阅读说明：本技术 一种集热方法 (Heat collection method ) 是由 胡艳鑫 苏梓沛 肖佳煜 江鉴潮 莫连健 于 2021-08-03 设计创作，主要内容包括：本发明公开一种集热方法,集热过程为；阳光照射真空集热管,使真空集热管内壁的脉动热管的外侧铜管内的液态工质吸热形成气塞,在气塞的推动下,工质将热量输送至储水箱内并进行换热冷凝,并回落至外侧铜管内继续与真空集热管的内壁进行导热,如此往复,不断与储水箱进行换热；当外侧铜管与储水箱内的温差越来越小,外侧铜管内的压力变高,在内部压力的推动下,工质将回流到被相变材料包裹的内侧铜管内被相变材料冷凝,实现热量过余时储热,而工质冷凝后再回流给相邻的外侧铜管补充液态工质,如此往复,实现闭环路柱状绕组结构的脉动热管的单向循环集热。本发明可有效减小接触热阻,提高热管的运行效率,集热效率高。(The invention discloses a heat collection method, which comprises the following steps of; the sunlight irradiates the evacuated collector tube, so that a liquid working medium in an outer copper tube of the pulsating heat tube on the inner wall of the evacuated collector tube absorbs heat to form an air plug, the working medium conveys heat into the water storage tank under the pushing of the air plug and carries out heat exchange and condensation, the working medium falls back into the outer copper tube and continues to conduct heat with the inner wall of the evacuated collector tube, and the heat exchange with the water storage tank is carried out repeatedly in the way; when the temperature difference between the outer copper pipe and the water storage tank is smaller and smaller, the pressure in the outer copper pipe is increased, working medium flows back to the inner copper pipe wrapped by the phase-change material to be condensed by the phase-change material under the pushing of the internal pressure, heat storage is realized when heat is excessive, the working medium is condensed and then flows back to the adjacent outer copper pipe to supplement liquid working medium, and the reciprocating is realized in such a way, and the unidirectional circulation heat collection of the pulsating heat pipe with the closed loop columnar winding structure is realized. The invention can effectively reduce the contact thermal resistance, improve the operation efficiency of the heat pipe and has high heat collection efficiency.)

1. The heat collection method is characterized by comprising the following steps:

sunlight irradiates on the evacuated collector tube (2), the outer wall of the evacuated collector tube (2) conducts heat to the inner wall, so that liquid working medium in an outer copper tube (41) of a pulsating heat tube (4) close to the inner wall of the evacuated collector tube (2) absorbs heat to form an air plug, under the pushing of the air plug, the working medium in the outer copper tube (41) conveys heat into a water storage tank (5) for heat exchange, the working medium in the outer copper tube (41) is condensed along with the heat, falls back into the outer copper tube (41) under the action of gravity and continues to conduct heat with the inner wall of the evacuated collector tube (2), and the steps are repeated in such a way to continuously conduct heat exchange with the water storage tank (5);

when the water temperature in the water storage tank (5) rises, the temperature difference between the outer copper pipe (41) of the pulsating heat pipe (4) and the water storage tank (5) is smaller and smaller, working media in the outer copper pipe (41) cannot be completely condensed, more longer air plugs can be formed, the pressure in the outer copper pipe (41) is higher and higher, the working media flow back into the inner copper pipe (42) wrapped by the phase-change material (8) under the pushing of the internal pressure, at the moment, the redundant heat of the working media is absorbed by the phase-change material (8) and then condensed, the heat is stored in the phase-change material (8), the heat storage is realized when the heat is excessive, the working media flow back after being condensed, the liquid working media are supplemented to the adjacent outer copper pipe (41), and the reciprocating operation is carried out, and the unidirectional circulation heat collection of the pulsating heat pipe (4) with the closed loop columnar winding structure is realized.

