Shell-and-tube heat exchanger, its operating method, and refrigeration equipment equipped with it

Abstract

To provide a technique suitable for improving heat exchange efficiency of a shell-and-tube type heat exchanger.SOLUTION: A shell-and-tube type heat exchanger according to the present disclosure comprises a shell 201, a plurality of heat transfer tubes 202 arranged inside the shell 201 so as to be parallel to each other, and a nozzle 204 arranged on the side of inlets for a heat medium in the plurality of heat transfer tubes 202, and spraying a liquid-phase refrigerant toward the side of outlets from the side of the inlets for the heat medium in the plurality of heat transfer tubes 202. One example of the shell-and-tube type heat exchanger is an evaporator 101.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a shell-and-tube heat exchanger, a method for operating the same, and a refrigeration system including the same. [Background technology]

[0002] There is a known technology for cooling the refrigerant inside a heat transfer tube by spraying cooling water toward the heat transfer tube. A conventional evaporative condenser described in Patent Document 1 has multiple spray nozzles that spray cooling water toward a condensing coil. Heat exchange between the cooling water and the refrigerant flowing through the condensing coil causes the cooling water to evaporate, and the refrigerant is cooled and condensed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 073367 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable to improve the heat exchange efficiency when the configuration described in Patent Document 1 is applied to a shell-and-tube heat exchanger. The present disclosure provides a technique suitable for improving the heat exchange efficiency of a shell-and-tube heat exchanger. [Means for solving the problem]

[0005] The shell-and-tube heat exchanger of the present disclosure comprises: A shell and a plurality of heat transfer tubes arranged parallel to one another inside the shell; a first nozzle disposed on a heat medium inlet side of the plurality of heat transfer tubes and configured to spray a liquid-phase refrigerant onto the plurality of heat transfer tubes from the heat medium inlet side toward the heat medium outlet side of the plurality of heat transfer tubes; It is equipped with:

[0006] A method for operating a shell-and-tube heat exchanger according to the present disclosure is a method for operating a shell-and-tube heat exchanger according to the present disclosure, causing the heat medium to flow through the plurality of heat transfer tubes; spraying the liquid-phase refrigerant from the first nozzle toward the plurality of heat transfer tubes to cause heat exchange between the heat medium and the liquid-phase refrigerant; adjusting a spray pressure of the liquid-phase refrigerant from the first nozzle so that an outer edge of the flow of the liquid-phase refrigerant sprayed from the nozzle reaches a position at a predetermined distance from the outlet toward the inlet of the plurality of heat transfer tubes; Includes.

[0007] A refrigeration device according to the present disclosure includes the shell-and-tube heat exchanger according to the present disclosure as at least one of an evaporator and a condenser. [Effects of the Invention]

[0008] According to the present disclosure, a technique suitable for improving the heat exchange efficiency of a shell-and-tube heat exchanger can be provided. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a configuration diagram of an absorption refrigeration device according to a first embodiment of the present disclosure. [Figure 2] A longitudinal cross-sectional view of the evaporator of the absorption refrigeration unit shown in Figure 1 [Figure 3] FIG. 3 is a top view showing the positional relationship between the heat transfer tubes and the nozzles in the evaporator shown in FIG. [Figure 4] A characteristic diagram showing the relationship between the distance from the inlet of the heat transfer tube and the temperature difference ΔT between the heat transfer medium and the refrigerant [Figure 5] FIG. 10 is a longitudinal cross-sectional view of an evaporator according to a second embodiment. [Figure 6] FIG. 10 is a longitudinal cross-sectional view of an evaporator according to a third embodiment. [Figure 7A] FIG. 10 is a diagram showing the spray pattern of liquid refrigerant sprayed from a nozzle. [Figure 7B] FIG. 10 is a diagram showing the spray pattern of liquid refrigerant sprayed from a nozzle. [Figure 8]A longitudinal cross-sectional view of the evaporator taken along line AA in Figure 6. [Figure 9] A diagram showing the spray and flow state of liquid phase refrigerant DETAILED DESCRIPTION OF THE INVENTION

[0010] (Findings that formed the basis of this disclosure) At the time the inventors conceived this disclosure, when refrigerant was sprayed onto a heat transfer tube, the refrigerant sometimes failed to reach areas far from the nozzle due to factors such as the influence of airflow inside the shell, which changes depending on load fluctuations or operating conditions. In other words, there was a problem of dryout on the surface of the heat transfer tube. "Dryout" refers to the phenomenon in which a large dry area forms on the surface of the heat transfer tube. Increasing the nozzle spray pressure allows the refrigerant to reach a greater distance. However, increasing the spray pressure may damage the heat transfer tube due to erosion. Increasing the number of nozzles increases costs. Furthermore, increasing the number of nozzles increases the amount of refrigerant sprayed, which increases the thickness of the liquid film on the surface of the heat transfer tube. The thicker the liquid film, the lower the heat exchange efficiency.

[0011] On the other hand, near the outlet of the heat exchanger, the temperature difference between the heat transfer medium flowing inside the heat transfer tube and the refrigerant on the surface of the heat transfer tube is small. In other words, the wetness of the heat transfer tube near the outlet of the heat exchanger has little effect on the performance of the heat exchanger. Also, even if the spray pressure is low and the refrigerant cannot directly reach the end of the heat transfer tube, if the refrigerant flow has a velocity component parallel to the longitudinal direction of the heat transfer tube, inertia will extend the reach of the refrigerant liquid film.

[0012] Based on this finding, the present inventors have come to form the subject of the present invention.

[0013] Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters or redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art.

[0014] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0015] (Embodiment 1) Hereinafter, the first embodiment will be described with reference to FIGS.

[0016] [1-1. Configuration of absorption refrigeration unit] 1 is a configuration diagram of an absorption refrigeration system 100 according to the first embodiment. The absorption refrigeration system 100 includes an evaporator 101, an absorber 102, a regenerator 103, and a condenser 104. These are connected to each other by paths 110a, 110b, 110c, 110d, and 209. The refrigerant and absorbing liquid in the absorption refrigeration system 100 are, for example, water and a lithium bromide solution. Another example of the refrigerant and absorbing liquid is ammonia and water.

[0017] The evaporator 101 is configured as a shell-and-tube heat exchanger according to the first embodiment. The evaporator 101 includes a heat transfer tube 202 and a circulation circuit 205. A heat transfer medium, such as water, flows through the heat transfer tube 202. The circulation circuit 205 includes a pump 206. A nozzle 204 is provided at the downstream end of the circulation circuit 205. The upstream end of the circulation circuit 205 is connected to the bottom of the evaporator 101. A liquid refrigerant is stored at the bottom of the evaporator 101. The liquid refrigerant circulates through the circulation circuit 205 by the operation of the pump 206. Specifically, the liquid refrigerant is sent to the nozzle 204 by the pump 206 and sprayed from the nozzle 204 toward the heat transfer tube 202. Heat exchange occurs between the heat transfer medium in the heat transfer tube 202 and the sprayed liquid refrigerant, thereby extracting cold from the refrigerant. The refrigerant is heated on the surface of the heat transfer tube 202 and evaporates. The outlet of the evaporator 101 is connected to the absorber 102 via a path 209 .

