Device, heat exchanger, and evaporator

Abstract

A device according to the present disclosure comprises a heating element and a heat exchanger having an evaporator that absorbs heat from the heating element and causes a liquid-phase working fluid to evaporate, the heat exchanger causing gas-phase working fluid flowing out from the evaporator to condense and circulate to the evaporator, wherein: the evaporator comprises an evaporation body that guides the liquid-phase working fluid to an outer surface thereof by capillary force and causes the working fluid to evaporate, and an accommodating body that accommodates the evaporation body and has an inner surface facing the outer surface; on one of the outer surface and the inner surface, a plurality of first protruding portions protruding toward the other of the outer surface and the inner surface are formed at predetermined intervals; on the other of the outer surface and the inner surface, second protruding portions protruding toward said one of the outer surface and the inner surface are formed between two mutually adjacent first protruding portions; and the second protruding portions include a main portion protruding toward said one of the outer surface and the inner surface from the other of the outer surface and the inner surface and having a tip end in contact with the one of the outer surface and the inner surface, and sub-portions protruding from the main portion in a direction intersecting the main portion and having tip ends in contact with the first protruding portions.

Description

Apparatus, heat exchanger, and evaporator

[0001] This disclosure relates to apparatus, heat exchangers, and evaporators.

[0002] Patent Document 1 discloses a loop-type heat pipe in which an evaporator is formed in a flat plate shape and comprises a wick having a vertical groove formed on the heat receiving plate surface to guide the gas phase working fluid and a liquid groove formed on the opposing plate surface to guide the liquid phase working fluid, and the wick evaporates the liquid phase working fluid in the liquid groove into the gas phase while moving it toward the vertical groove by capillary force.

[0003] Patent Document 2 and Non-Patent Document 1 disclose a loop-type heat pipe having a wick with a plurality of steam grooves on its outer circumferential surface and an evaporator body that houses the wick, wherein when the heating element generates the most heat during the operation of the electronic device, a liquid-phase working fluid seeps out into the corners formed by the side surface of the steam grooves in the wick and the inner circumferential surface of the evaporator body.

[0004] Patent Document 3 discloses an apparatus comprising a heating element and a heat exchanger that condenses the gaseous working fluid flowing out of the evaporator and recirculates it back into the evaporator, wherein the evaporator comprises an evaporator that evaporates the working fluid flowing in along a predetermined direction, and a housing that houses the evaporator and has an inner surface facing its outer surface. The evaporator has an evaporator projection that protrudes toward the housing on its outer surface and is formed along this direction, and the housing has a housing projection that protrudes toward the evaporator on its inner surface and engages with the evaporator projection, and the evaporator projection and the housing projection are spaced apart from the opposing inner or outer surface and form a steam groove that guides the evaporated working fluid.

[0005] Japanese Patent Publication No. 2016-211767, Japanese Patent Publication No. 2018-170317, Japanese Patent Publication No. 2021-99169

[0006] Kimihide Odagiri, and Hosei Nagano, “Investigation on Liquid-Vapor Interface Behavior in Capillary Evaporator for High Heat Flux Loop Heat Pipe,” International Journal of Thermal Sciences, Vol. 140, pp. 530-538 (2019).

[0007] Incidentally, in recent years, as electronic devices and other equipment have become smaller and more high-performance, the heat density in these devices has increased. Therefore, there is a need to efficiently remove the high heat flux from the heat-generating elements installed in these devices. Accordingly, the technology disclosed herein aims to provide devices with improved heat exchange efficiency.

[0008] To this end, the technology disclosed herein is an apparatus comprising a heating element and a heat exchanger having an evaporator that absorbs heat from the heating element to evaporate a liquid-phase working fluid, and condenses the gaseous working fluid discharged from the evaporator and recirculates it to the evaporator, wherein the evaporator comprises an evaporator that guides a liquid-phase working fluid to its outer surface by capillary force and evaporates it, and a housing that houses the evaporator and has an inner surface facing the outer surface, wherein a plurality of first protrusions are formed at predetermined intervals on one of the outer surface and the inner surface, projecting toward the other of the outer surface and the inner surface, and a second protrusion is formed on the other, projecting toward the one between two adjacent first protrusions, and the second protrusion includes a main part that projects toward the one from the other and whose tip contacts the one, and a sub-part that projects toward the main part in a direction intersecting the main part and whose tip contacts the first protrusion.

[0009] According to this disclosure, it is possible to provide devices that improve heat exchange efficiency.

[0010] This is a schematic diagram showing a loop-type heat pipe according to this embodiment. (a) shows a cross-sectional view of the evaporator according to this embodiment in the axial direction, and (b) is a cross-sectional view taken from the IIb-IIb plane of (a). This is an enlarged view of III in Figure 2(b). This is an enlarged view of IV in Figure 3. (a) and (b) are diagrams to explain Modification 1. (a) to (c) are diagrams to explain Modification 2. (a) and (b) are diagrams to explain Modification 3. (a) to (c) are diagrams to explain Modification 4. This is a diagram to explain Modification 5. This is a diagram to explain Modification 6. (a) and (b) are diagrams to explain Modification 7. This is a perspective view showing an overview of the measurement experiment. This is a diagram showing the schematic configuration of the measurement sample. This is a diagram showing the measurement results for each measurement sample, with the horizontal axis representing the heat flux (W / cm). ２ The diagram shows the heating element temperature (°C) on the vertical axis. This is a diagram illustrating a mobile phone equipped with a loop-type heat pipe.

[0011] The embodiment will be described in detail below with reference to the attached drawings. <Configuration of Loop-Type Heat Pipe 100> Figure 1 is a schematic diagram showing the loop-type heat pipe 100 according to this embodiment. First, the configuration of the loop-type heat pipe 100 to which this embodiment is applied will be described with reference to Figure 1. The loop-type heat pipe 100 to which this embodiment is applied is configured to circulate a working fluid in order to cool a heat-generating element 200, such as a computer CPU, which is installed inside the enclosure of an electronic device, without supplying power from the outside.

[0012] More specifically, a loop-type heat pipe 100, an example of a cooling element, includes an evaporator 101 that evaporates the working fluid to cool the heat-generating element 200 by utilizing the latent heat of vaporization of the working fluid, and a condenser 107 that liquefies the working fluid vaporized in the evaporator 101 by releasing heat. The loop-type heat pipe 100 also includes a vapor line 105 that sends the working fluid vaporized in the evaporator 101 to the condenser 107, and a liquid line 109 that sends the working fluid liquefied in the condenser 107 back to the evaporator 101. The loop-type heat pipe 100 is filled with a working fluid that undergoes a phase change between the liquid and gas phases. Examples of working fluids used include water, ethanol, acetone, and ammonia.

[0013] <Operation of Loop-Type Heat Pipe 100> Next, the operation within the loop-type heat pipe 100 will be explained with reference to Figure 1. The heat generated in the heating element 200 is transferred to the evaporator 101 (see arrow C1). The working fluid that has absorbed heat in the evaporator 101 vaporizes and is sent to the condenser 107 through the steam pipe 105 (see arrow A1) (see arrow A2). The working fluid sent to the condenser 107 releases heat (see arrow C2) and liquefies. The liquefied working fluid is then sent back to the evaporator 101 through the liquid pipe 109 (see arrow A3) (see arrow A4).

[0014] <Configuration of Evaporator 101> Figure 2(a) shows a cross-sectional view of the evaporator 101 in the axial direction according to this embodiment, and Figure 2(b) is a cross-sectional view taken from the plane IIb-IIb of Figure 2(a).

[0015] Next, with reference to Figures 1 and 2, the configuration of the evaporator 101 to which this embodiment is applied will be described. As shown in Figure 2(a), the evaporator 101 has an evaporator body 110 provided in an electronic device (not shown) and configured to transfer heat from a heating element 200, and a liquid reservoir 120 connected to the evaporator body 110 and containing liquid and gaseous working fluids inside. The evaporator 101 also has a wick 130 inserted into the evaporator body 110, and an introduction pipe (bayonet pipe) 170, one end of which is positioned inside the wick 130 and the other end of which is connected to a liquid pipe 109 to introduce liquid working fluid into the wick 130.

[0016] The evaporator body 110 is made of a hollow tubular metal, with one end connected to the steam pipe 105 and the other end connected to the liquid reservoir 120. The liquid reservoir 120 has a hollow tubular member that is continuous inside with the evaporator body 110. In the illustrated example, the liquid reservoir 120 is provided with an insertion port 129 into which the liquid pipe 109 is inserted.

[0017] The wick 130 is a component made of porous metal. The wick 130 generates capillary force in the working fluid, thereby moving the working fluid.

