JP2002071297A - Photocatalytic heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalytic heat exchanger having an excellent hydrophilicity, an excellent deodorizing property and a good press workability without causing silica odor. SOLUTION: The photocatalytic heat exchanger is characterized in that a fin 21 surface of the heat exchanger is coated with photocatalytic particles 32 made by coating a ceramic film having fine pores and inactive as a photocatalyst on a surface of titanium oxide particles and a hydrophilic organic binder 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger for an air conditioner, and more particularly, to a photocatalytic heat exchanger which realizes an excellent deodorizing function in an air conditioner for home use or automobile use.

[0002]

2. Description of the Related Art Activated carbon, ozone, noble metal-based oxidation catalysts, and the like have been used for deodorization in conventional air conditioners. However, in either method, it is necessary to install the air conditioner at a position that does not obstruct the flow path of the air flowing into and out of the heat exchanger so as not to obstruct the cooling and heating functions inherent to the air conditioner. For this reason, the contact area with the odorous gas is small, and at present, sufficient deodorizing performance cannot be obtained.

As a method for solving the above-mentioned problem, there has been proposed a photocatalytic heat exchanger in which a titanium oxide powder as a photocatalyst is formed on an aluminum fin of a heat exchanger together with a silica-based inorganic binder (Japanese Patent Application Laid-Open No. Hei 8-8). No. 296992). Specifically, as shown in FIG. 4, a corrosion-resistant coating 42 and a coating 45 composed of titanium oxide fine particles 43 and a silica-based inorganic binder 44 are sequentially formed on the surface of the main body portion 41 of the aluminum fin. 4
By irradiating the ultraviolet light 3 with the ultraviolet light, deodorization is performed by decomposition of the odor gas contacted by the photocatalytic action generated on the surface of the titanium oxide fine particles 43. In other words, since the heat exchanger has a large contact area with odor gas and is coated with a photocatalyst, superior deodorization performance can be obtained compared to the conventional deodorization method using a noble metal-based oxidation catalyst. Having.

[0004] Titanium oxide also exhibits superhydrophilicity when irradiated with an ultraviolet lamp. It was said that moisture existing near the heat exchanger surface became water droplets on the aluminum fin surface, which was a problem with the conventional heat exchanger, and that the air was blown into the room from the air outlet of the cooling air and the floor was wetted by the wind Can also be prevented.

[0005]

However, in the photocatalytic heat exchanger, since a silica-based inorganic substance is used as the binder, there is a problem that an unpleasant cement odor is generated immediately after the start of the cooling / heating operation.

[0006] The conventional photocatalytic heat exchanger also has a problem in production. The photocatalytic heat exchanger first forms a titanium oxide photocatalyst powder silica-based inorganic binder on an aluminum fin to form a photocatalytic film, and then presses the fin material using a volatile press oil to form a fin of a predetermined shape. Further, after the fins are combined with the refrigerant tube, the fins are heated and dried at a predetermined temperature to degrease volatile press oil to produce the fins. At this time, since the titanium oxide and the inorganic binder constituting the photocatalytic film are both hard materials, the film formed at the time of pressing is peeled off, and the wear of a press tool used at the time of press working becomes severe. There was a problem in press formability.

To solve these problems, it is effective to use an organic binder. However, when an organic binder is used, the photocatalytic action of titanium oxide not only decomposes the odorous gas that has come into contact, but also decomposes the organic binder. However, there was a defect that it was peeled off.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a photocatalytic heat exchanger which realizes an excellent deodorizing function in an air conditioner for home use or automobile use.

[0009]

In order to achieve the above object, a photocatalyst heat exchanger of the present invention uses a fin surface made of a heat conductive metal material as a photocatalyst having fine pores on the surface of titanium oxide particles. The photocatalyst particles coated with an inert ceramic film are coated with an organic binder.

As described above, since an organic binder is used as a binder, it is possible to eliminate generation of an unpleasant cement odor when a silica-based inorganic binder is used. In addition, by using photocatalyst particles having titanium oxide particles coated with an inert ceramic film as a photocatalyst having fine pores on the surface of titanium oxide particles, the titanium oxide and the organic binder do not come into direct contact with each other. The photocatalytic action of titanium oxide at the time of irradiation can prevent the organic binder from decomposing and deteriorating.

