Heat exchanger and its design method, and heat transfer tube

Abstract

A heat exchanger according to the invention is a circular double-tube device having a first heat transfer tube through which a first fluid can flow from a first inlet to a first outlet, and a second heat transfer tube through which a second fluid can flow from a second inlet to a second outlet. The first heat transfer tube has a first region in which the tube diameter decreases from the first inlet toward the first outlet, a second region continuous with the first region in which the tube diameter increases, and a third region continuous with the second region in which the tube diameter increases more than in the second region. The tube diameter of the second heat transfer tube is constant from the second inlet to the second outlet and is the sum of the minimum value of the tube diameter of the first heat transfer tube and the maximum value of the flow path width of the second fluid.

Description

Heat exchanger and refrigeration cycle device

[0001] An embodiment of the present invention relates to a heat exchanger and a refrigeration cycle device.

[0002] A plate heat exchanger, an example of a conventional heat exchanger, is constructed by stacking multiple roughly plate-shaped plates in parallel at a predetermined interval, with each space between the plates serving as a flow path. High-temperature fluid and low-temperature fluid flow alternately through each flow path between every other plate, exchanging heat through each plate.

[0003] Japanese Patent Application Laid-Open No. 2007-10202

[0004] One object of one embodiment of the present invention is to reduce pressure loss in a heat exchanger with a simple configuration.

[0005] A heat exchanger according to one embodiment of the present invention has a first heat transfer tube through which a first fluid can flow from a first inlet to a first outlet, and a second heat transfer tube through which a second fluid can flow from a second inlet to a second outlet, wherein the heat transfer surface of the first heat transfer tube is in contact with the heat transfer surface of the second heat transfer tube, the cross-sectional area of ​​the first heat transfer tube decreases from the first inlet to the first outlet, and the cross-sectional area of ​​the second heat transfer tube is constant from the second inlet to the second outlet.

[0006] In the above configuration, the height of the first inlet of the first heat transfer tube is greater than the height of the first outlet.

[0007] The above-described configuration further includes a plurality of fins arranged parallel to the direction in which the first fluid can flow in the second heat transfer tube.

[0008] In the above configuration, the first fluid is a refrigerant, the second fluid is a heat dissipating fluid, and the first fluid and the second fluid flow in opposite directions.

[0009] The above-described configuration further includes a plurality of fins arranged parallel to the direction in which the first fluid can flow through the first heat transfer tube.

[0010] In the above configuration, the first fluid is air, the second fluid is a heat dissipating fluid, and the first fluid and the second fluid flow in opposite directions.

[0011] In the above configuration, the first fluid is air, the second fluid is a heating fluid, and the first fluid and the second fluid flow in the same direction.

[0012] In the above configuration, the first fluid is an evaporated gas of the refrigerant, and the second fluid is a condensed liquid.

[0013] In the above configuration, the first heat transfer tube has a flow path whose cross section perpendicular to the heat transfer surface with the second heat transfer tube is rectangular, and the second heat transfer tube has a flow path whose cross section perpendicular to the heat transfer surface is rectangular.

[0014] In the above configuration, the first heat transfer tube is the inner tube of the circular double pipe, and the second heat transfer tube is the outer tube of the circular double pipe.

[0015] In the above configuration, the first heat transfer tube is the inner tube of the rectangular double pipe, and the second heat transfer tube is the outer tube of the rectangular double pipe.

[0016] A heat exchanger according to one embodiment of the present invention comprises a first heat transfer tube through which a first fluid can flow from a first inlet to a first outlet, and a second heat transfer tube through which a second fluid can flow from a second inlet to a second outlet, wherein the heat transfer surface of the first heat transfer tube is in contact with the heat transfer surface of the second heat transfer tube, and the first heat transfer tube has a first region in which the cross-sectional area perpendicular to the flow direction of the first fluid decreases from the first inlet to the first outlet, a second region continuous with the first region and in which the cross-sectional area increases from the first inlet to the first outlet, and a third region continuous with the second region and in which the cross-sectional area increases from the first inlet to the first outlet, wherein the rate of increase in the cross-sectional area in the third region is greater than the rate of increase in the cross-sectional area in the second region, and the cross-sectional area of ​​the second heat transfer tube is constant from the second inlet to the second outlet.

[0017] The above-described configuration further includes a plurality of fins arranged parallel to the direction in which the second fluid can flow in the second heat transfer tube.

[0018] In the above configuration, the first heat transfer tube has a flow path whose cross section perpendicular to the contact surface with the second heat transfer tube is rectangular, and the second heat transfer tube has a flow path whose cross section perpendicular to the contact surface is rectangular.

[0019] In the above configuration, the first heat transfer tube is the inner tube of the circular double pipe, and the second heat transfer tube is the outer tube of the circular double pipe.

[0020] In the above configuration, the first heat transfer tube is the inner tube of the rectangular double pipe, and the second heat transfer tube is the outer tube of the rectangular double pipe.

[0021] A heat exchanger according to one embodiment of the present invention has a first heat transfer tube through which a first fluid can flow from a first inlet to a first outlet, and a second heat transfer tube through which a second fluid can flow from a second inlet to a second outlet, wherein the heat transfer surface of the first heat transfer tube is in contact with the heat transfer surface of the second heat transfer tube, and the area of ​​a cross section of the first heat transfer tube perpendicular to the direction in which the first fluid can flow is constant from the first inlet to the first outlet, and the area of ​​a cross section of the second heat transfer tube perpendicular to the direction in which the second fluid can flow is constant from the second inlet to the second outlet.

[0022] In the above configuration, the first fluid is a condensed liquid of a refrigerant, and the second fluid is a heating fluid.

[0023] In the above configuration, the first heat transfer tube has a flow path whose cross section perpendicular to the contact surface with the second heat transfer tube is rectangular, and the second heat transfer tube has a flow path whose cross section perpendicular to the contact surface is rectangular.

[0024] In the above configuration, the first heat transfer tube is the inner tube of the circular double tube, and the second heat transfer tube is the outer tube of the circular double tube.

[0025] In the above configuration, the first heat transfer tube is the inner tube of the rectangular double pipe, and the second heat transfer tube is the outer tube of the rectangular double pipe.

[0026] A refrigeration cycle device according to an embodiment of the present invention includes a refrigerant circuit including a heat exchanger according to an embodiment of the present invention, and the refrigerant circuit is configured to contain a refrigerant mixture of propane, CO ２ The tank is filled with a natural refrigerant such as isobutane, ammonia, or propane R290, or a fluorocarbon refrigerant such as R32 or R134-a.

[0027] According to one embodiment of the present invention, the pressure loss of the heat exchanger can be reduced with a simple configuration.

[0028] 1 is a schematic diagram of a heat exchanger according to an embodiment of the present invention. FIG. 1 is a perspective view showing details of a heat exchanger according to an embodiment of the present invention. FIG. 2 is a side view of a heat exchanger. FIG. 3 is a perspective view showing details of a heat exchanger according to an embodiment of the present invention. FIG. 4 is a perspective view of a heat exchanger according to an embodiment of the present invention. FIG. 5 is a perspective view of a heat exchanger according to an embodiment of the present invention. FIG. 6 is a perspective view of a heat exchanger according to an embodiment of the present invention. FIG. 7 is a perspective view of a heat exchanger according to an embodiment of the present invention. FIG. 8 is a perspective view of a heat exchanger according to an embodiment of the present invention. FIG. 9 is a perspective view of a heat exchanger according to an embodiment of the present invention. FIG. 10 is a perspective view of a heat exchanger according to an embodiment of the present invention. FIG. 11 is a perspective view of a heat exchanger according to an embodiment of the present invention. FIG. 12 is a perspective view of a heat exchanger according to an embodiment of the present invention. 27 is a diagram showing a refrigeration cycle apparatus according to an embodiment of the present invention. FIG. 28 is a table summarizing variables when designing according to a heat exchanger design method according to an embodiment of the present invention. FIG. 29 is a schematic diagram of a heat exchanger according to an embodiment of the present invention. FIG. 29 is a schematic diagram showing details of a heat exchanger according to an embodiment of the present invention. FIG. 29 is a cross-sectional view of the heat exchanger shown in FIG. 23. FIG. 29 is a schematic diagram showing details of a heat exchanger according to an embodiment of the present invention. FIG. 29 is a cross-sectional view of the heat exchanger shown in FIG. 27. FIG. 29 is a diagram showing a refrigeration cycle apparatus according to an embodiment of the present invention. FIG. 30 is a table summarizing evaporator configurations designed by an evaporator design method using various refrigerants.1 is a table summarizing the configuration of an evaporator designed by the evaporator design method using various refrigerants. 2 is a table summarizing the configuration of an evaporator designed by the condenser design method using various refrigerants. 3 is a table summarizing the configuration of an evaporator designed by the condenser design method using various refrigerants.

[0029] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. However, the present invention can be embodied in various forms without departing from the spirit of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below. Furthermore, in the drawings, the width, thickness, shape, etc. of each part may be shown schematically compared to the actual form to make the explanation clearer. However, these schematic diagrams are merely examples and do not limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements that are the same or similar to those described in the previous drawings may be given the same reference numerals, and redundant explanations may be omitted.

[0030] First Embodiment A heat exchanger 1 according to one embodiment of the present invention will be described with reference to FIGS. 1 to 2B. FIG. 1 is a schematic cross-sectional view showing the heat exchanger 1 according to one embodiment of the present invention. The heat exchanger 1 includes at least a heat exchange section 10. The heat exchanger 1 may further include a first inlet 22, a first outlet 24, a second inlet 26, a second outlet 28, a first distribution reservoir 32, a first collection reservoir 34, a second fluid distribution reservoir 36, and a second fluid collection reservoir 38. The heat exchanger 1 may further include a fan 12, turbines 14 and 18, a pump 16, and a generator 19.

[0031] The heat exchange unit 10 includes at least one heat exchanger 100. Although Fig. 1 illustrates an example in which one heat exchanger 100 is included, the number of heat exchangers 100 is not particularly limited. The configuration of the heat exchanger 100 will be described in detail later.

[0032] As shown in FIG. 1 , a first fluid 106 is drawn into the first inlet 22 by the fan 12. The first fluid 106 drawn in from the first inlet 22 flows into the first fluid distribution reservoir 32. Next, the first fluid 106 is distributed from the first fluid distribution reservoir 32 to the first heat transfer tubes 102 of the heat exchanger 100, and flows through the first heat transfer tubes 102 of the heat exchanger 100. Next, the first fluid 106 discharged from the first heat transfer tubes 102 of the heat exchanger 100 is collected in the first fluid collection reservoir 34. Thereafter, the first fluid 106 is discharged from the first outlet 24. The discharged first fluid 106 is sent to the generator 19 by the turbine 14.

[0033] As shown in FIG. 1 , the second fluid 108 is introduced into the second inlet 26 by the pump 16. The second fluid 108 introduced into the second inlet 26 flows into the second fluid distribution basin 36. The second fluid 108 is then distributed from the second fluid distribution basin 36 to the second heat transfer tubes 104 of the heat exchanger 100 and flows through the second heat transfer tubes 104 of the heat exchanger 100. The second fluid 108 is then discharged from the second heat transfer tubes 104 of the heat exchanger 100 and collected in the second fluid collection basin 38. The second fluid 108 is then discharged from the second outlet 28. The discharged second fluid 108 is sent by the turbine 18.

[0034] [Configuration of Heat Exchanger] Fig. 2A is a perspective view showing the details of the heat exchanger 100, and Fig. 2B is a side view of the heat exchanger 100. The heat exchanger 100 functions as a condenser. The heat exchanger 100 includes a first heat transfer tube 102 and a second heat transfer tube 104. A first fluid 106 can flow through the first heat transfer tube 102, and a second fluid 108 can flow through the second heat transfer tube 104. The first fluid 106 is a refrigerant. Examples of refrigerants include propane and CO ２ The second fluid 108 is a heat-dissipating fluid, which may be water, brine, or antifreeze.

[0035] The flow direction of the first fluid 106 and the flow direction of the second fluid 108 are opposite to each other. In Fig. 2A, the traveling directions of the first fluid 106 and the second fluid 108 are indicated by outline arrows. The first fluid flows into the first heat transfer tube 102 through the first inlet 22 and is discharged from the first outlet 24. The second fluid flows into the second heat transfer tube 104 through the second inlet 26 and is discharged from the second outlet 28.

[0036] In this embodiment, the first heat transfer tube 102 and the second heat transfer tube 104 are rectangular tubes. ２ and height H1 ｉｎ The first outlet 24 is expressed as a width b ２ and height H1 ｏｕｔ The length from the first inlet 22 to the first outlet 24 of the first heat transfer tube 102 is expressed as length l ２ The second inlet 26 of the second heat transfer tube 104 is defined by a width b ２ and height H2 ｉｎ The second outlet 28 is expressed as a width b ２ and height H2 ｏｕｔ The length from the second inlet to the second outlet of the second heat transfer tube 104 is expressed as length l ２ The height H and width b of the first heat transfer tube 102 and the second heat transfer tube 104 shown in FIGS. ２ represents the height and width of the inner diameter of the tube.

[0037] The heat transfer surface of the first heat transfer tube 102 is in contact with the heat transfer surface of the second heat transfer tube 104, and in this embodiment, the bottom surface of the first heat transfer tube 102 is in contact with the top surface of the second heat transfer tube 104. In this embodiment, the bottom surface of the first heat transfer tube 102 and the top surface of the second heat transfer tube 104 are horizontal (perpendicular to the direction in which gravity acts). A cross section perpendicular to the bottom surface of the first heat transfer tube 102 is rectangular, but the area of ​​the cross section decreases from the first inlet 22 toward the first outlet 24 of the flow path. Furthermore, a cross section perpendicular to the top surface of the second heat transfer tube 104 is rectangular, but the area of ​​the cross section is the same from the second inlet 26 of the flow path toward the second outlet 28 of the flow path.

[0038] In the heat exchanger 100, the height H1 of the first inlet 22 of the first heat transfer tube 102ｉｎ is the height H1 of the first outlet 24 ｏｕｔ It is preferable that it is greater than .

[0039] 2A and 2B show a case where the second heat transfer tube 104 has a plurality of fins 109 arranged parallel to the flow path. By providing a plurality of fins 109, it is possible to improve the heat exchange efficiency between the first fluid 106 and the second fluid 108. The second heat transfer tube 104 does not necessarily have to be provided with a plurality of fins 109.

[0040] <Condenser Design Method> A design method for applying the heat exchanger shown in Figures 2A and 2B to a condenser for extracting condensation volume change work will be described. In a condenser, as the velocity of the first fluid 106 increases during a phase change from gas to liquid, the cross-sectional area of ​​the first fluid 106 decreases. Therefore, the cross section perpendicular to the bottom surface of the first heat transfer tube 102, which is the flow path of the first fluid 106, decreases from the first inlet 22 to the first outlet 24. In the design method described below, the lengths (direction of fluid flow) of the first heat transfer tube 102 and the second heat transfer tube 104 are divided into 100 parts. Of the total length of the first heat transfer tube 102 divided into 100 parts, the inlet is 1D and the outlet is 100CY. Of the total length of the second heat transfer tube 104, the inlet is 100CY and the outlet is 100D.

