JPH09303940A - Refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit the defrosting of a heat exchanger as well as the removal of smell constituents existing in a refrigerator. SOLUTION: Smell in a refrigerating chamber 7 is sucked by a fan 1 through an air suction port 9 and smell is adsorbed by a catalyst layer 3 and/or a catalyst layer 4, which include a zeolite, while cooling is effected by a heat exchanger 6, in usual. When the heat exchanger 6 is frosted and a cooling capacity is dropped, a catalyst is activated by exciting a heat generating body 2 to decompose and eliminate the smell adsorbed by the catalyst coating layer 3 and/or the catalyst coating layer 4. At the same time, frost, adhered to the heat exchanger 6, is removed by the ascending of heated air. Further, water drops will not hit a honeycomb type ceramic heat generating body 2 by a water drop protecting plate 5. After removing the frost, adhered to the heat exchanger 6, and the adsorbing capacity of the catalyst layer 3 and/or the catalyst layer 4 is restored again, the excitation is stopped and the adsorption of the small constituents is effected again. The adsorption of smell and the decomposition of the smell are repeated alternately in such a manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator having a deodorizing function capable of defrosting a heat exchanger and removing odorous components existing in a refrigerator for a long period of time.

[0002]

2. Description of the Related Art Generally, various odors are present in a refrigerator. These malodorous components are mainly mercaptans, amines, etc., and are derived from foods.

Conventionally, as a means for deodorizing the odor in such a refrigerator, a means of arranging activated carbon in the refrigerator and adsorbing an odor component gas to deodorize has been mainly used. Further, recently, a means has been used in which a device having an ozone generating function is arranged in a room to oxidize and decompose a malodorous component by ozone gas.

Further, Japanese Patent Laid-Open No. 4-281177 describes a deodorizing constitution by forming a catalyst coating layer on a quartz tube heater for defrosting and / or a water drop protection plate.

[0005]

Since the conventional adsorption means using activated carbon has a limited adsorption capacity,
It was necessary to change the activated carbon regularly. There is also a problem that moisture in the atmosphere hinders gas adsorption.
On the other hand, in the means for decomposing odors by ozone, a special device is required to control the generation of ozone at the optimum concentration for decomposition and deodorization, and there are components that are difficult to decompose.
There was a problem such as the life of the ozone generator. Further, in the deodorizing configuration by forming the catalyst coating layer on the quartz tube heater for defrosting and / or the water drop protection plate, a part of the odorous components contained in the circulating air between the refrigerating compartment and the heat exchanger is brought into contact with the catalyst coating layer. Since it passes without passing through, it requires a large amount of air circulation to achieve the target odor reduction amount.

The present invention solves the above problems and provides a refrigerator capable of removing frost adhering to a heat exchanger with a simple structure and removing odors and harmful gases in a refrigerator with high efficiency and long life. The purpose is to do.

[0007]

To achieve the above object, the present invention provides at least a refrigerating chamber, a fan, a heat exchanger, and a honeycomb-shaped ceramic heating element provided substantially below the heat exchanger. A water droplet protection member provided in proximity to and above the heat generating element, and substantially the entire amount of air flow generated by the fan circulating in the refrigerating chamber and the heat exchanger passes through the honeycomb ceramic heat generating element. Is configured as
In addition, the heating element has a catalyst coating layer.

The honeycomb-shaped ceramic heating element comprises a honeycomb-shaped ceramic resistor and a catalyst coating layer provided on the surface of the honeycomb-shaped ceramic resistor.

The ceramic resistor used in the honeycomb-shaped ceramic heating element may be SiC or PTC ceramic. Of these, PTC ceramics are controlled by the Curie temperature that is unique to the material, so if a heater cooling means such as air blowing is not used, almost no current flows through the heater, and the amount of heat that can be output from the heater is extremely small. A honeycomb resistor made of SiC having NTC characteristics is desirable because the amount of heat output from the heating element can be changed by changing the applied power regardless of the presence of cooling means.

Aluminum is used as the electrode material of the present invention,
Nickel, copper, brass, silver-Pt, silver-Pd, and Pt can be used, and a plurality of electrode materials among them may be used together depending on the purpose. Moreover, various methods can be used as the electrode forming method. For example, the electrode material paste may be applied and then baked, or may be directly applied by metal sputtering, vapor deposition, or thermal spraying. Of these, it is preferable to form the electrode by thermal spraying because the contact resistance between the electrode and the ceramic resistor can be minimized.

Further, in the present invention, it is desirable that the conductive electrode is formed so as to protrude to both side surfaces of the wall surface on which the electrode is formed. This is because it is possible to prevent a temperature decrease on the side surface of the honeycomb heating element and realize a uniform heat generation temperature distribution. It is desirable that the conductive electrode portion formed on both side surfaces of the electrode forming wall surface is 1 mm or more and 5 mm or less from the end surface. This is because a very uniform temperature distribution of the honeycomb heating element can be obtained in the range of the protruding electrode.

