CN213542861U - Plate heat exchanger and water heater - Google Patents

Abstract

The utility model discloses a plate heat exchanger and a water heater, wherein the plate heat exchanger comprises a main body structure, a first pipeline and a second pipeline which are arranged in the main body structure in a penetrating way and are mutually independent, a temperature sensor, a heating module and a control module; the temperature sensor is used for acquiring the temperature value of the buffer solution; the control module is used for generating a first trigger signal when the temperature value is smaller than a first set threshold value and sending the first trigger signal to the heating module to start heating; the control module is also used for generating a second trigger signal to stop heating when the temperature value of the buffer solution is greater than or equal to a second set threshold value. The plate heat exchanger of the utility model adds the heating module to heat the buffer solution in the buffer solution pipeline in time, thereby ensuring the first hot water outlet speed and stability when the user uses water again after water cut off; the water outlet waiting time of the user is reduced, and the use experience of the user is improved; meanwhile, the heating module can also reduce the temperature fluctuation of the plate heat exchanger, and further improve the hot water outlet stability.

Description

Plate heat exchanger and water heater

Technical Field

The utility model relates to a water heater technical field, in particular to plate heat exchanger and water heater.

Background

The user temporarily stops the water (for example wash hair, with the shower bath) in the use of water heater, and the time of opening the water use water heater goes out water and has great temperature variation because need consume the lower water of part temperature in outer pipeline earlier, then consume the higher water of temperature in the water heater. In addition, the water temperature is fluctuated due to the conditions of gas pressure, water flow fluctuation and the like, and the water temperature needs a long time to be recovered to a set value, so that the user experience is poor, and even the user can be scalded.

At present, a water mixing device is mainly added on a water outlet pipeline of a water heater, the water mixing device consists of a water inlet pipe, a water outlet pipe and a cavity container, and hot water can be mixed in the container before flowing out of a machine. However, this solution has the following problems: when water is discharged for the first time, hot water is mixed with cold water in the water mixing device, so that the temperature increase rate is reduced, and the time for a client to wait for hot water is increased; the heat exchange speed in the water mixing container is slow and the temperature is not easy to be uniform.

The water outlet condition of the water heater can be improved through the plate heat exchanger, but the existing plate heat exchanger generally has the problems that the time for firstly discharging hot water is long, and the water discharging stability cannot meet higher use requirements of users; although the conventional heat exchanger can store certain heat, when the heat exchanger is not used for a long time, the stored heat is gradually reduced along with the lapse of time, and the longer the time is, the lower the capability of maintaining the stability of the outlet water temperature is, so that the user experience is reduced; when the user stops water for a period of time and uses water again, the problem that the water output cannot meet the water using requirement of the user still exists.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is to provide a plate heat exchanger and water heater in order to overcome among the prior art the defect that plate heat exchanger can't satisfy the user to going out hot water speed and going out the operation requirement of hot water stability.

The utility model discloses an above-mentioned technical problem is solved through following technical scheme:

the utility model provides a plate heat exchanger, which comprises a main body structure, a first pipeline and a second pipeline which are arranged in the main body structure in a penetrating way and are mutually independent, a temperature sensor, a heating module and a control module;

the second pipeline is used for storing buffer liquid to exchange heat with water flowing through the first pipeline, and the temperature sensor and the heating module are arranged on the second pipeline;

the temperature sensor and the heating module are both electrically connected with the control module;

the temperature sensor is used for acquiring the buffer solution temperature value of the buffer solution in the second pipeline and sending the buffer solution temperature value to the control module;

the control module is used for comparing the buffer solution temperature value with a first set threshold value, generating a first trigger signal when the buffer solution temperature value is smaller than the first set threshold value, and sending the first trigger signal to the heating module, wherein the heating module is used for starting heating according to the first trigger signal so as to heat the buffer solution in the buffer solution pipeline;

the control module is further used for generating a second trigger signal and sending the second trigger signal to the heating module when the buffer solution temperature value is greater than or equal to a second set threshold value, and the heating module is used for stopping heating according to the second trigger signal;

wherein the second set threshold is greater than the first set threshold.

