Louvered elliptical tube micro-lattice heat exchangers

A heat exchanger comprising a heat exchanger core, the heat exchanger core comprising:

• a first plurality of hollow members extending in a first direction;
• and
• a second plurality of hollow members extending in a second direction different from the first direction,
• the hollow members of the first plurality of hollow members and the second plurality of hollow members intersecting at a plurality of hollow nodes,
• each hollow member of the first plurality of hollow members and the second plurality of hollow members having:
• a length in a longitudinal axis, the length being a largest dimension of each respective one of the hollow members, and
• at a point along the length, an elongated cross section in a plane perpendicular to the longitudinal axis, the cross section comprising a smallest diameter in a direction parallel to a minor axis, the minor axis being perpendicular to the longitudinal axis, and a largest diameter in a direction parallel to a major axis, the major axis being perpendicular to the longitudinal axis, the minor axis and the major axis lying in the plane of the cross section, the largest diameter being at least 20 percent longer than the smallest diameter, and
• the largest diameter of a first one of the first plurality of hollow members extending in a different direction from the largest diameter of a second one of the first plurality of hollow members.