Patent Publication Number: US-2022228819-A1

Title: Heat exchanger member, heat exchanger, and cooling system

Description:
TECHNICAL FIELD 
     The present invention relates to a heat exchanger member using a refrigerant having a cooling effect compared to water, in which a metal surface is provided with characteristics other than the characteristics inherent to the metal, and a device including the member. 
     BACKGROUND ART 
     In a cooling system using a refrigerant, the refrigerant circulates in the system during operation, an object is cooled by vaporization of the refrigerant flowing in a heat exchanger in a cooling unit, and the refrigerant is coded and liquefied by outside air or the like in the heat exchanger of a heat dissipation unit. In the above cooling system, the size of the system which may impose a limitation in the installation and the energy consumption of the pump for circulating the refrigerant are determined by the efficiency of releasing heat to the outside in the heat exchanger of the heat dissipation unit, to liquefy the refrigerant (hereinafter, referred to as liquefaction efficiency), the efficiency of vaporizing the refrigerant in the heat exchanger of the cooling unit to take away heat (hereinafter, referred to as vaporization efficiency), and the pressure loss of the refrigerant flowing through the tube. 
     On the other hand, in recent years, the amount of information processed by semiconductor devices and the processing speed have been increasing, and high integration as a countermeasure therefor causes a limitation .in the installation of a corresponding cooling system and increases power consumption. 
     Therefore, for the freedom in the installation of a cooling system and for the reduction of the energy consumption, techniques related to liquefaction efficiency, vaporization efficiency, and pressure loss reduction have been studied. Such a technique is disclosed in, for example, Patent Literature 1. 
     Patent Literature 1 describes a method of enhancing vaporization efficiency of a cooling unit and liquefaction efficiency of a heat dissipation unit by adding a gas-liquid separating unit in a cooling system. 
     CITATIONS LIST 
     Patent Literature 
     Patent Literature 1: JP 2004-190928 A 
     SUMMAPY OF INVENTION 
     Technical Problems 
     However, in the technique of Patent Literature 1, it is necessary to separately add a gas-liquid separating unit to the cooling system, and there is a problem that the installation of the cooling system is limited and the cost is greatly increased. 
     The present invention has been made in view of the above problems, and an object of the present invention is to provide a heat exchanger member, a heat exchanger, and a cooling system that are highly efficient by providing, to a surface of a metal in contact with a refrigerant of a heat exchanger used for a cooling unit and a heat dissipation unit, characteristics not found in the metal itself with a coating film excelling in thermal conductivity and excelling in wettability with the refrigerant. 
     Solutions to Problems 
     In order to solve the above problems, a heat exchanger member of the present invention is a heat exchanger member made of metal and having a surface that comes into contact with a refrigerant when a heat exchanger formed by the heat exchanger member is operated. The heat exchanger member includes a metal oxide film provided on the surface, having protrusions, and containing crystalline carbon. An average spacing between apexes of the protrusions is greater than or equal to 20 nm and less than or equal to 80 nm, an average value of the heights of the apexes of adjacent protrusions is greater than or equal to 10 nm and less than or equal to 70 nm, and an aspect ratio which is a value obtained by dividing the average height by the average spacing is less than one. 
     Advantageous Effects of Invention 
     The present invention has an effect that a function of enhancing liquefaction and vaporization efficiency of a heat exchanger can be added to a heat exchanger member. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic view illustrating a semiconductor cooling system using a heat exchanger member according to a first embodiment of the present invention. 
         FIG. 2  is a view illustrating a heat exchanger member according to the first embodiment of the present invention. 
         FIG. 3  is a schematic view illustrating a cross section taken along line a-a in  FIG. 2 . 
         FIG. 4  is an AFM observation result of a refrigerant contact surface of the heat exchanger member according to the first embodiment of the present invention. 
         FIG. 5  is a diagram illustrating equipment for manufacturing the first embodiment of the present invention. 
         FIG. 6  is a diagram illustrating a time chart of a load electrolysis density for manufacturing the first embodiment of the present invention. 
         FIG. 7  is a view showing a liquefaction test of the first embodiment of the present invention. 
         FIG. 8  is an SEM perspective view of the first embodiment of the present invention. 
