JP2019184228A - Shell-and-tube type heat exchanger and atomizing method in it - Google Patents

Abstract

To make supply amount distribution of the cooling medium reasonable on the surface of the heat transfer tube.SOLUTION: A shell-and-tube type heat exchanger (101) of the disclosure, comprises: a shell (201); a flat shaped heat transfer tube (202) through which a first fluid flows from an inlet to an outlet; and a nozzle (204) for atomizing a second fluid toward the heat transfer tube (202). When the point on the surface of the heat transfer tube (202), which is located at the same position from the inlet (202p) and the outlet (202q), is the intermediate point (P1); the amount of the second fluid sprayed from the nozzle (204) and reaching the range from the inlet (202p) to the intermediate point (P1) in the heat transfer tube (202) per unit time is defined as Q1; and the amount of the second fluid sprayed from the nozzle (204) and reaching the range from the outlet (202q) to the intermediate point (P1) in the heat transfer tube (202) per unit time is Q2, the relationship Q1>Q2 is satisfied.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a shell and tube heat exchanger and a spraying method therefor.

  FIG. 10 shows the configuration of the shell and tube heat exchanger described in Patent Document 1. The shell and tube heat exchanger described in Patent Literature 1 includes a shell 1, a flat heat transfer tube 2, a nozzle member 3, and a cooling medium inflow tube 4. The flat heat transfer tubes 2 are arranged in three rows and four stages. The cooling medium is ejected from the nozzle member 3 toward the flat heat transfer tube 2. The cooling medium comes into contact with the flat surface of the flat heat transfer tube 2 to exchange heat with the medium to be cooled flowing through the flat heat transfer tube 2.

JP2013-53620A

  If heat transfer tubes having a flat shape are used in a shell and tube heat exchanger, the heat transfer tube mounting density inside the shell can be increased, so the heat transfer area per unit volume of the shell and tube heat exchanger can be reduced. It is advantageous to increase. That is, using a heat transfer tube having a flat shape is advantageous for downsizing of the shell-and-tube heat exchanger.

  However, in the conventional shell and tube heat exchanger, the spray amount of the cooling medium is not sufficiently optimized. Dryout occurs where there is not enough spray. In locations where the spray amount is excessive, the cooling medium stays and forms a thick liquid film. As a result, the substantial heat transfer area is reduced, the cooling medium cannot be evaporated efficiently, and high heat transfer performance cannot be exhibited.

  The present disclosure provides a technique for optimizing the distribution of the supply amount of the cooling medium on the surface of the heat transfer tube in the shell-and-tube heat exchanger.

This disclosure
Shell,
A flat heat transfer tube located inside the shell and through which the first fluid flows from the inlet toward the outlet;
A spray method in a shell-and-tube heat exchanger, the nozzle being located inside the shell and spraying a second fluid toward the heat transfer tube,
A point on the surface of the heat transfer tube located equidistant from the inlet and the outlet is an intermediate point,
The amount of the second fluid sprayed from the nozzle and reaching the range from the inlet to the intermediate point in the heat transfer tube per unit time is defined as Q1,
When the amount of the second fluid sprayed from the nozzle and reaching the range from the outlet to the intermediate point in the heat transfer tube per unit time is Q2,
And spraying the second fluid from the nozzle toward the heat transfer tube so as to satisfy a relationship of Q1> Q2.
A spraying method is provided.

  According to the present disclosure, in the shell and tube heat exchanger, it is possible to optimize the distribution of the supply amount of the cooling medium on the surface of the heat transfer tube. Thereby, it is possible to avoid the formation of a liquid film having a thick cooling medium and the occurrence of dryout.

FIG. 1 is a configuration diagram of a refrigeration cycle apparatus using the shell-and-tube heat exchanger of the present disclosure. FIG. 2 is a longitudinal sectional view of the evaporator according to the first embodiment of the present disclosure. FIG. 3 is another longitudinal sectional view of the evaporator according to Embodiment 1 of the present disclosure. FIG. 4 is a cross-sectional view of the heat transfer tube. FIG. 5A is a diagram showing a spraying state of the refrigerant mist. FIG. 5B is a diagram showing a sprayed state of the refrigerant mist on the heat transfer tubes. FIG. 6A is a longitudinal sectional view of the spray nozzle. FIG. 6B is a cross-sectional view of the spray nozzle. FIG. 6C is a longitudinal sectional view of another spray nozzle. FIG. 7A is a diagram illustrating a positional relationship between a heat transfer tube and a spray nozzle. FIG. 7B is a diagram illustrating the posture of the spray nozzle according to the modification. FIG. 8A is a diagram illustrating a three-dimensional shape of the flow of the refrigerant mist. FIG. 8B is another diagram showing a three-dimensional shape of the flow of the refrigerant mist. FIG. 9 is a diagram showing the spread of the refrigerant mist in the direction in which the heat transfer tubes are arranged. FIG. 10 is a configuration diagram of a conventional heat exchanger using a flat heat transfer tube. FIG. 11A is a diagram showing a diffusion state of the cooling medium sprayed from the spray nozzle to the heat transfer tube. FIG. 11B is a diagram illustrating a diffusion state of the cooling medium sprayed from the spray nozzle to the heat transfer tube. FIG. 12 is a diagram illustrating a spray state in the configuration of the reference example.

(Knowledge that became the basis of the present invention)
As a result of diligent studies, the present inventors have found that dry-out occurs remarkably in a fin-and-tube heat exchanger configured using a flat heat transfer tube. The reason is as follows.

