WO2020080426A1 - Method for inhibiting progress of corrosion in air conditioners, air conditioner, and refrigerant piping - Google Patents

Abstract

A method for inhibiting progress of corrosion in an air-conditioner comprising an indoor unit that has an indoor heat exchanger with refrigerant piping made from phosphorus deoxidized copper or oxygen-free copper, wherein moisture, which is present in corroded pores occurring in the refrigerant piping, is removed after a cooling operation or a dehumidification operation during air conditioner operation. This moisture removing operation is performed within the interval from after the cooling operation or the dehumidification operation is completed until a designated time period has elapsed. In addition, cuprous oxide is provided on the inner wall face of the corroded pores formed in the refrigerant piping that is formed from copper piping for air conditioners, wherein the copper piping has a copper content of 99.95% or more and an oxygen content of 10 ppm or less, and the remainder is unavoidable impurities.

Description

Method of suppressing corrosion progress of air conditioner, air conditioner and refrigerant pipe

The present invention relates to a method for suppressing the progress of corrosion of an air conditioner, an air conditioner, and a refrigerant pipe.

Conventionally, a fin-and-tube heat exchanger having a refrigerant pipe and fins has been used for an indoor unit of an air conditioner. As the refrigerant tube, a copper tube made of JIS standard phosphorous deoxidized copper C1220 is used because of its excellent thermal conductivity and workability. In recent years, heat exchangers have been required to more strictly control refrigerant leakage, and in particular, countermeasures against ant nest corrosion occurring in copper pipes have become more necessary.

Patent Document 1 describes that it is made of oxygen-free copper containing 0.05 to 1.5% by mass of Mn and an oxygen content of 100 ppm or less, and is resistant to the ant-like corrosion resistance used in heat exchanger pipes. An excellent corrosion resistant copper alloy tube is disclosed. Further, in Patent Document 2, copper containing 0.05 to 5% by mass of Mn and 0.05 to 5% by mass of Mg alone or in combination, or further containing 0.05 to 10% by mass of Zn. A fin-tube heat exchanger is disclosed in which a copper alloy tube made of an alloy is used to improve the ant nest corrosion resistance.

Japanese Unexamined Patent Publication No. 06-197273 Japanese Patent No. 3046471

The corrosion-resistant copper alloy pipe of Patent Document 1 has been significantly improved in corrosion resistance against ant nest corrosion compared to the phosphorus-deoxidized copper pipe, and is therefore used in air conditioner models that place importance on ant nest corrosion countermeasures. In order to further improve the corrosion resistance to ant-like corrosion, it is effective to make the content of Mn exceed 1.5% as described in Patent Document 2, but with the standard material. Compared with a certain phosphorous deoxidized copper pipe, there is a problem that rolling workability and brazing property are deteriorated and the manufacturing cost is increased.

The present invention has been made in view of such a problem, in an air conditioner including an indoor unit having a heat exchanger using a refrigerant pipe made of copper or copper alloy, in which the corrosion of ant nest corrosion in the refrigerant pipe The first object is to provide a technique having an excellent effect of suppressing the progress.
A second object of the present invention is to provide an air conditioner equipped with an indoor unit, which is excellent in the effect of suppressing the progress of corrosion of ant nest corrosion in a refrigerant pipe using a specific copper material. .

A method for inhibiting corrosion progress of an air conditioner according to the present invention is a method for inhibiting corrosion progress of an air conditioner including an indoor unit having an indoor heat exchanger using a refrigerant pipe made of phosphorous deoxidized copper. In this case, after the cooling operation or the dehumidifying operation is completed, a moisture removing operation is performed to remove the water present inside the corrosion holes generated in the refrigerant pipe, and the moisture removing operation is the cooling operation or the dehumidifying operation end. It will be done within 10 days after the end.

A method for controlling the progress of corrosion of an air conditioner according to the present invention is a method for inhibiting the progress of corrosion of an air conditioner including an indoor unit having an indoor heat exchanger that uses a refrigerant pipe made of oxygen-free copper, and At this time, after the end of the cooling operation or the dehumidifying operation, a water removing operation for removing the water present inside the corrosion holes generated in the refrigerant pipe is performed, and the water removing operation ends the cooling operation or the dehumidifying operation. It will be done within 60 days after the later.

In the method for suppressing the progress of corrosion of an air conditioner according to the present invention, by performing the water removal operation, the progress of corrosion holes generated in the refrigerant pipe to the through holes that penetrate the pipe wall thickness is suppressed.

In the method for suppressing the progress of corrosion of an air conditioner according to the present invention, it is preferable to further perform a display operation for notifying the user that the water removal operation is necessary before the water removal operation.

In the method for suppressing the progress of corrosion of an air conditioner according to the present invention, when the refrigerant pipe made of phosphorus deoxidized copper is used, the display operation is performed until 5 days have elapsed from the end of the cooling operation or the dehumidification operation. Is preferably carried out. Further, in the method for suppressing the progress of corrosion of an air conditioner according to the present invention, when the refrigerant pipe made of oxygen-free copper is used, the display operation is performed until 50 days have elapsed from the end of the cooling operation or the dehumidifying operation. It is preferable to be performed in between.

In the method for suppressing corrosion progress of an air conditioner according to the present invention, since the moisture removal operation is reliably performed by further performing the display operation, particularly the display operation performed after a predetermined period, the corrosion hole generated in the refrigerant pipe is It is further suppressed to proceed to the through hole penetrating the wall thickness.

In the method for suppressing corrosion progress of an air conditioner according to the present invention, it is preferable that the water removal operation is performed by heating and drying the refrigerant pipe.

In the method for suppressing the progress of corrosion of an air conditioner according to the present invention, the heating and drying satisfy the following expression (1) when the holding temperature of the refrigerant pipe is X (° C) and the holding time is Y (min). Is preferred.
Y ≧ 4000e ^−0.11X (1)

The method for suppressing the progress of corrosion of an air conditioner according to the present invention is an air conditioner in which the Cu content used in the indoor unit of the air conditioner is 99.95% or more, the oxygen content is 10 ppm or less, and the balance is unavoidable impurities. Cuprous oxide is provided on the inner wall surface of the corrosion hole formed in the refrigerant pipe made of the copper pipe for use. By providing cuprous oxide on the inner wall surface of the corrosion hole in this way, the oxidation of copper in the corrosion hole is suppressed, and the progress of ant nest corrosion that progresses to the through hole that penetrates the wall thickness of the corrosion hole is suppressed. can do.

In the method for suppressing the progress of corrosion of an air conditioner according to the present invention, it is preferable that a moisture removing operation is performed to provide cuprous oxide in the corrosion hole, and the moisture removing operation is performed by heating and drying the refrigerant pipe.

The method for controlling the progress of corrosion of an air conditioner according to the present invention, by performing the moisture removal operation, the moisture in the corrosion holes generated in the refrigerant pipe is removed and cuprous oxide is formed in the corrosion holes to form at least cuprous oxide. By partially filling the inside of the corrosion hole in the tip side, the penetration of water is blocked and the progress to the through hole penetrating the wall thickness of the tube is suppressed.

In the method for suppressing corrosion progress of an air conditioner according to the present invention, the moisture removal operation may be performed within 60 days or 90 days after the end of the cooling operation or the dehumidifying operation of the air conditioner. preferable. Further, in the method for suppressing corrosion progress of an air conditioner according to the present invention, it is more preferable to further perform a display operation informing the user that the water removal operation is necessary before the water removal operation.

In the method for suppressing corrosion progress of an air conditioner according to the present invention, by performing the moisture removal operation within 60 days or 90 days, the moisture in the corrosion holes generated in the refrigerant pipe due to the moisture adhered by the cooling operation or the dehumidifying operation is removed. It is possible to suppress the removal of cuprous oxide in the corrosive holes and progress to the through holes penetrating the pipe wall thickness. Further, in the method for suppressing corrosion progress of an air conditioner according to the present invention, it is preferable to further perform a display operation, particularly a display operation performed after a predetermined period. This ensures that the water removal operation is performed.

In the method for suppressing the progress of corrosion of an air conditioner according to the present invention, it is preferable that the heating and drying is performed by a heating operation of the air conditioner or a heater provided in the indoor unit.

In the method for suppressing the progress of corrosion of an air conditioner according to the present invention, it is preferable that the heating and drying is performed together with the prevention of exhaust from the indoor unit to the room and the prevention of exhaust heat.
In the method for suppressing the progress of corrosion of an air conditioner according to the present invention, it is preferable that the exhaust prevention and the exhaust heat prevention are performed by a louver provided in the indoor unit.
In the method for suppressing corrosion progress of an air conditioner according to the present invention, it is preferable that the exhaust prevention and the exhaust heat prevention are performed by a drain pipe provided in the indoor unit.

In the method for suppressing the progress of corrosion of an air conditioner according to the present invention, it is preferable that the water removal operation is performed by vacuuming (pressure reduction processing) for reducing the pressure inside the indoor unit.

