CN110822772A

CN110822772A - Falling film evaporator

Info

Publication number: CN110822772A
Application number: CN201810923286.9A
Authority: CN
Inventors: 苏秀平; 王生龙; 盛世民; 樊敏楠
Original assignee: York Wuxi Air Conditioning and Refrigeration Co Ltd; Johnson Controls Technology Co
Current assignee: York Wuxi Air Conditioning and Refrigeration Co Ltd; Johnson Controls Technology Co
Priority date: 2018-08-14
Filing date: 2018-08-14
Publication date: 2020-02-21

Abstract

The application relates to a falling film evaporator (100), wherein the falling film evaporator (100) accommodates a heat exchange pipe (304), a porous plate (205) and a spray pipe (202) in a shell (101), wherein the porous plate (205) is arranged between the spray pipe (202) and the heat exchange pipe (304), so that refrigerant sprayed out of the spray pipe (202) is sprayed to the surface of the heat exchange pipe (304) through distribution of the porous plate (205). The spray openings (301) on the spray pipes (202) are strip-shaped, and the extending direction of the openings is vertical to the length direction of the spray pipes (202). The length direction of the spray pipe (202) is set to be approximately vertical to the length direction of the heat exchange pipe (304), so that the refrigerant sprayed out of the spray opening (301) approximately flows towards the length direction of the shell (101), the flow path of the refrigerant is greatly prolonged, and uneven spraying of the refrigerant to the surface of the heat exchange pipe (304) is avoided.

Description

Falling film evaporator

Technical Field

The application relates to the technical field of falling film evaporators.

Background

The falling film evaporator generally adopts a refrigerant distributor to distribute the refrigerant on the surface of a heat exchange tube to form a liquid film for evaporation, utilizes a film evaporation mechanism on the surface of the heat exchange tube, has the advantages of high heat transfer efficiency and low refrigerant charge amount, and is a research hotspot in the refrigeration and air conditioning industry in recent years. However, the uniformity of refrigerant distribution across the heat exchange tube bundle within the evaporator is a critical factor that limits the heat exchange performance of the evaporator. The state of the refrigerant entering the refrigerant distributor is usually a gas-liquid two-phase refrigerant, and if the two-phase refrigerant is not uniformly distributed on the heat exchange tube bundle of the falling film evaporator, the refrigerant distributor can supply excessive refrigerant to one part of heat exchange tubes, and the refrigerant supply to the other part of heat exchange tubes is insufficient, so that a dry spot phenomenon can occur, and the overall heat exchange performance of the falling film evaporator is reduced.

Disclosure of Invention

It is an object of the present application to provide an improved falling film evaporator capable of uniformly distributing refrigerant to heat exchange tubes.

In order to achieve the above object, the present application provides a falling film evaporator comprising: casing, heat exchange tube, perforated plate, shower and feed liquor pipe. The shell is provided with a cavity; the length direction of the heat exchange tube is consistent with the length direction of the shell; the porous plate is arranged above the heat exchange tube and is provided with a plurality of distribution holes; the spraying pipe is arranged above the porous plate, a plurality of spraying ports are formed in the spraying pipe, the spraying ports are distributed at intervals along the length direction of the spraying pipe, and the spraying ports are arranged to be capable of spraying a refrigerant to the porous plate; the liquid inlet pipe is in fluid communication with the spray pipe, so that the refrigerant flowing through the liquid inlet pipe can flow into the spray pipe; the heat exchange pipe, the porous plate and the spray pipe are all arranged in the containing cavity; the length direction of the shower pipe is approximately perpendicular to the length direction of the shell.

In the falling film evaporator, the length direction of the porous plate is consistent with the length direction of the shell, and the spray ports are arranged to spray the refrigerant to the porous plate so that the refrigerant can flow along the length direction of the porous plate.

As in the foregoing falling film evaporator, the bottom of the spray pipe has an arc end surface, the arc end surface protrudes toward the perforated plate, the spray opening is in a bar shape, and at least a part of the spray opening is disposed on the arc end surface.

As in the falling film evaporator, the shower tube has two extending portions extending along the length direction of the shell, the end portions of the extending portions include convex arc end surfaces, the shower openings are in a bar shape, and at least a part of the shower openings are arranged on the arc end surfaces.

