阅读说明：本技术 热交换器用构件、热交换器、空调机以及冰箱 (Member for heat exchanger, air conditioner, and refrigerator ) 是由 田岛秀春 高川资起 于 2020-09-11 设计创作，主要内容包括：通过导热性优异的被膜对金属表面赋予金属自身没有的特性,且实现高效率的热交换器用构件。热交换器用构件由金属构成,在金属表面具有含碳氧化膜(112B),在含碳氧化膜(112B)上设置有微小凹凸(112C),微小凹凸(112C)的凸部的顶点的平均间隔为40nm以上且120nm以下,并且相邻的凸部的顶点以及凹部的底点的高度之差的平均值为30nm以上且250nm以下。(A heat exchanger member having high efficiency is realized by imparting a characteristic which a metal does not have to a metal surface by a coating film having excellent thermal conductivity. The member for a heat exchanger is made of metal, has a carbon-containing oxide film (112B) on the metal surface, and is provided with fine irregularities (112C) on the carbon-containing oxide film (112B), wherein the average distance between the apexes of the convex portions of the fine irregularities (112C) is 40nm to 120nm, and the average distance between the height differences between the apexes of adjacent convex portions and the bottoms of concave portions is 30nm to 250 nm.)

1. A member for a heat exchanger, which is composed of a metal, characterized in that,

a metal oxide film containing carbon is provided on the surface of the metal, irregularities are provided on the metal oxide film,

the average distance between the peaks of the convex portions of the concave-convex portions is 40nm to 120nm, and the average value of the difference in height between the peaks of the adjacent convex portions and the bottom points of the concave portions is 30nm to 250 nm.

2. A member for a heat exchanger according to claim 1,

the content ratio of carbon contained in the range of 3-5 nm from the surface of the metal oxide film is more than 20 at% and less than 40 at%.

3. A member for a heat exchanger according to claim 1 or 2,

the thickness of the metal oxide film is 100nm to 300 nm.

4. A heat exchanger, characterized in that,

a heat exchange fin comprising the member for a heat exchanger according to any one of claims 1 to 3.

5. An indoor unit for an air conditioner, characterized in that,

there is provided the heat exchanger of claim 4.

6. An outdoor unit for an air conditioner, characterized in that,

there is provided the heat exchanger of claim 4.

7. A refrigerator is characterized in that a refrigerator body is provided with a refrigerator door,

there is provided the heat exchanger of claim 4.

Technical Field

The present invention relates to a member for a heat exchanger that imparts characteristics to a metal surface other than the characteristics inherent in the metal, and a device provided with the member.

Background

When the air conditioner is operated, dew condensation or frost formation occurs on the surfaces of heat exchange fins of heat exchangers provided in the indoor unit and the outdoor unit. The condensation or frost on the surface of the heat exchange fin causes the following adverse effects: the heat exchange performance is lowered, the air blowing efficiency is lowered, and the power consumption of the air conditioner itself is increased. In recent years, in the field of air conditioning, techniques involving water drainage have been actively studied as measures against condensation and frost formation on the surfaces of the heat exchange fins. Such a technique is disclosed in patent document 1, for example.

Patent document 1 describes the following method: a coating composition is formed on the surface of a heat exchanger, wherein the coating composition is composed of a water-soluble organic solvent dissolving a fluororesin, the fluororesin, hydrophilic silica particles and hydrophobic silica particles, and condensation, frosting and the like generated on the heat exchanger are inhibited.

Documents of the prior art

Patent document

Patent document 1: WO2016/181676 publication

Disclosure of Invention

Problems to be solved by the invention

However, in the technique of patent document 1, silica particles or an organic material having a thermal conductivity lower than that of a general metal or a metal oxide film are used, and the thermal conductivity of the silica particles (about 1/20 of the thermal conductivity of alumina) is significantly lower than that of aluminum, which is a general material of a heat exchange fin of a heat exchanger, and alumina naturally formed on the surface thereof. Therefore, there are the following problems: when an air conditioner is operated in an environment where dew condensation or the like does not occur, the coating composition itself, which should be a measure against an increase in power consumption of the air conditioner, increases the power consumption of the air conditioner.

