Heat exchanger and refrigeration cycle apparatus

A heat exchanger comprising:

• a plurality of heat exchange modules arranged with spacing from one another along a direction of flow of air, wherein
• each of the plurality of heat exchange modules includes
• a pair of headers through which a fluid passes, the two headers being placed at a distance from each other in an up-down direction,
• a plurality of flat heat-transfer tubes each having a flat shape in cross-section, being placed between the two headers such that a flat surface of a long side of the flat shape of each of the flat heat-transfer tubes and a flat surface of a long side of the flat shape of another of the flat heat-transfer tubes face each other with spacing from one another, and each having therein flow passages through which the fluid flows, and
• a plurality of corrugated fins each having a corrugated shape and being each placed between ones of the flat heat-transfer tubes that face each other, the corrugated shape having apices joined to the flat heat-transfer tubes, the plurality of corrugated fins each including fin modules between the apices, the fin modules being arranged in the up-down direction,
• one of the corrugated fins situated on a leeward side in the direction of flow of the air is higher in outside-tube heat transfer coefficient than is one of the corrugated fins situated on a windward side in the direction of flow of the air, and
• when, in the direction of flow of the air, a length of protrusion of the corrugated fin situated on the windward side in a windward direction relative to a corresponding one of the flat heat-transfer tubes is defined as ya and a length of protrusion of the corrugated fin situated on the leeward side in the windward direction relative to a corresponding one of the flat heat-transfer tubes is defined as yB, a relationship yA>yB holds.