As mentioned above, the cross section of the shower tube is in a flat ellipse shape, the two extension portions are respectively located at the left and right ends of the shower tube, the shower opening is in a bar shape, and the shower opening extends from the bottom of the shower tube to the arc end faces at the left and right ends of the shower tube respectively.

In the falling film evaporator, the cross section of the shower pipe is inverted "Y", the two extending portions are respectively located at the bottom of the shower pipe and extend obliquely downward, the shower opening is in a bar shape, and at least a part of the shower opening is disposed on the arc end surface.

As mentioned above, in the falling film evaporator, a plurality of the shower pipes are disposed, and top ends of the shower pipes are connected to each other, so that the shower pipes are in fluid communication with each other.

In the falling film evaporator, the number of the spray pipes is even, and the plurality of the spray pipes are symmetrically distributed relative to the liquid inlet pipe.

The falling film evaporator as set forth above further comprising a liquid inlet box disposed between the liquid inlet tube and the shower tube such that the liquid inlet tube and the shower tube can be in fluid communication through the liquid inlet box.

As in the falling film evaporator described above, the falling film evaporator further includes a cover plate disposed at an upper portion of the shower pipe, and two side edges of the cover plate extend toward the porous plate and are connected with two side edges of the porous plate in a sealing manner by direct or indirect connection.

The falling film evaporator has the advantages that the length direction of the spray pipe is set to be approximately vertical to the length direction of the shell of the evaporator, the spray-out refrigerant can move approximately towards the length direction of the shell from the spray opening due to the arrangement, the flow path of the spray-out refrigerant from the spray opening is prolonged, and the problem that the spray-out refrigerant is blocked to spray the surface of the heat exchange pipe unevenly due to the flow is avoided.

Drawings

Fig. 1 is a schematic perspective view of a falling film evaporator 100 according to an embodiment of the present application;

fig. 2 is a schematic structural view of a portion of the components located inside the shell 101 of the falling film evaporator 100 shown in fig. 1;

FIG. 3 is a radial cross-sectional view of the falling film evaporator 100 shown in FIG. 1 at the location of the liquid inlet tube 102;

FIG. 4 is an enlarged partial view of the falling film evaporator 100 shown in FIG. 3 in the area of the shower tubes 202;

FIG. 5 is a schematic perspective view of the shower 202 of FIG. 2;

FIG. 6 shows a cross-section of the shower 202 shown in FIG. 5 at the location of the shower opening 301;

FIG. 7 shows the trajectory of the refrigerant after it exits the shower pipe 202 arranged in the position shown in FIG. 4;

FIG. 8A shows a first embodiment of the cross-sectional shape of the shower 202 at the location of the shower opening 301;

FIG. 8B shows a second embodiment of the cross-sectional shape of the shower 202 at the location of the shower opening 301;

fig. 9 is an axial cross-sectional view of a falling film evaporator with two shower tubes 202 at the location of the liquid inlet tube 102;

figure 10A shows a first embodiment of two shower arrangements in a falling film evaporator;

FIG. 10B shows a second embodiment of two shower arrangements in a falling film evaporator;

FIG. 10C illustrates a third embodiment of two shower tube configurations in a falling film evaporator;

FIG. 10D shows a fourth embodiment of two shower tube configurations in a falling film evaporator;

figure 11 shows a comparative example of the positional arrangement of the shower tubes inside the falling film evaporator;

figure 12 shows an axial cross-sectional view of a falling film evaporator at a feed tube location with the arrangement of shower tube locations shown in figure 11;

figure 13 shows a radial cross-sectional view of a falling film evaporator at a feed tube location with the arrangement of shower tube locations shown in figure 11;

FIG. 14 illustrates a trajectory of the refrigerant after it exits the shower tube illustrated in FIG. 13;

fig. 15 shows the flow rate of the refrigerant flowing through different positions in the width direction of the perforated plate shown in fig. 14.

Detailed Description

Various embodiments of the present application will now be described with reference to the accompanying drawings, which form a part hereof. It should be understood that although directional terms, such as "front," "rear," "upper," "lower," "left," "right," "top," "bottom," and the like may be used herein to describe various example structural portions and elements of the application, these terms are used herein for convenience of description only and are to be determined based on the example orientations shown in the figures. Because the embodiments disclosed herein can be arranged in a variety of orientations, these directional terms are used for purposes of illustration only and are not to be construed as limiting.

