Water heater and corrosion prevention design method therefor

Abstract

A water heater and a corrosion prevention design method therefor. The water heater comprises: an inner tank, which comprises a metal tank body and a first insulating layer covering the inner wall of the metal tank body; a metal component, which is disposed in the inner tank and is electrically connected to the metal tank body; and a corrosion prevention assembly, comprising: an electronic anode, which extends into the inner tank, and a direct-current power source module, which comprises a positive electrode electrically connected to the electronic anode and a negative electrode electrically connected to the metal tank body, and is configured to apply a weak-current voltage between the metal tank body and the electronic anode, wherein the total area of an exposed metal surface of the metal component that is in direct contact with water in the inner tank is less than or equal to 0.5 m2. Since the direct-current power source module applies a weak-current voltage between the metal tank body and the electronic anode and between the metal component and the electronic anode, corrosion prevention requirements of the inner tank and the metal component can be met, thereby reducing the risk of hydrogen evolution explosion, reducing the potential safety hazard of electric leakage of the corrosion prevention assembly, and reducing the difficulty of an electronic control design of the water heater.

Description

Water heater and anti-corrosion design method thereof

[0001] This application claims priority to the Chinese patent application filed on January 15, 2024, with application number 202410060201.4 and invention name “A water heater and its anti-corrosion design method”, the content of which should be understood as incorporated into this application by reference. Technical Field

[0002] This article relates to liner anti-corrosion technology, especially a water heater and its anti-corrosion design method. Background Art

[0003] Water heaters are common household appliances used to provide hot water. However, because the inner tank of a water heater is exposed to high temperatures and humidity for long periods of time, it is prone to corrosion, which shortens the lifespan of the water heater. To prevent corrosion, traditional water heaters typically use electronic anode protection technology.

[0004] Electronic anode is a technology that suppresses liner corrosion by applying an external current to the anode to maintain an anodic protection potential. Traditional electronic anodes usually use titanium rods as carriers and are coated with metal oxides as anode materials.

[0005] The traditional electronic anode protects the surface of the enamel tank, which has a smaller exposed area that needs to be inhibited from corrosion, and requires lower protection current and protection voltage. The protection current is usually only 22.5mA / m 2 , the protection voltage is usually only 2-3.8V, and the electronic anode can achieve control and protection effects with weak electricity.

[0006] However, in order to improve heating efficiency and increase application scenarios, water heaters use metal electric heaters, metal coils and other components. These metal components have a large exposed area, which will increase the protection current and protection voltage of the electronic anode, thereby bringing the risk of hydrogen evolution, the difficulty of weak current to meet protection requirements, the safety hazard of leakage of strong current, and the difficulty of electronic control design.

[0007] Summary of the Invention

[0008] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0009] The present invention provides a water heater, comprising:

[0010] The liner comprises a metal tank body and a first insulating layer covering an inner wall of the metal tank body;

[0011] a metal component disposed in the inner container and electrically connected to the metal can body; and

[0012] Corrosion-resistant components, including:

[0013] an electronic anode extending into the inner container; and

[0014] a DC power supply module, comprising a positive electrode electrically connected to the electronic anode and a negative electrode electrically connected to the metal can body, and configured to apply a weak voltage between the metal can body and the electronic anode;

[0015] The total area of ​​the exposed metal surface of the metal parts that is in direct contact with the water in the inner tank is less than or equal to 0.5m 2 .

[0016] In an exemplary embodiment, the metal component includes a first metal component and / or a second metal component;

[0017] The first metal component has the exposed metal surface;

[0018] The metal surface of the second metal component is subjected to insulation treatment to form a second insulation layer, and the second insulation layer can separate the metal surface of the second metal component from the water in the inner container.

[0019] In an exemplary embodiment, the insulation treatment of the metal surface of the second metal component includes:

[0020] Coating insulating paint on the metal surface, coating rubber on the metal surface, coating plastic on the metal surface, applying anti-corrosion paint on the metal surface, oxidizing the metal surface, passivating the metal surface or laminating insulating material on the metal surface.

[0021] In an illustrative embodiment, the output current of the DC power supply module is less than or equal to an output current upper limit, and the output current upper limit is calculated using the following formula:

[0022] Where:

[0023] I is the upper limit of output current;

[0024] I0 is the protection current density of the inner tank;

[0025] A0 is the area of ​​the inner wall of the metal tank covered by the first insulation layer;

[0026] I i is the protection current density of the exposed metal surface of the i-th first metal component;

[0027] A i is the area of ​​the exposed metal surface of the i-th first metal component that is in direct contact with the water in the liner;

[0028] n is the number of first metal parts;

[0029] J i is the protection current density of the metal surface of the i-th second metal component covered by the second insulating layer;

[0030] a i is the area of ​​the metal surface of the i-th second metal component covered by the second insulating layer;

[0031] N is the number of second metal parts.

[0032] In an exemplary embodiment, the protective current density I0 of the inner liner is the maximum value of the self-corrosion current density of the inner liner in aqueous solution;

[0033] The protection current density I of the i-th first metal component i is the maximum value of the self-corrosion current density of the exposed metal surface of the i-th first metal component in the aqueous solution;

[0034] The protection current density J of the i-th second metal component i is the maximum value of the self-corrosion current density of the metal surface of the i-th second metal component covered by the second insulating layer in aqueous solution;

[0035] The temperature of the aqueous solution is within the temperature range designed for use of the inner liner, and the conductivity of the aqueous solution is 400-2000 μS / cm.

[0036] In an illustrative embodiment, the output voltage of the DC power supply module is less than or equal to an output voltage upper limit, and the output voltage upper limit is calculated using the following formula:

[0037] Where:

[0038] E is the upper limit of output voltage;

[0039] I is the upper limit of output current;

[0040] R0 is the polarization resistance of the electronic anode;

[0041] R shui is the resistance of the water in the inner tank;

[0042] R i is the cathode polarization resistance of the i-th first metal component;

[0043] n is the number of first metal parts;

[0044] r i is the cathode polarization resistance of the i-th second metal component;

[0045] N is the number of second metal parts.

[0046] In an illustrative embodiment, the polarization resistance R0 of the electronic anode is the slope of the polarization curve of the electronic anode in aqueous solution at the corrosion potential;

[0047] Cathodic polarization resistance R of the i-th first metal component i is the slope of the polarization curve of the i-th first metal component in aqueous solution at the corrosion potential;

[0048] Cathodic polarization resistance r of the i-th second metal component i is the slope of the polarization curve of the i-th second metal component in aqueous solution at the corrosion potential;

[0049] The temperature of the aqueous solution is within the temperature range designed for use of the inner liner, and the conductivity of the aqueous solution is 400-2000 μS / cm.

