Method for Making a Shaped Multichannel Heat Exchanger
A technique is provided for forming and coating heat exchangers. The heat exchanger may be of any suitable type, such as employing two or more manifolds, with tubes, such as multichannel tubes extending between the manifolds, with fins being provided around or between the tubes. The overall heat exchanger structure is made as a slab that is advanced through an oven, such as in a brazing zone. Heat applied in the brazing zone heats the entire slab to an elevated temperature, and immediately after the brazing zone the slab is hot formed to provide bends or other configurations or contours. A coating is then applied at the elevated temperature, and the heat exchanger may advance through a curing station at which cooling is controlled to promote curing of the coating. The overall process provides a streamlined integrated assembly and manufacturing procedure for formed and coated heat exchangers.
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This application claims priority from and the benefit of U.S. Provisional Application Ser. No. 60/867,043, entitled MICROCHANNEL HEAT EXCHANGER APPLICATIONS, filed Nov. 22, 2006, U.S. Provisional Application Ser. No. 60/882,033, entitled MICROCHANNEL HEAT EXCHANGER APPLICATIONS, filed Dec. 27, 2006, and U.S. Provisional Application Ser. No. 60/909,598, entitled MICROCHANNEL COIL HEADER, filed Apr. 2, 2007, which are hereby incorporated by reference.
BACKGROUNDThe present invention relates generally to methods for making a shaped mulitchannel heat exchanger.
Heat exchangers are used in a variety of settings and for many purposes. For example, liquid-to-air heat exchangers are used throughout industry, and in many heating, ventilating, air conditioning and refrigeration applications. The latter applications include residential, commercial, and industrial air conditioning systems in which heat exchangers serve as both condensers and evaporators in a thermal cycle. In general, when used in as an evaporator, liquid or primarily liquid refrigerant enters a heat exchanger and is evaporated to draw thermal energy from an air flow stream that is drawn over the heat exchanger tubes and fins. When used as a condenser, the, refrigerant enters in a vapor phase (or a mixed phase) and is de-superheated, condensed and sub-cooled in the condenser.
Recent developments in heat exchanger designs have included the use of multichannel or multiple channel tubes. These tubes are often generally flat in shape, and include a number of parallel fluid passageways along their width. Current designs include from 16 to 24 passages, although the number of passages may vary, as may their internal configuration. The tubes are generally aligned parallel with one another and in fluid communication with manifolds used to distribute and collect the refrigerant. Heat exchanging fins are disposed between the tubes and aid in transferring heat to or from the fluid flowing through the internal passage ways of the tubes.
Depending upon the application, heat exchangers may be provided in various forms and shapes. In the simplest applications, a generally planar slab configuration is provided, with all tubes being parallel with one another and in generally the same plane as the manifolds. However, in other applications it is particularly advantageous to bend or wrap the heat exchangers around other equipment to increase the density of the heat exchanger capabilities. For example, in many residential air conditioners, an outside heat exchanger is wrapped around two, three, or even four sides of other system components, and single or multiple fans draw air through the wrapped heat exchanger.
A difficulty in the manufacturing of such heat exchangers involves processes used to initially form the heat exchanger slabs, followed by processes for bending the slabs and painting or coating the slabs with a desired external coating. Where manufacturing operations occur at different locations, it is most beneficial to form flat slabs and transport these for storage and manufacturing to other locations in this flat configuration. In certain system designs, then, at a second manufacturing location the slabs are cold formed to provide their ultimate wrapped shape. Where paints or coatings are then applied that require curing at elevated temperatures, separate heating arrangements must be provided for the coatings. Current manufacturing techniques do not allow for enhanced integration of these processes.
SUMMARYIn accordance with aspects of the invention, a method for making a heat exchanger is presented. The method includes conveying through an oven, an assembled heat exchanger including a plurality of multichannel tubes extending between a pair of manifolds, to permanently join the multichannel tubes to the manifolds, and hot forming the multichannel tubes and/or manifolds in a forming station downstream of the oven at least partially utilizing heat energy transmitted to the heat exchanger in the oven.
In accordance with further aspects of the invention, a method for making a heat exchanger is presented. The method includes conveying through an oven, an assembled heat exchanger including a plurality of multichannel tubes extending between a pair of manifolds, to permanently join the multichannel tubes to the manifolds, applying a coating to the heat exchanger utilizing heat energy transmitted to the heat exchanger in the oven, and controlling the temperature of the heat exchanger and the coating to cure the coating and to cool the heat exchanger.
In accordance with yet further aspects of the invention, a system for making a heat exchanger is provided. The system includes a heat exchanger assembling station at which a plurality of multichannel tubes are assembled between a pair of manifolds, an oven through which the assembled heat exchanger is conveyed to permanently join the multichannel tubes to the manifolds, and a hot forming station downstream of the oven at which the heat exchanger is formed at least partially utilizing heat energy transmitted to the heat exchanger in the oven.
