Method for controlling corrosion of water heater and water heater

Abstract

The application discloses a water heater anti-corrosion control method and a water heater. The water heater anti-corrosion control method comprises the following steps: inputting a detection current with a current value I1 and a current output time T1 to calculate a loop resistance R t ; obtaining the conductivity of water in an inner container by using the calculated loop resistance R t ; determining the a and b values in a Tafel relationship formula according to the obtained conductivity, and calculating the overpotential of an electron anode according to the Tafel relationship formula η=a+b log I; calculating the voltage calibration value E t of the electron anode according to the formula E t =U-η according to the calculated overpotential η of the electron anode; and adjusting the output current value I t according to the calculated voltage calibration value E t . The control accuracy of the current anti-corrosion is improved, so that the anti-corrosion effect of the water heater is improved.

Description

Technical Field

[0001] This invention belongs to the field of household appliance technology, and in particular relates to a method for corrosion prevention control of water heaters and a water heater. Background Technology

[0002] Currently, water heaters are common household appliances, categorized into electric water heaters, heat pump water heaters, and solar water heaters. Electric water heaters are widely used due to their convenience. Among them, storage-type electric water heaters, equipped with a water tank, offer advantages such as large water output and stable water temperature, making them increasingly popular with families.

[0003] A typical storage-type electric water heater usually consists of a water tank, an electric heating element, and an electronic control board. To protect the inner tank from corrosion, the water tank is usually treated with anti-corrosion measures. Common methods include adding a magnesium rod or an external electronic anode. Using an external electronic anode for corrosion protection avoids the scale buildup that can occur with magnesium rods. For example, Chinese Patent Publication No. CN 110701784A discloses an inner tank structure and a storage-type electric water heater. The inner tank structure includes an electronic anode, which comprises a titanium electrode rod, a connecting screw, and a plastic shell. The titanium electrode rod and the connecting screw are connected together, and the plastic shell is injection molded and encapsulated around the titanium electrode rod and the connecting screw.

[0004] During use, the electronic anode is typically energized to generate current for corrosion prevention. In the control process, the electronic anode acts as a reference electrode, measuring the voltage between the anode and the inner tank. When the measured voltage is lower than the target voltage, the output is increased; when the measured voltage is higher than the target voltage, the output is decreased. However, in actual use, the potential of the electronic anode decreases with decreasing water conductivity, temperature, and loop current. Furthermore, differences in coating formulations and sintering quality between different electronic anode manufacturers also affect the electronic anode's potential. This potential difference is particularly noticeable at low loop currents (such as in low-temperature, low-conductivity environments and when the inner tank enamel is in excellent condition). Because the electronic anode's potential is influenced by numerous factors and its fluctuations are uncontrollable, the control precision for electronic anode corrosion prevention is poor, affecting the corrosion prevention effect of the inner tank. Therefore, the technical problem this invention aims to solve is how to design a technology to improve the control precision of electronic anode corrosion prevention to enhance the corrosion prevention effect of the water heater. Summary of the Invention

[0005] This invention provides a water heater corrosion prevention control method and water heater, which improves the control accuracy of current corrosion prevention to enhance the corrosion prevention effect of the water heater.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: In one aspect, the present invention provides a method for controlling corrosion in water heaters, comprising: First, input a detection current with a current value of I1, and the current output time is T1, to calculate the loop resistance R. t ; Using the calculated loop resistance R t The conductivity of the water in the inner tank is obtained, and the values ​​of a and b in the Tafel relation are determined based on the obtained conductivity. Then, the overpotential of the electronic anode is calculated according to the Tafel relation η = a + b log I. Based on the calculated overpotential η of the electronic anode, according to formula E t =U-η, calculate the voltage calibration value E of the electronic anode. t ; Based on the calculated voltage calibration value E t To adjust the output current value I t ; Where a represents the Tafel intercept, b represents the Tafel slope, I represents the current when the electronic anode is working, and U represents the loop voltage when the electronic anode is working.

[0007] In one embodiment of this application, the step of calculating the voltage calibration value E... t To adjust the output current value I t Specifically: When the calculated voltage calibration value E t When the voltage exceeds the voltage calibration threshold E0, the output current value is gradually reduced according to the preset current reduction range until E... t Within the range of E0 (1±c%); When the calculated voltage calibration value E t When the voltage is less than the voltage calibration threshold E0, the output current value is gradually increased according to the preset current increase range until E... t Within the range of E0 (1±c%); Among them, 15≥c≥5.

