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. 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. The heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween. The inner and outer walls are concentric at the primary flow inlet of the heat exchanger core. 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. 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.

A counter-flow heat exchanger core includes a first wall defining a longitudinal axis. The first flow path is defined within the first wall. The first flow path includes a primary flow inlet and a primary flow outlet downstream from the primary flow inlet. The heat exchanger core includes at least two hollow vanes circumferentially spaced apart and extending in a radially inward direction from the first wall. Each of the at least two hollow vanes includes a first vane wall and a second vane wall. The heat exchanger core includes a second flow path defined within the at least two hollow vanes between the first vane wall and second vane wall of each of the at least two hollow vanes. The heat exchanger core includes at least one fin extending between two of the at least two circumferentially spaced apart vanes.

A counter-flow heat exchanger core includes a first wall defining a longitudinal axis. The first flow path is defined within the first wall. The first flow path includes a primary flow inlet and a primary flow outlet downstream from the primary flow inlet. The heat exchanger core includes at least two hollow vanes circumferentially spaced apart and extending in a radially inward direction from the first wall. Each of the at least two hollow vanes includes a first vane wall and a second vane wall. The heat exchanger core includes a second flow path defined within the at least two hollow vanes between the first vane wall and second vane wall of each of the at least two hollow vanes. The heat exchanger core includes at least one fin extending between two of the at least two circumferentially spaced apart vanes.

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. 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. The heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween. The inner and outer walls are concentric at the primary flow inlet of the heat exchanger core. 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. 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.

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. 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. The heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween. The inner and outer walls are concentric at the primary flow inlet of the heat exchanger core. 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. 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.

A heat exchanger including a header having a plurality of header openings with rigid tubes that may be made of plastic are inserted in the openings. The tubes are sealed to the header to prevent leakage between the header and the tubes to prevent water and air leakage between the wet, scavenger air stream flowing through the tubes and a dry air stream flowing around the tubes. A method of making the heat exchanger includes providing the openings with a flange and uses an interference fit between the rigid heat exchange tubes and the header openings. A self-leveling sealant may be used to seal the heat exchanger tubes to the header using, for example, a paint roller and/or a paint sprayer.

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. 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. The heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween. The inner and outer walls are concentric at the primary flow inlet of the heat exchanger core. 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. 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.

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. 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. The heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween. The inner and outer walls are concentric at the primary flow inlet of the heat exchanger core. 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. 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.

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. 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. The heat exchanger core includes a primary flow inlet, a primary flow outlet and a middle portion therebetween. The inner and outer walls are concentric at the primary flow inlet of the heat exchanger core. 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. 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.

A heat exchanger including a header having a plurality of header openings with rigid tubes that may be made of plastic are inserted in the openings. The tubes are sealed to the header to prevent leakage between the header and the tubes to prevent water and air leakage between the wet, scavenger air stream flowing through the tubes and a dry air stream flowing around the tubes. A method of making the heat exchanger includes providing the openings with a flange and uses an interference fit between the rigid heat exchange tubes and the header openings. A self-leveling sealant may be used to seal the heat exchanger tubes to the header using, for example, a paint roller and/or a paint sprayer.