JP2007509311A - Method and tool for producing an improved heat transfer surface - Google Patents

Abstract

  The present invention relates to an improved heat transfer surface, and a method and tool for producing the improved heat transfer surface. Some embodiments include a boiling surface that includes a plurality of main grooves, protrusions, and secondary grooves to form a boiling cavity. The boiling surface can be formed using a tool for cutting the inner surface of the tube. The tool has a tool axis and at least one tip having a cut end and a lift end. A method for manufacturing a boiling surface is also disclosed, the method comprising cutting the inner surface of the tube to form a main groove, and then forming the protrusions and minor grooves by cutting and lifting the inner surface. .

Description

  REFERENCE INFORMATION FOR RELATED APPLICATIONS: This application claims the priority of US Patent Application No. 60 / 514,418, filed Oct. 23, 2003.

  The present invention relates generally to improved heat transfer surfaces and methods and tools for making improved heat transfer surfaces.

  The present invention relates to an improved heat transfer surface that facilitates heat transfer from one side of the surface to the other. Heat transfer surfaces are typically submerged evaporators, falling film coolers, spray evaporators, absorption coolers, condensers, direct expansion cooling used in low temperature industries, chemical industries, petrochemical industries, food processing industries, etc. Used in devices such as heaters, single-phase coolers, and heaters. These applications include a variety of pure water, water and glycol mixtures, any type of refrigerant (eg, R-22, R-134a, R-123), ammonia, petrochemical fluids, and other mixtures. Any heat transfer medium may be used, but is not limited to these.

  Some types of heat transfer surfaces work by absorbing heat using liquid phase changes. Therefore, heat transfer surfaces often incorporate a surface to enhance boiling or evaporation. Surface heat transfer performance is improved by increasing the number of cores on the boiling surface, causing agitation in the vicinity of the single-phase heat transfer surface, or increasing the area of the condensation surface to increase the surface tension effect on the condensation surface. it can. One method for increasing boiling or evaporation is to form a porous layer on the heat transfer surface by subjecting the heat transfer surface to a roughening process by a sintering method, a radiation melting method, or an edging method. It is known that a heat transfer surface having such a porous layer exhibits better heat transfer performance than a smooth heat transfer surface. However, the cavities or cells formed by the above method are small, and impurities contained in the boiling liquid can clog the cavities or cells, thereby impairing the heat transfer performance of the surface heat transfer surface. In addition, because the cavities or cells are not uniformly sized or dimensioned, the heat transfer performance can vary across the surface. Furthermore, known heat transfer tubes incorporating boiling or evaporating surfaces often require multiple passes or multiple passes to create the final surface.

  Pipe manufacturers have invested a great deal of money in U.S. Pat.No. 4,561,497 to Nakajima et al. U.S. Pat.No. 4,602,681 to Daikoku et al. U.S. Pat. Experiments have been conducted using alternative designs, including those disclosed in US Pat. No. 4,678,029, Lin, US Pat. No. 4,794,984, and Angeli, US Pat. No. 5,351,397.

  All of these surface designs are designed to improve the heat transfer performance of the surface, but the industry still continues to modify existing designs and improve the heat transfer performance. There is a need to continue to improve the design of tubes by creating designs. In addition, there is also a need to create designs and patterns that can be transferred to the surface of a tube more quickly and cost effectively. As will be described later, the geometry of the heat transfer surface of the present invention has a greatly improved heat transfer performance as well as the tool for forming the shape.

  Embodiments of the present invention provide an improved heat transfer surface that can be formed into a tube and a submerged evaporator used in at least the applications described above (ie, low temperature industry, chemical industry, petrochemical industry, food processing industry). , Improving heat transfer performance of tubes used in all applications such as falling film coolers, spray evaporators, absorption coolers, condensers, direct expansion coolers, single phase coolers, and heaters) There is provided a method of forming a heat transfer surface that can be used to achieve this. The surface is improved by a plurality of cavities that greatly shorten the transition time from one phase to the next, for example from boiling to evaporation. The cavity creates an additional path for fluid to flow in the tube, thereby enhancing the turbulence of the heat transfer medium flowing in the tube. The protrusions that create cavities also provide extra (additional) surface area for further heat exchange. Experiments have shown that the performance of tubes according to embodiments of the present invention is greatly improved.

