Spray heat exchanger and refrigeration system equipped therewith

Abstract

This suppresses dryout and improves the heat exchange efficiency of spray-type heat exchangers. [Solution] The spray heat exchanger of the present disclosure comprises a shell 201, a plurality of heat transfer tubes 202 arranged inside the shell 201 along the row direction and the column direction, and a nozzle 204 arranged inside the shell 201 and spraying a liquid phase refrigerant in a flattened spray pattern toward the plurality of heat transfer tubes 202, wherein the spray axis Am of the nozzle 204 passes between a pair of heat transfer tubes 202 located in the column closest to the nozzle 204, and the spacing P1 between adjacent heat transfer tubes 202 in the row direction at the location where the spray axis Am exists is wider than the spacing P2 between adjacent heat transfer tubes 202 in the row direction at the location where the spray axis Am does not exist.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a spray-type heat exchanger and a refrigeration apparatus including the same. BACKGROUND ART

[0002] A technique for cooling a liquid inside heat transfer tubes by spraying cooling water toward the heat transfer tubes is known. A conventional evaporative condenser described in Patent Document 1 includes a plurality of water 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 PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] In the prior art, it is difficult to deliver a sufficient amount of liquid-phase refrigerant to the heat transfer tubes arranged at positions distant from the nozzles. When the liquid-phase refrigerant is insufficient, dryout may occur on the surfaces of the heat transfer tubes. "Dryout" means a phenomenon in which a large dry surface is formed on the surface of a heat transfer tube.

[0005] Increasing the spray pressure of the nozzles allows the liquid-phase refrigerant to reach farther positions. However, increasing the spray pressure may damage the heat transfer tubes due to erosion. Increasing the number of nozzles raises the cost. Further, an increased number of nozzles increases the spray amount of the liquid-phase refrigerant, which increases the thickness of the liquid film on the surfaces of the heat transfer tubes. The thicker the liquid film, the lower the heat exchange efficiency.

[0006] In view of the above circumstances, the present disclosure provides a technique suitable for suppressing dryout and improving the heat exchange efficiency of a spray-type heat exchanger. [Means for solving the problem]

[0007] This disclosure is, Shell and, Multiple heat transfer tubes arranged inside the shell along the row and column directions, A nozzle is positioned inside the shell and sprays liquid-phase refrigerant in a flat spray pattern toward the plurality of heat transfer tubes, Equipped with, The spray axis of the nozzle passes between a pair of heat transfer tubes located in the row closest to the nozzle. The spacing between adjacent heat transfer tubes in the step direction at the location where the spray axis exists is wider than the spacing between adjacent heat transfer tubes in the step direction at the location where the spray axis does not exist. We provide a spray-type heat exchanger. [Effects of the Invention]

[0008] According to the technology disclosed herein, it is possible to suppress dryout and improve the heat exchange efficiency of a spray heat exchanger. [Brief explanation of the drawing]

[0009] [Figure 1] Configuration diagram of an absorption refrigeration system according to Embodiment 1 [Figure 2] Figure 1 shows a longitudinal cross-sectional view of the evaporator of an absorption refrigeration system. [Figure 3] Longitudinal cross-section of the evaporator along line III-III shown in Figure 2. [Figure 4] Top view showing the positional relationship between the heat transfer tube and the nozzle. [Figure 5A] A diagram showing the spray pattern of liquid phase refrigerant sprayed from a nozzle. [Figure 5B] A diagram showing the spray pattern of liquid phase refrigerant sprayed from a nozzle. [Figure 6] Longitudinal cross-sectional view of the evaporator according to Embodiment 2 [Figure 7A] Partial enlarged view of Figure 3 [Figure 7B] Enlarged view of the dashed line area in Figure 7A [Figure 8A] Partial enlarged view of Figure 6 [Figure 8B] Diagram showing the arrangement of heat transfer tubes in Modification 1 [Figure 8C] Diagram showing the arrangement of heat transfer tubes in Modification 2 [Figure 9] Contour diagram showing the test results of Sample 1 and Sample 2 [Modes for Carrying Out the Invention]

[0010] (Embodiment 1) Hereinafter, Embodiment 1 will be described with reference to Figure 1 to Figure 5B.

[0011] [1-1. Configuration of Absorption Refrigeration Apparatus] Figure 1 is a configuration diagram of an absorption refrigeration apparatus 100 according to Embodiment 1. The absorption refrigeration apparatus 100 includes an evaporator 101, an absorber 102, a regenerator 103, and a condenser 104. These are interconnected by paths 110a, 110b, 110c, 110d and 209. The refrigerant and the absorption liquid in the absorption refrigeration apparatus 100 are, for example, water and a lithium bromide solution. Other examples of the refrigerant and the absorption liquid are ammonia and water.

