JP2005083600A - Defrosting heater and defrosting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a defrosting heater capable of dispensing with a shade member, by enabling the surface temperature to exceed a safety standard provided by the Japan Electrical Manufacturers' Association on ignition of a refrigerant, even when the combustible refrigerant leaks in a defrosting state. <P>SOLUTION: This defrosting heater is composed of a metallic pipe 2, a glass tube 3 inserted into the metallic pipe 2, and a heating wire 4 inserted into the glass tube 3, and is characterized by forming a coating film composed of a highly radioactive material having higher emissivity on far infrared radiation than metal being a constituent material of the metallic pipe 2, on both of an inside surface 21 and an outside surface 21 of the metallic pipe 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heater and a system for defrosting a refrigerator of a household refrigerator. Here, the refrigerator is a concept including a freezer and a refrigerated freezer.

  As a refrigerant for a refrigerator cooler, isobutane, which is a hydrocarbon-based refrigerant, has come to be used in response to a request for environmental regulations such as prevention of ozone layer destruction and prevention of global warming. Isobutane is a flammable medium and ignites at 494 ° C., unlike alternative chlorofluorocarbon, which is a conventional refrigerant. Therefore, when isobutane is used as a refrigerant, if a defrost heater whose surface temperature is increased to near the ignition point of isobutane is used, there is a risk of ignition or explosion when the refrigerant leaks. Therefore, the Japan Electrical Manufacturers' Association stipulates that the surface temperature of the defrost heater when isobutane is used as a refrigerant must be 394 ° C. or lower, which is 100 ° C. lower than the ignition point of isobutane.

  On the other hand, as a defrosting heater, a single glass tube structure in which a heating wire is inserted through a glass tube has been generally used. However, in a defrost heater having a single glass tube structure, the surface temperature of the glass tube reaches about 450 ° C. in an open empty state. Therefore, it is no longer possible to use a conventional single glass tube structure as a defrosting heater when isobutane is used as a refrigerant.

  Therefore, a defrosting heater having a double glass tube structure as shown in Patent Document 1 has been developed and used. This is made by inserting a glass tube through which a heating wire is inserted into a glass tube having a larger diameter. According to this, since the outer glass tube has a large surface area, the surface temperature is suppressed to about 352 ° C., and the safety standard defined by the Japan Electrical Manufacturers' Association can be satisfied.

However, in the defrosting heater having a double glass tube structure, the frost on the surface of the cooler is melted by the defrosting heater, and cold water and ice pieces fall from the surface of the cooler, resulting in a high temperature on the outer glass tube surface. The glass tube on the outside may be damaged. Therefore, in order to prevent this, a structure is adopted in which the defrost heater is covered from above with an umbrella member made of metal.
JP 2002-195735 A

When the structure covered with the above-described umbrella member is employed, there are the following problems.
(1) Space and cost for arranging the umbrella member are necessary.
(2) Since the heat applied to the cooler from the defrost heater is blocked by the umbrella member, the thermal efficiency of the defrost heater is reduced.

  In the present invention, even when the flammable refrigerant leaks in a defrosted state, the surface temperature can exceed the safety standard stipulated by the Japan Electrical Manufacturers' Association regarding the ignition of the refrigerant, and the umbrella member can be made unnecessary. An object of the present invention is to provide a frost heater and to provide a defrost system capable of suppressing the surface temperature of the defrost heater to the extent that the safety standards prescribed by the Japan Electrical Manufacturers' Association are satisfied. And

  The invention according to claim 1 is a defrosting heater for a refrigerator cooler, comprising a metal tube, a glass tube inserted through the metal tube, and a heating wire inserted through the glass tube, At least one of the inner surface and the outer surface is treated so that the emissivity with respect to far infrared rays is higher than that of the metal that is a constituent material of the metal tube.

  As the metal that is a constituent material of the metal tube, aluminum is mainly used because it is inexpensive and easy to process, but copper, iron, titanium, or the like may be used. In addition, the metal mentioned here is the concept also including the alloy.