In the method for suppressing corrosion progress of an air conditioner according to the present invention, by performing vacuuming of the indoor unit as the moisture removal operation, the corrosion holes generated in the refrigerant pipe can progress to the through holes that penetrate the pipe wall thickness. It is further suppressed.

An air conditioner according to the present invention is an air conditioner including an indoor unit having an indoor heat exchanger using a refrigerant pipe, and an outdoor unit, wherein the indoor unit uses the corrosion progress suppressing method for the air conditioner to A control device for controlling the air conditioner will be provided.

In the air conditioner according to the present invention, the indoor unit is provided with a control device that controls the air conditioner by using the above-described corrosion progress suppressing method for the air conditioner, so that the corrosion hole generated in the refrigerant pipe penetrates through the pipe wall thickness. The progress to the hole is suppressed.

The refrigerant pipe according to the present invention is a refrigerant pipe used in an indoor heat exchanger provided in an indoor unit of an air conditioner, and using the corrosion progress suppressing method of the air conditioner, corrosion generated in the refrigerant pipe. It is assumed that cuprous oxide is formed inside the pores.

In the refrigerant tube according to the present invention, by forming cuprous oxide inside the corrosion hole generated in the refrigerant tube, it is possible to prevent the corrosion hole from progressing to a through hole that penetrates the wall thickness of the tube.

According to the corrosion progress inhibiting method for an air conditioner, the air conditioner, and the refrigerant pipe according to the present invention, in a configuration including an indoor unit having a heat exchanger using a refrigerant pipe made of phosphorus deoxidized copper or oxygen-free copper, the refrigerant pipe In particular, it is excellent in the effect of suppressing the corrosion progress of ant nest corrosion. As a result, leakage of the refrigerant in the air conditioner can be suppressed, the frequency of exchanging the heat exchanger can be extended, and the operating cost of the air conditioner can be reduced.
Further, an indoor unit having a heat exchanger using a refrigerant pipe made of a copper pipe for an air conditioner, the Cu content of which is 99.95% or more, the oxygen content of which is 10 ppm or less, and the balance of which is an unavoidable impurity is provided. In the constitution, it is excellent in the effect of suppressing the progress of corrosion, especially the ant nest corrosion in the refrigerant pipe. As a result, leakage of the refrigerant in the air conditioner can be suppressed, the frequency of exchanging the heat exchanger can be extended, and the operating cost of the air conditioner can be reduced.

It is a cycle diagram which shows typically the structure of the air conditioner which concerns on this invention. It is sectional drawing which shows typically the structure of the indoor unit of the air conditioner which concerns on this invention. It is a partial front view which shows the structure of the heat exchanger used for an indoor unit. It is a block diagram which shows the structure of the control apparatus used for an indoor unit. It is a front view which shows the structure of a corrosion reproduction apparatus. It is sectional drawing which shows typically the state which provided the cuprous oxide in the ant nest-like corrosion hole formed in the refrigerant pipe of the air conditioner which concerns on this invention. It is sectional drawing which expands the area | region of A of FIG. 6A, and is shown typically. In the refrigerant pipe of the air conditioner according to the present invention, the progress state of corrosion when dried twice a day in a test period of 20 days in an atmosphere of 0.5% formic acid was measured by an X-ray CT scanner (manufactured by Shimadzu Corporation, It is a photograph observed with a model type inspeXio SMX-225CT FPD). 7A is a photograph observed with an X-ray CT scanner (manufactured by Shimadzu Corporation, model inspeXio SMX-225CT FPD) in a state in which the position of the corrosion hole at the observation point is cut in the longitudinal direction of the refrigerant pipe in FIG. 7A. In the refrigerant pipe of the air conditioner according to the present invention, the progress of corrosion when not dried in the atmosphere of 0.5% formic acid during the test period of 20 days was measured by an X-ray CT scanner (manufactured by Shimadzu Corporation, model inspeXio SMX). -225CT FPD). 8A is a photograph observed with an X-ray CT scanner (manufactured by Shimadzu, model inspeXio SMX-225CT FPD) in a state in which the position of the corrosion hole at the observation point in FIG. 8A is cut in the longitudinal direction of the refrigerant pipe. In the refrigerant pipe of the air conditioner according to the present invention, the progress of corrosion once dried before observation was observed with an X-ray CT scanner (manufactured by Shimadzu Corporation, model inspeXio SMX-225CT FPD) once before observation in a test period of 10 days. It is an observed photograph. 9A is a photograph observed with an X-ray CT scanner (manufactured by Shimadzu Corporation, model inspeXio SMX-225CT FPD) with the position of the corrosion hole at the observation point in FIG. 9A being cut in the longitudinal direction of the refrigerant pipe. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 9A. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 9B. In the refrigerant pipe of the air conditioner according to the present invention, the progress of corrosion when dried twice before observation during the test period of 20 days was confirmed by an X-ray CT scanner (manufactured by Shimadzu Corporation, model inspeXio SMX-225CT FPD). It is an observed photograph. FIG. 10A is a photograph observed with an X-ray CT scanner (manufactured by Shimadzu Corporation, model inspeXio SMX-225CT FPD) with the position of the corrosion hole at the observation point in FIG. 10A being cut in the longitudinal direction of the refrigerant pipe. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 10A. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 10B. In the refrigerant pipe of the air conditioner according to the present invention, the progress of corrosion when dried 3 times before observation during the test period of 30 days was measured by an X-ray CT scanner (Shimadzu Corporation, model inspeXio SMX-225CT FPD). It is an observed photograph. FIG. 11B is a photograph observed with an X-ray CT scanner (manufactured by Shimadzu Corporation, model inspeXio SMX225CT FPD) in a state in which the position of the corrosion hole at the observation point in FIG. 11A is cut in the longitudinal direction of the refrigerant pipe. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 11A. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 11B. In the refrigerant pipe of the air conditioner according to the present invention, the progress of corrosion when dried 4 times before observation in 40 days of the test period was measured by an X-ray CT scanner (manufactured by Shimadzu Corporation, model inspeXio SMX-225CT FPD). It is an observed photograph. 12A is a photograph observed by an X-ray CT scanner (manufactured by Shimadzu Corporation, model inspeXio SMX-225CT FPD) in a state in which the position of the corrosion hole at the observation point in FIG. 12A is cut in the longitudinal direction of the refrigerant pipe. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 12A. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 12B. In the refrigerant pipe of the air conditioner according to the present invention, the progress of corrosion when dried 5 times before observation in a test period of 50 days was performed by an X-ray CT scanner (manufactured by Shimadzu Corporation, model inspeXio SMX-225CT FPD). It is an observed photograph. FIG. 13A is a photograph observed with an X-ray CT scanner (manufactured by Shimadzu Corp., model inspeXio SMX-225CT FPD) in a state where the position of the corrosion hole at the observation point in FIG. 13A is cut in the longitudinal direction of the refrigerant pipe. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 13A. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 13B. In the refrigerant pipe of the air conditioner according to the present invention, the progress of corrosion when dried six times before observation in the test period of 60 days was confirmed by an X-ray CT scanner (manufactured by Shimadzu Corporation, model inspeXio SMX-225CT FPD). It is an observed photograph. It is the photograph observed with the X-ray CT scanner (the Shimadzu Corporation make, model inspeXio SMX-225CT FPD) in the state which cut | disconnected the position of the corrosion hole of the observation point in FIG. 14A in the longitudinal direction of the refrigerant pipe. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 14A. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 14B. In the refrigerant pipe of the air conditioner according to the present invention, the progress of corrosion when dried 7 times before observation within 90 days of the test period was measured by an X-ray CT scanner (manufactured by Shimadzu Corporation, model inspeXio SMX-225CT FPD). It is an observed photograph. It is the photograph observed with the X-ray CT scanner (the Shimadzu Corporation make, model inspeXio SMX-225CT FPD) in the state which cut | disconnected the position of the corrosion hole of the observation point in FIG. 15A in the longitudinal direction of the refrigerant pipe. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 15A. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 15B. In the refrigerant pipe of the air conditioner according to the present invention, the progress of corrosion when dried 8 times before observation for 120 days during the test period is observed with an X-ray CT scanner (Shimadzu Corporation, model inspeXio SMX-225CT FPD). It is a photograph taken. FIG. 16B is a photograph observed with an X-ray CT scanner (manufactured by Shimadzu Corp., model inspeXio SMX-225CT FPD) in a state where the position of the corrosion hole at the observation point in FIG. 16A is cut in the longitudinal direction of the refrigerant pipe. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 16A. It is the photograph which expanded the position of the corrosion hole of the observation point of FIG. 16B.

First, an air conditioner, an indoor unit, and an indoor heat exchanger used in the corrosion progress inhibiting method of the present invention will be described with reference to the drawings.