[0008] In one embodiment of this application, the calculated loop resistance R is used. t To obtain the conductivity of the water in the inner tank, the values ​​of a and b are determined based on the obtained conductivity. Then, the overpotential of the electron anode is calculated using the Tafel relation η = a + b log I. Specifically: Detect the water temperature in the water heater, and based on the detected water temperature, first obtain the loop resistance R under the corresponding water temperature condition. t The conductivity of the corresponding inner tank water is then used to determine the values ​​of a and b in the inner tank water corresponding to the conductivity under the corresponding water temperature conditions. Then, the overpotential η of the electronic anode when the current is I in the previous energizing cycle is calculated using the Tafel relation.

[0009] In one embodiment of this application, the conductivity of the inner tank water corresponding to the loop resistance Rt under the corresponding water temperature condition is first obtained, and then the values ​​of a and b in the inner tank water corresponding to the conductivity under the corresponding water temperature condition are determined, specifically as follows: According to R at different temperatures t The relationship curve between conductivity and the circuit resistance is used to calculate the loop resistance R under the measured water temperature conditions. t The corresponding conductivity; Based on the relationship curves between conductivity and values ​​of a and b at different temperatures, the circuit resistance R is calculated under the measured water temperature conditions. t The corresponding values ​​of a and b.

[0010] In one embodiment of this application, the loop resistance R under the corresponding water temperature condition is first obtained. t The conductivity of the corresponding inner tank water is then used to determine the values ​​of a and b in the inner tank water corresponding to the conductivity under the corresponding water temperature conditions. Specifically: Based on the preset loop resistance R at different temperatures t A table corresponding to conductivity is provided, and the conductivity value is determined by looking up the table based on the detected water temperature. Based on a pre-set table of conductivity and values ​​of a and b at different temperatures, the values ​​of a and b are determined by looking up the table according to the detected water temperature.

[0011] In one embodiment of this application, it further includes: At each interval T2, the electronic anode is de-energized, and the circuit voltage and output current values ​​before the de-energization are recorded. After a power outage lasting for T3 hours, a detection current of value I1 is input, and the current output time is T1, in order to calculate the loop resistance R. t ; and according to R t The values ​​of a and b in the Tafel equation are determined based on the values ​​of the water temperature in the water heater, and then the circuit voltage calibration value E is calculated when the current is I before the electron anode is de-energized. t And based on the newly obtained voltage calibration value E t Adjust the output current value.

[0012] In one embodiment of this application, when the output current value of the electronic anode is not less than a preset current threshold I0; The corrosion prevention and control method for water heaters includes: Step 1: The electronic anode is de-energized and held for a duration of T4. First, a detection current of I2 is input, with a current output time of T1. The loop voltage E1 is measured. Then, the electronic anode is de-energized again and held for a duration of T4. Next, a detection current of I3 is input, with a current output time of T1. The loop voltage E2 is measured. Calculate the potential difference ΔE between E2 and E1. t ; Step 2: After each energization of the electronic anode lasts for a duration of T5, Step 1 is executed, and according to Formula I... t =I （t-1） *(△E （t-1） / △E t Calculate the output current value for the next energizing cycle; Where, I3>I2≥I0, I （t-1） This is the output current value during the previous power-on cycle.

[0013] In one embodiment of this application, the potential difference ΔE between E2 and E1 is calculated. t Specifically: The water temperature in the water heater is detected, and the temperature calibration coefficient k is determined by looking up a table based on the detected water temperature; then, according to the formula ΔE... t = (E2-E1)k, to calculate the potential difference ΔE t .

[0014] Another embodiment of this application provides a water heater, including a controller, a water tank, and an electronic anode, wherein the electronic anode is disposed in the water tank, and the controller is configured to perform the above-described water heater anti-corrosion control method.

[0015] In one embodiment of this application, the water tank includes an outer shell and two inner tanks, and a connector is provided between the two inner tanks to form a communication channel, through which the two inner tanks are connected to each other. The electronic anode is disposed in the two inner liner and passes through the connecting channel, and the portion of the electronic anode located in the connecting channel is provided with an insulating layer.

[0016] Compared with the prior art, the advantages and positive effects of the present invention are as follows: by calculating the actual loop resistance through the output detection current during the electronic anode corrosion prevention control process, and then obtaining the voltage calibration value as the adjustment standard to control the output current value, the calculated voltage calibration value can more accurately represent the inner tank protection status, thereby achieving precise constant potential control in the water heater without adding a reference electrode, improving the control accuracy of electronic anode corrosion prevention to improve the corrosion prevention effect of the water heater and reduce the risk of hydrogen evolution. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is one of the flowcharts for the water heater corrosion prevention control method of the present invention; Figure 2 This is one of the flowcharts for the water heater corrosion prevention control method of the present invention; Figure 3 The polarization curve of the electronic anode; Figure 4 This is a schematic diagram of the structure of an embodiment of the water heater of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that in the description of this invention, the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," which indicate directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0024] Water heaters are common household appliances, with those equipped with water tanks being the most widely used. Common types of water heaters with water tanks include electric water heaters and heat pump water heaters, differing primarily in their heating methods. During use, the water tank also requires anti-corrosion treatment. Let's take an electric water heater as an example.