[0018] The absorber 102 is configured, for example, by a shell-and-tube heat exchanger. The absorber 102 has heat transfer tubes 121 and a spray tray 107. A heat medium such as water flows inside the heat transfer tubes 121. An absorbing liquid is sprayed from the spray tray 107 toward the heat transfer tubes 121. The absorbing liquid is cooled on the surface of the heat transfer tubes 121, and the gas-phase refrigerant is absorbed into the absorbing liquid. An outlet of the absorber 102 is connected to an inlet of the regenerator 103 by a path 110a. The path 110a has a pump 106.

[0019] The regenerator 103 is equipped with a heater 123 for heating the absorption liquid. The heater 123 may be a boiler itself, or may be a circuit in which a heat medium heated by the boiler circulates. The bottom of the regenerator 103 is connected to the spray tray 107 of the absorber 102 by a path 110d. Because the internal pressure of the regenerator 103 is higher than the internal pressure of the absorber 102, the absorption liquid is sent from the bottom of the regenerator 103 to the spray tray 107 due to the pressure difference. The outlet of the regenerator 103 is connected to the inlet of the condenser 104 by a path 110b.

[0020] The absorber 102 is configured, for example, by a shell-and-tube heat exchanger. The condenser 104 is a heat exchanger for cooling and liquefying the refrigerant that has been heated and vaporized in the regenerator 103. The condenser 104 includes, for example, heat transfer tubes 124. A heat medium such as water flows inside the heat transfer tubes 124. The refrigerant is cooled and liquefied on the surface of the heat transfer tubes 124. An outlet of the condenser 104 is connected to an inlet of the evaporator 101 by a path 110c.

[0021] The paths 110a and 110b are vapor paths, and the paths 110c and 110d are liquid paths. Each path is made up of at least one metal pipe.

[0022] [1-2. Operation of absorption refrigeration unit] The operation and function of the absorption refrigeration system 100 configured as above will be described below.

[0023] In the evaporator 101, liquid-phase refrigerant is pressure-fed to the nozzle 204 through the circulation circuit 205 by the pump 206, and is sprayed from the nozzle 204 in a mist state onto the heat transfer tubes 202. The sprayed liquid-phase refrigerant exchanges heat with the heat medium flowing inside the heat transfer tubes 202 on the surface of the heat transfer tubes 202 and evaporates. This generates a low-temperature, low-pressure gas-phase refrigerant. The gas-phase refrigerant passes through a path 209 and is drawn into the absorber 102. In the absorber 102, the gas-phase refrigerant is absorbed by the absorbing liquid dropped from the spray tray 107. At this time, the absorbing liquid absorbs the gas-phase refrigerant on the surface of the heat transfer tubes 121 while being cooled by the heat transfer tubes 121. The absorbing liquid then flows down to the bottom of the absorber 102 and is sent to the regenerator 103 through a path 110a. Just before flowing into the regenerator 103, the absorbing liquid is a mixture of an absorbent and a refrigerant. After flowing into the regenerator 103, the absorption liquid is heated by the heater 123. The heating causes the refrigerant components with low boiling points to vaporize and be separated as high-temperature gas-phase refrigerant. The absorption liquid is sent to the spray tray 107 via path 110d. The separated high-temperature gas-phase refrigerant is sent to the condenser 104 via path 110b. The high-temperature gas-phase refrigerant is cooled and condensed by the heat transfer tube 124. This produces a liquid-phase refrigerant. The liquid-phase refrigerant is sent to the evaporator 101 via path 110c. The above cycle is repeated.

[0024] The absorption refrigeration system 100 is applied to, for example, commercial or residential air conditioners. The heat medium cooled in the evaporator 101 is supplied to a room and used for cooling the room. Alternatively, the heat medium heated in the condenser 104 is supplied to a room and used for heating the room. The heat medium is, for example, water. However, the application of the absorption refrigeration system 100 is not limited to air conditioners, and it may also be used in other devices such as chillers and heat storage devices.

[0025] [1-3. Evaporator configuration] FIG. 2 is a vertical cross-sectional view of the evaporator 101 of the absorption refrigeration system 100 shown in FIG. 1. The evaporator 101 is composed of a shell-and-tube heat exchanger. The evaporator 101 is also called a spray evaporator. The evaporator 101 includes a shell 201, a plurality of heat transfer tubes 202, and a nozzle 204. In FIG. 2, the Z axis represents an axis parallel to the vertical direction. The X axis represents an axis parallel to the horizontal direction. The direction perpendicular to the paper surface is the Y axis (not shown).

[0026] The shell 201 is a container having, for example, a rectangular or circular cross section. The container may be a pressure-resistant container. The shell 201 has an inlet 201a and an outlet 201b. A path 110c is connected to the inlet 201a. The absorber 102 is connected to the outlet 201b via a path 209. A liquid-phase refrigerant flows from the outside into the inside of the shell 201 through the inlet 201a. A gas-phase refrigerant generated on the surfaces of the multiple heat transfer tubes 202 is led to the outside of the shell 201 through the outlet 201b.

[0027] The plurality of heat transfer tubes 202 are arranged parallel to one another inside the shell 201. Each of the plurality of heat transfer tubes 202 has an inlet 202p and an outlet 202q. The heat transfer tubes 202 have, for example, a circular cross section. The heat transfer tubes 202 are made of a metal such as copper or stainless steel, and are typically copper tubes. In this embodiment, the plurality of heat transfer tubes 202 are arranged in three rows in the vertical direction. The heat transfer tubes 202 are also arranged in multiple rows in the direction perpendicular to the plane of the drawing.

[0028] The nozzle 204 is disposed on the heat medium inlet side of the plurality of heat transfer tubes 202. A liquid-phase refrigerant is sprayed from the nozzle 204 onto the plurality of heat transfer tubes 202 from the heat medium inlet side toward the heat medium outlet side of the plurality of heat transfer tubes 202. The liquid-phase refrigerant is, for example, liquid water.

[0029] In the longitudinal direction of the heat transfer tube 202, the nozzle 204 is located between the middle position of the heat transfer tube 202 and the inlet 202p. However, the nozzle 204 may be located as close to the inlet 202p as possible. In this case, the liquid-phase refrigerant can also be sprayed onto the portion of the heat transfer tube 202 near the inlet 202p.

[0030] The shape of the flow of the liquid-phase refrigerant sprayed from the nozzle 204 is, for example, conical.

[0031] FIG. 3 is a top view showing the positional relationship between the heat transfer tube 202 and the nozzle 204 in the evaporator 101 shown in FIG. 2. In FIG. 3, the X-axis and Y-axis each represent axes parallel to the horizontal direction. Dashed lines represent outer edges E1 and E2 of the flow of the sprayed liquid-phase refrigerant in a plan view. The nozzle 204 has a spray axis Am. The spray axis Am is the central axis of the nozzle 204 and passes through the center of the opening of the nozzle 204. The spray axis Am passes through the center of the flow of the sprayed liquid-phase refrigerant. A nozzle hole is located at the center of the nozzle 204. The flow of the sprayed liquid-phase refrigerant is fan-shaped with a divergence angle α in a plan view. The divergence angle α is, for example, not less than 90 degrees and not more than 120 degrees. The divergence angle α is typically 105 degrees.

