US-12624904-B2 - Heat exchanger and refrigeration cycle apparatus

US12624904B2US 12624904 B2US12624904 B2US 12624904B2US-12624904-B2

Abstract

A corrugated fin of a heat exchanger is formed such that fin sections are joined together one after another in a tube axial direction of a plurality of flat heat-transfer tubes. Louvers in the fin sections of the corrugated fin are divided into a first louver group formed further upstream in a direction of flow of air than a drain slit in the corrugated fin and a second louver group formed further downstream in the direction of flow of air than the drain slit. Plate portions of the first louver group and plate portions of the second louver group are inclined to a flat-plate portion in the fin sections and inclined in respective directions that are opposite to each other. The drain slit includes a plurality of drain slits provided in a plurality of respective rows between the first louver group and the second louver group.

Inventors

Yoji ONAKA
Rihito ADACHI
Nanami KISHIDA
Taisaku GOMYO
Tetsuji Saikusa
Yuki NAKAO
Atsushi KIBE
Hiroyuki Morimoto

Assignees

MITSUBISHI ELECTRIC CORPORATION

Dates

Publication Date: 20260512
Application Date: 20210413

Claims (17)

1 . A heat exchanger comprising: a plurality of flat heat-transfer tubes each formed in a flat shape in cross-section, provided with a plurality of flow passages formed by through holes, and placed side by side and spaced from one another in a direction orthogonal to a direction of flow of air; and a corrugated fin placed between the plurality of flat heat-transfer tubes, the corrugated fin being formed such that fin sections that are plate-shaped are joined together one after another in a wave shape in a tube axial direction of the plurality of flat heat-transfer tubes, the fin sections each having a drain slit formed such that the drain slit extends in a tube side-by-side placement direction of the plurality of flat heat-transfer tubes, and a plurality of louvers each having a louver slit extending in the tube side-by-side placement direction and a plate portion inclined to a flat-plate portion that is tabular-shaped in the fin section, the plurality of louvers being divided into a first louver group formed further upstream in the direction of flow of air than the drain slit and a second louver group formed further downstream in the direction of flow of air than the drain slit, the plate portions of the first louver group and the plate portions of the second louver group being inclined to the flat-plate portion and inclined in respective directions that are opposite to each other, the drain slit comprising a plurality of drain slits provided in a plurality of respective rows between the first louver group and the second louver group at an interval in the direction of flow of air, wherein: when an inter-louver air passage cross-sectional area AL is defined as AL=((Lp×sinθ)−t)×NL×Lw and a drain slit opening area As is defined as As=Ns×Sw×Ss, 1≤AL/As≤4 is satisfied, where NL [−] is the number of the plurality of louvers, θ[rad] is a louver angle of the plate portion of each of the plurality of louvers inclined to the flat-plate portion, Lp [mm] is a pitch between adjacent ones of the plurality of louvers, Lw [mm] is a width of each of the plurality of louvers in the tube side-by-side placement direction, t [mm] is a thickness of the corrugated fin, Ns [−] is row counts of the plurality of drain slits, Sw [mm] is a width of each of the plurality of drain slits in the tube side-by-side placement direction, and Ss [mm] is a length of each of the plurality of drain slits in the direction of flow of air.
2 . The heat exchanger of claim 1 , wherein the plurality of drain slits of the plurality of respective rows are formed adjacent to each other in the direction of flow of air, and a length in the direction of flow of air of a heat-transfer region that is a region of the fin section interposed in the direction of flow of air by adjacent ones of the plurality of drain slits provided in a plurality of respective rows is shorter than a length of each of a corresponding one of the plurality of drain slits in the direction of flow of air.
3 . The heat exchanger of claim 1 , wherein an angle of the plate portion of each of the plurality of louvers inclined to the flat-plate portion ranges from 15 degrees to 30 degrees.
4 . The heat exchanger of claim 1 , wherein the corrugated fin has an upstream protruding portion protruding further upstream than the plurality of flat heat-transfer tubes and having a thickness that is greater than a thickness of a portion of the corrugated fin that is other than the upstream protruding portion.
