TWI732016B - Heat exchanger formed with anti-fouling coating film - Google Patents

Abstract

The heat exchanger of the present disclosure is a heat exchanger in which an antifouling coating film is formed on the surface of an antifouling object, wherein the antifouling coating film is at least composed of nano particles, and the surface of the antifouling coating film has arithmetic The average roughness Ra is the unevenness in the range of 2.5 to 100 nm. In this way, the present disclosure can provide a heat exchanger that can at least effectively inhibit or prevent the adhesion of dry dirt.

Description

Heat exchanger formed with anti-fouling coating film

The present disclosure relates to a heat exchanger formed with an anti-fouling coating film. In particular, it relates to a heat exchanger that can effectively inhibit or prevent the adhesion of dry dirt.

The refrigeration cycle has been widely used in various freezer fields such as air conditioners, refrigerators, refrigerated display cabinets, and vending machines. The refrigeration cycle is equipped with a heat exchanger to absorb heat from a low-temperature heat source and dissipate heat to a high-temperature heat source. However, various substances are easily attached to the heat exchanger to form "dirt".

For example, an air conditioner uses a heat exchanger to exchange heat with the sucked air, so various substances contained in the air tend to adhere to the heat exchanger and form "dirt". If this kind of dirt adheres to the heat exchanger, it will not only reduce the performance of the heat exchanger, but also multiply microorganisms such as molds or bacteria, which may cause hygienic problems.

In this regard, for example, in International Publication No. 2008/087877, in order to prevent the adhesion of both hydrophilic dirt and lipophilic (hydrophobic) dirt on the heat exchanger of an air conditioner, a method containing a dioxide with an average particle diameter of 15nm or less is proposed. A coating composition made by blending silicon ultrafine particles and fluororesin particles in a predetermined mass ratio.

SUMMARY OF THE INVENTION As disclosed in International Publication No. 2008/087877, there are hydrophilic dirt (wet dirt) and lipophilic dirt (oily dirt) in dirt attached to articles. These dirts are all “wet” dirts that use “liquid” such as water or oil as a medium (solvent or dispersion medium, etc.). However, the dirt attached to objects not only has the layer of such "wet" dirt, but also has the layer of "dry" dirt such as dust. In the technology disclosed in the aforementioned International Publication No. 2008/087877, only the "wetness" aspect is discussed to suppress the adhesion of dirt on the article, so it is difficult to sufficiently prevent or suppress the adhesion of dry dirt.

As a result of diligent research by the present inventors, it has been found that “dry” dirt should be divided into two types: a relatively large and hard matter and a relatively small and soft matter. For the convenience of explanation, the former "dry" dirt is called "high specific gravity hard type", and the latter's "dry" dirt is called "small specific gravity soft type". As far as "dry" dirt is concerned, both the carbon of lipophilic dirt and the dust of hydrophilic dirt belong to the "high specific gravity" type of dirt.

Here, the lipophilic (hydrophobic) dirt series in International Publication No. 2008/087877 includes oil fume, cigarette tar, carbon, etc., and the hydrophilic dirt includes dust. Moreover, in the example of International Publication No. 2008/087877, the "dust" series of "hydrophilic dirt" included Kanto loam dust and carbon black, and air sprayed the dust on the coating film to evaluate its Adhesion. That is, in International Publication No. 2008/087877, the "dry" dirt of "high specific gravity" is regarded as "hydrophilic dirt" and its adhesion is evaluated. From this, it can be judged that the International Publication No. 2008/ No. 087877 does not fully evaluate the "dry" dirt of the "high specific gravity hard type".

On the other hand, the "small specific gravity soft type" dirt may include fiber-based dust such as cotton dust or cotton wool, or food powder-based dust such as wheat flour and cornstarch. In International Publication No. 2008/087877, no assessment has been made for this type of "soft type with a small specific gravity" of "dry" dirt. Therefore, the coating composition disclosed in International Publication No. 2008/087877 has not been fully studied for preventing "dry" dirt.

The present disclosure was made in order to solve the above-mentioned problems, and its object is to provide a heat exchanger that can effectively suppress or prevent the adhesion of dry dirt at least.