  Some embodiments of the present invention include a method of using a tool having a mirror image of a pattern that can be easily added to existing manufacturing equipment and desired to be formed on the surface of a tube. Some embodiments of the present invention can also be easily added to existing manufacturing equipment, with the cut end (cut end) for incising (cutting the surface) the pipe surface and lifting the pipe surface ( And a method of using a tool having a lift end for lifting) to form protrusions. In this way, protrusions are formed without removing metal from the inner surface of the tube, thereby eliminating debris that can damage the device in which the tube is used. Finally, some embodiments of the present invention can be easily added to existing manufacturing equipment as well, using a tool such as a mandrel to flatten or bend the tip of the protrusion. including. The grooves, protrusions and flattened tips on the tube surface can be formed in the same or different operations. In some embodiments of the present invention, three tools are secured to a single axis and the tube surface is formed in one operation.

  Heat transfer surfaces formed in accordance with embodiments of the present invention can be used on the inner or outer surface of the heat transfer tube, or can be used on flat heat transfer surfaces such as those used to cool microelectronics. Such a surface may be suitable for any number of applications, such as for use in HVAC (heating, ventilating, air conditioning), low temperature industry, chemical industry, petrochemical industry, food processing industry. Including. The physical shape of the protrusions can be altered to suit a particular application and liquid medium (fluid medium).

  Tubes according to the present invention generally require that heat be transferred from one side of the tube to the other, such as multiphase (high purity liquid or gas, or liquid / gas mixture) evaporators and condensers. It should be understood that this is useful for any application, but is not so limited. The following description provides the desired dimensions of the tubes of the present invention, but the tubes of the present invention are in no way limited to those dimensions. Rather, the desired dimensions of the tube will depend on many factors, of which the most important is the nature of the fluid flowing through the tube. Those skilled in the art will understand how to change the geometry of the tube surface to maximize the heat transfer used with a variety of fluids in a variety of applications. Furthermore, although the drawing shows the surface as if it were seen on the inner surface of the tube, the surface is also suitable for use on the outer surface of the tube or on flat surfaces such as those used in microelectronics. It should be understood that there is.

  As shown in FIG. 1, some embodiments of the present invention include a heat transfer surface with a main groove 108 in the inner surface 104 of the tube 100. As will be appreciated by those skilled in the art, the number of main grooves 108 can vary depending on the application in which the heat transfer surface is used and the liquid medium used. The main groove 108 may be formed by any method including, but not limited to, cutting (cutting), deformation, broaching, or extrusion. The main groove 108 is formed in the inner surface 104 at a helical angle α with respect to the axis s (not shown) of the tube 100. The helix angle α can be any angle between 0 ° and 90 °, but preferably does not exceed 70 °. One skilled in the art will readily understand that this preferred helix angle α is often determined, at least in part, by the liquid medium used.

  In general, the higher the viscosity of the liquid flowing through the tube 100, the deeper the main groove 108 should be. For example, a depth that is greater than zero and less than the thickness of the tube wall 102 will generally be desirable. In the present application, the thickness of the tube wall 102 is measured from the inner surface 104 to the outer surface 106.

  The axial pitch of the main grooves 108 depends on many factors, including the helix angle α, the number of main grooves 108 formed in the inner surface 104 of the tube 100, and the inner diameter of the tube 100. For purposes of this application, the inner diameter is measured from the inner surface 104 of the tube 100. An axial pitch of 0.5 to 5.0 mm is generally preferred (1.5 mm).

Some embodiments of the present invention also include a protrusion or fin 110. The protrusion 110 may cut the inner surface 104 and be lifted from the inner surface 104, as shown in FIGS. The protrusion 110 preferably forms an angle θ with respect to the axis s of the tube 100. The height _{e p} of protrusions 110, inner surface 104 is determined by the cut depth t and angle θ to be cut. The height e _p of protrusions 110 is preferably cut depth t or more values, preferably a value of up to three times the cutting depth t. The depth of the cutting / lifting tool 300 is preferably larger than the depth of the main groove 108.

The axial pitch Pa _{, p} of the protrusions 110 can be any value greater than zero, and the axial pitch Pa _{, p} is generally, among other factors, the cut / lift tool 300 and tube 100 being manufactured. Relative rotation speed per minute between the cutting / lifting tool 300 being manufactured and the relative axial feed between the tube 100 and the tube 100 and the cut used to form the protrusion 110 during manufacturing. / Will depend on the number of tips 302 provided on the lift tool 300. The axial pitch Pa _{, p} of the protrusions 110 is preferably 0.05 to 0.5 mm. Axial pitch P _{a, p} and height e _p is generally determined by the number of projections, the height e _p as the number of protrusions increases will decrease.

