A small and medium-sized thermocline heat storage tank with double-layer sectional partition and design method

Abstract

This invention relates to a small-to-medium-sized inclined thermocline thermal storage tank with double-layer segmented baffles and its design method, belonging to the field of energy storage and thermal energy utilization technology. The vertical cylindrical tank has a height-to-diameter ratio H / D of 2; it includes a hot fluid outlet located at the top of the tank and a cold fluid inlet located at the bottom of the tank, with the ratio of the diameter of the hot fluid outlet and the cold fluid inlet to the diameter of the tank bottom surface b / D being 0.1; it includes two layers of baffles with identical structures, which are fixedly installed in the tank at dimensionless heights h / H=0.25 and h / H=0.75 respectively, with a circular through hole in the center of each baffle, and the ratio of the through hole diameter to the diameter of the tank bottom surface d / D being 0.5; the thermal storage tank suppresses the mixing of hot and cold water during the heat storage / release process through the double-layer segmented baffles. This invention significantly suppresses the mixing of hot and cold water in small and medium-sized thermal storage tanks, stabilizes the temperature gradient, and improves thermal storage efficiency. It also provides a standardized baffle scheme that can be quickly switched to meet the needs of multiple scenarios, and establishes a generalized and reproducible quantitative design method based on dimensionless analysis applicable to tanks of 10~50m³.

Description

Technical Field

[0001] This invention belongs to the field of energy storage and thermal energy utilization technology, and relates to the structural optimization and design method of inclined thermocentric thermal storage device. Specifically, it is a small and medium-sized vertical inclined thermocentric thermal storage tank with double-layer segmented partition and its optimization design method, which can be applied to scenarios such as thermal and electrical decoupling of small and medium-sized cogeneration units, industrial waste heat recovery, district centralized heating and building energy supply. Background Technology

[0002] Driven by the "dual-carbon" strategic goal, my country's energy structure is accelerating its transformation towards low-carbon energy, with new energy sources such as wind and solar power becoming one of the main energy sources. The rapid expansion of new energy installed capacity is driving coal-fired power to gradually shift from baseload power to peak-shaving and flexible support power. Combined heat and power (CHP), as the core mode in the coal-fired power system that combines electricity production and heat supply, directly relates its operational flexibility to the release of coal-fired power's peak-shaving potential. However, traditional CHP units are constrained by the "heat-driven power generation" operating mode, with highly coupled electricity and heat output. During the heating season, it is difficult to reduce power generation to absorb surplus clean energy, while during the non-heating season, low heat utilization efficiency is a problem, severely limiting the operational flexibility and carbon reduction potential of the energy system. Therefore, promoting the decoupling transformation of CHP has become a key path to improve the flexibility of coal-fired power.

[0003] Existing thermoelectric decoupling technologies are mainly divided into three categories. The first category is electrothermal conversion technologies, including electrode boilers, absorption heat pumps, and solid-state electric thermal storage devices. This type of technology has an extremely fast response speed, capable of completing full-load regulation within seconds, and can quickly smooth out the fluctuations in renewable energy generation. It also has strong decoupling capabilities, enabling 100% peak load shaving for the unit. However, this type of technology is less economical. Its energy conversion efficiency is low; the electrothermal conversion efficiency of electrode boilers is approximately 95%, but considering grid transmission and distribution losses, the overall energy utilization rate is less than 85%. Operating costs are high, relying entirely on off-peak electricity prices. When off-peak electricity prices exceed 0.3 yuan / kWh, operating costs will exceed the cost of coal-fired heating. It can only achieve a one-way conversion of electrical energy to thermal energy, and cannot solve the problem of over-generation when heat load is insufficient, thus limiting its application scenarios.

[0004] The second category is unit-specific modification technologies, including low-pressure cylinder zero-output / cylinder-cut-off modification technology, high back-pressure modification technology, and bypass system modification technology. Low-pressure cylinder zero-output modification can completely cut off the steam intake to the low-pressure cylinder during the heating season, significantly reducing power generation output; however, the modification is complex, involves high investment, and is only applicable to the heating season. High back-pressure modification increases the turbine exhaust pressure for heating, offering high heating efficiency but poor peak-shaving flexibility. Bypass system modification achieves peak-shaving by directly introducing main steam or reheat steam into the condenser, but suffers from significant energy losses and is only used as an auxiliary peak-shaving method.

