Solar water heater

Abstract

According to the solar water heater, a circulating pump is connected with a temperature control device and a water storage tank so as to circularly flow water in a circulating box based on temperature data of a temperature sensor; the heat collector is connected with the solar panel and the circulating box and comprises a vacuum tube heat exchanger composed of an inner copper tube and an outer vacuum tube, the inner copper tube comprises a vortex tube, and a first gradual change section is located at the upper end of the inner tube wall; the first cross section is twisted by a first preset angle in the longitudinal direction along with the first gradual change section and is smoothly and gradually changed into a blade shape from a circle with the radius being R, the second cross section is twisted by a second preset angle in the longitudinal direction along with the vortex flow section, and the second cross section is in a blade shape; the third cross section is twisted by a third preset angle in the longitudinal direction along with the second gradual change section, meanwhile, the blade shape is smoothly and gradually changed into a circle with the radius being R, sawtooth-shaped threads are arranged on the inner side of the blade shape, and the thread rotating direction of the sawtooth-shaped threads is consistent with the rotating direction of the vortex tube.

Description

Technical Field

[0001] The utility model relates to the technical field of water heaters, in particular to a solar water heater. Background Art

[0002] A solar water heater refers to a device that heats water from a low temperature to a high temperature by utilizing solar energy and belongs to a kind of renewable technology. Solar water heaters can be divided into active type and passive type according to the circulation mode. The passive type usually includes a water storage tank and a collector. The system utilizes the fact that when water absorbs solar energy and is heated, its specific gravity becomes lighter and it rises automatically, while cold water sinks automatically to complete the water circulation. The active type adds a water circulation pump and a temperature control device on this basis, and the water circulation is completed by the circulation pump. Although the price of the passive type is cheaper than that of the active water heater, its absorption efficiency of sunlight is relatively low. Therefore, the market share of active solar water heaters is increasing year by year. Whether it is the passive type or the active type, both are greatly affected by the weather. If it rains continuously for a long time, the solar water heater will not be able to produce hot water. In addition, due to the slow fluid velocity inside the water heater, the pipeline is prone to scaling, resulting in heat resistance caused by dirt. The above two points will greatly reduce the heat exchange efficiency.

[0003] The above information disclosed in the background art section is only used to enhance the understanding of the background of the present utility model, and therefore may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Utility Model

[0004] To solve the above problems, the present utility model provides a solar water heater, which improves the heat exchange efficiency and avoids pipeline scaling by locally applying eddy currents.

[0005] The purpose of the present utility model is achieved by the following technical solutions.

[0006] A solar water heater includes

[0007] A circulation tank, which includes

[0008] A water storage tank that holds water

[0009] A temperature control device, which includes a temperature sensor for measuring the temperature inside the water storage tank and a controller connected to the temperature sensor

[0010] A circulation pump that is connected to the temperature control device and the water storage tank to circulate the water in the circulation tank based on the temperature data of the temperature sensor;

[0011] A solar panel;

[0012] A collector, which connects the solar panel and the circulation tank. The collector includes a vacuum tube heat exchanger composed of an internal copper tube and an external vacuum tube. The internal copper tube includes a vortex tube, and the vortex tube includes an outer tube wall and an inner tube wall. Among them,

[0013] The inner tube wall includes

[0014] A first tapered section, which is located at the upper end of the inner tube wall. The first tapered section has a first length and a first cross-section in the longitudinal direction of the vortex tube. The first cross-section smoothly changes from a circle with a radius of R to a blade shape while twisting a first predetermined angle in the longitudinal direction of the first tapered section.

[0015] A vortex flow section, which connects the first tapered section. The vortex flow section has a second length and a second cross-section in the longitudinal direction of the vortex tube. The second cross-section twists a second predetermined angle in the longitudinal direction of the vortex flow section, and the second cross-section is the blade shape.

[0016] A second tapered section, which connects the vortex flow section and is located at the lower end of the inner tube wall. The second tapered section has a third length and a third cross-section in the longitudinal direction of the vortex tube. The third cross-section smoothly changes from the blade shape to a circle with a radius of R while twisting a third predetermined angle in the longitudinal direction of the second tapered section.