[0018] Furthermore, the wick 130 is a hollow tubular member with one end closed and the other end open. The wick 130 is provided in contact with the inner surface (inner surface) 111 of the evaporator body 110. When assembling the evaporator 101, for example, the wick 130 is inserted into the evaporator body 110 before connecting the evaporator body 110 and the liquid reservoir 120.

[0019] Wick 130 has so-called macropores with a pore diameter larger than 50 nm. Specifically, the effective pore diameter (or average pore diameter) of Wick 130 is, for example, 0.1 μm to 25 μm. This average pore diameter was measured by the bubble point method, but it may also be measured by other methods.

[0020] It should be noted that the wick 130 is not limited to porous metal, and may be formed of porous resin such as polytetrafluoroethylene (PTFE), porous ceramic, porous glass, porous fibers, or the like. Also, the porosity of the wick 130 is 25% to 70%. Furthermore, when a material with low thermal conductivity is used for the wick 130, heat leakage from the evaporator body 110 to the liquid reservoir 120 can be reduced. In the case where it is desired to further reduce heat leakage, it is generally preferable to use a non-metal, which has lower thermal conductivity than a metal.

[0021] Also, the outer diameter of the wick 130 is, for example, in a range of 3 mm to 100 mm, preferably in a range of 4 mm to 80 mm, and more preferably in a range of 6 mm to 60 mm. It should be noted that although the wick 130 in the illustrated example is a cylindrical member, the shape of the wick 130 may be another shape such as a plate shape (rectangular parallelepiped) (described later).

[0022] The introduction pipe 170 is a hollow tubular member provided inside the wick 130. In the illustrated example, the evaporator body 110, the wick 130, and the introduction pipe 170 are provided coaxially.

[0023] <Operation of Evaporator 101> Next, the operation inside the evaporator 101 will be described with reference to FIG. 2. First, the liquid-phase working fluid sent to the evaporator 101 through the liquid pipe 109 flows into the evaporator body 110 via the introduction pipe 170 (see arrow B1).

[0024] The working fluid that has flowed into the evaporator main body 110 permeates the wick 130 inside the evaporator main body 110. A part of the working fluid that has flowed into the evaporator main body 110 is supplied to the liquid reservoir 120 (see arrow B3) and retained in the liquid reservoir 120. The working fluid that has permeated the wick 130 moves toward the outer peripheral surface (outer surface) 131 by the capillary force of the wick 130 (see arrow B2), and is heated by the heat of the heating element 200 to vaporize. This vaporized working fluid moves toward the steam pipe 105 side while passing through a gap (described later) between the evaporator main body 110 and the wick 130 (see arrow B4). Further, as the working fluid in the evaporator main body 110 permeates the wick 130, the working fluid in the liquid reservoir 120 is supplied to the evaporator main body 110.

[0025] Here, on the outer peripheral surface 131 of the wick 130, as the vaporized working fluid moves toward the steam pipe 105 side, the liquid-phase working fluid that has permeated the wick 130 moves toward the outer peripheral surface 131 of the wick 130. Then, this liquid-phase working fluid vaporizes and moves to the steam pipe 105. In this manner, the above cycle is repeated without interruption of the flow of the working fluid on the outer peripheral surface 131 of the wick 130. Then, the heat generated in the heating element 200 is transported from the evaporator 101 to the condenser 107 (see FIG. 1) as described above.

[0026] In the following description, the circumferential direction of the wick 130 may be simply referred to as the circumferential direction. Further, the axial direction of the wick 130 may be simply referred to as the axial direction. This axial direction is a direction along the flow direction in which the liquid-phase working fluid flows in through the introduction pipe 170 (see arrow B1), or the flow direction in which the gas-phase working fluid flows out through the steam pipe 105 (see arrow A1). Further, the radial direction of the wick 130 may be simply referred to as the radial direction.

[0027] <Evaporator Main Body 110 and Wick 130> FIG. 3 is an enlarged view of the area within III in FIG. 2(b). In other words, FIG. 3 is a cross-sectional view taken along a plane orthogonal to the axial direction. FIG. 4 is an enlarged view of the area within IV in FIG. 3. Next, with reference to FIG. 2 to FIG. 4, the evaporator main body 110 and the wick 130 to which the present embodiment is applied will be described in detail.

[0028] First, as shown in Figure 2(b), the outer circumferential surface of the evaporator body 110 that receives heat from the heating element 200 (see Figure 1) becomes the heat receiving surface 119. The evaporator body 110 has an inner circumferential surface 111 that faces the wick 130. The wick 130 also has an outer circumferential surface 131 that faces the evaporator body 110. More specifically, the inner circumferential surface 111 of the evaporator body 110 faces the outer circumferential surface 131 of the wick 130. The outer circumferential surface 131 of the wick 130 is formed to have the same axial length as the inner circumferential surface 111 of the evaporator body 110 and is supported by the inner circumferential surface 111 of the evaporator body 110.

[0029] Here, as shown in Figure 2(b), the evaporator body 110 has a container recess 113 on its inner circumferential surface 111. This container recess 113 is a groove that extends in the axial direction. The container recess 113 is formed along the entire axial direction of the inner circumferential surface 111 of the evaporator body 110, but it may also be provided only in a part of the axial direction. Furthermore, multiple container recesses 113 are provided on the inner circumferential surface 111 of the evaporator body 110. To explain further, multiple container recesses 113 are provided at predetermined intervals in the circumferential direction.

[0030] Here, as shown in Figure 3, the evaporator body 110 can be understood as having a configuration in which a container protrusion 112 is formed on the inner circumferential surface 111, which is a portion sandwiched between the container recesses 113. This container protrusion 112 is formed along the container recesses 113. In other words, the container protrusion 112 is a projection that extends in the axial direction.

[0031] Furthermore, as shown in Figure 3, the container protrusion 112 and the container recess 113 each have a substantially square cross-section. The inner circumferential surface 111 of the evaporator body 110 is formed by the container side surface 114, which is the side surface of the container protrusion 112 and is aligned radially, the container top surface 116, which is the top surface of the container protrusion 112 and is aligned circumferentially, and the container bottom surface 118, which is the bottom surface of the container recess 113 and is aligned circumferentially.

[0032] The container protrusions 112 project from the container bottom surface 118 toward the outer circumferential surface 131 of the wick 130. In other words, the container protrusions 112 project in one direction in the radial direction. Multiple such container protrusions 112 are formed at intervals in the circumferential direction intersecting the axial and radial directions. That is, multiple container protrusions 112 are provided in the circumferential direction via container recesses 113. The container top surface 116, which is the tip of the container protrusion 112, is in contact with the outer circumferential surface 131 of the wick 130. The width dimension W2 of the container protrusion 112 is equal to the width dimension W1 of the container recess 113. The container protrusion 112 is formed with a width dimension W2 over the entire axial direction.

[0033] As shown in Figure 2(b), the outer circumferential surface 131 of the wick 130 has a wick base surface 133 which is a surface that follows the circumferential direction. In addition, multiple wick protrusions 132 are formed on the outer circumferential surface 131 of the wick 130, protruding from the wick base surface 133.

[0034] As shown in Figure 3, the wick protrusions 132 project toward the heat receiving surface 119 of the evaporator body 110 between two adjacent container protrusions 112. Furthermore, multiple wick protrusions 132 are provided at predetermined intervals in the circumferential direction. The wick protrusions 132 and container protrusions 112 can be considered as fins. The wick protrusions 132 and wick base surface 133 are formed along the entire axial length of the outer circumferential surface 131 of the wick 130.

[0035] As shown in Figure 3, the wick projection 132 is formed with a cross shape in its axial orthogonal cross-section. The wick projection 132 includes a main portion 140 extending radially from the wick base surface 133 toward the container bottom surface 118, and sub-parts 150 (150A, 150B) extending circumferentially from the main portion 140 toward the container projection 112.

[0036] As shown in Figure 4, the main portion 140 is formed in a rectangular shape in cross-section and extends from the wick base surface 133 toward the container bottom surface 118. More specifically, the main portion 140 extends radially along the protruding direction of the container protrusion 112. This main portion 140 has a pair of main portion side surfaces 143 (143a, 143b) which are the sides of the main portion 140 and extend radially, and a main portion tip surface 141 which is the tip of the main portion 140 and extends circumferentially.

[0037] The sub-parts 150 (150A, 150B) are each formed in a rectangular shape in cross-section. The sub-parts 150 (150A, 150B) are formed on the main part side surfaces 143 (143a, 143b), respectively, and extend toward two adjacent container protrusions 112. More specifically, sub-part 150A extends from the main part side surface 143a toward the container side surface 114 of the container protrusion 112 opposite to the main part side surface 143a. Similarly, sub-part 150B extends from the main part side surface 143b toward the container side surface 114 of the container protrusion 112 opposite to the main part side surface 143b. These sub-parts 150 (150A, 150B) extend circumferentially from approximately the midpoint in the radial direction of the main part 140. The sub-part 150 (150A, 150B) has a pair of sub-part side surfaces 153 (153a, 153b) that are the sides of the sub-part 150 and extend in the circumferential direction, and a sub-part tip surface 151 that is the tip of the sub-part 150 and extends in the radial direction.

