Air conditioner, method for estimating amount of adhered salt, and program

Abstract

This air conditioner includes: a heat exchanger; a corrosion sensor for acquiring corrosion information related to the corrosion state of the heat exchanger; a humidity sensor for acquiring first humidity information related to the humidity around the heat exchanger; and a control unit communicatively connected to the corrosion sensor and the humidity sensor. The control unit is configured to acquire the corrosion information and the first humidity information by the corrosion sensor and the humidity sensor, estimate the corrosion rate of the heat exchanger on the basis of the corrosion information, and estimate the amount of salt adhered to the heat exchanger on the basis of the first humidity information and the corrosion rate.

Description

Air conditioner, method for estimating amount of adhered salt, and program

[0001] The present disclosure relates to an air conditioner, a method for estimating the amount of adhered salt, and a program.

[0002] Heat exchangers made of metal such as aluminum, for example, the heat exchanger of the outdoor unit of an air conditioner, can be corroded by corrosive substances such as salts in the atmosphere. When corrosive substances such as salts adhere to the heat exchanger, the corrosion of the heat exchanger is significantly promoted, and there is a risk of refrigerant leakage if through holes occur in the refrigerant pipes, and the life of the heat exchanger is shortened. In order to extend the life of the heat exchanger, techniques for estimating the amount of adhered salt to the heat exchanger have been studied.

[0003] Japanese Patent No. 6087269

[0004] The air conditioner described in Patent Document 1 focuses on the fact that a temperature difference occurs when the electrode is corroded, and estimates the amount of salt adhesion to the heat exchanger based on the temperature difference. In addition, there is a technique for estimating the amount of adhered salt using an ACM sensor (Atmospheric Corrosion Monitor Sensor) that generates a corrosion current according to the corrosion state of the evaluation target metal. However, there is room for improvement in terms of improving the estimation system for the amount of salt adhesion at low cost.

[0005] An object of the present disclosure is to provide an air conditioner, a method for estimating the amount of adhered salt to the heat exchanger of the air conditioner, and a program.

[0006] In order to solve the above-described problems, the present disclosure provides an air conditioner, a method for estimating the amount of adhered salt to the heat exchanger of the air conditioner, and a program.

[0007] An air conditioner according to one embodiment of the present disclosure includes a heat exchanger, a corrosion sensor for acquiring corrosion information relating to the corrosion status of the heat exchanger, a humidity sensor for acquiring first humidity information relating to the humidity around the heat exchanger, and a control unit that is communicated to the corrosion sensor and the humidity sensor. The control unit is configured to acquire corrosion information and first humidity information from the corrosion sensor and the humidity sensor, to estimate the corrosion rate of the heat exchanger based on the corrosion information, and to estimate the amount of salt adhering to the heat exchanger based on the first humidity information and the corrosion rate.

[0008] Furthermore, another embodiment of the present disclosure of a method for estimating the amount of salt adhering to a heat exchanger of an air conditioner includes: obtaining corrosion information related to the corrosion status of the heat exchanger and first humidity information related to the humidity around the heat exchanger; estimating the corrosion rate of the heat exchanger based on the corrosion information; and estimating the amount of salt adhering to the heat exchanger based on the first humidity information and the corrosion rate.

[0009] Furthermore, other embodiments of the program relating to this disclosure cause the air conditioner to execute a method for estimating the amount of attached salt.

[0010] Furthermore, other embodiments of the storage medium relating to this disclosure are non-temporary, computer-readable storage media on which a computer program is stored. The method for estimating the amount of attached salt is realized when the computer program is executed by a processor.

[0011] In this disclosure, an air conditioner, a method for estimating the amount of salt adhering to it, a program, and a storage medium can be used to estimate the amount of salt adhering to the heat exchanger of an air conditioner.

[0012] Block diagram of an example air conditioner in Embodiment 1 Flowchart of an example of a method for estimating the amount of attached salt in Embodiment 1 Schematic diagram of an example of estimating the amount of attached salt Graph showing the relationship between the amount of attached salt, relative humidity and corrosion status Schematic diagram of an example of estimating the amount of attached salt Schematic diagram of an example of estimating the surface humidity of a corrosion sensor Schematic diagram of an example of estimating the corrosion rate Schematic diagram of an example of estimating the corrosion rate Schematic diagram of an example of estimating the amount of attached salt Schematic diagram of an example of estimating the amount of attached salt Flowchart of an example of a method for estimating the amount of attached salt in Embodiment 3

[0013] <Technical Concepts> Before describing specific embodiments of the air conditioner, salt deposit estimation method, program, and storage medium relating to this disclosure, we will first explain the technical concepts described in this disclosure using an example. The air conditioner of this disclosure performs a salt deposit estimation method to estimate the amount of salt deposited on the heat exchanger of the air conditioner. The air conditioner can further determine the salt damage level based on the estimated salt deposit amount and take countermeasures to extend the life of the heat exchanger based on the determination result.

[0014] The inventors of this disclosure focused on the fact that the corrosion rate of metal products such as aluminum in salt-damaged areas is greatly influenced by the humidity near the product and the amount of salt adhering to the product, and thus developed the salt adhering amount estimation method of this disclosure. When an air conditioner performs the salt adhering amount estimation method, it acquires corrosion information related to the corrosion status of the heat exchanger to be estimated, and first humidity information related to the humidity around the heat exchanger. Based on the corrosion information, the air conditioner estimates the corrosion rate of the heat exchanger, and then estimates the amount of salt adhering to the heat exchanger based on the first humidity information and the corrosion rate. Based on the corrosion rate, the amount of salt adhering can be estimated more accurately.

[0015] Furthermore, conventional sensors that detect the amount of salt deposits generally have short lifespans or are expensive. For example, carbon steel-based ACM sensors can be used to detect the amount of salt deposits, but carbon steel corrodes rapidly in salt-damaged areas, causing the electrode film to peel off prematurely (for example, within two or three months). Patent document 1, which does not use ACM sensors, uses two dedicated thermistor sensors as temperature sensors to estimate the amount of salt deposits. One of the thermistor sensors has an electrode exposed to the outside air to withstand corrosion and is not a typical temperature sensor. Installing ACM sensors or dedicated components in this way is often difficult due to space constraints on the air conditioner.

[0016] According to the salt deposition amount estimation method of this disclosure, the amount of deposited salt can be estimated even without using an ACM sensor, for example, by using corrosion information obtained from a more common / inexpensive electrical resistance corrosion sensor (RCM sensor). Furthermore, the salt deposition amount estimation method of this disclosure can estimate the amount of deposited salt by utilizing sensors already installed in air conditioners for air conditioning and humidification functions. However, the salt deposition amount estimation method of this disclosure can also be implemented even if an ACM sensor is used as the corrosion sensor.

