JP5712744B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner including a detector that displays a detection of corrosion caused by an organic acid in a copper heat transfer tube used as a heat exchanger by a color change.

  Since copper has excellent corrosion resistance and excellent heat conductivity and workability, it is used in heat transfer tubes of heat exchangers of air conditioners. FIG. 4 is a view showing an example of a conventional heat exchanger. In the figure, the heat exchanger 200 is configured by attaching a plate fin 101 to a copper heat transfer tube 102. The copper heat transfer tube 102 includes straight tube portions 102a and 102b and a hairpin portion 103. When local corrosion occurs in these portions, there is a problem that refrigerant gas leaks. As local corrosion that causes such defects, ant nest corrosion, stress corrosion cracking, and the like are known.

Among these, ant nest-like corrosion occurs in an organic acid atmosphere such as formic acid or acetic acid, and is called ant nest-like corrosion because the corrosion shape is ant nest-like micropores.
The reason why the heat exchanger is exposed to the organic acid atmosphere is that the lubricating oil or processing oil used during the manufacture of the heat exchanger remains attached to the copper heat transfer tube, which deteriorates and generates an organic acid. When the organic acid contained in the building materials and interior materials of the building where the air conditioner is installed volatilizes, or when it is released from the organic material pasted inside the air conditioner or the adhesive used for the pasting Various causes are considered.

  Conventionally, as a local corrosion detection method, a method related to stress corrosion cracking has been mainly used, and few detection methods corresponding to ant nest corrosion are known. As a detection method for stress corrosion cracking, for example, as a detection method developed for quantitatively predicting the risk of structural damage due to stress corrosion cracking and managing long-term life, Developed technology for sensitively observing phenomena at the initial stage (cracking and sprouting stage) at a small stage and a stage with strong stochastic character. There is a method for detecting the occurrence of stress corrosion cracking and / or pitting corrosion, which is characterized by visualizing the occurrence process of stress corrosion cracking and / or pitting corrosion of a metal material (see, for example, Patent Document 1).

Further, when inspecting whether the atmosphere is an organic acid atmosphere, an active sampling method is generally used. The active sampling method is a method in which air is forced to pass through a collection tube using a suction pump and the material is collected. It was selected as a standard method in the “Guidelines for Measuring Indoor Air” established by the Ministry of Health, Labor and Welfare. Yes.
This active sampling method can evaluate the current air quality in a short time of several minutes to 30 minutes, but cannot know the change over time from the shipment of the product over a long period of time.

JP 2008-216232 A (page 4, lines 19 to 44)

  As described above, as a method for predicting local corrosion, there are few known detection methods corresponding to ant nest corrosion. There was no non-destructive method for detecting ant nest-like corrosion, and there was no choice but to observe the cross section after embedding and polishing the cut surface of the copper tube.

  The present invention has been made to solve the above-described problems, and is an organic acid that causes ant nest corrosion (for example, acetic acid, formic acid, other organic acids. Hereinafter, only with organic acids) It is an object of the present invention to provide a detection method capable of easily and non-destructively confirming the occurrence of (described) and preventing refrigerant gas leakage in advance.

Air conditioner according to the present invention comprises a heat exchanger using a copper pipe as a heat transfer tube, and a detecting means for detecting the organic acid in the intake atmosphere, sensing means comprises an oxidation catalyst and an organic acid detecting agent It is characterized by this.

  According to the air conditioner according to the present invention, the amount of organic acid in the air can be integratedly detected by checking the degree of discoloration, and gas leakage due to ant nest corrosion can be predicted in advance, and heat exchange The equipment can be replaced at an appropriate time.

It is front sectional drawing of the indoor unit of the air conditioner which concerns on Embodiment 1 of this invention. It is a schematic sectional drawing of the detector which concerns on Embodiment 1 of this invention. It is sectional drawing of the front view of the air conditioner of the detector which concerns on Embodiment 3 of this invention. It is the figure which showed an example of the conventional heat exchanger.

Embodiment 1 FIG.
Next, Embodiment 1 of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar reference numerals are used for the same or similar parts. The drawings are schematic, and the ratio of each dimension is different from the actual one. Accordingly, specific dimensions and the like are determined in consideration of the following description, and the relations and ratios of the mutual dimensions may be different from those in the actual drawings.

  FIG. 1 is a front sectional view of an indoor unit in an air conditioner according to Embodiment 1 of the present invention. In the figure, an indoor unit 100 of an air conditioner (hereinafter sometimes referred to only as an indoor unit) 100 is mainly installed on the ceiling. A suction port 10 and an air outlet 11 are provided on the lower surface of the housing 9, and the blower 4 is installed in the housing 9.

