Solar water heater capable of controlling water outlet temperature

Abstract

The invention provides an outlet water temperature controlled solar water heater which comprises a heat collecting pipe and a water tank, the heat collecting pipe comprises an evaporation end and a condensation end, the evaporation end absorbs solar heat, and the condensation end is inserted into the water tank and releases heat to water in the water tank; the water heater is characterized in that the water tank is divided into N independently-heated areas, N is larger than or equal to 2, the heat exchange areas of the condensation ends of the areas are different, the heat exchange areas of the condensation ends of the N areas are gradually increased, each area is provided with an independent water inlet and an independent water outlet, the water outlet is connected with a water user, and a water outlet valve is arranged on the water outlet. A temperature sensor is arranged in each area and used for detecting the temperature of heated water in the area, the temperature sensors and the water outlet valves are in data connection with a controller, a user inputs the water temperature, the user is controlled to determine the opening degree of the water outlet valves according to the temperature detected by the temperature sensors, and therefore the water temperature input by the user is achieved. According to the solar water heater with the rapid temperature control function, water at different temperatures can be rapidly output, and the requirements of users can be rapidly met.

Description

Technical Field

[0001] The present invention relates to a solar water heater, and more particularly to a solar water heater with outlet water temperature control. Background Art

[0002] With the rapid development of modern social economy, the demand for energy by human beings is increasing. However, the reserves of traditional energy sources such as coal, oil, and natural gas are continuously decreasing and becoming increasingly scarce, resulting in continuous price increases. At the same time, the environmental pollution problems caused by conventional fossil fuels are becoming more and more serious, which greatly restricts the development of society and the improvement of the quality of human life. The energy problem has become one of the most prominent problems in the contemporary world. Therefore, seeking new energy sources, especially clean energy without pollution, has become a hot topic of current research.

[0003] Solar energy is a clean energy source that is inexhaustible and has a huge amount of resources. The total amount of solar radiation energy received by the earth's surface every year is 1×10 18 kW·h, which is more than ten thousand times the total annual energy consumption of the world. However, due to the small energy density of solar radiation reaching the earth (about one kilowatt per square meter) and its discontinuity, it brings certain difficulties to large-scale development and utilization. Therefore, in order to widely use solar energy, not only technical problems need to be solved, but also it must be economically competitive with conventional energy sources.

[0004] The output of solar water heating temperature control has always been a research hotspot in the solar energy field. A variety of studies have also been carried out in the prior art. CN103216945A provides a solar water heater with temperature control function. The water heater includes a central controller, a water heater, and a water tank connected to the water heater. The water inlet of the water heater is communicated with an external water source through a pipeline. The water tank is connected to the water heater, and an electric heating device and a temperature control device are provided on the water tank and the water heater, so as to realize the temperature control of the water heater. The present invention can control the heating power according to the water temperature, avoid the rapid thermal expansion of the inner tank, and at the same time control the water temperature according to the water flow rate to ensure the uniformity of the heating temperature. CN106016788A discloses a temperature control system and its control method. The temperature control system includes a storage tank for storing phase change materials after heating, at least one stirrer arranged inside the storage tank, and at least one hollow pipeline arranged inside the storage tank. The air inlets of the hollow pipelines are all connected to a hot and cold air blower. Temperature sensors are arranged on the side walls of the storage tank and the hollow pipeline. The present invention can monitor the temperature of the phase change materials in the storage tank at any time, and obtain the temperature inside the storage tank in real time through the temperature sensors, control the hot and cold air blower to blow hot air or cold air into the hollow pipeline to heat or cool the phase change materials in the storage tank, realize the adjustment of the temperature inside the storage tank, and achieve precise temperature control; through the stirring of the stirrer, the flow of the phase change materials at various places in the storage tank is realized, ensuring the uniformity of the temperature of the phase change materials in the storage tank, with good heat equalization effect, simple operation, precise, rapid, safe and intelligent temperature control of the molten salt storage tank. CN110806021A provides a trough solar collector system with temperature control, including a water heater. The water heater includes a collector tube and a reflector. The collector tube absorbs solar energy and heats the water in the collector tube. The collector tubes are multiple in parallel, and a reflector corresponds to the lower part of each collector tube. The feature is that a temperature sensor is arranged at the outlet of each collector tube to measure the fluid temperature at the outlet of the collector tube. The control system is data-connected to the temperature sensor, and judges the heating conditions of each collector tube according to the data detected by the temperature sensor. Through the above control system, the present invention can find out the collector tube with a low outlet temperature, check it, find out the cause of the problem, and facilitate improvement. The control system can also automatically remind which collector tube has an outlet temperature lower than the normal value.