[0017] Each of the embodiments described below is an example of the present disclosure. The numerical values, shapes, configurations, steps, and order of steps shown in each of the following embodiments are illustrative and do not limit the present disclosure. Among the components in Embodiment 1 below, those components that are not described in the independent claim representing the highest-level concept are described as optional components.

[0018] In each of the embodiments described below, variations may be shown for certain elements, and other elements may be combined with any configuration as appropriate, with each combined configuration producing its respective effect. In each embodiment, the effects of each variation are achieved by combining the configurations of each variation.

[0019] In the following detailed descriptions, terms such as “First,” “Second,” etc., are used solely for illustrative purposes and should not be understood as expressing or implying relative importance or ranking of technical features. Features designated as “First” or “Second” express or imply that they include one or more such features.

[0020] Embodiment 1: Hereinafter, Embodiment 1 of the air conditioner, salt deposit estimation method, program, and storage medium according to the present disclosure will be described in detail with reference to the drawings as appropriate.

[0021] Figure 1 is a block diagram of an example of an air conditioner in Embodiment 1. In the embodiment of Figure 1, the air conditioner 10 includes at least one heat exchanger 11, a storage unit 12, a control unit 13, and various sensors 14. The air conditioner 10 may also include a communication unit 15 that can communicate with a server 20 and / or a terminal device 30. Through the communication unit 15 and the internet, the air conditioner 10 can perform specific functions, receive commands from users, and provide users with information about the air conditioner 10.

[0022] The following is an overview of the components of the air conditioner 10.

[0023] <Air Conditioner 10> The air conditioner 10 is a control space, for example, an interior space of a room in a home or office, which is the target of air conditioning control. The air conditioner 10 includes components such as a heat exchanger 11, a compressor, and a fan for performing air conditioning functions such as cooling and heating. The air conditioner 10 has, for example, a cooling function, a heating function, and / or an air purification function. The air conditioner 10 may also include a ventilation device that introduces outdoor air from outside the control space into the control space. The operating modes for air conditioning include at least a cooling mode and a heating mode. Furthermore, the air conditioner 10 may have operating modes such as a dehumidifying mode, a humidifying mode, a fan mode, and a ventilation mode, and these functions / operating modes can be freely combined (for example, a heating and humidifying function, a cooling and ventilation mode, etc.).

[0024] <Heat Exchanger 11> The heat exchanger 11 includes a plurality of fins and refrigerant piping through which the refrigerant flows. If the refrigerant piping corrodes to the point where the pipe walls are penetrated, the refrigerant inside may leak, potentially affecting the health and safety of the user. The air conditioner 10 can estimate the amount of salt adhering to the heat exchanger 11 or its refrigerant piping and take countermeasures to extend the life of the heat exchanger 11 according to the estimation result.

[0025] If the air conditioner 10 includes an outdoor unit and an indoor unit, and each of the outdoor and indoor units includes a heat exchanger 11, the salt deposition amount estimation method may be applied to the heat exchanger 11 of the outdoor unit, which is relatively susceptible to salt damage, or it may be applied to both heat exchangers 11. The following explanation will mainly focus on the heat exchanger 11 of the outdoor unit as the target of the salt deposition amount estimation method.

[0026] <Storage Unit 12> The storage unit 12 is a recording medium for recording various information and control programs, and may also be a memory that functions as a work area for the control unit 13. The storage unit 12 can be implemented as, for example, flash memory, RAM (Random Access Memory), ROM (Read Only Memory), other storage devices, or a combination thereof as appropriate. The storage unit 12 may store log data acquired from each sensor 14, information for estimating the amount of attached salt, standards, thresholds, comparison tables, statistical models, mathematical formulas, etc.

[0027] Furthermore, the storage unit 12 may store a computer program that causes the control unit 13 to execute the method for estimating the amount of attached salt. In other words, the storage unit 12 may be a non-temporary computer-readable storage medium on which the computer program is stored. The method for estimating the amount of attached salt is executed when the computer program is executed by the processor of the control unit 13.

[0028] <Control Unit 13> The control unit 13 of the air conditioner 10 executes the salt deposit estimation method of this disclosure. The control unit 13 is a controller that is responsible for controlling at least some of the functions of the air conditioner 10. The control unit 13 includes a general-purpose processor such as a CPU, MPU, MCU, FPGA, DSP, or ASIC that realizes predetermined functions by executing a program. The control unit 13 can realize various controls on the server 20 by calling and executing a control program stored in the storage unit 12. The control unit 13 can also cooperate with the storage unit 12 to read and write data stored in the storage unit 12. The control unit 13 is not limited to realizing predetermined functions through the cooperation of hardware and software, but may also be a hardware circuit specifically designed to realize predetermined functions.

[0029] <Sensor 14> In order to perform the air conditioning function and to estimate the amount of attached salt, the air conditioner 10 may include various sensors 14. Time-series data (i.e., log data) of the measured values ​​that each sensor 14 periodically detects and outputs can be stored in the storage unit 12. The control unit 13 may read log data for a certain period from the storage unit 12 as needed, or it may directly obtain the latest measured value from the sensor 14.

[0030] The air conditioner 10 includes a corrosion sensor 141 for acquiring corrosion information related to the corrosion status of the heat exchanger 11. The corrosion sensor 141 is positioned in the same environment as the heat exchanger 11 to be detected, and may be provided, for example, on the surface or around the heat exchanger 11.

[0031] In one example, the corrosion sensor 141 is an electrical resistance corrosion sensor (RCM sensor). The RCM sensor includes a metal sensor part, and when the thickness (cross-sectional area) of the sensor part decreases due to corrosion, the electrical resistance value output by the RCM sensor increases. Therefore, the electrical resistance value output by the RCM sensor represents the corrosion status of the heat exchanger 11. In this case, the corrosion information may include the electrical resistance value output by the corrosion sensor 141, or the remaining thickness of the corrosion sensor 141.

[0032] In another example, the corrosion sensor 141 is of a different type from the RCM sensor. For example, the corrosion sensor 141 may be an ACM sensor, a combination of a visual corrosion sensor that changes color as corrosion progresses, a camera, and image processing technology, or an ultrasonic sensor, an electromagnetic sensor, or an optical sensor. The corrosion situation can be analyzed by comparing the corrosion information with a predetermined threshold or by detecting changes in the corrosion information.