[0050] In an exemplary embodiment, the inner container is constructed as a cylindrical can-shaped structure, and the resistance of the water in the inner container is R shui Use the following formula to calculate:

[0051] Where:

[0052] R shui is the resistance of the water in the tank;

[0053] ρ is the density of water in the liner;

[0054] H is the height of the liner;

[0055] D is the diameter of the inner liner.

[0056] In an illustrative embodiment, the output current of the DC power module is less than or equal to 200 mA, and the output voltage of the DC power module is less than or equal to 4 V.

[0057] In an illustrative embodiment, the upper limit of the output current is greater than 200 mA, and a plurality of the anti-corrosion components are provided.

[0058] The present application also provides an anti-corrosion design method for a water heater, the water heater comprising an inner tank and a metal component disposed within the inner tank, the inner tank comprising a metal tank body electrically connected to the metal component and a first insulating layer covering an inner wall of the metal tank body, the anti-corrosion design method comprising:

[0059] The total area of ​​exposed metal surfaces of metal parts in direct contact with the water in the tank is greater than 0.5m 2, the exposed metal surface of at least a portion of the metal parts is insulated so that the total area of ​​the exposed metal surface of the metal parts directly in contact with the water in the inner tank is less than or equal to 0.5m 2 .

[0060] In an illustrative embodiment, the anti-corrosion design method further includes:

[0061] The total area of ​​exposed metal surfaces of metal parts in direct contact with the water in the tank is greater than 0.5m 2 The exposed metal surface of at least a portion of the metal component is insulated and covered with a second insulating layer so that the total area of ​​the exposed metal surface of the metal component directly in contact with the water in the inner tank is less than or equal to 0.5m 2 .

[0062] In an exemplary embodiment, the total area of ​​the exposed metal surface of the metal component that is in direct contact with the water in the inner tank is less than or equal to 0.5m 2 , and the metal component only includes a first metal component with an exposed metal surface, the output current upper limit is determined according to the protection current density of the inner tank, the area of ​​the inner wall of the metal tank body covered by the first insulating layer, the protection current density of the exposed metal surface of each first metal component, and the area of ​​the exposed metal surface of each first metal component directly in contact with the water in the inner tank, and the output current of the DC power supply module is set to be less than or equal to the output current upper limit.

[0063] In an illustrative embodiment, the anti-corrosion design method further includes:

[0064] The total area of ​​exposed metal surfaces of metal parts in direct contact with the water in the tank is less than or equal to 0.5m 2 , and the metal parts only include a first metal part with an exposed metal surface, the output voltage upper limit is determined according to the output current upper limit, the polarization resistance of the electronic anode, the resistance of the water in the inner tank and the cathode polarization resistance of each first metal part, and the output voltage of the DC power supply module is set to be less than or equal to the output voltage upper limit.

[0065] In an illustrative embodiment, the anti-corrosion design method further includes:

[0066] After insulating the exposed metal surface of at least a portion of the metal component, the metal component includes a first metal component having the exposed metal surface and a second metal component having the metal surface subjected to the insulation treatment;

[0067] Determine an output current upper limit based on the protection current density of the inner tank, the area of ​​the inner wall of the metal tank body covered by the first insulating layer, the protection current density of the exposed metal surface of each first metal component, the area of ​​the exposed metal surface of each first metal component directly in contact with the water in the inner tank, the protection current density of the metal surface of each second metal component covered by the second insulating layer, and the area of ​​the metal surface of each second metal component covered by the second insulating layer, and set the output current of the DC power supply module to be less than or equal to the output current upper limit;

[0068] The output voltage upper limit is determined based on the output current upper limit, the polarization resistance of the electronic anode, the resistance of the water in the inner tank, the cathode polarization resistance of each first metal component, and the cathode polarization resistance of each second metal component, and the output voltage of the DC power supply module is set to be less than or equal to the output voltage upper limit.

[0069] In the technical solution of the present application, when water is placed in the inner tank, the water is conductive due to the impurities dissolved in the water, and the inner tank, the electronic anode, and the metal parts are all in contact with the water. The DC power supply module applies a positive voltage to the electronic anode and a negative voltage to the metal tank body and the metal parts. A loop is formed between the electronic anode, the metal parts, the metal tank body, the water, and the DC power supply module. The current output from the positive electrode of the DC power supply module flows through the electronic anode and the water to reach the metal parts and the metal tank body, and finally flows back to the negative electrode of the DC power supply module. In this process, the DC power supply module outputs electrons to the metal tank body and the metal parts serving as the cathode. These electrons are provided to substances in the water that can react chemically with the metal tank body and the metal parts to undergo electrochemical reactions, thereby preventing the metal tank body and the metal parts from being corroded.

[0070] Since the first insulating layer covers the inner wall of the metal tank, and the total area of ​​the exposed metal surface of the metal parts directly in contact with the water in the inner tank is less than or equal to 0.5m 2 In this way, the total area of ​​the exposed metal surface in direct contact with the water in the inner tank is small. The DC power supply module can meet the anti-corrosion requirements of the inner tank and metal parts by loading a weak voltage between the metal tank body and the electronic anode and between the metal parts and the electrode anode, thereby reducing the risk of hydrogen evolution explosion, reducing the safety hazard of leakage of anti-corrosion components, and also reducing the difficulty of the electrical control design of the water heater.

[0071] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. Other advantages of the present application can be realized and obtained by the solutions described in the description and the drawings.

[0072] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description.

[0073] Summary of the Figures

[0074] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0075] FIG1 is a schematic diagram of the structure of a water heater according to an embodiment of the present application;

[0076] FIG2 is a schematic diagram of measurement points of the inner liner in an embodiment of the present application.

[0077] Details

[0078] This application describes multiple embodiments, but this description is exemplary rather than restrictive, and it will be apparent to those skilled in the art that there may be more embodiments and implementations within the scope of the embodiments described herein. Although many possible feature combinations are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element in any other embodiment, or may replace any other feature or element in any other embodiment.

[0079] The present application includes and contemplates combinations of features and elements known to those of ordinary skill in the art. The embodiments, features, and elements disclosed in this application may also be combined with any conventional features or elements to form a unique inventive solution. Any features or elements of any embodiment may also be combined with features or elements from other inventive solutions to form another unique inventive solution. Therefore, it should be understood that any feature shown and / or discussed in this application may be implemented individually or in any appropriate combination. Therefore, except for the limitations made according to the appended claims and their equivalents, the embodiments are not subject to other limitations. In addition, various modifications and changes may be made within the scope of protection of the appended claims.