[0041] In the following description, the first fluid 106 is entirely gas at the inlet of the first heat transfer tube 102, and therefore the quality fraction is 1. Furthermore, as the proportion of gas decreases from the second division of the first heat transfer tube 102 onwards, the velocity of the first fluid 106 increases, and at the outlet, the first fluid 106 becomes entirely liquid. Note that at each division point, the first fluid 106 becomes a two-phase flow.

[0042] <STEP 1> First, the refrigerant and the condensation temperature for the first heat transfer tube 102 are determined.

[0043] <STEP 2> Maximum condensation change work E ｃｍａｘ Calculate.

[0044] R: gas constant T: absolute condensation temperature v ｇ : condensed vapor specific volume vｌ : specific volume of condensate

[0045] <STEP 3> Calculate the maximum speed.

[0046]

[0047] <STEP 4> Condensation heat release Q ｃ Calculate Q ｃ = latent heat of condensation

[0048] <STEP 5> Dryness degree χ when the number of divisions is n and the division point is k ｋ Calculate.

[0049]

[0050] <STEP 6> Volume change work E at each division point k ｋ Calculate.

[0051]

[0052] <STEP 7> Speed ​​u for each division point k ｋ Calculate.

[0053]

[0054] <STEP 8> Density ρ for each division point k ｋ Calculate.

[0055]

[0056] <STEP 9> Flow path cross-sectional area A at each division point k ｋ Calculate.

[0057]

[0058] <STEP 10> Minimum flow path cross-sectional area A ｍｉｎ Select .

[0059] <STEP 11> Minimum flow path height h ｍｉｎ Select .

[0060] <STEP 12> Minimum flow path cross-sectional area A ｍｉｎ and minimum flow path height h ｍｉｎ The flow path width b is calculated from

[0061]

[0062] <STEP 13> Flow path height h for each division point k when flow path width b is fixed ｋ Calculate.

[0063]

[0064] <STEP 14> Calculate the condensation channel length. Make the channel height equal to the channel length. The energy loss can be calculated using the following formula:

[0065]

[0066] The total length L is calculated by making the representative length equal to the channel height.

[0067]

[0068] <STEP 15> Next, the heat dissipation fluid used for condensation for the second heat transfer tube 104 is considered. The amount of heat dissipation Qc is calculated. Qc = latent heat

[0069] <STEP 16> A heat dissipation fluid for heating the condensed refrigerant is selected. As the heat dissipation fluid, a liquid with a high heat transfer coefficient (water, brine, antifreeze) is used.

[0070] <STEP 17> Inlet temperature T of heat dissipation fluid ｗｉｎ and outlet temperature T ｗｏｕｔ (condensation temperature) is determined. The inlet temperature T of the heat dissipating fluid ｉｎ and outlet temperature T ｏｕｔ Temperature difference ΔT ｗ is calculated by the following formula: ｗ =T ｗｉｎ -T ｗｏｕｔ

[0071] <STEP 18> Required mass flow rate of heat dissipation fluid m ｗ Calculate.

[0072]

[0073] <STEP 19> The temperature drop of the heat dissipation fluid at each division point k is calculated.

[0074]

[0075] <STEP 20> Calculate the temperature of the heat dissipation fluid at each division point k. The temperature of the heat dissipation fluid at each division point k can be calculated using the following formula: Temperature of heat dissipation fluid at point k = inlet temperature of heat dissipation fluid - temperature drop to point k T ｗｋ =T ｗｉｎ -k × ΔT ｗｋ

[0076] <STEP 21> Velocity u of heat dissipation fluid ｗ Determine.

[0077] <STEP 22> Flow path cross-sectional area A of heat dissipation fluid ｗ Calculate.

[0078] ρ ｗ : Density of heat dissipating fluid

[0079] <STEP 23> Flow path height h of the heat dissipation fluid for each division point k ｗ Calculate.

[0080] A ｗ : Channel cross-sectional area b: Channel width (Condensation channel width: fixed)

[0081] <STEP 24> Reynolds number R of heat dissipation fluid ｅｗ Calculate.

[0082]

[0083] <STEP 25> Nusselt number N of heat dissipation fluid ｕｗ Calculate.

[0084] P ｒ : Prandtl number

[0085] <STEP 26> Heat transfer coefficient H of heat dissipation fluid ｗ Calculate.

[0086]

[0087] <STEP 27> The temperature difference between the evaporation temperature and the heat dissipation fluid temperature at each division point k is expressed as follows: ΔT = T ｋ +ΔT ｅ

[0088] <STEP 28> Determine the overall heat transfer coefficient. Since the heat transfer coefficient of evaporation is large, the overall heat transfer coefficient is considered to be the heat transfer coefficient of the heat dissipating fluid. K = H ｗ

[0089] <STEP 29> The average temperature difference for each division point k is calculated.

[0090]

[0091] <STEP 30> Flow path length l for each division point k ｋ Amount of heat exchanged = heat transfer coefficient x heat transfer area x temperature difference = heat transfer coefficient x flow path width x flow path length x temperature difference

[0092]

[0093] <STEP 31> Finally, the total length L is calculated.

[0094]

[0095] By the above method, the heat exchanger 100 according to one embodiment of the present invention can be designed.

[0096] In the heat exchanger 100 designed using the above method, the cross-sectional area of ​​the first outlet 24 of the first heat transfer tube 102 is approximately 0.4% of the cross-sectional area of ​​the first inlet 22. By tapering the shape of the first heat transfer tube 102 to match the volume change of the first fluid 106, pressure loss in the first heat transfer tube 102 can be reduced. Therefore, the velocity of the first fluid 106 increases as it travels through the first heat transfer tube 102. The velocity of the first fluid 106 at the first outlet 24 can be approximately 10 times the velocity of the first fluid 106 at the first inlet 22. This acceleration of the velocity of the first fluid 106 increases the volumetric work of gas condensation that can be extracted from the heat exchanger 100. The volumetric work of gas condensation at the first outlet 24 can be approximately 100 times the volumetric work of gas condensation at the first inlet 22.

[0097] Second Embodiment A heat exchanger 100A according to one embodiment of the present invention will be described with reference to Figures 3A and 3B. The heat exchanger 100A can be used as the heat exchange section 10 in the heat exchange device 1 shown in Figure 1 .

[0098] [Configuration of Heat Exchanger] FIG. 3A is a perspective view showing details of the heat exchanger 100A, and FIG. 3B is a side view of the heat exchanger 100A. The heat exchanger 100A functions as an evaporator. The heat exchanger 100A includes a first heat transfer tube 102 and a second heat transfer tube 104. A first fluid 106 can flow through the first heat transfer tube 102, and a second fluid 108 can flow through the second heat transfer tube 104. The first fluid 106 is a refrigerant. The refrigerant may be the same as the refrigerant described in the first embodiment. The second fluid 108 is a heating fluid. Water, brine, or antifreeze may be used as the heating fluid.

[0099] The flow direction of the first fluid 106 and the flow direction of the second fluid 108 are opposite to each other. In Fig. 3A, the traveling directions of the first fluid 106 and the second fluid 108 are indicated by outline arrows. The first fluid 106 flows into the first heat transfer tube 102 through the first inlet 22 and is discharged from the first outlet 24. The second fluid flows into the second heat transfer tube 104 through the second inlet 26 and is discharged from the second outlet 28.

[0100] The first heat transfer tube 102 and the second heat transfer tube 104 are rectangular tubes. The first inlet 22 of the first heat transfer tube 102 is formed with a width b ２ and height H1 ｉｎ The first outlet 24 is expressed as a width b ２ and height H1 ｏｕｔ The length from the first inlet 22 to the first outlet 24 of the first heat transfer tube 102 is expressed as length l ２ l ２ The second inlet 26 of the second heat transfer tube 104 is defined by a width b ２ and height H2 ｉｎ The second outlet 28 is expressed as a width b ２ and height H2 ｏｕｔ The length from the second inlet to the second outlet of the second heat transfer tube 104 is expressed as length l ２ The height H and width b of the first heat transfer tube 102 and the second heat transfer tube 104 shown in FIGS. ２ is the height H and width b of the inner diameter of the pipe ２ Represents.

[0101] The heat transfer surface of the first heat transfer tube 102 is in contact with the heat transfer surface of the second heat transfer tube 104, and in this embodiment, the bottom surface of the first heat transfer tube 102 is in contact with the top surface of the second heat transfer tube 104. In this embodiment, the bottom surface of the first heat transfer tube 102 and the top surface of the second heat transfer tube 104 are horizontal (perpendicular to the direction of gravity). Here, the first heat transfer tube 102 and the second heat transfer tube 104 are divided into 100 sections. Of the entire length of the first heat transfer tube 102 divided into 100 sections, the inlet is designated as point 1D and the outlet is designated as point 100CY. Of the entire length of the first heat transfer tube 102 divided into 100 sections, the 34th division is designated as point 34AK and the 50th division is designated as point 50BA. Of the entire length of the second heat transfer tube 104 divided into 100 sections, the outlet is designated as point 1D and the inlet is designated as point 100CY. Of the entire length of the second heat transfer tube 104, the 34th division is designated as point 34AK, and the 50th division is designated as point 50BA.

[0102] The first heat transfer tube 102 has a tapered shape and a divergent shape. In this embodiment, the first heat transfer tube 102 has a first region in which the cross-sectional area decreases from the first inlet 22 to the first outlet 24, a second region continuous with the first region and having a constant cross-sectional area from the first inlet 22 to the first outlet 24, and a third region continuous with the second region and having an increasing cross-sectional area from the first inlet 22 to the first outlet 24. The first region is the volume of the first heat transfer tube 102 from point 1D to point 34AK, the second region is the volume of the first heat transfer tube 102 from point 34AK to point 50BA, and the third region is the volume of the first heat transfer tube 102 from point 50BA to point 100CY. The cross-sectional area of ​​the first heat transfer tube 102 at point 34AK is the smallest cross-sectional area of ​​the first heat transfer tube 102. The cross-sectional area of ​​the first heat transfer tube 102 increases from point 34AK to point 50BA. Also, the cross-sectional area of ​​the first heat transfer tube 102 increases from point 50BA to point 100CY. The rate of increase in the cross-sectional area from point 50BA to point 100CY is greater than the rate of increase in the cross-sectional area from point 34AK to point 50BA.

[0103] The cross section of the second heat transfer tube 104 perpendicular to the upper surface thereof is rectangular, but the area of ​​the cross section is the same from the second inlet 26 of the flow path to the second outlet 28 of the flow path.

[0104] 3A and 3B show a case where the second heat transfer tube 104 has a plurality of fins 109 arranged parallel to the flow path. By providing a plurality of fins 109, it is possible to improve the heat exchange efficiency between the first fluid 106 and the second fluid 108. The second heat transfer tube 104 does not necessarily have to be provided with a plurality of fins 109.

[0105] 3A and 3B is applied to an evaporator for extracting evaporation volume change work. As described above, the first heat transfer tube 102 and the second heat transfer tube 104 are divided into 100 sections.

[0106] In the following description, the first fluid 106 is entirely liquid at the inlet of the first heat transfer tube 102, and therefore the quality fraction is 0. Furthermore, as evaporation progresses and the proportion of gas increases after the second division of the first heat transfer tube 102, the velocity of the first fluid 106 increases, and at the outlet, the first fluid 106 becomes entirely gas. Note that at each division point, the first fluid 106 becomes a two-phase flow.

[0107] <STEP 1> First, the refrigerant and evaporation temperature for the first heat transfer tube 102 are determined.

[0108] <STEP 2> The quality fraction χ at the inlet of the evaporator is calculated.

[0109]

[0110] <STEP 3> Next, the heat quantity q required for evaporation ｅ Calculate.

[0111]

[0112] <STEP 4> Next, the volume change work E per flow rate of 1 kg / s is calculated.

[0113] R: gas constant T: absolute temperature v ｇ : specific volume of evaporated vapor v ｅ : specific volume of evaporated liquid

[0114] <STEP 5> Next, the maximum volume change work E ｍａｘ Calculate.

[0115]

[0116] <STEP 6> Next, the state of the inlet and outlet of the evaporator is divided, and the state quantity for each division is calculated. If the number of divisions is n and the division point is k, the amount of heat absorption required up to point k is expressed by the following formula.

[0117]

[0118] The amount of heat required to reach point k is E ｋ is calculated using the following formula:

[0119]

[0120] Velocity u at point k ｋ is calculated using the following formula:

[0121]

[0122] Dryness at point k χ ｋ is calculated using the following formula:

[0123]

[0124] k-point density ρ ｋ is calculated using the following formula:

[0125] ρ ｇ : density of vapor ρ ｌ : density of the liquid

[0126] Flow path cross-sectional area A ｋ is determined by the continuity relation.

[0127]

[0128] <STEP 7> Minimum flow path cross-sectional area A at division point k ｋｍｉｎ Calculation of minimum flow path height h ｋｍｉｎ The flow path width b is calculated for b: flow path width h ｋｍｉｎ : Minimum flow path height

[0129] <STEP 8> Fix the flow path width b calculated in STEP 7, and calculate the flow path height h for each division point k. ｋ Ask for.

[0130]

[0131] <STEP 9> In order to reduce pressure loss due to velocity, the flow path length at each division point k is set to be equal to or less than the flow path height, and the cumulative flow path length is calculated.

[0132]

[0133] The energy loss ΔE due to speed can be calculated using the following formula:

[0134] d: characteristic length (circular pipe, pipe diameter, rectangular 2h) l: flow path length However, since the heat transfer coefficient of phase change is very large, the overall heat transfer coefficient of the heat exchanger depends on the heat transfer coefficient of the heating fluid described below.

[0135] <STEP 10> Next, a heating fluid for heating the evaporated refrigerant is selected for the second heat transfer tube 104. A liquid with a high heat transfer coefficient (water, brine, antifreeze) is used as the heating fluid.

[0136] <STEP 11> Inlet temperature T of heating fluid ｗｉｎ and outlet temperature T ｗｏｕｔ (evaporation temperature) is determined. The temperature difference ΔT between the inlet and outlet temperatures of the heating fluid ｗ can be calculated using the following formula: ΔTw = T ｗｉｎ -T ｗｏｕｔ

[0137] <STEP 12> Required mass flow rate of heating fluid m ｗ Calculate.

[0138]

[0139] <STEP 13> The temperature decrease of the heating fluid at each division point k is calculated.

[0140] <STEP 14> Calculate the temperature of the heating fluid at each division point k. Temperature of the heating fluid at point k = inlet temperature of the heating fluid - temperature drop to point k T ｗｋ =T ｗｉｎ -k × ΔT ｗｋ

[0141] <STEP 15> Velocity u of the heating fluid ｗ <STEP 16> Determine the cross-sectional area A of the flow path of the heating fluid. ｗ Calculate.

[0142] ρ ｗ : density of the heated fluid

[0143] <STEP 17> Flow path height h of the heating fluid at each division point k ｗ Calculate.

[0144] A ｗ : cross-sectional area of ​​flow path b: flow path width (evaporation flow path width fixed)

[0145] <STEP 18> The Reynolds number of the heated fluid is calculated.

