Heat exchange tube, falling film evaporator and refrigerating unit

Abstract

The utility model discloses a heat exchange tube, a falling film evaporator and a refrigerating unit. The heat exchange tube comprises a base body; a plurality of fin structures are spirally arranged on the outer side wall of the base body in the circumferential direction, protrusions arranged in the circumferential direction are arranged at the ends, away from the base body, of the fin structures, and evaporation holes are formed between the adjacent protrusions in the circumferential direction; every two adjacent fin structures and the base body form an evaporation cavity structure, and the evaporation cavity structures are communicated with the evaporation holes. The liquid refrigerant enters the evaporation cavity structure through the evaporation holes and is in contact with the nucleation site in the evaporation cavity structure, so that the nucleation site better generates evaporation bubbles, the generation condition of the evaporation bubbles is improved, the external heat resistance of the heat exchange tube is reduced, and the heat exchange efficiency of the heat exchange tube is improved.

Description

Technical Field

[0001] This utility model relates to the field of refrigeration technology, and in particular to a heat exchange tube, a falling film evaporator, and a refrigeration unit. Background Technology

[0002] In compression refrigeration units, the evaporator is a crucial component of the refrigeration system, and its performance directly affects the overall system's energy efficiency and operational efficiency. Currently, commonly used evaporator types include dry-type evaporators, flooded evaporators, and falling film evaporators. With the continuous development of refrigeration technology and the national requirements for "energy conservation and emission reduction" and "carbon peaking and carbon neutrality," improving the heat exchange efficiency of evaporators has become a key research focus. The heat exchange performance of an evaporator largely depends on the heat exchange tubes it uses.

[0003] In evaporative heat transfer, the nucleation boiling mechanism is considered an important way to improve heat transfer efficiency. According to the nucleation boiling theory, when the liquid refrigerant is heated above the saturation temperature, bubbles form at the nucleation sites on the heat transfer surface and detach from the surface as they grow. In this process, the evaporation of the liquid refrigerant, the detachment of bubbles, and the convection effect of the liquid pool jointly increase the heat transfer rate.

[0004] However, in existing heat exchanger tube designs, especially falling film evaporator tube designs, manufacturers focus more on how to improve the "hydrophilicity" of the liquid refrigerant on the tube surface through surface design to expand the effective heat exchange area. However, existing research shows that liquid refrigerant exhibits a "hydrophilic" state on copper surfaces without modification. In this process, existing designs neglect the issue of how to improve the conditions for evaporation bubble formation after the liquid refrigerant is dripped onto the heat exchanger tube surface through a drip distributor. Utility Model Content

[0005] This invention provides a heat exchange tube, a falling film evaporator, and a refrigeration unit to solve the problems in the prior art where the evaporation bubble generation conditions of the heat exchange tube are poor, resulting in high external thermal resistance and low heat transfer efficiency.

[0006] The technical solution of this utility model is a heat exchange tube, comprising:

[0007] Matrix;

[0008] The fin structure has multiple fin structures spirally arranged along the circumferential direction on the outer side wall of the substrate. Each fin structure has circumferentially arranged protrusions at the end away from the substrate, and evaporation holes are formed between adjacent protrusions along the circumferential direction.

[0009] The adjacent fin structures and the substrate form an evaporation cavity structure, which communicates with the evaporation holes.

[0010] Furthermore, the fin structure located below the two adjacent protrusions is provided with a slotted structure running through it along the axial direction.

[0011] Furthermore, the protrusion is recessed inward to form a cavity, and the inner diameter of the cavity gradually decreases radially.

[0012] Furthermore, a groove structure is provided radially on the side of every two adjacent fin structures, and the groove structure communicates with the slotted structure.

[0013] Furthermore, the inner diameter of the groove structure at one end near the protrusion is larger than the inner diameter at the other end.

[0014] Furthermore, each of the fin structures is provided with a first aileron and a second aileron on both sides corresponding to the groove structure; the first aileron and the second aileron are curved relative to each other;

[0015] The substrate, the fin structure, and the corresponding first and second ailerons form a semi-enclosed cavitation structure.