  In the housing 9, a suction air passage 1 (hereinafter sometimes referred to as an upstream side) from the suction port 10 to the blower 4 and a blowout air passage 5 (hereinafter, downstream) from the blower 4 to the blowout port 11. May be described as a side). The air sucked from the suction port 10 is subjected to dust removal by an air cleaning filter 2 provided in the suction air passage 1, cooled or heated by the heat exchanger 3, and sent to the blower 4.

  The heat exchanger 3 is disposed obliquely when viewed from the front, and a drain pan 6 is provided below to receive moisture (dew condensation water or the like) that has dropped on the heat exchanger 3. Further, a temperature sensor 7 is disposed between the air purifying filter 2 and the drain pan 6, and a detector 8 is disposed side by side with the temperature sensor 7. By arranging in this way, it is possible to provide an air conditioner that has no pressure loss and does not affect the cooling and heating efficiency.

  FIG. 2 is a schematic diagram of a cross section of the detector according to Embodiment 1 of the present invention. In the figure, a detector 8 includes a detection unit 20 for detecting a specific gas generated from an organic acid or the like in the air, a support 23 that supports the detection unit 20, a gas transmission hole 24, and an observation window. Part 25. The amount of gas is detected by adsorbing the organic acid that has passed through the gas permeation hole 24 to the detection member 20, and the amount can be visually observed from the observation window 25.

  The detection unit 20 uses a porous sheet such as a nonwoven fabric or silica gel as the carrier 26, and the carrier 26 is mixed with copper powder 21 as an oxidation catalyst and reacts with an organic acid to exhibit a color reaction. The organic acid detector 22 is impregnated and dried.

  Here, the organic acid detection agent 22 utilizes a change in the color change region by an acid-base indicator, a redox indicator, or a detection reagent for a metal salt / metal oxide. For example, a coloring agent in which an acid-base indicator that reacts in the presence of acetic acid or formic acid is dissolved in a wetting agent such as glycerin is used, and this agent is adsorbed on the surface of substrate particles such as silica gel, aluminum, or silicon dioxide. In particular, by using the ground particles obtained by crushing and classifying silicon dioxide, the air smoothly flows through the gaps between the particles, and the color change can be clearly grasped.

It is desirable to use an acid-base indicator having a color change range near pH 4. For example, diazo methyl orange and sultone bromocresol-ol green are preferred.
Methyl orange changes from orange to red over pH 3.2 to 4.2, and bromocresol-ol green reacts with carboxylic acid to change from blue to yellow. From this, discoloration near pH 4 can be confirmed, and the possibility of ant nest corrosion can be detected.
In the above embodiment, “detection reagent” refers to a reagent that can be determined only by the presence or absence of discoloration, while “indicator” refers to a substance that can be determined not only by the presence or absence of discoloration but also by quantification based on pH value or the like However, the boundary is not clear and is not limited to this.

In addition, alkali and acid-base indicators that react with acetic acid or formic acid can also be used as detection agents. Thereby, the efficiency of discoloration can be improved. In this case, acetic acid or formic acid reacts with alkali and the acid-base indicator changes color. Various alkalis can be used. As an example of the reaction principle in this case, it is expressed as follows:
CH ₃ COOH + Na ₂ SiO.nH ₂ O → CH ₃ CO ₂ Na + H ₂ O
In this case, it is preferable to use an acid-base indicator having a color change range near neutrality. For example, triphenylmethane-based cresol-red and sultone-based phenol red are preferred. Near neutral, Cresol-red is changed from pale pink to yellow, and phenol-red is changed from red to yellow. Thereby, generation | occurrence | production of an organic acid can be confirmed.

  According to this configuration, by detecting the amount of organic acid in the air and confirming the degree of discoloration, it is possible to predict gas leakage due to ant nest-like corrosion in advance and clarify the replacement time of the heat exchanger.

  The relationship between the organic acid concentration or pH and the ant nest corrosion is shown in Table 1 or 2 below.

  From Table 1, it can be seen that a clear correlation may not be observed when the organic acid concentration is 0.5 ppm. On the other hand, from Table 2, it can be confirmed that ant nest corrosion does not occur at pH 4 or higher.

Here, by mixing the copper powder 21, copper acts as an oxidation catalyst, generates an organic acid, accelerates ant nest-like corrosion, and facilitates detection.
An appropriate amount of the copper powder 21 is added as an oxidation catalyst. When this amount is small, there is a problem that the organic acid is not sufficiently generated. Conversely, when the amount is large, there is a problem that the change of the colorant is difficult to understand.