When the system shown in
The outdoor unit draws in environmental air through sides as indicated by the arrows directed to the sides of unit OU, forces the air through the outer unit coil by a means of a fan (not shown) and expels the air as indicated by the arrows above the outdoor unit. When operating as an air conditioner, the air is heated by the condenser coil within the outdoor unit and exits the top of the unit at a temperature higher than it entered the sides. Air is blown over indoor coil IC, and is then circulated through the residence by means of ductwork D, as indicated by the arrows in
When the unit in
Chiller CH, which includes heat exchangers for both evaporating and condensing a refrigerant as described above, cools water that is circulated to the air handlers. Air blown over additional coils that receive the water in the air handlers causes the water to increase in temperature and the circulated air to decrease in temperature. The cooled air is then routed to various locations in the building via additional ductwork. Ultimately, distribution of the air is routed to diffusers that deliver the cooled air to offices, apartments, hallways, and any other interior spaces within the building. In many applications, thermostats or other command devices (not shown in
Referring to
It should be noted that, while heat exchanger 10 is illustrated as including multichannel tubes, other tubes could be used in the heat exchanger, and the techniques described below could also be adapted to forming such heat exchangers. The orientation of the tubes and of the manifolds should not be considered as limiting in any way. That is, the manifolds themselves could be bent, with bends in the heat exchanger being made along the direction of the tubes, and the manifolds positioned in upper and lower locations, generally opposite or at right angles to the orientation illustrated in
For example,
At a flux station 50, material is sprayed or otherwise applied to the assembled heat exchanger that will serve to join the components together and to seal locations at which the tubes and manifolds are joined. While these materials may be generally described as a “flux”, those skilled in the art will appreciate that the particular compositions of the materials may vary widely, depending upon the materials used for the heat exchanger itself and the conditions under which the heat exchanger is to operate, as well as those conditions under which the heat exchanger is manufactured. In general, the flux will completely coat the components described above, and will remain on the heat exchanger following manufacturing. A drying or degassing station 52 may then be provided at which the flux is dried and any gasses contained within the heat exchanger, tubes, and any other internal interstices are allowed to or encouraged to escape. In certain applications, this drying may occur at atmospheric pressures and temperatures.
Once the heat exchanger is assembled, held in the brazing frame, and coated with a joining and sealing material (referred to generally herein as a flux), the entire assembly may enter a brazing zone, as indicated by reference numeral 54 in
The forming station 56 performs hot forming of the heat exchanger slab to arrive at a desired formed shape, typically the final shape of the heat exchanger itself. Progressive forming may be performed at this forming station, and the temperature to which the heat exchanger is raised in the brazing zone serves to facilitate hot forming of the structure. While additional heat may be added in the forming station 56, in a presently contemplated embodiment, the temperature at which the heat exchanger exits the brazing zone is sufficient to facilitate this hot forming.
Following forming of the heat exchanger, a coating or paint is applied at a coating station as indicated by reference numeral 58 in
Following coating station 58, the formed and coated heat exchanger then passes through a controlled cool-down zone as indicated at reference numeral 60 in
The slab 62, exits at an elevated temperature and is then transferred to a transfer conveyor 68 to the hot forming station 56. At the hot forming station 56, and with the heat exchanger slab still hot from the oven 66, the slab is formed by mechanical means as generally illustrated in
The arrangement of
Continuing with the illustrated example,
As illustrated in
Following forming the heat exchanger at step 96, then, a paint or coating is applied at step 98. This coating may be applied by any suitable mechanism, and will typically be applied in conformance with specifications for the coating provided by the coating supplier. At step 100, then, the formed and coated heat exchanger is cooled at a controlled rate to allow for curing of the coating. Following such curing, the formed and coated heat exchanger may be cooled to any temperatures and transferred to stock or directly to downstream assembly processes, as indicated generally by reference numeral 102. Such processes will typically include mounting the heat exchanger in an air conditioning system, a heat pump system, a chiller, or any other application. The ultimate application in which the heat exchanger is used is not limited to air conditioners, heat pumps, chillers or even to the heating, ventilating, air conditioning and refrigeration context.
The methods described herein may find application in making any type of heat exchanger. However, the methods are particularly well-suited for making multichannel designs. The methods may be used with any form of heat exchanger, including those in which manifolds or headers are unbent, or designs in which these components are bent. Furthermore, the methods may be adapted for single, or multiple bends in a heat exchanger depending upon the physical configuration of the system. The methods are intended to streamline manufacturing and provide much greater efficiency in the use of thermal energy for the assembly process, hot forming, coating, and curing of coatings.
