Annular heat exchanger

1. A heat exchanger comprising:

a header; and

an annular core fluidly connected to the header, the annular core comprising:

an inner diameter defining a radially inner face;

an outer diameter defining a radially outer face;

first flow channels arranged in a first set of layers between the inner diameter and the outer diameter, each of the first flow channels comprising:

a first inlet;

a first outlet;

a first axial region extending between the first inlet and the first outlet; and

a first curved region between the first axial region and the first outlet; and

second flow channels arranged in a second set of layers between the inner diameter and the outer diameter and interleaved with the first flow channels, each of the second flow channels comprising:

a second inlet;

a second outlet;

a second axial region extending between the second inlet and the second outlet;

a second curved region between the second inlet and the second axial region; and

a third curved region between the second axial region and the second outlet;

wherein each of the second flow channels has a first cross-sectional shape at the second curved region and the third curved region and a second cross-sectional shape at the second axial region.

2. The heat exchanger of claim 1 ,

wherein each of the second flow channels is defined by a tangential width at the second axial region, and the tangential widths increase from an innermost one of the second set of layers to an outermost one of the second set of layers with respect to the inner diameter of the annular core.

3. The heat exchanger of claim 2 ,

wherein the tangential widths increase monotonically.

4. The heat exchanger of claim 1 ,

wherein the first and second flow channels form a lattice at the first and second axial regions such that, at the first axial region, each of the first flow channels has a circular cross-sectional area defined by a cross-sectional diameter and, at the second axial region, each of the second flow channels has a contoured cross-sectional area.

5. The heat exchanger of claim 4 ,

wherein the cross-sectional diameters of the first flow channels are equal.

6. The heat exchanger of claim 1 ,

wherein the first outlet of each of the first flow channels is positioned along the radially outer face of the annular core.

7. The heat exchanger of claim 1 ,

wherein the second inlet of each of the second flow channels and the second outlet of each of the second flow channels are positioned along the radially inner face of the annular core.

8. The heat exchanger of claim 1 ,

wherein the first flow channels are configured to receive or discharge a first fluid and the second flow channels are configured to receive or discharge a second fluid; and

wherein the first fluid and the second fluid flow through the heat exchanger in generally opposite directions, such that the heat exchanger has a counter-flow arrangement.

9. The heat exchanger of claim 1 ,

wherein the heat exchanger is a condenser.

10. The heat exchanger of claim 1 ,

wherein the inner face of the heat exchanger mates with a radial interface of an air cycle machine in an environmental control system.

11. The heat exchanger of claim 10 ,

wherein the second inlet of each of the second flow channels and the second outlet of each of the second flow channels are configured to permit direct fluid communication with components of the air cycle machine at the radial interface.

12. The heat exchanger of claim 1 ,

wherein the annular core is a single, monolithic, additively manufactured unit.

13. The heat exchanger of claim 1 ,

wherein the annular core further comprises a standoff that extends from the inner face; and

wherein the header is connected to the annular core at the standoff.

14. The heat exchanger of claim 4 , wherein the contoured cross-sectional area of each of the second flow channels is closely aligned between the circular cross-sectional areas of adjacent ones of the first flow channels.

15. The heat exchanger of claim 14 , wherein the contoured cross-sectional area of each of the second flow channels is hexagonal and includes four concave sides each of which is shaped to accommodate an arc of the circular cross-sectional area of an adjacent one of the first flow channels.

16. A method comprising:

constructing an annular heat exchanger core as a single, monolithic unit utilizing an additive manufacturing process, the annular core comprising:

an inner diameter defining a radially inner face;

an outer diameter defining a radially outer face;

first flow channels in a first set of layers between the inner diameter and the outer diameter, each of the first flow channels comprising:

an inlet;

an outlet;

an axial region extending between the inlet and the outlet; and

a first curved region between the first axial region and the first outlet; and

second flow channels in a second set of layers between the inner diameter and the outer diameter and interleaved with the first flow channels, each of the second flow channels comprising:

an inlet;

an outlet;

an axial region extending between the inlet and outlet;

a second curved region between the second inlet and the second axial region; and

a third curved region between the second axial region and the second outlet;

wherein each of the second flow channels has a first cross-sectional shape at the second curved region and the third curved region and a second cross-sectional shape at the second axial region;

constructing a heat exchanger header; and

connecting the header to the annular core to form a heat exchanger.

17. The method of claim 16 ,

wherein each of the second flow channels is defined by a tangential width in the axial region, and the tangential widths increase from an innermost one of the second set of layers to an outermost one of the second set of layers with respect to the inner diameter of the annular core.

18. The method of claim 16 ,

wherein constructing the annular core as the single, monolithic unit utilizing the additive manufacturing process further comprises constructing the annular core from an aluminum-silicon alloy.

19. The method of claim 16 ,

wherein connecting the header to the annular core to form the heat exchanger further comprises welding the header to the annular core.

20. The method of claim 16 , further comprising:

mating the inner face of the heat exchanger with a radial interface of an air cycle machine in an environmental control system.