JPH0345894A - Fin material for heat exchanger - Google Patents

Abstract

PURPOSE:To reduce a decrease in room heating and cooling capacity of a heat pump by employing a fin material provided with a thin film to follow rough surface of an aluminum film material having an uneven parts of specific surface roughness as a fin material for a heat exchanger on the fin material. CONSTITUTION:An aluminum fin material for a heat exchanger is composed of an aluminum alloy plate imparted with surface roughness of 0.2 - 5mum to its surface, and a water repellent thin film so coated as to follow the uneven part of the surface. Thus, since droplets adhered to the surface are easily rolled to be dropped without remain due to small contact of the droplet with the surface in addition to the water repellent effect of the thin film, a fin material for a heat exchanger having high performance can be obtained. For example, carbon tetrafluoride plasma polymerized coating resin film is formed on an aluminum alloy plate added directly with an uneven part on its surface to obtain an aluminum film material. In this case, the rough surface may be formed by rolling or ceramic coating, or a coating may be formed of a LB film, by a sputtering, a depositing method.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fin material for a heat exchanger, and more particularly to a fin material for a heat exchanger that prevents condensed water from accumulating on its surface.

Conventional technology In recent years, the proportion of air-source heat pump type air conditioners (hereinafter simply referred to as heat pumps) among air conditioners has rapidly increased, and they now account for more than half of household rule air conditioners, commercial room air conditioners, etc. ing. Furthermore, most of the heat exchangers used in these heat pumps are fin-tube heat exchangers that are composed of aluminum fins and refrigerant pipes that run perpendicularly to the aluminum fins. When a heat pump is used for cooling, moisture condenses on the fin surface of the indoor heat exchanger, causing a bridging phenomenon of condensed water between the fins, resulting in a decrease in the amount of air passing through the indoor heat exchanger.
This in turn causes a decrease in cooling capacity. On the other hand, during heating, the same phenomenon occurs in the outdoor heat exchanger as in the aforementioned indoor heat exchanger during cooling. During noisy heating, frost builds up on the outdoor heat exchanger due to the outside temperature.

If frost forms on the outdoor heat exchanger, ventilation resistance increases,
This will cause a decrease in heating capacity, and if the heating progresses further, the fins will become clogged due to frost formation, in which case heating operation will need to be temporarily stopped and defrosted, which will impair the comfort of heating. It can also be a cause. Therefore, in order to reduce the decline in the cooling capacity and heating capacity, and to reduce frost formation on the outdoor unit heat exchanger that is pressed during heating, reduce the number of times of defrosting, and improve comfort, it is necessary to All you have to do is constantly remove the condensed water on the fin surface of the machine's heat exchanger. One way to do this is to make the fin surface water repellent so that the condensed water rolls off.

As a method for this, coating with tetrafluoroethylene resin, trifluoroethylene chloride resin, etc. is known, as proposed in, for example, Japanese Utility Model Application Publication No. 48-11414 and Japanese Utility Model Application Publication No. 51-15261. .

Problems to be Solved by the Invention On the surface of the fin material coated with the resin with excellent water repellency, it is possible to roll off relatively large condensed water with a diameter of about 2 microns or more from the fin surface. It can be expected to have some effect as a fin material. However, in recent heat exchangers, the fin spacing tends to become narrower in order to increase the total fin surface area in order to increase the capacity. The fin spacing of current heat exchangers is generally about 2 to 3 m, and the method of applying resin with excellent water repellency described above involves dropping fine droplets of about 1 inch in diameter from the fin surface. Since water droplets remaining on the fin surface create bridges between the fins and accumulate, this creates ventilation resistance and freezes on the casing, forming frost.

Its water repellent effect was insufficient. Therefore, it is an object of the present invention to provide a high-performance fin material for a heat exchanger that can constantly remove condensed water on the surface of the fins so as not to reduce the cooling/heating capacity of the heat pump.

Means for Solving the Problems To achieve this object, the aluminum fin material for heat exchangers of the present invention consists of a 7-luminium alloy plate whose surface has been given a surface roughness of 0.2 μm to 5 μm, and an uneven surface. It is composed of a water-repellent thin film coated to conform to the water.

Effect With the above structure, water droplets adhering to the surface not only have the water-repellent effect of the thin film, but also the contact area between the surface and the water droplets is small, so they easily roll off and do not remain behind, allowing for high-performance heat treatment. Fin material for exchangers can be obtained.

Example An embodiment of the present invention will be described below.

The table shows, as an example, an aluminum fin material in which a 47 fluorocarbon deosma polymerization coating resin film was formed on an aluminum alloy plate whose surface was directly roughened by chemical treatment, so as to follow the roughness, and as a comparative example, an aluminum fin material was used. 47 fluorocarbon plasma
This figure shows the falling angle when a water droplet with a diameter of about 1 drop is dropped on an aluminum fin material with a coating resin film formed on it, and an aluminum fin material with a fluorocarbon resin spray-coated on an aluminum alloy plate whose surface is directly textured. The falling angle refers to the angle of inclination of the sample plate at the point when the sample surface is tilted and droplets dropped onto the surface begin to fall. The smaller the falling angle, the smaller the interaction between the sample surface and the droplet, which means that the droplet falls more easily. On the other hand, if the interaction between the sample surface and the droplet is too large, the droplet will not fall even if the sample surface is tilted 90 degrees.

As can be seen from the table, in the comparative example, the droplet did not fall even when the sample surface was tilted 90 degrees, but in this example, the falling angle was significantly smaller. This is because, in addition to the plasma-polymerized film making the surface water-repellent, the unevenness on the fins reduces the contact area with droplets and keeps the droplets on the fin surface. This is because it is not possible. Surface roughness 0
．． If the thickness was 1 μm, the effect could not be obtained as shown in Comparative Example 1, so a thickness of 0.2 μm or more is required. In addition, even if the surface roughness is 5 μm or more, for example 10 μm, Comparative Example 2
As shown in Figure 2, this effect cannot be obtained, and the thickness needs to be 5 μm or less. Furthermore, when using a normal coating method, even if the surface of the substrate is roughened, the surface roughness of the coating does not conform to the provided unevenness and is only about 0.1 μm, but when viewed microscopically, it becomes a smooth surface, so it is not effective. In this example, chemical treatment was used as a method of forming unevenness on the aluminum fin material, but other methods include forming unevenness directly during rolling by roll processing, forming a rough surface by using ceramic coating, etc. A similar effect can be obtained by other methods. Furthermore, although plasma polymerization was used as a thin film coating in this embodiment, any method that follows the irregularities of the aluminum substrate may be used, and similar effects can be obtained by, for example, an LB film, sputtering, or vapor deposition method.

Effects of the Invention In the present invention, a fin material in which a thin film is applied to an aluminum fin material having irregularities with a surface roughness of 0.2 μm to 5 μm so as to follow the rough surface is used as a fin material for a heat exchanger. Shi, the fin spacing is 2m! It has effective performance in rolling off water droplets condensed on the fin surface even when the width is as narrow as 1.

Therefore, by delaying the cracking between the fins of the heat pump heat exchanger due to frost formation, it is possible to reduce the decrease in the cooling and heating capacities of the heat pump, and to extend the defrosting interval for outdoor unit heat exchange during heating. O that can improve comfort

Claims (1)

[Claims] An aluminum alloy plate with a surface roughness of 0.2 μm to 5 μm,
A fin material for heat exchangers that has a water-repellent thin film that follows the rough surface.