Heat exchanger, air-conditioning apparatus including the same, and method of producing flat-tube u-bend

A heat exchanger comprising a plurality of flat tubes each having a flat cross section, and a plurality of flat-tube U-bends each having a flat cross section and a U-shape in external appearance,

• a plurality of flat-tube columns each made up of the plurality of flat tubes installed in a plurality of tiers in a set direction being arranged in a direction intersecting the set direction,
• the plurality of flat tubes in the plurality of flat-tube columns being arranged in a staggered manner in the set direction,
• each of the plurality of flat-tube U-bends being placed in a pair of coupling portions of the plurality of flat tubes,
• each of the pair of coupling portions being placed in one of a pair of the plurality of flat-tube columns that are next to each other in the direction intersecting the set direction,
• the plurality of flat-tube U-bends being twisted such that major axes of flat cross sections in both end portions of each of the plurality of flat-tube U-bends are oriented in same directions as major axes of flat cross sections of the plurality of flat tubes connected to the both end portions,
• the both end portions of the plurality of flat-tube U-bends being twisted against other portions of the plurality of flat-tube U-bends.