KR20240063935A - Evaporator and refrigeration system including same - Google Patents

Abstract

This application covers Shell; It is installed in the cavity and arranged in a row, and includes a plurality of heat exchange tubes, where the center of the heat exchange tube in each row is arranged along the height direction, and the center of the two adjacent heat exchange tubes in the adjacent row is the center of the cavity. A falling film tube bundle disposed offset in the width direction, wherein the falling film tube bundle has the same minimum distance between the outer surfaces of the heat exchange tubes in at least two different rows among the four adjacent heat exchange tubes in two adjacent rows. It provides an evaporator configured to be larger than the minimum gap between the outer surfaces of two of the heat exchange tubes. In the present application, by increasing the flow space of the refrigerant in the width direction (W), by reducing the flow rate of the gas flowing between the corresponding heat exchange pipes, the gas phase Reynolds number (Re _v ) and the liquid film Reduces the ratio of Reynolds number (Re _film ), thereby improving the heat exchange efficiency of the evaporator.

Description

Evaporator and refrigeration system including same

This application relates to an evaporator, and particularly to an evaporator with high heat exchange efficiency and a refrigeration system including the same.

A traditional refrigeration system includes an evaporator, condenser, throttling device and compressor. When the low-temperature refrigerant liquid passes through the evaporator, it undergoes heat exchange with the external working fluid and absorbs the heat of the working fluid, so that the temperature of the working fluid is lowered and a cooling effect is realized, and the working fluid can be air. , it may be coolant. After heat exchange, the refrigerant liquid is vaporized into gaseous refrigerant and flows into the compressor. The heat exchange efficiency of the evaporator is affected by several factors.

The first aspect of the present application has at least one object to provide an evaporator with high heat exchange efficiency. The evaporator includes a shell including cavities having longitudinal, width and height directions; It is installed in the cavity and arranged in a row, and includes a plurality of heat exchange tubes, each heat exchange tube extending along the longitudinal direction of the cavity, the center of the heat exchange tube in each row is arranged along the height direction, and adjacent a falling film tube bundle in which the centers of two adjacent heat exchange tubes in a row are arranged to be offset in the width direction of the cavity; Here, the falling film tube bundle is such that among the four adjacent heat exchange tubes in two adjacent rows, the minimum gap between the outer surfaces of the heat exchange tubes in at least two different rows is greater than the minimum spacing between the outer surfaces of the two heat exchange tubes in the same row. It is composed largely.

According to the first aspect, by setting a gap between the outer surfaces of the heat exchange tubes of at least two different rows among the four adjacent heat exchange tubes in two adjacent rows, reducing the flow rate of the gas flowing through the heat exchange tubes of the two adjacent rows, Improves heat exchange efficiency of the evaporator.

According to the first aspect, each heat exchange tube in the falling film tube bundle has the same pipe diameter, and the center spacing in the width direction of the cavity of the two adjacent heat exchange tubes in an adjacent row and one of the heat exchange tubes in each row The ratio of the spacing between the centers of the two adjacent heat exchange pipes in the height direction of the cavity is satisfies.

According to the first aspect, the falling film tube bundle includes a plurality of first heat exchange tubes having a large tube diameter and a plurality of second heat exchange tubes having a small tube diameter; In the row of the falling film tube bundles, the first heat exchange tube and the second heat exchange tube are arranged to be offset.

According to the first aspect, the falling film tube bundle includes a plurality of first heat exchange tubes having a large tube diameter and a plurality of second heat exchange tubes having a small tube diameter, and the plurality of first heat exchange tubes are arranged in a row. , a plurality of second heat exchange tubes are arranged in a row; Here, the rows of the first heat exchange tubes and the rows of the second heat exchange tubes are arranged to be offset.

According to the first aspect, in the two adjacent rows of heat exchange tubes, 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 is greater than or equal to the large pipe diameter of the first heat exchange tubes.

According to the first aspect, the large diameter of the first heat exchange tube is 25.4 mm; The small diameter of the second heat exchange tube is 19.05 mm.

According to the first aspect, the evaporator further includes a first baffle and a second baffle respectively installed outside the cavity in the width direction of the falling film tube bundle, wherein the first baffle and the second baffle A plurality of windows are each installed, the plurality of windows are arranged along the longitudinal direction of the cavity, and the plurality of windows are installed outside the central portion of the falling film tube bundle in the height direction of the cavity.

According to the first aspect, a liquid blocking baffle extending along the longitudinal direction of the cavity is provided outside the window in the first baffle and the second baffle, respectively, wherein the top of the liquid blocking baffle corresponds to the window. It is connected to the first baffle and the second baffle, and the liquid blocking baffle is spaced apart from the window at a certain distance.

The second aspect of the present application has at least one object to provide a refrigeration system including a compressor, a condenser, a throttling device, and an evaporator according to any one of the first aspect installed in a refrigerant circuit.

1 is a schematic block diagram of a refrigeration system.
Figure 2 is a perspective view of the evaporator of Figure 1.
Figure 3A is a radial cross-sectional view of one embodiment of the evaporator of Figure 2;
Figure 3b is a local enlarged view of four adjacent heat exchange tubes in the falling film tube bundle of Figure 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 according to 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 of Figure 2;
Figure 4b is a local enlarged view of four adjacent heat exchange tubes in the falling film tube bundle of Figure 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 according to 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 another embodiment of the evaporator of Figure 2;
Figure 5b is a local enlarged view of four adjacent heat exchange tubes in the falling film tube bundle of Figure 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 according to 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 another embodiment of the evaporator of Figure 2;
FIG. 6B is a structural schematic diagram of the first baffle of FIG. 6A.
FIG. 6C 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 according to the embodiment shown in FIG. 6A and the falling film tube bundle in an ideal state.

