CN111981870A

CN111981870A - Falling film type heat exchanger and heat pump unit comprising same

Info

Publication number: CN111981870A
Application number: CN202010821121.8A
Authority: CN
Inventors: 张治平; 王宗信; 胡东兵; 胡海利
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2020-11-24
Anticipated expiration: 2040-08-14
Also published as: CN111981870B

Abstract

The invention discloses a falling film heat exchanger and a heat pump unit comprising the same. Through the arrangement, the pressure drop of the gaseous refrigerant is reduced and the uniformity of gas distribution is improved under the heating working condition, so that the heat exchange efficiency is improved, the gas-liquid separation degree can be effectively improved under the refrigerating working condition, the uniform distribution effect of the liquid refrigerant is improved, and the heat exchange efficiency is effectively improved.

Description

Falling film type heat exchanger and heat pump unit comprising same

Technical Field

The invention relates to the technical field of heat pump units, in particular to a falling film type heat exchanger and a heat pump unit comprising the same.

Background

Heat pump units are increasingly widely used because of the simultaneous consideration of both cooling and heating functions, and conventional heat pump units employ flooded heat exchangers or dry heat exchangers.

If a flooded heat exchanger is adopted, the heat exchange tube is soaked in the refrigerant under the refrigeration working condition, and the refrigerant filling amount is large. When the unit works, the heat of the chilled water on the inner side of the refrigerant absorption tube is transferred under the influence of the refrigerant hydrostatic column, and the heat exchange efficiency is low; in the heating condition, the gaseous refrigerant outside the tube condenses and transfers heat to the cooling water inside the tube to produce hot water.

If a dry heat exchanger is adopted, when the refrigeration working condition is met, a gas-liquid two-phase refrigerant is evaporated in the tube, and the inlet cannot uniformly distribute liquid to all heat exchange tubes, so that the heat exchange efficiency of each position of the heat exchanger is greatly different, the outlet of the heat exchange tube with more liquid distribution has the problem of air outlet liquid, and the outer side of the tube of the dry heat exchanger is subjected to baffling heat exchange of chilled water and is influenced by a flow field and flow velocity, and the heat exchange efficiency of the outer side of the tube is lower; in the heating condition, the problems of uneven gas distribution at the inner side of the tube and low heat exchange efficiency at the outer side of the tube exist.

Therefore, a heat exchange mode of the falling film heat exchanger is generated, and specifically, the working principle of the falling film heat pump heat exchanger is that refrigerant liquid on the outer side of the tube drips and sprays the heat of the frozen water in the evaporation absorption tube on the outer wall surface of the heat exchange tube during refrigeration, and refrigerant gas condenses on the outer side of the tube during heating to transfer the heat to cooling water on the inner side of the tube. The problems of uneven liquid distribution and gas distribution when the gas-liquid two-phase refrigerant flows in the tube of the dry heat exchanger and low heat exchange efficiency caused by small flow velocity of the secondary refrigerant outside the tube are solved; and meanwhile, under the refrigeration working condition, the film evaporation is arranged outside the tube, the influence of a hydrostatic column on the heat exchange efficiency is avoided, and the advantage of the full-liquid heat exchanger is obvious.

However, when the falling film heat pump heat exchanger is in a cooling working condition, the gas-liquid mixed refrigerant is uniformly distributed along the horizontal direction of the shell through the liquid distribution structure on the upper part of the shell, and then is dripped to the outer wall surface of the heat exchange tube from top to bottom along the tube bank. At the moment, because the liquid distribution structure is in a gas-liquid mixed state with pressure, the liquid distribution structure has very high requirements on the horizontal uniform liquid distribution capability. The liquid refrigerant drips from top to bottom and the compressor suction port is also located at the top of the shell, so that when the liquid distribution structure is designed, the gas circulation is required to be avoided from carrying liquid drops to return to the compressor suction port.