  FIG. 11A shows a diffusion state of the cooling medium sprayed from the spray nozzle 11 to the heat transfer tube 12. The heat transfer tube 12 is a heat transfer tube having a circular cross section. The cooling medium is sprayed from the spray nozzle 11 toward the heat transfer tube 12 at a constant flow rate. The sprayed cooling medium reaches the heat transfer tube 12 in a mist state. FIG. 11A shows in a circular arc how the mist-state cooling medium sprayed from the spray nozzle 11 moves forward over time. As shown in FIG. 11A, in the heat transfer tube 12, a point where the distance to the inlet of the heat transfer tube 12 and the distance to the outlet are equal is defined as an intermediate point M1. The upper end of the heat transfer tube 12 is an inlet, and the lower end of the heat transfer tube 12 is an outlet. An arc including the intermediate point M1 of the heat transfer tube 12 is defined as an arc a1, and an arc including the inlet of the heat transfer tube 12 is defined as an arc b1. The spray nozzle 11 is disposed at the height of the intermediate point M1 of the heat transfer tube 12.

  When the mist of the cooling medium has advanced to the position of the arc a1, the mist contacts the intermediate point M1 of the heat transfer tube 12. When the mist advances to the position of the arc b1, the mist contacts the inlet and outlet (upper end and lower end) of the heat transfer tube 12. Since the arc a1 is shorter than the arc b1, the density of mist particles on the arc b1 is lower than the density of mist particles on the arc a1. When the fin-and-tube heat exchanger is an evaporator, the temperature difference between the fluid flowing in the heat transfer tube 12 and the mist is the largest at the inlet of the heat transfer tube 12 and the smallest at the outlet of the heat transfer tube 12. Therefore, when the fin-and-tube heat exchanger is an evaporator, dryout is most likely to occur near the inlet of the heat transfer tube 12.

  The fact that dryout tends to occur near the inlet applies to both heat exchanger tubes with a circular cross section and flat heat transfer tubes. However, in the flat heat transfer tube, dryout near the inlet becomes more obvious. The reason is as follows.

  FIG. 11B shows, in the same manner as FIG. 11A, a circular arc of the mist state of the cooling medium sprayed from the spray nozzle 11 moving forward with time. The heat transfer tube 13 is a heat transfer tube having a flat shape. The heat transfer tube 13 has a wide width with respect to the traveling direction of the mist. Therefore, the density of the mist particles existing on the arc c1 when the mist advances to the position of the arc c1 is higher than the density of the mist particles existing on the arc a1 when the mist advances to the position of the arc a1. It is lower than the density of the mist particles existing on the arc b1 when the mist advances to the position of the arc b1. That is, a sufficient amount of the cooling medium cannot be supplied to a portion in the vicinity of the inlet of the heat transfer tube 13 that is located on the side far from the spray nozzle 11, and dryout is more likely to occur in that portion. In the flat heat transfer tube 13, there is an uneven supply amount of the cooling medium not only in the longitudinal direction but also in the width direction, which can be said to promote the occurrence of dryout.

  Based on the above findings, the present inventors have arrived at each aspect according to the present disclosure.

The spray method in the shell and tube heat exchanger according to the first aspect of the present disclosure is:
Shell,
A flat heat transfer tube located inside the shell and through which the first fluid flows from the inlet toward the outlet;
A spray method in a shell-and-tube heat exchanger, the nozzle being located inside the shell and spraying a second fluid toward the heat transfer tube,
A point on the surface of the heat transfer tube located equidistant from the inlet and the outlet is an intermediate point,
The amount of the second fluid sprayed from the nozzle and reaching the range from the inlet to the intermediate point in the heat transfer tube per unit time is defined as Q1,
When the amount of the second fluid sprayed from the nozzle and reaching the range from the outlet to the intermediate point in the heat transfer tube per unit time is Q2,
And spraying the second fluid from the nozzle toward the heat transfer tube so as to satisfy a relationship of Q1> Q2.
including.

  According to the first aspect of the present disclosure, in the shell-and-tube heat exchanger, the distribution of the supply amount of the cooling medium on the surface of the heat transfer tube can be optimized. Thereby, it is possible to avoid the formation of a liquid film having a thick cooling medium and the occurrence of dryout.

  In the second aspect of the present disclosure, for example, in the spraying method according to the first aspect, the nozzle may spray the second fluid stored at the bottom of the shell toward the heat transfer tube. According to the second aspect, it is easy to recover the liquid phase refrigerant, and energy consumption for supplying the liquid phase refrigerant to the nozzle can be suppressed.

  In the third aspect of the present disclosure, for example, in the spraying method according to the first or second aspect, the amount of the second fluid that reaches the heat transfer tube per unit time gradually decreases from the inlet toward the outlet. As described above, the second fluid may be sprayed from the nozzle toward the heat transfer tube. According to the third aspect, the distribution of the supply amount of the liquid-phase refrigerant on the surface of the heat transfer tube can be further optimized.

  In the fourth aspect of the present disclosure, for example, the spraying method according to any one of the first to third aspects may further include flowing the first fluid through the heat transfer tube.

The shell and tube heat exchanger according to the fifth aspect of the present disclosure is:
Shell,
A flat heat transfer tube located inside the shell and through which the first fluid flows from the inlet toward the outlet;
A nozzle located inside the shell and spraying a second fluid toward the heat transfer tube;
With
A point on the surface of the heat transfer tube located equidistant from the inlet and the outlet is an intermediate point,
The amount of the second fluid sprayed from the nozzle and reaching the range from the inlet to the intermediate point in the heat transfer tube per unit time is defined as Q1,
When the amount of the second fluid sprayed from the nozzle and reaching the range from the outlet to the intermediate point in the heat transfer tube per unit time is Q2,
The relationship of Q1> Q2 is satisfied.

  According to the fifth aspect of the present disclosure, in the shell and tube heat exchanger, the distribution of the supply amount of the cooling medium on the surface of the heat transfer tube can be optimized. Thereby, it is possible to avoid the formation of a liquid film having a thick cooling medium and the occurrence of dryout.