[0033] The air conditioner 10 includes a humidity sensor 142 for acquiring first humidity information related to the humidity around the heat exchanger 11. Since the humidity variation in a relatively small space is not large, the humidity sensor 142 does not need to be installed in the immediate vicinity of the heat exchanger 11. For example, if the target of the salt deposit estimation method is the heat exchanger 11 of the outdoor unit, the humidity sensor 142 may be an existing outdoor humidity sensor of the air conditioner 10.

[0034] The air conditioner 10 may include other sensors such as an indoor temperature sensor, an outdoor temperature sensor, an indoor humidity sensor, and a motion sensor. For example, as will be described later, the air conditioner 10 may further include a first temperature sensor 143 for measuring the outdoor temperature outside the controlled space, and a second temperature sensor 144 for measuring the surface temperature of the heat exchanger 11.

[0035] <Communication Unit 15> The communication unit 15 can also communicate between the air conditioner 10, the server 20, and the terminal device 30, and can, for example, send and receive Internet packets. The communication unit 15 can obtain weather information regarding the humidity at the location of the air conditioner 10 (i.e., outdoor humidity) from the server 20 or an external information source via the Internet. The control unit 13 may cooperate with the air conditioner 10 and / or the terminal device 30 via the communication unit 15 for the air conditioning control of the air conditioner 10. The communication unit 15 may communicate between the air conditioner 10, the server 20, and the terminal device 30 in accordance with standards such as Wi-Fi®, IEEE 802.2, IEEE 802.3, 3G, LTE, etc., and send and receive data. The communication unit 15 may communicate via the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication network, infrared, Bluetooth (registered trademark), etc.

[0036] As described above, the air conditioner can perform the method for estimating the amount of attached salt. However, if the server 20 or terminal device 30 is stopped and is in communication with the air conditioner 10, it may receive corrosion information and first humidity information from the air conditioner 10 and perform part or all of the method for estimating the amount of attached salt.

[0037] Server 20 is a server for managing and controlling at least one air conditioner 10, but it may be used for other purposes. For example, Server 20 may be a management server for the manufacturer of the air conditioner 10, or it may be an application server for managing related applications 36 executed on terminal device 30.

[0038] The terminal device 30 is a device related to the air conditioner 10. The terminal device 30 can communicate data with the server 20 or the air conditioner 10. In one example, the terminal device 30 is an information terminal that connects to the air conditioner 10 via the internet or the server 20. For example, the terminal device 30 may be a smartphone, mobile phone, tablet, wearable device, or computer with a dedicated related application 36 installed. In another example, the terminal device 30 is a remote controller that connects to the air conditioner 10 via infrared or Bluetooth®. For example, the terminal device 30 may be a remote controller that manages and controls only the air conditioner 10, or it may be a remote controller that can manage and control multiple types of home appliances simultaneously.

[0039] Up to this point, we have provided a general overview of the air conditioner's configuration. The air conditioner can perform a salt deposition amount estimation method to estimate the amount of salt deposited on the heat exchanger. Below, we will describe the features of the salt deposition amount estimation method, program, and storage medium according to this embodiment, using an example in which the heat exchanger of the outdoor unit is the target of the salt deposition amount estimation method.

[0040] <Method for Estimating the Amount of Adhered Salt> The method for estimating the amount of adhered salt according to this disclosure estimates the amount of salt adhering to the heat exchanger 11 of the air conditioner 10, that is, the amount of salt adhering to the heat exchanger 11. The control unit 13 may periodically perform the method for estimating the amount of adhered salt using information stored in the storage unit 12 or real-time measurements obtained by each sensor 14. For example, the control unit 13 may perform the method for estimating the amount of adhered salt once every hour, once every day, once every three days, once every seven days, once every ten days, or once every month. The period during which each sensor 14 acquires information may differ from the period during which the control unit 13 performs the method for estimating the amount of adhered salt.

[0041] Figure 2 is a flowchart of an example of a method for estimating the amount of attached salt in Embodiment 1, and Figure 3 is a schematic diagram of an example of estimating the amount of attached salt. In the examples of Figures 2 and 3, the method for estimating the amount of attached salt includes steps S110 to S130.

[0042] In the method for estimating the amount of adhering salt, first, the control unit 13 obtains corrosion information related to the corrosion state of the heat exchanger 11 and first humidity information related to the humidity around the heat exchanger 11 by means of the corrosion sensor 141 and the humidity sensor 142 (step S110). The corrosion information may include an electrical resistance value representing the corrosion state of the heat exchanger 11, the remaining wall thickness (i.e., the remaining thickness of the metal sensor part), a current value, and the like. The first humidity information may be the outdoor humidity outdoors in the control space of the air conditioner 10, or the humidity on the surface or around the heat exchanger 11. Also, the first humidity information may be relative humidity or absolute humidity. For example, the first humidity information may be the outdoor relative humidity obtained by an outdoor humidity sensor generally provided in the outdoor unit.

[0043] The control unit 13 estimates the corrosion rate of the heat exchanger based on the corrosion information (step S120). When the corrosion sensor 141 is an RCM sensor, if the corrosion rate is high, the thickness (cross-sectional area) of the sensor part decreases significantly due to corrosion, and the electrical resistance value output by the RCM sensor increases. When the corrosion sensor 141 is an ACM sensor, generally, the corrosion current output by the ACM sensor is considered to be directly proportional to the corrosion rate. That is, there is a strong correlation between the corrosion information and the corrosion rate.

[0044] Also, for different materials and installation locations of the air conditioner 10 with different salt concentrations in the atmosphere, by obtaining the correlation between specific corrosion information and the corrosion rate through corrosion experiments, a statistical model, a learned model, a mathematical formula, a comparison table, etc. (hereinafter sometimes abbreviated as "model etc." or "mathematical formula etc.") representing the completion can be obtained. In one example, a model etc. suitable for the material and installation location of the heat exchanger 11 is stored in the storage unit 12, and the control unit 13 can obtain the estimated corrosion rate by, for example, inputting the corrosion information into the model or mathematical formula etc., or by collating the comparison table with the corrosion information.