Here, the heat conductive metal material is desirably aluminum or an aluminum alloy.

The invention of claim 2 is characterized in that, in the invention of claim 1, the organic binder has hydrophilicity.

As described above, the structure in which the organic binder has hydrophilicity is a structure in which the photocatalyst particles to be used are formed by coating the surface of titanium oxide particles with an inert ceramic film as a photocatalyst having fine pores. This is because the decrease in the superhydrophilic effect on the surface of the photocatalyst particles as compared with the case of using the conventional titanium oxide powder is compensated for by the hydrophilicity of the binder.

At this time, as the organic binder,
It is desirable to use a polymer containing (meth) acrylic acid or vinyl alcohol as a polymerization unit, a cellulose compound, or a mixture thereof.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. 1 is a schematic side view of the inside of an indoor unit of an air conditioner using the photocatalytic heat exchanger of the present invention, FIG. 2 is a perspective view of the photocatalytic heat exchanger of the present invention, and FIG. 3 is an aluminum fin of the photocatalytic heat exchanger of the present invention. FIG.

As shown in FIG. 1, a photocatalytic heat exchanger 12, an ultraviolet lamp (15 W; peak wavelength 365 nm) 13, and a blower 14 are provided in the indoor unit 11. As shown in FIG. 2, the photocatalyst heat exchanger 12 has a structure in which a large number of aluminum fins 21 are attached in parallel at regular intervals to a metal pipe 22 which is a passage for a refrigerant. As shown in FIG. 3, the aluminum fins 21 are made of a photocatalyst particle 32 formed by coating a surface of a main body 31 made of aluminum with an inert ceramic film as a photocatalyst having fine pores on the surface of titanium oxide particles. And a film 34 formed of an organic binder 33.

Here, in the indoor unit 11,
As shown by the arrow, the indoor air passes through the photocatalytic heat exchanger 12 from above the indoor unit 11 and further passes through the blower 14.
After passing through, the air is discharged from the lower part of the indoor unit 11 into the room. Further, by turning on the ultraviolet lamp 13, the odor gas contained in the room air in contact with the photocatalyst particles 23 in the coating 25 formed on the surface of the aluminum fin 21 of the photocatalyst heat exchanger 12 is decomposed by photocatalysis. It is deodorized. Further, since the organic binder 33 has hydrophilicity, it is possible to prevent a problem that water droplets are generated on the surface of the aluminum fin 21 and the floor is wet as it is from the outlet and wets the floor.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The photocatalyst heat exchanger of the present invention will be described below together with its manufacturing method.

(Example) As an aluminum fin material, an aluminum plate (material: 1330, thickness: 0.1 mm, temper: H26) previously degreased and washed with water was used. The photocatalyst powder is a powder obtained by coating the surface of anatase-type titanium oxide particles having a particle size of about 40 nm with porous alumina having pores of 10 nm (for example, Patent Publication: No. 2).
945926) was used. In addition, the binder
Polyvinyl alcohol which is a polymer compound having hydrophilicity was used.

The titanium oxide photocatalyst powder coated with porous alumina is coated on an aluminum plate together with polyvinyl alcohol as a hydrophilic organic binder, and dried by heating at 200 ° C. for 30 seconds. A photocatalytic film having a thickness of 0.5 μm was formed thereon. Then, the fin material was pressed using a volatile press oil to form fins having a predetermined shape. Furthermore, after assembling this fin to the refrigerant tube,
By heating and drying at a predetermined temperature, the volatile press oil was degreased, and a photocatalytic heat exchanger A was produced.

Comparative Example Next, as a comparative example, anatase-type titanium oxide particles (ST-01, Ishihara Sangyo) having a particle size of about 7 nm were used as a photocatalyst powder, and a silica-based inorganic material was used as a binder. After the application, it was dried by heating at 150 ° C. for 30 minutes to form a photocatalytic film having a thickness of 0.5 μm. And the photocatalyst heat exchanger B was produced like the above-mentioned method.

