A phase change electric water heater and a method of operating the same

Abstract

The application relates to the technical field of water heaters, and particularly discloses a phase-change electric water heater and an operation method thereof, wherein low-temperature tap water first flows through a water tank preheating module, a first-stage preheating is completed by using the water tank preheating module, the water inlet basic temperature is advancedly lifted, and then the preheated water flow enters first heat exchange pipes to continue absorbing the heat of a phase-change heat exchange medium in a phase-change heat storage module to realize second heating, a two-stage gradient heating heat exchange structure that the water tank preheating module preheats first and then enters the phase-change heat storage module is constructed, the heat exchange temperature difference between the water inlet and the phase-change heat storage module is greatly reduced, low-temperature cold water directly impacting a heat exchange surface of the first heat exchange pipes is avoided from the source, intense cold and heat alternating stress is eliminated, and the service life is prolonged. The heat exchange protruding structure of the outer wall of the first heat exchange pipes increases the effective heat exchange surface area in a unit pipe length range, the total heat exchange area between the outer side of the pipe wall and the phase-change heat exchange medium is significantly improved, and therefore the overall heat exchange efficiency is effectively enhanced.

Description

Technical Field

[0001] This invention relates to the field of water heater technology, and in particular to a phase change electric water heater and its operating method. Background Technology

[0002] Phase change electric water heaters utilize a phase change heat transfer medium with high heat storage density to store latent heat, thereby achieving a continuous and high-flow-rate supply of hot water in a relatively small volume.

[0003] Existing phase change electric water heaters typically use a direct-flow heat exchange method where low-temperature tap water is directly introduced into the phase change heat storage chamber. In winter, when low-temperature tap water enters the storage chamber directly, the significant temperature difference between the tap water and the phase change heat storage medium causes the high-temperature liquid phase change heat exchange medium at the interface to rapidly cool and solidify upon contact with the cold water. This forms a dense solid insulation layer on the heat exchange surface. Because the solid phase change heat exchange medium has extremely low thermal conductivity, this insulation layer directly blocks the transfer of latent heat from the internal high-temperature liquid phase change heat exchange medium. This prevents most of the latent heat stored in the phase change heat exchange medium from being continuously released to participate in hot water heat exchange, significantly reducing the overall efficient and continuous utilization rate of the phase change heat storage system. It can even lead to temporary water outages and interruptions in hot water supply. Simultaneously, the impact of cold water causes severe alternating thermal stress within the phase change heat exchange medium, leading to material delamination, cracking, and failure after long-term operation. This results in a continuous decline in heat storage and release performance, shortening the lifespan of the phase change heat storage medium to some extent. Summary of the Invention

[0004] The first technical problem to be solved by the present invention is to provide a phase change electric water heater that can improve heat exchange efficiency and extend service life.

[0005] The second technical problem to be solved by the present invention is to provide an operating method for a phase change electric water heater, which can improve the heat exchange efficiency of the phase change water heater and extend its service life.

[0006] The first technical problem mentioned above is solved by the following technical solution:

[0007] A phase change electric water heater, comprising:

[0008] A phase change thermal energy storage module includes a thermal energy storage body, a phase change heat transfer medium, and a first heat exchange tube. The first heat exchange tube is disposed within the thermal energy storage body, and the phase change heat transfer medium is filled within the thermal energy storage body. The outer wall of the phase change heat transfer medium of the first heat exchange tube has multiple heat exchange protrusions along its circumferential direction. These multiple heat exchange protrusions are spaced apart along the extension direction of the phase change heat transfer medium of the first heat exchange tube. The phase change heat transfer medium fills the phase change heat transfer medium within the thermal energy storage body and encloses the outer wall of the phase change heat transfer medium of the first heat exchange tube and the heat exchange protrusions.

[0009] A water tank preheating module, wherein the outlet of the water tank preheating module is connected to the inlet of the first heat exchange tube;

[0010] A water inlet pipe, which is connected to the water inlet of the water tank preheating module;

[0011] The first water outlet pipe is connected to the water outlet of the first heat exchange pipe;

[0012] A first electric heater is used to heat the water tank preheating module and the phase change heat transfer medium.

[0013] The phase-change electric water heater of the present invention has the following advantages compared with the prior art:

[0014] The first electric heater preheats the water tank preheating module and the phase change heat storage medium. When supplying heating water, low-temperature tap water first flows through the water tank preheating module via the inlet pipe, completing the first-stage preheating and raising the base temperature of the inlet water in advance. The preheated water then enters the first heat exchange tube to further absorb heat from the phase change heat storage medium in the heat storage body, achieving secondary heating before flowing out from the first outlet pipe. This constructs a two-stage cascade heating heat exchange structure where the water tank preheating module preheats the water before it enters the phase change heat storage module, significantly reducing the heat exchange between the inlet water and the phase change heat storage module. The temperature difference not only improves heating efficiency but also prevents direct impact of low-temperature cold water on the heat exchange surface of the first heat exchange tube. Under stable heat exchange conditions with a small temperature difference, the phase change heat exchange medium can undergo phase change and solidification layer by layer in an orderly manner, avoiding the problem of instantaneous rapid solidification of the surface layer to form a dense solid insulation layer. The latent heat stored inside the phase change heat exchange medium can be released steadily, completely, and continuously, improving its heat exchange efficiency. It also eliminates severe hot and cold alternation stress, avoiding aging problems such as cracking, delamination, and performance degradation that may occur in the phase change heat exchange medium under the impact of cold water, effectively extending its service life. In addition, the heat exchange protrusion structure on the outer wall of the first heat exchange tube increases the effective heat exchange surface area per unit tube length, significantly increasing the total heat exchange area between the outer wall of the tube and the phase change heat exchange medium, allowing the latent heat stored inside the phase change heat exchange medium to be released steadily, completely, and continuously, thereby effectively enhancing the overall heat exchange efficiency.

[0015] In one embodiment, the water tank preheating module includes a water tank and a second heat exchange tube. The water tank is used to store liquid heat exchange medium. The first electric heater and the second heat exchange tube are both disposed in the water tank. The inlet of the second heat exchange tube is connected to the inlet pipe, and the outlet of the second heat exchange tube is connected to the inlet of the first heat exchange tube.

[0016] In one embodiment, the phase change electric water heater further includes a first connecting pipe, a control valve, a second outlet pipe, and a first bypass pipe. The outlet of the water tank preheating module is connected to the inlet of the first heat exchange pipe through the first connecting pipe. The inlet of the first bypass pipe is connected to the first connecting pipe. The outlet of the first outlet pipe and the outlet of the first bypass pipe are respectively connected to the inlet of the second outlet pipe through the control valve. The control valve is used to control the second outlet pipe to selectively connect to the first outlet pipe or the first bypass pipe.

