Heat exchange unit for absorption chiller, absorption chiller, and heat exchange method

Abstract

To provide an absorption refrigerator heat exchange unit advantageous for enhancing wettability of solution having high viscosity on heat transfer tubes.SOLUTION: An absorption refrigerator heat exchange unit 1 according to the present disclosure comprises a first container 5a, a first heat transfer tube group 6f, a first dropper 7a, a second container 5b, a second heat transfer tube group 6s, and a second dropper 7b. The first dropper 7a comprises a plurality of first dropping parts 74a arranged along a longitudinal direction of first heat transfer tubes 6a. Refrigerant liquid is dropped toward the first heat transfer tube group 6f from the first dropping parts 74a. The second dropper 7b comprises a plurality of second dropping parts 74b arranged along a longitudinal direction of second heat transfer tubes 6b. Solution is dropped toward the second heat transfer tube group 6s from the second dropping parts 74b. A distance P2 between the second dropping parts 74b adjacent to each other in the longitudinal direction of the second heat transfer tubes 6b is smaller than a distance P1 of the first dropping parts 74a adjacent to each other in the longitudinal direction of the first heat transfer tubes 6a.SELECTED DRAWING: Figure 1

Description

【Technical Field】 【0001】 The present disclosure relates to a heat exchange unit for an absorption refrigerator, an absorption refrigerator, and a heat exchange method. 【Background Art】 【0002】 Conventionally, a liquid spraying device for an absorption refrigerator having a configuration for dropping a liquid is known. 【0003】 For example, the liquid spraying device described in Patent Document 1 includes a tray and a guide body. The tray has a long structure for receiving the liquid to be sprayed. The guide body has a large number of dropping ports provided in the longitudinal direction, and the liquid is dropped from the dropping ports. A blocking wall is provided on the guide body, and the blocking wall has a long-side partition and a short-side partition. The long-side partition blocks the open end on the long-side of the liquid receiving portion of the guide body. The short-side partition blocks the open end on the short-side of the liquid receiving portion. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Patent Laid-Open No. 7-4782 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 The present disclosure provides a heat exchange unit for an absorption refrigerator that is advantageous for enhancing the wettability in a heat transfer tube of a solution having a viscosity higher than the viscosity of a refrigerant liquid in an evaporator of an absorption refrigerator. 【Means for Solving the Problems】 【0006】 The heat exchange unit for an absorption refrigerator in the present disclosure is a first container, a first heat transfer tube group including a plurality of first heat transfer tubes arranged in a plurality of stages and a plurality of rows inside the first container, A first dripper having a plurality of first dripping parts arranged along the longitudinal direction of the first heat transfer tube, which drips refrigerant liquid from the first dripping parts toward the first heat transfer tube group, The second container, The second heat transfer tube group includes a plurality of second heat transfer tubes arranged in multiple stages and multiple rows inside the second container, A second dropper is provided, which has a plurality of second dropping points arranged along the longitudinal direction of the second heat transfer tube, and which drops a solution from the second dropping points toward the group of second heat transfer tubes, The distance between adjacent second dripping parts in the longitudinal direction of the second heat transfer tube is smaller than the distance between adjacent first dripping parts in the longitudinal direction of the first heat transfer tube. [Effects of the Invention] 【0007】 The heat exchange unit for absorption refrigerators in this disclosure facilitates the formation of a uniform liquid film on the second heat transfer tube due to the small spacing between the solution droplets dropped from multiple second dropper points. Therefore, the heat exchange unit for absorption refrigerators in this disclosure is advantageous for improving the wettability of the heat transfer tubes of a solution having a viscosity higher than that of the refrigerant liquid in the evaporator of the absorption refrigerator. [Brief explanation of the drawing] 【0008】 [Figure 1] Diagram showing the heat exchange unit of Embodiment 1 [Figure 2A] Figure 1 is a cross-sectional view showing the first dripper and first heat transfer tube of the heat exchange unit. [Figure 2B] Figure 1 shows a cross-section of the first dripper and the first heat transfer tube of the heat exchange unit. [Figure 3A] Cross-sectional view showing the second dripper and second heat transfer tube of the heat exchange unit in Figure 1. [Figure 3B] Figure 1 shows a cross-section of the second dripper and the second heat transfer tube of the heat exchange unit. [Figure 4] Diagram showing the cross-section of a dripper and heat transfer tubes in a reference example. [Figure 5A] This figure shows a cross-section of the second dripper and the second heat transfer tube of the heat exchange unit of Embodiment 2 at time t. [Figure 5B] This figure shows a cross-section of the second dripper and the second heat transfer tube of the heat exchange unit in Embodiment 2 at time t+Δt. [Figure 6A] A diagram showing the cross-section of a dripper and heat transfer tubes in a reference example at time t. [Figure 6B] A diagram showing the cross-section of a dripper and heat transfer tubes in a reference example at time t+Δt. [Figure 7] Diagram showing an absorption chiller of Embodiment 