[0005] The third category is thermal energy storage technology. This type of technology achieves decoupling of thermoelectric output through the storage and release of thermal energy, and is currently the most widely used and best-performing thermoelectric decoupling solution in engineering applications. Its core advantages are: strong system compatibility, matching all types of cogeneration units without requiring modifications to the original unit structure; and good overall economic efficiency, with the unit volume investment for water-based sensible heat storage being only 150-250 yuan / m³. 3 The service life can reach over 20 years; the peak-shaving depth is large, enabling the unit to adjust 40%-70% of the electrical load; the energy utilization rate is high, with a comprehensive heat storage and release efficiency of over 90%. However, this type of technology also has obvious shortcomings: sensible heat storage suffers from mixing losses of hot and cold fluids, and the stability of the thermocline directly determines the system performance; latent heat storage costs 3-5 times more than sensible heat storage, and phase change materials are prone to leakage and thermal conductivity degradation; chemical heat storage technology is not mature enough, the reaction conditions are harsh, and it is currently only in the laboratory research stage, making large-scale engineering applications difficult.

[0006] Comparing the three technologies, single-tank inclined temperature layer thermal storage technology, with its comprehensive advantages such as simple structure, low cost, strong system adaptability, and reliable operation, has become the optimal solution for achieving heat and electricity decoupling in small and medium-sized combined heat and power (CHP) and district heating systems. It utilizes the physical property that the density of water decreases with increasing temperature to form a stable inclined temperature layer within the tank, achieving natural stratification of hot and cold water, thereby effectively suppressing heat mixing losses during the heat storage / release process.

[0007] As a core component in thermocline thermal storage tanks, baffles are crucial for suppressing hot and cold mixing and enhancing stratification stability. Their structural form, installation location, and opening parameters directly determine the flow field distribution and thermocline evolution within the tank. A well-designed baffle can effectively block the direct impact of the inlet jet, divide the fluid space within the tank, and suppress axial heat conduction and radial mixing, thereby significantly reducing the thermocline thickness and improving the performance of the thermal storage tank. Summary of the Invention

[0008] The purpose of this invention is to address the problems of significant boundary effects in small and medium-sized inclined thermocentric thermal storage tanks (30m³ class), severe mixing of hot and cold water due to poor adaptability of existing baffle structures, large thickness and poor stability of the inclined thermocentric layer, and low thermal storage efficiency. This invention provides a small and medium-sized inclined thermocentric thermal storage tank with a double-layer segmented baffle. Furthermore, addressing the issues of disconnect between operating parameters and structural parameters in existing thermal storage tanks, the limited variety of baffle structure options and poor engineering flexibility, and the lack of a universal and replicable quantitative design method for small and medium-sized tanks (10-50m³), this invention provides a design method for the coordinated optimization of operating parameters and baffle structure. This aims to achieve optimal global performance of the thermal storage tank and improve the convenience and economy of engineering applications.

[0009] To achieve the above objectives, the present invention provides a small to medium-sized inclined thermocline heat storage tank with a double-layer segmented baffle, comprising:

[0010] A vertical cylindrical tank with a height-to-diameter ratio (H / D) of 2; The inlet and outlet system includes a hot fluid outlet located at the top of the tank and a cold fluid inlet located at the bottom of the tank. The ratio of the diameter of the hot fluid outlet and the cold fluid inlet to the diameter of the bottom surface of the tank, b / D, is 0.1. The double-layer segmented baffle system consists of two identical baffles, which are fixedly installed at dimensionless heights h / H=0.25 and h / H=0.75 inside the tank, respectively, dividing the internal space of the tank into an upper high-temperature zone, a middle inclined temperature zone, and a lower low-temperature zone; each baffle has a circular through hole in its center, and the ratio of the through hole diameter to the tank bottom diameter d / D is 0.5; the baffles are made of heat-insulating material. The heat storage tank utilizes the physical property that the density of water decreases as the temperature rises. During the heat storage / release process, it uses a double-layered segmented baffle to suppress the mixing of hot and cold water, thereby achieving natural stratification of hot and cold water within the tank and stabilizing the temperature gradient in the central region.

[0011] Preferably, the tank has a volume of 30m³, a total height H of 4.24m, and a bottom diameter D of 2.12m.

[0012] Preferably, the diameters of both the hot fluid outlet and the cold fluid inlet are 0.212m.

[0013] Preferably, the thickness of the partition is 10mm to 20mm.