[0032] The spray axis Am is parallel to a plane (XY plane) including the central axis Bx of the heat transfer tube 202. The central axis Bx is an axis parallel to the longitudinal direction of the heat transfer tube 202 and passing through the center of the cross section of the heat transfer tube 202. The spray axis Am is inclined with respect to the Y axis, which is an axis perpendicular to the longitudinal direction of the heat transfer tube 202, and is also inclined with respect to the central axis Bx of the heat transfer tube 202. The angle θ between the central axis Bx and the spray axis Am is, for example, not less than 30 degrees and not more than 50 degrees. The angle θ is typically 45 degrees. The angle θ is an acute angle formed between the traveling direction of the liquid-phase refrigerant along the spray axis Am of the nozzle 204 and a direction parallel to the longitudinal direction of the heat transfer tube 202 and from the inlet 202p to the outlet 202q of the heat transfer tube 202.

[0033] 3, "spraying the liquid-phase refrigerant onto the heat transfer tubes 202 from the inlet side toward the outlet side of the heat medium in the heat transfer tubes 202" means that the angle θ is an acute angle. With this configuration, the liquid-phase refrigerant can reach close to the outlet 202q of the heat transfer tube 202.

[0034] The spray pressure of the nozzle 204 can be adjusted so that the sprayed liquid-phase refrigerant reaches position P1 directly. An outer edge E1 of the liquid-phase refrigerant flow intersects with the heat transfer tube 202 at position P1. Position P1 is a position a distance L from the outlet 202q of the heat transfer tube 202 toward the inlet 202p. In other words, the liquid-phase refrigerant flow (liquid-phase refrigerant mist) does not directly reach the portion of the heat transfer tube 202 near the outlet 202q. However, the liquid-phase refrigerant flow has a velocity component parallel to the longitudinal direction of the heat transfer tube 202. Therefore, the liquid-phase refrigerant spreads due to inertial force. As a result, heat exchange also occurs in the portion near the outlet 202q.

[0035] In this embodiment, the liquid-phase refrigerant is also sprayed in a direction inclined from a direction perpendicular to the longitudinal direction of the heat transfer tube 202 (a direction parallel to the Y-axis) toward the inlet side of the heat transfer tube 202. With this configuration, the liquid-phase refrigerant is also sprayed near the inlet 202p of the heat transfer tube 202, making it less likely that dryout will occur near the inlet 202p of the heat transfer tube 202. The flow of the liquid-phase refrigerant shown in Fig. 3 is achieved by adjusting the orientation of the nozzle 204 and the spray pressure.

[0036] That is, the liquid-phase refrigerant is sprayed from the nozzle 204 toward the plurality of heat transfer tubes 202, causing heat exchange between the heat medium and the liquid-phase refrigerant. The spray pressure of the liquid-phase refrigerant from the nozzle 204 is adjusted so that the outer edge E1 of the flow of the liquid-phase refrigerant sprayed from the nozzle 204 reaches a position at a predetermined distance L from the outlet 202q toward the inlet 202p of the plurality of heat transfer tubes 202.

[0037] As shown in FIG. 2, the evaporator 101 further includes a flow path cover 207, a flow path cover 208, and a circulation circuit 205. The configuration of the circulation circuit 205 is as described with reference to FIG. 1. A nozzle 204 is provided at the downstream end of the circulation circuit 205. The flow path cover 207 has an inlet 211 for the heat medium. The flow path cover 207 is attached to the shell 201 so as to cover the inlets 202p of the multiple heat transfer tubes 202. The flow path cover 208 has an outlet 212 for the heat medium. The flow path cover 208 is attached to the shell 201 so as to cover the outlets 202q of the multiple heat transfer tubes 202. The heat medium flows into the heat transfer tubes 202 through the flow path cover 207 and flows out of the heat transfer tubes 202 to the outside through the flow path cover 208.

[0038] In this embodiment, the heat medium flows in the same direction (from left to right) through the heat transfer tubes 202. That is, the evaporator 101 has one path.

[0039] [1-4. Evaporator Operation] The operation and function of the evaporator 101 configured as above will be described below.

[0040] In the evaporator 101, the liquid-phase refrigerant is pressure-fed by the pump 206 through the circulation circuit 205 to the nozzle 204, and is sprayed from the nozzle 204 onto the heat transfer tube 202 in a mist state.

[0041] A heat medium such as water flows into the flow path cover 207 from the inlet 211, and flows into the heat transfer tube 202 through the flow path cover 207. The heat medium then flows from left to right through the heat transfer tube 202, passes through the flow path cover 208, and flows out from the outlet 212.

[0042] As shown in Fig. 3, liquid-phase refrigerant is sprayed from nozzles 204 from the inlet side of the heat transfer medium to the outlet side of multiple heat transfer tubes 202. The flow of the liquid-phase refrigerant has a divergence angle α. The sprayed liquid-phase refrigerant exchanges heat with the heat transfer medium on the surface of the heat transfer tubes 202 and evaporates. The flow of liquid-phase refrigerant does not reach outlets 202q of the heat transfer tubes 202, but reaches position P1, which is a distance L from the outlet 202q. Wetting and spreading of the liquid-phase refrigerant due to inertial force can be expected, but the amount of liquid-phase refrigerant sprayed in the region between position P1 and the outlet 202q is small.

[0043] FIG. 4 is a characteristic diagram showing the relationship between the distance from the inlet 202p of the heat transfer tube 202 and the temperature difference ΔT. The horizontal axis represents the distance from the inlet 202p of the heat transfer tube 202. The vertical axis represents the temperature difference ΔT. The temperature difference ΔT is the temperature difference between the heat medium and the refrigerant. The temperature difference ΔT is largest at the inlet 202p of the heat transfer tube 202, decreases toward the outlet 202q, and is smallest at the outlet 202q. Heat exchange between the heat medium and the refrigerant is almost complete near the outlet 202q of the heat transfer tube 202. Therefore, the amount of heat exchange is small in the region between position P1 and the outlet 202q (the region corresponding to the distance L). According to this embodiment, it is possible to generate a sparse region where the amount of spray of liquid-phase refrigerant is small in the region where the amount of heat exchange is small, making dryout less likely to occur.

[0044] [1-5. Effects, etc.] As described above, in this embodiment, the nozzle 204 is arranged on the heat medium inlet side of the plurality of heat transfer tubes 202, and sprays the liquid-phase refrigerant onto the plurality of heat transfer tubes 202 from the heat medium inlet side toward the heat medium outlet side of the plurality of heat transfer tubes 202.