2. A pulsating heat pipe applying the heat collection method of claim 1, characterized in that the pulsating heat pipe (4) is a closed loop circuit cylindrical winding structure formed by connecting a plurality of copper pipes through elbows, and comprises an evaporation section (401) and a condensation section (403), wherein the condensation section (403) is used for extending into a water storage tank (5), and the evaporation section (401) is used for extending into a vacuum heat collection pipe (2); a cavity (7) is constructed on the inner wall of the vacuum heat collecting tube (2), and a phase-change material (8) is filled in the cavity (7); an outer copper tube (41) positioned outside the winding in an evaporation section (401) of the pulsating heat pipe (4) is tightly attached to the inner wall of the vacuum heat collecting tube (2), and an inner copper tube (42) positioned inside the winding is arranged in the cavity (7) and is wrapped by the phase-change material (8).

3. The pulsating heat pipe according to claim 2, wherein the cavity wall of the cavity (7) is constructed by polytetrafluoroethylene, a plurality of accommodating grooves (9) are formed between the outer side of the cavity wall and the inner wall of the evacuated collector tube (2), and an outer copper tube (41) positioned outside the winding in the evaporation section (401) of the pulsating heat pipe (4) is placed in the accommodating grooves (9) and tightly attached to the inner wall of the evacuated collector tube (2).

4. A pulsating heat pipe as claimed in claim 3, wherein the portions of the cavity wall of the cavity (7) except for the portion forming the accommodating groove (9) are fixedly attached with a heat conducting metal sheet (10), and are attached to the inner wall of the evacuated collector tube (2) through the heat conducting metal sheet (10).

5. A pulsating heat pipe as claimed in claim 3, wherein a gap between the body of the outer copper tube (41) and said receiving groove (9) is seamlessly filled with a thermally conductive silicone grease.

6. A pulsating heat pipe as claimed in claim 2, wherein the difference between the overall outer diameter of the pulsating heat pipe (4) and the inner diameter of the evacuated collector tube (2) is no more than 1 mm.

7. A pulsating heat pipe as claimed in claim 2, wherein the number of bends at both ends of the pulsating heat pipe (4) is not more than 8, and the bending radius of the bends is not less than 10 mm.

8. A pulsating heat pipe as claimed in claim 2, wherein the copper pipe of the pulsating heat pipe (4) is made of red copper material, the inner diameter of the copper pipe is not more than 4mm, the liquid working medium placed in the pipe comprises deionized water or self-wetting fluid, and the liquid filling rate is 40% -70%.

9. A solar energy utilization system, which is characterized by comprising the pulsating heat pipe, the linear Fresnel lens (1), the evacuated collector tube (2), the compound parabolic concentrator (3), a water storage tank (5) and a bracket (6) according to any one of claims 2 to 8; the linear Fresnel lens (1) and the compound parabolic condenser (3) are respectively arranged on the upper side and the lower side of the vacuum heat collecting tube (2) and fixed on the support (6), and condensing optical axes of the linear Fresnel lens and the compound parabolic condenser are coincided with the axis of the vacuum heat collecting tube (2); the vacuum heat collecting pipe (2) is fixed and obliquely arranged through the bracket (6); the water storage tank (5) is fixed to the top of the support (6) and communicated with the top of the evacuated collector tube (2), a condensation section (403) of the pulsating heat tube (4) extends into the water storage tank (5) through a mounting hole, and an evaporation section (401) extends into the evacuated collector tube (2).

10. The solar energy utilization system of claim 9, wherein the evacuated collector tube (2) is of a glass double-layer coaxial structure, the interlayer is evacuated, and comprises an inner glass tube, an outer glass tube and a vacuum interlayer, wherein the outer surface of the inner glass tube is coated with a selective absorption coating.

Technical Field

The invention relates to the technical field of solar heat utilization, in particular to a heat collection method.