[0025] An electric water heater is a type of water heater that uses electricity as its primary energy source. The high-temperature heat generated after the power is turned on directly heats the water stored in the water heater to produce hot water.

[0026] Electric water heaters typically consist of a water tank, an electric heating element, and an electronic control board. The water tank has a storage cavity to store water to be heated. The electric heating element is inserted into the storage cavity of the water tank. The electronic control board is used to control the electric heating element to operate by turning the power on and off, so that the water in the tank is heated to the set temperature.

[0027] For the water tank of an electric water heater, the tank generally consists of an outer shell and an inner tank, with an insulation layer between them. The outer shell is usually made of plastic to meet the requirements of aesthetic and diverse designs; the inner tank can be made of metal or plastic, depending on the needs.

[0028] In addition, the insulation layer formed between the outer shell and the inner liner is commonly made of materials such as asbestos, sponge, foam plastic, and polyurethane foam. In conventional technology, foaming is usually used to form the insulation layer in order to achieve good insulation effect.

[0029] The water tank is also equipped with an inlet pipe and an outlet pipe. The inlet pipe is used to deliver cold water into the water storage cavity formed inside the water tank, while the hot water in the water storage cavity is output from the outlet pipe.

[0030] For electric heating components, electric heating methods such as electric heating wires, magnetic energy, or silicon tube heating can be used to heat the water stored in the water storage chamber.

[0031] The control board is used to receive detection signals from relevant sensors (such as water temperature sensors and flow sensors) and control the power supply to and from the electric heating components.

[0032] When the electric water heater is working, the electric control board controls the electric heating element to be powered on and heated. When the water temperature in the tank reaches the set value, the electric control board controls the electric heating element to be powered off.

[0033] For water tanks with metal inner liner, corrosion can easily occur inside due to water quality. Therefore, magnesium rods are installed on the water tank and inserted into the water storage cavity inside the tank.

[0034] Alternatively, an electronic anode can be used to treat the inner liner for corrosion protection. During use, the electronic anode requires a power supply.

[0035] like Figure 1 As shown, this embodiment provides a method for controlling corrosion in water heaters, including: Step 101: First, input a detection current with a current value of I1, and the current output time is T1, to calculate the loop resistance R. t ; Step 102: Using the calculated loop resistance R t The conductivity of the water in the inner tank is obtained, and the values ​​of a and b in the Tafel relation are determined based on the obtained conductivity. Then, the overpotential of the electronic anode is calculated according to the Tafel relation η = a + b log I. Step 103: Based on the calculated overpotential η of the electronic anode, according to formula E... t =U-η, calculate the voltage calibration value E of the electronic anode. t ; Step 104: Based on the calculated voltage calibration value E t To adjust the output current value I t ; Where a represents the Tafel intercept, b represents the Tafel slope, I represents the current when the electronic anode is working, and U represents the loop voltage when the electronic anode is working.

[0036] Specifically, during the process of applying current-based corrosion protection to a water heater, a detection current with a value of I1 can be briefly output before the cathodic protection current is output, in order to calculate the circuit resistance R. t Based on the calculated loop resistance R t The conductivity of the water in the inner tank can be obtained, and then the values ​​of a and b in the Tafel relation can be determined based on the obtained conductivity. The overpotential of the electron anode can be calculated according to the Tafel relation η = a + b log I. Finally, the voltage calibration value E can be calculated. t .

[0037] Thus, according to the voltage calibration value E t It can more precisely adjust the power supply current to the electronic anode, improve the control accuracy of current corrosion prevention, and thus improve the corrosion prevention effect of the water heater.

[0038] By calculating the actual loop resistance through the output detection current during the current corrosion prevention control process, and then obtaining the voltage calibration value as the adjustment standard to control the output current value, precise constant potential control can be achieved in the water heater without adding a reference electrode, thereby improving the control accuracy of current corrosion prevention and improving the corrosion prevention effect of the water heater.

