Heat storage water tank inlet and outlet water distribution system based on numerical simulation

Abstract

The invention relates to the technical field of heat storage, and discloses a heat storage water tank inlet and outlet water distribution system based on numerical simulation, which comprises an integrated water distributor body, and the integrated water distributor body comprises a water inlet interface module, a water outlet interface module and an internal flow channel network module connected between the water inlet interface module and the water outlet interface module. The internal flow channel network module is of an irregular hierarchical bifurcated structure generated through topological optimization, the total sectional area of a fluid channel is gradually increased in the flowing direction, and the generation method of the internal flow channel network module is based on numerical simulation by constructing a composite function with the purpose of minimizing outlet kinetic energy flux and energy dissipation under multiple working conditions. And applying bionic bifurcation network constraint, and finally obtaining an integrated three-dimensional model which can be directly used for additive manufacturing through topological optimization iterative solution. The outlet kinetic energy can be remarkably reduced, fluid mixing is effectively restrained, temperature stratification is protected to the maximum extent, and therefore the overall energy utilization efficiency of a heat storage system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat storage, in particular to a water distribution system for water inlet and outlet of a heat storage tank based on numerical simulation. BACKGROUND

[0002] In many energy-saving systems such as district heating, solar comprehensive utilization, and central air conditioning, the heat storage tank is a key device for realizing time shift of energy, balancing load fluctuation, and improving system operation efficiency. The core working mechanism thereof relies on stable temperature stratification formed in the tank body due to water density difference. A clear and stable temperature stratification can ensure that the highest quality hot water is obtained at the energy output end and the lowest temperature return water is provided at the energy input end, thereby maximizing the effective available energy and energy conversion efficiency of the entire system.

[0003] However, in the process of charging or discharging hot water into the heat storage tank, the process of water inlet and outlet itself is the largest disturbance source to the stable stratification. In order to minimize this disturbance, a water distributor is usually deployed inside the tank body. The existing water distributor design mostly relies on traditional structures such as perforated pipes, radial discs, or multi-nozzle arrays. Although the original intention of these designs is to disperse concentrated pipe flows, their structural forms are often limited by traditional manufacturing processes and design methods based on simplified theory.

[0004] This leads to an inherent defect in the existing technology in actual application: even after dispersion, the local flow velocity of the fluid when finally leaving the water distributor and entering the tank body is still too high. This water flow carrying high kinetic energy will form an impact jet, generating strong turbulence and fluid entrainment near the outlet, inevitably causing violent mixing with the surrounding water body. This mixing effect directly erodes and destroys the valuable temperature and temperature layer, causing heat to mix prematurely and uncontrollably, essentially reducing the energy storage quality of the heat storage device. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a water distribution system for water inlet and outlet of a heat storage tank based on numerical simulation, which solves the problem of high outlet flow velocity of the existing water distributor, disturbance of temperature stratification in the heat storage tank, and influence on system energy conversion efficiency.

[0006] To achieve the above purpose, the present application provides a water distribution system for water inlet and outlet of a heat storage tank based on numerical simulation, which includes an integrated water distributor body, the integrated water distributor body includes a water inlet interface module, a water outlet interface module, and an internal flow channel network module communicating the water inlet interface module and the water outlet interface module.

[0007] The internal flow channel network module has a hierarchical branching structure. The key point is that the overall three-dimensional structure of the internal flow channel network module is determined through an optimization process that aims to minimize the preset performance indicators of the system under at least two different operating conditions.

[0008] In one specific implementation, the overall three-dimensional structure of the internal flow channel network module is determined by minimizing the composite objective function J. obj And the determined composite objective function J obj The mathematical expression is:

[0009]

[0010] in:

[0011] J obj The composite objective function;

[0012] N is the number of operating conditions, and N≥2;

[0013] i is an index representing a specific operating condition, and its value ranges from 1 to N;

[0014] w i Let be the weighting factor for the i-th operating condition;

[0015] J i Let be the objective function for a single operating condition under the i-th operating condition.

[0016] Furthermore, the single-condition objective function J i It includes a weighted sum of an energy dissipation term and an outlet kinetic flux term, wherein the energy dissipation term is used to characterize the flow resistance of the system under the i-th operating condition, and the outlet kinetic flux term is used to characterize the water distribution uniformity of the system under the i-th operating condition.