[0014] Preferably, the circular partition is a single-hole partition, with the circular through hole located at the geometric center of the partition.

[0015] Preferably, the double-layer segmented baffle system also includes a double-layer perforated baffle alternative. The double-layer perforated baffle has uniformly perforated holes with an opening rate of 40% and a single hole diameter of 13.3 mm. The installation position is the same as that of the double-layer single-hole baffle. The installation position, fixing method and support structure of the two baffle options are completely identical, and quick switching can be achieved without modifying the main structure of the tank.

[0016] The technical solution of this invention provides a design method for a small to medium-sized inclined thermocline thermal storage tank with a double-layer segmented baffle, comprising the following steps: Step 1: Determine the design inputs, including tank volume and application scenario; Step 2: Use ANSYS FLUENT to build a three-dimensional unsteady numerical model and verify the mesh independence and time step independence. Step 3: Design the tank's geometric parameters. After fixing the tank volume, select a height-to-diameter ratio (H / D) of 2. Step 4: Perform collaborative optimization of operating parameters. Determine the optimal inlet flow velocity as 0.12 m / s and the optimal temperature difference between hot and cold fluids as 40℃ through multi-condition three-dimensional unsteady-state numerical simulation. Step 5: Select and install the partition structure according to the application scenario; Step 6: Perform performance verification. Evaluate whether the thickness of the thermocline layer and the storage ratio meet the design requirements through numerical simulation or experimental testing, and output the final design scheme.

[0017] Preferably, in step 3, the height-to-diameter ratio H / D=2 is verified through multi-condition numerical simulation, which can achieve a dynamic balance between radial mixing loss and axial heat conduction loss under fixed volume conditions, thereby achieving the optimal value for the thickness of the inclined temperature layer.

[0018] Preferably, in step 5, the selection of the partition structure includes: Efficiency-first scenario: Use a double-layer single-hole partition with a hole diameter ratio d / D of 0.5, and install it at dimensionless heights h / H=0.25 and 0.75; For scenarios prioritizing flow field uniformity: a double-layer porous baffle is used with an opening rate of 40% and a single hole diameter of 13.3 mm. The installation position is the same as that of the double-layer single-hole baffle.

[0019] Preferably, in step 6, the target of performance verification is to keep the thickness of the inclined temperature layer stable within the range of 0.28m ± 0.02m.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects: 1. Optimize the heat storage performance of small and medium-sized thermal storage tanks using baffles. This invention is for 30m 3 The core feature of this type of small-to-medium-sized thermal storage tank is its significant boundary effect. It employs a symmetrical, dual-section, single-hole baffle arrangement, with two layers of baffles installed at dimensionless heights h / H=0.25 and h / H=0.75 respectively. This forms a three-section spatial structure: an upper high-temperature zone, a middle inclined temperature layer, and a lower low-temperature zone, effectively solving the problem of severe mixing of hot and cold water in small-to-medium-sized tanks. Compared to existing technologies, the influence range of the inlet jet is significantly reduced, effectively blocking the direct impact of cold water at the bottom and hot water at the top. The thickness of the inclined temperature layer remains stable at 0.28m ± 0.02m throughout the entire heat release cycle. The average thickness of the inclined temperature layer is reduced by 16.5% compared to the no-baffle condition and by 5.1% compared to the single-layer, single-hole baffle, achieving a significant improvement in the heat storage performance of small-to-medium-sized thermal storage tanks.

[0021] 2. Determine operating parameters and partition structure to achieve globally optimal performance. Existing technologies generally suffer from a disconnect between parameters and structure, failing to achieve global optimization. This invention establishes a quantitative matching relationship between inlet flow velocity (vin), hot and cold fluid temperature difference (ΔT), and baffle parameters (installation position, aperture ratio) through 12 sets of three-dimensional unsteady-state numerical simulations under different operating conditions, achieving deep synergistic optimization of operating parameters and baffle structure. For the double-layer single-hole baffle structure, the optimal inlet flow velocity is determined to be 0.12 m / s, at which the inertial force of the inlet jet and the buoyancy force of the cold fluid reach dynamic equilibrium, and the thickness of the inclined temperature layer is minimized. The optimal hot and cold fluid temperature difference is determined to be 40℃, which ensures sufficient energy storage density while avoiding local flow field turbulence caused by excessive density difference, resulting in the highest energy storage ratio. The optimal baffle parameters are determined to be a double-layer baffle installation position with h / H = 0.25 and 0.75, and an aperture ratio with d / D = 0.5, at which the baffle constraint effect is optimal and the fluid resistance is minimized.