In order to solve the aforementioned problems, the heat exchanger of the present disclosure is composed of a heat exchanger having an anti-fouling coating film formed on the surface of an anti-fouling object, wherein the antifouling coating film is at least composed of nano particles, and the antifouling The surface of the dirt coating film has unevenness with an arithmetic mean roughness Ra in the range of 2.5-100nm.

According to the aforementioned structure, an anti-fouling coating made of nano particles and having fine surface irregularities is formed on the surface of the anti-fouling object of the heat exchanger. Thereby, it is possible to effectively suppress or prevent the adhesion of dry dirt on the surface of the heat exchanger.

In the present disclosure, the above configuration can exert an effect to provide a heat exchanger that can at least effectively suppress or prevent the adhesion of dry dirt.

Embodiments of the Invention The structure of the heat exchanger of the present disclosure is a heat exchanger in which an antifouling coating film is formed on the surface of an antifouling object, wherein the antifouling coating film is at least composed of nano particles, and the antifouling coating The surface of the film has unevenness with an arithmetic mean roughness Ra in the range of 2.5-100nm.

According to the aforementioned structure, an anti-fouling coating made of nano particles and having fine surface irregularities is formed on the surface of the anti-fouling object of the heat exchanger. Thereby, it is possible to effectively suppress or prevent the adhesion of dry dirt on the surface of the heat exchanger.

The heat exchanger of the aforementioned configuration may also be a configuration in which the average particle diameter of the aforementioned nano particles is in the range of 5 to 100 nm.

According to the aforementioned configuration, if the average particle diameter of the nanoparticle is within the aforementioned range, finer surface irregularities can be achieved more satisfactorily.

In addition, the heat exchanger of the aforementioned structure may be that the aforementioned nanoparticle is selected from the group consisting of metal nanoparticle, inorganic oxide nanoparticle, inorganic nitride nanoparticle, inorganic chalcogenide nanoparticle, (methyl ) At least one of the group consisting of acrylic resin nanoparticles and fluororesin nanoparticles.

According to the aforementioned structure, if the nanoparticle is made of at least any material in the aforementioned group, a good antifouling coating can be formed.

In addition, the heat exchanger of the aforementioned structure may have a structure in which the film thickness of the aforementioned antifouling coating film is 500 nm or less.

According to the aforementioned structure, the chargeability of the antifouling coating film can be reduced satisfactorily, and the adhesion of dry dirt can be satisfactorily suppressed or prevented.

In addition, the heat exchanger of the aforementioned structure may also have a structure in which the antifouling coating film contains an adhering component in addition to the aforementioned nanoparticle, and the adhering component is made of at least a material that has affinity with the aforementioned nanoparticle.

According to the aforementioned structure, the strength or durability of the antifouling coating film can be improved, while the fine unevenness on the surface can be easily maintained, and the effect of inhibiting or preventing the adhesion of dry dirt can be improved.

In addition, the heat exchanger of the aforementioned configuration may also have a configuration in which the ratio of the dust adhesion area on the antifouling coating film to the dust adhesion area on the surface on which the antifouling coating film is not formed is the dust adhesion rate When the dust adhesion rate of the anti-fouling coating is 15% or less, the dust adhesion area is a mixture of organic simulated dust and inorganic simulated dust. The mixed simulated dust is sprayed and shaken, and the image is taken with an optical microscope. After binarizing the obtained image, the area ratio of the residual mixed simulated dust is calculated.

According to the aforementioned structure, the dust adhesion rate of the antifouling coating film is 15% or less, and therefore the adhesion of dry dirt can be particularly well suppressed or avoided.

In addition, the heat exchanger of the aforementioned structure may have a structure in which the surface resistivity of the aforementioned antifouling coating film is 10 ¹³ Ω/□ or less.

According to the aforementioned structure, the chargeability of the antifouling coating film can be reduced satisfactorily, so that the adhesion of dry dirt can be satisfactorily suppressed or prevented.

The following is a detailed description of the representative configuration examples of this disclosure. [Anti-fouling coating film]

The anti-fouling coating film formed on the heat exchanger of the present disclosure is a film composed of at least nano particles and having uneven surface with an arithmetic average roughness Ra of 2.5-100 nm. The nanoparticles constituting the antifouling coating film are not particularly limited, and representative examples include metal nanoparticles, inorganic oxide nanoparticles, inorganic nitride nanoparticles, inorganic chalcogenide nanoparticles (inorganic oxides). Nanoparticles are excluded), (meth)acrylic resin nanoparticles, fluororesin nanoparticles, etc.