The catalyst coating layer formed on the surface of the ceramic resistor of the present invention preferably contains at least activated alumina, zeolite and a platinum group metal, and these are preferably combined with an inorganic binder for use. By using activated alumina, zeolite and platinum group metal at the same time, it is possible to obtain a synergistic effect of improving the adsorption characteristics for acidic odor components as compared with the case of using activated alumina or zeolite alone.

Where a metal resistor is used, metal corrosion proceeds due to the catalytic oxidation of the coated catalyst coating layer.
This does not normally occur with the ceramic resistor of the present invention. However, at high temperatures, the oxidation reaction of the ceramic resistor by the catalyst coating layer begins to proceed and the resistance value changes, so the reaction between the catalyst coating layer and the honeycomb heating element is prevented between the catalyst coating layer and the honeycomb heating element. It is desirable to provide an oxidation reaction preventive layer. Further, since the conductive electrode is made of metal, it is not preferable to directly contact with the catalyst coating layer because of the problem of corrosion. In the present invention, the catalyst coating layer is formed so as to be separated from the conductive electrode, or when the catalyst coating layer is provided even on the conductive electrode, an oxidation reaction preventive layer is provided between the catalyst coating layer and the conductive electrode. Is desirable.

Materials used for the oxidation reaction preventive layer include glass, silica, alumina, titania, titanocarbosilane, and perhydropolysilazane, and one or more of these may be used in a single layer or multiple layers. Among these materials, silica and titanocarbosilane are excellent and desirable from the viewpoint of adhesion between the oxidation reaction preventing layer and the ceramic resistor and the catalyst coating layer.

The alumina used in the catalyst coating layer of the present invention is
It is a metastable alumina such as β-, γ-, δ-, θ-, η-, ρ-, and χ-alumina. Further, by supporting a promoter such as a rare earth oxide on the surface of alumina, further increase in activity can be expected.

Further, as the inorganic binder, silica is the most excellent as a binder and forms a film which is not easily peeled off from the resistor when the catalyst coating layer is formed on the surface of the ceramic resistor without deteriorating the catalytic properties. be able to.

The silica content of the present invention is preferably 10 to 40 wt% in the catalyst coating layer. When the content of silica exceeds 40 wt%, cracks are likely to be formed in the catalyst coating layer and the adhesion is likely to be deteriorated. On the other hand, if it is less than 10 wt%, a sufficient effect of improving adhesion of silica cannot be obtained.

As the noble metal used in the present invention, Pt, P
There are d, Rh, and Ru. Of these, Pt is preferable because it has an excellent odor adsorption capacity as compared with other noble metals, and it is more preferable to use both Pt and Pd because of the oxidative decomposition ability of odor. This is because the oxidative decomposition power of Pt or Pd is higher than that of Rh or Ir, and the use of both Pt and Pd further enhances the activity. In addition, Ru
When used at high temperatures, Ru is volatilized and becomes a harmful substance.

It is desirable that the catalyst coating layer of the present invention contains copper oxide. This is because coexistence of copper oxide with the platinum group metal in the catalyst coating layer can prevent deterioration of the odor adsorption performance of the platinum group metal at high temperatures. Especially copper oxide,
It is most effective to use it in the state of activated alumina carrying a noble metal and copper oxide.

It is desirable that the zeolite include at least a pentasil-type zeolite. This is because the adsorption performance of odors that are difficult to adsorb such as aldehyde and dimethyl disulfide can be improved. Of the pentasil-type zeolites, H-ZSM5 and Na-ZSM5 are particularly preferable because they have a particularly high adsorption performance for the hardly adsorbed odor.

Further, it is desirable that the zeolite of the present invention contains at least mordenite or Y-type zeolite. This is because the adsorption capacity for the odor of amines in the catalyst coating layer can be improved by including mordenite or Y-type zeolite.

It is desirable that the zeolite contains at least copper ion exchanged zeolite or iron ion exchanged zeolite. This is because when the catalytic oxidative decomposition of odors of the adsorbed amines is carried out, the catalyst coating layer contains copper ion-exchanged zeolite or iron ion-exchanged zeolite to suppress the production of nitrogen oxides and to obtain a high level of safe conversion to nitrogen. Because it will be done.

It is desirable to include cerium oxide in the catalyst coating layer of the present invention. By including cerium oxide in the catalyst coating layer, the catalytic oxidative decomposition activity for hydrocarbon compounds can be improved.