Hereinafter, various specific embodiments of the present application will be described with reference to the accompanying drawings that form a part of the present specification. In this application, “front”, “back”, “top”, “bottom”, “left”, “right”, “inside”, “outside”, “top”, “bottom”, “front”, “back” , “proximal end,” “distal end,” “transverse direction,” “longitudinal direction,” and the like have been used to describe structural parts and elements of various embodiments of the present application; however, as used herein, such terms are merely descriptive. For convenience only, these terms are established based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in this application can be installed in different orientations, these terms indicating orientation are merely descriptive and should not be considered limiting.

Ordinal numbers such as “first”, “second”, etc. used in this application are only for distinction and identification, have no other meaning, and do not indicate a specific order or have a specific relationship unless otherwise specified. For example, the term “first member” itself does not imply the existence of a “second member,” and the term “second member” itself does not imply the existence of a “first member.”

1 is a schematic block diagram of 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 form one refrigerant circulation circuit through piping. The circuit is charged with refrigerant. As shown in the direction of the arrow in FIG. 1, the refrigerant sequentially flows through the compressor 193, the condenser 191, the throttling device 192, and the evaporator 100, and then flows back into the compressor 193. In the refrigeration process, the throttling device 192 throttles the high-pressure liquid refrigerant from the condenser 191 to lower its pressure; The low-pressure refrigerant exchanges heat with the object to be cooled within the evaporator 100, absorbs heat from the object to be cooled, and is evaporated; The refrigerant vapor generated by vaporization is sucked into the compressor 193, and after being compressed, is discharged as a high-pressure gas; The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 193 undergoes heat exchange with the environmental medium in the condenser 191, releases heat, and is condensed into a liquid refrigerant; As the high-pressure liquid refrigerant flows through the throttling device 192 again, the pressure decreases. As this continues to circulate, a continuous refrigeration effect occurs.

Figure 2 is a perspective view of the evaporator 100 of Figure 1. As shown in Figure 2, the evaporator 100 has a shell 203, where the shell 203 includes a cylindrical body 204 and a pair of tubes. It includes a sheet 205, and the cylindrical body 204 is a cylinder with both ends open. A pair of tube sheets 205 are disposed at both ends of the cylindrical body 204, respectively, and the cylindrical body 204 has openings at both ends. to prevent. The cylindrical body 204 and a pair of tube sheets 205 are wrapped to form a cavity 310 (see FIG. 3A), and the cavity 310 is used to receive a heat exchange tube. An inlet pipe 208 and an outlet pipe 207 are connected to the tube sheet 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 the evaporator. It matches the direction of (100). A refrigerant inlet 101 and a refrigerant outlet 102 are installed in the cylindrical body 204, where both the refrigerant inlet 101 and the refrigerant outlet 102 are located at the top of the evaporator 100 in the height direction (H). and is shifted in the longitudinal and/or radial direction of the cylindrical body 204. The liquid refrigerant or gas-liquid mixed refrigerant in the refrigeration system 190 flows into the evaporator 130 from the refrigerant inlet 101, absorbs heat in the evaporator 130, and then changes into a gaseous refrigerant, and flows out of the refrigerant outlet 102. is discharged.

3A to 3C show a first embodiment of the evaporator of the present application. FIG. 3A is a radial cross-sectional view of the first embodiment of the evaporator of FIG. 2, FIG. 3B is a local enlarged view of four adjacent heat exchange tubes in the falling film tube bundle of FIG. 3A, and FIG. 3C is a comparison diagram of the theoretical value of the heat transfer coefficient. . As shown in FIGS. 3A and 3B, a cavity 310 is formed inside the shell 203, and a falling film tube bundle 315, a liquid filled tube bundle 316, and a distribution device ( 340) and demister 341 are installed. 2 and 3A, the refrigerant inlet 101 is located in the middle of the evaporator 100 in the longitudinal and width directions, which is advantageous for uniform distribution of the refrigerant. The refrigerant outlet 102 and the refrigerant inlet 101 are arranged to be offset in the longitudinal and/or radial directions. The distribution device 340 is installed on the upper part of the falling film tube bundle 315 and communicates with the refrigerant inlet 101 to uniformly distribute the refrigerant from the throttling device 192 received at the refrigerant inlet 101. Send it to the falling film tube bundle (315). The demister 341 is connected to the lower part of the refrigerant outlet 102, and the outlet of the gas obtained through evaporation of the falling film tube bundle 315 and the liquid-filled tube bundle 316 is installed at the lower part of the demister 341. Thus, the demister 341 can prevent liquid droplets mixed in the gaseous refrigerant obtained through evaporation from being discharged from the outlet 102.