[0017] In one embodiment, the phase change electric water heater further includes a second electric heater, a second bypass pipe, and a flow regulating valve. The second electric heater is disposed on the second outlet pipe and is located upstream of the connection between the second bypass pipe and the second outlet pipe. The second bypass pipe is connected between the inlet pipe and the second outlet pipe. The flow regulating valve is disposed on the second bypass pipe and is used to regulate the water flow rate in the second bypass pipe.

[0018] In one embodiment, the phase change electric water heater further includes an electromagnetic switch valve, a water pump, and a second connecting pipe. The second connecting pipe is connected between the inlet pipe and the second outlet pipe. The electromagnetic switch valve is disposed on the second connecting pipe and is used to control the flow of water in the second connecting pipe.

[0019] The water pump is installed on the inlet pipe and located downstream of the connection between the second connecting pipe and the inlet pipe; or, the water pump is installed on the second outlet pipe and located upstream of the connection between the second connecting pipe and the second outlet pipe; or, the water pump is installed on the first bypass pipe; or, the water pump is installed on the second connecting pipe.

[0020] In one embodiment, the phase change electric water heater further includes a water proportioning valve, which is disposed on the water inlet pipe and located downstream of the connection between the second connecting pipe and the water inlet pipe, and the water proportioning valve is used to adjust the water flow rate in the water inlet pipe.

[0021] In one embodiment, the phase change electric water heater further includes a first temperature sensor disposed on the first connecting pipe.

[0022] In one embodiment, the phase change electric water heater further includes a second temperature sensor and a third temperature sensor, wherein the second temperature sensor is used to detect the temperature of the phase change heat transfer medium, and the third temperature sensor is used to detect the temperature inside the water tank preheating module.

[0023] The second technical problem mentioned above is solved by the following technical solution:

[0024] A method for operating a phase change electric water heater, the phase change electric water heater comprising a phase change heat storage module, a water tank preheating module, an inlet pipe, a first outlet pipe, a first electric heater, a control valve, a second outlet pipe, a first bypass pipe, and a first temperature sensor, the phase change heat storage module comprising a heat storage body, a phase change heat transfer medium, and a first heat exchange tube, the first heat exchange tube being disposed within the heat storage body, the phase change heat transfer medium filling the heat storage body and surrounding the first heat exchange tube, the inlet pipe being connected to the inlet of the water tank preheating module, and the first outlet pipe... The first electric heater is connected to the outlet of the first heat exchange tube and is used to heat the water tank preheating module and the phase change heat transfer medium. The inlet of the first bypass pipe is connected to the outlet of the water tank preheating module and the inlet of the first heat exchange tube, respectively. The outlet of the first outlet pipe and the outlet of the first bypass pipe are connected to the inlet of the second outlet pipe through the control valve, respectively. The control valve is used to control the second outlet pipe to selectively connect to or to the first bypass pipe. The phase change electric water heater is characterized by the following operating method:

[0025] In response to the user's hot water usage status, the first outlet water temperature of the water tank preheating module is detected;

[0026] If the first outlet water temperature is not less than the target outlet water temperature of the second outlet water pipe, then control the control valve to connect the second outlet water pipe with the first bypass pipe, so that the water preheated by the water tank preheating module flows out through the first bypass pipe and the second outlet water pipe in sequence for heating.

[0027] If the first outlet water temperature is lower than the target outlet water temperature of the second outlet water pipe, the control valve is controlled to connect the second outlet water pipe to the first outlet water pipe, so that the water preheated by the water tank preheating module continues to flow through the first heat exchange tube to absorb the heat of the phase change heat medium and then flows out from the first outlet water pipe and the second outlet water pipe in sequence to provide heat.

[0028] The operating method of the phase change electric water heater described in this invention has the following advantages compared with the prior art:

[0029] The first electric heater preheats the water tank preheating module and the phase change heat exchange medium. The water tank preheating module, acting as the primary heat source, significantly reduces the temperature difference between the incoming water and the phase change heat storage module, improving heating efficiency. Simultaneously, it prevents low-temperature cold water from directly impacting the heat exchange surface of the first heat exchange tube. Under stable heat exchange conditions with a small temperature difference, the phase change heat exchange medium can undergo phase change and solidification layer by layer in an orderly manner, avoiding the problem of instantaneous rapid solidification of the surface layer to form a dense solid insulation layer. The latent heat stored inside the phase change heat exchange medium can be released steadily, completely, and continuously, improving its heat exchange efficiency. It also eliminates severe hot and cold alternating stress, preventing aging problems such as cracking, delamination, and performance degradation that may occur under the impact of cold water, effectively extending its service life. Meanwhile, the water… The first outlet water temperature of the preheating module is monitored in real time to provide a basis for control decisions. The control valve, as a path switching actuator, accurately controls the water flow to switch between the two branches based on the temperature judgment result. The first bypass pipe and the second outlet pipe form a "direct supply path". When the first outlet water temperature reaches the target outlet water temperature, the water flows directly through this path, avoiding the ineffective intervention of the phase change heat medium, reducing its thermal cycle fatigue, and improving its heat exchange efficiency. The first outlet water pipe and the first heat exchange tube containing the phase change heat medium form a "compensation heat path". When the first outlet water temperature does not reach the target outlet water temperature, the water flow is forced into this path. When flowing through the first heat exchange tube, it efficiently absorbs the latent heat released by the phase change heat medium, achieving secondary precise heating. In this design, the on-demand switching mechanism of the control valve ensures the tiered utilization of thermal energy between the water tank preheating module and the phase change heat storage medium—prioritizing the use of primary preheating energy and only drawing upon high-density phase change heat storage when insufficient, thereby improving overall heat exchange efficiency. Simultaneously, the direct supply mode via the first bypass pipe significantly reduces the number of charge-discharge cycles of the phase change heat storage medium under unnecessary operating conditions, delaying its phase change stratification and thermal performance degradation, fundamentally extending the service life of the first heat exchange tube and the phase change heat storage medium. Ultimately, hot water at the target temperature is stably output at the second outlet pipe, achieving a synergistic unity of enhanced heat exchange and improved durability.

