JP2017219269A - Cooling method of heating element - Google Patents
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Abstract
Description
本発明は、発熱体の冷却方法に関するものである。 The present invention relates to a method for cooling a heating element.
近年、図１に示すような軽水炉の圧力容器において、燃料棒が溶融事故を起こしても、原子炉圧力容器底部を外部から水で冷却してメルトスルーを生じさせない冷却機構が求められており、そのような冷却機構として、沸騰冷却方式によるものが知られている。 In recent years, in a pressure vessel of a light water reactor as shown in FIG. 1, there is a demand for a cooling mechanism that does not cause melt-through by cooling the bottom of the reactor pressure vessel with water from the outside even if a fuel rod causes a melting accident, As such a cooling mechanism, a boiling cooling system is known.
沸騰冷却方式には、プール沸騰方式と、強制流動沸騰方式がある。ここでは、プール沸騰方式による発熱体の一般的な冷却機構について説明する。図２は、従来のプール沸騰方式による冷却器を示している。冷却器は、容器と、容器内に収容された作動流体とを備え、容器は、冷却対象である発熱体との接触部を有する。発熱体において熱が発生し、接触部を通して作動流体に熱が伝わると、接触部の近傍に存在する作動流体が沸騰する。沸騰により蒸気が生じると気液の密度差により接触部に作動流体が供給される。こうして新たに供給された作動流体がさらに蒸発し、発熱体から熱を除去する。プール沸騰方式による冷却器は、強制流動沸騰方式のような液体を循環させるための外部動力源が不要であるため、コンパクト性および省エネルギー性に有利である。 The boiling cooling method includes a pool boiling method and a forced flow boiling method. Here, a general cooling mechanism of the heating element by the pool boiling method will be described. FIG. 2 shows a conventional pool boiling cooler. The cooler includes a container and a working fluid contained in the container, and the container has a contact portion with a heating element to be cooled. When heat is generated in the heating element and the heat is transmitted to the working fluid through the contact portion, the working fluid existing in the vicinity of the contact portion boils. When steam is generated by boiling, working fluid is supplied to the contact portion due to the density difference between the gas and liquid. In this way, the newly supplied working fluid is further evaporated, and heat is removed from the heating element. The pool boiling type cooler is advantageous in terms of compactness and energy saving because it does not require an external power source for circulating the liquid as in the forced flow boiling method.
プール沸騰方式による冷却方法の例として、本発明者は、特開２００９−１３９００５号公報（特許文献１）において多孔質体を発熱体と冷却容器内の水との間に設けて、多孔質体の毛細管現象により水を発熱体へ供給しつつ、それにより発生した蒸気を容器内の水中へ排出する構造を開示している。 As an example of a cooling method using a pool boiling method, the present inventor has disclosed a method of providing a porous body between a heating element and water in a cooling container in Japanese Patent Application Laid-Open No. 2009-139005 (Patent Document 1). A structure is disclosed in which water is supplied to the heating element by the capillary phenomenon, and the steam generated thereby is discharged into the water in the container.
しかしながら、従来、プール沸騰方式による発熱体の冷却方法は、発熱体が既に水等の作動流体中に浸漬されている状態で、徐々に温度上昇して高温となった発熱体を効果的に冷却しようとするものである。一方、高温の発熱体を水等の作動流体中に浸漬させることで冷却しようとする場合、下記の問題が生じる。 However, conventionally, the cooling method of the heating element by the pool boiling method effectively cools the heating element that has been gradually heated to a high temperature while the heating element is already immersed in a working fluid such as water. It is something to try. On the other hand, when trying to cool a hot heating element by immersing it in a working fluid such as water, the following problems arise.
図３は、大気圧下、水を用いた発熱体の沸騰冷却特性を示すためのグラフである。当該グラフは発熱体の伝熱面過熱度の対数をｘ軸にとり、発熱体の伝熱面熱流束の対数をｙ軸にとっている。当該グラフに示すように、例えば伝熱面温度が１０００℃以上の高温は水の膜沸騰が起こる領域（膜沸騰域）となる。そのため、このような高温の発熱体の伝熱面を水中に浸漬すると、伝熱面で水の膜沸騰が生じてしまう。膜沸騰では、蒸気の膜が伝熱面と水との境界に生じるため、伝熱面の熱が水に伝わらず伝熱面の冷却が不良となる。このように、高温になっている発熱体を単純に水没させるだけの沸騰冷却では、発熱体の冷却不足や冷却に時間がかかるという問題が生じる。そして、特に発熱体が図１に示すような原子炉圧力容器である場合、原子炉容器のメルトスルーの阻止が困難になるという非常に大きな問題となる。 FIG. 3 is a graph for showing boiling cooling characteristics of a heating element using water under atmospheric pressure. In the graph, the logarithm of the heat transfer surface superheat degree of the heat generating element is taken on the x axis, and the logarithm of the heat transfer surface heat flux of the heat generating element is taken on the y axis. As shown in the graph, for example, a high temperature at a heat transfer surface temperature of 1000 ° C. or higher is a region where water film boiling occurs (film boiling region). For this reason, when the heat transfer surface of such a high-temperature heating element is immersed in water, water film boiling occurs on the heat transfer surface. In film boiling, since a vapor film is generated at the boundary between the heat transfer surface and water, the heat of the heat transfer surface is not transferred to the water, resulting in poor cooling of the heat transfer surface. In this way, boiling cooling that simply submerses the heating element that is at a high temperature causes problems such as insufficient cooling of the heating element and a long time for cooling. In particular, when the heating element is a reactor pressure vessel as shown in FIG. 1, it becomes a very big problem that it is difficult to prevent melt-through of the reactor vessel.
本発明はこのような問題に鑑み、高温の発熱体を作動流体中に浸漬させて冷却する方法において、速やかに発熱体を冷却することが可能な発熱体の冷却方法を提供することを課題とする。 In view of such a problem, the present invention has an object to provide a cooling method for a heating element capable of quickly cooling the heating element in a method of cooling a heating element by immersing it in a working fluid. To do.
本発明者らは研究を重ねたところ、詳細は後述するが、高温になっている発熱体の表面に冷却部材としての多孔質体を設け、この状態で発熱体を作動流体中に浸漬することで、発熱体の伝熱面で作動流体の膜沸騰が生じることを良好に抑制し、速やかに伝熱面温度を作動流体の核沸騰が起こる領域（核沸騰域）となる過熱度まで低下させることができることを見出した。そして、このような構成によって、発熱体の伝熱面に蒸気膜が生じることが抑制され、作動流体によって効果的に発熱体を冷却することができることを見出した。 As a result of repeated research, the inventors of the present invention provide a porous body as a cooling member on the surface of the heating element that is at a high temperature, and immerses the heating element in the working fluid in this state. Therefore, it is possible to satisfactorily suppress film boiling of the working fluid on the heat transfer surface of the heating element, and quickly reduce the temperature of the heat transfer surface to the degree of superheat that becomes the region (nuclear boiling region) where the nucleate boiling of the working fluid occurs. I found that I can do it. And it discovered that a vapor | steam film | membrane was suppressed by such a structure and the heat transfer surface of a heat generating body produced | generated, and a heat generating body can be cooled effectively with a working fluid.