Fig. 1 shows a perspective view of a falling film evaporator 100 according to an embodiment of the present application. As shown in fig. 1, the falling film evaporator 100 includes a shell 101, a liquid inlet tube 102, a suction tube 104, and a tube sheet 103. The casing 101 is substantially cylindrical, and the tube plates 103 are provided at both ends of the casing 101 in the longitudinal direction. An inlet pipe 102 is provided at an upper portion of the case 101 for guiding the refrigerant into the inside of the case 101. A suction pipe 104 is also provided at an upper portion of the casing 101 for discharging gaseous refrigerant from the casing 101.

Fig. 2 is a schematic structural view of a part of components inside a shell 101 of the falling film evaporator 100 shown in fig. 1, wherein a liquid inlet pipe 102 outside the shell 101 is retained in fig. 2 for convenience of illustration. As shown in fig. 2, the falling film evaporator 100 further comprises a shower tube 202, a perforated plate 205, and a heat exchange tube bundle 201 (shown in fig. 3) disposed within the cavity of the shell 101. Shower 202 is disposed below inlet tube 102, perforated plate 205 is disposed below shower 202, and heat exchange tube bundle 201 is disposed below perforated plate 205. The shower 202 is generally tubular in shape with both ends closed. The top of the shower 202 is provided with an inlet 206 for fluid communication with the inlet pipe 102. The bottom of the shower pipe 202 is provided with a plurality of shower ports 301 (shown in fig. 3) for spraying the refrigerant entering the shower pipe 202 onto the perforated plate 205 below the shower pipe 202. The perforated plate 205 has a substantially elongated shape, and the longitudinal direction thereof coincides with the longitudinal direction of the casing 101. Perforated plate 205 is provided with a plurality of distribution holes 305 for redistributing the refrigerant sprayed onto perforated plate 205 so that the refrigerant can be evenly distributed to heat exchange tube bundle 201 below perforated plate 205. Side dams 204 are also provided on opposite left and right sides of the perforated plate 205. In the embodiment shown in fig. 2, the distribution holes 305 in the perforated plate 205 are all circular. In other embodiments, the dispensing aperture 305 can be other shapes, such as oval, square, diamond, etc. The longitudinal direction of the shower pipe 202 is substantially perpendicular to the longitudinal direction of the porous plate 205. The length direction of the shower pipe 202 is generally perpendicular to the length direction of the perforated plate 205, but the positional relationship between the two is not limited to a certain range. The shower pipes 202 are disposed above the middle position in the longitudinal direction of the porous plate 205 so that the refrigerant sprayed from the shower pipes 202 can be uniformly sprayed to both sides of the middle position of the porous plate 205.

The falling film evaporator 100 further comprises a liquid inlet box 203 arranged between the shower pipe 202 and the liquid inlet pipe 102 and a cover plate 302 arranged at the upper part of the shower pipe 202. The inlet box 203 extends the length of the shower 202 for fluidly communicating the inlet tube 102 with the inlet 206 of the shower 202 to enable initial distribution of refrigerant along the length of the shower 202. The cover plate 302 extends along the length of the perforated plate 205, and the two sides of the cover plate 302 extend downward, so that the cover plate 302 has an inverted "U" shape. The shower openings 301 of the shower pipes 202 are located in the cavity between the cover plate 302 and the porous plate 205, thereby ensuring that the refrigerant sprayed from the shower openings 301 can flow entirely to the porous plate 205.

Fig. 3 is a radial cross-sectional view of the falling film evaporator 100 shown in fig. 1 at the location of the liquid inlet tube 102. As shown in fig. 3, two bundles of heat exchange tubes 201 are accommodated in the shell 101, wherein one bundle of heat exchange tubes 201 is arranged in the accommodating space formed by the perforated plate 205 and the side baffle 204, and the other bundle of heat exchange tubes 201 is arranged at the bottom of the accommodating cavity of the shell 101.