  In the sixth aspect of the present disclosure, for example, in the shell and tube heat exchanger according to the fifth aspect, the nozzle sprays the second fluid stored in the bottom of the shell toward the heat transfer tube. Also good. According to the sixth aspect, it is easy to recover the liquid phase refrigerant, and energy consumption for supplying the liquid phase refrigerant to the nozzle can be suppressed.

  In the seventh aspect of the present disclosure, for example, in the shell and tube heat exchanger according to the fifth or sixth aspect, the amount of the second fluid sprayed from the nozzle and reaching the heat transfer tube per unit time is It may be gradually decreased from the inlet toward the outlet. According to the seventh aspect, the distribution of the supply amount of the liquid phase refrigerant on the surface of the heat transfer tube can be further optimized.

  In the eighth aspect of the present disclosure, for example, in the shell-and-tube heat exchanger according to any one of the fifth to seventh aspects, the nozzle includes an introduction portion that allows the second fluid to flow in, and the introduction portion. And a mist forming part for increasing the speed of the second fluid, and a mist forming part connected to the jet hole for making the second fluid into a mist shape. When viewed from a direction perpendicular to the surface, the central axis of the ejection hole may be located between the inlet and the intermediate point in the vertical direction, and the mist forming portion is located on the upper side in the vertical direction. An angle α between the first surface and the central axis of the ejection hole may be included, and the first surface may be included in the vertical direction. The angle between the two surfaces and the central axis of the ejection hole is an angle β. Alternatively, the relationship of the angle α <the angle β may be satisfied. According to the eighth aspect, it is possible to spray an appropriate amount of the liquid phase refrigerant according to the temperature difference between the water and the liquid phase refrigerant in the local area of the heat transfer tube. And it becomes possible to suppress the reduction | decrease of the heat-transfer area by dryout and / or the stay of the non-evaporated refrigerant. Furthermore, it becomes possible to evaporate a liquid phase refrigerant | coolant efficiently and can improve heat transfer performance.

  In the ninth aspect of the present disclosure, for example, in the shell-and-tube heat exchanger according to any one of the fifth to eighth aspects, the distance between the nozzle and the inlet of the heat transfer tube is the nozzle. And the distance between the outlet of the heat transfer tube. According to such a configuration, it is easy to optimize the distribution of the supply amount of the liquid phase refrigerant on the surface of the heat transfer tube.

  In the tenth aspect of the present disclosure, for example, in the shell and tube heat exchanger according to any one of the fifth to ninth aspects, the flow of the second fluid from the nozzle toward the heat transfer tube is changed to the second. When observed by cutting in a direction perpendicular to the fluid flow direction, the outer edge of the second fluid flow may have a rectangular shape. According to such a configuration, it is possible to spray the liquid phase refrigerant in a shape corresponding to the heat transfer tubes arranged in the rectangular region.

  In the eleventh aspect of the present disclosure, for example, in the shell and tube heat exchanger according to the tenth aspect, the rectangular shape has a pair of short sides parallel to a direction perpendicular to the flat surface of the heat transfer tube. It may be a shape. According to such a configuration, it is possible to spray the liquid phase refrigerant in a shape corresponding to the heat transfer tubes arranged in the rectangular region.

A refrigeration cycle apparatus according to a twelfth aspect of the present disclosure is provided.
A shell and tube heat exchanger according to any one of the fifth to eleventh aspects;
A compressor,
It has.

  By efficiently evaporating the refrigerant in the evaporator or condensing the refrigerant efficiently in the condenser, the efficiency (COP) of the refrigeration cycle can be improved.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited by the embodiment.

(Embodiment)
FIG. 1 shows a configuration of a refrigeration cycle apparatus using the shell-and-tube heat exchanger of the present disclosure. The refrigeration cycle apparatus 100 includes an evaporator 101, a compressor 102, a condenser 103, a flow valve 104, and flow paths 110a to 110d. The outlet of the evaporator 101 is connected to the suction port of the compressor 102 by a flow path 110a. The outlet of the compressor 102 is connected to the inlet of the condenser 103 by a flow path 110b. The outlet of the condenser 103 is connected to the inlet of the flow valve 104 by a flow path 110c. The outlet of the flow valve 104 is connected to the inlet of the evaporator 101 by a flow path 110d. The flow paths 110a and 110b are vapor paths, and the flow paths 110c and 110d are liquid paths. Each path is composed of, for example, at least one metal pipe.

  When the compressor 102 is started, the refrigerant is heated and evaporated in the evaporator 101. Thereby, a gaseous-phase refrigerant | coolant (refrigerant vapor | steam) is produced | generated. The generated gas phase refrigerant is sucked into the compressor 102 and compressed. The gas-phase refrigerant that has been compressed to high temperature and pressure is supplied from the compressor 102 to the condenser 103. The supplied high-temperature and high-pressure gas-phase refrigerant is cooled by the condenser 103 to be condensed and liquefied to generate a liquid-phase refrigerant (refrigerant liquid). The liquid phase refrigerant is returned as a liquid phase refrigerant from the condenser 103 to the evaporator 101 via the flow valve 104.

  The refrigeration cycle apparatus 100 is an air conditioner for business use or home use, for example. The to-be-cooled medium cooled by the evaporator 101 is supplied into the room and used for indoor cooling. Or the to-be-cooled medium heated with the condenser 103 is supplied indoors, and is utilized for indoor heating. The medium to be cooled is, for example, water. However, the refrigeration cycle apparatus 100 is not limited to an air conditioner, and may be another apparatus such as a chiller or a heat storage apparatus.

  In this embodiment, the phrase “water” is used instead of the phrase “cooled medium”. However, the medium to be cooled as the first fluid flowing through the heat transfer tube 202 is not limited to water, and may be a liquid such as oil or brine, or may be a gas such as air.