すなわち本発明は、作動流体を収容した容器の作動流体中に、発熱体を少なくとも部分的に浸漬して発熱体を冷却する沸騰方式による冷却方法において、発熱体の作動流体に浸漬する部分の表面に冷却部材としての多孔質体を設ける工程と、前記多孔質体が設けられた発熱体の表面を前記作動流体中に浸漬して、前記多孔質体が設けられた発熱体の表面の温度を低下させる工程とを備えた発熱体の冷却方法である。 That is, the present invention relates to a boiling method cooling method in which a heating element is at least partially immersed in a working fluid of a container containing the working fluid to cool the heating element, and the surface of the portion of the heating element that is immersed in the working fluid. A step of providing a porous body as a cooling member, and immersing the surface of the heating element provided with the porous body in the working fluid to adjust the temperature of the surface of the heating element provided with the porous body. A method of cooling the heating element.
本発明の発熱体の冷却方法は一実施形態において、前記作動流体に浸漬する部分の表面の温度が前記作動流体に膜沸騰が起こる温度領域にある発熱体に対し、前記作動流体に浸漬する部分の表面に多孔質体を設ける工程と、前記多孔質体が設けられた発熱体の表面を前記作動流体中に浸漬して、前記多孔質体が設けられた発熱体の表面の温度を前記作動流体に核沸騰が起こる温度領域となる過熱度まで低下させる工程とを備える。 In one embodiment of the method for cooling a heating element of the present invention, a part immersed in the working fluid with respect to a heating element in which the surface temperature of the part immersed in the working fluid is in a temperature region where film boiling occurs in the working fluid A step of providing a porous body on the surface of the heating element, and immersing the surface of the heating element provided with the porous body in the working fluid to set the temperature of the surface of the heating element provided with the porous body to the operating temperature. And a step of reducing the degree of superheat to a temperature range where nucleate boiling occurs in the fluid.
本発明の発熱体の冷却方法は別の一実施形態において、前記作動流体が水であって、且つ、大気圧下で前記発熱体を冷却する方法であり、前記作動流体に核沸騰が起こる温度領域となる過熱度が１３０℃以下である。 In another embodiment, the heating element cooling method of the present invention is a method in which the working fluid is water and the heating element is cooled under atmospheric pressure, and a temperature at which nucleate boiling occurs in the working fluid. The superheat degree which becomes an area | region is 130 degrees C or less.
本発明の発熱体の冷却方法は更に別の一実施形態において、前記多孔質体が、毛細管現象により前記作動流体を前記発熱体の表面に供給する作動流体供給部と、前記発熱体の表面で発生した蒸気を前記作動流体中へ排出する蒸気排出部とを備える。 In still another embodiment of the method for cooling a heating element of the present invention, the porous body includes a working fluid supply unit that supplies the working fluid to the surface of the heating element by capillary action, and a surface of the heating element. A steam discharge section for discharging the generated steam into the working fluid.
本発明の発熱体の冷却方法は更に別の一実施形態において、前記多孔質体が、前記発熱体側に設けられた第１の多孔質体と、前記作動流体側に設けられた第２の多孔質体とを備えた積層構造に構成された冷却部材であり、前記第１の多孔質体は、毛細管現象により前記作動流体を前記発熱体の表面に供給する第１の作動流体供給部と、前記発熱体の表面で発生した蒸気を前記第２の多孔質体側へ排出する第１の蒸気排出部とを備え、前記第２の多孔質体は、前記作動流体を前記第１の多孔質体に供給する第２の作動流体供給部と、前記第１の多孔質体から排出された蒸気を前記作動流体中へ排出する第２の蒸気排出部とを備え、前記第１の多孔質体よりも前記作動流体の透過率が大きい多孔質体で形成されている。 In still another embodiment of the method for cooling a heating element of the present invention, the porous body includes a first porous body provided on the heating element side and a second porosity provided on the working fluid side. And a first working fluid supply unit configured to supply the working fluid to the surface of the heating element by capillary action, and a cooling member configured in a laminated structure including a material. A first vapor discharge section for discharging vapor generated on the surface of the heating element to the second porous body side, and the second porous body supplies the working fluid to the first porous body. A second working fluid supply section for supplying the first working fluid, and a second steam discharging section for discharging the steam discharged from the first porous body into the working fluid, from the first porous body Is formed of a porous body having a high permeability of the working fluid.
本発明の発熱体の冷却方法は更に別の一実施形態において、前記発熱体が原子炉圧力容器である。 In still another embodiment of the heating element cooling method of the present invention, the heating element is a reactor pressure vessel.
本発明の発熱体の冷却方法によれば、高温の発熱体を作動流体中に浸漬させて冷却する方法において、速やかに発熱体を冷却することが可能な発熱体の冷却方法を提供することができる。 According to the method for cooling a heating element of the present invention, in the method for cooling a heating element by immersing it in a working fluid, it is possible to provide a cooling method for a heating element that can quickly cool the heating element. it can.
以下、図面を参照して本発明の実施形態を詳細に説明する。なお以下の実施形態は本願発明を例示するものであり、本願発明がこれら実施形態に限定されるものではない。
（実施形態１）
図４は、実施形態１に係るプール沸騰方式による発熱体の冷却方式を説明するための図である。図４において（Ａ）は実施形態１に係る発熱体及び多孔質体の模式図であり、（Ｂ）は実施形態１に係る多孔質体の平面図であり、（Ｃ）は実施形態１に係る発熱体及び多孔質体を冷却するための容器内へ浸漬した状態を示す模式図である。
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments exemplify the present invention, and the present invention is not limited to these embodiments.
(Embodiment 1)
FIG. 4 is a view for explaining a cooling method of the heating element by the pool boiling method according to the first embodiment. 4A is a schematic view of a heating element and a porous body according to Embodiment 1, FIG. 4B is a plan view of the porous body according to Embodiment 1, and FIG. It is a schematic diagram which shows the state immersed in the container for cooling the heat generating body and porous body which concern.
実施形態１に係る発熱体の冷却方法は、発熱体の作動流体に浸漬する部分の表面に冷却部材としての多孔質体を設ける工程と、多孔質体が設けられた発熱体の表面を作動流体中に浸漬して、多孔質体が設けられた発熱体の表面の温度を低下させる工程とを備える。このような構成によれば、高温になっている発熱体の表面に冷却部材としての多孔質体を設け、この状態で発熱体を作動流体中に浸漬するため、発熱体の伝熱面の温度が作動流体の膜沸騰が起こる領域（膜沸騰域）の温度であっても、多孔質体が作動流体を伝熱面へ供給することができる。このため、発熱体の伝熱面に蒸気膜が生じることが抑制され、作動流体によって効果的に発熱体を冷却することができる。 The heating element cooling method according to the first embodiment includes a step of providing a porous body as a cooling member on a surface of a portion immersed in the working fluid of the heating element, and a surface of the heating element provided with the porous body as a working fluid. And a step of reducing the temperature of the surface of the heating element provided with the porous body by immersing in the inside. According to such a configuration, since the porous body as a cooling member is provided on the surface of the heating element that is at a high temperature, and the heating element is immersed in the working fluid in this state, the temperature of the heat transfer surface of the heating element Even when the temperature of the working fluid is in a region where film boiling occurs (film boiling region), the porous body can supply the working fluid to the heat transfer surface. For this reason, the generation of a vapor film on the heat transfer surface of the heating element is suppressed, and the heating element can be effectively cooled by the working fluid.
