Patent ID: 8079229

Claim:
A refrigerant vapor compression system for heating liquid, comprising: a refrigerant compression device wherein a refrigerant is compressed from a suction low pressure to a discharge high pressure; a refrigerant-to-liquid heat exchanger wherein high pressure refrigerant is received from a discharge port of said compression device and passes in heat exchange relationship with the liquid to be heated, whereby the high pressure refrigerant transfers heat to the liquid; an economizer heat exchanger having a first pass receiving a first portion of the refrigerant having traversing said refrigerant-to-liquid heat exchanger and a second pass receiving a second portion of the refrigerant having traversed said refrigerant-to-liquid heat exchanger, said first pass and said second pass operatively associated in heat exchange relationship whereby the first portion of the refrigerant having traversed said refrigerant-to-liquid heat exchanger transfers heat to the second portion of the refrigerant having traversed said refrigerant-to-liquid heat exchanger; a first expansion device wherein the first portion of the refrigerant having traversed said refrigerant-to-liquid heat exchanger and said first pass of said economizer heat exchanger is expanded to a first lower pressure; a second expansion device wherein the second portion of refrigerant having traversed said refrigerant-to-liquid heat exchanger is expanded to a second lower pressure; an evaporator wherein the first portion of the refrigerant having traversed said first expansion device passes in heat exchange relationship with a fluid to be cooled; and a refrigerant circuit comprising, a first flow path connecting said compression device, said refrigerant-to-liquid heat exchanger, said economizer heat exchanger and said evaporator in refrigerant flow communication in a refrigerant circulation flow circuit, a second flow path directing the second portion of refrigerant from the first flow path at a location upstream of said first expansion device through said second pass of said economizer heat exchanger to said compression device at an intermediate pressure stage in the compression process within said compression device, and a third flow path simultaneously directing a third portion of refrigerant from the second flow path to a location upstream of a suction inlet port of said compression device, wherein the second portion and the third portion enter the compression device at different locations.