[0022] 3. Standardized selection solutions for multiple scenarios, allowing for quick switching without modifying the tank. This invention provides two standardized solutions: a double-layer single-hole baffle and a double-layer multi-hole baffle. The installation position, fixing method, and support structure of the two solutions are completely identical, requiring no modification to the main tank structure. The double-layer single-hole baffle is suitable for scenarios where minimizing the thickness of the inclined temperature layer and maximizing heat storage efficiency are primary goals, such as thermoelectric decoupling in small and medium-sized cogeneration units and industrial waste heat recovery. Its characteristics include low heat loss and high heat storage efficiency. The double-layer multi-hole baffle is suitable for scenarios requiring high uniformity of the flow field within the tank, such as commercial building heating and domestic hot water supply. Its parameters are an opening ratio of 40% and a single hole diameter of 13.3 mm, which can improve the uniformity of fluid velocity distribution within the tank by 25% and avoid local dead zones.

[0023] 4. Quantitative and replicable design methods The optimization design criteria of this invention are derived based on dimensionless analysis methods, and possess strong universality and reproducibility. (Due to 10-50m) 3 The surface area to volume ratio of a vertical cylindrical water-medium inclined thermostatic precipitator is 0.8-1.5 m². -1 , compared with the 30m studied in this invention 3 Can (approximately 1.1m) -1 The flow and heat transfer laws dominated by boundary effects are highly similar and are on the same order of magnitude. The obtained baffle parameters and operating parameters can be directly scaled, making them convenient for engineering applications. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the basic tank structure of the physical model of the inclined thermosphere thermal storage tank in the present invention, which is a small-to-medium-sized inclined thermosphere thermal storage tank with double-layer segmented baffles and design method. Figure 2This is a schematic diagram of the single-layer, single-hole partition structure of the physical model of the inclined thermosphere thermal storage tank in the present invention, which is a small-to-medium-sized inclined thermosphere thermal storage tank with double-layer segmented partitions and its design method. Figure 3 This is a schematic diagram of the double-layer single-hole partition structure of the physical model of the inclined thermosphere thermal storage tank in the present invention, which is a small-to-medium-sized inclined thermosphere thermal storage tank with double-layer segmented partition and design method. Figure 4 This is a schematic diagram of the double-layer porous partition structure of the physical model of the inclined thermosphere thermal storage tank in the present invention, which is a small-to-medium-sized inclined thermosphere thermal storage tank with double-layer segmented partition and design method. Figure 5 This is a schematic diagram of the porous partition structure of the physical model of the inclined thermosphere thermal storage tank with double-layer segmented partitions in the present invention. Figure 6 This is a flowchart illustrating the design method of a small-to-medium-sized inclined thermocline heat storage tank with double-layer segmented partitions according to the present invention. Detailed Implementation

[0025] 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.

[0026] This invention discloses a small-to-medium-sized inclined-temperature layer thermal storage tank with a double-layer segmented baffle and its optimized design method. The thermal storage tank adopts a vertical cylindrical structure with a volume of 30m³. 3 Through the coordinated design and optimization of tank geometry parameters, inlet and outlet systems, double-layer segmented baffle systems, and operating parameters, the mixing of hot and cold water inside the tank is effectively suppressed, the thickness of the inclined temperature layer is reduced, and the heat storage efficiency and storage ratio are improved. It can be widely used in scenarios such as heat and power decoupling of small and medium-sized cogeneration units, industrial waste heat recovery, district centralized heating, and building energy supply.

[0027] The main body of the tank adopts a vertical cylindrical design with a height-to-diameter ratio (H / D) of 2, corresponding to a total tank height (H) of 4.24m and a bottom diameter (D) of 2.12m. This height-to-diameter ratio has been verified through numerical simulation, enabling a dynamic balance between radial mixing losses and axial heat conduction losses under fixed volume conditions. This results in an optimal thickness of the thermocline layer, providing a basic geometric framework for small and medium-sized thermal storage tanks that balances structural compactness with thermal stratification stability.