また、発熱体の冷却方法は、作動流体に浸漬する部分の表面の温度が作動流体に膜沸騰が起こる温度領域にある発熱体に対し、作動流体に浸漬する部分の表面に多孔質体を設ける工程と、多孔質体が設けられた発熱体の表面を作動流体中に浸漬して、多孔質体が設けられた発熱体の表面の温度を作動流体に核沸騰が起こる温度領域となる過熱度まで低下させる工程とを備えてもよい。このような構成によれば、高温になっている発熱体の表面に冷却部材としての多孔質体を設け、この状態で発熱体を作動流体中に浸漬するため、発熱体の伝熱面の温度が作動流体の膜沸騰が起こる領域（膜沸騰域）の温度であっても、多孔質体が作動流体を伝熱面へ供給することができる。このため、発熱体の伝熱面で作動流体の膜沸騰が生じることを良好に抑制し、速やかに伝熱面温度を作動流体の核沸騰が起こる領域（核沸騰域）となる過熱度まで低下させることができる。従って、発熱体の伝熱面に蒸気膜が生じることが抑制され、作動流体によって効果的に発熱体を冷却することができる。 In addition, the method of cooling the heating element is to provide a porous body on the surface of the portion immersed in the working fluid with respect to the heating element in which the temperature of the surface of the portion immersed in the working fluid is in a temperature range where film boiling occurs in the working fluid. A process and a superheat degree in which the surface of the heating element provided with the porous body is immersed in the working fluid, and the temperature of the surface of the heating element provided with the porous body becomes a temperature region where nucleate boiling occurs in the working fluid May be provided. According to such a configuration, since the porous body as a cooling member is provided on the surface of the heating element that is at a high temperature, and the heating element is immersed in the working fluid in this state, the temperature of the heat transfer surface of the heating element Even when the temperature of the working fluid is in a region where film boiling occurs (film boiling region), the porous body can supply the working fluid to the heat transfer surface. For this reason, it is well suppressed that film boiling of the working fluid occurs on the heat transfer surface of the heating element, and the temperature of the heat transfer surface is quickly reduced to the degree of superheat that becomes the region where the fluid nucleate boils (nuclear boiling region). Can be made. Therefore, the generation of a vapor film on the heat transfer surface of the heating element is suppressed, and the heating element can be effectively cooled by the working fluid.
作動流体が水であって、且つ、大気圧下で前記発熱体を冷却する方法である場合、作動流体に核沸騰が起こる温度領域となる過熱度を１３０℃以下とし、この１３０℃以下まで発熱体の伝熱面の温度を低下させることで、発熱体の伝熱面に蒸気膜が生じることが抑制され、作動流体によって効果的に発熱体を冷却することができる。なお、本発明で使用する作動流体は、水以外であってもよく、例えば、低温流体、冷媒、有機溶媒等の表面張力を有する液体とすることができる。作動流体として、例えば０．１体積％程度のナノ流体を含んだ水を用いると、発熱体の伝熱面に作動流体の蒸発によるナノ流体の層が生じるため、より良好に発熱体を冷却することができる。本発明において、「ナノ流体」は平均粒径が例えば１０ｎｍ〜３０ｎｍ、または２０〜２５ｎｍであってもよく、または２１ｎｍ程度であってもよい。また、「ナノ流体」の材質はＴｉＯ2であってもよい。 When the working fluid is water and the heating element is cooled under atmospheric pressure, the degree of superheating, which is a temperature range where nucleate boiling occurs in the working fluid, is set to 130 ° C. or less, and heat is generated to 130 ° C. or less. By reducing the temperature of the heat transfer surface of the body, the formation of a vapor film on the heat transfer surface of the heating element is suppressed, and the heating element can be effectively cooled by the working fluid. The working fluid used in the present invention may be other than water, and for example, it can be a liquid having surface tension such as a low-temperature fluid, a refrigerant, or an organic solvent. For example, when water containing about 0.1% by volume of nanofluid is used as the working fluid, a nanofluid layer is formed on the heat transfer surface of the heating element by evaporation of the working fluid. be able to. In the present invention, the “nanofluid” may have an average particle diameter of, for example, 10 nm to 30 nm, 20 to 25 nm, or about 21 nm. The material of “nanofluid” may be TiO 2 .
発熱体の作動流体に浸漬する部分の表面に設ける冷却部材としての多孔質体は、作動流体を発熱体の伝熱面へ供給して発熱体の伝熱面で作動流体の膜沸騰が生じることを抑制できるものであればよい。当該多孔質体としては、図４（Ｂ）に示すように毛細管現象により作動流体を発熱体の表面に供給する作動流体供給部と、発熱体の表面で発生した蒸気を作動流体中へ排出する蒸気排出部とを備えるのが好ましい。このような構成によれば、図５に示すように、多孔質体の作動流体供給部が毛細管現象により作動流体を発熱体の表面に供給すると同時に、多孔質体の蒸気排出部が発熱体の表面で発生した蒸気を作動流体中へ排出することができる。このように、作動流体の供給と蒸気の排出を別個の経路を用いて行うことで、より良好に作動流体を発熱体の伝熱面へ供給して蒸気膜が生じることを抑制するとともに、蒸気が発熱体の伝熱面を覆うことで限界熱流束が制限されるという問題を回避することが可能となる。多孔質体は、図４（Ｂ）に示すようなハニカム状の構造であってもよい。 The porous body as a cooling member provided on the surface of the part of the heating element that is immersed in the working fluid supplies the working fluid to the heat transfer surface of the heating element and causes film boiling of the working fluid on the heat transfer surface of the heating element. What is necessary is just to be able to suppress this. As the porous body, as shown in FIG. 4 (B), a working fluid supply unit that supplies a working fluid to the surface of the heating element by capillary action, and vapor generated on the surface of the heating element is discharged into the working fluid. It is preferable to provide a steam discharge part. According to such a configuration, as shown in FIG. 5, the working fluid supply unit of the porous body supplies the working fluid to the surface of the heating element by capillarity, and at the same time, the vapor discharge unit of the porous body serves as the heating element. Steam generated on the surface can be discharged into the working fluid. As described above, the supply of the working fluid and the discharge of the steam are performed using separate paths, so that the working fluid can be supplied to the heat transfer surface of the heat generating body better and the generation of the steam film can be suppressed. However, it is possible to avoid the problem that the critical heat flux is limited by covering the heat transfer surface of the heating element. The porous body may have a honeycomb structure as shown in FIG.
