Refrigeration apparatus with expander control for improved coefficient of performance

A refrigeration apparatus, comprising:

• a refrigerant circuit along which a compressor, a heat dissipator, an expander, and an evaporator are connected, for performing a refrigeration cycle by circulating a refrigerant in the refrigerant circuit, the refrigerant circuit including a bypass passageway connecting upstream and downstream sides of the expander and a bypass control valve for regulating refrigerant flow rate in the bypass passageway, the compressor and the expander being located in a single housing;
• an injection passageway through which a portion of the refrigerant flowing towards the expander from the heat dissipator in the refrigerant circuit is introduced into an internal communication passageway connecting a first expansion chamber to a second expansion chamber of the expander in the process of expansion;
• a flow rate control valve for regulating the refrigerant flow rate in the injection passageway;
• and
• a controller configured to perform a primary control operation including
• adjusting position of the flow rate control valve with the bypass control valve held in a fully closed state,
• the controller being further configured to perform an auxiliary control operation including
• adjusting position of the bypass control valve with the flow rate control valve held in a fully opened state when the flow rate control valve enters the fully opened state during the primary control operation, and
• resuming the primary control operation when the bypass control valve enters the fully closed state during the auxiliary control operation.

A method of controlling refrigerant flow in a refrigeration apparatus including a refrigerant circuit along which a compressor, a heat dissipator, an expander, and an evaporator are connected and performing a refrigeration cycle, a bypass passageway connecting upstream and downstream sides of the expander, and an injection passageway supplying a portion of the refrigerant into an internal communication passageway connecting a first expansion chamber to a second expansion chamber of the expander, the method comprising:

• determining whether a flow rate valve regulating refrigerant flow rate in the injection passageway is in a fully opened position;
• adjusting position of a bypass control valve regulating refrigerant flow rate in the bypass passageway based on said determining;
• determining whether the bypass control valve is in a fully closed position;
• and
• adjusting position of the flow rate valve based on the determining whether the bypass control valve is in the fully closed position.