The cerium oxide content of the present invention is preferably 2 to 15 wt% in the catalyst coating layer. When the content of cerium oxide exceeds 15 wt%, the oxidative decomposition characteristics of the catalyst begin to decrease, and when the content is less than 2 wt%, a sufficient effect of adding cerium oxide cannot be obtained.

It is desirable to include barium oxide in the catalyst coating layer of the present invention. By including barium oxide in the catalyst coating layer, the oxidative decomposition characteristics of the catalyst can be improved.

The content of barium oxide of the present invention is preferably 0.5 to 5 wt% in the catalyst coating layer. If the content of barium oxide exceeds 5 wt%, the adhesion of the catalyst coating layer will deteriorate, and if it is less than 0.5 wt%, a sufficient effect of adding barium oxide cannot be obtained.

Similar effect can be obtained by using barium carbonate instead of barium oxide of the present invention. The desirable addition amount of barium carbonate is 0.5 to 5 wt% in terms of barium oxide amount.

Various methods can be used for the catalyst coating layer forming method of the present invention. For example, there are spray coating, dip coating, electrostatic coating method and the like.

Next, the operation of the present invention will be described.

According to the present invention having the above-mentioned structure, normally, the air in the chamber is circulated from the bottom to the top of the honeycomb ceramic heating element by a fan, and the odor component in the chamber is coated with the honeycomb ceramic heating element. The catalyst layer containing as an adsorbent adsorbs and deodorizes, and the inside of the refrigerator is cooled by a heat exchanger. When the heat exchanger is frosted and the cooling capacity drops to a certain level, the fan is stopped and the honeycomb ceramic heating element is energized so that the catalyst substance in the catalyst coating layer coated on the honeycomb ceramic heating element Is activated, and the odorous components adsorbed in the catalyst coating layer are oxidized and decomposed by a chemical action to make them odorless. At the same time, the air heated by the honeycomb ceramic heating element rises to remove the frost adhering to the heat exchanger. The heated frost drops as water drops, but the water drop protection plate prevents the drops from falling onto the honeycomb ceramic heating element.

After the frost adhering to the heat exchanger is removed by the heating from the honeycomb ceramic heating element and the adsorption capacity of the catalyst coating layer is restored again, the electricity supply to the honeycomb ceramic heating element is stopped and the catalyst is reactivated. Adsorption of odorous components by the coating layer.

As described above, by alternately repeating the adsorption of odor by the catalyst coating layer and the oxidative decomposition of the odor component by energizing the honeycomb ceramic heating element, it is possible to remove the malodor in the chamber for a long period of time.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG. In Figure 1, 1 is a fan,
Reference numeral 2 denotes a honeycomb-shaped ceramic heating element, 3 denotes a catalyst layer covering the honeycomb-shaped ceramic heating element 2, 4 denotes a water droplet protection plate, 5
Is a heat exchanger, 6 is a freezing room, 7 is a refrigerating room, 8 is an opening / closing door, 9
Is an air inlet, and 10 is an air outlet.

When a switch (not shown) of the refrigerator is turned on, cooling of the inside of the refrigerator starts, and the air in the refrigerating chamber 7 sucked from the air suction port 9 by the activated fan 1 has a honeycomb shape as shown by an arrow. Ceramic heating element 2 and water drop protection plate 4
Sent to

Here, since the honeycomb ceramic heating element 2 is not energized, the honeycomb ceramic heating element 2 containing Cu ion-exchanged A-type zeolite having a high adsorption ability at a low temperature and the catalyst coating layer 3 of the water droplet protection plate 4 are used. Odor components in the air are adsorbed and removed. The purified air becomes cold air by the heat exchanger 5 and is sent again into the refrigerating chamber 7, and this air circulation is repeated.

When the heat exchanger 5 is frosted and the cooling capacity drops to a certain level, the fan 1 is stopped by a signal from a timer or a temperature sensor (not shown),
The honeycomb ceramic heating element 2 is energized and the heat exchanger 5
The frost attached to is removed. At the same time, the honeycomb-shaped ceramic heating element 2 heats the catalyst coating layer 3 coated on the surface,
The catalyst metal is activated, and the odorous components adsorbed on the catalyst coating layer 3 are oxidized and decomposed to regenerate the catalyst coating layer 3.

The water droplet protection plate 4 is provided to prevent water droplets generated by melting of frost when the heat exchanger 5 is defrosted from directly falling on the surface of the honeycomb ceramic heating element 2. After the frost adhering to the heat exchanger 5 is removed and the adsorption capacity of the catalyst coating layer 3 is restored again, the energization of the honeycomb ceramic heating element 2 is stopped and the odorous components are adsorbed by the catalyst layer 3 again. .

