JPWO2019030905A1 - Radiant plate - Google Patents

Abstract

Provided is a radiation plate capable of improving cooling efficiency by using a ceramic powder having a high emissivity of far infrared rays and increasing the circumference of an opening. The radiation plate includes a resin substrate (2) having a plurality of openings (4), and the resin substrate (2) is formed by kneading a matrix resin with a first ceramic powder containing calcium carbonate as a main component. ..

Description

The present invention relates to a radiation plate used for a heat exchanger of an air conditioner.

In recent years, the average surface temperature of the earth has risen, and the number of air conditioners installed has increased dramatically. Even overseas, the spread of air conditioners has increased record-setting due to rising living standards. However, in some countries, where the power supply is insufficient and power outages frequently occur, there is a demand for power saving of air conditioners that consume large amounts of power.

Conventionally, the power saving of air conditioning has been dealt with by increasing the set temperature of cooling and enhancing the cold insulation effect and the heat storage effect by a heat insulating material. Further, Patent Document 1 proposes a power-saving technique that enhances the function of the heat exchanger of the air conditioner.

JP, 2014-224621, A

In the technique described in Patent Document 1, a net formed by kneading a ceramic powder containing silicon dioxide (SiO ₂ ) as a main component with a resin to form the net is used. It is described that the temperature of the passing air is changed and the heat exchange efficiency is increased by mounting the net in the air circulation path. However, although the shape of the net and the aperture ratio per unit area are described, there is no description about the effect of the type of ceramic powder, the shape of the openings, etc. on the heat exchange efficiency.

In view of the above problems, the present invention improves cooling efficiency by providing a plurality of openings in a resin base formed by kneading and molding a ceramic powder having a high emissivity of far infrared rays and increasing the circumferential length of the openings. It is intended to provide a radiation plate capable of

In order to achieve the above object, one embodiment of the present invention is a radiating plate having a plurality of openings, which is provided with a resin substrate in which a base material resin is kneaded with a first ceramic powder containing calcium carbonate as a main component. Use as a summary.

It is desirable that the first ceramic powder is blended in an amount of 35±10 mass% with respect to the base material resin. Further, the second ceramic powder containing silicon dioxide as a main component may be further kneaded. In this case, it is preferable that the first ceramic powder is mixed with the second ceramic powder in an amount of 66.6 mass% and the first and second ceramic powders are mixed with the base resin in an amount of 35±10 mass %. Further, the aperture ratio of the plurality of openings on the surface of the resin substrate is 60±5%, and in the planar shape of each of the plurality of openings, the perimeter ratio defined by the percentage of the perimeter with respect to the opening area is 35% or more. Is desirable.

According to the present invention, it is possible to provide a radiation plate capable of improving cooling efficiency by using ceramic powder having a high emissivity of far infrared rays and increasing the circumferential length of the opening.

It is a plane schematic diagram showing an example of a radiation plate concerning an embodiment of the present invention. It is an enlarged view of the opening part provided in the radiation plate shown in FIG. It is the schematic which shows the AA cross section of the radiation plate shown in FIG. It is a figure which shows an example of the infrared emissivity measurement result by the indirect measuring method of the ceramic powder A used for the radiation plate which concerns on embodiment of this invention. It is a figure which shows an example of the particle size distribution measurement result by the laser diffraction method of the ceramic powder A used for the radiation plate which concerns on embodiment of this invention. It is a figure which shows an example of the infrared emissivity measurement result by the indirect measuring method of the ceramics powder B used for the radiation plate which concerns on embodiment of this invention. It is a figure which shows an example of the particle size distribution measurement result by the laser diffraction method of the ceramic powder B used for the radiation plate which concerns on embodiment of this invention. It is a schematic plan view showing an example of a conventional radiation plate. It is a figure which shows an example of the relationship between the aperture ratio of the radiation plate and the power saving efficiency of an air conditioner which concern on embodiment of this invention. It is a figure which shows an example of the relationship of the opening area of the opening part of a radiation plate and circumference ratio which concern on embodiment of this invention. It is a figure which shows an example of the relationship between the circumference ratio of the radiation plate and the power saving efficiency of an air conditioner which concern on embodiment of this invention. It is the schematic which shows the cross section of the radiation plate which concerns on other embodiment of this invention.

An embodiment of the present invention will be described below with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and the relationship between the thickness and width of layers, the ratio of the thickness of each layer, and the like are different from actual ones. Further, it is needless to say that the drawings include parts in which dimensional relationships and ratios are different from each other.