The falling film tube bundle 315 is generally installed in the middle and upper part of the cavity 310, and the liquid-filled tube bundle 316 is installed in the bottom of the cavity 310, and the liquid-filled tube bundle 316 and the falling film tube bundle There is a certain gap between the bottoms of (315). The falling film tube bundle 315 and the liquid-filled tube bundle 316 are heat exchange tube bundles formed by sequentially arranging a plurality of heat exchange tubes 320, respectively. Each heat exchange pipe 320 has the same pipe diameter D ₀ , and each heat exchange pipe 320 extends along the longitudinal direction L of the cavity 305 . As one embodiment, the pipe diameter (D ₀ ) of the heat exchange tube 320 is 1 inch, that is, 25.4 mm. Inside each heat exchange tube, it is connected to the inlet pipe 208 and the outlet pipe 207 to form a fluid passage for distributing water or other media. A refrigerant passage for distributing refrigerant is formed in the gap between each heat exchange pipe 320 and the adjacent heat exchange pipe 320. The medium in the fluid passage and the refrigerant in the refrigerant passage exchange heat through the pipe wall of the heat exchange pipe.

Each heat exchange tube 320 in the falling film tube bundle 315 is arranged in a row, and adjacent rows are spaced apart at the same distance. Additionally, the centers of the heat exchange tubes 320 in each row are arranged to be evenly spaced apart at equal intervals along the height direction (H). In the width direction (W), the centers of the adjacent heat exchange pipes 320 among the two adjacent rows of heat exchange pipes 320 are arranged to be offset but have the same spacing. In other words, the centers of the two heat exchange pipes 320 adjacent in the width direction (W) are not located on the same horizontal line, that is, they are not located at the same height. In the height direction H, the centers of two adjacent heat exchange pipes 320 are located on the same vertical line, that is, located at the same width. The reason for arranging the heat exchange tubes in this way is that during the falling film evaporation process, the liquid refrigerant to be evaporated flows from top to bottom, forming a liquid film on the outer surface of the tube wall of each heat exchange tube 320, and forming a liquid film on the outer surface of the tube wall of each heat exchange tube 320. This is because heat exchange occurs with . The reason that the heat exchange tubes 320 are arranged in a row and the adjacent heat exchange tubes 320 are arranged offset in the width direction and not side by side is that the direction of extension of the refrigerant passage formed between the two adjacent rows of heat exchange tubes 320 is that of the liquid refrigerant. This is to avoid that it does not match the direction of gravity, making it difficult to form a liquid film in the heat exchange pipes in the lower row. The piping method of the present application is advantageous in that the non-evaporated liquid refrigerant continues to flow to the outer surface of the lower heat exchange tube 320 to form a liquid film, thereby improving the evaporation efficiency of each heat exchange tube.

Each heat exchange tube 320 in the liquid-filled tube bundle 316 is also arranged in a row and laid on the bottom of the cavity 310. Even after heat exchange in the falling film tube bundle 315, some of the liquid refrigerant is still not completely evaporated into gaseous refrigerant, and this portion of the liquid refrigerant is at a height of the liquid-filled tube bundle 316 at the bottom of the cavity 310. A liquid level higher than the height is formed. The heat exchange tube 320 in the liquid filled tube bundle 316 is immersed in this portion of liquid refrigerant to further evaporate the liquid refrigerant into gaseous refrigerant.

The evaporator 100 further includes a first baffle 331 and a second baffle 332, each of the first baffle 331 and the second baffle 332 in the width direction (W) of the falling film tube bundle 315. ) and extends along the longitudinal direction (L). The first baffle 331 and the second baffle 332 are used to prevent the liquid refrigerant from flowing to the outside of the falling film tube bundle 315, so that the refrigerant flows through each heat exchange tube in the falling film tube bundle 315 from top to bottom. It is used to guide the flow through. The gaseous refrigerant obtained through evaporation flows along the first baffle 331 and the second baffle 332 and is discharged from the bottom of the first baffle 331 and the second baffle 332. In other words, the outlet of the gaseous refrigerant obtained by evaporation in the falling film tube bundle 315 is generally located at the bottom edge of the first baffle 331 and the second baffle 332.

FIG. 3B shows an enlarged structure of four adjacent heat exchange tubes 320a, 320b, 320c, and 320d in two adjacent rows of the falling film tube bundle 315 of FIG. 3A. Those skilled in the art will know that since the heat exchange tubes 320 in the falling film tube bundle 315 are arranged uniformly, these four heat exchange tubes may be any four adjacent heat exchange tubes in two adjacent rows, which are two adjacent each, and the three adjacent heat exchange tubes It can be understood that the centers of the heat exchange tubes form two acute triangle shapes. As shown in Figure 3b, the heat exchange tube 320a and the heat exchange tube 320b are located in the same row, and the heat exchange tube 320c and the heat exchange tube 320d are located in the same row. Additionally, the heat exchange tube 320a, heat exchange tube 320b, and heat exchange tube 320c are adjacent, and their centers form an acute triangle shape. The heat exchange tube 320b, heat exchange tube 320c, and heat exchange tube 320d are adjacent, and their centers form an acute triangle shape. In the height direction H, the centers of the heat exchange tubes 320a and 320b adjacent to each other in the same row have a gap H ₀ (hereinafter abbreviated as vertical gap). In the width direction W, the centers of the adjacent heat exchange tubes 320a and 320c in different rows have a gap W ₀ (hereinafter abbreviated as horizontal gap). There is a minimum gap (X ₀ ) between the outer surfaces of the heat exchange tube (320a) and the heat exchange tube (320b). There is a minimum gap (V ₀ ) between the heat exchange tube (320a) and the outer surface of the heat exchange tube (320c). In this example, V ₀ is greater than X ₀ . Also, H ₀ and W ₀ are satisfies the relationship.