[0017] Jagged threads are provided on the inner side of the blade shape, and the thread rotation direction of the jagged threads is the same as the rotation direction of the vortex tube.

[0018] In the solar water heater described above, the blade shape includes a square with a side length of 2r and semi-circles with a radius of r extending on each side of the square. The cross-sectional area of the first cross-section remains unchanged. The outer tube wall is a straight tube, and its radius R ranges from 0.01 m to 1 m. The radius .

[0019] In the solar water heater described above, the cross-sectional area of the third cross-section remains unchanged, and the cross-sectional areas of the first cross-section, the second cross-section, and the third cross-section are the same.

[0020] In the solar water heater described above, the tooth height of the jagged threads is 0.1 mm - 1 mm.

[0021] In the solar water heater described above, the blade shape is composed of two blades, three blades, four blades, five blades, six blades, seven blades, or eight blades.

[0022] In the solar water heater described above, the length of the first transition section: the length of the middle four-blade cross-section section: the length of the second transition section is 2D:4D:2D, where D is the diameter of the circular cross-section. The first and second transition sections each rotate 90°, and the middle four-blade cross-section rotates 180°.

[0023] In the solar water heater described above, at the starting section and the ending section of the gradually changing section, there is an α-transition curve based on the cosine function, where , characterized in that is the distance from the circular inlet to the corresponding cross-section, 0.2 < a < 0.6, and at the same time 3 < b < 8.

[0024] In the solar water heater described above, the collector and the circulation tank are connected by a hose.

[0025] In the solar water heater described above, the sum of the first predetermined angle, the second predetermined angle, and the third predetermined angle is 360 degrees.

[0026] In the solar water heater described above, the ratio of the sum of the first length, the second length, and the third length to the radius R is 6:1.

[0027] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0028] The present utility model induces the generation of vortex flow by its own structure without external energy supply. There are no components leaking into the pipeline, which will not cause blockage to the pipeline, nor bring difficulties to pipeline scaling and cleaning. The inner wall of the vortex tube 11 is further provided with internal threads to increase the heat exchange area and improve the heat exchange efficiency. The present utility model installs the vortex tubes 11 at intervals to continuously form vortex flow, thereby improving the heat exchange efficiency of the solar water heater. The present utility model can freely switch the operation mode according to needs, so as to meet the hot water demand under different conditions. The present utility model proposes to use phase change materials to absorb solar heat. The vortex flow used in the present utility model has the function of self-cleaning the pipeline, avoiding the deposition of dirt in the pipeline to block heat, and reducing the number of cleaning times. The present utility model causes small pressure loss and small fluid resistance to the solar water heater.

[0029] The above description is only an overview of the technical solution of the present utility model. In order to make the technical means of the present utility model clearer and more understandable, to the extent that those skilled in the art can implement it according to the content of the specification, and in order to make the above and other purposes, features, and advantages of the present utility model more obvious and understandable, the following takes the specific implementation manner of the present utility model as an example for illustration. Description of the Drawings

[0030] By reading the detailed description in the following preferred specific embodiments, various other advantages and benefits of the present utility model will become clear to those of ordinary skill in the art. The accompanying drawings of the specification are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present utility model. Obviously, the following-described drawings are only some embodiments of the present utility model, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts. Moreover, throughout the drawings, the same reference numerals are used to represent the same components.

[0031] In the drawings:

[0032] Figure 1 is a schematic structural diagram of the solar water heater of the present utility model;

[0033] Figure 2 is a schematic structural diagram of the collector of the solar water heater of the present utility model;

[0034] Figure 3 is a schematic structural diagram of the vortex tube of the solar water heater;

[0035] Figure 4 is a cross-sectional view of the inner wall at a certain transition stage position in the gradient region of the solar water heater;

[0036] Figure 5 is a schematic diagram of the blade shape of the solar water heater;

[0037] Figure 6 is a schematic diagram of the serrated thread of the blade of the solar water heater;

[0038] Figure 7 is a schematic structural diagram of the vacuum tube water heater with phase change material added to the solar water heater;

[0039] Figure 8 is a schematic diagram of the comparison of Nusselt numbers with and without a vortex flow tube in the solar water heater;

