Packed bed type phase change heat storage heating simulation system, simulation method and heat storage unit

Abstract

The invention relates to the technical field of heat energy storage and heating, and provides a packed bed type phase change heat storage and heating simulation system, a simulation method and a heat storage unit.The method comprises the steps that a seasonal heat storage and heating system dynamic simulation platform is constructed through TRNSYS, component parameters and the energy flow relation are defined, and the dynamic performance and the real-time simulation result of a heat storage and heating system are obtained; a filling type phase change heat storage unit is adopted, temperature distribution, change trend and phase change process in the heat storage unit are simulated in TRNSYS, and simulation data of the filling type phase change heat storage unit are obtained; the simulation data are imported into multi-physics field simulation software COMSOL by controlling the time step length to be consistent, a multi-physics field coupling simulation model is established, and a coupling simulation result is obtained; and based on a coupling simulation result, heat storage unit design parameters and a control strategy are optimized and output. The method is free from limitation of modular system simulation, and flexibility and precision of modular simulation are further improved. According to the method, the advantages of two simulation tools are utilized, so that the modeling of the energy system configuration is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal energy storage and heating, and in particular to a packed bed phase change thermal storage and heating simulation system, a simulation method and a heat storage unit. Background Art

[0002] With the rapid growth of renewable energy utilization, energy storage technologies have also developed rapidly. Seasonal thermal storage, in particular, effectively alleviates the seasonal imbalance between solar energy supply and demand by storing excess summer solar energy and releasing it across the winter, significantly improving the overall utilization efficiency of solar energy systems.

[0003] Numerous scholars have conducted in-depth research on seasonal heat storage methods from various perspectives. Zhang et al. used hydraulic fracturing technology to transform reservoirs, injecting fracturing fluid containing thermal insulation materials into the upper and lower strata of the target aquifer, and constructed a large-capacity, low-heat-loss, above-ground, trans-seasonal heat storage system. Hanne et al. injected hot water up to 150°C into a Danish mine to construct an underground high-temperature heat storage layer, achieving large-scale seasonal heat storage. This type of aquifer-based heat storage solution is mainly aimed at community-level applications. Due to the large space requirements and high initial investment, it is difficult to promote it to distributed single buildings.

[0004] Furthermore, seasonal heat storage using tanks is a common solution for small residential buildings. Research has shown that combining short-term and long-term water tanks can significantly improve the overall energy efficiency of thermal storage systems. Currently, these thermal storage systems often use water due to its high specific heat capacity, but this typically requires higher temperatures or larger spaces, resulting in significant heat loss and reduced energy efficiency.

[0005] With the rapid development of phase-change thermal storage materials, their high energy density, constant-temperature heat release characteristics, and high energy efficiency have shown great potential in the field of seasonal heat storage. Therefore, applying phase-change materials to seasonal heat storage systems for small homes is expected to further optimize volume control and system efficiency. Consequently, a growing number of researchers are investigating the application of phase-change thermal storage in small homes. However, this research has only explored its feasibility theoretically and lacks numerical simulations or experimental verification to evaluate its practical application value.

[0006] Although phase change materials (PCMs) hold great potential for interseasonal heat storage applications, their main drawback is their generally poor thermal conductivity. To overcome this shortcoming, numerous researchers have conducted research on material modification and structural optimization. However, these methods for improving system heat transfer performance through optimization are complex and often lack structural stability. Packed bed latent heat storage is a relatively simple method for improving heat transfer efficiency. Its simple design, impressive energy storage capacity, and low failure rate have led to its widespread adoption in latent heat storage systems.

[0007] Therefore, how to use packed bed phase change heat storage tanks to replace the seasonal water tanks in traditional seasonal heat storage systems, simulate the dynamic operation of residential heating systems throughout the year, derive optimization solutions to improve solar energy security and system stability, and improve the flexibility and accuracy of simulations has become a technical problem that needs to be solved urgently. Summary of the Invention

[0008] In view of this, the main purpose of the present invention is to provide a packed bed phase change thermal storage heating simulation system, simulation method and heat storage unit, aiming to improve the flexibility and accuracy of simulation based on packed bed phase change thermal storage heating system.