[0080] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps in the specific order described. As will be understood by those skilled in the art, other orders of steps are also possible. Therefore, the specific order of the steps set forth in the specification should not be interpreted as a limitation to the claims. In addition, the claims for the method and / or process should not be limited to performing their steps in the order written, and those skilled in the art can readily understand that these orders can be changed and still remain within the spirit and scope of the embodiments of the present application.

[0081] As shown in FIG1 , FIG1 shows the structure of a water heater 100 in an embodiment of the present application. The water heater 100 includes an inner tank 1 , a water inlet pipe 4 , a water outlet pipe 5 , a metal component 3 and an anti-corrosion component 2 .

[0082] The inner tank 1 is used to hold water, which can be tap water. The inner tank 1 includes a metal tank body 11, a first insulating layer and a joint 12. The metal tank body 11 is the skeleton structure of the inner tank 1. The metal tank body 11 is made of metal, which can be iron, an iron alloy, copper or a copper alloy. The metal tank body 11 is made of, for example, welded steel plates, which can be carbon steel plates or stainless steel plates. The metal tank body 11 can be constructed in a cylindrical, capsule-shaped, box-shaped or spherical shape. The inner wall of the metal tank body 11 is provided with a first insulating layer. The first insulating layer covers the inner wall of the metal tank body 11. The first insulating layer is made of an insulating material, which can be ceramic, glass, plastic, rubber, silicone, etc. In this embodiment, the first insulating layer is an enamel layer, which is an insulating layer formed by melting and solidifying an inorganic glass material on the inner wall of the metal tank body 11. The first insulating layer separates the water in the inner tank 1 from the metal tank body 11, making it difficult for the water in the inner tank 1 to corrode the metal tank body 11. The metal tank body 11 is provided with a through-hole, and the connector 12 is inserted through the through-hole and connected to the metal tank body 11. The connector 12 can be made of metal and electrically conductive with the metal tank body 11. The connector 12 can be welded to the metal tank body 11. The connector 12 can be configured as a cylindrical structure, with one end of the connector 12 located inside the metal tank body 11 and the other end located outside the metal tank body 11. The end of the connector 12 facing the inside of the metal tank body 11 can be threaded, which can be internal or external. The metal tank body 11 can be provided with multiple through-holes, each with a connector 12. The connectors 12 can be installed on the sidewall of the metal tank body 11. The multiple connectors 12 can include an inlet connector 121 and an outlet connector 122. The height of the inlet connector 121 can be lower than that of the outlet connector 122.

[0083] The water inlet pipe 4 and the water outlet pipe 5 are both arranged in the inner tank 1. The water inlet pipe 4 can be arranged below the water outlet pipe 5. One end of the water inlet pipe 4 is connected to the water inlet joint 121, and the other end of the water inlet pipe 4 extends to the top of the inner tank 1. One end of the water outlet pipe 5 is connected to the water outlet joint 122, and the other end of the water outlet pipe 5 extends to the bottom of the inner tank 1. The water inlet pipe 4 is configured to inject water into the inner tank 1, and the water outlet pipe 5 is configured to discharge the water in the inner tank 1. The end of the water inlet joint 121 facing outside the inner tank 1 is configured to be connected to an external tap water supply pipeline, and the end of the water outlet joint 122 facing outside the inner tank 1 is configured to be connected to an external hot water supply pipeline.

[0084] The metal component 3 is made of metal material, and the metal can be iron, iron alloy, copper or copper alloy. The metal component 3 is arranged in the inner liner 1 and is connected to the joint 12 of the inner liner 1. The metal component 3 is fixed to the metal tank body 11 through the joint 12. The joint 12 electrically connects the metal component 3 and the metal tank body 11. The metal component 3 and the joint 12 can be threaded or welded. The number of metal components 3 can be one or more. The metal component 3 includes a heat exchanger and an electric heater. The heat exchanger includes a heat exchange tube. The heat exchange tube can be a copper tube or a steel tube. The heat exchange tube can be constructed as a coil, and the coil can be a tubular structure constructed as a spiral. The joint 12 can also include a heat exchange joint 124 and an electric heating joint 123. Two heat exchange joints 124 can be provided, and the two heat exchange joints 124 are respectively connected to the opposite ends of the coil. A high-temperature refrigerant is input into one end of the heat exchange tube. When the refrigerant flows through the heat exchange tube, it exchanges heat with the water in the inner tank 1, thereby heating the water in the inner tank 1. The electric heater is installed on the electric heating joint 123. The electric heater is configured to convert electrical energy into thermal energy, thereby heating the water in the inner tank 1. The electric heater may include a metal outer cover and a heating wire. The metal outer cover may be a tubular outer cover, or a stainless steel outer cover. The heating wire is insulated from the metal outer cover and arranged in the metal outer cover, wherein the metal outer cover and the metal tank body 11 are electrically conductive, and the heating wire is configured to be connected to an external power source to achieve heating. A plurality of electric heaters may be provided, and the plurality of electric heaters are respectively connected to a plurality of electric heating joints 123. The total area of ​​the exposed metal surface of the metal component 3 that is in direct contact with the water in the inner tank 1 is less than or equal to 0.5m 2 .

[0085] The anti-corrosion component 2 includes an electronic anode 21 and a DC power supply module 22. The electronic anode 21 is a conductor. The shape of the electronic anode 21 is not limited and can be a rod, ring, sphere or ring. In this embodiment, the electronic anode 21 is constructed in a straight strip shape, one end of the electronic anode 21 is fixed to the top of the inner liner 1 and is not in direct contact with the metal can body 11 of the inner liner 1. The metal can body 11 of the inner liner 1 and the electronic anode 21 can be separated by an insulating member, and the insulating member can be constructed as a sleeve structure, and the insulating member is sleeved on the end of the electronic anode 21 close to the top of the inner liner 1. The electronic anode 21 can be set on the central axis of the inner liner 1. The electronic anode 21 can be made of corrosion-resistant metal.

[0086] The DC power module 22 includes a positive electrode and a negative electrode. The DC power module 22 can be located outside the inner liner 1. The positive electrode of the DC power module 22 is electrically connected to the electronic anode 21 via a wire. The negative electrode of the DC power module 22 is electrically connected to the metal can body 11 of the inner liner 1 via a wire. The positive electrode of the DC power module 22 outputs a positive voltage, and the negative electrode of the DC power module 22 outputs a negative voltage. The voltage output by the DC power module 22 is a weak voltage. This weak voltage is a DC voltage less than or equal to 36V.