[0028] A hot fluid outlet is located at the top of the tank, and a cold fluid inlet is located at the bottom. Both inlet and outlet diameters are 0.212 m, with an inlet / outlet diameter ratio (b / D) of 0.1. This design, based on fluid dynamics analysis, effectively reduces the disturbance of the inlet jet to the flow field within the tank, preventing severe mixing of hot and cold water in the inlet and outlet areas and providing boundary conditions for the stable formation of the thermocline. Two identical circular single-hole baffles are fixedly installed inside the tank, located at dimensionless heights h / H of 0.25 and h / H of 0.75, respectively. Each baffle has a circular through-hole at its center, with a diameter ratio (d / D) of 0.5. The baffles are made of insulating material with a thickness of 10 to 20 mm and are fixed to the support brackets on the inner wall of the tank by welding or bolting.

[0029] The core function of this double-layer single-hole baffle system is to divide the internal space of the tank into three independent spaces: an upper high-temperature zone, a middle inclined temperature zone, and a lower low-temperature zone, forming a three-section constraint structure. The upper and lower baffles are symmetrically arranged and work together: when cold water enters from the bottom inlet, it first flows upward through the central through-hole of the lower baffle. The lower baffle blocks the radial diffusion of cold water to the surrounding areas, causing the cold water to rise only in the central region, avoiding direct mixing with the surrounding hot water; when hot water enters from the top, the upper baffle plays the same constraining role, preventing the hot water from directly impacting the lower low-temperature zone. The combined effect of the two baffles keeps the inclined temperature zone stable in the central region, with its thickness controllable within the range of 0.28m ± 0.02m, effectively suppressing axial heat conduction and radial mixing.

[0030] When the application scenario requires high uniformity of the flow field within the tank, the double-layer single-hole baffle can be replaced with a double-layer multi-hole baffle. The multi-hole baffle adopts a uniform perforation structure with an opening ratio of 40% and a single hole diameter of 13.3mm. Its installation position is exactly the same as the double-layer single-hole baffle, located at dimensionless heights h / H of 0.25 and h / H of 0.75. This structure disperses the fluid into multiple fine streams through densely and uniformly distributed small holes, improving the uniformity of fluid velocity distribution within the tank by 25%, effectively avoiding local dead zones. It is suitable for scenarios with high requirements for flow field uniformity, such as commercial building heating and domestic hot water supply. The installation position, fixing method, and support structure of the two baffle solutions are completely identical, allowing for rapid switching without modifying the main tank structure, significantly improving the engineering flexibility and adaptability of the device to multiple scenarios.

[0031] The height-to-diameter ratio design of the tank body, the proportional control of the inlet and outlet systems, and the segmented constraint of the baffle system work together to form the thermal stratification protection system of the thermal storage tank. The tank height-to-diameter ratio H / D of 2 provides a basic geometric environment for suppressing radial mixing and balancing axial heat conduction losses; the inlet / outlet diameter ratio b / D of 0.1 weakens the disturbance intensity of the inlet jet at the boundary; and the double-layer baffles form a physical barrier inside the tank, redistributing and guiding the fluid that has entered the tank. Throughout the entire thermal storage and release cycle, the insulating properties of the baffles reduce axial heat conduction through solid components, while the perforated structure of the baffles balances local flow velocities through a throttling effect. These three elements work together to enable stable natural stratification of the hot and cold water inside the tank based on density differences.

[0032] The heat storage tank of this invention utilizes the physical property that the density of water decreases with increasing temperature to achieve natural stratification of hot and cold water. During heat storage, high-temperature hot water enters the tank from the top hot fluid outlet, while low-temperature cold water flows out from the bottom cold fluid inlet. During heat release, low-temperature cold water enters the tank from the bottom cold fluid inlet, while high-temperature hot water flows out from the top hot fluid outlet. A double-layered, single-hole baffle divides the tank into three independent spaces: an upper high-temperature zone, a middle inclined temperature layer zone, and a lower low-temperature zone. This effectively blocks the direct impact of the inlet jet and suppresses axial heat conduction and radial mixing. When cold water enters from the bottom, it first flows upward through the central through-hole of the lower baffle. The baffle prevents the cold water from radially diffusing outwards, causing it to rise only in the central region and avoiding direct mixing with the surrounding hot water. When hot water enters from the top, the upper baffle serves the same purpose. The two baffles work together to keep the inclined temperature layer in the central region, with a stable thickness within the range of 0.28m ± 0.02m.