[0045] A statistical model refers to a mathematical model that embodies a series of statistical assumptions regarding the generation of sample data. Usually, a statistical model is defined as a mathematical relationship between one or more random variables and other non-random variables The statistical model used in the present disclosure is capable of time series analysis, that is, it can predict future states and future observation values through time series modeling For example, the control unit 13 may estimate the corrosion rate using a statistical model called a state space model

[0046] A learned model refers to a machine learning model that has been pre-trained on a dataset using machine learning techniques The learned model available in step S120 can estimate (predict) the corrosion rate when specific corrosion information is input

[0047] Next, the control unit 13 estimates the amount of adhered salt to the heat exchanger 11 based on the first humidity information and the corrosion rate (step S130) Similarly, for different materials and installation locations, the correlation between the corrosion rate and humidity is obtained through corrosion experiments, and the control unit 13 can estimate the amount of adhered salt based on the correlation, the acquired first humidity information, and the corrosion rate

[0048] FIG 4 is a graph showing the relationship between the amount of adhered salt, relative humidity, and corrosion status, and is an example of obtaining the correlation between the amount of adhered salt, corrosion rate, and relative humidity through a corrosion experiment The experiment was conducted in Okinawa using an ACM sensor as a corrosion sensor Generally, it is considered that the corrosion current output by the ACM sensor is directly proportional to the corrosion rate As test conditions, an ACM sensor was attached to the outdoor unit of a household air conditioner installed in a house in Okinawa, and continuous heating operation with the set temperature at 23°C was carried out for one year The output (corrosion current value) from the ACM sensor was monitored at intervals of 10 minutes, and the temperature and humidity of the outside air near the outdoor unit (by a temperature and humidity sensor) and the temperature of the ACM sensor itself (by a thermocouple) were also measured Regarding the material of the ACM sensor, the working electrode is an Al-2% Zn alloy, the counter electrode is silver, and the dimensions and configuration conform to Japanese Industrial Standard (JIS) Z2384

[0049] Figure 4 is a graph showing a portion of the log data extracted during the test period. The horizontal axis represents the relative humidity of the corrosion sensor surface, and the vertical axis represents the output of the ACM sensor on a logarithmic scale. The plots marked with ▲ (black triangles) and 〇 (white circles) were extracted at different points in time. The ▲ plots represent data extracted when rainfall accompanied by strong winds from the sea occurred after the acquisition period, while the 〇 plots represent data extracted at a later point in time. In other words, the 〇 plots are thought to indicate a higher amount of attached salt.

[0050] As can be seen from the graph in Figure 4, the corrosion rate tends to increase with increasing relative humidity (directly proportional to the corrosion current). Furthermore, comparing the data for relatively low salt content (▲ plots) and relatively high salt content (〇 plots), it can be seen that, for the same relative humidity, the corrosion rate increases as the salt content increases.

[0051] In one embodiment, the first humidity information is the outdoor absolute humidity. Based on a psychrometric chart, if any two of the three parameters—absolute humidity, relative humidity, and temperature—are known, the remaining one can be calculated. Therefore, if the first humidity information is the outdoor absolute humidity, the control unit 13 obtains the outdoor temperature and calculates the outdoor relative humidity based on the outdoor absolute humidity and outdoor temperature. Then, in step S130, the control unit 13 estimates the amount of attached salt based on the calculated relative humidity and the estimated corrosion rate. Formulas for estimating the amount of attached salt based on the corrosion rate and relative humidity can be derived experimentally or empirically.

[0052] In one embodiment, step S130 estimates the amount of salt deposited based on the surface relative humidity of the corrosion sensor 141. Figure 5 is a schematic diagram of an example of the estimation of the amount of salt deposited. If the surface relative humidity of the corrosion sensor 141 cannot be directly obtained, the control unit 13 estimates the surface relative humidity of the corrosion sensor 141 based on first humidity information. For example, if the first humidity information includes the outdoor humidity outside the control space of the air conditioner, the control unit 13 estimates the surface relative humidity of the corrosion sensor 141 as second humidity information based on the first humidity information. Then, the control unit 13 estimates the amount of salt deposited on the heat exchanger 11 based on the estimated second humidity information and the corrosion rate.

[0053] Since the saturated water vapor amount changes with temperature, the control unit 13 may first estimate the surface temperature of the corrosion sensor 141 in order to estimate the surface relative humidity of the corrosion sensor 141. Figure 6 is a schematic diagram of an example of estimating the surface humidity of the corrosion sensor.

[0054] As mentioned above, if any two of the absolute humidity, relative humidity, and temperature are known, the remaining one can be calculated. Furthermore, since the variation in absolute humidity within a relatively small space is not large, the outdoor absolute humidity can be considered as the surface absolute humidity of the corrosion sensor 141. Based on the above, the control unit 13 can estimate the surface relative humidity of the corrosion sensor 141 as second humidity information based on the outdoor absolute humidity and the surface temperature of the corrosion sensor 141.

[0055] The surface temperature of the corrosion sensor 141 can be estimated based on the outdoor temperature and the surface temperature of the heat exchanger 11. In the embodiment shown in Figure 6, the air conditioner 10 further includes a first temperature sensor 143 for measuring the outdoor temperature and a second temperature sensor 144 for measuring the surface temperature of the heat exchanger 11. The control unit 13 obtains the outdoor temperature and the surface temperature of the heat exchanger 11 from the first temperature sensor 143 and the second temperature sensor 144.

[0056] More specifically, the surface temperature of the corrosion sensor 141 is affected by the outdoor temperature, the surface temperature of the heat exchanger 11, and the positional relationship between the heat exchanger 11 and the corrosion sensor 141. For example, if the corrosion sensor 141 is located far from the heat exchanger 11, the surface temperature of the corrosion sensor 141 will be closer to the outdoor temperature than to the surface temperature of the heat exchanger 11. On the other hand, if the corrosion sensor 141 is located on or near the surface of the heat exchanger 11, the surface temperature of the corrosion sensor 141 will be close to the surface temperature of the heat exchanger 11. Formulas for estimating the surface temperature of the corrosion sensor 141 can be obtained through experiments conducted in advance. Using such formulas, the surface temperature of the corrosion sensor 141 can be estimated based on the outdoor temperature and the surface temperature of the heat exchanger 11.

[0057] Once the surface temperature of the corrosion sensor 141 is obtained, the control unit 13 estimates the surface relative humidity of the corrosion sensor 141 as second humidity information based on the outdoor absolute humidity and the surface temperature of the corrosion sensor 141.

[0058] If the heat exchanger 11 to be estimated is an indoor heat exchanger, the control unit 13 obtains the indoor temperature and indoor humidity of the controlled space using the existing indoor temperature sensor and indoor humidity sensor of the air conditioner 10. Based on the surface temperature of the heat exchanger 11, the indoor temperature, and the indoor humidity, the control unit 13 estimates the surface temperature of the corrosion sensor 141, and further estimates the surface relative humidity of the corrosion sensor 141 to estimate the amount of salt adhering to it.

[0059] Even if the corrosion sensor 141 is installed in a location other than the surface of the heat exchanger 11, the amount of adhering salt can be estimated more accurately by using the surface relative humidity of the corrosion sensor 141, as shown in Figures 5 and 6.