[0030] In one embodiment, the water tank preheating module includes a water tank and a second heat exchange tube. The water tank is used to store a liquid heat exchange medium. Both the first electric heater and the second heat exchange tube are disposed in the water tank. The inlet of the second heat exchange tube is connected to the inlet pipe, and the outlet of the second heat exchange tube is connected to the inlet of the first heat exchange tube. The operation method of the phase change electric water heater further includes:

[0031] If the temperature of the liquid heat exchange medium in the water tank is lower than the first preset temperature, the first electric heater is activated to heat the liquid heat exchange medium in the water tank, wherein the first preset temperature is not lower than the target outlet water temperature.

[0032] In one embodiment, the phase-change electric water heater further includes a second electric heater, a second bypass pipe, and a flow regulating valve. The second electric heater is disposed on the second outlet pipe and is located upstream of the connection between the second bypass pipe and the second outlet pipe. The second bypass pipe is connected between the inlet pipe and the second outlet pipe. The flow regulating valve is disposed on the second bypass pipe. The operation method of the phase-change electric water heater further includes:

[0033] If the real-time water temperature of the second water outlet pipe is lower than the target water temperature, the second electric heater is activated to heat the water flowing through the second water outlet pipe so that the real-time water temperature of the second water outlet pipe reaches the target water temperature.

[0034] If the real-time outlet water temperature of the second outlet pipe is greater than the target outlet water temperature, the flow regulating valve is controlled to increase the water flow rate of the second bypass pipe so that the real-time outlet water temperature of the second outlet pipe reaches the target outlet water temperature.

[0035] In one embodiment, the phase-change electric water heater further includes an electromagnetic switch valve, a water pump, a second connecting pipe, and a second temperature sensor. The second connecting pipe is connected between the inlet pipe and the second outlet pipe. The electromagnetic switch valve is disposed on the second connecting pipe and is used to control the flow of water in the second connecting pipe. The water pump is disposed on the inlet pipe and located downstream of the connection between the second connecting pipe and the inlet pipe; or, the water pump is disposed on the second outlet pipe and located upstream of the connection between the second connecting pipe and the second outlet pipe; or, the water pump is disposed on the first bypass pipe; or, the water pump is disposed on the second connecting pipe. The second temperature sensor is used to detect the temperature of the phase-change heat transfer medium. The operation method of the phase-change electric water heater further includes:

[0036] In response to the user's unused hot water status, if the temperature of the liquid heat exchange medium in the water tank is lower than the second preset temperature, the first electric heater is controlled to start; wherein, the second preset temperature is not lower than the first preset temperature;

[0037] If the temperature of the liquid heat exchange medium in the water tank is not lower than the second preset temperature, the first electric heater is controlled to stop heating and the temperature of the phase change heat exchange medium of the phase change heat storage module is obtained.

[0038] If the temperature of the phase change heat medium is less than the third preset temperature, the control valve is controlled to connect the second outlet pipe to the first outlet pipe, the electromagnetic switch valve is opened and the water pump is started, wherein the third preset temperature is greater than the target outlet temperature.

[0039] If the temperature of the phase change heat transfer medium is not less than the third preset temperature, the electromagnetic switch valve is controlled to close and the water pump is stopped.

[0040] In one embodiment, the phase change electric water heater further includes a water proportioning valve, which is disposed on the inlet pipe and located downstream of the connection between the second connecting pipe and the inlet pipe. The operating method of the phase change electric water heater further includes:

[0041] If the temperature of the phase change heat medium is less than the third preset temperature, the control valve is controlled to connect the second outlet pipe to the first outlet pipe, the electromagnetic switch valve is opened and the water pump is started.

[0042] If the first outlet water temperature is lower than the third preset temperature, the water proportional valve is controlled to reduce the water flow rate of the second connecting pipe so that the first outlet water temperature reaches the third preset temperature.

[0043] In one embodiment, the operation method of the phase change electric water heater further includes:

[0044] When the opening of the water proportional valve is adjusted to the minimum and the first outlet water temperature is lower than the third preset temperature, the first electric heater is activated to make the first outlet water temperature reach the third preset temperature.

[0045] In one embodiment, the control activates the first electric heater, followed by:

[0046] If the first outlet water temperature is lower than the third preset temperature, the second electric heater is activated to bring the first outlet water temperature up to the third preset temperature. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the phase change electric water heater provided by the present invention;

[0048] Figure 2 for Figure 1 A magnified view of part A in the middle;

[0049] Figure 3 for Figure 1 A magnified view of part B in the middle section.

[0050] in:

[0051] 1. Phase change thermal energy storage module; 101. Thermal energy storage body; 102. Phase change thermal medium; 103. First heat exchange tube; 1031. Heat exchange protrusion;

[0052] 2. Water tank preheating module; 201. Water tank; 202. Second heat exchange tube;

[0053] 3. Inlet pipe; 4. First outlet pipe; 5. First electric heater; 6. First connecting pipe; 7. Control valve; 8. Second outlet pipe; 9. First bypass pipe; 10. Second electric heater; 11. Second bypass pipe; 12. Flow regulating valve; 13. Solenoid switch valve; 14. Water pump; 15. Second connecting pipe; 16. Water proportional valve; 17. First temperature sensor; 18. Second temperature sensor; 19. Third temperature sensor; 20. Fourth temperature sensor; 21. Controller; 22. Housing; 23. Water flow sensor. Detailed Implementation

[0054] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0055] In the description of this invention, it should be noted that the terms "center," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Specifically, the terms "first position" and "second position" refer to two different positions.

[0056] Unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and connections within two components or interactions between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0057] Unless otherwise expressly specified and limited, "above" or "below" a 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 a 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" of a 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.

[0058] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0059] Please refer to Figure 1 and Figure 2 As shown, this embodiment provides a phase change electric water heater, which includes: a phase change heat storage module 1, a water tank preheating module 2, an inlet pipe 3, a first outlet pipe 4, and a first electric heater 5. The phase change heat storage module 1 includes a heat storage body 101, a phase change heat transfer medium 102, and a first heat exchange tube 103. The first heat exchange tube 103 is disposed inside the heat storage body 101, and the outer wall of the first heat exchange tube 103 is provided with a plurality of heat exchange protrusions 1031 along the circumferential direction. The plurality of heat exchange protrusions 1031 are arranged along the first heat exchange tube 103. The phase change heat exchange medium 102 is distributed in the extension direction of the 03, and the phase change heat exchange medium 102 is filled in the heat storage body. The phase change heat exchange medium 102 wraps the outer wall of the first heat exchange tube 103 and the heat exchange protrusion 1031. The outlet of the water tank preheating module 2 is connected to the inlet of the first heat exchange tube 103. The inlet pipe 3 is connected to the inlet of the water tank preheating module 2. The first outlet pipe 4 is connected to the outlet of the first heat exchange tube 103. The first electric heater 5 is used to heat the water tank preheating module 2 and the phase change heat storage module 1.