As described above, according to the refrigerator of the embodiment of the present invention, by alternately repeating the adsorption of the odor by the catalyst coating layer 3 and the oxidative decomposition of the adsorbed odor component during the operation of the refrigerator, a long period of time can be obtained. There is an effect that it is possible to remove the foul odor and defrost inside the refrigerator.

Another embodiment of the present invention is shown in FIG. In FIG. 2, 11 is a fan A, 12 is a honeycomb ceramic heating element, 13 is a catalyst layer coated on the honeycomb ceramic heating element 12, 14 is a water droplet protection plate, 15 is a heat exchanger, 16 is a freezing chamber, and 17 is Refrigerator, 18 is an opening / closing door, 19 is an air inlet, 20 is an air outlet, 21 is a fan B, 22 is a flow control valve A, and 23 is a flow control valve B.

When a switch (not shown) of the refrigerator is turned on, cooling of the inside of the refrigerator starts, and the air in the refrigerating chamber 17 sucked from the air suction port 19 by the activated fan 11 has a honeycomb shape as shown by an arrow. It is sent to the ceramic heating element 12 and the water drop protection plate 14.

Here, the honeycomb-shaped ceramic heating element 12
Is not energized, the odorous component in the air is adsorbed and removed by the catalyst coating layer 13 of the honeycomb-shaped ceramic heating element 12 having a high adsorption ability at a low temperature. The purified air becomes cold air by the heat exchanger 15 and is sent again from the freezing compartment 16 into the refrigerating compartment 17, and this air circulation is repeated.

When the heat exchanger 15 is frosted and the cooling capacity drops to a certain level, the fan A11 is stopped by a signal from a timer or a temperature sensor (not shown), and the honeycomb ceramic heating element 12 is The frost attached to the heat exchanger 15 is removed by being energized. At the same time, the honeycomb-shaped ceramic heating element 12 heats the catalyst coating layer 13 coated on the surface to activate the catalyst metal, and the catalyst coating layer 13 is activated.
The catalyst coating layer 13 is regenerated by oxidatively decomposing the odorous components adsorbed on the. After the frost adhering to the heat exchanger 15 is removed and the adsorption ability of the catalyst coating layer 13 is restored again, the energization of the honeycomb ceramic heating element 12 is stopped and the odorous component is adsorbed by the catalyst layer 13 again. .

In the normal refrigerating operation state, the flow rate control valve A22 is used to control the flow of cold air from the freezing compartment 16 to the refrigerating compartment 17 by a signal such as an appropriate temperature sensor or timer. It is possible to achieve too cold and energy saving. Further, by using the fan B21 to directly supply the cool air of the heat exchanger 15 to the refrigerating compartment 17, it is possible to prevent the opening / closing door 18 from being frequently opened and closed during the summer and to prevent the refrigerating performance of the refrigerating compartment 17 from being degraded. Further, if the flow control valves A and B of 22 and 23 are used together, not only the optimum refrigerating performance can be obtained, but also the deodorizing performance can be improved. For example, the flow control valve A from the freezer compartment 16 to the refrigerating compartment 17 is closed, the flow control valve B is opened, and the temperature of the heat exchanger 15 is adjusted to the refrigerating compartment 17.
By increasing the temperature so that the temperature does not drop too much and circulating the cool air without passing through the freezer compartment 16, energy saving and deodorizing performance can be improved. Such cold air circulation can be performed even during defrosting.

Usually, the odor in the refrigerator is mainly generated from the food stored in the refrigerator compartment. This is because the vapor pressure of the odorous components in the food is very low due to the low temperature in the freezing compartment. Since the odor is constantly generated in the refrigerating chamber 17, the honeycomb-shaped ceramic heating element 12,
By efficiently circulating the cold air via the heat exchanger 15 and the flow control valve B, it is possible to prevent odors from accumulating in the refrigerating chamber 17 and preventing the odor transfer between foods and adhesion to the inner wall of the refrigerator, thereby improving the deodorizing performance. Be improved.

The water drop protection plate 14 is provided to prevent water drops generated by melting of frost when the heat exchanger 15 is defrosted from directly falling on the surface of the honeycomb ceramic heating element 12.

As described above, according to the refrigerator of the embodiment of the present invention, the adsorption of the odor by the catalyst coating layer 13 and the oxidative decomposition of the adsorbed odor component are alternately repeated during the operation of the refrigerator, so that the refrigerator can be used for a long period of time. There is an effect that it is possible to remove the foul odor and defrost inside the refrigerator.

A more specific embodiment of the honeycomb-shaped ceramic heating element of the present invention will be described. An embodiment of the honeycomb-shaped ceramic heating element of the present invention is shown in the drawings. In FIG. 3, 24 is a SiC honeycomb as a ceramic honeycomb resistor, 25 is a conductive electrode, 26 is a catalyst coating layer, 27 is an oxidation reaction prevention layer, and 28 is an air flow.