3 [Modes for carrying out the invention] 【0009】 (Knowledge that forms the basis of this disclosure) At the time the inventors conceived this disclosure, spray-type and atomizing devices had been devised as techniques to improve the wettability of liquids in heat transfer tubes in absorption chillers. However, it was difficult to adapt atomizing devices to the absorbers of absorption chillers, and from the viewpoint of commonizing parts between evaporators and absorbers, it was common to use spray-type devices in both evaporators and absorbers. Under these circumstances, the inventors noticed that the wettability of the solution in the heat transfer tubes of the absorber was lower than that of the refrigerant liquid in the heat transfer tubes of the evaporator, and conceived the idea of ​​configuring a dropper specifically for dropping the solution in the absorber. In order to realize this idea, the inventors discovered that there was a problem in that high-viscosity solutions do not spread easily when they adhere to the heat transfer tubes by dropping, and the subject of this disclosure was formed to solve this problem. 【0010】 Therefore, this disclosure provides a heat exchange unit for an absorption chiller that is advantageous for improving the wettability of a solution having a viscosity higher than the viscosity of the refrigerant liquid in the evaporator of the absorption chiller in the heat exchange tube. 【0011】 Hereinafter, embodiments will be described in detail with reference to the drawings. However, a more detailed description than necessary may be omitted. For example, a detailed description of well-known matters or a redundant description of substantially the same configuration may be omitted. Note that 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. 【0012】 (Embodiment 1) Hereinafter, Embodiment 1 will be described with reference to FIGS. 1, 2A, 2B, 3A, and 3B. In the attached drawings, the negative z-axis direction is the gravitational direction. The x-axis, y-axis, and z-axis are orthogonal to each other. 【0013】 [1-1. Configuration] As shown in FIG. 1, the heat exchange unit 1 for an absorption refrigerator includes a first container 5a, a first heat transfer tube group 6f, a first drip pan 7a, a second container 5b, a second heat transfer tube group 6s, and a second drip pan 7b. The first heat transfer tube group 6f includes a plurality of first heat transfer tubes 6a arranged in a plurality of stages and a plurality of rows inside the first container 5a. As shown in FIGS. 2A and 2B, the first drip pan 7a has a plurality of first drip portions 74a arranged along the longitudinal direction (X-axis direction) of the first heat transfer tube 6a. In addition, the first drip pan 7a drips the refrigerant liquid from the first drip portions 74a toward the first heat transfer tube group 6f. The second heat transfer tube group 6s includes a plurality of second heat transfer tubes 6b arranged in a plurality of stages and a plurality of rows inside the second container 5b. As shown in FIGS. 3A and 3B, the second drip pan 7b has a plurality of second drip portions 74b arranged along the longitudinal direction of the second heat transfer tube 6b. In addition, the second drip pan 7b drips the solution from the second drip portions 74b toward the second heat transfer tube group 6s. As shown in FIGS. 2B and 3B, the interval P2 between adjacent second drip portions 74b in the longitudinal direction (X-axis direction) of the second heat transfer tube 6b is smaller than the interval P1 between adjacent first drip portions 74a in the longitudinal direction of the first heat transfer tube 6a. 【0014】 As long as the interval P2 is smaller than the interval P1, the value of the ratio (P2 / P1) of the interval P2 to the interval P1 is not limited to a specific value. 【0015】 The first dripper 7a is located above the first heat transfer tube group 6f in the direction of gravity. The second dripper 7b is located above the second heat transfer tube group 6s in the direction of gravity. 【0016】 As shown in Figure 1, the heat exchange unit 1 includes, for example, an evaporator 2, an absorber 3, and a vapor channel 4. The heat exchange unit 1 is filled with a refrigerant and a solution. The evaporator 2 generates refrigerant vapor. The absorber 3 absorbs the refrigerant vapor generated in the evaporator 2. The vapor channel 4 is a channel that guides the refrigerant vapor generated in the evaporator 2 to the absorber 3. 【0017】 Evaporator 2 is a shell-and-tube heat exchanger. Typically, evaporator 2 is a spray-type shell-and-tube heat exchanger. For example, when a refrigerant with a negative saturated vapor pressure at room temperature (20°C ± 15°C), such as water, is used, the water level head of the refrigerant liquid tends to have a large influence on the evaporation pressure in a full-liquid type shell-and-tube heat exchanger. Therefore, when a refrigerant such as water is used, it is advantageous for evaporator 2 to be a spray-type shell-and-tube heat exchanger. 【0018】 The evaporator 2 includes a first container 5a, a first heat transfer tube group 6f, and a first dripper 7a. The first container 5a is, for example, a container having heat insulation and pressure resistance. A refrigerant liquid is stored in the first container 5a. In addition, the first container 5a isolates the refrigerant vapor inside the first container 5a from outside air such as atmospheric pressure air. In the first heat transfer tube group 6f, a plurality of first heat transfer tubes 6a are arranged parallel to each other and form multiple stages in the direction of gravity. The plurality of first heat transfer tubes 6a are arranged, for example, to form a square grid or a rectangular grid in a plane perpendicular to the longitudinal direction of the first heat transfer tubes 6a. The first heat transfer tubes 6a are made of copper or stainless steel. Grooves may be formed on the inner and outer surfaces of the first heat transfer tubes 6a. 