[0012] The evaporator 101 is constituted by the spray-type heat exchanger according to Embodiment 1. The evaporator 101 includes a heat transfer tube 202 and a circulation circuit 205. A heat medium such as water flows inside 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-phase refrigerant is stored at the bottom of the evaporator 101. The liquid-phase refrigerant circulates through the circulation circuit 205 by the action of the pump 206. Specifically, the liquid-phase refrigerant is sent by the pump 206 to the nozzle 204, and is sprayed from the nozzle 204 toward the heat transfer tube 202. Heat exchange occurs between the heat medium in the heat transfer tube 202 and the sprayed liquid-phase refrigerant, whereby cold energy is extracted from the refrigerant. The refrigerant is heated and evaporates on the surface of the heat transfer tube 202. The outlet of the evaporator 101 is connected to the absorber 102 via the path 209.

[0013] The absorber 102 is constituted by, for example, a shell-and-tube heat exchanger. The absorber 102 includes heat transfer tubes 121 and a distribution tray 107. A heat medium such as water flows inside the heat transfer tubes 121. Absorbent liquid is distributed from the distribution tray 107 toward the heat transfer tubes 121. The absorbent liquid is cooled on the surfaces of the heat transfer tubes 121, and the vapor-phase refrigerant is absorbed into the absorbent liquid. The outlet of the absorber 102 is connected to the inlet of the regenerator 103 via a path 110a. The path 110a includes a pump 106.

[0014] The regenerator 103 is provided with a heater 123 for heating the absorbent liquid. The heater 123 may be a boiler itself, or may be a circuit in which a heat medium heated by a boiler circulates. The bottom of the regenerator 103 is connected to the distribution tray 107 of the absorber 102 via a path 110d. Since the internal pressure of the regenerator 103 is higher than the internal pressure of the absorber 102, the absorbent liquid is sent from the bottom of the regenerator 103 to the distribution tray 107 by the pressure difference. The outlet of the regenerator 103 is connected to the inlet of the condenser 104 via a path 110b.

[0015] The condenser 104 is constituted by, for example, 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 is provided with, 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 surfaces of the heat transfer tubes 124. The outlet of the condenser 104 is connected to the inlet of the evaporator 101 via a path 110c.

[0016] The path 110a and the path 110b are vapor paths. The path 110c and the path 110d are liquid paths. Each path is constituted by at least one metal pipe.

[0017] [1-2. Operation of Absorption Refrigeration Apparatus] The operation and effect of the absorption refrigeration apparatus 100 configured as described above will be explained below.

[0018] In the evaporator 101, liquid-phase refrigerant is pumped by the pump 206 through the circulation circuit 205 to the nozzle 204 and sprayed from the nozzle 204 as a mist onto the heat transfer tubes 202. The sprayed liquid-phase refrigerant evaporates by exchanging heat with the heat transfer medium flowing inside the heat transfer tubes 202 on the surface of the heat transfer tubes 202. This generates a low-temperature, low-pressure gaseous-phase refrigerant. The gaseous-phase refrigerant is drawn into the absorber 102 via the path 209. In the absorber 102, the gaseous-phase refrigerant is absorbed by the absorbent liquid dripped from the spray tray 107. At this time, the absorbent liquid is cooled by the heat transfer tubes 121 and absorbs the gaseous-phase refrigerant on the surface of the heat transfer tubes 121. After that, the absorbent liquid flows down to the bottom of the absorber 102 and is sent to the regenerator 103 via the path 110a. Just before flowing into the regenerator 103, the absorbent liquid is a mixture of absorbent and refrigerant. After flowing into the regenerator 103, the absorbent liquid is heated by the heater 123. Heating vaporizes the refrigerant components with lower boiling points, separating them as high-temperature gaseous refrigerant. The absorbent liquid is sent to the spray tray 107 via path 110d. The separated high-temperature gaseous refrigerant is sent to the condenser 104 via path 110b. The high-temperature gaseous refrigerant is cooled and condensed by the heat transfer tube 124. This generates liquid refrigerant. The liquid refrigerant is sent to the evaporator 101 via path 110c. The above cycle is repeated.

[0019] The absorption refrigeration system 100 is applied, for example, to commercial or residential air conditioning systems. The heat transfer medium cooled in the evaporator 101 is supplied to the room and used for cooling the room. Alternatively, the heat transfer medium heated in the condenser 104 is supplied to the room and used for heating the room. The heat transfer medium is, for example, water. However, the application of the absorption refrigeration system 100 is not limited to air conditioning systems, and may also be other devices such as chillers or thermal storage devices.