Background

The heat pipe type vacuum pipe is used for solar heat collection, has the advantages of wide heat collection range, small heat loss, difficult pipe explosion and the like, and can improve the solar energy grade by matching with different light condensation modes. In order to stabilize the working temperature of the heat collector and prolong the working time, the heat pipe type vacuum tube can be filled with energy storage phase change materials. In the structure of the traditional heat pipe type vacuum tube, the contact area between a heat pipe and the inner wall of the vacuum tube is small, the thermal resistance is large, and the temperature fluctuation is large; the working principle of various heat pipe type vacuum tube heat collecting devices filled with phase change materials in the tubes is that solar radiation is collected by the vacuum tubes and transmitted to the phase change materials directly contacted with the inner walls of the vacuum tubes, and then the phase change materials are transmitted to the heat pipes positioned in the middle of the vacuum tubes, the phase change materials are generally organic phase change materials with low supercooling degrees, although the organic phase change materials have a certain energy storage effect, the organic phase change materials with high thermal resistance are directly contacted with the vacuum tubes, so that the heat pipes in the vacuum tubes are difficult to start, and the initial heat collecting efficiency of the device is influenced; the existing composite parabolic light condensation technology in the market has limited improvement on the energy grade of a solar heat collector. For example, chinese patent No. CN209230041U, publication No. 2019.8.9: a solar water heater based on Fresnel line light-gathering and heat-collecting is characterized in that a heat pipe is integrally wrapped by a phase-change material, the heat pipe is not in contact with the inner wall of a vacuum pipe, the thermal resistance is large, the operation efficiency of the heat pipe is low, and the heat-collecting efficiency is low.

Disclosure of Invention

The invention provides a heat collecting method, which can effectively reduce thermal contact resistance, improve the operating efficiency of a heat pipe and has high heat collecting efficiency.

The technical scheme of the invention is as follows:

the heat collecting method comprises the following steps:

sunlight irradiates on the evacuated collector tube, the outer wall of the evacuated collector tube conducts heat to the inner wall, so that liquid working medium in an outer copper tube of the pulsating heat tube tightly attached to the inner wall of the evacuated collector tube absorbs heat to form an air plug, the working medium in the outer copper tube conveys the heat into the water storage tank and conducts heat exchange under the pushing of the air plug, the working medium in the outer copper tube condenses along with the air plug and falls back into the outer copper tube under the action of gravity to conduct heat continuously with the inner wall of the evacuated collector tube, and the heat exchange with the water storage tank is conducted repeatedly;

after the temperature in the water storage tank rises, the temperature difference between the outer copper pipe of the pulsating heat pipe and the water storage tank is smaller and smaller, working media in the outer copper pipe cannot be completely condensed, more longer air plugs can be formed, the pressure in the outer copper pipe is higher and higher, the working media flow back into the inner copper pipe wrapped by the phase-change material under the pushing of the internal pressure, at the moment, redundant heat of the working media is condensed after being absorbed by the phase-change material, the heat is stored in the phase-change material, the heat is stored when the heat is excessive, the working media flow back after being condensed, liquid working media are supplemented to the adjacent outer copper pipe, the operation is repeated, and the unidirectional circulation heat collection of the pulsating heat pipe with the closed-loop columnar winding structure is realized.

A pulsating heat pipe applying the heat collection method is a closed loop columnar winding structure formed by connecting a plurality of copper pipes through elbows, and comprises an evaporation section and a condensation section, wherein the condensation section is used for extending into a water storage tank, and the evaporation section is used for extending into a vacuum heat collection pipe; a cavity is constructed on the inner wall of the vacuum heat collecting tube, and a phase-change material is filled in the cavity; an outer copper pipe positioned outside the winding in the evaporation section of the pulsating heat pipe is tightly attached to the inner wall of the vacuum heat collecting pipe, and an inner copper pipe positioned inside the winding is arranged in the cavity and is wrapped by the phase-change material.