多孔質体における作動流体供給部を構成する多孔質は、たとえばコーディライト等のセラミックスまたは焼結金属とすることができる。特に酸化物等の濡れ性の良い多孔質体、または、プラズマ照射等の濡れ性が向上する加工が施された多孔質体で構成されるのが望ましい。 The porous material constituting the working fluid supply unit in the porous material may be ceramics such as cordierite or sintered metal, for example. In particular, it is desirable to be composed of a porous body with good wettability such as oxide or a porous body that has been processed to improve wettability such as plasma irradiation.
なお、多孔質体は、円形、格子状、ハニカム状等とすることができる。また図５では作動流体供給部及び蒸気排出部が上方の発熱体の表面及び下方の作動流体側に直交するように図示してあるが、作動流体供給部及び蒸気排出部は、発熱体の表面と作動流体に接する面との間の経路をそれぞれ与えるものであれば、直交せずに、例えば、湾曲した経路や折れ曲がった経路となるように構成されていてもよい。また、本実施形態では、多孔質体が有する矩形状の孔が蒸気排出部として機能するが、当該孔の形状は特に限定されず、その他の多角形状、円形状、楕円形状等であってもよい。また、当該孔は多孔質体が元々備えている孔であってもよいし、多孔質体に形成した孔であってもよい。 The porous body can be circular, lattice, honeycomb or the like. In FIG. 5, the working fluid supply unit and the steam discharge unit are illustrated so as to be orthogonal to the surface of the upper heating element and the lower working fluid side. As long as the path between the surface and the surface in contact with the working fluid is respectively provided, the path may be configured to be, for example, a curved path or a bent path without being orthogonal. In the present embodiment, the rectangular holes of the porous body function as a vapor discharge part, but the shape of the holes is not particularly limited, and may be other polygonal shapes, circular shapes, elliptical shapes, or the like. Good. The hole may be a hole originally provided in the porous body, or may be a hole formed in the porous body.
また、多孔質体の形態は特に限定されず、例えば多孔質粒子の集合体で構成されていてもよく、多孔質層で構成されていてもよい。 In addition, the form of the porous body is not particularly limited, and for example, it may be composed of an aggregate of porous particles or may be composed of a porous layer.
（実施形態２）
図６は、実施形態２に係るプール沸騰方式による発熱体の冷却方式を説明するための図である。図６において（Ａ）は実施形態２に係る発熱体及び多孔質体の模式図であり、（Ｂ）は実施形態２に係る多孔質体の平面図であり、（Ｃ）は実施形態２に係る発熱体及び多孔質体を冷却するための容器内へ浸漬した状態を示す模式図である。
(Embodiment 2)
FIG. 6 is a diagram for explaining a cooling method of the heating element by the pool boiling method according to the second embodiment. 6A is a schematic view of a heating element and a porous body according to the second embodiment, FIG. 6B is a plan view of the porous body according to the second embodiment, and FIG. It is a schematic diagram which shows the state immersed in the container for cooling the heat generating body and porous body which concern.
実施形態２に係る発熱体の冷却方法は、上記実施形態１に対して、多孔質体の構造が異なっている。具体的には、多孔質体が、発熱体側に設けられた第１の多孔質体と、作動流体側に設けられた第２の多孔質体とを備えた積層構造に構成された冷却部材であり、第１の多孔質体は、毛細管現象により作動流体を前記発熱体の表面に供給する第１の作動流体供給部と、発熱体の表面で発生した蒸気を第２の多孔質体側へ排出する第１の蒸気排出部とを備え、第２の多孔質体は、作動流体を第１の多孔質体に供給する第２の作動流体供給部と、第１の多孔質体から排出された蒸気を作動流体中へ排出する第２の蒸気排出部とを備え、第１の多孔質体よりも作動流体の透過率が大きい多孔質体で形成されている。このような構成によれば、高温になっている発熱体の表面に冷却部材としての多孔質体を設け、この状態で発熱体を作動流体中に浸漬するため、発熱体の伝熱面の温度が作動流体の膜沸騰が起こる領域（膜沸騰域）の温度であっても、多孔質体が作動流体を伝熱面へ供給することができる。このため、発熱体の伝熱面で作動流体の膜沸騰が生じることを良好に抑制し、速やかに伝熱面温度を作動流体の核沸騰が起こる領域（核沸騰域）となる過熱度まで低下させることができる。従って、発熱体の伝熱面に蒸気膜が生じることが抑制され、作動流体によって効果的に発熱体を冷却することができる。 The heating element cooling method according to the second embodiment is different from the first embodiment in the structure of the porous body. Specifically, the porous body is a cooling member configured in a laminated structure including a first porous body provided on the heating element side and a second porous body provided on the working fluid side. The first porous body includes a first working fluid supply unit that supplies a working fluid to the surface of the heating element by capillary action, and discharges vapor generated on the surface of the heating body to the second porous body side. And a second porous body discharged from the first porous body and a second working fluid supply section that supplies the working fluid to the first porous body. And a second vapor discharge portion that discharges the vapor into the working fluid, and is formed of a porous body that has a larger working fluid permeability than the first porous body. According to such a configuration, since the porous body as a cooling member is provided on the surface of the heating element that is at a high temperature, and the heating element is immersed in the working fluid in this state, the temperature of the heat transfer surface of the heating element Even when the temperature of the working fluid is in a region where film boiling occurs (film boiling region), the porous body can supply the working fluid to the heat transfer surface. For this reason, it is well suppressed that film boiling of the working fluid occurs on the heat transfer surface of the heating element, and the temperature of the heat transfer surface is quickly reduced to the degree of superheat that becomes the region where the fluid nucleate boils (nuclear boiling region). Can be made. Therefore, the generation of a vapor film on the heat transfer surface of the heating element is suppressed, and the heating element can be effectively cooled by the working fluid.