[0005] The temperature control structure in the prior art is complex and the implementation speed is relatively slow. Therefore, this application makes improvements and proposes a new-structured solar water heater that can intelligently control the output temperature, so as to quickly output water at different temperatures and quickly meet the needs of users. Summary of the Invention

[0006] In order to overcome the defects and deficiencies existing in the prior art, the present invention provides a new-structured solar water heater that can quickly output water at different temperatures and quickly meet the needs of users.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A solar water heater with outlet water temperature control, comprising a heat collecting tube and a water tank. The heat collecting tube includes an evaporation end and a condensation end. The evaporation end absorbs solar heat, and the condensation end is inserted into the water tank to release heat to the water in the tank. It is characterized in that the water tank is divided into N independently heated areas, where N is greater than or equal to 2. The heat exchange areas of the condensation ends of each area are different, and the heat exchange areas of the condensation ends of the N areas gradually increase. Each area has an independent water inlet and an outlet. The outlet is connected to the water user, and a water outlet valve is provided on the outlet. A temperature sensor is arranged in each area to detect the temperature of the water after heating in the area. The temperature sensor, the water outlet valve and the controller are connected for data. The user inputs the water use temperature, and the controller determines the opening degree of each water outlet valve according to the temperature detected by the temperature sensor so as to achieve the water use temperature input by the user.

[0009] As an improvement, the controller is used to store the temperature data detected by the temperature sensor and sort the temperature data. After the controller receives the water use temperature input by the user, it compares the water use temperature with the temperature data in the database. If there is consistent temperature data, the controller controls the water outlet valve of the corresponding area to be fully opened, and the water outlet valves of other areas are closed. If the temperature data is inconsistent, the controller selects two adjacent temperature data in size, so that the water use temperature is between the two temperature data. Thus, the controller adjusts the opening degrees of the water outlet valves corresponding to the two data, and the other water outlet valves are closed, realizing the rapid output of water meeting the requirements.

[0010] As an improvement, at least one partition is arranged along the vertical direction of the water tank, so that the water tank is set into multiple heating areas distributed left and right.

[0011] As an improvement, along the direction from left to right, the heat exchange areas of the condensation ends in different heating areas gradually increase.

[0012] As an improvement, at least one partition is arranged along the horizontal direction of the water tank, so that the water tank is set into multiple heating areas distributed up and down.

[0013] As an improvement, along the direction from top to bottom of the water tank, the heat exchange areas of the condensation ends in different heating areas gradually increase.

[0014] As an improvement, N = 2, so that the heating area is divided into an upper area and a lower area.

[0015] As an improvement, it includes a cold water tank. The water inlet is communicated with the cold water tank. The cold water tank is provided with a separate cold water outlet, and a cold water valve is arranged at the cold water outlet. A temperature sensor is arranged in the cold water tank to detect the temperature of the cold water. The temperature sensor and the cold water valve are connected to the controller for data. The controller is used to store the temperature data detected by the temperature sensor and sort the temperature data. After the controller receives the user input of the water use temperature, it compares the water use temperature with the temperature data in the database. If there is consistent temperature data, the controller controls the water outlet valve in the corresponding area to be fully opened, and the water outlet valve in the other area and the cold water valve are closed. If the temperature data is inconsistent, the controller selects two adjacent temperature data in terms of size between the cold water temperature and the two hot water temperatures, so that the water use temperature is between the two temperature data. Thus, the controller adjusts the opening degrees of the valves corresponding to the two data, and the other valve is closed, realizing the rapid output of water meeting the requirements.

[0016] As an improvement, the partition is a heat conductor, and the flow directions of the water in the upper area and the lower area are opposite.

[0017] As an improvement, the heat collecting tube is a pulsating heat pipe.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] By setting multiple independent heating areas, the present invention can output hot water at different temperatures through each heating area, so that the user's required temperature can be quickly and accurately positioned between two data. Thus, by adjusting the valves corresponding to the data, the rapid output of the required temperature is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of the water tank of the solar water heater of the present invention;

[0021] Figure 2 is another schematic structural diagram of the water tank of the solar water heater of the present invention;

[0022] Figure 3 is Figure 1 the schematic control structure diagram of

[0023] Figure 4 is the schematic control structure diagram of two areas;

[0024] Figure 5 is the schematic structural diagram of the water tank of the integrated heat collecting tube water heater of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following will make a detailed description of the specific embodiments of the present invention with reference to the accompanying drawings.