The pulsating heat pipe is of a closed loop columnar winding structure, wherein an outer copper pipe positioned outside a winding in an evaporation section is tightly attached to the inner wall of the vacuum heat collecting pipe, so that the contact thermal resistance is reduced, after the evaporation section transfers heat to a condensation section, the excess heat is transferred to an inner copper pipe positioned inside the winding and is coupled with a phase change material in a cavity, so that the heat storage function is realized; the outer copper pipe of the pulsating heat pipe of the closed loop columnar winding structure is in direct contact with the inner wall of the evacuated collector tube, and the phase-change material is not in contact with the inner wall of the evacuated collector tube, so that the defect of high thermal resistance of the conventional heat pipe type vacuum pipe is overcome, and the heat collected by the outer copper pipe is condensed by the water storage tank and then stored by the inner copper pipe, so that the water production speed of the heat pipe is increased compared with that of the common phase-change heat storage heat pipe type vacuum pipe, and the heat storage is realized when the heat is excessive; the starting of the common pulsating heat pipe has certain randomness, and in the invention, because of the temperature difference inside the vacuum heat collecting pipe during working, a certain pressure difference exists between two copper pipes connected with each elbow winding of the pulsating heat pipe, an air plug formed after the outer copper pipe absorbs heat is firstly transferred to a water storage tank through a top elbow, then is transferred to an inner copper pipe through the top elbow, and then is condensed after the inner copper pipe and a phase change material are coupled in a cavity, so that heat storage is realized when the heat is excessive, and finally, the inner copper pipe flows back to a bottom elbow to supplement a liquid working medium for the other adjacent outer copper pipe, so that the reciprocating operation can realize the unidirectional operation of the pulsating heat pipe, the starting characteristic is optimized, and the operation efficiency of the pulsating heat pipe is improved.

Furthermore, the cavity wall of the cavity is formed by adopting polytetrafluoroethylene, a plurality of accommodating grooves are formed between the outer side of the cavity wall and the inner wall of the vacuum heat collecting tube, and an outer copper tube positioned on the outer side of the winding in the evaporation section of the pulsating heat pipe is arranged in the accommodating grooves and tightly attached to the inner wall of the vacuum heat collecting tube.

The wall of the heat storage cavity is made of polytetrafluoroethylene, so that the heat insulation performance is good, the weight is light, and the heat leakage of the phase change material at night is reduced.

Furthermore, the parts of the cavity wall of the cavity except for the part forming the accommodating groove are fixedly attached with heat conducting metal sheets, and are tightly attached to the inner wall of the vacuum heat collecting tube through the heat conducting metal sheets. The heat conducting metal sheet can enhance the heat conducting performance between the inner wall of the vacuum heat collecting pipe and the pulsating heat pipe.

Furthermore, the clearance between the tube body of the outer copper tube and the accommodating groove is seamlessly filled with heat-conducting silicone grease, so that the thermal contact resistance can be further reduced.

Furthermore, the difference between the overall outer diameter of the pulsating heat pipe and the inner diameter of the vacuum heat collecting pipe is not more than 1mm, so that the outer side of the pulsating heat pipe is in seamless direct contact with the inner wall of the vacuum heat collecting pipe as far as possible, and the contact thermal resistance is reduced.

Furthermore, the number of elbows at two ends of the pulsating heat pipe is not more than 8, and the bending radius of the elbows is not less than 10mm, so that the shape of a section channel at the elbows is not obviously flattened, and the performance of the pulsating heat pipe is influenced by overlarge flow resistance.

Furthermore, the copper pipe of the pulsating heat pipe is made of red copper material, so that the heat conductivity coefficient is high, heat transfer is facilitated, the hardness is low, and the processing operation is convenient; the inner diameter of the copper pipe is not more than 4mm, so that the surface tension effect is fully exerted, an air plug for driving the pulsating heat pipe to run is easier to generate during the running of the pulsating heat pipe, and the running is better started; meanwhile, the liquid working medium arranged in the tube comprises deionized water or self-wetting fluid, and the liquid filling rate is 40-70%.

The invention also provides a solar energy utilization system which comprises the pulsating heat pipe, the linear Fresnel lens, the evacuated collector tube, the compound parabolic condenser, the water storage tank and the support, wherein the linear Fresnel lens and the compound parabolic condenser are respectively arranged at the upper side and the lower side of the evacuated collector tube and are fixed on the support, the condensing optical axes of the linear Fresnel lens and the compound parabolic condenser are coincided with the axis of the evacuated collector tube, the evacuated collector tube is fixed and obliquely arranged through the support, the water storage tank is fixed at the top of the support and is communicated with the top of the evacuated collector tube, the condensing section of the pulsating heat pipe extends into the water storage tank through the mounting hole, and the evaporating section extends into the evacuated collector tube.