In view of the above, chinese patent application with patent publication No. CN110375574A discloses a falling film uniform distribution device capable of improving film distribution and exhaust performance, and belongs to the technical field of heat exchangers. The arc-shaped end enclosure of the falling film uniform distribution device is arranged at the top of the plate-fin heat exchanger body, and the plate-fin heat exchanger body and the arc-shaped end enclosure are both arranged in the outer shell; a first-stage distribution plate is arranged at the lower opening of the arc-shaped end socket and is an arc-shaped plate with the middle part protruding upwards, a second-stage distribution plate is arranged below the first-stage distribution plate, a third-stage distribution plate is arranged below the second-stage distribution plate, and uniformly distributed holes are formed in the first-stage distribution plate, the second-stage distribution plate and the third-stage distribution plate; and a plurality of trapezoidal film distributors are fixed at the bottom of the third-stage distribution plate and are arranged at the centers of inlets at the top ends of the evaporation channels in a one-to-one correspondence manner. The multistage uniform distribution device structure and the trapezoidal film distribution device are adopted, the film distribution effect is improved, the film is arranged on the built-in supporting mechanism to realize gas-liquid separation, and the risk that liquid is carried by gas is reduced.

Although the above scheme can have a certain effect on liquid distribution and gas-liquid separation, in a heating condition, a gaseous refrigerant enters the heat exchanger from the top, and at this time, due to the arrangement of the multi-stage distribution plates, the flow path of the gaseous refrigerant is longer, a larger pressure drop is generated, energy waste of the compressor is caused, and the heat exchange efficiency is lower.

Disclosure of Invention

The invention provides a falling film type heat exchanger, aiming at solving the defect that the heat exchange efficiency of the falling film type heat exchanger in the prior art is low under the heating condition.

The invention adopts the technical scheme that the falling film heat exchanger comprises a shell, wherein a liquid distribution structure and a heat exchange tube are arranged in the shell, an air inlet tube is arranged on the shell, a gas-homogenizing structure is arranged at the end part of the air inlet tube, the air inlet tube or the gas-homogenizing structure penetrates through the liquid distribution structure, and the air inlet tube or the gas-homogenizing structure penetrates through the liquid distribution structure to enable the gas-homogenizing structure to be positioned between the liquid distribution structure and the heat exchange tube.

Preferably, the air inlet pipe penetrates through the liquid distribution structure, and the gas-equalizing structure is provided with a plurality of gas-equalizing holes which enable the gaseous refrigerant to be dispersed and contact with the heat exchange pipe.

Preferably, the gas homogenizing structure is a gas homogenizing box, a plurality of gas homogenizing holes are formed in the gas homogenizing box, and the gas homogenizing holes formed in the bottom of the gas homogenizing box correspond to the heat exchange tubes respectively.

Preferably, the intake pipe is provided with two or more, two or more the one end intercommunication of intake pipe is converged and is worn out the casing, two or more the other end of intake pipe is equallyd divide and is provided with respectively the box of evening gas.

Preferably, the gas-equalizing structure penetrates through the liquid distribution structure and is positioned on at least one side of the heat exchange tube, a plurality of gas-equalizing holes which enable the gaseous refrigerant to be dispersed and to be in contact with the heat exchange tube are formed in the gas-equalizing structure, and the gas-equalizing holes are uniformly formed in one side, facing the heat exchange tube, of the gas-equalizing structure.

Preferably, the gas-homogenizing structure comprises at least one pair of gas-permeable plates positioned at two sides of the heat exchange tube, the upper ends of the gas-permeable plates are communicated and connected with the gas inlet tube, and the gas-permeable plates are arranged in a hollow mode and provided with a plurality of gas-homogenizing holes towards one side of the heat exchange tube.

Preferably, the air equalizing holes formed in each pair of the air permeable plates are formed in a staggered manner.

Preferably, the air holes of one of the air permeable plates of each pair are opened in the upper half part, and the air holes of the other of the air permeable plates of each pair are opened in the lower half part.

Preferably, the bottom of each pair of the ventilation plates is provided with an air equalizing hole.

Further, the top of the shell is also provided with an air outlet pipe, the top of the shell is provided with a liquid inlet pipe, the bottom of the shell is provided with a liquid outlet pipe, and the bottom end of the liquid inlet pipe is located in the liquid distribution structure.

Preferably, the liquid inlet pipe is positioned at the central position of the liquid distribution structure.

Preferably, the bottom of the liquid distribution structure is at least one layer of liquid-equalizing plate, a plurality of uniformly distributed liquid-equalizing holes are formed in the liquid-equalizing plate, and the liquid-equalizing holes in the lowermost liquid-equalizing plate are correspondingly arranged with the heat exchange tubes.