Further, in recent years, it has been found that a water repellent treatment having only excellent contact angle and slip angle has no significant effect on adhesion of water droplets due to actual condensation (the reason is not clear at present). Therefore, a technique of performing a water repellent treatment on a heat exchanger has not been put into practical use, and measures against passive condensation and frost formation by a hydrophilic treatment have been taken.

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, an air conditioner, and a refrigerator, which have high efficiency by providing a film having excellent thermal conductivity to a metal surface of a heat exchanger or a heat exchange fin forming the heat exchanger, the metal surface having properties that the metal does not have.

Means for solving the problems

In order to solve the above problems, a heat exchanger member according to the present invention is a heat exchanger member made of a metal, the metal having a metal oxide film containing carbon on a surface thereof, wherein the metal oxide film is provided with irregularities, and an average distance between apexes of the irregularities is 40nm to 120nm, and an average distance between heights of apexes of adjacent irregularities and bottom points of recesses is 30nm to 250 nm.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the following effects are achieved: the heat exchanger member can be provided with a function of improving the heat exchange efficiency of the heat exchanger.

Drawings

Fig. 1 is a perspective view showing an indoor unit of an air conditioner using a heat exchanger member according to a first embodiment of the present invention.

Fig. 2 is a view showing a member for a heat exchanger according to a first embodiment of the present invention.

Fig. 3 is a schematic view showing a cross section viewed along an arrow a-a of fig. 2.

Fig. 4 is an AFM observation result of the surface of the heat exchanger member according to the first embodiment of the present invention.

Fig. 5 is a diagram showing an apparatus for making the first embodiment of the present invention.

Fig. 6 is a graph showing a time chart of the supported electrolytic density for producing the first embodiment of the present invention.

Fig. 7 is a graph showing the results of the condensation test according to 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 of a comparative example of the first embodiment of the present invention.

Detailed Description

(first embodiment)

Embodiments of the present invention will be described below with reference to fig. 1 to 9.

Indoor unit structure of air conditioner with member

Fig. 1 is a diagram showing a cut pattern of an indoor unit 100 of an air conditioner. An indoor unit 100 of an air conditioner includes a heat exchanger 110, an air filter 120, a blower fan 130, a drain pan 140, a casing 150, and a control unit and a drive unit, not shown.

The heat exchanger 110 includes refrigerant pipes 111 and fins 112. The heat exchanger member of the present invention refers to a member constituting the heat exchanger 110 (the refrigerant pipe 111 and the fin 112). In the following description, the heat exchanger member will be described as a member constituting the fin 112.

< Structure of Member >

Fig. 2 and fig. 3, which is a sectional view taken along a-a of fig. 2, show a fin 112 constituting a heat exchanger 110, which is a specific example of the heat exchanger member according to the present invention. As shown in fig. 3, a carbon-containing oxide film 112B is provided on a metal base 112A made of a main material (aluminum, stainless steel, copper, or the like) forming the fin 112, and fine irregularities 112C are provided on the carbon-containing oxide film 112B. The carbon-containing oxide film 112B having the fine irregularities 112C is a metal oxide film containing carbon, and provides a function of improving the heat exchange efficiency of the heat exchanger 110.

The fins 112 are made of a metal plate such as a rolled aluminum plate, a rolled stainless steel plate, or a rolled copper plate. The thickness of the fins 112 is preferably 0.05 to 0.50. The thickness of the fins 112 is preferably 0.05 to 0.20, so that the fins 112 can have a larger surface area than the fins 112 of a heat exchanger having the same volume when the heat exchanger is configured. The size is appropriately determined according to the purpose of use.