[0146]

[0147] <STEP 19> Nusselt number N of heating fluid ｕｗ Calculate.

[0148] P ｒ : Prandtl number

[0149] <STEP 20> Heat transfer coefficient H of heating fluid ｗ Calculate.

[0150] <STEP 21> The temperature difference between the evaporation temperature and the heating fluid temperature at each division point k is expressed as follows: ΔT = T ｋ +ΔT ｅ

[0151] <STEP 22> Determine the overall heat transfer coefficient. Since the heat transfer coefficient of evaporation is large, the overall heat transfer coefficient is considered to be the heat transfer coefficient of the heating fluid. K = H ｗ

[0152] <STEP 23> The average temperature difference for each division point k is calculated.

[0153]

[0154] <STEP 24> Flow path length l for each division point k ｋ Amount of heat exchanged = heat transfer coefficient x heat transfer area x temperature difference = heat transfer coefficient x flow path width x flow path length x temperature difference

[0155] K: heat transfer rate ΔT=temperature difference q=exchanged heat amount

[0156] <STEP 25> Finally, the total length L is calculated.

[0157]

[0158] By the above method, the heat exchanger 100A according to one embodiment of the present invention can be designed.

[0159] In the heat exchanger 100A designed using the above method, the cross-sectional area of ​​the first heat transfer tube 102 at point 34AK is approximately 20% of the cross-sectional area of ​​the first inlet 22. The cross-sectional area of ​​the first heat transfer tube 102 at point 100CY is approximately 0.4% of the cross-sectional area of ​​the first inlet 22. The volume of the first fluid 106 in the first heat transfer tube 102 decreases, and then increases as the gas volume increases. Therefore, by shaping the first heat transfer tube 102 with a tapered shape and a divergent shape that correspond to the volume change of the first fluid 106, pressure loss in the first heat transfer tube 102 can be reduced. Therefore, the velocity of the first fluid 106 accelerates as it travels through the first heat transfer tube 102. The velocity of the first fluid 106 at the first outlet 24 can be approximately 10 times the velocity of the first fluid 106 at the first inlet 22. The increased velocity of the first fluid 106 increases the liquid evaporation volumetric work that can be extracted from the heat exchanger 100A. The liquid evaporation volumetric work at the first outlet 24 can be as much as 100 times the liquid evaporation volumetric work at the first inlet 22.

[0160] Table 1 shows the relationship between the work of volume change and latent heat for various refrigerants at 10° C., and Table 2 shows the relationship between the work of volume change and latent heat for various refrigerants at 45° C. Tables 1 and 2 show that the work of volume change is about 50% of the latent heat.

[0161]

[0162]

[0163] Third Embodiment A heat exchanger 100B according to one embodiment of the present invention will be described with reference to Figures 4A and 4B. The heat exchanger 100B can be used as the heat exchange section 10 in the heat exchange device 1 shown in Figure 1.

[0164] [Configuration of Heat Exchanger] FIG. 4A is a perspective view showing details of the heat exchanger 100B, and FIG. 4B is a side view of the heat exchanger 100B. The heat exchanger 100B functions as a heating fluid recovery device or a heat dissipation fluid recovery device. The heat exchanger 100B includes a first heat transfer tube 102 and a second heat transfer tube 104. A first fluid 106 can flow through the first heat transfer tube 102, and a second fluid 108 can flow through the second heat transfer tube 104. When the heat exchanger 100B is used as a heating fluid recovery device, the first fluid 106 is air, and the second fluid 108 is a heating fluid. Water, brine, or antifreeze is used as the heating fluid. When the heat exchanger 100B is used as a heat dissipation fluid recovery device, the first fluid 106 is air, and the second fluid 108 is a heat dissipation fluid. The heat dissipation fluid may be water, brine, or antifreeze.

[0165] The flow direction of the first fluid 106 and the flow direction of the second fluid 108 are opposite to each other. In Fig. 4A, the traveling directions of the first fluid 106 and the second fluid 108 are indicated by open arrows. The first fluid flows into the first heat transfer tube 102 through the first inlet 22 and is discharged from the first outlet 24. The second fluid flows into the second heat transfer tube 104 through the second inlet 26 and is discharged from the second outlet 28.

[0166] The first heat transfer tube 102 and the second heat transfer tube 104 are rectangular tubes. The first inlet 22 of the first heat transfer tube 102 is formed with a width b ２ and height H1 ｉｎ The first outlet 24 is expressed as a width b ２ and height H1 ｏｕｔ The length from the first inlet 22 to the first outlet 24 of the first heat transfer tube 102 is expressed as length l ２ l ２ The second inlet 26 of the second heat transfer tube 104 is defined by a width b ２ and height H2 ｉｎ The second outlet 28 is expressed as a width b ２ and height H2 ｏｕｔ The length from the second inlet to the second outlet of the second heat transfer tube 104 is expressed as length l ２ The height H and width b of the first heat transfer tube 102 and the second heat transfer tube 104 shown in FIGS. ２ is the height H and width b of the inner diameter of the pipe２ Represents.

[0167] The heat transfer surface of the first heat transfer tube 102 is in contact with the heat transfer surface of the second heat transfer tube 104, and in this embodiment, the bottom surface of the first heat transfer tube 102 is in contact with the top surface of the second heat transfer tube 104. In this embodiment, the bottom surface of the first heat transfer tube 102 and the top surface of the second heat transfer tube 104 are horizontal (perpendicular to the direction of gravity). A cross section perpendicular to the bottom surface of the first heat transfer tube 102 is rectangular, but the area of ​​the cross section decreases from the first inlet 22 to the first outlet 24 of the flow path. Furthermore, a cross section perpendicular to the top surface of the second heat transfer tube 104 is rectangular, but the area of ​​the cross section is the same from the second inlet 26 of the flow path to the second outlet 28 of the flow path.

[0168] 4A shows a case where the eleventh heat transfer tube 1022 has a plurality of fins 109 arranged parallel to the flow path. By providing a plurality of fins 109, it is possible to improve the heat exchange efficiency between the first fluid 106 and the second fluid 108. The eleventh heat transfer tube 1022 does not necessarily have to be provided with a plurality of fins 109.

[0169] In the heat exchanger 100B, the cross-sectional area of ​​the first outlet 24 of the first heat transfer tube 102 is smaller than the cross-sectional area of ​​the first inlet 22. By tapering the shape of the first heat transfer tube 102 to match the volume change of the first fluid 106, pressure loss in the first heat transfer tube 102 can be reduced. Therefore, the velocity of the first fluid 106 accelerates as it travels through the first heat transfer tube 102. The velocity of the first fluid 106 at the first outlet 24 can be approximately 10 times the velocity of the first fluid 106 at the first inlet 22. By accelerating the velocity of the first fluid 106, the amount of gas condensation volumetric work that can be extracted can be increased. The volume change work at the first outlet 24 can be approximately 100 times the volume change work at the first inlet 22.

[0170] Fourth Embodiment A heat exchanger 100C according to one embodiment of the present invention will be described with reference to Figures 5A and 5B. The heat exchanger 100C can be used as the heat exchange section 10 in the heat exchange device 1 shown in Figure 1 .

[0171] [Configuration of Heat Exchanger] Fig. 5A is a perspective view showing the details of the heat exchanger 100C, and Fig. 5B is a side view of the heat exchanger 100C. The heat exchanger 100 functions as a liquid-liquid exchanger. The heat exchanger 100C includes a first heat transfer tube 102 and a second heat transfer tube 104. A first fluid 106 can flow through the first heat transfer tube 102, and a second fluid 108 can flow through the second heat transfer tube 104. The first fluid 106 is a condensed liquid of a refrigerant. Examples of refrigerants include propane, CO ２ The second fluid 108 is, for example, a heated fluid that has undergone heat exchange in an evaporator. The second fluid 108 may be water, brine, or antifreeze.

[0172] The flow direction of the first fluid 106 and the flow direction of the second fluid 108 are opposite to each other. In Fig. 5A, the traveling directions of the first fluid 106 and the second fluid 108 are indicated by outline arrows. The first fluid flows into the first heat transfer tube 102 through the first inlet 22 and is discharged from the first outlet 24. The second fluid flows into the second heat transfer tube 104 through the second inlet 26 and is discharged from the second outlet 28.

[0173] The first heat transfer tube 102 and the second heat transfer tube 104 are rectangular tubes. The first inlet 22 of the first heat transfer tube 102 is formed with a width b ２ and height H1 ｉｎ The first outlet 24 is expressed as a width b ２ and height H1 ｏｕｔ The length from the first inlet 22 to the first outlet 24 of the first heat transfer tube 102 is expressed as length l ２ l ２ The second inlet 26 of the second heat transfer tube 104 is defined by a width b ２ and height H2 ｉｎ The second outlet 28 is expressed as a width b ２ and height H2 ｏｕｔ The length from the second inlet 26 to the second outlet 28 of the second heat transfer tube 104 is expressed as length l ２ The height H and width b of the first heat transfer tube 102 and the second heat transfer tube 104 shown in FIGS. ２is the height H and width b of the inner diameter of the pipe ２ Represents.

[0174] The heat transfer surface of the first heat transfer tube 102 is in contact with the heat transfer surface of the second heat transfer tube 104, and in this embodiment, the bottom surface of the first heat transfer tube 102 is in contact with the top surface of the second heat transfer tube 104. In this embodiment, the bottom surface of the first heat transfer tube 102 and the top surface of the second heat transfer tube 104 are horizontal (perpendicular to the direction of gravity). A cross section perpendicular to the bottom surface of the first heat transfer tube 102 is rectangular, but the area of ​​the cross section decreases from the first inlet 22 to the first outlet 24 of the flow path. Furthermore, a cross section perpendicular to the top surface of the second heat transfer tube 104 is rectangular, but the area of ​​the cross section is the same from the second inlet 26 of the flow path to the second outlet 28 of the flow path.

[0175] Fifth Embodiment A heat exchanger 100D according to one embodiment of the present invention will be described with reference to Figures 6A and 6B. The heat exchanger 100D can be used as the heat exchange section 10 in the heat exchange device 1 shown in Figure 1 .

[0176] [Configuration of Heat Exchanger] FIG. 6A is a perspective view showing details of the heat exchanger 100D, and FIG. 6B is a side view of the heat exchanger 100D. The heat exchanger 100D functions as a gas-liquid heat exchanger. The heat exchanger 100D includes a first heat transfer tube 102 and a second heat transfer tube 104. A first fluid 106 can flow through the first heat transfer tube 102, and a second fluid 108 can flow through the second heat transfer tube 104. The first fluid 106 is an evaporated gas of a refrigerant. The refrigerant may be the same as the refrigerant described in the first embodiment. The second fluid 108 is a condensate. Water, brine, or antifreeze may be used as the condensate.

[0177] The flow direction of the first fluid 106 and the flow direction of the second fluid 108 are opposite to each other. In Fig. 6A, the traveling directions of the first fluid 106 and the second fluid 108 are indicated by outline arrows. The first fluid flows into the first heat transfer tube 102 through the first inlet 22 and is discharged from the first outlet 24. The second fluid flows into the second heat transfer tube 104 through the second inlet 26 and is discharged from the second outlet 28.

[0178] The first heat transfer tube 102 and the second heat transfer tube 104 are rectangular tubes. The first inlet 22 of the first heat transfer tube 102 is formed with a width b ２ and height H1 ｉｎ The first outlet 24 is expressed as a width b ２ and height H1 ｏｕｔ The length from the first inlet 22 to the first outlet 24 of the first heat transfer tube 102 is represented by length l2l2. The second inlet 26 of the second heat transfer tube 104 is represented by width b ２ and height H2 ｉｎ The second outlet 28 is expressed as a width b ２ and height H2 ｏｕｔ The length from the second inlet 26 to the second outlet 28 of the second heat transfer tube 104 is expressed as length l ２ The height H and width b of the first heat transfer tube 102 and the second heat transfer tube 104 shown in FIGS. ２ is the height H and width b of the inner diameter of the pipe ２ Represents.

[0179] The bottom surface of the first heat transfer tube 102 is in contact with the top surface of the second heat transfer tube 104. In this embodiment, the bottom surface of the first heat transfer tube 102 and the top surface of the second heat transfer tube 104 are horizontal (perpendicular to the direction in which gravity acts). A cross section perpendicular to the bottom surface of the first heat transfer tube 102 is rectangular, but the area of ​​the cross section decreases from the first inlet 22 to the first outlet 24 of the flow path. Furthermore, a cross section perpendicular to the top surface of the second heat transfer tube 104 is rectangular, but the area of ​​the cross section remains the same from the second inlet 26 of the flow path to the second outlet 28 of the flow path.

[0180] 6A and 6B show a case where the second heat transfer tube 104 has a plurality of fins 109 arranged parallel to the flow path. By providing a plurality of fins 109, it is possible to improve the heat exchange efficiency between the first fluid 106 and the second fluid 108. The second heat transfer tube 104 does not necessarily have to be provided with a plurality of fins 109.

[0181] [Design Method of Gas-Liquid Heat Exchanger] A design method for applying the gas-liquid heat exchanger shown in Figures 6A and 6B to extract the isobaric volume change work of evaporated steam will be described. As described above, the first heat transfer tube 102 and the second heat transfer tube 104 are divided into 100 sections.

[0182] <STEP 1> The condensed liquid temperature and evaporated steam temperature T after gas-liquid heat exchange are calculated. These are expressed by the following equations based on the balance equation for the amount of heat exchanged.

[0183] Condensate temperature: T ｌ Specific heat: C ｌ Evaporation temperature: Tg Specific heat: Cg

[0184] <STEP 2> Maximum value E of the isobaric volume change work of evaporated steam ｍａｘ Calculate E = R × (T ２ -T １ )=R×(T-Tg)E ｍａｘ = R x (T - Tg) R is the gas constant and the evaporation vapor outlet velocity u ｇｏｕｔ is expressed by the following formula:

[0185]

[0186] <STEP 3> Condensate inlet velocity u ｌｉｎ , exit velocity u ｌｏｕｔ , the inlet velocity of the evaporation above u ｇｉｎ , exit velocity u ｇｏｕｔ Set.

[0187] <STEP 4> Divide the heat exchanger into n parts and calculate the condensate velocity u at each division point k. ｌｋ , temperature T ｌｋ , the evaporation rate u ｇｋ , temperature T ｇｋ Calculate the condensate u at each division point k. ｌｋ The velocity is expressed by the following formula:

[0188]

[0189] Condensate temperature T at each division point k ｌｋ is expressed by the following formula:

[0190]

[0191] Temperature T of evaporated steam at each division point k ｇｋ is expressed by the following formula:

[0192]

[0193] The evaporation rate u at each division point k ｇｋ is expressed by the following formula:

[0194]

[0195] Density of evaporated vapor at each division point k v ｇｋ The density of evaporated vapor at each division point k is calculated as v ｇｋ is expressed by the following equation, since Pv=RT.

[0196]

[0197] (P is pressure, R is gas constant)

[0198] <STEP 5> Calculate the flow path cross-sectional area for each division point k of the condensate and evaporated steam. ｌｋ Calculate.

[0199]

[0200] Flow path cross-sectional area A for each division point k of evaporated steam ｇｋ Calculate.