【0019】 As shown in Figures 2A and 2B, the first dripper 7a includes a tray 71a, a holder 73a, and a slit component 77a. A storage space 70a is formed inside the tray 71a, and the refrigerant liquid 18 is stored in the storage space 70a. The tray 71a is elongated in a direction parallel to the longitudinal direction of the first heat transfer tube 6a. A plurality of distribution holes 72a are formed at the bottom of the tray 71a. The plurality of distribution holes 72a are arranged, for example, along a direction parallel to the longitudinal direction of the first heat transfer tube 6a. The holder 73a is joined to the bottom surface of the tray 71a. The holder 73a has a slope directly below the distribution holes 72a. In addition, the holder 73a has a side surface that is connected to its slope and extends toward the first heat transfer tube group 6f. The end of this side surface forms the first dripping section 74a. The first dripping section 74a is, for example, plate-shaped. The first drop portion 74a has a tapered first tip portion 75a that protrudes toward the first heat transfer tube group 6f. The first tip portion 75a has a ridge or apex formed thereon. The first tip portion 75a is, for example, plate-shaped. The slit component 77a is joined to the side surface of the holder 73a, and a groove 78a is formed between the slit component 77a and the side surface of the holder 73a. In addition, as shown in Figure 2B, the slit component 77a has an opening 76a near the first drop portion 74a. As a result, multiple openings 76a are arranged along the longitudinal direction of the first heat transfer tube 6a. 【0020】 Each of the tray 71a, holder 73a, and slit component 77a can be manufactured, for example, by press-forming a stainless steel plate. The first dropper 7a can be manufactured by welding the tray 71a, holder 73a, and slit component 77a together. 【0021】 Absorber 3 is a shell-and-tube heat exchanger. Absorbers are typically spray-type shell-and-tube evaporators. 【0022】 The absorber 3 includes a second container 5b, a second heat transfer tube group 6s, and a second dripper 7b. The second container 5b is, for example, a container having thermal insulation and pressure resistance. The solution is stored in the second container 5b. In addition, the second container 5b isolates the refrigerant vapor inside the second container 5b from the outside air, such as atmospheric pressure air. In the second heat transfer tube group 6s, the multiple second heat transfer tubes 6b are arranged parallel to each other and form multiple stages in the direction of gravity. The multiple second heat transfer tubes 6b are arranged, for example, to form a square grid or a rectangular grid in a plane perpendicular to the longitudinal direction of the second heat transfer tubes 6b. The second heat transfer tubes 6b are made of copper or stainless steel. Grooves may be formed on the inner and outer surfaces of the second heat transfer tubes 6b. 【0023】 As shown in Figures 3A and 3B, the second dropper 7b includes a tray 71b, a holder 73b, and a slit component 77b. A storage space 70b is formed inside the tray 71b, and the solution 26 is stored in the storage space 70b. The tray 71b extends, for example, in a direction parallel to the longitudinal direction of the second heat transfer tube 6b. A plurality of distribution holes 72b are formed at the bottom of the tray 71b. The plurality of distribution holes 72b are arranged, for example, along a direction parallel to the longitudinal direction of the second heat transfer tube 6b. The holder 73b is joined to the bottom surface of the tray 71b. The holder 73b has a slope directly below the distribution holes 72b. In addition, the holder 73b has a side surface that is connected to its slope and extends toward the second heat transfer tube group 6s. The end of this side surface forms the second dropper portion 74b. The second drop section 74b has a tapered second tip 75b that protrudes toward the second heat transfer tube group 6s. The second drop section 74b is, for example, plate-shaped. The second tip 75b has a ridge or apex formed thereon. The second tip 75b is, for example, plate-shaped. The slit component 77b is joined to the side surface of the holder 73b, and a groove 78b is formed between the slit component 77b and the side surface of the holder 73b. In addition, as shown in Figure 3B, the slit component 77b forms an opening 76b near the second drop section 74b. As a result, multiple openings 76b are arranged along the longitudinal direction of the second heat transfer tube 6b. 【0024】 The tray 71b, the holder 73b, and the slit component 77b can each be manufactured, for example, by press-forming a stainless steel plate. The second dropper 7b can be manufactured by welding the tray 71b, the holder 73b, and the slit component 77b together. 【0025】 The internal space of the first container 5a and the internal space of the second container 5b are connected by a vapor channel 4. An eliminator 12 is positioned in the vapor channel 4. The vapor channel 4 includes a bent section due to the eliminator 12. This prevents the refrigerant liquid inside the first container 5a from being dragged by the flow of refrigerant vapor and led into the inside of the second container 5b. 【0026】 The steam passage 4 is made of a metal material such as iron that has heat insulation and pressure resistance. The eliminator 12 is manufactured by welding together parts formed by press-forming stainless steel plates. 【0027】 As the refrigerant to be filled into the heat exchange unit 1, for example, a hydrofluorocarbon (HFC) type fluorocarbon refrigerant or a natural refrigerant such as water and ammonia can be used. In addition, as the solution to be filled into the heat exchange unit 1, for example, an aqueous lithium bromide solution and an ionic fluid can be used. 