WO2023036004A1

WO2023036004A1 - Evaporator and refrigeration system comprising same

Info

Publication number: WO2023036004A1
Application number: PCT/CN2022/115500
Authority: WO
Inventors: 苏秀平
Original assignee: 约克（无锡）空调冷冻设备有限公司; 江森自控泰科知识产权控股有限责任合伙公司
Priority date: 2021-09-08
Filing date: 2022-08-29
Publication date: 2023-03-16
Also published as: CN115773597A; TW202314173A; KR20240063935A; EP4400783A1

Abstract

An evaporator (100), comprising: a housing (203), the housing (203) being provided with an accommodating cavity (310), and the accommodating cavity (310) having a length direction (L), a width direction (W), and a height direction (H); and falling film tube bundles (315) disposed in the accommodating cavity (310) and arranged in columns, each falling film tube bundle (315) comprising a plurality of heat exchange tubes (320), the centers of the heat exchange tubes (320) in each column being arranged along the height direction (H), and the centers of two adjacent heat exchange tubes (320) in adjacent columns being staggered in the width direction (W) of the accommodating cavity (310); wherein the falling film tube bundles (315) are configured such that, among four adjacent heat exchange tubes (320) in two adjacent columns, the minimum distance between the outer surfaces of at least two heat exchange tubes (320) in different columns is greater than the minimum distance between the outer surfaces of two heat exchange tubes (320) in the same column.

Description

Evaporator and refrigeration system including same

technical field

The present application relates to an evaporator, in particular to an evaporator with high heat exchange efficiency and a refrigeration system including the same.

Background technique

A traditional refrigeration system has an evaporator, condenser, throttling device and compressor. When the low-temperature refrigerant liquid passes through the evaporator, it exchanges heat with the external working fluid and absorbs the heat of the working fluid, thereby reducing the temperature of the working fluid and achieving the cooling effect. The working fluid can be air or cooling water. After heat exchange, the refrigerant liquid is vaporized into a gaseous refrigerant and enters the compressor. The heat exchange efficiency of the evaporator is affected by many factors.

Contents of the invention

At least one object of the first aspect of the present application is to provide an evaporator with high heat exchange efficiency. The evaporator includes: a housing, the housing has a cavity, and the cavity has a length direction, a width direction and a height direction; falling film tube bundles, the falling film tube bundles are arranged in the cavity and arranged in a row, The falling film tube bundle includes several heat exchange tubes, each heat exchange tube extends along the length direction of the cavity, and the centers of the heat exchange tubes in each row are arranged along the height direction and adjacent to each other The centers of the adjacent two heat exchange tubes in the columns are arranged staggered in the width direction of the cavity; wherein, the falling film tube bundles are configured such that the adjacent four tubes in the adjacent two columns In the heat exchange tubes, the minimum distance between the outer surfaces of at least two heat exchange tubes in different rows is greater than the minimum distance between the outer surfaces of two heat exchange tubes in the same row.

According to the above first aspect, among the four adjacent heat exchange tubes in two adjacent columns, the distance between the outer surfaces of at least two different columns of the heat exchange tubes is set so that the flow through adjacent The gas flow velocity of the two rows of heat exchange tubes is reduced, thereby improving the heat exchange efficiency of the evaporator.

According to the first aspect above, each heat exchange tube in the falling film tube bundle has the same tube diameter, and the center of the two adjacent heat exchange tubes in adjacent rows in the width direction of the cavity The ratio of the spacing between the heat exchange tubes in each column to the center spacing of two adjacent heat exchange tubes in the height direction of the cavity satisfies

According to the first aspect above, the falling film tube bundle includes several first heat exchange tubes with larger diameters and several second heat exchange tubes with smaller diameters; on the row of the falling film tube bundles, The first heat exchange tubes and the second heat exchange tubes are arranged alternately.

According to the first aspect above, the falling film tube bundle includes several first heat exchange tubes with relatively large diameters and several second heat exchange tubes with relatively small diameters, and the several first heat exchange tubes form a Arranged in a row, several of the second heat exchange tubes are arranged in a row; wherein, the rows of the first heat exchange tubes and the rows of the second heat exchange tubes are arranged in a staggered manner.

According to the first aspect above, the distance between the centers of the adjacent first heat exchange tubes and the second heat exchange tubes in the width direction of the cavity in two adjacent rows of heat exchange tubes is not less than The larger diameter of the first heat exchange tube.

According to the first aspect above, the larger diameter of the first heat exchange tube is 25.4 mm; and the smaller diameter of the second heat exchange tube is 19.05 mm.

According to the first aspect above, the evaporator further includes: a first baffle and a second baffle, the first baffle and the second baffle are respectively arranged at the ends of the falling film tube bundle in the chamber. The outer side in the width direction; wherein, the first baffle and the second baffle are respectively provided with several windows, the several windows are arranged along the length direction of the cavity, and the several windows are in the In the height direction of the cavity, it is arranged outside the middle part of the falling film tube bundle.

According to the above-mentioned first aspect, a liquid baffle extending along the length direction of the cavity is respectively provided on the outside of the window on the first baffle and the second baffle, wherein the top of the liquid baffle connected to the respective first and second baffles, and the liquid baffles are spaced a distance from the window.

At least one object of the present application in the second aspect is to provide a refrigeration system, including: a compressor, a condenser, a throttling device and an evaporator arranged in the refrigerant circuit, wherein the evaporator is any of the first aspects one item.