[0020] [1-3. Evaporator Configuration] Figure 2 is a longitudinal cross-sectional view of the evaporator 101 of the absorption chiller 100 shown in Figure 1. Figure 3 is a longitudinal cross-sectional view of the evaporator 101 along line III-III shown in Figure 2. The evaporator 101 is composed of a spray heat exchanger. A spray heat exchanger is a type of shell-and-tube heat exchanger. The evaporator 101 comprises a shell 201, a plurality of heat transfer tubes 202, and at least one nozzle 204. In Figures 2 and 3, the Z axis represents an axis parallel to the vertical direction. The X and Y axes represent axes parallel to the horizontal direction.

[0021] The shell 201 is, for example, a container having a rectangular or circular cross-sectional shape. The container may be a pressure vessel. The shell 201 includes an inlet 201a and an outlet 201b. A path 110c is connected to the inlet 201a. An absorber 102 is connected to the outlet 201b via a path 209. Through the inlet 201a, liquid-phase refrigerant flows into the shell 201 from the outside. Through the outlet 201b, gaseous-phase refrigerant generated on the surfaces of the multiple heat transfer tubes 202 is guided to the outside of the shell 201.

[0022] Multiple heat transfer tubes 202 are arranged parallel to each other inside the shell 201 along the tier direction and the column direction. In this embodiment, the tier direction is parallel to the vertical direction, and the column direction is parallel to the horizontal direction. With this configuration, liquid phase refrigerant can be dripped from the heat transfer tubes 202 of the upper tier to the heat transfer tubes 202 of the lower tier by gravity. Multiple heat transfer tubes 202 are arranged in multiple tiers along the vertical direction (Z-axis direction) and in multiple columns along the horizontal direction (Y-axis direction). The longitudinal direction of the heat transfer tubes 202 is parallel to the horizontal direction (X-axis direction). The heat transfer tubes 202 are, for example, heat transfer tubes having a circular cross-sectional shape. The heat transfer tubes 202 are made of metal such as copper or stainless steel, and are typically copper tubes.

[0023] The multiple heat transfer tubes 202 include a plurality of first heat transfer tubes 202a belonging to the first stage in the step direction, and a plurality of second heat transfer tubes 202b belonging to the second stage adjacent to the first stage in the step direction. The plane containing the spray axis Am of the nozzle 204 passes between the first stage and the second stage. The first stage is any stage located above the spray axis Am. The second stage is a stage located below the spray axis Am. The first stage may be the uppermost stage in the vertical direction. The second stage may be the second-to-last stage in the vertical direction. By spraying a liquid-phase refrigerant between the uppermost stage and the second-to-last stage, it is possible to avoid the formation of heat transfer tubes 202 that do not contribute to heat exchange.

[0024] In this embodiment, twelve heat transfer tubes 202 are arranged in the row direction (Y-axis direction). However, the number of heat transfer tubes 202 in the row direction is not particularly limited. For example, the number of heat transfer tubes 202 in the row direction can range from 12 to 24.

[0025] 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 Figure 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 transfer medium. The flow path cover 207 is attached to the shell 201 so as to cover the inlets or outlets of a plurality of heat transfer tubes 202. The flow path cover 208 has an outlet 212 for the heat transfer medium. The flow path cover 208 is attached to the shell 201 so as to cover the inlets or outlets of a plurality of heat transfer tubes 202. The heat transfer medium flows into the evaporator 101 through the flow path cover 207 and flows out of the evaporator 101 through the flow path cover 208. The flow path cover 207 may be provided with both an inlet 211 and an outlet 212.

[0026] In this embodiment, the heat transfer medium is distributed and flows through a 3-stage x 12-column heat transfer tube 202.

[0027] Multiple partition plates 210 are arranged inside the flow path cover 207. Multiple partition plates 210 are arranged inside the flow path cover 208. The partition plates 210 are arranged every three stages inside either the flow path cover 207 or the flow path cover 208. The flow direction of the heat transfer medium reverses inside the flow path cover 207 and the flow path cover 208. After flowing into the flow path cover 207, the heat transfer medium flows through the lowest stage of heat transfer tubes, meandering in a serpentine shape towards the uppermost stage of heat transfer tubes. After flowing through the uppermost stage of heat transfer tubes, the heat transfer medium flows out to the outside through the flow path cover 208. "Heat transfer tube group" refers to multiple heat transfer tubes 202 arranged in sets of three stages.

[0028] The flow path cover 207 connects the inlet and outlet of the heat transfer medium in an adjacent heat transfer tube group. The flow path cover 208 connects the inlet and outlet of the heat transfer medium in an adjacent heat transfer tube group. Through the action of flow path covers 207 and 208, the flow direction of the heat transfer medium can be smoothly changed.