[0038] Now, such an evaporator 101 has a steam channel 160, which is a passage for the vaporized working fluid. This steam channel 160 is partitioned by two adjacent container protrusions 112 and the outer circumferential surface 131 of the wick 130. More specifically, the steam channel 160 is formed when the container top surface 116 of the container protrusion 112 and the wick base surface 133 are in close contact, causing the wick base surface 133 to close the container recess 113. Thus, the steam channel 160 is partitioned by the container side surface 114, the container bottom surface 118, and the wick base surface 133. With the wick protrusions 132 positioned in this steam channel 160, the steam channel 160 is further partitioned into four spaces. In other words, the main side surface 143 (143a, 143b) and the secondary side surface 153 (153a, 153b) are exposed to the steam channel 160.

[0039] As shown in Figure 3, the thickness dimension (width dimension) T1 of the main part 140 is the same throughout the radial direction. Similarly, the thickness dimension T2 of the sub-parts 150 (150A, 150B) is the same throughout the circumferential direction. These thickness dimensions T1 and T2 are the same (T1 = T2), and are set to be approximately 1 / 3 the size of the width dimension W1 of the container recess 113 (T1 = W1 × 1 / 3, T2 = W1 × 1 / 3). In other words, the relationship between the thickness dimensions T1 and T2 of the wick protrusion 132 and the width dimension W1 of the container recess 113 is T1 + T2 × 2 = W1.

[0040] Furthermore, as shown in Figure 3, the top surface 116 of the container protrusion 112 is in contact with the wick base surface 133. The contact area is A Ｗ２ The main tip surface 141 of the wick projection 132 is in contact with the bottom surface 118 of the container. The contact area is A Ｔ１ Furthermore, the tip surfaces 151 of the sub-parts 150 (150A, 150B) are in contact with the opposing container sides 114. The contact area of ​​each is A Ｔ２ These contact interfaces (contact areas) function as evaporation surfaces that promote the vaporization of the working fluid. In the following description, the "contact interface between the container top surface 116 of the container protrusion 112 and the wick base surface 133" will be appropriately referred to simply as the "contact interface of the container top surface 116". Also, the "contact interface between the main tip surface 141 of the steam groove 160 and the container bottom surface 118, and the contact interfaces between the two sub-tip surfaces 151 and the container side surface 114" will be appropriately referred to collectively as the "contact interface of the wick protrusion 132".

[0041] Here, we will explain the area of ​​the contact interface of the container top surface 116 and the contact interface of the wick protrusion 132. First, as mentioned above, the relationship between the thickness dimensions T1 and T2 of the wick protrusion 132 and the width dimension W1 of the container recess 113 is T1 + T2 × 2 = W1. From this, as shown in Figure 3, the contact area of ​​the contact interface of the "wick protrusion 132" is A Ｔ１ +A Ｔ２ ×2 = A Ｗ１ It is set up to satisfy the relationship.

[0042] With such a configuration, the contact area at the plurality of "contact interfaces of the container top surface 116" (A Ｗ２ ) accounts for 50% of the area of the heat receiving surface 119 in terms of area ratio. On the other hand, the contact area of the plurality of "contact interfaces of the wick convex portions 132" (A Ｔ１ +A Ｔ２ ×2) accounts for 50% of the area of the heat receiving surface 119 in terms of area ratio. That is, the total area of the contact interfaces between the inner peripheral surface 110 of the evaporator body 110 and the outer peripheral surface 131 of the wick 130 accounts for 100% of the area of the heat receiving surface 119 in terms of ratio. Hereinafter, "the ratio of the area of the contact interface to the area of the heat receiving surface 119" is simply referred to as "contact area ratio" as appropriate.

[0043] Now, as shown in FIG. 4, the vapor groove 160 is partitioned into four spaces (see the first space R1, the second space R2, the third space R3, and the fourth space R4) by the wick convex portions 132, and each space has four corners respectively. Here, a portion inside the vapor groove 160 where the container side surface 114 of the evaporator body 110 intersects the wick base surface 133 of the wick 130 is defined as a first corner Cn1. Further, a portion inside the vapor groove 160 where the container bottom surface 118 of the evaporator body 110 intersects the main portion side surfaces 143 (143a, 143b) of the wick 130 is defined as a second corner Cn2. Further, a portion inside the vapor groove 160 where the container side surface 114 of the evaporator body 110 intersects the sub portion side surfaces 153 (153a, 153b) of the wick 130 is defined as a third corner Cn3.

[0044] In addition, as shown in FIG. 4, for each single vapor groove 160, there are two first corners Cn1 at positions spaced apart in the circumferential direction. Further, for each single vapor groove 160, there are two second corners Cn2 at adjacent positions sandwiching the main portion 140 in the circumferential direction. Further, for each single vapor groove 160, two third corners Cn3 are formed at adjacent positions sandwiching the sub portion 150 (150A, 150B) in the radial direction, so there are four third corners Cn3 in total.

[0045] Furthermore, in the example shown in Figure 4, the sub-parts 150 (150A, 150B) extend from both sides of the main part side surfaces 143 (143a, 143b) and are configured to contact two adjacent container protrusions 112. In other words, both ends of the wick protrusion 132 in the circumferential direction are sandwiched between the container protrusions 112. To put it another way, the wick protrusion 132 is positioned to brace itself between the container protrusions 112 in the circumferential direction. This ensures that the tip of the sub-part 150 makes secure contact with the container protrusion 112.

[0046] Next, the flow of the working fluid will be explained. The liquid phase working fluid, which moves from the inner circumferential surface 137 (see Figure 2) to the outer circumferential surface 131 of the wick 130 due to capillary force, is heated and vaporizes, and flows out into the steam groove 160 formed between the evaporator body 110 and the wick 130. The gaseous phase working fluid that flows out moves along the steam groove 160 and exits towards the steam pipe 105 (see Figure 1).

[0047] More specifically, the liquid working fluid moves from the inner circumferential surface 137 (see Figure 2) to the outer circumferential surface 131 of the wick 130 due to capillary force. Then, as shown in Figure 4, a portion of it moves toward the contact interface of the container top surface 116 (see arrow D1), and another portion moves toward the wick protrusion 132 (see arrow D2).

[0048] When the liquid working fluid reaches the contact interface between the wick base surface 133 and the container protrusion 112 (container top surface 116) (see arrow D1), it vaporizes due to the heat transferred from the heat receiving surface 119 to the container top surface 116, absorbing latent heat of vaporization from the surroundings.

[0049] Furthermore, in the liquid-phase working fluid that has moved to the wick projection 132 (see arrow D3), a portion moves from the main portion 140 toward the tip surface 141 of the main portion (see arrow D4), and another portion moves from the main portion 140 toward the tip surface 151 of the sub-portion (see arrow D6). In this way, the liquid-phase working fluid that has moved to the wick projection 132 moves within the wick projection 132 while branching.

[0050] The liquid-phase working fluid moving toward the main tip surface 141 (see arrow D4) vaporizes as it moves toward the contact interface between the main tip surface 141 and the container bottom surface 118 (see arrow D5), absorbing latent heat of vaporization from the surroundings due to the heat transmitted from the heat-receiving surface 119 to the container bottom surface 118. Similarly, the liquid-phase working fluid moving toward the secondary tip surface 151 (see arrow D6) vaporizes as it moves toward the contact interface between the secondary tip surface 151 of the wick protrusion 132 and the container side surface 114 (see arrow D7), absorbing latent heat of vaporization from the surroundings due to the heat transmitted from the heat-receiving surface 119 to the container side surface 114.

[0051] Thus, in the evaporator 101, in addition to vaporization of the working fluid at the contact interface of the container top surface 116, vaporization of the working fluid also occurs at the contact interface of the wick protrusion 132. In other words, since the contact area ratio is large at 100% throughout the evaporator 101, vaporization of the liquid phase working fluid is greatly promoted, and a large amount of latent heat of vaporization can be removed. As a result, the heat exchange efficiency of the evaporator 101 can be improved compared to a configuration without the wick protrusion 132.

[0052] Furthermore, when the loop-type heat pipe 100 is operating, as shown in Figure 4, liquid-phase working fluid may seep out, or rather, advance, into the first corner Cn1 inside the steam groove 160 (third space R3 and fourth space R4). The liquid-phase working fluid that advances into the first corner Cn1 forms a surface connecting the container side surface 114 of the evaporator body 110 and the wick base surface 133 of the wick 130. This surface can be considered as a liquid bridge Lq1 of the liquid-phase working fluid, formed at the common boundary between the container side surface 114 of the evaporator body 110, the wick base surface 133 of the wick 130, and the steam groove 160. Note that this surface (interface) of the liquid-phase working fluid curves due to the action of the surface tension of the liquid-phase working fluid.