[0033] This invention proposes a set of methods applicable to 10 to 50 m based on dimensionless analysis and three-dimensional unsteady-state numerical simulation. 3 A quantitative optimization design method for vertical cylindrical hydrothermal strata tanks is proposed. This method first determines the design inputs, including the tank volume and application scenario. Then, ANSYS FLUENT is used to build the model, and mesh independence and time step independence are verified to ensure the reliability of the numerical simulation results.

[0034] The design method in this invention includes the following steps: 1. Tank geometry design: After fixing the tank volume, the height-to-diameter ratio H / D is selected as 2. This value is verified through multi-condition simulation, which can achieve a dynamic balance between radial mixing loss and axial heat conduction loss, and minimize the average slope temperature layer thickness.

[0035] 2. Operational Parameter Optimization: Through 12 sets of three-dimensional unsteady-state numerical simulations under different operating conditions, a quantitative matching relationship between inlet flow velocity, temperature difference between hot and cold fluids, and baffle parameters was established. The optimal inlet flow velocity was determined to be 0.12 m / s, at which point the inertial force of the inlet jet and the buoyancy force of the cold fluid reach dynamic equilibrium, and the thickness of the inclined thermocline layer is minimized. The optimal temperature difference between hot and cold fluids was determined to be 40 degrees Celsius. This temperature difference can ensure sufficient energy storage density while avoiding local flow field turbulence caused by excessive density difference, thus maximizing the energy storage ratio.

[0036] 3. Baffle Structure Selection and Installation: The baffle structure selection and installation are based on the application scenario. When minimizing the thickness of the inclined temperature layer and maximizing heat storage efficiency are the primary objectives, such as in efficiency-priority scenarios like heat and power decoupling in small and medium-sized cogeneration units and industrial waste heat recovery, a double-layer single-hole baffle with a pore size ratio d / D of 0.5 is used, installed at dimensionless heights h / H of 0.25 and 0.75. When high uniformity of the flow field within the tank is required and a certain amount of flow loss is acceptable, such as in scenarios prioritizing flow field uniformity like commercial building heating and domestic hot water supply, a double-layer multi-hole baffle with an opening rate of 40% and a single pore diameter of 13.3mm is used, installed in the same position as the double-layer single-hole baffle.

[0037] 4. After the selection is completed, the performance is verified. The thickness of the thermocline and the storage ratio are evaluated through numerical simulation or experimental testing to determine whether they meet the design requirements. Finally, the verified optimal design scheme is output.

[0038] The present invention will be further illustrated by the following examples, but these examples do not limit the scope of the invention.

[0039] Example 1: This embodiment selects 30m 3 A simulation verification was conducted on a vertical inclined thermostatic precipitator tank without a diaphragm foundation. In this embodiment, the tank's geometric parameters were set to a volume of 30 m³. 3 The tank has a height-to-diameter ratio (H / D) of 2, a height of 4.24 m, a bottom diameter of 2.12 m, and an inlet / outlet diameter ratio (b / D) of 0.1. Operating parameters are set as follows: inlet velocity 0.12 m / s, cold fluid inlet temperature 20°C, hot fluid initial temperature 60°C, and a temperature difference of 40°C between the cold and hot fluids. Numerical simulation is performed using a three-dimensional unsteady-state numerical model established based on ANSYS FLUENT. The RNG k-ε turbulence model, SIMPLE pressure-velocity coupling algorithm, and second-order upwind discrete control equations are employed. The iterative convergence residual is 1 × 10⁻⁶. -3 The time step is 3 seconds, and the total simulation time is 7500 seconds.

[0040] During the simulated heat release process, the tank was initially filled with 60°C hot water, while 20°C cold water flowed in from the bottom inlet at a velocity of 0.12 m / s. The hot water flowed out from the top outlet. The temperature field distribution and the change in the thermocline thickness within the tank were monitored throughout the process. After the simulation, the axial temperature distribution data within the tank were extracted, and the average thermocline thickness was calculated to be 0.34 m. The test results showed that a significant hot and cold water mixing zone existed within the tank during the heat release process, and the inlet jet directly impacted the upper hot water zone, resulting in an irregular thermocline morphology. This embodiment demonstrates that under the condition of no baffles, a 30m... 3 The hot and cold water in the thermocline storage tank are severely mixed, the thermocline is unstable, and the heat storage efficiency is low, which cannot meet the high-efficiency operation requirements of thermoelectric decoupling for small and medium-sized cogeneration units.