Specifically, metal nanoparticles can include elements of group 11 of the periodic table or alloys thereof such as gold (Au), silver (Ag), copper (Cu), iron platinum (FePt), etc.; nickel (Ni, group 10 element) , Tin (Sn, Group 14 element) and other metal elements for plating other than Group 11 elements of the periodic table. In addition, inorganic oxide nanoparticles can include silicon dioxide (silicon _{oxide, SiO 2} ), yttrium oxide (Y ₂ O ₃ ), barium titanate (BaTiO ₃ ), antimony-doped tin oxide (ATO), and titanium oxide. (TiO ₂ ), indium oxide (In ₂ O ₃ ), etc. Examples of inorganic nitride nanoparticles include gallium nitride (GaN). Examples of inorganic chalcogenide nanoparticles include cadmium selenide (CdSe). Examples of (meth)acrylic resin nanoparticles include polymethyl methacrylate (PMMA). Examples of fluororesin nanoparticles include polytetrafluoroethylene (PTFE).

Basically, only one type of these nanoparticles is used to form an anti-fouling coating film, but a plurality of types may be combined to form an anti-fouling coating film. Among them, it is particularly preferable to use silica nanoparticles from the viewpoints of versatility, cost, and easy adjustment of the average particle size. In addition, the antifouling coating film is basically composed of only nano particles, but it may contain ingredients other than nano particles without hindering the antifouling performance of the antifouling coating film. For example, in addition to nanoparticles, anti-fouling coatings can also contain antistatic agents.

The particle size of the nanoparticle is not particularly limited as long as it is nanoscale (less than 1 μm). In the present disclosure, it is preferably 100 nm or less, and preferably in the range of 5 to 100 nm. In addition, the preferable range of the average particle diameter can also be in the range of greater than 15 nm and less than 100 nm, or in the range of 20 nm to 100 nm.

As long as the particle size of the nano particles is below 100 nm, the surface of the anti-fouling coating film can be easily realized with a nano-level uneven structure. In addition, although it depends on the specific structure of the anti-fouling coating film, as long as the nanoparticle size is in the range of 5 to 100 nm, the nano-level uneven structure can be easily adjusted to a more suitable range. In addition, when the anti-fouling coating contains a component as described later, the nano-particle size can be set in the range of greater than 15nm and less than 100nm, or within the range of 20-100nm, and the nano-level uneven structure can be easily formed. Adjust in a more suitable range.

In addition, the specific composition of the anti-fouling coating film will vary depending on various conditions such as the method of forming the anti-fouling coating film and the surface condition of the heat exchanger of the object to be coated. However, there is a tendency that the particle size of the nano particles should not be too small. The particle size of the nanoparticles is too small, and there is a tendency for the nanoparticles to aggregate with each other and become coarser. As a result, the surface unevenness of the obtained antifouling coating film becomes larger than the predetermined arithmetic average roughness Ra. At this time, dry dirt tends to adhere to the large irregularities on the surface, so dry dirt tends to adhere.

The arithmetic average surface roughness Ra of the antifouling coating film should be within the range of 2.5~100nm. As long as the arithmetic average roughness Ra is within this range, by forming such an antifouling coating film on the heat exchanger of the coated object, at least the adhesion of dry fouling can be effectively suppressed or prevented.

In addition, as described above, the antifouling coating film is composed of at least nano particles, and the surface arithmetic average roughness Ra is within the aforementioned range, and the specific structure other than that is not particularly limited. For example, the film thickness of the antifouling coating film is not particularly limited. Generally, it is less than 1 μm (1,000 nm), preferably 500 nm or less, and preferably in the range of 20 to 500 nm.

If the film thickness of the antifouling coating film is less than 1μm, it is at the nanometer level. Since the film thickness is relatively small (thin), the chargeability of the antifouling coating film can be reduced well, so that the adhesion of dry fouling can be well suppressed or prevented, and at the same time It can improve the transparency of the anti-fouling coating film. In addition, although it differs depending on the conditions, as long as the film thickness is 500 nm or less, the chargeability of the antifouling coating film can be further reduced and the transparency can be further improved. In addition, although it varies depending on the conditions, as long as the film thickness is in the range of 20 to 500 nm, the transparency can be improved and the chargeability can be further reduced, which can better inhibit or prevent the adhesion of dry dirt.

