Annular axial flow ribbed heat exchanger
A cylindrical, annular axial flow heat exchanger for use as a gas cooler in a thermal regenerative machine such as a Stirling engine is provided. The heat exchanger includes an outer shell of sufficient strength and thickness to withstand the pressure exerted by the working fluid and a tubular member positioned adjacent to and in contact with the outer shell, the tubular member having spaced apart sidewalls defining a flow passage therebetween. At least one of the sidewalls of the tubular member is embossed with ribs, the ribs being in contact with the inner surface of the outer shell thereby defining axially extending flow passages between the outer shell and tubular member along the circumference thereof for the flow of a second, gaseous fluid through the heat exchanger. The first fluid flows circumferentially through tubular member, while the second fluid flows axially between the outer shell and the tubular member.
1. A heat exchanger comprising:
an outer shell having an outer surface and an inner surface, the outer shell defining a generally cylindrical wall extending along an axis between a first and second end;
a tubular member positioned adjacent to the inner surface of the outer shell so as to form an annular gap therebetween, the tubular member having at least a portion in contact with the inner surface of the outer shell so as to provide a first set of one or more axially-extending spaces in the annular gap provided between the inner surface of the outer shell and the tubular member, the tubular member extending along said axis between opposed axial ends and having a first circumferential end and a second circumferential end, the first circumferential end abutting said second circumferential end so as to define an annular, tubular form, the tubular member following the circumference of the inner surface of said outer shell, and defining an open, interior space;
the tubular member having first and second spaced apart walls defining a first flow passage therebetween for the flow of a first fluid through said heat exchanger, the first flow passage extending from said first circumferential end to said second circumferential end and defining a maximum circumferential length generally corresponding to the distance between the first circumferential end and the second circumferential end of said tubular member;
an inlet opening extending through the outer shell and the first sidewall of said tubular member proximal to said first circumferential end of said tubular member, the inlet opening being in fluid communication with said first flow passage for delivering said first fluid to said first flow passage;
an outlet opening extending through the outer shell and the first sidewall of the tubular member proximal to said second circumferential end, the outlet opening being in fluid communication with the first flow passage for discharging said first fluid from said first flow passage;
a second fluid flow passage comprising at least the first set of one or more axially-extending spaces formed between the inner surface of said outer shell and the tubular member, the second fluid flow passage having open, axially spaced ends for the flow of a second fluid through said heat exchanger;
wherein said inlet opening and said outlet opening are arranged at respective opposed axial ends of said tubular member, the first flow passage having both circumferential and axial flow directions so that fluid entering through the inlet opening in said first circumferential end of the tubular member at one axial end thereof flows the maximum circumferential length and axial length of the tubular member before exiting the heat exchanger through the outlet opening at said second circumferential end of the tubular member at the opposed axial end thereof; and
wherein said first and second circumferential ends of said tubular member are in the form of corresponding angled ends, each angled end defining an acute, outermost corner, the inlet and outlet openings being formed, respectively, in the acute, outermost corner of the corresponding angled end.
2. The heat exchanger as claimed in claim 1 , wherein the first sidewall of the tubular member comprises a series of outwardly protruding ribs forming said first set of axially-extending spaces between the first sidewall of the tubular member and the inner surface of the outer shell defining said second flow passage.
3. The heat exchanger as claimed in claim 1 , wherein a boss is formed in respective ends of the first sidewall of the tubular member, the inlet opening and the outlet opening extending through the respective boss, each boss having a sealing surface surrounding the respective inlet or outlet opening, the sealing surface contacting and sealing against the inner surface of the outer shell.
4. The heat exchanger as claimed in claim 1 , wherein the inlet and outlet openings in said tubular member are substantially aligned in the axial direction when said angled ends are arranged in their abutting, juxtaposed relationship.
5. The heat exchanger as claimed in claim 1 , further including an inner shell having an outer surface and an inner surface, the inner shell defining a generally cylindrical wall extending along said axis between a first and second end, the inner shell being positioned adjacent to and in contact with the second sidewall of the tubular member so as to provide a second set of one or more axially-extending spaces therebetween, the inner shell following the inner circumference of the tubular member and maintaining said open, interior space.
6. The heat exchanger as claimed in claim 5 , wherein the second sidewall of the tubular member comprises a series of ribs, said ribs forming said second set of axially-extending spaces between the second sidewall of the tubular member and the outer surface of the inner shell, said second set of axially extending spaces forming part of said second flow passage.
7. The heat exchanger as claimed in claim 6 , wherein the second fluid flowing through the heat exchanger is split between the first set of axially extending spaces formed between the outer shell and the tubular member and the second set of axially extending spaces formed between the inner shell and the tubular member.
8. The heat exchanger as claimed in 7 , wherein said first set of axially extending spaces are oriented in a first diagonal direction and wherein said second set of axially extending spaces are oriented in a second diagonal direction generally opposite to said first diagonal direction.
9. The heat exchanger as claimed in claim 1 , wherein the first and second circumferential ends are formed with corresponding tabs and recesses to ensure proper alignment of the first and second circumferential ends when said ends are arranged in juxtaposition forming said tubular member.
