Positive displacement expander and fluid machinery

A positive displacement expander comprising:

• an expansion mechanism in which a high-pressure fluid is expanded in an expansion chamber to generate power;
• a communication path which diverges from a fluid inflow side of the expansion chamber and communicates with a suction/expansion process position of the expansion chamber;
• and
• a circulation control mechanism disposed in the communication path for regulating a flow rate of the fluid, wherein
• the expansion mechanism is provided with a backflow prevention mechanism for preventing the fluid from flowing from the expansion chamber into the communication path, and
• the circulation control mechanism is comprised of an electric-operated valve capable of adjusting the degree of opening.

A positive displacement expander comprising:

• an expansion mechanism in which a high-pressure fluid is expanded in an expansion chamber to generate power;
• a communication path which diverges from a fluid inflow side of the expansion chamber and communicates with a suction/expansion process position of the expansion chamber;
• and
• a circulation control mechanism disposed in the communication path for regulating a flow rate of the fluid, wherein
• the expansion mechanism is provided with a backflow prevention mechanism for preventing the fluid from flowing from the expansion chamber into the communication path, and
• the circulation control mechanism is comprised of an electromagnetically opening/closing valve capable of opening and closing.

A positive displacement expander comprising:

• an expansion mechanism in which a high-pressure fluid is expanded in an expansion chamber to generate power;
• a communication path which diverges from a fluid inflow side of the expansion chamber and communicates with a suction/expansion process position of the expansion chamber;
• and
• a circulation control mechanism disposed in the communication path for regulating a flow rate of the fluid, wherein
• the expansion mechanism is provided with a backflow prevention mechanism for preventing the fluid from flowing from the expansion chamber into the communication path, and
• the circulation control mechanism is comprised of a differential pressure regulating valve which opens when differential pressure between pressure of the fluid during an expansion process in the expansion chamber and pressure on the fluid outflow side is greater than a predetermined value.

A positive displacement expander comprising:

• an expansion mechanism in which a high-pressure fluid is expanded in an expansion chamber to generate power;
• a communication path which diverges from a fluid inflow side of the expansion chamber and communicates with a suction/expansion process position of the expansion chamber;
• and
• a circulation control mechanism disposed in the communication path for regulating a flow rate of the fluid, wherein
• the expansion mechanism is provided with a backflow prevention mechanism for preventing the fluid from flowing from the expansion chamber into the communication path, and
• the expansion mechanism is configured to carry out an expansion process of a vapor compression type refrigeration cycle in which the high pressure becomes super-critical pressure.

A positive displacement expander comprising:

• an expansion mechanism in which a high-pressure fluid is expanded in an expansion chamber to generate power;
• a communication path which diverges from a fluid inflow side of the expansion chamber and communicates with a suction/expansion process position of the expansion chamber;
• and
• a circulation control mechanism disposed in the communication path for regulating a flow rate of the fluid, wherein
• the expansion mechanism is provided with a backflow prevention mechanism for preventing the fluid from flowing from the expansion chamber into the communication path, and
• the expansion mechanism is configured to be a rotary expansion mechanism in which rotation power is recovered by means of expansion of the fluid.

A fluid machinery comprising:

• a positive displacement expander;
• a motor;
• and
• a compressor driven by the positive displacement expander and the motor in order to compress a fluid, the positive displacement expander, the motor, and the compressor being provided in a casing,
• wherein the positive displacement expander comprises:
• an expansion mechanism in which the compressed fluid is expanded in an expansion chamber to generate power;
• a communication path which diverges from a fluid inflow side of the expansion chamber and communicates with a suction/expansion process position of the expansion chamber;
• and
• a circulation control mechanism disposed in the communication path for regulating a flow rate of the fluid,
• wherein the expansion mechanism is provided with a backflow prevention mechanism for preventing the fluid from flowing from the expansion chamber into the communication path.