         FIG. 9  is an SEM perspective view cf a comparative example with respect to the first embodiment of the present invention. 
         FIG. 10  is a view illustrating a heat exchanger member according to a second embodiment of the present invention. 
         FIG. 11  is a schematic view illustrating a cross section taken along line a-a in  FIG. 10 . 
         FIG. 12  is an AFM observation result of a refrigerant contact surface of the heat exchanger member according to the second embodiment of the present invention. 
         FIG. 13  is a view illustrating a facility for manufacturing the second embodiment of the present invention. 
         FIG. 14  is a diagram illustrating a time chart of a load electrolysis density for manufacturing the second embodiment of the present invention. 
         FIG. 15  is a view showing a cooling test of the second embodiment of the present invention. 
         FIG. 16  is a SEM perspective view of the second embodiment of the present invention. 
         FIG. 17  is a SEM perspective view of a comparative example with respect to the second embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     First Embodiment 
     Hereinafter, embodiments of the present invention will be described with reference to  FIGS. 1 to 9 . 
     &lt;Configuration of Semiconductor Cooling System in which Member is Incorporated&gt; 
       FIG. 1  is a schematic diagram illustrating a semiconductor cooling system  100 . The semiconductor cooling system  100  includes a cooling unit (heat exchanger)  110 , a heat dissipation unit (heat exchanger)  120 , a compressor  130 , an expansion valve  140 , and the like. 
     The heat dissipation unit  120  includes a heat exchanger  121  and a fan  122 , and heat released when the refrigerant is liquefied inside the heat exchanger  121  is released to the outside of the system by the fan  122 . The heat exchanger member of the present invention means a member forming the heat exchanger  121 . In the following description, the heat exchanger member will be described as a member forming the heat exchanger  121  which is a tube in which the refrigerant is liquefied inside. 
     &lt;Configuration of Member&gt; 
       FIG. 2  and  FIG. 3 , which is a cross-sectional view taken along line a-a in  FIG. 2 , are views showing a tube forming the heat exchanger  121 , which is a specific example of a heat exchanger member of the present invention. As shown in  FIG. 3 , a crystalline carbon-containing oxide film  121 C provided with fine protrusions  121 B is provided on a metal base  121 A made of a main material (aluminum, stainless steel, copper, etc.) forming a tube. The crystalline carbon-containing oxide film  121 C having the fine protrusions  121 B as a metal oxide film containing crystalline carbon, and provides a function of enhancing the wettability between the refrigerant and the tube inner surface in contact with the refrigerant in a gas state in the heat, exchanger  121 , and enhancing the efficiency of cooling the refrigerant by the high thermal conduction rate of the contained crystalline carbon. 
     The tube is made of a metal tube such as an aluminum tube, a stainless tube, or a copper tube. The wail thickness and length of the tube are not particularly defined, and are appropriately determined according to the purpose of use. 
     The crystalline carbon-containing oxide film  121 C is an oxide of a metal same as or similar to the metal base material, containing crystalline carbon. The film thickness of the crystalline carbon-containing oxide film  121 C may be 10 nm to 300 nm. Furthermore, the film thickness of the crystalline carbon-containing oxide film  121 C is preferably 300 nm to 300 nm in order to enhance the liquefaction efficiency by utilizing the thermal conductivity of the contained crystalline carbons. The content ratio of carbon contained in the carbon-containing oxide film  121 C may be 5 at % to 50 at % at a point of 3 nm to 5 nm from the surface (the surface opposite to the surface in contact with the metal base  121 A). Furthermore, the content ratio of the crystalline carbon contained in the carbon-containing oxide film  121 C is preferably 8 at % to 40 at % at a point of 3 nm to 5 nm from the surface in order to provide characteristics given by containing the crystalline carbon and to maintain the strength of the film. 
     The crystalline carbon contained in the crystalline carbon-containing oxide film  121 C is preferably a carbon nanotube, fullerene, graphene, or the like to enhance thermal conduction. 
     The fine protrusions  121 B are provided on the surface of the crystalline carbon-containing oxide film  121 C (the surface opposite to the surface in contact with the metal base  121 A), and an average spacing between adjacent apexes of the fine protrusions  121 B is greater than or equal to 20 nm and less than or equal to 80 nm, an average value of the height of the apexes of the protrusions is greater than or equal to 10 nm and less than or equal to 70 nm, and an aspect ratio which is a value obtained by dividing the average height by the average spacing is less than one. 