[0045] According to this configuration, the liquid-phase refrigerant is sprayed from the nozzle 204 in the axial direction of the heat transfer tube 202. The heat transfer tube 202 includes a portion close to the nozzle 204 and a portion distant from the nozzle 204. The liquid-phase refrigerant easily reaches the portion close to the nozzle 204. Therefore, the portion close to the nozzle 204 is a dense region where a large amount of liquid-phase refrigerant is sprayed. On the other hand, the liquid-phase refrigerant is unlikely to reach the portion distant from the nozzle 204. Therefore, the portion distant from the nozzle 204 is a sparse region where a small amount of liquid-phase refrigerant is sprayed. The nozzle 204 is disposed on the inlet side of the heat transfer tube 202. Therefore, in the dense region, the temperature difference ΔT between the liquid-phase refrigerant and the heat medium in the heat transfer tube 202 is large. On the other hand, in the sparse region, heat exchange between the refrigerant and the heat medium is sufficiently progressing, so the temperature difference ΔT therebetween is small. Since the temperature difference ΔT is small and a sparse region where a small amount of liquid-phase refrigerant is sprayed can be generated in a region with a small amount of heat exchange, dryout is less likely to occur. For these reasons, even in an area far from the nozzle 204 and with a small amount of liquid-phase refrigerant sprayed, dryout can be avoided without increasing the spray pressure of the nozzle 204. According to the technology of the present disclosure, it is possible to improve the heat exchange efficiency of the evaporator 101 while avoiding erosion and increasing the reliability of the evaporator 101.

[0046] In the present embodiment, the angle θ formed between the direction of travel of the liquid-phase refrigerant along the spray axis Am of the nozzle 202 and the direction parallel to the longitudinal direction of the heat transfer tube 202 and from the inlet 202p to the outlet 202q of the heat transfer tube 202 may be an acute angle. With this configuration, the liquid-phase refrigerant can reach close to the outlet 202q of the heat transfer tube 202.

[0047] (Embodiment 2) Hereinafter, the second embodiment will be described with reference to Fig. 5. The same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

[0048] [2-1. Evaporator configuration] 5 is a vertical cross-sectional view of an evaporator 301 according to a second embodiment. In the evaporator 301 of this embodiment, the plurality of heat transfer tubes 202 include a first heat transfer tube group 202a and a second heat transfer tube group 202b. The first heat transfer tube group 202a is a heat transfer tube group including the heat transfer tube 202 located in the uppermost stage inside the shell 201. The second heat transfer tube group 202b is a heat transfer tube group adjacent to and below the first heat transfer tube group 202a. The flow direction of the heat medium in the first heat transfer tube group 202a is opposite to the flow direction of the heat medium in the second heat transfer tube group 202b. Specifically, the flow direction of the heat medium in the first heat transfer tube group 202a is opposite by 180 degrees to the flow direction of the heat medium in the second heat transfer tube group 202b. The heat transfer medium flows through the second heat transfer tube group 202b and the first heat transfer tube group 202a in this order. A "heat transfer tube group" refers to a collection of multiple heat transfer tubes 202 through which a heat transfer medium in the same temperature range flows.

[0049] In this embodiment, the nozzle 204 described in the first embodiment is defined as a first nozzle 204a. The first nozzle 204a is a nozzle that sprays liquid-phase refrigerant onto the first heat transfer tube group 202a. However, the liquid-phase refrigerant that does not evaporate in the first heat transfer tube group 202a drips onto the second heat transfer tube group 202b. Because the first heat transfer tube group 202a is the heat transfer tube group located at the uppermost stage, even if the liquid-phase refrigerant sprayed from the first nozzle 204a does not directly reach the vicinity of the outlet of the first heat transfer tube group 202a, this has little effect on the heat exchange efficiency of the evaporator 301.

[0050] The evaporator 301 further includes a second nozzle 204b. The second nozzle 204b is disposed at a position on the heat medium outlet side of the second heat transfer tube group 202b, shifted from the position of the first nozzle 204a toward the heat medium outlet side of the first heat transfer tube group 202a. Liquid-phase refrigerant is sprayed from the second nozzle 204b onto the second heat transfer tube group 202b. The heat medium outlet side of the first heat transfer tube group 202a is the heat medium inlet side of the second heat transfer tube group 202b. The heat medium inlet side of the first heat transfer tube group 202a is the heat medium outlet side of the second heat transfer tube group 202b. The distance between the first nozzle 204a and the second nozzle 204b in a direction parallel to the longitudinal direction of the heat transfer tube 202 is equal to, for example, the distance L described in the first embodiment.

[0051] The second nozzle 204b is a nozzle that sprays the liquid-phase refrigerant onto the second heat transfer tube group 202b from the outlet side toward the inlet side of the heat medium in the second heat transfer tube group 202b. The second nozzle 204b can increase the heat exchange amount of the second heat transfer tube group 202b.

[0052] In this embodiment, the spray direction of the second nozzle 204b matches the spray direction of the first nozzle 204a. In other words, the spray axis of the second nozzle 204b is parallel to the spray axis Am (FIG. 3) of the first nozzle 204a. With this configuration, the liquid-phase refrigerant sprayed from the first nozzle 204a drips from the first heat transfer tube group 202a to the second heat transfer tube group 202b, so that the liquid-phase refrigerant can be delivered to areas that cannot be reached by the liquid-phase refrigerant sprayed from the second nozzle 204b.

[0053] The evaporator 301 has only the first nozzle 204a as a nozzle that sprays liquid-phase refrigerant onto the first heat transfer tube group 202a. This configuration reduces the cost of the evaporator 301. The second nozzle 204b is the only nozzle that directly sprays liquid-phase refrigerant onto the second heat transfer tube group 202b. However, the liquid-phase refrigerant sprayed from the first nozzle 204a also drips onto the second heat transfer tube group 202b.

[0054] The structure and characteristics of the first nozzle 204a are, for example, the same as those of the second nozzle 204b. In other words, the same nozzle product can be used for the first nozzle 204a and the second nozzle 204b. This allows the cost of the evaporator 301 to be reduced.

[0055] During operation of the evaporator 301, the spray pressure of the first nozzle 204a may be equal to or different from the spray pressure of the second nozzle 204b. In this embodiment, the circuit for supplying liquid-phase refrigerant to the first nozzle 204a also serves as the circuit for supplying liquid-phase refrigerant to the second nozzle 204b. In other words, the circulation circuit 205 is shared by the first nozzle 204a and the second nozzle 204b. Therefore, excluding pressure loss in the circulation circuit 205, the spray pressure of the first nozzle 204a is equal to the spray pressure of the second nozzle 204b.

[0056] In this embodiment, the plurality of heat transfer tubes 202 further includes a third heat transfer tube group 202c, a fourth heat transfer tube group 202d, and a fifth heat transfer tube group 202e. Each heat transfer tube group is composed of a plurality of heat transfer tubes 202 arranged in three rows in the vertical direction. The flow directions of the heat medium in the odd-numbered heat transfer tube groups are the same. The flow directions of the heat medium in the even-numbered heat transfer tube groups are the same. The flow direction of the heat medium in the odd-numbered heat transfer tube groups is opposite to the flow direction of the heat medium in the even-numbered heat transfer tube groups. One nozzle 204 is provided for each heat transfer tube group. The nozzle 204 that sprays liquid-phase refrigerant toward the odd-numbered heat transfer tube groups is the first nozzle 204a. The nozzle 204 that sprays liquid-phase refrigerant toward the even-numbered heat transfer tube groups is the second nozzle 204b. The first nozzles 204a and the second nozzles 204b are arranged alternately in a staggered pattern along the vertical direction. The positions of the multiple first nozzles 204a in the longitudinal direction of the heat transfer tube 202 are aligned with one another. The positions of the multiple second nozzles 204b in the longitudinal direction of the heat transfer tube 202 are aligned with one another.