【0028】 As shown in Figure 1, the heat exchange unit 1 further includes, for example, a first pump 8, a circulation path 9, a first supply path 13, a second supply path 14, a discharge path 15, and a second pump 16. 【0029】 The first pump 8 is, for example, a velocity-type canned pump. The first pump 8 is located in the circulation path 9. One end of the circulation path 9 is connected to the first container 5a. When the first pump 8 is operated, the refrigerant liquid stored in the first container 5a is pumped through the circulation path 9. 【0030】 The first supply channel 13 is connected to the first container 5a. The refrigerant liquid is supplied to the first container 5a through the first supply channel 13. The refrigerant liquid supplied to the first container 5a is then guided to the first dripper 7a. The other end of the circulation channel 9 is connected to the first circulation channel 13, and the refrigerant liquid that has passed through the circulation channel 9 is supplied back to the first container 5a. 【0031】 The second supply channel 14 is connected to the second container 5b. solution The solution is supplied to the second container 5b via the second supply channel 14. The solution supplied to the second container 5b is then led to the second dropper 7b. 【0032】 The discharge channel 15 is connected to the second container 5b. The second pump 16 is located in the discharge channel 15. The second pump 16 is, for example, a velocity-type canned pump. The operation of the second pump 16 pumps the solution stored in the second container 5b to the outside of the absorber 3. 【0033】 Each of the circulation path 9, the first supply path 13, the second supply path 14, and the discharge path 15 is composed of a flow path member having, for example, thermal insulation and pressure resistance. 【0034】 [1-2. Operation] The operation and function of the heat exchange unit 1, configured as described above, will now be explained. When the heat exchange unit 1 is left unattended for a specific period, such as overnight, the temperature inside the heat exchange unit 1 is uniformly equal to approximately room temperature, and the pressure inside is also uniform. For example, if the room temperature is 25°C, the temperature inside the heat exchange unit 1 will also be uniformly 25°C. When the heat exchange unit 1 is in use, a heat transfer medium such as water, which has absorbed heat from outside the heat exchange unit 1, flows inside the first heat transfer tube 6a of the first heat transfer tube group 6f. This heat transfer medium flows into the first heat transfer tube 6a at, for example, 12°C. On the other hand, a heat transfer medium such as water, which has released heat to the outside of the heat exchange unit 1, flows inside the second heat transfer tube 6b of the second heat transfer tube group 6s. This heat transfer medium flows into the second heat transfer tube 6b at, for example, 32°C. 【0035】 When the heat exchange unit 1 is put into use, the refrigerant liquid is first supplied to the inside of the evaporator 2 through the first supply passage 13. The temperature of the supplied refrigerant liquid is, for example, about 35°C. As shown in Figures 2A and 2B, the refrigerant liquid 18 supplied to the evaporator 2 is stored in the storage space 70a of the tray 71a of the first dripper 7a. The refrigerant liquid 18 stored in the storage space 70a is distributed through the distribution holes 72a and the opening 76a and dripped from the first dripping section 74a toward the first heat transfer tube group 6f. After dripping, the refrigerant liquid 18 forms droplets 24 and flows down the outer surface of the first heat transfer tubes 6a and is stored in the lower part of the first container 5a. The refrigerant liquid 18 stored in the lower part of the first container 5a is pumped by the pump 8 and passed through the circulation passage 9 to be led back into the inside of the evaporator 2. In this way, the refrigerant liquid circulates between the inside and outside of the evaporator 2. When an absorption chiller equipped with a heat exchange unit 1 is operating at rated load, the flow rate of the refrigerant liquid 18 is, for example, about 30 liters / minute, and the amount of refrigerant liquid 18 dripped by the first dripper 7a is approximately equal to that flow rate. 【0036】 Next, solution 26 is supplied to absorber 3 through the second supply channel 14. The temperature, solute concentration, and viscosity of the supplied solution 26 are, for example, approximately 50°C, 63% by mass, and 0.00678 Pa·s, respectively. The viscosity of solution 26 can be about 4.8 times that of the refrigerant liquid supplied to evaporator 2. The solution 26 supplied to absorber 3 is stored in the storage space 70b in the tray 71b of the second dropper 7b. The solution 26 stored in the storage space 70b is distributed through the distribution holes 72b and opening 76b and dripped from the second dropper 74b toward the second heat transfer tube group 6s. After forming droplets 27, the dripped solution 26 flows down the outer surface of the second heat transfer tubes 6b and is stored in the lower part of the second container 5b. The solution 26 stored at the bottom of the second container 5b is pumped by the second pump 16 and discharged outside the heat exchange unit 1 through the discharge passage 15. When the absorption chiller equipped with the heat exchange unit 1 is operating at rated load, the flow rate of the solution 26 supplied from the second supply passage 14 and dispensed by the second dripper 7b is, for example, about 16 liters / minute. This flow rate is about half the flow rate of the refrigerant liquid 18 when the absorption chiller is operating at rated load. 