Heat transfer system

Abstract

Provided is a heat transfer system for transferring heat generated in a heat source by using a fluid, wherein: the heat transfer system comprises a flow passage wall defining a flow passage through which the fluid flows, and a metal porous body that is disposed in the flow passage and transmits heat generated in the heat source to the fluid flowing through the flow passage; in a cross-section perpendicular to a first direction from the upstream side to the downstream side in the flow passage provided with the metal porous body, the flow passage includes a region where a third cross-sectional area S3 decreases along the first direction, where the third cross-sectional area S3 is an area S1–S2 obtained by subtracting a second cross-sectional area S2 from a first cross-sectional area S1, the first cross-sectional area S1 is the cross-sectional area of the flow path, and the second cross-sectional area S2 is the cross-sectional area of the metal porous body; the metal porous body is composed of a metal in which a plurality of pores are formed; at least some of the pores among the plurality of pores are open pores; the metal is composed of any of a metal composed of a single metal element selected from a first group consisting of aluminum, magnesium, copper, silver and gold, an alloy composed of two or more metal elements selected from the first group, a mixed-state metal of two or more metal elements selected from the first group, an alloy of one or more metal elements selected from the first group and one or more elements selected from a second group consisting of iron, cobalt, chromium, nickel, manganese, tin, zinc, silicon, phosphorus, carbon, boron, scandium, molybdenum, tungsten, and titanium, or a mixed-state metal of one or more metal elements selected from the first group and one or more elements selected from the second group; the pore diameter of the pores in the metal porous body is 10-420 μm; the porosity of the metal porous body is 60-85%; and the transmittance of the metal porous body is 0.6 × 10–12 m2 or greater.

Description

Heat Transfer System

[0001] The present disclosure relates to a heat transfer system. This application claims priority to Japanese Patent Application No. 2023-204504, filed December 4, 2023. The entire contents of the Japanese patent application are incorporated herein by reference.

[0002] In heat transfer systems that use fluids as heat transport media, such as heat exchangers, boilers, air conditioners, and radiators, the method of transferring heat between a high-temperature medium and a low-temperature medium via a heat transfer member with high thermal conductivity, known as heat exchange, is commonly used in a variety of applications.

[0003] In order to improve the heat exchange efficiency of a heat transfer system, a technique of providing a porous metal body as a heat transfer member in a fluid flow path has been studied (for example, Patent Document 1).

[0004] International Publication No. 2017 / 038380

[0005] A heat transfer system according to the present disclosure is a heat transfer system that transfers heat generated in a heat source using a fluid, the heat transfer system comprising: a flow path wall that defines a flow path through which the fluid flows; and a metal porous body that is disposed in the flow path and transfers heat generated in the heat source to the fluid flowing through the flow path; wherein, in a cross section of the flow path in which the metal porous body is disposed, taken perpendicular to a first direction from upstream to downstream of the flow path, when a cross-sectional area of ​​the flow path in which the metal porous body is disposed is a first cross-sectional area S1, a cross-sectional area of ​​the metal porous body is a second cross-sectional area S2, and an area S1-S2 obtained by subtracting the second cross-sectional area S2 from the first cross-sectional area S1 is a third cross-sectional area S3, the flow path includes a region where the third cross-sectional area S3 decreases along the first direction; the metal porous body is made of a metal having a plurality of pores formed therein, at least some of the pores are open pores; and the metal is a metal consisting of one metal element selected from a first group consisting of aluminum, magnesium, copper, silver, and gold; an alloy consisting of two or more metal elements selected from the first group; a metal in a composite state of two or more metal elements selected from the first group; an alloy consisting of one or more metal elements selected from the first group and one or more elements selected from a second group consisting of iron, cobalt, chromium, nickel, manganese, tin, zinc, silicon, phosphorus, carbon, boron, scandium, molybdenum, tungsten, and titanium; or a metal in a composite state of one or more metal elements selected from the first group and one or more elements selected from the second group, wherein the pore diameter of the pores of the metal porous body is 10 μm or more and 420 μm or less, the porosity of the metal porous body is 60% or more and 85% or less, and the transmittance of the metal porous body is 0.6×10 －１２ m ２ That is the heat transfer system.

[0006] FIG. 1 is a diagram illustrating a typical configuration example of a heat transfer system according to a first embodiment. FIG. 2 is a diagram illustrating a region of the heat transfer system 1 of FIG. 1 where the porous metal body 4 is provided, viewed from above the heat source 8. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2. FIG. 5 is another example of the cross-sectional view taken along line IV-IV in FIG. 2. FIG. 6 is another example of the cross-sectional view taken along line III-III in FIG. 2. FIG. 7 is another example of the cross-sectional view taken along line IV-IV in FIG. 2. FIG. 8 is a diagram illustrating a typical configuration example of a heat transfer system according to a fourth embodiment. FIG. 9 is a diagram illustrating a region of the heat transfer system 1 of FIG. 8 where the porous metal body 4 is provided, viewed from above the heat source 8. FIG. 10 is a rear view of FIG. 9. FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 9. FIG. 12 is an example of the cross-sectional view taken along line XII-XII in FIG. 9. Fig. 13 is another example of a cross-sectional view taken along line XII-XII in Fig. 9. Fig. 14 is a diagram showing the structure inside the flow channel of sample 2. Fig. 15 is a diagram showing the structure inside the flow channel of sample 3. Fig. 16 is a diagram showing the structure inside the flow channel of sample 4. Fig. 17 is a diagram showing the structure inside the flow channel of sample 2-1.

[0007] [Problem to be Solved by the Present Disclosure] Heat transfer systems using porous metal bodies tend to experience a decline in heat exchange efficiency as the heat exchanger is used. This tendency is particularly pronounced when industrial water containing a large amount of impurities is used as the fluid. Therefore, there is a demand for a heat transfer system that has excellent heat exchange efficiency and that suppresses the decline in heat exchange efficiency with use.

[0008] Therefore, an object of the present disclosure is to provide a heat transfer system that has excellent heat exchange efficiency and is suppressed from decreasing in heat exchange efficiency with use.

[0009] [Effects of the Present Disclosure] According to the present disclosure, it is possible to provide a heat transfer system that has excellent heat exchange efficiency and is suppressed from decreasing in heat exchange efficiency with use.

[0010] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be described. (1) A heat transfer system of the present disclosure is a heat transfer system that transfers heat generated in a heat source using a fluid, the heat transfer system comprising: a flow path wall that defines a flow path through which the fluid flows; and a metal porous body that is disposed in the flow path and transfers heat generated in the heat source to the fluid flowing through the flow path, wherein, in a cross section of the flow path in which the metal porous body is disposed, taken perpendicular to a first direction from upstream to downstream of the flow path, when a cross-sectional area of ​​the flow path is defined as a first cross-sectional area S1, a cross-sectional area of ​​the metal porous body is defined as a second cross-sectional area S2, and an area S1-S2 obtained by subtracting the second cross-sectional area S2 from the first cross-sectional area S1 is defined as a third cross-sectional area S3, the flow path includes a region where the third cross-sectional area S3 decreases along the first direction, the metal porous body is made of a metal having a plurality of pores formed therein, at least some of the pores are open pores, and the metal porous body is formed of a metal having a plurality of pores formed therein, at least some of the pores are open pores. The metal porous body is made of a metal consisting of one metal element selected from a first group consisting of aluminum, magnesium, copper, silver, and gold, an alloy consisting of two or more metal elements selected from the first group, a metal in a composite state of two or more metal elements selected from the first group, an alloy consisting of one or more metal elements selected from the first group and one or more elements selected from a second group consisting of iron, cobalt, chromium, nickel, manganese, tin, zinc, silicon, phosphorus, carbon, boron, scandium, molybdenum, tungsten, and titanium, or a metal in a composite state of one or more metal elements selected from the first group and one or more elements selected from the second group, and the pore size of the pores of the metal porous body is 10 μm or more and 420 μm or less, the porosity of the metal porous body is 60% or more and 85% or less, and the transmittance of the metal porous body is 0.6×10 －１２ m ２ That is the heat transfer system.

[0011] According to the present disclosure, it is possible to provide a heat transfer system that has excellent heat exchange efficiency and is suppressed from decreasing in heat exchange efficiency with use.

[0012] (2) In the above (1), the length L3 of the region along the first direction where the third cross-sectional area S3 decreases may be 30% or more of the length L1 of the metal porous body along the first direction, thereby further suppressing a decrease in heat exchange efficiency due to use of the heat transfer system.