<Air conditioner>
As shown in FIG. 1, the air conditioner 1 includes an outdoor unit 2, an indoor unit 3, and a control device 17 (see FIG. 2), and the outdoor unit 2 and the indoor unit 3 are connected via a refrigerant pipe 9. Has been done. The outdoor unit 2 connects a compressor 4 for compressing a refrigerant, a four-way valve 5 for switching the flow of the refrigerant, an outdoor heat exchanger 6 for exchanging heat with the refrigerant, and an expansion valve 7 for expanding the refrigerant, respectively. The refrigerant pipe 9 is provided. The indoor unit 3 includes an indoor heat exchanger 8 that is connected to the four-way valve 5 and the expansion valve 7 via a refrigerant pipe 9 to exchange heat with the refrigerant.

In the air conditioner 1, during the cooling operation or the dehumidifying operation, the refrigerant discharged from the compressor 4 flows through the four-way valve 5, the outdoor heat exchanger 6, the expansion valve 7, the indoor heat exchanger 8 and the four-way valve 5 again. The air is sucked into the compressor 4 via the air conditioning system and the cooling operation or the dehumidifying operation is performed.

In the air conditioner 1, during the heating operation, the refrigerant discharged from the compressor 4 flows through the four-way valve 5, the indoor heat exchanger 8, the expansion valve 7, and the outdoor heat exchanger 6, and is compressed again via the four-way valve 5. It is sucked into the machine 4 and the heating operation is performed.

<Indoor unit>
As shown in FIGS. 2 and 3, the indoor unit 3 includes a casing 14 and an intake grill 12 that form an indoor air duct 13, an indoor heat exchanger 8 and an indoor blower 10 that are arranged in the indoor air duct 13, and will be described later. A controller 17 for controlling the air conditioner 1 by using the corrosion progress suppressing method described above, and a heater 11 used for removing water inside the corrosion holes generated in the refrigerant pipe 21 of the indoor heat exchanger 8 under the control of the controller 17. The louver 15, the drain pipe 16, and the decompression pump 19 are provided. The indoor unit 3 may include a plurality of indoor heat exchangers 8 and a plurality of indoor fans 10, and the number of the indoor heat exchangers 8 and the number of the indoor fans 10 do not have to be the same. Although the control device 17 is arranged in the indoor unit 3 in the present embodiment, the present invention is not limited to this embodiment. Further, when the moisture removal operation is performed by the heating operation of the air conditioner 1, the heater 11 and the decompression pump 19 are not always necessary.

In the indoor unit 3, during the cooling operation, the dehumidifying operation, or the heating operation, the indoor air sucked from the intake grill 12 is heat-exchanged by the indoor heat exchanger 8 into cold air or warm air, and the cold air or warm air is used indoors. The blower 10 blows the air from the air outlet 18 into a room that is a living space to perform a cooling operation, a dehumidifying operation, or a heating operation.

<Indoor heat exchanger>
As shown in FIG. 3, the indoor heat exchanger 8 includes a straight pipe 21a and a refrigerant pipe 21 including a large number of straight pipes 21a arranged in parallel and a large number of return bend pipes 21b joined to both ends of the straight pipe 21a. And a large number of plate-shaped fins 22 arranged in parallel on the outer surface of the plate at regular intervals. As the refrigerant pipe 21, a copper pipe made of phosphorus deoxidized copper C1220 or oxygen-free copper C1020 specified in JIS H 3300: 2012 (CDA10200) is used from the viewpoint of thermal conductivity and workability. An aluminum fin is used for the fin 22 from the viewpoint of thermal conductivity and workability.

A straight tube having a smooth inner surface is used as the straight tube 21a, but in order to improve thermal conductivity, it is preferable to use a grooved tube in which a groove having a predetermined shape is formed on the inner surface of the tube. The shape of the groove is not particularly limited, but the groove lead angle of the groove is 15 to 45 degrees, the groove depth is 0.10 to 0.35 mm, and the crest angle of the fin 22 formed between the grooves is 5 to 30 degrees. The fin root radius is preferably 1/10 to 1/3 of the groove depth. Further, although a smooth pipe having a smooth inner surface is used as the return bend pipe 21b, it is preferable to use a grooved pipe similar to the straight pipe 21a in order to improve thermal conductivity. The wall thickness of these tubes is generally around 0.2 mm.

In the indoor heat exchanger 8, during the cooling operation or the dehumidifying operation, the refrigerant expanded by the expansion valve 7 of the outdoor unit 2 is supplied to the inside of the refrigerant pipe 21, whereby the indoor air is heat-exchanged with the cool air and the cooling operation is performed. The dehumidifying operation is performed. At this time, the fins 22 installed on the outer surface of the refrigerant tube 21 are cooled to a temperature lower than room temperature by the refrigerant flowing through the refrigerant tube 21 of the indoor heat exchanger 8. Thereby, the air around the fins 22 is cooled, and the dew point of the indoor air is higher than the temperature of the fins 22, so that dew condensation occurs on the fins 22. If the atmosphere in which the indoor unit 3 is installed contains a lower carboxylic acid or the like, it may dissolve in dew condensation water and cause ant nest corrosion in the refrigerant pipe 21.

In the indoor heat exchanger 8, during the heating operation, the refrigerant discharged from the compressor 4 of the outdoor unit 2 is supplied to the inside of the refrigerant pipe 21 via the four-way valve 5, so that the indoor air exchanges heat with warm air. The heating operation is performed.

<Control device>
The controller 17 operates the air conditioner 1 after a predetermined period has elapsed from the end of the first cooling operation or dehumidifying operation, or after the first cooling operation or dehumidifying operation after the last moisture removal operation, After a lapse of a predetermined period, the air conditioner 1 is controlled so as to perform a moisture removal operation for removing moisture existing inside the corrosion holes generated in the refrigerant pipe 21 of the indoor unit 3 (indoor heat exchanger 8). The first cooling operation or dehumidifying operation means the first cooling operation or dehumidifying operation when the cooling operation or dehumidifying operation is performed a plurality of times. Here, it is preferable that the moisture removal operation has two types of moisture removal operation modes of heating and drying or evacuation.

As shown in FIG. 4, the control device 17 includes a storage unit 17A, an output unit 17B, and a calculation unit 17D. The storage unit 17A stores the operation history including the cooling mode, the heating mode, the water removal mode, and other operation modes of the air conditioner 1, and the time information such as the operation time. The output unit 17B outputs to the air conditioner 1 (the indoor unit 3 or the outdoor unit 2 and the indoor unit 3) a command (signal) for performing the moisture removal operation. The calculation unit 17D instructs the output unit 17B to output a command based on the operation history of the storage unit 17A and the like. It is preferable that the control device 17 further includes an input unit 17C that receives a signal of the moisture removal operation mode from a remote controller or the like during the moisture removal operation of the air conditioner 1. The storage unit 17A stores the water removal operation standby period in which the water removal operation is not performed. The calculation unit 17D counts the water removal operation standby period based on time information such as a timer (not shown), and stores it in the storage unit 17A. The storage unit 17A stores conditions in the water removal operation, specifically, heat drying conditions and vacuum evacuation conditions. Here, the heating and drying conditions are a preset temperature and time. Further, as the heating and drying conditions, the holding temperature X and the holding time Y of the refrigerant pipe 21 that satisfies the following relational expression (1), the holding time Y of the refrigerant pipe 21 that satisfies the relational expression (2), and the temperature with the environmental temperature. It is preferable to store the difference Z. Details of the relational expressions (1) and (2) will be described later.
Y ≧ 4000e ^−0.11X (1)
Y ≧ 1100Z ^−1.5 (2)

The calculation unit 17D, based on the operation history of the storage unit 17A, performs air conditioning until a predetermined number of days elapses after the cooling operation or the dehumidifying operation ends, that is, until the moisture removal operation standby period reaches a predetermined value. The output unit 17B is instructed to automatically output (when the set condition (time) is reached until the predetermined value is reached) for performing the moisture removal operation of the machine 1. The predetermined number of days can be arbitrarily set within the range of the number of days not exceeding the water removal operation standby period (predetermined period). The calculation unit 17D also instructs the output unit 17B to output a command to perform the moisture removal operation of the air conditioner 1 based on the input of the moisture removal operation mode from the remote controller or the like. Here, the water removal operation standby period is 10 days in the case of the refrigerant tube 21 made of phosphorus deoxidized copper, and 60 days in the case of the refrigerant tube 21 made of oxygen-free copper. In addition, when the moisture removal operation command is output from the output unit 17B, the remote controller, or the like, the calculation unit 17D resets the counter, which is stored in the storage unit 17A and is counting the moisture removal operation standby period, to zero. When the moisture removal operation mode is not input from the remote controller or the like, the calculation unit 17D selects the moisture removal operation mode (heat drying or evacuation) in a preset mode, and the selected moisture removal operation is performed. Based on the mode, the output unit 17B is instructed to output a command to perform the moisture removal operation of the air conditioner 1.