  FIG. 2 is a vertical sectional view of the evaporator 101 (AA cross section in FIG. 1). As shown in FIG. 2, the evaporator 101 is configured by a shell and tube heat exchanger. Specifically, the evaporator 101 includes a shell 201, a heat transfer pipe 202, a header 203, a spray nozzle 204, a circulation circuit 205, a circulation pump 206, an inflow pipe 207, and an outflow pipe 208. The heat transfer tube 202, the header 203, the spray nozzle 204, the circulation circuit 205, and the circulation pump 206 are disposed inside the shell 201. By efficiently evaporating the refrigerant in the evaporator 101, the efficiency (COP) of the refrigeration cycle can be improved.

  A flow path 110d and a flow path 110a can be connected to the inflow pipe 207 and the outflow pipe 208, respectively.

  The heat transfer tube 202 is a multi-hole and flat heat transfer tube. Water flows from the inlet of the heat transfer tube 202 toward the outlet. A plurality of heat transfer tubes 202 are arranged between the header 203 and the header 203 so that the flat surface is parallel to the vertical direction. Examples of the material of the heat transfer tube 202 include metal materials such as aluminum, aluminum alloy, and stainless steel. The circuit 105 that circulates water (first fluid) through the heat transfer tube 202 may be a sealed circuit that is isolated from the outside air.

  In the present embodiment, the heat transfer tubes 202 are arranged in three stages in the vertical direction. The amount of the liquid-phase refrigerant to be sprayed may be equal or different at each stage.

  The shell 201 is configured to store a liquid-phase refrigerant at the bottom thereof. The circulation circuit 205 connects the bottom of the shell 201 and each of the spray nozzles 204. A circulation pump 206 is disposed in the circulation circuit 205. By the action of the circulation pump 206, the liquid refrigerant stored at the bottom of the shell 201 is supplied to the spray nozzle 204 through the circulation circuit 205. According to such a configuration, it is easy to recover the liquid phase refrigerant, and energy consumption for supplying the liquid phase refrigerant to the spray nozzle 204 can be suppressed.

  The spray nozzle 204 is arranged to spray the liquid refrigerant from the side toward the heat transfer tube 202 in the horizontal direction. Specifically, the spray nozzle 204 faces the side surface of the heat transfer tube 202 and sprays the liquid phase refrigerant toward the heat transfer tube 202 from a direction parallel to the flat surface. In the present embodiment, as an example, the spray nozzle 204 is disposed at the same height as the inlet of the heat transfer tube 202 in the vertical direction. In this embodiment, water flows through the heat transfer tube 202 from the top to the bottom of the drawing. A liquid phase refrigerant is an example of the 2nd fluid which should exchange heat with water which is an example of the 1st fluid.

  In this specification, the position of “the inlet of the heat transfer tube 202” means the uppermost position on the surface of the heat transfer tube 202 to which the liquid refrigerant sprayed from the spray nozzle 204 can directly reach. The position of “the outlet of the heat transfer tube 202” means the lowest position on the surface of the heat transfer tube 202 to which the liquid refrigerant sprayed from the spray nozzle 204 can directly reach. For example, when the end of the heat transfer tube 202 is located inside the header 203, the liquid refrigerant cannot reach the surface of the end directly. Therefore, the position of the “inlet of the heat transfer tube 202” does not necessarily match the position of the open end of the heat transfer tube 202. The position of the “outlet of the heat transfer tube 202” does not necessarily coincide with the open end of the heat transfer tube 202.

  In this embodiment, the shell 201 has a rectangular cross-sectional shape, but may have a circular cross-sectional shape. The shell 201 may be a pressure vessel.

  FIG. 3 shows a CC cross section of the evaporator in FIG.

  The heat transfer tube 202 extends from the lower part of the shell 201 to the upper part in the vertical direction, and is disposed inside the shell 201. Both ends of the heat transfer tube 202 in the vertical direction are connected to the header 203. Water flows into the heat transfer tube 202. The method of flowing water through the heat transfer tube 202 may be another method that does not use a header.

  The second fluid from the spray nozzle 204 toward the heat transfer tube 202 so that the amount of the liquid refrigerant reaching the heat transfer tube 202 per unit time gradually decreases from the inlet of the heat transfer tube 202 toward the outlet of the heat transfer tube 202. Is sprayed. Details will be described later.

  The inlet of the header 203 is connected to the tube plate cover 209a. The outlet of the header 203 is connected to the tube plate cover 209b. The tube plate cover 209a is provided with an inlet tube 301 through which water flows in, and the tube plate cover 209b is provided with an outlet tube 302 through which water exchanged in the heat transfer tube 202 flows out. That is, water flows into the evaporator 101 from the inlet pipe 301 located at the lower part of the shell 201. Then, the water flows out of the evaporator 101 from the outlet pipe 302 located at the upper part of the shell 201 via the plurality of headers 203 and the heat transfer pipes 202.

  Further, the flow path inside the tube plate cover 209 is partitioned by a partition plate 303. The inside of the tube sheet covers 209a and 209b is partitioned so that water flowing out from the header 203 flows into the header 203 directly above.

  FIG. 4 is an enlarged view of a cross section of the heat transfer tube 202. The heat transfer tube 202 includes an outer wall 401 and a partition wall 402, and a space surrounded by the outer wall 401 and the partition wall 402 serves as a water flow path 403. The outer wall 401 and the partition 403 are thin plates, and have a thickness of about 0.5 to 0.8 mm, for example. On the other hand, the cross-sectional shape of the flow path 403 is rectangular in this embodiment. The flow path 403 has, for example, a narrow tube shape having a square cross section with a side of about 0.5 mm to 3 mm. In the present embodiment, the cross-sectional shape of the channel 403 is a quadrangle, but it may be a circle or a triangle. Further, the surface area may be increased by forming fine grooves or fins on the inner wall surface of the flow path 403.