[0026] Figures 1-5Disclosed is a solar water heater of the present invention. A solar water heater with outlet water temperature control includes a heat collecting tube 1 and a water tank 2. The heat collecting tube includes an evaporation end 11 and a condensation end 12. The evaporation end absorbs solar heat, and the condensation end is inserted into the water tank 2 to release heat to the water in the water tank 2.

[0027] As Figure 1 shown, the water tank 2 is divided into N independently heated areas 21, where N is greater than or equal to 2. The heat exchange areas of the condensation ends of each area are different or the amounts of cold water for heat exchange are different, so that the water temperatures in different areas are different after heating. Each area has an independent water inlet 22 and a water outlet 23. The water outlet 23 is connected to the water user, and a water outlet valve 3 is provided on the water outlet. A temperature sensor is provided in each area to detect the temperature of the water after heating in the area. The temperature sensor, the water outlet valve and the controller are connected for data. The user inputs the water use temperature, and the controller determines the opening degree of each water outlet valve 3 according to the temperature detected by the temperature sensor, so as to achieve the water use temperature input by the user.

[0028] By setting a plurality of independent heating areas in the present invention, hot water at different temperatures can be output through each heating area, so that the user's required temperature can be quickly and accurately positioned between two data, and then by adjusting the valves corresponding to the data, the required temperature can be quickly output.

[0029] As an improvement, the controller is used to store the temperature data detected by the temperature sensor and sort the temperature data. After the controller receives the user input water use temperature, it compares the water use temperature with the temperature data in the database. If there is consistent temperature data, the controller controls the water outlet valve of the corresponding area to be fully open and the water outlet valves of other areas to be closed. If the temperature data is inconsistent, the controller selects two adjacent temperature data in size, so that the water use temperature is between the two temperature data. Then the controller adjusts the opening degrees of the water outlet valves corresponding to the two data, and other water outlet valves are closed, so as to quickly output the water meeting the requirements. Through the present invention, the hot water in the area closest to the output temperature can be directly mobilized to quickly output the corresponding temperature required by the user.

[0030] As an improvement, as Figure 1 、 3 shown, at least one partition 4 is provided in the water tank along the vertical direction, so that the water tank is set into a plurality of heating areas distributed left and right.

[0031] As an improvement, along the direction from left to right, the hot water temperatures in different heating areas gradually increase or gradually decrease. By gradually increasing or gradually decreasing the output hot water temperature as described above, the data sorting in the controller can be simplified, so that the control of the opening and closing of the corresponding valves is simple. It is only to open and close the adjacent valves, and the data processing is easy and convenient.

[0032] As an improvement, the temperature can be gradually changed by gradually increasing or decreasing the heat exchange area of the condensation end, or by gradually increasing or decreasing the amount of water heated in the area.

[0033] As an improvement, as Figure 2 , 4 shown, at least one partition 4 is arranged horizontally in the water tank, so that the water tank is arranged into multiple heating areas distributed vertically. As an improvement, along the direction from top to bottom of the water tank, the hot water temperature of different heating areas gradually increases or decreases. By gradually increasing or decreasing the output hot water temperature as described above, the data sorting in the controller can be simplified, and thus the control of the opening and closing of the corresponding valves can be simplified. All are adjacent valves to be opened and closed, and the data processing is easy and convenient.

[0034] As an improvement, the temperature can be gradually changed by gradually increasing or decreasing the heat exchange area of the condensation end, or by gradually increasing or decreasing the amount of water heated in the area.

[0035] As an improvement, the partition 4 is a heat conductor, and the water flow directions in adjacent areas are opposite. Through the heat conductor, heat transfer of water in adjacent areas can be realized, and through the opposite water flow directions in adjacent areas, countercurrent heat exchange similar to that of a shell-and-tube heat exchanger can be realized, so as to more fully absorb solar heat and improve the heat transfer effect.

