WO2001081849A1

WO2001081849A1 - Integral fin passage heat exchanger

Info

Publication number: WO2001081849A1
Application number: PCT/US2001/012965
Authority: WO
Inventors: Stephen L. White; Brian S. Naumann
Original assignee: Honeywell International Inc.
Priority date: 2000-04-25
Filing date: 2001-04-23
Publication date: 2001-11-01
Also published as: US20020153129A1

Abstract

A plate-fin heat exchanger (10) includes a plurality of integral fin passages (12) and a plurality of fins (14). Each fin (14) is located between and bonded to outer surfaces of adjacent integral fin passages (12). Each integral fin passage (12) has integrally formed plates (16) and extended surfaces (18). The integral fin passages (12) may be formed by extrusion.

Description

INTEGRAL FIN PASSAGE HEAT EXCHANGER

BACKGROUND OF THE INVENTION

The present invention relates generally to heat exchangers More specifically, the present invention relates to a plate-fin heat exchanger

A typical plate-fin heat exchanger includes a core and manifolds The core includes a plurality of plates, a plurality of fins located between and bonded to the plates, and a plurality of closure bars. The plates and fins define hot side and cold side passageways. The closure bars provide closure of the fins and precise spacing between the plates. During operation of the heat exchanger, a hot fluid flows through the hot side passageways and a cold fluid flows through the cold side passageways. Heat is transferred from the hot fluid to the cold fluid. The manifolds direct the hot fluid and cold fluid to and from the hot side and cold side passageways.

A large number of parts are assembled during construction of the metal core, and great care is taken to assemble the parts. A large number of welds and braze joints are made during the construction of the metal core

Reducing the number of parts would simplify the construction of the metal core and reduce the cost of construction. Reducing the number of parts would also reduce the number of brazed joints that could possibly leak

Therefore, it is desirable to reduce the parts count of plate-fin heat exchangers.

SUMMARY OF THE INVENTION The core of a plate-fin heat exchanger according to the present invention has a reduced parts count. The heat exchanger core comprises first and second integral fin passages, each integral fin passage having integrally formed plates and extended surfaces; and a fin located between and bonded to outer surfaces of the first and second integral fin passages Reducing the parts count simplifies the construction of the core and reduces the number of brazed joints that could possibly leak. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an exploded view of a heat exchanger core according to the present invention;

Figures 2a and 2b are illustrations of two different fin geometries;

Figure 3 is an illustration of a header plate and integral fin passages of another heat exchanger core according to the present invention;

Figure 4 is a flowchart of a method of constructing a heat exchanger according to the present invention; and

Figures 5a and 5b are illustrations of different profiles of passageways within the integral fin passages.

DETAILED DESCRIPTION OF THE INVENTION Reference is made to Figure 1 , which illustrates a heat exchanger core 10. The core 10 includes a plurality of integral fin passages 12 and a plurality of fins 14. Each integral fin passage 12 includes a pair of plates 16 and a plurality of extended surfaces 18 between the plates 16. The plates 16 and the extended surfaces 18 define straight fluid passageways 20. The two extended surfaces 18a and 18b at the edges of the plates 16 also function as closure bars.

The plates 16 and the extended surfaces 18 are integrally formed. That is, they form a unitary structure. For instance, the integral fin passages 12 may be formed by extrusion. Any extrudable material having good heat transfer characteristics may be used for the integral fin passages 12. Such material includes, without limitation, copper and aluminum. Using integral fin passages 12 reduces the parts count of the heat exchanger core 10.

Each fin 14 is located between and bonded to outer surfaces of adjacent integral fin passages 12. Each fin 14 may have a metal core 14a that is clad with a braze material 14b (a portion of the braze material has been removed to show the metal core 14a). The braze material 14b enhances the bond between the fins 14 and the extruded passages 12.

The plates 16 and the fins 14 define second fluid passageways 22. The second fluid passageways 22 may provide any type of flow path. For example, the second fluid passageways 22 may be straight and arranged to provide a cross-flow relative to the first fluid passageways 20. The core 10 may instead include inlet and outlet turning fins 24 for providing co-current (i.e., same direction) or countercurrent (i.e., opposite direction) flow relative to the first fluid passageways 20. The inlet and outlet turning fins 24 may be oriented to provide generally either a Z-flow path or a U-flow path. A Z-flow path begins at one end of the heat exchanger core 10 and ends at an opposite side and opposite corner. A U-flow path begins and ends on the same side, but opposite corners of the core 10. The inlet and outlet turning fins 24 may be oriented at various angles relative to the first fluid passageway 20. Figure 1 happens to show fins 14 providing a Z-flow path, with the turning fins 24 being oriented at a 90 degree angle relative to the first fluid passageway 20.

The integral fin passages 12 and fins 14 may be stacked in an alternating sequence (in the z-direction). Thus, each fin 14 is located between a pair of adjacent integral fin passages 12.