The temperature of the buffer solution is always kept at the preset buffer solution temperature through the arrangement of the heating device in the utility model; when setting up this heat exchanger in the water heater, can guarantee that the user temporarily stops the water and opens the water again and can both use satisfied leaving water temperature and go out water fastly at any time, further promoted user's use and experienced.

In addition, the electric heating device is added in the plate heat exchanger, so that the first hot water outlet time is shortened, the problem that the first hot water outlet of the existing water mixing device is slow is solved, the time for waiting for water outlet of a user is shortened, and the use experience of the user is improved; meanwhile, the auxiliary electric heating device can reduce the temperature fluctuation of the plate heat exchanger, and further improve the stability of hot water.

The utility model discloses a plate heat exchanger compares in current water admixing device, and the heat transfer is faster, even, and user's water is kept apart with the buffer solution, avoids quality of water to be polluted, has guaranteed user's water safety.

Preferably, the main structure of the plate heat exchanger comprises a cover plate, a bottom plate, a plurality of first metal sheets and a plurality of second metal sheets;

the first metal sheet and the second metal sheet are arranged between the cover plate and the bottom plate in a staggered and stacked mode, and the cover plate is covered on the bottom plate;

the cover plate is provided with a buffer water inlet hole, a user water inlet hole and a user water outlet hole;

buffer liquid flow channels are arranged on the surface of each first metal sheet, and each buffer liquid flow channel is communicated with the buffer liquid water inlet hole;

and each second metal sheet surface is provided with a user water flow channel, and each user water flow channel is communicated with the user water inlet hole and the user water outlet hole.

Preferably, the first metal sheet and the second metal sheet are sequentially stacked between the cover plate and the bottom plate.

Preferably, the first metal sheet comprises a first metal body, and the first metal body is provided with a first opening, a second opening, the buffer fluid channel and at least one third opening;

the first opening and the second opening are arranged outside the buffer liquid flow channel, and the third opening is arranged in the buffer liquid flow channel;

the second metal sheet comprises a second metal main body, and a fourth opening, a fifth opening, the user water flow channel and at least one sixth opening are formed in the second metal main body;

the fourth opening and the fifth opening are arranged in the user water flow channel, and the sixth opening is arranged outside the buffer liquid flow channel;

the first opening hole is communicated with the fourth opening hole, the second opening hole is communicated with the fifth opening hole, and the third opening hole is communicated with the sixth opening hole through connecting pipes;

wherein each of the third openings and the buffer flow channels form the second channel;

the fourth opening, the fifth opening, and the user water flow passage form the first pipe.

Preferably, the buffer solution runner with user's water runner all includes the holding tank, the border of holding tank has set firmly sealed the pad, the third trompil the fourth trompil and fifth trompil are all seted up and are corresponded in the holding tank.

Preferably, the plate heat exchanger further comprises an exhaust valve fixedly arranged on the main body structure and communicated with the inside of the main body structure;

the exhaust valve is used for exhausting air in the main body structure.

Preferably, the plate heat exchanger further comprises a drain valve fixedly arranged on the main body structure and communicated with the inside of the main body structure;

the drain valve is used for discharging liquid in the main body structure.

Preferably, the plate heat exchanger further comprises a liquid level sensor, and the liquid level sensor is arranged on the second pipeline;

the liquid level sensor is electrically connected with the control module and is used for collecting the liquid level value of the buffer solution in the second pipeline.

Preferably, the plate heat exchanger further comprises a pressure sensor disposed on the second pipe;

the pressure sensor is electrically connected with the control module and is used for collecting the pressure value of the buffer solution in the second pipeline.

The utility model also provides a water heater, the water heater includes foretell plate heat exchanger.

The utility model discloses an actively advance the effect and lie in:

(1) the plate heat exchanger of the utility model can keep the temperature of the buffer solution at the preset buffer solution temperature all the time through the arrangement of the heating device; when setting up this heat exchanger in the water heater, can guarantee that the user temporarily stops the water and opens the water again and can both use satisfied leaving water temperature and go out water fastly at any time, has promoted user's use and has experienced.