When the signal of the moisture removal operation mode received by the input unit 17C is heating and drying, the calculation unit 17D instructs the output unit 17B to output the drive command during the normal heating operation to the outdoor unit 2 and the indoor unit 3. It is more preferable to instruct the output unit 17B to output a command to block exhaust and exhaust heat by the louver 15 or the drain pipe 16 when the heating operation is started. The arithmetic unit 17D may instruct the output unit 17B to output a drive command to the heater 11 of the indoor unit 3 when the moisture removal operation mode signal received by the input unit 17C is heating and drying.
In addition, when the signal of the moisture removal operation mode received by the input unit 17C is evacuation, the calculation unit 17D may instruct the output unit 17B to output a drive command to the decompression pump 19 of the indoor unit 3. preferable.

When the moisture removal operation mode is heating and drying, the calculation unit 17D is based on the desired temperature or the desired time for heating and drying input to the input unit 17C from the remote controller or the like during the moisture removal operation of the air conditioner 1. The holding temperature X (° C.) or the holding time Y (min) of the refrigerant pipe 21 during heating and drying that satisfies the above relational expression (1) (Y ≧ 4000e ^{−0.11X 2} ) is calculated. That is, when either the Y value or the X value of the relational expression (1) is input, the calculation unit 17D calculates and sets the heating time and the heating temperature of the heating and drying based on the relational expression (1). change. The calculation unit 17D heats and dries the indoor unit 3 (heater 11) or the outdoor unit 2 and the indoor unit 3 at the holding temperature X (° C) or the holding time Y (min) of the refrigerant pipe 21 calculated by the calculation unit 17D. The output unit 17B is instructed to do so. It should be noted that the input from the remote controller or the like may be only a heating / drying command. In that case, the command is output to the output unit 17B so that the heating / drying operation is performed by the operation of the remote controller or the like.

In the calculation unit 17D, instead of the holding temperature X (° C.) of the refrigerant pipe 21, the temperature difference Z between the environmental temperature of the environment in which the air conditioner 1 is installed during heating and drying and the holding temperature X of the refrigerant pipe 21 is used. Then, the holding temperature X or the holding time Y of the refrigerant pipe 21 may be calculated. At that time, the calculation unit 17D uses the above relational expression (2) (Y ≧ 1100Z−1.5). The ambient temperature is measured by a temperature sensor (not shown) provided in the indoor unit 3 or the like and stored in the storage unit 17A. Desired values of the temperature difference Z and the holding time Y are input by the user to the input unit 17C by a remote controller or the like and sent to the calculation unit 17D. It should be noted that the input from the remote controller or the like may be only a command for heating and drying. In that case, the calculation unit 17D outputs the holding time Y and the temperature difference Z of the refrigerant pipe 21 stored in advance in the storage unit 17A to the output unit 17B. The arithmetic unit 17D detects the end of heating and drying based on the preset temperature and time stored in the storage unit 17A, and instructs the output unit 17B to output a command to end the heating and drying. To do. In addition, the calculation unit 17D determines whether or not the elapsed time of the relational expression (1) or (2) has elapsed based on the temperature difference between the temperature of the refrigerant pipe 21 and the ambient temperature stored in the storage unit 17A. Thus, the end of heating and drying is detected, and the output unit 17B is instructed to output a command to end the heating and drying.

It is preferable that the control device 17 controls the air conditioner 1 so as to perform, in addition to the water removal operation, a display operation that notifies the user that the water removal operation is necessary after the cooling operation or the dehumidification operation is completed. Further, it is more preferable that the control device 17 controls the air conditioner 1 so that the first display operation is performed after the end of the cooling operation or the dehumidifying operation and before the lapse of a predetermined number of days. Here, the predetermined number of days is less than a predetermined period (water removal operation standby period), and in the case of the refrigerant pipe 21 made of phosphorus deoxidized copper, for example, 5 days, the refrigerant pipe 21 made of oxygen-free copper is used. In one case, it is 50 days. It is preferable that the display operation is continuously performed until the water removal operation is performed.

Based on the operation history of the storage unit 17A, the control device 17 gives an alarm to the user that the water removal operation is necessary at the time when a predetermined period has elapsed from the end of the cooling operation or the dehumidification operation. Alternatively, it is preferable that the arithmetic unit 17D instructs the output unit 17B to output a command to be displayed or lighted on the remote controller, output the command, and send the command to the remote controller or the indoor unit 3.
In the controller 17, the temperature data of the refrigerant pipe 21 measured by a temperature sensor (not shown) provided in the indoor heat exchanger 8 or the like is fed back to the calculation unit 17D during the moisture removal operation (heating and drying) to feed the refrigerant pipe. The holding temperature X or the holding time Y of 21 may be recalculated by the calculation unit 17D, and the result may be instructed and output to the output unit 17B.

<Corrosion progress control method>
A method for suppressing the progress of corrosion of an air conditioner according to the present invention will be described. The configurations of the air conditioner, the indoor unit, and the indoor heat exchanger will be described with reference to FIGS. 1 to 3.
The corrosion progress suppressing method of the present invention is a corrosion progress suppressing method for an air conditioner 1 including an indoor unit 3 having an indoor heat exchanger 8 using a refrigerant pipe 21, and a water removal operation is performed.

(Water removal operation)
In the moisture removal operation, when the air conditioner 1 is in operation, after the cooling operation or the dehumidification operation is completed, the water present inside the corrosion holes generated in the refrigerant pipe 21 is removed.
The water removal operation is performed during the period from the end of the first cooling operation or dehumidification operation to the elapse of a predetermined period (water removal operation standby period). In addition, even when the air conditioner 1 is stopped or the heating operation is performed after the water removal operation is completed, the water removal operation is performed for a predetermined period after the end of the first cooling operation or dehumidification operation thereafter. Here, the first cooling operation or dehumidifying operation means the first cooling operation or dehumidifying operation when the cooling operation or dehumidifying operation is performed a plurality of times. The water removal operation standby period is 10 days for the refrigerant pipe 21 made of phosphorus-deoxidized copper and 60 days for the refrigerant pipe 21 made of oxygen-free copper. Then, by performing the moisture removal operation within the predetermined period in this manner, the corrosion holes generated in the refrigerant pipe 21 are suppressed from proceeding to the through holes penetrating the pipe wall thickness.

The water removal operation is preferably controlled by the control device 17 provided in the indoor unit 3 and automatically performed based on preset conditions, but the remote controller of the air conditioner 1 (wired connection type and The wireless connection type: see FIG. 4), the user may manually control the implementation.

The moisture removal operation is not particularly limited as long as it is possible to remove the moisture present inside the corrosion holes generated in the refrigerant pipe 21, but the heat drying, the exhaust prevention and the exhaust prevention without the exhaust prevention and the exhaust heat prevention. Heat drying with heat inhibition or evacuation is preferable.

By performing the moisture removal operation, since moisture does not remain inside the corrosion holes, the corrosion does not proceed even if the corrosion holes are newly exposed to the corrosion environment after the moisture removal operation, and the corrosion holes generated in the refrigerant pipe 21 are It is possible to suppress the progress to the through hole penetrating the wall thickness of the pipe.

Further, the mechanism of suppressing the through hole is considered as follows. A condensation medium generated during the cooling operation or dehumidifying operation of the air conditioner dissolves a corrosive medium such as formic acid contained in the atmosphere and stays on the outer surface of the refrigerant pipe 21 to form a starting point for ant nest corrosion. It From this starting point, the corrosion progresses toward the inside of the refrigerant pipe while forming a ant-hole-shaped corrosion hole. During the progress of corrosion, water containing a corrosion medium and cuprous oxide (Cu ₂ O) that is a corrosion product are formed inside the corrosion holes. Here, the cuprous oxide fills at least a part of the inside of the corrosion hole by coating the inner surface of the corrosion hole. Before the corrosion hole penetrates the refrigerant pipe 21, the air conditioner is heated and dried, and vacuum treatment is performed to remove water from the inside of the corrosion hole, and the inner surface of the corrosion hole is covered with dried cuprous oxide. In addition, it plays a role of protecting the inner surface of the corrosion hole from the corrosion medium. The cuprous oxide existing from the entrance of the corrosion hole to the inside after removing the water is densely filled in the inside of the corrosion hole by drying (however, the inside of the corrosion hole is not only cuprous oxide but also copper oxide (CuO) as an impurity). May be slightly included). Further, the cuprous oxide once formed by the corrosion reaction can be stably present even after being dried and then contacted again with the water containing the corrosion medium. For this reason, even if the entrance portion of the existing corrosion hole of the dried refrigerant pipe 21 is again covered with the water containing the corrosion medium, the dense cuprous oxide filling the corrosion hole causes the moisture inside the corrosion hole. Does not allow him to enter. In this way, the progress of ant nest corrosion in the existing corrosion pits is prevented. After that, with respect to the newly formed ant nest corrosion, the same treatment is performed before the corrosion holes penetrate the refrigerant tube 21 to stop the ant nest corrosion from progressing and penetrate the refrigerant tube. Can be suppressed.

