Ribbed spherical phase change material capsule, layered heat storage tank and solar heat storage system

Abstract

The present disclosure provides a ribbed spherical phase change material capsule, a layered heat storage tank and a solar heat storage system. The ribbed spherical phase change material capsule comprises a shell, a phase change material and a plurality of longitudinal ribs arranged on the outer surface of the shell. The plurality of longitudinal ribs are arranged to extend from the polar region to the equatorial region along the meridian direction of the shell and are uniformly spaced along the circumferential direction of the shell. By the above technical solution, the shell surface of the capsule is provided with a plurality of longitudinal ribs, which can increase the heat transfer area and disturb the surrounding heat transfer fluid, induce boundary layer transition, delay flow separation, suppress local heat retention area, strengthen the convective heat transfer effect between the capsule and the fluid, realize rapid melting or solidification of the phase change material, reduce the interfacial thermal resistance and improve the uniformity of the internal temperature, shorten the heat charging and discharging time, improve the heat efficiency, and have better cycle stability. It is suitable for dense packing and large-scale heat storage applications.

Description

Technical Field

[0001] This disclosure relates to the field of solar energy storage technology, specifically to a ribbed spherical phase change material capsule, a layered thermal storage tank, and a solar thermal storage system. Background Technology

[0002] Solar thermal energy storage systems convert solar energy into thermal energy for storage or use, representing a highly efficient and environmentally friendly energy conversion method. However, existing solar thermal energy storage systems generally suffer from problems such as a mismatch between solar energy supply and heat load demand, low energy utilization efficiency under off-peak conditions, and poor heat transfer performance of the storage equipment. These issues can be addressed using thermal energy storage technology based on phase change materials (PCMs). By utilizing the absorption and release of latent heat during the phase change process of PCMs, the thermal energy storage density is increased, thus solving the problems of intermittency and fluctuation in solar energy utilization and improving the efficiency of solar energy utilization.

[0003] In related technologies, phase change materials (PCCs) used in solar thermal storage systems typically employ an encapsulated PCC capsule structure, which features simple structure, good mechanical stability, and ease of stacking. However, the surface of traditional PCC capsules is relatively smooth, resulting in a limited effective heat transfer area, weak turbulence on the surrounding heat transfer fluid, and a low convective heat transfer coefficient. This leads to a prolonged heat charging and releasing process in the thermal storage device, making it difficult to meet the requirements for efficient thermal energy storage and extraction. Summary of the Invention

[0004] The purpose of this disclosure is to provide a ribbed spherical phase change material capsule, a layered thermal storage tank, and a solar thermal storage system to at least partially solve the problems existing in the aforementioned related technologies.

[0005] To achieve the above objectives, a first aspect of this disclosure provides a ribbed spherical phase change material capsule, comprising: a shell configured as a spherical structure, the interior of the shell being hollow; a phase change material disposed within the shell; and longitudinal ribs disposed on the outer surface of the shell, wherein the number of longitudinal ribs is multiple, the multiple longitudinal ribs are configured to extend from the polar region to the equatorial region along the meridional direction of the shell, and the multiple longitudinal ribs are evenly spaced along the circumference of the shell.

[0006] Optionally, the longitudinal rib includes: a first segment connected to the outer surface of the shell, the width of the first segment being set to rib width w; a second segment connected to the end of the first segment away from the shell, the second segment being configured as a tapered structure that gradually narrows away from the shell, the height of the second segment being defined as d; the upper end of the second segment is provided with a rounded corner, the radius of the rounded corner being defined as r, to form a smooth transition at the rib top; wherein, the total height of the longitudinal rib is defined as h, used to represent the height of the complete rib structure from one of the polar regions of the shell to the other polar region, wherein the rib width w, the radius r, and the height d are configured to remain uniform or vary relative to the extension direction of the total height h of the longitudinal rib.

[0007] Optionally, the cross-sectional shape of the longitudinal rib is set to one or a combination of rectangular, trapezoidal, spindle-shaped and curved structures.

[0008] Optionally, at least a portion of the longitudinal ribs on each of the housings may have different cross-sectional shapes.

[0009] Optionally, the number of longitudinal ribs is set to no more than thirty-two and no less than two, and the circumferential spacing between any two adjacent longitudinal ribs is configured to be selectively adjustable to form heat exchange zones of different sizes for heat exchange with the airflow.

[0010] A second aspect of this disclosure provides a layered thermal storage tank, comprising: a grid-type packed bed with a plurality of vertically arranged baffles for forming a plurality of grid-like receiving cavities in a horizontal direction; and the ribbed spherical phase change material capsules provided according to a first aspect of this disclosure, wherein the ribbed spherical phase change material capsules are disposed in the receiving cavities, and the number of ribbed spherical phase change material capsules in any one receiving cavity is plurality, wherein the plurality of ribbed spherical phase change material capsules located in the same receiving cavity are arranged along the vertical direction.