[0039] In one embodiment, the step of adjusting the voltage calibration value E based on the calculated voltage calibration value... t To adjust the output current value I t Specifically: When the calculated voltage calibration value E t When the voltage exceeds the voltage calibration threshold E0, the output current value is gradually reduced according to the preset current reduction range until E... t Within the range of E0 (1±c%); When the calculated voltage calibration value E t When the voltage is less than the voltage calibration threshold E0, the output current value is gradually increased according to the preset current increase range until E... t Within the range of E0 (1±c%); Among them, 15≥c≥5.

[0040] Specifically, in the actual control process, for the calculated voltage calibration value E t Compared with a preset voltage calibration threshold E0, at the voltage calibration value E t If the voltage calibration threshold E0 is exceeded within a preset range, then the voltage calibration value E will be used. t This corresponds to reducing the output current value.

[0041] Conversely, at the voltage calibration value E t If the voltage falls below or exceeds the preset range of the voltage calibration threshold E0, then the voltage calibration value E is used. t This corresponds to increasing the output current value.

[0042] During the adjustment process, the current will be adjusted according to the preset increase or decrease range until the voltage calibration value E is adjusted. t Within the range of E0 (1±c%).

[0043] Therefore, through the above logic, the output current of the electronic anode of the water heater can be automatically controlled to ensure that the inner tank in the water tank is always at a suitable protection potential (E0), thus achieving constant potential control of the inner tank even in the absence of a reference electrode.

[0044] In another embodiment, the calculated loop resistance R is used. t To obtain the conductivity of the water in the inner tank, the values ​​of a and b are determined based on the obtained conductivity. Then, the overpotential of the electron anode is calculated using the Tafel relation η = a + b log I. Specifically: Detect the water temperature in the water heater, and based on the detected water temperature, first obtain the loop resistance R under the corresponding water temperature condition. t The conductivity of the corresponding inner tank water is then used to determine the values ​​of a and b in the inner tank water corresponding to the conductivity under the corresponding water temperature conditions. Then, the overpotential η of the electronic anode when the current is I in the previous energizing cycle is calculated using the Tafel relation.

[0045] Specifically, the Tafel relation η = a + b log I is used when an electrochemical reaction occurs at the electron anode. In this equation, η represents the overpotential of the electron anode, which is the increase in potential after the electron anode is energized compared to when it is not energized; a represents the Tafel intercept, the magnitude of which is related to factors such as the properties of the electrode material, the state of the electrode surface, the composition of the solution, and the temperature; b represents the Tafel slope, which is a constant mainly related to temperature; and I represents the current density at the surface of the electron anode.

[0046] Thus, during the control process, the loop resistance R is calculated. t Then, the conductivity of the water in the inner tank is accurately obtained based on the detected water temperature, so that the conductivity can be closer to the conductivity corresponding to the water temperature in the inner tank.

[0047] Similarly, under the corresponding water temperature conditions, the corresponding values ​​of a and b are accurately determined based on the obtained conductivity.

[0048] For different water temperature conditions, the loop resistance R tThe relationship between conductivity and the conductivity of the water in the inner tank, as well as the relationship between conductivity and values ​​a and b, can be obtained through experiments at the factory, and the relevant information obtained can be stored in the controller of the water heater. Here, we will not limit or elaborate on the specific relationship.

[0049] In one embodiment, the conductivity of the inner tank water corresponding to the loop resistance Rt under the corresponding water temperature condition is first obtained, and then the values ​​of a and b in the inner tank water corresponding to the conductivity under the corresponding water temperature condition are determined, specifically as follows: According to R at different temperatures t The relationship curve between conductivity and the circuit resistance is used to calculate the loop resistance R under the measured water temperature conditions. t The corresponding conductivity; Based on the relationship curves between conductivity and values ​​of a and b at different temperatures, the circuit resistance R is calculated under the measured water temperature conditions. t The corresponding values ​​of a and b.

[0050] Specifically, in the entire DC circuit of the inner tank protected by the output current of the electronic anode, the circuit resistance is mainly affected by the reaction resistance of the electronic anode. The circuit resistance value can be approximated as the reaction resistance of the electronic anode. In fresh water, the reaction resistance of the electronic anode is mainly affected by the temperature and conductivity of the water under a specific current. That is to say, by measuring the circuit resistance under I1, the conductivity of the solution at a certain temperature can be determined.

[0051] With the electronic anode fixed and the solution environment relatively stable, the two Tafel constants, a and b, of the electronic anode are also essentially fixed. In other words, after measuring the temperature and conductivity of the outlet water, the values ​​of a and b under this environment can be further determined, thereby establishing the loop resistance R at a specific temperature. t The relationship between the electronic anode and the Tafel constants a and b is then established. The overpotential value η of the electronic anode can then be calculated. Therefore, at the factory stage, the values ​​of a and b corresponding to specific electronic anodes in the embodiment at different water temperatures and conductivity levels can be measured. Based on the correspondence between temperature, conductivity, and the values ​​of a and b, the temperature and loop resistance R can be measured in the embodiment. t To determine the a and b values ​​of the electronic anode.

