HEAT EXCHANGER
A heat exchanger includes a heat transfer tube group in which a plurality of first heat transfer tubes ( 3 ) through which a first fluid flows and a plurality of second heat transfer tubes ( 4 ) through which a second fluid that exchanges heat with the first fluid flows are arranged alternately while being in contact with each other. The heat transfer tube group is formed in a spiral shape by being wound in X direction perpendicular to Y direction in which the first heat transfer tubes ( 3 ) and the second heat transfer tubes ( 4 ) are arranged. A plurality of concave portions ( 3 a ) are provided on both sides, in the X direction, of an outer circumferential surface ( 31 ) of each of the first heat transfer tubes ( 3 ), along an extending direction of the first heat transfer tube ( 3 ). The plurality of concave portions ( 3 a ) form convex portions on an inner circumferential surface of the first heat transfer tube ( 3 ).
1 . A heat exchanger comprising a heat transfer tube group in which a plurality of first heat transfer tubes through which a first fluid flows and a plurality of second heat transfer tubes through which a second fluid that exchanges heat with the first fluid flows are arranged alternately while being in contact with each other, the heat transfer tube group being formed in a spiral shape so as to have a shape of a flat rectangular plate by being wound in a perpendicular direction perpendicular to an arrangement direction in which the first heat transfer tubes and the second heat transfer tubes are arranged,
wherein a plurality of concave portions are provided on both sides, in the perpendicular direction in which the first heat transfer tubes and the second heat transfer tubes are out of contact with each other, of an outer circumferential surface of each of the first heat transfer tubes, along an extending direction of the first heat transfer tube, the plurality of concave portions form convex portions on an inner circumferential surface of the first heat transfer tube.
2 . The heat exchanger according to claim 1 , wherein the concave portions provided on one side, in the perpendicular direction, of the outer circumferential surface of the first heat transfer tube and the concave portions provided on the other side, in the perpendicular direction, of the outer circumferential surface of the first heat transfer tube are disposed alternately along the extending direction of the first heat transfer tube.
3 . The heat exchanger according to claim 1 , wherein the concave portions provided on one side, in the perpendicular direction, of the outer circumferential surface of the first heat transfer tube and the concave portions provided on the other side, in the perpendicular direction, of the outer circumferential surface of the first heat transfer tube are disposed at positions facing each other in the perpendicular direction.
4 . The heat exchanger according to claim 1 , wherein a plurality of concave portions also are provided on both sides, in the perpendicular direction, of an outer circumferential surface of each of the second heat transfer tubes, along an extending direction of the second heat transfer tube, and the plurality of concave portions form convex portions on an inner circumferential surface of the second heat transfer tube.
5 . The heat exchanger according to claim 4 , wherein the concave portions provided on one side, in the perpendicular direction, of the outer circumferential surface of the second heat transfer tube and the concave portions provided on the other side, in the perpendicular direction, of the outer circumferential surface of the second heat transfer tube are disposed alternately along the extending direction of the second heat transfer tube.
6 . The heat exchanger according to claim 4 , wherein the concave portions provided on one side, in the perpendicular direction, of the outer circumferential surface of the second heat transfer tube and the concave portions provided on the other side, in the perpendicular direction, of the outer circumferential surface of the second heat transfer tube are disposed at positions facing each other in the perpendicular direction.
7 . The heat exchanger according to claim 1 , wherein the concave portions are linear recesses extending in a specified direction.
8 . The heat exchanger according to claim 7 , wherein the specified direction is a direction parallel to the extending direction of the first heat transfer tube.
9 . The heat exchanger according to claim 7 , wherein the specified direction is a direction inclined with respect to the extending direction of the first heat transfer tube.
10 . The heat exchanger according to claim 1 , wherein the heat transfer tube group is formed in an approximately-rectangular spiral shape that is wound while repeating alternately a straight portion and a bent portion that is bent approximately 90° C. with a uniform bend radius.
11 . The heat exchanger according to claim 1 , wherein a gap is formed between an outer-located winding portion and an inner-located winding portion adjacent to each other in the heat transfer tube group.
12 . The heat exchanger according to claim 1 , wherein a heat insulating material is interposed between an outer-located winding portion and an inner-located winding portion adjacent to each other in the heat transfer tube group.
13 . The heat exchanger according to claim 1 , wherein the first fluid is heated by the second fluid.
14 . The heat exchanger according to claim 13 , wherein the first fluid is water and the second fluid is a refrigerant.
15 . The heat exchanger according to claim 1 , wherein both of the first heat transfer tubes and the second heat transfer tubes are circular tubes, and the first heat transfer tubes have an outer diameter equal to or larger than that of the second heat transfer tubes.
16 . The heat exchanger according to claim 1 , wherein the first fluid flows through the first heat transfer tubes from an peripheral side toward a central side of the spiral shape, and the second fluid flows through the second heat transfer tubes from the central side toward the peripheral side of the spiral shape.
17 . The heat exchanger according to claim 4 , wherein the concave portions are linear recesses extending in a specified direction.
18 . The heat exchanger according to claim 17 , wherein the specified direction is a direction parallel to the extending direction of the second heat transfer tube.
19 . The heat exchanger according to claim 17 , wherein the specified direction is a direction inclined with respect to the extending direction of the second heat transfer tube.