[0040] Figure 9 is a schematic diagram of the comparison of the vortex flow enhanced heat transfer coefficients with and without a vortex flow tube in the solar water heater;

[0041] Figure 10 is a schematic diagram of the CFD simulation model of the vortex tube of the solar water heater;

[0042] Figure 11 is Figure 10 a schematic diagram of the Nusselt numbers under different CFD simulation models of the solar water heater;

[0043] Figure 12 is Figure 10 a schematic diagram of the Darcy friction coefficients under different CFD simulation models of the solar water heater;

[0044] Figure 13 is Figure 10 a schematic diagram of the Reynolds number under different CFD simulation models of a solar water heater;

[0045] Figure 14 is a schematic diagram of different vortex tube arrangements of a solar water heater. Detailed implementation manners

[0046] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0047] It should be noted that in the description of the specification and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that technicians may use different terms to refer to the same component. The specification and claims do not use the difference in terms as a way to distinguish components, but use the difference in functions of components as the criterion for distinction. As mentioned throughout the specification and claims, the term "comprising" or "including" is an open-ended term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is the preferred implementation manner for implementing the present invention, but the description is for the purpose of the general principle of the specification and is not used to limit the scope of the present invention. The protection scope of the present invention shall be subject to what is defined by the appended claims.

[0048] For the convenience of understanding the embodiments of the present invention, the following will further explain with specific embodiments as examples in conjunction with the accompanying drawings, and each accompanying drawing does not constitute a limitation on the embodiments of the present invention.

[0049] For better understanding, as Figures 1 to 14 shown, a solar water heater includes

[0050] a circulation tank 6, which includes

[0051] a water storage tank 7, which holds water

[0052] a temperature control device, which includes a temperature sensor for measuring the temperature in the water storage tank 7 and a controller connected to the temperature sensor

[0053] a circulation pump 8, which is connected to the temperature control device and the water storage tank 7 to circulate the water in the circulation tank 6 based on the temperature data of the temperature sensor;

[0054] a solar panel;

[0055] A collector 9, which connects the solar panel and the circulation tank 6. The collector 9 includes a vacuum tube heat exchanger 10 composed of an internal copper tube and an external vacuum tube. The internal copper tube includes a vortex tube 11. The vortex tube 11 includes an outer tube wall 1 and an inner tube wall 2. Among them,

[0056] The inner tube wall 2 includes,

[0057] A first tapered section 3, which is located at the upper end of the inner tube wall 2. The first tapered section 3 has a first length and a first cross-section in the longitudinal direction of the vortex tube 11. The first cross-section smoothly changes from a circle with a radius of R to a blade shape while the first tapered section 3 twists a first predetermined angle in the longitudinal direction.

[0058] A vortex flow section 4, which connects the first tapered section 3. The vortex flow section 4 has a second length and a second cross-section in the longitudinal direction of the vortex tube 11. The second cross-section twists a second predetermined angle in the longitudinal direction of the vortex flow section 4. The second cross-section is the blade shape.

[0059] A second tapered section 5, which connects the vortex flow section 4 and is located at the lower end of the inner tube wall 2. The second tapered section 5 has a third length and a third cross-section in the longitudinal direction of the vortex tube. The third cross-section smoothly changes from the blade shape to a circle with a radius of R while the second tapered section 5 twists a third predetermined angle in the longitudinal direction.

[0060] Jagged threads are provided on the inner side of the blade shape, and the thread rotation direction of the jagged threads is the same as the rotation direction of the vortex tube 11.

[0061] In a preferred embodiment of the solar water heater, the blade shape includes a square with a side length of 2r and semi-circles with a radius of r extending on each side of the square. The cross-sectional area of the first cross-section remains unchanged. The outer tube wall 1 is a straight tube, and its radius R ranges from 0.01 m to 1 m. The radius .

[0062] In a preferred embodiment of the solar water heater, the cross-sectional area of the third cross-section remains unchanged, and the cross-sectional areas of the first cross-section, the second cross-section, and the third cross-section are the same.

[0063] In a preferred embodiment of the solar water heater, the tooth height of the jagged threads is 0.1 mm - 1 mm.