[0011] Optionally, a plurality of the ribbed spherical phase change material capsules are configured in the grid-type packed bed to form a thermal jump layer in the vertical direction.

[0012] A third aspect of this disclosure provides a solar thermal energy storage system, comprising: a thermal energy harvesting system; a circulation system including a heat exchange pipeline and a plurality of valves disposed on the heat exchange pipeline for controlling the opening and closing of the heat exchange pipeline; a water storage system; a stratified thermal energy storage system including a stratified thermal storage tank as described in any one of claims 6-7; and a thermal energy utilization system, wherein the water storage system and the thermal energy utilization system are connected through the heat exchange pipeline, and the thermal energy harvesting system, the water storage system, and the stratified thermal energy storage system are connected through the heat exchange pipeline.

[0013] Optionally, the thermal energy harvesting system includes multiple solar collectors for absorbing solar energy.

[0014] Optionally, the circulation system further includes: a first control valve disposed at the input end of the thermal energy harvesting system; a circulation pump disposed between the first control valve and the first port of the stratified thermal energy storage system; a second control valve disposed in parallel with the circulation pump between the first control valve and the first port of the stratified thermal energy storage system; a third control valve disposed at the output end of the thermal energy harvesting system, and the third control valve is selectively connected to the second port of the stratified thermal energy storage system and the input end of the water storage system, respectively; a fourth control valve disposed at the first port of the stratified thermal energy storage system, for selectively connecting the stratified thermal energy storage system to the second control valve and the circulation pump, respectively; and a fifth control valve disposed at the output end of the water storage system, for preventing fluid backflow.

[0015] Optionally, the circulation system includes: a first circulation loop comprising the heat energy harvesting system, the second control valve, the circulation pump, the fifth control valve, the water storage system, and the third control valve connected in sequence, for allowing fluid to flow between the heat energy harvesting system and the water storage system; a second circulation loop comprising the heat energy harvesting system, the second control valve, the circulation pump, the fourth control valve, the stratified heat energy storage system, and the third control valve connected in sequence, for allowing fluid to flow between the heat energy harvesting system and the stratified heat energy storage system; and a third circulation loop comprising the water storage system, the third control valve, the stratified heat energy storage system, the fourth control valve, the second control valve, the circulation pump, and the fifth control valve connected in sequence, for allowing fluid to flow between the stratified heat energy storage system and the water storage system.

[0016] Optionally, the water storage system includes: a water tank; an inlet connected to the thermal energy utilization system for receiving low-temperature fluid flowing out of the thermal energy utilization system; and an outlet connected to the thermal energy utilization system for outputting high-temperature fluid to the thermal energy utilization system.

[0017] Optionally, the thermal energy utilization system includes a thermal energy usage terminal.

[0018] Through the above technical solution, the capsule shell surface is provided with multiple longitudinal ribs extending from the polar region to the equatorial region along the meridian direction. This increases the heat transfer area and disturbs the surrounding heat transfer fluid, inducing early boundary layer transition, delaying flow separation, and suppressing local thermal stagnation zones. This enhances the convective heat transfer effect between the capsule and the fluid, enabling rapid melting or solidification of the phase change material, reducing interfacial thermal resistance, and improving the uniformity of internal temperature. Compared to smooth spherical capsules, this disclosure offers shorter charging and discharging times, higher thermal efficiency, better cycle stability, and is suitable for dense filling and large-scale thermal energy storage applications.

[0019] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0021] Figure 1 This is a schematic diagram of a solar thermal storage system according to an exemplary embodiment.

[0022] Figure 2 This is a schematic diagram of the internal structure of a layered thermal storage tank according to an exemplary embodiment.

[0023] Figure 3 This is a top view schematic diagram of a stratified thermal storage tank according to an exemplary embodiment.

[0024] Figure 4 This is a schematic diagram of the structure of a ribbed spherical phase change material capsule according to an exemplary embodiment.

[0025] Figure 5 This is a schematic cross-sectional view of a ribbed spherical phase change material capsule after being transversely cut along the equatorial region, according to an exemplary embodiment.

[0026] Figure 6 This is a schematic cross-sectional view of a ribbed spherical phase change material capsule cut longitudinally along the polar region, according to an exemplary embodiment.

[0027] Figure 7 This is a schematic longitudinal cross-sectional view of a longitudinal rib according to an exemplary embodiment.

[0028] Figure 8 This is a schematic diagram of the structure of a ribbed spherical phase change material capsule according to an exemplary embodiment.

[0029] Figure 9 This is a schematic diagram of the structure of a ribbed spherical phase change material capsule according to an exemplary embodiment.