Description of drawings

Figure 1 is a schematic block diagram of a refrigeration system;

Fig. 2 is a perspective view of the evaporator in Fig. 1;

Figure 3A is a radial cross-sectional view of one embodiment of the evaporator of Figure 2;

Fig. 3B is a partial enlarged view of four adjacent heat exchange tubes in the falling film tube bundle in Fig. 3A;

Fig. 3C is a comparison diagram of the theoretical value of the heat transfer coefficient of a single heat exchange tube in the falling film tube bundle of the evaporator of the embodiment shown in Fig. 3A and the falling film tube bundle in an ideal state;

Figure 4A is a radial cross-sectional view of another embodiment of the evaporator in Figure 2;

Fig. 4B is a partially enlarged view of four adjacent heat exchange tubes in the falling film tube bundle in Fig. 4A;

Fig. 4C is a comparison diagram of the theoretical value of the heat transfer coefficient of a single heat exchange tube in the falling film tube bundle of the evaporator of the embodiment shown in Fig. 4A and the falling film tube bundle in an ideal state;

Figure 5A is a radial cross-sectional view of yet another embodiment of the evaporator in Figure 2;

Fig. 5B is a partially enlarged view of four adjacent heat exchange tubes in the falling film tube bundle in Fig. 5A;

Fig. 5C is a comparison diagram of the theoretical value of the heat transfer coefficient of a single heat exchange tube in the falling film tube bundle of the evaporator of the embodiment shown in Fig. 5A and the falling film tube bundle in an ideal state;

Figure 6A is a radial cross-sectional view of yet another embodiment of the evaporator in Figure 2;

Fig. 6B is a schematic structural view of the first baffle in Fig. 6A;

Fig. 6C is a comparison chart of the theoretical value of the heat transfer coefficient of a single heat exchange tube in the falling film tube bundle of the evaporator shown in Fig. 6A and the falling film tube bundle in an ideal state.

Detailed ways

Various embodiments of the present application will be described below with reference to the accompanying drawings, which form a part hereof. It should be understood that although directional terms are used in this application, such as "front", "rear", "upper", "lower", "left", "right", "inner", "outer", " "Top", "bottom", "front", "reverse", "proximal", "distal", "transverse", "longitudinal", etc. describe various example structural parts and elements of the application, but these are used herein The terminology is for convenience of description only and is based on the exemplary orientations shown in the drawings. Since the embodiments disclosed in this application can be arranged in different orientations, these directional terms are for illustration only and should not be regarded as limiting.

Ordinal numerals such as "first" and "second" used in this application are only used for distinction and identification, and do not have any other meanings. If not specified, they do not indicate a specific order, nor do they have a specific association sex. For example, the term "first element" by itself does not imply the presence of a "second element", nor does the term "second element" itself imply the existence of a "first element".

FIG. 1 is a schematic block diagram of a refrigeration system 190 . As shown in FIG. 1 , the refrigeration system 190 includes a compressor 193 , a condenser 191 , a throttling device 192 and an evaporator 100 , which are connected by pipes to form a refrigerant circulation loop, and the loop is filled with refrigerant. As shown by the arrow direction in FIG. 1 , the refrigerant flows through the compressor 193 , the condenser 191 , the throttling device 192 and the evaporator 100 in sequence, and enters the compressor 193 again. During the refrigeration process, the throttling device 192 throttles the high-pressure liquid refrigerant from the condenser 191 to reduce its pressure; the low-pressure refrigerant exchanges heat with the object to be cooled in the evaporator 100, absorbs the heat of the object to be cooled and Vaporization; the refrigerant vapor generated by vaporization is sucked by the compressor 193, and discharged in a high-pressure gas state after being compressed; the high-temperature and high-pressure gas refrigerant discharged from the compressor 193 performs heat exchange with the ambient medium in the condenser 191, releases heat and condenses into Liquid refrigerant: the high-pressure liquid refrigerant flows through the throttling device 192 again to reduce the pressure. Repeatedly, a continuous cooling effect is produced.

Fig. 2 is a perspective view of the evaporator 100 in Fig. 1, as shown in Fig. 2, the evaporator 100 has a shell 203, the shell 203 includes a cylindrical main body 204 and a pair of tube sheets 205, the cylindrical main body 204 is two A cylindrical shape with an open end, a pair of tube plates 205 are placed at both ends of the cylindrical main body 204 to seal the openings at both ends of the cylindrical main body 204 . The cylindrical main body 204 and a pair of tube plates 205 enclose a cavity 310 (see FIG. 3A ), which is used for accommodating heat exchange tubes. A water inlet pipe 208 and a water outlet pipe 207 are connected to the tube plate 205 . Referring to the position shown in FIG. 2 , the evaporator 100 has a height direction H, a length direction L and a width direction W, and the height direction, length direction and width direction of the cavity 310 are consistent with the direction of the evaporator 100 . The cylindrical main body 204 is provided with a refrigerant inlet 101 and a refrigerant outlet 102, wherein the refrigerant inlet 101 and the refrigerant outlet 102 are located at the upper part of the evaporator 100 in the height direction H, and on the cylindrical main body 204 Staggered in the length direction and/or radial direction. The liquid refrigerant or gas-liquid mixed refrigerant in the refrigeration system 190 enters the evaporator 130 from the refrigerant inlet 101 , absorbs heat in the evaporator 130 and becomes a gaseous refrigerant, and is discharged from the refrigerant outlet 102 .