[0016] Furthermore, a groove structure is provided on the base at the bottom of two adjacent fin structures, the groove structure extending toward the corresponding fin structures on both sides; and the groove structure communicates with the trench structure.

[0017] The groove structures are distributed at intervals along the circumference of the fin structure.

[0018] Furthermore, the inner wall of the substrate facing away from the fin structure is provided with a microrib structure along the circumferential spiral, and the microrib structure is distributed in a multi-head spiral or a cross spiral.

[0019] This utility model also proposes a falling film evaporator, which includes the heat exchange tubes described above.

[0020] This utility model also proposes a refrigeration unit, which includes the heat exchange tubes described above.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] The liquid refrigerant of this invention enters the evaporation chamber structure through the evaporation holes and comes into contact with the nucleation sites within the evaporation chamber structure, thereby enabling the nucleation sites to generate evaporation bubbles more effectively. This improves the conditions for the generation of evaporation bubbles, thereby reducing the external thermal resistance of the heat exchange tube and increasing the heat exchange efficiency of the heat exchange tube. Attached Figure Description

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this invention are used to distinguish different objects and not to describe a particular order.

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a cross-sectional view of the heat exchange tube proposed in this utility model;

[0026] Figure 2 This is a partial structural schematic diagram of the heat exchange tube proposed in this utility model;

[0027] Figure 3 for Figure 2 An enlarged schematic diagram of reference numeral A in the attached figure;

[0028] Figure 4 for Figure 2 An enlarged view of reference numeral B in the attached diagram;

[0029] Figure 5 This is a partial top view of the heat exchange tube proposed in this utility model;

[0030] Figure 6 for Figure 5 The circumferential diagram proposed in the paper.

[0031] Figure label:

[0032] 10. Matrix; 101. Smooth section; 102. High-efficiency heat exchange section; 103. Transition section;

[0033] 20. Fin structure; 201. Protrusion; 202. Evaporation hole; 203. Cavity; 204. First aileron; 205. Second aileron;

[0034] 30. Slotted structure;

[0035] 40. Trench structure;

[0036] 50. Cavitation structure;

[0037] 60. Groove structure;

[0038] 70. Microrib structure;

[0039] 80. Passage. Detailed Implementation

[0040] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model. Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the present utility model, and does not imply that every embodiment of the present utility model must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0041] The principle and structure of this utility model will be described in detail below with reference to the accompanying drawings and embodiments.

[0042] In some embodiments, to improve the conditions for evaporation bubble formation, thereby reducing the external thermal resistance of the heat exchange tube and improving the heat exchange efficiency of the heat exchange tube, such as... Figure 1 , Figure 2 and Figure 5 As shown, this utility model proposes a heat exchange tube, comprising:

[0043] Matrix 10;

[0044] The fin structure 20 has multiple fin structures 20 spirally arranged along the circumferential direction on the outer side wall of the substrate 10. Each fin structure 20 has a circumferentially arranged protrusion 201 at the end away from the substrate 10, and an evaporation hole 202 is formed between adjacent protrusions 201 along the circumferential direction.

[0045] The adjacent fin structure 20 and the substrate 10 form an evaporation chamber structure (not shown, same throughout), and the evaporation chamber structure communicates with the evaporation hole 202.

[0046] It should be noted that, in this embodiment, the substrate 10 is preferably cylindrical in shape and is integrally formed by extrusion of metal material. Furthermore, the evaporation holes 202 facilitate the generation, growth, and escape of evaporation bubbles from within the evaporation chamber structure, as well as the entry of liquid refrigerant into the evaporation chamber structure. Additionally, the protrusions 201 of any fin structure 20 will contact the protrusions 201 of adjacent fin structures 20 arranged in a cross pattern.