[0009] To achieve the above objectives, in a first aspect, the present invention provides a phase change heat storage unit for a filled heat storage heating simulation system, comprising: a solar collector for collecting solar energy and converting it into thermal energy; a packed bed phase change heat storage tank, formed by filling capsules encapsulating phase change material, with a water layer provided at the bottom of the phase change heat storage tank, and the top of the phase change heat storage tank connected to a buffer water tank via a pipe; a temperature-controlled diverter valve for adjusting flow distribution according to the temperature of the heat storage tank outlet and the buffer water tank outlet; and an air source heat pump for supplementary heating when the return water temperature is lower than a set threshold.

[0010] Preferably, the phase change material is sodium acetate trihydrate, the phase change temperature of the phase change material is 58-61° C., and the latent heat storage density of the phase change material is 264 kJ / kg.

[0011] Preferably, the return water temperature threshold range of the air source heat pump is 30-35°C.

[0012] In a second aspect, the present invention provides a simulation method for a packed bed phase change thermal storage heating system, comprising the following steps:

[0013] S1, build a dynamic simulation platform for seasonal thermal storage heating system through the transient system simulation model TRNSYS, define system component parameters and energy flow relationships, and obtain the dynamic performance and real-time simulation results of the thermal storage heating system;

[0014] S2, using the phase change thermal storage unit for the packed-bed thermal storage heating simulation system disclosed in the first aspect above, simulating the temperature distribution, change trend, and phase change process in the packed-bed phase change thermal storage unit in TRNSYS, and obtaining simulation data of the packed-bed thermal storage unit;

[0015] S3, by controlling the time step to be consistent, the simulation data of the packed bed phase change thermal storage unit is imported into the multi-physics simulation software COMSOL, a coupled simulation model of the coupled transient system simulation model and the multi-physics simulation model is established, and the coupled simulation results are obtained;

[0016] S4, based on the coupled simulation results, optimize and output the design parameters and control strategy of the thermal storage unit.

[0017] Preferably, the simulation model of the multi-physics simulation software COMSOL includes multi-physics local thermal non-equilibrium simulation and non-isothermal flow simulation, wherein the simulation process includes heat conduction, heat convection and non-isothermal flow in porous media.

[0018] In a third aspect, the present invention provides a packed bed phase change thermal storage heating simulation system, comprising:

[0019] The dynamic simulation module of the seasonal thermal storage heating system is used to build a dynamic simulation platform for the seasonal thermal storage heating system through the transient system simulation model TRNSYS, define system component parameters and energy flow relationships, and obtain the dynamic performance and real-time simulation results of the thermal storage heating system;

[0020] A filled phase-change heat storage module, comprising the phase-change heat storage unit for the filled heat storage heating simulation system disclosed in the first aspect above, for collecting temperature distribution, change trend, and phase change process within the filled phase-change heat storage unit to obtain simulation data of the heat storage unit;

[0021] The multi-physics coupling simulation module is used to import the simulation data of the packed bed phase change thermal storage unit into the multi-physics simulation software COMSOL by controlling the time step to be consistent, establish a coupled simulation model of the coupled transient system simulation model and the multi-physics simulation model, and obtain coupled simulation results;

[0022] The strategy optimization and output module is used to optimize and output the design parameters and control strategies of the thermal storage unit based on the coupled simulation results.

[0023] In the technical solution provided by the present invention, a packed bed phase change heat storage tank is used to replace the seasonal water tank in the traditional seasonal heat storage system. A single-family house is used as the research object to simulate the dynamic operation of its heating system throughout the year. Based on the simulation results, the temperature change trend, heat loss, operation after connecting to the auxiliary heat pump and system energy consumption of the phase change heat storage tank and the traditional water tank system in different time periods of the heating season are compared. From the perspective of cost optimization, an optimization solution to improve the solar energy guarantee rate and system stability is proposed. The present invention uses the transient system simulation model TRNSYS to build a complete system model. In order to accurately understand the temperature distribution and change trend inside the seasonal heat storage tank over a long span, the simulation process of the seasonal heat storage tank is innovatively introduced into the multi-physics simulation software COMSOL. This method breaks away from the limitations of modular system simulation, effectively solves the limitations of traditional modular simulation, makes up for the lack of common components, and further improves the flexibility and accuracy of modular simulation. This method takes advantage of the advantages of the two simulation tools to make the modeling of energy system configuration more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] One or more embodiments are exemplarily illustrated by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0025] Figure 1 A schematic flow chart of a packed bed phase change thermal storage heating simulation system disclosed in one or more embodiments of the present application;

[0026] Figure 2 This is a schematic structural diagram of a phase change heat storage unit disclosed in one or more embodiments of the present application.