Preferably, the top of the liquid distribution structure is provided with a layer of gas-liquid filter screen.

Furthermore, the position of the liquid equalizing plate, which is opposite to the liquid inlet pipe, is provided with an anti-impact filter screen.

Preferably, the gas-liquid filter screen and the scour protection filter screen are coiled by stainless steel materials and are stacked, and the corrugations of the wire mesh are staggered and consistent in density when the wire mesh is coiled.

Further, still be equipped with top baffle and the side shield that the cover located cloth liquid structure top in the casing, top baffle and side shield enclose and establish into below open-ended cavity.

The invention also provides a heat pump unit which comprises the falling film heat exchanger.

Compared with the prior art, the invention has the following beneficial effects:

1. the pressure drop of the gaseous refrigerant is reduced under the heating working condition, and the uniformity of gas distribution is improved, so that the heat exchange efficiency is improved;

2. the gas-liquid separation degree can be effectively improved under the refrigeration working condition, the uniform distribution effect of liquid refrigerants is improved, and the heat exchange efficiency is effectively improved;

3. the anti-impact filter screen can timely separate gas-liquid mixed refrigerants entering the liquid inlet, and direct impact of the liquid refrigerants on the liquid homogenizing plate is avoided due to the anti-impact filter screen, so that the liquid refrigerants are further uniformly distributed;

4. the arrangement of the gas homogenizing box avoids the direct impact of the gaseous refrigerant on the heat exchange pipe, reduces the generation of vibration, and improves the gas homogenizing effect;

5. the air distributing holes formed in pairs in the air permeable plates are arranged in a staggered mode, so that a central flow dead zone formed by air distribution at the same height on two sides can be avoided, the vertically staggered air inlet structure can form a stable flow field in the shell, and the area of the heat exchange tube is utilized more effectively.

Drawings

The invention is described in detail below with reference to examples and figures, in which:

FIG. 1 is an axial sectional view schematically illustrating a heating condition-related structure according to a first embodiment;

FIG. 2 is a schematic circumferential sectional view of a heating condition-related structure of the first embodiment;

FIG. 3 is an axial sectional view of a structure relating to a heating mode according to a second embodiment;

FIG. 4 is a schematic circumferential sectional view of a structure relating to a heating condition of the second embodiment;

FIG. 5 is a top view of FIG. 4;

FIG. 6 is a schematic circumferential cross-sectional view of a refrigeration condition-related structure of the present invention;

FIG. 7 is a top view of the structure relating to the refrigeration condition of the present invention, mainly showing the positional relationship between the liquid inlet pipe and the gas outlet pipe;

fig. 8 is a plan view of a structure relating to a heating operation condition of the present invention, mainly showing a positional relationship between an intake pipe and a communicating pipe.

1. A liquid inlet pipe; 2. an air outlet pipe; 3. an air inlet interface; 4. a communicating pipe; 5. an air inlet pipe; 6. a liquid outlet pipe; 7. a housing; 8. a heat exchange pipe; 9. a closing baffle; 10. a top baffle; 11. a liquid homogenizing plate; 12. a gas-liquid filter screen; 14. a gas homogenizing box; 15. a scour protection filter screen; 16. side baffles; 17. a support structure; 18. a gas permeable plate; 19. a homogenization hole; 20. air holes are uniformly distributed.

Detailed Description

A falling film heat exchanger is shown in figure 1 and comprises a shell 7, wherein a liquid distribution structure and heat exchange tubes 8 are arranged in the shell 7, the liquid distribution structure is fixed in the shell 7, and the heat exchange tubes 8 are arranged in multiple rows and are positioned right below the liquid distribution structure. An air inlet pipe 5 is installed at the top of the shell 7, an air equalizing structure is arranged at the end part of the air inlet pipe 5, the air inlet pipe 5 or the air equalizing structure penetrates through the liquid distribution structure, and a plurality of air equalizing holes 20 which enable gaseous refrigerants to be dispersed and to be in contact with the heat exchange pipe 8 are formed in the air equalizing structure.