[0041] Example 2: This embodiment selects 30m 3 The operation of a vertical inclined thermocline thermal storage tank with a single-layer, single-hole baffle was simulated and verified. The operation process was consistent with that of Example 1, with only the internal structure of the tank being adjusted. The tank geometry parameters were the same as in Example 1. The baffle structure was set to install a single-layer circular single-hole baffle at a dimensionless height h / H of 0.5 inside the tank, with a hole diameter ratio d / D of 0.5. The baffle was made of insulating material with a thickness of 15 mm. The operating parameters and numerical simulation settings were completely consistent with those of Example 1, and the total simulation time was 7500 s.

[0042] The simulated heat release process was the same as in Example 1, with the temperature field distribution and thermocline thickness changes within the tank monitored throughout. After the simulation, the axial temperature distribution data within the tank was extracted, and the average thermocline thickness was calculated to be 0.25 m. The test results showed that the baffle effectively separated the hot and cold water regions, suppressed the direct impact of the inlet jet, and resulted in a more regular thermocline morphology. This example demonstrates that a single-layer, single-hole baffle can significantly improve the 30 m... 3 The performance of the inclined temperature layer heat storage tank is improved. The average thickness of the inclined temperature layer is reduced by 12% compared with the case without baffles, but there is still room for further optimization.

[0043] Example 3: This embodiment selects 30m 3 The vertical inclined thermocline thermal storage tank was simulated and verified under the condition of double-layer single-hole baffles. The operation process was consistent with that of Example 1, with adjustments made to the internal structure of the tank. The tank geometry parameters were the same as in Example 1. The baffle structure was set up with a circular single-hole baffle installed at dimensionless heights h / H of 0.25 and h / H of 0.75 inside the tank. The two baffles were identical in specifications, with a hole diameter ratio d / D of 0.5. The baffles were made of insulating material with a thickness of 15 mm. The operating parameters and numerical simulation settings were completely consistent with those of Example 1, with a total simulation time of 7500 s.

[0044] The simulated heat release process was the same as in Example 1, with the temperature field distribution and thermocline thickness changes within the tank monitored throughout. After the simulation, the axial temperature distribution data within the tank was extracted, and the average thermocline thickness was calculated to be 0.28 m. The test results showed that the two baffles formed a three-segment spatial structure, significantly enhancing the segmented constraint effect on the fluid within the tank, and the thermocline showed almost no stretching or disturbance. This example demonstrates that the double-layer single-hole baffle structure can further improve the thickness by 30 m. 3 The performance of the inclined temperature layer heat storage tank is improved. The average thickness of the inclined temperature layer is reduced by 16.5% compared with the case without baffles, and further reduced by 5.1% compared with the case with a single layer and a single hole baffle, thus achieving the optimal balance between the stability of the inclined temperature layer and the heat storage efficiency.

[0045] Through simulation verification of the above three implementation methods, the following conclusions can be drawn: The double-layer single-hole partition structure proposed in this invention can effectively suppress 30m 3 The mixing of hot and cold water in small and medium-sized inclined thermocline thermal storage tanks significantly reduces the thickness of the thermocline, increases the storage ratio, and achieves a leapfrog improvement in thermal storage performance compared to traditional structures. The synergistic optimization of operating parameters and baffle structure is key to achieving optimal performance of the thermal storage tank. Under the optimal combination of operating parameters—an inlet flow velocity of 0.12 m / s, a temperature difference between hot and cold fluids of 40 degrees Celsius, and a height-to-diameter ratio of 2—the double-layer single-hole baffle provides the best constraint effect. Furthermore, due to the 10 to 50 m... 3 The surface area to volume ratio of a vertical cylindrical water-medium inclined thermostatic precipitator is 0.8-1.5 m². -1 , compared with the 30m studied in this invention 3 The tank is approximately 1.1m in size. -1 The flow heat transfer laws dominated by boundary effects, which are of the same order of magnitude, are highly similar. Therefore, the optimization design criteria derived from the dimensionless analysis method have strong universality and reproducibility. The obtained baffle parameters and operating parameters can be directly scaled and applied to similar tanks, making engineering applications convenient and with broad prospects for promotion.