[0060] With this configuration, the first electric heater 5 preheats the water tank preheating module 2 and the phase change heat exchange medium 103. When supplying heating water, the low-temperature tap water first flows through the water tank preheating module 2 via the inlet pipe 3, completing the first-stage preheating using the water tank preheating module 2 to raise the base temperature of the inlet water in advance. Then, the preheated water flows into the first heat exchange tube 103 to further absorb heat from the phase change heat exchange medium 102 in the heat storage body 101 for secondary heating before flowing out from the first outlet pipe 4. This constructs a two-stage stepped heating heat exchange structure where the water tank preheating module 2 preheats the water before it enters the phase change heat storage module 1, significantly reducing the distance between the inlet water and the phase change heat storage module. The temperature difference between the two heat exchange tubes improves the heating effect and prevents low-temperature cold water from directly impacting the heat exchange surface of the first heat exchange tube 103. Under stable heat exchange conditions with a small temperature difference, the phase change heat medium 102 can undergo phase change and solidification layer by layer in an orderly manner, without the problem of instantaneous rapid solidification of the surface layer to form a dense solid insulation layer. The latent heat stored inside the phase change heat medium 102 can be released steadily, completely and continuously, improving its heat exchange efficiency. It also eliminates the stress of severe hot and cold alternation and avoids aging problems such as cracking, delamination, and performance degradation that may occur in the phase change heat medium 102 under the impact of cold water, effectively extending its service life. In addition, the heat exchange protrusion structure on the outer wall of the first heat exchange tube 103 increases the effective heat exchange surface area per unit tube length, significantly increasing the total heat exchange area between the outer wall of the tube and the phase change heat medium, so that the latent heat stored inside the phase change heat medium can be released steadily, completely and continuously, thereby effectively enhancing the overall heat exchange efficiency.

[0061] In this embodiment, as Figure 2 As shown, the heat exchange protrusion is a heat exchange fin sleeved on the outer peripheral wall of the first heat exchange tube 103. In other embodiments, the heat exchange protrusion 1031 is a protrusion formed by pressing the tube wall of the first heat exchange tube 103.

[0062] Alternatively, please refer to Figure 3 As shown, the water tank preheating module 2 includes a water tank 201 and a second heat exchange tube 202. The water tank 201 stores the liquid heat exchange medium. The first electric heater 5 and the second heat exchange tube 202 are both located inside the water tank 201. The inlet of the second heat exchange tube 202 is connected to the inlet pipe 3, and the outlet of the second heat exchange tube 202 is connected to the inlet of the first heat exchange tube 103. Furthermore, the second heat exchange tube 202 is serpentine. This configuration introduces the second heat exchange tube 202 to achieve a water circuit isolation design, ensuring that the water flows through the independently enclosed pipe of the second heat exchange tube 202 throughout the entire process, without any direct contact with the static liquid heat exchange medium in the inner tank of the water tank 201, thereby achieving physical isolation of the water circuit system. With this structure, the scale and corrosion problems of the inner tank that are common in traditional storage water heaters can be fundamentally eliminated. There is no need to install anti-corrosion magnesium rods, thus completely eliminating the need for periodic replacement of magnesium rods and manual descaling, significantly reducing the operation and maintenance costs of the equipment. In addition, the serpentine pipeline layout effectively extends the water flow path and increases the heat exchange area, thereby significantly improving heat exchange efficiency while taking into account both long-term reliability and energy-saving operation performance.

[0063] Furthermore, in this embodiment, the outer peripheral wall of the second heat exchange tube 202 is sleeved on the heat exchange fins.

[0064] In this embodiment, the liquid heat exchange medium is water. In other embodiments, the liquid heat exchange medium may also be an aqueous solution of ethylene glycol, mineral heat transfer oil, etc.

[0065] In this embodiment, the phase change electric water heater also includes a first connecting pipe 6, a control valve 7, a second outlet pipe 8, and a first bypass pipe 9. The outlet of the water tank preheating module 2 is connected to the inlet of the first heat exchange pipe 103 through the first connecting pipe 6. The inlet of the first bypass pipe 9 is connected to the first connecting pipe 6. The outlets of the first outlet pipe 4 and the first bypass pipe 9 are respectively connected to the inlet of the second outlet pipe 8 through the control valve 7. The control valve 7 is used to control the second outlet pipe 8 to selectively connect to the first outlet pipe 4 or the first bypass pipe 9. Further, the control valve 7 is a three-way valve. With this configuration, by adjusting the opening and closing state or the switching angle of the control valve 7, precise switching and flow path guidance control of the corresponding pipeline on / off logic can be achieved. This intelligent response mechanism ensures that the system can automatically adjust the water path direction according to real-time water temperature changes, thereby optimizing heat distribution while ensuring water comfort, avoiding ineffective heating or heat waste, and further improving the overall energy efficiency and operational stability of the unit.

[0066] Optionally, the phase change electric water heater also includes a first temperature sensor 17, which is installed on the first connecting pipe 6. In actual operation, the control valve 7 responds to the detection signal fed back by the first temperature sensor 17. When the measured temperature value represented by the temperature detection signal reaches or exceeds the preset temperature threshold, the control valve 7 automatically adjusts its opening state according to the preset control strategy to achieve precise control of the medium flow direction.

[0067] In this embodiment, the phase change electric water heater also includes a controller 21 and a housing 22. The controller 21 is installed in the housing 22. The outlet of the second water outlet pipe 8 and the inlet of the water inlet pipe 3 both extend out of the housing 22. The controller 21 can serve as the core of the whole machine control, and collect signals such as the inlet water, the heat storage module of the water tank 201, the phase change heat storage module 1, and the outlet water temperature in real time. According to its program logic, it controls the coordination of various components of the water circuit and the heating components to achieve preheating of the inlet water, phase change heat transfer with small temperature difference, and constant temperature outlet water control. At the same time, it completes fault protection such as over-temperature and dry burning to ensure the safe and efficient operation of the equipment.

[0068] Optionally, the phase change electric water heater also includes a second temperature sensor 18 and a third temperature sensor 19. The second temperature sensor 18 is used to detect the temperature of the phase change heat transfer medium 102, and the third temperature sensor 19 is used to detect the temperature inside the water tank preheating module 2. By setting the second temperature sensor 18 and the third temperature sensor 19, the system can obtain independent temperature information of the two key links, the phase change heat transfer medium 102 and the preheating side, respectively. This provides accurate and reliable data support for the controller 21 to perform multiple control logics such as heat storage start / stop judgment, heat release switching decision, and overheat protection, thereby realizing refined perception and intelligent control of the system's operating status.