[0201]

[0202] <STEP 6> Minimum flow path cross-sectional area A of condensate ｌｍｉｎ Calculate the minimum flow path height h ｌｍｉｎ is set, and the fixed flow path width b at the time of the minimum flow path cross-sectional area is calculated. The fixed flow path width b is expressed by the following formula.

[0203]

[0204] Flow path height h for each condensate division point k ｌｋ Calculate the flow path height h for each division point k of the condensate. ｌｋ is expressed by the following formula:

[0205]

[0206] Flow path height h for each division point k of evaporated steam ｇｋis expressed by the following formula:

[0207]

[0208] <STEP 7> Calculate the Reynolds number of the condensed liquid and evaporated vapor. Reynolds number R Ｅ , Nusselt number N ｕ The heat transfer coefficient h can be determined in the same manner as in STEP 24 to STEP 26 shown in the first embodiment.

[0209]

[0210] <STEP 8> If there is a large difference between the heat transfer coefficient of each k-point of the condensate division and the heat transfer coefficient of the evaporated steam, an expansion fin is installed on the evaporated steam side, and the overall heat transfer coefficient after the installation of the heat transfer area expansion fin is calculated.

[0211] <STEP 9> Divide the heat exchange amount into n parts, and calculate the heat exchange amount Q / n for each division point k, the temperature difference ΔTk between the condensed liquid and the evaporated steam, the flow path width b of the heat exchanger, and the flow path length for each division point.

[0212] <STEP10> Heat exchange amount Q ｋ is the heat transfer coefficient K and the temperature difference ΔT ｋ and heat transfer area D ｋ It is expressed by the following formula using Q ｋ = K × ΔT ｋ ×D ｋ Dk = b x l ｋ Therefore, it is expressed by the following formula.

[0213] The total length L of the heat exchanger is expressed by the following formula.

[0214]

[0215] Sixth Embodiment In the previous embodiment, an example was described in which the bottom surface of the first heat transfer tube 102 and the second heat transfer tube 104 are in contact with the top surface of the second heat transfer tube 104 in the rectangular first and second heat transfer tubes 102 and 104. However, this embodiment is not limited to this. The first heat transfer tube 102 and the second heat transfer tube 104 may form a double pipe. In this case, the first heat transfer tube 102 may be the inner pipe, and the second heat transfer tube 104 may be the outer pipe. In a heat exchanger using a double pipe, the cross-sectional shape of the first heat transfer tube 102 and the second heat transfer tube 104 may be circular or rectangular. Hereinafter, a detailed description will be given using a condenser as an example.

[0216] FIG. 7 is a perspective view showing details of the heat exchanger 100E. The heat exchanger 100E functions as a condenser. The heat exchanger 100E includes a first heat transfer tube 102 and a second heat transfer tube 104. In FIG. 7, the first heat transfer tube 102 is the inner tube, and the second heat transfer tube 104 is the outer tube. The diameter (also referred to as height or tube diameter) of the second heat transfer tube 104 is larger than the diameter (also referred to as height or tube diameter) of the first heat transfer tube 102, and the first heat transfer tube 102 and the second heat transfer tube 104 form a double pipe. The cross-sectional shape of the first heat transfer tube 102 is circular, but its area decreases from the first inlet 22 toward the first outlet of the flow path. The cross-sectional shape of the second heat transfer tube 104 is also circular, but its area increases from the second inlet toward the second outlet of the flow path. Other configurations are similar to those of the heat exchanger 100, so the description of the heat exchanger 100 may be referred to.

[0217] FIG. 8 is a perspective view showing details of the heat exchanger 100F. The heat exchanger 100F functions as a condenser. In FIG. 8, the first heat transfer tubes 102-1 and 102-2 are inner tubes, and the second heat transfer tube 104 is an outer tube. While FIG. 8 illustrates an example in which two first heat transfer tubes 102-1 and 102-2 are used as the first heat transfer tubes, an embodiment of the present invention is not limited to this, and three or more first heat transfer tubes 102 may be used. The cross-sectional diameter of the second heat transfer tube 104 only needs to be larger than the diameters of the multiple first heat transfer tubes 102 and may be set appropriately depending on the diameters and number of the first heat transfer tubes 102. Furthermore, the area of ​​the second heat transfer tube 104 may be constant from the second inlet to the second outlet of the flow path.

[0218] FIG. 9 is a perspective view showing details of the heat exchanger 100G. The heat exchanger 100G functions as a condenser. The heat exchanger 100G includes a first heat transfer tube 102 and a second heat transfer tube 104. In FIG. 9, the first heat transfer tube 102 is the inner tube of a rectangle, and the second heat transfer tube 104 is the outer tube of a rectangle. The height and width of the second heat transfer tube 104 are greater than the height and width of the first heat transfer tube 102, and the first heat transfer tube 102 and the second heat transfer tube 104 form a rectangular double tube. In addition, the cross-sectional area of ​​the inlet of the first heat transfer tube 102 only needs to be greater than the cross-sectional area of ​​the outlet of the first heat transfer tube 102.

[0219] FIG. 10 is a perspective view showing details of the heat exchanger 100H. The heat exchanger 100H functions as a condenser. The heat exchanger 100H includes a first heat transfer tube 102 and a second heat transfer tube 104. In FIG. 10, the first heat transfer tube 102 is the inner tube, and the second heat transfer tube 104 is the outer tube. While FIG. 10 illustrates an example in which four first heat transfer tubes 102-1 to 102-4 are used as the first heat transfer tubes, the number of first heat transfer tubes 102 may be two or more. The cross-sectional diameter of the second heat transfer tube 104 only needs to be larger than the diameters of the multiple first heat transfer tubes 102 and may be set appropriately depending on the diameter and number of the first heat transfer tubes 102. Furthermore, the area of ​​the second heat transfer tube 104 may be constant from the second inlet to the second outlet of the flow path.

[0220] FIG. 11 is a perspective view showing details of the heat exchanger 100I. The heat exchanger 100I functions as an evaporator. The heat exchanger 100I includes a first heat transfer tube 102 and a second heat transfer tube 104. In FIG. 11, the first heat transfer tube 102 is the inner tube, and the second heat transfer tube 104 is the outer tube. The diameter (height) of the second heat transfer tube 104 is larger than the diameter (height) of the first heat transfer tube 102, and the first heat transfer tube 102 and the second heat transfer tube 104 form a double pipe. As shown in FIG. 11, the first heat transfer tube 102 and the second heat transfer tube 104 have a tapered shape and a flared shape. The cross section of the first heat transfer tube 102 is circular, but has a region where the area decreases and a region where the area increases from the first inlet 22 toward the first outlet of the flow path. 3A and 3B , the first heat transfer tube 102 may have a first region whose cross-sectional area decreases from the first inlet 22 to the first outlet 24, a second region continuing from the first region and whose cross-sectional area is constant from the first inlet 22 to the first outlet 24, and a third region continuing from the second region and whose cross-sectional area increases from the first inlet 22 to the first outlet 24. The second heat transfer tube 104 may also have, surrounding the first heat transfer tube 102, a first region whose cross-sectional area decreases from the second inlet 26 to the second outlet 28, a second region continuous with the first region whose cross-sectional area is constant from the first inlet 22 to the first outlet 24, and a third region continuous with the second region whose cross-sectional area increases from the first inlet 22 to the first outlet 24. The rest of the configuration is similar to that of the heat exchanger 100A, so the description of the heat exchanger 100A may be referred to.

[0221] FIG. 12 is a perspective view showing details of the heat exchanger 100J. The heat exchanger 100J functions as an evaporator. The heat exchanger 100J includes a first heat transfer tube 102 and a second heat transfer tube 104. In FIG. 12, the first heat transfer tubes 102-1 and 102-2 are inner tubes, and the second heat transfer tube 104 is an outer tube. Although FIG. 12 illustrates an example in which two first heat transfer tubes 102-1 and 102-2 are used as the first heat transfer tubes, one embodiment of the present invention is not limited to this, and three or more first heat transfer tubes 102 may be used. 3A and 3B, the first heat transfer tubes 102-1, 102-2 may have a first region in which the cross-sectional area decreases from the first inlet 22 to the first outlet 24, a second region continuous with the first region and having a constant cross-sectional area from the first inlet 22 to the first outlet 24, and a third region continuous with the second region and having an increasing cross-sectional area from the first inlet 22 to the first outlet 24. The cross-sectional diameter of the second heat transfer tube 104 may be larger than the diameters of the multiple first heat transfer tubes 102 and may be set appropriately depending on the diameters and number of the first heat transfer tubes 102. Furthermore, as shown in FIG. 12, the area of ​​the second heat transfer tube 104 may be constant from the second inlet to the second outlet of the flow path.

[0222] Although not shown in detail, a rectangular double-pipe heat exchanger can also be applied to the evaporator. In this case, the first heat transfer pipe 102 may be formed as an inner pipe using the shape of the first heat transfer pipe 102 shown in Figures 3A and 3B, and the second heat transfer pipe 104 may be formed as a pipe provided outside the first heat transfer pipe 102.

[0223] 4A to 6B (the heating fluid recovery device, the heat dissipation fluid recovery device, the liquid-liquid heat exchanger, and the gas-liquid heat exchanger) may also be configured with double pipes. When the heat exchangers 100B to 100D are configured with double pipes, the first heat transfer pipe 102 and the second heat transfer pipe 104 may be configured with circular double pipes or rectangular double pipes. Furthermore, the number of first heat transfer pipes 102 provided inside the second heat transfer pipe 104 may be one or two or more.

[0224] Seventh Embodiment A heat exchanger 1A according to one embodiment of the present invention will be described with reference to FIG. 13. FIG. 13 is a schematic cross-sectional view showing a heat exchanger 1A according to one embodiment of the present invention. The difference from the heat exchanger 1 shown in FIG. 1 is that the heat exchanger 1A has a plurality of heat exchangers in the heat exchange section 10. As the other configurations are similar to those of the heat exchanger 1 shown in FIG. 1, detailed description will be omitted. In the heat exchanger 1A, any of the heat exchangers 100, 100A to 100J can be used as the heat exchanger section 10. In this embodiment, a case where the heat exchanger section 10 has a plurality of heat exchangers 100A will be described.

[0225] 13 shows an example including six heat exchangers 100A-1 to 100A-6, but the number of heat exchangers 100A is not particularly limited. A first fluid distribution reservoir 32 is connected to the inlet of each of the first heat transfer tubes 102 of the heat exchangers 100A-1 to 100A-6. A first fluid collection reservoir 34 is connected to the outlet of each of the first heat transfer tubes 102. A second fluid separation reservoir 36 is connected to the inlet of each of the second heat transfer tubes 104. A second fluid separation reservoir 38 is connected to the outlet of each of the second heat transfer tubes 104.

[0226] 13 , the first fluid distribution reservoirs 32 are provided continuously in the z-axis direction, and the first fluid collection reservoirs 34 are also provided continuously in the z-axis direction. Although not shown in detail, each second heat transfer tube 104 penetrates the first fluid distribution reservoir 32 to be connected to the second fluid collection reservoir 38, and penetrates the first fluid collection reservoir 34 to be connected to the second fluid collection reservoir 36. Therefore, the first fluid 106 that flows in from the first inlet 22 flows into the first fluid distribution reservoir 32, and then simultaneously flows into the first heat transfer tubes 102 of the heat exchangers 100A-1 to 100A-6. After the first fluid 106 is collected in the first fluid collection reservoir 34, it is discharged from the first outlet 24. In addition, when the second fluid 108 that flows in from the second inlet 26 flows into the second fluid distribution reservoir 36, it simultaneously flows into the second heat transfer tubes 104 of the heat exchangers 100A-1 to 100A-6, and after the second fluid 108 is collected in the second fluid collection reservoir 38, it is discharged from the second outlet 28.

[0227] When multiple heat exchangers 100A-1 to 100A-6 are provided, it is preferable to provide a support member 41 between the second heat transfer tube 104 of the heat exchanger 100A-1 and the heat exchanger 100A-2. The shape of the support member 41 is not particularly limited, but it may be, for example, at least one plate-shaped member. The support member 41 is preferably made of a material with high thermal conductivity, such as aluminum or copper. In this way, by supporting the second heat transfer tube 104 of the heat exchanger 100A-1 and the first heat transfer tube 102 of the heat exchanger 100A-2, which are adjacent in the vertical direction, with the support member 41, the energy efficiency of the heat exchange unit 10 can be improved.

[0228] Eighth Embodiment In this embodiment, a refrigeration cycle apparatus 300 according to one embodiment of the present invention will be described.

[0229] Fig. 14 is a schematic diagram showing a refrigeration cycle apparatus 300 according to one embodiment of the present invention. As shown in Fig. 14, the refrigeration cycle apparatus 300 includes a refrigerant circuit in which a compressor 302, a condenser 304, a turbine 308, a condensing pressure adjustment valve 312, a liquid-liquid heat exchanger 314, a receiver 316, a low-pressure expansion valve 318, an evaporator 322, a turbine 326, and a gas-liquid separator 328 are connected by piping, and in which a refrigerant circulates. The refrigerant circuit includes a refrigerant circuit for circulating a refrigerant, such as propane, CO ２ The refrigerant is filled with a natural refrigerant such as isobutane, ammonia, or propane R290, or a fluorocarbon refrigerant such as R32 or R134-a. A heat-dissipating fluid recovering device 306 may be provided to assist the condenser 304, and a heating fluid recovering device 324 may be provided to assist the evaporator 322.

[0230] The refrigerant circuit includes at least one of the heat exchangers 100, 100A to 100J described in the previous embodiments. In this embodiment, the heat exchanger 100 is used as the condenser 304, the heat exchanger 100C is used as the liquid-liquid heat exchanger 314, the heat exchanger 100A is used as the evaporator 322, and the heat exchanger 100B is used as the heat dissipation fluid recoverer 306 and the heating fluid recoverer 324. Therefore, the reference numerals of the components, such as the first heat transfer tube 102 and the second heat transfer tube 104, described in the heat exchangers 100, 100A, 100B, and 100C will be used as appropriate. In the following description, the case will be described in which a refrigerant flows as the first fluid 106 into the first heat transfer tube 102 described in each of the heat exchangers 100, 100A, 100B, and 100C, and water flows as the second fluid 108 into the second heat transfer tube 104.

[0231] The compressor 302 compresses the refrigerant introduced from the suction port, thereby increasing the pressure and temperature of the refrigerant. The compressed refrigerant becomes a high-temperature, high-pressure gas.

[0232] In the condenser 304 (see the heat exchanger 100 shown in FIGS. 2A and 2B ), a high-temperature, high-pressure gaseous refrigerant flows into the first heat transfer tube 102 as the first fluid 106. Water flows into the second heat transfer tube 104 as the second fluid 108 (heat dissipation fluid). The high-temperature, high-pressure gas exchanges heat with the water in the condenser 304, thereby releasing heat and lowering its temperature. Here, the high-temperature, high-pressure gas turns into a liquid and is discharged from the condenser 304 as a liquid refrigerant.

[0233] The turbine 308 can be driven by a liquid refrigerant, which allows the energy contained in the refrigerant to be recovered as mechanical energy.