When the conductive electrode 25 is energized, the SiC honeycomb 2
4 heats up and stabilizes at a temperature corresponding to the applied power. Even if the amount of applied power is increased to raise the temperature of the SiC honeycomb 24, the resistance change is suppressed because the oxidation reaction prevention layer 27 is provided on the surface of the SiC honeycomb 24. When the SiC honeycomb 24 is not energized, the odor components in the room are usually separated by the catalyst coating layer 26.
It is adsorbed and deodorized by the zeolite and precious metal contained therein. Then, when the SiC honeycomb 24 is energized before the odor component is adsorbed to the limit of the odor adsorption capacity of the catalyst coating layer 26, heat is transferred from the SiC honeycomb 24 to the catalyst coating layer 26 installed so as to cover the outer periphery. The heating is performed efficiently, and the catalyst can be heated to its activation temperature in a short time. The odorous components adsorbed on the catalyst coating layer 26 are oxidized and purified by the activated catalyst.

Furthermore, since the heating element also heats the air in the vicinity thereof, an air flow 28 is generated as convection near the heating element. When the air stream 28 comes into contact with the catalyst coating layer 26 heated to the activation temperature by heating or diffuses into the coating layer, odors and harmful components contained in the air stream 28, such as carbon monoxide ( (Hereinafter referred to as CO) and ammonia are purified by the catalytic action.

[0050]

EXAMPLES Next, detailed examples of the present invention will be described. Example 1 A SiC honeycomb resistor having a length of 60 mm, a width of 150 mm, and a thickness of 10 mm was used, and a copper electrode was formed as a conductive electrode by thermal spraying with the configuration shown in FIG. Next, using silica sol, the thickness of the resistor is about 60 μm except for the copper electrode part.
The resistor A of the present invention having the siliceous oxidation preventing layer and the resistor B having no oxidation preventing layer were prepared.

400 g of γ-alumina and an inorganic binder
As colloidal alumina 1000 with an alumina content of 10 wt%
g, copper ion exchanged A-type zeolite 500 g, water 15
A slurry A was prepared by adding 00 g, 30 g of chloroplatinic acid as Pt, 30 g of palladium chloride as Pd and 15 g and an appropriate amount of hydrochloric acid, and thoroughly mixing with a ball mill.
The heating element A and the heating element B were prepared by applying the slurry A to the resistor A and the resistor B, respectively, to form a catalyst coating layer. The catalyst coating amounts were both 5.0 g.

Further, a nichrome wire as an electric resistor, and an insulator having an outer diameter of 10 mm, an inner diameter of 9 mm and a length of 15 c.
One set of 5 m quartz tubes, length 100 mm, width 100 mm,
Honeycomb SU with a thickness of 10 mm and a cell density of 100 cells / in ²
Comparative heating elements A and B in which 5.0 g of the catalyst coating layer was formed on each of the S430 resistors using the slurry A were prepared.

A mercaptan oxidation purification test and a durability test were performed on these heating elements. In the methyl mercaptan oxidation purification test, the heating element is placed in a cubic resin container made of fluorine resin of 0.5 m ³ and the center of the heating element is blown by blowing air inside the container at a flow rate of 50 l / min to the heating element. It was carried out by injecting methyl mercaptan into the container so that the concentration became 10 ppm to the place where electricity was applied so that the temperature of the outer surface of was about 450 ° C., and checking the change in the concentration of methyl mercaptan in the container after 20 minutes of electricity application. The change with time of the methyl mercaptan concentration was examined by gas chromatography. The endurance test is conducted by energizing the temperature of the outer surface of the center of the heating element to 450 ° C. in 40 ° C. air, maintaining the temperature for 10 minutes, stopping energizing, cooling for 20 minutes, and then energizing again. After repeating the energization cycle of 1000 times, the presence or absence of abnormality in the catalyst coating layer was examined. The results are shown in (Table 1).

[0054]

[Table 1]

As is clear from Table 1, the heating elements A and B of the present invention have a mercaptan oxidation purification property and a comparative heating element A which is a quartz tube heating element and a comparative heating element B which is a metal heating element. It had excellent durability. 90% relative humidity
In the same test as the above durability test in air, no abnormalities were found in the heating elements A and B and the comparative heating element A, whereas the catalyst coating layer peeled off on the comparative heating element B which is a metal heating element. Not only that, remarkable rusting was observed.