[0047] Thus, when liquid refrigerant drips onto the finned structure 20 on the outer wall of the heat exchange tube, the liquid refrigerant enters the evaporation chamber structure through the evaporation hole 202. At this time, the liquid refrigerant flows within the evaporation chamber structure and undergoes nucleation boiling. Because the nucleation sites are located within the evaporation chamber structure, when the liquid refrigerant drips onto the outer wall of the heat exchange tube, it will first pass through the protrusion 201 and / or enter the evaporation chamber structure through the evaporation hole 202, and will not directly contact the nucleation sites within the evaporation chamber structure. Compared to the situation where the liquid refrigerant directly impacts the nucleation sites on the exposed surface, causing the nucleation sites to fail, or requiring a larger heat flux to start the boiling process, the evaporation chamber structure proposed in this invention can improve the fluidity of the liquid refrigerant, effectively utilize the heat exchange area of ​​the finned structure 20, and thus enable the nucleation sites to better generate evaporation bubbles, thereby improving the conditions for the generation of evaporation bubbles, reducing the external thermal resistance of the heat exchange tube, and improving the heat exchange efficiency of the heat exchange tube.

[0048] In some embodiments, to avoid insufficient lateral distribution of liquid refrigerant in the lower layer of the finned structure 20, such as... Figure 3 As shown, the fin structure 20 located below the two adjacent protrusions 201 is provided with a slotted structure 30 extending through it along the axial direction.

[0049] It is understood that the slotted structure 30 is also distributed along the circumferential direction of the fin structure 20. Furthermore, the preferred shape of the slotted structure 30 in this embodiment is an inverted trapezoid. Of course, the shape of the slotted structure 30 can also be selected as a triangle, rectangle, or other suitable shape depending on the actual situation, and is not limited here.

[0050] The dripping liquid refrigerant does not seamlessly cover the fin structure 20 on the outer wall of the heat exchange tube. The grooved structure 30 facilitates the axial diffusion of the liquid refrigerant on the fin structure 20, making full use of the heat exchange area of ​​the fin structure 20 and improving the heat transfer coefficient of the heat exchange tube.

[0051] In this embodiment, the slotted structure 30 increases the heat exchange area of ​​the finned structure 20 and slows down the downward flow of the liquid refrigerant in the evaporation chamber structure under gravity. This prevents the liquid refrigerant from accumulating on the lower surface of the finned structure 20 under gravity, and avoids evaporation from being concentrated on the lower surface of the finned structure 20, which would otherwise fail to fully utilize the heat exchange area of ​​the finned structure 20 along the entire circumference. Consequently, the liquid refrigerant can fully contact the sidewall of the finned structure 20 corresponding to the slotted structure 30, increasing the superheat required for evaporation, improving the fluidity of the liquid refrigerant, and fully utilizing the heat exchange area of ​​the finned structure 20 along the circumference. This reduces the external thermal resistance of the heat exchange tube and improves the heat exchange efficiency of the heat exchange tube.

[0052] In some embodiments, such as Figure 2The protrusion 201 shown is recessed inward to form a cavity 203, and the inner diameter of the cavity 203 gradually decreases in the radial direction.

[0053] It is understood that the opening shape of the cavity 203 is preferably elliptical. Of course, the opening shape of the cavity 203 can also be selected as circular or other suitable shapes according to the actual situation, which is not limited here.

[0054] In this embodiment, a velocity gradient is formed by the tapered cross section of the cavity 203, which causes the inflowing liquid refrigerant to generate a controllable spiral secondary vortex, thereby increasing the turbulence of the liquid refrigerant and transforming the originally ineffective end flow into an effective heat exchange area, thereby enhancing the contact efficiency between the liquid refrigerant and the surface of the fin structure 20.

[0055] In some embodiments, such as Figure 3 As shown, a groove structure 40 is radially provided on the side of every two adjacent fin structures 20, and the groove structure 40 communicates with the slotted structure 30.

[0056] It is understood that the groove structure 40 proposed in this embodiment is distributed along the circumferential direction of the fin structure 20.