【0037】 As solution 26 flows down the outer surface of the second heat transfer tube 6b, the refrigerant vapor filled inside the heat exchange unit 1 is absorbed by solution 26. This causes the temperature of solution 26 to rise. At the same time, solution 26 is cooled by the heat transfer medium flowing inside the second heat transfer tube 6b, so absorption by the supercooled solution 26 occurs continuously. As a result, the pressure inside the heat exchange unit decreases. Consequently, the refrigerant liquid 18 flowing down the outer surface of the first heat transfer tube 6a evaporates. The evaporation of refrigerant liquid 18 lowers its temperature. However, at the same time, the refrigerant liquid 18 is superheated by the heat transfer medium flowing inside the first heat transfer tube 6a, so evaporation of refrigerant liquid 18 occurs continuously. As a result, the pressure inside the heat exchange unit 1 is maintained within a predetermined range, and the internal state of the heat exchange unit 1 becomes steady state. In the steady state, the temperature and viscosity of refrigerant liquid 18 are approximately 7°C and 0.001427 Pa·s, respectively. On the other hand, the temperature, solute concentration, and viscosity of the solution 26 discharged from the absorber 3 are approximately 36°C, 57% by mass, and 0.004768 Pa·s, respectively. 【0038】 The operation of the first dropper 7a and the second dropper 7b will be explained using Figures 2A, 2B, 3A, 3B, and 4. 【0039】 As shown in Figures 2A and 2B, the refrigerant liquid 18 supplied to the first dripper 7a via the first supply passage 13 is stored in the storage space 70a. The refrigerant liquid 18 stored in the storage space 70a flows down while being distributed through a plurality of distribution holes 72a arranged in the longitudinal direction of the tray 71a. The refrigerant liquid 18 is guided onto the inclined surface of the holder 73a and flows down the surface of the holder 73a. Next, the refrigerant liquid 18 is guided into the groove 78a and stored again. After that, the refrigerant liquid 18 is again distributed and flows down through a plurality of openings 76a arranged in the longitudinal direction of the tray 71a. The refrigerant liquid 18 that has passed through the openings 76a is guided to the first dripping section 74a and is dripped from the first tip 75a of the first dripping section 74a. The refrigerant liquid 18, dropped by the first dropping section 74a, forms a droplet 24, then spreads out on the surface of the first heat transfer tube 6a, forming a liquid film 25 as it flows down. 【0040】 As shown in Figures 3A and 3B, the solution 26 supplied to the second dropper 7b via the second supply path 14 is stored in the storage space 70b. The solution 26 stored in the storage space 70b flows down while being distributed through a plurality of distribution holes 72b arranged longitudinally in the tray 71b. The solution 26 is guided onto the inclined surface of the holder 73b and flows down the surface of the holder 73b. Next, the solution 26 is guided into the groove 78b and stored again. After that, the solution 26 is again distributed and flows down through a plurality of openings 76b arranged longitudinally in the tray 71b. The solution 26 that has passed through the openings 76b is guided to the second dropper 74b and is dispensed from the second tip 75b of the second dropper 74b. The solution 26 dispensed by the second dropper 74b forms a droplet 27, and then spreads out on the surface of the second heat transfer tube 6b, forming a liquid film 28 as it flows down. 【0041】 Figure 4 schematically shows the process when the dropper 7p, which is a reference example, is used in place of the second dropper 7b to dispense solution 26 dropwise. The dropper 7p is configured in the same way as the first dropper 7a. 【0042】 [1-3. Effects, etc.] As described above, in this embodiment, the heat exchange unit 1 for absorption chillers comprises a first container 5a, a first heat transfer tube group 6f, a first dripper 7a, a second container 5b, a second heat transfer tube group 6s, and a second dripper 7b. The first heat transfer tube group 6f includes a plurality of first heat transfer tubes 6a arranged in multiple stages and multiple rows inside the first container 5a. The first dripper 7a has a plurality of first dripping parts 74a arranged along the longitudinal direction of the first heat transfer tubes 6a. In addition, the first dripper 7a drips refrigerant liquid from the first dripping parts 74a toward the first heat transfer tube group 6f. The second heat transfer tube group 6s includes a plurality of second heat transfer tubes 6b arranged in multiple stages and multiple rows inside the second container 5b. The second dripper 7b has a plurality of second dripping parts 74b arranged along the longitudinal direction of the second heat transfer tubes 6b. In addition, the second dropper 7b drops the solution from the second dropping section 74b toward the second heat transfer tube group 6s. The distance P2 between adjacent second dropping sections 74b in the longitudinal direction (X-axis direction) of the second heat transfer tube 6b is smaller than the distance P1 between adjacent first dropping sections 74a in the longitudinal direction of the first heat transfer tube 6a. 