(2) Increase electric heater unit in plate heat exchanger for first hot water time, improved the problem that current water mixing device first goes out hot water slowly, it is long when reducing user's waiting to go out water, promoted user's use and experienced.

(3) The auxiliary electric heating device can reduce the temperature fluctuation of the plate heat exchanger, and further improve the stability of hot water.

(4) The utility model discloses a plate heat exchanger compares in current water admixing device, and the heat transfer is faster, even, and user's water is kept apart with the buffer solution, avoids quality of water to be polluted, has guaranteed user's water safety.

(5) The utility model discloses a plate heat exchanger is through designing two kinds of sheetmetals and alternate range upon range of setting in proper order in order to form the pipeline that is used for holding business turn over water pipeline and user hold the buffer solution, and the buffer solution that realizes the uniform temperature carries out timely heat transfer to the cold water that intakes to guarantee the stable purpose of water heater leaving water temperature.

Drawings

Fig. 1 is a first structural schematic diagram of a plate heat exchanger according to embodiment 1 of the present invention.

Fig. 2 is a first structural schematic diagram of a main structure in a plate heat exchanger according to embodiment 1 of the present invention.

Fig. 3 is a second schematic structural diagram of a main structure in a plate heat exchanger according to embodiment 1 of the present invention.

Fig. 4 is a second schematic structural diagram of the plate heat exchanger according to embodiment 1 of the present invention.

Fig. 5 is a schematic structural diagram of a water heater according to embodiment 2 of the present invention.

Detailed Description

The present invention is further illustrated by way of the following examples, which are not intended to limit the scope of the invention.

Example 1

As shown in fig. 1 and 2, the plate heat exchanger of the present embodiment includes a main body structure 1, a first pipeline L1 and a second pipeline L2 (see fig. 2) penetrating through the main body structure 1 and independent of each other, a temperature sensor 2, a heating module 3, a liquid level sensor 4, a pressure sensor 5, and a control module 6.

The second pipeline L2 is used for storing buffer solution to exchange heat with water flowing through the first pipeline L1, namely, the liquid for heat exchange (corresponding to the second pipeline) and the user water (corresponding to the first pipeline) in the heat exchanger exchange heat in a non-direct contact mode, so that the problems of scaling, deterioration and the like caused by more water in the heat exchanger are solved, the water quality is guaranteed, and the service life of the heat exchanger is prolonged.

The control module in the plate heat exchanger can be arranged in the main body structure or outside the main body structure; in addition, according to actual requirements (such as cost saving), a controller in equipment provided with the plate heat exchanger is directly adopted as a control module of the plate heat exchanger, and the plate heat exchanger can be controlled to be started or stopped to heat as long as temperature feedback of the plate heat exchanger can be received.

The temperature sensor 2 and the heating module 3 are both provided on the second line L2.

Wherein, the heating module can set up on the second pipeline surface, perhaps set up in the second pipeline all can, as long as can in time heat the buffer solution in the second pipeline. In addition, the heating module may be an existing electric heating device.

The temperature sensor 2 and the heating module 3 are both electrically connected with the control module 6;

the temperature sensor 2 is used for acquiring the buffer solution temperature value of the buffer solution in the second pipeline L2 and sending the buffer solution temperature value to the control module 6;

the control module 6 is used for comparing the buffer solution temperature value with a first set threshold value, generating a first trigger signal when the buffer solution temperature value is smaller than the first set threshold value and sending the first trigger signal to the heating module 3, and the heating module 3 is used for starting heating according to the first trigger signal so as to heat the buffer solution in the buffer solution pipeline;

the control module 6 is further configured to generate a second trigger signal and send the second trigger signal to the heating module 3 when the buffer solution temperature value is greater than or equal to a second set threshold value, and the heating module 3 is configured to stop heating according to the second trigger signal; wherein the second set threshold is greater than the first set threshold.

When the plate heat exchanger is installed in the water heater, the plate heat exchanger is replenished with water when the plate heat exchanger is used for the first time, and the plate heat exchanger can be normally used after the water replenishing is successful.