第１の多孔質体の第１の作動流体供給部は、毛細管現象により発熱体の表面に作動流体を供給する。第１の多孔質体の第１の蒸気排出部は、発熱体からの熱により発生した蒸気を、発熱体の表面から第２の多孔質体側へ排出する。例えば、第１の多孔質体を多孔質層で構成し、多数の矩形状の孔を有するメッシュ構造を有し、矩形状の孔の周囲の格子状の多孔質層部分が毛細管現象により発熱体の表面に作動流体を供給する第１の作動流体供給部として機能し、矩形状の孔が発熱体の表面で発生した蒸気を第２の多孔質体側へ排出する第１の蒸気排出部として機能する構成としてもよい。このように作動流体の供給と蒸気の排出を別個の経路を用いて行うことにより、蒸気が発熱体の表面を覆ってしまい限界熱流束が制限されるという問題の発生を抑制することができる。また第２の多孔質体は、例えば、第１の多孔質体と同様に、多孔質層で構成し、多数の矩形状の孔を有するメッシュ構造を有し、矩形状の孔の周囲の格子状の多孔質層部分が第１の多孔質体に作動流体を供給する第２の作動流体供給部として機能し、矩形状の孔が第１の多孔質体から排出された蒸気を作動流体中へ排出する第２の蒸気排出部として機能する構成としてもよい。第２の多孔質体は、第１の多孔質体に比べて作動流体の透過率が大きく、作動流体を保持する機能を有し、第２の多孔質体上部で合体気泡が滞留する間にも、速やかに第１の多孔質体への作動流体の供給が行われるように機能する。 The first working fluid supply unit of the first porous body supplies the working fluid to the surface of the heating element by capillary action. The first vapor discharge unit of the first porous body discharges the steam generated by the heat from the heating element from the surface of the heating element to the second porous body side. For example, the first porous body is composed of a porous layer, has a mesh structure having a large number of rectangular holes, and the lattice-shaped porous layer portion around the rectangular holes is heated by a capillary phenomenon. Functions as a first working fluid supply unit that supplies a working fluid to the surface of the heat exchanger, and a rectangular hole functions as a first steam discharge unit that discharges steam generated on the surface of the heating element to the second porous body side. It is good also as composition to do. Thus, by supplying the working fluid and discharging the steam using separate paths, it is possible to suppress the occurrence of the problem that the steam covers the surface of the heating element and the limit heat flux is limited. Further, the second porous body is formed of a porous layer, for example, like the first porous body, has a mesh structure having a large number of rectangular holes, and a lattice around the rectangular holes. The porous layer portion having a shape functions as a second working fluid supply section for supplying the working fluid to the first porous body, and the rectangular holes allow the vapor discharged from the first porous body to flow into the working fluid. It is good also as a structure which functions as a 2nd steam discharge part discharged | emitted. The second porous body has a larger working fluid permeability than the first porous body, has a function of holding the working fluid, and the united bubbles stay in the upper part of the second porous body. Also, the working fluid is quickly supplied to the first porous body.
第２の多孔質体は、多孔質体が有する孔半径を第１の多孔質体の孔半径より大きくして作動流体を通しやすくすることで、第１の多孔質体の透過率よりも作動流体の透過率を大きくすることができる。ここで、多孔質体が有する孔半径は、各多孔質体が元々備えている孔の半径であってもよいし、各多孔質体に形成した孔の半径であってもよい。ここで、多孔質体の孔の形状は、多角形状、円形状、楕円形状等、種々の形状とすることが可能であるが、本発明において「孔半径」は、そのような種々の孔形状における外接円の半径を示す。さらに、第２の多孔質体は、多孔質体の空隙率を第１の多孔質体の空隙率より大きくして作動流体を通しやすくすることで、第１の多孔質体の透過率よりも作動流体の透過率を大きくすることができる。多孔質体の空隙率は、例えば、多孔質体の製造工程において金属粉末と混合させるバインダーの粒径・量などを調整することによって大きくすることができる。 The second porous body operates more than the permeability of the first porous body by making the pore radius of the porous body larger than the pore radius of the first porous body to facilitate the passage of the working fluid. The fluid permeability can be increased. Here, the pore radius of the porous body may be a radius of a hole originally provided in each porous body, or may be a radius of a hole formed in each porous body. Here, the shape of the pores of the porous body can be various shapes such as a polygonal shape, a circular shape, and an elliptical shape. In the present invention, the “pore radius” refers to such various pore shapes. The radius of the circumscribed circle at. Furthermore, the second porous body has a porosity of the porous body larger than that of the first porous body to facilitate the passage of the working fluid, so that the permeability of the first porous body is higher than that of the first porous body. The permeability of the working fluid can be increased. The porosity of the porous body can be increased, for example, by adjusting the particle size / amount of the binder to be mixed with the metal powder in the manufacturing process of the porous body.
第１の多孔質体の形状としては、多孔質体への接触面積が大きくなるため発熱体の表面で発生した蒸気を水中へ逃がすための孔の大きさは小さいほうがよく、例えば、１００〜２０００μｍとすることができる。また、多孔質底部を通過する場合の圧力損失を小さくできるため、発熱体の表面で発生した蒸気を水中へ逃がすための孔と孔の間隔は小さい方がよく、例えば、１００〜１０００μｍとすることができる。 As the shape of the first porous body, since the contact area with the porous body is increased, the size of the hole for releasing the steam generated on the surface of the heating element into water is preferably small, for example, 100 to 2000 μm. It can be. In addition, since the pressure loss when passing through the porous bottom can be reduced, the gap between the holes for releasing the steam generated on the surface of the heating element into the water should be small, for example, 100 to 1000 μm. Can do.
第１の多孔質体における第１の作動流体供給部を構成する多孔質は、たとえばコーディライト等のセラミックスまたは焼結金属とすることができる。特に酸化物等の濡れ性の良い多孔質体、または、プラズマ照射等の濡れ性が向上する加工が施された多孔質体で構成されるのが望ましい。 The porous material constituting the first working fluid supply section in the first porous body can be ceramics such as cordierite or sintered metal, for example. In particular, it is desirable to be composed of a porous body with good wettability such as oxide or a porous body that has been processed to improve wettability such as plasma irradiation.
第１の多孔質体は、第１の作動流体供給部において、液体の蒸発が起これば毛細管現象により発熱体の表面に作動流体を供給するが、毛管力による液体供給の限界メカニズムを考慮すれば、毛細管の長さ（すなわち、第１の多孔質体の厚さ）は薄いほうがよりその限界、すなわち「限界熱流束」を高くすることができる。一方、図３において、高熱流束条件下の発熱体の表面上で蒸気塊が形成される様子を示したが、その蒸気塊の体積は時間と共に増大し、やがて発熱体の表面から切断離脱する。この蒸気塊と発熱体の表面近傍をより詳細に説明すれば、蒸気塊と発熱体の表面の間（すなわち蒸気塊の底部）には、有限厚さの液膜（一般に、マクロ液膜と呼ばれる）が存在する。このような高熱流束条件下においては、蒸気塊がマクロ液膜上に滞留している間に蒸気塊底部のマクロ液膜が蒸発消耗し尽くすときにバーンアウトが発生する。このときの熱流束が「限界熱流束」と呼ばれる。第１の多孔質体の厚さは、上述の通り毛管力による液体供給の限界メカニズム（毛管限界メカニズム）から薄いほうがよいが、薄過ぎてマクロ液膜の厚さと同程度であると、第１多孔質体の発熱体の表面近傍で液枯れが生じやすく、限界熱流束が小さくなる。 The first porous body supplies the working fluid to the surface of the heating element by capillary action when the liquid evaporates in the first working fluid supply section. However, considering the limit mechanism of the liquid supply by capillary force. For example, as the capillary length (that is, the thickness of the first porous body) is thinner, the limit, that is, the “critical heat flux” can be increased. On the other hand, FIG. 3 shows a state in which a vapor mass is formed on the surface of the heating element under a high heat flux condition, but the volume of the vapor mass increases with time and eventually detaches from the surface of the heating element. . If the vapor mass and the vicinity of the surface of the heating element are described in more detail, a liquid film having a finite thickness (generally called a macro liquid film) is formed between the vapor mass and the surface of the heating element (that is, the bottom of the vapor mass). ) Exists. Under such a high heat flux condition, burnout occurs when the macro liquid film at the bottom of the vapor mass is exhausted and exhausted while the vapor mass remains on the macro liquid film. The heat flux at this time is called “limit heat flux”. As described above, the thickness of the first porous body is preferably thinner from the limit mechanism of liquid supply by capillary force (capillary limit mechanism), but if the thickness is too thin and is approximately the same as the thickness of the macro liquid film, Liquid withering tends to occur near the surface of the porous heating element, and the critical heat flux is reduced.