In particular, if the film thickness is below 500nm (or within the range of 20~500nm), since the heat exchanger of the coated object is basically made of metal, even if the antifouling coating is electrostatically charged, it can be exchanged by heat The conductivity of the device is grounded (earth). Therefore, substantial charging can be avoided. Thereby, the adhesion of dry dirt can be further effectively suppressed or prevented. In addition, if the film thickness of the antifouling coating film becomes larger (thick), since the aforementioned antifouling coating film is mainly composed of nano particles, it is likely to cause cracks, but if the film thickness is below 500nm, it can be substantially avoided. crack.

The surface characteristics of the antifouling coating film are not particularly limited, and the surface resistivity may be 10 ¹³ Ω/□ or less. Thereby, the chargeability of the antifouling coating film can be reduced satisfactorily, and therefore the adhesion of dry dirt can be satisfactorily suppressed or prevented. In addition, the water contact angle of the antifouling coating film may be less than 15°, and although it depends on each condition, it may be 10° or less. In this way, as long as the water contact angle of the antifouling coating film is small, the hydrophilicity of the surface can be improved. Therefore, even if dry dirt accumulates on the surface of the anti-fouling coating, the accumulated dry dirt can be easily removed by washing with water.

In addition, the method for measuring the particle size of the nanoparticle is not particularly limited, and a known method (diffusion method, inertial method, sedimentation method, microscopy method, light scattering diffraction method, etc.) can be appropriately used. As far as the calculation in this implementation is concerned, the particle size measured by a known method should be of the nanometer level. In addition, the method for measuring (evaluating) the arithmetic average roughness Ra of the antifouling coating film is not particularly limited. For example, a laser microscope or atomic force microscope (AFM) can be used to measure (evaluate) the arithmetic average roughness Ra according to JIS B0601. Just figure it out. In addition, the method of measuring the film thickness of the antifouling coating film is not particularly limited. In this embodiment, as described in the following examples, the coating section is observed with an electron microscope and the film thickness is measured from a plurality of observation images to calculate the average value. In addition, the method for measuring (evaluating) the water contact angle of the antifouling coating film is not particularly limited. For example, a contact angle meter manufactured by Kyowa Interface Science Co., Ltd., product name: DMo-501 may be used for measurement (evaluation).

The specific formation method (manufacturing method) of the antifouling coating film is not particularly limited, and as long as the fine irregularities derived from the nanoparticle can be formed, various known methods can be used. Representative formation methods include, for example, well-known coating methods in which nanoparticle-containing coating solutions (coating agents) are prepared and applied, sol-gel method, nano stamper, transfer using anodized molds, Sandblasting and self-organization of ceramics, etc.

As mentioned above, the antifouling coating film is only required to be composed of at least nano particles, and may also contain an adhering component, and the adhering component is at least composed of a material that has affinity for the nanoparticle. As far as the function of the adjoining component is concerned, as long as it has the function of allowing the nano particles to adhere to each other and the function of adhering the nano particles to the surface of the heat exchanger of the coated object. Therefore, it is sufficient to use materials that have at least affinity for nanoparticles as the main component.

Since the anti-fouling coating film contains the adhering component, the strength or durability of the anti-fouling coating film made of nano particles can be improved. In addition, the nano particles can be well maintained on the surface of the antifouling coating film, so it is easy to maintain the fine unevenness of the surface, and the effect of inhibiting or preventing the adhesion of dry dirt can be improved.

There is no particular limitation on the specific composition of the subsequent component, as long as it has an affinity for the nanoparticle. For example, if the nanoparticle is a silica nanoparticle, a material that has affinity with silica can be used as the connecting component. Materials that have affinity for silicon dioxide include silane compounds such as tetramethoxysilane or tetraethoxysilane, acryl-based resins, and fluororesins. In addition, in addition to these materials, the following components may also contain known additives. Therefore, as far as the heat exchanger of the present disclosure is concerned, it is sufficient that the antifouling coating is at least composed of nano particles, but it may also be composed of a component in addition to the nano particles, or may be in addition to the nano particles. In addition to the particles and subsequent components, it also contains known additives.