[0013] (3) In the above (1) or (2), the flow path wall may include a flow path cross-sectional area adjusting member disposed in the flow path and configured to reduce the third cross-sectional area S3. By adjusting the shape and arrangement of the flow path cross-sectional area adjusting member, it is possible to easily adjust the region where the third cross-sectional area S3 is reduced.

[0014] (4) In the above (1) or (2), the metal porous body may include a main body portion extending in the first direction, a first end face of the main body portion on the upstream side of the flow path, and a second end face of the main body portion on the downstream side of the flow path, and the metal porous body may have a through hole formed therein that penetrates from the first end face to the second end face, separate from the plurality of pores.

[0015] This is expected to improve heat exchange efficiency by promoting the intake of fluid into the porous metal body through the wall surfaces of the through holes, and to prevent foreign matter contained in the fluid from entering the porous metal body and causing clogging by passing through the through holes.

[0016] (5) In the above (4), when the cross-sectional area of ​​the through hole in a cross section of the metal porous body perpendicular to the first direction is defined as a fourth cross-sectional area S4, the metal porous body may include a region in which the fourth cross-sectional area S4 decreases along the first direction, and in a cross section of the flow path in which the metal porous body is provided perpendicular to the first direction, all of the outer edges of the metal porous body may be in contact with the flow path wall.

[0017] According to this, by slowing down the fluid movement speed on the inner wall surface of the through-holes, the intake of the fluid into the metal porous body is promoted, and it is expected that the heat exchange efficiency will be improved. On the other hand, by increasing the flow speed at the center of the through-holes, the effect of expelling foreign matter will be maintained.

[0018] (6) In any of (1) to (5) above, the metal porous body may include a main body portion extending in the first direction, a first end face of the main body portion on the upstream side of the flow path, and a second end face of the main body portion on the downstream side of the flow path, and the heat transfer system may include a shielding member provided on the first end face.

[0019] This further suppresses the decrease in heat exchange efficiency that occurs with use in the heat transfer system.

[0020] (7) In any one of (1) to (6) above, the thermal conductivity of the metal may be 100 W / m·K or more. This further improves the heat exchange efficiency of the heat transfer system.

[0021] (8) In any one of the above (1) to (7), the transmittance of the porous metal body is 0.8 × 10 －１２ m ２ This further improves the heat exchange efficiency of the heat transfer system.

[0022] (9) In any one of the above (1) to (8), the open porosity of the pores of the metal porous body may be 60% or more, thereby reducing the flow resistance of the fluid.

[0023] (10) A heat transfer system according to the present disclosure is a heat transfer system that transfers heat generated in a heat source using a fluid, the heat transfer system comprising: a flow path wall that defines a flow path through which the fluid flows; and a metal porous body that is disposed in the flow path and transfers heat generated in the heat source to the fluid flowing through the flow path; when viewed along a first direction from upstream to downstream of the flow path in which the metal porous body is disposed, the metal porous body includes a first region that is located on the heat source side and has a first width; and a second region that is located on the opposite side of the heat source across the first region and has a width narrower than the first width; the flow path is occupied by the first region and the second region; the metal porous body is made of a metal having a plurality of pores formed therein, at least some of the pores being open pores; and the metal is aluminum. the porous metal body is made of a metal consisting of one metal element selected from a first group consisting of aluminum, magnesium, copper, silver, and gold; an alloy consisting of two or more metal elements selected from the first group; a metal in a composite state of two or more metal elements selected from the first group; an alloy consisting of one or more metal elements selected from the first group and one or more elements selected from a second group consisting of iron, cobalt, chromium, nickel, manganese, tin, zinc, silicon, phosphorus, carbon, boron, scandium, molybdenum, tungsten, and titanium; or a metal in a composite state of one or more metal elements selected from the first group and one or more elements selected from the second group; the pore diameter of the pores of the porous metal body is 10 μm or more and 420 μm or less; the porosity of the porous metal body is 60% or more and 85% or less; and the transmittance of the porous metal body is 0.6×10 －１２ m ２ That is the heat transfer system.

[0024] According to the present disclosure, it is possible to provide a heat transfer system that has excellent heat exchange efficiency and is suppressed from decreasing in heat exchange efficiency with use.

[0025] [Details of the embodiment of the present disclosure] Specific examples of the heat transfer system of the present disclosure will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference numerals represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately changed for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0026] In this specification, the expression "A to B" means the upper and lower limits of a range (i.e., A or more and B or less), and when no unit is specified for A and a unit is specified only for B, the unit of A and the unit of B are the same.

[0027] In the present specification, when a compound or the like is represented by a chemical formula, unless the atomic ratio is particularly limited, it is understood to include any conventionally known atomic ratio, and is not necessarily limited to only those within the stoichiometric range.

[0028] In the present disclosure, when one or more numerical values ​​are described as the lower limit and the upper limit of a numerical range, the combination of any one numerical value described in the lower limit and any one numerical value described in the upper limit is also disclosed.

[0029] In developing a heat transfer system that has excellent heat exchange efficiency and that suppresses the decrease in heat exchange efficiency with use, the inventors investigated the reasons for the decrease in heat exchange efficiency in conventional heat transfer systems. In conventional heat transfer systems, for example, as shown in Figure 16, a flow path 3 is occupied by a porous metal body 4. When the porous metal body 4 was observed after using the heat transfer system having the configuration shown in Figure 16 for a certain period of time, it was confirmed that impurities contained in the fluid 2 had adhered to the pores of the porous metal body 4, causing clogging. It was estimated that the clogging easily hinders the transfer of heat from the porous metal body 4 to the fluid 2, resulting in a decrease in heat exchange efficiency.

[0030] Based on the above assumption, the inventors assumed that the decrease in heat exchange efficiency could be suppressed by suppressing clogging of the porous metal body 4, and after much trial and error, they completed the heat transfer system of the present disclosure. A specific example of the heat transfer system of the present disclosure is described below.

[0031] [Embodiment 1] The configuration of a heat transfer system according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 1") will be described with reference to Figures 1 to 4. As shown in Figure 1, the heat transfer system 1 of Embodiment 1 includes a flow path wall 3a that defines a flow path 3 through which a fluid 2 flows, and a porous metal body 4 that is disposed in the flow path 3 and transfers heat generated in a heat source 8 to the fluid 2 flowing through the flow path 3.

[0032] Fig. 2 is a view of the region where the porous metal body 4 is provided in the heat transfer system 1 of Fig. 1, viewed from above the heat source 8. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 2. In Fig. 4, the direction of arrow F1 corresponds to a first direction from upstream to downstream of the flow path.

[0033] In the flow path provided with the porous metal body 4, the porous metal body 4 is provided on the flow path wall 3a located on the heat source 8 side. This makes it easier for heat generated in the heat source 8 to be transferred to the porous metal body 4. When a driving force in the direction of arrow F1 is applied to the fluid 2 to pass through the porous metal body 4, heat exchange occurs between the fluid 2 and the heat source 8 via the porous metal body 4. The heat transfer system 1 can include a metal plate 11 disposed between the heat source 8 and the flow path wall 3a, which promotes heat transfer from the heat source 8 to the fluid 2.

[0034] The thermal conductivity of the porous metal body used in the first embodiment is higher than that of common fluids (e.g., water, radiator fluid, industrial water) used in heat transfer systems. Therefore, in the flow path 3 provided with the porous metal body 4, heat from the heat source 8 is easily transferred to the fluid 2 through the porous metal body 4. In other words, the presence of the porous metal body 4 improves the efficiency of heat exchange between the fluid 2 and the heat source 8.

[0035] On the other hand, if a porous metal body 4 is provided in the flow path 3, the porous metal body 4 increases the movement resistance (pressure loss) of the fluid 2, and the flow velocity of the fluid 2 in the direction of arrow F1 after passing through the porous metal body 4 tends to decrease. A decrease in the flow velocity in the direction of arrow F1 reduces the heat exchange efficiency between the fluid 2 and the heat source 8. Because the porous metal body 4 used in embodiment 1 has high permeability, the effect of an increase in the amount of heat transfer due to the large specific surface area (a positive effect on heat exchange efficiency) is greater than the effect of a decrease in flow velocity due to an increase in movement resistance (a negative effect on heat exchange efficiency), thereby improving the heat exchange efficiency. Therefore, the effect of a decrease in flow velocity due to the provision of the porous metal body 4 is suppressed. Therefore, by using the porous metal body 4 of embodiment 1, the heat exchange efficiency between the fluid 2 and the heat source 8 is improved overall.