When the solar collector is installed, the linear Fresnel lens is fixed by a support and is installed above the vacuum heat collecting tube at a certain distance and angle, so that a light condensing optical axis is superposed with the axis of the vacuum heat collecting tube; the compound parabolic condenser is fixed below the vacuum heat collecting tube by a bracket at a certain distance and angle, so that the light condensing optical axis of the compound parabolic condenser is also superposed with the axis of the vacuum heat collecting tube; the pulsating heat pipe of the closed loop columnar winding structure is matched with the structure of the vacuum heat collecting pipe, an inner copper pipe of the evaporation section is introduced into a cavity filled with a phase change material, the outer surface of an outer copper pipe is tightly attached to the inner wall of the vacuum heat collecting pipe, and the condensation section penetrates through the mounting hole to enter the water storage tank; the vacuum heat collecting tube and the water storage tank are fixed by utilizing an aluminum alloy support, wherein the vacuum heat collecting tube is obliquely arranged, the inclination angle is 15-65 degrees, different inclination angles can be adjusted according to different geographical positions to adapt to different solar altitude angles, and the device can be realized by adjusting the aluminum alloy support.

Wherein, the copper pipe is wrapped by polyurethane foaming heat-insulating material at the mounting hole for heat-insulating treatment to form a heat-insulating section, and finally, glue is used for sealing and leakage prevention.

Because the linear Fresnel lens is adopted for parallel light condensation, the lens has certain curvature, and the tracking-free performance can be realized to a certain degree; the solar vacuum heat collecting tube is assisted with the compound parabolic condenser for secondary light condensation, so that the solar radiation can be fully utilized, the heat flux density is improved, the heat grade is improved, meanwhile, the installation quantity of the vacuum heat collecting tubes can be reduced, and the equipment cost is reduced.

Furthermore, the vacuum heat collecting tube has a glass double-layer coaxial structure, the interlayer is vacuumized and comprises an inner glass tube, an outer glass tube and a vacuum interlayer, and the outer surface of the inner glass tube is coated with a selective absorption coating. The selective absorption coating can enhance the heat conduction capability of the tube wall of the vacuum heat collecting tube and improve the heat collecting efficiency.

The invention has the beneficial effects that:

1. the pulsating heat pipe is integrally of a closed loop columnar winding structure, the outer copper pipe of the evaporation section is attached to the inner wall of the vacuum heat collecting pipe, so that the contact thermal resistance is effectively reduced, the heat transfer efficiency is improved, the inner copper pipe extends into the cavity filled with the phase change material, the space in the vacuum heat collecting pipe is fully utilized for heat storage, the phase change material is not in direct contact with the inner wall of the vacuum heat collecting pipe, and the contact thermal resistance is further reduced;

2. the outer copper pipe of the pulsating heat pipe is in direct contact with the inner wall of the vacuum heat collecting pipe, heat is transmitted to the water storage tank by utilizing the pulsating effect, excess heat after the water storage tank is condensed is conducted to the phase-change material heat storage by the inner copper pipe, the heat collecting mode that hot water is produced firstly and then energy is stored can be realized, and the inner copper pipe and the outer copper pipe which are connected by the same elbow have stable temperature difference, so that the pulsating heat pipe can operate in a single direction, the operation efficiency of the heat pipe is improved, and the heat collecting efficiency of the device is high.

Drawings

FIG. 1 is a schematic structural view of a solar energy utilization system according to the present invention;

FIG. 2 is a schematic view of the installation position of the pulsating heat pipe;

FIG. 3 is a schematic structural diagram of a pulsating heat pipe;

FIG. 4 is another angle schematic of a pulsating heat pipe;

FIG. 5 is a schematic structural view of a chamber;

FIG. 6 is a schematic view of a pulsating heat pipe installed in a evacuated collector tube;

in the figure: the solar heat collector comprises a linear Fresnel lens 1, a vacuum heat collecting tube 2, a compound parabolic condenser 3, a pulsating heat pipe 4, an outer copper pipe 41, an inner copper pipe 42, an evaporation section 401, a heat insulation section 402, a condensation section 403, a water storage tank 5, a support 6, a cavity 7, a phase-change material 8, a containing groove 9 and a heat conducting metal sheet 10.