In some existing falling film tube bundles, the centers of three adjacent heat exchange tubes in a row of heat exchange tubes are generally arranged in an equilateral triangle shape. These heat exchange tubes generally have a horizontal spacing equal to D ₀ and generally has a vertical spacing of In other words, the ratio of the horizontal spacing and vertical spacing of these heat exchange tubes is approximately cos30°.

In a falling film evaporator, the gas-liquid two-phase refrigerant flowing into the evaporator from the refrigerant inlet is distributed by a distribution device and then uniformly distributed on the surface of the heat exchange tube at the top of the falling film tube bundle, forming a liquid film to perform heat exchange. Some of the liquid refrigerant is converted to gas through evaporation and heat exchange, and some of the non-evaporated liquid refrigerant falls into the heat exchange tube in the lower row and continues to evaporate. The flow rate of the liquid refrigerant flowing through the falling film tube bundle is the falling film tube bundle. Although it gradually decreases from the top to the bottom of the bundle, the flow rate of gaseous refrigerant gradually increases.

After research, the applicant found that the heat transfer coefficient (h _r ) of each heat exchange tube of the falling film tube bundle could fit the Gaussian distribution equation (1):

Here, y0, A, w, xc are the fitting constants, Re _v is the gas phase Reynolds number, and Re _film is the liquid film Reynolds number. Through the Gaussian distribution equation (1), it can be seen that the heat transfer coefficient (h _r ) decreases as the ratio of the gas phase Reynolds number (Re _v ) and the liquid film Reynolds number (Re _film ) increases. Here, the gas phase Reynolds number (Re _v ) and the intertube flow rate of the gaseous refrigerant form a directly proportional relationship, and the liquid film Reynolds number (Re _film ) and the liquid state refrigerant flow rate also form a directly proportional relationship. The smaller the flow rate of the gaseous refrigerant, the smaller the gas phase Reynolds number (Re _v ) and the larger the heat transfer coefficient (h _r ). The larger the flow rate of the liquid refrigerant, the larger the liquid film Reynolds number (Re _film ) and the larger the heat transfer coefficient (h _r ).

The flow rate of the gaseous refrigerant is related to the flow rate of the gaseous refrigerant and the distribution area of the gaseous refrigerant. By increasing the minimum gap between the tube wall outer surfaces of the heat exchange tubes of different rows of falling film tube bundles, and increasing the space of the refrigerant passage in the width direction (W), under a constant flow rate of gaseous refrigerant, the corresponding heat exchange tubes By reducing the flow rate of passing gas, the heat transfer coefficient (h _r ) is improved. However, after the horizontal spacing between heat exchange tubes increases, the number of heat exchange tubes in the falling film tube bundle that can be placed within a cavity of a certain size also decreases accordingly, causing the heat exchange amount of the evaporator to decrease. Therefore, by increasing the minimum gap between the outer surfaces of the tube walls of the heat exchange tubes of the falling film tube bundle within a certain range, the heat exchange efficiency of the evaporator can be improved, thereby increasing the heat exchange amount of the evaporator. Alternatively, reduce the number of heat exchange tubes while maintaining the same amount of heat exchange in the evaporator.

In this embodiment, compared to 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 gap 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 ) of the centers of the heat exchange tubes and increasing the horizontal spacing (W ₀ ) of the centers of the heat exchange tubes. do. Specifically, the falling film tube bundle 315 of the present application increases the ratio of the horizontal spacing (W ₀ ) and the vertical spacing (H ₀ ) to (1~1.5)*cos30°. In other words, 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 the shape of an equilateral triangle, but in the shape of an isosceles triangle with an apex angle of less than 60°. The increased ratio of the horizontal gap (W ₀ ) and the vertical gap (H ₀ ) can improve the heat exchange efficiency of the evaporator 100 by reducing the flow rate of gas flowing through the two adjacent rows of heat exchange tubes 320.

3C shows the heat transfer of a single heat exchange tube among the present embodiment falling film tube bundle 315, a conventional falling film tube bundle, a falling film tube bundle under ideal circumstances, and a liquid filled tube bundle under ideal circumstances, for the same number of heat exchange tubes. This is a comparison of the theoretical values of the coefficients, and the theoretical values are obtained through the Gaussian distribution equation (1). In Figure 3c, the abscissa represents different numbers of heat exchange pipes from top to bottom, and the ordinate represents the heat transfer coefficient. Here, straight lines 361 and 362 represent the heat transfer coefficients of a single heat exchange tube in a falling film tube bundle and a liquid filled tube bundle under ideal circumstances, 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 the present embodiment, respectively.

As can be seen in Figure 3C, in an ideal situation, the heat transfer coefficients of the heat exchange tubes in both the falling film tube bundle and the liquid filled tube bundle do not decrease as the number of rows increases. However, in a conventional falling film tube bundle, the heat transfer coefficient decreases rapidly as the number of rows increases, and even in the lower rows of heat exchange tubes at the bottom, the heat exchange efficiency drops below the heat transfer coefficient of a liquid-filled tube bundle in an ideal situation. However, in the falling film tube bundle of this embodiment, the heat transfer coefficient remains comparable to that of a falling film tube bundle in an almost ideal situation. Although the heat exchange tubes at the bottom are somewhat degraded, the heat transfer coefficient is much higher than that of a liquid-filled tube bundle under ideal circumstances.