このように、発熱体の表面に設ける多孔質体の厚さは、毛管限界メカニズムの観点からは薄いほうがよいが、マクロ液膜の厚さより薄いと多孔質体内部で液枯れが生じやすく、限界熱流束が小さくなるという問題がある。そこで、本発明では、発熱体の表面に設ける多孔質体を第１の多孔質体とし、その上に（作動流体側に）、第１の多孔質体よりも作動流体の透過率が大きい第２の多孔質体を設けている。このような構成によれば、第１の多孔質体とその上方の蒸気塊との間に、作動流体を第１の多孔質体に向かって潤沢に液体を供給する第２の多孔質体が存在するため、第１の多孔質体の厚さを薄くしても、液枯れの発生が抑制され、限界熱流束が小さくなることを防ぐことができる。また、第２の多孔質体の液供給量は多いほど好ましいため、第２の多孔質体の厚みも大きくするのが好ましい。具体的には、例えば、第１の多孔質体の厚さを１００μｍ程度と薄くする場合、第２の多孔質体の厚さは１〜２ｍｍ以上程度とするのが好ましい。 As described above, the thickness of the porous body provided on the surface of the heating element is preferably thin from the viewpoint of the capillary limit mechanism. There is a problem that the heat flux becomes small. Therefore, in the present invention, the porous body provided on the surface of the heating element is the first porous body, on which (on the working fluid side) the first working fluid has a higher permeability of the working fluid than the first porous body. Two porous bodies are provided. According to such a configuration, the second porous body that supplies the working fluid to the first porous body in an abundant manner between the first porous body and the vapor mass above the first porous body. Therefore, even if the thickness of the first porous body is reduced, the occurrence of liquid withering is suppressed, and the critical heat flux can be prevented from being reduced. Moreover, since it is so preferable that there are many liquid supply amounts of a 2nd porous body, it is preferable to also enlarge the thickness of a 2nd porous body. Specifically, for example, when the thickness of the first porous body is as thin as about 100 μm, the thickness of the second porous body is preferably about 1 to 2 mm or more.
第２の多孔質体は、コーディライト等のセラミックスで形成してもよいが、特に加工性や強度の点から金属で形成するのが好ましい。特に酸化物等の濡れ性の良い多孔質体、または、プラズマ照射等の濡れ性が向上する加工が施された多孔質体で構成されるのが望ましい。 The second porous body may be formed of ceramics such as cordierite, but is preferably formed of metal from the viewpoint of workability and strength. In particular, it is desirable to be composed of a porous body with good wettability such as oxide or a porous body that has been processed to improve wettability such as plasma irradiation.
なお、第１の多孔質体及び第２の多孔質体は、円形、格子状、ハニカム状等とすることができる。また図７では第１及び第２の作動流体供給部及び蒸気排出部が上方の発熱体の表面及び下方の作動流体側に直交するように図示してあるが、第１及び第２の作動流体供給部及び蒸気排出部は、発熱体の表面と作動流体に接する面との間の経路をそれぞれ与えるものであれば、直交せずに、例えば、湾曲した経路や折れ曲がった経路となるように構成されていてもよい。また、本実施形態では、各多孔質体が有する矩形状の孔が蒸気排出部として機能するが、当該孔の形状は特に限定されず、その他の多角形状、円形状、楕円形状等であってもよい。また、当該孔は各多孔質体が元々備えている孔であってもよいし、各多孔質体に形成した孔であってもよい。 Note that the first porous body and the second porous body may be circular, lattice-shaped, honeycomb-shaped, or the like. In FIG. 7, the first and second working fluid supply units and the steam discharge unit are illustrated so as to be orthogonal to the surface of the upper heating element and the lower working fluid side. As long as the supply unit and the steam discharge unit respectively provide a path between the surface of the heating element and the surface in contact with the working fluid, the supply unit and the steam discharge unit are configured to be, for example, a curved path or a bent path without being orthogonal to each other. May be. Further, in this embodiment, the rectangular holes of each porous body function as a vapor discharge part, but the shape of the holes is not particularly limited, and may be other polygonal shapes, circular shapes, elliptical shapes, etc. Also good. Further, the holes may be holes originally provided in each porous body, or may be holes formed in each porous body.
また、第１の多孔質体と第２の多孔質体との形態は特に限定されず、例えば、第１の多孔質体及び第２の多孔質体が、いずれも多孔質粒子の集合体で構成されていてもよい。また、第１の多孔質体及び第２の多孔質体が、いずれも多孔質層で構成されていてもよい。さらに、第１の多孔質体及び第２の多孔質体のいずれか一方が多孔質粒子の集合体で構成されており、他方が多孔質層で構成されていてもよい。第１の多孔質体、第２の多孔質体が、多孔質粒子の集合体で構成されている場合、例えば複数の多孔質粒子間の隙間が蒸気排出部としての機能を有し、当該隙間の周囲の部材が作動流体供給部として機能する構成とすることができる。 In addition, the form of the first porous body and the second porous body is not particularly limited. For example, the first porous body and the second porous body are both aggregates of porous particles. It may be configured. Moreover, both the 1st porous body and the 2nd porous body may be comprised by the porous layer. Furthermore, one of the first porous body and the second porous body may be composed of an aggregate of porous particles, and the other may be composed of a porous layer. In the case where the first porous body and the second porous body are composed of an aggregate of porous particles, for example, a gap between a plurality of porous particles has a function as a vapor discharge portion, and the gap It is possible to adopt a configuration in which the members around are functioning as a working fluid supply unit.
また、冷却部材の積層構造は、第１の多孔質体と、第２の多孔質体とで構成されたものに限定されず、第２の多孔質体の作動流体側にさらに第３の多孔質体を設けて、全体で３層の積層構造としてもよい。この場合、第３の多孔質体は、作動流体を第２の多孔質体に供給する作動流体供給部と、第２の多孔質体から排出された蒸気を作動流体中へ排出する蒸気排出部とを備えている。同様に、冷却部材の積層構造は、第２の多孔質体の作動流体側に複数の多孔質体を積層させて全体で４層以上の構成としてもよい。 Further, the laminated structure of the cooling member is not limited to the one constituted by the first porous body and the second porous body, and the third porous body is further provided on the working fluid side of the second porous body. A material body may be provided to form a three-layer structure as a whole. In this case, the third porous body includes a working fluid supply section that supplies the working fluid to the second porous body, and a steam discharge section that discharges the steam discharged from the second porous body into the working fluid. And. Similarly, the laminated structure of the cooling member may be configured to have a total of four or more layers by laminating a plurality of porous bodies on the working fluid side of the second porous body.