  The compressor 102 may be a speed type compressor such as a centrifugal compressor, or may be a positive displacement compressor such as a scroll compressor.

  The type of the condenser 103 is not particularly limited. A heat exchanger such as a plate heat exchanger or a shell and tube heat exchanger may be used for the condenser 103.

  About the evaporator 101 comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  In the evaporator 101, the liquid phase refrigerant is heated and evaporated. The vaporized low-temperature and low-pressure gas-phase refrigerant is sucked into the compressor 102 through the flow path 110a and compressed into the high-temperature and high-pressure gas-phase refrigerant. The compressed high-temperature and high-pressure gas-phase refrigerant flows into the condenser 103 through the flow path 110b. The high-temperature and high-pressure gas-phase refrigerant that has flowed into the condenser 103 is cooled in the condenser 103 to be condensed and liquefied. The condensed and liquefied high-pressure liquid refrigerant is returned to the evaporator 101 as a low-pressure liquid refrigerant from the flow passage 110d while being depressurized through the flow valve 104 through the flow passage 110c.

  The flow state of the refrigerant mist sprayed from the spray nozzle 204 in such a refrigeration cycle will be described. FIG. 5A shows the spray state of the refrigerant mist.

  In the evaporator 101, the liquid-phase refrigerant pumped by the circulation pump 206 is sprayed from the spray nozzle 204 toward the heat transfer tube 202 as an atomized refrigerant liquid through the circulation circuit 205.

  As shown in FIG. 5A, the liquid-phase refrigerant is sprayed in the horizontal direction from the spray nozzle 204 and reaches the heat transfer tube 202 while expanding radially. Thereby, the liquid phase refrigerant is sprayed from the inlet to the outlet of the heat transfer tube 202. The angle of the refrigerant mist spreading downward in the vertical direction is represented by an angle β (unit: degree) with respect to the horizontal direction. The angle β is an angle formed by a plane passing through the lower limit of the refrigerant mist flow and a plane parallel to the horizontal direction.

  FIG. 5B shows the amount of refrigerant mist sprayed onto the heat transfer tube 202. A point on the surface of the heat transfer tube 202 located at an equal distance from the inlet 202p of the heat transfer tube 202 and the outlet 202q of the heat transfer tube 202 is defined as an intermediate point P1. The amount of liquid-phase refrigerant sprayed from the spray nozzle 204 and reaching the range from the inlet 202p to the intermediate point P1 in the heat transfer tube 202 per unit time is defined as Q1. The amount of liquid-phase refrigerant sprayed from the spray nozzle 204 and reaching the range from the outlet 202q in the heat transfer tube 202 to the intermediate point P1 per unit time is defined as Q2. In the present embodiment, the liquid phase refrigerant is sprayed from the spray nozzle 204 toward the heat transfer tube 202 so as to satisfy the relationship of Q1> Q2.

  When the liquid phase refrigerant is sprayed from the spray nozzle 204 toward the heat transfer tube 202 while flowing water through the heat transfer tube 202, the water in the heat transfer tube 202 is cooled by the liquid phase refrigerant. The temperature of water is high in the vicinity of the inlet 202p of the heat transfer tube 202 and is low in the vicinity of the outlet 202q of the heat transfer tube 202. When the liquid refrigerant is sprayed from the spray nozzle 204 toward the heat transfer tube 202 so as to satisfy the relationship of Q1> Q2, it is difficult for dryout to occur near the inlet 202p, and near the intermediate point P1 and the outlet 202q. Liquid phase refrigerant is unlikely to be excessive. That is, according to the present embodiment, the distribution of the supply amount of the liquid phase refrigerant on the surface of the heat transfer tube 202 can be optimized. Thereby, it is possible to avoid the formation of a thick liquid film of the liquid phase refrigerant or the occurrence of dryout. As a result, the heat exchange performance of the evaporator 101 can be sufficiently exhibited.

  FIG. 6A shows a longitudinal section of the spray nozzle 204. FIG. 6B shows a cross section of the spray nozzle 204. The spray nozzle 204 includes an introduction part 501, an ejection hole 502, and a mist formation part 504. The introduction unit 501 is a part that allows liquid phase refrigerant to flow through the circulation circuit 205. The ejection hole 502 is a part connected to the introduction part 501. The flow passage cross-sectional area of the ejection hole 502 is smaller than the flow passage cross-sectional area of the introduction portion 501. Accordingly, the speed of the liquid refrigerant increases in the ejection holes 502. In the present embodiment, the introduction part 501 has a circular cross section and a constant flow path cross-sectional area. The ejection hole 502 also has a circular cross section and a constant flow path cross-sectional area. The mist formation part 504 is a part connected to the ejection hole 502 and has a function of making the liquid phase refrigerant into a mist. At the outlet 503 of the ejection hole 502, a mist forming part 504 is connected to the ejection hole 502. The mist formation part 504 has the 1st surface 505 and the 2nd surface 506 as the inner surface. The first surface 505 is a surface located on the upper side in the vertical direction. The second surface 506 is a surface located on the lower side in the vertical direction. The first surface 505 and the second surface 506 are flat surfaces extending toward the inlet 202p of the heat transfer tube 202 and the outlet 202q of the heat transfer tube 202, respectively.

  However, the spray nozzle applicable to the evaporator 101 is not limited to the thing of this embodiment.