Corrosion holes, especially ant nest-like corrosion holes, have a very small hole shape, and therefore a driving force such as a pressure difference between the inside and outside of the hole is required to remove water that has once entered the inside of the hole.
In the case of heat drying, the pressure inside the pores rises due to volume expansion and vaporization of water inside the pores due to heating, resulting in a pressure difference inside and outside the pores. This pressure difference acts on the water inside the holes as a driving force for removal from the inside of the holes.
In the case of evacuation, the pressure on the outer surface of the refrigerant pipe decreases, so that a pressure difference occurs inside and outside the hole. This pressure difference acts on the water inside the holes as a driving force for removal from the inside of the holes.

The heating and drying is for heating and drying the refrigerant pipe 21 of the indoor heat exchanger 8. The heating and drying conditions are set with preset temperature and time. Alternatively, when the holding temperature X (° C.) and the holding time of the refrigerant pipe 21 are set to Y (min) in the heat drying, it is preferable to satisfy the following formula (1). Here, the holding temperature X of the refrigerant pipe 21 is the reached temperature of the refrigerant pipe 21 itself. Then, the reached temperature is a value measured by a sensor directly provided in the refrigerant pipe 21, or a value calculated by measuring the indoor heat exchanger 8 and calculating a preset temperature from the measured temperature. It's temperature. Since it is necessary to make the temperature of the refrigerant pipe 21 higher than the internal temperature of the indoor unit 3 in order to dry the refrigerant pipe 21, X is preferably 25 ° C. or higher in normal operation.
Y ≧ 4000e ^−0.11X (1)
The heating and drying conditions include a temperature difference Z (° C.) between the environmental temperature (° C.) of the environment in which the air conditioner 1 is installed and the holding temperature X (° C.) of the refrigerant tube 21 in the heating and drying, and the holding time Y ( min) may satisfy the above-mentioned formula (2).
Y ≧ 1100Z ^−1.5 (2)
Further, the above relational expression (1) or (2) is derived by the (heating drying condition confirmation test) described later.
When the heating and drying are performed by the heating operation of the air conditioner, the temperature of the refrigerant flowing through the indoor heat exchanger 8 is high on the upstream side (refrigerant inlet side) and low on the downstream side (refrigerant outlet side). Therefore, in order to perform the heating and drying reliably and in a short time, it is desirable to measure the holding temperature X in the refrigerant pipe on the downstream side of the indoor heat exchanger 8. Further, when the indoor unit 3 includes a plurality of indoor heat exchangers 8, it is desirable to use the value of the indoor heat exchanger 8 that has the lowest temperature as the holding temperature X. Even when the heating and drying are performed by the heater, the measurement point of the holding temperature X may be determined in the same manner as in the heating operation.

The inside of the corrosion hole generated in the refrigerant pipe 21 of the indoor heat exchanger 8 by performing heat drying at the temperature and time set as described above, or at a temperature and time satisfying the above formula (1) or the above formula (2). The water content can be removed, and the corrosion holes can be prevented from advancing to the through holes penetrating the wall thickness of the pipe. Further, it is considered that the air inside the corrosion holes can be sufficiently removed in a shorter time than the above formula (1) or the above formula (2) by performing air blowing at the same time as heating and drying. In addition, it is preferable that the air is blown by, for example, the indoor blower 10 provided inside the indoor unit 3.

The refrigerant pipe 21 forming the indoor heat exchanger 8 is covered with the aluminum fins 22, and when heated and dried, the temperature of the refrigerant pipe 21 and the aluminum fins 22 increases as a unit. Then, the temperature of the moisture retained between the aluminum fins 22 first rises, and the vaporization of this moisture begins. When the moisture between the aluminum fins 22 evaporates due to the vaporization, the temperature of the refrigerant pipe 21 and the aluminum fins 22 further rises, and the moisture in the gap between the refrigerant pipes 21 and the aluminum fins 22 and the ant nest-like corrosion are formed. Evaporation of water inside the corroded corrosion holes of the refrigerant pipe 21 becomes active. Since the refrigerant pipe 21 is covered with the aluminum fins 22, it takes time to vaporize the water. In the present invention, the water inside the corrosion holes of the refrigerant pipe 21 is also vaporized and removed. In the actual indoor heat exchanger 8, the outer diameter and wall thickness of the refrigerant tubes 21, the thickness of the aluminum fins 22, the pitch, and the number of the refrigerant tubes 21 forming the indoor heat exchanger 8 are different. Therefore, it is desirable to experimentally determine the actual time required to dry the indoor heat exchanger 8 based on the relational expression (1) or (2) at the design stage of the heat exchanger.

In addition, conventionally, in order to prevent mold that is generated inside the indoor heat exchanger 8 due to dew condensation water, a technique of blowing air into the indoor unit 3 after cooling or dehumidifying operation, or performing a blowing operation while heating is known. is there. In these techniques, the main purpose is to remove the condensed water accumulated between the aluminum fins 22 by the wind pressure, and the removal of moisture in the gap between the aluminum fins 22 and the refrigerant pipes (copper pipes) 21 is also taken into consideration. Not a thing. Even if water remains in the gap between the aluminum fin 22 and the refrigerant pipe (copper pipe) 21, the antibacterial action of copper suppresses the generation of mold in this portion. The method for suppressing corrosion of an air conditioner and the air conditioner according to the present invention is a technique for removing even water in the gap between the aluminum fin 22 and the refrigerant pipe (copper pipe) 21 and the water inside the corrosion hole formed in the copper pipe. This point is different from the above-mentioned technique for the purpose of preventing mildew.

For heating and drying, the heating operation of the air conditioner 1 or the driving of the heater 11 provided in the indoor unit 3 described in FIG. 2, or the heating operation of the air conditioner 1 and the driving of the heater 11 provided in the indoor unit 3 are performed at the same time. It is preferably carried out by carrying out. The heating operation of the air conditioner 1 or the driving of the heater 11 is controlled by the control device 17 provided in the indoor unit 3. The heating operation of the air conditioner 1 is the same as the normal heating operation described above.

As shown in FIG. 2, the heater 11 is disposed between the indoor heat exchanger 8 and the indoor blower 10 in the indoor air passage 13, but the cold air that has been heat-exchanged by the indoor heat exchanger 8 or When the warm air is blown by the indoor blower 10, it is preferably arranged at a position where it does not hinder the blowing. The number of heaters 11 is not limited to one and may be plural, but it is preferable that the number is the same as the number of indoor heat exchangers 8 or half of the number of indoor heat exchangers 8. Further, it is preferable that the heater 11 is installed at a position where concentrated heat can be dried on a portion of the indoor heat exchanger 8 where corrosion is likely to proceed. As a place where corrosion easily progresses, for example, a drain pan and the like where water is relatively present can be considered.

It is preferable that the heating and drying be performed together with the prevention of exhaust from the indoor unit 3 to the room and the prevention of exhaust heat. It is preferable that the exhaust prevention and the exhaust heat prevention are performed by the louver 15 or the drain pipe 16 provided in the indoor unit 3 shown in FIG.

The louver 15 is provided at the air outlet 18 of the casing 14, and by closing it, high heat and high humidity gas phase generated by the heating and drying operation can be prevented from being exhausted and exhausted from the air outlet 18 into the room. Further, for example, by providing an exhaust air passage (not shown) connected to the outdoor unit or the outdoor unit 2 in the indoor unit 3 and providing a blower or the like in the exhaust air passage, high heat of the indoor air passage 13 can be passed through the exhaust air passage. High humidity gas phase can be exhausted and exhausted to the outside.

The same number of drain pipes 16 as the indoor heat exchangers 8 are provided below the indoor heat exchangers 8 in the indoor air duct 13. In addition, for example, the drain pipe 16 is inclined toward the exhaust air duct side (not shown), and a blower or the like is provided in the exhaust air duct, so that the high heat of the indoor air duct 13 generated by the heating and drying operation is generated through the exhaust air duct. High humidity gas phase can be exhausted and exhausted to the outside. As a result, it is possible to prevent the high heat and high humidity vapor phase generated by the heating and drying operation from being exhausted and exhausted from the air outlet 18 into the room.

The evacuation is not particularly limited as long as the indoor air passage 13 of the indoor unit 3 can be depressurized, but it is preferable to perform the evacuation with the decompression pump 19 shown in FIG. 2 with the louver 15 closed. The control of the decompression pump 19 and the degree of decompression is preferably performed by the control device 17 provided in the indoor unit 3. Then, by performing such vacuuming, the water inside the corrosion holes generated in the refrigerant pipe 21 is removed, and the corrosion holes generated in the refrigerant pipe 21 progress to the through holes penetrating the pipe wall thickness. Is suppressed. The vapor pressure of water in the corrosion holes of the refrigerant pipe 21 is determined by the temperature of the refrigerant pipe 21. Therefore, in order to remove water by vacuuming, it is necessary to set the degree of vacuum in the indoor unit 3 to be smaller than the vapor pressure obtained from the temperature of the refrigerant pipe 21. The higher the temperature, the higher the vapor pressure, so combining vacuum evacuation with heating operation enables more effective water removal.