[0030] Explanation of reference numerals in the attached figures:

[0031] 10-Heat energy harvesting system, 11-Heat collector, 20-Circulation system, 21-Circulation pump, 22-First control valve, 23-Second control valve, 24-Third control valve, 25-Heat exchange pipeline, 26-Fourth control valve, 27-Fifth control valve, 30-Water storage system, 31-Water tank, 32-Inlet, 33-Outlet, 40-Layered heat energy storage system, 41-Ribbed spherical phase change material capsule, 411-Shell, 4111-Polar region, 4112-Equatorial region, 412-Phase change material, 413-Longitudinal rib, 42-Grid-type packed bed, 43-Liquid inlet, 44-Liquid outlet, 50-Heat energy utilization system, 51-Heat energy use terminal. Detailed Implementation

[0032] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0033] In this disclosure, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" generally refer to the upper and lower, top and bottom of the relevant components in actual use. "Inner" and "outer" refer to the inner and outer sides of the relevant components relative to the actual contour. Furthermore, the terms "first," "second," etc., used in this disclosure are for distinguishing one element from another and do not have sequential or importance implications.

[0034] The first aspect of this disclosure provides a ribbed spherical phase change material capsule, with reference to... Figures 2 to 9 The ribbed spherical phase change material capsule 41 includes a shell 411, a phase change material 412, and longitudinal ribs 413. The shell 411 is configured as a spherical structure with a hollow interior. The phase change material 412 is disposed inside the shell 411. The longitudinal ribs 413 are disposed on the outer surface of the shell 411. There are multiple longitudinal ribs 413, which are arranged to extend from the polar region 4111 to the equatorial region 4112 along the meridional direction of the shell 411, and the multiple longitudinal ribs 413 are evenly spaced along the circumference of the shell 411.

[0035] In the above embodiment, the shell 411 adopts a spherical hollow structure, and the phase change material 412 is encapsulated inside the shell 411. Within a preset operating temperature range, a reversible solid-liquid phase change can occur. The phase change material transitions from solid to liquid, which is a heat-charging process, allowing it to absorb latent heat through the shell 411. The phase change material transitions from liquid to solid, which is a heat-releasing process, allowing it to release latent heat through the shell 411, achieving high-density thermal energy storage and stabilizing the temperature change of the heat exchange fluid. Longitudinal ribs 413 extend from the polar region 4111 to the equatorial region 4112 along the meridional direction of the shell 411, and are evenly spaced circumferentially. This increases the effective heat exchange area of ​​the capsule, while simultaneously disturbing the boundary layer of the heat exchange fluid, disrupting the thermal stagnation region, inducing the formation of micro-vortices, and enhancing the convective heat transfer efficiency between the phase change material 412 and the heat exchange fluid. The meridional arrangement ensures smooth flow of the fluid around the capsule and reduces local flow resistance.

[0036] For example, refer to Figures 4 to 9 The longitudinal rib 413 may include a first segment and a second segment. The first segment may be connected to the outer surface of the housing 411, and the width of the first segment may be set to the rib width w. The second segment may be connected to the end of the first segment away from the housing, and the second segment may be configured as a tapered structure that gradually narrows away from the housing 411. The height of the second segment may be set to d, and the upper end of the second segment may be provided with a rounded corner, the radius of which may be set to r, so as to form a smooth transition at the rib top. The total height of the longitudinal rib 413 may be set to h, which is used to represent the height of the complete rib structure from one polar region 4111 of the housing 411 to the other polar region 4111. The rib width w, radius r, and height d are configured to remain uniform or vary relative to the extension direction of the total height h of the longitudinal rib 413.

[0037] In the above embodiment, the longitudinal rib 413 adopts a two-section structure. The first section serves as a connecting base to ensure the connection strength with the shell 411 and prevent the rib from falling off. The second section tapers outward away from the shell 411 and is equipped with rounded corners. The rounded corner structure can reduce stress concentration, prevent the rib from cracking during thermal cycling, and reduce fluid flow resistance, thereby reducing pressure loss. At the same time, the rib width w, rounded corner radius r, and height d can be kept uniform or varied along the extension direction of the total height h of the longitudinal rib 413, so that capsules with different longitudinal rib 413 structures can be flexibly selected according to heat exchange requirements and fluid flow rate. This allows for precise control of flow resistance while enhancing heat exchange, ensuring a balance between capsule durability and heat exchange efficiency.