[0027] Figure 3 A schematic diagram of energy flow in a packed bed phase change thermal storage heating simulation system disclosed in one or more embodiments of the present application;

[0028] FIG4( a ) is a schematic diagram comparing simulation results of the simulation system disclosed in one or more embodiments of the present application with experimental data of latent heat packed beds in the literature;

[0029] FIG4( b ) is a schematic diagram comparing simulation results of the simulation system disclosed in one or more embodiments of the present application with the results of the simulated seasonal water tank average temperature variation throughout the year in the literature;

[0030] Figure 5 A schematic diagram of the annual meteorological data of Baoding City, China disclosed in one or more embodiments of the present application;

[0031] Figure 6 A schematic diagram of a heating model of a packed bed phase change thermal storage heating simulation system disclosed in one or more embodiments of the present application;

[0032] Figure 7 A schematic diagram of the building load, phase change tank inlet temperature, and flow rate disclosed in one or more embodiments of the present application;

[0033] Figure 8 A schematic diagram of temperature changes and heat storage capacity data of a phase change material water storage tank in a non-heating season disclosed in one or more embodiments of the present application;

[0034] Figure 9 A schematic diagram illustrating changes in the outlet temperature and average temperature of a seasonal hot water storage tank before the air source heat pump is activated during the heating season according to one or more embodiments of the present application;

[0035] Figure 10 A schematic diagram of temperature changes in a system at the beginning of a heating season according to one or more embodiments of the present application;

[0036] FIG11( a ) is a schematic diagram of temperature variation parameters of a system around December 6, disclosed in one or more embodiments of the present application;

[0037] FIG11( b ) is a schematic diagram of the internal temperature distribution of the phase change material hot water storage tank of the system around December 6, disclosed in one or more embodiments of the present application;

[0038] FIG12( a ) is a schematic diagram illustrating changes in system-related temperatures at the end of December, as disclosed in one or more embodiments of the present application;

[0039] FIG12( b ) is a schematic diagram of the internal temperature distribution of the phase change material water storage tank of the system at the end of December according to one or more embodiments of the present application;

[0040] FIG13( a ) is a schematic diagram illustrating changes in system-related temperatures in mid-January according to one or more embodiments of the present application;

[0041] FIG13( b ) is a schematic diagram of the internal temperature distribution of the phase change material hot water storage tank of the system in mid-January according to one or more embodiments of the present application;

[0042] Figure 14 A schematic diagram of the cumulative effective heat supply of the phase change material water storage tank disclosed in one or more embodiments of the present application during the entire heating season;

[0043] Figure 15 A schematic diagram illustrating the heat loss and total amount of the phase change heat storage tank and water tank disclosed in one or more embodiments of the present application during the heating season;

[0044] Figure 16 A schematic diagram of the return water temperature change of the phase change heat storage tank and water tank system during the heating season and the start and stop of the air source heat pump disclosed in one or more embodiments of the present application;

[0045] FIG17( a ) is a schematic diagram of energy distribution and system performance coefficient of a phase change thermal storage tank system disclosed in one or more embodiments of the present application during the heating season;

[0046] FIG17( b ) is a schematic diagram of energy distribution and system performance coefficient of the water tank system disclosed in one or more embodiments of the present application during the heating season;

[0047] Figure 18 A schematic diagram illustrating comparison results of various aspects of the PCM storage tank system and the water tank system disclosed in one or more embodiments of the present application;

[0048] FIG19( a ) is a schematic diagram showing a comparison of the outlet temperature of a seasonal heat storage tank during the heating season after adjusting solar collector parameters according to one or more embodiments of the present application without using an air source heat pump;

[0049] FIG19( b ) is a schematic diagram illustrating outlet temperature variations at different storage tank heights according to one or more embodiments of the present application;

[0050] Figure 20 A schematic diagram of the life cycle cost changes disclosed in one or more embodiments of the present application;

[0051] Figure 21 This is a flow chart of a simulation method for a packed bed phase change thermal storage heating system disclosed in one or more embodiments of the present application. DETAILED DESCRIPTION