(Embodiment)
The radiation plate according to the embodiment of the present invention is used, for example, in a heat exchanger of an air conditioner, and includes a resin substrate 2 having a plurality of openings 4 as shown in FIGS. 1 to 3. The resin substrate 2 is formed by kneading a base material resin with ceramic powder.

As a base material resin of the resin substrate 2, a resin such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), vinyl chloride (PVC), polystyrene (PS) is used. PE is excellent in fire resistance, heat resistance, chemical resistance, low temperature brittleness, moisture resistance, etc., and has good processability and is inexpensive. PE has a low softening temperature, is excellent in fluidity even when a large amount of ceramic powder is mixed, and can be processed into a complicated shape. In the embodiment, PE is used as the base material resin.

The ceramic powder contained in the resin substrate 2 converts the absorbed heat energy into a growing light beam having a wavelength in the far infrared region of 4 μm to 14 μm, and radiates the heat into the air. Far-infrared radiation characteristics of ceramic powder differ depending on the place of production, particle size, etc. For example, as shown in FIG. 4, the ceramic powder A (first ceramic powder) of a certain production area has a high emissivity of far infrared rays having a wavelength near 4 μm. The first ceramic powder contains 99% or more of calcium carbonate (CaCO ₃ ) as a main component, and contains 0.5% or less of silicon dioxide (SiO ₂ ). The particle diameter of the first ceramic powder used in the embodiment is 10 μm or less, as shown in FIG.

Further, as shown in FIG. 6, the ceramic powder B (second ceramic powder) from other producing areas has a high emissivity of far infrared rays having a wavelength near 14 μm. The second ceramic powder is made up of about 67% of SiO ₂ , which is the main component, about 15% of alumina (Al ₂ O ₃ ), about 4% of ferric oxide (Fe ₂ O ₃ ), and sodium oxide (Na ₂ O) about 4%, calcium oxide (CaO) about 3%, potassium oxide (K ₂ O) about 3%, magnesium oxide (Mg ₂ O) about 2%, titanium dioxide (TiO ₂ ) about 0%. It is contained at 0.5%. The particle diameter of the second ceramic powder used in the embodiment is 10 μm or less, as shown in FIG. 7.

The first ceramic powder generally has a high far-infrared emissivity, and the material is inexpensive. However, as shown in FIG. 4, the emissivity is partially low in the wavelength range of 5 μm to 15 μm. On the other hand, although the material cost of the second ceramic powder is higher than that of the first ceramic powder, as shown in FIG. 6, the emissivity is relatively high in the wavelength range of 5 μm to 15 μm. Therefore, as the radiation plate, the first ceramic powder alone can achieve a sufficient effect, but it is more desirable to mainly add the first ceramic powder and supplementarily add the second ceramic powder.

Even if 50% by mass or more of the ceramic powder is blended with the base material resin, the far infrared ray emissivity is slightly increased, and the cooling effect is only slightly improved. In the resin substrate 2 according to the embodiment, the first ceramic powder is blended in an amount of 35±10 mass% with respect to the base material resin in consideration of cost increase. Alternatively, when the first and second ceramic powders are mixed and used, it is desirable to mix 35±10 mass% of ceramic powder in which 66.6 mass% or more of the first ceramic powder is mixed with the second ceramic powder. Even if the second ceramic powder mixed with the first ceramic powder is increased to 1/3 mass ratio or more, the cooling effect is not improved much and the manufacturing cost is increased.

As shown in FIG. 2, the planar shape of the opening 4 has a square as a basic figure, and a rectangular projection 6 is provided on each side of the square. The length of one side of the square is L. The protrusion 6 is provided at the center of each side, has a width W, and a length P toward the opposite side. The corners of the opening 4 are rounded with a radius R. As shown in FIG. 3, the thickness of the resin substrate 2 is T. The planar shape of the opening 4 is not limited to a square, and may be polygonal or circular. The corners of the opening 4 are not limited to rounded corners and may be chamfered or may not be processed. Further, the projection 6 may be provided on at least one side, and the shape of the projection 6 is not limited.

The radiating plate has a rectangular shape, and a convex portion 10a and a concave portion 10b are provided on the outer circumference. The convex portion 10a and the concave portion 10b provided on one side of the radiation plate can be fitted to the concave portion 10b and the convex portion 10a on the opposite side, respectively. By connecting the protrusions 10a and the recesses 10b to each other, the radiation plate can be easily installed in conformity with the shape of the heat exchanger.