[0017] In a preferred embodiment, the hierarchical bifurcation structure of the internal flow channel network module is guided by biomimetic bifurcation network constraints based on Murray's law during its generation process. These constraints cause the equivalent diameter of the parent pipe at any bifurcation node in the hierarchical bifurcation structure to approximately satisfy the following relationship with the equivalent diameter of the child pipe at that node:

[0018]

[0019] in:

[0020] d p The equivalent diameter of the main pipe at the bifurcation node;

[0021] m is a preset exponent;

[0022] M is the total number of sub-pipes branching off from the bifurcation node;

[0023] j is the index representing a specific sub-pipeline, and its value ranges from 1 to M;

[0024] d c,j Let be the equivalent diameter of the j-th sub-pipe.

[0025] The internal flow channel network module includes a main channel extending from the water inlet interface module, and multiple end channels formed by the main channel after at least one branching, extending to the water outlet interface module. As the fluid flows from the main channel to the multiple end channels, the total cross-sectional area of ​​the flow channel is designed to gradually increase in order to achieve a gradual decrease in flow velocity.

[0026] The integrated water distributor body generated through this optimization process has a three-dimensional organic form with a free-form surface profile. This integrated water distributor body can be integrally formed through additive manufacturing process.

[0027] A second aspect of the present invention provides a water distribution method for the inlet and outlet of a hot water storage tank based on numerical simulation, comprising the following steps:

[0028] A three-dimensional calculation model of the hot water storage tank is established, and a design domain is defined at the inlet and outlet positions of the model.

[0029] A composite objective function is constructed, which aims to minimize the energy dissipation and outlet kinetic energy flux of the water distribution system under at least two different operating conditions.

[0030] A biomimetic bifurcation network constraint based on Murray's law is applied to the composite objective function;

[0031] The composite objective function and the biomimetic bifurcation network constraints are iteratively solved using a topology optimization algorithm to generate the optimal material distribution within the design domain, thereby determining the three-dimensional structure of the water distribution system.

[0032] This invention provides a water distribution system for hot water storage tanks based on numerical simulation. It offers the following advantages:

[0033] 1. This invention employs an optimization process aimed at minimizing preset performance indicators of the system under at least two different operating conditions, and constructs a corresponding composite objective function, so that the final water distribution system can maintain water distribution uniformity over a wide operating range. This solves the technical defect of the prior art where the water distributor only performs optimally under a single rated operating condition and its performance drops sharply under varying operating conditions. Thus, it can more effectively maintain the thermal stratification structure inside the hot water storage tank and improve the overall efficiency of the energy storage system in actual operation.

[0034] 2. This invention, by simultaneously optimizing both the energy dissipation term (characterizing flow resistance) and the outlet kinetic flux term (characterizing water distribution uniformity) in the composite objective function, enables the generated water distribution system to simultaneously achieve the two technical effects of low flow resistance and uniform water distribution. Low flow resistance directly reduces the energy consumption of external conveying equipment; while uniform and low-speed water distribution reduces the impact disturbance on the thermal stratification interface inside the tank. This resolves the technical contradiction in existing technologies that typically require high resistance to achieve uniform water distribution.

[0035] 3. This invention introduces biomimetic bifurcation network constraints based on Murray's law to guide the internal flow channel network module to form a physically efficient hierarchical bifurcation structure. This structure follows the physical laws of low-dissipation fluid distribution, which not only promotes the achievement of low flow resistance from the structural origin, but also achieves stable and progressively reduced flow velocity through the step-by-step bifurcation morphology. It provides another mechanism to protect the thermal stratification interface in addition to low outlet kinetic energy, and achieves comprehensive performance that cannot be achieved by existing technologies through simple geometric design. Attached Figure Description

[0036] Figure 1 This is a system architecture diagram of the present invention;

[0037] Figure 2 For the purposes of this invention Figure 1 A schematic diagram of the cross-sectional structure of the central axis;

[0038] Figure 3 This is a flowchart of the method of the present invention;

[0039] Figure 4 This is a schematic diagram of the topology optimization design domain and boundary conditions of the present invention;

[0040] Figure 5 This is a schematic diagram of the topology optimization process of the present invention.