[0046] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A medium-sized inclined thermocline heat storage tank with double-layer segmented baffles, characterized in that, include: A vertical cylindrical tank with a height-to-diameter ratio (H / D) of 2; The inlet and outlet system includes a hot fluid outlet located at the top of the tank and a cold fluid inlet located at the bottom of the tank. The ratio of the diameter of the hot fluid outlet and the cold fluid inlet to the diameter of the bottom surface of the tank, b / D, is 0.

1. The double-layer segmented baffle system consists of two identical baffles, which are fixedly installed at dimensionless heights h / H=0.25 and h / H=0.75 inside the tank, respectively, dividing the internal space of the tank into an upper high-temperature zone, a middle inclined temperature zone, and a lower low-temperature zone; each baffle has a circular through hole in its center, and the ratio of the through hole diameter to the tank bottom diameter d / D is 0.5; the baffles are made of heat-insulating material. The heat storage tank utilizes the physical property that the density of water decreases as the temperature rises. During the heat storage / release process, it uses a double-layered segmented baffle to suppress the mixing of hot and cold water, thereby achieving natural stratification of hot and cold water within the tank and stabilizing the temperature gradient in the central region.

2. A small to medium-sized inclined thermocline heat storage tank with double-layer segmented baffles according to claim 1, characterized in that, The tank has a volume of 30m³, a total height H of 4.24m, and a bottom diameter D of 2.12m.

3. A small to medium-sized inclined thermocline heat storage tank with double-layer segmented baffles according to claim 1, characterized in that, The diameters of both the hot fluid outlet and the cold fluid inlet are 0.212m.

4. A small to medium-sized inclined thermocline heat storage tank with double-layer segmented baffles according to claim 1, characterized in that, The thickness of the partition is 10mm to 20mm.

5. A small to medium-sized inclined thermocline heat storage tank with double-layer segmented baffles according to claim 1, characterized in that, The circular partition is a single-hole partition, with the circular through hole located at the geometric center of the partition.

6. A small to medium-sized inclined thermocline heat storage tank with double-layer segmented baffles according to claim 1, characterized in that, The double-layer segmented baffle system also includes a double-layer perforated baffle alternative. The double-layer perforated baffle has uniformly perforated holes with an opening rate of 40% and a single hole diameter of 13.3 mm. The installation position is the same as that of the double-layer single-hole baffle. The installation position, fixing method and support structure of the two baffle options are completely identical, and a quick switch can be achieved without modifying the main structure of the tank.

7. A design method for a small to medium-sized inclined thermocline thermal storage tank with a double-layer segmented baffle according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Determine the design inputs, including tank volume and application scenario; Step 2: Use ANSYSFLUENT to build a three-dimensional unsteady numerical model and verify the mesh independence and time step independence. Step 3: Design the tank's geometric parameters. After fixing the tank volume, select a height-to-diameter ratio (H / D) of 2. Step 4: Perform collaborative optimization of operating parameters. Determine the optimal inlet flow velocity as 0.12 m / s and the optimal temperature difference between hot and cold fluids as 40℃ through multi-condition three-dimensional unsteady-state numerical simulation. Step 5: Select and install the partition structure according to the application scenario; Step 6: Perform performance verification. Evaluate whether the thickness of the thermocline layer and the storage ratio meet the design requirements through numerical simulation or experimental testing, and output the final design scheme.

8. The design method of a small-to-medium-sized inclined thermocline heat storage tank with double-layer segmented baffles according to claim 7, characterized in that, In step 3, the height-to-diameter ratio H / D=2 was verified through multi-condition numerical simulation, which showed that under fixed volume conditions, the radial mixing loss and axial heat conduction loss could be dynamically balanced, thereby achieving the optimal value for the thickness of the inclined temperature layer.

9. The design method of a small-to-medium-sized inclined thermocline heat storage tank with double-layer segmented baffles according to claim 8, characterized in that, Step 5, the selection of the partition structure includes: Efficiency-first scenario: Use a double-layer single-hole partition with a hole diameter ratio d / D of 0.5, and install it at dimensionless heights h / H=0.25 and 0.75; For scenarios prioritizing flow field uniformity: a double-layer porous baffle is used with an opening rate of 40% and a single hole diameter of 13.3 mm. The installation position is the same as that of the double-layer single-hole baffle.

10. The design method of a small-to-medium-sized inclined thermocline heat storage tank with double-layer segmented baffles according to claim 9, characterized in that, In step 6, the goal of performance verification is to keep the thickness of the thermocline layer stable within the range of 0.28m ± 0.02m.

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