In the method for suppressing the progress of corrosion of an air conditioner according to the present invention, it is preferable to further perform a display operation.
<Display operation>
The display operation informs the user that the water removal operation is necessary, and the alarm is displayed or lit on the indoor unit 3 or the remote controller. If the air conditioner 1 is connected to the Internet, it may be announced by e-mail. Then, the control of the display operation is performed by the control device 17 provided in the indoor unit 3 shown in FIG.

It is preferable that the display operation is performed before the water removal operation and before a predetermined period of time has elapsed after the end of the first cooling operation or dehumidification operation. In addition, even after the water removal operation performed by the display operation is completed, when the air conditioner 1 is stopped or heated, the predetermined period of time elapses after the end of the first cooling operation or dehumidifying operation thereafter. It is preferable to carry out the display operation. Here, the first cooling operation or dehumidifying operation means the first cooling operation or dehumidifying operation when the cooling operation or dehumidifying operation is performed a plurality of times. The predetermined period is 5 days in the case of the refrigerant pipe 21 made of phosphorus deoxidized copper, 90 days in the case of the refrigerant pipe 21 made of oxygen-free copper, more preferably 60 days, and further preferably 50 days. In this way, by further performing the display operation, the moisture removal operation is reliably performed, so that the corrosion holes generated in the refrigerant pipe 21 are further suppressed from advancing to the through holes penetrating the pipe wall thickness. .

The copper pipe for an air conditioner used in the method for suppressing the progress of corrosion of an air conditioner according to the present invention has a Cu content of 99.95% or more, an oxygen content of 10 ppm or less, and the balance being unavoidable impurities. This composition includes compositions of oxygen-free copper C1020 defined by JIS H3300: 2012 and oxygen-free copper C10200 of the CDA standard. By using the copper pipe having the above composition, when water removal treatment is performed after ant nest-like corrosion occurs, cuprous oxide 40, which is a corrosion product, adheres to the inner wall surface of the corrosion hole. It prevents the corrosive liquid containing the corrosive medium from coming into contact with the copper pipe base material (Cu) inside. Therefore, even when the corrosion hole Ch is newly exposed to the ant nest-like corrosion environment, it is possible to prevent the corrosion from further progressing and prevent the corrosion hole Ch from penetrating the thickness of the copper pipe. be able to.

As the copper pipe for an air conditioner of the present invention, C1020 and C10200 can be used, but these copper pipes are high-purity pure copper having an oxygen content of 10 ppm or less and a conductivity of 101% IACS or more, and are usually vacuum. It is manufactured by using special melting and casting equipment such as melting and atmosphere melting, and strict control of raw materials and impurities. In addition, not only equipment but also advanced operation technology based on experience and know-how is required for its production. Therefore, the manufacturing cost tends to increase. Therefore, as the copper pipe for an air conditioner of the present invention, the Cu content is 99.95% or more and the oxygen content is 10 ppm or less, and P, Si, Al, Mg, Zn, Be, as unavoidable impurities, An oxygen-free copper equivalent copper tube containing up to 0.035% of one or more selected from elements such as Ca, Fe, Ni, Co, Mn, Ti, Cr, and Zr may be used. The oxygen-free copper equivalent copper tube can be manufactured at a lower cost than oxygen-free copper by utilizing an element having a greater affinity for oxygen than Cu as a deoxidizing element. The electrical conductivity of the copper tube corresponding to oxygen-free copper is preferably 90% IACS or more, and more preferably 95% IACS or more. In order to keep the conductivity within the above range, it is desirable that the contents of P, Si, Al, and Fe, which reduce the conductivity even in a small amount, be 0.005% or less. In particular, P is an element that promotes ant nest corrosion, so 0.004% or less is desirable, 0.0035% or less is more desirable, and 0.003% or less is even more desirable.

The following simulated corrosion test was conducted in order to evaluate the corrosion progress inhibiting effect of the corrosion progress inhibiting method according to the present invention in an actual air conditioner. In addition, a heating and drying condition confirmation test was conducted in order to derive the heating and drying conditions in the actual air conditioner according to the present invention. Further, a water removal operation standby period confirmation test was conducted in order to derive the water removal operation standby period in the actual air conditioner according to the present invention.

(Simulation corrosion test)
For the simulated corrosion test, the corrosion reproduction device 30 shown in FIG. 5 was used. The corrosion reproducing apparatus 30 includes a closed container 31 having an internal capacity of 2 L, a silicon stopper 34 installed on the upper portion of the closed container 31, and a sample material 33 simulating a refrigerant pipe inserted in the silicon stopper 34. .
The sealed container 31 was filled with 500 mL of the corrosive liquid 32 (an aqueous solution containing a corrosive medium), and the inside thereof was replaced with oxygen at 1 L / min for 5 min. As the test material 33, a smooth tube made of phosphorus-deoxidized copper C1220 or oxygen-free copper C1020 specified in JIS H3300: 2012 with an outer diameter of 9.52 mm, a wall thickness of 0.80 mm, and a length of 200 mm was used. . The smooth tube sealed the lower end exposed from the silicon stopper 34 to the corrosive liquid 32 side.
In order to adjust the internal environment of the closed container 31 to the humidity saturated state, the closed container 31 was installed in a constant temperature bath (test atmosphere temperature 40 ° C.). The outer surface of the pipe of the test material 33 exposed 100 mm from the corrosive liquid 32 side of the silicon stopper 34 was used as the corrosion evaluation surface.

Using the corrosion reproducing device 30 in which the test material 33 is installed, the test material 33 is subjected to a predetermined temperature cycle, specifically, moisture adhesion by cooling (assuming cooling operation), water removal by heating or vacuuming (moisture removal). A cycle operation (assuming a removal operation) and a temperature cycle in which the test atmosphere temperature was kept at 40 ° C. (assuming a stopped state) were repeatedly performed (moisture removal twice a day). The test material 33 was cooled and held in a constant temperature bath. The water was removed by taking out the test material 33 and applying hot air thereto. At this time, the temperature of the copper tube surface was 80 ° C. In this test, as shown in FIGS. 6A and 6B, water droplets containing a corrosive medium volatilized from the corrosive liquid 32 are condensed on the outer surface of the test material 33 by cooling, and ant nest corrosion occurs and progresses. In addition, the water vaporizes due to heating and the water in the corrosion holes is also removed, and the progress of ant nest corrosion is stopped. After the drying, in the next cooling cycle, the test material 33 to which the water containing the corrosive liquid 32 adheres has ant nest-like corrosion at a new location, but the corrosion does not proceed at the existing corrosion hole portion. After completion of the cycle operation, the outer surface of the pipe of the test material 33 was observed with an X-ray CT scanner (Shimadzu Corporation, model inspeXio SMX-225CTFPD), and corrosion of all corrosion holes generated in the entire circumference of the pipe at a pipe length of 10 mm was observed. The depth was measured, and the corrosion progress inhibiting effect was evaluated at the maximum corrosion depth (see FIGS. 7A and 7B). When the maximum corrosion depth was less than 0.20 mm, which is ¼ of the wall thickness, it was evaluated that the corrosion progress inhibiting effect was obtained.

A smooth tube made of phosphorus-deoxidized copper C1220 and oxygen-free copper C1020 specified in JIS H 3300: 2012 with an outer diameter of 9.52 mm, a wall thickness of 0.80 mm and a length of 200 mm is used to remove water. A test similar to the above was performed except that it was not performed, and the state of corrosion was observed in the same manner (see FIGS. 8A and 8B).

In order to confirm the effect of inhibiting the progress of corrosion by removing the water inside the corrosion holes in the actual air conditioner, the cycle operation conditions shown in Table 1 were run for 20 consecutive days. A 0.5 vol% formic acid solution was used as the corrosive liquid 32 (corrosion medium is formic acid). After the operation was completed, the maximum corrosion hole depth was measured. The results are shown in Table 1.

 

From the results of Table 1, Example No. that satisfies the requirements of the present invention for removing water. In Nos. 1 to 3, the maximum corrosion hole depth was less than 0.20 mm, and it was confirmed that there was an effect of suppressing corrosion progress. In addition, Comparative example No. which does not satisfy the requirements of the present invention in which water is not removed. In Nos. 4 and 5, the maximum corrosive hole depths are 0.80 mm and 0.29 mm, and corrosive holes penetrating the wall thickness (0.20 mm) of the copper pipe generally used for air conditioners are formed. It was

(Heating and drying condition confirmation test)
In an environment where the surface of the refrigerant pipe is condensed and ant nest-like corrosion occurs, in order to investigate the time required for heating and drying the refrigerant pipe, we simulated the environment inside the corrosion hole and conducted a test in a humidity saturated environment. It was
For the heating and drying condition confirmation test, the corrosion reproducing apparatus 30 shown in FIG. 5 was used as in the simulated corrosion test. Pure water was used as a medium corresponding to the corrosive liquid 32. As the test material 33, a smooth tube made of phosphorus-deoxidized copper C1220 was used. The bottom of the closed container 31 was heated in order to keep the internal environment of the closed container 31 at a temperature of 33 ° C. and in a humidity saturated state. Items other than the above were the same as those in the simulated corrosion test.
Shown in Table 2 after holding the test material (copper tube) 33 at 5 to 10 ° C. for 10 minutes with a temperature controller attached to the test material 33 exposed above the silicon stopper 34 (outside the closed container 31). The test material (copper tube) 33 was dried under the conditions. After drying, the dried state of the surface of the test material (copper tube) 33 was visually confirmed. Regarding a part of the sample material 33, after cooling to 5 to 10 ° C., it is taken out of the closed container 31 and the sample material (copper tube) 33 is heated by a temperature controller in an indoor environment (24 ° C.). The state of drying was visually confirmed while warming. As a result, when the test material (copper tube) 33 reached 26.6 ° C., the drying was completed, and the time required for the drying was 11.5 minutes. The results are shown in Table 2.