(Method for manufacturing radiation plate)
An example of the radiation plate according to the embodiment will be described. First, a ceramic powder in which the first ceramic powder is mixed in an amount of about 67% or more with respect to the second ceramic powder is prepared. The mass ratio of the ceramic powder to the PE resin of the base resin is 80:20, and the mixture is put into a heated kneading device and sufficiently kneaded until uniform. The kneaded material is continuously extruded while being extruded from a multi-hole nozzle having a diameter of 3 mm to prepare pellets having a diameter of about 3 mm and a length of about 2.5 mm, which is used as a master batch.

Pellets prepared as a masterbatch containing about 80% by mass of ceramic powder and PE resin-only pellets were mixed in a mixer so that the target compounding ratio, for example, about 35% by mass of ceramic powder, was mixed, Use pellets with the mixing ratio.

The pellets in the normal mixing ratio are heated to a temperature at which they can flow in an injection molding machine. The mold is pushed into the mold from the injection molding machine, and after cooling, the molded radiation plate is taken out from the mold. In this way, the radiation plate according to the embodiment is manufactured. As shown in FIGS. 5 and 7, the ceramic powder has a fine particle diameter of 10 μm or less, so that it can be easily kneaded with the base material resin. Further, even if the ceramic powder is kneaded with the base material resin in a high proportion of 30% by mass or more, the surface of the molded radiation plate can be made smooth because the particle diameter is small.

(Example)
In order to increase the cooling efficiency of the radiation plate, it is necessary to increase the far infrared ray emissivity of the resin substrate 2. When the radiation plate is installed on the air intake side of the outdoor unit or the indoor unit of the air conditioner, the thickness T of the resin substrate 2 is preferably 2 mm to 3 mm. If the thickness T is less than 2 mm, the contact area with the air flowing into the radiating plate decreases, and the far infrared emissivity decreases. When the thickness T is thicker than 3 mm, the air blowing resistance increases and the cooling effect is suppressed. Further, considering the ease of processing, the heat T is preferably 2.4 mm±1 mm.

In the conventional radiation plate, the shape of the plurality of openings 4a arranged in the resin substrate 2 is, for example, a regular hexagon as shown in FIG. Alternatively, the shape of the opening 4a may be square or perfect circle. If the opening ratio defined by the percentage of the opening area of the plurality of openings 4a with respect to the total surface area of the resin substrate 2 is small, the ventilation resistance increases and the cooling efficiency decreases. In the conventional radiation plate, in order to increase the cooling efficiency, the opening area of each opening 4a is increased to increase the aperture ratio.

However, even if the opening area of the opening 4a is increased, the cooling effect may be decreased. In order to increase the cooling effect, it is necessary to increase the area where air contacts the resin substrate 2 and increase the radiation amount of far infrared rays. As shown in the table of FIG. 10, in the planar shape of the openings 4 and 4a, the perimeter ratio defined by the percentage of the perimeter with respect to the opening area decreases as the opening area increases. For example, the perimeter ratio of the conventional opening 4a is large at about 32% for a square, about 30% for a regular hexagon, and about 29% for a perfect circle when the opening area is about 158 mm ² . When the opening area is increased to about 253 mm ² , the perimeter is reduced to about 25% for squares, about 23% for regular hexagons, and about 22% for perfect circles.

The opening 4 of the embodiment shown in FIG. 10 has the same shape as that of FIG. When the opening area is approximately 158 mm ² , the length L is 13.5 mm, the width W is 2.4 mm, the length P is 1.6 mm, and the radius R is 1.2 mm. When the opening area is about 253 mm ² , the length is L to 17 mm, the width is W to 3 mm, the length is P to ² mm, and the radius is R to 1.5 mm. As shown in the table of FIG. 10, the perimeter and perimeter of the opening 4 according to the embodiment are both about 44% to about 47% larger than the largest square of the conventional opening 4a.

In order to evaluate the cooling efficiency of the radiation plate according to the embodiment, the radiation plate was attached to the air intake side of the outdoor unit of the air conditioner to measure the power saving efficiency of the air conditioner. The mixing ratio of the first and second ceramic powders contained in the resin substrate 2 is 2:1. The radiation plate is provided with the openings 4 having an opening area of about 253 mm ² shown in the table of FIG. FIG. 9 shows the relationship between the aperture ratio of the radiation plate and the power saving efficiency of the air conditioner according to the embodiment. As shown in the table of FIG. 9, the aperture ratio is about 40%, the power saving efficiency is about 3% to about 9%, the aperture ratio is about 50%, the power saving efficiency is about 14% to about 21%, and the aperture ratio is about 60%. %, the power saving efficiency is about 20% to about 36%, and the power saving efficiency increases as the aperture ratio increases.