[0064] In a preferred embodiment of the solar water heater, the blade shape is composed of two blades, three blades, four blades, five blades, six blades, seven blades, or eight blades.

[0065] In the preferred embodiment of the solar water heater described above, the length of the first transition section: the length of the middle four - blade cross - section section: the length of the second transition section is 2D:4D:2D, where D is the diameter of the circular cross - section. The first and second transition sections each turn 90°, and the middle four - blade cross - section turns 180°.

[0066] In the preferred embodiment of the solar water heater described above, at the starting section and the ending section of the gradual change section, there is an α - transition curve based on the cosine function, where , characterized in that, is the distance from the circular inlet to the corresponding cross - section, 0.2 < a < 0.6, and at the same time 3 < b < 8.

[0067] In the preferred embodiment of the solar water heater described above, the collector 9 and the circulation tank 6 are connected by a hose.

[0068] In the preferred embodiment of the solar water heater described above, the sum of the first predetermined angle, the second predetermined angle and the third predetermined angle is 360 degrees.

[0069] In the preferred embodiment of the solar water heater described above, the ratio of the sum of the first length, the second length and the third length to the radius R is 6:1.

[0070] In one embodiment, in the first and second gradual change sections 5, during the process that the cross - section shape of the inner wall of the pipe gradually changes from a circular shape to a blade - shaped cross - section, the cross - section rotates clockwise (+1) or counter - clockwise (-1) by a certain preset angle along the axial direction. In the illustration, the rotated angle is 90 degrees.

[0071] In one embodiment, as Figure 4 shown, where Rcs is the diameter of the circumscribed circle of the inner square after the gradual change is completed. R is the diameter of the circumscribed circle of the inner square during the gradual change process. rf is the radius of the blade - shaped sector after the gradual change is completed, and r is the radius of the blade - shaped sector during the gradual change process. A is the center of the blade - shaped sector. y is the distance from A to the center O of the circumscribed circle of the square. λ is the angle formed by the radius Rcs of the blade - shaped sector and the vertical side (FB) of the square. When the cross - section is circular, λ is 45°, and when the cross - section is in the complete blade shape, λ is 90°. When the λ angle gradually increases from 45° to 90°, a series of transition cross - sections can be formed. During the axial gradual change process of these cross - sections, they rotate clockwise (or counter - clockwise) by a predetermined angle, Figure 4 rotating 90° clockwise in

[0072] In one embodiment, the complete gradual change processes of the three - blade, four - blade and five - blade are shown as follows. Below the cross - section of the vortex flow section 4, the effect of 5 is the best. Among them, the smaller the area of the inner inscribed triangle, quadrilateral and pentagon, the stronger the ability to generate vortices. At the same time, serrated threads are arranged inside the blade, and the rotation direction of the threads is the same as the rotation direction of the vortex tube 11.

[0073] In one embodiment, as Figure 6 shown, in the blade shape, T is the bottom wall thickness, H is the tooth height, W1 is the bottom groove distance, W2 is the tooth top width, and γ is the tooth tip angle. The rotation angle of the internal pitch sawtooth is consistent with the rotation angle of the vortex tube 11.

[0074] Among them, on the premise of ensuring strength and processing technology, the thinner the bottom wall thickness, the better the heat transfer effect.

[0075] Among them, the tooth height is an important factor affecting heat transfer. Increasing the tooth height will increase the inner surface heat transfer area and the ability to break the liquid film on the heat transfer wall, enhancing the heat transfer effect. Preferably, the tooth height is in the range of 0.1 mm - 1 mm.

[0076] Among them, the smaller the tooth tip angle, the more the inner surface heat transfer area can be increased, the liquid film thickness of the condensation heat transfer can be thinned, and the vaporization core of the evaporation heat transfer can be enhanced. However, when the tooth tip angle is too small, the tooth height is depressed and deformed after expansion, resulting in a reduction in heat transfer efficiency. Therefore, on the premise of ensuring the anti-expansion strength of the tooth, the smaller the tooth tip angle of the internal thread tube, the better. Preferably, the tooth tip angle range is 10° - 50°. When the pipe diameter is small, a small tooth tip angle should be used, and when the pipe diameter increases, the tooth tip angle should be increased accordingly.