[0029] The nozzle 204 is located inside the shell 201 and sprays a liquid-phase coolant in a flattened spray pattern toward a plurality of heat transfer tubes 202. The liquid-phase coolant is, for example, liquid water. In this embodiment, the spray axis Am of the nozzle 204 passes between a pair of heat transfer tubes 202 located in the row closest to the nozzle 204. The long axis direction of the flattened spray pattern is perpendicular to the step direction. The spacing P1 between adjacent heat transfer tubes 202 in the step direction at the location where the spray axis Am exists is wider than the spacing P2 between adjacent heat transfer tubes 202 in the step direction at the location where the spray axis Am does not exist. The "spacing between adjacent heat transfer tubes 202 in the step direction" (so-called step pitch) means the distance between the centers of a pair of heat transfer tubes 202 in the step direction (vertical direction).

[0030] In this embodiment, the nozzles 204 are arranged at multiple positions in the stepped direction. The nozzles 204 may also be arranged at multiple positions along the longitudinal direction of the heat transfer tubes 202. With this configuration, the surfaces of multiple heat transfer tubes 202 can be uniformly wetted with liquid-phase coolant.

[0031] The structure and characteristics of each nozzle 204 are identical to those of the others. In other words, nozzles from the same product can be used for each nozzle 204. This reduces the cost of the evaporator 101. In this embodiment, the circulation circuit 205 is shared by each nozzle 204. Therefore, excluding the pressure loss in the circulation circuit 205, the spray pressure of each nozzle 204 is equal to those of the others.

[0032] Figure 4 is a top view showing the positional relationship between the heat transfer tube 202 and the nozzle 204. The dashed lines represent the outer edges E1 and E2 in plan view of the sprayed liquid phase refrigerant flow. The spray axis Am is the central axis of the nozzle 204 and passes through the center of the nozzle hole. The spray axis Am passes through the center of the sprayed liquid phase refrigerant flow. The sprayed liquid phase refrigerant flow is a sector with a spread angle α in plan view. The spread angle α is, for example, 120 degrees.

[0033] The spray axis Am is parallel to the plane (XY plane) containing the central axis Bx of the heat transfer tube 202. The central axis Bx is parallel to the longitudinal direction of the heat transfer tube 202 and passes 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 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, 60 degrees.

[0034] In this embodiment, the nozzle 204 is located on only one side in the row direction (Y-axis direction) and not on the other side in the row direction. According to this embodiment, even if the nozzle 204 is located on only one side in the row direction, a sufficient amount of liquid-phase coolant can be delivered to the surface of the heat transfer tube 202, which is located at a distance from the nozzle 204.

[0035] For example, in the absorption refrigeration system 100 shown in Figure 1, when the evaporator 101 and absorber 102 are integrally formed, an eliminator is provided in the path 209 to prevent refrigerant droplets from moving directly from the evaporator 101 to the absorber 102. In this case, it is difficult to secure space to place a nozzle 204 between the path 209 and the heat transfer tubes 202 of the evaporator 101. Such space may lead to an increase in the size of the evaporator 101 and absorber 102. Therefore, it is sometimes required to place the nozzle 204 on only one side in the row direction. If the nozzle 204 is placed on only one side in the row direction, it is difficult for the liquid phase refrigerant to reach the heat transfer tubes 202 located far from the nozzle 204. However, with the evaporator 101 of this embodiment, a sufficient amount of liquid phase refrigerant can be delivered to the heat transfer tubes 202 located far from the nozzle 204. When there are space constraints for the nozzle 204, adopting the evaporator 101 of this embodiment can provide a higher dry-out suppression effect.

[0036] Figures 5A and 5B show the spray patterns of the liquid phase refrigerant sprayed from the nozzle 204. As shown in Figure 5A, the liquid phase refrigerant sprayed from the nozzle 204 forms a fan-shaped spray region M. Furthermore, the shape of the spray region S that appears when this spray pattern is projected onto a plane H perpendicular to the spray axis Am is flattened. The liquid phase refrigerant sprayed in this spray pattern passes between the heat transfer tubes 202.

[0037] The spray region S, which represents the spray pattern, has a major axis L. The major axis L is parallel to the XY plane and perpendicular to the stage direction (Z-axis direction) of the evaporator 101. The plane containing the major axis L and the spray axis Am passes between adjacent heat transfer tubes 202 in the stage direction.

[0038] [1-4. Evaporator Operation] The operation and function of the evaporator 101, configured as described above, will be explained below.

[0039] A heat transfer medium such as water flows from the inlet 211 into the flow path cover 207, and then flows through the flow path cover 207 into the heat transfer tube 202. The heat transfer medium then flows through the heat transfer tube 202, passes through the flow path cover 208, and flows out from the outlet 212.