5 . The heat exchanger of claim 4 , wherein the upstream protruding portion of the corrugated fin is thickened by folding back a portion of the fin section protruding further upstream than the plurality of flat heat-transfer tubes.
6 . The heat exchanger of claim 1 , wherein ones of the plurality of drain slits in ones of the fin sections adjacent to each other in the tube axial direction are displaced from each other in the tube side-by-side placement direction.
7 . The heat exchanger of claim 1 , wherein the corrugated fin is formed such that ones of the fin sections identical in position of ones of the plurality of drain slits to each other in the direction of flow of air are periodically and repeatedly located in the tube axial direction.
8 . The heat exchanger of claim 1 , wherein the plurality of flat heat-transfer tubes are placed in a plurality of rows and are spaced from one another in the direction of flow of air, the corrugated fin is provided commonly for the plurality of rows, and the corrugated fin has the plurality of louvers and the plurality of drain slits formed in correspondence with each of the plurality of rows.
9 . The heat exchanger of claim 8 , further comprising an interrow drain slit formed in a position corresponding to a space between each adjacent two of the plurality of rows in the direction of flow of air.
10 . The heat exchanger of claim 9 , wherein in the corrugated fin common to each of the plurality of rows, the interrow drain slit is one of the plurality of drain slits that divides the plurality of louvers into the first louver group and the second louver group.
11 . The heat exchanger of claim 9 , wherein an opening area of the interrow drain slit is larger than an opening area of each of the plurality of drain slits other than the interrow drain slit.
12 . A refrigeration cycle apparatus comprising the heat exchanger of claim 1 .
13 . The heat exchanger of claim 1 , wherein: each of the plurality of drain slits and the plurality of louvers are parallel to each other.
14 . The heat exchanger of claim 13 , wherein: each of the plurality of drain slits is orthogonal to the direction of the flow of air.
15 . The heat exchanger of claim 1 , wherein: each of the plurality of drain slits is orthogonal to the direction of the flow of air.
16 . A heat exchanger, comprising: a plurality of flat heat-transfer tubes each formed in a flat shape in cross-section, provided with a plurality of flow passages formed by through holes, and placed side by side and spaced from one another in a direction orthogonal to a direction of flow of air; and a corrugated fin placed between the plurality of flat heat-transfer tubes, the corrugated fin being formed such that fin sections that are plate-shaped are joined together one after another in a wave shape in a tube axial direction of the plurality of flat heat-transfer tubes, the fin sections each having a drain slit formed such that the drain slit extends in a tube side-by-side placement direction of the plurality of flat heat-transfer tubes, and a plurality of louvers each having a louver slit extending in the tube side-by-side placement direction and a plate portion inclined to a flat-plate portion that is tabular-shaped in the fin section, the plurality of louvers being divided into a first louver group formed further upstream in the direction of flow of air than the drain slit and a second louver group formed further downstream in the direction of flow of air than the drain slit, the plate portions of the first louver group and the plate portions of the second louver group being inclined to the flat-plate portion and inclined in respective directions that are opposite to each other, the drain slit comprising a plurality of drain slits provided in a plurality of respective rows between the first louver group and the second louver group at an interval in the direction of flow of air, wherein; the flat-plate portion has two ends in the tube side-by-side placement direction and the fin section has, at each of the two ends of the flat-plate portion, an apex joined to the plurality of flat heat-transfer tubes, and one of a plurality of the fin sections has one of the plurality of drain slits formed in a position at which the one of the plurality of drain slits overlaps the apex at one or each of the two ends when the one of the plurality of drain slits is seen from an angle parallel with the tube axial direction.