[0234] The condensation pressure regulating valve 312 maintains the liquid refrigerant that has passed through the turbine 308 at a predetermined pressure, thereby keeping the condensation temperature of the liquid refrigerant constant.

[0235] In the liquid-liquid heat exchanger 314 (heat exchanger 100C shown in FIGS. 5A and 5B ), liquid refrigerant flows into the first heat transfer tube 102 as the first fluid 106. Furthermore, water flows into the second heat transfer tube 104 as the second fluid 108 (heating fluid) discharged from an evaporator 322 (described later). The liquid-liquid heat exchanger 314 exchanges heat between the liquid refrigerant and the water, causing the liquid refrigerant to release heat to the water and lower its temperature. As a result, the liquid refrigerant is discharged from the liquid-liquid heat exchanger 314 as a liquid refrigerant with a lowered temperature. The liquid-liquid heat exchanger 314 exchanges heat between the refrigerant discharged from the condenser 304 and the heating fluid discharged from the evaporator 322.

[0236] The receiver 316 temporarily stores the liquid refrigerant whose temperature has been reduced after passing through the liquid-liquid heat exchanger 314, thereby absorbing pressure fluctuations within the refrigeration cycle apparatus 300 and stabilizing the overall pressure. The receiver 316 also reduces the pressure of the liquid refrigerant.

[0237] The low-pressure expansion valve 318 reduces the temperature of the low-pressure liquid refrigerant discharged from the receiver 316 by reducing the pressure of the liquid refrigerant. This promotes evaporation of the refrigerant in the evaporator 322, improving heat exchange efficiency. Furthermore, the low-pressure expansion valve 318 can adjust the refrigerant to an appropriate pressure and temperature even if the refrigerant is supercooled by the receiver 316.

[0238] In the evaporator 322 (heat exchanger 100A shown in FIGS. 3A and 3B ), a low-temperature, low-pressure liquid refrigerant flows into the first heat transfer tube 102 as the first fluid 106. Water flows into the second heat transfer tube 104 (heating fluid). The low-temperature, low-pressure liquid refrigerant exchanges heat with the water in the evaporator 322, heating the refrigerant and increasing its temperature. As a result, the liquid refrigerant turns into a gas, and is discharged from the evaporator 322 as a high-temperature, low-pressure gas refrigerant.

[0239] The turbine 326 can be driven by a gaseous refrigerant, which allows the energy of the refrigerant to be recovered as mechanical energy.

[0240] The gas-liquid separator 328 separates the high-temperature, low-pressure gas refrigerant into gas and liquid refrigerants. If liquid refrigerant enters the compressor 302, compression efficiency may decrease, potentially increasing energy consumption. By separating the liquid refrigerant from the gas refrigerant using the gas-liquid separator 328, it is possible to prevent the liquid refrigerant from flowing into the compressor 302. This improves the efficiency of the compressor 302. The liquid refrigerant after separation may be supplied to the receiver 316.

[0241] The gas refrigerant separated by the gas-liquid separator 328 is compressed again in the compressor 302. In this manner, the refrigeration cycle in which the refrigerant circulates is repeated by the refrigerant circuit in the refrigeration cycle apparatus 300.

[0242] Here, the heat dissipation fluid restorer 306 (heat exchanger 100B shown in FIGS. 4A and 4B ) is provided to assist the condenser 304. The second outlet of the second heat transfer tube 104 of the heat dissipation fluid restorer 306 is connected to the second inlet 26 of the second heat transfer tube 104 of the condenser 304 by piping, and the second outlet 28 of the second heat transfer tube 104 of the condenser 304 is connected to the second inlet 26 of the second heat transfer tube 104 of the heat dissipation fluid restorer 306 by piping. As a result, the second fluid 108 circulates through the second heat transfer tube 104 of the heat dissipation fluid restorer 306 and the second heat transfer tube 104 of the condenser 304. In the heat dissipation fluid restorer 306, heat exchange between the second fluid 108 (heat dissipation fluid) after heat exchange and air can be performed, thereby extracting the volume change work of the air.

[0243] The heating fluid restorer 324 (heat exchanger 100B shown in FIGS. 4A and 4B ) is provided to assist the evaporator 322. The second outlet of the second heat transfer tube 104 of the heat dissipation fluid restorer 306 is connected to the second inlet of the second heat transfer tube 104 of the evaporator 322 by piping, and the second outlet of the second heat transfer tube 104 of the evaporator 322 is connected to the second inlet of the second heat transfer tube 104 of the heat dissipation fluid restorer 306 by piping. This allows the second fluid 108 to circulate through the second heat transfer tube 104 of the heat dissipation fluid restorer 306 and the second heat transfer tube 104 of the evaporator 322. In the heating fluid restorer 324, heat exchange between the second fluid 108 (heating fluid) after heat exchange and air can be performed, thereby extracting the work of volume change of the air.

[0244] FIG. 15 is a schematic diagram showing a refrigeration cycle apparatus 300A according to one embodiment of the present invention. As shown in FIG. 15, the refrigeration cycle apparatus 300 includes a refrigerant circuit in which a refrigerant circulates, including a compressor 302, a condenser 304, a turbine 308, a condensing pressure control valve 312, a liquid-liquid heat exchanger 314, a receiver 316, a low-pressure expansion valve 318, an evaporator 322, a turbine 326, and a gas-liquid separator 328, all connected by piping. The refrigeration cycle apparatus 300A shown in FIG. 15 differs from the refrigeration cycle apparatus 300 shown in FIG. 14 in that the receiver 316 is provided between the condensing pressure control valve 312 and the liquid-liquid heat exchanger 314. This allows the receiver 316 to temporarily store refrigerant and prevent excessive supply to the liquid-liquid heat exchanger, even if the amount of refrigerant supplied from the condensing pressure control valve 312 temporarily increases.

[0245] At least one of the heat exchangers 100, 100A to 100C can be applied to the refrigeration cycle apparatus 300, 300A according to one embodiment of the present invention. The heat exchangers 100, 100A to 100C are heat exchangers with reduced pressure loss. Therefore, the velocity of the first fluid 106 flowing through the first heat transfer tube 102 in the heat exchangers 100, 100A to 100C can be increased. This increases the volume change work that can be extracted by the heat exchangers 100, 100A to 100C.

[0246] Ninth Embodiment In this embodiment, a refrigeration cycle apparatus 400 according to one embodiment of the present invention will be described.

[0247] 16 and 17 are schematic diagrams showing a refrigeration cycle apparatus 300 according to one embodiment of the present invention. As shown in Fig. 16 and 17, the refrigeration cycle apparatus 400 includes a refrigerant circuit in which a compressor 402, a condenser 404, a throttle expansion valve 418, an evaporator 422, and a gas-liquid heat exchanger 425 are connected by piping, and in which a refrigerant circulates. The refrigerant circuit includes a refrigerant such as propane, CO ２The refrigerant is filled with a natural refrigerant such as isobutane, ammonia, or propane R290, or a fluorocarbon refrigerant such as R32 or R134-a. A heat dissipation fluid recovering device 406 may be disposed after the condenser 304, and a heating fluid recovering device 424 may be disposed after the evaporator 322.

[0248] The refrigerant circuit includes at least one of the heat exchangers 100, 100A to 100D described in the previous embodiments. In this embodiment, the heat exchanger 100 is used as the condenser 404, the heat exchanger 100D is used as the gas-liquid heat exchanger 425, the heat exchanger 100A is used as the evaporator 422, and the heat exchanger 100B is used as the heat dissipation fluid restorer 406 and the heating fluid restorer 424. Therefore, the reference numerals of the components, such as the first heat transfer tube 102 and the second heat transfer tube 104, described in the heat exchangers 100, 100A, 100B, and 100D will be used as appropriate. In the following description, the case will be described in which a refrigerant flows as the first fluid 106 into the first heat transfer tube 102 described in each of the heat exchangers 100, 100A, 100B, and 100D, and water flows as the second fluid 108 into the second heat transfer tube 104.

[0249] As shown in FIG. 16, when the refrigeration cycle apparatus 2 is used in the first state, the changeover valves 218 and 224 are closed, and the changeover valves 222 and 226 are open.

[0250] The compressor 402 compresses the refrigerant introduced from the suction port, thereby increasing the pressure and temperature of the refrigerant. The compressed refrigerant becomes a high-temperature, high-pressure gas.

[0251] In the condenser 404 (see the heat exchanger 100 shown in FIGS. 2A and 2B ), a high-temperature, high-pressure gaseous refrigerant flows into the first heat transfer tube 102 as the first fluid 106. Water flows into the second heat transfer tube 104 as the second fluid 108 (heat dissipation fluid). The high-temperature, high-pressure gas exchanges heat with the water in the condenser 304, thereby releasing heat and lowering its temperature. Here, the high-temperature, high-pressure gas turns into a liquid and is discharged from the condenser 304 as a liquid refrigerant.

[0252] Since the switching valve 434 is closed and the switching valve 432 is open, the high-temperature, high-pressure liquid refrigerant is supplied to the throttle expansion valve 418. The high-temperature, high-pressure liquid refrigerant is expanded by the throttle expansion valve 418 to generate low-temperature, low-pressure liquid refrigerant, which is then supplied to the evaporator 422.

[0253] In the evaporator 422 (heat exchanger 100A shown in FIGS. 3A and 3B ), a low-temperature, low-pressure liquid refrigerant flows into the first heat transfer tube 102 as the first fluid 106. Water flows into the second heat transfer tube 104 (heating fluid). The low-temperature, low-pressure liquid refrigerant exchanges heat with the water in the evaporator 322, thereby heating the refrigerant and increasing its temperature. As a result, the liquid refrigerant turns into a gas, and is discharged from the evaporator 322 as a high-temperature, low-pressure gas refrigerant.

[0254] Since the switching valve 438 is closed and the switching valve 436 is open, the gaseous refrigerant discharged from the evaporator 422 is compressed again in the compressor 402. In this manner, the refrigeration cycle in which the refrigerant is circulated is repeated by the refrigerant circuit in the refrigeration cycle apparatus 400.

[0255] Here, the heat dissipation fluid restorer 406 (heat exchanger 100B shown in FIGS. 4A and 4B ) cools the air using the heat dissipation fluid discharged from the condenser 404. The second inlet of the second heat transfer tube 104 of the heat dissipation fluid restorer 406 is connected to the second outlet of the second heat transfer tube 104 of the condenser 404 by piping. In the heat dissipation fluid restorer 406, heat is exchanged between the second fluid 108 (heat dissipation fluid) after heat exchange and the air, thereby extracting the volume change work of the air.

[0256] The heating fluid restorer 424 (heat exchanger 100B shown in FIGS. 4A and 4B ) heats the air using the heating fluid discharged from the evaporator 322. The second inlet of the second heat transfer tube 104 of the heating fluid restorer 424 is connected by piping to the second outlet of the second heat transfer tube 104 of the evaporator 422. In the heating fluid restorer 424, heat exchange is performed between the second fluid 108 (heating fluid) after heat exchange and the air, thereby extracting the volume change work of the air.

[0257] As shown in FIG. 17, when the refrigeration cycle apparatus 2 is used in the second state, the changeover valves 218 and 224 are open, and the changeover valves 222 and 226 are closed.

[0258] A low-temperature, low-pressure gas refrigerant is introduced into the compressor 202 through a suction port. The compressor 202 compresses the low-temperature, low-pressure gas refrigerant to generate a high-temperature, high-pressure gas refrigerant, and supplies the high-temperature, high-pressure gas refrigerant to a condenser through a discharge port.

[0259] The condenser 204 condenses the high-temperature, high-pressure gas refrigerant supplied from the compressor 202 using a heat dissipating fluid to generate a high-temperature, high-pressure liquid refrigerant, which is then discharged from a discharge port.

[0260] Because switching valve 218 is open and switching valve 222 is closed, high-temperature, high-pressure liquid refrigerant is supplied to gas-liquid heat exchanger 208. Also, because switching valve 438 is open and switching valve 436 is closed, low-temperature, low-pressure gas refrigerant discharged from evaporator 422 is supplied to gas-liquid heat exchanger 208. As a result, gas-liquid heat exchanger 208 exchanges heat between the high-temperature, high-pressure liquid refrigerant and the low-temperature, low-pressure gas refrigerant. At this time, the liquid refrigerant is subcooled and the gas refrigerant is moderately heated. Subcooling the liquid refrigerant can suppress flash gas in the refrigerant liquid pipes. Furthermore, moderately heating the gas refrigerant can prevent wet gas refrigerant from being sucked into the compressor.

[0261] At least one of the heat exchangers 100, 100A to 100D can be applied to the refrigeration cycle apparatus 400 according to one embodiment of the present invention. The heat exchangers 100, 100A to 100D are heat exchangers with reduced pressure loss. Therefore, the velocity of the first fluid 106 flowing through the first heat transfer tube 102 in the heat exchangers 100, 100A to 100D can be increased. This increases the volume change work that can be extracted by the heat exchangers 100, 100A to 100D.

[0262] Tenth Embodiment A heat exchanger 1B according to one embodiment of the present invention will be described with reference to FIG. 22. FIG. 22 is a schematic cross-sectional view showing a heat exchanger 1B according to one embodiment of the present invention. The heat exchanger 1B includes heat exchangers 100K-1 and 100K-2. The heat exchanger 1B further includes a first inlet 22, a first outlet 24, a second inlet 26, a second outlet 28, a first fluid distribution reservoir 32, a first fluid collection reservoir 34, a second fluid distribution reservoir 36, and a second fluid collection reservoir 38. In this embodiment, the heat exchanger 1B includes two heat exchangers, but the heat exchanger 1B may include one heat exchanger or three or more heat exchangers. When the heat exchangers 100K-1 and 100K-2 are not particularly distinguished from each other, they will be referred to as heat exchanger 100K.

[0263] The heat exchanger 100K functions as an evaporator. The heat exchanger 100K includes a first heat transfer tube 102 and a second heat transfer tube 104. The heat exchanger 100K is configured as a circular double tube. The first heat transfer tube 102 is an inner tube, and the second heat transfer tube 104 is an outer tube. A first fluid 106 can flow through the first heat transfer tube 102, and a second fluid 108 can flow through the second heat transfer tube 104. Here, the first fluid 106 is a refrigerant, and the second fluid 108 is a heating fluid.

[0264] In each of the heat exchangers 100K-1 and 100K-2, the second heat transfer tube 104 is connected to the second fluid distribution reservoir 36 and the second fluid collection reservoir 38. In each of the heat exchangers 100K-1 and 100K-2, the first heat transfer tube 102 passes through the second fluid collection reservoir 38 to be connected to the first fluid distribution reservoir 32, and passes through the second fluid distribution reservoir 36 to be connected to the first fluid collection reservoir 34.

[0265] 22 , the first fluid 106 is sucked into the first inlet 22. The first fluid 106 sucked from the first inlet 22 flows into the first fluid distribution reservoir 32. Next, the first fluid 106 is distributed from the first fluid distribution reservoir 32 to the first heat transfer tubes 102 of the heat exchangers 100K-1 and 100K-2, and flows through the first heat transfer tubes 102. Next, the first fluid 106 discharged from the first heat transfer tubes 102 of the heat exchangers 100K-1 and 100K-2 is collected in the first fluid collection reservoir 34. Thereafter, the first fluid 106 is discharged from the first outlet 24.