The working principle of the plate heat exchanger is as follows: after the water heater is started, the machine starts to output heat load to heat inlet water, an auxiliary heating device (namely a heating module) in the plate heat exchanger acts simultaneously, and the electric controller monitors outlet water temperature to adjust the machine load and the electric heating load; after short-term water cut-off, the temperature sensor in the plate heat exchanger monitors the temperature of the buffer solution in real time, and once the temperature of the buffer solution is lower than a set temperature N degree (specific values can be set according to actual conditions, for example, the temperature difference can be set to 5 ℃), the auxiliary heating mode is started to heat the buffer solution so as to prevent the reduction of the temperature of the buffer solution from influencing the speed and the stability of water outlet.

The temperature of the buffer solution is always kept at the preset buffer solution temperature through the arrangement of the heating device in the utility model; when setting up this heat exchanger in the water heater, can guarantee that the user temporarily stops the water and opens the water again and can both use satisfied leaving water temperature and go out water fastly at any time, further promoted user's use and experienced.

In addition, the electric heating device is added in the plate heat exchanger, so that the first hot water outlet time is shortened, the problem that the first hot water outlet of the existing water mixing device is slow is solved, the time for waiting for water outlet of a user is shortened, and the use experience of the user is improved; meanwhile, the auxiliary electric heating device can reduce the temperature fluctuation of the plate heat exchanger, and further improve the stability of hot water.

The utility model discloses a plate heat exchanger compares in current water admixing device, and the heat transfer is faster, even, and user's water is kept apart with the buffer solution, avoids quality of water to be polluted, has guaranteed user's water safety.

Specifically, as shown in fig. 3, the main structure 1 of the plate heat exchanger of the present embodiment includes a cover plate 7, a bottom plate 8, a plurality of first metal sheets 9, and a plurality of second metal sheets 10.

The first metal sheet 9 and the second metal sheet 10 are stacked between the cover plate 7 and the bottom plate 8, and the cover plate 7 is covered on the bottom plate 8; in an alternative embodiment, the first metal sheet 9 and the second metal sheet 10 are stacked in series between the cover plate 7 and the base plate 8.

The cover plate 7 is provided with a buffer water inlet hole P1, a user water inlet hole P2 and a user water outlet hole P3;

wherein, the surface of each first metal sheet 9 is provided with a buffer solution runner 11, and each buffer solution runner 11 is communicated with a buffer solution water inlet hole P1;

each of the second metal sheets 10 has a user water flow path 12 formed on a surface thereof, and each of the user water flow paths 12 is communicated with both of the user water inlet hole P2 and the user water outlet hole P3.

Specifically, the first metal sheet 9 comprises a first metal body 13, and a first opening 14, a second opening 15, a buffer fluid channel 11 and at least one third opening 16 are formed in the first metal body 13;

the first opening 14 and the second opening 15 are arranged outside the buffer fluid channel 11, and the third opening 16 is arranged in the buffer fluid channel 11;

the second metal sheet 10 comprises a second metal body 17, wherein the second metal body 17 is provided with a fourth hole 18, a fifth hole 19, a user water flow channel 12 and at least one sixth hole 20;

fig. 5 shows two third openings 16 on the first metal sheet 9, and two sixth openings 20 on the second metal sheet 10.

And a plurality of third openings and sixth openings (two openings are arranged in fig. 3) are arranged, so that the universality of the heat exchanger is ensured.

The fourth opening 18 and the fifth opening 19 are arranged in the user water flow passage 12, and the sixth opening 20 is arranged outside the buffer fluid flow passage 11;

wherein, buffer solution runner 11 and user water runner 12 all include the holding tank, and the border of holding tank has set firmly sealed the pad, and third trompil 16, fourth trompil 18 and fifth trompil 19 are all seted up in the holding tank that corresponds.

The first opening 14 is communicated with the fourth opening 18, the second opening 15 is communicated with the fifth opening 19, and the third opening 16 is communicated with the sixth opening 20 through connecting pipes.