[0041] The module consists of: 1. Water inlet interface module; 2. Water outlet interface module; and 3. Internal flow channel network module. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example:

[0044] Please see the appendix Figure 1 - Appendix Figure 5This invention provides a water distribution system for a hot water storage tank based on numerical simulation, comprising:

[0045] The integrated water distributor body includes:

[0046] Water inlet module 1 is used to receive fluid from the outside;

[0047] The water inlet interface module 1 is the fluid inlet part of the integrated water distributor body. Its function is to realize the mechanical connection and fluid communication between the integrated water distributor body and the external water supply main.

[0048] In this embodiment, the outer end face of the water inlet interface module 1 is constructed as a standard flange structure. The flange structure includes an annular sealing surface and a plurality of bolt through holes evenly distributed along the outer periphery of the sealing surface. Through this flange structure, the integrated water distributor body can be detachably and sealed to the external water supply main pipe, which also has a flange structure, by means of bolt fastening.

[0049] The inlet interface module 1 has a through-flow fluid channel inside. The cross-sectional size of the inlet end of the fluid channel matches the nominal inner diameter of the external water supply main pipe to ensure the continuity of the cross-sectional area when the fluid enters. In the direction extending from the inlet end to the internal flow channel network module 3, the inner wall of the fluid channel smoothly transitions with the inner wall of the main channel of the internal flow channel network module 3, forming a continuous internal flow channel without abrupt changes in cross-section. This smooth transition structure aims to reduce local pressure loss and flow separation caused by geometric abrupt changes when the fluid enters.

[0050] The inlet interface module 1 is not an independent component, but a single structure manufactured together with the internal flow channel network module 3 and the outlet interface module 2 through an integrated molding process. Its material is continuous and the same as other parts of the integrated water distributor body, thus ensuring the integrity and pressure resistance of the overall structure.

[0051] The water outlet interface module 2 is used to evenly distribute the fluid into the hot water storage tank;

[0052] The water outlet module 2 is the fluid outlet part of the integrated water distributor body. Its function is to discharge the fluid distributed by the internal flow channel network module 3 into the designated water layer of the hot water storage tank in the form of low kinetic energy flux.

[0053] The water outlet interface module 2 is macroscopically presented as a three-dimensional curved surface. The outer contour of this curved surface is adapted to the installation position of the integrated water distributor body in the hot water storage tank and the preset water distribution range. For example, for a cylindrical hot water storage tank, the outer contour of the water outlet interface module 2 is usually circular.

[0054] On the surface of the water outlet module 2, there is an array of multiple end outlets. Each end outlet is the termination point of an end channel in the internal flow channel network module 3. The aperture, spatial arrangement, and outlet orientation of these end outlets are not arranged in a uniform or regular geometric array.

[0055] Specifically, the precise spatial coordinates, cross-sectional area, and outflow angle of the central axis of each terminal outlet are determined by the optimization process based on the objective of minimizing the outlet kinetic energy flux. Therefore, the distribution density and aperture size of the terminal outlet vary in different regions of the outlet interface module 2 to achieve control over the total kinetic energy flux of the entire interface outlet.

[0056] The key structural feature of the outlet interface module 2 is that the sum of the cross-sectional areas of all its end outlets is greater than the cross-sectional area of ​​the inlet end of the fluid channel inside the inlet interface module 1. This increase in total cross-sectional area is the physical basis for achieving macroscopic deceleration of the fluid from the inlet to the outlet.

[0057] Similar to the inlet interface module 1, the outlet interface module 2 is also a single structure formed by seamless connection with the internal flow channel network module 3 through an integrated molding process. The transition area from each end channel to its corresponding end outlet has a smooth inner wall surface to maintain the fluid's wall-attached flow and suppress unnecessary flow loss.

[0058] Internal flow channel network module 3 is used to connect the inlet interface module and the outlet interface module;

[0059] The internal flow channel network module has a hierarchical bifurcation structure, and the overall three-dimensional structure of the internal flow channel network module is determined by an optimization process aimed at minimizing the preset performance indicators of the system under at least two different operating conditions.