As the above processing, for example, the following three methods can be used.
・ Method of applying highly radioactive material.
A method of coloring after anodizing.
-A method for processing irregularities.

  As a method for processing the unevenness, a method of roughing the inner surface or the outer surface by, for example, blasting or a method of groove processing by, for example, knurl can be used. Incidentally, in the temperature range of 200 to 600 ° C., the emissivity of the polished surface of the aluminum material is 0.039 to 0.055, while the emissivity of the rough surface is also 0.055 to 0.078. . That is, when the rough surface is processed, the emissivity is high.

  The invention according to claim 2 is the invention according to claim 1, wherein at least one of the inner surface and the outer surface of the metal tube has a high emissivity with respect to far infrared rays higher than that of the metal that is a constituent material of the metal tube. The coating film which consists of material is formed.

The coating film is formed by applying a highly radioactive material. As the highly radioactive material, for example, the following four types can be used.
・ Organic polymer materials.
A composite material of an oxide material, a carbon material, a carbide material, etc. and the above organic polymer material.
・ Inorganic polymer materials.
A composite material of an oxide material, a carbon material, a carbide material, etc. and the above inorganic polymer material.

  As an organic polymer material, it has physical properties that can be easily applied as a single substance or diluted in a solvent, and the formed coating film has high adhesion to metals and non-metals, high hardness, and high A material having toughness is used. For example, polyester resin, amino resin, epoxy resin, polyurethane resin, acrylic resin, acrylic emulsion resin, vinyl chloride resin, fluorine resin, phenol resin, silicon resin, or the like can be used.

  The inorganic polymer material is an inorganic polymer that does not contain a carbon-carbon bond, and for example, silicate, phosphate, silica sol, alumina sol, and the like can be used.

As the oxide material, TiO ₂ , SiO ₂ , ZrO ₂ , Fe ₂ O ₃ , Cu ₂ O, or the like can be used. Carbon black, graphite, etc. can be used as the carbon material. As the carbide material, TaC, ZrC, SiC, BC or the like can be used.

  The invention according to claim 3 is the invention according to claim 2, wherein the highly radioactive material has a high emissivity with respect to far infrared rays having a wavelength of 3 to 10 μm.

  The invention according to claim 4 is the invention according to claim 1, wherein the metal tube is an aluminum tube, and a colored anodized film is formed on at least one of the inner surface and the outer surface of the metal tube. It is what.

  The anodized film that has been colored is formed by anodizing and then coloring. The anodizing treatment and the coloring treatment can be performed by a known method. For example, the coloring process includes a natural coloring method, an electrolytic coloring method, and a staining method. Natural coloring methods include alloy coloring methods and electrolytic coloring methods.

  The invention according to claim 5 is a defrosting system for a refrigerator cooler, comprising a defrosting heater and an umbrella member covering the defrosting heater from above, and at least one of the lower surface and the upper surface of the umbrella member However, it is processed so that the emissivity regarding a far infrared ray may become higher than the metal which is a constituent material of an umbrella member.

  As the defrosting heater, a conventional double glass tube structure may be used. As the processing, the same method as in the case of the defrosting heater according to claim 1 can be used.

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the defrosting heater is any one of the first to fourth aspects.

  In the first aspect of the present invention, the far infrared rays emitted from the heating wire are actively absorbed and radiated toward the cooler on at least one of the inner surface and the outer surface of the treated metal tube. The That is, heat dissipation is actively performed. For example, when only the inner surface is treated, far-infrared rays emitted by heating wires are actively absorbed on the inner surface and converted to heat, increasing the temperature of the metal tube and at the same time outside the metal tube. Heat is dissipated from the surface toward the cooler. When only the outer surface is treated, the far-infrared heat emitted by the heating wire increases the surface temperature of the metal tube, is actively absorbed on the outer surface, and is radiated toward the cooler. When both the inner and outer surfaces are treated, far-infrared rays emitted by heating wires are actively absorbed on the inner surface and converted to heat, increasing the temperature of the metal tube and at the same time Is actively absorbed and emitted towards the cooler.