[0057] A partition plate 210 is arranged inside the flow path cover 207 to separate the second heat transfer tube group 202b from the third heat transfer tube group 202c, and a partition plate 210 is arranged to separate the fourth heat transfer tube group 202d from the fifth heat transfer tube group 202e. A partition plate 210 is arranged inside the flow path cover 208 to separate the first heat transfer tube group 202a from the second heat transfer tube group 202b, and a partition plate 210 is arranged to separate the third heat transfer tube group 202c from the fourth heat transfer tube group 202d. Therefore, the heat medium flows through the fifth heat transfer tube group 202e, the fourth heat transfer tube group 202d, the third heat transfer tube group 202c, the second heat transfer tube group 202b, and the first heat transfer tube group 202a in this order. The flow direction of the heat medium is reversed inside the flow path cover 207 and inside the flow path cover 208. After flowing into the flow path cover 207, the heat medium flows through the lowermost heat transfer tube group (fifth heat transfer tube group 202e) and flows toward the uppermost heat transfer tube group (first heat transfer tube group 202a) while repeatedly meandering in a serpentine shape. After flowing through the uppermost heat transfer tube group, the heat medium flows out through the flow path cover 208 to the outside.

[0058] The flow path cover 207 communicates the heat medium inlet of the first heat transfer tube group 202a with the heat medium outlet of the second heat transfer tube group 202b. The flow path cover 207 also communicates the heat medium inlet of the third heat transfer tube group 202c with the heat medium outlet of the fourth heat transfer tube group 202d. The flow path cover 208 communicates the heat medium inlet of the second heat transfer tube group 202b with the heat medium outlet of the third heat transfer tube group 202c. The flow path cover 208 also communicates the heat medium inlet of the fourth heat transfer tube group 202d with the heat medium outlet of the fifth heat transfer tube group 202e. The flow path covers 207 and 208 function to smoothly change the flow direction of the heat medium.

[0059] In this embodiment, only one nozzle is provided for each heat transfer tube group. Only one first nozzle 204a is disposed at a height position overlapping the first heat transfer tube group 202a in the vertical direction. Only one second nozzle 204b is disposed at a height position overlapping the second heat transfer tube group 202b in the vertical direction. This configuration also applies to the third heat transfer tube group 202c, the fourth heat transfer tube group 202d, and the fifth heat transfer tube group 202e. Increasing the number of nozzles makes it easier to spray the liquid refrigerant over the entire heat transfer tube 202. However, if the spray rate increases too much, the liquid film on the surface of the heat transfer tube 202 becomes too thick. In this case, heat exchange efficiency may actually decrease. Increasing the number of nozzles also increases costs. This embodiment is suitable for cases where it is desired to maximize heat exchange efficiency while limiting the total number of nozzles 204. Furthermore, since the number of nozzles 204 can be reduced, this embodiment is suitable for reducing the cost of the evaporator 301 and making the evaporator 301 smaller.

[0060] [2-2. Evaporator Operation] The operation and function of the evaporator 301 configured as above will be described below.

[0061] The liquid-phase refrigerant is sprayed from the first nozzle 204a in the axial direction of the heat transfer tube 202. More specifically, the liquid-phase refrigerant is sprayed from the first nozzle 204a toward the first heat transfer tube group 202a. The liquid-phase refrigerant is likely to reach the portion close to the first nozzle 204a. Therefore, the portion close to the first nozzle 204a is a dense region A1 where a large amount of liquid-phase refrigerant is sprayed. On the other hand, the liquid-phase refrigerant is unlikely to reach the portion distant from the first nozzle 204a. Therefore, the portion distant from the first nozzle 204a is a sparse region B1 where a small amount of liquid-phase refrigerant is sprayed.

[0062] The heat transfer medium flows from the lowest heat transfer tube group to the highest heat transfer tube group, meandering in a serpentine pattern. A first nozzle 204a, which sprays liquid-phase refrigerant onto the first heat transfer tube group 202a, which is the highest heat transfer tube group, is located on the inlet side of the first heat transfer tube group 202a. Therefore, the area near the outlet of the first heat transfer tube group 202a is a sparse region B1, where the amount of liquid-phase refrigerant sprayed is small. However, in the sparse region B1, heat exchange between the refrigerant and the heat transfer medium is sufficiently progressing, making it less likely for dryout to occur.

[0063] On the other hand, the second nozzle 204b is positioned at a position shifted from the position of the first nozzle 204a toward the heat medium outlet of the first heat transfer tube group 202a. The amount of shift of the second nozzle 204b from the position of the first nozzle 204a is equal to the length of the sparse region B1 in the longitudinal direction of the heat transfer tube 202, i.e., the distance L. The liquid-phase refrigerant sprayed from the second nozzle 204b sufficiently reaches the vicinity of the inlet of the second heat transfer tube group 202b. The portion near the inlet of the second heat transfer tube group 202b is a dense region B2 where a large amount of liquid-phase refrigerant is sprayed. The portion near the outlet of the second heat transfer tube group 202b is located behind the second nozzle 204b. Therefore, the liquid-phase refrigerant sprayed from the second nozzle 204b hardly reaches the portion near the outlet of the second heat transfer tube group 202b. The portion near the outlet of the second heat transfer tube group 202b is a sparse region A2 where a small amount of liquid-phase refrigerant is sprayed. However, the dense region A1 is located above the sparse region A2. Therefore, the liquid-phase refrigerant drips from the dense region A1 toward the sparse region A2. As a result, the heat transfer tubes 202 in the sparse region A2 are wetted with the liquid-phase refrigerant. A similar phenomenon is repeated in the third heat transfer tube group 202c, the fourth heat transfer tube group 202d, and the fifth heat transfer tube group 202e. Therefore, the entire third heat transfer tube group 202c, the fourth heat transfer tube group 202d, and the fifth heat transfer tube group 202e are sufficiently wetted with the liquid-phase refrigerant.

[0064] In this way, the entire second heat transfer tube group 202b is wetted by the liquid-phase refrigerant sprayed by the second nozzle 204b and the liquid-phase refrigerant dripping from the first heat transfer tube group 202a. Ultimately, the only region where the amount of liquid-phase refrigerant sprayed is small and dripping from above is not expected is the sparse region B1. The sparse region B1 is the region in the evaporator 301 where the temperature difference ΔT between the refrigerant and the heat medium is smallest, and where the amount of heat exchange is small. The wet state of the sparse region B1 has little effect on the heat exchange performance of the evaporator 301.