  The shape of the protrusion 110 is determined by the shape of the inner surface 104 and the orientation of the inner surface 104 after the main groove 108 is cut with respect to the moving direction of the cutting / lifting tool 300. In the embodiment shown in FIGS. 2A and 2B, the protrusion 100 has four side surfaces 120, a sloped top surface 122 (helps reduce heat transfer resistance), and a substantially pointed tip 124.

  As shown in FIGS. 3A-3D, the tip 124 of the protrusion 110 can be optionally flattened to create a boiling cavity 114. Alternatively, as shown in FIGS. 4A and 4B, the tip 124 of the protrusion 110 can be bent to create a boiling cavity 114. In other embodiments, the tip 124 of the protrusion 110 can be thickened to create a boiling cavity 114. In yet other embodiments, as shown in FIGS. 5A and 5B, the protrusions 110 may be angled with respect to each other to create a boiling cavity 114. The tip 124 of the protrusion 110 can remain substantially straight (not bent or flattened) and can be perpendicular to the inner surface 104 of the tube 100 if a condensing surface is desired. However, if a boiling or evaporating surface is desired, the efficiency of the boiling surface can be substantially improved by creating a boiling cavity 114. Creating a boiling reservoir 114 creates a flow path through which the fluid flows, enhancing the transition from liquid to boiling or from boiling to evaporation.

  However, the projections 110 of the present invention are not limited to the illustrated embodiment, but rather can be formed in any shape. Further, the protrusions 110 in the tube 100 need not have the same shape or the same geometric shape.

  As shown in FIG. 2A, the minor groove 112 may be positioned between adjacent protrusions 110. The secondary groove 112 is oriented at an angle τ (not shown) with respect to the axis s of the tube 100. The angle τ can be any angle between about 80 ° and 100 °. The angle τ is preferably about 90 °. The depth of the sub-groove 112 is between the depth of the main groove 108 and the height of the protrusion 110. The depth of the sub-groove 112 is preferably larger than the depth of the main groove 108.

  Some embodiments of the present invention also include a method and tool for creating a boiling surface on a tube. A grooving tool 200 as shown in FIG. 6 is particularly useful for forming the main groove 108. Since the grooving tool 200 has an outer diameter that is larger than the inner diameter of the tube 100, the main groove 108 is formed when pulled or pushed through the tube 100. The grooving tool 200 also includes an aperture 202 for attaching a shaft 130 (shown in FIG. 10).

  The cut / lift tool 300 shown in FIGS. 7A-7D and FIGS. 8A-8D can be used to form protrusions 110 and minor grooves 112. The cut / lift tool 300 can be manufactured from any material having structural integrity that is resistant to metal cutting (metal cutting), but is preferably manufactured from carbide. The embodiment of the cut / lift tool 300 shown in FIGS. 7A-7D and FIGS. 8A-8D generally has a tool axis q, two bottom surfaces 312, and one or more side walls 314. An aperture 308 is positioned through the cut / lift tool 300. A tip 302 is formed on the side wall 314 of the cut / lift tool 300. However, the tip 302 can be mounted or formed on any structure capable of supporting the tip 302 in a desired orientation with respect to the tube 100, and such a structure is shown in FIGS. Note that it is not limited to those disclosed in 8A-8D. Furthermore, the tips 302 can be retracted (retracted) into their support structure so that the number of tips 302 used in the cutting process can be easily changed.

7A-7D illustrate one embodiment of a cut / lift tool 300 having a single tip 302. FIGS. 8A-8D show an alternative embodiment of a cut / lift tool 300 having four tips 302. One skilled in the art will appreciate that any number of tips 302 may be provided in the cut / lift tool 300 depending on the desired pitch Pa _{, p} of the protrusions 110. Further, the geometry of each of the tips 302 need not be the same as the tip 302 of a cut / lift tool 300 having a single tip 302. Rather, the cut / lift tool 300 may be provided with a tip 302 having a different geometric shape to form protrusions 110 having different shapes, orientations, and other geometric shapes.