[0077] Among them, the bottom groove width W1 and the tooth top width W2 determine the number of teeth. Increasing the number of teeth, that is, the threaded ribs, is beneficial to increasing the inner surface heat transfer area. However, if the bottom groove width W1 is too small, the stirring intensity of the fluid in the pipe will be weakened, the liquid film thickness between the teeth will be increased, the thermal resistance will be increased, and the heat transfer ability will be reduced, making the heat transfer efficiency of the threaded tube approach that of the smooth tube. Therefore, reasonable parameters for the tooth pitch W1 and the tooth top width W2 should control the number of teeth within a reasonable range.

[0078] For the vortex tube 11, if the spacing change between sections is uniform during the clockwise rotation along the axis, this transition method is called linear transition. In order to generate a greater vortex intensity and reduce the pressure loss along the way, a more smooth and fluent transition method can be designed at the starting section and the ending section of the gradual change section, that is, the angle turned within a unit distance is smaller. Such as the α transition curve based on the cosine function, or the Vitosinski curve. Among them . Among them, is the spacing from the circular inlet to the corresponding section, and a and b are coefficients greater than 0. When a is less than 1 and b is greater than 1, the change rate of the section spacing at the starting section and the ending section of the transition pipe is lower because the transition is more smooth. A relatively optimized choice is 0.2 < a < 0.6, and at the same time 3 < b < 8.

[0079] The overall rotation angle of the flow channel should be 90°*n, and the rotation angle of the flow channel can be freely adjusted according to the actual situation. Among them, 90°*4 = 360° is the best. According to a relatively optimized length ratio, the length of the first transition section: the length of the middle four-blade cross-section section: the length of the second transition section = 2D:4D:2D. Where D is the diameter of the circular cross-section. The first and second transition sections each rotate 90°, and the middle four-blade cross-section rotates 180°.

[0080] In the vortex tube 11 described, the ratio of the sum of the first length, the second length, and the third length to the radius R is 6:1.

[0081] Among them, the ratio of the sum of the first length, the second length, and the third length to the radius R is 6:1. This value is obtained by studying the ratio of the heat exchange efficiency and pressure loss generated by the vortex tube 11 and the ordinary circular tube under the same conditions. When the pressure loss is not a consideration factor, the ratio can be further reduced to 4:1 to generate a higher heat exchange efficiency.

[0082] When the diameter, shape, and length of the vortex tube 11 are determined, the flow channel can be compressed from a circle to an elliptical pipe according to needs, so as to increase the area receiving sunlight.

[0083] In one embodiment, the solar water heater mainly consists of a collector 9 and a circulation tank 6. The collector 9 and the circulation tank 6 are connected by a plastic hose, and a heat insulation layer is installed on the connecting pipe. The circulation tank 6 includes a circulation pump 8, a temperature control device, a flow control device, and a 100L water storage tank 7. The circulation tank 6 is equipped with wheels and can be freely moved according to needs. Until the temperature reaches the set temperature. The circulation mode of the device can be freely selected according to needs. When it becomes active, the internal liquid flow rate can be controlled by the circulation pump 8. A fixed temperature can also be set. When the temperature in the water storage tank 7 is lower than the set temperature, the circulation pump 8 automatically starts to ensure sufficient hot water supply at any time. The vacuum tube heat exchanger 10 is composed of an internal copper tube and an external vacuum tube. The copper tube part in the collector 9 is taken out, 10 internal U-shaped copper tubes are cut, and replaced with 3D printed vortex tubes 11. The first 3D printed vortex tube 11 should be 20D (20 times the inner diameter of the copper tube) away from the water inlet, and the 2nd, 3rd, 4th, 5th, 6th, and 7th copper tubes are connected at intervals of about 20D. This spacing is obtained through computational fluid dynamics CFD simulation. Computational fluid dynamics CFD simulation proves that the U-shaped elbow will reduce the vortex effect, so the installation position of the vortex tube 11 should be about 20D away from the U-shaped elbow. A total of 140 copper tubes are installed in this device, and the specific number of copper tubes can be adjusted according to the length of the device.