(Experiment 1) The odor of the obtained photocatalyst heat exchanger A and photocatalyst heat exchanger B was evaluated. The odor was evaluated by a panelist after performing a breath blow. As a result, the photocatalyst heat exchanger B of the present invention felt a rather strong odor, while the photocatalyst heat exchanger A of the present invention hardly felt it.

(Experiment 2) Next, the workability in producing the photocatalytic heat exchanger was evaluated. The evaluation was performed by observing the state of peeling of the inner surface of the collar when processing was performed using a drawless die (ironing rate: 52%) which is an ironing method.

As a result, when a titanium oxide photocatalyst powder coated with the porous alumina of the present invention and a photocatalytic film of polyvinyl alcohol as a hydrophilic organic binder are formed on aluminum fins, a heat exchanger is formed. For this reason, no peeling was observed even when pressing was performed. However, when the photocatalyst film was formed by the conventional titanium oxide photocatalyst powder and the silica-based inorganic binder, peeling of the film was observed in some places by press working.

From the above results, it can be seen that the photocatalytic heat exchanger A having the configuration of the present invention is more excellent in workability at the time of production than the photocatalytic heat exchanger B having the conventional configuration. In the present invention, by using an organic binder, the adhesion between the aluminum fin and the photocatalyst film is improved, and the organic binder is softer and has better processability than the conventional silica-based inorganic binder. ,
It is thought that this is the cause.

(Experiment 3) Further, with respect to the obtained photocatalyst heat exchanger A and photocatalyst heat exchanger B, a part of the fin was cut out (size: 5 mm square) to prepare each sample.
The hydrophilicity was evaluated by measuring the contact angles of water drops of these samples. The hydrophilicity was evaluated by irradiating each sample for 10 minutes at an irradiation distance of 25 cm using a fluorescent lamp light source (15 W; peak wavelength 365 nm) in the ultraviolet region.
After a certain period of time, 1 microliter of ultrapure water (μ
1) is dropped, and the contact angle of ultrapure water is measured using a contact angle meter.

As a result, the contact angle of the fins in the photocatalytic heat exchanger A of the present invention was 8 ° immediately after the start of the elapsed time measurement, 11 ° after 12 hours, and 12 ° after 36 hours. The contact angle of the fins in the comparative photocatalytic heat exchanger B was 7 ° immediately after the start of the elapsed time measurement, 12 ° after 12 hours, and 14 ° after 36 hours.

From the above results, the photocatalytic heat exchange A of the present invention
Was found to have the same level of hydrophilicity as the conventional photocatalytic heat exchanger B.

(Experiment 4) The photocatalytic heat exchanger A of the present invention described above.
The deodorizing performance of the air conditioner indoor unit (both having the structure shown in FIG. 1) was evaluated using the air conditioner indoor unit using the photocatalyst heat exchanger B of the comparative example. The specific evaluation method is a photocatalyst heat exchanger A and a photocatalyst heat exchanger B
Air conditioner indoor units, each with a height of 2m and a width of 4
m, an airtight laboratory (20 m in room temperature, 4 m in depth)
(filled with acetaldehyde having a concentration of ppm), the temperature was set to 20 ° C., the cooling operation was performed while maintaining the humidity at 40%, and the photocatalytic decomposition performance of acetaldehyde was measured. In addition, the drain hose of the dehumidified dew condensation water which is usually taken out of the room was guided into a plastic tank provided in the airtight laboratory in order to ensure the airtightness of the laboratory.

As a result, in the indoor unit of the air conditioner using the comparative photocatalytic heat exchanger B, the concentration of acetaldehyde after about 30 minutes was 10 ppm and 3 ppm after 1 hour.
In the photocatalyst heat exchanger A of the present invention, the concentration of acetaldehyde after about 30 minutes was 9 ppm, and was 3 ppm after 1 hour. That is, it was found that the photocatalyst heat exchanger A of the present invention had excellent deodorizing properties as in the case of the conventional photocatalyst heat exchanger B.