Each tip 302 is formed by the intersection of planes A, B and C. Plane A, B
And a cut end 304 is formed by the intersection of C. The cut end 304 cuts the inner surface 104 to form a layer as a first step for forming the protrusion 110. The plane B is oriented at an angle φ with respect to a plane perpendicular to the tool axis q (see FIG. 7B). The angle φ is defined as θ−90 °. Therefore, the angle φ is preferably between about 40 ° and about 70 ° so that the cut end 304 can slice the inner surface 104 at a desired angle θ between about 20 ° and about 50 °.

The intersection of the planes A, B, and C forms a lift end 306 that lifts the inner surface 104 upward to form a protrusion 110. Angle phi ₁ is defined by a plane perpendicular to the plane C and the tool axis q. The angle φ ₁ determines the tilt angle ω (the angle between the plane perpendicular to the longitudinal axis s of the tube and the plane of the longitudinal axis of the protrusion 110), and the protrusion 110 is lifted at this angle φ ₁ by the lift end 306. The The angle φ ₁ = the angle ω, and therefore, by adjusting the angle φ ₁ in the cutting / lifting tool 300, the inclination angle ω of the protrusion 110 can be directly influenced. This tilt angle ω (and angle φ _{1 as} well) is preferably an absolute value of any angle between about −45 ° and about 45 ° with respect to a plane perpendicular to the longitudinal axis s of the tube. In this way, the protrusions 110 can be aligned with a plane perpendicular to the longitudinal axis s of the tube, or can be tilted to the left and right with respect to the plane perpendicular to the longitudinal axis s of the tube 100. Further, the tip 302 can be formed to have different geometric shapes (ie, the angle φ ₁ can be different for each tip 302), so that the protrusions 110 in the tube 100 can be inclined at different angles. (Or may not be inclined at all) and may be inclined in different directions with respect to a plane perpendicular to the longitudinal axis s of the tube 100.

For example, as shown in FIG. 11, the cut / lift tool 300 may incorporate the cut ends at two different angles. In a cut / lift tool 300 having four cut ends, two pairs of cut ends 318, 320 may be used to create a boiling surface with inclined protrusions 110, as shown in FIGS. . To create such a surface, adjacent ends 318, 320 have different angles phi _1. Changing the angle of inclination of the protrusions 110 is possible to obtain a specific gap (gap) g between the protrusions 110 at the opening 116 of the boiling cavity 114, thereby causing a curved fluid flow along the inner surface 104. Is affected.

式中、ｐは突起１１０の軸方向ピッチであり、
φは平面Ｂと工具軸ｑに垂直な平面との間の角度であり、
φ_１は工具３００の、平面Ｃと工具軸ｑに垂直な平面との間の角度であり、
ｔはカット深さである。 Hence, the resulting gap g can be calculated as follows:

Where p is the axial pitch of the protrusions 110;
φ is the angle between plane B and the plane perpendicular to tool axis q,
φ ₁ is the angle between the plane C of the tool 300 and the plane perpendicular to the tool axis q,
t is the cut depth.

又は、もしもφ＝90-θであれば、

式中、ｔはカット深さであり、
φは平面Ｂと工具軸ｑに垂直な平面との間の角度であり、
θは管１００の長手方向の軸ｓに対して層がカットされる角度である。 While a preferred range of physical dimension values for the protrusions 110 has been identified, it should be noted that the physical dimensions of the cut / lift tool 300 can be varied to affect the physical dimensions of the resulting protrusions 110. The merchant will understand. For example, the depth t and angle of cutting edge 304 cuts into inner surface 104 phi affects the height _{e p} of protrusions 110. Therefore, the height e _p of protrusions 110 may be adjusted using the following formula.

Or if φ = 90-θ,

Where t is the cut depth,
φ is the angle between plane B and the plane perpendicular to tool axis q,
θ is the angle at which the layer is cut with respect to the longitudinal axis s of the tube 100.

又は、もしもφ＝90-θであれば、

式中、Ｐ_ａ，ｐは突起１１０の軸方向ピッチであり、
φは平面Ｂと工具軸ｑに垂直な平面との間の角度であり、
θは管１００の長手方向の軸ｓに対して内面１０４がカットされる角度である。 The thickness _{S p} of protrusions 110, the pitch _{P a} of the protrusion 110 _is determined depending on _p and the angle phi. Thus, the thickness S _p can be adjusted using the following equation.