When the antifouling coating film contains the adjoining component, its content (content rate) is not particularly limited. For example, when the total weight of the antifouling coating film is 100% by weight, the ideal range may be in the range of 5-60% by weight. A preferable range may be in the range of 10-50% by weight. Although it varies depending on the conditions, once the amount of the attached component exceeds 60% by weight, the amount of the attached component relative to the nanoparticle will be too much, and the arithmetic average roughness Ra of the surface of the antifouling coating may exceed the predetermined range. In addition, if the subsequent component is less than 5% by weight, it may not be possible to sufficiently obtain the effect of improving the strength or durability according to the content of the subsequent component. [Dust adhesion rate of anti-fouling coating]

The dust adhesion rate of the antifouling coating film of the aforementioned structure is 15% or less. Here, the dust adhesion rate of the present disclosure is based on the amount of simulated dust adhesion on the heat exchanger surface (covered surface composed of the anti-fouling coating film) on which the anti-fouling coating film is formed, relative to the amount of dust on the heat exchanger surface without the anti-fouling coating Calculate the simulated dust adhesion amount on the surface of the membrane heat exchanger (coated object) (the surface before coating).

As mentioned above, "dry" dirt contains a relatively large and hard "high specific gravity hard type" and a relatively small specific gravity and soft "small specific gravity soft type". In the present disclosure, the simulated dust used to calculate the dust adhesion rate is suitable to use the "high specific gravity hard type" simulated dust and the "small specific gravity soft type" simulated dust mixed with mixed simulated dust. Generally speaking, "high specific gravity hard type" simulated dust is dust composed of inorganic materials, and "small specific gravity soft type" simulated dust is simulated dust composed of organic materials.

The specific types of "high specific gravity hard type" simulated dust and "small specific gravity soft type" simulated dust are not particularly limited. You can appropriately select and use test powders specified in various specifications such as JIS (Japanese Industrial Standards). "High specific gravity hard type" or "small specific gravity soft type". In addition, the "high specific gravity hard type" simulated dust and the "small specific gravity soft type" simulated dust can all be one type, but it is advisable to use two or more types in combination.

In the present disclosure, as shown in the following embodiments, two kinds of silica sand of inorganic materials are used as the "high specific gravity hard type" simulated dust, and the organic material lint and corn starch are used as the "small specific gravity soft type" simulated dust. Specific silica sand can use 2 types of the first type silica sand and the third type silica sand specified in JIS Z 8901.

For lint, you can use a test powder sold by the Japan Air Purification Association (JACA). Commercially available corn starch can be used. Silica sand system is used to evaluate the adhesion of the "high specific gravity hard type", the cotton lint system is used to evaluate the adhesion of fiber dust in the "small specific gravity soft type", and the corn starch system is used to evaluate the food powder in the "small specific gravity soft type" Used for adhesion of dust. Therefore, an example of the ideal mixed dust of the "high specific gravity hard type" simulated dust and the "small specific gravity soft type" simulated dust can be a mixed simulated dust formed by a mixture of organic simulated dust and inorganic simulated dust.

In the Examples and Comparative Examples of International Publication No. 2008/087877, the simulated dust uses Kanto loam dust or carbon black separately to evaluate the adhesion (anti-fouling performance) of the dust. However, there are various types of dust contained in the general living space. Therefore, it is necessary to evaluate the antifouling performance of dry dirt as disclosed in this disclosure. Even if a single type of dust is used to evaluate the adhesion (antifouling performance), it is not sufficient. evaluation result. In addition, the Kanto loam dust is used for the evaluation of hydrophilic dirt, and carbon black is used for the evaluation of lipophilic dirt. These are all “dry” dirt with a “high specific gravity” type. In International Publication No. 2008/087877, there is no comment on "dry" dirt of "small specific gravity, soft type" such as fiber-based dust or food powder-based dust.

In contrast, the present disclosure does not use a single simulated dust as dry dirt, but models the actual dust existing in the living space, and uses a "high specific gravity hard type" to simulate dust and a "small specific gravity soft type" to simulate dust mixing. The resulting mixture simulates dust. Therefore, the antifouling performance of dry dirt can be evaluated well. In addition, although the dry dirt dust system dust also contains things that are hydrophilic like the Kanto loam dust, in the mixed simulated dust of this disclosure, in addition to the fiber-based simulated dust lint, hydrophilic corn starch is also used as food. The powder system simulates dust. Corn starch acts as a dry dirt in a dry state, but when there is moisture, it will absorb water and act as a hydrophilic dirt. By using corn starch with such characteristics as simulated dust, the antifouling performance corresponding to actual dust can be evaluated well.