 

As shown in Table 2, Example No. with heating and drying. Comparative Examples Nos. 6 to 14 have no heating and drying even if they are dried in a humidity saturated environment. It was possible to obtain a dried state without condensation similar to the drying under the actual environment of 15 (indoor environment). Therefore, under the heating and drying conditions of the present invention, it is considered that not only the pipe surface of the refrigerant pipe (test material) but also the water inside the corrosion holes can be sufficiently dried in an actual environment.

In addition, from the results of Table 2, when the holding temperature of the refrigerant pipe (copper pipe) is X (° C.) and the holding time is Y (min) in the heating and drying, the heating and drying conditions satisfying the following formula (1) are required. For example, it is considered that the water inside the corrosion holes can be removed and the progress of corrosion can be suppressed well.
Y ≧ 4000e ^−0.11X (1)
Further, from the results of Table 2, the temperature difference between the environmental temperature of the environment in which the indoor unit is installed and the holding temperature of the refrigerant pipe (copper pipe) in heating and drying is X (° C) is Z (° C), and the holding time is Y. When it is set to (min), it is considered that if the heating and drying conditions satisfy the following formula (2), the water inside the corrosion holes can be removed and the progress of corrosion can be suppressed well.
Y ≧ 1100Z ^−1.5 (2)

(Water removal operation standby period confirmation test)
In order to investigate the water removal operation standby period required for suppressing the progress of corrosion, the test material (copper tube) 33 was tested for 120 minutes at 20 ° C. for 120 minutes using the corrosion reproducing apparatus 30 shown in FIG. A cycle operation was performed in which a temperature cycle of cooling (assuming water adhesion due to cooling operation) and holding at 40 ° C. for 1320 minutes (assuming a stopped state) was repeatedly performed (no water removal). After the lapse of a predetermined number of days, the maximum corrosion depth of the test material 33 was measured in the same manner as the simulated corrosion test. The results are shown in Table 3.
As the test material 33 of this test, a smooth tube made of phosphorus-deoxidized copper C1220 or oxygen-free copper C1020 with an outer diameter of 9.52 mm, a wall thickness of 0.80 mm, and a length of 200 mm was used. A 0.01 vol% formic acid solution simulating the environment was used.

 

From the results of Table 3, in the test material 33 made of phosphorus deoxidized copper, the maximum corrosion depth after 10 days was 0.19 mm and after 30 days was 0.34 mm. The sample 33 made of oxygen-free copper had a maximum corrosion depth of 0.12 mm even after 60 days.
Since the thickness of a general copper pipe used as a refrigerant pipe of an air conditioner is 0.20 mm, a water removal operation standby period is 10 days in an air conditioner using a refrigerant pipe made of phosphorus deoxidized copper C1220. If the water removal operation is set to 10 days (10 days or less) after the completion of the first cooling operation or dehumidification operation, corrosion holes that penetrate the wall thickness of the refrigerant pipe are generated. It was confirmed that it could be suppressed. In an air conditioner using a refrigerant pipe made of oxygen-free copper C1020, the water removal operation standby period is set to 60 days, that is, 60 days after the end of the first cooling operation or dehumidification operation (within 60 days). It was confirmed that the generation of corrosion holes penetrating the wall thickness of the refrigerant pipe can be suppressed by performing the water removal operation on (1).

(Heat drying effect confirmation test)
In order to investigate the effect of corrosion control over a long period of time by heating and drying, a 0.5 vol% formic acid solution (corrosion medium is formic acid) simulating an actual environment in which an air conditioner is used as the corrosive liquid 32 is used in a humidity saturated environment. The test was conducted.
In this test, the corrosion reproducing apparatus 30 shown in FIG. 5 was used as in the simulated corrosion test. As the test material 33, a smooth tube (outer diameter: 9.52 mm, wall thickness: 0.80 mm, length: 200 mm) made of oxygen-free copper C1020 was used. The test procedure is as follows.

(1) Up to 60 days after the start of the test The following [first item] and [second item] are repeated 6 times.
[First Item] The test material is held for 10 days in a cycle in which the internal environment of the closed container 31 is set to a temperature of 40 ° C. for 22 hours and a temperature of 20 ° C. for 2 hours (10 cycles).
[Second item] After 10 days, the test material 33 is taken out of the closed container 31 and subjected to a moisture removal treatment by applying hot air (the surface temperature of the test material is 80 ° C.), and then the X-ray CT scanner described above. Observe and observe.

(2) From 60 days to 120 days after the start of the test The following [third item] and [fourth item] are repeated twice for the test material 33 held for 60 days in one test.
[Third item] The test material is held for 30 days in a cycle in which the internal environment of the closed container 31 is set to a temperature of 40 ° C for 22 hours and a temperature of 20 ° C for 2 hours (30 cycles).
[Fourth item] After 30 days have passed, the test material 33 is taken out of the closed container 31 and subjected to a moisture removal treatment by applying hot air (the surface temperature of the test material is 80 ° C.), and then the X-ray CT scanner described above. Observe and observe.

Results of observation with an X-ray CT scanner in the effect confirmation test of heat drying are shown with reference to FIGS. 9A to 9D to 16A to 16D. In addition, in the test material 33, it is assumed that the first corrosion hole Ch1 (corrosion hole having the deepest corrosion depth) that is formally numbered is used as a reference for the observation. Also, since the ant nest corrosion progresses three-dimensionally, it is not possible to observe the whole image by observing only one cross section. Therefore, the [range] including the first corrosion hole Ch1 existing on the 10th day is defined, and all the corrosion holes existing within the defined range in the cross section in the pipe axis direction and the pipe axis orthogonal direction are changed to one cross section. Superposition processing was performed. In addition, here, in FIG. 9A to FIG. 9D to FIG. 16A to FIG. 16D, it is shown that all the corrosion holes Ch included in the slice images of 1000 sheets are displayed on one screen in the range of the total sample length of 10 mm. By such an overlapping process, it was possible to observe the entire image of the first corrosion hole Ch1 and other corrosion holes Ch to be observed.

FIG. 9A is a photograph of the progress state of corrosion in the refrigerant pipe of the air conditioner, which was observed once during the test period of 10 days before observation by the CT scanner. FIG. 9B is a photograph observed by the above-mentioned CT scanner in a state where the position of the corrosion hole at the observation point in FIG. 9A is cut in the longitudinal direction of the refrigerant pipe. FIG. 9C is an enlarged photograph of the position of the corrosion hole at the observation point in FIG. 9A. FIG. 9D is an enlarged photograph of the position of the corrosion hole at the observation point in FIG. 9B. 10A to 10D to 16A to 16D have the same positional relationship as in FIGS. 9A to 9D, but the test period is different.

As shown in FIGS. 9A to 9D, in the corroded state of the sample material 33 on the 10th day, the first corrosion hole Ch1 of the sample material 33 and other corrosion holes Ch are formed on the pipe surface. The depth of the first corrosion hole Ch1 at this time is 0.24 mm.
As shown in FIGS. 10A to 10D, in the corroded state of the sample material 33 on the 20th day, the first corrosion hole Ch1 of the sample material 33 and the other corrosion holes Ch are formed on the pipe surface. The depth of the first corrosion hole Ch1 at this time is 0.24 mm.
As shown in FIGS. 11A to 11D, in the corroded state of the sample material 33 on the 30th day, the first corrosion hole Ch1 of the sample material 33 and other corrosion holes Ch are formed on the pipe surface. The depth of the first corrosion hole Ch1 at this time is 0.24 mm.
As shown in FIGS. 12A to 12D, in the corroded state of the sample material 33 on the 40th day, the first corrosion hole Ch1 of the sample material 33 and other corrosion holes Ch are formed on the pipe surface. The depth of the first corrosion hole Ch1 at this time is 0.24 mm.