[0038] It should be noted that the total height h can be used to change the degree of protrusion of the ribs towards the surrounding heat transfer fluid, affecting the overall effective heat transfer area of ​​the capsule. Higher longitudinal ribs 413 can increase the surface area and enhance the turbulence of the fluid around the capsule, thereby improving convective heat transfer efficiency. However, an excessively high total height h may also increase flow resistance and pressure drop, requiring adaptive adjustments based on the actual fluid velocity and operating conditions. Simultaneously, the rib width w affects both the heat conduction path through the capsule shell and the interaction with the surrounding fluid. Wider longitudinal ribs 413 provide a larger thermal conduction area for heat transfer from the shell to the phase change material 412, contributing to uniform melting and solidification. A smaller rib width w can generate more localized turbulence in the fluid, thereby enhancing boundary layer disturbance and accelerating heat exchange. Furthermore, the height d between adjacent longitudinal ribs 413 is a factor affecting fluid flow behavior and heat transfer performance. A higher height d can form a deeper groove structure between any two adjacent longitudinal ribs 413, which can enhance fluid mixing, induce local circulation, and thin the thermal boundary layer, thereby improving heat transfer efficiency. A lower height d can form a shallower groove structure, which can provide a smoother flow path, reduce pressure drop, and reduce potential fluid stagnation. At the same time, the fillet radius r can be used to change fluid dynamics and heat transfer efficiency. When the fluid bypasses the longitudinal ribs 413, the fillets at the tips and roots can reduce turbulence and flow separation caused by sharp edges, thereby reducing flow resistance, ensuring smooth fluid flow through the interrib area, promoting uniform heat transfer along the ribs and capsule surface, avoiding local overheating or thermal stress concentration, improving material lifespan, increasing the contact area between the fluid and the ribs, and enabling faster and more uniform heat transfer during charging and discharging.

[0039] Meanwhile, depending on the actual fluid flow rate or fluid type, the capsule can be selected with longitudinal ribs 413 having different total height h, rib width w, corner radius r, and height d, so as to adjust the capsule configuration according to different positions, reduce the temperature gradient inside the phase change material 412, which is conducive to the formation of a stable thermal jump layer in the grid-type packed bed 42, enabling the system to effectively cope with changing heat loads and fluid flow conditions, thereby improving the overall thermal energy storage efficiency and energy utilization rate, and extending the service life of the stratified thermal energy storage system 40.

[0040] For example, the cross-sectional shape of the longitudinal rib 413 may be set as one of a rectangular, trapezoidal, spindle-shaped and curved structure or any combination of two, and the cross-sectional shape of at least a portion of the longitudinal ribs 413 on each shell 411 may be set to be different.

[0041] In the above embodiments, the longitudinal ribs 413 can be selected from a variety of cross-sectional shapes. Rectangular and trapezoidal cross-sections can increase the heat exchange area, while fusiform and curved cross-sections can optimize the fluid flow state and reduce flow resistance. Longitudinal ribs 413 with different cross-sectional shapes can be used on a single capsule to form heat exchange zones of different sizes on the capsule surface, adapting to the heat exchange requirements of airflows with different flow rates and further improving heat exchange uniformity.

[0042] For example, refer to Figures 4 to 9 The number of longitudinal ribs 413 can be set to no more than thirty-two and no less than two, and the circumferential spacing between any two adjacent longitudinal ribs 413 can be configured to be selectively adjustable to form heat exchange zones of different sizes for heat exchange with the airflow.

[0043] In the above embodiments, the number of longitudinal ribs 413 is limited to 2 to 32. This range can balance heat exchange area and flow resistance control. The circumferential spacing between adjacent longitudinal ribs 413 can be adjusted to form differentiated heat exchange zones on the capsule surface, adapting to the airflow heat exchange requirements under different operating conditions, avoiding excessive or insufficient local heat exchange, and improving the synchronization of charge and release heat of the phase change material 412. For example Figure 8 The capsules in this type of capsule have a relatively small number of longitudinal ribs 413. This type of capsule can reduce fluid resistance and increase flow rate. Figure 9 The capsules in this type of capsule have a relatively large number of longitudinal ribs 413. This type of capsule can increase the heat exchange area and improve the heat exchange efficiency, thereby increasing the latent heat absorption value per unit capsule. The appropriate type can be selected based on actual heat exchange requirements, which will not be elaborated upon here.

[0044] A second aspect of this disclosure provides a layered thermal storage tank, referring to... Figure 2 and Figure 3 The layered thermal storage tank may include a grid-type packed bed 42 and ribbed spherical phase change material capsules 41 provided in the first aspect embodiment of this disclosure. The grid-type packed bed 42 may be provided with multiple vertically arranged baffles to form multiple grid-like receiving cavities in the horizontal direction. The ribbed spherical phase change material capsules 41 may be disposed in the receiving cavities, and the number of ribbed spherical phase change material capsules 41 in any one receiving cavity may be multiple. Multiple ribbed spherical phase change material capsules 41 located in the same receiving cavity may be arranged vertically.