As shown in fig. 1 and 2, the air inlet pipe 5 directly extends downwards and penetrates through the liquid distribution structure, the bottom end of the air inlet pipe 5 is fixedly mounted in the air equalizing structure which is an air equalizing box 14, the air equalizing box 14 is positioned between the liquid distribution structure and the heat exchange pipe 8, air equalizing holes 20 are formed in the bottom and the periphery of the air equalizing box 14, and the positions of the air equalizing holes 20 formed in the bottom correspond to the heat exchange pipe 8 below the air equalizing box.

Through the setting of above-mentioned gas box 14, gaseous refrigerant gets into and directly reachs gas box 14 from intake pipe 5 during the operating mode heats, escapes through a plurality of gas holes 20 and contacts with heat exchange tube 8, realizes the heat transfer, has reduced highly compressed gaseous refrigerant to the impact of heat exchange tube 8, has reduced the vibrations that produce easily.

As shown in fig. 1 and 2, in order to make the gaseous refrigerant more uniformly dispersed, a plurality of the gas-homogenizing boxes 14 may be provided according to the size of the heat exchanger, that is, two or more gas inlet pipes 5 are provided, one ends of the two or more gas inlet pipes 5 are communicated and converged and penetrate through the housing 7, and the other ends of the two or more gas inlet pipes 5 are respectively provided with the gas-homogenizing boxes 14. Be provided with two intake pipes 5 and two gas box 14 of samming in this embodiment, the intercommunication is realized through one end horizontally communicating pipe 4 in the upper end of two intake pipes 5, is provided with vertical ascending interface 3 that admits air on communicating pipe 4 again to the refrigerant under the working condition of heating only need get into the heat exchanger from this entry of interface 3 that admits air, can realize homodisperse's effect through a plurality of gas box 14 of samming.

In another embodiment, the gas-homogenizing structure penetrates through the liquid-distributing structure and is located on at least one side of the heat exchange tube 8, as shown in fig. 3 and 4, the gas-homogenizing holes 20 are uniformly formed in one side of the gas-homogenizing structure facing the heat exchange tube 8, specifically, the gas-homogenizing structure comprises at least one pair of ventilating plates 18 located on two sides of the heat exchange tube 8, the upper ends of each pair of ventilating plates 18 are communicated and connected with the gas inlet tube 5, and the ventilating plates 18 are arranged in a hollow manner and are provided with a plurality of gas-homogenizing holes 20 on one side facing the heat exchange tube 8.

The air equalizing holes 20 formed in each pair of the air permeable plates 18 are arranged in a staggered manner, so that a central flow dead zone formed by air distribution at the same height on two sides can be avoided, stable flow fields can be formed in the shell 7 by arranging the air equalizing holes 20 staggered up and down, and the area of the heat exchange tube 8 can be utilized more effectively. Meanwhile, the air equalizing holes 20 are formed in the lowest portion of the pair of air permeable plates 18 and used for timely removing the liquid condenser and preventing liquid accumulation in the air permeable plates 18.

As shown in fig. 3-5, the upper ends of each pair of air-permeable plates 18 are also communicated through a communication pipe 4, and the communication pipe 4 is communicated with the air inlet pipe 5, so that the refrigerant can enter the air-permeable plates 18 on both sides respectively after entering from the air inlet pipe 5, and certainly, in order to adapt to the size of the heat exchanger and improve the heat exchange efficiency, the number of the air-permeable plates 18 can be multiple.

In order to further improve the air-equalizing effect, the air-equalizing box 14 is located on the central line of the shell 7, and if paired air-permeable plates 18 are adopted, each pair of air-permeable plates 18 are also symmetrically arranged along the central line, so that the refrigerant can be more dispersed and uniform when escaping from the air-equalizing holes 20, the internal flow field of the shell 7 can be optimized, and the air distribution uniformity of the shell 7 is increased.

Through the scheme, the gaseous refrigerant is directly dispersed out through the air equalizing hole 20 under the heating condition and then contacts with the heat exchange tube 8 for heat exchange, so that the flow path of the refrigerant is reduced, the pressure drop is reduced, the power of the compressor is improved, and the heat exchange efficiency is also improved.