Individual closure bars 26 may be located at edges of, and brazed between, plates 16 of adjacent integral fin passages 12. Each individual closure bar 26 may be made of a metal core having a braze cladding. The closure bars 26 provide closure for the second fluid passageways 22 and they provide precise spacing between the integral fin passages 12. Closure for the second fluid passageways 22 may be provided by four straight or two L- shaped closure bars. The topmost closure bars 26 have been omitted for clarity.

Instead of using individual closure bars 26, closure bars for the sides of the fins 14 (in the direction of the first fluid passageways 20) may be formed integrally with the plates 16 of the integral fin passage 12. An extruded closure bar of one integral passage would be brazed or welded to an adjacent integral fin passage 12. Forming the fin closure bars as part of the integral fin passages 12 further reduces the parts count of the heat exchanger core 10.

The integral fin passages 12 may provide the hot side or cold side passageways. During operation of the heat exchanger shown in Figure 1 , a first fluid enters the first end of the integral fin passages 12, passes straight though the core 10 (in a y-direction) and exits a second end of the integral passages 12. A second fluid enters one corner of the core 10 (in an x- direction), is turned to flow parallel to the first fluid (in the y-direction), and is turned again to flow out of the opposite corner of the core 10 (in the x- direction). Heat is transferred from the hot fluid to the cold fluid. Manifolds (not shown) direct the hot fluid and cold fluid to and from the hot side and cold side passageways.

The fins 14 may have any typical heat transfer fin geometry. For example, the fin geometry may be plain rectangular (Figure 1), rectangular offset (Figure 2a) or wavy (Figure 2b). Other types of fin geometries include, without limitation, perforated geometry, plain triangular geometry and louvered geometry.

The heat exchanger core 10 may provide any type of flow path. Types of countercurrent and co-current paths include, without limitation, straight flow paths, 'Z'-flow paths and 'U'-flow paths.

A simple cross flow heat exchanger having an entirely straight rectangular fin geometry may be formed by stacking integral fin passages in a z-direction. Integral fin passages for the hot fluid may extend in the x- direction and integral fin passages for the cold fluid may extend along the y- direction.

Referring now to Figure 3, another heat exchanger core 110 includes first and second header plates 126 instead of the individual closure bars. The header plates 126 serve the same function as the individual closure bars: providing closure for the fluid flowing between each of the integral fin passages 112 as well as providing precise spacing between the integral fin passages 112. The header plates 126 may be machined or formed from sheet metal. A heat exchanger core 110 having two header plates 126 has a lower parts count than a core 10 having multiple closure bars 26. The integral fin passages 112 may be brazed or welded to the header plates 126.

Reference is now made to Figure 4. A method of fabricating a heat exchanger core includes the following steps. A plurality of integral fin passages are provided, with each integral fin passage having been extruded to form plates and extended surfaces (block 202). Fins and closure structures (e.g., closure bars, header plates) are assembled with the integral fin passages (block 204). The fins and closure structures are brazed or otherwise bonded to the integral fin passages (block 206). Thus, the integral fin passages, the fins and the closure structures are brazed together at the same time. After the core has been brazed, manifolds are welded or otherwise mounted to the closure bars of the heat exchanger core (block 208). The manifolds may also be clad with a braze material.

The integral fin passages are not limited to passageways having rectangular profiles. The passageways may have round or other profiles. See, for example, Figures 5a and 5b.

The integral fin passages are not limited to the design shown in the drawings. For instance, an alternative integral fin passageway could include a flattened tube and a fin within the flattened tube. Such an alternative integral fin passage would have plates and closure bars that are integrally formed.

The present invention is not limited to the specific embodiments described above. Instead, the present invention is construed according to the claims that follow.

Claims

WHAT IS CLAIMED IS:

1. A heat exchanger (10) comprising: first and second integral fin passages (12), each integral fin passage having integrally formed plates (16) and extended surfaces (18); and a fin (14) located between and bonded to outer surfaces of the first and second integral fin passages.

2. The heat exchanger of claim 1 , wherein extended surfaces (18a, 18b) at edges of the plates provide closure bars for the integral fin passages.

3. The heat exchanger of claim 2, wherein at least one integral fin passage further includes a closure bar (26) for the fin.

4. The heat exchanger of claim 2, further comprising closure bars (26) for the fin, each closure bar being located between and bonded to the outer surfaces of the first and second integral fin passages.

5. The heat exchanger of claim 1 , further comprising first and second header plates (126), first ends of the integral fin passages (112) fitting into slots in the first header plate, second ends of the integral fin passages fitting into slots in the second header plate, the header plates providing closure for the fin.

6. The heat exchanger of claim 1 , wherein each integral fin passage (12) provides a plurality of straight fluid flow passageways (20).