US20120073785A1

US20120073785A1 - Compact high efficiency air to air heat exchanger with integrated fan

Info

Publication number: US20120073785A1
Application number: US13/247,058
Authority: US
Inventors: Nicholas HERRICK-KAISER
Original assignee: Ametek Inc
Current assignee: Ametek Inc
Priority date: 2010-09-28
Filing date: 2011-09-28
Publication date: 2012-03-29

Abstract

A heat exchanger for a sealed enclosure is disclosed that includes a separator plate and a motor secured to the separator plate. The motor rotates a shaft having opposed ends, an ambient air impeller is secured to one end of the shaft, and an enclosed air impeller is secured to an opposite end of the shaft. An ambient shell secured to the separator plate substantially encloses the ambient air impeller and an enclosed air shell secured to the separator plate substantially encloses the enclosed air impeller. Each shell has an axial opening and a radial opening and a plurality of curvilinear fins extending between the separator plate and the shells. Airflow through the enclosed air shell imparts heat to the fins which transfer the heat for rejection by the airflow through the ambient air shell.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of U.S. Provisional Application Ser. No. 61/387,094 filed Sep. 28, 2010, which is incorporated herein by reference.

TECHNICAL FIELD

Generally, the present invention is directed to an air to air heat exchanger. Specifically, the present invention is directed to an exchanger which removes heat from one volume of air and rejects it into another volume of air.

BACKGROUND ART

There exist many air cooled heat sinks and air to air heat exchangers throughout industry. However, the prior art designs are no longer adequate for handling increasing thermal loads from electronic equipment.
Typically in industry, heat exchangers comprise a motor-driven fan and heat sink as two separately designed components which are then simply attached to each other. Such designs result in mis-match inefficiencies and poor performance. Moreover, such constructions result in high power consumption by the motor which may result in pre-mature failure of the assembly.
A prior art heat exchange system is shown in FIG. 1. In such a system, a sealed enclosure is provided where it is desired to maintain the air within the enclosure separate from ambient air outside the enclosure. The air within the enclosure may be kept separate for any number of reasons, but most likely so as to prevent contaminants from outside, or the ambient air, from adversely affecting components maintained within the enclosure. The enclosure includes heat producing electronics which must be cooled so as to ensure their operability. The enclosure maintains a wall which has mounted thereto a heat exchanger that operates by circulating heated air in the enclosure and ambient air outside the enclosure. The heat exchanger absorbs heat within the enclosure and the circulating ambient air draws that heat off and expels it outwardly away from the enclosure so as to maintain an operating temperature within the sealed enclosure. One proposed solution is to use a plurality of pins in each side of the heat exchanger. The pins provide a low impedance heat sink and an increased surface area. Although an improvement, the pins' surface area and shape do not enhance, and in some cases impedes, the airflow, which in turn increases power consumption.
Therefore, there is a need in the art for heat exchangers which provide improved air-flow efficiency while also reducing power consumption. There is also a need to efficiently transfer heat without any loss in performance, and there is a need to provide these features in a reduced size without sacrificing the effectiveness of the configuration.

SUMMARY OF THE INVENTION

In light of the foregoing, it is a first aspect of the present invention to provide a compact high efficiency air to air heat exchanger with integrated fan.
It is another aspect of the present invention to provide a heat exchanger for a sealed enclosure, comprising a separator plate, a motor secured to the separator plate, said motor rotating a shaft having opposed ends, an ambient air impeller secured to one end of the shaft and an enclosed air impeller secured to an opposite end of said shaft, an ambient shell secured to the separator plate and substantially enclosing the ambient air impeller and an enclosed air shell secured to the separator plate and substantially enclosing the enclosed air impeller, each shell having an axial opening and a radial opening, and a plurality of curvilinear fins extending between the separator plate and the shells.
It is yet another aspect of the present invention to provide a heat exchanger, comprising a plate, a motor having a rotatable shaft with opposed ends, the motor carried by the plate, an impeller carried by each opposed end of the shaft, a shell partially enclosing each impeller and spaced apart from the plate to form a corresponding radial opening, each shell having an axial opening, and a plurality of fins extending between the plate and each shell, wherein rotation of the impellers draws air in through the axial openings, over the plurality of fins and out the radial openings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings wherein:

