Thermal relief mechanism for combination-type heat exchangers

1. A multi-fluid heat exchanger for transferring heat between a first fluid and a common fluid in one part of the heat exchanger and between a second fluid and the common fluid in a second part of the heat exchanger, the heat exchanger comprising:

a first elongated header pipe having a plurality of tube receiving openings spaced along a length of the first header pipe; a second elongate header pipe having a plurality of tube receiving openings spaced along a length of the second header pipe;

a first core section comprising a plurality of parallel, spaced tubes, each of the tubes having a first end and a second end, with the first end received in a corresponding one of the tube receiving openings of the first header pipe and the second end received in a corresponding one of the tube receiving openings of the second header pipe to direct the first fluid between the first and second header pipes through an interior of the tube;

a second core section comprising a plurality of parallel, spaced tubes, each of the tubes having a first end and a second end, with the first end received in a corresponding one of the tube receiving openings of the first header pipe and the second end received in a corresponding one of the tube receiving openings of the second header pipe to direct the second fluid between the first and second header pipes through an interior of the tube, the second core spaced from the first core along the lengths of the first and second header pipes; and

a pair of baffles located in the first header pipe at a location between the first and second cores to divide an interior of the first header pipe into a first fluid manifold for the first fluid and a second fluid manifold for the second fluid, the first header pipe includes a cut portion located between the pair of baffles, the cut portion having at least a majority of a transverse cross section of the header pipe removed in comparison to the immediately adjacent transverse cross sections of the first header pipe, wherein the cut portion is sized so that any remaining part of the transverse cross section of the first header pipe at the cut portion is severed under thermal cycling of the heat exchanger during operation of the heat exchanger.

2. The heat exchanger of claim 1 wherein all of the transverse cross section of the first header pipe has been removed in the cut portion, so that the first header pipe is separated into two unconnected pieces.

3. The heat exchanger of claim 1 wherein one of the tube openings of the first header pipe is located at the cut portion.

4. The heat exchanger of claim 3 wherein the one of the tube openings of the first header pipe does not have a tube end received therein.

5. The heat exchanger of claim 3 wherein the cut portion is defined by at least one saw cut extending through a portion of the header pipe outside of the one of the tube openings.

6. The heat exchanger of claim 3 wherein the cut portion is defined by a saw cut extending through a side of the header pipe immediately opposite from the one of the tube openings.

7. The heat exchanger of claim 3 wherein the cut portion is defined by a saw cut extending through the one of the tube openings.

8. The heat exchanger of claim 1 wherein the cut portion is defined by a pair of saw cuts extending through opposite respective sides of the first header pipe.

9. The heat exchanger of claim 1 wherein the cut portion is characterized by the absence of any of the tube openings.

10. The heat exchanger of claim 1 further comprising another pair of baffles located in the second header pipe at a location between the first and second cores to divide an interior of the second header pipe into a first fluid manifold for the first fluid and a second fluid manifold for the second fluid, the second header pipe including a second cut portion located between the another pair of baffles, the second cut portion having at least a majority of a transverse cross section of the header pipe is removed in comparison to the immediately adjacent transverse cross sections of the first header pipe.

11. A method of making a multi-fluid heat exchanger for transferring heat between a first fluid and a common fluid in one part of the heat exchanger and between a second fluid and the common fluid in a second part of the heat exchanger, the method comprising the steps of:

a) providing a heat exchanger with first and second parallel flow core sections extending between a pair of elongated header tubes, with each of the tubes having a first fluid manifold for the first core section and a second fluid for the second core section;

b) providing a cut portion in one of the elongated headers at a location between the first and second manifolds, the cut portion having at least part of the header connecting the first and second manifolds of the header;

c) thermal cycling the heat exchanger to sever the at least part of the one of the elongated headers so that the first and second manifolds of the header are no longer connected at the cut portion.

12. The method of claim 11 wherein step b) comprises providing the cut portion after the first and second core seconds are assembled and brazed together with the pair of elongated headers.

13. The method of claim 11 wherein step b) comprises providing the cut portion before the first and second core seconds are assembled and brazed together with the pair of elongated headers.

14. A multi-fluid heat exchanger for transferring heat between a first fluid and a common fluid in one part of the heat exchanger and between a second fluid and the common fluid in a second part of the heat exchanger, the heat exchanger comprising:

a first elongated header pipe having a plurality of tube receiving openings spaced along a length of the first header pipe; a second elongate header pipe having a plurality of tube receiving openings spaced along a length of the second header pipe;

a first core section comprising a plurality of parallel, spaced tubes, each of the tubes having a first end and a second end, with the first end received in a corresponding one of the tube receiving openings of the first header pipe and the second end received in a corresponding one of the tube receiving openings of the second header pipe to direct the first fluid between the first and second header pipes through an interior of the tube;

a second core section comprising a plurality of parallel, spaced tubes, each of the tubes having a first end and a second end, with the first end received in a corresponding one of the tube receiving openings of the first header pipe and the second end received in a corresponding one of the tube receiving openings of the second header pipe to direct the second fluid between the first and second header pipes through an interior of the tube, the second core spaced from the first core along the lengths of the first and second header pipes; and

a pair of baffles located in the first header pipe at a location between the first and second cores to divide an interior of the first header pipe into a first fluid manifold for the first fluid and a second fluid manifold for the second fluid, the first header pipe includes a cut portion located between the pair of baffles, the cut portion having at least a majority of a transverse cross section of the header pipe removed in comparison to the immediately adjacent transverse cross sections of the first header pipe,

wherein there is a serpentine fin extending between the first and second cores and connected to both the first and second cores.

15. The heat exchanger of claim 14 wherein all of the transverse cross section of the first header pipe has been removed in the cut portion, so that the first header pipe is separated into two unconnected pieces.

16. The heat exchanger of claim 14 wherein one of the tube openings of the first header pipe is located at the cut portion.

17. The heat exchanger of claim 14 wherein the cut portion is defined by a pair of saw cuts extending through opposite respective sides of the first header pipe.

18. The heat exchanger of claim 17 wherein the cut portion is defined by at least one saw cut extending through a portion of the header pipe outside of the one of the tube openings.

19. The heat exchanger of claim 17 wherein the cut portion is defined by a saw cut extending through a side of the header pipe immediately opposite from the one of the tube openings.