Coaxial economizer assembly and method

A method of flowing fluid through a coaxial economizer in chiller system comprising the steps of:

• a. receiving a fluid from an upstream compressor stage of a multistage compressor into a coaxial economizer;
• said coaxial economizer comprising:
• i. an inner housing and an outer housing having a common longitudinal axis;
• said outer housing having an inlet for receiving a fluid from the upstream compressor stage and an outlet for conveying a fluid to a downstream compressor stage of a multistage compressor;
• ii. a flow chamber forming a fluid flow path about the inner housing;
• iii. a flash chamber for flashing fluid in a liquid state to a gas state;
• and
• iv. a flow passage between said flash chamber and the flow chamber for conveying a flashed gas from the flash chamber to the flow chamber;
• wherein the flashed gas conveyed from the flash chamber and the fluid received from the inlet of the outer housing mix along the fluid flow path toward the outlet of the outer housing;
• b. flashing a liquid to a gas within the flash chamber;
• c. passing the gas within the flash chamber through the flow passage to the flow chamber;
• and
• d. mixing and flowing the gas conveyed from the flash chamber and the fluid received from the inlet of the outer housing along the fluid flow path to the outlet of the coaxial economizer.