FIG. 1 is a schematic drawing of a prior art heat exchange system showing the general operational concepts of a heat exchanger for a sealed enclosure;

FIG. 2 is a schematic drawing of a heat exchange system according to the concepts of the present invention;

FIG. 3 is a cross-sectional view of a heat exchange system in accordance with the concepts of the present invention;

FIG. 4 is an elevational view of the heat exchange system with a cover shell removed so as to show a plurality of curvilinear fins according to the concepts of the present invention;

FIG. 5 is a cross-sectional view taken along lines 5-5 of FIG. 4 showing further details of the curvilinear fins and the heat exchange system; and

FIG. 6 is a detailed view of FIG. 4 that shows an air impeller in relation to the curvilinear fins.

BEST MODE FOR CARRYING OUT THE INVENTION

A heat exchanger device according to the present invention consists of two major components. The first component is a two-sided heat sink—an aluminum heat sink with two substantially identical sides. One side removes heat and cools air, heat then passes through the metal body, then the other side rejects the heat into a cooling airstream. The second major component of the heat exchanger is an integrated fan system which consists of one central motor, drive electronics, and a bearing system which powers two air moving centrifugal impellers—one for each side of the heat sink. Integration and interaction of the fan and the heat sink provides many advantages over prior art configurations. By integrating the fan system, the size of the heat exchanger becomes compact. Interaction between radial fins of the heat sink and centrifugal impeller allows for higher fan efficiency due to the recovery of dynamic pressure.
As will be discussed in detail, heat sink fins are oriented such that the exiting airflow path from the impellers is disrupted as little as possible during transition into the heat sink. From there, smooth recovery of dynamic pressure through the heat sink is achieved. In addition to the heat sink and fan system, there are two covers which are attached to respective sides of the heat sink. These covers force airflow from the impellers to pass through the channels in the heat sink.
Referring now to FIGS. 2-6, it can be seen that a heat exchange system according to the concepts of the present invention is designated generally by the numeral 10. The system 10 is configured for attachment to a housing wall 12 which separates the ambient air from the enclosed air of a sealed enclosure. Maintained within the system 10 is a motor 14 from which extends a shaft 16. The shaft extends axially from both sides of the motor and one end of the shaft 16 rotates an ambient air impeller 18 while an opposite end of the shaft rotates an enclosed air impeller 20. An ambient shell 22 at least partially encloses the ambient air impeller 18 and in a similar manner an enclosed shell 24 at least partially encloses the enclosed air impeller 20. Both shells 22 and 24 substantially cover their respective impellers and are provided in a tapered configuration as best seen in FIG. 3. However, skilled artisans will appreciate that the shells could be flat so as to be substantially parallel with the wall 12 of the sealed enclosure. Or the shells could be provided with an inverse taper or any other shape needed to meet the dimensional requirements of the sealed enclosure. Moreover, the impellers 18 and 20 may be shaped to match the corresponding shape of the corresponding shell 22 and 24 to enhance air flow efficiency. The impellers 18 and 20 typically include vanes or fins which may or may not be on a disc rotated by the motor shaft. Additionally, the vanes may be partially enclosed or not. In any event, each shell 18 and 20 has respective axial openings 26 and 27, and respective radial openings 28 and 29. As skilled artisans will appreciate, as the impellers are rotated by the motor shaft, air is drawn in through the axial openings and expelled out the radial openings. Each opening 28 and 29 is defined by a shell edge 62 which in most embodiments is of a circular configuration.
As best seen in the detailed FIG. 3, a separating plate 30 is utilized by the system wherein the outer periphery of the plate 30 is adapted to be secured and sealed to the housing wall 12 by fasteners, welding or other secure mechanical attachment. Extending from the separating plate 30 in a central region is an internal motor bracket 34 for carrying the motor 14 and related components. Bearings 38 are utilized to facilitate rotation of the motor shaft 16 with respect to the internal motor bracket 34. Wire leads 42 are connected to the motor 14 and any particular control elements wherein the opposite end of the wire leads are maintained in a connector that is connected to an appropriate power supply. As shown in FIG. 3, the connector is mounted within or adjacent the shell which is maintained internally within the housing wall 12.
