KR20110033198A - Method for manufacturing tube and fin heat exchanger with reduced tube diameter and optimized fin produced thereby - Google Patents

Abstract

In accordance with a preferred embodiment of the present invention an improved method of manufacturing a tube and fin heat exchanger is disclosed which comprises a process of increasing the strength and stiffness of a heat exchanger. More rigid fins have a greater tendency to maintain proper alignment within the stack of fins, which helps to race long stacks of fins with small (eg 5 mm) diameter tubing. Preferably, fin stiffness is increased by forming a plurality of longitudinal ribs in the fin during the fin stamping process. More preferably, two ribs are provided for each longitudinal row of collared holes. Preferred embodiments of the present invention are also dimensioned and arranged for optimal thermodynamic performance when used with small diameter tubing, reducing the space required for a given heat exchanger system.

Description

METHOD FOR MANUFACTURING TUBE AND FIN HEAT EXCHANGER WITH REDUCED TUBE DIAMETER AND OPTIMIZED FIN PRODUCED THEREBY}

The present invention relates generally to novel fin design for tube and fin heat exchangers, and more particularly for tube and fin heat exchangers.

As shown in FIG. 1, a conventional tube and fin heat exchanger 10 consists of a stack of generally planar metal fins 12 sandwiched between an upper end plate 14 and a bottom end plate 16. The terms "top" and "bottom" used to refer to an end plate of a heat exchanger are derived based on the heat exchanger's orientation during expansion in a vertical hairpin expander press and must necessarily indicate the orientation of the heat exchanger in any particular installation. It is not.

The pin 12 has a plurality of collared holes 18 formed therethrough, and the upper end plate 14 and the bottom end plate 16 have corresponding holes 20 formed therethrough. Once the pins 12 and end plates 14, 16 are stacked, the holes 18, 20 are axially aligned to receive a plurality of U-shaped hairpin tubes (“hairpins”) 22 through the stack. The hairpin 22 is formed by bending a length of a small tube, typically copper, aluminum, steel or titanium 180 degrees around a small diameter mandrel. The hairpin tube 22 passes through or lacquers an assembly of loosely stacked pins from the bottom end plate 16 such that the open end 26 of the hairpin tube 22 extends beyond the top end plate 14. The upper end plate 14 slides over the open end 26 of the hairpin 22 and the hairpin 22 is mechanically inflated from the inside to create a tight fit with the pin 12. Finally, a return bend fitting 24 is soldered or brazed to the open end 26 of the hairpin tube 22 to create a dead fluid flow system through the stack of fins 12.

It is advantageous to use very small diameter hairpin tubing to maximize the heat transfer area within a given heat exchanger size and geometry. Smaller tubes increase the total heat transfer area and heat transfer coefficient at the cooling side of the heat exchanger, which greatly improves system efficiency. In addition, smaller tubing diameters reduce the airflow wake effect behind the heat tubes, which reduces the pressure loss due to the presence of the tubes facing the incoming air. Low pressure losses on the air side further reduce fan motor power requirements and increase fin area, further improving system heat transfer efficiency. In addition, the larger the tube diameter, the thicker the tube wall thickness must be in order to sustain a certain pressure differential. Thus, smaller tube diameters allow thinner tube walls for a given cooling pressure, which reduces material costs.

According to the state of the art, the heating, ventilation and air conditioning (“HVAC”) industry typically manufactures tube and fin heat exchangers using hairpin tubes having a diameter of 7.0 mm to 9.5 mm (3/8 inch). Although the industry wishes to manufacture smaller diameter heat exchanger coils, prior art manufacturing techniques have limited such coils to short lengths, which in turn limited the commercial success of small diameter coils. The source of the problem is that when the hairpin tubing becomes very small, the racing process becomes very difficult, hindering the commercially viable manufacture of any but the shortest heat exchanger. For example, a heat exchanger of 6 feet or more in length is easily manufactured using 3/8 inch copper tubing. However, if 5 mm copper tubing is used, racing a heat exchanger longer than about 36 inches is not commercially feasible due to the effect of the "chinese handcuff" of many fins. Accordingly, it is desirable to provide a manufacturing process that produces a more rigid heat exchanger fin that is produced to facilitate the lacing process of coils of small diameter, such as 5 mm or less.