  Therefore, according to invention of Claim 1, the radiation | emission of the heat | fever from a defrost heater can be increased, Therefore, a defrost effect can be improved. Moreover, since the heat generated from the heating wire can be actively and gradually dissipated successively, the temperature inside the metal tube can be suppressed low, and therefore the surface temperature of the metal tube can be suppressed to a low temperature and the safety standard can be sufficiently satisfied. .

  According to the first aspect of the present invention, since the metal pipe is provided on the outside, there is no risk of breakage even if cold water or ice pieces collide. Therefore, the umbrella member that covers the defrosting heater from above is provided. Can be made unnecessary. Therefore, the space and cost for arranging the umbrella member can be eliminated, and the defrosting system can be reduced in size and cost. Further, if the umbrella member is eliminated, the heat applied from the defrost heater to the cooler is not blocked by the umbrella member, so that heat transfer from the defrost heater to the cooler can be performed efficiently. The effect can be improved.

  According to invention of Claim 2, the defrost heater of Claim 1 is realizable easily and cheaply. In addition, the defrost heater according to claim 1, wherein the metal pipe is not limited to an aluminum pipe but is a copper pipe, an iron pipe, a titanium pipe, or the like.

  According to invention of Claim 3, since most of the far infrared rays emitted from a heating wire are far infrared rays of a wavelength of 3-10 micrometers, the defrosting effect by the defrost heater of Claim 1 can be improved more.

  According to invention of Claim 4, the defrost heater of Claim 1 is easily realizable using a well-known technique.

  In the invention according to claim 5, the far infrared ray emitted from the defrost heater is actively absorbed in at least one of the treated lower surface and the upper surface of the umbrella member toward the cooler. Radiated. That is, heat transfer from the defrost heater to the cooler is performed efficiently. For example, when only the lower surface is treated, far infrared rays emitted from the defrost heater are actively absorbed on the lower surface and radiated toward the cooler via the umbrella member. When only the upper surface is processed, the heat transmitted to the umbrella member in the far infrared rays emitted from the defrost heater is actively absorbed on the upper surface via the umbrella member, and is transferred to the cooler. Radiated towards. When both the lower surface and the upper surface are treated, far-infrared rays emitted by the defrost heater are actively absorbed on the lower surface, through the umbrella member, and further actively absorbed on the upper surface, Radiated toward the cooler.

  Therefore, according to the fifth aspect of the present invention, the heat generated from the defrost heater can be efficiently transmitted to the cooler, and therefore the defrost effect in the entire system can be improved. Moreover, this effect can be obtained by simply performing a simple treatment on the umbrella member.

  According to invention of Claim 6, the defrosting effect in the whole system can be improved more by the improvement of the defrosting effect by defrosting heater itself, and the improvement of the defrosting effect by an umbrella member.

  FIG. 1 is a partial sectional front view of the defrosting heater of the present invention, and FIG. 2 is a longitudinal sectional view of the defrosting system of the present invention. As shown in FIG. 2, the defrost heater 1 is installed directly under the cooler 10 on the back side of the refrigerator. In general, an umbrella member 20 that covers the defrost heater 1 from above is provided above the defrost heater 1. The umbrella member 20 may be provided integrally with the defrost heater 1.

  The defrosting heater 1 of the present invention has a double tube structure composed of a metal tube 2 and a glass tube 3. That is, the defrost heater 1 includes a metal tube 2, a glass tube 3 inserted through the metal tube 2, and a heating wire 4 inserted through the glass tube 3. The heating wire 4 is connected to the lead wire 6 in a cap 5 that seals the metal tube 2 and the glass tube 3 at both ends.

  In the defrosting heater 1 of the present invention, at least one of the inner surface 21 and the outer surface 22 of the metal tube 2 is processed so that the emissivity relating to far infrared rays is higher than that of the metal that is a constituent material of the metal tube 2. Has been.