Figures 4a to 4c show a second embodiment of the evaporator of the present application. Figure 4a shows a radial cross-section of an evaporator 400 according to a second embodiment of the evaporator of Figure 2, Figure 4b is a local enlarged view of four adjacent heat exchange tubes in the falling film tube bundle of Figure 4a, and Figure 4c. is a comparison diagram of the theoretical value of the heat transfer coefficient. 4A and 4B, the same point as the first embodiment is that the evaporator 400 is also provided with a falling film tube bundle 415 and a liquid filling tube bundle 416, and the falling film tube bundle ( 415) and the liquid-filled tube bundle 416 each include a plurality of heat exchange tubes arranged in a row. Here, the heat exchange tube in the liquid filled tube bundle 416 and the arrangement method of the heat exchange tube are the same as in the first embodiment. However, the falling film tube bundle 415 is different from the first embodiment, and the heat exchange tubes in the falling film tube bundle 415 no longer have the same tube diameter, but a plurality of first heat exchange tubes (D _{1 ) having a large tube diameter (D 1} ). 421) and a plurality of second heat exchange tubes 422 having a small pipe diameter (D ₂ ), and in each row of the falling film tube bundle 415, a first heat exchange tube 421 and a second heat exchange tube 422. ) are placed misaligned. In other words, any four adjacent heat exchange tubes in two adjacent rows necessarily include two first heat exchange tubes 421 of large diameter and two second heat exchange tubes 422 of small tube diameter. As one embodiment, the large pipe diameter (D ₁ ) of the first heat exchange pipe 421 is the same as the pipe diameter (D ₀ ) of the heat exchange pipe 320 in the first embodiment. In this embodiment, the pipe diameter (D ₁ ) of the first heat exchange pipe 421 with a large pipe diameter is 1 inch, that is, 25.4 mm, and the pipe diameter (D ₂ ) of the second heat exchange pipe 422 with a small pipe diameter is 3/4. inch, or 19.05 mm. In the falling film tube bundle 415, the ratio of the number of first heat exchange tubes 421 and second heat exchange tubes 422 is about 1:1.

Figure 4b shows an enlarged structure of four adjacent heat exchange tubes (421a, 421b, 422a, 422b) in two adjacent rows. These heat exchange tubes are two adjacent, and the centers of the three adjacent heat exchange tubes form two equilateral triangles. form As shown in Figure 4b, the heat exchange tube 421a and the heat exchange tube 422a are located in the same row, and the heat exchange tube 422b and the heat exchange tube 421b are located in the same row. 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 the adjacent heat exchange tubes 421a and 422a in the same row have a vertical gap H ₁ . In the width direction W, the centers of adjacent heat exchange tubes 421a and 422b in different rows have a horizontal gap W ₁ . There is _a minimum gap ( There is a minimum gap (V ₁ ) between the outer surfaces of . In this example, V ₁ is greater than X ₁ and W ₁ ≥D ₁ .

In general, the heat transfer coefficient of the second heat exchange pipe 422 with a small pipe diameter is larger than that of the first heat exchange pipe 421 with a large pipe diameter, and the cost is low, but the heat exchange area is small, so the overall heat exchange capacity is compared to the first heat exchange pipe 421. It is worse than the heat exchange tube (421). In this embodiment, some of the first heat exchange pipes 421 with a large pipe diameter (D ₁ ) are replaced by second heat exchange pipes 422 with a small pipe diameter (D ₂ ), and on the other hand, the pipe diameter of some of the heat exchange pipes is By reducing the minimum gap (V ₁ ) of some outer surfaces, the heat exchange efficiency of the evaporator is improved by reducing the flow rate of gas flowing between the corresponding heat exchange tubes. On the other hand, in the same row, for the first heat exchange tube 421 in the lower row of the second heat exchange tube 422, the heat exchange capacity of the second heat exchange tube 422 is lower than that of the first heat exchange tube 421. is smaller, the flow rate of the liquid refrigerant in the first heat exchange tube 421 in the lower row is increased, thereby improving the flow rate of the liquid refrigerant in the first heat exchange tube 421 in the lower row, thereby increasing the liquid film Reynolds number (Re _film ) By increasing , the heat transfer coefficient (h _r ) is further improved.

In this way, even if the horizontal spacing (W ₀ ) of the center of the heat exchange tube is not increased, the space of the refrigerant passage in the width direction (W) can be increased, so that the purpose of reducing the flow rate of gas flowing between the corresponding heat exchange tubes is achieved. make it happen In this embodiment, compared to the prior art in which all heat exchange tubes are of large diameter, the center spacing of each heat exchange tube does not change, but the space of the refrigerant passage between the heat exchange tube 421a and the heat exchange tube 422b and the heat exchange tube 422a ) and the space of the refrigerant passage between the heat exchange tube (422b) was all increased. Therefore, the overall heat exchange efficiency of the evaporator according to this embodiment can still be improved, and the cost of the heat exchange tube can be reduced overall.

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 do not form two equilateral triangles, but the first Similar to the embodiment, the horizontal spacing between adjacent heat exchange tubes in different rows may be increased to form two isosceles triangles.

