Abstract: A heat exchanger includes fins that are arranged in a direction orthogonal to a direction in which air flows and a heat transfer pipe that extends through the fins and that is bonded and fixed to the fins when the heat transfer pipe is radially expanded by a pipe-expanding method. Tall projections and short projections are provided on an inner surface of the heat transfer pipe. The tall projections are arranged in a circumferential direction and extend in an axial direction of the heat transfer pipe. The short projections are arranged between the tall projections and extend in the axial direction. Opposing side surfaces of the tall and short projections after the expansion of the heat transfer pipe are so inclined that when extensions are drawn from the side surfaces, the extensions cross each other in an inner region of the heat transfer pipe.

Abstract: An air-conditioning apparatus includes an outdoor unit equipped with an outdoor-side heat exchanger formed by inserting a plurality of heat transfer pipes made of a metal material, such as aluminum or an aluminum alloy, into a plurality of fins, and an indoor unit equipped with an indoor-side heat exchanger formed by inserting a plurality of heat transfer pipes made of a metal material, such as aluminum or an aluminum alloy, into a plurality of fins. The heat transfer pipes in the outdoor-side heat exchanger are each internally provided with a plurality of straight grooves substantially parallel to the pipe axial direction. The heat transfer pipes in the indoor-side heat exchanger are each internally provided with a plurality of spiral grooves having a predetermined lead angle.

Abstract: An air-conditioning apparatus includes an outdoor unit equipped with an outdoor-side heat exchanger formed by inserting a plurality of heat transfer pipes made of a metal material, such as aluminum or an aluminum alloy, into a plurality of fins, and an indoor unit equipped with an indoor-side heat exchanger formed by inserting a plurality of heat transfer pipes made of a metal material, such as aluminum or an aluminum alloy, into a plurality of fins. The heat transfer pipes in the outdoor-side heat exchanger are each internally provided with a plurality of straight grooves substantially parallel to the pipe axial direction. The heat transfer pipes in the indoor-side heat exchanger are each internally provided with a plurality of spiral grooves having a predetermined lead angle.

Abstract: A heat exchanger includes fins that are arranged in a direction orthogonal to a direction in which air flows and a heat transfer pipe that extends through the fins and that is bonded and fixed to the fins when the heat transfer pipe is radially expanded by a pipe-expanding method. Tall projections and short projections are provided on an inner surface of the heat transfer pipe. The tall projections are arranged in a circumferential direction and extend in an axial direction of the heat transfer pipe. The short projections are arranged between the tall projections and extend in the axial direction. Opposing side surfaces of the tall and short projections after the expansion of the heat transfer pipe are so inclined that when extensions are drawn from the side surfaces, the extensions cross each other in an inner region of the heat transfer pipe.