[0060] The internal flow channel network module 3 is the core functional part of the integrated water distributor body. It physically fills the space between the inlet interface module 1 and the outlet interface module 2, and provides a complete distribution channel for fluid from the inlet to the outlet.

[0061] The internal flow channel network module 3 has a hierarchical branching network structure. The network starts with a main channel that is connected to the internal fluid channel of the water inlet interface module 1. After the main channel extends a certain distance in a preset direction, it undergoes the first branching, splitting into multiple first-level sub-channels. Subsequently, some or all of the first-level sub-channels will undergo a second branching, forming second-level sub-channels. This branching process can be repeated multiple times until the final terminal channels that are connected to the various terminal outlets on the water outlet interface module 2 are formed.

[0062] The geometric features of this hierarchical bifurcation network are irregular. Specifically, the number of sub-channels generated by each bifurcation, the extension length of each sub-channel, the diameter, and the bifurcation angle do not follow the preset geometric rules, but are determined autonomously by the optimization process based on the goal of global optimal performance. Therefore, the entire network presents an asymmetrical, tree-like organic form in three-dimensional space.

[0063] The flow channels of the internal flow channel network module 3 are all free-form pipes with smooth inner walls. The center line of the channel is a three-dimensional spatial curve, not a straight line. The cross-sectional shape and area of ​​the channel can also change continuously along its length. This structural form is a direct result of the numerical topology optimization algorithm solving the fluid dynamics control equations and seeking the optimal solution within a given design domain.

[0064] At each bifurcation node, the equivalent diameter of the parent pipe and the equivalent diameter of all the child pipes satisfy a specific mathematical relationship defined by the biomimetic bifurcation network constraints. A direct structural result is that at any bifurcation node, the sum of the cross-sectional areas of all the child channels is greater than the cross-sectional area of ​​the parent pipe. This structural feature runs through the entire network, resulting in the total flow cross-sectional area that the fluid passes through from the main channel to all the end channels increasing step by step. According to the fluid continuity equation, this structure ensures that the average flow velocity of the fluid decreases step by step and smoothly when it flows in the network.

[0065] The internal flow channel network module 3, as a whole, is a completely continuous single structure with the water inlet interface module 1 and the water outlet interface module 2, without any splicing or assembly interfaces.

[0066] Please see the appendix Figure 3 The water distribution method for hot water storage tanks based on numerical simulation includes the following steps:

[0067] S100. Establish a three-dimensional calculation model of the hot water storage tank, and define a preset three-dimensional space at the water inlet and outlet positions of the model. This space is defined as the design domain.

[0068] S200, Constructing the composite objective function J obj This function is used in subsequent optimization solutions to quantify and minimize the energy dissipation and outlet kinetic flux of the water distribution system under at least two different operating conditions. The composite objective function J obj The mathematical expression is:

[0069]

[0070] in:

[0071] J obj It is a composite objective function;

[0072] N is the number of operating conditions, and its value is an integer greater than or equal to 2;

[0073] i is an index representing a specific operating condition, and its value ranges from 1 to N;

[0074] w i Let be the weighting factor for the i-th operating condition;

[0075] J i Let J be the single-condition objective function under the i-th operating condition. i

[0076] It consists of a weighted sum of the energy dissipation term and the exit kinetic energy flux term.

[0077] S300 applies a biomimetic bifurcation network constraint based on Murray's law to the composite objective function. This constraint guides the internal flow channel network module 3 to form a hierarchical bifurcation structure with specific geometric characteristics during the optimization process. This constraint ensures that at any bifurcation node in the structure, the equivalent diameter of the parent pipe and the equivalent diameter of the child pipe at that node approximately satisfy the following relationship:

[0078]

[0079] in:

[0080] d p The equivalent diameter of the main pipe at the bifurcation node;

[0081] m is a preset exponent;

[0082] M is the total number of sub-pipes branching off from the bifurcation node;

[0083] j is the index representing a specific sub-pipeline, and its value ranges from 1 to M;

[0084] d c,j Let be the equivalent diameter of the j-th sub-pipe.