10. The heat exchanger as claimed in claim 1 , wherein the tubular member is comprised of first and second mating, elongate plates having opposed ends, the first and second plates each comprising a central portion surrounded by a peripheral flange for sealingly joining to the corresponding peripheral flange on the mating first or second plate, the first and second plates defining said first and second spaced-apart sidewalls of said first flow passage, the opposed ends of the first and second plates forming the first and second circumferential ends of the tubular member.
11. The heat exchanger as claimed in claim 10 , wherein the central portions of the first and second plates are embossed with ribs, the ribs being spaced-apart by corresponding trough regions, the ribs on the first plate being oriented in a first, diagonal direction and the ribs on the second plate being oriented in a second, diagonal direction, opposite to said first direction, the ribs on the first plate contacting the inner surface of the outer shell so as to define the first set of axially extending spaces therebetween, the corresponding trough regions on the first and second plates contacting each other when said plates are arranged in their facing relation defining said first flow passage, the first flow passage thereby forming a tortuous fluid path through the tubular member.
12. The heat exchanger as claimed in claim 11 , wherein a boss is formed in respective ends of the first plate, the inlet opening and the outlet opening extending through the respective boss, each boss having a sealing surface surrounding the respective inlet or outlet opening, the sealing surface contacting and sealing against the inner surface of the outer shell.
13. The heat exchanger as claimed in claim 12 , wherein said opposed ends of said first and second plates are angled, the angled ends of said first plate corresponding to and mating with the angled ends of said second plate, the corresponding angled ends of said first and second plates forming the angled first and second circumferential ends of said tubular member.
14. The heat exchanger as claimed in claim 13 , wherein the inlet and outlet openings in said first plate are substantially aligned in the axial direction when said angled ends of said tubular member are positioned in their abutting, juxtaposed relationship.
15. The heat exchanger as claimed in claim 11 , further including an inner shell having an outer surface and an inner surface, the inner shell defining a generally cylindrical wall extending along said axis between a first and second end, the inner shell being positioned adjacent to and in contact with the second plate of the tubular member so as to provide a second set of one or more axially-extending spaces therebetween, the inner shell following the inner circumference of the tubular member and maintaining said open, interior space.
16. The heat exchanger as claimed in claim 15 , wherein the second set of one or more axially-extending spaces is formed by the ribs on the second plate of the tubular member and the outer surface of the inner shell, said second set of one or more axially extending spaces forming part of said second flow passage.
17. The heat exchanger as claimed in claim 12 , wherein the angled ends of the first and second plates are formed with corresponding tabs and recesses to ensure proper alignment of the first and second circumferential ends of the tubular member when said first and second plates are formed into their generally cylindrical tubular form.
18. The heat exchanger as claimed in claim 1 , wherein the outer shell has a thickness to contain an inner gas pressure of at least about 4 bar.
19. The heat exchanger as claimed in claim 1 , wherein the first fluid is a liquid coolant and the second fluid is a gas.
20. The heat exchanger as claimed in claim 1 , wherein the heat exchanger is incorporated in a Stirling engine, components of the Stirling engine being received in said open, interior space.
21. A heat exchanger comprising:
an outer shell having an outer surface and an inner surface, the outer shell defining a generally cylindrical wall extending along an axis between a first and second end,
a tubular member positioned adjacent to the inner surface of the outer shell so as to form an annular gap therebtween, the tubular member having at least a portion in contact with the inner surface of the outer shell so as to provide a first set of one or more axially-extending spaces in the annular gap provided between the inner surface of the outer shell and the tubular member, the tubular member extending along said axis between opposed axial ends and having a first circumferential end and a second circumferential end, the first circumferential end abutting said second circumferential end so as to define an annular, tubular form, the tubular member following the circumference of the inner surface of said outer shell, and defining an open, interior space;
the tubular member having first and second spaced apart walls defining a first flow passage therebetween for the flow of a first fluid through said heat exchanger, the first flow passage extending from said first circumferential end to said second circumferential end and defining a maximum circumferential length generally corresponding to the distance between the first circumferential end and the second circumferential end of said tubular member;
an inlet opening extending through the outer shell and the first sidewall of said tubular member proximal to said first circumferential end of said tubular member, the inlet opening being in fluid communication with said first flow passage for delivering said first fluid to said first flow passage;
an outlet opening extending through the outer shell and the first sidewall of the tubular member proximal to said second circumferential end, the outlet opening being in fluid communication with the first flow passage for discharging said first fluid from said first flow passage;
a second fluid flow passage comprising at least the first set of one or more axially-extending spaces formed between the inner surface of said outer shell and the tubular member, the second fluid flow passage having open, axially spaced ends for the flow of a second fluid through said heat exchanger;
wherein said inlet opening and said outlet opening are arranged at respective opposed axial ends of said tubular member, the first flow passage having both circumferential and axial flow directions so that fluid entering through the inlet opening in said first circumferential end of the tubular member at one axial end thereof flows the maximum circumferential length and axial length of the tubular member before exiting the heat exchanger through the outlet opening at said second circumferential end of the tubular member at the opposed axial end thereof; and
wherein the inlet and outlet openings in said tubular member are substantially aligned in the axial direction when said first and second circumferential ends are arranged in their abutting, juxtaposed relationship;
wherein said first and second circumferential ends of said tubular member are in the form of corresponding angled ends, each angled end defining an acute, outermost corner.