  The amount of copper powder 21 added was 0%, 0.01%, 0.1%, 0.5%, 1.0%, and the degree of discoloration when left for 120 hours, 240 hours, 480 hours was examined. The results are shown in 3 below. The degree of color change is measured using a color difference meter. Color difference: 0 to 1.5 is ◎, 1.5 to 3.0 is ○, 3.0 to 6.0 is Δ, 6.0 to 12.0 is × And 12.0 or more was set to xx.

Accordingly, the amount of copper added is desirably 0.1% to 0.5%. When this amount is as small as 0.01%, it is understood that the organic acid is not sufficiently generated without discoloration. Further, when the amount is as large as 1.0% or more, there is a problem that it is difficult to understand the change of the colorant with a large degree of discoloration.

  In addition to the copper powder, a noble metal such as platinum or palladium, or a base metal such as manganese or nickel can be used as the catalyst metal.

Embodiment 2. FIG.
In the first embodiment, the organic acid detector uses an acid-base indicator, an oxidation-reduction indicator, or a change in the color change range by a metal salt / metal oxide detection reagent, and reacts with an organic acid. It shows a color reaction relatively quickly, but knows the change in the amount of organic acid generated over time by using an organic acid detector whose color or shade changes gradually according to the amount of organic acid generated. It is possible to predict the replacement time of the heat exchanger. In particular, since the gas leak can be predicted in advance, the amount of greenhouse gas emissions due to the gas leak can be suppressed.
The configuration is the same as that shown in FIG.

  As the organic acid detection agent according to Embodiment 2 of the present invention, for example, sodium metasilicate is used as an alkali that reacts with acetic acid or formic acid as a detection reagent, and cresol red is used as an acid-base indicator. The detection reagent is coated on the surface of silicon dioxide. Table 4 below shows the results of investigating the presence or absence of ant nest corrosion using a system in which 0.1% of copper powder was added to this and the standing time and the degree of discoloration. The degree of color change is measured using a color difference meter. Color difference: 0 to 1.5 is ◎, 1.5 to 3.0 is ○, 3.0 to 6.0 is Δ, 6.0 to 12.0 is × And 12.0 or more was set to xx.

From this, when the degree of discoloration exceeds 12.0 or more, it becomes clear that ant nest-like corrosion occurs, and it becomes possible to predict the replacement time of the heat exchanger. In particular, since the gas leak can be predicted in advance, the amount of greenhouse gas emissions due to the gas leak can be suppressed.

Embodiment 3 FIG.
FIG. 3 is a front sectional view conceptually showing the indoor unit of an air conditioner that is Embodiment 3 of the present invention. This indoor unit of the air conditioner has the same configuration as that of the first embodiment, and the difference is the position of the detector and the number of installation. In the indoor unit 100, detectors 15a to 15c according to Embodiment 3 of the present invention are arranged immediately after the intake air and the blown air pass as shown in FIG. 3 and at three locations inside the indoor unit.

  Here, the amount of organic acid in the indoor air in which the air conditioner is installed is set immediately after the intake air passes, and the amount of organic acid in the air diffused in the indoor unit is set just after the blown air. Can be confirmed. Thereby, the difference of the time-dependent change of the organic acid amount in a suction | inhalation and blowing location can be grasped | ascertained. Furthermore, since the airflow passing through the heat exchanger 3 is not affected by being installed outside the ventilation path inside the indoor unit, the amount of organic acid generated in the indoor unit can be monitored without impairing the cooling / heating efficiency. it can.

  DESCRIPTION OF SYMBOLS 1 Suction air path, 2 Air purifying filter-3 Heat exchanger, 4 Blower, 5 Blower air path, 6 Drain pan, 7 Temperature sensor, 8, 15a, 15b, 15c Detector, 9 Case, 10 Suction port, 11 Air outlet, 20 detection member 21 copper powder, 22 organic acid detection agent, 23 support, 24 gas permeation hole, 25 observation window part, 26 carrier, 100 indoor unit

Claims (4)

A heat exchanger using a copper pipe as a heat transfer tube,
A detection means for detecting organic acid in the intake atmosphere ,
The air conditioner characterized in that the detection means includes an oxidation catalyst and an organic acid detection agent .   The air conditioner according to claim 1, wherein the oxidation catalyst is a catalyst metal, and the catalyst metal includes any one of copper powder, platinum, palladium, manganese, and nickel. The detection means has a detection member in which the oxidation catalyst and the organic acid detection agent are added to a carrier,
The organic acid detection agent, an acid - base indicators, redox indicator or a metal salt - according to claim 1 or 2, characterized in that utilizes the change of color transition range by the detection reagent of the metal oxide Air conditioner. The detection means includes a support that supports the detection member, a window provided on the detection member, and a gas permeation hole .
The air conditioner according to claim 3, wherein the organic acid in the intake air atmosphere is detected by observing the degree of discoloration of the detection member from the window.

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