FIG. 11 shows the relationship between the circumference ratio of the radiation plate and the power saving efficiency of the air conditioner according to the embodiment. As a comparative example, FIG. 11 also shows the evaluation results of the radiation plate having the square and perfect circle shapes shown in FIG. 10 and having the opening 4a having an opening area of about 253 mm ² . The aperture ratio is about 60% in both the example and the comparative example. As shown in the table of FIG. 11, in the embodiment, the circumference ratio is about 36% and the power saving efficiency is about 20% to about 36%. In the comparative example, the circumference ratio is about 25% for a square and about 22% for a perfect circle, and the power saving efficiency of each is about 15% to about 28% and about 12% to about 24%. Thus, the power saving efficiency is increased by the increase of the circumference ratio.

In order not to reduce the cooling efficiency, it is desirable that the aperture ratio is 60%±5% and the circumferential length ratio is 35% or more. As shown in FIG. 10, when the aperture ratio is increased, the circumference ratio is decreased. For example, when the aperture ratio exceeds 60% and becomes large, the cooling efficiency is reduced due to the decrease in the circumference ratio.

As described above, according to the embodiment, the ceramic powder mixed with the base material resin has a high far-infrared emissivity. Further, in the resin substrate 2, a square is used as a basic figure, and the openings 4 in which the rectangular protrusions 6 are installed are arranged on each side of the square to suppress the decrease in the circumference ratio due to the increase in the opening ratio. There is. As a result, it is possible to realize a radiation plate capable of improving cooling efficiency.

(Other embodiments)
As described above, the present invention has been described by way of embodiments, but it should not be understood that the descriptions and drawings forming a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.

In the embodiment, as shown in FIG. 3, the peripheral portion of the opening 4 is formed at a substantially right angle. In this case, there is a possibility that the flow of air is disturbed at the peripheral edge of the opening 4 to increase the ventilation resistance and reduce the cooling efficiency. As shown in FIG. 12, on one surface side of the resin substrate 2, the peripheral edge portion 8 of the opening 4 including the protrusion 6 is rounded. For example, in an outdoor unit of an air conditioner, a radiation plate is attached so that air is taken in from the one side whose peripheral edge 8 is rounded. The air can smoothly flow into the opening 4 having the rounded peripheral portion 8 and can suppress the decrease in cooling efficiency. The radius of rounding is preferably 0.5 mm to 2 mm, more preferably 1 mm±0.1 mm. When the radius of rounding is out of the range of 0.5 mm to 2 mm, the ventilation resistance becomes remarkable.

As described above, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the matters specifying the invention according to the scope of claims appropriate from this disclosure.

2... Resin base 4... Opening 6... Protrusion 8... Peripheral part

Claims (10)

A radiation plate, comprising: a resin base having a plurality of openings, wherein the resin base is formed by kneading a base material resin with a first ceramic powder containing calcium carbonate as a main component. The radiation plate according to claim 1, wherein the resin base material contains the first ceramic powder in an amount of 35±10% by mass with respect to the base material resin. The radiation plate according to claim 1, wherein the resin base is formed by further kneading the base resin with a second ceramic powder containing silicon dioxide as a main component. The radiation plate according to claim 3, wherein the resin base contains the first and second ceramic powders mixed in an amount of 35±10 mass% with respect to the base resin. The radiation plate according to claim 3 or 4, wherein the first ceramic powder is mixed in an amount of 66.6 mass% or more with respect to the second ceramic powder. The radiation plate according to claim 1, wherein each of the first and second ceramic powders has a particle size of 10 μm or less. The opening ratio of the plurality of openings on the surface of the resin substrate is 60±5%, and in the planar shape of each of the plurality of openings, the perimeter ratio defined by the percentage of the perimeter with respect to the opening area is 35% or more. It exists, The radiation plate of any one of Claims 1-6 characterized by the above-mentioned. The radiation plate according to claim 7, wherein the planar shape has a regular polygon as a basic figure, and at least one side of the regular polygon is provided with a protrusion extending from the one side to the opposite side. 8. The radiating plate according to claim 7, wherein the planar shape has a square as a basic figure, and rectangular protrusions extending from each side to the opposite side are provided on each side of the square. The radiation plate according to any one of claims 7 to 9, wherein a peripheral edge portion of each of the plurality of openings is rounded on the surface side of the resin substrate.

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