[0057] In this embodiment, the groove structure 40 further increases the heat exchange area of ​​the fin structure 20, and the groove structure 40 can improve the retention of liquid refrigerant, so that the liquid refrigerant can fully contact the side wall of the fin structure 20 corresponding to the groove structure 40, which is conducive to the superheating of liquid refrigerant and promotes the superheating required for the formation of evaporation bubbles, thereby reducing the external thermal resistance of the heat exchange tube and improving the heat exchange efficiency of the heat exchange tube.

[0058] In some embodiments, to further increase the time that the groove structure 40 retains the liquid refrigerant and thus improve the heat exchange efficiency of the heat exchange tube, the inner diameter of the end of the groove structure 40 near the protrusion 201 is larger than the inner diameter of the other end.

[0059] It is understood that the preferred shape of the groove structure 40 proposed in this embodiment is an inverted trapezoid. Of course, the shape of the groove structure 40 can also be selected as an inverted triangle or other suitable shape according to the actual situation, which is not limited here.

[0060] In some embodiments, such as Figure 2 and Figure 4 As shown, each fin structure 20 is provided with a first aileron 204 and a second aileron 205 on both sides of the groove structure 40; the first aileron 204 and the second aileron 205 are curved relative to each other;

[0061] The substrate 10, the fin structure 20, and the corresponding first aileron 204 and second aileron 205 form a semi-closed cavitation structure 50.

[0062] It should be noted that the base 10 and fin structure 20 forming the cavitation structure 50 are both located between the corresponding first aileron 204 and second aileron 205.

[0063] In this embodiment, a portion of the liquid refrigerant is stored by the relatively curved first aileron 204 and second aileron 205, which greatly slows down the downward migration speed of the liquid refrigerant between adjacent fin structures 20 in the evaporation chamber structure. This further makes full use of the heat exchange area of ​​the fin structure 20, reduces the external thermal resistance of the heat exchange tube, and thus improves the heat exchange efficiency of the heat exchange tube. In addition, the semi-enclosed cavitation structure 50 can easily trap the gas remaining at the tail of the evaporation bubble to form a stable and continuous evaporation bubble, and provides more vaporization nucleus formation points (vaporization nucleus formation points are equivalent to nucleation sites) to generate nucleation boiling, thereby improving the formation efficiency of nucleation boiling, further reducing the external thermal resistance of the heat exchange tube, and improving the heat exchange efficiency of the heat exchange tube.

[0064] The base 10 is provided with channels 80 corresponding to the first auxiliary wing 204 and the second auxiliary wing 205. The extension length of the first auxiliary wing 204 and the second auxiliary wing 205 in the channel 80 accounts for 5%-80% of the inner diameter of the entire channel 80. This facilitates the retention of the liquid refrigerant flowing downward in the direction of gravity inside the channel 80, increases the residence time of the liquid refrigerant, allows the liquid refrigerant to be fully superheated, improves the formation efficiency of nucleation boiling, and is conducive to the formation of evaporation bubbles, thereby reducing the external thermal resistance of the heat exchange tube and improving the heat exchange efficiency of the heat exchange tube.

[0065] In some embodiments, such as Figure 2 and Figure 6 As shown, a groove structure 60 is provided on the base 10 at the bottom of two adjacent fin structures 20, and the groove structure 60 extends toward the corresponding two sides of the fin structure 20; and the groove structure 60 communicates with the groove structure 40.

[0066] The groove structure 60 is distributed circumferentially along the fin structure 20.

[0067] It is understood that the groove structure 60 proposed in this embodiment is preferably an inverted trapezoid. Of course, the shape of the groove structure 60 can also be selected as a triangle, rectangle or other suitable shape according to the actual situation, which is not limited here.

[0068] Furthermore, the groove structure 60 is located at the bottom of the groove structure 40 facing the base 10.

[0069] In this embodiment, the groove structure 60 further increases the heat exchange area of ​​the fin structure 20. Because the groove structure 60 is close to the heat source, it effectively provides the superheat required for evaporation and provides more vaporization nucleus formation points, which is conducive to the formation of evaporation bubbles, further improving the conditions for bubble formation, thereby reducing the external thermal resistance of the heat exchange tube and improving its heat exchange efficiency. Furthermore, the spaced groove structures 60 further improve the residence and heat transfer of the liquid refrigerant in the circumferential direction.