[0065] [2-3. Effects, etc.] As described above, in this embodiment, the evaporator 301 further includes the second nozzle 204b, which is located at the heat medium outlet side of the second heat transfer tube group 202b and shifted from the first nozzle 204a toward the heat medium outlet side of the first heat transfer tube group 202a. With this configuration, even in a large-capacity evaporator having multiple heat transfer tube groups, a sparse region B1 can be generated only near the outlet of the first heat transfer tube group 202a, which is the uppermost heat transfer tube group. The entire second heat transfer tube group 202b, which is the lower heat transfer tube group, can be wetted with liquid-phase refrigerant. Therefore, dryout can be avoided without increasing the spray pressure of the first nozzle 204a and the second nozzle 204b. According to the technology disclosed herein, it is possible to improve the heat exchange efficiency of the evaporator 301 while avoiding erosion and increasing the reliability of the evaporator 301.

[0066] In the present embodiment, the evaporator 301 may further include a second nozzle 204b that is disposed at a position on the heat medium outlet side of the second heat transfer tube group 202b, shifted from the position of the first nozzle 204a toward the heat medium outlet side of the first heat transfer tube group 202a, and sprays the liquid-phase refrigerant onto the second heat transfer tube group 202b. The second nozzle 204b allows the liquid-phase refrigerant to be sufficiently sprayed onto the second heat transfer tube group 202b.

[0067] In the present embodiment, the second nozzle 204b may spray the liquid-phase refrigerant onto the second heat transfer tube group 202b from the outlet side toward the inlet side of the heat medium in the second heat transfer tube group 202b. The second nozzle 204b can increase the heat exchange amount of the second heat transfer tube group 202b.

[0068] Furthermore, in the present embodiment, the spray direction of the second nozzle 204b may be the same as the spray direction of the first nozzle 204a. With this configuration, the liquid-phase refrigerant sprayed from the first nozzle 204a drips from the first heat transfer tube group 202a to the second heat transfer tube group 202b, so that the liquid-phase refrigerant can be delivered to areas that cannot be reached by the liquid-phase refrigerant sprayed from the second nozzle 204b.

[0069] In the present embodiment, the evaporator 301 may have only the first nozzle 204a as a nozzle for spraying the liquid-phase refrigerant onto the first heat transfer tube group 202a. With such a configuration, the cost of the evaporator 301 can be reduced.

[0070] In this embodiment, the evaporator 301 may further include a flow path cover 207 that connects the heat medium inlet of the first heat transfer pipe group 202a to the heat medium outlet of the second heat transfer pipe group 202b. The flow path cover 207 functions to smoothly change the flow direction of the heat medium.

[0071] (Embodiment 3) Hereinafter, the third embodiment will be described with reference to Figures 6 to 9. The same components as those in the first or second embodiment will be assigned the same reference numerals and detailed description thereof will be omitted.

[0072] [3-1. Evaporator configuration] Fig. 6 is a vertical cross-sectional view of an evaporator 401 according to the third embodiment. The difference between the evaporator 401 of the present embodiment and the evaporator 301 (Fig. 5) of the second embodiment is the shape of the flow of the liquid-phase refrigerant sprayed from the nozzle 204. Except for this point, the configuration of the evaporator 401 is the same as the configuration of the evaporator 301. In the present embodiment, the flow of the liquid-phase refrigerant sprayed from the nozzle 204 has a flat shape.

[0073] 7A and 7B are diagrams showing the spray pattern of the liquid-phase refrigerant sprayed from the nozzle 204. The nozzle 204 sprays the liquid-phase refrigerant in a flat spray pattern having a spray axis Am. As shown in FIG. 7A, the liquid-phase refrigerant sprayed from the nozzle 204 forms a fan-shaped spray area M. Furthermore, when this spray pattern is projected onto a plane H perpendicular to the spray axis Am, the shape of the spray area S that appears is flat. The liquid-phase refrigerant sprayed in such a spray pattern passes between the heat transfer tubes 202.

[0074] Fig. 8 is a vertical cross-sectional view of the evaporator 401 taken along line AA shown in Fig. 6. In the example shown in Fig. 8, 12 heat transfer tubes 202 are arranged in the Y-axis direction. However, the number of heat transfer tubes 202 in the Y-axis direction is not particularly limited. The nozzle 204 sprays the liquid-phase refrigerant so that the spray axis Am passes between the pair of heat transfer tubes 202 closest to the nozzle 204 in the direction perpendicular to the longitudinal direction of the heat transfer tubes 202 (the Y-axis direction), and the spray area S passes between the pair of heat transfer tubes 202. The spray axis Am extends horizontally, for example.

[0075] For example, the nozzles 204 are arranged only on one side in the Y-axis direction, and not on the other side in the Y-axis direction. Therefore, the nozzles 204 spray the liquid-phase refrigerant in, for example, the positive direction of the Y-axis in a plane (YZ plane) perpendicular to the longitudinal direction of the heat transfer tube 202.

[0076] 9 is a diagram showing the spray and flow state of the liquid-phase refrigerant sprayed from the nozzle 204. The multiple heat transfer tubes 202 include a first stage 22a and a second stage 22b. The first stage 22a has multiple heat transfer tubes 202 arranged along a first plane. The second stage 22b has multiple heat transfer tubes 202 arranged along a second plane parallel to the first plane, and is adjacent to the first stage 22a in the direction perpendicular to the first plane (Z-axis direction). The first and second planes are planes parallel to the XY plane.

[0077] Between the first stage 22a and the second stage 22b, there exists an imaginary plane that does not intersect with any tangible object and extends from one end to the other end of the first stage 22a in the arrangement direction of the heat transfer tubes 202 of the first stage 22a.

[0078] The plurality of heat transfer tubes 202 in the first stage 22a and the plurality of heat transfer tubes 202 in the second stage 22b form a rectangular lattice, a square lattice, or a parallelogram lattice in a third plane perpendicular to the longitudinal direction (X-axis direction) of the heat transfer tubes 202. The third plane is a plane parallel to the YZ plane.

[0079] The spray axis Am of the spray pattern of the liquid-phase refrigerant sprayed from the nozzle 204 passes between the first ends 22j of the multiple heat transfer tubes 202 in the first stage 22a and the second ends 22k of the multiple heat transfer tubes 202 in the second stage 22b. The first ends 22j are the ends closer to the second stage 22b in the direction perpendicular to the first plane (the Z-axis direction). The second ends 22k are the ends closer to the first stage 22a in the direction perpendicular to the first plane (the Z-axis direction). The spray pattern of the liquid-phase refrigerant sprayed from the nozzle 204 passes between the first stage 22a and the second stage 22b.

[0080] The second stage 22b is, for example, disposed below the first stage 22a in the vertical direction. The plurality of heat transfer tubes 202 includes, for example, a lower heat transfer tube group 22c. The lower heat transfer tube group 22c has a plurality of heat transfer tubes 202 and is disposed below the second stage 22b in the vertical direction. Each of the plurality of heat transfer tubes 202 of the lower heat transfer tube group 22c is, for example, disposed directly below one of the plurality of heat transfer tubes 202 of the second stage 22b.