[0053] Similarly, liquid-phase working fluid may advance into the second corner Cn2 inside the steam channel 160 (first space R1 and second space R2). The liquid-phase working fluid that advances into the second corner Cn2 forms a surface connecting the bottom surface 118 of the evaporator body 110 and the main side surfaces 143 (143a, 143b) of the wick 130. This surface can also be considered as a liquid bridge Lq2 formed at the common boundary between the bottom surface 118 of the evaporator body 110, the main side surfaces 143 (143a, 143b) of the wick 130, and the steam channel 160.

[0054] Similarly, liquid-phase working fluid may advance into the third corner Cn3 inside the steam channel 160 (see first space R1 to fourth space R4). The liquid-phase working fluid that advances into the third corner Cn3 forms a surface connecting the container side surface 114 of the evaporator body 110 and the secondary side surfaces 153 (153a, 153b) of the wick 130. This surface can also be considered as a liquid bridge Lq3 formed at the common boundary between the container side surface 114 of the evaporator body 110, the secondary side surfaces 153 (153a, 153b) of the wick 130, and the steam channel 160.

[0055] Furthermore, as shown in Figure 4, a gas-liquid interface of the working fluid is formed on the container side surface 114 of the evaporator body 110. Similarly, a gas-liquid interface of the working fluid is formed on the container bottom surface 118 of the evaporator body 110, the wick base surface 133 of the wick 130, the main side surfaces 143 (143a, 143b) of the wick 130, and the secondary side surfaces 153 (153a, 153b) of the wick 130.

[0056] Furthermore, the boundary line between the three phases—the solid phase of the evaporator body 110 or wick 130, the liquid phase of the working fluid, and the gas phase of the working fluid—in the region where the surface of the evaporator body 110 and the surface of the wick 130 intersect is sometimes called the three-phase boundary line Bd. This region where the surface of the evaporator body 110 and the surface of the wick 130 intersect is the region where either the container side surface 114 or the container bottom surface 118 intersects with either the wick base surface 133, the main side surface 143 (143a, 143b), or the sub-side surface 153 (153a, 153b). The region where the surface of the evaporator body 110 and the surface of the wick 130 intersect can be considered as the region where either the evaporator body 110 or the wick 130 abuts against the other.

[0057] Here, the longer the length of the three-phase boundary line Bd, the greater the evaporation area and the higher the heat exchange efficiency of the evaporator 101. This is thought to be because the evaporation surface of the liquid phase working fluid increases due to the formation of liquid bridges Lq1, Lq2, and Lq3. Alternatively, it can be considered that heat transport occurs via a liquid film with low thermal resistance (the liquid phase working fluid that has advanced into the steam groove 160).

[0058] In the illustrated example, each steam channel 160 has two first corners Cn1, two second corners Cn2, and four third corners Cn3. The formation of these first corners Cn1, second corners Cn2, and third corners Cn3 increases the number of locations where the three-phase boundary Bd is formed, which can improve the heat exchange efficiency of the evaporator 101. To further explain, in the example shown in Figure 4, each steam channel 160 has eight locations where the three-phase boundary Bd is formed.

[0059] Generally, if a steam groove is provided in the area where the evaporator body 110 and the wick 130 come into contact with each other in order to secure a flow path for the vaporized working fluid, the contact area becomes small, making it difficult to secure a large contact area ratio. To explain further, the contact area ratio is often between 30% and 70%. Thus, a contact area ratio of less than 100% is almost unheard of in general cooling devices other than loop heat pipes (for example, liquid cooling). Therefore, although loop heat pipes use evaporation, a phase change phenomenon that has higher cooling performance than liquid cooling, the evaporation surface where heat exchange takes place is smaller than the heat receiving surface, which can result in a decrease in overall cooling performance compared to liquid cooling.

[0060] In contrast, the evaporator 101 in this embodiment has a contact interface with the wick protrusion 132, thus ensuring a large contact area ratio. Furthermore, the number of locations where the three-phase boundary line Bd is formed increases. As a result, the heat exchange efficiency of the evaporator 101 can be significantly improved.

[0061] The container recess 113 and the wick protrusion 132 are formed by well-known techniques such as cutting, laser processing, or etching. Alternatively, the container recess 113 and the wick protrusion 132 may be formed when the evaporator body 110 and the wick 130 are manufactured using a 3D printer.

[0062] Furthermore, the smaller the width dimension W1 of the container recess 113, the greater the heat transfer coefficient and the maximum heat flux. On the other hand, if the width dimension W1 of the container recess 113 is small, the resistance experienced by the gas phase working fluid increases. Also, if the width dimension W1 of the container recess 113 is small, the manufacturing cost increases. Therefore, the width dimension W1 of the container recess 113 is preferably in the range of, for example, 0.3 mm to 5.0 mm.

[0063] Furthermore, although the container protrusion 112 was formed along the entire axial direction on the inner circumferential surface 111 of the evaporator body 110, it may also be provided only in a portion of the axial direction. The same applies to the wick protrusion 132. Also, in Figures 3 and 4, the sub-parts 150 (150A, 150B) are shown to extend in a direction perpendicular to the main part side surface 143 (143a, 143b), but this is not limited to this. The sub-parts 150 (150A, 150B) may extend diagonally outward or inward in the radial direction, for example. Note that by adopting a configuration in which the sub-parts 150 (150A, 150B) are perpendicular to the main part side surface 143 (143a, 143b), the process of forming the wick protrusion 132 in the manufacturing process can be simplified.

[0064] <Modification 1> Figures 5(a) and (b) are diagrams illustrating Modification 1. Note that Figures 5(a) and (b) correspond to Figure 3, which shows the above embodiment. Furthermore, in the description of Figures 5(a) and (b) and subsequent figures, the same reference numerals are used for components identical to those in the above embodiment, and their detailed descriptions are omitted. Next, Modification 1 will be described with reference to Figures 5(a) and (b).

[0065] In the above embodiment, the cross-sectional shape of the wick projection 132 was described as being cross-shaped, but this is not the only option. For example, as shown in Figure 5(a), a container recess 213 with a large depth dimension and a rectangular cross-section, and a wick projection 232 with a sub-part 250 (250A to 250D) configured in two stages in the radial direction may be used. In the example shown in Figure 5(a), the main part 240 is formed to be long in the radial direction, and the tip surfaces 151 of the sub-parts 250 (250A to 250D) are in contact with the opposing container sides 214, with the contact area being A Ｔ２ This means that the area of ​​the contact interface of the wick protrusion 232 is A Ｔ１ +A Ｔ２ It becomes x4.

[0066] By configuring it in this way, the contact interface area of ​​the wick protrusion 232 increases compared to the wick protrusion 132, (A Ｗ２ +A Ｔ１ +A Ｔ２×4), the contact area ratio can be increased. Furthermore, the third corner Cn3 is formed in two places each in close proximity to the sub-parts 250 (250A to 250D), increasing the total to eight places. That is, in the example shown in Figure 5(a), there are twelve places where the three-phase boundary line Bd is formed for each steam groove 160. In other words, the number of places where the three-phase boundary line Bd is formed increases. As a result, the heat exchange efficiency of the evaporator 110 can be improved compared to the wick protrusion 132.

[0067] Similarly, as shown in Figure 5(b), for example, the evaporator body 310 and wick 330 may be made to be even longer in the radial direction by forming the container recess 313 and the main part 340, and the sub-parts 350 (350A to 350F) to be configured in three stages in the radial direction as the wick protrusion 332. In the example shown in Figure 5(b), the main part 340 is made to be even longer in the radial direction, and the tip surfaces 151 of the sub-parts 350 (350A to 350F) are in contact with the opposing container sides 314, and the contact area is A Ｔ２ This means that the area of ​​the contact interface of the wick protrusion 332 is A Ｔ１ +A Ｔ２ It becomes ×6.

[0068] By configuring it in this way, the area of ​​the contact interface of the wick protrusion 332 is further increased compared to the wick protrusion 132 (A Ｗ２ +A Ｔ１ +A Ｔ２ ×6), the contact area ratio can be further increased. Furthermore, the third corner Cn3 is formed in two places at close proximity to the sub-parts 350 (350A to 350F), increasing the total number of locations to twelve. That is, in the example shown in Figure 5(b), there are sixteen locations where the three-phase boundary line Bd is formed for each steam groove 160. In other words, the number of locations where the three-phase boundary line Bd is formed increases. As a result, the heat exchange efficiency of the evaporator 110 can be further improved compared to the wick protrusion 132.