Tube-finned heat exchangers of the prior art feature 7 to 3/8 inch tubing and generally employ fins having a fin width of 19 mm to 22 mm and a transverse tube pitch of 19 mm to 25.4 mm. Fins with fin dimensions of the prior art do not deliver optimal performance to tubes of smaller diameters, such as 5 mm. Therefore, it is desirable to provide heat exchanger fins with improved thermodynamic performance optimized for small diameter piping and whereby the heat exchanger system takes up less space.

It is a primary object of the present invention to provide a manufacturing process for producing rigid fins to facilitate the racing of large size tubes and fin heat exchangers with pipes of 5 mm or less.

Another object of the present invention is to provide a heat exchanger manufacturing process in which heat exchanger fins having a plurality of longitudinal ribs are used to enhance the racing process.

It is another object of the present invention to provide heat exchanger fins designed and arranged for use with pipes of 5 mm or less in order to maximize thermodynamic heat transfer.

Another object of the present invention is to provide a heat exchanger fin that promotes condensation flow from the fin.

The above as well as other objects of the present invention are realized in an improved method of manufacturing a tube and fin heat exchanger comprising a process for increasing the strength and stiffness of the heat exchanger according to a preferred embodiment of the invention. More rigid fins have a greater tendency to maintain proper alignment within the stack of fins, which helps to race long stacks of fins with small (eg 5 mm) diameter tubing. Preferably, fin stiffness is increased by forming a plurality of longitudinal ribs in the fin during the fin stamping process. More preferably, two ribs are provided for each longitudinal row of collared holes.

Preferred embodiments of the present invention are also dimensioned and arranged for optimal thermodynamic performance when used with small diameter tubing, reducing the space required for a given heat exchanger system.

The pin preferably comprises a slit with an end having an angle of incidence of 30 degrees to the airflow, which assists in redirecting the airflow from the tube passing through the collared hole, avoiding the reflux zone behind the tube and being parallel Provides more efficient air mixing in the slits. The slit end at an angle also creates a vortex in the region of the fin with the largest distance to the adjacent tube, which improves heat transfer across that region.

According to the present invention, it is possible to provide a manufacturing process for manufacturing rigid fins to facilitate the racing of large size tubes and fin heat exchangers with pipes of 5 mm or less, and a heat exchanger fin having a plurality of longitudinal ribs is provided. Provide heat exchanger manufacturing processes used to improve the racing process, provide heat exchanger fins designed and arranged for use with pipes of 5 mm or less to maximize thermodynamic heat transfer, and condensate flow from fins It is possible to provide a heat exchanger fin to promote the heat.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on the Example shown in an accompanying drawing.
1 is an exploded perspective view of a conventional tube and fin heat exchanger of the prior art,
FIG. 2 is a perspective view of a portion of heat exchanger fins arranged for a single longitudinal row of a 5 mm hairpin tube according to a first embodiment of the present invention, with a preferred slot pattern repeated between pairs of collared holes, Shows a pair of longitudinal ribs formed in the wall and adjoining the colored holes,
3 is a plan view of a portion of the heat exchanger fins of the single hairpin row of FIG. 2,
4 is a perspective view of a portion of a heat exchanger fin arranged for two longitudinal rows of a 5 mm hairpin tube according to a second embodiment of the present invention, with a preferred slot pattern repeated between pairs of collared holes, Shows two pairs of longitudinal ribs formed and adjoining two longitudinal rows of colored holes,
5 is a plan view of a portion of the heat exchanger fin of FIG. 4,
6 is a bottom view of a portion of the heat exchanger fin of FIG. 4,
7 is an enlarged cross-sectional view of the heat exchanger fin of FIG. 4 taken along line 7-7 of FIG. 5, with the colored holes shown in dashed lines to show the details of the raised slots.
8 is a left side view of a portion of the heat exchanger fin of FIG. 4 (the front of the fin being determined by the incident airflow),
9 is an enlarged cross-sectional view of a longitudinal rib of a portion of the heat exchanger fin of FIG. 4 taken along line 9-9 of FIG.
10 is a plan view of a portion of the heat exchanger fin of FIG. 4 showing the details and preferred dimensions of the raised slot pattern for optimizing thermodynamic performance by a 5 mm hairpin tube, FIG.
FIG. 11 is an enlarged cross sectional view of the raised vane taken along line 11-11 of FIG. 10.