Or if φ = 90-θ,

Where P _{a, p} is the axial pitch of the protrusions 110;
φ is the angle between plane B and the plane perpendicular to tool axis q,
θ is an angle at which the inner surface 104 is cut with respect to the longitudinal axis s of the tube 100.

  In some embodiments of the present invention, the tip 124 of the protrusion 110 may be flattened or bent using the flat tool 400 shown in FIG. The flat tool 400 preferably has a diameter that is larger than the diameter of the protrusion 110 on the inner surface 104. Therefore, as the flat tool 400 is pulled or pushed through the tube 100, the tip 124 of the protrusion 100 is bent or flattened. Flat tool 400 includes an aperture 402 for attachment to shaft 130.

  In other embodiments, the tip 124 of the protrusion 110 may obtain a shape similar to the flattened or bent tip 124 shown in FIGS. 3A and 3B without using the flat tool 400. For example, the cut / lift tool 300 may incorporate a tip capable of creating a protrusion 110 having a shape similar to the flattened protrusion tip 124, as shown in FIGS. 4A and 4B. In other embodiments, the cut / lift tool 300 may incorporate a tip 316 for flattening the tip 124 of the protrusion 110 as shown in FIG. 9B. The cut / lift tool 300 shown in FIG. 9A can be used to create a boiling surface as shown in FIGS. 9B and 9C.

式中、φ_２はカット端の１番目の位置の突起と工具送り方向との間の角度であり、
φ_３はカット端の２番目の位置の突起と工具送り方向との間の角度であり、
ｔはカットの総深さであり、
ｔ_１はカット端の最初の位置のためのカット深さであり、次いで突起先端１２４は図１３Ｂに示されたようになり、そして隙間ｇが下記のように計算され得る。

もしも以下が真であるならば、

その結果、突起１２４は図１３に示されたものになるであろうし、隙間ｇは下記のように計算され得る。

The boiling surface used in the heat transfer surface may be obtained by creating a protrusion 110 having a thickened tip 124. As shown in FIGS. 12A and 12B, a heat transfer surface having a thickened tip 124 can be used to create a boiling cavity 114. The protrusion 110 having a thickened tip 124 can be obtained by using the following formula with reference to FIGS. 13A and 13B.

Where φ ₂ is the angle between the protrusion at the first position of the cut end and the tool feed direction,
φ ₃ is the angle between the protrusion at the second position of the cut end and the tool feed direction,
t is the total depth of the cut,
t ₁ is the cut depth for the initial position of the cut end, then the protrusion tip 124 is as shown in FIG. 13B, and the gap g can be calculated as follows:

If the following is true:

As a result, the protrusion 124 will be as shown in FIG. 13, and the gap g can be calculated as follows.

  13C and 13D show an embodiment of a cut / lift tool 300 for creating a protrusion 110 having a thickened tip 124.

  FIG. 10 is one possible manufacturing configuration for improving (strengthening) the surface of the tube 100. These forms in no way limit the process by which the tube 100 according to the present invention is manufactured. Rather, any tube manufacturing process using any suitable equipment or configuration may be used. The tube 100 of the present invention has various materials having suitable physical properties including structural integrity, malleability, and plasticity, such as copper, copper alloys, aluminum, aluminum alloys, brass, titanium, steel, and stainless steel. Can be built from.

  In one example of a method for improving the inner surface 104 of the tube 100, the shaft 130 on which the flat tool 400 is rotatably mounted through the aperture 402 extends into the tube 100. The cut / lift tool 300 is attached to the shaft 130 through the aperture 308. The grooving tool 200 is attached to the shaft 130 through the aperture 202. Bolts 132 fix all three tools 200, 300, 400 in place. Tools 200, 300, 400 are preferably rotatably fixed to shaft 130 by any suitable means. FIGS. 7D and 8D show a keyway 310 that is provided on the cut / lift tool 300 and engages a protrusion (not shown) on the shaft, thereby securing the cut / lift tool 300 in place relative to the shaft 130. Show.