[0036] As shown in FIG. 4 , a flow channel cross-sectional area adjusting member 12 is provided on the flow channel wall 3a of the flow channel at a location where the metal porous body 4 is provided. In a cross section perpendicular to a first direction from upstream to downstream of the flow channel 3 where the metal porous body 4 is provided, the cross-sectional area of ​​the flow channel 3 is defined as a first cross-sectional area S1, the cross-sectional area of ​​the metal porous body 4 is defined as a second cross-sectional area S2, and the area S1-S2 obtained by subtracting the second cross-sectional area S2 from the first cross-sectional area S1 is defined as a third cross-sectional area S3. The flow channel 3 includes a region where the third cross-sectional area S3 decreases along the first direction. This increases the flow velocity of the fluid in the region where the third cross-sectional area S3 decreases. When the flow velocity of the fluid increases, a force directed toward the outside of the metal porous body is applied to the fluid that has entered the pores of the metal porous body, facilitating the fluid's movement out of the metal porous body. As the fluid moves, impurities contained in the fluid also move out of the metal porous body, thereby suppressing adhesion of impurities to the pores of the metal porous body and suppressing clogging of the metal porous body. Therefore, in the heat transfer system of the first embodiment, the heat exchange efficiency accompanying use is suppressed.

[0037] The length L3 of the region where the third cross-sectional area S3 along the first direction decreases may be 30% or more of the length L1 of the porous metal body along the first direction. This makes it easier for the fluid flow rate to increase, improves the anti-clogging effect of the porous metal body, and further suppresses the heat exchange efficiency associated with use in the heat transfer system. The percentage of the length L3 with respect to the length L1 may be 30% or more and 100% or less, 40% or more and 100% or less, or 60% or more and 100% or less. When the percentage of the length L3 with respect to the length L1 is 100%, this means that the region where the third cross-sectional area S3 decreases is located from the upstream side to the downstream side of the flow path in which the porous metal body 4 is provided.

[0038] 4, the third cross-sectional area S3 may be smallest on the downstream side of the flow path 3 where the porous metal body 4 is provided. The downstream side of the flow path where the porous metal body is provided means a region of the flow path between the center of the width of the flow path when viewed along the first direction and the downstream end of the flow path.

[0039] In the region where the third cross-sectional area S3 decreases, the percentage (S3 / S1)×100 of the third cross-sectional area S3 relative to the first cross-sectional area S1 may be 0% or more and 90% or less, or 8% or more and 50% or less.

[0040] In the region where the third cross-sectional area S3 decreases, the difference between the maximum value and the minimum value of the percentage (S3 / S1)×100 may be 8% or more and 90% or less.

[0041] In areas other than the area where the third cross-sectional area S3 of the flow path where the metal porous body is provided decreases, the percentage (S3 / S1) x 100 of the third cross-sectional area S3 to the first cross-sectional area S1 may be 0% or more and 90% or less.

[0042] <Flow Channel> In the heat transfer system 1 of the first embodiment, the flow channel 3 is defined by a flow channel wall 3a. The flow channel 3 may form at least one closed loop. The closed loop may have branches within one closed loop. The flow channel 3 may also form multiple closed loops arranged in parallel. When the flow channel 3 forms a closed loop, the fluid 2 circulates within the flow channel 3.

[0043] The cross-sectional shape of the flow channel 3 in a cross section perpendicular to the first direction from upstream to downstream of the flow channel is not particularly limited. For example, the cross-sectional shape of the flow channel 3 may be rectangular, circular, or elliptical. The area of ​​the cross section is not particularly limited and can be changed appropriately depending on the application.

[0044] The flow path wall 3a may have an opening that connects the flow path 3 with the external space of the flow path 3. In this case, the fluid 2 can move between the flow path 3 and the external space.

[0045] The shape of the flow path wall 3a is not particularly limited, and any conventionally known shape can be used.

[0046] The material of the flow path wall 3a can be appropriately selected taking into consideration fluid resistance, thermal conductivity, heat insulation, etc. For example, a fluororesin such as polytetrafluoroethylene can be used. The material of the flow path wall 3a located in the region where the metal porous body is provided may be a material having higher thermal conductivity than the other portions (e.g., aluminum, copper, stainless steel, aluminum oxide). Furthermore, the flow path wall located in the region where the metal porous body is provided may be covered with a material different from the flow path wall (e.g., aluminum, copper, stainless steel).

[0047] The flow path wall 3a and the metal porous body 4 may be in contact with each other. This increases the amount of heat transferred from the metal porous body 4 to the fluid 2, further improving the fluid flow rate, further increasing the flow rate generated by the entire heat transfer system, and further improving the heat exchange efficiency. The flow path wall 3a and the metal porous body 4 may be integrally molded or soldered together. As long as the effects of the present disclosure are not impaired, a configuration in which the flow path wall 3a and the metal porous body 4 are not in contact is also within the scope of the present disclosure. Examples of such a configuration include a case in which a very small gap exists between the flow path wall 3a and the metal porous body 4, or a case in which another member with very high thermal conductivity is sandwiched between the flow path wall 3a and the metal porous body 4.

[0048] <Porous Metal Body> In the heat transfer system 1 of the first embodiment, the porous metal body 4 is made of a metal having a plurality of pores formed therein. At least some of the pores are open pores. Open pores refer to pores contained in the porous metal body 4 that are connected to the surface of the porous metal body 4. Because the porous metal body 4 has open pores, fluid can pass through the open pores to move between the outside and the inside of the porous metal body 4. At least some of the pores are connected to each other. Of the outer surface of the porous metal body 4 in the region where the third cross-sectional area S3 decreases, the region that is not in contact with the flow path wall 3a is exposed, and no material is present to block the open pores. This allows fluid that has entered the pores of the porous metal body 4 to easily move to the outside of the porous metal body 4.

[0049] <Composition> The metal constituting the metal porous body 4 is a metal consisting of one metal element selected from a first group consisting of aluminum, magnesium, copper, silver, and gold; an alloy consisting of two or more metal elements selected from the first group; a metal in a composite state of two or more metal elements selected from the first group; an alloy consisting of one or more metal elements selected from the first group and one or more elements selected from a second group consisting of iron, cobalt, chromium, nickel, manganese, tin, zinc, silicon, phosphorus, carbon, boron, scandium, molybdenum, tungsten, and titanium; or a metal in a composite state of one or more metal elements selected from the first group and one or more elements selected from the second group.

[0050] The above metals have high thermal conductivity, which further improves the heat exchange efficiency of the heat transfer system.

[0051] In the present disclosure, the term "metal" is defined as a concept including metals consisting of one type of metal element, alloys containing two or more types of metal elements, and metals in a composite state of two or more types of metal elements.

[0052] In the present disclosure, the term "a metal in a composite state of two or more metal elements" refers to a state in which two or more metals exist as individual substances, rather than as an alloy. Specifically, it refers to a state in which the surfaces of two or more metal powders are bonded together to form a molded product.

[0053] In the present disclosure, "a metal in a composite state of one or more metal elements selected from Group 1 and one or more elements selected from Group 2" means, when the element of Group 2 is carbon, a powder of one or more metals selected from Group 1 bonded to graphite or diamond, or a carbide of one or more metals selected from Group 1. When the element of Group 2 is boron, a powder of one or more metals selected from Group 1 bonded to a powder of boron alone, or a boride of one or more metals selected from Group 1.

[0054] Examples of alloys include Cu-1% Ag alloy and Al-1% Mg-0.6% Si-0.5% Fe-0.25% Cu-0.1% Cr alloy (A6061).

[0055] From the viewpoint of high thermal conductivity, the metal may be pure copper, pure aluminum, a copper alloy containing 50 mass% or more of copper, or an aluminum alloy containing 50 mass% or more of aluminum. The alloy may be in a state where the constituent elements are solid-solved in copper, aluminum, etc. The alloy may be in a state where precipitates or heterogeneous phases are dispersed.

[0056] The composition of the constituent elements of the porous metal body is measured by ICP emission spectrometry.

[0057] The metal porous body of the heat transfer system of embodiment 1 may contain impurities other than the above metals, as long as the effects of the present disclosure are not impaired. Here, as defined above, "metal" encompasses metals consisting of one metal element, alloys containing two or more metal elements, and composite metals containing two or more metal elements. The metal porous body of embodiment 1 may be composed of the above metals and impurities. Examples of such impurities include oxygen, hydrogen, carbon, nitrogen, sulfur, phosphorus, boron, silicon, and metal elements other than the metal elements in the first and second groups. The impurities are contained independently from the matrix phase in the form of precipitates or the like. The content of the impurities need only be less than the volume ratio required to achieve a predetermined thermal conductivity. For example, it can be 3 atomic % or less. The content of the impurities is measured by gas chromatography (GC) analysis or ICP atomic emission spectrometry.