本発明は、原子炉圧力容器の冷却の他、種々の電子機器、その他の高発熱密度を有する熱機器全般の冷却に適用可能である。たとえば、核融合炉のダイバータ冷却、キャピラリーポンプループの高性能化、半導体レーザ、データセンターのサーバの冷却、フロン冷却式チョッパ制御装置、パワー電子機器等に用いることができる。または、ガラスやアルミの溶融炉の側部や底部から周囲環境へ放散する熱を節減して、高温作業環境を改善する水冷ジャケットに適用可能である。さらに、大型ごみ焼却炉等の耐火壁を外部から冷却して損傷を軽減するための、耐火壁側部や耐火壁底部に設置する水冷ジャケットに適用可能である。 The present invention is applicable not only to cooling of a reactor pressure vessel but also to cooling of various electronic devices and other thermal devices having a high heat generation density. For example, it can be used for divertor cooling of fusion reactors, high performance of capillary pump loops, semiconductor lasers, server cooling of data centers, CFC-controlled chopper control devices, power electronic devices, and the like. Alternatively, it can be applied to a water-cooled jacket that improves the high-temperature work environment by reducing the heat dissipated from the side or bottom of a glass or aluminum melting furnace to the surrounding environment. Furthermore, the present invention can be applied to a water-cooled jacket installed on the side of the fire wall or the bottom of the fire wall to reduce damage by cooling the fire wall such as a large garbage incinerator from the outside.
以下に本発明を実施例でさらに詳細に説明するが、本発明はこれらに限定されるものではない。 The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.
図８に実施例で用いたクエンチ実験の試験装置を示す。発熱体として円柱状の銅ブロック試験体を準備した。銅ブロック試験体の底面が伝熱面であり、直径３０ｍｍ、高さ１５０ｍｍであった。銅ブロック試験体の加熱は、上部より挿入した４本のカートリッジヒーターで行い、３７０℃程度に保持した。次に、銅ブロック試験体の伝熱面には厚み１０ｍｍのハニカム多孔質体ａ（図９のハニカム構造体（a）装着）、厚み１ｍｍのハニカム多孔質体ｂ（図９のハニカム構造体（b）装着）をそれぞれ別途装着し、各２回の実験を行った。これら２種類のハニカム多孔質体ａ、ｂはいずれも長峰製作所製ハニカム多孔質体（ＮＡハニカム）であり、主成分はカルシウムアルミネート、溶解シリカ、二酸化チタンで、有効熱伝導率は４［Ｗ／（ｍ・Ｋ）］である。また、銅ブロック試験体の温度測定のために、伝熱面上より距離１５ｍｍの位置の円柱状の銅ブロック試験体の中心軸上に直径１ｍｍのＫ型シース熱電対を挿入した。
次に、加熱を止めたハニカム多孔質体が装着された銅ブロック試験体を、ハニカム多孔質体側から作動流体として蒸留水が入った容器へ浸漬させた。このとき、液温は飽和状態とした。銅ブロック試験体を蒸留水中に浸漬させた状態で、１０００秒経過するまでの銅ブロック試験体の温度測定を行った。
また、別途、ハニカム多孔質体の代わりに、厚さ５ｍｍの多孔質板を発熱体底面に装着した以外は同様にクエンチ実験を行い、１０００秒経過するまでの銅ブロック試験体の温度測定を行った（図９の多孔質板（５ｍｍ）装着）。
また、別途、ハニカム多孔質体を装着しない以外は同様にクエンチ実験を行い、１０００秒経過するまでの銅ブロック試験体の温度測定を行った（図９の銅ブロック試験体（蒸留水））。
さらに、別途、ハニカム多孔質体を装着せず、且つ、作動流体を０．１体積％のＴｉＯ2で形成された粒径２１ｎｍのナノ流体を含んだ蒸留水とした以外は同様にクエンチ実験を行い、１０００秒経過するまでの銅ブロック試験体の温度測定を行った（図９の銅ブロック試験体（ナノ流体０．１Ｖ％））。
FIG. 8 shows a test apparatus for the quench experiment used in the examples. A cylindrical copper block test body was prepared as a heating element. The bottom surface of the copper block specimen was a heat transfer surface, and had a diameter of 30 mm and a height of 150 mm. The copper block test specimen was heated with four cartridge heaters inserted from above, and maintained at about 370 ° C. Next, a honeycomb porous body a having a thickness of 10 mm (mounted with the honeycomb structure (a) in FIG. 9) and a honeycomb porous body b having a thickness of 1 mm (the honeycomb structure in FIG. b) Mounting) was mounted separately, and two experiments were performed. These two types of honeycomb porous bodies a and b are both Nagamine's honeycomb porous bodies (NA honeycomb), the main components are calcium aluminate, dissolved silica and titanium dioxide, and the effective thermal conductivity is 4 [W / (M · K)]. Further, in order to measure the temperature of the copper block specimen, a K-type sheath thermocouple having a diameter of 1 mm was inserted on the central axis of the cylindrical copper block specimen at a distance of 15 mm from the heat transfer surface.
Next, the copper block test body on which the heated porous honeycomb body was mounted was immersed in a container containing distilled water as a working fluid from the honeycomb porous body side. At this time, the liquid temperature was saturated. With the copper block specimen immersed in distilled water, the temperature of the copper block specimen was measured until 1000 seconds passed.
Separately, instead of the honeycomb porous body, a quench experiment was performed in the same manner except that a porous plate having a thickness of 5 mm was mounted on the bottom surface of the heating element, and the temperature of the copper block specimen was measured until 1000 seconds passed. (Installation of porous plate (5 mm) in FIG. 9).
Separately, a quench experiment was performed in the same manner except that the honeycomb porous body was not attached, and the temperature of the copper block test specimen was measured until 1000 seconds passed (copper block test specimen (distilled water) in FIG. 9).
Furthermore, a quenching experiment was conducted in the same manner except that the honeycomb porous body was not attached and the working fluid was distilled water containing a nanofluid having a particle size of 21 nm formed of 0.1% by volume of TiO 2. The temperature of the copper block test specimen was measured until 1000 seconds passed (copper block test specimen of FIG. 9 (nanofluid 0.1 V%)).
図９に上記試験結果を示す。図９によれば、多孔質体非装着時には蒸留水の飽和温度に達するまで約８５０秒かかっているが、多孔質体装着時にはすべての場合において蒸留水の飽和温度に達するまでの時間が大幅に短縮されていることがわかった。
また、厚さ５ｍｍの多孔質板を装着した場合と、厚さ５ｍｍのハニカム多孔質体を装着した場合とを比較すると、厚さ５ｍｍのハニカム多孔質体を装着した場合のほうが蒸留水の飽和温度に達するまでの時間が短いことがわかった。
FIG. 9 shows the test results. According to FIG. 9, it takes about 850 seconds to reach the saturation temperature of distilled water when the porous body is not attached, but the time to reach the saturation temperature of distilled water is significantly increased in all cases when the porous body is attached. I found that it was shortened.