Fig. 4 is an enlarged partial view of the falling film evaporator 100 shown in fig. 3 in the region of the shower pipe 202. As shown in fig. 4, a plurality of shower ports 301 are arranged at intervals along the length direction of the shower pipe 202 at the bottom of the shower pipe 202. The sealed connection of cover plate 302 and side dams 204 ensures that all of the refrigerant sprayed from spray openings 301 flows to perforated plates 205 and is distributed through distribution holes 305 in the perforated plates to heat exchange tube bundle 201. In other embodiments, the cover plate 302 may be directly and hermetically connected to the opposite left and right sides of the porous plate 205, and this configuration may also ensure that all of the refrigerant sprayed from the spray opening 301 flows to the porous plate 205.

Fig. 5 illustrates a perspective view of the shower pipe 202 shown in fig. 2. As shown in fig. 5, the bottom of the shower pipe 202 is provided with a plurality of shower ports 301. Each spray opening 301 is strip-shaped and extends from the bottom of the spray pipe 202 to the two side walls, and the opening extending direction of the spray opening 301 enables the plane where each spray opening 301 is located to be perpendicular to the length direction of the spray pipe 202. The plurality of shower ports 301 are arranged in parallel with each other and at intervals along the length direction of the shower pipe 202.

Fig. 6 shows a cross-section of the shower pipe 202 shown in fig. 5 at the location of the shower opening 301. As shown in fig. 6, the cross-section of the shower pipe 202 has an upper portion with a substantially rectangular shape and a lower portion with a substantially semicircular arc shape, and the shower port 301 is located at the semicircular arc position of the bottom of the shower pipe 202 and is shown by a blank portion of the lower portion of the shower pipe in fig. 6. When the refrigerant is jetted from the shower port 301 of the shower pipe 202, the refrigerant is uniformly dispersed outward in the opening direction of the shower port 301. The refrigerant sprayed from the shower port 301 has a certain flow velocity, and since the shower port 301 has a long and thin strip shape, the sprayed refrigerant is hardly scattered in the length direction of the shower pipe 202, and most of the refrigerant is sprayed only in the width direction of the shower pipe 202.

Fig. 7 shows an axial sectional view of the housing 101 of the falling film evaporator 100 at the location of the liquid inlet pipe 102, wherein the arrows indicate the movement trajectory of the refrigerant after it has been sprayed out of the shower pipe 202. As shown in fig. 7, the cover plate 302, the perforated plate 205, and the side baffle 204 have the same length as the shell 101, and have substantially the same length, and their ends extend to the tube plate 103. The refrigerant jetted from the shower pipe 202 is jetted into the lower region of the shower port 301 until it is jetted onto the porous plate 205, under the influence of the opening shape of the shower port 301 and the pressure difference between the inside and the outside of the shower pipe 202. Since the initial velocity of the refrigerant sprayed from the spray openings 301 is high, the refrigerant still has a high velocity after being sprayed to the porous plate 205, and therefore the refrigerant still flows toward both ends of the porous plate 205 along the length direction of the porous plate 205. Since the length of the perforated plate 205 is sufficient, the velocity of the refrigerant is reduced with the continuous flow, and when the refrigerant moves to a position close to the tube plates 103 on both sides, the velocity of the refrigerant is already small and will not form a vortex at the tube plates 103 on both sides, thereby realizing the uniform distribution of the refrigerant on the surface of the perforated plate. During the movement of the refrigerant along the length direction of the perforated plate 205, the refrigerant can flow from the distribution holes 305 on the perforated plate 205 to the heat exchange tube bundle 201 below the perforated plate 205, so that the refrigerant is uniformly distributed to the heat exchange tubes 304.

Fig. 8A and 8B show cross-sections of two further embodiments of the shower 202 in the position of the shower opening, respectively. In both embodiments, the cross-sectional shape of the shower 202 is different from the cross-sectional shape of the shower 202 shown in FIG. 6. The shower pipe 202 shown in fig. 6 is generally vertically long in cross section, and has a narrow lateral width, which is represented by a rectangular upper portion and a semicircular lower portion. However, when the lateral width of the cross section of the shower pipe 202 is narrow, the movement distance of the refrigerant in the length direction of the porous plate 205 is limited, and therefore, in order to enable the refrigerant jetted from the shower pipe 202 to move smoothly to a position close to the tube plate 103, the present application in some embodiments extends the shower pipe 202 out of two extension portions 801 in the width direction of the shower pipe 202 (i.e., in the length direction of the housing 101), and the shower port is at least partially provided on the extension portions, thereby facilitating to increase the shower distance of the refrigerant in the length direction of the housing 101.

