

Abstract: A refrigerant circuit (10) of a refrigeration apparatus is filled up with carbon dioxide as a refrigerant. In the refrigerant circuit (10), a first compressor (21) and a second compressor (22) are arranged in parallel. The first compressor (21) is connected to both an expander (23) and a first electric motor (31), and is driven by both of the expander (23) and the first electric motor (31). On the other hand, the second compressor (22) is connected only to a second electric motor (32), and is driven by the second electric motor (32). In addition, the refrigerant circuit (10) is provided with a bypass line (40) which bypasses the expander (23). The bypass line (40) is provided with a bypass valve (41). And, the capacity of the second compressor (22) and the valve opening of the bypass valve (41) are regulated so that the COP of the refrigeration apparatus is improved after enabling the refrigeration apparatus to operate properly in any operation conditions.