     Furthermore, in order to provide higher wettability to the refrigerant, the fine protrusions  121 B more preferably have an average spacing between adjacent apexes of the fine protrusions  121 B of greater than or equal to 25 nm and less than or equal to 65 nm, an average value of the height of the apexes of the protrusions of greater than or equal to 15 nm and less than or equal to 55 nm, and an aspect ratio which is a value obtained by dividing the average height by the average spacing of less than 0.83. 
     Hereinafter, an example according to the first embodiment will be described with reference to  FIGS. 5 to 8 . The heat exchanger  121  in the example is manufactured from an aluminum tube having an outer diameter of 9 mm (inner diameter 6 mm)×220 nm. The following treatment was performed in order to provide the crystalline carbon-containing oxide film  121 C having the fine protrusions  121 B on the inner surface of the aluminum tube (metal base  121 A). 
     First, the aluminum tube (metal base  121 A) is immersed and degreased with ethanol (immersion time: 30 minutes). Thereafter, as shown in  FIG. 5 , the aluminum tube connected to the electric circuit  400  and the SUS 304 electrode  404  connected to the electric circuit  400  in a state of being inserted inside the aluminum tube so as not to contact the inner surface of the aluminum tube are immersed in the bath  300  containing the treatment liquid  301 . In the treatment liquid  301  in the bath  300 , sodium hydroxide and 0.2% single-walled carbon nanotube dispersion liquid dispersed in purified water by a dispersant are added to purified water so as to have concentrations of 0.35 g/l and 1.35 ml/l, respectively, and the temperature is adjusted so that the liquid temperature becomes 30° C. 
     Thereafter, the voltage is loaded on the aluminum tube by a rectifier  401 , a rectifier  402 , and a changeover switch  403  with the pattern illustrated in  FIG. 6 , wherein the current flowing in the direction of the arrow illustrated in  FIG. 6  is defined as the current in the + direction. 
     Finally, the aluminum tube is washed with water and dried (80° C. for 30 minutes) in a thermostatic bath. In this way, the crystalline carton-containing oxide film  121 C having a thickness of 200 nm is provided on the surface of the aluminum tube (metal base  121 A), and at the same time, the fine protrusions  121 B having an average spacing between apexes of the adjacent fine protrusions  121 B on 61 nm and an average value of heights of the fine protrusions  121 B of 50 nm are provided on the surface of the crystalline carbon-containing oxide film  121 C ( FIG. 4 ), thereby obtaining the heat exchanger  121 . 
     &lt;Demonstration Test&gt; 
     Here, characteristics required for the heat exchanger in the heat dissipation unit will be described. The heat exchanger in the heat dissipation unit takes heat from the refrigerant in a gas state that has been vaporized in the cooling unit and has a high temperature and a high pressure through the compressor, and dissipates the heat to the outside, thereby liquefying the refrigerant. At that time, it is necessary to liquefy all the refrigerant so that the refrigerant can circulate through the system. Therefore, if the liquefaction efficiency per unit area with which the refrigerant of the heat exchanger comes into contact is low, the size of the heat exchanger becomes large, which imposes a limitation in the installation of the cooling system and greatly increases the cost. 
     Furthermore, since the cooling system of the semiconductor generally has a larger heat dissipation unit than a cooling unit, the liquefaction efficiency affects the size and cost of the entire unit. Therefore, it has been required to enhance the liquefaction efficiency in the heat exchanger of the heat dissipation unit. 
     In the tube forming the heat exchanger of the present invention, the contact angle indicating wettability with the refrigerant (so-called fluorocarbons such as fluorocarbon, a mixture of methylnonafluorobutyl ether and methylnonafluoroisobutyl ether, and the like) can be made very small. For example, in the case of aluminum, the contact angle can be set to 0.67°, from 4.18° when untreated, by adopting the structure according to the present invention, so that the refrigerant is easily flowed and collected. In addition, the structure according to the present invention excels in heat exchangeability because it contains crystalline carbon excelling in thermal conductivity such as carbon nanotubes. Therefore, the heat exchanger of the present invention excels in liquefaction efficiency. 