[0052] The conductivity-resistance curve, as well as the conductivity-values ​​a and b curve at different temperatures, are stored in the built-in memory of the water heater's controller. During actual use, the Tafel constants a and b are determined based on the tank temperature and the circuit resistance Rt, and then the overpotential is calculated using η = a + blogI. Subsequently, the voltage calibration value E between the inner tank and the electronic anode is further calculated. t =U-η; through E t The value represents the real-time protection status of the inner liner.

[0053] For example, in practical applications, the E0 value can be fixed at 0.9V (the suitable potential for the inner liner). t When E > 0.9V, the output current decreases; when E t When the voltage is less than 0.9V, the current increases and the output increases.

[0054] In another embodiment, the loop resistance R under the corresponding water temperature condition is first obtained. t The conductivity of the corresponding inner tank water is then used to determine the values ​​of a and b in the inner tank water corresponding to the conductivity under the corresponding water temperature conditions. Specifically: Based on the preset loop resistance R at different temperatures t A table corresponding to conductivity is provided, and the conductivity value is determined by looking up the table based on the detected water temperature. Based on a pre-set table of conductivity and values ​​of a and b at different temperatures, the values ​​of a and b are determined by looking up the table according to the detected water temperature.

[0055] Specifically, with the electron anode fixed and the solution environment relatively stable, the two Tafel constants, a and b, are also essentially fixed. As mentioned above, at the factory stage, the values ​​of a and b corresponding to different temperature conditions can be calculated by heating water to different temperatures, thus obtaining a table of conductivity versus resistance.

[0056] A table showing the correlation between conductivity and resistance is stored in the built-in memory of the water heater's controller. During actual use, the Tafel constants a and b are determined by looking up the table based on the tank temperature. Then, the overpotential is calculated using η = a + blogI. Finally, the voltage calibration value E between the inner tank and the electronic anode is calculated. t =U-η; through E t The value represents the real-time protection status of the inner liner.

[0057] In one embodiment, the water heater corrosion prevention control method further includes: at every interval T2, the electronic anode is de-energized, and the circuit voltage and output current values ​​before the de-energization are recorded; After a power outage lasting for T3 hours, a detection current of value I1 is input, and the current output time is T1, in order to calculate the loop resistance R. t ; and according to R t The values ​​of a and b in the Tafel equation are determined based on the values ​​of the water temperature in the water heater, and then the circuit voltage calibration value E is calculated when the current is I before the electron anode is de-energized. t And based on the newly obtained voltage calibration value E t Adjust the output current value.

[0058] Specifically, during the operation of the water heater, the water temperature and quality inside the heater will constantly change. In order to dynamically adjust the protective current output, the electronic anode will be de-energized every T2 time interval during the current anti-corrosion protection process. At this time, the circuit voltage and output current value before the power-off are recorded.

[0059] After the electron anode is de-energized for a certain period of time, the loop resistance R is re-established. t The detection involves inputting a current value of I1 and detecting the current output for a time period of T1, in order to calculate the loop resistance R. t Then, based on the newly calculated loop resistance R... t The voltage calibration value E is calculated based on the measured water temperature. t The output current value I is adjusted by comparing its magnitude with the target voltage E0. t .

[0060] In another embodiment of this application, during the use of the water heater, as the ceramic layer on the inner tank ages and peels off, the output current value I will decrease. t Continuing to increase. (Reference) Figure 3 As shown, when the current of the electronic anode exceeds the set value, the resistance of the electronic anode will rapidly drop to a certain value and then rapidly rise again. In order to further improve the control accuracy of current corrosion prevention, when the output current value is not less than the preset current threshold I0; The corrosion prevention and control method for water heaters includes: Step 201: After the electronic anode is de-energized and remains de-energized for a duration of T4, a detection current of I2 is first input, with a current output time of T1, and the loop voltage E1 is measured. Then, the electronic anode is de-energized again and remains de-energized for a duration of T4. Next, a detection current of I3 is input, with a current output time of T1, and the loop voltage E2 is measured. Calculate the potential difference ΔE between E2 and E1. t ; Step 202: After each energization of the electronic anode lasts for a duration of T5, step 1 is executed, and according to formula I... t =I （t-1） *(△E （t-1） / △E t Calculate the output current value for the next energizing cycle; Where I3>I2≥I0. （t-1） This represents the output current value during the current energizing cycle. I3 and I2 are in the low resistance region.