Next, the heating elements A and B are heated to 50 l / m by a fan.
While blowing the air in the container at a flow rate of in to the heating element, it was placed in a closed box with a volume of 0.5 m ³ whose inner wall surface was covered with fluorine resin, and the air-diluted methyl mercaptan at a concentration of 10 ppm was not energized. And the amount of residual methyl mercaptan was measured 30 minutes after the heating element was put in and the amount of residual methyl mercaptan was measured. The amount of residual methyl mercaptan is 7% for both
The deodorization was promptly performed. <Example 2> The heating element A and the heating element B prepared in Example 1 were energized to apply a power load such that the temperature of the heating element reached 500 ° C, and the change in resistance after 1000 hours of continuous energization was measured. The results are shown in (Table 2).

[0057]

[Table 2]

As is clear from (Table 2), the resistance value of the heating element A having the antioxidant layer did not change, but the resistance value of the heating element B having no oxidation layer was found to change. From this result, when forming the catalyst coating layer, it is desirable to provide an oxidation reaction prevention layer between the catalyst coating layer and the honeycomb heating element to prevent the reaction between the catalyst coating layer and the honeycomb heating element.

When the heating element B is energized and the heating element temperature is 300
No change in resistance value is observed after 1000 hours of continuous energization under a power load of 0 ° C., and the oxidation reaction preventive layer is not necessary at a relatively low temperature. <Example 3> A heating element having the same structure as that of the heating element A was prepared by variously changing the material of the conductive electrode as shown in (Table 3). The initial resistance value of each heating element was 5.0 Ω. Next, each heating element was energized and an electric load was applied so that the temperature of the heating element reached 700 ° C., and the resistance value after 1000 hours of continuous energization was measured. The results are shown in (Table 3).

[0060]

[Table 3]

As is clear from Table 3, nickel,
Copper, brass, silver-Pt, silver-Pd, and Pt are desirable because they have little resistance change. In particular, silver-Pd / brass and silver-Pt / brass do not change in resistance value, and it is desirable that the conductive electrode has a two-layer structure. <Example 4> A heating element having the same structure as that of the heating element A was prepared by changing the material of the antioxidant layer as shown in Table 4 below. A thermal shock test was performed on these heating elements to examine the adhesion of the catalyst coating layer. In the thermal shock test, the heating element is energized, the temperature of the catalyst coating layer is set at every 25 ° C., the temperature is maintained for 10 minutes, and then the temperature is dropped in room temperature water to check whether the catalyst coating layer is peeled off. The maximum temperature that does not cause the heat resistance was defined as the thermal shock resistance temperature. The results are shown in (Table 4).

[0062]

[Table 4]

As is clear from Table 4, silica and titanocarbosilane are desirable because of their high thermal shock resistance temperature. Further, when a two-layered antioxidant layer having silica as the upper layer and titanocarbosilane as the lower layer is provided, the thermal shock resistance temperature is 750.
The temperature was ℃ and good results were obtained. Titanocarbosilane has the most excellent moisture resistance among the antioxidant layer materials shown in (Table 4). Due to such two layers, the antioxidant layer is excellent in both moisture resistance and adhesion of the catalyst coating layer. Is obtained and desirable. <Example 5> A heating element having the same configuration as that of the heating element A was prepared by variously changing the method of forming the conductive electrode as shown in (Table 5). The initial resistance value of each heating element is shown in (Table 5).

[0064]

[Table 5]

As is clear from (Table 5), the spraying method is preferable as the method for forming the conductive electrode because the value having the lowest resistance value can be obtained. <Example 6> In the slurry A of Example 1, the slurry 1 containing no platinum group salt, the platinum group salt containing no γ, and γ
-Similar to the heating element A, using a slurry 2 in which alumina is all copper ion-exchanged A-type zeolite and a slurry 3 which does not contain a platinum group salt and in which copper ion-exchanged A-type zeolite is all γ-alumina. Heating elements C, D, and E having 5.0 g of each catalyst coating layer were prepared.

An acetic acid adsorption test was performed on the heating elements C, D, and E, and the acetic acid residual rate 60 minutes after the start of measurement was compared with that of the heating element A. In the acetic acid adsorption test, the heating element was placed in a cubic fluorine resin container of 0.5 m ³ and the heating element was not heated, while the air inside the container at a flow rate of 50 l / min was blown to the heating element. Then, acetic acid was injected into the container so that the concentration became 40 ppm, and the change of the concentration with time was examined. The change with time of the acetic acid concentration was examined by gas chromatography.

The results are shown in (Table 6). As is clear from (Table 6), the heating element A of the present invention was superior to the heating elements C, D and E in the adsorption characteristics of acetic acid which is an acidic odor component. Therefore, by using activated alumina, zeolite, and platinum group metal at the same time, it is possible to obtain a synergistic effect of improving the adsorption characteristics for acidic odor components, compared with the case of using activated alumina or zeolite alone.