     A heat exchanger  121  of the present invention shown in  FIGS. 2 to 4 and 8  (contact angle with a refrigerant of 0.67°, 10% content rate of crystalline carbon (at a point of 5 nm from the surface)) and a heat exchanger  522  (contact angle with a refrigerant of 4.18°, 0% content rate of crystalline carbon (at a point of 5 nm from the surface)) which is formed of a comparative untreated aluminum tube having an inner surface as shown in  FIG. 9  and having the same shape as that of the present invention are connected to silicon tubes  541  and  542  and installed outside the thermostatic bath  510  as shown in  FIG. 7 , the silicon tubes  541  and  542  being connected to refrigerant containers  531  and  532  which are installed in a thermostatic bath  510  of a liquefaction characteristic evaluation device  500  shown in  FIG. 7  and in which refrigerant is enclosed. 
     Thereafter, the inside of the thermostatic bath  510  was operated to become 70° C. to evaporate the refrigerant in the refrigerant containers  531  and  532 , the vaporized refrigerant was introduced into the heat exchangers  121  and  522 , the refrigerant cooled and liquefied at room temperature (15° C.) was collected in the collection containers  551  and  552 , the weight of the liquefied refrigerant was measured and divided by the weight of the refrigerant enclosed in the refrigerant containers  531  and  532 , respectively, thereby deriving the liquefaction efficiency. 
     As a result, in the heat exchanger  121  of the present invention, it was confirmed that the liquefaction efficiency became 71.1%, which improved from the liquefaction efficiency 59.8% of the comparative untreated heat exchanger  522 . 
     In the present example, in order to form the crystalline carbon-containing oxide film  121 C having the fine protrusions  121 B on the surface, a wet electrolytic treatment under the above conditions is used, but the present invention is not limited thereto, and the crystalline carbon-containing oxide film may be formed under other conditions or by other treatment methods (sputtering using a metal oxide target containing carbon nanotubes, sol-gel method, or the like). However, the wet electrolytic treatment is superior to other treatment methods in terms of cost. 
     As described above, in the heat exchanger  121  (also a heat exchanger member) of the present invention, the size of the entire cooling system can be made smaller than the conventional mechanism in which a mechanism such as the gas-liquid separating unit is added, so that limitation in the installation is reduced. In addition, since a large change is not involved, it is not necessary to change a portion related to the cooling system, so that an increase in cost can be suppressed. 
     The first embodiment of the present invention is not limited to the pipe-shaped member forming the heat exchanger  121 , and may be a member forming a partition wall for cooling a refrigerant provided inside the heat exchanger, a member such as an internal fin, or the like, but in any case, the effect same as the member forming the hear, exchanger  121  is obtained. 
     In addition, as a matter of course, a heat exchanger including a member forming the heat exchanger  121 , a member forming a partition wall for cooling a refrigerant provided inside the heat exchanger, and a member such as an internal fin has the same effect as the heat exchanger  121 . 
     Furthermore, as it is obvious that the cooling system provided with the heat exchanger formed of the members according to the embodiment cf the present invention also exhibits the same effects as those of the heat exchanger  121 , the size of the entire cooling system can be reduced, so that limitation in the installation can be reduced. In addition, since a large change is not involved, it is not necessary to change a portion related to the cooling system, so that an increase in cost can be suppressed. 
     Second Embodiment 
     Hereinafter, an embodiment of the present invention will be described with reference to  FIGS. 10 to 17 . 
     &lt;Configuration of Semiconductor Cooling System in which Member is Incorporated&gt; 
       FIG. 1  is a schematic diagram illustrating a semiconductor cooling system  100 . The semiconductor cooling system  100  includes a cooling unit  110 , a heat, dissipation unit  120 , a compressor  130 , an expansion valve  140 , and the like. 
     The cooling unit  110  includes a heat exchanger  111  and a semiconductor  150 , and the heat generated in the semiconductor  150  is removed when the refrigerant vaporizes inside the heat exchanger  111 , so that the semiconductor  150  is cooled. The heat exchanger member of the present invention means a member forming the heat exchanger  111 . In the following description, the heat exchanger member will be described as a member forming the heat exchanger  111  which is a tube in which the refrigerant is vaporized inside. 