[0040] The liquid-phase refrigerant is pumped by the pump 206 through the circulation circuit 205 to the nozzle 204, and sprayed from the nozzle 204 in a mist state onto the heat transfer tube 202. The flow of the liquid-phase refrigerant has a spread angle α. The sprayed liquid-phase refrigerant evaporates upon heat exchange with the heat transfer medium on the surface of the heat transfer tube 202.

[0041] The liquid-phase refrigerant sprayed from the nozzle 204 travels in a row direction through the heat transfer tubes 202. A portion of the liquid-phase refrigerant comes into contact with the heat transfer tubes 202, flows along their surfaces, and drips onto the heat transfer tubes 202 below. The spacing P1 of the heat transfer tubes 202 at the location where the spray axis Am is present is wider than the spacing P2 of the heat transfer tubes 202 at the location where the spray axis Am is absent. Therefore, at the location where the spray axis Am is present, a flow of liquid-phase refrigerant in the form of a mist of a predetermined thickness can easily pass through the heat transfer tubes 202. In this case, a sufficient amount of liquid-phase refrigerant can reach the heat transfer tubes 202 located far from the nozzle 204. As a result, the surfaces of multiple heat transfer tubes 202 are uniformly wetted with the liquid-phase refrigerant.

[0042] On the other hand, since the spacing P2 between the heat transfer tubes 202 is relatively narrow in the position where the spray axis Am is absent, the distance the refrigerant droplets fall is short in the position where the spray axis Am is absent. In this case, the droplets are less affected by the flow of vapor inside the shell 201, and the variation in the droplet's fall position is small. When the variation in the droplet's fall position is small, the droplets can fall from near the bottom of the upper heat transfer tube 202 to near the top of the lower heat transfer tube 202. As a result, the surface of the lower heat transfer tube 202 is uniformly wetted with the liquid phase refrigerant.

[0043] As described above, according to this embodiment, liquid-phase refrigerant can be stably dripped from the upper heat transfer tube 202 to the lower heat transfer tube 202, while a sufficient amount of liquid-phase refrigerant can also be delivered to the heat transfer tube 202 located at a distance from the nozzle 204. As a result, dry-out on the surface of the heat transfer tube 202 is suppressed, and the heat exchange efficiency of the evaporator 101 is improved.

[0044] (Embodiment 2) Embodiment 2 will be described below with reference to Figures 6 to 9. Components identical to those in Embodiment 1 are given the same numbers and detailed descriptions are omitted.

[0045] [2-1. Evaporator Configuration] Figure 6 is a longitudinal cross-sectional view of the evaporator 301 according to Embodiment 2. As described in Embodiment 1, the plurality of heat transfer tubes 202 include a plurality of first heat transfer tubes 202a belonging to the first stage in the stage direction and a plurality of second heat transfer tubes 202b belonging to the second stage adjacent to the first stage in the stage direction. In this embodiment, the distance P3 between adjacent first heat transfer tubes 202a and second heat transfer tubes 202b in the front row M1 is wider than the distance P1 between adjacent first heat transfer tubes 202a and second heat transfer tubes 202b in the rear row M2. The distance from the nozzle 204 to the front row M1 is shorter than the distance from the nozzle 204 to the rear row M2. With this configuration, dryout can be suppressed and the heat exchange efficiency of the evaporator 301 can be further improved.

[0046] In this embodiment, the front row M1 includes multiple rows. Similarly, the rear row M2 includes multiple rows. The number of rows included in the front row M1, i.e., the number of heat transfer tubes 202 included in the front row M1, is not particularly limited. The number of rows included in the rear row M2, i.e., the number of heat transfer tubes 202 included in the rear row M2, is also not particularly limited. In one example, the number of rows included in the front row M1 is equal to the number of rows included in the rear row M2. The technology of this disclosure is particularly useful when there are many heat transfer tubes in the row direction.

[0047] Furthermore, the spacing P1 or P3 between adjacent heat transfer tubes 202 in the step direction at a location where the spray axis Am exists is wider than the spacing P2 between adjacent heat transfer tubes 202 in the step direction at a location where the spray axis Am does not exist. In other words, the evaporator 301 of this embodiment satisfies the relationship spacing P3 > spacing P1 > spacing P2. In one example, the ratio of spacing P1 to spacing P2 (P1 / P2) is from 1.1 to 1.2. The ratio of spacing P3 to spacing P2 (P3 / P2) is from 1.15 to 1.25, where spacing P3 > spacing P1.

[0048] [2-2. Evaporator Operation] Figure 7A is a partially enlarged view of Figure 3 showing the evaporator 101 of Embodiment 1. Figure 7B is an enlarged view of the dashed line portion of Figure 7A. As shown in Figures 7A and 7B, the liquid phase refrigerant sprayed from the nozzle 204 travels in the row direction through the heat transfer tubes 202. Due to the contact resistance between the liquid phase refrigerant and the heat transfer tubes 202, the more rows of heat transfer tubes 202 there are, the more difficult it becomes for the liquid phase refrigerant to reach the heat transfer tubes 202 located further away from the nozzle 204.