[0266] The second fluid 108 flows in through the second inlet 26. The second fluid 108 that has flowed in through the second inlet 26 flows into the second fluid distribution reservoir 36. The second fluid 108 is then distributed from the second fluid distribution reservoir 36 to the second heat transfer tubes 104 of each of the heat exchangers 100K-1 and 100K-2, and flows through the second heat transfer tubes 104. The second fluid 108 that has been discharged from the second heat transfer tubes 104 of each of the heat exchangers 100K-1 and 100K-2 is then collected in the second fluid collection reservoir 38. The second fluid 108 is then discharged from the second outlet 28.

[0267] 23 is a schematic diagram showing details of a heat exchanger 100K according to an embodiment of the present invention. In the heat exchanger 100K, the first fluid 106 flows through the first heat transfer tube 102 from the inlet 121 to the outlet 122 in the direction of the arrow, while the first fluid 106 evaporates due to the heating of the second fluid 108 flowing from the inlet 141 to the outlet 142 in the direction of the arrow, generating work of volume change, decreasing the density, and increasing the velocity.

[0268] As shown in Figure 23, the first heat transfer tube 102 has a first region 102a in which the tube diameter decreases from the inlet 121 to the outlet 122, a second region 102b in which the tube diameter increases continuously from the first region 102a, and a third region 102c in which the tube diameter increases continuously from the second region 102b. The rate of increase in the tube diameter in the third region 102c is greater than the rate of increase in the tube diameter in the second region 102b. Thus, the outer shape of the first heat transfer tube 102 tapers to form a diverging tube. The length of the second region 102b from the inlet 121 to the outlet 122 is longer than the length of the first region 102a, and the length of the first region 102a from the inlet 121 to the outlet 122 is longer than the length of the third region 102c.

[0269] 22, the pipe diameter of the first heat transfer tube 102 penetrating the second fluid collecting reservoir 38 is the same as the pipe diameter of the first heat transfer tube 102 at the inlet 121 in the heat exchanger 100K. Furthermore, the pipe diameter of the first heat transfer tube 102 penetrating the second fluid distribution reservoir 36 is the same as the pipe diameter of the first heat transfer tube 102 at the outlet 122 in the heat exchanger 100K. The first fluid distribution reservoir 32 and the second fluid collecting reservoir 38 may be adjacent to each other, or may be in contact with each other. Similarly, the first fluid collecting reservoir 34 and the second fluid distribution reservoir 36 may be adjacent to each other, or may be in contact with each other. The first heat transfer tube 102 penetrates the second fluid collecting reservoir and the second fluid distribution reservoir.

[0270] The diameter of the second heat transfer tube 104 is constant from the inlet 141 to the outlet 142. The diameter of the second heat transfer tube 104 is the sum of the minimum value of the tube diameter (or outer diameter) of the first heat transfer tube 102 and the maximum value of the flow path width of the second fluid 108. Here, the minimum value of the tube diameter of the first heat transfer tube 102 refers to the minimum value of the tube diameter (or outer diameter) of the first region 102a. The maximum value of the flow path width of the second fluid 108 is a value obtained by dividing the flow path cross-sectional area of ​​the second fluid 108 by π and then dividing the result by the minimum value of the tube diameter of the first heat transfer tube 102. With the first heat transfer tube 102 and the second heat transfer tube 104 configured as described above, a relationship is established in which the overall heat transfer coefficient of the second fluid 108 is the reciprocal of the overall heat transfer coefficient of the first fluid 106. The relationship between the heat transfer coefficient of the first fluid 106 and the heat transfer coefficient of the second fluid 108 will be described in detail later.

[0271] In the heat exchanger 100K, the first fluid 106 flowing in through the inlet 121 of the first heat transfer tube 102 undergoes evaporation due to heating by the second fluid 108, generating volume change work, decreasing its density, and increasing its velocity. The first heat transfer tube 102 has a first region 102a, a second region 102b, and a third region 102c adapted to the state change and volume change work of the first fluid 106 as the first fluid 106 evaporates. The first heat transfer tube 102 is designed so that the second region 102b, where evaporation progresses most, is the longest, followed by the first region 102a, which corresponds to the rapid rise of evaporation, and the third region 102c, where the change is almost complete, in that order.

[0272] <Design Method of Evaporator> A design method for applying the heat exchanger 100K shown in Figures 22 and 23 to an evaporator for extracting the volume change work of the first fluid 106 (evaporating refrigerant) will be described with reference to Figure 24. In the design method for the heat exchanger 100K described below, the required heat exchange amount between the first fluid 106 and the second fluid 108 is divided into 100 parts.

[0273] In the following description, the first fluid 106 becomes an evaporating two-phase flow at the inlet 121 and outlet 122 of the first heat transfer tube 102 (also referred to as the inner tube).

[0274] <STEP 1> First, for the first heat transfer tube 102, the evaporation temperature te is set as the dryness fraction χ at the inlet 121. ｉｎ Calculate.

[0275] hcl: condensed liquid enthalpy (kJ) heg: vapor enthalpy (kJ) hel: vapor enthalpy (kJ)

[0276] <STEP 2> Calculate E, the standard volume change work of evaporation (standard mass 1 kg).

[0277] χ ｉｎ： Inlet dryness R: Gas constant (kJ / kg) T: Absolute evaporation temperature (K) vl: Specific volume of liquid (m ３ / kg) vg: specific volume of steam (m ３ / kg)

[0278] <SETP3> The required heat exchange amount between the first fluid 106 and the second fluid 108 is divided into n parts, and the dryness fraction χ at each division point k is calculated. ｋ Here, n=100. ｋ =χ ｉｎ + (1-χ ｉｎ ) × k / n χ ｉｎ = Dryness fraction at the inlet of the heat exchanger n = 100 k = 1 to 100

[0279] <SETP4> Cumulative volume change work E of the evaporating two-phase flow at each division point k ｋ Calculate E ｋ = E × k / n E: Work of volume change

[0280] <STEP 5> Speed ​​u for each division point k ｋ Calculate.

[0281]

[0282] <STEP 6> Density ρ of the evaporating two-phase flow at each division point k ｋ Calculate ρ ｋ =χ ｋ +ρ ｇ + (1-χ ｉｎ ) × ρ ｌ ρ ｇ : steam density (kg / m ３ ) ρ ｌ : density of liquid (kg / m ３ )

[0283] <STEP 7> Standard flow path cross-sectional area A for each division point k ｋ Here, the mass flow rate is assumed to be 1 kg / s. ｋ = 1 / (u ｋ ×ρ ｋ )

[0284] <STEP 8> Diameter D of the evaporating two-phase flow passage in the first heat transfer tube 102 at each division point k ｋ Calculate.

[0285]

[0286] <STEP 9> Flow path cross-sectional area A when the mass of evaporated refrigerant is mass m ｍｋ Calculate the following. ｍｋ =A ｋ× mm m: Mass of evaporated refrigerant (kg)

[0287] <STEP 10> Diameter D of each division point k of the first heat transfer tube 102 ｍｋ Calculate.

[0288]

[0289] <STEP 11> The pipe diameter φ of the heat transfer surface of the first heat transfer pipe 102 ｋ Calculate φ ｋ =D ｍｋ +2t t: thickness of the metal wall of the first heat transfer tube 102

[0290] <STEP 12> Next, the dryness fraction χ at the inlet of the second heat transfer tube 104 (also referred to as the outer tube) ｉｎ From the latent heat Q, the amount of heat exchanged q per standard mass (1 kg) of evaporation is calculated. q = (1 - χ ｉｎ ) x Q

[0291] <STEP 13> Set the heating fluid and determine the mass m ｗ Calculate.

[0292] t ｗｉｎ : Inlet temperature of heating fluid t ｏｕｔ :Outlet temperature of heating fluid C ｗ : specific heat of the heated fluid

[0293] <STEP 14> Flow path cross-sectional area A per unit mass of heating fluid ｗ Calculate.

[0294] u ｗ : velocity of heated fluid (m ２ / s) ρ ｗ : density of heating fluid (kg / m ３ )

[0295] <STEP 15> Mass m of heating fluid ｗ The cross-sectional area A of the flow path corresponding to ｗｍ Calculate the following. ｗｍ =A ｗ ×m ｗ

[0296] <STEP 16> Maximum flow path width of heating fluid maxb ｗｍ Calculate.

[0297] minφ ｋ : Pipe diameter φ of the first heat transfer pipe 102 at division point k ｋ The minimum value of

[0298] <STEP 17> Circumferential length C of the heat transfer surface at each division point k of the first heat transfer tube 102 ｉｒｋ Calculate the following. ｉｒｋ = (D ｍｋ + 2t) × π

[0299] <STEP 18> The tube diameter φ of the second heat transfer tube 104 ｏｕｔ Calculate φ ｏｕｔ = minφ ｋ +maxb ｗｍｋ minφ ｋ : Tube diameter φ at division point k of the first heat transfer tube 102 ｋ The minimum value of maxb ｗｍｋ : Flow path width b at division point k of heating fluid ｗｍｋ Maximum value of

[0300] <STEP 19> Flow path width b of the heating fluid at each division point k ｗｍｋ Calculate b ｗｍｋ =(φ ｏｕｔ -φ ｋ ) / 2 φ ｋ : Pipe diameter of the flow path at each division point k of the first heat transfer pipe 102

[0301] <STEP 20> The characteristic length d of the heating fluid at each division point k ｗｍｋ Calculate d ｗｍｋ = 2 × b ｗｍｋ

[0302] <STEP 21> Reynolds number Re of the heating fluid at each division point k ｗｍｋ Calculate Re ｗｍｋ = (d ｗｍｋ ×u ｗ ) / V ｗ d ｗｍｋ : Representative length u of the heated fluid at each division point k ｗ :Speed ​​V ｗ : Dynamic viscosity coefficient of heated fluid (m ２ / s)

[0303] <STEP 22> Nusselt number Nu for each division point k of the heating fluid ｗｍｋ Calculate Nuｗｍｋ = 0.023 × Re ０．８ ×Pr ０．４ Pr: Prandtl number

[0304] <STEP 23> Heat transfer coefficient H of the heating fluid at each division point k ｗｍｋ (W / (m ２ Calculate H ｗｍｋ = (Nu ｗｍｋ ×λ ｗ ) / d ｗｍｋ λ ｗ : Thermal conductivity of the heating fluid (W / (m K))

[0305] <STEP 24> Heat transfer coefficient H of metal wall ｍ Calculate H ｍ = λ ｍ / t λ ｍ : Thermal conductivity of metal wall (W / (m·K)) t: Thickness of metal wall

[0306] <STEP 25> The overall heat transfer coefficient K (W / (m ２ However, since the heat transfer coefficient of the evaporating two-phase flow is very large, it is not taken into account in the calculation of the overall heat transfer coefficient. Here, the reciprocal of the overall heat transfer coefficient K, 1 / K, is calculated.

[0307]

[0308] <STEP 26> Reciprocal 1 / K.

[0309] <STEP 27> Temperature t of the heating fluid at each division point k ｗ Calculate t ｗ = t ｗｉｎ -(t ｗｉｎ -t ｗｏｕｔ ) × (k / n) t ｗｉｎ : Inlet temperature of heating fluid t ｗｏｕｔ : Outlet temperature of heating fluid

[0310] <STP28> Temperature t of the heating fluid at each division point k ｗ and evaporation temperature t ｅ Temperature difference Δt ｋ Calculate Δt ｋ = t ｗ -t ｅ

[0311] <STEP 29> The flow path length l of the heat exchanger for each division point k ｋ Calculate the value of l. ｋ = (q / n) / (K ｋ ×Δt ｋ ×C ｉｒｋ ) K ｋ : Heat transfer coefficient at division point k

[0312] <STEP 30> Calculate the total length L of the heat exchanger. The total length L is calculated by multiplying the flow path length l for each division point k by the ｋ is the sum of

[0313]

[0314] <STEP 31> Flow path cross-sectional area A for each division point k ｋ Based on this, the maximum value maxA ｋ and the minimum value minA ｋ Ratio y to Ａ Calculate y Ａ = max A ｋ / minA ｋ

[0315] <STEP 32> Diameter D of the flow path at division point k ｋ Based on this, the maximum value maxD ｋ and the minimum value minD ｋ The ratio y ｂ Calculate y ｂ = max D ｋ / minD ｋ

[0316] 30 shows the configuration of an evaporator designed by the evaporator design method using various refrigerants. The following conditions were applied in the evaporator design method. <Condition 1> Mass flow rate: 1 kg / s Heating fluid: water Inlet temperature: 14°C Outlet temperature: 5°C

[0317] 31 is a table summarizing the configuration of evaporators designed using various refrigerants according to the evaporator design method. The following conditions were applied in the evaporator design method. <Condition 2> Mass flow rate: 0.05 kg / s Heating fluid: water Inlet temperature: 14°C Outlet temperature: 5°C

[0318] As shown in FIGS. 30 and 31, ２The volume change during evaporation is smaller than that of other refrigerants, and the flow rate fluctuation is also gentle. Therefore, when the heat exchanger 100K is used as an evaporator, ２ By using water or brine as the heating fluid, it is possible to achieve a structure in which the change in the cross-sectional area of ​​the first heat transfer tube 102 is suppressed. This provides design advantages such as reduced pressure loss, suppressed energy loss, and simplified structure. ２ has excellent heat transfer performance, improves the heat exchange efficiency in the first region 102d and the second region 102e, and contributes to the miniaturization of the heat exchange device.

[0319] FIG. 25 is a schematic diagram showing the detailed configuration of a heat exchanger 100M according to one embodiment of the present invention. Here, the case where the heat exchanger 100M is used as an evaporator will be described. In the heat exchanger 100M, as in the heat exchanger 100L, the pipe diameter of the second heat transfer tube 104 is determined by the sum of the minimum pipe diameter (or outer diameter) of the first heat transfer tube 102 and the maximum flow path width of the second fluid 108. However, in the heat exchanger 100M, when the ratio between the minimum and maximum pipe diameters (or outer diameters) of the first heat transfer tube 102 is small, i.e., the change in pipe diameter is small, the difference between the minimum and maximum values ​​can be treated as an error range. Therefore, there is no problem in designing the pipe diameter of the second heat transfer tube 104 even if it is approximately defined as the sum of the representative pipe diameter (e.g., average or reference pipe diameter) of the first heat transfer tube 102 and the flow path width of the second fluid 108.

[0320] CO as a refrigerant ２ When using water or brine (second fluid 108) as the heating fluid (first fluid 106), the ratio of the minimum and maximum diameters of the first heat transfer tubes 102 can be reduced to approximately two times. ２ Since the volume change during evaporation is relatively small, a long flow path can be secured while avoiding a sudden change in the pipe diameter of the first heat transfer pipe 102. Therefore, the first heat transfer pipe 102 can have a long overall length while having a structure in which the pipe diameter changes gradually, and the heat exchanger 100M can be configured as a linear double pipe structure.