     &lt;Configuration of Member&gt; 
       FIG. 19  and  FIG. 11 , which is a cross-sectional view taken along line a-a in  FIG. 10 , are views showing a tube forming the heat exchanger  111 , which is a specific example of a heat exchanger member of the present invention. As shown in  FIG. 11 , a crystalline carbon-containing oxide film  111 C provided with fine protrusions  111 B is provided on a metal base  111 A made of a main material (aluminum, stainless steel, copper, etc.) forming a tube. The crystalline carbon-containing oxide film  111 C having the fine protrusions  111 B is a metal oxide film containing crystalline carbon. In the heat exchanger  111 , the crystalline carbon-containing oxide film  111 C increases the wettability between the refrigerant and the tube inner surface in contact with the refrigerant in a liquid state, increases the contact area with the refrigerant even when the refrigerant starts to vaporize at the time of cooling, and enhances the thermal conduction rate by the contained crystalline carbon having a high thermal conduction rate, thus providing the function of enhancing the efficiency (vaporization efficiency) of transferring heat transferred from the semiconductor  150  through the heat exchanger  111  to the refrigerant. 
     The tube is made of a metal tube such as a copper tube, an aluminum tube, or a stainless tube. The wall thickness and length of the tube are not particularly defined, and are appropriately determined according to the purpose of use. 
     The crystalline carbon-containing oxide film  111 C is an oxide of a metal same as or similar to the metal base material, containing crystalline carbon. The film thickness of the crystalline carbon-containing oxide film  111 C may be 10 nm to 300 nm. Furthermore, the film thickness of the crystalline carbon-containing oxide film  111 C is preferably 100 nm to 300 nm in order to enhance vaporization efficiency (=efficiency of transferring heat from a semiconductor to a refrigerant) by utilizing the thermal conductivity of the contained crystalline carbons. The content ratio of carbon contained in the carbon-containing oxide film  121 C may be 5 at % to 50 at % at a point of 3 nm to 5 nm from the surface (the surface opposite to the surface in contact with the metal base  121 A). Furthermore, the content ratio of the crystalline carbon contained in the carbon-containing oxide film  121 C is preferably 8 at % to 40 at % at a point of 3 nm to 5 nm from the surface in order to provide characteristics given by containing the crystalline carbon and to maintain the strength of the film. 
     The crystalline carbon contained in the crystalline carbon-containing oxide film  111 C is preferably a carbon nanotube, fullerene, graphene, or the like to enhance thermal conduct ion. 
     The fine protrusions  111 B are provided on the surface of the crystalline carbon-containing oxide film  111 C (the surface opposite to the surface in contact with the metal base  111 A), and an average spacing between adjacent apexes of the fine protrusions  111 B is greater than or equal to 20 nm and less than or equal to 80 nm, an average value of the height of the apexes of the protrusions is greater than or equal to 30 nm and less than or equal to 70 nm, and an aspect ratio which is a value obtained by dividing the average height by the average spacing is less than one. 
     Furthermore, in order to provide higher wettability to the refrigerant, the fine protrusions  111 B more preferably have an average spacing between adjacent apexes of the fine protrusions  111 B of greater than or equal to 25 nm and less than or equal to 65 nm, an average value of the height of the apexes of the protrusions of greater than or equal to 15 nm and less than or equal to 55 nm, and an aspect ratio which is a value obtained by dividing the average height by the average spacing of less than 0.83. 
     Hereinafter, an example according to the second embodiment will be described with reference to  FIGS. 13 to 16 . The heat exchanger  111  in the example is manufactured from an 11 mm copper square rod having a length of 50 mm with a through hole of φ5 mm at the center as shown in  FIG. 15 . The following treatment was performed to provide the crystalline carbon-containing oxide film  111 C having the fine protrusions  111 B on the surface of the hole of φ5 mm of the copper square rod (metal base  111 A). 