[0068]

[Table 6]

Example 7 400 g of γ-alumina, 1000 g of colloidal alumina having an alumina content of 10 wt% as an inorganic binder, and copper ion-exchanged A-type zeolite 450
g, copper oxide 50 g, water 1500 g, chloroplatinic acid as Pt
As a slurry 4 was prepared by adding 30 g, palladium chloride as Pd and 15 g and an appropriate amount of hydrochloric acid, and thoroughly mixing using a ball mill.

A slurry 5 having the same composition as that of the slurry 4 was prepared in the same manner as the slurry 4 by using an aqueous solution of chloroplatinic acid, palladium chloride, and alumina in which Pt, Pd, and CuO were previously supported using copper nitrate and alumina. Further, the prepared slurry 4 was used to prepare a slurry 6 in which all the noble metal content was copper oxide.

Example 1 using these slurries 4, 5 and 6
Heating elements F, G, and H were prepared from the same method and the same ceramic resistor.

In order to compare the heating elements F, G and H with the heating element A, a methyl mercaptan purification test was conducted. In the methyl mercaptan purification test, the heating element was placed in a cubic container made of fluorine resin of 0.5 m ³ and 50 l /
While blowing air in the container at a flow rate of min to the heating element, methyl mercaptan was injected into the container so that the concentration became 8 ppm, and 90 minutes later, the concentration of methyl mercaptan was examined. The heating element was not heated and the measurement was carried out by gas chromatography. Further, after the adsorption test, the heating element was heated in air at 700 ° C. for 20 hours, cooled to room temperature, and again subjected to a methylmercaptan purification test to examine the heat resistance of the deodorant. The results are shown in (Table 7).

[0073]

[Table 7]

As is clear from (Table 7), the heating element to which only noble metal or copper oxide is added is 700 ° C.
However, the heat resistance of the deodorant can be improved by adding both copper oxide and a noble metal. Further, it is desirable that both copper oxide and a noble metal are supported on alumina in advance and the heat resistance is further improved. <Example 8> In the slurry-A of Example 1, a slurry in which the copper ion-exchanged zeolite was all replaced with various zeolites shown in (Table 7) was prepared to prepare a heating element having the same configuration as the heating element A. did.

Further, in the slurry A of Example 1, slurry having the same total amount of noble metal components but Pt only, Pd only, Rh only, and Ru only was prepared, and a heating element having the same structure as the heating element A was prepared. It was created.

The adsorbing properties of trimethylamine and acetaldehyde having a hardly adsorbed odor were tested on these heating elements. In the odor adsorption test, the heating element was placed in a cubic fluorine resin container of 0.5 m ³ and the heating element was not heated, but the air inside the container at a flow rate of 50 l / min was blown to the heating element. , Trimethylamine, and acetaldehyde were injected into the container so that the concentration was 10 ppm, and the odor residual rate in the container after 60 minutes of adsorption was evaluated. The odor concentration in the container was examined by gas chromatography. The results are shown in (Table 8) and (Table 9).

[0077]

[Table 8]

As is clear from Table 8, pentasil type zeolite, Y type zeolite, mordenite, Cu-
The A-type zeolite was excellent in the adsorption property of both acetaldehyde and trimethylamine. Further, among the zeolites, pentasil-type zeolite ZSM5 and silicalite are preferable due to their acetaldehyde adsorption property, and particularly H
-ZSM5 and Na-ZSM5 are the most desirable and desirable. Further, Y-type zeolite and mordenite are excellent in the adsorption property of trimethylamine, and are desirable. Zeolites are selected according to the target odor to be deodorized. Further, it is desirable that a mixture of pentasil-type zeolite and Y-type zeolite or mordenite is used because it is possible to obtain one having excellent adsorption properties for both acetaldehyde and trimethylamine.

[0079]

[Table 9]

As is clear from Table 9, Pt-Pd and Pt among the noble metals have excellent acetaldehyde adsorption properties, and it is desirable that Pt is contained as the noble metal component. <Example 9> The oxidative decomposition performance of trimethylamine was measured using heating elements having different zeolite species shown in Table 8. In the measurement, a helium dilution gas containing 1000 ppm of trimethylamine and 21% of oxygen was passed through each heating element heated at 300 ° C. at SV 5000 h ⁻¹ , and the nitrogenation rate at the time of oxidative decomposition of trimethylamine by the heating element was evaluated. The results are shown in (Table 10).

[0081]

[Table 10]

As is clear from (Table 10), copper ion-exchanged zeolite and iron ion-exchanged zeolite are desirable because of their high nitrogenation rate. The concentration of trimethylamine contained in the air as an odor is usually low, and it does not matter if nitrogen oxides are produced, but in an environment where the amount of produced nitrogen oxides is large, it is preferable to use copper ion exchanged zeolite or iron ion exchanged zeolite. Further, the copper ion-exchanged zeolite and the iron ion-exchanged zeolite are also excellent in the adsorption property of acetaldehyde and trimethylamine as shown in (Table 8).