4C shows, for the same number of heat exchange tubes, the first heat exchange tube in the falling film tube bundle 415 in this embodiment, the second heat exchange tube in the falling film tube bundle 415 in this embodiment, and the first heat exchange tube under ideal circumstances. A falling film tube bundle comprising a first heat exchange tube under ideal circumstances, a liquid filled tube bundle comprising a second heat exchange tube under ideal circumstances, a falling film tube bundle comprising a second heat exchange tube under ideal circumstances. A comparison diagram of the theoretical value of the heat transfer coefficient of a single heat exchange tube in the tube bundle is shown, and the theoretical value is obtained through the Gaussian distribution equation (1). In Figure 4c, the abscissa represents different numbers of heat exchange pipes from top to bottom, and the ordinate represents the heat transfer coefficient. Here, straight line 461, straight line 462, straight line 463, and straight line 464 respectively represent a falling film tube bundle containing the first heat exchange tube under ideal circumstances, and a liquid fill containing the first heat exchange tube under ideal circumstances. It represents the heat transfer coefficient of a single heat exchange tube in a tube bundle, a falling film tube bundle comprising a second heat exchange tube under ideal circumstances, and a liquid filled tube bundle comprising a second heat exchange tube under ideal circumstances. Curve 460 and curve 470 respectively represent heat transfer coefficients of the first heat exchange tube and the second heat exchange tube of the falling film tube bundle 415 of the present embodiment.

As can be seen from FIG. 4C, in an ideal situation, the heat transfer coefficients of the falling film tube bundle and the liquid-filled tube bundle comprising the second heat exchange tube with a small tube diameter are respectively that of the falling film tube containing the first heat exchange tube with a large tube diameter. This demonstrates that larger and smaller diameter heat exchange tubes have better heat transfer coefficients than bundles and liquid-filled tube bundles. Additionally, a falling film tube bundle containing a small diameter secondary heat exchange tube can maintain a significant heat transfer coefficient in near-ideal situations, and the heat transfer coefficient does not significantly decrease as the number of rows is reduced. The heat transfer coefficient of the falling film tube bundle including the first heat exchange tube of large diameter is always higher than that of the liquid-filled tube bundle of the same diameter under ideal circumstances.

Figures 5a to 5c show a third embodiment of the evaporator of the present application. FIG. 5A is a radial cross-sectional view of the evaporator 500 according to the third embodiment of the evaporator of FIG. 2, FIG. 5B is a local enlarged view of four adjacent heat exchange tubes of the falling film tube bundle of FIG. 4A, and FIG. 5C. is a comparison diagram of the theoretical value of the heat transfer coefficient. As shown in FIGS. 5A and 5B, a falling film tube bundle 515 and a liquid filled tube bundle 516 are also installed in the evaporator 500, and the falling film tube bundle 515 and the liquid filled tube bundle 516 ) and a plurality of heat exchange tubes arranged in a row, where the heat exchange tubes in the liquid-filled tube bundle 516 and the arrangement method of the heat exchange tubes are the same as the first and second embodiments. In addition, the heat exchange tubes in the falling film tube bundle 515 include a plurality of first heat exchange tubes 521 with a large tube diameter (D ₁ ) and a plurality of second heat exchange tubes 522 with a small tube diameter (D ₂ ). do. The difference from the second embodiment is that a plurality of first heat exchange tubes 521 are arranged in a row, a plurality of second heat exchange tubes 522 are arranged in a row, and the heat of the first heat exchange tube 521 is exchanged with the second heat exchange tube. The rows of pipes 522 are arranged in a misaligned manner. As one embodiment, the large pipe diameter (D ₁ ) of the first heat exchange pipe 521 is the same as the pipe diameter (D ₀ ) of the heat exchange pipe 320 in the first embodiment. In this embodiment, the pipe diameter (D ₁ ) of the first heat exchange pipe 521 with a large pipe diameter is 1 inch, that is, 25.4 mm, and the pipe diameter (D ₂ ) of the second heat exchange pipe 522 with a small pipe diameter is 3/4. inch, or 19.05 mm. In the falling film tube bundle 515, the ratio of the number of first heat exchange tubes 521 and second heat exchange tubes 522 is about 1:1.

Figure 5b shows an enlarged structure of four adjacent heat exchange tubes (521a, 521b, 522a, 522b) in two adjacent rows. These heat exchange tubes are two adjacent, and the centers of the three adjacent heat exchange tubes form two equilateral triangles. form As shown in Figure 5b, the heat exchange tube 521a and the heat exchange tube 521b are located in the same row, and the heat exchange tube 522a and the heat exchange tube 522b are located in the same row. 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 the adjacent heat exchange tubes 521a and 522a in the same row have a vertical gap (H ₂ ). In the width direction W, the centers of the adjacent heat exchange tubes 521a and 522a in different rows have a horizontal gap W ₂ . There is a minimum gap (X ₂ ) between the outer surfaces of the heat exchange tube (521a) and the heat exchange tube (521b). There is a minimum gap (V ₂ ) between the outer surfaces of the heat exchange tube (522a) and the heat exchange tube (521b), and between the outer surfaces of the heat exchange tube (522a) and the heat exchange tube (521a). In this example, V ₂ is greater than X ₂ and W ₂ ≥D ₁ .

Similar to the second embodiment, this embodiment also replaces some of the first heat exchange pipes 521 with a large pipe diameter (D ₁ ) with second heat exchange pipes 522 with a small pipe diameter (D ₂ ), and some of the first heat exchange pipes 521 with a small pipe diameter (D 2 ). By reducing the pipe diameter of the heat exchange tube, the minimum gap (V ₁ ) of the outer surface is increased, thereby reducing the flow rate of gas flowing between the corresponding heat exchange tubes, thereby improving the heat exchange efficiency of the evaporator. Compared to the second embodiment, although V ₂ < V ₁ , the minimum distance between the outer surfaces of the heat exchange tubes between adjacent rows among the heat exchange tubes in each row of the falling film tube bundle 515 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 rows, the centers of the three adjacent heat exchange tubes do not form two equilateral triangles, but the first Similar to the embodiment, the horizontal spacing between adjacent heat exchange tubes in different rows may be increased to form two isosceles triangles.