     First, the copper square rod (metal base  111 A) is immersed and degreased with ethanol (immersion time: 30 minutes). Thereafter, as shown in  FIG. 13 , the copper square rod connected to the electric circuit  600  and the SUS 304 electrode  604  connected to the electric circuit  600  in a state of being inserted inside the copper square rod so as not to contact the inner surface of the hole formed in the copper square rod are immersed in the bath  700  containing the treatment liquid  701 . In the treatment liquid  701  in the bath  700 , sodium hydroxide and 0.2% single-walled carbon nanotube dispersion liquid dispersed in purified water by a dispersant are added to purified water so as to have concentrations of 0.95 g/l and 1.35 ml/l, respectively, and the temperature is adjusted so that the liquid temperature becomes 30° C. 
     Thereafter, the voltage is loaded on the aluminum tube by a rectifier  601 , a rectifier  602 , and a changeover switch  603  with the pattern illustrated in  FIG. 14 , wherein the current flowing in the direction of the arrow illustrated in  FIG. 14  is defined as the current in the + direction. 
     Finally, the copper square rod is washed with water and dried (80° C. for 30 minutes) in a thermostatic bath. In this way, the crystalline carbon-containing oxide film  111 C having a thickness of 150 nm is provided on the surface of the copper square rod (metal base  111 A), and at the same time, the fine protrusions  111 B having an average spacing between apexes of the adjacent fine protrusions  111 B of 30.0 nm and an average value of heights of the fine protrusions  111 B of 16.4 nm are provided on the surface of the crystalline carbon-containing oxide film  111 C ( FIG. 12 ), thereby obtaining the heat exchanger  111 . 
     &lt;Demonstration Test&gt; 
     Here, characteristics required for the heat exchanger in the cooling unit will be described. In the heat exchanger in the cooling unit, the refrigerant in a liquid state that has been liquefied in the heat dissipation unit and has a low temperature and a low pressure through the expansion valve receives heat generated from a semiconductor to be cooled, and vaporizes, thereby cooling the semiconductor. At that time, if the heat generated in the semiconductor cannot be efficiently taken away, the temperature of the semiconductor rises, and the semiconductor maybe finally destroyed. On the other hand, semiconductors have been increasingly highly integrated in recent years, and therefore the amount of heat generated during the operation is increasing more and more. Therefore, it is necessary to liquefy all the refrigerant so that the refrigerant can circulate through the system that enhances the efficiency of vaporizing the refrigerant to take away heat (hereinafter, referred to as vaporization efficiency). Therefore, if the liquefaction efficiency per unit area with which the refrigerant of the heat exchanger comes into contact is low, the size of the heat exchanger becomes large, which imposes a limitation in the installation of the cooling system and greatly increases the cost. 
     Furthermore, since the cooling system of the semiconductor generally has a larger heat dissipation unit than a cooling unit, the vaporization efficiency affects the size and cost of the entire unit. 
     Therefore, in the heat exchanger of the cooling unit, it has been required to increase the efficiency (vaporization efficiency) of vaporizing the refrigerant to take away heat, that is, the heat transfer rate to the refrigerant. 
     In addition, as high integration progresses further, the heat generated in the semiconductor vaporizes the refrigerant just before the semiconductor, causing a burnout in which cooling is impossible no matter how much refrigerant is flowed, which has been a factor that limits integration of the semiconductor. Therefore, it has been required to increase the critical heat flux at which the burnout occurs, together with the heat transfer rate. 
     On the inner surface of the hole in the square rod forming the heat exchanger  111  of the present invention, the contact angle indicating wettability with the refrigerant (so-called fluorocarbons such as fluorocarbon, a mixture of methylnonafluorobutyl ether and methylnonafluoroisobutyl ether, and the like) can be mads very small. For example, in the case of copper, the contact angle can be set to 1.77°, from 5.72° when untreated, by adopting the structure according to the present invention, so that the refrigerant and the hole inner surface come into contact with each other over a wider area even when vaporization of the refrigerant starts, and thus heat transfer becomes efficient. In addition, in the structure according to the present invention, the heat exchangeability is further enhanced since crystalline carbon such as carbon nanotubes excelling in thermal conductivity is contained. Therefore, the heat exchanger of the present invention excels in vaporization efficiency (heat transfer rate). 