[0058] <Structure> The porous metal body 4 is made of a metal having a plurality of pores formed therein. That is, the porous metal body 4 has a plurality of pores. At least some of the pores are open pores. The pore diameter of the porous metal body is 10 μm or more and 420 μm or less. The porosity of the porous metal body 4 is 60% or more and 85% or less. The transmittance of the porous metal body 4 is 0.6×10 －１２ m ２ This allows the fluid to pass through the interior of the porous metal body through the pores in the porous metal body.

[0059] The porous metal body may include a main body portion extending in a first direction, a first end face of the main body portion on an upstream side of the flow path, and a second end face of the main body portion on a downstream side of the flow path, and a shielding member may be provided on the first end face. The shielding member may be provided so as to cover the entire first end face or so as to cover a portion of the first end face.

[0060] <<Pore Diameter>> In embodiment 1, the pore diameter of the pores in the metal porous body is 10 μm or more and 420 μm or less. When the pore diameter of the pores in the metal porous body is 10 μm or more, an increase in the flow resistance of the fluid is suppressed. When the minimum pore diameter of the pores is less than 10 μm, fluid movement due to capillary force is less likely to occur, so even open pores act as substantially closed pores in portions far from the shortest path of the fluid movement path. When the pore diameter of the pores in the metal porous body is 420 μm or less, the contact area with the fluid is increased, and heat transfer between the metal porous body and the fluid can be promoted.

[0061] The pore size of the metal porous body may be 15 μm or more and 420 μm or less, 20 μm or more and 380 μm or less, 30 μm or more and 360 μm or less, or 40 μm or more and 300 μm or less.

[0062] The pore size of the metal porous body is measured by mercury intrusion porosimetry. Mercury intrusion porosimetry is performed in accordance with JIS R 1655:2003 "Method for testing pore size distribution of molded bodies by mercury intrusion porosimetry for fine ceramics." An AutoPore V9600 from Micrometrics can be used as the apparatus. In this disclosure, the pore size of the metal porous body refers to the range of the pore size distribution of the open pores of the metal porous body measured by mercury intrusion porosimetry. For example, "the pore size of the metal porous body is 10 μm or more and 420 μm or less" means that the pore size of each open pore of the metal porous body is within the range of 10 μm or more and 420 μm or less.

[0063] <Porosity> In the first embodiment, the porosity of the metal porous body 4 is 60% or more and 85% or less. The lower limit of the porosity of the metal porous body is 60% or more from the viewpoint of reducing the flow resistance of the fluid. The upper limit of the porosity of the metal porous body is 85% or less from the viewpoint of increasing the contact area with the fluid and promoting the transfer of heat between the metal porous body and the fluid. The porosity of the metal porous body may be 70% or more and 85% or less, or may be 75% or more and 80% or less.

[0064] The porosity of a porous metal body is defined by the following formula (1): Porosity = 1 - [mass of porous metal body [g] / (volume of porous metal body [cm ３ ]×Material density [g / cm ３ ]) )]} × 100 [%] (1) The "volume of the metal porous body [cm ３ ]" means the volume based on the outer shape of the metal porous body including pores.

[0065] <<Transmittance>> In the first embodiment, the transmittance of the porous metal body is 0.6 × 10 －１２ m ２ As a result, the flow resistance of the fluid is reduced. The permeability of the porous metal body is 0.60×10 －１２ m ２ Above 1.0 x 10 －１０ m ２ or less, 0.70 × 10 －１２ m ２ Above 1.0 x 10 －１０ m ２ or less, 0.80 × 10 －１２ m２ Above 1.0 x 10 －１０ m ２ or less, or 0.90 x 10 －１２ m ２ Above 1.0 x 10 －１０ m ２ The following is also acceptable.

[0066] The permeability of a porous metal body can be measured by evaluating the water permeability of the porous metal body in accordance with JIS R 1671:2006, "Test method for water permeability and hydraulic equivalent diameter of porous fine ceramic bodies." Specifically, an evaluation sample consisting of a porous metal body with a diameter of 25 mm and a thickness of 3 mm is prepared, and evaluation is performed based on the above-mentioned JIS standard. If the porous metal body to be evaluated is smaller than the size of the evaluation sample, an evaluation sample may be prepared by combining multiple porous metal bodies to obtain a diameter of 25 mm and a thickness of 3 mm.

[0067] <Open Porosity> In the heat transfer system 1 of the first embodiment, the metal porous body 4 includes open pores. In the present disclosure, "open porosity" refers to the volume ratio (volume %) of open pores to the total pores (including open pores and closed pores) contained in the metal porous body. "Open pores" refer to pores contained in the metal porous body that are in communication with the surface of the metal porous body. "Closed pores" refer to pores contained in the metal porous body that are not in communication with the surface of the metal porous body.

[0068] In the first embodiment, the open porosity of the pores of the metal porous body may be 50% or more from the viewpoint of reducing the flow resistance of the fluid, or may be 50% or more and 100% or less, 60% or more and 100% or less, or 70% or more and 100% or less.

[0069] The open porosity of pores in a porous metal body is measured as follows: First, the apparent porosity P1 (corresponding to the open porosity of the porous metal body) is measured by the Archimedes method or mercury intrusion porosimetry (specified in JIS R 1655:2003 "Test method for pore size distribution of molded fine ceramics by mercury intrusion porosimetry").

[0070] The porosity P2 of the porous metal body (corresponding to the total porosity of the porous metal body) is calculated based on the above formula (1).

[0071] The percentage of the apparent porosity P1 of the porous metal body relative to the porosity P2 of the porous metal body is calculated as (P1 / P2) x 100. This percentage is the open porosity of the pores of the porous metal body.

[0072] <Thermal Conductivity of Porous Metal Body> In the first embodiment, the thermal conductivity of the porous metal body may be 10 W / m·K or more. This makes it easier for heat from outside the internal space to be transferred to the fluid through the porous metal body. The thermal conductivity of the porous metal body may be 10 W / m·K or more and 205 W / m·K or less, 15 W / m·K or more and 205 W / m·K or less, or 25 W / m·K or more and 205 W / m·K or less.

[0073] The thermal conductivity of a porous metal body is measured as follows. The upper and lower surfaces (circular portions) of a porous metal body processed to φ10 mm x 2.2 mmt are polished to a thickness of 2.0 mm using emery paper in a non-oxidizing room temperature atmosphere with an oxygen concentration of 10,000 ppm. After removing shavings using an air blower or the like, pure aluminum foil having a diameter of 10 mm and a thickness of 20 μm is brought into contact with the polished upper and lower surfaces of the porous metal body. In this state, a load of 50 kgf is applied using a hand press to bring the aluminum foil into close contact with the porous metal body, thereby obtaining a measurement sample.

[0074] The thermal conductivity of the porous metal body is measured by the laser flash method using the measurement sample. More specifically, the thermal diffusion coefficient is measured using an LFA457 MicroFlash (manufactured by NETZSCH), and the thermal conductivity in the thickness direction of the porous metal body is calculated based on the thermal diffusion coefficient and the volume ratio and specific heat of each constituent material.

[0075] When calculating the thermal conductivity, the specific heat of each constituent material is determined based on "Metal Data Book, 4th Edition" (2004, Maruzen Publishing), edited by the Japan Institute of Metals. Pores can be treated as air, and their specific heat is calculated as 1.0 kJ / (kg K). Prior to measuring the thermal conductivity, the thermal conductivity of a pure copper sample of the same shape is measured under the same conditions, and the result is used as a reference to correct the measurement results.

[0076] If the planar shape of the metal porous body to be evaluated is smaller than a circle with a diameter of 10 mm, cut out multiple samples and align them so that their surfaces are on the same plane to form a 50 mm diameter sample. ２ The above measurement area may be secured for evaluation.

[0077] <Thermal Conductivity of Metal> In the porous metal body of the heat transfer system of embodiment 1, the thermal conductivity of the metal may be 100 W / m·K or more. Factors that contribute to the thermal conductivity of the porous metal body include the thermal conductivity of the material, the volume ratio of the metal in the porous metal body, and, when the porous metal body is formed by bonding metal powders, the interfacial thermal resistance between the metal powders. When the thermal conductivity of the metal is 100 W / m·K or more, the thermal conductivity of the porous metal body is improved.

