JPS61250494A - Heat exchanger - Google Patents

Abstract

PURPOSE:To prevent the corrosion of the heat exchanger and improve the durability and reliability of the same by a method wherein a coating layer, consisting of organic resin binder, is formed on the surface of copper made heat transfer member at the side contacting with water and, further, another coating layer, consisting of a coating, in which alkaline glass powder is dispersed into and mixed with the organic resin binder, is formed thereon so that a part of the copper made heat transfer member is exposed. CONSTITUTION:The coating layer 5, consisting of organic resin binder, and another coating layer 6, consisting of a coating, in which alkaline glass powder is dispersed into and and mixed with the organic resin binder, are formed on the surface of the heat exchanger 2, consisting of the copper made heat transfer members, so that the exposed member 2' of the heat exchanger is existing. When the heat exchanger 2 is used under a circumstance, in which the quality of water is low in PH value and strong in corrosive property, alkaline content is eluated from the alkaline glass dispersed in the upper coating layer 6, therefore, the water is neutralized and the corrosive property thereof is eliminated. When the neutralizing function, effected by the coating layer 6, is lost, corrosive elements in water begin the corrosion reaction between the heat exchanger 2, however, the corrosion is caused on only the exposed section 2' of the heat exchanger.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat exchanger made of a copper heat transfer member used in solar water heaters, electric water heaters, and the like.

BACKGROUND OF THE INVENTION Copper, which is a heat transfer member of a heat exchanger, corrodes in a water environment such as underground water where the pH (hydrogen ion concentration) is 7 or less and a large amount of free carbonate and anions are present. When water containing copper ions eluted due to this corrosion is used in a bath,
There was a problem in that copper ions reacted with resin acids such as soap to form blue complex salts, which adsorbed to towels and bathtub walls, causing them to turn blue.

Conventionally, as a means to solve this problem, (1) a metal plating layer of nickel, tin, etc. is provided on the surface of a copper heat transfer member.

(2) Provide a coating layer using organic or inorganic paint.

(3) A rust preventive agent such as a silicate or phosphate polymer is added to water to form a protective film of the rust preventive component on the surface of the copper heat transfer member.

There is such a thing.

Problems to be Solved by the Invention The above-mentioned nickel and tin plating layer has only a short-term corrosion protection effect because the metal plating corrodes in a short period of time in an environment with poor water quality, and the copper is exposed as the plating layer wears out. Corrosion factors enter through the existing pinholes and gaps in the molecular structure of the paint coating layer and corrode the copper, which damages the adhesion of the coating layer and causes phenomena such as peeling. There was a problem that the anticorrosion effect was only for a short period of time.

In addition, the protective film made with rust preventive agents deteriorates and peels off in a short period of time, so it is necessary to add rust preventive agents periodically.
There was a problem in that it was difficult to manage in ordinary households.

The present invention solves such conventional problems and prevents corrosion of heat exchangers made of copper heat transfer members over a long period of time, thereby significantly improving durability and reliability.

Means for Solving the Problems In order to solve the above-mentioned problems, the heat exchanger of the present invention includes a coating layer made of organic resin Pine Goo on the surface of the copper heat transfer member on the side that comes into contact with water, and a coating layer made of organic resin Pine Goo. A coating layer made of a paint obtained by dispersing and mixing alkali glass powder into an organic resin binder is formed so that a part of the copper heat transfer member is exposed.

Function: With the above configuration, even if the heat exchanger is placed in a water environment with low pH and strong corrosivity, such as underground water, the coating made of the organic resin binder and alkali glass powder formed on the copper heat transfer member can be used. Since the alkali content in the alkali glass is eluted from the layer, water is neutralized and corrosivity can be eliminated.