As shown in fig. 8A, the cross section of the shower pipe 202 has a flat oval shape, the edges of the upper and lower sides are straight, two extending portions 801 are respectively located at the left and right sides of the shower pipe 202, and the end of each extending portion 801 has an outward convex arc end surface 501, so that the cross section of the shower pipe 202 has a longer transverse span. Fig. 8A shows the positions of the shower outlets 301 in the blank part of the cross section of the shower pipe, and the shower outlets 301 are in the shape of a strip and located in the lower half of the shower pipe 202 and extend from the bottom of the shower pipe 202 to the arc end surfaces 501 on both sides.

The shower pipe 202 shown in fig. 8B has an inverted "Y" shape in cross section, and two extending portions 801 are respectively provided on both sides of the bottom of the shower pipe 202 and extend obliquely downward, so that an angle a is formed between the two extending portions 801. In some embodiments, the angle a is greater than or equal to 60 ° to allow for a greater extension of the lateral width of the shower 202. As can be seen from fig. 8B, the end of each extension 801 has an outwardly convex circular arc end surface 501, and the shower outlets 301 are located approximately on both circular arc end surfaces 501. Fig. 8B shows two shower ports 301 located on the same cross-section of the shower pipe 202. In the length direction of the shower pipes 202, a row of shower openings 301 is arranged on the arc end surface 501 of each side at intervals, so that two rows of shower openings 301 are arranged on a single shower pipe 202 shown in fig. 8B, and the spraying distance of the refrigerant in the length direction of the porous plate 205 is greatly increased.

Fig. 9 shows an axial sectional view of a falling film evaporator with two shower pipes 202 at the location of the liquid inlet pipe 102. As shown in fig. 9, in order to accommodate the longer length of the housing 101 and to increase the spraying distance of the spraying pipes 202 in the longitudinal direction of the housing 101, the embodiment shown in fig. 9 employs two spraying pipes 202 arranged side by side inside the evaporator housing 101. The cross section of the shower pipes 202 can be any one of the shapes shown in fig. 6, fig. 8A and fig. 8B, and a liquid inlet box 203 is arranged above each shower pipe 202, so that the refrigerant can be primarily distributed along the length direction of the shower pipes 202 before entering the shower pipes 202. In order to facilitate the uniform distribution of the refrigerant, the liquid inlet pipe 102 is disposed at the middle position of the housing 101 in the axial direction, and the two shower pipes 202 are disposed in parallel at the same height above the porous plate 205 and symmetrically disposed at the left and right sides of the liquid inlet pipe 102. As shown in fig. 9, the distance between the central axis of any one of the two shower pipes 202 in the vertical direction and the central axis of the liquid inlet pipe 102 is L, and the distance between the central axis of any one of the two shower pipes 202 in the vertical direction and the tube plate 103 on the corresponding side thereof is L. The above-described symmetrical structural arrangement of the shower pipes 202 facilitates uniform spraying of the refrigerant to the surface of the perforated plate 205.

To satisfy the above arrangement of the shower pipes 202, the liquid inlet pipe 102 of the embodiment shown in fig. 9 is arranged: one end of the liquid inlet pipe 102 adjacent to the refrigerant inlet is vertically extended, before extending into the shell 101, the liquid inlet pipe 102 is branched into two branch pipes, the two branch pipes respectively horizontally extend towards two sides of the length direction of the shell 101, and the two branch pipes respectively form vertical corners above the position where the two spray pipes 202 are located so as to vertically extend downwards, so that the two branch pipes respectively connect two liquid inlet boxes 203 arranged above the two spray pipes 202 in a container of the shell 101. With the above arrangement, the refrigerant is branched into two paths after entering the liquid inlet pipe 102, and flows into two different shower pipes 202, respectively.

In some embodiments, the number of showers 202 can be set to an even number greater than two to accommodate falling film evaporators with longer length shells. The even number of the showers 202 is advantageous for the uniform distribution on both sides of the liquid inlet pipe 102, so that the refrigerant flowing through the liquid inlet pipe 102 is uniformly distributed to the showers 202.

Fig. 10A to 10D each show a further embodiment of the simultaneous arrangement of two shower pipes 202 in a falling film evaporator.