【0043】 As shown in Figures 2A and 2B, the viscosity of the refrigerant liquid 18 dripped from the first dripper 7a is low, and the flow rate of the refrigerant liquid 18 is also high, so even when the spacing P1 is relatively large, the wettability of the refrigerant liquid 18 on the first heat transfer tube 6a tends to be good. On the other hand, as shown in Figure 4, when the solution 26 is dripped using a dripper 7p having the same configuration as the first dripper 7a, the liquid film 28 formed on the surface of the second heat transfer tube 6b does not spread easily. This is because the viscosity of the solution 26 is high, about 4.8 times that of the refrigerant liquid 18. For this reason, when using the dripper 7p, the area of ​​the part of the surface of the second heat transfer tube 6b that is not wetted by the solution 26 becomes large, making it difficult to achieve good wettability of the solution 26 on the second heat transfer tube 6b. On the other hand, according to this embodiment, the spacing P2 is smaller than the spacing P1, so when the solution 26 is dripped by the second dripper 7b, the spacing between the liquid droplets 27 becomes smaller. Therefore, a uniform liquid film 28 is formed on the surface of the second heat transfer tube 6b, and the wettability of the solution 26 on the second heat transfer tube 6b tends to increase. 【0044】 According to this embodiment, a heat exchange method can be provided that includes the following items (I), (II), and (III). (I) In a first heat transfer tube group 6f which includes multiple first heat transfer tubes 6a arranged in multiple stages and multiple rows inside the first container 5a, a first heat transfer medium is supplied to the inside of the first heat transfer tubes 6a. In addition, a refrigerant liquid 18 is dripped from multiple positions arranged at first intervals P1 along the longitudinal direction of the first heat transfer tubes 6a toward the first heat transfer tube group 6f. (II) In the second heat transfer tube group 6s, which includes multiple second heat transfer tubes 6b arranged in multiple rows and columns inside the second container 5b, a second heat transfer medium is supplied to the inside of the second heat transfer tubes 6b. In addition, solution 26 is dripped from multiple positions arranged at second intervals P2 along the longitudinal direction of the second heat transfer tubes 6b toward the second heat transfer tube group 6s. (III) No. two The interval P2 is smaller than the first interval P1. 【0045】 (Embodiment 2) Embodiment 2 will be described below with reference to Figures 5A and 5B. The heat exchange unit according to Embodiment 2 is configured in the same way as the heat exchange unit 1 according to Embodiment 1, except for parts that will not be specifically described. The second dripper 7c according to Embodiment 2, shown in Figure 5A, is configured in the same way as the second dripper 7b, except for parts that will not be specifically described. Components of the second dripper 7c that are the same as or correspond to components of the second dripper 7b are denoted by the same reference numerals, and detailed descriptions are omitted. The description of Embodiment 1 also applies to Embodiment 2, to the extent that it does not contradict the technical description. 【0046】 [2-1. Structure] As shown in Figure 5A, in the second dropper 7c, the second dropper section 74 b It has a tapered second tip portion 75b that protrudes toward the second heat transfer tube group 6s. The second tip portion 75b is sharper than the first tip portion 75a. In other words, the width of the second projection at a specific distance from the tip of the second projection is smaller than the width of the first projection at a specific distance from the tip of the first projection. The second projection is obtained by projecting the second tip portion 75b onto a plane parallel to the longitudinal direction of the second heat transfer tube 6b, in a direction perpendicular to the longitudinal direction of the second heat transfer tube 6b. The first projection is obtained by projecting the first tip portion 75a onto a plane parallel to the longitudinal direction of the first heat transfer tube 6a, in a direction perpendicular to the longitudinal direction of the first heat transfer tube 6a. 【0047】 [2-2. Operation] The operation and function of the second dripper 7c, configured as described above, are explained below. When the absorption chiller equipped with the heat exchange unit 1 is operating at a load of about 50%, the amount of refrigerant vapor generated in the evaporator 2 and absorbed in the absorber 3 is about half. On the other hand, the circulation rate of the refrigerant liquid 18 dripped by the first dripper 7a toward the first heat transfer tube group 6f is constant regardless of the load of the absorption chiller, for example, about 30 liters / minute. This is because the refrigerant liquid 18 stored in the first container 5a is circulated through the circulation path 9 between the inside and outside of the evaporator 2 by the operation of the first pump 8. On the other hand, the flow rate of the solution 26 dripped by the second dripper 7c is determined according to the load of the absorption chiller. For this reason, when the absorption chiller is operating at a load of about 50%, the flow rate of the solution 26 dripped by the second dripper 7c is about 8 liters / minute, for example, which is about one-quarter of the flow rate of the refrigerant liquid 18. 【0048】 As shown in Figures 5A and 5B, the solution 26 supplied via the second supply channel 14 is stored in the storage space 70b. The solution 26 stored in the storage space 70b flows down while being distributed through a plurality of distribution holes 72b arranged in the longitudinal direction of the tray 71b. The solution 26 is guided onto the inclined surface of the holder 73b and flows down the surface of the holder 73b. Next, the solution 26 is guided into the groove 78b and stored again. After that, the solution 26 is again distributed and flows down through a plurality of openings 76b arranged in the longitudinal direction of the tray 71b. The solution 26 that has passed through the openings 76b is guided to the second dropping section 74b and is dispensed from the second tip 75b of the second dropping section 74b. At this time, the solution 26 flows down and is dispensed in a manner such as being inscribed within the second projection of the second tip 75b. Figures 5A and 5B show the state of the liquid film 28 of solution 26 at time t and time t+Δt, respectively. 