[0069] Optionally, the phase change electric water heater also includes a second electric heater 10, a second bypass pipe 11, and a flow regulating valve 12. The second electric heater 10 is installed on the second outlet pipe 8 and is located upstream of the connection between the second bypass pipe 11 and the second outlet pipe 8. The second bypass pipe 11 is connected between the inlet pipe 3 and the second outlet pipe 8. The flow regulating valve 12 is installed on the second bypass pipe 11 and is used to regulate the water flow rate within the second bypass pipe 11. With this design, the second heater acts as an auxiliary heat source to provide secondary heating compensation for the hot water flowing out of the heat storage body. It can quickly replenish the heat of the hot water flowing through the heating pipe, ensuring that the terminal outlet water temperature remains stable within the target range. This effectively compensates for the temperature drop caused by insufficient heat storage, and is especially suitable for heating guarantee scenarios with large-flow continuous water use or extreme low-temperature conditions. At the same time, by adjusting the valve core opening of the flow regulating valve 12, the flow rate of cold water flowing through the second bypass pipe 11 is precisely controlled, thereby realizing the proportional mixing and distribution of cold water and hot water in the heating pipeline, ensuring that the output water temperature of the heating pipe quickly approaches and stabilizes at the preset target temperature.

[0070] Furthermore, the phase change electric water heater also includes a fourth temperature sensor 20, which is installed on the second outlet pipe 8 and is located upstream of the connection between the second bypass pipe 11 and the second outlet pipe 8. The controller 21 responds to the temperature signal of the fourth temperature sensor 20 and can actively control the valve core opening of the flow regulating valve 12.

[0071] Optionally, the phase change electric water heater further includes an electromagnetic switch valve 13, a water pump 14, and a second connecting pipe 15. The second connecting pipe 15 is connected between the inlet pipe 3 and the second outlet pipe 8. The electromagnetic switch valve 13 is installed on the second connecting pipe 15 and is used to control the flow of water in the second connecting pipe 15. The water pump 14 is installed on the inlet pipe 3 and is located downstream of the connection between the second connecting pipe 15 and the inlet pipe 3; or, the water pump 14 is installed on the second outlet pipe 8 and is located upstream of the connection between the second connecting pipe 15 and the second outlet pipe 8; or, the water pump 14 is installed on the first bypass pipe 9; or, the water pump 14 is installed on the second connecting pipe 15.

[0072] With this configuration, driven by the water pump 14, when the heat 104 of the phase change heat medium is insufficient, an internally closed heat storage circulation loop can be formed. Water flows through the second heat exchange tube 202 to absorb heat from the liquid heat exchange medium to form energy storage hot water. Then, it enters the first heat exchange tube 103 through the first connecting pipe 6 to release heat to the phase change heat medium 102 in the heat storage body for heat storage. The energy storage hot water, after its temperature drops, flows out to the first outlet pipe 4 and passes through the control valve 7, the second outlet pipe 8, and the second electric heater 10 in sequence. Finally, it returns to the second heat exchange tube 202 through the second connecting pipe 15, continuously circulating, so that the phase change heat medium 102 can reach the heat storage set value in an orderly manner in the internal circulation, thereby reducing the dependence on external energy and improving the heat storage efficiency and energy utilization rate.

[0073] Optionally, the phase-change electric water heater also includes a water proportional valve 16. The water proportional valve 16 is located downstream of the connection point between the second connecting pipe 15 and the water inlet pipe 3, and is used to regulate the water flow rate in the water inlet pipe 3. By assembling the water proportional valve 16 in the system pipeline, it is used to adjust the water flow rate in the pipeline in real time. This valve continuously and precisely linearly adjusts the inlet water flow rate by changing the valve core opening according to system operating requirements or set parameters, thereby achieving dynamic control of the water flow rate. This adjustment mechanism not only meets the flow rate requirements under different water usage scenarios but also works in conjunction with the heat storage stage, indirectly controlling the water temperature by adjusting the inlet water flow rate, thus avoiding large fluctuations in the outlet water temperature. Simultaneously, precise flow control also helps reduce unnecessary water supply energy consumption, further improving overall resource utilization efficiency.

[0074] In this embodiment, the phase change electric water heater also includes a water flow sensor 23. The water flow sensor 23 is installed in the inlet pipe 3 and located upstream of the connection between the second bypass pipe 11 and the inlet pipe 3. It is used to monitor the instantaneous water flow and cumulative flow value flowing through the inlet pipe 3 in real time. Based on this flow signal, the controller 21 can accurately determine the user's water usage status (such as start / stop, large / small flow switching) and water consumption, and accordingly coordinate with the heating system, water proportional valve 16 and other actuators to perform adaptive adjustments, thereby achieving on-demand heating and dynamic matching. It should be noted that during the hot water operation, if the user has a need for increased pressure and flow or the water flow sensor 23 detects that the water flow information is lower than the minimum water flow setting value, the controller 21 will control the water pump 14 to run to achieve the effect of increased pressure and flow.

[0075] This embodiment also provides an operation method for a phase change electric water heater, based on controller control logic, responding to independent hot water usage states and user-unused hot water states, including the following steps:

[0076] In standby mode, control valve 7 is in the position connecting the first bypass pipe 9 and the second outlet pipe 8. When the user turns on the water terminal equipment, tap water will flow from the inlet of the inlet pipe 3 through the water flow sensor 23. Then the water flow sensor 23 will feed back the real-time detected water flow signal to the controller 21, so that the controller 21 responds to the hot water use status and enters the hot water use operation control mode.

[0077] At this time, in response to the user's hot water usage status, tap water will sequentially pass through the water flow sensor 23, water proportioning valve 16, and water pump 14 in the inlet pipe 3 into the second heat exchange tube 202 inside the water tank 201. The tap water absorbs heat from the liquid heat exchange medium in the water tank 201 through the second heat exchange tube 202 for preheating. After being preheated to a certain temperature, it flows out from the outlet of the second heat exchange tube 202 and flows through the first connecting pipe 6 to the first temperature sensor 17. The first temperature sensor 17 detects the first outlet water temperature of the water tank preheating module 2. If the first outlet water temperature is not less than the target temperature of the second outlet pipe 8, the tap water will be preheated. If the target outlet water temperature is set, the control valve 7 is used to connect the second outlet pipe 8 with the first bypass pipe 9, so that the water preheated by the water tank preheating module 2 flows through the first connecting pipe 6 and then sequentially through the first bypass pipe 9 and the second outlet pipe 8 for heating. If the first outlet water temperature is lower than the target outlet water temperature of the second outlet pipe 8, the control valve 7 is used to connect the second outlet pipe 8 with the first outlet pipe 4, so that the water preheated by the water tank preheating module 2 continues to flow through the first connecting pipe 6 and the first heat exchange pipe 103 to absorb the heat of the phase change heat medium 102, and then sequentially flows out from the first outlet pipe 4 and the second outlet pipe 8 for heating and use by the user.