[0078] The thermal conductivity of the metal may be 100 W / m·K or more and 400 W / m·K or less, or 200 W / m·K or more and 400 W / m·K or less, or 350 W / m·K or more and 400 W / m·K or less.

[0079] The thermal conductivity of metals is measured as follows. A porous metal body is heated in a hydrogen atmosphere at a temperature (K) that is 80% of the lowest melting temperature (K) of the materials that make up the body, resulting in a state in which no oxide coating of the base metal is present on the interior wall of the porous metal body. The body is then densified in a vacuum (10 Pa or less) by spark plasma sintering while maintaining a non-oxidizing atmosphere. The heating temperature is the hydrogen atmosphere treatment temperature, and the pressure is 30 MPa for 10 minutes. The thermal conductivity of the resulting dense body is measured by the laser flash method. More specifically, the thermal diffusion coefficient is measured using an LFA457 MicroFlash (manufactured by NETZSCH), and the thermal conductivity through the thickness is calculated based on the thermal diffusion coefficient and the volume ratio and specific heat of each constituent material.

[0080] When calculating the thermal conductivity, the specific heat of each constituent material is determined based on "Metal Data Book, 4th Edition" (2004, Maruzen Publishing), edited by the Japan Institute of Metals. Pores can be treated as air, and their specific heat is calculated as 1.0 kJ / (kg K). Prior to measuring the thermal conductivity, the thermal conductivity of a pure copper sample of the same shape is measured under the same conditions, and the result is used as a reference to correct the measurement results.

[0081] If the planar shape to be evaluated is smaller than a circle with a diameter of 10 mm, cut out multiple samples and align them so that their surfaces are on the same plane to form a 50 mm ２ The above measurement area may be secured for evaluation.

[0082] <Method for manufacturing porous metal body> The following describes an example of a method for manufacturing the porous metal body of the heat transfer system of embodiment 1. The method for manufacturing the porous metal body of embodiment 1 can include a preparation step, a mixing step, a sintering step, and a cleaning step.

[0083] <Preparation Step> In the preparation step, a raw material powder of the porous metal body and sodium chloride powder (NaCl powder) are prepared.

[0084] Examples of the raw material powder include metal powders made of one metal element selected from Group 1 consisting of aluminum, magnesium, copper, silver, and gold, alloy powders made of two or more metal elements selected from Group 1, and powders made of one or more metal elements selected from Group 1 and one or more elements selected from Group 2 consisting of iron, cobalt, chromium, nickel, manganese, tin, zinc, silicon, phosphorus, carbon, boron, scandium, molybdenum, tungsten, and titanium.

[0085] The particle diameter D10 of the raw material powder is 6 to 45 μm, D50 is 13 to 75 μm, and D90 is 27 to 106 μm. Here, the particle diameter D10 of the raw material powder is the particle diameter at which the cumulative volume fraction from the small diameter side is 10% in a histogram where the horizontal axis represents particle diameter and the vertical axis represents volume fraction. The particle diameter D50 of the raw material powder is the particle diameter at which the cumulative volume fraction from the small diameter side is 50% in the histogram. The particle diameter D90 of the raw material powder is the particle diameter at which the cumulative volume fraction from the small diameter side is 90% in the histogram. The D10, D50, and D90 are measured by a laser diffraction / scattering method.

[0086] The particle diameter D50 of the NaCl powder is 45 to 500 μm. Here, the particle diameter D50 of the NaCl powder is the particle diameter at which the cumulative volume fraction from the smallest diameter side is 50% in a histogram in which the horizontal axis represents particle diameter and the vertical axis represents volume fraction. The histogram is created based on the results of sieving a sample using a sieve specified in JIS Z 8801-1:2019 "Test sieves - Part 1: Metal mesh sieves" and measuring the mass of the sample remaining on each sieve.

[0087] <Mixing Step> Next, in the mixing step, the raw material powder and NaCl powder are mixed to obtain a mixed powder. The mixing ratio of the raw material powder and NaCl powder is appropriately adjusted depending on the porosity of the metal porous body to be manufactured. The percentage of NaCl powder in the mixed powder varies depending on the average particle size of the NaCl powder: if the average particle size is 45 to 70 μm, it is 60 to 88 vol %, and if the average particle size is more than 70 μm and 500 μm or less, it is 79 to 88 vol %.

[0088] The mixed powder is placed in a cylindrical glass container with a diameter of 100 mm and a wall thickness of 1 mm, and mixed for 10 minutes by rotating the glass container at 120 rpm around the axial direction of the container. A rotary mill, for example, can be used for mixing. Alternatively, a W-type mixer, V-type mixer, or drum mixer can also be used if the raw material powders and NaCl powder can be uniformly mixed. If there is a risk of dust explosion from the mixed powder, the atmosphere inside the glass container can be replaced with a low-oxygen atmosphere or an inert atmosphere.

[0089] <Sintering Step> Next, in the sintering step, the mixed powder is loaded into a mold made of graphite or hot-working alloy tool steel, and pressure sintering is performed to obtain a sintered body. The pressure sintering conditions are 20 to 750°C, a pressure of 10 to 2000 MPa, and a holding time of 1 second to 30 minutes. Before pressure sintering, the mixed powder may be preformed into a green compact.

[0090] <<Cleaning Step>> Next, in the cleaning step, the sintered body is immersed in water to dissolve NaCl into the water, thereby obtaining a porous metal body. Specifically, approximately 1 L of pure water is prepared for 10 g of sintered body. The pure water is placed in a beaker, and the sintered body is immersed in the pure water and stirred. By immersing for a total of approximately 50 hours, with the pure water being replaced every 5 hours, NaCl is sufficiently dissolved outside the porous metal body. This allows the porous metal body of the heat transfer system of embodiment 1 to be obtained.

[0091] <Volume of Porous Metal Body> In the first embodiment, the porous metal body 4 is provided in the heat receiving area 6, and the volume of the porous metal body 4 may be 30% or more of the volume of the heat receiving area 6. This increases the amount of heat transferred from the porous metal body 4 to the fluid 2, further improving the flow rate of the fluid, further improving the flow rate generated by the entire heat transfer system, and further improving the heat exchange efficiency.

[0092] The volume occupied by the metal porous body 4 relative to the volume of the heat receiving area 6 may be 30% or more and 100% or less, 40% or more and 100% or less, 50% or more and 100% or less, or 90% or more and 100% or less.

[0093] <Flow path cross-sectional area adjusting member> In the flow path provided with the metal porous body 4 of the heat transfer system 1 of embodiment 1, a flow path cross-sectional area adjusting member 12 is provided in the flow path other than the flow path 3 provided with the metal porous body. The shape of the flow path cross-sectional area adjusting member 12 is not particularly limited as long as it can reduce the third cross-sectional area S3.

[0094] The material of the flow path cross-sectional area adjusting member 12 can be appropriately selected in consideration of resistance to fluid, thermal conductivity, heat insulation, etc. For example, fluororesin such as polytetrafluoroethylene, stainless steel, copper, aluminum, etc. can be used.

[0095] The flow path wall 3a and the flow path cross-sectional area adjusting member 12 may be in contact with each other. The flow path wall 3a and the flow path cross-sectional area adjusting member 12 may be integrally molded or soldered together. Furthermore, the flow path wall 3a and the flow path cross-sectional area adjusting member 12 may not be in contact with each other. An example of such a configuration is when another member is sandwiched between the flow path wall 3a and the flow path cross-sectional area adjusting member 12.

[0096] <Fluid> In the heat transfer system 1 of the first embodiment, the fluid 2 may be a liquid. There are no particular limitations on the type of fluid 2, as long as it is a type commonly used in heat transfer systems. Examples of the fluid 2 include water, radiator fluid, acetone, ethanol, and industrial water. In particular, when the fluid is industrial water containing impurities, the heat exchange efficiency of conventional heat transfer systems tends to decrease with use. According to the heat transfer system of the present disclosure, even when the fluid is industrial water containing impurities, the decrease in heat exchange efficiency with use is suppressed.

[0097] There are no particular limitations on the viscosity of the fluid 2 as long as it is within a range generally used in transfer systems, and the viscosity of the fluid 2 may be, for example, 0.1 mPa·s or more and 10 mPa·s or less.

[0098] The heat transfer system 1 may further include a pump 5 for circulating the fluid 2 in a predetermined flow direction.