[0061] Specifically, when the output current exceeds the current threshold I0, i.e., during current regulation outside the Tafel region, the electron anode is first de-energized. Then, different detection currents are intermittently input to the electron anode, thereby detecting the loop voltages E1 and E2 from the two detections and calculating the potential difference ΔE. t .

[0062] When the input current value of the electronic anode exceeds the current threshold I0 during operation, step 1 is executed after each energization lasting for a duration of T5. In this way, ΔE can be obtained from the two consecutive inputs. （t-1） and △E t According to Formula I t =I （t-1） *(△E （t-1） / △E t ) Calculate the output current value in the next energizing cycle.

[0063] When the output current exceeds the current threshold I0, constant potential control can no longer be performed. At this time, the resistance of the electronic anode is low, while the resistance of the inner liner is relatively high. The resistance of the inner liner is related to the condition of the enamel. After temperature calibration, the state of the inner liner enamel layer can be characterized by the change in loop resistance within this range. In this way, without a reference electrode, compared to existing technologies that only set different constant voltage or constant current outputs based on temperature, or adjust the current output based on the measured voltage between the electronic anode and the inner liner, or the loop resistance, the actual effect is greatly affected by the environment and cannot reflect the true state of the inner liner. The above-mentioned technical solution of this application utilizes the low resistance region to minimize the influence of the anode resistance (i.e., the environment) on the loop resistance, and can more closely reflect the state of the inner liner.

[0064] In another embodiment, due to the different water temperatures in the inner tank of the water heater, the resistance of the inner tank changes. To achieve more precise control, the potential difference ΔE between E2 and E1 is calculated. t Specifically: The water temperature in the water heater is detected, and the temperature calibration coefficient k is determined by looking up a table based on the detected water temperature; then, according to the formula ΔE... t = (E2-E1)k, to calculate the potential difference ΔE t .

[0065] Specifically, at the factory stage, the circuit voltage can be measured in the laboratory beforehand based on different water temperatures in the inner tank. For example, under identical conditions, the circuit voltage values ​​at water temperatures ranging from 5 degrees to 75 degrees Celsius can be measured. After multiplying all values ​​by k, the circuit voltage value at 75 degrees Celsius can be calibrated; that is, k is 1 at 75 degrees Celsius. In this way, the temperature calibration coefficient k corresponding to different temperatures can be obtained.

[0066] The pressure difference ratio after temperature calibration is used to characterize the condition of the inner enamel and adjust the output size. This method is more precise than the ordinary loop resistance feedback scheme and is more conducive to providing more accurate current corrosion protection for inner enamel layers that have been damaged.

[0067] Based on the above technical solutions, an example is given.

[0068] First, the polarization curves of the electron anode are measured at different temperatures (e.g., 5-75 degrees Celsius, with a 5-degree gradient) and different conductivities (e.g., 100-2000 μs / cm, with a 100-degree gradient). From the polarization curves, a current value (e.g., 1 mA) is obtained. This current value is within the Tafel region of the polarization curves measured under various conditions. At the same time, the low resistance range is found, which is also the low current range of the polarization curves measured under all conditions (15-22 mA in this case). The Tafel constants a and b are recorded at each temperature and conductivity.

[0069] Under different temperature gradients, the anode resistance of the electron anode in freshwater with different conductivities was measured at the aforementioned measured current (1mA). The corresponding Tafel constant values ​​for each temperature and anode resistance were entered into the controller.

[0070] The system outputs a 1mA current for 10 minutes initially, followed by a 10-second power-off (the purpose of the power-off is to eliminate the influence of the 10-minute power-on on subsequent measurements; a 10-second power-off is the minimum time. If the power-off time is delayed, the power-on time needs to be extended to ensure the protection effect, i.e., the power-on / power-off time ratio should be greater than 60).

[0071] After a power outage of 10 seconds, a 1mA current is output for 1 second (the time is consistent with the step time of the scanning polarization curve). The Tafel constant is measured, and the potential correction value η is calculated.

[0072] Determine the magnitude of the corrected potential value relative to 0.9V, and adjust the output current for the next cycle (the current adjustment can be based on the measured value being far from 0.9V, increasing the current change, and being close to 0.9V, decreasing the current change; for example, within the range of 0.9V ± 0.2V, adjust the current in steps of 0.05mA each time, and beyond this range, adjust the current in steps of 0.1mA each time).

[0073] By operating in a loop according to the above logic, the correction voltage between the electronic anode and the inner liner is kept around 0.9V for most of the time.