Although not shown, when the method or / and tool of the present invention is used to create the inner surface of a tube, the manufacturing configuration includes an arbor that can be used to improve the outer surface of the tube. obtain. Arbor generally includes a tool arrangement having finned disks that cause outer fins, each having an axial pitch Pa _{, o} , to project radially from one to many starting positions. This tool configuration may include additional disks, such as notching or flattening disks, to further improve the outer surface of the tube. However, it should also be noted that, depending on the tube application, there is no need to make any modifications to the outer surface of the tube. During operation, the tube wall moves between the mandrel and the arbor, thereby applying pressure to the tube wall.

  A mirror image of the desired inner surface pattern is provided on the grooving tool 200 so that when the tube 100 engages the grooving tool 200, the grooving tool 200 forms a desired pattern on the inner surface 104 of the tube 100. Yes. The desired inner surface 104 includes a main groove 108 as shown in FIG. After forming the main groove 108 in the inner surface 104 of the tube 100, the tube 100 faces a cut / lift tool 300 positioned adjacent to and downstream of the grooving tool 200. A cut end (a plurality of cut ends) 304 of the cutting / lifting tool 300 cuts the inner surface 104. Next, the lift end (plural lift ends) 306 of the cut / lift tool 300 lifts the inner surface 104 to form the protrusion 110.

式中、Ｐ_ａ，ｏは外側フィンの軸方向ピッチであり、
Ｚ_ｏは管の外径上のフィン起点の数であり、
Ｚ_ｉはカット／リフト工具３００の先端３０２の数である。 When the protrusion 110 is formed at the same time as the outer fining and the cutting / lifting tool 300 is fixed (ie when the tool 300 is not rotating or moving axially), the tube 100 automatically rotates. And has axial movement. In this case, the axial pitches Pa _{, p} of the protrusions 100 are determined by the following formula.

_Where P _{a, o} is the axial pitch of the outer fins,
Z _o is the number of fin origins on the outer diameter of the tube,
Z _i is the number of tips 302 of the cut / lift tool 300.

式中、ＲＰＭ_ｔｕｂｅは管１００の回転数であり、
Ｐ_ａ，ｏは外側フィンの軸方向ピッチであり、
Ｚ_ｏは管の外径上のフィン起点の数であり、
Ｐ_ａ，ｐは突起１１０の所望の軸方向ピッチであり、
Ｚ_ｉはカット／リフト工具３００の先端３０２の数である。 The cut / lift tool 300 can also be rotated to obtain the axial pitch Pa _{, p} of _a particular protrusion. Both the tube 100 and the cut / lift tool 300 can be rotated in the same direction, or both the tube 100 and the cut / lift tool 300 can be rotated in opposite directions. The rotation of the cutting / lifting tool 300 (at the number of revolutions per minute (RPM)) required to obtain the predetermined axial pitches Pa _{, p} can be calculated using the following equation.

_Where RPM _tube is the number of revolutions of tube 100;
P _{a, o} is the axial pitch of the outer fins,
Z _o is the number of fin origins on the outer diameter of the tube,
Pa _{and p} are the desired axial pitches of the protrusions 110;
Z _i is the number of tips 302 of the cut / lift tool 300.

If the calculation result is a negative value, the cut / lifting tool 300 should rotate in the same direction as the tube 100 in order to obtain the desired pitch P _a, to _p. Alternatively, if the calculation result is a positive value, the cut / lift tool 300 should rotate in the opposite direction to the tube 100 to obtain the desired pitch Pa _{, p} .

  Although the formation of the protrusion 110 is shown in the same operation as the formation of the main groove 108, it is noted that the protrusion 110 may be formed in a different operation using the tube 100 in which the main groove 108 has been previously formed. I want. This will generally require assembly to rotate the cut / lift tool 300 or tube 100 and move the cut / lift tool 300 or tube 100 along the axis of the tube. In addition, a support (not shown) is preferably provided to center the cut / lift tool 300 against the inner surface 104 of the tube.

式中、Ｘ_ａは管１００とカット／リフト工具３００との間の相対軸方向速度（距離／時間）であり、
ＲＰＭはカット／リフト工具３００と管１００との間の相対回転数であり、
Ｐ_ａ，ｐは突起１１０の所望の軸方向ピッチであり、
Ｚ_ｉはカット／リフト工具３００の先端３０２の数である。 In this case, the axial pitches Pa _{, p} of the protrusions 110 are determined by the following formula.

Where X _a is the relative axial velocity (distance / time) between the tube 100 and the cut / lift tool 300;
RPM is the relative rotational speed between the cut / lift tool 300 and the tube 100;
Pa _{and p} are the desired axial pitches of the protrusions 110;
Z _i is the number of tips 302 of the cut / lift tool 300.