[0049] Figure 8A is a partially enlarged view of Figure 6 showing the evaporator 301 of this embodiment. As shown in Figure 8A, according to this embodiment, the distance P3 between adjacent first heat transfer tubes 202a and second heat transfer tubes 202b in the front row M1 is wider than the distance P1 between adjacent first heat transfer tubes 202a and second heat transfer tubes 202b in the rear row M2. With this configuration, the contact resistance between the heat transfer tubes 202 in the front row M1 and the liquid phase refrigerant is reduced, and the liquid phase refrigerant can easily reach the heat transfer tubes 202 in the rear row M2. In other words, a sufficient amount of liquid phase refrigerant can reach the heat transfer tubes 202 that are located far from the nozzle 204. As a result, the surfaces of multiple heat transfer tubes 202 are uniformly wetted with the liquid phase refrigerant.

[0050] In the step direction (Z-axis direction), the position of the first heat transfer tube 202a in the front row M1 is different from the position of the first heat transfer tube 202a in the rear row M2. The first heat transfer tube 202a in the front row M1 is located higher in the step direction than the first heat transfer tube 202a in the rear row M2. In the step direction, the position of the second heat transfer tube 202b in the front row M1 is the same as the position of the second heat transfer tube 202b in the rear row M2. The centers of the second heat transfer tube 202b in the front row M1 and the centers of the second heat transfer tube 202b in the rear row M2 are located on the same plane parallel to the horizontal direction. With this configuration, the relationship P3 > P2 is satisfied.

[0051] Figure 8B shows the arrangement of the heat transfer tubes 202 in modified example 1. In the step direction (Z-axis direction), the position of the first heat transfer tube 202a included in the front row M1 is different from the position of the first heat transfer tube 202a included in the rear row M2. The first heat transfer tube 202a included in the front row M1 is located above the first heat transfer tube 202a included in the rear row M2 in the step direction. In the step direction, the position of the second heat transfer tube 202b included in the front row M1 is different from the position of the second heat transfer tube 202b included in the rear row M2. The second heat transfer tube 202b included in the front row M1 is located below the second heat transfer tube 202b included in the rear row M2 in the step direction. With this configuration, the relationship P3 > P2 is satisfied.

[0052] Figure 8C shows the arrangement of the heat transfer tubes 202 in modified example 2. In the step direction (Z-axis direction), the position of the first heat transfer tube 202a included in the front row M1 is the same as the position of the first heat transfer tube 202a included in the rear row M2. The centers of the first heat transfer tube 202a included in the front row M1 and the centers of the first heat transfer tube 202a included in the rear row M2 are located on the same plane parallel to the horizontal direction. In the step direction, the position of the second heat transfer tube 202b included in the front row M1 is different from the position of the second heat transfer tube 202b included in the rear row M2. The second heat transfer tube 202b included in the front row M1 is located lower in the step direction than the second heat transfer tube 202b included in the rear row M2. With this configuration, the relationship P3 > P2 is satisfied. [Examples]

[0053] An experiment to verify the effect obtained in the evaporator 301 of Embodiment 2 was conducted using the following method.

[0054] (Sample 1) Heat transfer tubes with an outer diameter of 12.7 mm and a length of 1020 mm were arranged in 5 rows x 24 columns. For the first and second rows of heat transfer tubes, as explained with reference to Figure 8A, the number of columns in the front row M1 was set to 12, and the number of columns in the rear row M2 was also set to 12. In the front row M1, the spacing P3 between the first heat transfer tube 202a and the second heat transfer tube 202b was set to 21.5 mm. In the rear row M2, the spacing P1 between the first heat transfer tube 202a and the second heat transfer tube 202b was set to 17.5 mm. The vertical spacing between the heat transfer tubes in the second to fifth rows was set to 17.5 mm. The spacing between the heat transfer tubes in the column direction was 20.0 mm.

[0055] (Sample 2) Heat transfer tubes with an outer diameter of 12.7 mm and a length of 1020 mm were arranged in 5 rows x 24 columns. For the first and second rows of heat transfer tubes, the number of columns in the front row M1 was set to 12, and the number of columns in the rear row M2 was also set to 12. In the front row M1, the spacing between the first heat transfer tube 202a and the second heat transfer tube 202b was set to 17.5 mm. In the rear row M2, the spacing between the first heat transfer tube 202a and the second heat transfer tube 202b was set to 21.5 mm. The vertical spacing of the heat transfer tubes from the second to the fifth rows was set to 17.5 mm. In other words, the arrangement of the heat transfer tubes in Sample 2 was the reverse of the arrangement in Sample 1 (the arrangement in this disclosure). In Sample 2, the spacing of the heat transfer tubes was narrower near the nozzle and wider further away from the nozzle.