Further, as shown in fig. 6-8, a liquid inlet pipe 1 and a gas outlet pipe 2 are installed at the top of a shell 7, a liquid outlet pipe 6 is arranged at the bottom of the shell 7, in order to improve the uniform distribution degree of the liquid refrigerant under the refrigeration working condition, the liquid uniformizing device is a box-packed device and comprises a sealing baffle plate 9 on the periphery, at least one layer of liquid uniformizing plate 11 at the bottom and a gas-liquid filter screen 12 arranged at the top, the bottom end of the liquid inlet pipe 1 directly extends into the liquid uniformizing device, a plurality of uniform liquid uniformizing holes 19 are formed in the liquid uniformizing plate 11, and the liquid refrigerant is leaked from the liquid uniformizing holes 19 and then drops on a heat exchange pipe 8 below, so that heat absorption and evaporation.

In the embodiment, as shown in fig. 6-8, the liquid-homogenizing plate 11 is provided with two layers and fixed at the bottom of the four closed baffles 9 by welding, and liquid-homogenizing holes 19 formed in the liquid-homogenizing plate 11 of the second layer are arranged corresponding to the positions of the heat exchange tubes 8 arranged in rows below. Meanwhile, the position of the first-layer liquid equalizing plate 11, which is opposite to the liquid inlet pipe 1, is provided with the scour prevention filter screen 15, the gas-liquid filter screen 12 and the scour prevention filter screen 15 are made of stainless steel materials in a coiled and stacked mode, for example, 1Cr18Ni9Ti, and the corrugations of the wire mesh are required to be staggered and consistent in density when being coiled. Wherein, scour protection filter screen 15 is the silk screen structure, fills in the brace rod box that the iron bar welded, accomplishes fixedly the box welding above the liquid homogenizing plate 11.

When the refrigeration working condition is adopted, the throttled gas-liquid phase refrigerant enters the liquid distribution structure through the liquid inlet pipe 1, and the high-speed fluid at the outlet of the liquid inlet pipe 1 impacts the anti-impact filter screen 15. The filter screen is of a porous elastic structure and has wettability to liquid, so that on one hand, the elastic deformation of the filter screen is utilized to prevent high-speed fluid at the outlet of the liquid inlet pipe 1 from impacting the liquid homogenizing plate 11 to generate vibration to influence the working stability of the liquid homogenizing plate; on the other hand, the filter screen can adsorb liquid to carry out gas-liquid separation on the fluid, the final effect is that the liquid is deposited on the liquid equalizing plate 11 at the bottom of the liquid distribution structure, and the gas flows out from the top of the liquid distribution structure, so that the liquid distribution uniformity effect of the liquid distribution structure is improved; meanwhile, the filter screen is of a porous structure, and fluid is guided to flow back and forth in the anti-impact filter screen 15, so that the flow speed is reduced, and the uniformity of a flow field and the uniformity of liquid distribution are improved. The gas after the initial gas-liquid separation by the anti-impact filter screen 15 flows upwards through the gas-liquid filter screen 12 to separate the liquid again. On the one hand, the gas is guided to flow out of the liquid distribution structure, so that the disturbance of the gas to the internal flow field of the liquid distribution structure is reduced, the liquid is strengthened and homogenized, and on the other hand, the liquid is gathered in the liquid distribution structure to prevent the gas carrying liquid drops from reaching the gas outlet pipe 2 to cause the problem of gas suction and liquid carrying.

Further, still install the cover in casing 7 and locate top baffle 10 and the side shield 16 of cloth liquid structure top, top baffle 10 and side shield 16 enclose and establish into below open-ended cavity, and the cavity is whole to be opening spill down, and top baffle 10 and side shield 16 pass through bearing structure 17 to be fixed in the top of casing 7, and bearing structure 17 can be the ironware, realizes fixedly through the welded form. The gas passing through the gas-liquid filter screen 12 is guided to flow downwards and then reaches the gas outlet pipe 2 from the flow path outside the side baffle 16 along with the gas generated by the evaporation heat exchange on the surface of the heat exchange pipe 8. The stroke of the gas reaching the compressor is increased through the concave flow path, and the problems of gas suction and liquid entrainment of the compressor are further avoided.

Similarly, in order to improve the uniformity of liquid distribution, the liquid inlet pipe 1 is arranged at the center of the liquid distribution structure, and the gas outlet pipe 2 is arranged on the center line according to the position of the compressor.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. Falling liquid film heat exchanger, including casing (7), be equipped with cloth liquid structure and heat exchange tube (8) in casing (7), its characterized in that, be equipped with intake pipe (5) on casing (7), the tip of intake pipe (5) is equipped with the gas-equalizing structure, intake pipe or gas-equalizing structure pass the cloth liquid structure and make gas-equalizing structure is located between cloth liquid structure and heat exchange tube (8).