2-11 illustrate fins 12 ′ dimensioned for small tubing (eg, 5 mm or less in outer diameter) optimized for use with condensers or evaporators of conventional air conditioners. 2 and 3 illustrate a heat exchanger fin 12 'according to a first embodiment of the present invention characterized by a single longitudinal row of collared holes 18' for use in a single row of coil assemblies. 4 through 8 illustrate a heat exchanger fin 12 ′ according to a second embodiment of the present invention comprising two longitudinal rows of collared holes 18 ′ for use in a double row coil assembly. However, the pins 12 'can be arranged for three, four, five and six or more rows of coils according to the invention. The leading and trailing edges of the pin 12 'preferably have corrugated edges.

Referring mainly to FIGS. 2 to 6, according to a preferred embodiment of the present invention, a tube and fin heat exchanger manufacturing process of 5 mm or less includes a novel and non-obvious treatment step in forming heat exchanger fins. . As in the prior art heat exchanger fins, fins 12 'are formed by a stamping process in a fin press, such as produced by Burr Oak Tool, Stuggis, Michigan. The pin raw material is conveyed from the roll of sheet metal to the press. Various metals, heat treatments and thicknesses are available, but the general industrial choice is aluminum. The pin stock is released from the uncoiler, lubricated and then conveyed through the press where the die is pulled out of the press to form details, punching the colored holes and cutting the pin to the desired length and width. Stamping generally takes place in several stages.

However, in a preferred manufacturing process, the pin press includes a die that forms two longitudinal ribs 100 in the fin 12 'for each longitudinal row of collared holes 18'. The purpose of the longitudinal reinforcing ribs 100 is to assist in the manufacture of the coil assembly. More rigid fins tend to maintain proper alignment on the racing table within the stack of fins, which helps to race along the stack of fins with small (eg 5 mm) diameter tubing.

Each longitudinal row of collared holes 18 'is disposed between its own pair of longitudinal ribs. In the case of a single row coil structure, the pin 12 'has two ribs 100 (FIGS. 2 and 3), and in the case of a double row coil structure, the pin 12' has four ribs 100 (FIG. 4). To FIG. 6). Thus, there are two longitudinal ribs 100 between adjacent rows of longitudinal collared holes 18 '. In a preferred embodiment of the present invention, the height h _r (FIG. 9) of the rib 100 on the surface 103 of the fin 12 ′ is between 0.05 and 0.25 mm. More preferably, h _r is about 0.125 mm.

The rib 100 is also advantageous for the removal of condensate formed on the fins during the cold evaporation process. Rib 100 functions to provide a path for condensate to follow between the rows of piping in a multi-coil structure. In a single row coil structure, the rib 100 provides a flow path for condensate at both the leading and trailing edges of the fins (relative to the airflow over the fins). The rib 100 promotes the discharge of condensate from the fin 12 'and thus concomitant withdrawal of condensate, i.e. condensate is blown out of the fin and incorporated into the stream of air flowing across the fin 12'. Minimize.

Heat exchanger capacity and efficiency are determined by both fin area and tube area. An optimized heat exchanger must balance the use of fin and tube area to produce the best heat transfer between the cooling and air sides in a cost effective manner. The combination of fin 12 ′ and a smaller diameter tube (eg, 5 mm or less) according to a preferred embodiment of the present invention provides optimum heat transfer efficiency and cost efficiency.

As best shown by the perspective view of FIGS. 2 and 4, a plurality of slits 110 are disposed in the space between the collared holes 18 ′ within a predetermined longitudinal row. Each slit 110 forms a raised or raised ribbon-like segment or vane 112 that is parallel to the fin surface 103 and at the two longitudinal ends 113 at the surface of the fin 12 ′. Combined. Segment 112 defines an opening 114 that separates inlet airflow between raised vanes 112 and fin surface 103. The depth dimension d _v (FIGS. 8, 9) of the slit (along the direction of the airflow) is optimized to reduce boundary layer formation at the segment 112, which improves heat transfer capability. Preferably, d _v is 0.5 to 1.5 mm. More preferably, d _v is about 1.0 mm. The spacing depth d _i of the pin between adjacent vanes 112 is also preferably equal to the vane depth d _v .