[0036] The present invention discloses a method for controlling the rapid outlet water temperature, including the following steps:

[0037] 1) The temperature sensor detects the temperature of the hot water in each area, and transmits the hot water temperature data and the corresponding valve code to the controller;

[0038] 2) The controller is used to store the temperature data and valve code detected by the temperature sensor into the database, and sort the temperature data and valve code according to the temperature magnitude;

[0039] 3) The user inputs the water use temperature. After the controller receives the user input water use temperature, it compares the water use temperature with the temperature data in the database. If there is consistent temperature data, the controller controls the outlet valve corresponding to the temperature data to be fully opened, and other outlet valves to be closed; if the temperature data is inconsistent, it proceeds to step 4);

[0040] 4) The controller selects two temperature data adjacent to the water use temperature from the database according to the water use temperature, so that the water use temperature is interposed between the two temperature data. Thus, the controller adjusts the opening degrees of the valves corresponding to the two data, and closes other outlet valves, so as to quickly output the water meeting the requirements.

[0041] As an improvement, in step 4, if the water temperature used by the user is T, the adjacent high-temperature data in the database is T1, and the low-temperature data is T2, then the valve opening corresponding to the high-temperature data and the valve opening corresponding to the low-temperature data are (T - T2) / (T1 - T). This can quickly achieve the output of water that meets the requirements.

[0042] As an improvement, in step 4, if the required temperature increases, the opening of the high-temperature valve is increased, and the opening of the low-temperature valve is decreased.

[0043] As an improvement, in step 4, if the required temperature decreases, the opening of the high-temperature valve is decreased, and the opening of the low-temperature valve is increased.

[0044] As an improvement, when the opening of the high-temperature valve or the low-temperature valve reaches 100% or 0, and still fails to meet the water use requirements, it returns to step 3).

[0045] As an improvement, as Figure 2 、 4 shown, N = 2, so that the heating area is divided into an upper area and a lower area.

[0046] As an improvement, it includes a cold water tank 5. The water inlet is communicated with the cold water tank. The cold water tank is provided with a separate cold water output pipeline 7 communicated with the user. A cold water valve 6 is provided on the cold water output pipeline. A temperature sensor is arranged in the cold water tank to detect the temperature of the cold water. The temperature sensor and the cold water valve are data-connected to the controller. The controller is used to store the temperature data detected by the temperature sensor and the corresponding cold water valve code.

[0047] As an improvement, the data stored in the database in step 2) includes cold water tank temperature data and cold water valve code data. Through the above settings, cold water can participate in the temperature output, and the temperature between the cold water and the lowest temperature can be output. The range of temperature output is increased.

[0048] As an improvement, as Figure 4As shown in the figure, it includes a cold water tank 5. The water inlet is connected to the cold water tank. The cold water tank is provided with a separate cold water output pipe 7 connected to the user. A cold water valve 6 is provided on the cold water output pipe. A temperature sensor is provided in the cold water tank to detect the temperature of the cold water. The temperature sensor and the cold water valve are connected to the controller for data. The controller is used to store the temperature data detected by the temperature sensor and sort the temperature data. After receiving the user input of the water use temperature, the controller compares the water use temperature with the temperature data in the database. If there is consistent temperature data, the controller controls the water outlet valve in the corresponding area to be fully opened, and the water outlet valve in the other area and the cold water valve are closed. If the temperature data is inconsistent, the controller selects two adjacent temperature data between the cold water temperature and the two hot water temperatures, so that the water use temperature is between the two temperature data. Thus, the controller adjusts the opening degrees of the valves corresponding to the two data, and the other valve is closed to achieve rapid output of water meeting the requirements.

[0049] As an improvement, the partition is a heat conductor, and the water flow directions in the upper area and the lower area are opposite. Through the heat conductor, heat transfer of water in adjacent areas can be achieved. Moreover, through the opposite water flow directions in adjacent areas, countercurrent heat exchange similar to that of a shell-and-tube heat exchanger can be realized, so as to more fully absorb solar heat and improve the heat transfer effect.