[0070] In some embodiments, such as Figure 1 As shown, the inner wall of the substrate 10 facing away from the fin structure 20 is provided with a microrib structure 70 in a circumferential spiral pattern. The microrib structure 70 is distributed in a multi-head spiral or a cross spiral pattern.

[0071] It is understandable that the microrib structure 70 is integrally formed with the substrate 10.

[0072] Thus, in this embodiment, the spirally distributed micro-rib structure 70 can effectively increase the heat exchange area of ​​the inner wall of the heat exchange tube, while also increasing the disturbance of the liquid refrigerant on the inner wall of the heat exchange tube, thereby enhancing the effect of turbulent secondary flow and thus improving the heat exchange efficiency of the inner wall of the heat exchange tube.

[0073] In some embodiments, such as Figure 1 As shown, the substrate 10 is composed of a smooth section 101, a high-efficiency heat exchange section 102 and a transition section 103; the two ends of the high-efficiency heat exchange section 102 are respectively provided with transition sections 103, and the end of the transition section 103 away from the high-efficiency heat exchange section 102 is correspondingly provided with a smooth section 101.

[0074] The transition section 103 can avoid the problem of stress concentration in the heat exchange tube. The flow velocity in a conventional heat exchange tube is generally around 3 m / s, which can cause a certain amount of vibration to the heat exchange tube. The transition section 103 can prevent the heat exchange tube from failing due to vibration.

[0075] The outer wall of the high-efficiency heat exchange section 102 is provided with multiple fin structures 20 spirally arranged circumferentially; the inner walls of both the high-efficiency heat exchange section 102 and the transition section 103 are provided with micro-rib structures 70 spirally distributed; the inner wall of the smooth section 101 is not provided with micro-rib structures 70, and the outer walls of both the smooth section 101 and the transition section 103 are provided with fin structures 20; the inner and outer diameters of the high-efficiency heat exchange section 102 and the transition section 103 are equal, the inner and outer diameters of the smooth section 101 are larger than the inner and outer diameters of the transition section 103, and the inner and outer diameters of the smooth section 101 towards the end of the transition section 103 gradually decrease until they are equal to the inner and outer diameters of the transition section 103.

[0076] In some embodiments, the present invention also provides a falling film evaporator, which includes the heat exchange tubes described above.

[0077] It should be noted that, in this embodiment, the preferred type of falling film evaporator is a horizontal falling film evaporator.

[0078] In this way, the heat exchange tube is located inside the falling film evaporator. When the liquid refrigerant distributed inside the falling film evaporator by a drip distributor (not shown, the same throughout) drips onto the fin structure 20 on the outer wall of the heat exchange tube, the liquid refrigerant first enters the evaporation cavity structure through the protrusion 201 and / or evaporation hole 202 to make full contact with the first auxiliary fin 204 and the second auxiliary fin 205, so as to superheat it and provide sufficient superheat for evaporation. Instead, it does not directly enter the evaporation cavity structure, thus ensuring that the liquid refrigerant does not directly impact the nucleation sites in the evaporation cavity structure. This effectively utilizes the heat exchange area of ​​the fin structure 20, thereby enabling the nucleation sites to better generate evaporation bubbles, thus improving the conditions for the generation of evaporation bubbles, reducing the external thermal resistance of the heat exchange tube, improving the heat exchange efficiency of the heat exchange tube, and improving the evaporation efficiency of the falling film evaporator.

[0079] Through the synergistic effect of the slotted structure 30, grooved structure 40, cavitation structure 50, and recessed structure 60, the heat exchange efficiency of the evaporation chamber structure and the flow performance of the liquid refrigerant are significantly improved, thereby further improving the conditions for the generation of evaporation bubbles, further reducing the external thermal resistance of the heat exchange tube, further improving the heat exchange efficiency of the heat exchange tube, and improving the evaporation efficiency of the falling film evaporator.

[0080] In some embodiments, the present invention also provides a refrigeration unit, the refrigeration unit including the heat exchange tubes described above.