5C shows the same number of heat exchange tubes, the first heat exchange tube in the falling film tube bundle 515 in this embodiment, the second heat exchange tube in the falling film tube bundle 515 in this embodiment, and the first heat exchange tube under ideal circumstances. A falling film tube bundle comprising a first heat exchange tube under ideal circumstances, a liquid filled tube bundle comprising a second heat exchange tube under ideal circumstances, a falling film tube bundle comprising a second heat exchange tube under ideal circumstances. A comparison diagram of the theoretical value of the heat transfer coefficient of a single heat exchange tube in the tube bundle is shown, and the theoretical value is obtained through the Gaussian distribution equation (1). In Figure 5c, the abscissa represents different numbers of heat exchange pipes from top to bottom, and the ordinate represents the heat transfer coefficient. Here, straight line 561, straight line 562, straight line 563, and straight line 564 respectively represent a falling film tube bundle containing the first heat exchange tube under ideal circumstances, and a liquid fill containing the first heat exchange tube under ideal circumstances. Indicates the heat transfer coefficient of a single heat exchange tube in a tube bundle, a falling film tube bundle including a second heat exchange tube under ideal circumstances, and a liquid-filled tube bundle containing a second heat exchange tube under ideal circumstances. Curve 560 and curve 570 respectively represent heat transfer coefficients of the first heat exchange tube and the second heat exchange tube of the falling film tube bundle 515 of the present embodiment.

As can be seen from FIG. 5C, 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 somewhat as the number of rows increases, but the heat transfer coefficient increases with the number of rows. is not significantly reduced, and is higher than the heat transfer coefficient of each liquid-filled tube bundle.

Figures 6a to 6c show a fourth embodiment of the evaporator of the present application. Figure 6a shows a radial cross-sectional view of the evaporator 600 according to the fourth embodiment of the evaporator of Figure 2, Figure 6b shows a structural schematic diagram of the baffle 631 of Figure 6a, and Figure 6c shows the theory of the heat transfer coefficient. It is also a value comparison. As shown in FIGS. 6A and 6B, a falling film tube bundle 615 and a liquid filled tube bundle 616 are installed in the evaporator 600, and the falling film tube bundle 615 and the liquid filled tube bundle 616 ) each includes a plurality of heat exchange tubes arranged in a row. In this embodiment, the heat exchange tube in the liquid-filled tube bundle 616 and the arrangement method of the heat exchange tube are the same as the first embodiment. In addition, since the heat exchange tubes in the falling film tube bundle 615 and the arrangement method of the heat exchange tubes are generally the same as those of the first embodiment, redundant description will be omitted here. The 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 passage 638 extending generally along the width direction (W).

The evaporator 600 includes a first baffle 631 and a second baffle 632, and the first baffle 631 and the second baffle 632 each extend in the width direction (W) of the falling film tube bundle 615. It is installed on the left and right sides of. A plurality of windows 635 are installed in each of the first baffle 631 and the second baffle 632, and these windows 635 are arranged along the longitudinal direction (L) and correspond to the fluid passage 638. installed in location. The fluid passage 638 and the window 635 can allow the gaseous refrigerant obtained through evaporation in the upper heat exchange pipe to flow out through the window 635 rather than continuing to flow through the lower heat exchange pipe. Accordingly, the flow rate of gaseous refrigerant flowing through the lower heat exchange pipe is reduced.

In this embodiment, even if the number of heat exchange tubes is the same as in the first embodiment, a part of the gaseous refrigerant may be discharged through the fluid passage 638 and the window 635, so that the flow rate of the gaseous refrigerant in the lower falling film tube bundle By reducing , the heat exchange efficiency of the evaporator can be further improved compared to the first embodiment.

Figure 6C shows, for the same number of heat exchange tubes, the falling film tube bundle 615 of the present embodiment, the falling film tube bundle 315 of the first embodiment, the falling film tube bundle under ideal circumstances, and the liquid-filled tube bundle under ideal circumstances. A comparison diagram of the theoretical value of the heat transfer coefficient of a single heat exchange tube is shown, and the theoretical value is obtained through the Gaussian distribution equation (1). In Figure 6c, the abscissa represents different numbers of heat exchange tubes from top to bottom, and the ordinate represents the heat transfer coefficient. Here, straight lines 661 and 662 represent the heat transfer coefficients of a single heat exchange tube in a falling film tube bundle and a liquid filled tube bundle under ideal circumstances, respectively. Curves 668 and 670 represent the heat transfer coefficients of the falling film tube bundle 615 of the present embodiment and the falling film tube bundle 315 of the first embodiment, respectively.

As can be seen from FIG. 6C, in the falling film tube bundle 615 of this embodiment, the heat transfer coefficient of each row of heat exchange tubes can be maintained at a high level by discharging part of the gaseous refrigerant from the central part.

Those skilled in the art will know that although the installation of the heat exchange pipe in the falling film tube bundle in this embodiment is generally the same as the first embodiment, the heat exchange pipe may be installed generally the same as the second embodiment or the third embodiment, or the heat exchange pipe may be installed generally the same as the second embodiment or the third embodiment. It can be understood that all that is necessary is to install a fluid passage in the falling film tube bundle of the third embodiment, and install a window for discharging gaseous refrigerant in the baffle corresponding to the fluid passage.