As shown in fig. 10A, two shower pipes 202 are arranged side by side at the same height, and share one liquid inlet box 203. The liquid inlet box 203 has a wide cross section so that both side portions in the width direction of the liquid inlet box 203 are connected to the top ends of the two shower pipes 202, respectively. The arrangement adopts a straight-through liquid inlet pipe 102 to be simultaneously in fluid communication with the two spray pipes 202 through the common liquid inlet box 203, so that only one opening is needed to be arranged on the shell 101 for the liquid inlet pipe 102 to pass through, and the structures of the liquid inlet pipe 102 and the shell 101 are simplified.

FIG. 10B illustrates another embodiment of a dual shower arrangement. As shown in fig. 10B, the two showers 202 are disposed in parallel at the same height, and each shower 202 has a substantially circular cross-section, which is designed to facilitate uniform scattering of the refrigerant along the direction of the shower opening.

Fig. 10C and 10D each show a configuration in which two shower tubes 202 are arranged at an angle within the falling film evaporator. As shown in fig. 10C and 10D, in the same cross section of the falling film evaporator, the central axes of the two shower pipes 202 form an angle B of 60 ° or more. The above-described arrangement of the angle B is advantageous for increasing the lengthwise spraying distance of the spray pipe 202 in the falling film evaporator shell. In order to enable the central axes of the two spray pipes 202 to be arranged at a certain angle B on the same section of the falling film evaporator, the liquid inlet pipe 102 is arranged to extend one end of the liquid inlet pipe vertically downwards, and is branched into two branch pipes before the spray pipes 202 are communicated, so that the two branch pipes horizontally extend in opposite directions respectively, and above the two spray pipes 202, the two branch pipes form corners which are obtuse angles respectively, so that the two branch pipes extend towards the oblique lower parts far away from each other respectively until the two spray pipes 202 are introduced respectively.

The length direction of the spray pipes 202 is perpendicular to the length direction of the shell 101 of the falling film evaporator 100, and the spray openings 301 are in a strip shape, so that the refrigerant sprayed out of the spray pipes 202 can flow in the length direction of the shell 101 approximately, the movement space of the refrigerant is increased, and the refrigerant can be uniformly sprayed onto the surface of the porous plate 205. Without the arrangement of the spray tubes 202 of the present application, the path of the refrigerant exiting the spray tubes 202 may be limited due to insufficient radial width of the shell 101, resulting in uneven spraying of the refrigerant onto the heat exchange tube bundle 201.

Fig. 11 shows a comparative example of the positional arrangement of the shower pipe 1202 inside the falling film evaporator. Unlike the embodiment of the present application in which the lengthwise direction of the shower pipes 202 is arranged perpendicular to the lengthwise direction of the porous plate 205, the comparative example shown in fig. 11 arranges the lengthwise direction of the shower pipes 1202 to coincide with the lengthwise direction of the porous plate 1205. As shown in fig. 11, the length of the shower pipe 1202 is substantially the same as the length of the cover plate 1302, the perforated plate 1205 and the side baffle 1204, and the shower pipe 1202 is disposed above the perforated plate 1205, so that the refrigerant can enter the liquid inlet box 1203 from the liquid inlet pipe 1102 and then be sprayed onto the surface of the perforated plate 1205 through the shower pipe 1202. In the comparative example, the arrangement of the spray openings 1301 on the spray pipe 1202 is the same as the arrangement of the spray openings 301 shown in fig. 5 in the embodiment of the present application, and the spray openings 1301 are parallel to each other and are equidistantly arranged along the length direction of the spray pipe 1202. In contrast, in this comparative example, the shower pipe 1202 is provided in the longitudinal direction along the longitudinal direction of the porous plate 1205, and the shower port 1301 is provided so that the refrigerant is discharged from the shower pipe 1202 and then moves substantially in the width direction of the porous plate 1205.

Fig. 12 shows an axial cross-sectional view of a falling film evaporator at the location of the liquid inlet pipe 1102 with the arrangement of shower pipe 1202 locations shown in fig. 11. As shown in fig. 12, the liquid inlet box 1203, the shower pipe 1202, the cover plate 1302, the perforated plate 1205 and the side baffle 1204 are all disposed inside the housing 1101 of the falling film evaporator, and the lengths of the shower pipe 1202, the cover plate 1302, the perforated plate 1205 and the side baffle 1204 are substantially the same as the length of the housing 1101.