[0081] The plurality of heat transfer tubes 202 of the lower heat transfer tube group 22c, together with the plurality of heat transfer tubes 202 of the second stage 22b, form, for example, a rectangular lattice or a square lattice in the third plane.

[0082] [3-2. Evaporator Operation] The operation and function of the evaporator 401 configured as above will be described below.

[0083] As shown in Fig. 8, the nozzle 204 sprays liquid-phase refrigerant toward the space between the heat transfer tubes 202 of two rows adjacent to each other in the Z-axis direction. The liquid-phase refrigerant is sprayed in a spray pattern in which a spray axis Am extends between the two rows. The sprayed liquid-phase refrigerant adheres to the surfaces of the heat transfer tubes 202. Heat exchange between the heat medium inside the heat transfer tubes 202 and the liquid-phase refrigerant adhering to the surfaces of the heat transfer tubes 202 causes the liquid-phase refrigerant to evaporate and generate gas-phase refrigerant. The liquid-phase refrigerant that does not evaporate flows along the surfaces of the heat transfer tubes 202 and drips toward the heat transfer tube 202 below.

[0084] As shown in FIG. 9 , the liquid-phase refrigerant sprayed from the nozzle 204 passes between the heat transfer tubes 202 in the first stage 22a and the second stage 22b, which are arranged to form a rectangular lattice, a square lattice, or a parallelogram lattice in the third plane. Between the first stage 22a and the second stage 22b, there are no components, such as heat transfer tubes, that directly impede the movement of the liquid-phase refrigerant sprayed from the nozzle 204. Therefore, the liquid-phase refrigerant sprayed from the nozzle 204 tends to move straight between the first stage 22a and the second stage 22b. Meanwhile, a portion of the liquid-phase refrigerant sprayed from the nozzle 204 contacts the first end 22j of the heat transfer tube 202 in the first stage 22a and the second end 22k of the heat transfer tube 202 in the second stage 22b. The portion of the liquid-phase refrigerant that contacts the heat transfer tube 202 in the first stage 22a flows in the positive direction of the Z axis along the leading edge of the heat transfer tube 202 relative to the flow of the liquid-phase refrigerant. On the other hand, a portion of the liquid-phase refrigerant in contact with the heat transfer tubes 202 of the second stage 22b flows in the negative Z-axis direction along the leading edges of the heat transfer tubes 202. In addition, another portion of the liquid-phase refrigerant flows in the negative Z-axis direction along the trailing edges of the heat transfer tubes 202 of the second stage 22b. Such a flow of the liquid-phase refrigerant occurs around the heat transfer tubes 202 of each row of the first stage 22a and the second stage 22b.

[0085] As shown in FIG. 9, in the upper heat transfer tube group 22m consisting of the first stage 22a and the second stage 22b, the liquid-phase refrigerant comes into direct contact with the surfaces of the heat transfer tubes 202, causing heat transfer accompanied by forced convection, and promoting heat exchange between the liquid-phase refrigerant and the heat medium.

[0086] The liquid-phase refrigerant forms a liquid film while flowing in the negative Y-axis direction on the surfaces of the heat transfer tubes 202 of the second tier 22b, and some of the liquid-phase refrigerant forming the liquid film evaporates. The unevaporated liquid-phase refrigerant that has not completely evaporated in the upper heat transfer tube group 22m drips from the lowermost heat transfer tubes 202 of the second tier 22b toward the heat transfer tubes 202 of the lower heat transfer tube group 22c. The dripped liquid-phase refrigerant flows downward while forming a liquid film on the surfaces of the heat transfer tubes 202, and some of the liquid-phase refrigerant evaporates, while another portion of the liquid-phase refrigerant drips toward the heat transfer tubes 202 further below. Such flow and dripping of the liquid-phase refrigerant occurs around the heat transfer tubes 202 of each row of the lower heat transfer tube group 22c. In this way, the liquid-phase refrigerant sprayed from the nozzles 204 drips from the heat transfer tubes 202 of the upper heat transfer tube group 22m and is indirectly supplied to the periphery of the heat transfer tubes 202 of the lower heat transfer tube group 22c. The liquid-phase refrigerant remaining after dripping is stored at the bottom of the shell 201.

[0087] Liquid-phase refrigerant sprayed from the nozzles 204 is supplied directly to the periphery of the heat transfer tubes 202 of the upper heat transfer tube group 22m, causing forced convection. The nozzles 204 spray the liquid-phase refrigerant in a flat spray pattern having a spray axis Am, so the liquid-phase refrigerant tends to travel in a straight line between the first stage 22a and the second stage 22b. This makes it easy for forced convection of the liquid-phase refrigerant to occur even around the heat transfer tubes 202 that are far from the nozzles 204 in the upper heat transfer tube group 22m. Therefore, the surfaces of the heat transfer tubes 202 that are far from the nozzles 204 are easily wetted with the liquid-phase refrigerant, making it difficult for dryout to occur on the surfaces of the farther heat transfer tubes 202.

[0088] In addition, because the liquid-phase refrigerant drips from the heat transfer tubes 202 of the upper heat transfer tube group 22m toward the lower heat transfer tube group 22c, a liquid film of the liquid-phase refrigerant is likely to form on the surfaces of the heat transfer tubes 202 in the lower heat transfer tube group 22c that are far from the nozzle 204. Therefore, the surfaces of the heat transfer tubes 202 located far from the nozzle 204 are likely to be wetted with the liquid-phase refrigerant, and dryout is less likely to occur on the surfaces of the heat transfer tubes 202 that are far from the nozzle 204.

[0089] [3-3. Effects, etc.] As described above, in this embodiment, the nozzle 204 may have a spray axis Am that passes between the first end 22j of the plurality of heat transfer tubes 202 in the first tier 22a, which is closer to the second tier 22b, and the second end 22k of the plurality of heat transfer tubes 202 in the second tier 22b, which is closer to the first tier 22a, in the direction perpendicular to the first plane, and may spray the liquid in a flat spray pattern that passes between the first tier 22a and the second tier 22b. The spray axis Am passes between the first end 22j of the plurality of heat transfer tubes 202 in the first tier 22a and the second end 22k of the plurality of heat transfer tubes 202 in the second tier 22b. The first end 22j is the end that is closer to the second tier 22b of the plurality of heat transfer tubes 202 in the first tier 22a, in the direction perpendicular to the first plane. The second end 22k is an end of the plurality of heat transfer tubes 202 in the second stage 22b that is closer to the first stage 22a in the direction perpendicular to the first plane.

[0090] The nozzle 204 sprays the liquid-phase refrigerant in a flat spray pattern having a spray axis Am, so the liquid-phase refrigerant tends to travel in a straight line between the first stage 22a and the second stage 22b. Therefore, in the first stage 22a and the second stage 22b, forced convection of the liquid-phase refrigerant tends to occur around the heat transfer tubes 202 that are far from the nozzle 204. As a result, the surfaces of the heat transfer tubes 202 that are far from the nozzle 204 tend to be wetted with the liquid-phase refrigerant, and dryout is less likely to occur on the surfaces of the heat transfer tubes 202 that are far from the nozzle 204.