【0049】 [2-3. Effects, etc.] As described above, in this embodiment, the second tip portion 75b is sharper than the first tip portion 75a. For example, when an absorption chiller equipped with the heat exchange unit of this embodiment is operated at a load of about 50%, the flow rate of the solution 26 dripped by the second dripper 7c is significantly reduced. This flow rate is, for example, one-quarter of the flow rate of the refrigerant liquid 18 dripped by the first dripper 7a, and may be half the flow rate of the solution 26 dripped by the second dripper 7c during rated operation of the absorption chiller. For example, consider the case where a dripper 7p according to a reference example is used instead of the second dripper 7c, as shown in Figures 6A and 6B. In this case, even if the liquid film 28 spreads over a wide area of ​​the surface of the second heat transfer tube 6b at time t, the area of ​​the surface of the second heat transfer tube 6b covered by the liquid film 28 becomes smaller at time t+Δt. As a result, the wetting state of the solution 26 on the surface of the second heat transfer tube 6b may become non-uniform over time. This is because the diameter of the droplet 27 of solution 26 is approximately the same as the diameter of the droplet 24 of refrigerant liquid 18, and is relatively large. 【0050】 On the other hand, in this embodiment, the second tip 75b is sharper than the first tip 75a, and the solution 26 flows down and drips along this sharper second tip 75b. As a result, the diameter of the solution droplets 27 becomes smaller, and when the flow rate of the solution 26 is the same in the second dropper 7c and the dropper 7p, the time interval between drops of the solution 26 in the second dropper 7c is shorter. In other words, the solution 26 is continuously dripped toward the second heat transfer tube group 6s in a temporally uniform manner. Therefore, even when the absorption chiller equipped with the heat exchange unit of this embodiment is operated at a load of about 50% with a low flow rate of the solution 26, temporal non-uniformity of the wetting state of the solution 26 on the surface of the second heat transfer tube 6b is suppressed. As a result, a good liquid film 28 can be formed on the surface of the second heat transfer tube 6b. 【0051】 (Embodiment 3) Embodiment 3 will be described below with reference to Figure 7. 【0052】 [3-1. Structure] As shown in Figure 7, the absorption chiller 100 includes a heat exchange unit 1. The absorption chiller 100 further includes, for example, a regenerator 80 and a condenser 90. The absorption chiller 100 is, for example, a single-effect cycle absorption chiller. 【0053】 [3-2. Operation] The operation and function of the absorption chiller 100, configured as described above, will now be explained. The solution 26 stored in the second container 5b is led to the regenerator 80 through the discharge passage 15. In the regenerator 80, the concentration of the solute in the solution 26 is increased by heating. The solution 26 with increased solute concentration is led to the absorber 3 through the second supply passage 14. Meanwhile, refrigerant vapor is generated by heating the solution 26 in the regenerator 80. This refrigerant vapor is led to the condenser 90, where it is cooled and condensed to produce refrigerant liquid. The refrigerant liquid is then, for example, depressurized and led to the evaporator 2 through the first supply passage 13. 【0054】 [3-3. Effects] As described above, in this embodiment, the absorption chiller 100 is equipped with a heat exchange unit 1. In the heat exchange unit 1, a liquid film 28 of the solution 26 is uniformly formed on the surface of the second heat transfer tube 6b, and the wettability of the solution 26 on the second heat transfer tube 6b tends to be high. For this reason, the coefficient of performance (COP) of the absorption chiller 100 tends to be high. 【0055】 (Other embodiments) As described above, Embodiments 1, 2, and 3 have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and can be applied to embodiments that have been modified, replaced, added, or omitted. Furthermore, it is possible to create new embodiments by combining the components described in Embodiments 1 and 2 above. Therefore, other embodiments will be illustrated below. 【0056】 In Embodiment 1, an example of a first dripper 7a was described, comprising a tray 71a, a holder 73a, and a slit component 77a. The first dripper 7a only needs to be capable of dripping refrigerant liquid from a plurality of first dripping parts 74a toward the first heat transfer tube group 6f. Therefore, the first dripper 7a is not limited to a configuration comprising a tray 71a, a holder 73a, and a slit component 77a. However, having such a configuration makes it easier to distribute the refrigerant liquid along the longitudinal direction of the first heat transfer tube 6a. 【0057】 In Embodiments 1 and 2, a configuration comprising a tray 71b, a holder 73b, and a slit component 77b was described as an example of the second droppers 7b and 7c. The second droppers 7b and 7c only need to be capable of dropping solution from a plurality of second dropping sections 74b toward the second heat transfer tube group 6s. Therefore, the second droppers 7b and 7c are not limited to a configuration comprising a tray 71b, a holder 73a, and a slit component 77a. However, having such a configuration for the second droppers 7b and 7c makes it easier to distribute the solution along the longitudinal direction of the second heat transfer tube 6b. 