[0078] Specifically, when the heat stored in the water tank preheating module 2 and the phase change heat storage module 1 gradually decreases, if the temperature of the liquid heat exchange medium in the water tank 201 falls below the first preset temperature, the first electric heater 5 is activated to heat the liquid heat exchange medium in the water tank 201. The first preset temperature is not lower than the target outlet water temperature. Then, through temperature feedback from the fourth temperature sensor 20, it is ensured that the hot water outlet temperature is the target outlet water temperature.

[0079] Specifically, if the real-time outlet water temperature of the second outlet pipe 8 is lower than the target outlet water temperature, the second electric heater 10 is activated to heat the water flowing through the second outlet pipe 8, so that the real-time outlet water temperature of the second outlet pipe 8 reaches the target outlet water temperature. If the real-time outlet water temperature of the second outlet pipe 8 is higher than the target outlet water temperature, the flow regulating valve 12 is controlled to increase the water flow rate of the second bypass pipe 11, so that the real-time outlet water temperature of the second outlet pipe 8 reaches the target outlet water temperature. It should be noted that if the second electric heater 10 still cannot reach the target outlet water temperature by heating the water flowing through the second outlet pipe 8, the controller will control the water proportional valve to adjust the main water flow rate, gradually reducing the main water flow rate (but ensuring the minimum water flow rate actually used), so that the real-time outlet water temperature after preheating reaches the target outlet water temperature.

[0080] With this configuration, the first electric heater 5 preheats the water tank preheating module 2 and the phase change heat transfer medium 102. The water tank preheating module 2 serves as the primary heat source, significantly reducing the heat exchange temperature difference between the inlet water and the phase change heat storage module 1. This improves the heating effect and prevents low-temperature cold water from directly impacting the heat exchange surface of the first heat exchange tube 103. Under stable heat exchange conditions with a small temperature difference, the phase change heat transfer medium 102 can undergo phase change solidification layer by layer in an orderly manner, avoiding the problem of instantaneous rapid solidification of the surface layer to form a dense solid insulation layer. The latent heat stored inside the phase change heat transfer medium 102 can be released steadily, completely, and continuously, improving its heat exchange efficiency. This eliminates severe hot and cold alternation stress, preventing aging problems such as cracking, delamination, and performance degradation that may occur in the phase change heat transfer medium 102 under the impact of cold water, effectively extending its service life. The first outlet water temperature of the preheating module 2 is monitored in real time to provide a basis for control decisions. The control valve 7 acts as a path switching actuator and accurately controls the water flow to switch between the two branches based on the temperature judgment result. The first bypass pipe 9 and the second outlet pipe 8 form a "direct supply path". When the first outlet water temperature reaches the target outlet water temperature, the water flows directly through this path, avoiding the ineffective intervention of the phase change heat medium 102, reducing its thermal cycle fatigue, and improving its heat exchange efficiency. The first outlet pipe 4 and the first heat exchange tube 103 containing the phase change heat medium 102 form a "heat supplement path". When the first outlet water temperature does not reach the target outlet water temperature, the water flow is forced into this path. When flowing through the first heat exchange tube 103, it efficiently absorbs the latent heat released by the phase change heat medium 102 and achieves secondary precise heating. In this design, the on-demand switching mechanism of control valve 7 ensures the tiered utilization of thermal energy between the water tank preheating module 2 and the phase change heat storage medium 102—prioritizing the use of primary preheating energy and only calling upon high-density phase change heat storage when insufficient, thereby improving overall heat exchange efficiency. Simultaneously, the direct supply mode via the first bypass pipe 9 significantly reduces the number of charge-discharge cycles of the phase change heat storage medium 102 under unnecessary operating conditions, delaying its phase change stratification and thermal performance degradation, fundamentally extending the service life of the first heat exchange tube 103 and the phase change heat storage unit. Ultimately, hot water at the target temperature is stably output at the second outlet pipe 8, achieving a synergistic unity of enhanced heat exchange and improved durability.

[0081] In response to the user's lack of hot water, as hot water continues to be used, the heat stored in the water tank preheating module 2 and the phase change heat storage module 1 gradually decreases. When the third temperature sensor 19 detects that the temperature of the liquid heat exchange medium in the water tank preheating module 2 is lower than the second preset temperature (the second preset temperature is not lower than the first preset temperature), the controller 21 will switch to a control mode for the individual water tank preheating module 2 to store heat. Specifically, the controller 21 starts the first electric heater 5 to heat the liquid heat exchange medium in the water tank 201. After the third temperature sensor 19 detects that the temperature of the liquid heat exchange medium in the water tank preheating module 2 has reached the second preset temperature, the heat storage mode process of the water tank preheating module 2 is completed.

[0082] At this time, the temperature of the phase change heat exchange medium 102 of the phase change heat storage module 1 is simultaneously acquired. If the second temperature sensor 18 detects that the temperature of the phase change heat exchange medium 102 in the heat storage body 101 is less than the third preset temperature (the third preset temperature is greater than the target outlet water temperature), the controller 21 will enter the control mode for the phase change heat storage module 1 to store heat and use. The controller 21 controls the control valve 7 to cut off the connection between the first bypass pipe 9 and the first connecting pipe 6, so that the second outlet pipe 8 and the first outlet pipe 4 are in a direct connection state, and controls the electromagnetic switch valve 13 to start and open. At the same time, the water pump 14 is driven to run. Under the drive of the water pump 14, the water flow in the second heat exchange tube 202 in the water tank 201 absorbs heat from the liquid heat exchange medium to form energy storage hot water. The water flows from the outlet of the second heat exchange tube 202 through the first connecting pipe 6, and then the energy storage hot water temperature information is fed back through the first temperature sensor 17. If the first outlet water temperature is less than the third preset temperature, the controller 21 controls the water proportional valve 16 to adjust the energy storage hot water flow rate, gradually reducing the water flow rate, so that the first outlet water temperature reaches the third preset temperature. During the process, the stored hot water that meets the temperature requirements enters the first heat exchange tube 103 inside the heat storage body 101 and releases heat to the phase change heat medium 102 inside the heat storage body 101 for heat storage. The stored hot water, after its temperature drops, flows out to the first outlet pipe 4, passes through the control valve 7, the second outlet pipe 8, and the second electric heater 10 in sequence, and finally flows through the second connecting pipe 15, through the electromagnetic switch valve 13 and the water proportion valve 16, and returns to the water pump 14. The above process is repeated continuously for heat storage.