As shown in FIGS. 13A to 13D, in the corroded state of the sample material 33 on the 50th day, the first corrosion hole Ch1 of the sample material 33 and other corrosion holes Ch are formed on the pipe surface. The depth of the first corrosion hole Ch1 at this time is 0.24 mm.
As shown in FIGS. 14A to 14D, in the corroded state of the sample material 33 on the 60th day, the first corrosion hole Ch1 of the sample material 33 and other corrosion holes Ch are formed on the pipe surface. The depth of the first corrosion hole Ch1 at this time is 0.24 mm.
As shown in FIGS. 15A to 15D, in the corroded state of the sample material 33 on the 90th day, the first corrosion hole Ch1 of the sample material 33 and other corrosion holes Ch are formed on the pipe surface. The depth of the first corrosion hole Ch1 at this time is 0.24 mm.
As shown in FIGS. 16A to 16D, in the corroded state of the sample material 33 on the 120th day, the first corrosion hole Ch1 of the sample material 33 and other corrosion holes Ch are formed on the pipe surface. The depth of the first corrosion hole Ch1 at this time is 0.24 mm.

As described above, in the test material 33, during the test period with heating and drying, it is possible to determine that the corrosion has not progressed because the cuprous oxide 40 is provided inside the first corrosion hole Ch1. Therefore, under the heating and drying conditions of the present invention, not only the pipe surface of the refrigerant pipe (test material) but also the water inside the corrosion holes can be sufficiently dried in the actual environment, and the cuprous oxide 40 can be contained in the corrosion holes. It is considered that the provision of the element suppresses the progress of corrosion.

Although the refrigerant pipe has been described above, the present invention is also suitably applied when the refrigerant pipe connecting the outdoor unit and the indoor unit is a copper pipe. According to the operation of the air conditioner as described above, water is inevitably removed from the inside of the refrigerant pipe, and it is considered that the same effect is achieved. Further, in the above, the predetermined period is designated by the number of days, but it may be designated by the time. When a refrigerant pipe made of oxygen-free copper is used, it is preferable that the moisture content be within 1440 hours after the first cooling operation or the dehumidifying operation is completed or after the first cooling operation or the dehumidifying operation is completed after the last water removing operation. The removal operation is performed. Furthermore, the timing of the water removal operation is set to 60 days in the description, but as shown in FIGS. 15A to 15D and 16A to 16D, the refrigerant pipe 21 is penetrated during the period of 120 days or less. Since no state has occurred, if it is within 120 days, it may be set as 90 days or 100 days, for example.

Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is obvious to those skilled in the art that various changes or modifications can be conceived within the scope described in the claims, and naturally, they also belong to the technical scope of the present invention. Understood. Further, the constituent elements in the above-described embodiments may be arbitrarily combined without departing from the spirit of the invention.

This application is based on the Japanese patent application filed on Oct. 16, 2018 (Japanese Patent Application No. 2018-194942) and the Japanese patent application filed on Oct. 16, 2018 (Japanese Patent Application No. 2018-194943). The contents are hereby incorporated by reference.

1 Air Conditioner 2 Outdoor Unit 3 Indoor Unit 4 Compressor 5 Four-Way Valve 6 Outdoor Heat Exchanger 7 Expansion Valve 8 Indoor Heat Exchanger 9 Refrigerant Pipe 10 Indoor Blower 11 Heater 12 Intake Grill 13 Indoor Airway 14 Casing 15 Louver 16 Drain Pipe 17 Control device 17A Storage unit 17B Output unit 17C Input unit 17D Calculation unit 18 Air outlet 19 Decompression pump 21 Refrigerant pipe 21a Straight pipe 21b Return bend pipe 22 Aluminum fin (fin)
30 Corrosion reproducing device 31 Sealed container 32 Corrosion liquid 33 Specimen material 34 Silicon stopper 40 Cuprous oxide Ch Corrosion hole (ant nest-like corrosion hole)
CH1 1st corrosion hole (ant nest corrosion hole)

Claims (23)

1. A method for inhibiting corrosion progress of an air conditioner having an indoor unit having an indoor heat exchanger using a refrigerant tube made of phosphorus deoxidized copper, wherein during operation of the air conditioner, after completion of cooling operation or dehumidifying operation, the A water removal operation for removing water existing inside the corrosion holes generated in the refrigerant pipe is performed, and the water removal operation is performed within 10 days after the end of the cooling operation or the dehumidification operation. A method for suppressing the progress of corrosion of an air conditioner, which is characterized by the following.
2. The method for suppressing the progress of corrosion of an air conditioner according to claim 1, further comprising a display operation for notifying the user that the water removal operation is necessary before the water removal operation.
3. The method for suppressing corrosion progress of an air conditioner according to claim 2, wherein the display operation is performed within 5 days after the end of the cooling operation or the dehumidifying operation.
4. A method for suppressing the progress of corrosion of an air conditioner having an indoor unit having an indoor heat exchanger using a refrigerant pipe made of oxygen-free copper, wherein during operation of the air conditioner, after completion of a cooling operation or a dehumidifying operation, the refrigerant Performing a water removal operation for removing the water existing inside the corrosion hole generated in the pipe, and the water removal operation is performed within 60 days after the end of the cooling operation or the dehumidification operation. A method for suppressing the progress of corrosion of an air conditioner, which is characterized by:
5. The method for suppressing the progress of corrosion of an air conditioner according to claim 4, wherein a display operation for notifying the user that the water removal operation is necessary is further performed before the water removal operation.
6. The method for suppressing the progress of corrosion of an air conditioner according to claim 5, wherein the display operation is performed within 50 days after the end of the cooling operation or the dehumidifying operation.
7. The method for suppressing the progress of corrosion of an air conditioner according to claim 1, wherein the water removal operation is performed by heating and drying the refrigerant pipe.
8. The method for suppressing the progress of corrosion of an air conditioner according to claim 4, wherein the water removal operation is performed by heating and drying the refrigerant pipe.
9. 8. The air conditioner according to claim 7, wherein the heating and drying satisfy the following expression (1) when the holding temperature of the refrigerant pipe is X (° C.) and the holding time is Y (min). Corrosion progress control method.
   Y ≧ 4000e ^−0.11X (1)
10. 9. The air conditioner according to claim 8, wherein the heating and drying satisfy the following expression (1) when the holding temperature of the refrigerant pipe is X (° C.) and the holding time is Y (min). Corrosion progress control method.
    Y ≧ 4000e ^−0.11X (1)
11. Corrosion holes formed in a refrigerant pipe made of a copper pipe for an air conditioner, which has a Cu content of 99.95% or more and an oxygen content of 10 ppm or less with the balance being an unavoidable impurity used in an indoor unit of an air conditioner. A method for suppressing the progress of corrosion of an air conditioner, characterized by providing cuprous oxide on the inner wall surface of the air conditioner.
12. The method for suppressing the progress of corrosion of an air conditioner according to claim 11, wherein a water removal operation is performed to provide cuprous oxide in the corrosion holes, and the water removal operation is performed by heating and drying the refrigerant pipe. .
13. 13. The method for suppressing the progress of corrosion of an air conditioner according to claim 12, wherein the water removal operation is performed within 60 days after the completion of the cooling operation or the dehumidifying operation of the air conditioner.
14. The method for suppressing the progress of corrosion of an air conditioner according to claim 12, wherein a display operation for notifying the user that the water removal operation is necessary is further performed before the water removal operation.
15. The method for suppressing corrosion progress of an air conditioner according to claim 14, wherein the display operation is performed within 50 days after the end of the cooling operation or the dehumidifying operation of the air conditioner.
16. The method for suppressing the progress of corrosion of an air conditioner according to any one of claims 7, 8 and 10, wherein the heating and drying is performed by a heating operation of the air conditioner.
17. The method for suppressing the progress of corrosion of an air conditioner according to any one of claims 7, 8 and 10, wherein the heating and drying is performed by a heater provided in the indoor unit.
18. The method for suppressing the progress of corrosion of an air conditioner according to any one of claims 7, 8 and 10, wherein the heating and drying are performed together with the prevention of exhaust from the indoor unit to the room and the prevention of exhaust heat.
19. The method for suppressing the progress of corrosion of an air conditioner according to claim 18, wherein the exhaust prevention and the exhaust heat prevention are performed by a louver provided in the indoor unit.
20. The method for suppressing the progress of corrosion of an air conditioner according to claim 18, wherein the exhaust prevention and the exhaust heat prevention are performed by a drain pipe provided in the indoor unit.
21. The method for suppressing the progress of corrosion of an air conditioner according to any one of claims 1, 4 and 12, wherein the water removal operation is performed by vacuuming to reduce the pressure inside the indoor unit.
22. An outdoor unit, an indoor unit, and a control device are provided, the indoor unit has an indoor heat exchanger using a refrigerant pipe, and the control device is any one of claims 1, 4, and 11. The air conditioner is controlled by using the method for suppressing the progress of corrosion of the air conditioner according to claim 4.
23. A refrigerant pipe used for an indoor heat exchanger provided in an indoor unit of an air conditioner, wherein the corrosion progress suppressing method for the air conditioner according to any one of claims 1, 4 and 11 is used, A refrigerant pipe, characterized in that cuprous oxide is formed inside a corrosion hole generated in the refrigerant pipe.

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