Each impeller 18 and 20 maintains a disc 52 a, 52 b from which extends a plurality of curvilinear vanes 54 a, 54 b. As used herein, the “a” suffix is used for components associated with the ambient air impeller 18 and the “b” suffix is used for components associated with enclosed air the impeller 20. Each vane provides a leading edge 56 opposite a trailing edge 58. It will be appreciated that the vanes 54 extends substantially perpendicularly from the disc 52. A top edge 60 interconnects the edges 56 and 58 and is positioned in a relatively close proximity to an underside of the associated shell. Collectively, the leading edges 56 are sized to form a diameter that is substantially equivalent to the diameter formed by the shell edge 62. Positioning of the leading edges 56 in this way allows the efficient pulling in of air through the axial openings.
Positioned radially away from the impellers 18 and 20 and extending axially from both sides of the separating plate 30 are a plurality of curvilinear fins 70. The curvilinear fins extend from the separating plate to an underside 71 of each respective shell. In other words, each fin has a top edge 73 contacting an underside of the adjacent shell along an entire length thereof and a bottom edge 75 in contact with the separator plate 30, along an entire length thereof. The edges 73 and 75 may be integrally formed with the separator plate 30 or with their respective shells 22 or 24. A fin gap 72 is provided between each curvilinear fin 70 and each fin is provided with a leading edge 74 that is proximally adjacent the impellers and a trailing fin edge 76 which is positioned away from each impeller and disposed proximally the outer periphery of the shells. The leading edges 74 are of a greater dimensional height than the trailing edges 76 so that the respective top edges are in contact with the tapered shell. Tapering of the shells ensures efficient airflow therethrough. It will be appreciated that the fin gap 72 provides an enclosed airflow passageway that is formed by the adjacent curvilinear fins, the enclosing shell 22 or 24, and the separator plate. The enclosed passageway allows for the efficient capture of air exhausted by the trailing edges of the impeller vanes. Each passageway expands laterally but diminishes in height where it exits by virtue of the tapered shells and the way in which the fins are configured. In other words, the passageways expand laterally and diminish in height from their respective axial openings to the respective radial openings. This configuration provides an efficient absorption of heat from within the enclosure, efficient transfer of heat through both sets of curvilinear fins on both sides of the plate 30, and an efficient dissipation of the transferred heat into the ambient.
As best seen in FIG. 6, a chamber 80 is formed between the trailing edges 58 of each respective impeller 18 and 20 and the leading fin edge of the respective curvilinear fins 70. The chamber 80 facilitates collection of air exhausted by the impellers and assists in transitioning the exhausted air into the passageways.
In operation, energization of the motor 14 initiates rotation of the motor shaft and the impellers 18 and 20. Inside the enclosure, air heated by the electronics or other heat generating mechanisms is drawn in axially through the opening 26 and expelled out the radial openings 28. During this airflow process, the heated air contacts the curvilinear fins and excess heat is absorbed therein. This heat migrates from the enclosure side through the separating plate to the fins maintained on the ambient side. Simultaneously, rotation of the shaft 16 results in airflow movement of cooling air through the axial opening 27, through the gaps and associated passageways provided by the curvilinear fins and out the radial openings. Accordingly, the flow of ambient air withdraws the heat absorbed by these fins so as to provide for an effective heat transfer from the interior of the enclosure to the exterior of the enclosure.
Skilled artisans will appreciate that the present construction has a number of advantages. The present construction provides a highly compact and energy efficient performance. This is accomplished by integrating a centrifugal blower and motor paired with a complimentary heat sink so as to obtain high levels of efficiency. The present construction greatly improves the thermal load that can be absorbed or transferred while still maintaining all other operational characteristics. Such a configuration also reduces power consumption. This has been accomplished by utilizing curvilinear fins in conjunction with the airflow configuration to facilitate the exchange of heat, wherein the curvilinear fins are utilized to assist in the airflow movement of the fan configurations. This allows for larger surface areas within the circular confines of the system envelope to be utilized and further allows the vanes to recover dynamic pressure from the impeller thereby increasing blower efficiency. Although the present embodiment is directed for use with a sealed enclosure, other embodiments may use the heat exchange system 10 in a non-sealed enclosure.
Thus, it can be seen that the objects of the invention have been satisfied by the structure and its method for use presented above. While in accordance with the Patent Statutes, only the best mode and preferred embodiment has been presented and described in detail, it is to be understood that the invention is not limited thereto or thereby. Accordingly, for an appreciation of the true scope and breadth of the invention, reference should be made to the following claims.