In an implementation scheme, the connecting pipe may be a sealing gasket structure between the connecting holes, or may be other implementation structures, as long as the buffer solution pipeline and the user water pipeline can be independent and staggered with each other, so as to achieve the effect of effective heat exchange.

Each third opening 16 and the buffer liquid flow channel 11 form a second pipeline L2, the fourth opening 18, the fifth opening 19 and the user water flow channel 12 form a first pipeline L1 to form completely independent pipelines, so that the buffer liquid and the user water for heat exchange in the heat exchanger adopt indirect contact type heat exchange, the problems of scaling, deterioration and the like caused by more water in the heat exchanger are reduced, the water quality is ensured, and the service life of the heat exchanger is prolonged.

The principle of forming two completely independent pipelines is as follows:

the buffer solution flow channel 11 is used for accommodating a buffer solution flowing from the buffer solution inlet hole P1, guiding the buffer solution to the buffer solution flow channel 11 of the next first metal sheet through the sixth opening hole 20 through the third opening hole 16 of the next first metal sheet, and so on, thereby completing injection of the buffer solution, and when the buffer solution is injected, the buffer solution does not need to flow.

The user water flows from the user water inlet hole P2 through the first opening 14 of the first metal sheet into the user water flow channel 12 of the second metal sheet, then flows through the fourth opening 18 through the first opening 14 of the next first metal sheet into the user water flow channel 12 of the next second metal sheet, and so on, and finally flows out through the fifth opening 19 of the second metal sheet closest to the cover plate 7 to the second opening 15 of the first metal sheet, and further flows out of the heat exchanger through the user water outlet hole P3.

In the heat exchanger of the present embodiment, the number of metal sheets, the material of the metal sheets, the number of holes in the metal sheets, the number of holes provided in the cover plate and the bottom plate, the communication manner, and the like can be adjusted according to actual conditions.

As shown in fig. 4, the plate heat exchanger of this embodiment further includes an exhaust valve 22 and a drain valve 23, which are fixedly disposed on the main structure 1 and are communicated with the inside of the main structure 1. Wherein, a in the figure corresponds to the position of water used by a user, and b in the figure corresponds to the position of buffer solution.

The exhaust valve 22 is used for exhausting air in the main body structure 1 and exhausting hot air in the plate heat exchanger, so that the use safety of the plate heat exchanger is ensured.

Typically the exhaust valve position should be located on top of the plate heat exchanger, depending on the particular mounting orientation of the heat exchanger. Of course, the position can be adjusted according to actual requirements. In addition, the exhaust valve adopts the existing exhaust valve structure, and the specific exhaust process belongs to the mature technology in the field, so the detailed description is omitted here.

The drain valve 23 is used for draining the liquid in the main body structure 1, for example, when the water heater is not used for a long time or is maintained, the drain valve is opened to drain the liquid in the plate heat exchanger, so as to avoid the accumulated water from forming dirt in the plate heat exchanger, causing deterioration and the like to damage the plate heat exchanger, and prolong the service life of the water heater.

Generally, the drain valve needs to be installed at the lowest part of the heat exchanger or a pipeline communicated with the heat exchange, and the drain valve depends on the actual installation position of the heat exchanger. Of course, the position can be adjusted according to actual requirements.

The heat exchanger of this embodiment belongs to plate heat exchanger, and the plate heat exchanger of this embodiment compares in current water admixing device, has advantages such as small, simple structure, heat transfer speed are fast and reliable operation is stable.

The temperature of the buffer solution is always kept at the preset buffer solution temperature through the arrangement of the heating device; when the heat exchanger is arranged in a water heater, a user can be guaranteed to use a satisfactory outlet water temperature at any time when the water is temporarily stopped and then the water is started, the outlet water speed is high, and the use experience of the user is further improved; the electric heating device is added in the plate heat exchanger, so that the first hot water outlet time is shortened, the problem that the first hot water outlet of the existing water mixing device is slow is solved, the time for waiting for water outlet of a user is shortened, and the use experience of the user is improved; meanwhile, the auxiliary electric heating device can reduce the temperature fluctuation of the plate heat exchanger, and further improve the stability of hot water. In addition, the plate heat exchanger of this embodiment compares in current water admixing device, has advantages such as small, simple structure.