[0085] S400: The composite objective function and the biomimetic bifurcation network constraints are solved iteratively using a topology optimization algorithm to generate the optimal material distribution within the design domain.

[0086] The optimal material distribution ultimately determined the overall three-dimensional structure of the internal flow channel network module 3, and integrated the geometry of the inlet interface module 1 and the outlet interface module 2, thus forming a complete integrated water distributor body.

Claims

1. A water distribution system for a hot water storage tank based on numerical simulation, characterized in that, include: The integrated water distributor body includes: The water inlet module is used to receive fluid from the outside. The water outlet interface module is used to evenly distribute the fluid into the hot water storage tank; An internal flow channel network module is used to connect the water inlet interface module and the water outlet interface module; The internal flow channel network module has a hierarchical bifurcation structure, and the overall three-dimensional structure of the internal flow channel network module is determined by an optimization process aimed at minimizing the preset performance indicators of the system under at least two different operating conditions.

2. The water distribution system for a hot water storage tank based on numerical simulation according to claim 1, characterized in that, The overall three-dimensional structure of the internal flow channel network module is determined by minimizing the composite objective function J. obj And the determined composite objective function J obj The definition of is: Among them: J obj The composite objective function is defined as follows: N is the number of operating conditions, and N≥2; i is the index representing a specific operating condition, from 1 to N; w i J is the weighting factor for the i-th operating condition; i Let be the objective function for a single operating condition under the i-th operating condition.

3. The water distribution system for a hot water storage tank based on numerical simulation according to claim 2, characterized in that, The single-condition objective function J i The weighted sum of the energy dissipation term and the outlet kinetic flux term is used to characterize the flow resistance and water distribution uniformity of the system under the i-th operating condition.

4. The water distribution system for a hot water storage tank based on numerical simulation according to claim 1, characterized in that, The hierarchical branching structure of the internal flow channel network module is guided by biomimetic branching network constraints based on Murray's law during its generation process, so as to promote the distribution of fluid in a low-energy dissipation manner.

5. The water distribution system for a hot water storage tank based on numerical simulation according to claim 4, characterized in that, The biomimetic bifurcation network constraint causes the equivalent diameter of the parent pipe at any bifurcation node in the hierarchical bifurcation structure to approximately satisfy the following relationship with the equivalent diameter of the child pipe at that node: Where: d p d is the equivalent diameter of the parent pipe at the bifurcation node; m is a preset exponent; M is the total number of sub-pipes branching off from the bifurcation node; j is the index of a specific sub-pipe, from 1 to M; d c,j Let be the equivalent diameter of the j-th sub-pipe.

6. The water distribution system for a hot water storage tank based on numerical simulation according to claim 1, characterized in that, The integrated water distributor body has a three-dimensional organic form, and its surface contour is a free-form surface without standard straight lines, arcs or planar geometric features.

7. The water distribution system for a hot water storage tank based on numerical simulation according to claim 1, characterized in that, The integrated water distributor body is a component integrally formed using additive manufacturing technology.

8. The water distribution system for a hot water storage tank based on numerical simulation according to claim 1, characterized in that, The internal flow channel network module includes a main channel extending from the water inlet interface module, and multiple end channels formed by the main channel after at least one branching, extending to the water outlet interface module.

9. The water distribution system for a hot water storage tank based on numerical simulation according to claim 8, characterized in that, As the main channel flows to the multiple end channels, the total cross-sectional area of ​​the flow channel is designed to gradually increase in order to achieve a gradual decrease in flow velocity.

10. A water distribution method for hot water storage tanks based on numerical simulation, as described in any one of claims 1-9, characterized in that, Its characteristic is that it includes the following steps: A three-dimensional calculation model of the hot water storage tank is established, and a design domain is defined at the inlet and outlet positions of the model. A composite objective function is constructed, which aims to minimize the energy dissipation and outlet kinetic energy flux of the water distribution system under at least two different operating conditions. A biomimetic bifurcation network constraint based on Murray's law is applied to the composite objective function; The composite objective function and the biomimetic bifurcation network constraints are iteratively solved by a topology optimization algorithm to generate the optimal material distribution within the design domain, thereby determining the three-dimensional structure of the water distribution system.

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