[0060] In one embodiment, the control unit 13 determines a constant in the formula for estimating the amount of attached salt based on humidity. For example, the control unit 13 may determine the constant in the formula for estimating the amount of attached salt based on the surface relative humidity (second humidity information) of the corrosion sensor 141. From the graph in Figure 4, it can be seen that in both the plots marked with ▲ and the plots marked with ○, the slope of relative humidity with respect to the corrosion current differs between the region of relative humidity of approximately 40% to 80% and the region of relative humidity above that. Considering that the humidity sensor has a measurement error of about 5% RH, this inflection point is thought to roughly correspond to the deliquescence humidity of NaCl, the main component of sea salt particles (76% RH). That is, when the relative humidity exceeds the deliquescence humidity of NaCl, a water film containing a high concentration of electrolyte is formed on the surface, causing the corrosion current to increase dramatically. From this view, the relationship between the surface relative humidity of the corrosion sensor 141 and the corrosion rate can be expressed by the following equation 1.

[0061]

[0062] Here, i(t) is the corrosion rate, Q(t) is the amount of salt adhering to the surface, f(Q(t)) represents the conductivity, β is a constant, RH(t) is the relative humidity, and t is a specific time point. β can be set based on humidity.

[0063] Furthermore, since conductivity increases in proportion to electrolyte concentration in regions with low salt content, we can estimate, for example, the following equation 2.

[0064]

[0065] Here, f(Q(t)) represents conductivity, α is a constant, Q(t) is the amount of attached salt, and t is a specific point in time. α can be set based on the material of the heat exchanger 11, the installation location of the air conditioner 10, the season, the temperature, etc.

[0066] Combining equations 1 and 2, we obtain the following equation 3 for estimating the amount of attached salt. The parameters in equation 3 are the same as those in equations 1 and 2.

[0067]

[0068] In one example, the control unit 13 sets β based on relative humidity. Based on the first humidity information, the control unit 13 acquires the outdoor relative humidity or the surface relative humidity of the corrosion sensor 141 (second humidity information). The control unit 13 may then set the value of β based on whether the outdoor relative humidity or surface relative humidity is above a first threshold. For example, the first threshold may be set to 70%, 75%, 80%, or 85%, taking into account experimental results or the deliquescence humidity of NaCl. In one example, if the surface relative humidity of the corrosion sensor 141 is determined to be 80% or higher, β is set to 0.2, and if the surface relative humidity of the corrosion sensor 141 is determined to be below 80%, β is set to 0.05.

[0069] In step S130, the control unit 13 can calculate the amount of adhering salt based on the estimated corrosion rate and estimated humidity, for example, the estimated corrosion rate and the estimated surface relative humidity of the corrosion sensor 141.

[0070] As a result, the control unit 13 of the air conditioner 10 completes the process of estimating the amount of salt adhering to the heat exchanger 11. The control unit 13 may periodically repeat steps S110 to S130.

[0071] In one embodiment, the air conditioner 10 has a program used to perform the above-described method for estimating the amount of attached salt. This program causes the control unit 13 of the air conditioner 10 to perform the method for estimating the amount of attached salt.

[0072] In one embodiment, the air conditioner 10 has a non-temporary, computer-readable storage medium in which a computer program is stored. The salt deposition estimation method of the present disclosure is performed when the computer program is executed by a processor. The storage medium may be the same as the storage unit 11 of the air conditioner 10, may be included in the storage unit 11, or may be a different component from the storage unit 11.

[0073] <Embodiment 2> <Estimating corrosion rate using a state-space model> In Embodiment 2, the air conditioner 10 estimates the corrosion rate using a statistical model called a state-space model. The state-space model may be, for example, a linear Gaussian state-space model. More specifically, the state-space model may be a local linear trend model.

[0074] Figure 7 is a schematic diagram illustrating different examples of corrosion rate estimation. The state-space model estimates the corrosion rate using input data that includes time-series data of corrosion information.

[0075] A state-space model is a type of time-series model described by an observation equation and a state equation. The state equation is a differential equation that describes the values ​​that change over time (called state values), and can be expressed, for example, by equation 4 below. The observation equation is an equation that defines the relationship between state values ​​and observed values, and can be expressed, for example, by equation 5 below.

[0076]

[0077]

[0078] Here, μ(t) is the current state value, μ(t-1) is the past state value, y(t) is the measurement data input as the current observed value, and w(t) is the variance σ ｗ The white noise is the noise, and v(t) is noise originating from the characteristics of the sensor or measuring instrument.

[0079] In one embodiment, a local linear trend model is used as the state-space model. The local linear trend model further incorporates a trend component into the state equation to estimate the corrosion rate. The trend component indicates the long-term trend of data changes, and the state equation can be said to be time-series data that fluctuates along with this trend component. In this embodiment, the state equation is represented by the following equation 6, and the trend equation (trend component) is represented by the following equation 7.

[0080]

[0081]

[0082] Here, μ(t) is the current state value, μ(t-1) is the past state value, δ(t) is the current trend component, δ(t-1) is the past trend component, and w(t) is the variance σ ｗ This is white noise, and ζ(t) is the variance σ ζ It is white noise.

[0083] In one example, the corrosion sensor 141 is an RCM sensor, and the corrosion information includes the electrical resistance value output by the corrosion sensor 141, or the remaining thickness of the corrosion sensor 141. The control unit 13 inputs the electrical resistance value or the remaining thickness as input data to the state-space model. In another example, the corrosion information is the electrical resistance value output by the corrosion sensor 141. The control unit 13 estimates the remaining thickness of the corrosion sensor 141 based on this electrical resistance value and inputs the estimated remaining thickness as input data to the state-space model. Generally, the electrical resistance value increases as the remaining thickness of the corrosion sensor 141 (i.e., the remaining thickness of the metal sensor part) decreases. Therefore, the remaining thickness may be estimated using a formula such that the remaining thickness is inversely proportional to the electrical resistance value. For example, the remaining thickness may be estimated using the following equation 8.

[0084]

[0085] Here, R is the electrical resistance value (measured value), ρ(T) is the electrical resistivity, l is the length of the metal sensor portion of the corrosion sensor 141, and S is the cross-sectional area of ​​the metal sensor portion of the corrosion sensor 141.

[0086] In such an example, the local linear trend model includes a trend component that represents the trend of the corrosion rate progression according to the electrical resistance value or remaining thickness. That is, the control unit 13 estimates the corrosion rate by inputting input data, which includes time-series data of the electrical resistance value or remaining thickness, into a state-space model that includes a trend component representing the electrical resistance value or remaining thickness.