[0050] As an improvement, the heat collecting tube is a pulsating heat pipe. As Figure 5 shown in the figure. The pulsating heat pipe has the advantages of simple structure, small size, light weight, easy manufacturing, low cost and excellent performance. The operating principle and heat transfer characteristics of the pulsating heat pipe are very different from those of traditional heat pipes. When the pulsating heat pipe works, it can generally be divided into three parts. The two ends of the pipe are the heating section and the cooling section respectively, and the middle part of the pipe is the adiabatic section, and the adiabatic section can also be omitted. The operating principle of the pulsating heat pipe is as follows: when the pipe diameter is small enough, a series of vapor plugs and liquid plugs will be formed in the pipe; in the heating section, the liquid film between the vapor bubble or vapor column and the pipe wall will be continuously heated and evaporated, resulting in the expansion of the vapor bubble and the increase of pressure; at the same time, in the cooling section, the vapor bubble will condense, shrink and burst, and the pressure will drop, resulting in a driving pressure difference between the heating section and the condensation section, which pushes the vapor and liquid slugs to reciprocate between the heating section and the cooling section, and the heat is transferred from one end to the other end, thus realizing heat transfer or temperature control. It can be seen that in the pulsating heat pipe, the phase change of the working fluid mainly provides power for the working fluid, and the proportion of phase change heat transfer in the total heat transfer flux of the pulsating heat pipe is relatively small. The heat pipe mainly relies on the sensible heat change of the working fluid to achieve heat transfer.

[0051] As an improvement, as Figure 5As shown in the figure, the pulsating heat pipe includes multiple parallel straight pipes 13. Adjacent straight pipes are connected by upper bent pipes 14 and lower bent pipes 15. Among them, the leftmost and rightmost straight pipes 13 are connected by a horizontal straight pipe 16. A series loop structure is formed among the straight pipes 13, bent pipes 14, 15 and the horizontal straight pipe 16. The horizontal straight pipe 16 is located above the upper bent pipe 14 and a gap is provided between the horizontal straight pipe 16 and the upper bent pipe 14. The condensation end 12 includes the upper part of the straight pipe 13, the upper bent pipe 14 and the horizontal straight pipe 16. In the water tank 2, an upper area and a lower area are provided by a partition 4. The upper area and the lower area respectively have an inlet 22 and an outlet 23.

[0052] As an improvement, the upper area includes the horizontal straight pipe, the upper parts of the leftmost straight pipe and the rightmost straight pipe, and the lower area includes the upper bent pipe and the upper part of the straight pipe. The heat exchange area of the upper area is smaller than that of the lower area. Therefore, the water temperature output from the upper area is generally lower than that output from the lower area.

[0053] The partition is a heat conductor. Fluids in the upper area and the lower area can exchange heat through the partition. By setting a partition with regional heat conduction, heat exchange between fluids in the upper and lower areas can be realized, so that the heat in the upper and lower areas is complementary. Thus, the fluid with a higher temperature in the upper and lower areas transfers heat to the fluid with a lower temperature. Then, after the fluid with a higher temperature cools down, it absorbs the heat of the heat pipe, thereby achieving the maximum heat exchange amount. Through the heat conduction and heat complementarity of the partition, the best heat exchange effect can be achieved as much as possible whether it is in parallel flow or countercurrent heat exchange.

[0054] As an improvement, the partition includes a horizontal section 41 located in the gap, extending sections 42 extending downward from both ends of the horizontal section, and connecting sections 43 connecting the extending sections to the left and right walls of the water tank. A baffle is provided in the lower area. The baffle includes upper baffle plates 7 and lower baffle plates 8 arranged at intervals. The upper baffle plates extend downward from the horizontal section, and the lower baffle plates extend upward from the lower wall of the water tank. The straight pipes are arranged between adjacent baffle plates, and the upper bent pipes are arranged in the gap between the lower baffle plates and the partition.

[0055] In the present invention, by setting the upper and lower two areas, and a baffle plate structure is provided in the lower area, the straight pipe sections at different positions of the condensation end of the pulsating heat pipe can be adapted to the shape of the area, enabling the heat exchange fluid to fully contact the straight pipe sections and improving the heat exchange effect.

[0056] As an improvement, the flow direction of the water in the upper area is opposite to the flow direction of the fluid in the horizontal straight pipe, and the flow direction of the water in the lower area is opposite to the flow direction of the fluid in the bent pipe. The above can make the flow path of the fluid opposite to that of the fluid in the heat pipe in the area, thereby achieving the maximum heat exchange amount. By realizing regional flow, true countercurrent flow can be completely achieved.