[0045] In the above embodiments, the grid-type packed bed 42 forms a grid-like receiving cavity through vertical partitions, realizing the orderly positioning of the ribbed spherical phase change material capsules 41, avoiding random stacking, compression, and displacement of the capsules. The capsules in the same receiving cavity are arranged vertically, which can ensure that the heat exchange fluid flows evenly over all capsule surfaces, eliminate preferential flow channels and stagnant areas, and optimize the flow field distribution. At the same time, the vertical arrangement structure design can be combined with the natural thermal stratification characteristics of vertical storage tanks, using the difference in fluid density to form an upper and lower temperature gradient, improving the stability of thermal energy storage and extraction. The grid-type structure has a high degree of modularity, and the number of receiving cavities and the capsule filling amount can be flexibly adjusted according to the size of the storage tank and the energy storage capacity.

[0046] In other embodiments, the diameter ratio of the receiving cavity to the capsule within the grid-like packed bed 42 can be set to 1.5. In this embodiment, by changing the diameter ratio of the channels formed by the grid-like receiving cavity to the capsule, the heat transfer and flow effects of the fluid can be altered. Specifically, when the diameter ratio of the channel to the capsule is less than 3.5, the fluid is significantly affected by the wall effect, and the fluid flow and heat transfer are strongly constrained by the space within the grid-like packed bed 42. When the diameter ratio of the channel to the capsule is 1.5, the capsule is placed more tightly within the receiving cavity, the confined space is smaller, which allows for interaction between the capsule surface and the surrounding fluid, enhancing the convective heat transfer efficiency within the confined channels between the ribs. Simultaneously, this channel spacing can control the system pressure drop, maintain stable thermal stratification, balance the fluid contact with the capsule surface, control the flow rate, and ensure efficient charge-discharge heat cycles within the stratified thermal energy storage system 40.

[0047] For example, refer to Figure 2 and Figure 3 Multiple ribbed spherical phase change material capsules 41 are configured in a grid-type packed bed 42 to form a thermoclastic layer in the vertical direction.

[0048] In the above embodiment, the vertically arranged ribbed spherical phase change material capsules 41 form a stable thermoclastic layer along the vertical direction during the charge-discharge cycle. The thermoclastic layer is an interface region with rapid temperature changes, clearly separating the high-temperature zone and the low-temperature zone within the storage tank, reducing the mixing of hot and cold fluids, improving heat exchange efficiency, allowing the phase change material to fully participate in heat exchange, slowing down the heat penetration rate, and improving the stability of system temperature control. It should be noted that the thermoclastic layer is usually a primary thermoclastic layer that moves vertically during the charge-discharge process. Under complex operating conditions, multiple secondary thermoclastic layers can be formed. The ribbed spherical phase change material capsules 41 are arranged sequentially along the vertical direction, which can enhance the thermoclastic layering effect.

[0049] In other embodiments, during the charging process of the stratified thermal energy storage system 40, the hot fluid can enter the interior of the grid-type packed bed 42 from the liquid outlet 44 at the top of the grid-type packed bed 42, and the capsule can absorb heat. During the heat release process of the stratified thermal energy storage system 40, the hot fluid can enter from the liquid inlet 43 at the bottom. After contacting the capsule, the fluid absorbs heat from the phase change material 412 inside the capsule and leaves from the liquid outlet 44 at the top. The heat exchange efficiency is high, and the heat exchange effect is uniform and stable.

[0050] A third aspect of this disclosure provides a solar thermal storage system, referring to... Figure 1The solar thermal energy storage system may include a thermal energy harvesting system 10, a circulation system 20, a water storage system 30, a stratified thermal energy storage system 40, and a thermal energy utilization system 50. The circulation system 20 includes a heat exchange pipeline 25 and multiple valves disposed on the heat exchange pipeline 25 for controlling the opening and closing of the heat exchange pipeline 25. The stratified thermal energy storage system 40 includes a stratified thermal storage tank as provided in the second aspect embodiment of this disclosure. The water storage system 30 and the thermal energy utilization system 50 are connected via the heat exchange pipeline 25, and the thermal energy harvesting system 10, the water storage system 30, and the stratified thermal energy storage system 40 are connected via the heat exchange pipeline 25.

[0051] In the above embodiment, the thermal energy acquisition system 10 serves as the system heat source, absorbing solar energy and converting it into thermal energy. The circulation system 20, through the heat exchange pipeline 25 and the control valve, realizes the directional and quantitative control of fluid flow direction and flow rate. The water storage system 30 is used to buffer and store hot water to meet immediate heat demand. The stratified thermal energy storage system 40, with a stratified thermal storage tank as its core, realizes high-density latent heat storage. The thermal energy utilization system 50 is the terminal heat use unit. All components form a closed-loop thermal energy acquisition, storage, and utilization system through the heat exchange pipeline 25.

[0052] For example, refer to Figure 1 The thermal energy collection system 10 includes multiple solar collectors 11 for absorbing solar energy. The multiple solar collectors 11 can be connected in series or in parallel to improve the solar energy absorption efficiency and meet the heating needs of different scales.