Detailed Description

The drawings are for illustrative purposes only and are not to be construed as limiting the patent; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent.

Example 1:

as shown in fig. 1-6, a solar energy utilization system includes a linear fresnel lens 1, a vacuum heat collecting tube 2, a compound parabolic condenser 3, a pulsating heat pipe 4, a water storage tank 5 and a support 6;

the linear Fresnel lens 1 and the compound parabolic condenser 3 are respectively arranged at the upper side and the lower side of the evacuated collector tube 2 and fixed on the support 6, the condensing optical axes of the linear Fresnel lens 1 and the compound parabolic condenser 3 are coincided with the axis of the evacuated collector tube 2, the evacuated collector tube 2 is fixed and obliquely arranged through the support 6, the water storage tank 5 is fixed at the top of the support 6 and communicated with the top of the evacuated collector tube 2, wherein the pulsating heat tube 4 is a closed loop cylindrical winding structure formed by connecting a plurality of copper tubes through elbows, and comprises an evaporation section 401 and a condensation section 403, wherein the condensation section 403 extends into the water storage tank 5 through a mounting hole, and the evaporation section 401 extends into the evacuated collector tube 2; a cavity 7 is constructed on the inner wall of the vacuum heat collecting tube 2, and the cavity 7 is filled with a phase-change material 8; an outer copper tube 41 positioned outside the winding in the evaporation section 401 of the pulsating heat pipe 4 is tightly attached to the inner wall of the evacuated collector tube 2, and an inner copper tube 42 positioned inside the winding is arranged in the cavity and is wrapped by the phase change material 8.

When the solar collector is installed, the linear Fresnel lens 1 is fixed above the vacuum heat collecting tube 2 by a bracket 6 at a certain distance and angle, so that a light-gathering optical axis is superposed with the axis of the vacuum heat collecting tube 2; the compound parabolic condenser 3 is fixed below the vacuum heat collecting tube 2 by a bracket 6 at a certain distance and angle, so that the light condensing optical axis of the compound parabolic condenser is also superposed with the axis of the vacuum heat collecting tube 2; the pulsating heat pipe 4 of the closed loop columnar winding structure is matched with the structure of the evacuated collector tube 2, the inner copper pipe 42 of the evaporation section 401 is led into the cavity 7 filled with the phase-change material 8, the outer surface of the outer copper pipe 41 is tightly attached to the inner wall of the evacuated collector tube 2, and the condensation section 403 passes through the mounting hole and enters the water storage tank 5; the vacuum heat collecting tube 2 and the water storage tank 5 are fixed by utilizing the aluminum alloy support 6, wherein the vacuum heat collecting tube 2 is obliquely arranged, the inclination angle is 15-65 degrees, different inclination angles can be adjusted according to different geographical positions to adapt to different solar altitude angles, and the aluminum alloy support 6 can be adjusted to realize the purpose.

In this embodiment, the copper pipe is wrapped with a polyurethane foam insulation material at the mounting hole for insulation heat treatment to form an insulation section 402, and finally, the copper pipe is sealed and leak-proof by using glue.

In the embodiment, the linear Fresnel lens 1 is a curved surface structure, has a certain tracking-free capacity, is made of a glass lens with high light transmittance, and can focus solar radiation parallel lines with a certain area on an optical axis; the rest radiation reflection is received by the compound parabolic condenser 3, secondary condensation is carried out, the radiation receiving capacity of the vacuum heat collecting tube 2 is increased, the solar radiation of the vacuum heat collecting tube 2 can be fully utilized, the heat flow density is improved, the heat grade is improved, meanwhile, the installation quantity of the vacuum heat collecting tube 2 can be reduced, and the equipment cost is reduced.