In addition, when a case where a porous plate having a thickness of 5 mm is attached to a case where a porous body having a thickness of 5 mm is attached, the case where the honeycomb porous body having a thickness of 5 mm is attached is saturated with distilled water. It was found that the time to reach the temperature was short.
図１０に、厚み１０ｍｍ、１ｍｍの２種類のハニカム多孔質体ａ、ｂを装着したときの、銅ブロック試験体の伝熱面をＩＲカメラで撮影することで得られた伝熱面温度分布の観察写真を示す。ＩＲカメラはＦＬＩＲ社製Ａ６７００ｓｃを用いた。伝熱面を通った光は伝熱面下部に設置された金ミラーで反射し、ＩＲカメラに垂直に入射することで温度分布を得ている。また、表１に当該温度分布の評価結果を示す。伝熱面と作動流体（試験液体）との接触界面温度Ｔｓは下記式（１）から求めた。
式（１）： ［（ｋρＣp）A 1/2・ＴA＋（ｋρＣp）B 1/2・ＴB］／［（ｋρＣp）A 1/2＋（ｋρＣp）B 1/2］
FIG. 10 shows the heat transfer surface temperature distribution obtained by photographing the heat transfer surface of the copper block test body with an IR camera when two types of porous honeycomb bodies a and b having a thickness of 10 mm and 1 mm are mounted. An observation photograph is shown. The IR camera used was A6700sc manufactured by FLIR. The light passing through the heat transfer surface is reflected by a gold mirror installed at the lower part of the heat transfer surface, and enters the IR camera vertically to obtain a temperature distribution. Table 1 shows the evaluation results of the temperature distribution. The contact interface temperature Ts between the heat transfer surface and the working fluid (test liquid) was obtained from the following formula (1).
Formula (1): [(kρC p ) A 1/2 · T A + (kρC p ) B 1/2 · T B ] / [(kρC p ) A 1/2 + (kρC p ) B 1/2 ]
式（１）において、Ａはハニカム多孔質体、Ｂは水の物性値を用いている（Ａ：ρ＝１６７６ｋｇ／ｍ3、Ｃp＝０．５６２ｋＪ／（ｋｇ・Ｋ）、ｋ＝４ｗ／（ｍ・ｋ）、Ｂ：ρ＝９５８ｋｇ／ｍ3、Ｃｐ＝４．２１７ｋＪ／（ｋｇ・Ｋ）、ｋ＝０．０６８ｗ／（ｍ・ｋ））。またＴA＝Ｔ２、ＴB＝２７３．１５Ｋを用いている。
その結果、伝熱面に接触しているハニカム多孔質体ａの温度はハニカム多孔質体ｂに比べて低いため、ハニカム多孔質体ａはハニカム多孔質体ｂに比べてより早い時間でクエンチしたと考えられる。
In the formula (1), A is a honeycomb porous body, B is a physical property value of water (A: ρ = 1676 kg / m 3 , C p = 0.562 kJ / (kg · K), k = 4 w / (M · k), B: ρ = 958 kg / m 3 , Cp = 4.217 kJ / (kg · K), k = 0.068 w / (m · k)). Further, T A = T2 and T B = 273.15K are used.
As a result, since the temperature of the honeycomb porous body a in contact with the heat transfer surface is lower than that of the honeycomb porous body b, the honeycomb porous body a was quenched in an earlier time than the honeycomb porous body b. it is conceivable that.
Claims (6)
発熱体の作動流体に浸漬する部分の表面に冷却部材としての多孔質体を設ける工程と、
前記多孔質体が設けられた発熱体の表面を前記作動流体中に浸漬して、前記多孔質体が設けられた発熱体の表面の温度を低下させる工程と、
を備えた発熱体の冷却方法。 In the cooling method by the boiling method in which the heating element is cooled at least partially by immersing the heating element in the working fluid of the container containing the working fluid,
Providing a porous body as a cooling member on the surface of the portion immersed in the working fluid of the heating element;
Immersing the surface of the heating element provided with the porous body in the working fluid to reduce the temperature of the surface of the heating element provided with the porous body;
A method for cooling a heating element.
前記多孔質体が設けられた発熱体の表面を前記作動流体中に浸漬して、前記多孔質体が設けられた発熱体の表面の温度を前記作動流体に核沸騰が起こる温度領域となる過熱度まで低下させる工程と、
を備えた請求項１に記載の発熱体の冷却方法。 Providing a porous body on the surface of the portion immersed in the working fluid for a heating element in which the surface temperature of the portion immersed in the working fluid is in a temperature region where film boiling occurs in the working fluid;
The surface of the heating element provided with the porous body is immersed in the working fluid, and the temperature of the surface of the heating element provided with the porous body is overheated to be a temperature region where nucleate boiling occurs in the working fluid. Reducing the process to a degree,
The heating element cooling method according to claim 1, comprising:
前記作動流体に核沸騰が起こる温度領域となる過熱度が１３０℃以下である請求項２に記載の発熱体の冷却方法。 The working fluid is water, and the heating element is cooled under atmospheric pressure.
The method of cooling a heating element according to claim 2, wherein a superheat degree that is a temperature region in which nucleate boiling occurs in the working fluid is 130 ° C or less.
前記第１の多孔質体は、毛細管現象により前記作動流体を前記発熱体の表面に供給する第１の作動流体供給部と、前記発熱体の表面で発生した蒸気を前記第２の多孔質体側へ排出する第１の蒸気排出部とを備え、
前記第２の多孔質体は、前記作動流体を前記第１の多孔質体に供給する第２の作動流体供給部と、前記第１の多孔質体から排出された蒸気を前記作動流体中へ排出する第２の蒸気排出部とを備え、前記第１の多孔質体よりも前記作動流体の透過率が大きい多孔質体で形成されている請求項１〜３のいずれか一項に記載の発熱体の冷却方法。 The porous body is a cooling member configured in a laminated structure including a first porous body provided on the heating element side and a second porous body provided on the working fluid side,
The first porous body includes a first working fluid supply unit that supplies the working fluid to the surface of the heating element by capillary action, and vapor generated on the surface of the heating element on the second porous body side. A first steam discharge section for discharging to
The second porous body includes a second working fluid supply unit that supplies the working fluid to the first porous body, and vapor discharged from the first porous body into the working fluid. A second vapor discharge unit for discharging, and is formed of a porous body having a larger permeability of the working fluid than the first porous body. Cooling method of the heating element.
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| CN113834849A (en) * | 2020-06-23 | 2021-12-24 | 上海交通大学 | Visual test device for researching influence of surface characteristics on critical heat flux density |
| WO2023167087A1 (en) * | 2022-03-01 | 2023-09-07 | 国立大学法人九州大学 | Cooling member, cooler, cooling device, and cooling member manufacturing method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113834849A (en) * | 2020-06-23 | 2021-12-24 | 上海交通大学 | Visual test device for researching influence of surface characteristics on critical heat flux density |
| WO2023167087A1 (en) * | 2022-03-01 | 2023-09-07 | 国立大学法人九州大学 | Cooling member, cooler, cooling device, and cooling member manufacturing method |
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