3A-3C show a first embodiment of the evaporator of the present application. Fig. 3A is a radial cross-sectional schematic view of the first embodiment of the evaporator in Fig. 2, Fig. 3B is a partially enlarged view of four adjacent heat exchange tubes in the falling film tube bundle of Fig. 3A, and Fig. 3C is a theoretical value of the heat transfer coefficient Comparison chart. As shown in FIG. 3A and FIG. 3B , a cavity 310 is formed inside the housing 203 , and a falling film tube bundle 315 , a flooded tube bundle 316 , a distribution device 340 and a demister 341 are arranged in the cavity 310 . As shown in FIG. 2 and FIG. 3A , the refrigerant inlet 101 is located in the middle of the evaporator 100 in the length direction and the width direction, so as to facilitate even distribution of the refrigerant. The refrigerant outlet 102 and the refrigerant inlet 101 are arranged staggered in the length direction and/or the radial direction. The distributing device 340 is arranged above the falling film tube bundle 315 and communicated with the refrigerant inlet 101 to evenly distribute the refrigerant received from the refrigerant inlet 101 from the throttling device 192 into the falling film tube bundle 315 . The demister 341 is connected below the refrigerant outlet 102, and the outlet of the gas obtained by evaporation of the falling film tube bundle 315 and the flooded tube bundle 316 is arranged below the demister 341, so that the demister 341 can block the gas obtained by evaporation Liquid droplets entrained in the refrigerant are discharged from the refrigerant outlet 102 .

The falling film tube bundle 315 is arranged roughly at the upper middle of the cavity 310 , and the flooded tube bundle 316 is set at the bottom of the cavity 310 , and there is a certain distance between the flooded tube bundle 316 and the bottom of the falling film tube bundle 315 . The falling film tube bundle 315 and the flooded tube bundle 316 are respectively heat exchange tube bundles formed by a plurality of heat exchange tubes 320 arranged in sequence. Each heat exchange tube 320 has the same tube diameter D ₀ , and each heat exchange tube 320 extends along the length direction L of the cavity 305 . As an example, the diameter D ₀ of the heat exchange tube 320 is 1 inch, that is, 25.4 mm. A fluid channel is formed inside each heat exchange tube for communicating with the water inlet pipe 208 and the water outlet pipe 207 to circulate water or other media. The gap between each heat exchange tube 320 and adjacent heat exchange tubes 320 forms a refrigerant channel for circulating the refrigerant. The medium in the fluid channel exchanges heat with the refrigerant in the refrigerant channel through the tube wall of the heat exchange tube.

The heat exchange tubes 320 in the falling film tube bundle 315 are arranged in rows, and adjacent rows are spaced at the same distance. And the centers of the heat exchange tubes 320 in each row are evenly arranged at intervals along the height direction H at the same pitch. In the width direction W, the centers of adjacent heat exchange tubes 320 in two adjacent rows of heat exchange tubes 320 are arranged staggered and have the same interval. That is to say, in the width direction W, the centers of two adjacent heat exchange tubes 320 are not on the same horizontal line, that is, they are not on the same height. In the height direction H, the centers of two adjacent heat exchange tubes 320 are on the same vertical line, that is, they are on the same width. The heat exchange tubes are arranged in this way because, in the process of falling film evaporation, the liquid refrigerant to be evaporated will flow from top to bottom, forming a liquid film on the outer surface of the tube wall of each heat exchange tube 320, and the heat exchange tubes The medium in 320 performs heat exchange. Arranging the heat exchange tubes 320 in a row, and arranging the adjacent heat exchange tubes 320 staggered in the width direction instead of side by side is to avoid the extension of the refrigerant channel formed between two adjacent rows of heat exchange tubes 320 The direction is inconsistent with the direction of gravity of the liquid refrigerant, which makes it difficult to form a liquid film on the heat exchange tubes in the lower row. However, the tube layout method of the present application is beneficial for the unevaporated liquid refrigerant to continue to flow to the outer surface of the heat exchange tube 320 below to form a liquid film, thereby improving the evaporation efficiency of each heat exchange tube.

The heat exchange tubes 320 in the flooded tube bundle 316 are also arranged in a row and cover the bottom of the cavity 310 . After the heat exchange by the falling film tube bundle 315 , some liquid refrigerant still cannot be completely evaporated into gas refrigerant, and this part of the liquid refrigerant will form a liquid surface at the bottom of the cavity 310 that is higher than the height of the flooded tube bundle 316 . The heat exchange tubes 320 in the flooded tube bundle 316 are used to be submerged in this part of liquid refrigerant to further evaporate the liquid refrigerant into gas refrigerant.

The evaporator 100 further includes a first baffle 331 and a second baffle 332 , the first baffle 331 and the second baffle 332 are respectively arranged outside the falling film tube bundle 315 in the width direction W and extend along the length direction L. The first baffle 331 and the second baffle 332 are used to guide the refrigerant to flow through the heat exchange tubes in the falling film tube bundle 315 from top to bottom, so as to prevent the liquid refrigerant from flowing to the outside of the falling film tube bundle 315 . The evaporated gas refrigerant flows along the first baffle plate 331 and the second baffle plate 332 , and is discharged from the bottom of the first baffle plate 331 and the second baffle plate 332 . That is to say, the outlet of the gas refrigerant evaporated from the falling film tube bundle 315 is located approximately at the bottom edges of the first baffle plate 331 and the second baffle plate 332 .

FIG. 3B shows an enlarged structure of four adjacent heat exchange tubes 320 a , 320 b , 320 c , and 320 d in two adjacent rows in the falling film tube bundle 315 in FIG. 3A . Those skilled in the art can understand that, because the heat exchange tubes 320 in the falling film tube bundle 315 are uniformly arranged, the four heat exchange tubes can be any four adjacent heat exchange tubes in two adjacent rows, They are adjacent in pairs, and the centers of the three adjacent heat exchange tubes form two acute triangle shapes. As shown in FIG. 3B , the heat exchange tubes 320 a and 320 b are in the same column, and the heat exchange tubes 320 c and 320 d are in the same column. And the heat exchange tube 320a, the heat exchange tube 320b and the heat exchange tube 320c are adjacent to each other, and their centers form an acute triangle shape. The heat exchange tube 320b, the heat exchange tube 320c, and the heat exchange tube 320d are adjacent to each other, and their centers form an acute triangle shape. In the height direction H, the centers of adjacent heat exchange tubes 320a and 320b in the same column have a distance H ₀ (hereinafter referred to as vertical distance). In the width direction W, the centers of adjacent heat exchange tubes 320a and 320c in different rows have a distance W ₀ (hereinafter referred to as horizontal distance). There is a minimum distance X ₀ between the outer surfaces of the heat exchange tube 320a and the heat exchange tube 320b. There is a minimum distance V ₀ between the outer surfaces of the heat exchange tube 320a and the heat exchange tube 320c. In this embodiment, V ₀ is greater than X ₀ . And H ₀ and W ₀ satisfy the relation:

In some existing falling film tube bundles, the centers of three adjacent heat exchange tubes among the heat exchange tubes arranged in a row are generally arranged in the shape of an equilateral triangle. These tubes will have a horizontal spacing approximately equal to D ₀ , and approximately

vertical spacing. That is to say, the ratio of the horizontal pitch to the vertical pitch of these heat exchange tubes is approximately cos30°.

In the falling film evaporator, the gas-liquid two-phase refrigerant entering the evaporator from the refrigerant inlet is distributed by the distribution device and evenly distributed to the surface of the heat exchange tubes at the top of the falling film tube bundle to form a liquid film for heat exchange. Part of the liquid refrigerant is converted into gas after evaporation and heat exchange, and the other part of the non-evaporated liquid refrigerant will drop onto the lower row of heat exchange tubes and continue to evaporate. It gradually decreases to the bottom, while the gas refrigerant flow rate increases gradually.

The applicant has found through research that the heat transfer coefficient "h _r " of each heat exchange tube in the falling film tube bundle can be fitted to the Gaussian distribution equation (1):

Among them, y0, A, w, xc are fitting constants, _Rev is the gas phase Reynolds number, and Re _film is the liquid film Reynolds number. From the Gaussian distribution equation (1), it can be seen that the heat transfer coefficient " _hr " decreases as the ratio of the gas phase Reynolds number _Rev to the liquid film Reynolds number Re _film increases. Among them, the gas-phase Reynolds number _Rev is proportional to the flow velocity between the gas refrigerant tubes, and the liquid film Reynolds number Re _film is also proportional to the flow rate of the liquid refrigerant. When the flow rate of the gas refrigerant is smaller, the gas phase Reynolds number _Rev is smaller, and the heat transfer coefficient " _hr " is larger. When the liquid refrigerant flow rate is larger, the liquid film Reynolds number Re _film is larger, and the heat transfer coefficient " _hr " is also larger.

The flow rate of the gas refrigerant is related to the flow rate of the gas refrigerant and the flow area of the gas refrigerant. Increasing the minimum spacing between the outer surfaces of the tube walls of the heat exchange tubes in different columns of the falling film tube bundle can reduce the flow of the gas refrigerant through the corresponding channel by increasing the space of the refrigerant channel in the width direction W The flow rate of the gas between the heat exchange tubes, thereby increasing the heat transfer coefficient "h _r ". However, when the horizontal spacing between heat exchange tubes increases, the number of heat exchange tubes that can be arranged in a falling film tube bundle will decrease in a cavity of a certain size, resulting in a decrease in the heat transfer capacity of the evaporator. Therefore, increasing the minimum distance between the outer surfaces of the tube walls of the heat exchange tubes of the falling film tube bundle within a certain range can improve the heat exchange efficiency of the evaporator, thereby increasing the heat exchange capacity of the evaporator. Or reduce the number of heat exchange tubes when the evaporator maintains the same heat exchange capacity.

In this embodiment, compared with the existing falling film tube bundle, the size of the evaporator is the same as that of the prior art, and the size of each heat exchange tube is also the same. In this embodiment, the minimum spacing between the outer surfaces of the tube walls of the heat exchange tubes in different rows is increased by maintaining the vertical spacing H ₀ between the centers of the heat exchange tubes and increasing the horizontal spacing W ₀ between the centers of the heat exchange tubes. Specifically, the falling film tube bundle 315 of the present application increases the ratio of the horizontal spacing W ₀ to the vertical spacing H ₀ to (1˜1.5)*cos30°. That is to say, the centers of the three adjacent heat exchange tubes of the falling film tube bundle 315 of the present application are no longer arranged in an equilateral triangle shape, but are arranged in an isosceles triangle shape with an apex angle less than 60°. An increased ratio of the horizontal spacing W ₀ to the vertical spacing H ₀ will reduce the flow velocity of the gas flowing through two adjacent rows of heat exchange tubes 320 , thereby improving the heat exchange efficiency of the evaporator 100 .

Fig. 3 C shows that under the situation of the same number of heat exchange tubes, the falling film tube bank 315 of the present embodiment, the existing falling film tube bank, the falling film tube bank under ideal conditions and the unit in the flooded tube bank under ideal conditions The comparison chart of the theoretical value of the heat transfer coefficient of the root heat exchange tube, the theoretical value is obtained by the Gaussian distribution equation (1). In FIG. 3C , the abscissa shows different rows of heat exchange tubes from top to bottom, and the ordinate shows the heat transfer coefficient. Wherein, the straight line 361 and the straight line 362 represent the heat transfer coefficient of a single heat exchange tube in the falling film tube bundle and the flooded tube bundle under ideal conditions respectively. Curve 360 and curve 370 represent the heat transfer coefficients of the existing falling film tube bundle and the falling film tube bundle 315 of this embodiment, respectively.

It can be seen from Fig. 3C that under ideal conditions, the heat transfer coefficient of the heat exchange tubes in the falling film tube bank and the flooded tube bank will not decrease with the increase of the number of rows. However, in the existing falling film tube bundles, the heat transfer coefficient decreases rapidly with the increase of the number of rows, and even in the heat exchange tubes with low rows at the bottom, the heat transfer efficiency will drop below that of the ideal case of flooded tube bundles. heat transfer coefficient. However, in the falling film tube bundle of this embodiment, the heat transfer coefficient is almost kept equivalent to the heat transfer coefficient of the falling film tube bundle in the ideal case. Even if the heat exchange tubes at the bottom are slightly lowered, it is much higher than the heat transfer coefficient of the ideal case of flooded tube bundles.

