Interlocking plate heat exchanger

A method for making a heat exchanger, the method comprising:

• machining a plate of material having a starting thickness and at least one alignment feature, the machining comprising machining down the starting thickness to produce a heat exchanger plate having at least one flow passage segment, and at least two ribs arranged extending along each side of the at least one flow segment;
• removing the at least one alignment feature to provide a trimmed heat exchanger plate;
• stacking the trimmed heat exchanger plate with a further heat exchanger plate with the at least two ribs interlocked with ribs of the further heat exchanger plate, and the at least one flow segment aligned with a flow segment of the further heat exchanger plate;
• and
• joining the at least two ribs of the trimmed heat exchanger plate and the ribs of the further heat exchanger plate together, wherein the machining step produces the heat exchanger plate having the at least one flow passage segment and at least two ribs, and excess material extending in at least one dimension beyond the at least one flow passage segment and the at least two ribs to define the at least one alignment feature, the at least one dimension lying in a plane of the heat exchanger plate, and wherein the step of removing the at least one alignment feature comprises removing the excess material, wherein the machining step comprises machining the at least two ribs to have interlocking structure, wherein the interlocking structure is selected from the group consisting of a convex upward facing surface, a concave upward facing surface, or a combination of a convex upward facing surface and a concave upward facing surface, and further wherein the further heat exchanger plate has ribs that match the at least two ribs such that a convex surface is paired with a concave surface of the at least two ribs, and a concave surface is paired with a convex surface of the at least two ribs.