In the embodiment, the pulsating heat pipe 4 uses red copper as a material, has high heat conductivity coefficient, is beneficial to heat transfer, has low hardness and is convenient for processing operation; in order to fully play the surface tension effect and enable the pulsating heat pipe 4 to generate an air plug for driving the pulsating heat pipe 4 to run more easily during running, the inner diameter of a copper pipe of the pulsating heat pipe 4 is not more than 4mm, so that the outer diameter of the copper pipe is set to be 4mm, the inner diameter is set to be 3mm, and the wall thickness is set to be 0.5 mm; the elbow is directly processed by using a pipe bender, the number of the elbows is 16, the elbows at two ends are respectively 8, and in order to ensure that the cross section of a channel at the elbow is not deformed to a large extent and the flow resistance is overlarge to influence the performance of the heat pipe, the bending radius of the elbow is not less than 10 mm; the pulsating heat pipe 4 is finally connected end to end through processing to form a closed loop cylindrical winding structure, the outer diameter of the three-dimensional structure is 56mm, the length of the three-dimensional structure is 850mm, 600mm of the length of the inner wall of the vacuum heat collecting pipe 2 is plugged into the three-dimensional structure to serve as an evaporation section 401, 50mm of the length of the heat insulation section 402 is placed in an installation hole of the water storage tank 5, and 200mm of the length of the condensation section 403 extends into the water storage tank 5; after the manufacturing is finished, the pulsating heat pipe 4 is vacuumized and filled with liquid working medium which is deionized water, and the filling rate is 50%.

In the embodiment, a cavity 7 filled with a phase-change material is constructed on the inner wall of the vacuum heat collecting tube 2, the cavity wall of the cavity 7 is constructed and formed by polytetrafluoroethylene, the heat insulation performance is good, the weight is light, the heat leakage of the phase-change material at night is reduced, the phase-change material is industrial paraffin, the heat conductivity coefficient is 0.37W/(m.DEG C), the latent heat of phase change is 161.54kJ/kg, and the phase-change temperature is 65.3 ℃; a plurality of accommodating grooves 9 are formed between the outer side of the cavity wall and the inner wall of the evacuated collector tube 2, and an outer copper tube 41 positioned outside the winding in the evaporation section 401 of the pulsating heat tube 4 is arranged in the accommodating grooves 9 and clings to the inner wall of the evacuated collector tube 2; the heat conducting metal sheets 10 are fixedly attached to the parts of the cavity wall of the cavity 7 except for the accommodating groove 9, and are closely attached to the inner wall of the vacuum heat collecting tube 2 through the heat conducting metal sheets 10, so that seamless connection is realized, and the heat conducting performance between the inner wall of the vacuum heat collecting tube 2 and the pulsating heat pipe 4 can be enhanced through the inserted heat conducting metal sheets 10; meanwhile, the gap between the tube body of the outer copper tube 41 and the accommodating groove 9 is filled with heat-conducting silicone grease in a seamless mode, so that the heat contact area is increased, and the thermal contact resistance can be further reduced.

In this embodiment, the difference between the overall outer diameter of the pulsating heat pipe 4 and the inner diameter of the evacuated collector tube 2 is not more than 1mm, so that the outer side of the pulsating heat pipe 4 and the inner wall of the evacuated collector tube 2 are in direct contact as seamlessly as possible, and the thermal contact resistance is reduced.

In this embodiment, the glass material of the evacuated collector tube 2 is borosilicate glass, the outer tube diameter is 70mm, the inner tube diameter is 57mm, the tube thickness is 1.6mm, and the tube length is 700 mm; the vacuum heat collecting tube 2 is of a glass double-layer coaxial structure, the interlayer is vacuumized and comprises an inner glass tube, an outer glass tube and a vacuum interlayer, wherein the outer surface of the inner glass tube is coated with a selective absorption coating, and the selective absorption coating is arranged, so that the heat conducting capacity of the tube wall of the vacuum heat collecting tube 2 can be enhanced, and the heat collecting efficiency is improved.

The pulsating heat pipe 4 is a closed loop columnar winding structure, wherein an outer copper pipe 41 positioned outside the winding in the evaporation section 401 is tightly attached to the inner wall of the evacuated collector tube 2, so that the contact thermal resistance is reduced, after the evaporation section 401 transfers heat to the condensation section 403, the excess heat is transferred to an inner copper pipe 42 positioned inside the winding and is coupled with the phase change material 8 in the cavity 7, so that the heat storage function is realized.