4A-4C show a second embodiment of the evaporator of the present application. Fig. 4A shows the radial sectional view of the second embodiment evaporator 400 of the evaporator in Fig. 2, Fig. 4B is a partial enlarged view of four adjacent heat exchange tubes in the falling film tube bundle of Fig. 4A, Fig. 4C is Comparison chart of theoretical values of thermal coefficients. As shown in Fig. 4A and Fig. 4B, same as the first embodiment, the evaporator 400 is also provided with a falling film tube bank 415 and a flooded tube bank 416, and the falling film tube bank 415 and the flooded tube bank 416 respectively include several forming Heat exchange tubes arranged in rows. The heat exchange tubes in the flooded tube bundle 416 and the arrangement of the heat exchange tubes are the same as those in the first embodiment. But the falling film tube bundle 415 is different from the first embodiment, the heat exchange tubes in the falling film tube bundle 415 no longer have the same pipe diameter, but include several first heat exchange tubes 421 with a larger pipe diameter _D1 and several The first heat exchange tubes 421 and the second heat exchange tubes 422 are alternately arranged on each row of the falling film tube bundle 415, starting from the second heat exchange tubes 422 with a smaller tube diameter _D2 . That is to say, for any four adjacent heat exchange tubes in two adjacent columns, there must be two first heat exchange tubes 421 with larger diameters and two second heat exchange tubes 421 with smaller diameters. Tube 422. As an example, the larger diameter D ₁ of the first heat exchange tube 421 is equal to the diameter D ₀ of the heat exchange tube 320 in the first embodiment. In this embodiment, the diameter _D1 of the first heat exchange tube 421 with a large diameter is 1 inch, that is, 25.4 millimeters, and the diameter _D2 of the second heat exchange tube 422 with a small diameter is 3/4 inch. That is 19.05 millimeters. In the falling film tube bundle 415 , the quantity ratio of the first heat exchange tubes 421 and the second heat exchange tubes 422 is approximately 1:1.

Fig. 4B shows the enlarged structure of four adjacent

heat exchange tubes

421a, 421b, 422a and 422b in two adjacent columns, these heat exchange tubes are adjacent to each other, and the center of the three adjacent heat exchange tubes forms Two equilateral triangles. As shown in FIG. 4B , the heat exchange tubes 421 a and the heat exchange tubes 422 a are in the same column, and the heat exchange tubes 422 b and the heat exchange tubes 421 b are in the same column. In addition, the heat exchange tube 421a, the heat exchange tube 422a and the heat exchange tube 422b are adjacent to each other, and the heat exchange tube 421b, the heat exchange tube 422a and the heat exchange tube 422b are adjacent to each other. In the height direction H, the centers of adjacent

heat exchange tubes

421a and 422a in the same column have a vertical distance H ₁ . In the width direction W, the centers of adjacent

heat exchange tubes

421 a and 422 b in different rows have a horizontal distance W ₁ . There is a minimum distance X ₁ between the outer surfaces of the heat exchange tube 421a and the heat exchange tube 422a, between the outer surfaces of the heat exchange tube 421a and the heat exchange tube 422b, and there is a distance between the outer surfaces of the heat exchange tube 422a and the heat exchange tube 422b. Minimum pitch V ₁ . In this embodiment, V ₁ is greater than X ₁ , and W ₁ ≥ D ₁ .

Generally speaking, the heat transfer coefficient of the second heat exchange tube 422 with a smaller diameter is greater than that of the first heat exchange tube 421 with a larger diameter, and the cost is lower, but the heat transfer area is smaller, The overall heat exchange capacity is not as good as that of the first heat exchange tube 421 . In this embodiment, a part of the first heat exchange tube 421 with a larger diameter _D1 is replaced with a second heat exchange tube 422 with a smaller diameter _D2 . On the one hand, the diameter of a part of the heat exchange tube is reduced. The minimum distance V ₁ of a part of the outer surface is increased to reduce the flow velocity of the gas flowing between the corresponding heat exchange tubes, thereby improving the heat exchange efficiency of the evaporator. On the other hand, in the same column, for the first heat exchange tubes 421 in the lower row of the second heat exchange tubes 422, since the heat exchange capacity of the second heat exchange tubes 422 is smaller than that of the first heat exchange tubes 421 Therefore, the flow rate of the liquid refrigerant on the first heat exchange tubes 421 in the lower row increases, thereby increasing the liquid film Reynolds number Re by increasing the flow rate of the liquid refrigerant in the first heat exchange tubes 421 in the lower row. _film , thus further improving the heat transfer coefficient "h _r ".

In this way, even if the horizontal distance W ₀ between the centers of the heat exchange tubes is not increased, the space of the refrigerant channel in the width direction W can be increased, so as to achieve the purpose of reducing the flow velocity of the gas flowing between the corresponding heat exchange tubes. In this embodiment, the center-to-center distance of each heat exchange tube has not changed compared with the existing technology of all large-diameter heat exchange tubes, but the space of the refrigerant channel between the

heat exchange tubes

421a and 422b, and the heat exchange tubes The space of the refrigerant passage between the

heat pipes

422a and 422b is increased. Therefore, the overall heat exchange efficiency of the evaporator of this embodiment can still be improved, and overall, the cost of the heat exchange tube can be reduced.

It should be noted that, in some other embodiments, among the four adjacent

heat exchange tubes

421a, 421b, 422a and 422b in two adjacent rows, the centers of the three adjacent heat exchange tubes may not form two Instead of forming a regular triangle, similar to the first embodiment, the horizontal spacing between adjacent heat exchange tubes in different rows is increased to form two isosceles triangles.