[0099] <Heat Source> The heat transfer system 1 of the first embodiment can further include a heat source 8 that is provided outside the flow path 3 and provides heat to the fluid 2. The heating means of the heat source 8 is not particularly limited. For example, a direct heat source such as a semiconductor device, an electric heater, an air heater, or a lamp heater, or waste heat recovered from sunlight, an engine, a heat treatment furnace, or the like can be used.

[0100] [Embodiment 2] A heat transfer system according to another embodiment of the present disclosure (hereinafter also referred to as "Embodiment 2") will be described. The heat transfer system according to Embodiment 2 can have the same configuration as the heat transfer system according to Embodiment 1, except for the shape of the porous metal body. The shape of the porous metal body will be described below with reference to Figures 2, 3, and 5. Figure 2 is a view of the region of the heat transfer system 1 according to Embodiment 2, in which the porous metal body 4 is provided, as viewed from above the heat source 8. Figure 3 is a cross-sectional view taken along line III-III in Figure 2. Figure 5 is a cross-sectional view taken along line IV-IV in Figure 2. In Figure 5, the direction of arrow F1 corresponds to a first direction extending from upstream to downstream of the flow path.

[0101] In the heat transfer system of embodiment 2, the angle β between the normal direction of the surface (hereinafter also referred to as the "first contact surface 4a") of the outer surface of the metal porous body 4 in the second cross-sectional area increasing region 4A where the second cross-sectional area S2 of the metal porous body 4 increases and the first direction is greater than or equal to 60° and less than 90°.

[0102] In the heat transfer system of embodiment 2, the flow rate of the fluid increases near the first contact surface 4a. When the flow rate of the fluid increases, a force toward the outside of the porous metal body is applied to the fluid that has penetrated into the pores of the porous metal body, making it easier for the fluid to move out of the porous metal body. As the fluid moves, impurities contained in the fluid also move out of the porous metal body, suppressing the adhesion of impurities to the pores of the porous metal body and suppressing clogging of the porous metal body. Therefore, in the heat transfer system of embodiment 2, the heat exchange efficiency during use is suppressed.

[0103] The percentage of the area of ​​the first contact surface 4a to the area of ​​the surface (hereinafter also referred to as the "second contact surface") that comes into contact with the fluid present outside the metal porous body 4 among all the outer surfaces of the metal porous body 4 may be 30% or more, 50% or more, or may be 100%.

[0104] Of the entire outer surface of the metal porous body 4, the percentage of the area of ​​the first contact surface 4a relative to the area of ​​the second contact surface that comes into contact with the fluid outside the metal porous body 4 may be 80% or more, 90% or more, or even 100%.

[0105] [Embodiment 3] A heat transfer system according to another embodiment of the present disclosure (hereinafter also referred to as "Embodiment 3") will be described with reference to Figures 2, 6, and 7. Figure 2 is a view of a region of a heat transfer system 1 according to Embodiment 3, in which a porous metal body 4 is provided, as viewed from above a heat source 8. Figure 6 is a cross-sectional view taken along line III-III in Figure 2. Figure 7 is a cross-sectional view taken along line IV-IV in Figure 2. In Figure 7, the direction of arrow F1 corresponds to a first direction extending from upstream to downstream of the flow path.

[0106] 7 , the porous metal body 4 includes a main body 4B extending in a first direction, a first end face 4b on the upstream side of the flow path of the main body 4B, and a second end face 4c on the downstream side of the flow path of the main body 4B. In addition to the plurality of pores, the porous metal body 4 has a through hole 13 formed therein that penetrates from the first end face 4b to the second end face 4c. That is, the through hole 13 is defined by the inner wall of the porous metal body 4. The pore diameter of the through hole 13 in a cross section of the porous metal body 4 perpendicular to the first direction is sufficiently larger than the pore diameter of the porous metal body 4 and is also sufficiently larger than the size of impurities contained in the fluid.

[0107] In a cross section of the porous metal body 4 perpendicular to the first direction, if the cross-sectional area of ​​the through hole 13 is defined as a fourth cross-sectional area S4, the fourth cross-sectional area S4 may include a region where the cross-sectional area decreases along the first direction. This increases the flow rate of the fluid in the region where the cross-sectional area of ​​the through hole decreases. When the flow rate of the fluid increases, a force toward the outside of the porous metal body is applied to the fluid that has entered the pores of the porous metal body, making it easier for the fluid to move out of the porous metal body. As the fluid moves, impurities contained in the fluid also move out of the porous metal body, thereby suppressing adhesion of impurities to the pores of the porous metal body and suppressing clogging of the porous metal body. Therefore, in the heat transfer system of embodiment 3, heat exchange efficiency during use is suppressed.

[0108] In the heat transfer system 1 of the third embodiment, in a cross section perpendicular to the first direction of the flow path 3 in which the metal porous body 4 is provided, the entire outer edge of the metal porous body 4 may be in contact with the flow path wall. In this case, the cross-sectional area of ​​the through hole 13 in the cross section perpendicular to the first direction corresponds to the third cross-sectional area S3. Also, in the cross section perpendicular to the first direction of the flow path 3 in which the metal porous body 4 is provided, part of the outer edge of the metal porous body 4 may be in contact with the flow path wall 3a. In this case, the sum of the cross-sectional area of ​​the through hole 13 in the cross section perpendicular to the first direction and the cross-sectional area of ​​the region of the flow path 3 outside the outer edge of the metal porous body 4 corresponds to the third cross-sectional area S3. When there are multiple through holes 13, the cross-sectional area of ​​the through hole 13 refers to the sum of the cross-sectional areas of the multiple through holes 13.

[0109] The cross-sectional area of ​​the through hole in a cross section perpendicular to the first direction is 0.01 mm ２ More than 100 mm ２ It may be less than or equal to 0.015 mm ２ 60mm or more ２ The following is also acceptable.

[0110] The percentage of the minimum value of the cross-sectional area of ​​the through hole relative to the maximum value in a cross section perpendicular to the first direction may be 1% or more and 50% or less.

[0111] 6, the number of through holes is seven, but the number of through holes is not limited to this. The number of through holes may be one, or two or more.

[0112] Other than the above, the heat transfer system of Embodiment 3 can have the same configuration as the heat transfer system of Embodiment 1. The heat transfer system of Embodiment 3 may or may not include a flow path cross-sectional area adjusting member.

[0113] [Fourth Embodiment] The configuration of a heat transfer system according to another embodiment of the present disclosure (hereinafter also referred to as "fourth embodiment") will be described with reference to Figures 8 to 13. As shown in Figure 8, the heat transfer system 1 of the fourth embodiment includes a flow path wall 3a that defines a flow path 3 through which a fluid 2 flows, and a porous metal body 4 that is disposed in the flow path 3 and transfers heat generated in a heat source 8 to the fluid 2 flowing through the flow path 3.

[0114] Fig. 9 is a view of the region where the porous metal body 4 of the heat transfer system 1 of Fig. 8 is provided, viewed from above the heat source 8. Fig. 10 is a view of Fig. 9 as viewed from the back side. Fig. 11 is a cross-sectional view taken along line XI-XI of Fig. 9. Fig. 12 is an example of a cross-sectional view taken along line XII-XII of Fig. 9. Fig. 13 is another example of a cross-sectional view taken along line XII-XII of Fig. 9. In Figs. 12 and 13, the direction of arrow F1 corresponds to a first direction from upstream to downstream of the flow path.

[0115] A heat transfer system 1 according to a fourth embodiment includes a flow path wall 3a defining a flow path 3 through which a fluid 2 flows, and a metal porous body 4 disposed in the flow path 3 and configured to transfer heat generated at a heat source 8 to the fluid 2 flowing through the flow path 3. When viewed along a first direction from upstream to downstream of the flow path 3 in which the metal porous body 4 is disposed, the metal porous body includes a first region having a first width D1 located on the heat source side, and a second region having a width narrower than the first width (hereinafter also referred to as a "second width D2") located on the opposite side of the heat source across the first region. As shown in FIG. 11 , when the flow path 3 is viewed along the first direction from the upstream side, the flow path 3 is occupied by the first region and the second region. As a result, the pressure loss when the fluid 2 passes through the second region is smaller than the pressure loss when the fluid 2 passes through the first region, and the flow velocity of the fluid 2 passing through the second region is greater than the flow velocity of the fluid passing through the first region. When the flow rate of the fluid 2 passing through the second region becomes higher than the flow rate of the fluid passing through the first region, a force toward the outside of the porous metal body 4 is applied to the fluid 2 that has entered the pores in the first region, making it easier for the fluid 2 to move out of the porous metal body 4. As the fluid 2 moves, impurities contained in the fluid 2 also move out of the porous metal body 4, which prevents impurities from adhering to the pores of the porous metal body 4 and prevents clogging of the porous metal body 4. Therefore, in the heat transfer system of embodiment 4, the heat exchange efficiency during use is reduced.