  In the present embodiment, the central axis O of the spray nozzle 204 passing through the centers of the introduction portion 501 and the ejection hole 502 is parallel to the horizontal direction. “Parallel in the horizontal direction” does not necessarily mean that it is mathematically completely parallel. Taking into account manufacturing errors and assembly errors, for example, even if the central axis O is inclined ± 1 degree with respect to the horizontal direction, the central axis O can be regarded as being parallel to the horizontal direction. However, as will be described later, the central axis O may not be parallel to the horizontal direction.

  The liquid-phase refrigerant that has flowed from the introduction unit 501 is ejected through the ejection hole 502. When viewed from the direction perpendicular to the flat surface of the heat transfer tube 202, the central axis O of the introduction portion 501 and the ejection hole 502 is located between the inlet 202p and the intermediate point P1 (see FIG. 5B) in the vertical direction. The liquid phase refrigerant is ejected radially around the outlet 503 of the ejection hole 502. The liquid-phase refrigerant is changed in the horizontal direction by the first surface 505 (the upper surface in FIG. 6A) of the mist forming unit 504 and is ejected.

  The first surface 505 of the mist forming unit 504 is located near the inlet 202p of the heat transfer tube 202. The distance from the first surface 505 to the inlet 202p is shorter than the distance from the second surface 506 to the inlet 202p, for example. An angle formed by the first surface 505 and the central axis O is defined as an angle α (degrees).

  As shown in FIG. 6A, the second surface 506 of the mist forming portion 504 is inclined at an angle θ with respect to a surface parallel to the vertical direction.

  In FIG. 6A, the second surface 506 is located near the outlet 202q of the heat transfer tube 202. An angle formed by the second surface 506 and the central axis O is defined as an angle β (degrees).

  The angle β can be adjusted, for example, such that the surface passing through the lower limit of the refrigerant mist flow passes through the outlet 202q of the heat transfer tube 202.

  FIG. 6C is a diagram illustrating an example of the mist forming unit 504 when the angle α is 0 degrees. The first surface 505 is parallel to the horizontal direction.

  The mist forming unit 504 satisfies the relationship of angle α <angle β. As a result, an appropriate amount of the liquid phase refrigerant can be sprayed according to the temperature difference between the water and the liquid phase refrigerant in the local area of the heat transfer tube 202. And it becomes possible to suppress the reduction | decrease of the heat-transfer area by dryout and / or the stay of the non-evaporated refrigerant. Furthermore, it becomes possible to evaporate a liquid phase refrigerant | coolant efficiently and can improve heat transfer performance.

  FIG. 12 shows the spray state of the refrigerant mist when the central axis O1 of the spray nozzle 601 is located at the intermediate point between the inlet 602p and the outlet 602q of the heat transfer tube 602. The hatched portion of the heat transfer tube 602 represents a region (s1) in which the liquid-phase refrigerant sprayed at the same time can reach within a predetermined time. The region other than the shaded portion of the heat transfer tube 602 is a region (s2) where the liquid-phase refrigerant sprayed at the same time does not reach within a predetermined time.

  In the example shown in FIG. 12, the liquid phase refrigerant is sprayed radially in the vertical direction of the central axis O <b> 1 of the spray nozzle 601. An angle formed by a straight line passing through the outlet 602q of the heat transfer tube 602 and the spray nozzle 601 and a plane parallel to the horizontal direction (a plane including the central axis O1) is defined as an angle δ. An angle formed between a specific locus of the refrigerant mist and a plane parallel to the horizontal direction is defined as an angle γ. As the angle γ increases, the horizontal width (L) of the region s1 in which the refrigerant mist can reach within a predetermined time is shortened. The width L is a horizontal distance from the side surface of the heat transfer tube 602 to the outer edge of the region s1. When the central axis O1 of the spray nozzle 601 is set as a reference (= 0 degree), the transmission that can be wetted by the liquid-phase refrigerant sprayed at the same time as the angle γ approaches the angle δ between 0 ≦ γ ≦ δ. The horizontal area of the heat pipe 602 is reduced. In other words, the amount of spray per unit area in the horizontal direction decreases as the angle γ approaches the angle δ between 0 ≦ γ ≦ δ.

  The temperature difference between the water flowing in the heat transfer tube 602 and the refrigerant is the largest at the inlet 602p of the heat transfer tube 602. In order to achieve efficient heat exchange, the most refrigerant mist is required in the vicinity of the inlet 602p of the heat transfer tube 602. However, according to the configuration of FIG. 12, a sufficient amount of refrigerant mist may not be supplied to the upstream portion (portion from the inlet 602p to the intermediate point) of the heat transfer tube 602, and dryout may occur. An excessive amount of refrigerant mist may be supplied in the vicinity of the intermediate point to form a thick liquid film of liquid phase refrigerant.

  As described with reference to FIG. 5B, according to the present embodiment, a sufficient amount of the refrigerant mist is supplied to the upstream portion from the inlet 202p to the intermediate point P1, thereby preventing the occurrence of dryout and improving the efficiency. Heat exchange can be achieved. Since the refrigerant mist is not supplied excessively in the vicinity of the intermediate point P1, it is difficult to form a thick liquid film of the liquid phase refrigerant.

  In particular, according to the spray nozzle 204c described with reference to FIG. 6C, the refrigerant mist is sprayed while being concentrated in the formation direction of the first surface 505, so that the refrigerant mist is sprayed at a high density in the horizontal direction. .

  Since the water flowing through the heat transfer tube 202 is heat-exchanged with a low-temperature liquid refrigerant sprayed at a constant temperature, the temperature gradually decreases from the inlet 202p to the outlet 202q of the heat transfer tube 202. That is, the temperature difference between the temperature of the water flowing through the heat transfer tube 202 and the liquid phase refrigerant is greatest at the inlet 202p of the heat transfer tube 202 and decreases as it goes toward the outlet 202q.

  In the same heat transfer area, the smaller the temperature difference between water and the liquid refrigerant, the smaller the amount of heat that can be exchanged. That is, the flow rate of the liquid phase refrigerant that can be evaporated is also reduced.