[0053] For example, refer to Figure 1 The circulation system 20 includes a first control valve 22, a circulation pump 21, a second control valve 23, a third control valve 24, a fourth control valve 26, and a fifth control valve 27. Specifically, the first control valve 22 is located at the input end of the heat energy harvesting system 10; the circulation pump 21 is located between the first control valve 22 and the first port of the stratified heat energy storage system 40; the second control valve 23 is connected in parallel with the circulation pump 21 between the first control valve 22 and the first port of the stratified heat energy storage system 40; the third control valve 24 is located at the output end of the heat energy harvesting system 10 and is selectively connected to the second port of the stratified heat energy storage system 40 and the input end of the water storage system 30; the fourth control valve 26 is located at the first port of the stratified heat energy storage system 40 to selectively connect the stratified heat energy storage system 40 to the second control valve 23 and the circulation pump 21; and the fifth control valve 27 is located at the output end of the water storage system 30 to prevent fluid backflow.

[0054] In the above embodiments, the first control valve 22 and the second control valve 23 regulate the flow rate and direction of the fluid entering the system, the circulation pump 21 provides power for fluid circulation, the third control valve 24 realizes the directional delivery of fluid to the stratified thermal energy storage system 40 or the water storage system 30, the fourth control valve 26 regulates the fluid inflow and outflow of the stratified thermal storage tank, and the fifth control valve 27 is a check valve to prevent hot water backflow and ensure the hydraulic stability of the system.

[0055] During operation, the thermal energy harvesting system 10 absorbs solar radiation and converts it into thermal energy, which is transferred by the heat exchange fluid through the circulation system 20. The circulation pump 21 drives the fluid to circulate in the heat exchange pipeline 25. Simultaneously, the first control valve 22, the second control valve 23, and the third control valve 24 can respectively adjust the flow rate, flow direction, and pressure at different locations to improve thermal energy transfer efficiency and reduce energy loss. After entering the thermal stratification thermal energy storage system 40, the heat exchange fluid can exchange heat with the ribbed spherical phase change material capsules 41. Each phase change material capsule 41 includes a capsule shell 411 covering the phase change material 412 and multiple longitudinal ribs 413 formed on its outer surface. The longitudinal ribs 413 can increase the effective heat exchange area by disturbing the fluid boundary layer, accelerating the heat transfer between the phase change material 412 and the fluid, thereby improving the charge / discharge efficiency and overall thermal energy storage performance. After heat exchange, the cooled fluid can be circulated back to the thermal energy harvesting system 10 through the second port at the top, or directed to the thermal energy utilization system 50 for end-use.

[0056] For example, refer to Figure 1 The circulation system 20 may include a first circulation loop, a second circulation loop, and a third circulation loop. The first circulation loop may include a heat energy harvesting system 10, a second control valve 23, a circulation pump 21, a fifth control valve 27, a water storage system 30, and a third control valve 24 connected in sequence, for allowing fluid to flow between the heat energy harvesting system 10 and the water storage system 30. The second circulation loop may include a heat energy harvesting system 10, a second control valve 23, a circulation pump 21, a fourth control valve 26, a stratified heat energy storage system 40, and a third control valve 24 connected in sequence, for allowing fluid to flow between the heat energy harvesting system 10 and the stratified heat energy storage system 40. The third circulation loop may include a water storage system 30, a third control valve 24, a stratified heat energy storage system 40, a fourth control valve 26, a second control valve 23, a circulation pump 21, and a fifth control valve 27 connected in sequence, for allowing fluid to flow between the stratified heat energy storage system 40 and the water storage system 30.

[0057] In the above implementation, the three circulation loops can operate independently or in coordination to achieve efficient allocation of solar thermal energy: the first circulation loop is a direct heating loop, in which high-temperature fluid directly heats the water storage system 30 when there is sufficient solar irradiance to meet immediate heat demand; the second circulation loop is a heat storage loop, in which high-temperature fluid enters the stratified heat storage tank to complete latent heat storage when there is excess heat; and the third circulation loop is a heat release loop, in which the stratified heat storage tank releases heat energy to heat the water storage system 30 when there is no solar irradiance to continuously supply hot water.

[0058] It should be noted that when the system is in the first circulation loop, the third control valve 24 guides the high-temperature fluid from the heat energy harvesting system 10 into the water tank 31 of the water storage system 30. Inside the water tank 31, the fluid releases heat to the stored heat exchange fluid through convection and conduction, thereby increasing the water temperature inside the tank. The heated heat exchange fluid can then be piped to the heat energy usage terminal 51. Under conditions of sufficient solar irradiance, the first circulation loop can operate independently to better utilize real-time solar energy and avoid unnecessary energy storage losses. Furthermore, the first circulation loop can also operate in conjunction with the second circulation loop, allowing some solar energy to be directly supplied to the water tank 31 for heating, while the remaining heat is introduced into the stratified heat energy storage system 40 to optimize overall energy utilization performance. When solar irradiance weakens, the first circulation loop can still continue to operate, and heat can be supplemented through energy release from the third circulation loop or by auxiliary electric heating devices.