Referring to FIG. 10, the slits 110 are arranged in an X-shaped pattern 105, with each pattern 105 of the slits 110 between each pair of colored holes 18 ′ within a predetermined longitudinal row. Repeat on In the pattern 105, according to a preferred embodiment of the present invention, the slits 110 are ideally clustered by five longitudinal rows 120, 122, 124, 126, 128, respectively. The two rows 120, 122 at the front end and the two rows 126, 128 at the rear end (based on the direction of the airflow) can employ two slits 110, respectively, for this purpose Reference numeral 113 is preferably formed at an angle α of 15 to 45 degrees with respect to the normal direction of the air flow (air flow is assumed to be perpendicular to the longitudinal direction of the pin). Ideally, α is 30 degrees. The central column 124 preferably employs a single slit 110 having an end portion 113 formed parallel to the incident airflow. Due to the physical properties of the tube and fin heat exchanger, the central portion of the fin 12 ′ having the largest distance to the adjacent tube has the lowest heat transfer efficiency. Pattern 105 is designed to guide the airflow to create better turbulence that improves heat transfer over the area. The end angles 113 of the slit 110 in the first row 120, the second row 122, the fourth row 126, and the fifth row 128 generate vortices and corresponding turbulence. .

Referring to FIG. 5, fins 12 ′ also provide optimized and balanced tube distances and fin widths for 5 mm tubing. Tube-finned heat exchangers of the prior art arranged for 7 mm to 3/8 inch diameter tubing typically have a fin width of 19 mm to 22 mm and a transverse tube pitch of 19 mm to 25.4 mm. These prior art fins 12 do not deliver optimal performance at smaller tube sizes, and as a result, larger space in the heat exchanger than is needed to utilize fins 12 'according to a preferred embodiment of the present invention. need. On the other hand, fin 12 ′ has a reduced fin width dimension [p _w ; of 12-18 mm to provide optimized heat transfer capacity and efficiency with minimal use of fin and heat tube material. That is, the distance between the centers between two adjacent collared holes 18 'in a single longitudinal row] and the transverse tube pitch dimension (p _t ; Vertical ring between the centerlines of two adjacent longitudinal rows). More preferably, p _w is 16 mm and p _t is 13.86 mm.

9, the height h _v from the top surface of the vane 112 ′ to the top surface of the pin 12 ′ is preferably 0.25 to 0.75 mm. More preferably, h _v is about 0.5 mm.

The summary of the present disclosure has been recorded only to provide a sufficient number of examples to the US Patent and Trademark Office and to quickly determine the type and gist of the technical disclosure, and the summary only indicates preferred embodiments and collectively indicates the type of the present invention. It is not.

While some embodiments of the invention have been illustrated in detail, the invention is not limited to the embodiments shown, and modifications and variations of the embodiments will be apparent to those skilled in the art. Such modifications and variations are within the spirit and scope of the invention as described herein.

12 ': Pin 18': Collar hole
100: longitudinal rib 103: upper surface (surface)
105: X-shaped pattern 110: Slit
112: vane 113: longitudinal end
114: opening

Claims (17)