It should be noted that the present discussion makes use of the term “multichannel” tubes or “multichannel heat exchanger” to refer to arrangements in which heat transfer tubes include a plurality of flow paths between manifolds that distribute flow to and collect flow from the tubes. A number of other terms may be used in the art for similar arrangements. Such alternative terms might include “microchannel” and “microport.” The term “microchannel” sometimes carries the connotation of tubes having fluid passages on the order of a micrometer and less. However, in the present context such terms are not intended to have any particular higher or lower dimensional threshold. Rather, the term “multichannel” used to describe and claim embodiments herein is intended to cover all such sizes. Other terms sometimes used in the art include “parallel flow” and “brazed aluminum”. However, all such arrangements and structures are intended to be included within the scope of the term “multichannel.” In general, such “multichannel” tubes will include flow paths disposed along the width or in a plane of a generally flat, planar tube, although, again, the invention is not intended to be limited to any particular geometry unless otherwise specified in the appended claims.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions must be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
Claims
1. A method for making a heat exchanger comprising:
- conveying through an oven, an assembled heat exchanger including a plurality of multichannel tubes extending between a pair of manifolds, to permanently join the multichannel tubes to the manifolds; and
- hot forming the multichannel tubes and/or the manifolds in a forming station downstream of the oven at least partially utilizing heat energy transmitted to the heat exchanger in the oven.
2. The method of claim 1, comprising applying a brazing material to the assembled heat exchanger prior to entry into the oven, the brazing material at least partially melting in the oven to join the multichannel tubes to the manifolds.
3. The method of claim 1, comprising applying a coating to the heat exchanger after hot forming.
4. The method of claim 3, comprising controlling the temperature of the heat exchanger and the coating to cure the coating and to cool the heat exchanger.
5. The method of claim 1, comprising transferring the heat exchanger from an oven conveyor to a forming station via a forming station conveyor.
6. The method of claim 1, wherein the heat exchanger is hot formed by a mechanical forming tool that bends the multichannel tubes and/or the manifolds around one or more forms.
7. The method of claim 1, wherein the assembled heat exchanger is generally planar and is conveyed in a generally horizontal position through the oven.
8. The method of claim 7, wherein the heat exchanger is hot formed from the generally horizontal position in which it is conveyed through the oven.
9. The method of claim 1, wherein hot forming includes forming at least one bend in the multichannel tubes and/or the manifolds.
10. The method of claim 9, wherein hot forming includes forming two bends in the multichannel tubes and/or the manifolds.
11. A method for making a heat exchanger comprising:
- conveying through an oven, an assembled heat exchanger including a plurality of multichannel tubes extending between a pair of manifolds, to permanently join the multichannel tubes to the manifolds;
- hot forming the multichannel tubes and/or the manifolds in a forming station downstream of the oven at least partially utilizing heat energy transmitted to the heat exchanger in the oven;
- applying a coating to the heat exchanger after hot forming; and
- controlling the temperature of the heat exchanger and the coating to cure the coating and to cool the heat exchanger.
12. The method of claim 11, comprising applying a brazing material to the assembled heat exchanger prior to entry into the oven, the brazing material at least partially melting in the oven to join the multichannel tubes to the manifolds.
13. The method of claim 11, comprising transferring the heat exchanger from an oven conveyor to a forming station via a forming station conveyor.
14. The method of claim 11, wherein the heat exchanger is hot formed by a mechanical forming tool that bends the multichannel tubes and/or the manifolds around one or more forms.
15. The method of claim 11, wherein the assembled heat exchanger is generally planar and is conveyed in a generally horizontal position through the oven.
16. The method of claim 15, wherein the heat exchanger is hot formed from the generally horizontal position in which it is conveyed through the oven.
17. The method of claim 11, wherein hot forming includes forming at least one bend in the multichannel tubes and/or the manifolds.
18. A method for making a heat exchanger comprising:
- conveying through an oven, an assembled heat exchanger including a plurality of multichannel tubes extending between a pair of manifolds, to permanently join the multichannel tubes to the manifolds;
- applying a coating to the heat exchanger utilizing heat energy transmitted to the heat exchanger in the oven; and
- controlling the temperature of the heat exchanger and the coating to cure the coating and to cool the heat exchanger.
19. The method of claim 18, wherein the heat exchanger is hot formed following exit from the oven and prior to applying the coating.
20. A system for making a heat exchanger comprising:
- a heat exchanger assembling station at which a plurality of multichannel tubes are assembled between a pair of manifolds;
- an oven through which the assembled heat exchanger is conveyed to permanently join the multichannel tubes to the manifolds; and
- a hot forming station downstream of the oven at which the heat exchanger is formed at least partially utilizing heat energy transmitted to the heat exchanger in the oven.
21. The system of claim 20, comprising a coating station downstream of the hot forming station, the coating station applying a coating to the formed heat exchanger while the heat exchanger is hot.
22. The system of claim 21, comprising a controlled cool down zone downstream of the coating station for controlling cool down of the heat exchanger and curing of the coating.
Type: Application
Filed: Feb 29, 2008
Publication Date: Jun 19, 2008
Applicant: Johnson Controls Technology Company (Holland, MI)
Inventors: Peter J. Breiding (Wichita, KS), Charles B. Obosu (Wichita, KS), Jeffrey N. Nichols (Wichita, KS), Dan R. Burdette (Wichita, KS)
Application Number: 12/040,743
International Classification: B23P 15/26 (20060101); B21D 53/02 (20060101);