Claims

1. A heat exchanger for an enclosure, comprising:

a separator plate;

a motor secured to said separator plate, said motor rotating a shaft having opposed ends;

an ambient air impeller secured to one end of said shaft and an enclosed air impeller secured to an opposite end of said shaft;

an ambient shell secured to said separator plate and substantially enclosing said ambient air impeller and an enclosed air shell secured to said separator plate and substantially enclosing said enclosed air impeller, each said shell having an axial opening and a radial opening; and

a plurality of curvilinear fins extending between said separator plate and said shells.

2. The heat exchanger according to claim 1, wherein said separator plate is adapted to be secured to a housing wall of an enclosure, said enclosed air impeller moving heated air over said plurality of curvilinear fins and said ambient air impeller moving air over said plurality of curvilinear fins, said fins transferring heat from the heated air to the ambient air.

3. The heat exchanger according to claim 1, wherein said shells are tapered.

4. The heat exchanger according to claim 3, wherein said axial openings are defined by a shell edge, each said impeller having a plurality of vanes each having a leading edge, said leading edges collectively forming a diameter substantially equivalent to said shell edge.

5. The heat exchanger according to claim 3, wherein said fins have a top edge contacting said adjacent shell along an entire length thereof and a bottom edge contacting said separator plate along an entire length thereof.

6. The heat exchanger according to claim 1, wherein said fins have a top edge contacting said adjacent shell along an entire length thereof and a bottom edge contacting said separator plate along an entire length thereof.

7. A heat exchanger, comprising:

a plate;

a motor having a rotatable shaft with opposed ends, said motor carried by said plate;

an impeller carried by each said opposed end of said shaft;

a shell partially enclosing each said impeller and spaced apart from said plate to form a corresponding radial opening, each said shell having an axial opening; and

a plurality of fins extending between said plate and each said shell, wherein rotation of said impellers draws air in through said axial openings, over said plurality of fins and out said radial openings.

8. The heat exchanger according to claim 7, wherein said plurality of fins integrally extend from either said plate or said shells.

9. The heat exchanger according to claim 7, wherein said plurality of fins are curvilinear so as to form gaps therebetween that are used as passageways that expand laterally from said axial opening to said radial opening.

10. The heat exchanger according to claim 9, wherein each said shell is tapered so that said fins diminish in height from said axial opening to said radial opening.

11. The heat exchanger according to claim 10, where each said impeller has a plurality of vanes wherein each said vane has a leading edge proximal said adjacent axial opening and a trailing edge proximal said fins.

12. The heat exchanger according to claim 11, wherein said trailing edges and said fins form a circular chamber therebetween.