[0052] To facilitate understanding of the present invention, the present invention is described in more detail below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly attached to the other element, or one or more elements can be interposed therebetween. When an element is described as being "connected to" another element, it can be directly connected to the other element, or one or more elements can be interposed therebetween. The terms "vertical," "horizontal," "left," "right," "inner," "outer," and similar expressions used in this specification are for illustrative purposes only. In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating relative importance or implicitly specifying the number of technical features indicated. Therefore, unless otherwise specified, features specified as "first" or "second" may explicitly or implicitly include one or more of such features; "plurality" means two or more. The term "comprising" and any variations thereof are intended to be non-exclusive, and one or more other features, integers, steps, operations, units, components, and / or combinations thereof may be present or added.

[0053] In addition, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or internal communication between two components. All technical and scientific terms used in this specification have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs. The terms used in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more related listed items.

[0054] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0055] Example 1

[0056] To achieve the above objectives, the present invention provides a phase change heat storage unit for a filling type heat storage heating simulation system. Figures 1-21 , of which Figure 1 and attached Figure 2 They are respectively a flow chart of the heat storage heating system and a structural schematic diagram of the simulated heat storage unit in this embodiment, specifically including: a solar collector for collecting solar energy and converting it into thermal energy; a packed bed phase change heat storage tank, which is formed by filling capsules encapsulating phase change materials, with a water layer at the bottom of the phase change heat storage tank, and the top of the phase change heat storage tank is connected to the buffer water tank through a pipe; a temperature-controlled diverter valve, which adjusts the flow distribution according to the temperature of the heat storage tank outlet and the buffer water tank outlet; an air source heat pump, which is used to supplement the heat supply when the return water temperature is lower than the set threshold. In some embodiments, the phase change material is sodium acetate trihydrate, the phase change temperature of the phase change material is 58-61°C, and the latent heat storage density of the phase change material is 264kJ / kg. In some embodiments, the return water temperature threshold range of the air source heat pump is 30-35°C. The relevant parameters of the packed bed phase change heat storage tank and SAT are shown in Table 1:

[0057] Parameter name value Tank height H / m 4.6 Tank diameter D / m 2.5 Capsule diameter d / mm 50 Water layer height Hw / m 0.5 Phase transition temperature of SAT tm / ℃ 58-61 Density ρ / kg·m-3 1450 Phase change latent heat L / kJ·kg-1 264 Specific heat capacity cp / kJ·kg-1·K-1 1.71(s)，3.34(l) Thermal conductivity λ / W·m-1·K-1 0.4(s)，0.6(l) Cost C / $·kg-1 0.22–0.71

[0058] Table 1: Related parameters of packed bed phase change thermal storage tank and SAT

[0059] Example 2

[0060] To achieve the above objectives, an embodiment of the present invention provides a simulation method for a packed bed phase change thermal storage heating system, comprising the following steps:

[0061] S1, build a dynamic simulation platform for seasonal thermal storage heating system through the transient system simulation model TRNSYS, define system component parameters and energy flow relationships, and obtain the dynamic performance and real-time simulation results of the thermal storage heating system;

[0062] S2, using the phase change thermal storage unit for the packed-bed thermal storage heating simulation system disclosed in the above embodiment, simulating the temperature distribution, change trend and phase change process in the packed-bed phase change thermal storage unit in TRNSYS, and obtaining simulation data of the packed-bed thermal storage unit;

[0063] S3, by controlling the time step to be consistent, the simulation data of the packed bed phase change thermal storage unit is imported into the multi-physics simulation software COMSOL, a coupled simulation model of the coupled transient system simulation model and the multi-physics simulation model is established, and the coupled simulation results are obtained;

[0064] S4, based on the coupled simulation results, optimize and output the design parameters and control strategy of the thermal storage unit.

[0065] In some embodiments, the simulation model of the multi-physics simulation software COMSOL includes multi-physics local thermal non-equilibrium simulation and non-isothermal flow simulation, wherein the simulation process includes heat conduction, heat convection and non-isothermal flow in porous media.