On the other hand, even if all the alkaline content in the coating layer is eluted and the neutralization function is lost, the coating layer is formed on the copper heat transfer member so that a part of it is exposed, so corrosion will not occur in the exposed part ( Since the corrosion area becomes extremely small, the amount of copper eluted can be significantly suppressed. Furthermore, even if pinholes exist in the coating layer, the corrosion factors in water are consumed by the corrosion reaction in the exposed portions, so pinhole corrosion does not occur.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

FIG. 2 is a sectional view of a heat pipe type solar water heater applied as an example of the present invention. In the figure, 1 is a solar heat collecting plate, 2 is a heat exchanger made of a copper heat transfer member, 3 is a heat medium such as fluorocarbon gas, and 4 is a hot water storage tank for storing water. The present invention is applied to a heat exchanger made of the copper heat transfer member.

FIG. 1 is a sectional view of a main part of a heat exchanger made of a copper heat transfer member showing an embodiment of the present invention. In the figure, 5 is a coating layer made of organic resin Pine Gu, and 6 is a coating layer made of paint in which alkali glass powder is dispersed and mixed in an organic resin binder.
, 6 are formed so that the heat exchanger exposed member 2 is present on the surface of the heat exchanger 2 made of a copper heat transfer member.

Examples of the organic resin binder used in these coating layers 5 and 6 include mixtures of acrylic resin, melamine resin, and epoxy resin from the viewpoints of hot water resistance, corrosion resistance, and adhesion to copper.

Further, the coating layer 6 is a porous layer in which the amount of alkali glass powder added to the organic resin binder is increased so that the alkali content is more easily eluted than the alkali glass dispersed therein.

In order to achieve this porosity, it is necessary to add 100 to 200% by weight of alkali glass powder to the solid content of organic resin Paingo.
It is desirable that

In this configuration, even if the heat exchanger 2 in the solar water heater shown in FIG. Since alkaline components are eluted from the alkali glass dispersed in the upper coating layer 6, water is neutralized and corrosivity is eliminated. Corrosion of the heat exchanger 2 is prevented until the alkaline content in the coating layer 6 is completely eliminated and the neutralization function of the water is lost, so there is no elution of copper ions, which occurs on towels and bathtub walls caused by copper ions. can solve the problem of blue discoloration.

On the other hand, when the neutralization function of the coating layer 6 is lost, the corrosive factors in the water start a corrosive reaction with the heat exchanger 2, but the heat exchanger 2r/-i and the formed part of the coating layer 5.6 Since the heat exchanger is configured to have an exposed portion 2' (uncoated portion), corrosion occurs only in this exposed portion 2' of the heat exchanger. Therefore, the corroded area of the heat exchanger 2 is small, and furthermore, due to the corrosion reaction, a chemically stable green-blue film is gradually formed on the surface of the heat exchanger exposed part 2', which is eluted from the heat exchanger 2. The amount of copper ions can be suppressed below the concentration required to turn the towels and bathtub walls blue.

Furthermore, since the coating layer 5 is made only of the organic resin Bingoo, there are very few pinholes, and corrosion through the pinholes is difficult to occur, and most of the corrosion factors are consumed in the heat exchanger exposed portion 2'. Corrosion in the area is prevented and the coating layer will not peel off. Therefore, corrosion of the heat exchanger 2 can be prevented for a long period of time, and durability and reliability can be significantly improved.

Effects of the Invention As described above, the heat exchanger of the present invention provides the following effects.

(1) Corrosion of heat exchangers made of copper heat transfer members can be significantly suppressed and copper ion elution can be prevented, thereby preventing blue discoloration of towels and bathtub walls caused by copper ions.

(2) Since each of the two coating layers has two anti-corrosion functions, the anti-corrosion effect of the heat exchanger can be maintained over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a heat exchanger showing an embodiment of the present invention, and FIG. 2 is a sectional view of a heat pipe type solar water heater using the same heat exchanger. 2...Heat exchanger, 2'...Exposed part of heat exchanger, 5...Coating layer, 6...
coating layer.

Claims (2)

[Claims] (1) A coating layer made of an organic resin binder is applied to the surface of the copper heat transfer member on the side that comes into contact with water, and a coating layer made of a paint containing an alkali glass powder dispersed in the organic resin binder is further applied on the surface of the copper heat transfer member. A heat exchanger that is formed so that some parts are exposed. (2) Claim 1, wherein the organic resin binder is a mixture of acrylic resin, melamine resin, and epoxy resin.
Heat exchanger as described in section.