Heat exchanger and air-conditioning apparatus

A heat exchanger comprising:

• a plurality of heat transfer tubes spaced in a direction orthogonal to an air flow direction;
• and
• a corrugated fin disposed between the plurality of heat transfer tubes, the corrugated fin including a fin portion defining a flat surface and one or more heat transfer promoter groups each including a plurality of heat transfer promoters louver parts, the plurality of louver parts extending from one of the plurality of heat transfer tubes that are adjacent to an other one of the plurality of heat transfer tubes that are adjacent and sloping relative to the fin portion, wherein
• the plurality of louver parts include a first louver part disposed most upstream in the air flow direction,
• a first drain space having a shape in which a part of a perimeter thereof is defined by an edge of the first louver part and is open at upstream side of the first louver part in the air flow direction when viewed in a direction perpendicular to the fin portion is provided between the first louver part and an air upstream part of the fin portion that is located closest to and upstream of the first louver part in the air flow direction,
• a second drain space is provided between adjacent ones of the louver parts, and
• the first drain space has a larger area than the second drain space when viewed in a direction perpendicular to the fin portion.