  According to this embodiment, the flow rate of the liquid phase refrigerant reaching the heat transfer tube 202 is maximized at the position of the inlet 202p of the heat transfer tube 202 where the temperature difference between water and the liquid phase refrigerant is the largest. As it goes from the inlet 202p to the outlet 202q of the heat transfer tube 202, the temperature difference between water and the liquid phase refrigerant gradually decreases, and the flow rate of the liquid phase refrigerant gradually decreases. According to this embodiment, the liquid phase refrigerant is sprayed at an appropriate flow rate according to the temperature difference between the water in the heat transfer tube 202 and the liquid phase refrigerant. Specifically, the liquid-phase refrigerant is sprayed from the spray nozzle 204 toward the heat transfer tube 202 so that the amount of the liquid-phase refrigerant reaching the heat transfer tube 202 per unit time gradually decreases from the inlet 202p toward the outlet 202q. Is done. In other words, the liquid-phase refrigerant is sprayed so that the spray density gradually decreases from the inlet 202p of the heat transfer tube 202 toward the outlet 202q. In this way, the distribution of the supply amount of the liquid phase refrigerant on the surface of the heat transfer tube 202 can be further optimized.

  Further, since the liquid phase refrigerant is sprayed horizontally along the first surface 505 of the spray nozzle 204, the liquid phase refrigerant is directly sprayed in the vicinity of the inlet 202p of the heat transfer tube 202 arranged vertically. That is, the refrigerant mist escaping above the heat transfer tube 202 can be greatly reduced. For this reason, it is less likely that the refrigerant mist collides with the header 203, and the reattachment of surplus refrigerant flowing down from the header 203 to the heat transfer surface of the heat transfer tube 202 due to the collision is suppressed.

  FIG. 7A shows the positional relationship between the heat transfer tube 202 and the spray nozzle 204. In the present embodiment, the distance L1 between the spray nozzle 204 and the inlet 202p of the heat transfer tube 202 is shorter than the distance L2 between the spray nozzle 204 and the outlet 202q of the heat transfer tube 202. According to such a configuration, it is easy to optimize the distribution of the supply amount of the liquid phase refrigerant on the surface of the heat transfer tube 202.

  In the present embodiment, the straight line connecting the spray nozzle 204 and the inlet 202p of the heat transfer tube 202 is the central axis O of the spray nozzle 204 and intersects the front edge 202f of the heat transfer tube 202 perpendicularly.

  FIG. 7B is a diagram illustrating the posture of the spray nozzle 204 according to a modified example. The liquid phase refrigerant is sprayed radially from the spray nozzle 204. The spray angle of the liquid refrigerant is β1. The central axis O of the spray nozzle 204 is inclined β1 / 2 (degrees) downward from the horizontal direction. According to such an arrangement, the plane passing through the upper limit of the refrigerant mist flow is substantially parallel to the horizontal direction, so that the refrigerant mist passing through the upper portion of the inlet 202p of the heat transfer tube 202 can be reduced. Of course, as described with reference to FIGS. 6A to 6C, by appropriately adjusting the angle of the first surface 505 of the mist forming portion 504 of the spray nozzle 204, without changing the posture of the spray nozzle 204, The same effect can be obtained.

  8A and 8B show the three-dimensional shape of the flow of the refrigerant mist. FIG. 9 shows the expansion of the refrigerant mist in the direction in which the heat transfer tubes 202 are arranged. FIG. 9 shows a state where the heat transfer tube 202 and the refrigerant mist are observed from the vertical direction. The flow of the refrigerant mist is the flow of the liquid phase refrigerant from the spray nozzle 204 toward the heat transfer tube 202. When the flow of the refrigerant mist is cut and observed in a direction perpendicular to the flow direction of the refrigerant mist, the outer edge of the flow of the refrigerant mist shows a rectangular shape. The locus of the refrigerant mist forms a three-dimensional shape of a square pyramid. The rectangular shape is a shape having a pair of short sides parallel to a direction perpendicular to the flat surface of the heat transfer tube 202. According to such a configuration, it is possible to spray the liquid phase refrigerant in a shape corresponding to the heat transfer tubes 202 arranged in the rectangular region. For this reason, in the plurality of heat transfer tubes 202, it is possible to prevent occurrence of a portion where the refrigerant mist cannot reach and improve the wettability of the refrigerant mist. In particular, it is possible to prevent occurrence of a portion where the refrigerant mist cannot reach the four corner regions of the rectangular region.

  As described with reference to FIG. 5A, when the nozzle 204 is configured to satisfy the relationship of angle α <angle β, it is easy to form a three-dimensional shape of the refrigerant mist as shown in FIG. 8A. The flow direction of the refrigerant mist is, for example, a direction parallel to the central axis O. When the flow of the refrigerant mist is observed by being cut by a plane perpendicular to the central axis O, the position of the central axis O is offset to the inlet side of the heat transfer tube 202. Thereby, it is possible to form an ideal spray amount distribution from the inlet 202p of the heat transfer tube 202 toward the outlet 202q.

  As shown in FIG. 8B, the flow of the refrigerant mist shows a rectangular shape having a horizontal length H and a vertical length V. The length H in the horizontal direction is smaller than the length V in the vertical direction. In this case, as shown in FIG. 9, since the spray angle β2 of the refrigerant mist with respect to the heat transfer tube 202 becomes small, the refrigerant mist easily passes between the heat transfer tube 202 and the heat transfer tube 202. Since a sufficient amount of the refrigerant mist is also supplied to a portion located on the side far from the spray nozzle 204, further improvement in heat transfer performance can be expected.

  As described with reference to FIGS. 6A to 6C, the three-dimensional shape of the flow of the refrigerant mist can be controlled by the shape of the mist forming portion 504 of the spray nozzle 204.