From the results of Experiments 1 and 2, the photocatalytic heat exchanger A of the present invention solves the problems of cement odor and workability of the conventional photocatalytic heat exchanger B. From the results of Experiment 4, it can be seen that they have hydrophilic properties and deodorizing properties equivalent to those of the conventional photocatalytic heat exchanger.

In the photocatalyst particles of the embodiment of the present invention, alumina was used as the photocatalytically inactive ceramic film having fine pores coated on the surface of the titanium oxide particles. However, the present invention is not limited to this. Similar results were obtained with titanium oxide, zirconium oxide, silicon oxide, magnesium oxide and calcium oxide. In addition,
Although polyvinyl alcohol was used as the organic binder in the examples of the present invention, the present invention is not limited thereto, and any polymer containing (meth) acrylic acid or vinyl alcohol as a polymerization unit, a cellulose compound, or a mixture thereof may be used. Similar results were obtained. Specifically, poly (meth) acrylic acid, a copolymer of poly (meth) acrylic acid and polyvinyl acetate, a copolymer of poly (meth) acrylic acid and polyvinyl alcohol, and poly (meth) acrylic acid Cellulose copolymer, poly (meth) acrylic acid and starch copolymer, poly (meth) acrylamide,
Poly (meth) acrylamidomethylpropanesulfonic acid, copolymer of (meth) acrylic acid and polyamide, polyvinyl alcohol, partially saponified polyvinyl acetate,
It is a cellulosic resin.

In the embodiment of the present invention, the photocatalyst film is formed directly on the fins of aluminum or the like. However, the present invention is not limited to this. A chromate treatment layer is provided on the aluminum fins as a corrosion-resistant film. The same effect was obtained in the configuration in which the photocatalyst was formed above.

[0034]

As is clear from the above description, the photocatalyst heat exchanger of the present invention uses the fin surface of the heat exchanger with an inactive ceramic film as a photocatalyst having fine pores on the surface of titanium oxide particles. Because it is a configuration coated with the coated photocatalyst particles and the organic binder, compared with the conventional titanium oxide particles and the case of coating with the silica-based inorganic binder,
In addition to having excellent deodorizing performance and hydrophilic performance, there is an effect that there is no generation of cement odor and further excellent press workability.

[Brief description of the drawings]

FIG. 1 is a schematic side view of the interior of an indoor unit of an air conditioner using the photocatalytic heat exchanger of the present invention.

FIG. 2 is a perspective view of the photocatalytic heat exchanger of the present invention.

FIG. 3 is a cross-sectional view of the aluminum fin of the present invention.

FIG. 4 is a cross-sectional view of a conventional photocatalytic heat exchanger.

[Explanation of symbols]

Reference Signs List 11 Indoor unit of air conditioner 12 Photocatalytic heat exchanger 13 Ultraviolet lamp 14 Blower 21 Aluminum fin with photocatalytic coating 22 Metallic pipe 31 Aluminum fin 32 The surface was coated with an inert alumina film as a photocatalyst having fine pores Photocatalyst particles 33 Organic binder (polyvinyl alcohol) 34 Photocatalytic film 41 Aluminum fin 42 Titanium oxide particles 43 Silica-based inorganic binder 44 Photocatalytic film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B60H 3/00 F25B 39/00 P F24F 1/00 F28F 13/18 B F25B 39/00 B01D 53/36 H F28F 13/18 F24F 1/00 371 Z F-term (reference) 3L051 BC05 BC10 4C080 AA07 BB02 CC01 HH05 JJ04 KK08 LL02 LL03 MM02 NN02 4D048 AA22 AB01 AB03 BA03X BA07X BA39X BB03 BC07 CC33 CC34 CC42 EA01 4G069 AA03 BA04 CA07 BA01 BA01 CA04 EC22Y EE01 EE07 FA04 FB23

Claims (2)

[Claims] 1. A structure in which a fin surface made of a heat conductive metal material is coated with a photocatalyst particle having a surface of titanium oxide particles coated with an inert ceramic film as a photocatalyst having fine pores, and an organic binder. A photocatalytic heat exchanger. 2. The photocatalytic heat exchanger according to claim 1, wherein the organic binder has a hydrophilic property.