[0059] The second circulation loop is used to charge the stratified thermal energy storage system 40, primarily activated during periods of high solar irradiance or low immediate hot water demand. In this loop, the high-temperature fluid heated by the collector 11 is diverted by the third control valve 24 into the second port of the stratified thermal storage tank. The fluid flows downwards within the tank through a grid-like packed bed 42 composed of ribbed spherical phase change material capsules 41. The capsules have longitudinal ribs 413 on their outer walls, which enhance fluid turbulence and increase the effective heat exchange area, thereby promoting stable heat exchange between the heat exchange fluid and the phase change material 412. During heat transfer, the phase change material changes from a solid to a liquid state, absorbing latent heat and completing heat absorption and temporary storage under near-isothermal conditions. After partial heat release, the cooled heat exchange fluid is discharged from the first port at the bottom of the tank and returned to the thermal energy harvesting system via the circulation pump 21, before re-entering the collector 11 for heating. Alternatively, it can be distributed to other circulation loops according to specific needs, improving the system's response flexibility under load fluctuations.

[0060] The third circulation loop can be used to release previously stored heat energy from the stratified thermal energy storage system 40 when solar irradiance is insufficient (e.g., at night or on cloudy days). At this time, the low-temperature fluid from the water tank 31, driven by the circulation pump 21, flows back from the water tank 31 into the lower first port of the thermal storage tank. The heat exchange fluid flows upward through the gridded packed bed 42, causing the phase change material to undergo a liquid-to-solid phase change process, and transferring heat to the fluid during latent heat release, thus raising its temperature. The heated heat exchange fluid is discharged from the upper second port of the storage tank and enters the third control valve 24 located at the outlet of the thermal storage tank. The third control valve 24 can selectively guide the fluid into the water tank 31 or direct it to other system pipelines, thereby achieving precise control of the released heat. Subsequently, the hot fluid released from the water tank 31 is delivered to the hot water user terminal through the outlet pipeline and the fifth control valve 27, ensuring continuous hot water output without backflow, effectively avoiding thermal short circuits, and ensuring the stability and controllability of the heat energy output process.

[0061] The three loops described above enable the system to operate independently or collaboratively under varying solar irradiance and hot water demand conditions. Under high solar irradiance conditions, the first loop directly supplies the current solar thermal energy to the water tank to meet immediate hot water demand. When the collected heat exceeds the tank's demand, the second loop activates simultaneously, storing the excess heat in the stratified thermal energy storage system 40. This allows the system to absorb peak solar energy under high irradiance conditions, reducing heat waste. When the stratified thermal energy storage system 40 approaches saturation or no longer requires further storage, it continues to operate independently, maintaining a stable hot water output. Under conditions of insufficient solar irradiance, cloudy days, or nighttime, the third loop activates, releasing previously stored heat through a phase change process from liquid to solid using the phase change material 412, and transferring it to the water tank 31 to maintain tank temperature and continuous hot water supply. Simultaneously, according to the control strategy, the third loop can also operate as an auxiliary loop when there is remaining usable heat, further improving overall system efficiency.

[0062] For example, refer to Figure 1 The water storage system 30 may include a water tank 31, an inlet 32 ​​and an outlet 33. The inlet 32 ​​may be connected to the heat energy utilization system 50 to receive low-temperature fluid flowing out of the heat energy utilization system 50. The outlet 33 is connected to the heat energy utilization system 50 to output high-temperature fluid to the heat energy utilization system 50.

[0063] In the above embodiment, the water tank 31 is a hot water storage container, the inlet 32 ​​recovers low-temperature fluid, and the outlet 33 outputs high-temperature fluid, forming a closed loop to ensure the continuous heat demand of the heat energy utilization system 50.

[0064] For example, refer to Figure 1The thermal energy utilization system 50 may include a thermal energy utilization terminal 51. This disclosure does not impose specific restrictions on the structure and form of the thermal energy utilization terminal 51, including but not limited to equipment for adapting to various heat use scenarios such as residential heating, commercial hot water, and industrial preheating. It can be adapted to actual application needs, and it is necessary to ensure that it can realize the function of on-demand utilization of solar thermal energy. This will not be elaborated here.

[0065] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0066] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0067] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A ribbed spherical phase change material capsule, characterized in that, include: The shell is configured as a spherical structure, and the interior of the shell is hollow. Phase change material is disposed within the housing; And longitudinal ribs, provided on the outer surface of the shell, the number of longitudinal ribs is multiple, the multiple longitudinal ribs are configured to extend from the polar region to the equatorial region along the meridian direction of the shell, and the multiple longitudinal ribs are evenly spaced along the circumference of the shell.