(Embodiment 1)
In the first embodiment, an aluminum pipe is used as the metal pipe 2. Moreover, the highly radioactive material whose emissivity regarding far infrared rays is higher than aluminum is apply | coated to the outer surface 22 of the aluminum tube 2 as said process. Accordingly, a coating film made of a highly radioactive material is formed on the outer surface 22 of the aluminum tube 2.

  Specifically, A6063S-T5 or A-1050 was used as the aluminum material of the aluminum tube 2. Quartz glass was used as the glass material of the glass tube 3. As the heating wire 4, a nickel chrome heating wire was used.

  In addition, the product name “CT-400W”, which is a heat radiation coating agent manufactured by Okitsumo Co., Ltd., was used as the highly radioactive material. This radioactive material has a high emissivity for far infrared rays having a wavelength of 3 to 10 μm. The coating thickness was 20-30 μm. The emissivity of the coating film was 0.85 to 0.95.

  And the electric power shown in Table 1 was supplied to the heating wire 4 under the various dimension set as shown in Table 1, and the surface temperature of the aluminum tube 2 with respect to elapsed time was measured. T1, D1, and L1 are the thickness, outer diameter, and length of the glass tube 3, and T2, D2, and L2 are the thickness, outer diameter, and length of the aluminum tube 2, and H is The distance between the aluminum tube 2 and the umbrella member 20, and W is the width of the umbrella member 20.

(Comparative form 1)
The highly radioactive material was not applied to the aluminum tube 2, and the rest was exactly the same as in the first embodiment. And the surface temperature of the aluminum tube 2 with respect to the elapsed time after electric power supply was measured.

(Result 1)
In the first embodiment, the surface temperature of the aluminum tube 2 after power supply gradually increased immediately after power supply, became stable in about 15 minutes, and the top temperature was 286 ° C. after subtracting room temperature. On the other hand, in Comparative Example 1, the surface temperature of the aluminum tube 2 after power supply increased rapidly immediately after power supply, and the top temperature was 364 ° C. after subtracting room temperature. As can be seen by comparing the two, in Embodiment 1, the surface temperature of the aluminum tube 2 is suppressed to a considerably low temperature as compared with Comparative Embodiment 1, and the safety standard is sufficiently satisfied.

  Moreover, in the first embodiment, since the aluminum tube 2 is provided on the outside, there is no risk of damage even if cold water or ice pieces collide. Therefore, according to the first embodiment, the umbrella member 20 can be omitted.

  The above-described effects of the first embodiment are due to the application of the highly radioactive material to the inner surface 21 and the outer surface 22 of the aluminum tube 2.

(Embodiment 2)
Various dimensions and power supply were set as shown in Table 2, and the others were exactly the same as in the first embodiment. That is, a coating film made of a highly radioactive material is formed on the outer surface 22 of the aluminum tube 2. And the surface temperature of the aluminum tube 2 with respect to the elapsed time after electric power supply was measured.

(Comparative form 2)
The highly radioactive material was not applied to the aluminum tube 2, and the others were exactly the same as in the second embodiment. And the surface temperature of the aluminum tube 2 with respect to the elapsed time after electric power supply was measured.

(Embodiment 3)
Compared with the second embodiment, the thickness T2 of the aluminum tube 2 is increased. That is, it was set to 1.0 mm. Others are the same as those in the second embodiment. That is, a coating film made of a highly radioactive material is formed on the outer surface 22 of the aluminum tube 2. And the surface temperature of the aluminum tube 2 with respect to the elapsed time after electric power supply was measured.

(Comparative form 3)
The highly radioactive material was not applied to the aluminum tube 2, and the other components were exactly the same as in the third embodiment. And the surface temperature of the aluminum tube 2 with respect to the elapsed time after electric power supply was measured.

