Patent ID: 8356489

Claim:
A refrigerant system comprising: a compressor operable to compress a refrigerant and deliver the refrigerant to a downstream first heat exchanger, refrigerant from said first heat exchanger passing through an expander at which it expands and drives an expander element, and mechanical motion of said expander element being utilized to at least partially drive at least one other component, refrigerant flowing downstream of said expander passing through a second heat exchanger, and from said second heat exchanger back to said compressor through a compressor suction line; at least a portion of refrigerant tapped from an intermediate point in the expansion process in said expander, and returned through a return line to a location downstream of said second heat exchanger and upstream of said first heat exchanger; said returned refrigerant has been at least partially expanded in said expander; and a flow control device placed in said return line, said flow control device being operable to control the amount of returned refrigerant.