Fig. 13 shows a radial cross-sectional view of a falling film evaporator at the location of the liquid inlet pipe 1102 with the arrangement of shower pipe 1202 locations shown in fig. 11. As shown in fig. 13, the left and right sides of the falling film evaporator are symmetrically arranged, wherein the shower pipe 1202 is located in the middle position of the perforated plate 1205 in the width direction, two bundles of heat exchange tubes 1201 are arranged below the perforated plate 1205, one bundle of heat exchange tubes 1201 is accommodated in the accommodating space formed by the perforated plate 1205 and the side baffles 1204 at the two sides of the perforated plate, the other bundle of heat exchange tubes 1201 is arranged in the bottom space of the shell 1101, and the length direction of each heat exchange tube in the two bundles of heat exchange tubes 1201 is arranged along the length direction of the shell 1101.

Fig. 14 shows a movement locus of the refrigerant after being sprayed from the shower pipe 1202 shown in fig. 13. As shown in fig. 14, the initial velocity of the refrigerant jetted from the shower pipe 1202 is large, and the refrigerant still has a certain lateral velocity when it advances to the edge along the width direction of the porous plate 1205, but since the moving path of the refrigerant is substantially along the radial direction of the housing 1101, and the radial width of the housing 1101 is narrow, the width of the porous plate 1205 is limited, and therefore, the porous plate 1205 does not have a sufficient width for the refrigerant to further advance, and the refrigerant having a certain lateral velocity swirls at the edge of the porous plate 1205 due to being blocked by the cover plate 1302, thereby causing more refrigerant to be collected at both sides of the porous plate 1205 in the width direction than at the middle position.

Fig. 15 shows the refrigerant flow rates distributed at different positions in the width direction of the perforated plate 1205 shown in fig. 14. When the length direction of the shower pipe 1202 coincides with the length direction of the housing 1101, since the radial width of the housing 1101 is narrow, so that the width of the porous plate 1205 is limited, the refrigerant jetted from the shower pipe 1202 has a large lateral velocity when reaching the width edge of the porous plate 1205, and thus the movement is limited, resulting in uneven distribution of the refrigerant in the width direction of the porous plate 1205. As described in fig. 15, since each component in the falling film evaporator is symmetrically arranged on the left and right sides in the radial direction thereof, the refrigerant flow rate is also symmetrical with respect to the midpoint position thereof in the width direction of the perforated plate 1205. Specifically, the refrigerant flow rate is smallest at the intermediate position directly below the shower pipe 1202, and when the position is shifted toward both sides in the width direction of the porous plate 1205, the refrigerant flow rate gradually increases, and the refrigerant flow rate is largest at both edge positions of the porous plate 1205.

It can be seen that the falling film evaporator of the comparative example has the length direction of the shower pipe 1202 arranged along the length direction of the housing 1101, so that the refrigerant sprayed from the shower pipe 1202 moves substantially along the radial width direction of the housing 1101, and the radial width of the housing 1101 is narrow, so that the movement range of the refrigerant sprayed from the shower pipe 1202 is greatly limited, and the refrigerant cannot be uniformly sprayed onto the heat exchange tubes. The falling film evaporator 100 of the application sets the length direction of the heat exchange tube 202 to be vertical to the length direction of the shell 101, so that the refrigerant sprayed out of the spray tube 202 can move along the length direction of the shell 101 approximately, the movement path of the refrigerant is increased, uneven spraying of the heat exchange tube caused by limited movement of the refrigerant is prevented, and the phenomenon of 'dry spots' of the heat exchange tube caused by uneven spraying of the refrigerant is avoided. In addition, because the above-mentioned setting of this application has increased the motion route of refrigerant in shower 202 width direction both sides, that is to say, adopt the shower 202 setting mode of this application embodiment greatly increased the shower 202 of unit length to the spray coverage area of perforated plate 205, consequently, in order to satisfy the spraying effect of the perforated plate of the same area, adopt the shower 202 setting mode of this application embodiment greatly reduced the length of shower 202, correspondingly, above-mentioned setting has also reduced the opening quantity of shower 301 on shower 202, thereby obviously reduced the manufacturing degree of difficulty and the cost of shower.