  According to this embodiment, it is possible to spray an appropriate amount of the liquid phase refrigerant according to the temperature difference between the water and the liquid phase refrigerant. It is possible not only to prevent the occurrence of dryout on the heat transfer surface of the heat transfer tube 202, but also to suppress the reduction of the heat transfer area due to the retention of the non-evaporated liquid phase refrigerant. As a result, the liquid-phase refrigerant can be efficiently evaporated, and the heat transfer performance can be improved.

  Further, since the spray angle of the refrigerant mist sprayed to the inlet 202p of the heat transfer tube 202 becomes small, the refrigerant mist passing through the upper portion of the inlet 202p of the heat transfer tube 202 without colliding with the heat transfer tube 202 can be reduced. Therefore, it is possible to prevent excess refrigerant from reattaching to the heat transfer tube 202 and forming an excessive liquid film of liquid phase refrigerant on the surface of the heat transfer tube 202. This also contributes to improving the heat transfer performance of the evaporator 101. In particular, in a large-sized system, it is possible to optimize the liquid film by avoiding the reattachment of excess refrigerant, and it is possible to reduce pump power and increase efficiency because there is no wasteful spraying.

  The shell and tube heat exchanger disclosed in the present specification is particularly useful for an air conditioner such as a commercial air conditioner. The shell and tube heat exchanger may be used not only as an evaporator but also as a condenser. The refrigeration cycle apparatus disclosed in the present specification is not limited to an air conditioner, and may be another apparatus such as an absorption chiller, a chiller, or a heat storage device.

DESCRIPTION OF SYMBOLS 100 Refrigeration cycle apparatus 101 Evaporator 102 Compressor 103 Condenser 201 Shell 202 Heat transfer pipe 202p Inlet 202q Outlet 204, 204c Spray nozzle 207 Inflow pipe 208 Outflow pipe 501 Introducing section 502 Ejection hole 504 Mist forming section 505 First surface 506 Second Surface O Center axis

Claims (12)

Shell,
A flat heat transfer tube located inside the shell and through which the first fluid flows from the inlet toward the outlet;
A spray method in a shell-and-tube heat exchanger, the nozzle being located inside the shell and spraying a second fluid toward the heat transfer tube,
A point on the surface of the heat transfer tube located equidistant from the inlet and the outlet is an intermediate point,
The amount of the second fluid sprayed from the nozzle and reaching the range from the inlet to the intermediate point in the heat transfer tube per unit time is defined as Q1,
When the amount of the second fluid sprayed from the nozzle and reaching the range from the outlet to the intermediate point in the heat transfer tube per unit time is Q2,
And spraying the second fluid from the nozzle toward the heat transfer tube so as to satisfy a relationship of Q1> Q2.
A spraying method. The nozzle sprays the second fluid stored at the bottom of the shell toward the heat transfer tube.
The spraying method according to claim 1. Spraying the second fluid from the nozzle toward the heat transfer tube so that the amount of the second fluid reaching the heat transfer tube per unit time gradually decreases from the inlet toward the outlet;
The spraying method according to claim 1 or 2. And flowing the first fluid through the heat transfer tube.
The spraying method according to any one of claims 1 to 3. Shell,
A flat heat transfer tube located inside the shell and through which the first fluid flows from the inlet toward the outlet;
A nozzle located inside the shell and spraying a second fluid toward the heat transfer tube;
With
A point on the surface of the heat transfer tube located equidistant from the inlet and the outlet is an intermediate point,
The amount of the second fluid sprayed from the nozzle and reaching the range from the inlet to the intermediate point in the heat transfer tube per unit time is defined as Q1,
When the amount of the second fluid sprayed from the nozzle and reaching the range from the outlet to the intermediate point in the heat transfer tube per unit time is Q2,
Satisfying the relationship of Q1> Q2.
Shell and tube heat exchanger. The nozzle sprays the second fluid stored at the bottom of the shell toward the heat transfer tube,
The shell and tube type heat exchanger according to claim 5. The amount of the second fluid sprayed from the nozzle and reaching the heat transfer tube per unit time gradually decreases from the inlet toward the outlet;
The shell and tube type heat exchanger according to claim 5 or 6. The nozzle is connected to the introduction part for allowing the second fluid to flow in, the injection part connected to the introduction part for increasing the speed of the second fluid, and connected to the injection hole, so that the second fluid is mist-shaped. A mist forming part,
When viewed from the direction perpendicular to the flat surface of the heat transfer tube, the central axis of the ejection hole is located between the inlet and the intermediate point in the vertical direction,
The mist forming part includes a first surface located on the upper side in the vertical direction and a second surface located on the lower side in the vertical direction,
An angle formed by the first surface and the central axis of the ejection hole is an angle α,
When the angle formed between the second surface and the central axis of the ejection hole is an angle β,
Satisfying the relationship of the angle α <the angle β.
The shell-and-tube heat exchanger according to any one of claims 5 to 7.   The shell and tube according to any one of claims 5 to 8, wherein a distance between the nozzle and the inlet of the heat transfer tube is shorter than a distance between the nozzle and the outlet of the heat transfer tube. Type heat exchanger. When the flow of the second fluid from the nozzle toward the heat transfer tube is observed in a direction perpendicular to the flow direction of the second fluid, the outer edge of the flow of the second fluid has a rectangular shape.
The shell and tube type heat exchanger according to any one of claims 5 to 9. The rectangular shape is a shape having a pair of short sides parallel to a direction perpendicular to the flat surface of the heat transfer tube.
The shell and tube type heat exchanger according to claim 10. A shell and tube heat exchanger according to any one of claims 5 to 11,
A compressor,
With
Refrigeration cycle equipment.

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