[0084] The utility model induces the generation of vortex flow by its own structure without external energy supply. There is no component extending into the internal part of the non-directional pipeline, which will not cause blockage to the pipeline and will not bring difficulties to the operation and maintenance of the pipeline. The vortex tubes 11 are repeatedly installed at appropriate parts of the solar water heater in a targeted manner to ensure that the entire tubular reactor is in a vortex flow state. The vortex flow formed by the vortex tubes 11 can strongly impact the surface of the inner tube, improving the heat transfer efficiency. At the same time, the vortex flow has the function of self-cleaning the pipeline, avoiding the deposition of dirt in the tube and heat resistance.

[0085] As Figure 7 shown, each of the internal copper tubes of the vacuum tube heat exchanger 10 is wrapped with an external vacuum tube on the outside. The vacuum tube includes an inner glass layer 13 and an outer glass layer 12 surrounding it, and a vacuum layer 16 is formed between the two. The inner glass layer 13 surrounds the internal copper tube with the vortex tube 11, and a phase change material layer 15 is filled between them. Further, an aluminum fin layer 14 is provided on the outside of the internal copper tube. The internal copper tube uses the heat absorption coating of the inner tube to absorb sunlight and heat the water in the inner tube, and exchanges heat with the water tank or the connecting box to increase the water temperature. However, part of the heat cannot be absorbed by the water in time, resulting in losses. Therefore, the utility model proposes to fill the phase change material between the vacuum tube and the copper tube to store the heat that cannot be absorbed in time through its change between the liquid phase and the solid phase. The filled phase change material can be flexibly selected according to needs. The phase change material adopted by the utility model is stearic acid, and its thermodynamic related parameters are as follows:

[0086]

[0087] See Figure 8 , a CFD simulation model related to the utility model has been established, and numerical simulation proves that the vortex flow has the effect of improving the heat transfer efficiency. As Figures 11 to 13 shown, the velocity of the liquid is represented by the Reynolds number. The Reynolds number is a dimensionless number characterizing the fluid flow situation. The faster the liquid velocity, the larger the Reynolds number. The Nusselt number (Nu) is an important parameter in the heat transfer phenomenon. It directly affects the magnitude of the convective heat transfer coefficient, and evaluating the Nusselt number is also an index for evaluating the heat transfer efficiency. The magnitude of the Nusselt number represents the enhancement degree of convective heat transfer relative to the same fluid layer. The larger the Nusselt number, the more obvious the convective heat transfer effect. The Darcy friction coefficient (f) is a key dimensionless number describing the energy loss caused by the friction between the fluid in the pipeline and the wall surface. Under the same Reynolds number, the larger the Darcy friction coefficient, the greater the energy loss due to friction. As Figure 9It can be seen that when the vortex flow generator (vortex tube 11) is added, the heat transfer coefficient is significantly improved compared to the case without the vortex tube 11. This coefficient reaches its maximum value at the vortex tube 11 and then gradually decays. Therefore, considering adding multiple vortex tubes 11 to further increase the heat transfer coefficient. Different numbers of vortex tubes 11 are inserted into the circular tube at the same spacing. The inner diameter of the model's inner tube is 0.02 m. When the number of inserted vortex tubes 11 increases, both the Nusselt number and the friction coefficient will increase accordingly. Therefore, it is necessary to consider both the enhancement effect of the vortex tube 11 on heat transfer and the friction loss it causes. Another dimensionless number PEC is introduced and defined as follows, . This coefficient compares the Nusselt number and the friction coefficient of the vortex tube 11 and the circular tube under the same working conditions. When this number is greater than 1, it indicates that the overall performance of the vortex tube 11 is better than that of the circular tube. When the number of vortex tubes 11 is increased to 4 and the spacing of the vortex tubes 11 is 13.5D, the obtained PEC is the largest. For economic considerations in the present utility model, the spacing of the vortex tubes 11 is selected as 20D.

[0088] If it is necessary to further enhance the heat exchange efficiency, various different arrangements of the vortex tube 11 can be considered. Such as Figure 14 shown, the cross vortex flow arrangement is to stagger the placement of different numbers of vortex tubes 11, and the parallel vortex flow arrangement is to place different numbers of vortex tubes 11 in parallel. A certain distance of circular tube can be appropriately added between the vortex tubes 11 to reduce the pressure drop. The decaying vortex flow arrangement has been described above and will not be elaborated here. The continuous vortex flow arrangement is to adjust the distance of the second transition length to extend the vortex section.