In the evaporator according to each of the above embodiments, the falling film tube bundle in the evaporator according to the first embodiment is arranged in the width direction (W) by increasing the distance between heat exchange tubes in the width direction, that is, the spacing of heat exchange tubes between each row. ) to increase the space of the refrigerant passage. The falling film tube bundle in the evaporator according to the second and third embodiments replaces part of the heat exchange tube with a heat exchange tube of a small diameter to increase the minimum gap between the outer surfaces of the tube walls of the heat exchange tube, so that at least part of the width direction ( W) increases the space of the refrigerant passage.

In the present application, by increasing the flow space of the refrigerant in the width direction (W), by reducing the flow rate of the gas flowing between the corresponding heat exchange tubes, the gas phase Reynolds number (Re _v ) and the liquid film Reynolds number (Re _film ) reduces the ratio, thereby improving the heat exchange efficiency of the evaporator.

Although only some features of the present application are shown and described herein, various modifications and changes can be made by those skilled in the art. Accordingly, it is to be understood that the appended claims are intended to cover all modifications and changes falling within the substantive scope of the present application.

Claims (10)

As an evaporator,
A shell 203 including a cavity 310 having a longitudinal direction (L), a width direction (W), and a height direction (H);
It is installed in the cavity 310 and arranged in a row, and includes a plurality of heat exchange tubes 320, each heat exchange tube 320 extending along the longitudinal direction (L) of the cavity 310, and one of the heat exchange tubes 320 in each row. The center of the heat exchange tube 320 is disposed along the height direction (H), and the centers of the two adjacent heat exchange tubes 320 in the adjacent row are arranged to be offset in the width direction (W) of the cavity 310. Including a falling film tube bundle 315;
The falling film tube bundle 315 has a minimum gap (V ₀ , V ₁ , V ₂ ) between the outer surfaces of the heat exchange tubes 320 of at least two different rows among the four adjacent heat exchange tubes 320 in two adjacent rows. ) is configured to be larger than _the minimum gap ₍ X ₀ , In claim 1,
Among the four adjacent heat exchange pipes 320 in two adjacent rows, by setting the gap between the outer surfaces of the heat exchange pipes 320 in at least two different rows, the gas flowing through the heat exchange pipes 320 in the two adjacent rows An evaporator characterized in that the heat exchange efficiency of the evaporator (100) is improved by reducing the flow rate. In claim 2,
Each heat exchange tube 320 of the falling film tube bundle 315 has the same pipe diameter (D ₀ ), and in the width direction (W) of the cavity 310 of the two heat exchange tubes 320 adjacent to each other in an adjacent row. of the center spacing (W ₀ ) and the center spacing (H ₀ ) in the height direction (H) of the cavity 310 of the two adjacent heat exchange tubes 320 in each row. the ratio An evaporator characterized by satisfying the. In claim 2,
The falling film tube bundle 415 includes a plurality of first heat exchange tubes 421 having a large tube diameter D1 and a plurality of second heat exchange tubes 422 having a small tube diameter D2;
An evaporator, characterized in that in the row of the falling film tube bundle (415), the first heat exchange tube (421) and the second heat exchange tube (422) are arranged to be offset. In claim 2,
The falling film tube bundle 515 includes a plurality of first heat exchange pipes 521 having a large pipe diameter D1 and a plurality of second heat exchange pipes 522 having a small pipe diameter D2, and a plurality of the first heat exchange pipes 522 having a small pipe diameter D2. 1 heat exchange tubes 521 are arranged in a row, and a plurality of the second heat exchange tubes 522 are arranged in a row;
An evaporator, characterized in that the heat of the first heat exchange tube (521) and the heat of the second heat exchange tube (522) are arranged to be offset. In claim 4 or claim 5,
In the two adjacent rows of heat exchange tubes 320, the center spacing ( The evaporator is characterized in that W1, W2) is larger than the large diameter D1 of the first heat exchange pipes (421, 521). In claim 6,
The large diameter D1 of the first heat exchange pipes 421 and 521 is 25.4 mm;
The evaporator, characterized in that the small pipe diameter (D2) of the second heat exchange pipes (422, 522) is 19.05 mm. The method of claim 1, wherein the evaporator,
It further includes a first baffle 631 and a second baffle 632, respectively installed on the outside of the cavity 310 in the width direction (W) of the falling film tube bundle 615;
The first baffle 631 and the second baffle 632 are each provided with a plurality of windows 635, and the plurality of windows 635 are arranged along the longitudinal direction (L) of the cavity 310, , The plurality of windows 635 are provided outside the center of the falling film tube bundle 615 in the height direction (H) of the cavity 310. In claim 8,
The first baffle 631 and the second baffle 632 are each provided with a liquid blocking baffle 638 outside the window 635 extending along the longitudinal direction (L) of the cavity 310, The top of the liquid blocking baffle 638 is connected to the corresponding first baffle 631 and the second baffle 632, and the liquid blocking baffle 638 is spaced from the window 635 at a certain distance. Characterized by an evaporator. In the refrigeration system,
A refrigeration system comprising a compressor (193), a condenser (191), a throttling device (192) installed in a refrigerant circuit, and an evaporator (100) according to any one of claims 1 to 9.