Heat exchanger with air flow passage for exchanging heat

1. A heat exchanger comprising:

multiple flat tubes that extend in a second direction intersecting a first direction that is an air flow direction and that are disposed at intervals in a third direction that intersects the first direction and the second direction; and

multiple heat transfer fins that extend along the third direction and that are disposed at intervals along the second direction, wherein

the heat exchanger causes refrigerant in the flat tubes to exchange heat with the air flow that passes through heat exchange spaces formed by adjacent flat tubes and adjacent heat transfer fins when viewed from the first direction,

the heat transfer fins each have a heat transfer fin front side surface that is one main surface, a heat transfer fin back side surface that is the other main surface, and a plurality of protrusions that are bulging portions or cut and raised portions that protrude along the second direction from the heat transfer fin front side surface or the heat transfer fin back side surface,

the plurality of protrusions are disposed in the first direction in each of the heat exchange spaces, and the plurality of protrusions includes a leeward side protrusion located on the leeward side and a windward side protrusion located further to the windward side than the leeward side protrusion,

each of the heat exchange spaces comprises:

a one-side-protrusion that is one of either the windward side protrusion or the leeward side protrusion and that protrudes from either the heat transfer fin front side surface or the heat transfer fin back side surface;

an other-side-protrusion that is the other of the windward side protrusion or the leeward side protrusion;

a reference area that, when viewed from an air flow directional view from the windward side to the leeward side of the first direction, is a quadrilateral with a lateral side and a longitudinal side where

one of either the lateral side and the longitudinal side is defined by a length located between an edge of the one-side-protrusion, which is disposed in the heat transfer fin front side surface or the heat transfer fin back side surface that the one-side-protrusion protrudes from, and a main surface of the flat tube closest to the edge of the one-side-protrusion, and

the other of the lateral side and the longitudinal side is defined by a fin pitch of the heat transfer fins; and

a protruding area that is a subset of the reference area occupied by an inclined surface of the other-side-protrusion when viewed from the air flow directional view from the windward side to the leeward side of the first direction, and

a ratio of the protruding area to the reference area is equal to or greater than 0.2,

the plurality of protrusions include a strength enhancement protrusion that extends from one end side in the first direction towards the other end side in the first direction of the heat transfer fin and that increases strength of the heat transfer fin,

the heat transfer fin is formed with a plurality of flat tube insertion holes into which the flat tubes are inserted, the flat tube insertion holes extend from one end side in the first direction towards the other end side in the first direction of the heat transfer fin, and

when viewed from the third direction, a tip end of the strength enhancement protrusion is positioned further to the other end side in the first direction of the heat transfer fin than an edge, which is closest to the other end side in the first direction of the heat transfer fin, of the flat tube insertion hole.

2. The heat exchanger according to claim 1 , wherein

when the heat exchange space is viewed from the third direction, the other-side-protrusion is disposed at a position where a distance is greater than zero, the distance is provided between one of either a windward side edge of the other-side-protrusion and a leeward side edge of the other-side-protrusion that is closer to the flat tube and one of either a windward side end portion of the flat tube and a leeward side end portion of the flat tube that is closer to the other-side-protrusion.

3. The heat exchanger according to claim 1 , wherein

according to the air flow directional view, a protruding length of the other-side-protrusion is equal to or longer than a protruding length of the one-side-protrusion.

4. The heat exchanger according to claim 1 , wherein

the other-side-protrusion is disposed at the most windward side or at the most leeward side of the plurality of protrusions.

5. The heat exchanger according to claim 1 , wherein

the ratio of the protruding area to the reference area is equal to or greater than 0.5.

6. The heat exchanger according to claim 1 , wherein

the heat transfer fin is formed with a plurality of flat tube insertion holes into which the flat tubes are inserted, the flat tube insertion holes extend from one end side in the first direction towards the other end side in the first direction of the heat transfer fin, and

when viewed from the third direction, a terminal end of the strength enhancement protrusion is positioned further to one end side in the first direction of the heat transfer fin than the edge of the flat tube insertion hole.

7. The heat exchanger according to claim 1 , wherein

the heat transfer fin includes a fin main body that extends continuously from one end side in the third direction toward the other end side in the third direction of the heat transfer fin, and

the strength enhancement protrusion is partially or entirely disposed on the fin main body.

8. The heat exchanger according to claim 1 , wherein

when viewed from the third direction, the strength enhancement protrusion is partially or entirely disposed between the one-side-protrusion and the other-side-protrusion.

9. The heat exchanger according to claim 1 , wherein

the strength enhancement protrusion is integrated with the other-side-protrusion.