[0087] An increase in the time derivative of the electrical resistance output by the corrosion sensor 141 indicates an increase in the corrosion rate; therefore, the trend component representing the trend of the corrosion rate progression in relation to the electrical resistance value is an upward trend. On the other hand, a thick remaining thickness of the corrosion sensor 141 indicates a decrease in the corrosion rate and that corrosion is not progressing; therefore, the trend component representing the trend of the corrosion rate progression in relation to the remaining thickness is a downward trend.

[0088] In another example, the corrosion sensor 141 is an ACM sensor, and the corrosion information includes the current value of the corrosion current output by the corrosion sensor 141 (corrosion current value). In this case, the control unit 13 inputs this current value as input data to the state-space model. Since an increase in the corrosion current value represents an increase in the corrosion rate, the trend component representing the trend of the change in corrosion rate in accordance with the corrosion current value is an upward trend.

[0089] In one embodiment, the memory unit 12 stores multiple state-space models. Each of the multiple state-space models corresponds to a different material of the heat exchanger 11. In step S130, the control unit 13 selects and uses a suitable state-space model based on the material of the heat exchanger 11.

[0090] In one embodiment, temperature is further considered in estimating the amount of adhering salt. Figure 8 is a schematic diagram of an example of estimating the corrosion rate, and Figure 9 is a schematic diagram of an example of estimating the amount of adhering salt. The control unit 13 acquires the surface temperature of the corrosion sensor 141. For example, the surface temperature of the corrosion sensor 141 may be estimated based on the outputs of the first temperature sensor 143 and the second temperature sensor 144 as described above, or the estimated value may be read from the storage unit 12.

[0091] In this embodiment, the corrosion sensor 141 is an RCM sensor, and the corrosion information includes the electrical resistance value output by the corrosion sensor 141. The control unit 13 estimates the remaining thickness of the corrosion sensor 141 based on the electrical resistance value and the surface temperature of the corrosion sensor 141. For example, the temperature dependence may be measured in advance in a corrosion experiment, and the formula in equation 8 may be corrected to estimate the remaining thickness using the corrected formula. The control unit 13 can estimate the corrosion rate by inputting input data, including time-series data of the remaining thickness, into a state-space model that includes a trend component representing the trend of the change in corrosion rate according to the remaining thickness.

[0092] Furthermore, the control unit 13 may estimate the amount of salt adhering to the heat exchanger 11 based on the first humidity information, the corrosion rate, and the surface temperature of the corrosion sensor 141. For example, the temperature dependence of the outdoor temperature and the surface temperature of the corrosion sensor 141 may be measured in advance in a corrosion experiment, and the formulas 4 to 7 may be corrected to estimate the amount of salt adhering.

[0093] This completes the process of estimating the corrosion rate using a state-space model and further estimating the amount of adhering salt. By using trend components related to corrosion information such as electrical resistance or remaining thickness in the state-space model, the corrosion rate can be estimated more accurately.

[0094] Furthermore, the estimations using the various parameters mentioned above can be freely combined. For example, as shown in Figure 10, the amount of corrosive salt can be estimated using the electrical resistance value of the RCM sensor, the outdoor humidity (first humidity information), and the outdoor temperature, in addition to the state-space model, the surface relative humidity of the corrosion sensor 141 (second humidity information), and the surface temperature of the corrosion sensor 141.

[0095] <Embodiment 3> <Measures to extend the lifespan of the heat exchanger> Conventionally, it is possible to predict when refrigerant will leak from the refrigerant piping using a corrosion sensor and replace the refrigerant piping and heat exchanger before the predicted leak time. However, this alone is not enough to extend the service life of the heat exchanger. In Embodiment 3, the air conditioner 10 can estimate the amount of attached salt and then take measures to extend the lifespan of the heat exchanger 11 according to the estimation result.

[0096] Figure 11 is a flowchart of an example of the method for estimating the amount of attached salt in Embodiment 3, in which the method for estimating the amount of attached salt includes steps S110 to S150. Steps S110 to S130 in Figure 11 are the same as steps S110 to S130 in Figure 2, and the details are omitted here.

[0097] In Embodiment 3, the control unit 13 of the air conditioner 10 estimates the amount of attached salt in step S130, and then determines whether the estimated amount of attached salt exceeds a second threshold (step S140). If it is determined that the estimated amount of attached salt exceeds the second threshold, the control unit 13 takes countermeasures to extend the life of the heat exchanger 11 (step S150). On the other hand, if it is determined that the amount of attached salt is less than or equal to the second threshold, the method for estimating the amount of attached salt is completed.

[0098] In one example, the countermeasures include outputting a notification or alarm to at least one of the air conditioner 10, server 20, and terminal device 30 indicating that the amount of attached salt has exceeded a second threshold. This allows for remote monitoring by the server 20 or terminal device 30. Upon receiving the notification, the user or maintenance personnel of the air conditioner 10 can take further countermeasures or repair the heat exchanger 11 to extend its service life.

[0099] In another example, the countermeasures include issuing a notice prompting the heat exchanger 11 to be washed with water. Washing the heat exchanger 11 with water will wash away at least some of the salt adhering to it, reducing the amount of salt adhering, slowing the corrosion rate, and extending the service life of the heat exchanger 11.

[0100] In another example, the countermeasure includes generating condensed water on the surface of the heat exchanger 11 to wash away the surface of the heat exchanger 11. In this way, water is automatically generated on the surface of the heat exchanger 11, resulting in the effect of washing the heat exchanger 11 with water.

[0101] For example, if the heat exchanger 11 is the heat exchanger of the outdoor unit, when the air conditioner 10 performs heating operation, the heat exchanger 11 of the outdoor unit becomes an evaporator in the refrigeration cycle, and condensed water is generated on its surface. Therefore, the countermeasure includes performing heating operation to wash away the surface of the heat exchanger 11 and generate condensed water on the surface of the heat exchanger 11. On the other hand, if the heat exchanger 11 is the heat exchanger of the indoor unit, when the air conditioner 10 performs cooling operation, the heat exchanger 11 of the indoor unit becomes an evaporator in the refrigeration cycle, and condensed water is generated on its surface. Therefore, the countermeasure includes performing cooling operation to wash away the surface of the heat exchanger 11 and generate condensed water on the surface of the heat exchanger 11.