【0058】 In Embodiments 1 and 2, the first dropping section 74a is described as having a tapered first tip portion 75a that protrudes toward the first heat transfer tube group 6f, and the second dropping section 74b is described as having a tapered second tip portion 75b that protrudes toward the second heat transfer tube group 6s. The first dropping section 74a and the second dropping section 74b only need to be capable of dropping refrigerant liquid and solution, respectively. Therefore, the first dropping section 74a and the second dropping section 74b do not need to have a tapered first tip portion 75a and a tapered second tip portion 75b, respectively. However, if the first dropping section 74a has a tapered first tip portion 75a, the diameter of the refrigerant liquid droplets dropped from the first dropping section 74a can be easily adjusted to a desired size. In addition, if the second dropping section 74b has a tapered second tip portion 75b, the diameter of the solution droplets dropped from the second dropping section 74b can be easily adjusted to a desired size. 【0059】 In Embodiments 1 and 2, the first dropping section 74a and the second dropping section 74b were described as being plate-shaped. The first dropping section 74a and the second dropping section 74b only need to be capable of dropping the refrigerant liquid and the solution, respectively. Therefore, the first dropping section 74a and the second dropping section 74b are not limited to being plate-shaped. However, if the first dropping section 74a and the second dropping section 74b are plate-shaped, it is easier to manufacture them. The first dropping section 74a and the second dropping section 74b may also be cone-shaped or have a hollow structure. 【0060】 In Embodiment 3, a single-effect cycle absorption chiller was described as an example of the absorption chiller 100. The absorption chiller 100 only needs to be equipped with a heat exchange unit 1. Therefore, the absorption chiller 100 is not limited to a single-effect cycle absorption chiller. The absorption chiller 100 may be a double-effect cycle or triple-effect cycle absorption chiller. When a gas burner is used as the heat source for the regenerator 80, the absorption chiller 100 may be a gas chiller. 【0061】 Since the embodiments described above are for illustrative purposes of the technology described herein, various modifications, substitutions, additions, omissions, etc., can be made within the claims or their equivalents. [Industrial applicability] 【0062】 This disclosure is applicable to absorption chillers adapted for use in central air conditioning systems in buildings and chillers for process cooling, etc. [Explanation of Symbols] 【0063】 1. Heat exchange unit for absorption chiller 5a First container 5b Second container 6a First heat transfer tube 6b Second heat transfer tube 6f First heat transfer tube group 6s 2nd heat exchanger tube group 7a First dropper 7b, 7c Second dripping device 74a First drop lower part 74b Second drop lower part 75a First tip 75b Second tip 100 Absorption Refrigeration Unit

Claims

[Claim 1] The first container and The first heat transfer tube group includes a plurality of first heat transfer tubes arranged in multiple stages and multiple rows inside the first container, A first dripper having a plurality of first dripping parts arranged along the longitudinal direction of the first heat transfer tube, which drips refrigerant liquid from the first dripping parts toward the first heat transfer tube group, The second container, The second heat transfer tube group includes a plurality of second heat transfer tubes arranged in multiple stages and multiple rows inside the second container, A second dropper is provided, which has a plurality of second dropping points arranged along the longitudinal direction of the second heat transfer tube, and which drops a solution from the second dropping points toward the group of second heat transfer tubes, The first dropper has a first tray in which the refrigerant liquid to be supplied to the first dropper is stored, The second dropper has a second tray in which the solution to be supplied to the second dropper is stored, The distance between adjacent second drop-off points in the longitudinal direction of the second heat transfer tube is smaller than the distance between adjacent first drop-off points in the longitudinal direction of the first heat transfer tube. The first dripping part has a tapered first tip that protrudes toward the first heat transfer tube group, The second dripping portion has a tapered second tip that protrudes toward the second heat transfer tube group, The second tip is sharper than the first tip. Heat exchange unit for absorption chillers. [Claim 2] An absorption chiller comprising the heat exchange unit for an absorption chiller described in claim 1. [Claim 3] In a first heat transfer tube group including multiple first heat transfer tubes arranged in multiple rows and columns inside a first container, a first heat transfer medium is supplied inside the first heat transfer tubes, and a refrigerant liquid stored in a first tray is dripped toward the first heat transfer tube group from tapered first tips that protrude toward the first heat transfer tube group at multiple positions arranged at first intervals along the longitudinal direction of the first heat transfer tubes. In a second heat transfer tube group including multiple second heat transfer tubes arranged in multiple rows and columns inside a second container, the method includes supplying a second heat transfer medium inside the second heat transfer tubes, while dripping a solution stored in a second tray toward the second heat transfer tube group from tapered second tips that protrude toward the second heat transfer tube group at multiple positions arranged at second intervals along the longitudinal direction of the second heat transfer tubes, The second interval is smaller than the first interval. The second tip is sharper than the first tip. Heat exchange method.

Images