Patent ID: 7237602

Claim:
A heat exchanger for heat exchange among at least three fluids, comprising: a plurality of first heat exchanger tubes, each having a first-fluid passage formed therein to carry a first fluid; a plurality of second heat exchanger tubes each formed to cover one of the first heat exchanger tubes corresponding thereto, each one of the second heat exchanger tubes defining a second-fluid passage formed to carry a second fluid between an inner wall of the one of the second heat exchanger tubes and an outer wall of the one of the first heat exchanger tubes; a plurality of third heat exchanger tubes each formed to cover one of the second heat exchanger tubes corresponding thereto, each one of the third heat exchanger tubes defining a third-fluid passage formed to carry a third fluid between an inner wall of the one of the third heat exchanger tubes and an outer wall of the one of the second heat exchanger tubes; a pair of first tube plates provided on first and second ends of the first heat exchanger tubes; a pair of second tube plates provided on first and second ends of the second heat exchanger tubes; a pair of third tube plates provided on first and second ends of the second heat exchanger tubes; a first end ring extending between an outer edge of one of the first tube plates provided on the first ends of the first heat exchanger tubes and an outer edge of one of the second tube plates provided on the first ends of the second heat exchanger tubes, to define a second-fluid distribution chamber for distributing the second fluid into each second-fluid passage defined by each of the second heat exchanger tubes; a second end ring extending between an outer edge of the other of the first tube plates provided on the second ends of the first heat exchanger tubes and an outer edge of the other of the second tube plates provided on the second ends of the second heat exchanger tubes, to define a second-fluid collection chamber for collecting the second fluid from each second-fluid passage defined by each of the second heat exchanger tubes; a third end ring extending between an outer edge of one of the second tube plates provided on the first ends of the second heat exchanger tubes and an outer edge of one of the third tube plates provided on the first ends of the third heat exchanger tubes, to define a third-fluid distribution chamber for distributing the third fluid into each third-fluid passage defined by each of the third heat exchanger tubes; and a fourth end ring extending between an outer edge of the other of the second tube plates provided on the second ends of the second heat exchanger tubes and an outer edge of the other of the third tube plates provided on the second ends of the third heat exchanger tubes, to define a third-fluid collection chamber for collecting the third fluid from each third-fluid passage defined by each of the third heat exchanger tubes.