[0116] The percentage (D2 / D1)×100 of the second width D2 (mm) of the second region to the first width D1 (mm) of the first region of the metal porous body 4 may be 20% or more and less than 100%.

[0117] The average pore size and porosity of the pores in the second region of the metal porous body 4 may be the same as the average pore size and porosity of the pores in the first region. In this case, the percentage (D2 / D1)×100 of the second width D2 (mm) of the second region to the first width D1 (mm) of the first region may be 20% or more and less than 100%.

[0118] The average pore size and porosity of the pores in the second region of the metal porous body 4 may be larger than those in the first region. This further reduces pressure loss when the fluid passes through the second region, increases the flow rate of the fluid passing through the second region, and suppresses clogging by impurities.

[0119] When the average pore size and porosity of the pores in the second region are larger than the average pore size and porosity of the pores in the first region, the percentage (D2 / D1) x 100 of the second width D2 (mm) of the second region to the first width D1 (mm) of the first region may be 30% or more and less than 100%.

[0120] The average pore size of the pores in the first region and the average pore size of the pores in the second region are measured by the mercury intrusion method described in embodiment 1.

[0121] The heat transfer system of embodiment 4 can have the same configuration as the heat transfer system of embodiment 1, except for the shape of the porous metal body. The heat transfer system of embodiment 4 may or may not include a flow path cross-sectional area adjusting member.

[0122] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0123] [Study 1] <Fabrication of heat transfer system> A heat transfer system 1 having the configuration shown in Figure 1 was fabricated, and the relationship between the structure inside the flow path 3 heated by the heat source 8 and the heat transfer efficiency was confirmed. All samples had the same structure except for the structure inside the flow path 3 heated by the heat source 8.

[0124] When viewed from above the heat source 8, the flow path 3 heated by the heat source 8 is rectangular, with a length along the first direction (the length indicated by B2 in FIG. 2 ) of 80 mm and a length along a direction perpendicular to the first direction (the length indicated by B1 in FIG. 2 ) of 80 mm. When viewed from the upstream side, the length along the direction perpendicular to the first direction (the length indicated by B3 in FIG. 3 ) of the flow path 3 is 10 mm. The material of the flow path wall 3a is polytetrafluoroethylene. The cross sections perpendicular to the first direction of the flow path upstream of the flow path 3 heated by the heat source 8 (hereinafter also referred to as the "upstream flow path 3c") and the flow path downstream of the flow path heated by the heating unit (hereinafter also referred to as the "downstream flow path 3d") are each elliptical with a major axis of 10 mm and a minor axis of 8 mm.

[0125] An aluminum metal plate 11 was placed between the heat source 8 and the flow path wall 3a. The main surface of the metal plate 11 was a rectangle measuring 80 mm x 80 mm, and was placed so as to cover the outer wall of the flow path wall 3a on the heat source 8 side. The surface of the heat source 8 that was in contact with the metal plate 11 was a rectangle measuring 60 mm x 60 mm.

[0126] <<Samples 1-1 to 1-3>> In the heat transfer systems of Samples 1-1 to 1-3, the structure inside the flow path 3 was as shown in Fig. 3 and Fig. 4. The metal porous body was sheet-shaped, with a rectangular main surface measuring 80 mm x 80 mm and a thickness of 5 mm. The metal porous body was made of pure copper, with pore diameters of 15 μm to 250 μm, a porosity of 70%, and a transmittance of 1 × 10 －１２ m ２ The metal porous body and the flow path wall were molded as a single unit.

[0127] A flow channel cross-sectional area adjusting member 12 was provided on the downstream side of the flow channel 3, on the flow channel wall 3a opposite the flow channel wall 3a on which the metal porous body 4 was provided. The angle α (angle α shown in FIG. 3 ) formed between the flow channel wall 3a and the upstream surface of the flow channel cross-sectional area adjusting member 12 in the cross section of each sample along the thickness direction and the first direction of the flow channel 3 is shown in the “Angle α (°)” column of Table 1. The percentage (L3 / L1)×100 of the length L3 of the region where the third cross-sectional area S3 along the first direction decreases relative to the length L1 of the metal porous body along the first direction for each sample is shown in the “L3 / L1 (%)” column of Table 1. The flow channels of the heat transfer systems of Samples 1-1 to 1-3 include a region where the third cross-sectional area S3 decreases.

[0128] The heat transfer system of Sample 2 had the same structure as Sample 1, except that the metal porous body and the flow path cross-sectional area adjusting member were not provided in the flow path (see FIG. 14 ). The flow path of the heat transfer system of Sample 2 did not include a region where the third cross-sectional area S3 decreases.

[0129] <<Sample 3>> The heat transfer system of Sample 3 had the same structure as Sample 1 except that a metal porous body that was thicker than Sample 1 was used, the flow path was occupied by the metal porous body, and no flow path cross-sectional area adjusting member was provided (see FIG. 15 ). The flow path of the heat transfer system of Sample 3 did not include a region where the third cross-sectional area S3 decreases.

[0130] The heat transfer system of Sample 4 had the same structure as Sample 1, except that it did not include a flow path cross-sectional area adjusting member (see FIG. 16). The flow path of the heat transfer system of Sample 4 did not include a region where the third cross-sectional area S3 was reduced.

[0131] Sample 5: The heat transfer system of Sample 5 had the same structure as Sample 1 except for the shape of the porous metal body (see FIG. 5). The porous metal body of Sample 5 included a region on the upstream side of the flow path where the cross-sectional area (corresponding to the second cross-sectional area S2) in a cross section perpendicular to the first direction increased. The flow path of the heat transfer system of Sample 5 included a region where the third cross-sectional area S3 decreased.

[0132] The heat transfer system of Sample 6 had the same structure as Sample 1, except that the angle α of the flow path cross-sectional area adjusting member was 45° (see FIG. 4). The flow path of the heat transfer system of Sample 6 included a region where the third cross-sectional area S3 decreased.

[0133] <Heat Exchange Efficiency Evaluation Test of Heat Transfer System> A heat exchange efficiency evaluation test of the heat transfer system of each sample was carried out using industrial water with an alkalinity of 400 mg / L as fluid 2. The total alkalinity was determined by Gran's plot method (Proceedings of the Japan Society of Civil Engineers, No. 685 / VII-20, (2001), 157-164).

[0134] While the pump 5 provided a driving force to the fluid 2, the heat source 8 was operated to provide heat to the fluid 2, driving the heat transfer system 1 for each sample. The flow rate of the fluid 2 when flowing into the flow path 3 heated by the heat source 8 was 0.15 L / min. In each sample's heat transfer system, the heat source 8 was set to a power of 2 W, and the temperature T1 of the metal plate 11 1 hour after the start of heating and the temperature T2 of the metal plate 11 100 hours after heating were measured using a thermocouple. For each sample, the percentage difference between T2 and T1 relative to T1 was calculated as {(T2 - T1) / T1} x 100 (hereinafter also referred to as "rate of change"). The results are shown in the "Rate of Change (%)" column in Table 1. If T2 is 53°C or less and the rate of change is 10% or less, the heat transfer system is judged to have excellent heat exchange efficiency and to have suppressed deterioration in heat exchange efficiency with use.

[0135]

[0136] [Discussion] The heat transfer systems of Samples 1-1 to 1-3, Sample 5, and Sample 6 correspond to examples. These heat transfer systems have T2 of 53°C or less and a rate of change of 10% or less, and have excellent heat exchange efficiency while suppressing the decrease in heat exchange efficiency with use.

[0137] The heat transfer system of Sample 2 corresponds to a comparative example. The heat transfer system of Sample 2 had a T2 of 59° C., and was poor in heat exchange efficiency.

[0138] The heat transfer systems of Samples 3 and 4 correspond to comparative examples. The heat transfer systems of Samples 3 and 4 had T2 exceeding 53°C and a rate of change exceeding 10%, indicating poor heat exchange efficiency, and the heat exchange efficiency also decreased with use.

[0139] [Study 2] <Fabrication of heat transfer system> A heat transfer system 1 having the configuration shown in Fig. 8 was fabricated, and the relationship between the structure inside the flow path 3 heated by the heat source 8 and the heat transfer efficiency was confirmed. All samples had the same structure except for the structure inside the flow path 3 heated by the heat source 8.