(Result 2)
In Embodiment 2, the surface temperature of the aluminum tube 2 after power supply gradually increased immediately after power supply and became stable in about 15 minutes, and the top temperature was 262 ° C. after subtracting room temperature. On the other hand, in Comparative Example 2, the surface temperature of the aluminum tube 2 after power supply increased rapidly immediately after power supply, and the top temperature was 309 ° C. after subtracting room temperature. Similarly, the temperature was 246 ° C. in the third embodiment and 291 ° C. in the third comparative example. As can be seen by comparing these, in Embodiments 2 and 3, the surface temperature of the aluminum tube 2 is suppressed to a considerably low temperature as compared with Comparative Examples 2 and 3, and the safety standards are sufficiently satisfied. Further, this suppression effect appears regardless of the thickness of the aluminum tube 2. Note that the surface temperature of the aluminum tube 2 is lower as the aluminum tube 2 is thicker.

  Moreover, in Embodiments 2 and 3, since the aluminum tube 2 is provided on the outside, there is no risk of breakage even if cold water or ice pieces collide. Therefore, according to the second and third embodiments, the umbrella member 20 can be omitted.

  The above-described effects of the second and third embodiments are due to the application of the highly radioactive material to the outer surface 22 of the aluminum tube 2.

(Embodiment 4)
The umbrella member 20 was eliminated, various dimensions and supplied power were set as shown in Table 3, and the rest was exactly the same as in the first embodiment. That is, a coating film made of a highly radioactive material is formed on the outer surface 22 of the aluminum tube 2. As the highly radioactive material, the product name “CT-600” which is a coating agent for heat dissipation manufactured by Okitsumo Co., Ltd. was used. The radioactive material has a high emissivity for far infrared rays having a wavelength of 3 to 10 μm. And the surface temperature of the aluminum tube 2 with respect to the elapsed time after electric power supply was measured.

  Furthermore, using the measurement result of the surface temperature of the aluminum tube 2, the amount of heat transferred from the heating wire 4 through the glass tube 3 to the aluminum tube 2 is calculated, and the temperature rise gradient on the surface of the aluminum tube 2, the temperature gradient ratio, Sought.

(Embodiment 5)
A highly radioactive material was applied to the inner surface 21 and the outer surface 22 of the aluminum tube 2, and the others were exactly the same as in the fourth embodiment. That is, a coating film made of a highly radioactive material is formed on the inner surface 21 and the outer surface 22 of the aluminum tube 2. And the surface temperature of the aluminum tube 2 with respect to the elapsed time after electric power supply was measured. Moreover, the temperature rising gradient on the surface of the aluminum tube 2 and the temperature gradient ratio were determined.

(Comparative form 4)
The highly radioactive material was not applied to the aluminum tube 2, and the others were exactly the same as in the fourth embodiment. And the surface temperature of the aluminum tube 2 with respect to the elapsed time after electric power supply was measured. Moreover, the temperature rising gradient on the surface of the aluminum tube 2 and the temperature gradient ratio were determined.

(Result 3)
In Embodiment 4, the surface temperature of the aluminum tube 2 with respect to the elapsed time after power supply gradually increases immediately after power supply, becomes a stable temperature in about 15 minutes, and the top temperature is 269 ° C. minus room temperature. there were. Moreover, the surface temperature of the glass tube 3 at this time was 724 degreeC. Similarly, in Embodiment 5, it was 287 degreeC and the surface temperature of the glass tube 3 was 516 degreeC. On the other hand, in the comparative form 4, the surface temperature of the aluminum tube 2 with respect to the elapsed time after the power supply is rapidly increased immediately after the power supply, and the top temperature is 293 ° C. after subtracting the room temperature. The surface temperature of 3 was 777 ° C. As can be seen by comparing these, in Embodiments 4 and 5, the surface temperature of the aluminum tube 2 was suppressed to a low temperature as compared with Comparative Example 4. Moreover, the remarkable temperature rise inhibitory effect was seen on the surface of the glass tube 3 which is a heat supply source. This effect can be evaluated from the viewpoint of ensuring high safety in the environment where the flammable refrigerant is used.

  In addition, the temperature increase gradient on the surface of the aluminum tube 2 and the temperature gradient ratio in Embodiments 4 and 5 and Comparative Example 4 were as shown in Table 4.

