EP2788705B1

EP2788705B1 - Method of forming heat exchanger tubes

Info

Publication number: EP2788705B1
Application number: EP12799430.9A
Authority: EP
Inventors: Patrick Louis CLAVETTE; Satyam Bendapudi; Jefferi J. Covington
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2011-12-08
Filing date: 2012-11-28
Publication date: 2017-03-01
Anticipated expiration: 2032-11-28
Also published as: CN103998890A; US20140366573A1; EP2788705A1; CN103998890B; WO2013085771A1

Description

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to heat exchangers. More specifically, the present disclosure relates to forming enhanced tubes for microchannel heat exchangers.
Present microchannel heat exchanger systems are refrigerant to air applications. These systems include a plurality of microchannel tubes, typically formed of aluminum. The tubes each contain a number of channels or ports through which a flow of refrigerant is circulated. Thermal energy from the refrigerant flow is dissipated to an airflow, typically in a cross-flow orientation relative to the flow in the tubes. Such microchannel heat exchangers are typically applied to motor vehicle cooling systems.
Typical industrial air conditioning and refrigeration systems include a refrigerant evaporator or chiller. Chillers remove heat from a cooling medium that enters the unit, and deliver refreshed cooling medium to the air conditioning or refrigeration system to effect cooling of a structure, device or a given volume. Refrigerant evaporators or chillers use a liquid refrigerant or other working fluid to accomplish this task. Refrigerant evaporators or chillers lower the temperature of a cooling medium, such as water or other fluid, below that which could be obtained from ambient conditions.
One type of chiller is a flooded chiller, which typically includes a number of typically round heat exchange tubes submerged in a volume of a two-phase boiling refrigerant, having a specified boiling temperature. A cooling medium, often water, is processed by the chiller. The cooling medium enters the evaporator and is delivered to the heat exchange tubes. The cooling medium passing through the tubes releases its thermal energy to the boiling refrigerant.
DE 101 15 513 A1 shows a heat exchanger, especially an evaporator in an air-conditioning system of a motor vehicle, used for transferring heat between a first and a second heat medium comprises a number of flat tubes forming a block through which the first heat medium flows. The flat tubes are arranged in parallel so that channels for the second heat medium entering at one end of the block are formed in between adjacent flat tubes. The flat tubes extend in the direction of the block depth at least over a partial section at an angle to the end surface of the block.
US 3 092 470 A shows a method of preparing narrow strips of material each having an internal discontinuity between surface laminations, the laminations being connected at the lateral edges of the discontinuity, which comprises preparing a billet of material with a plurality of internal longitudinal channels spaced laterally from one another and from the longitudinal edges of the billet by portions of solid metal extending from face to face of the billet. The method prepares sheet stock having longitudinal external weakenings therein.
DE 10 2009 051280 shows a tube having impression-free sections alternately arranged in a tube longitudinal direction that is parallel to a tube longitudinal axis, and molded sections comprising impressions attached in a tube wall. One of the impression-free sections is arranged between the molded sections, and the other impression-free section is arranged at both tube ends. The molded sections have longitudinal extension of 25 to 100 mm in the tube longitudinal direction.
According to the invention, a method of forming a heat exchange tube for a refrigerant-flooded evaporator includes urging a billet into an extruded section and forming the billet into two tube halves including an outer wall and an inner wall having a plurality of channel halves. A textural element is formed at one or more of the outer wall and the inner wall via one or more rotating dies, and the two tube halves are joined to form the heat exchange tube.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic view of a method not covered by the present invention of forming a heat exchange tube;
FIG. 2 is a perspective view of an embodiment of a heat exchange tube;
FIG. 3 is a perspective view of a heat exchange tube half;
FIG. 4 is a schematic of textural elements of an inner wall of a tube half;
FIG. 5 is a schematic view of textural elements of an outer wall of a tube half; and
FIG. 6 is a schematic view of another embodiment of a method of forming a heat exchange tube.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Shown in FIG. 1 is a schematic of a method of forming microchannel tubes 10 for a refrigerant flooded evaporator. The method is utilized for forming the microchannel tubes 10 which, as shown in FIG.2, include a tube body 12 that may be non-circular in shape, for example, oval or elliptical. A plurality of channels 14, or ports, is configured for refrigerant flow therethrough. The tube body 12 may include any number of channels, for example between about 2 and 20 channels. In some embodiments, the tube body 12 is about 1 inch in width and includes about 10-16 channels 14 therein. In other embodiments, the tube body may include about 4-6 channels 14 therein. It is to be appreciated that these embodiments are merely exemplary and other configurations are contemplated within the present scope.
Referring again to FIG. 1, the method begins with a billet 16 of a selected raw material. In some embodiments, the material is copper or a copper alloy, but other materials, for example, aluminum and aluminum alloys are contemplated within the scope of the present disclosure. The billet is fed into a heating section 18 in pairs by a ram 20. The billet 16 pairs are heated to a selected temperature, and then urged through an extrusion section 22, where the billet pairs 16 are shaped into tube halves 24, shown also in FIG. 3. Each tube half 24 includes an outer wall 26 and an inner wall 28 that includes a plurality of channel halves 30.
Referring again to FIG. 1 and FIG. 3, the extruded tube halves 24 are then urged through a texture section 32. The texture section 32 includes one or more rotating dies 34 affixed to bearings (not shown) and driven by separate or shared drive motors (not shown). The rotating dies 34 emboss textural elements or patterns into the outer wall 26 and/or the channel halves 30 of the tube halves 24. The tube halves 24 then proceed to a unitization section 38 where they are secured to each other such as for example by brazing or solid state diffusion bonding. It is contemplated within the scope of the current invention that other suitable joining techniques may also be used.
Referring now to FIGs. 4-5, the textural elements or patterns added to the outer wall 26 and or the channel halves 30 may take many forms. As shown in FIG. 4, the inner wall 28 is embossed with a plurality of dimples 40, or a plurality of grooves 42 or fins 44 that are configured to increase heat transfer between a cooling medium 46 flowing through the channels 14 and the outer wall 26 by improving mixing of the cooling medium 46 in the channels 14. In some embodiments, the grooves 42 or fins 44 may be arranged in a helical and/or cross-hatched pattern. As shown in FIG. 5, the textural elements on the outer wall 26 are ridges 48, pockets 50, or other similar shape with sharp edges to improve nucleate boiling of a volume of refrigerant 52 in which the tubes 10 are submerged. Further, in some embodiments, the ridges 48 or other textures may be arranged helically of in a cross-hatched pattern on the outer wall 26.
According to the invention, as shown in FIG. 6, the tube halves 24 are urged over a rotating die 34 which forms patterns or textures in the channel halves 30 of the tube halves 24. The tube halves 24 then proceed to the unitization section 38 where they are joined. The joined tube 10 then proceeds through another texture section 32, including more rotating dies 34 that apply textural elements or patterns to the outer wall 26 of the tube 10.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is only limited by the scope of the appended claims.