Figure 4C shows that in the case of the same number of heat exchange tubes, the first heat exchange tube in the falling film tube bank 415 of the present embodiment, the second heat exchange tube in the falling film tube bank 415 of the present embodiment, the ideal situation Under the falling film tube bundle comprising the first heat exchange tube, ideally the flooded tube bank comprising the first heat exchange tube, ideally the falling film tube bank comprising the second heat exchange tube, ideally comprising the second The comparison diagram of the theoretical value of the heat transfer coefficient of a single heat exchange tube in the liquid-filled tube bundle of the heat exchange tube. The theoretical value is obtained by the Gaussian distribution equation (1). In FIG. 4C , the abscissa shows different rows of heat exchange tubes from top to bottom, and the ordinate shows the heat transfer coefficient. Among them, the straight line 461, the straight line 462, the straight line 463 and the straight line 464 represent the falling film tube bundle including the first heat exchange tube under ideal conditions, the flooded tube bundle including the first heat exchange tube under ideal conditions, and the tube bundle including the first heat exchange tube under ideal conditions. The heat transfer coefficient of the falling film tube bundle of the second heat exchange tube and, ideally, the heat transfer coefficient of a single heat exchange tube in the flooded tube bundle including the second heat exchange tube. The curve 460 and the curve 470 represent the heat transfer coefficients of the first heat exchange tube and the second heat exchange tube in the falling film tube bundle 415 of this embodiment, respectively.

It can be seen from Fig. 4C that under ideal conditions, the heat transfer coefficients of the falling film tube bundle and the flooded tube bundle including the second heat exchange tube with a small diameter are higher than those of the first heat exchange tube with a large diameter. Membrane tube bundles and liquid-filled tube bundles indicate that heat transfer tubes with small diameters have better heat transfer coefficients. Moreover, the falling film tube bundle including the second heat exchange tubes with small diameters can almost maintain a heat transfer coefficient equivalent to the ideal situation, and the heat transfer coefficient does not decrease significantly with the number of rows. The heat transfer coefficient of the falling film tube bundle including the first heat exchange tubes with large diameter is also always higher than that of the liquid-filled tube bundle with the same diameter under ideal conditions.

5A-5C illustrate a third embodiment of the evaporator of the present application. Fig. 5A shows the radial cross-sectional view of the third embodiment evaporator 500 of the evaporator in Fig. 2, Fig. 5B is a partial enlarged view of four adjacent heat exchange tubes in the falling film tube bundle of Fig. 4A, Fig. 5C is a heat exchange Comparison chart of theoretical values of coefficients. 5A and 5B, the evaporator 500 is also provided with a falling film tube bank 515 and a liquid flooded tube bank 516, and the falling film tube bank 515 and the flooded tube bank 516 respectively include several heat exchange tubes arranged in a row. The heat exchange tubes in the liquid tube bundle 516 and the arrangement of the heat exchange tubes are the same as those in the first embodiment and the second embodiment. Moreover, the heat exchange tubes in the falling film tube bundle 515 include several first heat exchange tubes 521 with a larger diameter _D1 and several second heat exchange tubes 522 with a smaller diameter _D2 . The difference from the second embodiment is that several first heat exchange tubes 521 are arranged in a row, and several second heat exchange tubes 522 are arranged in a row, and the rows of first heat exchange tubes 521 and the rows of second heat exchange tubes 522 Columns are staggered. As an example, the larger diameter D ₁ of the first heat exchange tube 521 is equal to the diameter D ₀ of the heat exchange tube 320 in the first embodiment. In this embodiment, the diameter _D1 of the first heat exchange tube 521 with a large diameter is 1 inch, that is, 25.4 millimeters, and the diameter _D2 of the second heat exchange tube 522 with a small diameter is 3/4 inch. That is 19.05 millimeters. In the falling film tube bundle 515 , the quantity ratio of the first heat exchange tubes 521 and the second heat exchange tubes 522 is approximately 1:1.

Fig. 5B shows the enlarged structure of four adjacent

heat exchange tubes

521a, 521b, 522a and 522b in two adjacent columns, these heat exchange tubes are adjacent to each other, and the center of three adjacent heat exchange tubes forms Two equilateral triangles. As shown in FIG. 5B , the

heat exchange tubes

521 a and 521 b are in the same column, and the

heat exchange tubes

522 a and 522 b are in the same column. In addition, the heat exchange tube 521a, the heat exchange tube 522a and the heat exchange tube 521b are adjacent to each other, and the heat exchange tube 521b, the heat exchange tube 522a and the heat exchange tube 522b are adjacent to each other. In the height direction H, the centers of adjacent

heat exchange tubes

521a and 522a in the same row have a vertical distance H ₂ . In the width direction W, the centers of adjacent

heat exchange tubes

521a and 522a in different rows have a horizontal distance W ₂ . There is a minimum distance X ₂ between the outer surfaces of the heat exchange tube 521a and the heat exchange tube 521b. There is a minimum distance V ₂ between the outer surfaces of the heat exchange tube 522a and the heat exchange tube 521b, and between the heat exchange tube 522a and the outer surface of the heat exchange tube 521a. In this embodiment, V ₂ is greater than X ₂ , and W ₂ ≥ _{D 1} .

Similar to the second embodiment, this embodiment also replaces a part of the first heat exchange tube 521 with a larger diameter _D1 with a second heat exchange tube 522 with a smaller diameter _D2 , and reduces a part The diameter of the heat exchange tubes increases the minimum distance V ₁ of the outer surface, so as to reduce the flow velocity of the gas flowing between the corresponding heat exchange tubes, thereby improving the heat exchange efficiency of the evaporator. Compared with the second embodiment, although V ₂ <V ₁ , in each row of heat exchange tubes in the falling film tube bundle 515 , the minimum distance between the outer surfaces of the heat exchange tubes between adjacent rows is increased.