[0066] In some embodiments, a coupled simulation model of a coupled transient system simulation model and a multi-physics field simulation model is established as follows: the coupled simulation model couples the simulation modules of solid heat transfer and fluid heat transfer in the multi-physics field local thermal non-equilibrium module, and couples the simulation modules of free porous medium flow and fluid flow in the non-isothermal flow simulation.

[0067] In some embodiments, S3 includes the following steps:

[0068] S31, the simulation model of the simplified packed bed phase change heat storage unit is a two-dimensional rotationally symmetric model. The packed bed region of the simplified phase change heat storage unit is a porous medium, and the porosity of the packed bed phase change heat storage unit varies radially.

[0069] In some embodiments, a simulation method for a packed bed phase change thermal storage heating system uses a modular transient system simulation program to simulate the seasonal thermal storage heating system of a single-family house in Baoding, China, focusing on analyzing the heating performance of the phase change material thermal storage unit during the heating season. Figure 1 , attached Figure 1 This is a system flow diagram of the packed bed phase change thermal storage heating system. Specifically, during the day, solar energy collected by the collectors is temporarily stored in the day and night tanks. A portion of this heat is used to raise the return water temperature for heating, while another portion is used to charge the phase change material in the seasonal thermal storage tank or to heat the building together with the phase change thermal storage tank. A temperature-controlled diverter valve adjusts the flow distribution based on the outlet temperatures of the buffer water tank and the phase change thermal storage tank, maintaining the heating temperature within the set range. In addition, an air-source heat pump is added as an auxiliary heat source to provide additional heat when heating is insufficient. Specifically, floor radiant heating is used during the heating season. To ensure comfort, the heating temperature is set at 40°C, and the return water temperature is set at no less than 30°C. When the return water temperature falls below 30°C, the air-source heat pump is activated and operates at a certain power level. The phase change thermal storage tank is buried underground near the building, exchanging heat only with the soil. The day and night tanks and buffer water tank are located indoors. The collectors are vacuum tubes, arranged in parallel on the south side of the roof. Furthermore, to study the operational characteristics of a seasonal heat storage system using phase-change materials, a control system was established. A water tank, theoretically calculated to have a total heat storage capacity equivalent to that of the phase-change heat storage tank at the start of the heating season, was used in its place.

[0070] This system uses TRNSYS software to build a dynamic simulation platform for a seasonal solar thermal storage system to obtain the system's dynamic performance and real-time simulation results. Detailed information on the main devices in the system is shown in Table 1 in the above example and Table 2 below:

[0071]

[0072]

[0073] Table 2: Module components in TRNSYS

[0074] In the system, the simulation of the phase change heat storage tank is processed by using the interpolation function to process the inlet temperature and flow rate. After accurately controlling the time step, the data is imported into the multi-physics simulation software COMSOL, and the time step is strictly controlled to be consistent, thus achieving effective data transmission. The phase change heat storage tank adopts a packed bed type thermal energy storage method. By encapsulating the phase change material in a capsule and filling it into the storage tank, efficient heat transfer is achieved. The schematic diagram of the storage tank is shown in the attached figure. Figure 2 As shown. PCM selects Sodium Acetate Trihydrate (SAT) as the heat storage medium because SAT has a high latent heat storage density and good economic efficiency. The relevant parameters are shown in Table 1 in the above embodiment. In the heat transfer simulation of COMSOL, the physical processes involved include heat conduction and heat convection, and the fluid dynamics considers the non-isothermal flow in the porous medium. In the multi-physics local thermal non-equilibrium module, the "solid heat transfer" and "fluid heat transfer" modules are combined through the coupling interface; in the non-isothermal flow module, the coupling interface is used to connect the "free porous medium flow" and "fluid flow" modules. In order to simplify the simulation of the model, the establishment of the physical model follows the following assumptions: 1. The radial porosity in the bed area of ​​PCM capsules of the same size is oscillating. However, the axial and circumferential porosity are consistent; 2. The HTF flow state remains stable; 3. The phase change material completely fills the internal volume of the capsule, and the influence of thermal expansion during the phase change process is not considered.

[0075] Based on the above assumptions, the storage tank is simplified into a two-dimensional rotationally symmetric model, and the packed bed region can be regarded as a porous medium with radially varying porosity.

[0076] The Brinkman equation and the continuity equation are combined to solve the flow in the porous media region.

[0077]

[0078] In formula (1): ε is the porosity of the packed bed; ρ f is the fluid density; is the vector velocity.