  As can be seen from Table 4, the heat transfer effect in Embodiments 4 and 5 is superior to that in Comparative Example 4. That is, according to the fourth and fifth embodiments, compared to the fourth comparative embodiment, a large amount of heat can be released to the outside, so that a great defrosting effect can be exhibited.

(Embodiment 6)
In the sixth embodiment, an aluminum tube is used as the metal tube 2. As the above treatment, the inner surface 21 and the outer surface 22 of the aluminum tube 2 are anodized and then colored. Therefore, a colored anodic oxide film is formed on the inner surface 21 and the outer surface 22 of the aluminum tube 2.

Specifically, the anodizing treatment was performed as follows. That is, the aluminum tube 2 was immersed in a 10% sulfuric acid aqueous solution and treated at a temperature of 25 ° C. with a voltage of 15 V and a current density of DC 1.5 Adm ⁻² for 20 minutes.

  Specifically, the coloring treatment was performed as follows. That is, the anodic oxide film obtained by the above anodic oxidation treatment was subjected to direct current electrolysis in an electrolytic solution containing nickel sulfate and boric acid. Thereby, it was colored black.

  Various dimensions and supply power were set as shown in Table 5, and the others were exactly the same as in the first embodiment. And the surface temperature of the aluminum tube 2 with respect to the elapsed time after electric power supply was measured.

(Comparative form 5)
The aluminum tube 2 was not subjected to the above-described coloring treatment, and the others were exactly the same as in the sixth embodiment. And the surface temperature of the aluminum tube 2 with respect to the elapsed time after electric power supply was measured.

(Result 4)
In the sixth embodiment, the surface temperature of the aluminum tube 2 after power supply gradually increases immediately after power supply, reaches a stable temperature in about 15 minutes, and the top temperature is 305 ° C. after subtracting the room temperature. . On the other hand, in Comparative Example 5, the surface temperature of the aluminum tube 2 after power supply increased rapidly from immediately after power supply, and the top temperature was 319 ° C. after subtracting room temperature. As can be seen by comparing the two, in Embodiment 6, the surface temperature of the aluminum tube 2 is suppressed to a low temperature as compared with Comparative Embodiment 5, and the safety standard is sufficiently satisfied.

  Moreover, in the sixth embodiment, since the aluminum tube 2 is provided on the outside, there is no fear of breakage even if cold water or ice pieces collide. Therefore, according to the sixth embodiment, the umbrella member 20 can be omitted.

  The above-described effects of the sixth embodiment are due to the fact that an anodized film that is colored is formed on the inner surface 21 and the outer surface 22 of the aluminum tube 2.

(Embodiment 7)
Embodiment 7 relates to the defrosting system of the present invention. As shown in FIG. 2, the defrosting system includes a defrosting heater 1 and an umbrella member 20 that covers the defrosting heater 1 from above. And in Embodiment 7, while using the same thing as the comparative form 3 as the defrost heater 1, and using the thing of the same dimension setting as the comparative form 2 as the umbrella member 20, the lower surface 201 and the upper surface 202 of the umbrella member 20 are used. In addition, a highly radioactive material having a higher emissivity for far infrared rays than that of the metal constituting the umbrella member 20 is applied. Therefore, a coating film made of a highly radioactive material is formed on the lower surface 201 and the upper surface 202 of the umbrella member 20.

  Specifically, the umbrella member 20 is made of an aluminum material (A6063S-T5 or A-1050). As the highly radioactive material, the product name “CT-400W”, which is a heat dissipation coating agent manufactured by Okitsumo Co., Ltd., was used.

  And the same electric power as the comparative form 2 was supplied, and the surface temperature of the aluminum tube 2 with respect to the elapsed time after that was measured.

(Comparative form 6)
The umbrella member 20 was not coated with a highly radioactive material, and the others were exactly the same as in the seventh embodiment. And the surface temperature of the aluminum tube 2 with respect to the elapsed time after electric power supply was measured.