As fin 12 'for tube and fin heat exchanger 10,
Generally sheet metal,
A plurality of first holes 18 'formed through the sheet metal and defining a first longitudinal row of holes 18',
First and second longitudinal ribs 100 continuously formed along the entirety of the sheet metal, wherein a first longitudinal row of holes 18 ′ is disposed between the first and second longitudinal ribs 100, Each of the first and second longitudinal ribs 100 has an upper surface protruding beyond the upper surface 103 defined by the sheet metal and no surface protruding beyond the lower surface defined by the sheet metal. The first and second longitudinal ribs 100,
A plurality of second holes 18 ′ formed through the sheet metal and defining a second longitudinal row of holes 18;
A third and fourth longitudinal rib 100 formed continuously along the entirety of the sheet metal, wherein a second longitudinal row of holes 18 ′ is disposed between the third and fourth longitudinal ribs 100, Each of the second and third longitudinal ribs 100 is disposed between first and second longitudinal rows of holes 18 ′, each of the third and fourth ribs defining an upper surface defined by the sheet metal. Third and fourth longitudinal ribs 100 having an upper surface protruding beyond 103 and no lower surface protruding beyond the lower surface defined by the sheet metal.
Finned tube and fin type heat exchanger having a. 2. The plurality of raised vanes (112) according to claim 1, wherein the plurality of raised vanes (112) form a generally X-shaped pattern (105) in said sheet metal between first and second holes (18 ') of said plurality of first holes (18'). Wherein each of the plurality of raised vanes 112 has a first and second longitudinal direction in the sheet metal such that an opening 114 is formed between the raised vanes 112 and the surface 103 of the sheet metal. Finned tube and fin heat exchanger that is formed between the slit (110). 3. The plurality of raised vanes (112) according to claim 2, wherein each of said plurality of raised vanes (112) consists of an intermediate section parallel to said planar sheet metal, said intermediate section being connected between generally planar first and second ends (113), Fins for tube and fin heat exchangers, wherein the first and second ends are connected and oriented at an acute angle with respect to the sheet metal sheet. 4. The plurality of raised vanes (112) according to claim 3, wherein the plurality of raised vanes (112) are arranged in a first row (120), a second row (122), a third row (124), and a second parallel to the first longitudinal rib (100). Fins for tube and fin heat exchangers disposed in four rows (126) and a fifth row (128). 4. The method of claim 3, wherein the first and second ends 113 of at least one of the plurality of raised vanes 112 are oriented at an angle α from an imaginary line perpendicular to the first longitudinal rib 100. And the angle α is 15 to 45 degrees. The fin for tube and fin heat exchanger according to claim 5, wherein the angle α is 25 to 35 degrees. 9. The nine raised vanes (112) of claim 1, wherein a generally X-shaped pattern (105) is formed in said sheet metal between first and second holes (18 ') of said plurality of first holes (18'). More,
Each of the nine raised vanes 112 is formed between the first and second longitudinal slits 110 in the sheet metal such that an opening 114 is formed between the raised vanes 112 and the surface 103 of the sheet metal. Formed on,
Each of the nine raised vanes 112 consists of a middle section parallel to the faceted sheet metal, the middle section being generally connected between the faceted first and second ends 113 and the first and second ends. Is connected to the sheet metal and oriented at an acute angle,
The first and second vanes 112 of the nine raised vanes 112 are disposed in a first row 120 of vanes 112 parallel to the first longitudinal rib 100, and the nine The third and fourth vanes 112 of the two raised vanes 112 are disposed in the second row 122 of the vanes 112 parallel to the first longitudinal rib 100, and the nine lifts The fifth vane 112 of the vane 112 is disposed in the third row 124 of the vanes 112 parallel to the first longitudinal rib 100, and the second row of vanes 112 ( 122 is disposed adjacent to the first and third rows between the first row 120 and the third row 124 of the vanes 112 and the sixth and seventh of the nine raised vanes 112. The vanes 112 are disposed in the fourth row 126 of the vanes 112 parallel to the first longitudinal ribs 100, and the third row 124 of the vanes 112 is formed of the vanes 112. Disposed between the second row 122 and the fourth row 126 and adjacent to the second and fourth rows, the eighth and ninth vanes of the nine raised vanes 112. 112 is disposed in a fifth row 128 of vanes 112 parallel to the first longitudinal rib 100, and a fourth row 126 of vanes 112 is formed in the vanes 112. Fins for tubes and fin heat exchangers disposed between the third row and the fifth row and adjacent to the third row and the fifth row. The tube and fin of claim 3, wherein each of the plurality of raised vanes 112 has a depth dimension d _v of 0.5 to 1.5 mm from the first slit 110 to the second slit 110. Fin for heat exchanger. 4. The height dimension h _v of each of the plurality of raised vanes 112 from the top surface 103 of the sheet metal to the top surface of the vane 112 is in the range of 0.25 to 0.75 mm. Fins for tubes and fin heat exchangers. The tube and fin heat exchange of claim 3, wherein each of the ribs 100 has a height dimension h _r from the top surface 103 of the sheet metal to the top surface of the rib 100. Instrument pin. The longitudinal distance p _w between the centers of two adjacent holes 18 ′ of the plurality of first holes 18 ′ in the first longitudinal row of holes 18 ′ is 12. And fins for tube and fin heat exchangers. 4. The tube of claim 3, wherein the vertical distance p _t between the center of the first longitudinal row of holes 18 ′ and the center of the second longitudinal row of holes 18 ′ is between 10 and 15 mm. Fins for fin heat exchangers. As fin 12 'for tube and fin heat exchanger 10,