2. The ribbed spherical phase change material capsule according to claim 1, characterized in that, The longitudinal ribs include: The first segment is connected to the outer surface of the shell, and the width of the first segment is set to the rib width w; The second segment connects to the end of the first segment furthest from the housing. The second segment is configured as a tapered structure that gradually narrows away from the housing, and its height is set as d. The upper end of the second segment has a rounded corner with a radius of r to create a smooth transition at the rib top. The total height of the longitudinal ribs is set as h, representing the complete rib structure height from one polar region of the housing to the other. The rib width w, the radius r, and the height d are configured to remain uniform or vary relative to the extension direction of the total height h of the longitudinal rib.

3. The ribbed spherical phase change material capsule according to claim 2, characterized in that, The cross-sectional shape of the longitudinal rib is set to one or a combination of two of the following: rectangular, trapezoidal, spindle-shaped and curved structures.

4. The ribbed spherical phase change material capsule according to claim 3, characterized in that, The cross-sectional shape of at least a portion of the longitudinal ribs on each of the housings is set to be different.

5. The ribbed spherical phase change material capsule according to claim 1, characterized in that, The number of longitudinal ribs is set to no more than thirty-two and no less than two, and the circumferential spacing between any two adjacent longitudinal ribs is configured to be selectively adjustable to form heat exchange zones of different sizes for heat exchange with the airflow.

6. A layered thermal storage tank, characterized in that, include: A grid-type filling bed is provided with multiple vertically arranged partitions to form multiple grid-like receiving cavities in the horizontal direction; And the ribbed spherical phase change material capsule according to any one of claims 1-5, wherein the ribbed spherical phase change material capsule is disposed in the receiving cavity, and the number of the ribbed spherical phase change material capsules in any one of the receiving cavities is multiple, wherein the multiple ribbed spherical phase change material capsules located in the same receiving cavity are arranged along the vertical direction.

7. The stratified thermal storage tank according to claim 6, characterized in that, Multiple ribbed spherical phase change material capsules are configured in the grid-type packed bed to form a thermal jump layer in the vertical direction.

8. A solar thermal storage system, characterized in that, include: Thermal energy harvesting system; A circulation system includes heat exchange pipelines and multiple valves disposed on the heat exchange pipelines for controlling the opening and closing of the heat exchange pipelines; Water storage system; A stratified thermal energy storage system, comprising a stratified thermal storage tank as described in any one of claims 6-7; And thermal energy utilization systems, The water storage system and the thermal energy utilization system are connected through the heat exchange pipeline, and the thermal energy acquisition system, the water storage system and the stratified thermal energy storage system are connected through the heat exchange pipeline.

9. The solar thermal storage system according to claim 8, characterized in that, The thermal energy harvesting system includes multiple solar collectors for absorbing solar energy.

10. The solar thermal storage system according to claim 8, characterized in that, The circulatory system also includes: The first control valve is located at the input end of the thermal energy acquisition system; A circulating pump is disposed between the first control valve and the first port of the stratified thermal energy storage system; The second control valve is connected in parallel with the circulation pump between the first control valve and the first port of the stratified thermal energy storage system. A third control valve is located at the output end of the thermal energy acquisition system, and the third control valve is selectively connected to the second port of the stratified thermal energy storage system and the input end of the water storage system, respectively. The fourth control valve is located at the first port of the stratified thermal energy storage system, and is used to selectively connect the stratified thermal energy storage system to the second control valve and the circulating pump respectively. And a fifth control valve, located at the output end of the water storage system, is used to prevent fluid backflow.

11. The solar thermal storage system according to claim 10, characterized in that, The circulatory system includes: The first circulation loop includes the thermal energy harvesting system, the second control valve, the circulation pump, the fifth control valve, the water storage system, and the third control valve connected in sequence, for allowing fluid to flow between the thermal energy harvesting system and the water storage system; The second circulation loop includes the thermal energy harvesting system, the second control valve, the circulation pump, the fourth control valve, the stratified thermal energy storage system, and the third control valve connected in sequence, for allowing fluid to flow between the thermal energy harvesting system and the stratified thermal energy storage system; And a third circulation loop, comprising the water storage system, the third control valve, the stratified thermal energy storage system, the fourth control valve, the second control valve, the circulation pump, and the fifth control valve connected in sequence, for allowing fluid to flow between the stratified thermal energy storage system and the water storage system.

12. The solar thermal storage system according to claim 8, characterized in that, The water storage system includes: Water tank; The inlet is connected to the thermal energy utilization system and is used to receive the low-temperature fluid flowing out of the thermal energy utilization system. And an outlet, connected to the heat energy utilization system, for outputting high-temperature fluid to the heat energy utilization system.

13. The solar thermal storage system according to claim 8, characterized in that, The thermal energy utilization system includes thermal energy usage terminals.

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