Abstract: A coil assembly for use in a heat exchanger having air flowing in a predetermined direction. The coil assembly comprises a plurality of parallel linear tubes, a plurality of return tubes interconnecting the linear tubes, and a plurality of fins. Each linear tube has a central portion with an elliptical cross-section and two end portions with round female sockets having circular cross-sections. Each return tube has two end portions with circular cross-sections. Each end portion of a return tube fits into a round female socket of a linear tube regardless of the orientation of the major axes of the linear tubes. The major axis of the elliptical cross-section resides at an oblique angle with respect to the direction of air flow. Each fin comprises a planar sheet of a heat-conductive material with a plurality of holes. The central portion of a linear tube extends through each hole. Each fin securely contacts each linear tube extending therethrough such that heat transfer therebetween is enhanced.

Abstract: A coil assembly for use in a heat exchanger having air flowing in a predetermined direction. The coil assembly comprises a plurality of parallel linear tubes, a plurality of return tubes interconnecting the linear tubes, and a plurality of fins. Each linear tube has a central portion with an elliptical cross-section and two end portions with round female sockets having circular cross-sections. Each return tube has two end portions with circular cross-sections. Each end portion of a return tube fits into a round female socket of a linear tube regardless of the orientation of the major axes of the linear tubes. The major axis of the elliptical cross-section resides at an oblique angle with respect to the direction of air flow. Each fin comprises a planar sheet of a heat-conductive material with a plurality of holes. The central portion of a linear tube extends through each hole. Each fin securely contacts each linear tube extending therethrough such that heat transfer therebetween is enhanced.