[0069] In this way, increasing the number of sub-parts of the wick protrusion can improve the heat exchange efficiency of the evaporator. Although not shown in the figures, the thickness dimensions T1 of the main part and T2 of the sub-parts of the wick protrusion can also be changed as appropriate. Furthermore, even with a configuration consisting of only one sub-part, the heat exchange efficiency of the evaporator can be improved compared to a configuration without a sub-part. In addition, the number of container protrusions 112 and container recesses 113 can be changed as appropriate, and the dimensions and shape, including the width dimensions W1 and W2, can also be changed as appropriate. Moreover, instead of forming the main parts 240 and 340 to be long in the radial direction, a configuration with multiple stages of sub-parts may be used.

[0070] <Modification 2> Figures 6(a) to 6(c) are diagrams illustrating Modification 2. Each of Figures 6(a) to 6(c) corresponds to Figure 4, which shows the above embodiment. Next, Modification 2 will be explained with reference to Figures 6(a) to 6(c).

[0071] In the above embodiment, the steam channel 160 is described as being equally divided into four spaces (see first space R1 to fourth space R4) by the wick protrusion 132, but the embodiment is not limited to this. For example, as shown in Figure 6(a), a wick protrusion 432X may be formed having a main portion 440X that is trapezoidal in cross-sectional view. That is, the main portion 440X is formed in a so-called tapered shape such that the base end is wider than the tip. The sub-parts 150 (150A, 150B) extend in the circumferential direction from approximately the midpoint of the main portion 440X in the radial direction. The sub-sections 150 (150A, 150B) divide the steam channel 160 into a high-temperature region 161 (see first space R11 and second space R12) close to the heat receiving surface 119 and a low-temperature region 162 (see third space R13 and fourth space R14) further away from the heat receiving surface 119 (see Figure 3). Since the main section 440X is wider at the base than at the tip, the cross-sectional area of ​​the flow path in the high-temperature region 161 is larger than the cross-sectional area of ​​the flow path in the low-temperature region 162.

[0072] Generally, the evaporator body 110 is hottest near the heat receiving surface 119, and the temperature tends to decrease as you move from the heat receiving surface 119 towards the top surface 116 of the container. Therefore, the amount of evaporation of the working fluid in and around the steam groove 160 is greater in the high-temperature region 161, which is closer to the heat receiving surface 119. In the example shown in Figure 6(a), the flow path cross-sectional area of ​​the high-temperature region 161 is larger than that of the low-temperature region 162, so the steam pressure loss in the high-temperature region 161, where the flow rate of the working fluid is relatively high, can be reduced.

[0073] Furthermore, since the main portion 440X is formed so that its base end is wider than its tip end, a large cross-sectional area of ​​the flow path for the working fluid on the upstream side can be secured in the direction from the base end to the tip end of the main portion 440X. As a result, the working fluid can be sufficiently supplied to the main portion tip surface 141 of the main portion 440X and the sub-part tip surface 151 of the sub-parts 150 (150A, 150B).

[0074] Furthermore, the main portion 440Y may be formed with two different thickness dimensions (widths), as shown in the wick protrusion 432Y of the wick 430Y in Figure 6(b). Specifically, the thickness dimension of the main portion 440Y is formed to be larger in the low-temperature region 162 (see the third space R23 and the fourth space R24) compared to the high-temperature region 161 (see the first space R21 and the second space R22). Even with such a configuration, the same effect as the wick 430X shown in Figure 6(a) can be obtained.

[0075] Furthermore, the sub-parts 450 (450A, 450B) may be formed closer to the wick base surface 133, as shown in Figure 6(c) for the wick 430Z, specifically the wick projection 432Z. Specifically, the sub-parts 450 (450A, 450B) extend circumferentially at a position closer to the wick base surface 133 than approximately midway along the radial direction of the main part 140. Even with this configuration, similar to the wick projection 432X shown in Figure 6(a), the flow path cross-sectional area of ​​the high-temperature region 161 (see first space R31 and second space R32) can be made larger than that of the low-temperature region 162 (see third space R33 and fourth space R34).

[0076] <Modification 3> Figures 7(a) and 7(b) are diagrams illustrating Modification 3. Note that each of Figures 7(a) and 7(b) corresponds to Figure 4, which shows the above embodiment. Next, Modification 3 will be explained with reference to Figures 7(a) and 7(b).

[0077] In the above embodiment, the cross-sectional shape of the steam channel 160 is formed as a square, but it is not limited to this. For example, as shown in Figure 7(a), the steam channel 560X of the evaporator body 510X has a recess 563X formed to enlarge the flow path cross-sectional area of ​​the high-temperature region 561X (see first space R51 and second space R52). One of these recesses 563X is formed at each end in the width direction of the container bottom surface 118. In other words, the recesses 563X are formed at a position away from the second corner Cn2. More specifically, one recess 563X is formed on each of the non-contact surfaces 564A and 564B of the container bottom surface 118 that do not come into contact with the main tip surface 141. Also, the recesses 563X are formed at a position close to the container side surface 114 on the non-contact surfaces 564A and 564B. The width dimension of the recess 563X is smaller than the width dimension W3 of the non-contact surfaces 564A and 564B of the container bottom surface 118, and is greater than half of the width dimension W3. Also, the depth dimension of the recess 563X is smaller than half of the width dimension of the recess 563X. This recess 563X is formed along the entire axial direction of the inner circumferential surface 111 of the evaporator body 510X.

[0078] When the wick projection 132 is provided in the steam channel 560X, the flow path cross-sectional area of ​​the steam channel 560X decreases compared to a configuration without the wick projection 132. However, since the flow path cross-section of the steam channel 560X is expanded by the recess 563X, the decrease in the flow path cross-sectional area of ​​the steam channel 560X can be suppressed. Therefore, the increase in steam pressure loss of the working fluid flowing through the steam channel 560X can be suppressed.

[0079] Furthermore, since the recess 563X is formed at a position spaced apart from the second corner Cn2, it does not hinder the formation of liquid bridge Lq2 (see Figure 4). The same applies to the liquid bridges Lq1 and Lq3 of the first corner Cn1 and the third corner Cn3. As a result, the heat exchange rate due to liquid bridge is maintained at the same level as that of the evaporator 101 shown in Figure 3. Note that in the example shown in Figure 7(a), the recess 563X is not provided in the low-temperature region 162 (see the third space R53 and the fourth space R54).

[0080] Here, as shown in Figure 7(b), the recess 563Y may be formed to enlarge the flow path cross-sectional area of ​​the low-temperature region 562Y (see third space R63 and fourth space R64). That is, as with the wick 530Y, the flow path cross-sectional area of ​​the steam groove 560Y may be enlarged by forming the recess 563Y on the wick base surface 133. This recess 563Y is formed one on each side of the base end of the wick protrusion 132 on the wick base surface 133 of the steam groove 560Y. In other words, the recess 563Y is formed at a position away from the first corner Cn1. More specifically, the recess 563Y is formed one each on the non-contact surfaces 565A and 565B of the wick base surface 133 that do not come into contact with the container top surface 116. Furthermore, the recess 563Y is formed at a position close to the main portion 140 of the non-contact surfaces 565A and 565B. The width dimension of the recess 563Y is smaller than the width dimension W4 of the non-contact surfaces 565A and 565B of the wick base surface 133, and is larger than half of the width dimension W4. Also, the depth dimension of the recess 563Y is smaller than half of the width dimension of the recess 563Y. This recess 563Y is formed along the entire axial direction of the inner circumferential surface 111 of the evaporator body 510Y. Even with this configuration, the same effect as the steam groove 560X shown in Figure 7(a) can be obtained.

[0081] Although not shown in the figures, recess 563Y may be provided not only in the low-temperature region 562Y (see third space R63 and fourth space R64) but also in the high-temperature region 161 (see first space R61 and second space R62). Furthermore, recesses 563X and 563Y may be formed at any location on the surface that demarcates the steam channels 560X and 560Y, respectively. In this case, it is desirable to form recesses 563X and 563Y at a distance from the first corner Cn1 and the third corner Cn3 so as not to interfere with the formation of liquid bridges Lq1 and Lq3 (see Figure 4). In addition, the cross-sectional shape, width, and depth of recesses 563X and 563Y can be changed.

[0082] <Modification 4> Figures 8(a) to 8(c) are diagrams illustrating Modification 4. Each of Figures 8(a) to 8(c) corresponds to Figure 4, which shows the above embodiment. Next, Modification 4 will be explained with reference to Figures 8(a) to 8(c).

[0083] In the above embodiment, a sub-part 150 (150A, 150B) is formed on the wick projection 132, but the embodiment is not limited to this. For example, as shown in Figure 8(a), the wick projection 632X may be composed only of the main part 140. In other words, the wick projection 632X has an I-shape in its axial orthogonal cross-section. Even with such a configuration, a contact interface is formed at the main part tip surface 141 of the main part 140, so the contact area ratio can be increased compared to a configuration in which the wick projection 632X is not formed. Furthermore, the formation of a liquid bridge Lq1 (see Figure 4) at the first corner Cn1 and a liquid bridge Lq2 (see Figure 4) at the second corner Cn2 can improve the heat exchange efficiency of the evaporator 110.