[0087] When water is contained within the inner tank 1, the water is conductive due to dissolved impurities. Simultaneously, the inner tank 1, the electronic anode 21, and the metal component 3 are all in contact with the water. The DC power module 22 applies a positive voltage to the electronic anode 21 and a negative voltage to the metal tank body 11 and the metal component 3. This forms a circuit between the electronic anode 21, the metal component 3, the metal tank body 11, the water, and the DC power module 22. The current output from the positive electrode of the DC power module 22 flows through the electronic anode 21 and the water, reaching the metal component 3, the connector 12, and the metal tank body 11, before returning to the negative electrode of the DC power module 22. During this process, the DC power module 22 outputs electrons to the metal tank body 11, the connector 12, and the metal component 3, which act as cathodes. These electrons are supplied to substances in the water that react chemically with the metal tank body 11, the connector 12, and the metal component 3, causing an electrochemical reaction, thereby preventing corrosion of the metal tank body 11, the connector 12, and the metal component 3.

[0088] Since the first insulating layer covers the inner wall of the metal tank body 11, and the total area of ​​the exposed metal surface of the metal component 3 that is in direct contact with the water in the inner tank 1 is less than or equal to 0.5m 2 In this way, the total area of ​​the exposed metal surface in direct contact with the water in the inner tank 1 is small, and the DC power supply module 22 can meet the anti-corrosion requirements of the inner tank 1 and the metal component 3 by loading a weak voltage between the metal tank body 11 and the electronic anode 21 and between the metal component 3 and the electrode anode, thereby reducing the risk of hydrogen evolution explosion, reducing the safety hazard of leakage of the anti-corrosion component 2, and also reducing the difficulty of the electrical control design of the water heater 100.

[0089] In an exemplary embodiment, the metal component 3 includes only a first metal component 31. The first metal component 31 has an exposed metal surface that is in direct contact with the water in the inner container 1. One or more first metal components 31 may be provided. The total exposed metal surface area of ​​all first metal components 31 is less than or equal to 0.5 m 2 .

[0090] Since the metal tank body 11 is electrically connected to the first metal component 31, the metal tank body 11 is electrically connected to the negative pole of the DC power module 22, and the electronic anode 21 is electrically connected to the positive pole of the DC power module 22, the DC power module 22 can load a negative voltage on the metal tank body 11 and the first metal component 31, and load a positive voltage on the electronic anode 21, which can prevent the metal tank body 11 and the first metal tank body 11 from being corroded by water.

[0091] The DC power module 22 is configured with an output current upper limit. The output current of the DC power module 22 is less than or equal to the output current upper limit. The output current upper limit is calculated according to the following formula:

[0092] Where:

[0093] I is the upper limit of output current, in A;

[0094] I0 is the protection current density of the inner tank 1, the unit is A / m 2 ;

[0095] A0 is the area of ​​the inner wall of the metal can 11 covered by the first insulating layer, in m 2 ;

[0096] I i is the protection current density of the i-th first metal component 31, in A / m 2 ;

[0097] A i is the area of ​​the exposed metal surface of the i-th first metal component 31 that is in direct contact with the water in the inner tank 1, in m 2 ;

[0098] n is the number of the first metal parts 31 .

[0099] The output voltage of the DC power supply module 22 is less than or equal to the output voltage upper limit, which is calculated according to the following formula:

[0100] Where:

[0101] I is the upper limit of output current, in A;

[0102] R0 is the polarization resistance of the electronic anode 21, in Ω;

[0103] R shui is the resistance of water in the inner tank 1, in Ω;

[0104] R i is the cathode polarization resistance of the i-th first metal component 31, in Ω;

[0105] n is the number of the first metal parts 31 .

[0106] In this way, when the current output by the DC power supply module 22 is less than or equal to the output current upper limit, and the voltage output by the DC power supply module 22 is less than or equal to the output voltage upper limit, the current output by the DC power supply module 22 mainly provides a protective current for the metal tank body 11, the joint 12 and the first metal component 31, so that the metal tank body 11, the joint 12 and the first metal component 31 are not corroded, and water is not electrolyzed to produce hydrogen, which can prevent the occurrence of hydrogen evolution explosion.

[0107] This example also proposes a verification test:

[0108] The protection current density of liner 1 is 12mA / m 2 The area of ​​the inner wall of the metal tank 11 covered by the first insulating layer is 1.85m 2 The first metal component 31 is an electric heater, and the protection current density of the first metal component 31 is 70mA / m 2 The area of ​​the exposed metal surface of the first metal component 31 that is in direct contact with the water in the inner tank 1 is 0.025m 2 At 20°C, when the resistivity of water in the inner tank 1 is 0.055Ω·m, it can be calculated that the upper limit of the output current is 23.95mA and the upper limit of the output voltage is 2.8V.

[0109] When the DC power supply module 22 outputs current according to the output current upper limit value and the output voltage upper limit value, the protection potential is measured at five positions on the outer wall of the inner tank 1. The test points are shown in Figure 2 and meet the protection potential requirements, that is, the protection potential range is -850 to -1100mV.

[0110] Table 1 Test results of protective potential (vs. SCE) of liner 1

[0111] In an exemplary embodiment, the metal component 3 includes a first metal component 31 and a second metal component. The first metal component 31 has an exposed metal surface that is in direct contact with the water in the inner container 1. One or more first metal components 31 may be provided. The total exposed metal surface area of ​​all first metal components 31 is less than or equal to 0.5 m 2 .

[0112] The metal surface of the second metal component 32 undergoes an insulation treatment to form a second insulating layer. Methods for insulating the metal surface of the second metal component 32 include applying an insulating varnish, applying rubber, applying plastic, applying an anti-corrosion coating, oxidizing the metal surface, passivating the metal surface, or applying an insulating material to the metal surface. The second insulating layer can be a layer of insulating varnish, plastic, or anti-corrosion coating applied to the metal surface of the second metal component 32. Alternatively, the second insulating layer can be a layer of insulating material adhered to the metal surface of the second metal component 32, such as a layer of glass, rubber, or silicone. Alternatively, the second insulating layer can be a metal oxide layer covering the second metal component 32. The second insulating layer can isolate the metal surface of the second metal component 32 from the water within the inner liner 1. This second insulating layer can significantly slow the corrosion rate of the second metal component 32. When the second metal component 32 is immersed in the water within the inner liner 1, a certain amount of leakage current may be generated between the metal portion and the water, causing the second metal component 32 to slowly corrode.