[0057] As an improvement, along the water flow direction in the lower region, the lengths by which the upper baffle extends downward and the lower baffle extends are first gradually increased, reach the middle position of the flow channel in the lower region and then are gradually decreased. Since the positions of the connection segments are the outlets and inlets of the upper region and the lower region respectively, or the inlets and outlets of the upper region and the lower region, the temperature difference between the two is the largest at this time and the heat exchange effect is the best. Because of the change in the extension lengths of the baffles, the heat exchange area and the flow disturbance effect at the middle position are increased, thereby increasing the heat transfer coefficient, increasing the heat exchange effect, making the overall heat transfer amount balanced, achieving overall heat exchange balance, and thus being able to further achieve the best heat exchange effect.

[0058] As an improvement, along the water flow direction in the lower region, the lengths by which the upper baffle extends downward and the lower baffle extends are first gradually increased with the increasing amplitude continuously increasing, reach the middle position of the flow channel in the lower region and then are gradually decreased with the increasing amplitude continuously increasing. The above settings can further achieve overall heat exchange balance and improve the heat exchange effect.

[0059] As an improvement, the partition is a structure symmetric about the middle position of the lower wall surface of the water tank.

[0060] As an improvement, the heat conduction performances of different positions of the partition are different, and the heat conduction performance of the horizontal section is greater than that of the extended section, and the heat conduction performance of the extended section is greater than that of the connection section. Since when the inlets of the upper region and the lower region are not on the same side of the water tank, the positions of the first parallel part and the third parallel part are the outlets and inlets of the upper region and the lower region respectively, or the inlets and outlets of the upper region and the lower region, the temperature difference between the two is the largest at this time and the heat exchange effect is the best. Because by increasing the heat conduction coefficient at the middle position, the heat exchange effect is increased, making the overall heat transfer amount balanced, achieving overall heat exchange balance, and thus being able to further achieve the best heat exchange effect.

[0061] Although the present invention has been disclosed above with preferred embodiments, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A solar water heater with controlled water outlet temperature, comprising a heat collecting tube and a water tank, wherein the heat collecting tube comprises an evaporation end and a condensation end, wherein the evaporation end absorbs solar heat, and the condensation end is inserted into the water tank to release heat to the water in the water tank; characterized in that: The water tank is divided into N independently heated areas, where N is greater than or equal to 2. The heat exchange area at the condensing end of each area is different or the amount of cold water exchanged is different, so that the temperature of water in different areas is different after heating. Each area has an independent water inlet and outlet. The water outlet is connected to the water user, and a water outlet valve is arranged on the water outlet. A temperature sensor is arranged in each area to detect the temperature of the water after heating in the area. The temperature sensor, the water outlet valve and the controller are connected in data. The user inputs the water temperature, and the controller is controlled to determine the opening of each water outlet valve according to the temperature detected by the temperature sensor to achieve the water temperature input by the user.

2. The solar water heater according to claim 1, characterized in that: The controller is used to store the temperature data detected by the temperature sensor and sort the temperature data. After receiving the water use temperature input by the user, the controller compares the water use temperature with the temperature data in the database. If the temperature data are consistent, the controller controls the water outlet valves in the corresponding area to be fully opened, and the water outlet valves in other areas are closed. If the temperature data are inconsistent, the controller selects two adjacent temperature data so that the water use temperature is between the two temperature data, so that the controller adjusts the opening of the water outlet valves corresponding to the two data, and closes other water outlet valves, so as to achieve rapid output of water that meets the requirements.

3. The solar water heater according to claim 1, characterized in that: The water tank is provided with at least one partition along the vertical direction, so that the water tank is arranged into a plurality of heating areas distributed left and right.

4. The solar water heater according to claim 3, characterized in that: Along the direction from left to right, the hot water temperature in different heating areas gradually increases or decreases.

5. The solar water heater according to claim 4, characterized in that: The gradual change of temperature can be achieved by gradually increasing or decreasing the heat exchange area at the condensing end, or by gradually increasing or decreasing the amount of water heated in the area.

6. The solar water heater according to claim 1, characterized in that: The water tank is provided with at least one partition along the lateral direction, so that the water tank is arranged into a plurality of heating areas distributed up and down.

7. The solar water heater according to claim 6, characterized in that: The heat exchange areas of the condensation ends of different heating areas of the water tank gradually increase from top to bottom.

8. The solar water heater according to claim 7, characterized in that: N=2, so that the heating area is divided into an upper area and a lower area.

9. The solar water heater according to claim 7, characterized in that: The baffle is a heat conductor, and the water in the upper and lower areas flows in opposite directions.

10. The solar water heater according to claim 7, characterized in that: The heat collecting pipe is a pulsating heat pipe.

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