[0089] The basic principles of the present application have been described above in combination with specific embodiments. However, it should be noted that the advantages, advantages, effects, etc. mentioned in the present application are only examples and not limitations. It cannot be considered that these advantages, advantages, effects, etc. are essential for each embodiment of the present application. In addition, the above-disclosed specific details are only for the purpose of illustration and easy understanding, rather than limitations. The above details do not limit the present application to necessarily adopt the above specific details to implement.

[0090] The above description has been given for purposes of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the form disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions, and sub-combinations thereof.

Claims

1. A solar water heater, characterized in that: It includes a circulation box and a collector. A circulation box comprising, A water storage tank, which holds water, The temperature control device includes a temperature sensor for measuring the temperature in the water storage tank and a controller connected to the temperature sensor. a circulation pump connected to the temperature control device and the water storage tank to circulate the water in the circulation box based on the temperature data of the temperature sensor; Solar panels; A heat collector is connected to the solar panel and the circulation box, wherein the heat collector comprises a vacuum tube heat exchanger composed of an inner copper tube and an outer vacuum tube, wherein the inner copper tube comprises a vortex tube, and the vortex tube comprises an outer tube wall and an inner tube wall, wherein: The inner tube wall includes: a first gradual section, which is located at the upper end of the inner tube wall, the first gradual section having a first length and a first cross section in the longitudinal direction of the vortex tube, the first cross section smoothly changes from a circle with a radius R to a blade shape while the first gradual section is twisted by a first predetermined angle in the longitudinal direction, a vortex flow section connected to the first gradual change section, the vortex flow section having a second length and a second cross section in the longitudinal direction of the vortex tube, the second cross section being twisted at a second predetermined angle in the longitudinal direction along with the vortex flow section, and the second cross section being in the shape of a blade; a second gradual change section, which is connected to the vortex flow section and is located at the lower end of the inner tube wall, the second gradual change section having a third length and a third cross section in the longitudinal direction of the vortex tube, the third cross section smoothly changes from the blade shape to a circle with a radius R while the second gradual change section is twisted by a third predetermined angle in the longitudinal direction, A sawtooth thread is arranged inside the blade shape, and the thread rotation direction of the sawtooth thread is consistent with the rotation direction of the vortex tube.

2. The solar water heater according to claim 1, characterized in that: The blade shape includes a square with a side length of 2r and a semicircle with a radius of r extending on each side of the square. The cross-sectional area of ​​the first cross section remains unchanged. The outer tube wall is a straight tube with a radius R of 0.01 m to 1 m. .

3. The solar water heater according to claim 1, characterized in that: The cross-sectional area of ​​the third cross-section remains unchanged, and the cross-sectional areas of the first cross-section, the second cross-section and the third cross-section are the same.

4. The solar water heater according to claim 1, characterized in that: The tooth height of the serrated thread is 0.1mm-1mm.

5. The solar water heater according to claim 1, characterized in that: The blade shape is composed of two blades, three blades, four blades, five blades, six blades, seven blades or eight blades.

6. The solar water heater according to claim 1, characterized in that: The length of the first transition section: the length of the middle four-blade cross-section section: the length of the second transition section is 2D:4D:2D, where D is the diameter of the circular cross-section. The first and second transition sections each rotate 90°, and the middle four-blade cross-section rotates 180°.

7. The solar water heater according to claim 1, characterized in that: The α transition curve based on the cosine function at the beginning and end of the gradient segment, where , is the distance from the circular inlet to the corresponding cross section, 0.2<a<0.6, and 3<b<8.

8. The solar water heater according to claim 1, characterized in that: The collector and the circulation box are connected by a hose.

9. The solar water heater according to claim 1, characterized in that: The sum of the first predetermined angle, the second predetermined angle and the third predetermined angle is 360 degrees.

10. The solar water heater according to claim 2, characterized in that: The ratio of the sum of the first length, the second length and the third length to the radius R is 6:1.

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