The carbon-containing oxide film 112B is an oxide of a metal that contains carbon and is the same as or similar to the metal base material. The thickness of the carbon-containing oxide film 112B may be 40nm to 300 nm. In order to make full use of the thermal conductivity of the carbon-containing material and improve the corrosion resistance, the carbon-containing oxide film 112B is preferably 100nm to 300nm thick. The carbon content of the carbon-containing oxide film 112B may be 5 to 50 at% at a distance of 3 to 5nm from the surface (opposite surface to the surface in contact with the metal substrate 112A). In order to have the characteristics imparted by the carbon-containing oxide film and maintain the strength of the film, the carbon-containing oxide film 112B preferably contains carbon at a ratio of 20 at% to 40 at% at a distance of 3nm to 5nm from the surface.

The carbon contained in the carbon-containing oxide film 112B is preferably crystalline, and carbon nanotubes, fullerenes, graphene, or the like are preferable for improving heat conductivity.

The fine irregularities 112C are provided on the surface of the carbon-containing oxide film 112B (the surface opposite to the surface in contact with the metal substrate 112A), and the average distance between the peaks of the fine irregularities 112C is 40nm to 120nm, and the average value of the difference in height between the peaks of adjacent peaks and the bottoms of the recesses is 30nm to 250 nm. In order to further impart anti-condensation properties, it is more preferable that the average value of the difference in height between the top of the convex portion and the bottom of the concave portion of the fine unevenness 112C is 100nm or more and 200nm or less.

Hereinafter, an example of the first embodiment will be described with reference to fig. 5 to 6. The fins 112 in the example were made of 67mm x 80mm x 0.3mm aluminum plates. In order to provide the carbon-containing oxide film 112B having the minute unevenness 112C on the surface of the aluminum plate (metal base material 112A), the following treatment is performed.

First, the aluminum plate (metal base material 112A) was subjected to immersion degreasing in an aqueous sodium hydroxide solution (immersion time: 5 minutes). Then, as shown in fig. 5, an aluminum plate connected to the circuit 400 and electrodes 404 and 405 made of SUS304(304 stainless steel) connected to the circuit 400 were immersed in the bath 300 containing the treatment liquid 301. With respect to the treatment liquid 301 in the bath 300, sodium hydroxide and a 5% carbon nanotube dispersion were added to purified water (purified water) so that the concentrations thereof became 1.7g/l and 40ml/l, respectively, and the temperature was adjusted so that the liquid temperature became 30 ℃.

When the current flows in the direction of the arrow shown in fig. 5, the voltage is applied to the aluminum plate through the rectifier 401, the rectifier 402, and the changeover switch 403 in the mode shown in fig. 6, in the case of the voltage in the + direction.

Finally, the mixture was washed with water and dried in a thermostatic bath (80 ℃ C., 30 minutes). In this way, the fin 112 was configured by providing the carbon-containing oxide film 112B of 200nm on the surface of the aluminum plate (metal base material 112A) and providing the fine irregularities 112C on the surface of the carbon-containing oxide film 112B, and the average interval of the apexes of the convex portions of the irregular shape of the fine irregularities 112C was 88nm and the average value of the height difference between the apexes of the adjacent convex portions and the base points of the concave portions was 100 nm.

< verification test >

Here, the characteristics required for the fins constituting the heat exchanger will be described. When a heat exchanger is used to absorb heat from the outside, dew condensation occurs on the surfaces of the fins. In an outdoor unit of an air conditioner or a refrigerator (refrigerator) during a heating operation, dew condensation turns into frost, which significantly affects heat exchange efficiency of a heat exchanger. In addition, in the indoor unit during the cooling operation, dew condensation also affects the heat conversion efficiency of heat exchange. Thus, the heat exchange efficiency of the heat exchanger can be significantly improved by preventing dew condensation. However, it is difficult to prevent the occurrence of dew condensation itself, and it is only possible to deal with this by performing a hydrophobic treatment or a hydrophilic treatment on the fins to allow dew condensation water to quickly slide off the surfaces of the fins. In this case, although the reason is not clear, when dew condensation occurs, even if the treatment is performed so that the contact angle or the slip angle, which is a general index showing hydrophobicity or hydrophilicity, is good, it is actually impossible to cause dew condensation water to slip as expected due to the good property.