[0102] In one embodiment, the control unit 13 determines the level of salt damage to the heat exchanger 11 by comparing the estimated amount of attached salt with a plurality of second thresholds of different sizes. The control unit 13 may take different countermeasures for different levels of salt damage. For example, if the control unit 13 determines that the salt damage level is low, it generates condensed water on the surface of the heat exchanger 11 to wash away the salt. On the other hand, if the control unit 13 determines that the salt damage level is high, it outputs an alarm to the terminal device 30 indicating that the amount of attached salt is high, and a notification prompting the heat exchanger 11 to be washed with water. Alternatively, the control unit 13 can set the operating time or set temperature of the heating or cooling operation to increase or decrease the amount of condensed water generated on the surface of the heat exchanger 11 according to the salt damage level.

[0103] This completes the countermeasures taken to extend the lifespan of the heat exchanger 11 based on the estimated amount of salt deposits. By taking the various countermeasures described above, it is possible to extend the lifespan of the heat exchanger 11, not just by estimating the amount of salt deposits on it.

[0104] (Other Embodiments) (Note) The above description of embodiments discloses the following technologies.

[0105] (Technical 1) The air conditioner includes a heat exchanger, a corrosion sensor for acquiring corrosion information related to the corrosion status of the heat exchanger, a humidity sensor for acquiring first humidity information related to the humidity around the heat exchanger, and a control unit that is communicated to the corrosion sensor and the humidity sensor. The control unit is configured to acquire the corrosion information and the first humidity information from the corrosion sensor and the humidity sensor, to estimate the corrosion rate of the heat exchanger based on the corrosion information, and to estimate the amount of salt adhering to the heat exchanger based on the first humidity information and the corrosion rate.

[0106] With such an air conditioner, the amount of salt adhering to the heat exchanger of the air conditioner can be estimated based on humidity information and corrosion rate.

[0107] (Technical 2) The air conditioner according to Technical 1, wherein the first humidity information includes the outdoor humidity outside, the control unit is further configured to estimate the surface relative humidity of the corrosion sensor as second humidity information based on the first humidity information, and to estimate the amount of salt adhering to the heat exchanger based on the second humidity information and the corrosion rate.

[0108] With this type of air conditioner, the amount of salt adhering to the heat exchanger can be estimated by considering the surface relative humidity of the corrosion sensor.

[0109] (Technical 3) The air conditioner according to Technical 2, further comprising a first temperature sensor for measuring the outdoor temperature and a second temperature sensor for measuring the surface temperature of the heat exchanger, wherein the control unit is further configured to acquire the outdoor temperature and the surface temperature of the heat exchanger using the first temperature sensor and the second temperature sensor, estimate the surface temperature of the corrosion sensor based on the outdoor temperature and the surface temperature of the heat exchanger, and estimate the surface relative humidity of the corrosion sensor as second humidity information based on the first humidity information and the surface temperature of the corrosion sensor.

[0110] With such an air conditioner, the air conditioner can estimate the surface relative humidity of a corrosion sensor using a conventional temperature sensor.

[0111] (Technology 4) The air conditioner according to any one of Technologies 1 to 3, wherein the corrosion sensor is an electrical resistance corrosion sensor (RCM sensor).

[0112] With such air conditioners, the amount of salt adhering to the heat exchanger can be estimated using RCM sensors, which are less expensive and have a longer lifespan compared to ACM sensors. Furthermore, for air conditioners that already have RCM sensors installed, the amount of salt adhering to the heat exchanger can be estimated without installing new ACM sensors.

[0113] (Technical 5) The air conditioner according to Technical 4, wherein the corrosion information includes an electrical resistance value output by the corrosion sensor or the remaining thickness of the corrosion sensor, and the control unit is further configured to estimate the corrosion rate by inputting input data including time-series data of the electrical resistance value or the remaining thickness into a state-space model which includes a trend component representing the trend of the progression of the corrosion rate according to the electrical resistance value or the remaining thickness.

[0114] With such air conditioners, the corrosion rate can be estimated using a state-space model and time-series data of corrosion information. Furthermore, if a trend component related to corrosion information, such as electrical resistance or remaining thickness, is used in the state-space model, the corrosion rate can be estimated more accurately.

[0115] (Technical 6) The air conditioner according to Technical 5, wherein the corrosion information includes an electrical resistance value output by the corrosion sensor, the control unit is further configured to obtain the surface temperature of the corrosion sensor, estimate the remaining thickness of the corrosion sensor based on the electrical resistance value and the surface temperature of the corrosion sensor, and estimate the corrosion rate by inputting input data including time-series data of the remaining thickness into a state-space model which includes a trend component representing the trend of the progression of the corrosion rate according to the remaining thickness.

[0116] With such an air conditioner, the corrosion rate can be estimated using a state-space model and time-series data of the remaining thickness of the corrosion sensor. Furthermore, the state-space model can estimate the corrosion rate by taking into account the surface temperature of the corrosion sensor.

[0117] (Technical 7) The air conditioner according to any one of Technical 1 to 6, wherein the first humidity information includes the outdoor relative humidity, and the control unit is further configured to estimate the amount of adhering salt based on the corrosion information and whether the outdoor relative humidity is above a first threshold.

[0118] With such an air conditioner, the state-space model can estimate the corrosion rate by taking into account the outdoor relative humidity.

[0119] (Technical 8) The air conditioner according to any one of Technical 1 to 6, wherein the control unit is further configured to acquire second humidity information including the surface relative humidity of the corrosion sensor, and to estimate the amount of adhering salt based on the corrosion information and whether or not the surface relative humidity of the corrosion sensor is equal to or greater than a first threshold.

[0120] With such an air conditioner, the state-space model can estimate the corrosion rate by taking into account the surface relative humidity of the corrosion sensor.

[0121] (Technical 9) The air conditioner according to any one of Technical 1 to 8, wherein the control unit is further configured to acquire the surface temperature of the corrosion sensor and to estimate the amount of salt adhering to the heat exchanger based on the first humidity information, the corrosion rate, and the surface temperature of the corrosion sensor.

[0122] With this type of air conditioner, the amount of salt adhering to the heat exchanger can be estimated by considering the surface temperature of the corrosion sensor.

[0123] (Technical 10) The air conditioner according to any one of Technical 1 to 9, wherein the control unit is further configured to take countermeasures to extend the life of the heat exchanger when it determines that the estimated amount of attached salt exceeds a second threshold.

[0124] With such an air conditioner, countermeasures to extend the lifespan of the heat exchanger can be automatically taken based on the estimated amount of accumulated salt.

[0125] (Technical 11) The air conditioner according to Technical 10, wherein the countermeasures include outputting a notification or alarm to at least one of the air conditioner, a terminal device capable of communicating with the air conditioner, and a server capable of communicating with the air conditioner, indicating that the amount of attached salt has exceeded a second threshold.