As mentioned above, the dust adhesion rate is defined as the amount of mixed simulated dust on the surface of the heat exchanger covered by the anti-fouling coating, relative to the mixed simulated dust on the surface before the coating of the anti-fouling coating The ratio of adhesion amount. In the present disclosure, the amount of mixed simulated dust on the surface before coating or on the coated surface can be calculated by taking an image with an optical microscope and then binarizing the image to calculate the area ratio of the remaining mixed simulated dust. And use this area ratio as the dust adhesion area. When the dust adhesion area on the surface before coating is A ₀ and the dust adhesion area on the coating surface is A ₁ , the dust adhesion rate _AR can be calculated by the following formula (1). [Math 1]

The dust adhesion rate of the anti-fouling coating film is only 15% or less, preferably 10% or less, preferably 5% or less, and particularly preferably 2% or less. If the dust adhesion rate is 15% or less, the visible dust adhesion is not obvious, so it can be judged that sufficient antifouling performance is obtained.

When calculating the dust adhesion rate, for example, an anti-fouling coating can be formed on part of the surface of the heat exchanger, or a part of the heat exchanger can be cut out to form an anti-fouling coating on it, and this can be used as an evaluation sample use. When the evaluation sample uses the surface on which the anti-fouling coating is formed as the "coated surface", the mixed simulated dust is attached to the coated surface, and the evaluation sample should be destaticized before the mixed simulated dust adheres .

In addition, the method of attaching the mixed simulated dust to the evaluation sample and the method of shaking off the attached mixed simulated dust are not particularly limited, and various methods can be suitably used. For example, in the embodiment described later, after a predetermined amount of mixed simulated dust is deposited on the coating surface, the evaluation sample is vertically poured and dropped to shake off the mixed simulated dust. In addition, there is no particular limitation on the image capturing of the coated surface using an optical microscope, and it is sufficient to capture a large number of images at a magnification at which the mixed simulated dust can be observed. There is no particular limitation on the binarization processing of the captured image, and it is sufficient to use known image processing software or the like. [Heat exchanger]

The heat exchanger of the present disclosure only needs to form the antifouling coating film of the aforementioned structure on the surface of the antifouling object. Here, the surface of the anti-fouling object can be a part of the surface of the heat exchanger, or it can be multiple parts of the surface of the heat exchanger, or it can be the entire surface of the heat exchanger.

The structure of the heat exchanger of the present disclosure, that is, the specific structure of the heat exchanger of the object to be covered by the antifouling coating film is not particularly limited, as long as it can be used in a refrigeration cycle or the like. Specific examples include heat exchangers used in air conditioners, refrigerators, refrigerated display cabinets, and vending machines.

In this embodiment, a heat exchanger used in an air conditioner will be cited as a representative heat exchanger. The specific structure of the heat exchanger used in the air conditioner is not particularly limited, as long as it is a well-known thing. Representative examples include the fin-tube type heat exchanger 10A as shown schematically in FIG. 1 or as shown schematically in FIG. 2 The plate laminated heat exchanger 10B and so on.

As shown in FIG. 1, the fin-tube type heat exchanger 10A typically has a structure in which a plurality of flat fins 11 are stacked and a refrigerant tube 12 having a plurality of bent portions penetrating the fins 11 is provided. The refrigerant pipe 12 forms a refrigerant flow path. For example, the refrigerant circulates in the refrigerant pipe 12 in the direction indicated by the thick arrow in the figure, so that the refrigerant and the outside air pass through the refrigerant pipe 12 and the fins 11 to exchange heat.

As shown in FIG. 2, the plate-laminated heat exchanger 10B typically has the following structure: a plate-laminated structure 14 having a rectangular parallelepiped shape (square columnar shape) is formed by laminating a plurality of rectangular heat-conducting plates 13, and the plate-laminated structure The two ends of 14 are respectively provided with refrigerant boxes 15. The refrigerant tank 15 communicates with the inside of each heat conduction plate 13 constituting the plate laminate structure 14. In each heat conduction plate 13, as shown by the thick arrow in the figure, for example, the refrigerant and the outside air exchange heat through the heat conduction plate 13 by circulating the refrigerant from one refrigerant tank 15 to the other refrigerant tank 15.