Further, in the hydrophobic treatment or the hydrophilic treatment, since silica particles or fluorine particles having a thermal conductivity lower than that of naturally formed alumina are provided on the surface of aluminum, there is a problem that a critical heat exchange rate is lowered.

The fin 112 constituting the heat exchanger of the present invention has a remarkable effect of suppressing condensation, although the mechanism thereof is not clear. Further, since the carbon-containing oxide film 112B containing carbon having a higher thermal conductivity than the alumina of the surface of the aluminum is provided, the heat exchange efficiency of aluminum, which is a main material of the fin 112, is not affected as compared with the general hydrophobic treatment and hydrophilic treatment in which the silica particles or fluorine particles having a lower thermal conductivity than the aluminum are provided.

The condensation test was performed by providing both the fins 112 (contact angle: 130 ° and sliding angle: 30 °) constituting the heat exchanger of the present invention shown in fig. 4 and 8 and the comparative fins (contact angle: 130 ° and sliding angle: 29 °) shown in fig. 9 on the cooler to compare the occurrence of condensation. The comparative fin was produced under conditions different from those of the present invention and had minute irregularities (Ra: 0.1 μm), but the average distance between the apexes of the projections forming the irregularities was 1.0 μm, which was large relative to the irregularities of the present invention.

Fig. 7 is a photograph showing the condensation state of each fin 60 minutes after the start of cooling. As can be seen from fig. 7, at least, the fin 112 of the present invention did not show the generation of dew condensation water, and the fin for comparison did not show the generation of dew condensation water. Although not shown, adhesion of dew condensation water was also confirmed in the same manner as in the comparative fin for the fin to which the hydrophilic coating or the hydrophobic coating was applied.

In addition, in the condensation test, the surface temperature of each fin was measured by a radiation thermometer, and it was confirmed that only the fin 112 of the present invention had a temperature 2 to 3 ℃ lower than that of a general aluminum fin, and it was confirmed that it exhibited excellent heat exchange properties.

In the present embodiment, the carbon-containing oxide film 112B having the fine irregularities 112C on the surface thereof is formed by wet electrolytic treatment under the above-described conditions, but the present invention is not limited thereto, and the 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, the fin 112 of the present invention can achieve the effect of preventing dew condensation and improving the heat exchange efficiency of the heat exchanger, as compared with the conventional hydrophilic coating or fluororesin coating or the conventional water repellent treatment by forming irregularities.

The first embodiment of the present invention is not limited to the fins 112, and may be, for example, cooling water piping for a radiator made of copper or a member constituting a water cooling jacket for cooling a power device, and in any case, the same effects as those of the fins 112 can be achieved. In addition, the carbon-containing oxide film 112B also achieves an effect of improving the corrosion resistance of the member.

The heat exchanger constituted by the above-described members such as the fins 112 achieves the same effects as the fins 112.

Further, since the air conditioner or the refrigerator provided with the heat exchanger constituted by the fins 112 and the like also remarkably achieves the same effect as the fins 112, the effect of reducing the power consumption can be finally achieved.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in the respective embodiments are also included in the technical scope of the present invention. Further, by combining the technical means disclosed in the respective embodiments, new technical features can be formed.

Industrial applicability of the invention

The present invention can be used for a heat exchanger member requiring dew condensation resistance, frost formation resistance, and corrosion resistance.

Description of the reference numerals

100: an indoor unit of an air conditioner,

112: a fin,

112B: a carbon-containing oxide film (metal oxide film),

112C: micro concave-convex,

300: a treatment tank,

400: an electrical circuit.