It should be noted that, in some other embodiments, among the four adjacent

heat exchange tubes

521a, 521b, 522a, and 522b in two adjacent columns, the centers of the three adjacent heat exchange tubes may not form two Instead of forming a regular triangle, similar to the first embodiment, the horizontal spacing between adjacent heat exchange tubes in different rows is increased to form two isosceles triangles.

Figure 5C shows that in the case of the same number of heat exchange tubes, including the first heat exchange tube in the falling film tube bank 515 of this embodiment, the second heat exchange tube in the falling film tube bank 515 of this embodiment, the ideal The falling film tube bundle including the first heat exchange tube under ideal conditions, the flooded tube bundle including the first heat exchange tube under ideal conditions, the falling film tube bundle including the second heat exchange tube under ideal conditions, and the falling film tube bundle including the second heat exchange tube under ideal conditions The comparison chart of the theoretical value of the heat transfer coefficient of a single heat exchange tube in the flooded tube bundle of the two heat exchange tubes. The theoretical value is obtained by the Gaussian distribution equation (1). In FIG. 5C , the abscissa shows different rows of heat exchange tubes from top to bottom, and the ordinate shows the heat transfer coefficient. Among them, the straight line 561, the straight line 562, the straight line 563 and the straight line 564 represent the falling film tube bundle including the first heat exchange tube under ideal conditions, the flooded tube bundle including the first heat exchange tube under ideal conditions, and the tube bundle including the first heat exchange tube under ideal conditions. The heat transfer coefficient of the falling film tube bundle of the second heat exchange tube and, ideally, the heat transfer coefficient of a single heat exchange tube in the flooded tube bundle including the second heat exchange tube. Curve 560 and curve 570 represent the heat transfer coefficients of the first heat exchange tube and the second heat exchange tube in the falling film tube bundle 515 of this embodiment, respectively.

It can be seen from Fig. 5C that although the heat transfer coefficient of the falling film tube bundle including the first heat exchange tube 521 and the second heat exchange tube 522 decreases with the increase of the number of rows, the heat transfer coefficient decreases with the increase of the row number. The decrease of the number is not obvious, and they are all higher than the heat transfer coefficients of the respective fully flooded tube bundles.

6A-6C illustrate a fourth embodiment of the evaporator of the present application. Figure 6A shows a radial cross-sectional view of the evaporator 600 of the fourth embodiment of the evaporator in Figure 2, Figure 6B shows a schematic structural view of the baffle plate 631 in Figure 6A, and Figure 6C is a comparison of theoretical values of heat transfer coefficients picture. As shown in FIG. 6A and FIG. 6B , the evaporator 600 is provided with a falling film tube bank 615 and a liquid flooded tube bank 616 , and the falling film tube bank 615 and the flooded tube bank 616 respectively include several heat exchange tubes arranged in a row. In this embodiment, the heat exchange tubes in the flooded tube bundle 616 and the arrangement of the heat exchange tubes are the same as those in the first embodiment. Moreover, the heat exchange tubes in the falling film tube bundle 615 and the arrangement of the heat exchange tubes are substantially the same as those in the first embodiment, and will not be repeated here. The only difference is that, in this embodiment, the heat exchange tubes in the middle of the falling film tube bundle 615 are spaced apart to form a fluid channel 638 extending approximately along the width direction W.

The evaporator 600 further includes a first baffle 631 and a second baffle 632 , and the first baffle 631 and the second baffle 632 are arranged on the left and right sides of the falling film tube bundle 615 in the width direction W, respectively. The first baffle 631 and the second baffle 632 are respectively provided with several windows 635 , and these windows 635 are arranged along the length direction L and are arranged at corresponding positions of the fluid channel 638 . The fluid channel 638 and the window 635 can allow the gas refrigerant evaporated by the upper heat exchange tube to flow out through the window 635 instead of continuing to flow through the lower heat exchange tube. As a result, the flow rate of the gas refrigerant flowing through the lower heat exchange tubes decreases.

In this embodiment, even though the number of heat exchange tubes is the same as that in the first embodiment, since part of the gaseous refrigerant can be discharged through the fluid channel 638 and the window 635, the flow rate of the gaseous refrigerant in the lower falling film heat exchange tube bundle is reduced, Therefore, compared with the first embodiment, the heat exchange efficiency of the evaporator can be further improved.

Figure 6C shows the falling film tube bundle 615 of this embodiment, the falling film tube bundle 315 in the first embodiment, the falling film tube bundle under ideal conditions and the flooded film tube bundle under ideal conditions in the case of the same number of heat exchange tubes. The comparison chart of the theoretical value of the heat transfer coefficient of a single heat exchange tube in the tube bundle. The theoretical value is obtained by the Gaussian distribution equation (1). In FIG. 6C , the abscissa shows different rows of heat exchange tubes from top to bottom, and the ordinate shows the heat transfer coefficient. Wherein, the straight line 661 and the straight line 662 represent the heat transfer coefficient of a single heat exchange tube in the falling film tube bundle and the flooded tube bundle under ideal conditions respectively. Curve 668 and curve 670 represent the heat transfer coefficients of the falling film tube bundle 615 of this embodiment and the falling film tube bundle 315 of the first embodiment, respectively.

It can be seen from FIG. 6C that in the falling film tube bundle 615 of this embodiment, a part of gas refrigerant is discharged through the middle, so that the heat transfer coefficient of each row of heat exchange tubes can be maintained at a relatively high level.