     The heat exchanger  111  of the present invention shown in  FIGS. 10 to 12 and 16  (contact angle with a refrigerant of 1.77°, 12% content rate of crystalline carbon (at a point of 5 nm from the surface)) and the heat exchanger  911  (contact angle with a refrigerant of 5.72°, 0% content rate of crystalline carbon (at a point of 5 nm from the surface)) which is formed of a comparative untreated copper square rod having an inner surface as shown in  FIG. 17  and having the same shape as that of the present invention are alternately installed in the measurement unit of the vaporization characteristic evaluation device  800  shown in  FIG. 15 , and ceramic heaters  151  or  152  resembling a semiconductor are placed on the upper surface of the installed heat exchangers  111  and  911 . 
     Thereafter, the pump of the vaporization characteristic evaluation device  800  was operated to circulate the refrigerant through the vaporization characteristic evaluation device, and then the output of the ceramic heater was increased to measure the temperature of each unit, thereby deriving the heat transfer rate and the critical heat flux with respect to the refrigerant of the heat, exchanger  111  of the present invention and the comparative untreated heat exchanger  911 . 
     As a result, in the heat exchanger  111  of the present invention, the heat transfer rate was 6.72 W/(m 2 K) and the critical heat flux was 4.47 W/m 2 , and it was confirmed that both the heat transfer rate and the critical heat flux improved from the heat transfer rate of 5.62 W/(m 2 K) and the critical heat flux of 4.32 W/m 2  of the comparative untreated heat exchanger  911 . 
     In the present example, in order to form the crystalline carbon-containing oxide film  111 C having the fine protrusions  111 B on the surface, a wet electrolytic treatment under the above conditions is used, but the present invention is not limited thereto, and the crystalline carbon-containing oxide film may be formed under other conditions or by other treatment methods (sputtering using a metal oxide target containing carbon nanotubes, sol-gel method, or the like). However, the wet electrolytic treatment is superior to other treatment methods in terms of cost. 
     As described above, since the heat exchanger  111  (also a heat exchanger member) oi the present invention has an excellent heat transfer rate (vaporization efficiency) as compared with the conventional heat exchanger  911  in which a surface in contact with a refrigerant is untreated, the size of the entire cooling system can be reduced, to that limitation in the installation is reduced. In addition, critical heat flux is improved, so that integration limit of the semiconductors can be improved. 
     The second embodiment of the present invention is not limited to the square rod shaped member with a hole that forms the heat exchanger  111 , and may be a member forming a partition wall for vaporizing a refrigerant provided inside the heat exchanger, a member such as an internal fin, or the like, but in any case, the effect same as the member forming the heat exchanger  111  is obtained. 
     In addition, as a matter of course, a heat exchanger including a member forming the heat exchanger  111 , a member forming a partition wall for vaporizing a refrigerant provided inside the heat exchanger, and a member such as an internal fin has the same effect as the heat exchanger  111 . 
     Furthermore, as it is obvious that the cooling system provided with the heat exchanger formed of the members according to the embodiment of the present invention also exhibits the same effects as those of the heat exchanger  111 , the size of the entire cooling system can be reduced, so that limitation in the installation can be reduced. In addition, since a large change is not involved, it is not necessary to change a portion related to the cooling system, so that an increase in cost can be suppressed, and furthermore, integration limit of the semiconductors can be improved. 
     The inner surface of the member (tube) according to the embodiment of the present invention can reduce the pressure loss when the refrigerant circulates in the cooling system in a state where the liquid and the gas are mixed, and for example, it has been confirmed that when the volume mixing ratio of the gas and the liquid is 30%, the pressure loss can be reduced by 37% as compared with the untreated case by subjecting the inner surface of the stainless tube to the treatment performed in the first and second examples. 
     Therefore, energy consumption of the pump for circulating the refrigerant can be reduced. 
     The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope defined in the Claims, where embodiments obtained by appropriately combining technical means disclosed in the different embodiments are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. 
     INDUSTRYAL APPLICABILITY 
     The present invention can be used for a heat exchanger member that requires improvement in liquefaction characteristics and/or vaporization characteristics. 
     REFERENCE SIGNS LIST 
       100  semiconductor cooling system 
       121  heat exchanger (heat dissipation unit) 
       121 A metal base 
       1218  fine protrusion 
       121 C crystalline carbon-containing oxide film (metal oxide film) 
       300  bath 
       400  electric circuit