  This formula is suitable in the following cases. That is, when (1) the tube 100 only moves axially (ie does not rotate) and the cut / lift tool 300 only rotates (ie does not move axially), (2) the tube 100 (3) The cut / lift tool 300 rotates and moves axially, but the tube 100 rotates both axially and axially when the cut / lift tool 300 only moves axially. (4) the tube 100 rotates and moves axially, but the tool 300 is fixed both rotationally and axially, and (5) any of the above combinations.

式中、Ｐ_ａ，ｒは主溝１０８の軸方向ピッチであり、
αは主溝１０８の、管の軸ｓに対する角度であり、
α_１は突起１１０間の所望のらせん角度であり、
Ｚ_ｉはカット／リフト工具３００の先端３０２の数であり、
Ｄ_ｉは管１００の内面１０４から測定された管１００の内径である。 The tube inner surface 104 of the present invention creates additional flow paths for fluid flow (through the secondary groove 112 and between the protrusions 110) to optimize heat transfer and pressure drop. FIG. 5C shows these additional flow paths for fluid traveling through the tube 100. These channels are in addition to the channels created between the main grooves 108 and have a helix angle α ₁ with respect to the tube axis s. The angle α ₁ is an angle between the protrusions 110 formed from the adjacent main grooves 108. The helix angle α ₁ , and hence the orientation of the flow path 128 through the tube 100, can also be adjusted by adjusting the pitches Pa _{, p} of the protrusions 110 using the following equations.

Where P _{a, r} is the axial pitch of the main groove 108;
α is the angle of the main groove 108 with respect to the axis s of the tube,
α ₁ is the desired helix angle between the protrusions 110;
Z _i is the number of tips 302 of the cut / lift tool 300;
_Di is the inner diameter of the tube 100 measured from the inner surface 104 of the tube 100.

Tube 100 made in accordance with the present invention has superior performance over existing tubes. 14-16 illustrate graphically the improved performance of the heat transfer surface according to an embodiment of the present invention. FIG. 14 is a graph showing the effect of aspect ratio on heat flux. FIG. 15 is a graph showing the effect of protrusions (fins) per inch (2.54 cm) on heat flux. FIG. 16 is a graph comparing the heat fluxes of different types of copper heat transfer surfaces with fine fins (micro fins) attached. The X axis indicates the heat flux (W / cm ² ), and the Y axis indicates the change in “heat minus wall heat minus bulk temperature” (ΔT (° C.) − T _wall −T _bulk ).

  The smooth line shows a wire test using HFE-7100. Filled circles indicate tubes made of copper roughened with silver solder. The open square shows the nichrome surface of the tube. A bright X shows a sample of tubing made in accordance with an embodiment of the present invention. Cloth shows a sample of tubing made in accordance with an alternative embodiment of the present invention. The dark X represents a sample of tubing made in accordance with an alternative embodiment of the present invention. The asterisk indicates a sample of a tube made according to an alternative embodiment of the present invention. The dark and closed circle shows a sample of tubing made in accordance with an alternative embodiment of the present invention. The closed diamond represents a sample of tubing made in accordance with an alternative embodiment of the present invention. A solid line with a semi-slash mark indicates a sample of a tube made in accordance with yet another embodiment of the present invention. The solid line with the slash marks indicates a sample of a tube made in accordance with a further alternative embodiment of the present invention.

  The heat transfer surface tested was a flat copper surface with about 185 protrusions per inch (2.54 cm). The protrusions were about 0.024 inches (0.6096 mm) in height and about 0.0027 inches (0.0688 mm) thick. The heat transfer surface of the present invention is about 8 times more effective than a roughened copper plate and about twice as effective as a copper foam.

  The above description is intended to illustrate various embodiments and structures related to the present invention. Various changes, additions and deletions (omitted) may be made to these embodiments and / or structures without departing from the scope and spirit of the invention.