[0074] As the enamel layer of the water heater's inner tank gradually fails, the required protection current gradually increases. Once it exceeds a certain value (e.g., 15mA), the current and voltage no longer follow the Tafel formula. Therefore, it is impossible to accurately calibrate the voltage between the electronic anode and the inner tank, and measuring the voltage between the electronic anode and the inner tank becomes meaningless.

[0075] When the output current exceeds 15mA, the anode resistance drops rapidly. Using the low resistance range, the circuit resistance is measured. At this time, the change in the inner tank resistance is easier to measure. This scheme selects the voltage difference (or resistance difference) in the low resistance range, which is more conducive to measuring the effect of the change in the inner tank resistance on the circuit resistance. Approximately according to the relationship that the protection current and the inner tank resistance are reciprocals, that is, the factor by which the resistance decreases is equal to the factor by which the protection current increases, we get the protection current = protection current of the previous cycle × (voltage difference measured in the previous cycle / voltage difference measured in this cycle).

[0076] Since the resistance of the inner tank is mainly affected by temperature, it is necessary to calibrate the voltage difference (or resistance difference) measured at different temperatures. The implementation plan is to measure the linear polarization resistance of the inner tank in 700μs / cm water at different temperature gradients in the range of 5-75℃, with 5 degrees as a gradient, and obtain the correction coefficient k at each temperature gradient (taking the test result at 75 degrees as k=1), and enter it into the controller.

[0077] After each voltage difference measurement, it needs to be multiplied by a temperature calibration factor k before calculation. The above current control logic is only suitable for situations where the current exceeds the Tafel region.

[0078] In some cases, the low resistance ranges measured in different environments differ significantly (without overlap). When the current exceeds the Tafel zone, select the starting value of the low resistance range with the largest current and measure the loop voltage at that value. Although the obtained voltage still mainly reflects the change in anode resistance, the proportion of inner tank resistance in the loop resistance is significantly increased at this time, which affects the loop resistance to a certain extent. The protection current output can be adjusted according to this loop resistance or voltage.

[0079] The specific implementation plan is as follows: Protection current = Previous cycle protection current × (Previous cycle circuit voltage / Current cycle circuit voltage) × k × Variable coefficient, where k is the temperature correction coefficient measured in the above plan, and the variable coefficient is obtained based on extensive testing or experience accumulation. It varies for each product model. For example, if the circuit voltage of a certain product decreases by 0.9 times, and the current needs to increase by 1.2 times to ensure good protection of the inner liner, then the variable coefficient is 1.1. For other models, the current needs to increase by 1.5 times to ensure good protection of the inner liner, then the variable coefficient is 1.36. The coefficient is determined to ensure that the inner liner is well protected in most cases.

[0080] In another embodiment of this application, a water heater is also provided, including a controller, a water tank, and an electronic anode, wherein the electronic anode is disposed in the water tank, and the controller is configured to perform the above-described water heater anti-corrosion control method.

[0081] Furthermore, such as Figure 4As shown, the water tank includes an outer shell and two inner tanks 1. A connector 11 is provided between the two inner tanks 1, and the connector 11 forms a communication channel, through which the two inner tanks 1 are connected to each other. The electronic anode 2 is disposed in the two inner liner 11 and passes through the connecting channel, and the portion of the electronic anode 2 located in the connecting channel is provided with an insulating layer 21.

[0082] Specifically, in order to improve the accuracy of detection and reduce the influence of the connector 11 on the electronic anode 2, an insulating layer 21 is provided on the electronic anode 2, which isolates the electronic anode 2 from the connector 11.

[0083] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed by the present invention.

Claims

1. A method for controlling corrosion in water heaters, characterized in that, include: First, input a detection current with a current value of I1, and the current output time is T1, to calculate the loop resistance R. t ; Using the calculated loop resistance R t The conductivity of the water in the inner tank is obtained, and the values ​​of a and b in the Tafel relation are determined based on the obtained conductivity. Then, the overpotential of the electronic anode is calculated according to the Tafel relation η = a + b log I. Based on the calculated overpotential η of the electronic anode, according to formula E t =U-η, calculate the voltage calibration value E of the electronic anode. t ; Based on the calculated voltage calibration value E t To adjust the output current value I t ; Where a represents the Tafel intercept, b represents the Tafel slope, I represents the current when the electronic anode is working, and U represents the loop voltage when the electronic anode is working.