[0081] It is understood that the refrigeration unit proposed in this embodiment is preferably a compressor refrigeration unit, and the refrigeration unit is equipped with an evaporator, and the evaporator is equipped with heat exchange tubes.

[0082] In this way, when the liquid refrigerant distributed by the drip distributor inside the evaporator drips onto the fin structure 20 on the outer wall of the heat exchange tube, the liquid refrigerant will first enter the evaporation cavity structure through the protrusion 201 and / or evaporation hole 202, instead of directly entering the evaporation cavity structure. This ensures that the liquid refrigerant does not directly impact the nucleation sites within the evaporation cavity structure, thereby effectively utilizing the heat exchange area of ​​the fin structure 20. This allows the nucleation sites to better generate evaporation bubbles, thereby improving the conditions for evaporation bubble generation, reducing the external thermal resistance of the heat exchange tube, and improving the heat exchange efficiency of the refrigeration unit.

[0083] Through the synergistic effect of the slotted structure 30, grooved structure 40, cavitation structure 50, and recessed structure 60, the heat exchange efficiency of the evaporation chamber structure and the flow performance of the liquid refrigerant are significantly improved, thereby further improving the conditions for the generation of evaporation bubbles, further reducing the external thermal resistance of the heat exchange tube, and further improving the heat exchange efficiency of the refrigeration unit.

[0084] Obviously, the embodiments described above are only some embodiments of this utility model, not all embodiments. The accompanying drawings show preferred embodiments of this utility model, but do not limit the patent scope of this utility model. This utility model can be implemented in many different forms; rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of this utility model. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this utility model specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this utility model.

Claims

1. A heat exchange tube, characterized by, include: Matrix (10); Fin structure (20): The outer side wall of the substrate (10) is provided with multiple fin structures (20) spirally arranged in the circumferential direction. Each fin structure (20) has a protrusion (201) arranged in the circumferential direction at one end away from the substrate (10). An evaporation hole (202) is formed between adjacent protrusions (201) in the circumferential direction. The adjacent fin structure (20) and the substrate (10) form an evaporation cavity structure, which is connected to the evaporation hole (202).

2. The heat exchange tube according to claim 1, wherein The fin structure (20) located below the two adjacent protrusions (201) has a slotted structure (30) extending through it along the axial direction.

3. The heat exchange tube according to claim 2, wherein The protrusion (201) is recessed inward to form a cavity (203), and the inner diameter of the cavity (203) gradually decreases radially.

4. The heat exchange tube of claim 2, wherein Each pair of adjacent fin structures (20) has a radially arranged groove structure (40) on its side, and the groove structure (40) communicates with the slotted structure (30).

5. The heat exchange tube according to claim 4, wherein The inner diameter of the groove structure (40) at one end near the protrusion (201) is larger than the inner diameter at the other end.

6. The heat exchange tube of claim 4, wherein Each of the fin structures (20) has a first aileron (204) and a second aileron (205) on both sides corresponding to the groove structure (40); the first aileron (204) and the second aileron (205) are curved relative to each other; The substrate (10), the fin structure (20), the corresponding first aileron (204) and the second aileron (205) form a semi-closed cavitation structure (50).

7. The heat exchange tube of claim 4, wherein A groove structure (60) is provided on the base (10) at the bottom of two adjacent fin structures (20), the groove structure (60) extends to the corresponding two sides of the fin structure (20); and the groove structure (60) communicates with the groove structure (40); The groove structure (60) is distributed circumferentially along the fin structure (20).

8. The heat exchange tube of claim 1, wherein The inner wall of the substrate (10) facing away from the fin structure (20) is provided with a micro-rib structure (70) in a circumferential spiral pattern. The micro-rib structure (70) is distributed in a multi-head spiral or a cross spiral pattern.

9. A falling film evaporator characterized by The falling film evaporator includes the heat exchange tube as described in any one of claims 1-8.

10. A refrigeration unit characterized by, The refrigeration unit includes the heat exchange tube as described in any one of claims 1-8.

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