[0084] Furthermore, as shown in Figure 8(b), the main portion 632Y may be formed in a so-called tapered shape, with the base being wider than the tip. Even with this configuration, the same effects as those of the wick 630X shown in Figure 8(a) can be obtained.

[0085] Furthermore, in the above embodiment, the main portion 140 of the wick projection 132 is formed to extend (reach) from the wick base surface 133 to the container bottom surface 118, but the invention is not limited to this. For example, as shown in Figure 8(c), the wick projection 632Z of the wick 630Z has a short main portion 640Z that does not reach the container bottom surface 118, and only the tip surface 151 of the sub-parts 150 (150A, 150B) contacts the container side surface 114. Even with such a configuration, a contact interface is formed at the tip surface 151 of the sub-parts 150 (150A, 150B), so the contact area ratio can be increased compared to a configuration in which the wick projection 632Z is ​​not formed. In addition, the formation of a liquid bridge Lq1 (see Figure 4) at the first corner Cn1 and a liquid bridge Lq3 (see Figure 4) at the third corner Cn3 can improve the heat exchange efficiency of the evaporator 110.

[0086] <Modification 5> Figure 9 is a diagram illustrating Modification 5. Note that Figure 9 corresponds to Figure 3, which shows the above embodiment. Next, Modification 5 will be explained with reference to Figure 9.

[0087] In the above embodiment, a container recess 113 is formed on the inner circumferential surface 111 of the evaporator body 110, and this container recess 113 is closed by the wick base surface 133 of the wick 130 to form a steam groove 160, but the embodiment is not limited to this. For example, as shown in Figure 9, a wick recess 735 may be formed on the outer circumferential surface 731 of the wick 730, and this wick recess 735 may be closed by the container base surface 718 of the inner circumferential surface 711 of the evaporator body 710 to form a steam groove 760.

[0088] In this wick 730, wick protrusions 732 with a roughly square cross-section protrude toward the inner circumferential surface 711 of the evaporator body 710. In other words, multiple wick protrusions 732 are formed in the circumferential direction via wick recesses 735. The outer circumferential surface 731 of the wick 730 is formed by wick side surfaces 734, which are the sides of the wick protrusions 732 and are aligned radially; wick top surfaces 737, which are the top surfaces of the wick protrusions 732 and are aligned circumferentially; and wick bottom surfaces 738, which are the bottom surfaces of the wick recesses 735 and are aligned circumferentially.

[0089] On the other hand, on the inner circumferential surface 711 of the evaporator body 710, a container projection 712 with a cross-shaped cross-section perpendicular to the axial direction protrudes toward the outer circumferential surface 731 of the wick 730. This container projection 712 protrudes radially from the container base surface 718 which extends in the circumferential direction and is positioned in the steam groove 760. The steam groove 760 is partitioned by the wick side surface 734, the wick bottom surface 738, and the container base surface 718.

[0090] Furthermore, the container projection 712 has a main portion 740 and a sub-part 750 (750A, 750B). The wick top surface 737 of the wick projection 732 is in contact with the container base surface 718. Also, the main tip surface 741 of the main portion 740 is in contact with the wick bottom surface 738 in the steam groove 760. Also, the sub-part tip surfaces 751 of the sub-parts 750 (750A, 750B) are in contact with the wick sides 734 of the opposing steam groove 760. With this configuration, a large contact area ratio is secured, similar to the above embodiment, and the number of locations where the three-phase boundary line Bd is formed is increased, so the heat exchange efficiency of the evaporator 110 can be greatly improved.

[0091] Although not shown in the figures, the container protrusion 712 provided on the evaporator body 710 may have a different shape, similar to the wick protrusion 132 in the above embodiment. Furthermore, the container protrusion 712 may have various configurations, similar to the wick protrusion described with reference to Figures 5 to 8 above.

[0092] <Modification 6> Figure 10 is a diagram illustrating Modification 6. Figure 10 is a perspective view of the wick 830 in Modification 6. In the above embodiment, it was explained that the wick recess 133 is a groove extending along the axial direction, but the wick recess 133 may also have a portion extending in a direction intersecting the axial direction. Specifically, as shown in Figure 10, in addition to the wick recess 833 and wick protrusion 832 extending in the axial direction formed on the outer circumferential surface 831, a wick circumferential recess 835 extending in the circumferential direction may also be formed. Similarly, a recess extending in the circumferential direction may be formed on the inner circumferential surface 111 of the evaporator body 110 corresponding to the position of this wick circumferential recess 835. By configuring this recess and the wick circumferential recess 835 to communicate with each other, the inside of the steam groove 160 becomes continuous with each other when the wick 830 is placed inside the evaporator body 110 as shown in Figure 3. Therefore, for example, even if the liquid phase working fluid does not reach a certain steam channel 160, the gas phase working fluid from another steam channel 160 flows in through the wick circumferential recess 835, thereby ensuring a flow path for the gas phase working fluid.

[0093] <Modification 7> Figures 11(a) and (b) are diagrams illustrating Modification 7. Figures 11(a) and (b) are perspective views of the evaporator body 910 and other components in Modification 7. For clarity, only a portion of the evaporator body 910 is shown in Figures 11(a) and (b).

[0094] Next, Modification 7 will be described with reference to Figures 11(a) and (b). First, as shown in Figures 11(a) and (b), the evaporator body 910 and the wick 930 may be formed in a flat plate shape. Then, as shown in Figure 11(a), a container recess 913 and a container protrusion 912 are formed on the inner surface 911 of the evaporator body 910, which is the surface facing the wick 930. Also, as shown in Figure 11(b), a wick protrusion 932 is formed on the outer surface 931 of the wick 930, which is the surface facing the evaporator body 910, at a position facing the container recess 913. Here, the container recess 913, the container protrusion 912, and the wick protrusion 932 are formed along the flow direction (see arrow B1), which is the direction in which the liquid phase working fluid flows in through the introduction pipe 170 (see Figure 1). The inner surface 911 of the evaporator body 910 and the outer surface 931 of the wick 930 are positioned opposite each other, so that the wick protrusion 932 is housed in the container recess 913.

[0095] <Measurement Results> Figure 12 is a perspective view showing an overview of the measurement experiment. Figures 13(a) to (e) show the schematic configuration of the measurement samples. To further explain, Figure 13 corresponds to the enlarged view in XIII of Figure 12. Figure 14 shows the measurement results for each measurement sample. To further explain, the horizontal axis in Figure 14 is the heat flux (W / cm²). ２ The graph shows the temperature of the heating plate (°C) on the vertical axis.

[0096] Next, referring to Figures 12 to 14, we will explain the change in heat exchange efficiency that occurs when the contact area ratio is changed.

[0097] Here, we will describe the experimental results using a flat wick 30 as a sample, as shown in Figure 12, as a model of the wick and evaporator body. In this experiment, the flat wick 30, a heating plate 10 (simulating the evaporator body), a flat heater 83, an insulating material 84, and a retaining plate 85 were stacked in order on top of a liquid reservoir 82 placed on a stage 81. The heat from the heater 83 was transferred to the wick 30 via the heating plate 10 (see arrow C21). Liquid ethanol (see arrow C23) was supplied to the liquid reservoir 82 as the working fluid. The side of the wick 30 was then observed with an infrared microscope (100x magnification).

[0098] Furthermore, in this experiment, the heat transfer coefficient h ｅｖ and maximum heat flux q ｍａｘ Performance evaluation was performed using the following method. Note that the heat transfer coefficient h ｅｖ and heat flux q ａｐｐｌｙ h is expressed by the following equations (1) and (2). ｅｖ = q ａｐｐｌｙ / (T ｈ -T ｖ ) (1) x ａｐｐｌｙ = Q ａｐｐｌｙ / A ｈ (2) Here, q ａｐｐｌｙ The heat flux (W / cm²) ２ ), Q ａｐｐｌｙ The thermal load (W) and T ｈ is the heating plate average temperature (℃), T ｖ The steam channel temperature (°C), A ｈ This is the contact area between the heating plate and the wick (including the grooved area that is not in contact) (cm²). ２ ) is the contact area between the heating plate and the wick in the illustrated example (however, including the groove portion that is not in contact) A ｈ 1.5 cm ２ That is the case.

[0099] Furthermore, Wick 30 is made of a porous stainless steel (SUS316L) with a pore diameter of 9.1 μm, a porosity of 52%, and a permeability of 1.09 × 10⁻⁶. －１３ I understand ２The dimensions of the wick 30 are 15 mm wide, 10 mm deep, 5 mm high, with a steam channel width of 1 mm and a steam channel height of 1 mm. The heating plate 10 is 1 mm thick.