[0113] Since the metal tank body 11 is electrically connected to the first metal component 31 and the second metal component 32, the metal tank body 11 is electrically connected to the negative pole of the DC power module 22, and the electronic anode 21 is electrically connected to the positive pole of the DC power module 22, the DC power module 22 can load a negative voltage on the metal tank body 11, the first metal component 31 and the second metal component 32, and load a positive voltage on the electronic anode 21, which can prevent the metal tank body 11, the first metal tank body 11 and the second metal part from being corroded by water.

[0114] The output current of the DC power supply module 22 is less than or equal to the output current upper limit, which is calculated using the following formula:

[0115] Where:

[0116] I is the upper limit of output current, in A;

[0117] I0 is the protection current density of the inner tank 1, the unit is A / m 2 ;

[0118] A0 is the area of ​​the inner wall of the metal can 11 covered by the first insulating layer, in m 2 ;

[0119] I i is the protection current density of the i-th first metal component 31, in A / m 2 ;

[0120] A i is the area of ​​the exposed metal surface of the i-th first metal component 31 that is in direct contact with the water in the inner tank 1, in m 2 ;

[0121] n is the number of the first metal components 31;

[0122] J i is the protection current density of the i-th second metal component 32, in A / m 2 ;

[0123] a i is the area of ​​the metal surface of the i-th second metal component 32 covered by the second insulating layer, in m 2 ;

[0124] N is the number of the second metal components 32 .

[0125] The output voltage of the DC power supply module 22 is less than or equal to the output voltage upper limit, which is calculated using the following formula:

[0126] Where:

[0127] E is the upper limit of the output voltage, in V;

[0128] I is the upper limit of output current, in A;

[0129] R0 is the polarization resistance of the electronic anode 21, in Ω;

[0130] R shui is the resistance of water in the inner tank 1, in Ω;

[0131] R i is the cathode polarization resistance of the i-th first metal component 31, in Ω;

[0132] n is the number of the first metal components 31;

[0133] r i is the cathode polarization resistance of the i-th second metal component 32, in Ω;

[0134] N is the number of the second metal components 32 .

[0135] In this way, when the current output by the DC power module 22 is less than or equal to the output current upper limit, and the voltage output by the DC power module 22 is less than or equal to the output voltage upper limit, the current output by the DC power module 22 is mainly used to protect the metal can body 11, the joint 12, each first metal component 31 and each second metal component 32 from corrosion, and will not electrolyze water to produce hydrogen, thereby preventing the occurrence of hydrogen evolution explosion.

[0136] At the same time, the total area of ​​the exposed metal surface of the metal component 3 is greater than 0.5m 2 When the exposed metal surface of a part or all of the metal parts 3 is insulated, the total area of ​​the exposed metal surface of the metal parts 3 can be reduced so that the total area of ​​the exposed metal surface of the metal parts 3 is less than or equal to 0.5m 2 , thereby being able to protect the inner tank 1 and the metal component 3 by applying a weak voltage.

[0137] This example also proposes a verification test:

[0138] The protection current density of liner 1 is 12mA / m 2 The area of ​​the inner wall of the metal tank 11 covered by the first insulating layer is 1.85m 2 The first metal component 31 is an electric heater, and the protection current density of the first metal component 31 is 70mA / m 2 The area of ​​the exposed metal surface of the first metal component 31 that is in direct contact with the water in the inner tank 1 is 0.025m 2 The second metal component 32 is a heat exchanger, and the protection current density of the second metal component 32 is 12mA / m2 The area of ​​the metal surface of the second metal component 32 covered by the second insulating layer is 0.32m 2 At 20°C, when the resistivity of water in the inner tank 1 is 0.055Ω·m, it can be calculated that the upper limit of the output current is 27.79mA and the upper limit of the output voltage is 3.2V.

[0139] When the DC power supply module 22 outputs current according to the output current upper limit value and the output voltage upper limit value, the protection potential is measured at five positions on the outer wall of the inner tank 1. The test points are shown in Figure 2 and meet the protection potential requirements, that is, the protection potential range is -850 to -1100mV.

[0140] Table 2 Test results of protective potential (vs. SCE) of liner 1

[0141] In one exemplary embodiment, the protective current density I0 of the inner liner 1 is the maximum self-corrosion current density of the inner liner 1 in an aqueous solution with a conductivity of 400-2000 μS / cm and within the designed operating temperature range of the inner liner 1. A sample of the inner liner 1 can be cut from the inner liner 1 and immersed in an aqueous solution with a conductivity of 400-2000 μS / cm and within the designed operating temperature range of the inner liner 1. The maximum self-corrosion current density of the inner liner 1 sample can then be measured using an electrochemical workstation. The designed operating temperature range of the inner liner 1 can be -10 to 85°C.

[0142] The protection current density I of the i-th first metal component 31 i The maximum self-corrosion current density of the exposed metal surface of the i-th first metal component 31 in an aqueous solution with a conductivity of 400-2000 μS / cm and within the designed operating temperature range of the inner liner 1. A sample of the i-th first metal component 31 can be cut from the i-th first metal component 31, and the exposed metal surface of the sample of the i-th first metal component 31 can be immersed in an aqueous solution with a conductivity of 400-2000 μS / cm and within the designed operating temperature range of the inner liner 1. The maximum self-corrosion current density of the exposed metal surface of the sample of the i-th first metal component 31 can then be measured using an electrochemical workstation.

[0143] The protection current density J of the i-th second metal component 32 iThe maximum value of the self-corrosion current density of the metal surface covered by the second insulating layer of the i-th second metal component 32 in an aqueous solution with a conductivity of 400-2000 μS / cm and within the designed operating temperature range of the inner liner 1. A portion of the i-th second metal component 32 sample can be cut from the i-th second metal component 32, and the second insulating layer and the metal surface covered by the second insulating layer of the i-th second metal component 32 sample can be immersed in an aqueous solution with a conductivity of 400-2000 μS / cm and within the designed operating temperature range of the inner liner 1. The maximum value of the self-corrosion current density of the metal surface covered by the second insulating layer of the i-th second metal component 32 sample can then be measured using an electrochemical workstation.

[0144] Since the quality of household water in different regions may vary, for example, the composition and content of dissolved substances in household water are different, resulting in different electrical conductivities, the electrical conductivity of household water is generally concentrated between 400-2000 μS / cm. The output current upper limit is the maximum value of the sum of the protection current of the inner tank 1 required to prevent the household water from corroding the inner tank 1, the first metal component 31, and the second metal component 32 during the use of the water heater 100, the protection current required by the first metal component 31, and the protection current required by the second metal component 32. Therefore, when the output current of the DC power supply module 22 is less than or equal to the above-mentioned output current upper limit, the output current of the DC power supply module 22 is used to form a protection current for the inner tank 1, the first metal component 31, and the second metal component 32, and will not electrolyze water to produce hydrogen, which can further prevent the electrolysis of the household water in the inner tank 1 from causing hydrogen evolution explosion.