[0056] (Spray test) A test was conducted in which water was sprayed in a flattened spray pattern onto the structures of Samples 1 and 2. The spray axis passed between the first and second heat transfer tubes. The angle θ of the spray axis (see Figure 4) was set to 60 degrees. The spread angle α (see Figure 4) was 112 degrees. The amount of water sprayed from the nozzle was 5.42 L / min. After a sufficient amount of time had elapsed since the start of spraying, the heat transfer tube located at the bottom (5th stage) was divided into multiple blocks vertically and horizontally, and the water droplets dripping onto each block were observed with a camera. The score for each block was recorded according to the judgment criteria shown in Table 1 below. In Table 1, "Dripping Area" indicates the ratio of the area where liquid droplets are dripping in each block. The results are shown in Figure 9.

[0057] [Table 1]

[0058] Figure 9(a) is a contour plot showing the test results for Sample 1. Figure 9(b) is a contour plot showing the test results for Sample 2. In the contour plots of Figure 9, each block is shown in five levels of intensity. The darkest block corresponds to a score of "5" in Table 1. The white block corresponds to a score of "0" in Table 1. The nozzle is located in the lower right corner of the contour plot in Figure 9.

[0059] As shown in Figure 9(a), with the arrangement of Sample 1, a sufficient amount of droplets was observed even at positions far from the nozzle. In contrast, with the arrangement of Sample 2, the amount of droplets was insufficient at positions far from the nozzle, and there was an overall uneven distribution of droplet amounts.

[0060] According to the results shown in Figures 9(a) and 9(b), it is desirable that the distance P3 between adjacent first heat transfer tubes 202a and second heat transfer tubes 202b in the front row M1 be wider than the distance P1 between adjacent first heat transfer tubes 202a and second heat transfer tubes 202b in the rear row M2.

[0061] [3. Addendum] Based on the above description of embodiments, the following technologies are disclosed.

[0062] (Technology 1) Shell and, Multiple heat transfer tubes arranged inside the shell along the row and column directions, A nozzle is positioned inside the shell and sprays liquid-phase refrigerant in a flat spray pattern toward the plurality of heat transfer tubes, Equipped with, The spray axis of the nozzle passes between a pair of heat transfer tubes located in the row closest to the nozzle. The spacing between adjacent heat transfer tubes in the step direction at the location where the spray axis exists is wider than the spacing between adjacent heat transfer tubes in the step direction at the location where the spray axis does not exist. Spray heat exchanger.

[0063] According to the technology disclosed herein, it is possible to suppress dryout and improve the heat exchange efficiency of a spray heat exchanger.

[0064] (Technology 2) The plurality of heat transfer tubes include a plurality of first heat transfer tubes belonging to a first stage in the stage direction and a plurality of second heat transfer tubes belonging to a second stage adjacent to the first stage in the stage direction, the plane including the spray axis passes between the first stage and the second stage, the distance between adjacent first and second heat transfer tubes in the front row is wider than the distance between adjacent first and second heat transfer tubes in the rear row, and the distance from the nozzle to the front row is shorter than the distance from the nozzle to the rear row, as described in Technical 1. With such a configuration, dryout can be suppressed and the heat exchange efficiency of the spray heat exchanger can be further improved.

[0065] (Technology 3) A spray heat exchanger according to Art 2, wherein the front row includes multiple rows and the rear row includes multiple rows. The art of this disclosure is particularly useful when there are many heat transfer tubes in the row direction.

[0066] (Technology 4) A spray-type heat exchanger according to any one of the technologies 1 to 3, wherein the stage direction is parallel to the vertical direction and the column direction is parallel to the horizontal direction. With such a configuration, liquid phase refrigerant can be dripped from the heat transfer tubes of the upper stage to the heat transfer tubes of the lower stage by gravity.

[0067] (Technology 5) The spray-type heat exchanger according to any one of the technologies 1 to 4, wherein the nozzles are arranged at multiple positions in the step direction. With this configuration, the surfaces of multiple heat transfer tubes can be uniformly wetted with a liquid-phase coolant.

[0068] (Technology 6) The spray-type heat exchanger according to Art 5, wherein the nozzles are located on only one side in the row direction. According to the Art of the Disclosure, even if the nozzles are located on only one side in the row direction, a sufficient amount of liquid-phase coolant can be delivered to the surface of heat transfer tubes located at a distance from the nozzles.