[0083]

As is apparent from the above description,
According to the present invention, the adsorption of the odorous component by the catalyst coating layer and the oxidative decomposition of the adsorbed odorous component are alternately repeated during the operation of the refrigerator, so that the refrigerator capable of exhibiting the deodorizing ability for a long period of time is provided. Can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a typical embodiment of the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a diagram illustrating a honeycomb-shaped ceramic heating element according to an embodiment of the present invention.

[Explanation of symbols]

 1 Fan 2 Honeycomb Ceramic Heating Element 3 Catalyst Layer Covering Honeycomb Ceramic Heating Element 4 Water Drop Protection Plate 5 Heat Exchanger 6 Freezing Room 7 Refrigerating Room 8 Opening / Closing Door 9 Air Inlet 10 Air Exhaust 11 Fan A 12 Honeycomb -Shaped ceramic heating element 13 Catalyst layer covering honeycomb-shaped ceramic heating element 2 Water drop protection plate 15 Heat exchanger 16 Freezing room 17 Refrigerating room 18 Opening door 19 Air intake port 20 Air discharge port 21 Fan B 22 Flow control valve A 23 Flow control valve B 24 SiC honeycomb 25 Conductive electrode 26 Catalyst coating layer 27 Oxidation reaction prevention layer 28 Air flow

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kimoyasu Honda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kunio Kimura, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (17)

[Claims] 1. A refrigerating chamber, a fan, a heat exchanger, a honeycomb heating element provided substantially below the heat exchanger, and a heating element provided substantially above and above the heating element. A water drop protection member is provided, and substantially the entire amount of the air flow that is circulated in the refrigerating chamber and the heat exchanger generated by the fan is configured to pass through the honeycomb ceramic heating element, and the heating element is a catalyst. A refrigerator having a coating layer. 2. A refrigerating chamber, a refrigerating chamber, a fan A, a fan B, a heat exchanger, a honeycomb-shaped ceramic heating element provided substantially below the heat exchanger, and a substantial heating element. Substantially all of the air flow that is generated by the fan A and that circulates from the freezer compartment to the heat exchanger via the refrigerating compartment is substantially the entire amount of the honeycomb ceramics. Air flow path A configured to pass through a heating element, and air passing through an air flow circulating from the refrigerating chamber to the heating element and the heat exchanger without passing through the freezing chamber generated by the fan B. A refrigerator comprising a flow path B and the honeycomb-shaped ceramic heating element having a catalyst coating layer. 3. The refrigerator according to claim 2, further comprising a control valve for controlling an air inflow amount into the fan B. 4. A honeycomb ceramic heating element in which the honeycomb ceramic heating element is at least substantially quadrangular prismatic or substantially quadrangular plate-shaped, and aluminum and nickel formed on a pair of outer peripheral surfaces facing each other of the honeycomb element. copper,
2. A catalyst coating layer comprising a conductive electrode made of at least one selected from brass, silver-Pd, silver-Pt, and Pt and coating the surface of the honeycomb-shaped ceramic resistor.
Or the refrigerator according to 2. 5. The refrigerator according to claim 4, wherein an oxidation reaction preventing layer is provided between the catalyst coating layer of the honeycomb ceramic heating element and the honeycomb ceramic resistor and / or the conductive electrode. 6. The heating element according to claim 4, wherein the conductive electrode is formed by thermal spraying. 7. The refrigerator according to claim 5, wherein the oxidation reaction preventive layer comprises at least one selected from glass, silica, alumina, titania, titanocarbosilane, and perhydropolysilazane. 8. The refrigerator according to claim 4, wherein the honeycomb-shaped ceramic resistor is SiC. 9. The refrigerator according to claim 1, 2, 4 or 5, wherein the catalyst coating layer comprises at least activated alumina, a platinum group metal, zeolite and an inorganic binder. 10. The refrigerator according to claim 1, wherein the catalyst coating layer contains copper oxide. 11. The refrigerator according to claim 1, wherein the catalyst coating layer comprises activated alumina carrying a noble metal and copper oxide. 12. The refrigerator according to claim 9, wherein the zeolite contains at least a pentasil-type zeolite. 13. The refrigerator according to claim 9, wherein the zeolite contains at least mordenite or Y-type zeolite. 14. The refrigerator according to claim 9, wherein the zeolite contains at least copper zeolite. 15. The pentasil-type zeolite is H-ZSM.
The refrigerator according to claim 12, comprising at least one selected from the group consisting of 5, Na-ZSM5. 16. The inorganic binder is silica.
The refrigerator as described. 17. The refrigerator according to claim 9, wherein the platinum group metal contains at least Pt.