[0145] In an illustrative embodiment, the polarization resistance R0 of the electronic anode 21 is the slope of the polarization curve of the electronic anode 21 at the corrosion potential in an aqueous solution within the temperature range for which the inner liner 1 is designed to be used and having a conductivity of 400-2000 μS / cm. The temperature range for which the inner liner 1 is designed to be used may be -10 to 85°C. The polarization curve of the electronic anode 21 is a curve showing the relationship between the electrode potential and the polarization current, where the abscissa of the polarization curve is the electrode potential and the ordinate of the polarization curve is the polarization current. The polarization curve of the electronic anode 21 can be directly measured by immersing the electronic anode 21 in an aqueous solution within the temperature range for which the inner liner 1 is designed to be used and having a conductivity of 400-2000 μS / cm. The corrosion potential of the electronic anode 21 is the potential measured when the electronic anode 21 reaches a stable corrosion state in an aqueous solution within the temperature range for which the inner liner 1 is designed to be used and having a conductivity of 400-2000 μS / cm when no external current is applied. The slope of the tangent of the polarization curve of the electronic anode 21 at the corrosion potential of the electronic anode 21 is the polarization resistance of the electronic anode 21. In this embodiment, the electronic anode 21 includes an anode body and an MMO coating (mixed metal oxide coating). The anode body can be constructed in a strip shape. The anode body is made of titanium or a titanium alloy. The anode body can be made of TA1 material or TA2 material. Titanium or a titanium alloy has good electrical conductivity and corrosion resistance, and is not easily corroded even when immersed in tap water for a long time, and will not affect the water quality. The MMO coating is coated on the outer surface of the anode body. The MMO coating has very good corrosion resistance and can extend the life of the electronic anode 21. Since the MMO coating separates the anode body from water, the polarization resistance of the electronic anode 21 is the polarization resistance of the MMO coating.

[0146] Cathode polarization resistance R of the i-th first metal component 31 i The slope of the polarization curve of the i-th first metal component 31 at the corrosion potential in an aqueous solution within the temperature range for which the inner liner 1 is designed and a conductivity of 400-2000 μS / cm. The polarization curve of the i-th first metal component 31 can be directly measured by immersing the i-th first metal component 31 in an aqueous solution within the temperature range for which the inner liner 1 is designed and a conductivity of 400-2000 μS / cm. The corrosion potential of the i-th first metal component 31 is the potential measured when the i-th first metal component 31 reaches a stable corrosion state in an aqueous solution within the temperature range for which the inner liner 1 is designed and a conductivity of 400-2000 μS / cm when no external current is applied. The slope of the tangent to the polarization curve of the i-th first metal component 31 at the corrosion potential of the i-th first metal component 31 is the polarization resistance of the i-th first metal component 31.

[0147] The cathode polarization resistance r of the i-th second metal component 32 iThe slope of the polarization curve of the i-th second metal component 32 at the corrosion potential in an aqueous solution within the temperature range for which the inner liner 1 is designed and a conductivity of 400-2000 μS / cm. The polarization curve of the i-th second metal component 32 can be directly measured by immersing the i-th second metal component 32 in an aqueous solution within the temperature range for which the inner liner 1 is designed and a conductivity of 400-2000 μS / cm. The corrosion potential of the i-th second metal component 32 is the potential measured when the i-th second metal component 32 reaches a stable corrosion state in an aqueous solution within the temperature range for which the inner liner 1 is designed and a conductivity of 400-2000 μS / cm when no external current is applied. The slope of the tangent to the polarization curve of the i-th second metal component 32 at the corrosion potential of the i-th second metal component 32 is the polarization resistance of the i-th second metal component 32.

[0148] The inner tank 1 is constructed as a cylindrical tank structure, and the resistance of the water in the inner tank 1 is R shui Use the following formula to calculate:

[0149] Where:

[0150] R shui is the resistance of water in the inner tank 1, in Ω;

[0151] ρ is the density of water in liner 1, in kg / m 3 ;

[0152] H is the height of the inner tank 1, in meters;

[0153] D is the diameter of the inner liner 1, in m.

[0154] In this way, the output voltage upper limit of the DC power supply module 22 matches the output current upper limit of the DC power supply module 22, that is, when the output voltage of the DC power supply module 22 reaches the output voltage upper limit, the output current of the DC power supply module 22 reaches the output current upper limit. Since the output current upper limit is the maximum value of the sum of the protection current of the inner tank 1 required to prevent domestic water from corroding the inner tank 1, the first metal component 31, and the second metal component 32 during the use of the water heater 100, therefore, when the output voltage of the DC power supply module 22 is less than or equal to the above-mentioned output voltage upper limit, the output current of the DC power supply module 22 is used to form a protection current for the inner tank 1, the first metal component 31, and the second metal component 32, and will not electrolyze water to produce hydrogen, which can further prevent the electrolysis of domestic water in the inner tank 1 from causing hydrogen evolution explosion.

[0155] In one exemplary embodiment, the output current of the DC power module 22 is less than or equal to 200 mA, and the output current of the DC power module 22 is less than or equal to the output current upper limit. The output voltage of the DC power module 22 is less than or equal to 4 V, and the output voltage of the DC power module 22 is less than or equal to the output voltage upper limit.

[0156] The output current of the DC power module 22 is less than or equal to 200 mA, and the output voltage of the DC power module 22 is less than or equal to 4 V. No hydrogen evolution reaction occurs at the metal can body 11 and the metal component 3 serving as the cathode, further reducing the possibility of hydrogen evolution explosion.

[0157] In an illustrative embodiment, the output current upper limit of the DC power supply module 22 is greater than 200 mmA, that is, when the maximum value of the sum of the protection currents required by the inner tank 1 and the metal component 3 is greater than 200 mA, multiple anti-corrosion components 2 are provided.

[0158] Since the maximum value of the sum of the protection currents required for the inner liner 1 and the metal component 3 is large, multiple anti-corrosion components 2 can be set to simultaneously apply protection current to the metal tank body 11 and the metal component 3, which can not only prevent a single anti-corrosion component 2 from being unable to provide a sufficiently large protection current, but also avoid hydrogen evolution explosion caused by excessive voltage output by the DC power supply module 22 of a single anti-corrosion component 2.