[0083] It should be noted that when the water proportional valve 16 adjusts the water flow rate to the minimum water flow rate Lmin, and the first outlet water temperature is lower than the third preset temperature, the controller 21 prioritizes starting the first electric heater 5 to heat the liquid heat exchange medium in the heating water tank 201, thereby increasing the energy storage hot water temperature of the second heat exchange tube 202 so that the first outlet water temperature reaches the third preset temperature. If the conditions are still not met, the controller 21 continues to simultaneously start the second electric heater 10 to heat the energy storage hot water flowing through the second outlet water pipe 8, and at the same time, the controller 21 simultaneously links and adjusts the water proportional valve 16 to adjust the energy storage hot water flow rate so that the first outlet water temperature reaches the third preset temperature. The above process is repeated continuously until the second temperature sensor 18 detects that the temperature of the phase change heat exchange medium 102 in the heat storage body 101 is greater than or equal to the second preset temperature. At this time, the heat storage mode process of the phase change heat storage module 1 is completed.

[0084] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A phase-change electric water heater, characterized in that, include: A phase change thermal energy storage module (1) includes a thermal energy storage body (101), a phase change thermal energy medium (102), and a first heat exchange tube (103). The first heat exchange tube (103) is disposed inside the thermal energy storage body (101), and the outer wall of the first heat exchange tube (103) is provided with a plurality of heat exchange protrusions (1031) along the circumferential direction. The plurality of heat exchange protrusions (1031) are distributed at intervals along the extension direction of the first heat exchange tube (103). The phase change thermal energy medium (102) is filled inside the thermal energy storage body (101), and the phase change thermal energy medium (102) wraps the outer wall of the first heat exchange tube (103) and the heat exchange protrusions (1031). Water tank preheating module (2), the outlet of the water tank preheating module (2) is connected to the inlet of the first heat exchange tube (103); Water inlet pipe (3), which is connected to the water inlet of the water tank preheating module (2); The first water outlet pipe (4) is connected to the outlet of the first heat exchange pipe (103); The first electric heater (5) is used to heat the water tank preheating module (2) and the phase change heat medium (102).

2. The phase change electric water heater according to claim 1, characterized in that, The water tank preheating module (2) includes a water tank (201) and a second heat exchange tube (202). The water tank (201) is used to store liquid heat exchange medium. The first electric heater (5) and the second heat exchange tube (202) are both installed in the water tank (201). The inlet of the second heat exchange tube (202) is connected to the inlet pipe (3), and the outlet of the second heat exchange tube (202) is connected to the inlet of the first heat exchange tube (103).

3. The phase-change electric water heater according to claim 1, characterized in that, The phase change electric water heater also includes a first connecting pipe (6), a control valve (7), a second outlet pipe (8), and a first bypass pipe (9). The outlet of the water tank preheating module (2) is connected to the inlet of the first heat exchange pipe (103) through the first connecting pipe (6). The inlet of the first bypass pipe (9) is connected to the first connecting pipe (6). The outlet of the first outlet pipe (4) and the outlet of the first bypass pipe (9) are respectively connected to the inlet of the second outlet pipe (8) through the control valve (7). The control valve (7) is used to control the second outlet pipe (8) to selectively connect to the first outlet pipe (4) or the first bypass pipe (9).

4. The phase change electric water heater according to claim 3, characterized in that, The phase change electric water heater also includes a second electric heater (10), a second bypass pipe (11), and a flow regulating valve (12). The second electric heater (10) is installed on the second outlet pipe (8) and is located upstream of the connection between the second bypass pipe (11) and the second outlet pipe (8). The second bypass pipe (11) is connected between the inlet pipe (3) and the second outlet pipe (8). The flow regulating valve (12) is installed on the second bypass pipe (11) and is used to regulate the water flow in the second bypass pipe (11).

5. The phase-change electric water heater according to claim 3, characterized in that, The phase change electric water heater also includes an electromagnetic switch valve (13), a water pump (14) and a second connecting pipe (15). The second connecting pipe (15) is connected between the water inlet pipe (3) and the second water outlet pipe (8). The electromagnetic switch valve (13) is installed on the second connecting pipe (15) and is used to control the flow of water in the second connecting pipe (15). The water pump (14) is located downstream of the inlet pipe (3) and the connection point between the second connecting pipe (15) and the inlet pipe (3); or, the water pump (14) is located upstream of the connection point between the second connecting pipe (15) and the second outlet pipe (8); or, the water pump (14) is located on the first bypass pipe (9); or, the water pump (14) is located on the second connecting pipe (15).

6. The phase-change electric water heater according to claim 5, characterized in that, The phase change electric water heater also includes a water proportioning valve (16), which is located downstream of the water inlet pipe (3) and the connection point between the second connecting pipe (15) and the water inlet pipe (3), and is used to adjust the water flow rate in the water inlet pipe (3).

7. The phase change electric water heater according to claim 3, characterized in that, The phase change electric water heater also includes a first temperature sensor (17), which is disposed on the first connecting pipe (6).

8. The phase-change electric water heater according to any one of claims 1-7, characterized in that, The phase change electric water heater also includes a second temperature sensor (18) and a third temperature sensor (19). The second temperature sensor (18) is used to detect the temperature of the phase change heat transfer medium (102), and the third temperature sensor (19) is used to detect the temperature inside the water tank preheating module (2).