[0069] (Technology 7) Shell and, Multiple heat transfer tubes arranged inside the shell along the row and column directions, A nozzle is positioned inside the shell and sprays liquid-phase refrigerant in a flat spray pattern toward the plurality of heat transfer tubes, Equipped with, The spray axis of the nozzle passes between a pair of heat transfer tubes located in the row closest to the nozzle. The plurality of heat transfer tubes include a plurality of first heat transfer tubes belonging to the first stage in the step direction, and a plurality of second heat transfer tubes belonging to the second stage adjacent to the first stage in the step direction. The plane including the spray axis passes between the first stage and the second stage, The spacing between adjacent first and second heat transfer tubes in the front row is wider than the spacing between adjacent first and second heat transfer tubes in the rear row. The distance from the nozzle to the front row is shorter than the distance from the nozzle to the rear row. Spray heat exchanger.

[0070] According to the technology disclosed herein, it is possible to suppress dryout and improve the heat exchange efficiency of a spray heat exchanger.

[0071] (Technology 8) A refrigeration system comprising, as at least one of the evaporator and condenser, a spray heat exchanger as described in any one of the Technical Sections 1 to 7. [Industrial applicability]

[0072] The spray heat exchanger disclosed herein is useful as an evaporator in an absorption refrigeration system. However, the spray heat exchanger may be used not only as an evaporator but also as a condenser. Furthermore, the spray heat exchanger disclosed herein can be used in refrigeration systems other than absorption refrigeration systems, such as turbo refrigeration systems and vapor compression refrigeration systems. The applications of the refrigeration system are not particularly limited and include household or commercial air conditioning systems, chillers, process cooling systems, and thermal energy storage systems. [Explanation of Symbols]

[0073] 100 Absorption Refrigeration System 101,301 Evaporator 102 Absorber 103 Regenerator 104 Condenser 106 Pump 107 Spray Tray Routes 110a, 110b, 110c, 110d 121 Heat transfer tube 123 Heater 124 Heat transfer tubes 201 Shell 201a Inlet 201b Outlet 202 Heat transfer tube 202a First heat transfer tube 202b Second heat transfer tube 204 nozzles 205 Circulation circuit 206 Pump 207,208 Flow channel cover 209 routes 210 Partition Plate 211 Inlet 212 Outlet Am spray shaft Bx center axis

Claims

1. Shell and, Multiple heat transfer tubes arranged inside the shell along the row and column directions, A nozzle is positioned inside the shell and sprays liquid-phase refrigerant in a flat spray pattern toward the plurality of heat transfer tubes, Equipped with, The spray axis of the nozzle passes between a pair of heat transfer tubes located in the row closest to the nozzle. The spacing between adjacent heat transfer tubes in the step direction at the location where the spray axis exists is wider than the spacing between adjacent heat transfer tubes in the step direction at the location where the spray axis does not exist. Spray heat exchanger.

2. The plurality of heat transfer tubes include a plurality of first heat transfer tubes belonging to the first stage in the step direction, and a plurality of second heat transfer tubes belonging to the second stage adjacent to the first stage in the step direction. The plane including the spray axis passes between the first stage and the second stage, The spacing between adjacent first and second heat transfer tubes in the front row is wider than the spacing between adjacent first and second heat transfer tubes in the rear row. The distance from the nozzle to the front row is shorter than the distance from the nozzle to the rear row. A spray-type heat exchanger according to claim 1.

3. The aforementioned front row includes multiple rows, The aforementioned rear row includes multiple rows, The spray-type heat exchanger according to claim 2.

4. The aforementioned step direction is parallel to the vertical direction, The aforementioned column direction is parallel to the horizontal direction. A spray-type heat exchanger according to claim 1.

5. The nozzles are arranged at multiple positions in the step direction. A spray-type heat exchanger according to claim 1.

6. The nozzle is located on only one side in the row direction. The spray-type heat exchanger according to claim 5.

7. Shell and, Multiple heat transfer tubes arranged inside the shell along the row and column directions, A nozzle is positioned inside the shell and sprays liquid-phase refrigerant in a flat spray pattern toward the plurality of heat transfer tubes, Equipped with, The spray axis of the nozzle passes between a pair of heat transfer tubes located in the row closest to the nozzle. The plurality of heat transfer tubes include a plurality of first heat transfer tubes belonging to the first stage in the step direction, and a plurality of second heat transfer tubes belonging to the second stage adjacent to the first stage in the step direction. The plane including the spray axis passes between the first stage and the second stage, The spacing between adjacent first and second heat transfer tubes in the front row is wider than the spacing between adjacent first and second heat transfer tubes in the rear row. The distance from the nozzle to the front row is shorter than the distance from the nozzle to the rear row. Spray heat exchanger.

8. The spray-type heat exchanger described in claim 1 is provided as at least one of the evaporator and the condenser. Refrigeration equipment.

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