Although the present application will be described with reference to the particular embodiments shown in the drawings, it should be understood that many variations of the falling film evaporator of the present application are possible without departing from the spirit and scope and background of the teachings of the present application. Those of ordinary skill in the art will also realize that there are different ways of varying the details of the structures in the embodiments disclosed herein that fall within the spirit and scope of the present description and claims.

Claims

1. A falling film evaporator, characterized in that: the falling film evaporator (100) comprises:

a housing (101), the housing (101) having a cavity;

the length direction of the heat exchange pipe (304) is consistent with the length direction of the shell (101);

a perforated plate (205), wherein the perforated plate (205) is arranged above the heat exchange pipe (304), and a plurality of distribution holes (305) are arranged on the perforated plate (205);

the spray pipe (202), the spray pipe (202) is set up above the said perforated plate (205), there are several spray mouths (301) on the said spray pipe (202), the said spray mouth (301) is distributed along the length direction of the said spray pipe (202) at intervals, and the said spray mouth (301) is set up to be able to spray the refrigerant to the said perforated plate (205); and

a liquid inlet pipe (102), the liquid inlet pipe (102) being in fluid communication with the shower pipe (202) such that refrigerant flowing through the liquid inlet pipe (102) can flow into the shower pipe (202);

wherein the heat exchange pipe (304), the porous plate (205) and the spray pipe (202) are all arranged in the cavity; the length direction of the shower pipe (202) is approximately perpendicular to the length direction of the shell (101).

2. The falling film evaporator according to claim 1, characterized in that:

the length direction of the porous plate (205) is consistent with the length direction of the shell (101), and the spraying openings (301) are arranged to enable the refrigerant to flow along the length direction of the porous plate (205) after the refrigerant is sprayed to the porous plate (205).

3. The falling film evaporator according to claim 1, characterized in that:

the bottom of shower (202) has circular arc terminal surface (501), circular arc terminal surface (501) are protruding towards the direction of perforated plate (205), spray mouth (301) are the bar, just at least partly setting of spray mouth (301) is in on the circular arc terminal surface (501).

4. The falling film evaporator according to claim 1, characterized in that:

the spray pipe (202) is provided with two extending parts (801) extending along the length direction of the shell (101), the end parts of the extending parts (801) comprise convex arc end surfaces (501), the spray openings (301) are strip-shaped, and at least one part of the spray openings (301) is arranged on the arc end surfaces (501).

5. The falling film evaporator according to claim 4, characterized in that:

the cross section of the spray pipe (202) is in a flat oval shape, the two extending parts (801) are respectively located at the left end and the right end of the spray pipe (202), the spray opening (301) is in a strip shape, and the spray opening (301) extends from the bottom of the spray pipe (202) to the arc end faces (501) at the left end and the right end of the spray pipe (202) respectively.

6. The falling film evaporator according to claim 4, characterized in that:

the cross section of the spray pipe (202) is inverted Y-shaped, the two extending parts (801) are respectively located at the bottom of the spray pipe (202) and extend towards the oblique lower direction, the spray opening (301) is strip-shaped, and at least one part of the spray opening (301) is arranged on the arc end surface (501).

7. The falling film evaporator according to claim 1, characterized in that:

a plurality of spray pipes (202) are arranged in the falling film evaporator (100), and the top ends of the plurality of spray pipes (202) are communicated with each other, so that the plurality of spray pipes (202) are communicated with each other in a fluid mode.

8. The falling film evaporator according to claim 7, characterized in that:

the number of the spray pipes (202) is even, and the plurality of spray pipes (202) are symmetrically distributed relative to the liquid inlet pipe (102).

9. The falling film evaporator according to claim 1, characterized in that:

the falling film evaporator (100) further comprises a liquid inlet box (203), the liquid inlet box (203) is arranged between the liquid inlet pipe (102) and the spray pipe (202), so that the liquid inlet pipe (102) and the spray pipe (202) can be in fluid communication through the liquid inlet box (203).

10. The falling film evaporator according to claim 1, characterized in that:

falling film evaporator (100) still includes apron (302), apron (302) set up the upper portion of shower (202), the both sides limit of apron (302) towards perforated plate (205) extend and through direct or indirect mode of connecting with the both sides limit sealing connection of perforated plate (205).