[0091] This embodiment also achieves the effects described in the second embodiment. That is, even when the heat transfer tubes 202 are arranged in multiple rows and multiple stages in the horizontal and vertical directions, the sparse region B1 can be generated only near the outlet of the first heat transfer tube group 202a, which is the uppermost heat transfer tube group. The second heat transfer tube group 202b, which is the heat transfer tube group located below, can be entirely wetted with the liquid-phase refrigerant. Therefore, dryout can be avoided without increasing the spray pressure of the first nozzle 204a and the second nozzle 204b. The technology disclosed herein can improve the heat exchange efficiency of the evaporator 401 while avoiding erosion and increasing the reliability of the evaporator 401. [Industrial Applicability]

[0092] The shell-and-tube heat exchanger disclosed herein is useful as an evaporator in an absorption refrigeration system. However, the shell-and-tube heat exchanger may be used not only as an evaporator but also as a condenser. The shell-and-tube heat exchanger disclosed herein may also be used in refrigeration systems other than absorption refrigeration systems, such as turbo refrigeration systems and vapor compression refrigeration systems. The use of the refrigeration system is not particularly limited, and examples include home or commercial air conditioning systems, chillers, process cooling systems, and heat storage systems. [Explanation of symbols]

[0093] 22a 1st stage 22b 2nd stage 22c Lower heat transfer tube group 22j 1st end 22k 2nd end 22m upper heat transfer tube bank 100 Absorption refrigeration unit 101,301,401 Evaporator 102 Absorber 103 Regenerator 104 Condenser 106 Pump 107 Spreading Tray Routes 110a, 110b, 110c, and 110d 121 Heat transfer tube 123 Heater 124 Heat transfer tube 201 Shell 201a Inlet 201b Outlet 202 Heat transfer tube 202a 1st heat transfer tube group 202b Second heat transfer tube group 202c Third heat transfer tube group 202d 4th heat transfer tube group 202e 5th heat transfer tube group 202p entrance 202q exit 204 Nozzle 204a No. 1 nozzle 204b Second nozzle 205 Circulation circuit 206 Pump 207,208 Flow path cover 209 Route 210 Partition 211 Inlet 212 Outlet Am spray shaft Bx center axis

Claims

1. A shell and a plurality of heat transfer tubes arranged parallel to one another inside the shell; a first nozzle disposed on a heat medium inlet side of the plurality of heat transfer tubes and configured to spray a liquid-phase refrigerant onto the plurality of heat transfer tubes from the inlet side toward the outlet side of the heat medium of the plurality of heat transfer tubes; A shell-and-tube heat exchanger comprising: the plurality of heat transfer tubes include a first heat transfer tube group and a second heat transfer tube group, the first heat transfer tube group is a heat transfer tube group including the heat transfer tube located at the uppermost stage inside the shell, the second heat transfer tube group is a heat transfer tube group located below the first heat transfer tube group and adjacent to the first heat transfer tube group, a flow direction of the heat medium in the first heat transfer tube group is opposite to a flow direction of the heat medium in the second heat transfer tube group, the heat medium flows through the second heat transfer tube group and the first heat transfer tube group in this order; the first nozzle is a nozzle that sprays the liquid-phase refrigerant onto the first heat transfer tube group, the shell-and-tube heat exchanger further includes a second nozzle that is disposed at a position on the heat medium outlet side of the second heat transfer tube group, the second nozzle being shifted from the position of the first nozzle toward the heat medium outlet side of the first heat transfer tube group, and that sprays the liquid-phase refrigerant onto the second heat transfer tube group. Shell and tube heat exchanger.

2. an angle θ between a direction of flow of the liquid-phase refrigerant along a spray axis of the first nozzle and a direction parallel to a longitudinal direction of the heat transfer tube and extending from an inlet to an outlet of the heat transfer tube is an acute angle; 2. The shell-and-tube heat exchanger according to claim 1.

3. the second nozzle sprays the liquid-phase refrigerant onto the second heat transfer tube group from an outlet side of the heat medium toward an inlet side of the second heat transfer tube group.

3. The shell-and-tube heat exchanger according to claim 1 or 2.

4. The spray direction of the second nozzle is the same as the spray direction of the first nozzle. The shell-and-tube heat exchanger according to any one of claims 1 to 3.

5. the shell-and-tube heat exchanger has only the first nozzle as a nozzle for spraying the liquid-phase refrigerant onto the first heat transfer tube group, The shell-and-tube heat exchanger according to any one of claims 1 to 4.

6. the plurality of heat transfer tubes include a first stage having a plurality of heat transfer tubes arranged along a first plane, and a second stage having a plurality of heat transfer tubes arranged along a second plane parallel to the first plane and adjacent to the first stage in a direction perpendicular to the first plane; the first nozzle has a spray axis that passes between a first end portion of the plurality of heat transfer tubes in the first stage that is close to the second stage in a direction perpendicular to the first plane and a second end portion of the plurality of heat transfer tubes in the second stage that is close to the first stage in a direction perpendicular to the first plane, and sprays the liquid-phase refrigerant in a flat spray pattern that passes between the first stage and the second stage. The shell-and-tube heat exchanger according to any one of claims 1 to 5.

7. A shell; a plurality of heat transfer tubes arranged parallel to one another inside the shell; a first nozzle disposed on a heat medium inlet side of the plurality of heat transfer tubes and configured to spray a liquid-phase refrigerant onto the plurality of heat transfer tubes from the inlet side toward the outlet side of the heat medium of the plurality of heat transfer tubes; Equipped with the plurality of heat transfer tubes include a first stage having a plurality of heat transfer tubes arranged along a first plane, and a second stage having a plurality of heat transfer tubes arranged along a second plane parallel to the first plane and adjacent to the first stage in a direction perpendicular to the first plane; the first nozzle has a spray axis that passes between a first end portion of the plurality of heat transfer tubes in the first stage that is close to the second stage in a direction perpendicular to the first plane and a second end portion of the plurality of heat transfer tubes in the second stage that is close to the first stage in a direction perpendicular to the first plane, and sprays the liquid-phase refrigerant in a flat spray pattern that passes between the first stage and the second stage. Shell and tube heat exchanger.

8. a flow path cover that connects an inlet for the heat medium in the first heat transfer tube group and an outlet for the heat medium in the second heat transfer tube group, The shell-and-tube heat exchanger according to any one of claims 1 to 6.

9. A method for operating the shell-and-tube heat exchanger according to any one of claims 1 to 8, comprising: causing the heat medium to flow through the plurality of heat transfer tubes; spraying the liquid-phase refrigerant from the first nozzle toward the plurality of heat transfer tubes to cause heat exchange between the heat medium and the liquid-phase refrigerant; adjusting a spray pressure of the liquid-phase refrigerant from the first nozzle so that an outer edge of the flow of the liquid-phase refrigerant sprayed from the nozzle reaches a position at a predetermined distance from the outlet toward the inlet of the plurality of heat transfer tubes; A method comprising:

10. The shell-and-tube heat exchanger according to any one of claims 1 to 8 is provided as at least one of an evaporator and a condenser. Refrigeration equipment.

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