Example 2

The water heater of the present embodiment includes the plate heat exchanger of embodiment 1.

As shown in fig. 5, the first pipe of the plate heat exchanger is disposed on the main water outlet pipe of the water heater. Wherein, a in the figure corresponds to the position of water used by a user, and b in the figure corresponds to the position of buffer solution.

The water heater of the embodiment further comprises a water replenishing valve 24, and the water replenishing valve 24 is a one-way valve.

One end of the water replenishing valve 24 is communicated with a main water inlet pipeline of the water heater, and the other end of the water replenishing valve 24 is communicated with a water inlet end of a second pipeline;

the water replenishing valve 24 is electrically connected with a controller in the water heater, the controller in the water heater is used for sending a trigger signal to the water replenishing valve 24, and the water replenishing valve 24 is opened or closed according to the trigger signal, so that the buffer solution is injected into the second pipeline to be started or stopped.

When the water heater is used for the first time, the water replenishing valve 24 should be controlled to open to replenish water (i.e. inject buffer solution) into the second pipeline of the heat exchanger, and the separated independent arrangement of the first pipeline and the second pipeline enables the liquid thermally buffered by the user not to be in direct contact with the water used by the user. When the water-saving lamp is normally used later, water supplement is not needed (except the case of not using for a long time, needing maintenance and the like).

In order to realize accurate control of the water replenishing valve 24, whether the second pipeline is filled with the buffer solution or not is automatically detected by arranging sensors such as a liquid level sensor and a pressure sensor in the plate heat exchanger, or the detection can be determined in a manual detection mode.

Specifically, a liquid level sensor is arranged in the plate heat exchanger, and the liquid level sensor is arranged on the second pipeline;

the liquid level sensor is electrically connected with a controller in the water heater and is used for acquiring the liquid level value of the buffer solution in the second pipeline and sending the liquid level value to the controller in the water heater;

the controller in the water heater is used for generating a trigger signal to trigger the water replenishing valve 24 to be opened when the liquid level value is smaller than a first set threshold value; and when the liquid level value reaches a first set threshold value, controlling the water replenishing valve 24 to be closed.

Or the like, or, alternatively,

a pressure sensor is arranged in the heat exchanger and is arranged on the second pipeline;

the pressure sensor is electrically connected with a controller in the water heater and is used for acquiring the pressure value of the buffer solution in the second pipeline and sending the pressure value to the controller in the water heater;

the controller in the water heater is used for generating a trigger signal to trigger the water replenishing valve 24 to be opened when the pressure value is smaller than a second set threshold value; and when the pressure value reaches a second set threshold value, controlling the water replenishing valve 24 to be closed.

The water heater is provided with the plate heat exchanger, the plate heat exchanger is additionally arranged in the main water outlet pipeline of the water heater, when the water heater is started for the first time after being closed and heated, the user water inlet and outlet pipeline in the plate heat exchanger is adopted to exchange heat with the buffer liquid pipeline, and when the water outlet temperature reaches the preset temperature, the temperature in the two pipelines reaches heat exchange balance; when the user stops water for a period of time and then begins to use water again in the service cycle, the buffer liquid pipeline exchanges heat with the water for the user in time, the good heat exchange performance of the plate heat exchanger is utilized to achieve quick response, the effect of weakening temperature fluctuation is achieved, the advantages of high heat exchange speed and uniform temperature after heat exchange are achieved, temperature change caused by fluctuation of water flow, pressure and the like is effectively avoided, namely no matter how long the user stops water for a long time, water can be discharged quickly all the time, the water outlet temperature meets the use comfort level of the user, and the use experience of the user is improved; meanwhile, the temperature increase speed is high when water is discharged for the first time, so that the time for a user to wait for hot water to be discharged is shortened, the use experience of the user is further improved, and the product performance of the water heater is improved.

Although specific embodiments of the present invention have been described above, it will be understood by those skilled in the art that this is by way of example only and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and the principles of the present invention, and these changes and modifications are all within the scope of the present invention.