[0100] Next, we will explain the measurement samples, the heating plate 10 and the wick 30. In this experiment, as shown in Figure 13, measurements were performed using five measurement samples with different contact area ratios and liquid crosslinking numbers between the heating plate 10 and the wick 30. The contact area ratio referred to here is the ratio of the area of ​​the contact interface between the heating plate 10 and the wick 30 to the heat receiving area of ​​the heating plate 10.

[0101] First, the first measurement sample (No. 1 in the figure) shown in Figure 13(a) has a wick recess 35 (steam groove 60) and a wick protrusion 32 formed on the outer surface 31 of the wick 30, while the inner surface 11 of the heating plate 10 is flat. In this first measurement sample, the contact area ratio is 50%, and the number of liquid crosslinks is 14.

[0102] Furthermore, the second measurement sample (No. 2 in the figure) shown in Figure 13(b) has a wick recess 35 (steam groove 60) and a wick protrusion 32 formed on the outer surface 31 of the wick 30, while a protrusion 12P with an I-shaped cross-section is formed on the inner surface 11P of the heating plate 10P, and this protrusion 12P is placed in the steam groove 60. In this second measurement sample, the contact area ratio is 63%, and the number of liquid crosslinks is 28.

[0103] Furthermore, the third measurement sample (No. 3 in the figure) shown in Figure 13(c) has a cross-shaped wick projection 32X formed on the outer surface 31X of the wick 30X, while a recess 13Q (steam groove 60) and a projection 12Q are formed on the inner surface 11Q of the heating plate 10Q. In this third measurement sample, the contact area ratio is 100%, and the number of liquid crosslinks is 56. This configuration corresponds to the configuration in Figure 3.

[0104] Furthermore, the fourth measurement sample (No. 4 in the figure) shown in Figure 13(d) has a wick recess 35 (steam groove 60) and a wick protrusion 32 formed on the outer surface 31 of the wick 30, while a cross-shaped protrusion 12R is formed on the inner surface 11R of the heating plate 10R. In this fourth measurement sample, the contact area ratio is 100%, and the number of liquid crosslinks is 56. This configuration corresponds to the configuration in Figure 9.

[0105] Furthermore, the fifth measurement sample (No. 5 in the figure) shown in Figure 13(e) has the same basic configuration as the third measurement sample, but the number of wick protrusions 32Y and recesses 13S (steam grooves 60) with a cross-shaped cross section has been increased. In this fifth measurement sample, the contact area ratio is 100%, and the number of liquid crosslinks is 88.

[0106] Comparing the contact area ratios of each of the above-mentioned measurement samples, the relationship is as follows: 1st measurement sample < 2nd measurement sample < 3rd measurement sample = 4th measurement sample = 5th measurement sample. Also, comparing the number of liquid crosslinks of each of the above-mentioned measurement samples, the relationship is as follows: 1st measurement sample < 2nd measurement sample < 3rd measurement sample = 4th measurement sample < 5th measurement sample.

[0107] In this experiment, the heat flux from heater 83 was set to 0.5 W / cm². ２ The temperature was increased step by step, and measurements were continued until the temperature of the heating plate 10 exceeded 100°C. The heat flux of the heater 83 when the temperature of the heating plate 10 reached 100°C was defined as the maximum heat flux, and the heat exchange rate of each sample was evaluated.

[0108] As shown in Figure 14, it was confirmed that the measured maximum heat flux differed for each sample. To further explain, Figure 14 shows that the maximum heat flux changes depending on the contact area ratio and the number of liquid bridges. Specifically, the maximum heat flux increases as the contact area ratio and the number of liquid bridges increase. In other words, the heat exchange rate increases as either the contact area ratio or the number of liquid bridges increases.

[0109] Furthermore, when comparing the third, fourth, and fifth measurement samples, even if the contact area ratio is the same, a larger number of liquid crosslinks results in a larger maximum heat flux and a higher heat exchange rate.

[0110] <Electronic Devices> Figure 15 is a diagram illustrating a mobile phone M equipped with a loop-type heat pipe 100. Next, the mobile phone M equipped with the loop-type heat pipe 100 will be described with reference to Figure 15.

[0111] As shown in Figure 15, the loop-type heat pipe 100 is installed in an electronic device such as a mobile phone M. The illustrated mobile phone M is a so-called smartphone with a flat plate shape. This mobile phone M comprises a central processing unit (CPU) 1, a loop-type heat pipe 100 for cooling the central processing unit 1, and a housing 3 that houses these inside. The heat generated in the central processing unit 1, which is an example of a heat source, is transferred to the evaporator 101 and released in the condenser 107. In the illustrated example, the condenser 107 has multiple folded sections to secure a heat dissipation area.

[0112] Here, the device on which the loop-type heat pipe 100, which is an example of a heat exchanger, is provided is not limited to the mobile phone M described above. For example, the loop-type heat pipe 100 may be provided in various devices equipped with heat-generating components, such as electronic devices like personal computers and projectors, and transportation equipment like automobiles.

[0113] Here, the evaporator body 110 is an example of a housing. The wick 130 is an example of an evaporator. The container protrusion 112 is an example of a first protrusion. The wick protrusion 132 is an example of a second protrusion.

[0114] The above embodiments, in whole or in part, and modifications are not limited to, but can also be described as follows: <Notes> (Note 1) An apparatus comprising a heating element and a heat exchanger having an evaporator that absorbs heat from the heating element and evaporates a liquid-phase working fluid, and condenses the gas-phase working fluid discharged from the evaporator and recirculates it to the evaporator, wherein the evaporator comprises an evaporator that guides a liquid-phase working fluid to the outer surface by capillary force and evaporates it, and a housing that houses the evaporator and has an inner surface facing the outer surface, wherein a plurality of first protrusions are formed at predetermined intervals on one of the outer surface and the inner surface, protruding toward the other of the outer surface and the inner surface, and a second protrusion is formed on the other, protruding toward the one between two adjacent first protrusions, and the second protrusion includes a main part that protrudes toward the one from the other and whose tip contacts the one, and a sub-part that protrudes toward the first protrusion from the main part in a direction intersecting the main part and whose tip contacts the first protrusion. (Note 2) The apparatus according to Note 1, wherein the sub-part extends from both sides of the main part toward the two adjacent first protrusions. (Note 3) The apparatus according to Note 1 or 2, wherein the sub-part extends in a direction perpendicular to the main part. (Note 4) The apparatus according to any one of Notes 1 to 3, wherein the sub-part is formed midway along the length of the main part in the direction of projection, and the main part and the sub-part divide the space between the two adjacent first protrusions into four spaces. (Note 5) The apparatus according to any one of Notes 1 to 4, wherein at least one of the outer surface and the inner surface has a recess formed in a region that demarcates any of the four spaces, so as to enlarge any of the spaces. (Note 6) The apparatus according to any one of Notes 1 to 5, wherein the sub-part extends in a direction intersecting the main part from a position closer to the base end of the main part than to the tip of the main part.(Note 7) The containment has a heat receiving surface on the side opposite to the inner surface that receives heat from the heating element, the evaporator is partitioned by two adjacent first protrusions and the other, and has a steam groove that guides the gas phase working fluid, the sub-part divides the steam groove into a high-temperature region close to the heat receiving surface and a low-temperature region away from the heat receiving surface, the high-temperature region has a larger flow path cross-sectional area than the low-temperature region, the apparatus according to any one of Notes 1 to 6. (Note 8) The base end of the main part is wider than the tip of the main part, the apparatus according to any one of Notes 1 to 7. (Note 9) The sub-part is formed in multiple locations at intervals along the direction in which the main part protrudes, the apparatus according to any one of Notes 1 to 8. (Note 10) The apparatus according to any one of Notes 1 to 9, wherein the housing has a heat-receiving surface on the side opposite to the inner surface that receives heat from the heating element, and the ratio of the area of ​​the contact portion between the outer surface and the inner surface to the area of ​​the heat-receiving surface is 100% or more. (Note 11) A device comprising a heating element and a heat exchanger having an evaporator that absorbs heat from the heating element and evaporates a liquid-phase working fluid, and condenses the gaseous working fluid discharged from the evaporator and recirculates it to the evaporator, wherein the evaporator comprises an evaporator that guides a liquid-phase working fluid to its outer surface by capillary force and evaporates it, and a housing that houses the evaporator and has an inner surface facing the outer surface, wherein a plurality of first protrusions are formed at predetermined intervals on one of the outer surface and the inner surface, projecting toward the other of the outer surface and the inner surface, and a second protrusion is formed on the other, projecting toward the one between two adjacent first protrusions, and the second protrusion includes a main part that projects toward the one from the other and whose tip contacts the one.(Note 12) A device comprising a heating element and a heat exchanger having an evaporator that absorbs heat from the heating element to evaporate a liquid-phase working fluid, and condensing the gaseous working fluid discharged from the evaporator and recirculating it to the evaporator, wherein the evaporator comprises an evaporator that guides a liquid-phase working fluid to the outer surface by capillary force and evaporates it, and a housing that houses the evaporator and has an inner surface facing the outer surface, wherein a plurality of first protrusions are formed at predetermined intervals on one of the outer surface and the inner surface, projecting toward the other of the outer surface and the inner surface, and a second protrusion is formed on the other, projecting toward the one between two adjacent first protrusions, and the second protrusion includes a main part that projects toward the one from the other, and a sub-part that projects toward the first protrusion from the main part in a direction intersecting the main part, with its tip in contact with the first protrusion. (Note 13) A heat exchanger having an evaporator that absorbs heat from the outside to evaporate a liquid-phase working fluid, and condensing a gaseous-phase working fluid that flows out of the evaporator and recirculating it to the evaporator, wherein the evaporator comprises an evaporator that guides a liquid-phase working fluid to the outer surface by capillary force and evaporates it, and a housing that houses the evaporator and has an inner surface facing the outer surface, wherein a plurality of first protrusions are formed at predetermined intervals on one of the outer surface and the inner surface, projecting toward the other of the outer surface and the inner surface, and a second protrusion is formed on the other between two adjacent first protrusions projecting toward the one, and the second protrusion includes a main part that projects toward the one from the other and whose tip contacts the one, and a sub-part that projects toward the main part in a direction intersecting the main part and whose tip contacts the first protrusion.(Note 14) An evaporator that absorbs heat from the outside, evaporates a liquid working fluid, discharges a gaseous working fluid, and allows the discharged gaseous working fluid to condense and recirculate, comprising: an evaporator that guides a liquid working fluid to the outer surface by capillary force and evaporates it; and a housing that houses the evaporator and has an inner surface facing the outer surface, wherein a plurality of first protrusions are formed at predetermined intervals on one of the outer surface and the inner surface, projecting toward the other of the outer surface and the inner surface, and a second protrusion is formed on the other, projecting toward the one between two adjacent first protrusions, and the second protrusion includes a main part that projects toward the one from the other and whose tip contacts the one, and a sub-part that projects toward the main part in a direction intersecting the main part and whose tip contacts the first protrusion.