FIG. 1 is a perspective view of a boiling surface partially formed on the inner diameter of a heat transfer tube according to an embodiment of the present invention. FIG. 2A is a perspective view of a partially formed boiling surface of the embodiment of FIG. FIG. 2B is a photomicrograph of the partially formed boiling surface of FIG. 2A. 2C is a cross-sectional view of the partially formed boiling surface of FIG. 2A. FIG. 3A is a perspective view of a boiling surface of the inner diameter of a heat transfer tube according to an alternative embodiment of the present invention. FIG. 3B is a cross-sectional view of the tube shown in FIG. 3A. FIG. 3C is a photomicrograph of the top view of the boiling surface of FIG. 3A. FIG. 3D is a photomicrograph of the cross section of the boiling surface of FIG. 3A. FIG. 4A is a perspective view of a boiling surface of the inner diameter of a heat transfer tube, according to an alternative embodiment of the present invention. FIG. 4B is a cross-sectional view of the tube shown in FIG. 4A. FIG. 5A is a perspective view of a boiling surface of the inner diameter of a heat transfer tube according to an alternative embodiment of the present invention. FIG. 5B is a photomicrograph of the cross section of the boiling surface of FIG. 5A. FIG. 5C is a cross-sectional view of the boiling surface of FIG. 5A. FIG. 6 is a perspective view of a tool according to an embodiment of the present invention. FIG. 7A is a perspective view of a tool according to an alternative embodiment of the present invention. FIG. 7B is a side view of the tool shown in FIG. 7A. FIG. 7C is a bottom view of the tool shown in FIG. 7A. FIG. 7D is a top view of the tool shown in FIG. 7A. FIG. 8A is a perspective view of a tool according to another embodiment of the present invention. FIG. 8B is a side view of the tool shown in FIG. 8A. FIG. 8C is a bottom view of the tool shown in FIG. 8A. FIG. 8D is a top view of the tool shown in FIG. 8A. FIG. 9A is a perspective view of a tool according to another embodiment of the present invention. FIG. 9B is a perspective view of the boiling surface formed by the tool of FIG. 99A. FIG. 9C is a photomicrograph of the boiling surface of FIG. 9B. FIG. 10 is a perspective view of an embodiment of a production facility that can be used to produce a heat transfer tube according to the present invention. FIG. 11 is a perspective view of a tool according to another embodiment of the present invention. FIG. 12A is a cross-sectional view of a boiling surface of the inner diameter of a heat transfer tube according to an alternative embodiment of the present invention. FIG. 12B is a photomicrograph of the cross section of the boiling surface of FIG. 12A. FIG. 13A is a cross-sectional view of a boiling surface formed using a cut end, in accordance with an embodiment of the present invention. FIG. 13B is a cross-sectional view of a boiling surface formed with a cut / lift end, in accordance with an alternative embodiment of the present invention. 13C is a cross-sectional view of a cut / lift end according to an embodiment of the present invention that may be used to form the boiling surface of FIGS. 13A and 13B. 13D is a perspective view of a cut / lift end according to an embodiment of the present invention that may be used to form the boiling surface of FIGS. 13A and 13B. FIG. 14 is a graph showing the effect of aspect ratio on heat flux. FIG. 15 is a graph showing the effect of protrusions (fins) per inch (2.54 cm) on heat flux. FIG. 16 is a graph comparing the heat fluxes of different types of copper heat transfer surfaces with fine fins (micro fins) attached.

Claims (3)

A tube comprising an inner surface, an outer surface, and a longitudinal axis;
The inner surface has at least one protrusion;
The at least one protrusion has at least two main grooves having a main groove cut depth and at least one sub groove having a sub groove cut depth equal to or greater than the main groove cut depth of each of the at least two main grooves. Formed by grooves,
A tube in which the main groove, protrusion and sub-groove form a boiling cavity. A method of manufacturing a tube having a longitudinal axis comprising:
a. Cutting the inner surface of the tube at a cut depth and at an angle to the longitudinal axis to form a main groove;
b. Forming an inner surface layer on the inner surface by cutting a minor groove at a cut depth and at an angle with respect to the longitudinal axis;
c. Lifting the inner surface layer to form protrusions having protrusion heights, protrusion thicknesses and protrusion pitches. A method for improving the inner surface of a tube,
a. Mounting a tool on the shaft, the tool having a tool axis and at least one tip formed by the intersection of at least a first plane, a second plane and a third plane and having a cut end and a lift end; And
b. Placing the tool in the tube;
c. Providing relative rotation and relative axial movement between the tube and the tool to at least partially cut the inner surface of the tube to form layers and grooves and lift the layer to project Forming a method.

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