Claims

A method of forming a heat exchange tube for a refrigerant-flooded evaporator comprising:
feeding a pair of billets (16) into a heating section (18) and heating the pair of billets (16) to a selected temperature;

urging the billet pairs (16) into and through an extrusion section (22), where the billet pairs (16) are formed into two tube halves (24), each tube half (24) including an outer wall (26) and an inner wall (28) having a plurality of channel halves (30);

forming a textural element at one or more of the outer wall (26) and the inner wall (28) via one or more rotating dies (34); and

joining the two tube halves (24) to form the heat exchange tube;

wherein a textural element is formed on the outer wall (26) of the heat exchange tube after joining of the two tube halves (24);

wherein the textural elements at the inner wall (28) are formed as a plurality of dimples (40), or a plurality of grooves (42) or fins (44) that are configured to increase heat transfer between a cooling medium (46) flowing through the channels (14) and the outer wall (26) by improving mixing of the cooling medium (46) in the channels (14); and

wherein the textural elements on the outer wall (26) are formed as ridges (48), pockets (50), or other similar shape with sharp edges to improve nucleate boiling of a volume of refrigerant (52) in which tubes (10) are submerged.
The method of Claim 1, further comprising joining the tube halves (24) in a unitization section (38) by solid state diffusion bonding, brazing, or other suitable joining technique.
The method of Claim 1 further comprising feeding the billet pairs (16) into the heating section (18) by a ram (20).
The method of Claim 1, wherein the billet pairs (16) comprise one of copper, copper alloy, aluminum or aluminum alloy.
The method of Claim 1, wherein the grooves (42) or fins (44) are arranged in a helical and/or cross-hatched pattern.
The method of Claim 1, wherein the ridges (48) or other textures are arranged helically or in a cross-hatched pattern on the outer wall (26).