[0140] When viewed from above the heat source 8, the flow path 3 heated by the heat source 8 is a rectangle having a length along the first direction (length indicated by B2 in FIG. 9 ) of 80 mm and a length along a direction perpendicular to the first direction (length indicated by B1 in FIG. 9 ) of 80 mm. When viewed from the upstream side, the length along the direction perpendicular to the first direction of the flow path 3 (length indicated by B3 in FIG. 12 ) is 10 mm. The material of the flow path wall 3 a is polytetrafluoroethylene.

[0141] An aluminum metal plate 11 was placed between the heat source 8 and the flow path wall 3a. The main surface of the metal plate 11 was a rectangle measuring 80 mm x 80 mm, and was placed so as to cover the outer wall of the flow path wall 3a on the heat source 8 side. The surface of the heat source 8 that was in contact with the metal plate 11 was a rectangle measuring 60 mm x 60 mm.

[0142] <<Sample 2-1>> In the heat transfer system of Sample 2-1, the structure inside the flow path was the structure shown in Fig. 17. The metal porous body was in the form of a sheet, with the main surface being a rectangle measuring 80 mm x 80 mm and a thickness of 10 mm. The metal porous body was made of pure copper, with pore diameters of 15 μm to 250 μm, a porosity of 70%, and a transmittance of 1 x 10 －１２ m ２ The metal porous body and the flow path wall were molded as a single unit.

[0143] The metal porous body of sample 2-1 does not include a first region having a first width located on the heat source side and a second region having a width narrower than the first width and located on the opposite side of the heat source across the first region.

[0144] <<Sample 2-2, Sample 2-3>> The heat transfer systems of Sample 2-2 and Sample 2-3 had the same configuration as Sample 2-1, except that the shape of the porous metal body was the shape shown in FIG. 12. Sample 2-2 and Sample 2-3 included a first region having a first width D1 located on the heat source side, and a second region located on the opposite side of the heat source across the first region, having a second width D2 narrower than the first width. Table 2 shows the first width D1, second width D2, and percentage (D2 / D1) x 100 of the porous metal bodies of Sample 2-2 and Sample 2-3. In Sample 2-2 and Sample 2-3, the thickness of the portion not corresponding to the second width D2 (thickness indicated by D5 in FIG. 12) was 5 mm.

[0145] <Evaluation test of heat exchange efficiency of heat transfer system> A test to evaluate the heat exchange efficiency of the heat transfer system of each sample was carried out. The specific test method and evaluation criteria were the same as those in Study 1. The results are shown in Table 2.

[0146]

[0147] [Discussion] The heat transfer system of Sample 2-1 corresponds to a comparative example. The heat transfer system of Sample 2-1 had a T2 exceeding 53°C and a rate of change exceeding 10%, which meant that the heat exchange efficiency was poor and also decreased with use.

[0148] The heat transfer systems of Samples 2-2 and 2-3 correspond to examples. The heat transfer systems of Samples 2-2 and 2-3 have a T2 of 53°C or less and a rate of change of 10% or less, and have excellent heat exchange efficiency, while suppressing a decrease in heat exchange efficiency with use.

[0149] Although the embodiments and examples of the present disclosure have been described above, it is intended from the beginning that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways. The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments and examples, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims.

[0150] 1 Heat transfer system, 2 Fluid, 3 Flow path, 3a Flow path wall, 3c Upstream flow path, 3d Downstream flow path, 4 Metal porous body, 4A Second cross-sectional area increasing region, 4B Main body, 4a First contact surface, 4b First end surface, 4c Second end surface, 5 Pump, 6 Heat receiving region, 8 Heat source, 11 Metal plate, 12 Flow path cross-sectional area adjusting member, 13 Through hole.

Claims

1. A heat transfer system that transfers heat generated in a heat source by using a fluid, comprising: a flow path wall that defines a flow path through which the fluid flows; and a porous metal body that is disposed in the flow path and transfers heat generated in the heat source to the fluid flowing through the flow path, wherein, in a cross section of the flow path in which the porous metal body is disposed, perpendicular to a first direction from upstream to downstream of the flow path, when a cross-sectional area of ​​the flow path in which the porous metal body is disposed is a first cross-sectional area S1, a cross-sectional area of ​​the porous metal body is a second cross-sectional area S2, and an area S1-S2 obtained by subtracting the second cross-sectional area S2 from the first cross-sectional area S1 is a third cross-sectional area S3, the flow path includes a region where the third cross-sectional area S3 decreases along the first direction, the porous metal body is made of a metal having a plurality of pores formed therein, and at least some of the pores are open pores, the metal being selected from a first group consisting of aluminum, magnesium, copper, silver and gold, an alloy made of two or more metal elements selected from the first group, a metal in a composite state of two or more metal elements selected from the first group; an alloy consisting of one or more metal elements selected from the first group and one or more elements selected from a second group consisting of iron, cobalt, chromium, nickel, manganese, tin, zinc, silicon, phosphorus, carbon, boron, scandium, molybdenum, tungsten, and titanium; or a metal in a composite state of one or more metal elements selected from the first group and one or more elements selected from the second group, wherein the pore size of the pores of the metal porous body is 10 μm or more and 420 μm or less, the porosity of the metal porous body is 60% or more and 85% or less, and the transmittance of the metal porous body is 0.6×10 －１２ m ２ That's it for the heat transfer system.

2. The heat transfer system of claim 1, wherein a length L3 of the region in which the third cross-sectional area S3 decreases along the first direction is 30% or more of a length L1 of the metal porous body along the first direction.

3. The heat transfer system according to claim 1 or 2, wherein the flow path wall includes a flow path cross-sectional area adjusting member disposed in the flow path and configured to reduce the third cross-sectional area S3.

4. A heat transfer system as described in claim 1 or claim 2, wherein the metal porous body includes a main body portion extending in the first direction, a first end face of the main body portion on the upstream side of the flow path, and a second end face of the main body portion on the downstream side of the flow path, and the metal porous body has through holes formed therein that extend from the first end face to the second end face, separate from the plurality of pores.

5. A heat transfer system as described in claim 4, wherein, in a cross-section perpendicular to the first direction of the metal porous body, when the cross-sectional area of ​​the through hole is a fourth cross-sectional area S4, the metal porous body includes a region in which the fourth cross-sectional area S4 decreases along the first direction, and in a cross-section perpendicular to the first direction of the flow path in which the metal porous body is provided, all of the outer edges of the metal porous body are in contact with the flow path wall.

6. A heat transfer system as described in any one of claims 1 to 5, wherein the metal porous body includes a main body portion extending in the first direction, a first end face of the main body portion on the upstream side of the flow path, and a second end face of the main body portion on the downstream side of the flow path, and the heat transfer system includes a shielding member provided on the first end face.

7. A heat transfer system according to any one of claims 1 to 6, wherein the thermal conductivity of the metal is 100 W / m·K or more.

8. The transmittance of the porous metal body is 0.8×10 －１２ m ２ The heat transfer system according to any one of claims 1 to 7, wherein:

9. A heat transfer system according to any one of claims 1 to 8, wherein the open porosity of the pores of the metal porous body is 60% or more.

10. A heat transfer system for transferring heat generated in a heat source by using a fluid, comprising: a flow path wall defining a flow path through which the fluid flows; and a porous metal body disposed in the flow path and transferring heat generated in the heat source to the fluid flowing through the flow path, wherein when viewed along a first direction from upstream to downstream of the flow path in which the porous metal body is disposed, the porous metal body includes a first region having a first width located on the heat source side, and a second region having a width narrower than the first width and disposed on the opposite side of the heat source across the first region, the flow path being occupied by the first region and the second region, the porous metal body being made of a metal having a plurality of pores formed therein, at least some of the pores being open pores, the metal being selected from a first group consisting of aluminum, magnesium, copper, silver and gold, an alloy consisting of two or more metal elements selected from the first group, a metal in a composite state of two or more metal elements selected from the first group, an alloy consisting of one or more metal elements selected from the first group and one or more elements selected from a second group consisting of iron, cobalt, chromium, nickel, manganese, tin, zinc, silicon, phosphorus, carbon, boron, scandium, molybdenum, tungsten, and titanium, or a metal in a composite state consisting of one or more metal elements selected from the first group and one or more elements selected from the second group, wherein the pore size of the pores of the metal porous body is 10 μm or more and 420 μm or less, the porosity of the metal porous body is 60% or more and 85% or less, and the transmittance of the metal porous body is 0.6×10 －１２ m ２ That's it for the heat transfer system.

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