Generally sheet metal,
A plurality of first holes 18 'formed through the sheet metal and defining a first longitudinal row of holes 18',
A plurality of raised vanes 112 forming an X-shaped pattern 105 generally in the sheet metal between the first and second holes 18 'of the plurality of first holes 18'.
And each of the plurality of raised vanes 112 includes first and second parallel slits in the sheet metal such that an opening 114 is formed between the raised vanes 112 and the surface 103 of the sheet metal. Between 110),
Each of the plurality of raised vanes 112 is composed of an intermediate section parallel to the faceted sheet metal, the intermediate section being generally connected between the planar first and second end portions 113 and the first and second end portions. Fins for tube and fin heat exchanger, wherein the fins are connected to the sheet metal and oriented at an acute angle. The first and second vanes 112 of the plurality of raised vanes 112 are arranged in a first row of vanes 112 parallel to the first longitudinal rows of the holes 18 '. 120)
Third and fourth vanes 112 of the plurality of raised vanes 112 are disposed in a second row 122 of vanes 112 parallel to the first longitudinal row of holes 18 ',
The fifth vanes 112 of the plurality of raised vanes 112 are disposed in the third row 124 of the vanes 112 parallel to the first longitudinal rows of the holes 18,
Sixth and seventh vanes 112 of the plurality of raised vanes 112 are disposed in a fourth row 126 of vanes 112 parallel to the first longitudinal row of holes 18 ',
Eighth and ninth vanes 112 of the plurality of raised vanes 112 are disposed in a fifth row 128 of vanes 112 parallel to the first longitudinal row of holes 18 ',
The second row 122 of the vanes 112 is disposed adjacent to the first row and the third row between the first row 120 and the third row 124 of the vane 112.
The third row 124 of the vanes 112 is disposed between the second row 122 and the fourth row 126 of the vanes 112 and is disposed adjacent to the second row and the fourth row.
The fourth row 126 of the vanes 112 is disposed between the third row and the fifth row 128 of the vanes 112 and is disposed adjacent to the third and fifth rows. Fin for heat exchanger. 15. The method of claim 14, wherein first and second of each of the first, second, third, fourth, sixth, seventh, eighth and ninth vanes 112 of the plurality of raised vanes 112. The distal end (113) is oriented at an angle (α) of 15 to 45 degrees from an imaginary line perpendicular to the first longitudinal column of the aperture (18 '). Tube and fin heat exchanger (10),
A plurality of fins 12 'disposed in a stack, and a tube 22 received through the stack and in physical contact with each of the plurality of fins 12, each of the plurality of fins 12' ,
Generally sheet metal,
A plurality of first and second holes 18 'formed through the sheet metal and defining first and second longitudinal rows of holes 18', respectively;
First and second longitudinal ribs 100 continuously formed along the entirety of the sheet metal, wherein a first longitudinal row of holes 18 ′ is disposed between the first and second longitudinal ribs 100, Each of the first and second longitudinal ribs 100 has an upper surface protruding beyond the upper surface 103 defined by the sheet metal and no surface protruding beyond the lower surface defined by the sheet metal. The first and second longitudinal ribs 100,
A third and fourth longitudinal rib 100 formed continuously along the entirety of the sheet metal, wherein a second longitudinal row of holes 18 ′ is disposed between the third and fourth longitudinal ribs 100, Each of the second and third longitudinal ribs 100 is disposed between first and second longitudinal rows of holes 18 ′, each of the third and fourth ribs defining an upper surface defined by the sheet metal. Third and fourth longitudinal ribs 100 having an upper surface protruding beyond 103 and no lower surface protruding beyond the lower surface defined by the sheet metal.
Tube and fin heat exchanger comprising a. Tube and fin heat exchanger (10),
A plurality of fins 12 'disposed in a stack, and a tube 22 received through the stack and in physical contact with each of the plurality of fins 12, each of the plurality of fins 12' ,
Generally sheet metal,
A plurality of first holes 18 'formed through the sheet metal and defining a first longitudinal row of holes 18',
A plurality of raised vanes 112 forming an X-shaped pattern 105 generally in the sheet metal between the first and second holes 18 'of the plurality of first holes 18'.
And each of the plurality of raised vanes 112 includes first and second parallel slits in the sheet metal such that an opening 114 is formed between the raised vanes 112 and the surface 103 of the sheet metal. Between 110),
Each of the plurality of raised vanes 112 is composed of an intermediate section parallel to the faceted sheet metal, the intermediate section being generally connected between the planar first and second end portions 113 and the first and second end portions. And the fin-type heat exchanger is connected to the sheet metal of the face and oriented at an acute angle.

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