[0115] Now, various embodiments and modifications have been described above, but these embodiments and modifications can of course be combined to form a single structure. To further explain, each embodiment, modification, and component described herein can be arbitrarily combined and applied as long as they are not mutually exclusive. For example, the structures of the evaporator body 110, wick 130, container protrusion 112, and wick protrusion 132 described above can be combined as appropriate. Furthermore, this disclosure is not limited in any way to the embodiments described above, and can be implemented in various forms without departing from the spirit of this disclosure.

[0116] 100... Loop-type heat pipe, 101... Evaporator, 107... Condenser, 110... Evaporator body, 112... Container protrusion, 113... Container recess, 130... Wick, 132... Wick protrusion, Lq1, Lq2, Lq3... Liquid crosslinking

Claims

1. A device comprising a heating element and a heat exchanger having an evaporator that absorbs heat from the heating element to evaporate a liquid-phase working fluid, and condensing the gaseous working fluid discharged from the evaporator and recirculating it to the evaporator, wherein the evaporator comprises an evaporator that guides a liquid-phase working fluid to its outer surface by capillary force and evaporates it, and a housing that houses the evaporator and has an inner surface facing the outer surface, wherein a plurality of first protrusions are formed at predetermined intervals on one of the outer surface and the inner surface, projecting toward the other of the outer surface and the inner surface, and a second protrusion is formed on the other, projecting toward the one between two adjacent first protrusions, and the second protrusion includes a main part that projects toward the one from the other and whose tip contacts the one, and a sub-part that projects toward the main part in a direction intersecting the main part and whose tip contacts the first protrusion.

2. The apparatus according to claim 1, wherein the sub-part extends from both sides of the main part toward the two adjacent first protrusions.

3. The apparatus according to claim 2, wherein the sub-part extends in a direction perpendicular to the main part.

4. The apparatus according to any one of claims 1 to 3, wherein the sub-part is formed midway along the length in the direction in which the main part protrudes, and the main part and the sub-part divide the space between the two adjacent first protruding parts into four spaces.

5. The apparatus according to claim 4, wherein at least one of the outer surface and the inner surface is provided with a recess formed in a region that demarcates any of the four spaces, so as to enlarge any of the spaces.

6. The apparatus according to any one of claims 1 to 3, wherein the sub-part extends in a direction intersecting the main part from a position closer to the base end of the main part than to the tip of the main part.

7. The apparatus according to any one of claims 1 to 3, wherein the housing has a heat receiving surface on the side opposite to the inner surface that receives heat from the heating element, the evaporator is partitioned by two adjacent first protrusions and the other and has a steam groove that guides a gaseous working fluid, the sub-part divides the steam groove into a high-temperature region near the heat receiving surface and a low-temperature region away from the heat receiving surface, and the high-temperature region has a larger flow path cross-sectional area than the low-temperature region.

8. The apparatus according to any one of claims 1 to 3, wherein the base end of the main part is wider than the tip of the main part.

9. The apparatus according to any one of claims 1 to 3, wherein the sub-parts are formed in a plurality at intervals along the direction in which the main part protrudes.

10. The apparatus according to any one of claims 1 to 3, wherein the housing has a heat-receiving surface on the side opposite to the inner surface that receives heat from the heating element, and the ratio of the area of ​​the contact portion between the outer surface and the inner surface to the area of ​​the heat-receiving surface is 100% or more.

11. A device comprising a heating element and a heat exchanger having an evaporator that absorbs heat from the heating element to evaporate a liquid-phase working fluid, and condensing the gaseous working fluid discharged from the evaporator and recirculating it to the evaporator, wherein the evaporator comprises an evaporator that guides a liquid-phase working fluid to its outer surface by capillary force and evaporates it, and a housing that houses the evaporator and has an inner surface facing the outer surface, wherein a plurality of first protrusions are formed at predetermined intervals on one of the outer surface and the inner surface, projecting toward the other of the outer surface and the inner surface, and a second protrusion is formed on the other, projecting toward the one between two adjacent first protrusions, and the second protrusion includes a main part that projects toward the one from the other and whose tip contacts the one.

12. A device comprising a heating element and a heat exchanger having an evaporator that absorbs heat from the heating element to evaporate a liquid-phase working fluid, and condensing the gaseous working fluid discharged from the evaporator and recirculating it to the evaporator, wherein the evaporator comprises an evaporator that guides a liquid-phase working fluid to its outer surface by capillary force and evaporates it, and a housing that houses the evaporator and has an inner surface facing the outer surface, wherein a plurality of first protrusions are formed at predetermined intervals on one of the outer surface and the inner surface, projecting toward the other of the outer surface and the inner surface, and a second protrusion is formed on the other, projecting toward the one between two adjacent first protrusions, and the second protrusion includes a main part projecting toward the one from the other, and a sub-part projecting toward the main part in a direction intersecting the main part, with its tip in contact with the first protrusion.

13. A heat exchanger having an evaporator that absorbs heat from the outside to evaporate a liquid-phase working fluid, and condensing a gaseous-phase working fluid that flows out of the evaporator and recirculating it to the evaporator, wherein the evaporator comprises an evaporator that guides a liquid-phase working fluid to the outer surface by capillary force and evaporates it, and a housing that houses the evaporator and has an inner surface facing the outer surface, wherein a plurality of first protrusions are formed at predetermined intervals on one of the outer surface and the inner surface, projecting toward the other of the outer surface and the inner surface, and a second protrusion is formed on the other, projecting toward the one between two adjacent first protrusions, and the second protrusion includes a main part that projects toward the one from the other and whose tip contacts the one, and a sub-part that projects toward the main part in a direction intersecting the main part and whose tip contacts the first protrusion.

14. An evaporator that absorbs heat from the outside, evaporates a liquid working fluid, discharges a gaseous working fluid, and allows the discharged gaseous working fluid to condense and recirculate, comprising: an evaporator that guides a liquid working fluid to the outer surface by capillary force and evaporates it; and a housing that houses the evaporator and has an inner surface facing the outer surface, wherein a plurality of first protrusions are formed at predetermined intervals on one of the outer surface and the inner surface, projecting toward the other of the outer surface and the inner surface, and a second protrusion is formed on the other, projecting toward the one between two adjacent first protrusions, and the second protrusion includes a main part that projects toward the one from the other and whose tip contacts the one, and a sub-part that projects toward a direction intersecting the main part and whose tip contacts the first protrusion.

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