(Result 5)
In the seventh embodiment, the surface temperature of the aluminum tube 2 with respect to the elapsed time after the power supply gradually increases immediately after the power supply, becomes a stable temperature in about 15 minutes, and the top temperature is 283 ° C. after subtracting the room temperature. Met. On the other hand, in Comparative Example 6, the surface temperature of the aluminum tube 2 after power supply increased rapidly immediately after power supply, and the top temperature was 291 ° C. after subtracting room temperature. As can be seen by comparing the two, in Embodiment 7, the surface temperature of the aluminum tube 2 is suppressed to a low temperature as compared with Comparative Embodiment 6. Therefore, Embodiment 7 can fully satisfy safety standards.

  The above-described effect of the seventh embodiment is due to the application of the highly radioactive material to the upper surface 201 and the lower surface 202 of the umbrella member 20.

(Another embodiment)
(1) In the first to fifth embodiments, the case where the coating film made of the highly radioactive material is formed on both the inner surface 21 and the outer surface 22 and the case where the coating film is formed only on the outer surface 22 are described. Moreover, the said coating film may be formed only in the inner surface 21, and even in that case, the surface temperature of the aluminum tube 2 can be suppressed to low temperature similarly to Embodiments 1-5, and a safety standard can be satisfy | filled.

(2) In the sixth embodiment, the case where the anodic oxide film subjected to the color treatment is formed on both the inner surface 21 and the outer surface 22 is described. In this case, the surface temperature of the aluminum tube 2 can be suppressed to a low temperature, and the safety standard can be satisfied.

(3) In the first to fifth embodiments, the case where an aluminum tube is used as the metal tube 2 is described. However, a copper tube, an iron tube, a titanium tube, or the like may be used. Similarly, the surface temperature of the metal tube 2 can be suppressed to a low temperature, and safety standards can be satisfied.

(4) In Embodiment 7, the case where a coating film made of a highly radioactive material is formed on both the lower surface 201 and the upper surface 202 is described. However, the coating film is formed only on the lower surface 201 or on the upper surface. It may be formed only on the surface 202, and even in that case, the surface temperature of the defrost heater 1 can be suppressed to a low temperature as in the seventh embodiment, and the safety standard can be satisfied.

  INDUSTRIAL APPLICATION Since the defrosting effect by a defrosting heater and a defrosting system can be improved with a simple structure, this invention has a large industrial utility value.

It is a partial section front view of the defrost heater of the present invention. It is a longitudinal cross-sectional view of the defrost system of this invention.

Explanation of symbols

1 Defrost heater 2 Metal tube (aluminum tube)
21 inner surface 22 outer surface 3 glass tube 4 heating wire 10 cooler 20 umbrella member 201 lower surface 202 upper surface

Claims (6)

In the defrost heater for the refrigerator cooler,
A metal tube, a glass tube inserted through the metal tube, and a heating wire inserted through the glass tube,
At least one of the inner surface and the outer surface of a metal tube is processed so that the emissivity regarding a far infrared ray may become higher than the metal which is a constituent material of a metal tube, The defrost heater characterized by the above-mentioned.   The coating film which consists of a highly radioactive material with a high emissivity regarding far-infrared rays compared with the metal which is a constituent material of a metal tube is formed in at least one of the inner surface and outer surface of a metal tube. Defrost heater of description.   The defrost heater according to claim 2, wherein the highly radioactive material has a high emissivity for far infrared rays having a wavelength of 3 to 10 µm.   The defrost heater according to claim 1, wherein the metal tube is an aluminum tube, and a colored anodized film is formed on at least one of the inner surface and the outer surface of the metal tube. In the defrosting system for the refrigerator cooler,
A defrost heater, and an umbrella member that covers the defrost heater from above,
A defrosting system characterized in that at least one of the lower surface and the upper surface of the umbrella member is processed so that the emissivity with respect to far-infrared rays is higher than that of a metal that is a constituent material of the umbrella member. The defrosting system according to claim 5, wherein the defrosting heater is any one of claims 1 to 4.

Images