[0126] Such countermeasures allow for notification or alarm output before heat exchanger corrosion progresses and refrigerant leakage occurs.

[0127] (Technical 12) The air conditioner according to Technical 10 or 11, wherein the countermeasures include outputting a notice prompting the washing of the heat exchanger.

[0128] Such countermeasures can encourage users to reduce the amount of salt adhering to the heat exchanger by washing it with water.

[0129] (Technical 13) The air conditioner according to any one of Technical 10 to 12, wherein the countermeasures include performing a heating operation to wash the surface of the heat exchanger and generating condensed water on the surface of the heat exchanger.

[0130] With these countermeasures, the air conditioner can automatically generate water to wash away the surface of the heat exchanger.

[0131] (Technical 14) A method for estimating the amount of salt adhering to a heat exchanger of an air conditioner, comprising: obtaining corrosion information related to the corrosion status of the heat exchanger and first humidity information related to the humidity around the heat exchanger; estimating the corrosion rate of the heat exchanger based on the corrosion information; and estimating the amount of salt adhering to the heat exchanger based on the first humidity information and the corrosion rate.

[0132] (Technical 15) A program that causes an air conditioner to execute the salt deposition amount estimation method described in Technical 14.

[0133] According to such a method or program for estimating the amount of salt deposited, the amount of salt deposited on the heat exchanger of an air conditioner can be estimated based on humidity information and corrosion rate.

[0134] The above are merely specific embodiments of the Disclosure, and the scope of protection of the Disclosure is not limited thereto. The Disclosure includes, but is not limited to, the contents described in the drawings and the specific embodiments described above. Various embodiments or examples disclosed can be combined without departing from the scope or spirit of the Disclosure. Any modifications that do not depart from the functional and structural principles of the Disclosure are within the scope of the claims.

[0135] 10 Air conditioner 11 Heat exchanger 12 Memory unit 13 Control unit 14 Sensor 141 Corrosion sensor 142 Humidity sensor 143 First temperature sensor 144 Second temperature sensor 15 Communication unit 20 Server 30 Terminal device

Claims

1. An air conditioner comprising: a heat exchanger; a corrosion sensor for acquiring corrosion information relating to the corrosion status of the heat exchanger; a humidity sensor for acquiring first humidity information relating to the humidity around the heat exchanger; and a control unit connected to the corrosion sensor and the humidity sensor via communication, wherein the control unit is configured to acquire the corrosion information and the first humidity information from the corrosion sensor and the humidity sensor, estimate the corrosion rate of the heat exchanger based on the corrosion information, and estimate the amount of salt adhering to the heat exchanger based on the first humidity information and the corrosion rate.

2. The air conditioner according to claim 1, wherein the first humidity information includes outdoor humidity outside, the control unit is further configured to estimate the surface relative humidity of the corrosion sensor as second humidity information based on the first humidity information, and to estimate the amount of salt adhering to the heat exchanger based on the second humidity information and the corrosion rate.

3. The air conditioner according to claim 2, further comprising: a first temperature sensor for measuring the outdoor temperature outside; and a second temperature sensor for measuring the surface temperature of the heat exchanger, wherein the control unit is further configured to acquire the outdoor temperature and the surface temperature of the heat exchanger using the first temperature sensor and the second temperature sensor; estimate the surface temperature of the corrosion sensor based on the outdoor temperature and the surface temperature of the heat exchanger; and estimate the surface relative humidity of the corrosion sensor as the second humidity information based on the first humidity information and the surface temperature of the corrosion sensor.

4. The air conditioner according to any one of claims 1 to 3, wherein the corrosion sensor is an electrical resistance corrosion sensor (RCM sensor).

5. The air conditioner according to claim 4, wherein the corrosion information includes an electrical resistance value output by the corrosion sensor or the remaining thickness of the corrosion sensor, and the control unit is further configured to estimate the corrosion rate by inputting input data including time-series data of the electrical resistance value or the remaining thickness to a state-space model which includes a trend component representing the trend of the progression of the corrosion rate according to the electrical resistance value or the remaining thickness.

6. The air conditioner according to claim 5, wherein the corrosion information includes an electrical resistance value output by the corrosion sensor, the control unit is further configured to obtain the surface temperature of the corrosion sensor, estimate the remaining thickness of the corrosion sensor based on the electrical resistance value and the surface temperature of the corrosion sensor, and estimate the corrosion rate by inputting input data including time-series data of the remaining thickness to a state-space model which includes a trend component representing the trend of the progression of the corrosion rate according to the remaining thickness.

7. The air conditioner according to any one of claims 1 to 6, wherein the first humidity information includes the outdoor relative humidity, and the control unit is further configured to estimate the amount of adhering salt based on the corrosion information and whether the outdoor relative humidity is above a first threshold.

8. The control unit is further configured to acquire second humidity information including the surface relative humidity of the corrosion sensor, and to estimate the amount of adhering salt based on the corrosion information and whether the surface relative humidity of the corrosion sensor is equal to or greater than a first threshold, according to any one of claims 1 to 6.

9. The control unit is further configured to acquire the surface temperature of the corrosion sensor and to estimate the amount of salt adhering to the heat exchanger based on the first humidity information, the corrosion rate, and the surface temperature of the corrosion sensor, according to any one of claims 1 to 8.

10. The air conditioner according to any one of claims 1 to 9, wherein the control unit is further configured to take countermeasures to extend the life of the heat exchanger when it determines that the estimated amount of attached salt exceeds a second threshold.

11. The air conditioner according to claim 10, wherein the countermeasures include outputting a notification or alarm to at least one of the air conditioner, a terminal device capable of communicating with the air conditioner, and a server capable of communicating with the air conditioner, indicating that the amount of attached salt has exceeded a second threshold.

12. The air conditioner according to claim 10 or 11, wherein the countermeasure includes outputting a notification prompting the washing of the heat exchanger.

13. The air conditioner according to any one of claims 10 to 12, wherein the countermeasures include performing a heating operation to wash the surface of the heat exchanger and generating condensed water on the surface of the heat exchanger.

14. A method for estimating the amount of salt adhering to a heat exchanger of an air conditioner, comprising: acquiring corrosion information related to the corrosion status of the heat exchanger and first humidity information related to the humidity around the heat exchanger; estimating the corrosion rate of the heat exchanger based on the corrosion information; and estimating the amount of salt adhering to the heat exchanger based on the first humidity information and the corrosion rate.

15. A program for causing an air conditioner to execute the method for estimating the amount of attached salt described in claim 14.

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