Heat exchangers

A counter-flow heat exchanger comprising:

• a heat exchanger core including an inner wall and an outer wall radially outward and spaced apart from the inner wall, wherein a first flow path is defined within the inner wall and a second flow path is defined between the inner wall and the outer wall, wherein the heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween, wherein the inner and outer walls are concentric at the primary flow inlet of the heat exchanger core, wherein the inner wall defines a first set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core diverging away from a radial center of the heat exchanger core, and wherein the inner wall and the outer wall define a second set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core converging toward the radial center of the heat exchanger core, wherein at least one channel of the first set of channels splits into multiple sub-channels to maintain a width smaller than a maximum threshold.

A counter-flow heat exchanger comprising:

• a heat exchanger core including an inner wall and an outer wall radially outward and spaced apart from the inner wall, wherein a first flow path is defined within the inner wall and a second flow path is defined between the inner wall and the outer wall, wherein the heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween, wherein the inner and outer walls are concentric at the primary flow inlet of the heat exchanger core, wherein the inner wall defines a first set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core diverging away from a radial center of the heat exchanger core, and wherein the inner wall and the outer wall define a second set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core converging toward the radial center of the heat exchanger core, wherein at least two channels of the second set of channels unite into a single joined channel to maintain a width greater than a minimum threshold.

A counter-flow heat exchanger comprising:

• a heat exchanger core including an inner wall and an outer wall radially outward and spaced apart from the inner wall, wherein a first flow path is defined within the inner wall and a second flow path is defined between the inner wall and the outer wall, wherein the heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween, wherein the inner and outer walls are concentric at the primary flow inlet of the heat exchanger core, wherein the inner wall defines a first set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core diverging away from a radial center of the heat exchanger core, and wherein the inner wall and the outer wall define a second set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core converging toward the radial center of the heat exchanger core, wherein at least one of the first and second flow paths include vanes to assist with flow distribution.

A counter-flow heat exchanger comprising:

• a heat exchanger core including an inner wall and an outer wall radially outward and spaced apart from the inner wall, wherein a first flow path is defined within the inner wall and a second flow path is defined between the inner wall and the outer wall, wherein the heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween, wherein the inner and outer walls are concentric at the primary flow inlet of the heat exchanger core, wherein the inner wall defines a first set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core diverging away from a radial center of the heat exchanger core, and wherein the inner wall and the outer wall define a second set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core converging toward the radial center of the heat exchanger core, wherein the heat exchanger core is substantially linear and defines a longitudinal axis between the primary flow inlet and the primary flow outlet, wherein a radial center of the inner wall is aligned with the longitudinal axis.

A counter-flow heat exchanger comprising:

• a heat exchanger core including an inner wall and an outer wall radially outward and spaced apart from the inner wall, wherein a first flow path is defined within the inner wall and a second flow path is defined between the inner wall and the outer wall, wherein the heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween, wherein the inner and outer walls are concentric at the primary flow inlet of the heat exchanger core, wherein the inner wall defines a first set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core diverging away from a radial center of the heat exchanger core, and wherein the inner wall and the outer wall define a second set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core converging toward the radial center of the heat exchanger core, wherein the inner and outer walls are concentric at the primary flow outlet of the heat exchanger core.

A counter-flow heat exchanger comprising:

• a heat exchanger core including an inner wall and an outer wall radially outward and spaced apart from the inner wall, wherein a first flow path is defined within the inner wall and a second flow path is defined between the inner wall and the outer wall, wherein the heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween, wherein the inner and outer walls are concentric at the primary flow inlet of the heat exchanger core, wherein the inner wall defines a first set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core diverging away from a radial center of the heat exchanger core, and wherein the inner wall and the outer wall define a second set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core converging toward the radial center of the heat exchanger core, wherein the heat exchanger core is cylindrical, wherein at an outlet of the heat exchanger core, in a cross-section taken perpendicular to a primary flow direction, an annulus is defined between the inner and outer walls.

A counter-flow heat exchanger comprising:

• a heat exchanger core including an inner wall and an outer wall radially outward and spaced apart from the inner wall, wherein a first flow path is defined within the inner wall and a second flow path is defined between the inner wall and the outer wall, wherein the heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween, wherein the inner and outer walls are concentric at the primary flow inlet of the heat exchanger core, wherein the inner wall defines a first set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core diverging away from a radial center of the heat exchanger core, and wherein the inner wall and the outer wall define a second set of channels extending axially from the primary flow inlet to the middle portion of the heat exchanger core converging toward the radial center of the heat exchanger core, wherein, from the middle portion of the heat exchanger core to the primary flow outlet, the first set of channels extends axially away from the middle portion to the primary flow outlet converging toward the radial center of the heat exchanger core and the second set of channels extends axially away from the middle portion to the primary flow outlet diverging away from the radial center of the heat exchanger core.