[0321] Eleventh Embodiment A heat exchanger 1C according to one embodiment of the present invention will be described with reference to FIG. 26 . FIG. 26 is a schematic cross-sectional view showing a heat exchanger 1C according to one embodiment of the present invention. The heat exchanger 1C includes heat exchangers 100L-1 and 100L-2. The heat exchanger 1C further includes a first inlet 42, a first outlet 44, a second inlet 46, a second outlet 48, a first fluid distribution reservoir 52, a first fluid collection reservoir 54, a second fluid distribution reservoir 56, and a second fluid collection reservoir 58. In this embodiment, the heat exchanger 1C includes two heat exchangers, but the heat exchanger 1C may include one heat exchanger or three or more heat exchangers. When the heat exchangers 100L-1 and 100L-2 are not particularly distinguished from each other, they will be referred to as heat exchanger 100L.

[0322] The heat exchanger 100L functions as a condenser. The heat exchanger 100L includes a first heat transfer tube 102 and a second heat transfer tube 104. The heat exchanger 100L is configured as a circular double tube. The first heat transfer tube 102 is an inner tube, and the second heat transfer tube 104 is an outer tube. A first fluid 106 can flow through the first heat transfer tube 102, and a second fluid 108 can flow through the second heat transfer tube 104. The first fluid 106 is a refrigerant. The second fluid 108 is a heat dissipation fluid.

[0323] In each of the heat exchangers 100L-1 and 100L-2, the second heat transfer tube 104 is connected to the second fluid distribution reservoir 56 and the second fluid collection reservoir 58. In each of the heat exchangers 100L-1 and 100L-2, the first heat transfer tube 102 passes through the second fluid collection reservoir 58 and is connected to the first fluid distribution reservoir 52, and passes through the second fluid distribution reservoir 56 and is connected to the first fluid collection reservoir 54.

[0324] 26 , the first fluid 106 is sucked into the first inlet 42. The first fluid 106 sucked from the first inlet 42 flows into the first fluid distribution reservoir 52. Next, the first fluid 106 is distributed from the first fluid distribution reservoir 52 to the first heat transfer tubes 102 of the heat exchangers 100L-1 and 100L-2, and flows through the first heat transfer tubes 102. Next, the first fluid 106 discharged from the first heat transfer tubes 102 of the heat exchangers 100L-1 and 100L-2 is collected in the first fluid collection reservoir 54. Thereafter, the first fluid 106 is discharged from the first outlet 44.

[0325] The second fluid 108 flows in through the second inlet 46. The second fluid 108 that has flowed in through the second inlet 46 flows into the second fluid distribution reservoir 56. The second fluid 108 is then distributed from the second fluid distribution reservoir 56 to the second heat transfer tubes 104 of the heat exchangers 100L-1 and 100L-2, and flows through the second heat transfer tubes 104 of the heat exchanger 100L. The second fluid 108 that has been discharged from the second heat transfer tubes 104 of the heat exchangers 100L-1 and 100L-2 is then collected in the second fluid collection reservoir 58. The second fluid 108 is then discharged from the second outlet 48.

[0326] 27 is a schematic diagram showing details of a heat exchanger 100L according to an embodiment of the present invention. In the heat exchanger 100L, the first fluid 106 flows through the first heat transfer tube 102 from the inlet 121 to the outlet 122 in the direction of the arrow, while condensation proceeds due to heat dissipation from the second fluid 108 flowing from the inlet 141 to the outlet 142 in the direction of the arrow, generating volume change work, increasing velocity, and increasing density.

[0327] 27 , the diameter of the first heat transfer tube 102 has a first region 102d and a second region 102e, where the diameter decreases from the inlet 121 to the outlet 122. The rate of decrease in the diameter in the first region 102d is greater than the rate of decrease in the diameter in the second region 102e. Therefore, the first heat transfer tube 102 is a tapered tube. The length of the first region 102d from the inlet 121 to the outlet 122 is shorter than the length of the second region 102e.

[0328] 26, the pipe diameter of the first heat transfer tube 102 penetrating the second fluid collecting reservoir 58 is the same as the pipe diameter of the first heat transfer tube 102 at the inlet 121 of the heat exchanger 100L. Furthermore, the pipe diameter of the first heat transfer tube 102 penetrating the second fluid distribution reservoir 56 is the same as the pipe diameter of the first heat transfer tube 102 at the outlet 122 of the heat exchanger 100L. The first fluid distribution reservoir 52 and the second fluid collecting reservoir 58 may be adjacent to each other, or may be in contact with each other. Similarly, the first fluid collecting reservoir 54 and the second fluid distribution reservoir 56 may be adjacent to each other, or may be in contact with each other. The first heat transfer tube 102 penetrates the second fluid collecting reservoir and the second fluid distribution reservoir.

[0329] The diameter of the second heat transfer tube 104 is constant from the inlet 141 to the outlet 142. The diameter of the second heat transfer tube 104 is the sum of the minimum diameter of the first heat transfer tube 102 and the maximum flow path width of the second fluid 108. Here, the minimum diameter of the first heat transfer tube 102 refers to the minimum diameter of the first region 102a. The maximum flow path width of the second fluid 108 is the value obtained by dividing the flow path cross-sectional area of ​​the second fluid 108 by π and then dividing the result by the minimum diameter of the first heat transfer tube 102. The above-described configuration of the first heat transfer tube 102 and the second heat transfer tube 104 establishes a relationship in which the overall heat transfer coefficient of the second fluid 108 is the reciprocal of the overall heat transfer coefficient of the first fluid 106. The relationship between the overall heat transfer coefficient of the first fluid 106 and the overall heat transfer coefficient of the second fluid 108 will be described in detail later.

[0330] In the first heat transfer tube 102, the first fluid 106 flowing in through the inlet 121 gradually condenses due to the heat dissipation from the second fluid 108. The density of the first fluid 106 increases as it changes from a gas to a liquid, and its velocity increases due to the work of volume change. To accommodate this state change of the first fluid 106, the first heat transfer tube 102 has a first region 102d and a second region 102e. In the first region 102d, condensation progresses near the inlet 121, so the volume of the fluid decreases rapidly, and the diameter of the first heat transfer tube 102 correspondingly decreases. Furthermore, in the second region 102e, condensation progresses and the volume change becomes gradual, so the rate of decrease in the diameter of the first heat transfer tube 102 is smaller than in the first region 102d. Furthermore, in the initial stage of condensation (first region 102d), a sudden change occurs in a short time, whereas in the later stage of condensation (second region 102e), the condensation progresses slowly, so that the second region 102e has a longer structure than the first region 102d.

[0331] <Condenser Design Method> A design method for the heat exchanger 100L shown in Figures 26 and 27 when applied to a condenser for extracting volume change work of a first fluid 106 (condensed refrigerant) will be described with reference to Figure 28. In a condenser, when the phase of the first fluid 106 changes from a gas to a liquid, the cross-sectional area of ​​the first fluid 106 decreases as the velocity of the first fluid 106 increases. Therefore, the flow path cross-sectional area of ​​the first fluid 106 decreases from the inlet 121 toward the outlet 122. In the design method for the heat exchanger L described below, the amount of heat required to be exchanged between the first fluid 106 and the second fluid 108 is divided by 100.

[0332] In the following description, the first fluid 106 is entirely gas at the inlet of the first heat transfer tube 102, and therefore the quality fraction is 1. Furthermore, as the proportion of gas decreases from the second division of the first heat transfer tube 102 onwards, the velocity of the first fluid 106 increases, and at the outlet, the first fluid 106 becomes entirely liquid. Note that at each division point, the first fluid 106 becomes a two-phase flow.

[0333] <STEP 1> The condensation temperature is t ｃ , latent heat of condensation Q ｃ , density of the condensate ρ ｌ , specific volume of condensate v ｌ , density of condensed vapor ρｇ , specific volume of condensed vapor v ｇ , gas constant R, dryness fraction χ at the inlet 121 of the first heat transfer tube 102 ｉｎ = 1, and the standard mass is m.

[0334] <STEP 2> Divide the heat exchange amount of the heat exchanger into n parts. k / n n=100 k=1 to 100

[0335] <STEP 3> Dryness fraction χ for each division point k ｋ Calculate χ ｋ =χ ｉｎ - (χ ｉｎ -k / n)

[0336] <STEP 4> Maximum volume change work E ｍａｘ Calculate.

[0337]

[0338] <STEP 5> Volume change work E at each division point k ｋ Calculate E ｋ = E ｍａｘ ×χ ｋ

[0339] <STEP 6> Speed ​​u for each division point k ｋ Calculate u ｋ = (2 × E ｋ ) ０．５

[0340] <STEP 7> Density ρ for each division point k ｋ Calculate ρ ｋ =χ ｋ ×ρ ｇ + (1-χ ｋ ) × ρ ｌ ρ ｇ : Vapor density ρ ｌ :Liquid density

[0341] <STEP 8> Flow path cross-sectional area A for each division point k ｋ Calculate the following. ｋ = 1 / (u ｋ ×ρ ｋ )

[0342] <STEP 9> Flow path diameter D for each division point k ｋ Calculate.

[0343]

[0344] <STEP 10> The pipe diameter φ of the heat transfer surface of the first heat transfer pipe 102 ｋ Calculate φ ｋ =D ｋ +2t t: thickness of metal wall

[0345] <STEP 11> Heat transfer circumference C of heat exchanger ｉｒｋ Calculate the following. ｉｒｋ =φ ｋ ×π

[0346] <STEP 12> Inlet temperature t of heat dissipation fluid ｗｉｎ and the outlet temperature t ｗｏｕｔ Temperature difference Δt ｗｃ Calculate Δt ｗｃ = t ｗｏｕｔ -t ｗｉｎ

[0347] <STEP 13> Temperature t of the heat dissipation fluid at each division point k ｗｋ Calculate t ｗｋ = t ｗｉｎ +Δt ｗｃ ×k / n

[0348] <STEP 14> Condensation temperature t for each division point k ｃ and the temperature of the heat dissipating fluid t ｗｋ Temperature difference Δt ｋ Calculate Δt ｋ = t ｃ -t ｗｋ

[0349] <STEP 15> The amount of heat exchange Q required for condensation is the latent heat Qc. Q = Q ｃ

[0350] <STEP 16> Mass flow rate of heat dissipation fluid m ｗ Calculate.

[0351] C ｗ : specific heat of the heat dissipating fluid

[0352] <STEP 17> Flow path cross-sectional area A of heating fluid ｗ Calculate.

[0353]

[0354] <STEP 18> Minimum value minφ of the pipe diameter of the first heat transfer pipe 102 for each division point k ｋ Calculate.

[0355] <STEP 19> Minimum value minφ of the first heat transfer tube 102 for each division point k ｋ Maximum flow path width maxb of the heat dissipation fluid ｗ Calculate.

[0356]

[0357] <STEP 20> Diameter φ of the second heat transfer tube ｏｕｔ Calculate φ ｏｕｔ = minφ ｋ +maxb ｗ

[0358] <STEP 21> Flow path width b of the heat dissipation fluid at each division point k ｗｍｋ Calculate b ｗｍｋ =(φ ｏｕｔ -φ ｋ ) / 2

[0359] <STEP 22> The representative length d of the flow path at each division point k of the heat dissipation fluid ｗｍｋ Calculate d ｗｍｋ = 2 × b ｗｍｋ

[0360] <STEP 23> Reynolds number Re of the heat dissipation fluid at each division point k ｋ Calculate. 　 Re ｋ = (d ｗｍｋ ×u ｗ ) / V ｗ V ｗ : Dynamic viscosity coefficient of heated fluid (m ２ / s)

[0361] <STEP 24> Nusselt number Nu for each division point k of the heat dissipation fluid ｋ Calculate Nu ｋ = 0.023 × Re ｋ ０．８ ×P ｒ ０．３ P ｒ : Prandtl number of heat-dissipating fluid

[0362] <STEP 25> H of the heat transfer coefficient of the heat dissipation fluid at each division point ｗｋ Calculate Hｗｋ = (Nu ｋ ×λ ｗ ) / d ｗｍｋ λ ｗ : Thermal conductivity of the heat dissipating fluid

[0363] <STEP 26> Heat transfer coefficient H of metal wall ｍ Calculate H ｍ = λ ｍ / t λ ｍ : Thermal conductivity of the metal wall t: Thickness of the metal wall

[0364] <STEP 27> Overall heat transfer coefficient K of the heat exchanger at each division point k ｋ However, since the heat transfer coefficient of the condensed refrigerant is very large, it is not taken into account in the calculation of the overall heat transfer coefficient. Here, the reciprocal of the overall heat transfer coefficient K, 1 / K, is calculated. ｋ Calculate.

[0365]

[0366] <STEP 28> The flow path length l of the heat exchanger for each division point k ｋ Calculate the value of l. ｋ = (Q ｃ / n) / (K ｋ ×Δt ｋ ×C ｉｒｋ ) <STEP 30> Calculate the total length L of the heat exchanger. The total length L is the flow path length l for each division point k. ｋ is the sum of

[0367]

[0368] 32 is a table summarizing the configuration of an evaporator designed by the condenser design method using various refrigerants. The following conditions were applied in the condenser design method. <Condition 3> Mass flow rate: 1 kg / s Heating fluid: water Inlet temperature: 14°C Outlet temperature: 5°C

[0369] 33 is a table summarizing the configuration of an evaporator designed using a condenser design method using various refrigerants. The following conditions were applied in the condenser design method. <Condition 4> Mass flow rate: 0.05 kg / s Heating fluid: water Inlet temperature: 14°C Outlet temperature: 5°C

[0370] As shown in FIGS. 32 and 33, CO２ The volume change due to condensation of CO is smaller than that of other refrigerants. Therefore, when the heat exchanger 100L is used as a condenser, ２ By using water or brine as the heat dissipation fluid, it is possible to achieve a structure in which the change in the cross-sectional area of ​​the first heat transfer tube 102 is suppressed. This provides design advantages such as reduced pressure loss, suppressed energy loss, and simplified structure. ２ has excellent heat transfer performance, improves the heat exchange efficiency in the first region 102d and the second region 102e, and contributes to the miniaturization of the heat exchange device.

[0371] 25 is used as a condenser, the pipe diameter of the second heat transfer pipe 104 is determined as the sum of the minimum pipe diameter of the first heat transfer pipe 102 and the maximum flow path width of the second fluid 108, as in the heat exchanger 100L. However, in the heat exchanger 100M, the ratio between the minimum and maximum pipe diameters of the first heat transfer pipe 102 is small, i.e., the change in pipe diameter is small, so the difference between the minimum and maximum values ​​can also be treated as an error range. Therefore, there is no problem in designing the pipe diameter of the second heat transfer pipe 104 even if it is approximately defined as the sum of the representative pipe diameter (e.g., average or reference pipe diameter) of the first heat transfer pipe 102 and the flow path width of the second fluid 108.

[0372] As shown in Table 4, CO was used as a refrigerant. ２ When using water or brine (second fluid 108) as the heating fluid, the ratio of the minimum and maximum diameters of the first heat transfer tubes 102 can be kept to approximately 1 to 4 times. ２ Since the volume change during condensation is relatively small, there is no need to suddenly change the diameter of the first heat transfer tube 102, making it easy to ensure a long flow path. Therefore, the first heat transfer tube 102 can have a structure in which the diameter changes gradually, while still having a long overall length, and the heat exchanger 100M can be configured as a straight double-tube structure.