2. The falling film heat exchanger according to claim 1, wherein the air inlet pipe (5) passes through the liquid distribution structure, and the gas-equalizing structure is provided with a plurality of gas-equalizing holes (20) for dispersing the gaseous refrigerant to contact the heat exchange pipes (8).

3. The falling film heat exchanger according to claim 2, wherein the gas-homogenizing structure is a gas-homogenizing box (14), a plurality of gas-homogenizing holes (20) are formed in the gas-homogenizing box (14), and the gas-homogenizing holes (20) formed in the bottom of the gas-homogenizing box (14) are respectively arranged corresponding to the positions of the heat exchange tubes (8).

4. The falling film heat exchanger according to claim 2, characterized in that the inlet pipes (5) are provided in two or more, one end of the two or more inlet pipes (5) is communicated and merged out of the shell (7), and the other end of the two or more inlet pipes (5) is provided with the gas homogenizing box (14), respectively.

5. The falling film heat exchanger according to claim 1, wherein the gas-homogenizing structure passes through the liquid-distributing structure and is located on at least one side of the heat exchange tube (8), the gas-homogenizing structure is provided with a plurality of gas-homogenizing holes (20) for dispersing the gaseous refrigerant to contact with the heat exchange tube (8), and the gas-homogenizing holes (20) are uniformly opened on one side of the gas-homogenizing structure facing the heat exchange tube (8).

6. The falling film heat exchanger according to claim 5, wherein the gas-homogenizing structure comprises at least one pair of gas-permeable plates (18) positioned at two sides of the heat exchange tube (8), the upper ends of each pair of gas-permeable plates (18) are communicated and connected with the gas inlet tube (5), and the gas-permeable plates (18) are arranged in a hollow manner and are provided with a plurality of gas-homogenizing holes (20) at one side facing the heat exchange tube (8).

7. The falling film heat exchanger according to claim 6, wherein the gas holes (20) of each pair of gas permeable plates (18) are staggered.

8. The falling film heat exchanger according to claim 6, wherein the gas holes (20) of one of the gas-permeable plates (18) of each pair open in the upper half and the gas holes (20) of the other of the gas-permeable plates (18) of each pair open in the lower half.

9. The falling film heat exchanger according to claim 6, wherein each pair of the gas permeable plates (18) is provided with a gas homogenizing hole (20) at the bottom.

10. The falling film heat exchanger according to any one of claims 1 to 9, wherein the shell (7) is further provided with an air outlet pipe (2) at the top, the shell (7) is provided with an air inlet pipe (1) at the top, the shell (7) is provided with an air outlet pipe (6) at the bottom, and the bottom end of the air inlet pipe (1) is located in the liquid distribution structure.

11. The falling film heat exchanger according to any of claims 10, characterized in that the liquid inlet pipe (1) is located in the central position of the liquid distribution structure.

12. The falling film heat exchanger according to claim 10, wherein the bottom of the liquid distribution structure is at least one liquid-homogenizing plate (11), the liquid-homogenizing plate (11) is provided with a plurality of uniformly distributed liquid-homogenizing holes (19), and the liquid-homogenizing holes (19) on the lowermost liquid-homogenizing plate (11) are arranged corresponding to the heat exchange tubes (8).

13. The falling film heat exchanger according to claim 10, wherein the top of the liquid distribution structure is a layer of gas-liquid filter screen (12).

14. The falling film heat exchanger according to claim 13, characterized in that an impingement screen (15) is arranged at a position of the liquid homogenizing plate (11) facing the liquid inlet pipe (1).

15. The falling film heat exchanger according to claim 14, wherein the gas-liquid filter screens (12) and the erosion-resistant filter screens (15) are made of stainless steel material coils stacked, and the corrugations of the wire mesh are staggered and uniform in density during coiling.

16. The falling film heat exchanger according to claim 1, wherein a top baffle (10) and a side baffle (16) are arranged in the shell (7) and cover the liquid distribution structure, and the top baffle (10) and the side baffle (16) enclose a cavity with an opening at the lower part.

17. A heat pump unit comprising a falling film heat exchanger according to claim 1.