[0159] This embodiment also provides a corrosion protection design method for a water heater 100. The water heater 100 includes an inner tank 1 and a metal component 3. The metal component 3 is disposed within the inner tank 1. The inner tank 1 includes a metal body 11 and a first insulating layer covering the inner wall of the metal body 11. The metal component 3 is electrically connected to the metal body 11.

[0160] The anti-corrosion design method includes the following steps:

[0161] Step S1: Determine whether the total area of ​​the exposed metal surface of the metal component 3 that is in direct contact with the water in the inner tank 1 is greater than 0.5m 2 If yes, go to step S2;

[0162] Step S2: Insulate at least a portion of the exposed metal surface of the metal component 3 and cover it with a second insulating layer so that the total area of ​​the exposed metal surface of the metal component 3 that is in direct contact with the water in the inner tank 1 is less than or equal to 0.5 m 2 .

[0163] Methods for insulating the metal surface of the second metal component 32 include coating the metal surface with insulating paint, coating the metal surface with rubber, coating the metal surface with plastic, applying anti-corrosion paint to the metal surface, oxidizing the metal surface, passivating the metal surface, or laminating the metal surface with insulating material. The insulating material may be rubber, silicone, or the like.

[0164] Since the first insulating layer covers the inner wall of the metal tank body 11, and the total area of ​​the exposed metal surface of the metal component 3 that is in direct contact with the water in the inner tank 1 is less than or equal to 0.5m 2 In this way, the total area of ​​the exposed metal surface in direct contact with the water in the inner tank 1 is small, and the DC power supply module 22 can meet the anti-corrosion requirements of the inner tank 1 and the metal component 3 by loading a weak voltage between the metal tank body 11 and the electronic anode 21 and between the metal component 3 and the electrode anode, thereby reducing the risk of hydrogen evolution explosion, reducing the safety hazard of leakage of the anti-corrosion component 2, and also reducing the difficulty of the electrical control design of the water heater 100.

[0165] In an illustrative embodiment, the anti-corrosion design method further includes step S3;

[0166] Step S1 also includes: when the total area of ​​the exposed metal surface of the metal component 3 directly in contact with the water in the inner tank 1 is not greater than 0.5m 2 When the metal component 3 only includes the first metal component 31 with an exposed metal surface, the process proceeds to step S3;

[0167] Step S3: Determine the output current upper limit based on the protection current density of the inner liner 1, the area of ​​the inner wall of the metal tank body 11 covered by the first insulating layer, the protection current density of the exposed metal surface of each first metal component 31, and the area of ​​the exposed metal surface of each first metal component 31 directly in contact with the water in the inner liner 1, and set the output current of the DC power supply module 22 to be less than or equal to the output current upper limit.

[0168] The output voltage upper limit is determined based on the output current upper limit, the polarization resistance of the electronic anode 21, the resistance of the water in the inner tank 1 and the cathode polarization resistance of each first metal component 31, and the output voltage of the DC power supply module 22 is set to be less than or equal to the output voltage upper limit.

[0169] The output current upper limit of the DC power module 22 can be calculated using the above formula (1). The output voltage upper limit of the DC power module 22 can be calculated using the above formula (2).

[0170] In this way, when the current output by the DC power supply module 22 is less than or equal to the output current upper limit, and the voltage output by the DC power supply module 22 is less than or equal to the output voltage upper limit, the current output by the DC power supply module 22 mainly provides a protective current for the metal tank body 11, the joint 12 and the first metal component 31, so that the metal tank body 11 and the first metal component 31 are not corroded, and water is not electrolyzed to produce hydrogen, which can prevent the occurrence of hydrogen evolution explosion.

[0171] In an illustrative embodiment, the anti-corrosion design method further includes step S4 after step S2;

[0172] Step S4: The metal component 3 includes a first metal component 31 having a bare metal surface and a second metal component 32 having an insulating metal surface;

[0173] The output current upper limit is determined based on the protection current density of the inner liner 1, the area of ​​the inner wall of the metal tank body 11 covered by the first insulating layer, the protection current density of the exposed metal surface of each first metal component 31, the area of ​​the exposed metal surface of each first metal component 31 that is in direct contact with the water in the inner liner 1, the protection current density of the metal surface of each second metal component 32 covered by the second insulating layer, and the area of ​​the metal surface of each second metal component 32 covered by the second insulating layer, and the output current of the DC power supply module 22 is set to be less than or equal to the output current upper limit;

[0174] The output voltage upper limit is determined based on the output current upper limit, the polarization resistance of the electronic anode 21, the resistance of the water in the inner tank 1, the cathode polarization resistance of each first metal component 31, and the cathode polarization resistance of each second metal component 32, and the output voltage of the DC power supply module 22 is set to be less than or equal to the output voltage upper limit.

[0175] The output current upper limit of the DC power module 22 can be calculated using the above formula (3). The output voltage upper limit of the DC power module 22 can be calculated using the above formula (4).

[0176] In this way, when the current output by the DC power supply module 22 is less than or equal to the output current upper limit, and the voltage output by the DC power supply module 22 is less than or equal to the output voltage upper limit, the current output by the DC power supply module 22 mainly provides a protective current for the metal tank body 11, the first metal component 31 and the second metal component 32, so that the metal tank body 11, the first metal component 31 and the second metal component 32 are not corroded, and water is not electrolyzed to produce hydrogen, which can prevent the occurrence of hydrogen evolution explosion.

[0177] It will be appreciated by those skilled in the art that all or some of the steps, systems, and functional modules / units in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementations, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed by several physical components in cooperation. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or temporary medium). As is well known to those skilled in the art, the term "computer storage medium" includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those skilled in the art that communication media generally embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

Claims

1. A water heater, wherein, Comprising: Inner liner, including a metal tank body and a first insulating layer covering the inner wall of the metal tank body; Metal component, disposed within the inner liner and electrically connected to the metal tank body; And Anticorrosion component, including: Electronic anode, extending into the inner liner; and DC power supply module, including a positive electrode electrically connected to the electronic anode and a negative electrode electrically connected to the metal tank body, configured to apply a weak electrical voltage between the metal tank body and the electronic anode; Among them, the total area of the exposed metal surface of the metal component in direct contact with the water phase in the inner container is less than or equal to 0.5 m 2 .

2. The water heater according to claim 1, wherein, The metal component includes a first metal component and / or a second metal component; The first metal component has the exposed metal surface; The metal surface of the second metal component is subjected to insulation treatment to form a second insulating layer, and the second insulating layer can separate the metal surface of the second metal component from the water within the inner liner.