The invention also provides a heat collection method, which comprises the following heat collection processes:

sunlight irradiates on the evacuated collector tube 2, the outer wall of the evacuated collector tube 2 conducts heat to the inner wall, so that liquid working medium in an outer copper tube 41 of a pulsating heat tube 4 tightly attached to the inner wall of the evacuated collector tube 2 absorbs heat to form an air plug, the working medium in the outer copper tube 41 conveys heat to a water storage tank 5 and conducts heat exchange under the pushing of the air plug, the working medium in the outer copper tube 41 is condensed along with the air plug and falls back into the outer copper tube 41 under the action of gravity to continue conducting heat with the inner wall of the evacuated collector tube 2, and the heat exchange is conducted repeatedly in such a way and continuously conducts heat exchange with the water storage tank 5;

when the water temperature in the water storage tank 5 rises, the temperature difference between the outer copper tube 41 of the pulsating heat pipe 4 and the water storage tank 5 is smaller and smaller, working media in the outer copper tube 41 cannot be completely condensed, more longer air plugs can be formed, the pressure in the outer copper tube 41 is higher and higher, the working media flow back into the inner copper tube 42 wrapped by the phase change material 8 under the pushing of the internal pressure, at the moment, redundant heat of the working media is absorbed by the phase change material 8 and condensed, the heat is stored in the phase change material 8, heat storage when the heat is excessive, the working media flow back after being condensed, liquid working media are supplemented to the adjacent outer copper tube 41, the operation is repeated, and the unidirectional circulation heat collection of the pulsating heat pipe 4 with the closed loop columnar winding structure is realized.

The invention adopts the pulsating heat pipe 4 with high heat transfer coefficient as the heat transfer component in the vacuum heat collecting pipe 2, wherein the pulsating heat pipe 4 is a closed loop columnar winding structure, the outer copper pipe 41 of the evaporation section 401 is directly contacted with the inner wall of the vacuum heat collecting pipe 2, and seamless attachment is realized through heat-conducting silicone grease, compared with the combination of the common pulsating heat pipe and the vacuum heat collecting pipe 2, the invention can greatly reduce contact thermal resistance, increase heat exchange area and further improve heat transfer efficiency; the inner copper tube 42 extends into the cavity 7 filled with the phase-change material 8, the outer copper tube 41 is driven by the air plug to be transferred to the elbow in the water storage tank 5 for condensation after heat collection, compared with a common phase-change material heat tube type vacuum tube heat collector, the water production speed can be greatly improved, when the temperature of the water tank rises, the air plug carrying heat in the pulsating heat tube 4 passes over the elbow, and is conveyed to the inner copper tube 42 to transfer heat to the phase-change material 8 for condensation, so that heat storage is realized when the heat is excessive; the liquid working medium is condensed in the inner copper tube 42 and then flows back to the elbow at the bottom, and the liquid working medium is supplemented to the adjacent outer copper tube 41, so that the reciprocating operation is favorable for the unidirectional operation of the pulsating heat tube 4, the starting characteristic is optimized, and the operation efficiency of the heat tube is improved.

According to the invention, the cavity wall constructed by polytetrafluoroethylene is arranged in the vacuum heat collecting tube 2, so that the phase change material 8 with low heat conductivity coefficient in the cavity 7 is not in direct contact with the inner wall of the vacuum heat collecting tube 2, and the problem of overlarge heat resistance of the traditional heat storage type heat pipe type vacuum tube can be greatly improved; and the polytetrafluoroethylene adopted by the cavity wall is a heat insulation material, so that the heat leakage loss of the phase-change material 8 at night can be reduced.

According to the invention, the linear Fresnel lens 1 in a curved surface shape is adopted for light condensation and heat collection, the compound parabolic condenser 3 is used for secondary light condensation, and one Fresnel lens light condensation unit is matched with a single evacuated collector tube 2, so that the heat grade is effectively improved, the heat flux density is improved, the cost is reduced, and the application prospect is good.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.