Those skilled in the art can understand that although in this embodiment, the arrangement of the heat exchange tubes in the falling film tube bundle is roughly the same as that of the first embodiment. However, the heat exchange tubes can also be set to be roughly the same as the second embodiment or the third embodiment, only the fluid passages need to be set in the falling film tube bundle in the second embodiment or the third embodiment, and the corresponding baffles of the fluid passages A window for discharging gas refrigerant can be provided on the board.

In the evaporators of the above-mentioned embodiments, the falling film tube bundle in the evaporator of the first embodiment is realized by increasing the distance between the heat exchange tubes in the width direction, that is, the distance between the heat exchange tubes in each column. The space of the refrigerant passage in the width direction W is increased. The falling film tube bundles in the evaporators of the second embodiment and the third embodiment increase the minimum distance between the outer surfaces of the tube walls of the heat exchange tubes by replacing a part of the heat exchange tubes with heat exchange tubes of small diameter, thereby The space of the refrigerant channel in at least a part of the width direction W is increased.

In this application, by increasing the flow space of the refrigerant in the width direction W, the flow velocity of the gas passing through the corresponding heat exchange tubes is reduced, thereby reducing the ratio of the gas phase Reynolds number _Rev to the liquid film Reynolds number Re _film , and This increases the heat exchange efficiency of the evaporator.

While only some of the features of the application have been illustrated and described herein, various modifications and changes will occur to those skilled in the art. It is therefore to be understood that the appended claims are intended to cover all such improvements and changes as fall within the true spirit of the application.

Claims

A kind of evaporator is characterized in that comprising:

A housing (203), the housing (203) has a cavity (310), and the cavity (310) has a length direction (L), a width direction (W) and a height direction (H);

Falling film tube bundle (315), the falling film tube bundle (315) is arranged in the cavity (310) and arranged in a row, including several heat exchange tubes (320) in the falling film tube bundle (315), each A heat exchange tube (320) extends along the length direction (L) of the cavity (310), and the centers of the heat exchange tubes (320) in each row are arranged along the height direction (H), and are relatively Centers of two adjacent heat exchange tubes (320) in adjacent columns are arranged staggered in the width direction (W) of the cavity (310);

Wherein, the falling film tube bundle (315) is configured such that, among the four adjacent heat exchange tubes (320) in two adjacent columns, at least two of the heat exchange tubes (320) in different columns The minimum spacing (V 0 , V 1 , V 2 ) between the outer surfaces is greater than the minimum spacing (X 0 , X 1 , X 2 ) between the outer surfaces of two heat exchange tubes (320) in the same column.
The evaporator according to claim 1, characterized in that:

Among the four adjacent heat exchange tubes (320) in two adjacent columns, the spacing between the outer surfaces of at least two different columns of the heat exchange tubes (320) is set so that the flow through adjacent The gas flow velocity of the two rows of heat exchange tubes (320) is reduced, thereby improving the heat exchange efficiency of the evaporator (100).
The evaporator according to claim 2, characterized in that:

Each heat exchange tube (320) in the falling film tube bundle (315) has the same tube diameter (D 0 ), and two adjacent heat exchange tubes (320) in adjacent columns The distance (W 0 ) between the center of the cavity (310) in the width direction (W) and the adjacent two heat exchange tubes (320) in each column of the heat exchange tubes (320) are in the cavity (310) The ratio of the center spacing (H 0 ) on the height direction (H) satisfies
The evaporator according to claim 2, characterized in that:

The falling film tube bundle (415) includes several first heat exchange tubes (421) with a larger diameter (D1) and several second heat exchange tubes (422) with a smaller diameter (D2);

On the column of the falling film tube bundle (415), the first heat exchange tubes (421) and the second heat exchange tubes (422) are arranged alternately.
The evaporator according to claim 2, characterized in that:

The falling film tube bundle (515) includes several first heat exchange tubes (521) with relatively large diameters (D1) and several second heat exchange tubes (522) with relatively small diameters (D2). The first heat exchange tubes (521) are arranged in a row, and several of the second heat exchange tubes (522) are arranged in a row;

Wherein, the columns of the first heat exchange tubes (521) and the columns of the second heat exchange tubes (522) are alternately arranged.
The evaporator according to claim 4 or 5, characterized in that:

The adjacent first heat exchange tubes (421, 521) and the second heat exchange tubes (422, 522) in the two adjacent rows of heat exchange tubes (320) are in the width direction of the cavity (310) ( The distance (W1, W2) between centers on W) is not smaller than the larger tube diameter (D1) of the first heat exchange tube (421, 521).
The evaporator according to claim 6, characterized in that:

The larger diameter (D1) of the first heat exchange tube (421, 521) is 25.4 mm; and

The smaller tube diameter (D2) of the second heat exchange tubes (422, 522) is 19.05mm.
The evaporator according to claim 1, wherein the evaporator further comprises:

The first baffle (631) and the second baffle (632), the first baffle (631) and the second baffle (632) are respectively arranged on the falling film tube bundle (615) in the container the outer side in the width direction (W) of the cavity (310);

Wherein, the first baffle (631) and the second baffle (632) are respectively provided with several windows (635), and the several windows (635) are arranged along the length direction of the cavity (310). (L) arrangement, and the several windows (635) are arranged outside the central part of the falling film tube bundle (615) in the height direction (H) of the cavity (310).
The evaporator according to claim 8, characterized in that:

The outside of the window (635) on the first baffle (631) and the second baffle (632) are each provided with a liquid baffle extending along the length direction (L) of the cavity (310) (638), wherein tops of said liquid baffles (638) are connected to respective said first baffles (631 ) and said second baffles (632), and said liquid baffles (638) are connected to said The windows (635) are spaced a certain distance apart.
A refrigeration system is characterized in that it comprises:

A compressor (193), a condenser (191), a throttling device (192) and an evaporator (100) arranged in the refrigerant circuit, wherein the evaporator (100) is any one of claims 1-9 mentioned.