3. The water heater according to claim 2, wherein, The method of insulating treatment for the metal surface of the second metal component includes: Coating an insulating paint on the metal surface, coating rubber on the metal surface, coating plastic on the metal surface, coating an anticorrosion paint on the metal surface, performing an oxidation treatment on the metal surface, performing a passivation treatment on the metal surface, or laminating an insulating material on the metal surface.

4. The water heater according to claim 2, wherein, The output current of the DC power supply module is less than or equal to the upper limit value of the output current, and the upper limit value of the output current is calculated by the following formula: Where: I is the upper limit value of the output current; I0 is the protection current density of the inner liner; A0 is the area of the inner wall of the metal tank body covered by the first insulating layer; I i is the protection current density of the exposed metal surface of the i-th first metal component; A i is the area of the exposed metal surface where the i-th first metal component is in direct contact with the water in the inner tank; n is the number of first metal components; J i is the protection current density of the metal surface of the i-th second metal component covered by the second insulating layer; a i is the area of the metal surface of the i-th second metal component covered by the second insulating layer; N is the number of second metal components.

5. The water heater according to claim 4, wherein, The protection current density I0 of the inner liner is the maximum value of the self-corrosion current density of the inner liner in the aqueous solution; The protection current density I of the i-th first metal component i is the bare metal surface of the i-th first metal component in water solution The maximum value of the self-corrosion current density in the liquid; The protection current density J of the i-th second metal component i is the maximum value of the self-corrosion current density of the metal surface of the i-th second metal component covered by the second insulating layer in the aqueous solution; Wherein, the temperature of the aqueous solution is within the temperature range of the designed use of the inner liner, and the conductivity of the aqueous solution is 400 - 2000 μS / cm.

6. The water heater according to claim 4 or 5, wherein, The output voltage of the DC power supply module is less than or equal to the upper limit value of the output voltage, and the upper limit value of the output voltage is calculated by the following formula: Where: E is the upper limit value of the output voltage; I is the upper limit value of the output current; R0 is the polarization resistance of the electronic anode; R shui is the resistance of the water in the inner container; R i is the cathodic polarization resistance of the i-th first metal component; n is the number of first metal components; r i is the cathodic polarization resistance of the i-th second metal component; N is the number of second metal components.

7. The water heater according to claim 6, wherein, The polarization resistance R0 of the electronic anode is the slope of the polarization curve of the electronic anode in the aqueous solution at the corrosion potential; The cathodic polarization resistance R of the i-th first metal component i is the slope of the polarization curve of the i-th first metal component in an aqueous solution at the corrosion potential; The cathodic polarization resistance r of the i-th second metal component i is the slope of the polarization curve of the i-th second metal component in the aqueous solution at the corrosion potential; Wherein, the temperature of the aqueous solution is within the temperature range of the designed use of the inner liner, and the conductivity of the aqueous solution is 400 - 2000 μS / cm.

8. The water heater according to claim 6, wherein, The inner container is structured as a cylindrical tank, and the resistance R of the water in the inner container shui is calculated using the following formula: Where: ρ is the density of the water in the inner liner; H is the height of the inner liner; D is the diameter of the inner liner.

9. The water heater according to claim 6, wherein, The output current of the DC power supply module is less than or equal to 200 mA, and the output voltage of the DC power supply module is less than or equal to 4 V.

10. The water heater according to claim 9, wherein, The upper limit value of the output current is greater than 200 mA, and multiple anticorrosion components are provided.

11. An anti-corrosion design method for a water heater, wherein, The water heater includes an inner liner and a metal component disposed within the inner liner. The inner liner includes a metal tank body electrically connected to the metal component and a first insulating layer covering the inner wall of the metal tank body. The anticorrosion design method includes: Based on the total area of the exposed metal surfaces of the metal components in direct contact with the water phase in the inner container being greater than 0.5 m 2 , the exposed metal surfaces of at least some of the metal components are insulated so that the total area of the exposed metal surfaces of the metal components in direct contact with the water phase in the inner container is less than or equal to 0.5 m 2 .

12. The anti-corrosion design method according to claim 11, wherein, The anticorrosion design method further includes: Based on the total area of the exposed metal surfaces of the metal components in direct contact with the water phase in the inner tank being greater than 0.5 m 2 , the exposed metal surfaces of at least a part of the metal components are insulated to cover a second insulating layer, so that the total area of the exposed metal surfaces of the metal components in direct contact with the water phase in the inner tank is less than or equal to 0.5 m 2 .

13. The anti-corrosion design method according to claim 12, wherein, The anticorrosion design method further includes: Based on that the total area of the exposed metal surfaces of the metal components in direct contact with the water phase in the inner liner is less than or equal to 0.5 m 2 , and the metal components only include the first metal components with exposed metal surfaces. Determine the upper limit value of the output current according to the protection current density of the inner liner, the area of the inner wall of the metal tank covered by the first insulating layer, the protection current density of the exposed metal surface of each first metal component, and the area of the exposed metal surface of each first metal component in direct contact with the water phase in the inner liner, and set the output current of the DC power supply module to be less than or equal to the upper limit value of the output current.

14. The anti-corrosion design method according to claim 13, wherein, The anticorrosion design method further includes: The total area of the exposed metal surfaces of the metal components in direct contact with the water phase in the inner tank is less than or equal to 0.5 m 2 , and the metal components only include the first metal components with exposed metal surfaces. The upper limit value of the output voltage is determined based on the upper limit value of the output current, the polarization resistance of the electronic anode, the resistance of the water in the inner tank, and the cathodic polarization resistance of each first metal component, and the output voltage of the DC power supply module is set to be less than or equal to the upper limit value of the output voltage.

15. The anti-corrosion design method according to claim 12, wherein The anticorrosion design method further includes: After insulating at least a part of the exposed metal surface of the metal component, the metal component includes a first metal component having an exposed metal surface and a second metal component whose metal surface has been subjected to insulation treatment. Determine the upper limit value of the output current according to the protection current density of the inner tank, the area of the inner wall of the metal tank covered by the first insulating layer, the protection current density of the exposed metal surface of each first metal component, the area of the exposed metal surface of each first metal component directly in contact with the water phase in the inner tank, the protection current density of the metal surface of each second metal component covered by the second insulating layer, and the area of the metal surface of each second metal component covered by the second insulating layer, and set the output current of the DC power supply module to be less than or equal to the upper limit value of the output current; Determine the upper limit value of the output voltage according to the upper limit value of the output current, the polarization resistance of the electronic anode, the resistance of the water in the inner tank, the cathodic polarization resistance of each first metal component, and the cathodic polarization resistance of each second metal component, and set the output voltage of the DC power supply module to be less than or equal to the upper limit value of the output voltage.

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