9. A method for operating a phase change electric water heater, the phase change electric water heater comprising a phase change heat storage module (1), a water tank preheating module (2), an inlet pipe (3), a first outlet pipe (4), a first electric heater (5), a control valve (7), a second outlet pipe (8), a first bypass pipe (9), and a first temperature sensor (17), the phase change heat storage module (1) comprising a heat storage body (101), a phase change heat transfer medium (102), and a first heat exchange tube (103), the first heat exchange tube (103) being disposed within the heat storage body (101), the phase change heat transfer medium (102) being filled within the heat storage body (101), and the phase change heat transfer medium (102) enveloping the first heat exchange tube (103), the inlet pipe (3) and the first outlet pipe (4) being connected to the first outlet pipe (5), the control valve (7), the second outlet pipe (8), the first bypass pipe (9), and the first temperature sensor (17). The inlet of the water tank preheating module (2) is connected, the first outlet pipe (4) is connected to the outlet of the first heat exchange pipe (103), the first electric heater (5) is used to heat the water tank preheating module (2) and the phase change heat medium (102), the inlet of the first bypass pipe (9) is connected to the outlet of the water tank preheating module (2) and the inlet of the first heat exchange pipe (103) respectively, the outlet of the first outlet pipe (4) and the outlet of the first bypass pipe (9) are connected to the inlet of the second outlet pipe (8) respectively through the control valve (7), the control valve (7) is used to control the second outlet pipe (8) to selectively connect to (4) or the first bypass pipe (9); characterized in that, The operation method of the phase change electric water heater includes: In response to the user's hot water usage status, the first outlet water temperature of the water tank preheating module (2) is detected; If the first outlet water temperature is not less than the target outlet water temperature of the second outlet pipe (8), then control the control valve (7) to make the second outlet pipe (8) and the first bypass pipe (9) connect, so that the water preheated by the water tank preheating module (2) flows out through the first bypass pipe (9) and the second outlet pipe (8) in sequence for heating; If the first outlet water temperature is less than the target outlet water temperature of the second outlet pipe (8), then the control valve (7) is controlled to connect the second outlet pipe (8) with the first outlet pipe (4), so that the water preheated by the water tank preheating module (2) continues to flow through the first heat exchange pipe (103) to absorb the heat of the phase change heat medium (102) and then flows out from the first outlet pipe (4) and the second outlet pipe (8) in sequence to provide heat.

10. The operation method of the phase change electric water heater according to claim 9, wherein the water tank preheating module (2) includes a water tank (201) and a second heat exchange tube (202), the water tank (201) is used to store a liquid heat exchange medium, the first electric heater (5) and the second heat exchange tube (202) are both disposed in the water tank (201), the inlet of the second heat exchange tube (202) is connected to the inlet pipe (3), and the outlet of the second heat exchange tube (202) is connected to the inlet of the first heat exchange tube (103), characterized in that, The operation method of the phase change electric water heater also includes: If the temperature of the liquid heat exchange medium in the water tank (201) is lower than the first preset temperature, the first electric heater (5) is activated to heat the liquid heat exchange medium in the water tank (201), wherein the first preset temperature is not lower than the target outlet water temperature.

11. The operating method of the phase change electric water heater according to claim 10, wherein the phase change electric water heater further comprises a second electric heater (10), a second bypass pipe (11), and a flow regulating valve (12), the second electric heater (10) is disposed on the second outlet pipe (8), the second electric heater (10) is located upstream of the connection between the second bypass pipe (11) and the second outlet pipe (8), the second bypass pipe (11) is connected between the inlet pipe (3) and the second outlet pipe (8), and the flow regulating valve (12) is disposed on the second bypass pipe (11), characterized in that, The operation method of the phase change electric water heater also includes: If the real-time outlet water temperature of the second outlet pipe (8) is less than the target outlet water temperature, the second electric heater (10) is activated to heat the water flowing through the second outlet pipe (8) so that the real-time outlet water temperature of the second outlet pipe (8) reaches the target outlet water temperature. If the real-time outlet water temperature of the second outlet pipe (8) is greater than the target outlet water temperature, the flow regulating valve (12) is controlled to increase the water flow of the second bypass pipe (11) so that the real-time outlet water temperature of the second outlet pipe (8) reaches the target outlet water temperature.

12. The operating method of the phase change electric water heater according to claim 11, characterized in that, The phase change electric water heater further includes an electromagnetic switch valve (13), a water pump (14), a second connecting pipe (15), and a second temperature sensor (18). The second connecting pipe (15) is connected between the inlet pipe (3) and the second outlet pipe (8). The electromagnetic switch valve (13) is installed on the second connecting pipe (15) and is used to control the flow of water in the second connecting pipe (15). The water pump (14) is installed on the inlet pipe (3) and is located downstream of the connection between the second connecting pipe (15) and the inlet pipe (3); or, the water pump (14) is installed on the second outlet pipe (8) and is located upstream of the connection between the second connecting pipe (15) and the second outlet pipe (8); or, the water pump (14) is installed on the first bypass pipe (9); or, the water pump (14) is installed on the second connecting pipe (15). The second temperature sensor (18) is used to detect the temperature of the phase change heat transfer medium (102). The operation method of the phase change electric water heater further includes: In response to the user's unused hot water status, if the temperature of the liquid heat exchange medium in the water tank (201) is lower than the second preset temperature, the first electric heater (5) is controlled to start; wherein the second preset temperature is not lower than the first preset temperature; If the temperature of the liquid heat exchange medium in the water tank (201) is not less than the second preset temperature, the first electric heater (5) is controlled to stop heating and the temperature of the phase change heat exchange medium (102) of the phase change heat storage module (1) is obtained; If the temperature of the phase change heat transfer medium (102) is less than the third preset temperature, the control valve (7) is controlled to connect the second outlet pipe (8) with the first outlet pipe (4), the electromagnetic switch valve (13) is opened and the water pump (14) is started, wherein the third preset temperature is greater than the target outlet water temperature; If the temperature of the phase change heat medium (102) is not less than the third preset temperature, control the electromagnetic switch valve (13) to close and stop the water pump (14).

13. The operating method of the phase change electric water heater according to claim 12, characterized in that, The phase change electric water heater further includes a water proportioning valve (16), which is disposed on the inlet pipe (3) and located downstream of the connection between the second connecting pipe (15) and the inlet pipe (3). The phase change electric water heater's operation method further includes: If the temperature of the phase change heat medium (102) is less than the third preset temperature, the control valve (7) is controlled to make the second water outlet pipe (8) connected to the first water outlet pipe (4), the electromagnetic switch valve (13) is opened and the water pump (14) is started. If the first outlet water temperature is lower than the third preset temperature, the water proportional valve (16) is controlled to adjust and reduce the water flow rate of the second connecting pipe (15) so that the first outlet water temperature reaches the third preset temperature.

14. The operating method of the phase change electric water heater according to claim 13, characterized in that, The operation method of the phase change electric water heater also includes: When the opening of the water proportional valve (16) is adjusted to the minimum and the first outlet water temperature is less than the third preset temperature, the first electric heater (5) is started to make the first outlet water temperature reach the third preset temperature.

15. The operating method of the phase change electric water heater according to claim 13, characterized in that, The control starts the first electric heater (5), and then includes: If the first outlet water temperature is lower than the third preset temperature, the second electric heater (10) is activated to make the first outlet water temperature reach the third preset temperature.

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