2. The water heater corrosion prevention control method according to claim 1, characterized in that, The voltage calibration value E calculated t To adjust the output current value I t Specifically: When the calculated voltage calibration value E t When the voltage exceeds the voltage calibration threshold E0, the output current value is gradually reduced according to the preset current reduction range until E... t Within the range of E0 (1±c%); When the calculated voltage calibration value E t When the voltage is less than the voltage calibration threshold E0, the output current value is gradually increased according to the preset current increase range until E... t Within the range of E0 (1±c%); Among them, 15≥c≥5.

3. The water heater corrosion prevention control method according to claim 1 or 2, characterized in that, Using the calculated loop resistance R t To obtain the conductivity of the water in the inner tank, the values ​​of a and b are determined based on the obtained conductivity. Then, the overpotential of the electron anode is calculated using the Tafel relation η = a + b log I. Specifically: Detect the water temperature in the water heater, and based on the detected water temperature, first obtain the loop resistance R under the corresponding water temperature condition. t The conductivity of the corresponding inner tank water is then used to determine the values ​​of a and b in the inner tank water corresponding to the conductivity under the corresponding water temperature conditions. Then, the overpotential η of the electronic anode when the current is I in the previous energizing cycle is calculated using the Tafel relation.

4. The water heater corrosion prevention control method according to claim 3, characterized in that, First, obtain the conductivity of the inner tank water corresponding to the loop resistance Rt under the corresponding water temperature condition. Then, determine the values ​​of a and b in the inner tank water corresponding to the conductivity under the corresponding water temperature condition. Specifically: According to R at different temperatures t The relationship curve between conductivity and the circuit resistance is used to calculate the loop resistance R under the measured water temperature conditions. t The corresponding conductivity; Based on the relationship curves between conductivity and values ​​of a and b at different temperatures, the circuit resistance R is calculated under the measured water temperature conditions. t The corresponding values ​​of a and b.

5. The water heater corrosion prevention control method according to claim 3, characterized in that, First, obtain the loop resistance R under the corresponding water temperature condition. t The conductivity of the corresponding inner tank water is then used to determine the values ​​of a and b in the inner tank water corresponding to the conductivity under the corresponding water temperature conditions. Specifically: Based on the preset loop resistance R at different temperatures t A table corresponding to conductivity is provided, and the conductivity value is determined by looking up the table based on the detected water temperature. Based on a pre-set table of conductivity and values ​​of a and b at different temperatures, the values ​​of a and b are determined by looking up the table according to the detected water temperature.

6. The water heater corrosion prevention control method according to claim 3, characterized in that, Also includes: At each interval T2, the electronic anode is de-energized, and the circuit voltage and output current values ​​before the de-energization are recorded. After a power outage lasting for T3 hours, a detection current of value I1 is input, and the current output time is T1, in order to calculate the loop resistance R. t ; and according to R t The values ​​of a and b in the Tafel equation are determined based on the values ​​of the water temperature in the water heater, and then the circuit voltage calibration value E is calculated when the current is I before the electronic anode is de-energized. t And based on the newly obtained voltage calibration value E t Adjust the output current value.

7. The water heater corrosion prevention control method according to claim 1, characterized in that, When the output current value of the electronic anode is not less than the preset current threshold I0; The corrosion prevention and control method for the water heater includes: Step 1: The electronic anode is de-energized and held for a duration of T4. First, a detection current of I2 is input, with a current output time of T1. The loop voltage E1 is measured. Then, the electronic anode is de-energized again and held for a duration of T4. Next, a detection current of I3 is input, with a current output time of T1. The loop voltage E2 is measured. Calculate the potential difference ΔE between E2 and E1. t ; Step 2: After each energization of the electronic anode lasts for a duration of T5, Step 1 is executed, and according to Formula I... t =I （t-1） *(△E （t-1） / △E t Calculate the output current value for the next energizing cycle; Where, I3>I2≥I0, I （t-1） This is the output current value during the previous power-on cycle.

8. The water heater corrosion prevention control method according to claim 7, characterized in that, Calculate the potential difference ΔE between E2 and E1. t Specifically: The water temperature in the water heater is detected, and the temperature calibration coefficient k is determined by looking up a table based on the detected water temperature; then, according to the formula ΔE... t = (E2-E1)*k, to calculate the potential difference ΔE t .

9. A water heater, comprising a controller, a water tank, and an electronic anode, wherein the electronic anode is disposed in the water tank, characterized in that, The controller is configured to perform the water heater corrosion prevention control method as described in any one of claims 1-7.

10. The water heater according to claim 9, characterized in that, The water tank includes an outer shell and two inner tanks. A connector is provided between the two inner tanks to form a communication channel, through which the two inner tanks are connected to each other. The electronic anode is disposed in the two inner liner and passes through the connecting channel, and the portion of the electronic anode located in the connecting channel is provided with an insulating layer.

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