Patent ID: 8424296

Claim:
A heat exchanger having a first end with a first gas flow opening and a second end with a second gas flow opening, wherein the first and second ends of the heat exchanger are spaced apart along a gas flow axis, and wherein the heat exchanger comprises: an inner shell defining an inner gas flow passage extending along the gas flow axis, wherein the inner gas flow passage has a first open end and a second open end, wherein the first open end of the inner gas flow passage is in flow communication with the first gas flow opening of the heat exchanger; an intermediate shell surrounding the inner shell, wherein a space between the inner shell and the intermediate shell defines an intermediate gas flow passage extending along the gas flow axis, wherein the intermediate gas flow passage has a first open end and a second open end, and wherein the second open end of the intermediate gas flow passage is in flow communication with the second open end of the inner gas flow passage; an outer shell surrounding the intermediate shell, wherein a space between the intermediate shell and the outer shell defines an outer gas flow passage extending along the gas flow axis, wherein the outer gas flow passage has a first open end and a second open end, wherein the first open end of the outer gas flow passage is in flow communication with the first open end of the intermediate gas flow passage and the second open end of the outer gas flow passage is in flow communication with the second gas flow opening of the heat exchanger; and a coolant flow passage defined by a cooling jacket attached to an outer surface of the outer shell, the coolant flow passage having an inlet and an outlet and extending along the gas flow axis, wherein the coolant flow passage is in heat exchange communication with the outer gas flow passage; wherein the cooling jacket includes a pair of manifolds, one of the manifolds having an interior communicating with a coolant inlet opening formed in the outer shell, and the other of the manifolds having an interior communicating with a coolant outlet opening formed in the outer shell; and wherein the heat exchanger further comprises a fitting block including coolant fittings which are in communication with the coolant inlet and outlet openings of the outer shell.