Regardless of whether the heat exchanger of the present disclosure is of a fin-tube type or a plate-laminated type, the antifouling coating film of the aforementioned structure is formed on at least a part of its surface. In this way, even if there is dry dirt (dust, etc.) on the surface of the heat exchanger (especially the surface of the fin or the surface of the heat transfer plate), the fine unevenness on the surface of the antifouling coating can effectively inhibit or prevent the adhesion of dry dirt.于surface.

In particular, by limiting the thickness of the antifouling coating film, the surface resistivity can be relatively reduced. Therefore, the additive effect of the surface fine unevenness can more effectively inhibit or prevent the adhesion of dry dirt. Moreover, if a hydrophilic substance such as silica particles is used as the nanoparticle, the accumulated dry dirt can be easily removed by washing the heat exchanger.

In this way, the heat exchanger of the present disclosure can be a heat exchanger with an antifouling coating film formed on the surface of an antifouling object, and the antifouling coating film is at least composed of nano particles and has a surface The arithmetic average roughness Ra is the unevenness in the range of 2.5~100nm. Thereby, it is possible to effectively suppress or prevent the adhesion of dry dirt on the surface of the heat exchanger. Example

For the present disclosure, further specific descriptions are made based on the embodiments and comparative examples, but the present disclosure is not limited by this. Those who are familiar with this technique can make various changes, corrections and changes without departing from the scope of this disclosure. (Mixed simulated dust)

Use the first type of silica sand and the third type of silica sand specified in JIS Z 8901 as the "high specific gravity hard type" simulated dust, and use the lint of the test powder sold by the Japan Air Purification Association (JACA) And commercially available corn starch is used as a "small specific gravity soft type" to simulate dust. The four types of simulated dust are weighed to equal weight and then mixed thoroughly to make mixed simulated dust. (Arithmetic average thickness of anti-fouling coating Ra)

The measurement was performed using a scanning probe microscope (manufactured by Hitachi High-Tech Science Co., product name: AFM5300), and the arithmetic average roughness Ra was calculated in accordance with JIS B0601. (Evaluation of dust adhesion rate)

After removing the static electricity of the evaluation sample, sprinkle the mixed simulated powder on the aforementioned evaluation sample and shake it off. Then, the surface of the evaluation sample is photographed with an optical microscope, and the photographic image is binarized to measure the surface The dust attachment area. In the evaluation sample surface, when the surface with no anti-fouling coating film is used as the reference surface and the surface with the anti-fouling coating film is used as the evaluation surface, the dust adhesion area on the evaluation surface is relative to the reference surface The ratio of the dust adhesion area is the dust adhesion rate. If the dust adhesion area is less than 5%, the dust adhesion rate is evaluated as "◎", greater than 5% and less than 15% is evaluated as "○", and greater than 15% is evaluated as "×". (Example 1)

Prepare an aluminum metal plate as a slice after cutting out a part of the heat exchanger. After preparing the following coating solution by a known method, the aforementioned coating solution was applied to about half of the surface of an aluminum metal plate and dried to prepare the evaluation test with the antifouling coating film formed in Example 1 In this way, the aforementioned coating liquid is prepared by sufficiently dispersing silica particles with an average particle diameter of 20 nm in ethanol as a dispersion medium by pH adjustment or the like. On this evaluation sample, an antifouling coating film was formed on one half of the surface, and an antifouling coating film was not formed on the remaining half of the surface. Regarding the sample for evaluation, the surface of the formed antifouling coating film had irregularities with an arithmetic average roughness Ra of 10 nm. In addition, the dust adhesion rate of the sample for evaluation was "◎". (Example 2)

Except for using silicon dioxide particles with an average particle diameter of 100 nm, an evaluation sample with an antifouling coating film formed in Example 2 was produced in the same manner as in Example 1. Regarding the sample for evaluation, the surface of the formed antifouling coating film had irregularities with an arithmetic average roughness Ra of 40 nm. In addition, the dust adhesion rate of the sample for evaluation was "○". (Comparative example 1)