[0373] Twelfth Embodiment In this embodiment, a refrigeration cycle apparatus 500 (also referred to as a refrigeration cycle volume change work extraction apparatus) according to one embodiment of the present invention will be described with reference to FIG.

[0374] Fig. 29 is a schematic diagram showing a refrigeration cycle apparatus 500 according to one embodiment of the present invention. As shown in Fig. 29, the refrigeration cycle apparatus 500 includes a compressor 508, a heat exchanger 100L (condenser), an expansion valve 502, a heat exchanger 100K (evaporator), pumps 506 and 514, and turbines 504 and 512, which are connected by piping to form a refrigerant circuit through which a refrigerant circulates.

[0375] In the refrigeration cycle apparatus 500, it is preferable to apply a heat exchanger according to an embodiment of the present invention to either or both of the condenser and the evaporator. In Fig. 29, a case where the heat exchanger 100K is used as the evaporator and the heat exchanger 100L is used as the condenser is described, but any of the other heat exchangers 100, 100A to 100I may be used as appropriate.

[0376] 29 , in the refrigeration cycle apparatus 500, the first fluid 106a (evaporated refrigerant) flows into the first fluid distribution reservoir 32 via the expansion valve 502. The distributed first fluid 106a exchanges heat with the second fluid 108a (heating fluid) in the heat exchanger 100K, generating evaporation volume change work. After heat exchange, the first fluid 106a (evaporated refrigerant) flows into the first fluid collection reservoir 34 and is collected there, where it is converted into motive energy by the turbine 504. Meanwhile, the second fluid 108a is accelerated by the pump 506, flows into the second fluid distribution reservoir 36, and is distributed to the heat exchanger 100K. Next, the second fluid 108a (heating fluid) after heat exchange is collected in the second fluid collection reservoir 38.

[0377] The first fluid 106a (superheated vapor) after power conversion is adiabatically compressed by the compressor 508 and flows into the first fluid distribution reservoir 52 as the first fluid 106b (condensed refrigerant). The distributed first fluid 106b condenses by exchanging heat with the second fluid 108a in the heat exchanger 100L, generating condensation volume change work. The first fluid 106b (condensate) after heat exchange is collected in the first fluid collection reservoir 54, and the volume change work is converted into motive energy by the turbine 512. Meanwhile, the second fluid 108b (heat dissipation fluid) is accelerated by the pump 514 and flows into the second fluid distribution reservoir 56, where it is distributed to the heat exchanger 100L and undergoes heat exchange. Next, the second fluid 108b (heat dissipation fluid) after heat exchange is collected in the second fluid collection reservoir 58.

[0378] When the heat exchanger 100K is used as an evaporator, the flow path is tapered to diverge to accommodate the volume expansion associated with the evaporation of the refrigerant, thereby increasing the flow velocity of the first fluid 106 and effectively recovering the volume change work. On the other hand, when the heat exchanger 100L is used as a condenser, the flow velocity increases in response to the volume contraction of the refrigerant, so the tapered shape optimizes the velocity and pressure distribution and suppresses pressure loss. This improves the thermal efficiency and reduces energy loss of the refrigeration cycle apparatus 500 as a whole.

[0379] In particular, in the refrigeration cycle device 500, CO is used as the first fluid 106. ２ When CO is used as the second fluid 108 and water is used as the second fluid 108, the heat exchanger 100L can be used as the evaporator and the condenser. ２ By using this refrigerant, the change in specific volume due to evaporation and condensation is small, which makes it possible to design a gradual change in the cross-sectional area of ​​the heat exchanger, realizing efficient energy recovery with reduced pressure loss and turbulence.In addition, its high heat transfer performance and high-pressure operating characteristics contribute to improving the coefficient of performance (COP) of the entire cycle.

[0380] Example 1 A specific example in which the heat exchanger 100 according to one embodiment of the present invention is applied to a condenser will be described.

[0381] When the heat exchanger 100 is applied to a condenser, the condenser can be designed according to STEP 1 to STEP 31 of the condenser design method described in the first embodiment.

[0382] FIG. 18 summarizes the values ​​substituted for the variables in STEPs 1 to 31 and the results obtained by substituting values ​​for the variables. As explained in the condenser design method, the first heat transfer tube 102 and the second heat transfer tube 104 are divided into 100 parts. FIG. 18 shows the design values ​​at point 1D and point 100CY for the first heat transfer tube 102 and the second heat transfer tube 104 of the heat exchanger 100 shown in FIGS. 2A and 2B. In this embodiment, the volume change work, heat absorption amount, speed, etc. are calculated for each division point k, but FIG. 18 only shows the calculation results at point 1D and point 100CY, and does not show the calculation results at the other division points.

[0383] In the heat exchanger 100 designed using the above method, the cross-sectional area of ​​the first outlet 24 of the first heat transfer tube 102 is approximately 0.4% of the cross-sectional area of ​​the first inlet 22. By tapering the shape of the first heat transfer tube 102 to match the volume change of the first fluid 106, pressure loss in the first heat transfer tube 102 can be reduced. Therefore, the velocity of the first fluid 106 accelerates as it travels through the first heat transfer tube 102. The velocity of the first fluid 106 at the first outlet 24 can be approximately 10 times the velocity of the first fluid 106 at the first inlet 22. By accelerating the velocity of the first fluid 106, the volumetric work of gas condensation that can be extracted can be increased. The volumetric work of gas condensation at the first outlet 24 can be approximately 100 times the volumetric work of gas condensation at the first inlet 22.

[0384] Example 2 A specific example in which the heat exchanger 100A according to one embodiment of the present invention is applied to an evaporator will be described.

[0385] When the heat exchanger 100A is applied to an evaporator, the evaporator can be designed according to STEP 1 to STEP 31 of the design method for the evaporator described in the second embodiment.

[0386] 19 to 21 show the values ​​to be substituted into the variables in STEP 1 to STEP 25 and the results of substituting the values ​​into the variables.

[0387] 19 to 21 show the values ​​substituted for the variables in STEPs 1 to 25 and the results obtained by substituting the values ​​for the variables. As described in the evaporator design method, the first heat transfer tube 102 and the second heat transfer tube 104 are divided into 100 sections. FIGS. 19 to 21 show the design values ​​at points 1D, 34AK, 50BA, and 100CY for the first heat transfer tube 102 and the second heat transfer tube 104 of the heat exchanger 100A shown in FIGS. 3A and 3B. In this example, the volume change work, heat absorption, velocity, etc. are calculated for each division point. However, FIGS. 19 to 21 only show the calculation results for points 1D, 34AK, 50BA, and 100CY; the calculation results for the other division points are omitted.

[0388] In the heat exchanger 100A designed using the above method, the cross-sectional area of ​​the first heat transfer tube 102 at point 34AK is approximately 2% of the cross-sectional area of ​​the first inlet 22. The cross-sectional area of ​​the first heat transfer tube 102 at point 100CY is approximately 0.4% of the cross-sectional area of ​​the first inlet 22. The volume of the first fluid 106 in the first heat transfer tube 102 decreases, and then increases as the gas volume increases. Therefore, by shaping the first heat transfer tube 102 to have a tapered shape and a divergent shape in accordance with the volume change of the first fluid 106, the pressure loss in the first heat transfer tube 102 can be reduced. Therefore, the velocity of the first fluid 106 accelerates as it travels through the first heat transfer tube 102. The velocity of the first fluid 106 at the first outlet 24 can be approximately 10 times the velocity of the first fluid 106 at the first inlet 22. The increased velocity of the first fluid 106 increases the amount of liquid evaporation volumetric work that can be extracted. The amount of liquid evaporation volumetric work at the first outlet 24 can be as much as 100 times the amount of liquid evaporation volumetric work at the first inlet 22.

[0389] Although one embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the present invention. For example, a parking device according to the present embodiment can be modified by a person skilled in the art by adding, deleting, or modifying components as appropriate, and the modifications are within the scope of the present invention as long as they incorporate the gist of the present invention. Furthermore, the above-described embodiments can be combined as appropriate as long as they are not mutually inconsistent, and technical matters common to each embodiment are included in each embodiment even if not explicitly stated.

[0390] Even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention.

[0391] 22: first inlet, 24: first outlet, 26: second inlet, 28: second outlet, 100: heat exchanger, 100A: heat exchanger, 100B: heat exchanger, 100C: heat exchanger, 100D: heat exchanger, 102: first heat transfer tube, 104: second heat transfer tube, 106: first fluid, 108: second fluid, 109: fin, 300: refrigeration cycle device, 300A: refrigeration cycle device, 302: compressor, 304: condenser, 306: heat dissipation fluid recovery device, 308: turbine, 312: condensation pressure adjustment valve, 314: liquid-liquid heat exchanger, 316: receiver, 318: low-pressure expansion valve, 322: evaporator, 324: heating fluid recovery device, 326: turbine, 328: gas-liquid separator

Claims

1. A first heat transfer tube through which a first fluid can flow from a first inlet to a first outlet, A circular double tube having a second heat transfer tube through which a second fluid can flow from a second inlet to a second outlet, The first heat transfer tube has a first region in which the diameter decreases from the first inlet to the first outlet, a second region in which the diameter increases continuously with respect to the first region, and a third region in which the diameter increases further than that of the second region, The diameter of the second heat transfer tube is constant from the second inlet to the second outlet. A heat exchanger in which the diameter of the second heat transfer tube is the sum of the minimum diameter of the first heat transfer tube and the maximum flow width of the second fluid.

2. The heat exchanger according to claim 1, wherein the rate of increase of the pipe diameter in the third region is greater than the rate of increase of the pipe diameter in the second region.

3. The heat exchanger according to claim 1, wherein the length of the second region from the first inlet to the first outlet is longer than the length of the first region, and the length of the first region from the first inlet to the first outlet is longer than the length of the third region.

4. The heat exchanger according to claim 1, wherein the first fluid is a refrigerant and the second fluid is a heating fluid.

5. The heat exchanger according to claim 1, wherein the first fluid is carbon dioxide and the second fluid is water or brine.

6. A first heat transfer tube through which a first fluid can flow from a first inlet to a first outlet, A circular double tube having a second heat transfer tube through which a second fluid can flow from a second inlet to a second outlet, The first heat transfer tube has a first region in which the tube diameter decreases from the first inlet to the first outlet, and a second region continuous with the first region in which the tube diameter decreases further than that of the first region. The flow path cross-sectional area in the second heat transfer tube is constant from the second inlet to the second outlet. The diameter of the second heat transfer tube is the sum of the minimum diameter of the first heat transfer tube and the maximum flow width of the second fluid. A heat exchanger in which, in the heat exchange region between the first fluid and the second fluid, the flow path cross-section at the first inlet is parallel to the flow path cross-section at the second inlet, and the flow path cross-section at the first outlet is parallel to the flow path cross-section at the second outlet.

7. The heat exchanger according to claim 6, wherein the rate of reduction of the pipe diameter in the first region is greater than the rate of reduction of the pipe diameter in the second region.

8. The heat exchanger according to claim 6, wherein the length of the first region from the first inlet to the first outlet is longer than the length of the second region.

9. The heat exchanger according to claim 6, wherein the first fluid is a refrigerant and the second fluid is a heat dissipation fluid.

10. The heat exchanger according to claim 6, wherein the first fluid is carbon dioxide and the second fluid is water or brine.

11. The first inlet is connected to a first fluid distribution reservoir that causes the first fluid to flow into the first heat transfer tube, The first outlet is connected to a first fluid collection reservoir that collects the first fluid that has flowed through the first heat transfer tube. The second inlet is connected to a second fluid distribution reservoir that causes the second fluid to flow into the second heat transfer tube. The heat exchanger according to claim 6, wherein the second outlet is connected to a second fluid collection reservoir that collects the second fluid that has flowed through the second heat transfer tube.

12. A first heat transfer tube through which a first fluid can flow from a first inlet to a first outlet, A circular double tube having a second heat transfer tube through which a second fluid can flow from a second inlet to a second outlet, The first heat transfer tube has a constant diameter from the first inlet to the first outlet. The second heat transfer tube has a constant diameter from the first inlet to the first outlet. The diameter of the second heat transfer tube is the sum of the diameter of the first heat transfer tube and the width of the flow path of the second fluid. The first fluid is a refrigerant, and the second fluid is water or brine. A heat exchanger in which, in the heat exchange region between the first fluid and the second fluid, the flow path cross-section at the first inlet is parallel to the flow path cross-section at the second inlet, and the flow path cross-section at the first outlet is parallel to the flow path cross-section at the second outlet.

13. The heat exchanger according to claim 12, wherein the refrigerant is carbon dioxide.

14. The first inlet is connected to a first fluid distribution reservoir that causes the first fluid to flow into the first heat transfer tube, The first outlet is connected to a first fluid collection reservoir that collects the first fluid that has flowed through the first heat transfer tube. The second inlet is connected to a second fluid distribution reservoir that causes the second fluid to flow into the second heat transfer tube. The heat exchanger according to claim 6, wherein the second outlet is connected to a second fluid collection reservoir that collects the second fluid that has flowed through the second heat transfer tube.

15. The heat exchanger described in claim 1 is provided as an evaporator, A refrigeration cycle apparatus comprising the heat exchanger described in claim 6 as a condenser.

16. A heat exchanger having a heat transfer tube having a first region in which the tube diameter decreases from a first inlet to a first outlet, a second region in which the tube diameter increases continuously with respect to the first region, and a third region in which the tube diameter increases more than that of the second region, continuous with respect to the second region.

17. A first heat transfer tube in which a first fluid can flow from a first inlet to a first outlet, A method for designing a heat exchanger having a circular double tube, the second heat transfer tube through which a second fluid can flow from a second inlet to a second outlet, Based on the dryness χ in of the first inlet of the first heat transfer tube and equation (1), the standard volume change work E of the first fluid is calculated. The standard volume change work E is divided into n parts, and the cumulative change work E k of the first fluid at each division point k is calculated based on equation (2). Based on conditional equation (3), the density ρk of the first fluid is calculated for each division point k. Based on the cumulative change work Ek of the first fluid at each division point k and equation (4), the velocity uk of the first fluid is calculated at each division point k. A heat exchanger design method for calculating the standard flow channel cross-sectional area A k for each division point k based on the density ρ k and velocity u k of the first fluid at each division point k and equation (5). [Math 1] (In equation (1), E represents the work done on the standard volume change, χ in represents the dryness of the inlet, R represents the gas constant (kJ / kg), T represents the absolute temperature of evaporation (K), vl represents the specific volume of the liquid (m³ / kg), and vg represents the specific volume of the vapor (m³ / kg).) [Math 2] (In equation (2), E k represents the cumulative change work at the division point k, and k represents the division point.) [Math 3] (In equation (3), ρ k represents the density at the division point k, χ k represents the degree of dryness at the division point k, and ρ l represents the density of the liquid.) [Math 4] (In equation (4), u k represents the velocity at the division point k.) [Math 5] (In equation (5), A k represents the standard channel cross-sectional area at the division point k.)

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