Abstract: In a compact heat exchanger, a heat exchanger tube adapted for precision assembly of an outer tube and an inner tube and free from decreasing heat transfer efficiency is provided. For this purpose, the heat exchanger tube includes: a plurality of parallel outer tubes; inner tubes inserted in the outer tubes and having their opposite ends extended outward of the outer tubes; a gap support member formed of a wire material disposed in a gap between an inner periphery of the outer tube and an outer periphery of the inner tube and making spiral contact with the inner periphery and the outer periphery substantially throughout the length of the outer tube; and a supporting member making spiral contact with an inner periphery of the inner tube throughout the length of the inner tube.

Abstract: The heat exchanger uses multi-layer tubes, performing efficient heat exchange. Each heat transfer tube includes an outer tube and an inner tube. Header unit directs first fluid through gaps between the inner tube and the outer tube from outer circumferences of the inner tube. The header units are stacked in a top-bottom direction with gap-forming members therebetween, leaving predetermined gap portion. Furthermore, a header cover directs the second fluid through the inner tubes extending from the header units, and is fitted from the outer side, and the second fluid is introduced. With this configuration, the second fluid flowing from the header cover is directed through the inside of the inner tubes and over outer surfaces of the outer tubes along the axial direction via the gap portions, enabling heat exchange to be performed from both inside and outside of the outer tubes.