Although silica particles with an average particle diameter of 100 nm were used, the coating solution was prepared without dispersing the aforementioned silica particles sufficiently. Except for this, the same method as in Example 1 was carried out to prepare a comparative example 1 with antifouling Evaluation sample of coating film. Regarding the sample for evaluation, the surface of the formed antifouling coating film had irregularities with an arithmetic mean roughness Ra of 140 nm. In addition, the dust adhesion rate of the sample for evaluation was "×". (Comparative example 2)

Although silica particles with an average particle diameter of 250 nm were used, the coating solution was prepared without sufficiently dispersing the aforementioned silica particles. Other than that, in the same manner as in Example 1, a comparative example 2 was formed with antifouling Evaluation sample of coating film. Regarding the sample for evaluation, the surface of the formed antifouling coating film had irregularities with an arithmetic mean roughness Ra of 130 nm. In addition, the dust adhesion rate of the sample for evaluation was "×". (Comparison of Examples and Comparative Examples)

As is clear from the results of Examples 1 and 2, if the antifouling coating film is composed of nano particles and has unevenness with the arithmetic average surface roughness Ra in the range of 2.5 to 100 nm, the dust adhesion rate can be suppressed to 15% or less, and it can well inhibit the adhesion of dry dirt in the heat exchanger. In contrast, as shown in Comparative Example 1 or 2, even if the antifouling coating film is composed of nano particles, if the unevenness on the surface of the antifouling coating exceeds the upper limit of the arithmetic average roughness Ra 100nm, the dust adhesion rate will be greater than 15% , And cannot well inhibit the adhesion of dry dirt.

In addition, the present disclosure is not limited to what is described in the foregoing embodiments, and various changes can be made within the scope shown in the scope of the patent application, and different embodiments or embodiments in which the technical means disclosed in multiple modifications are appropriately combined. It is also included in the technical scope of the present disclosure.

The present disclosure can be widely and appropriately used in the field of heat exchangers that are particularly required to prevent the adhesion of dry fouling.

10A‧‧‧Fin and tube heat exchanger 10B‧‧‧Plate layer heat exchanger 11‧‧‧Fin 12‧‧‧Refrigerant pipe 13‧‧‧Heat conduction plate 14‧‧‧Sheet laminated structure 15‧‧‧Refrigerant box

Fig. 1 is a schematic cross-sectional view showing an example of a heat exchanger according to an embodiment of the present disclosure, the structure of a fin and tube heat exchanger. Fig. 2 is a schematic cross-sectional view showing the structure of a plate laminated heat exchanger, an example of the heat exchanger according to the embodiment of the present disclosure.

10A‧‧‧Fin tube heat exchanger

11‧‧‧Fins

12‧‧‧Refrigerant tube

Claims (5)

A heat exchanger is formed on the metal surface of an antifouling object with an antifouling coating film that can effectively inhibit or prevent the adhesion of dry dirt, wherein the antifouling coating film is at least composed of nano particles, and the antifouling coating The surface of the coating film has unevenness with an arithmetic average roughness Ra in the range of 2.5~100nm, wherein the surface resistivity of the antifouling coating film is 10 ¹³ Ω/□ or less, and it makes the antifouling coating film on When the ratio of the dust adhesion area to the dust adhesion area on the surface where the antifouling coating film is not formed is the dust adhesion rate, the dust adhesion rate of the antifouling coating film is 15% or less, and the dust adhesion area is organic The mixed simulated dust is a mixture of simulated dust and inorganic simulated dust. After the mixed simulated dust is scattered and shaken, the image is taken with an optical microscope and the resulting image is binarized to calculate the area ratio of the remaining mixed simulated dust. Such as the heat exchanger of claim 1, wherein the average particle diameter of the aforementioned nanoparticle is in the range of 5-100 nm. The heat exchanger of claim 1 or 2, wherein the aforementioned nanoparticles are selected from metal nanoparticles, inorganic oxide nanoparticles, inorganic nitride nanoparticles, inorganic chalcogenide nanoparticles, (former Base) at least one of the group consisting of acrylic resin nanoparticles and fluororesin nanoparticles. Such as the heat exchanger of claim 1 or 2, wherein the aforementioned antifouling The thickness of the coating film is 500 nm or less. The heat exchanger according to claim 1 or 2, wherein the antifouling coating film contains, in addition to the aforementioned nanoparticle, an adhering component, and the adhering component is at least composed of a material that has affinity with the aforementioned nanoparticle.

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