Claims (10)

1. A plate heat exchanger is characterized by comprising a main body structure, a first pipeline and a second pipeline which are arranged in the main body structure in a penetrating manner and are mutually independent, a temperature sensor, a heating module and a control module;

the second pipeline is used for storing buffer liquid to exchange heat with water flowing through the first pipeline, and the temperature sensor and the heating module are arranged on the second pipeline;

the temperature sensor and the heating module are both electrically connected with the control module;

the temperature sensor is used for acquiring the buffer solution temperature value of the buffer solution in the second pipeline and sending the buffer solution temperature value to the control module;

the control module is used for comparing the buffer solution temperature value with a first set threshold value, generating a first trigger signal when the buffer solution temperature value is smaller than the first set threshold value, and sending the first trigger signal to the heating module, wherein the heating module is used for starting heating according to the first trigger signal so as to heat the buffer solution in the buffer solution pipeline;

the control module is further used for generating a second trigger signal and sending the second trigger signal to the heating module when the buffer solution temperature value is greater than or equal to a second set threshold value, and the heating module is used for stopping heating according to the second trigger signal;

wherein the second set threshold is greater than the first set threshold.

2. A plate heat exchanger according to claim 1, wherein the body structure of the plate heat exchanger comprises a cover plate, a base plate, a plurality of first metal sheets and a plurality of second metal sheets;

the first metal sheet and the second metal sheet are arranged between the cover plate and the bottom plate in a staggered and stacked mode, and the cover plate is covered on the bottom plate;

the cover plate is provided with a buffer water inlet hole, a user water inlet hole and a user water outlet hole;

buffer liquid flow channels are arranged on the surface of each first metal sheet, and each buffer liquid flow channel is communicated with the buffer liquid water inlet hole;

and each second metal sheet surface is provided with a user water flow channel, and each user water flow channel is communicated with the user water inlet hole and the user water outlet hole.

3. A plate heat exchanger according to claim 2, wherein the first metal sheet and the second metal sheet are arranged in between the cover plate and the base plate in a sequentially alternating stack.

4. A plate heat exchanger according to claim 2 or 3, wherein the first metal sheet comprises a first metal body with a first opening, a second opening, the buffer fluid channel and at least one third opening;

the first opening and the second opening are arranged outside the buffer liquid flow channel, and the third opening is arranged in the buffer liquid flow channel;

the second metal sheet comprises a second metal main body, and a fourth opening, a fifth opening, the user water flow channel and at least one sixth opening are formed in the second metal main body;

the fourth opening and the fifth opening are arranged in the user water flow channel, and the sixth opening is arranged outside the buffer liquid flow channel;

the first opening hole is communicated with the fourth opening hole, the second opening hole is communicated with the fifth opening hole, and the third opening hole is communicated with the sixth opening hole through connecting pipes;

each of the third openings and the buffer fluid flow channels form the second conduit;

the fourth opening, the fifth opening, and the user water flow passage form the first pipe.

5. The plate heat exchanger of claim 4, wherein the buffer fluid channel and the user water channel each comprise a receiving groove, a gasket is fixedly disposed at an edge of the receiving groove, and the third opening, the fourth opening, and the fifth opening are disposed in the corresponding receiving grooves.

6. A plate heat exchanger according to claim 1, further comprising an exhaust valve secured to the body structure and communicating with the interior of the body structure;

the exhaust valve is used for exhausting air in the main body structure.

7. The plate heat exchanger of claim 1, further comprising a drain valve secured to the body structure and in communication with the interior of the body structure;

the drain valve is used for discharging liquid in the main body structure.

8. The plate heat exchanger of claim 1, further comprising a liquid level sensor disposed on the second conduit;

the liquid level sensor is electrically connected with the control module and is used for collecting the liquid level value of the buffer solution in the second pipeline.

9. A plate heat exchanger according to claim 1, further comprising a pressure sensor arranged on the second line;

the pressure sensor is electrically connected with the control module and is used for collecting the pressure value of the buffer solution in the second pipeline.

10. A water heater, characterized in that it comprises a plate heat exchanger according to any of claims 1-9.

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