17 . The heat exchanger of claim 16 , wherein one of the plurality of the fin sections has one of the plurality of drain slits formed in a position at which the one of the plurality of drain slits does not overlap the apex at each of the two ends when the one of the plurality of drain slits is seen from an angle parallel with the tube axial direction.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is based on PCT filing PCT/JP2021/015325, filed Apr. 13, 2021, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a heat exchanger including a corrugated fin and to a refrigeration cycle apparatus. BACKGROUND ART For example, corrugated-fin-tube-type heat exchangers formed by alternately stacking flat heat-transfer tubes and corrugated fins are widespread. In a case in which such a heat exchanger is used as an evaporator, the surface temperature of a corrugated fin becomes lower than or equal to a freezing point, so that condensed water on a fin surface may freeze. The freezing of the condensed water on the fin surface mounts resistance to air passing through the heat exchanger, causing a deterioration in heat-transfer performance of the corrugated fin. To address this problem, there is a heat exchanger provided with a drain slit formed by a through hole in a corrugated fin so that condensed water on a fin surface is drained through the drain slit (see, for example, Patent Literature 1). It should be noted that the term “condensed water” refers to water having adhered to a surface of the heat exchanger as a result of condensation of moisture in the air. CITATION LIST Patent Literature Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2015-183908 SUMMARY OF INVENTION Technical Problem Although the heat exchanger of Patent Literature 1 has a drain slit through which condensed water on a fin surface is drained, enlarging an opening of the drain slit for improvement in drainage capacity invites a deterioration in heat-transfer performance due to a reduction in heat-transfer area while bringing about improvement in drainage capacity. The heat exchanger of Patent Literature 1 had room for improvement in terms of improving drainage capacity while maintaining heat-transfer performance. To solve problems such as those noted above, the present disclosure has as an object to provide a heat exchanger that makes it possible to improve drainage capacity while maintaining heat-transfer performance and a refrigeration cycle apparatus. Solution to Problem A heat exchanger according to an embodiment of the present disclosure includes a plurality of flat heat-transfer tubes each formed in a flat shape in cross-section, provided with a plurality of flow passages formed by through holes, and placed side by side and spaced from one another in a direction orthogonal to a direction of flow of air; and a corrugated fin placed between the plurality of flat heat-transfer tubes. The corrugated fin is formed such that fin sections that are plate-shaped are joined together one after another in a wave shape in a tube axial direction of the plurality of flat heat-transfer tubes, the fin sections each have a drain slit formed such that the drain slit extends in a tube side-by-side placement direction of the plurality of flat heat-transfer tubes, and a plurality of louvers each having a louver slit extending in the tube side-by-side placement direction and a plate portion inclined to a flat-plate portion that is tabular-shaped in the fin section, the plurality of louvers are divided into a first louver group formed further upstream in the direction of flow of air than the drain slit and a second louver group formed further downstream in the direction of flow of air than the drain slit, the plate portions of the first louver group and the plate portions of the second louver group are inclined to the flat-plate portion and inclined in respective directions that are opposite to each other, and the drain slit includes a plurality of drain slits provided in a plurality of respective rows between the first louver group and the second louver group. Further, a refrigeration cycle apparatus according to an embodiment of the present disclosure includes the aforementioned heat exchanger. Advantageous Effects of Invention By having drain slits in a plurality of rows between the first louver group and the second louver group, the heat exchanger according to an embodiment of the present disclosure makes it possible to improve drainage capacity while maintaining heat-transfer performance. Further, since the length of a heat-transfer region is longer than the length of a drain slit in the direction of flow of air, the heat exchanger according to an embodiment of the present disclosure makes it possible to improve drainage capacity while maintaining heat-transfer performance. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram illustrating a configuration of a heat exchanger according to Embodiment 1. FIG. 2 is a schematic perspective view of part of the heat exchanger according to Embodiment 1. FIG. 3 is a schematic cross-sectional view of a flat-plate portion of a corrugated fin according to Embodiment 1 as taken along a direction of flow of air. FIG. 4 is an explanatory diagram of the positions of drain slits i