[0079] The momentum equation for the Brinkman equation is shown below:

[0080]

[0081] In formula (2), p is pressure; μ is dynamic viscosity; K is the permeability of porous media; C i is the inertial resistance coefficient; F is the force term, which includes the influence of gravity and other body forces; g is the acceleration due to gravity. K and C can be determined by the following formula i .

[0082]

[0083] In formulas (3) and (4), d is the inner diameter of the capsule.

[0084] A continuous solid phase model is used to resolve the local thermal non-equilibrium between the fluid and the heat storage medium. The energy conservation equation for the HTF and PCM can be calculated using the following formula:

[0085]

[0086] In formula (5) and (6), c p is the specific heat capacity; ρ is the density; λ is the thermal conductivity; h V is the volume heat transfer coefficient between the fluid and the envelope, which can be calculated by the following formula:

[0087]

[0088] In formula (7), Re is the Reynolds number, which is a parameter describing the flow properties of the fluid; Pr is the Prandtl number, which is a parameter describing the heat transfer characteristics of the fluid.

[0089] The porosity of the packed bed can be determined based on the capsule diameter d p and radial position R x The calculation formula is as follows:

[0090]

[0091] in:

[0092] a=0.045-0.55e -D / d (9)

[0093] r′=(D / 2-R x ) / d (10)

[0094]

[0095] r r =br′2+r′+0.5,b=0.037-2e -D / d (12)

[0096]

[0097] Where: a, b, c and α are dimensionless constants; r′ is the normalized radial position; r e is the relative effective radius; r se is the relative radial position of the effective sphere center; r r is the radial position parameter.

[0098] Please refer to the attached Figure 3 , attached Figure 3 This is an energy flow diagram of a packed bed phase change heat storage heating system and simulation method. SC The solar collector receives solar radiation and converts it into heat energy. This energy is mainly divided into heat Q entering the seasonal heat storage tank. ST and the heat Q used to increase the initial heating temperature BT , where Q DT_loss , Q ST_loss , Q BT_loss are the heat losses caused by heat exchange between the day and night water tanks, PCM tanks and buffer tanks, respectively. Pipe_loss is the pipe heat loss of the entire system, Q HP Q is the additional heat provided by the air source heat pump when the heating temperature is insufficient. STES is the heat stored in the system during the non-heating season. The energy balance of the entire system can be expressed as:

[0099] Q SC +Q STES +Q HP =Q load +Q loss (14)

[0100] in

[0101] Q STES,PCM =m PCM (c p,s ΔT s +Δh fusion +c p,l ΔT l ) (15)

[0102] Q STES,w =m w c p,w ΔT w (16)

[0103] Q load =Q ST,load +Q BT,load +Q HP (17)

[0104] Qloss =Q DT,loss +Q ST,loss +Q BT,loss +Q pipe,loss (18)

[0105] Q T,loss =kA(T s -T g ) (19)

[0106] Where k is the heat transfer coefficient of the seasonal water tank surface, A is the surface area of ​​the tank, T s and T g The energy stored in the phase change thermal storage tank in the non-heating season is mainly divided into sensible heat and latent heat. p,s and C p,l are the specific heat of the solid and liquid phase change materials, ΔT s and ΔT l are the temperature changes of the phase change material in solid and liquid states, Δh fusion is the energy released or absorbed during the phase change process. The solar energy guarantee rate of the system can be calculated by the following formula:

[0107]

[0108] To verify the accuracy of the model, this example compared simulation results with experimental data from latent heat-packed beds in the literature. The results are shown in Figure 4(a), which shows experimental data for a PCM tank model. The gray line in the figure represents the experimentally measured temperature curve, while the green curve corresponds to the simulation results after adjusting the model to the same dimensions as the literature experiment and replacing the heat storage medium with the experimental Li2CO3-K2CO3-Na2CO3 mixture.

[0109] The comparison results show that the temperature change trends of the simulation and the experiment are basically consistent, but there are certain errors in the sensible heat rise stage. Analysis shows that the main source of the error is that the packaging material 304stainless steel used to encapsulate the PCM affects the thermal conductivity and specific heat capacity of the capsule PCM, causing it to deviate from the thermal physical parameters of the PCM itself. The experiment did not provide the parameters of the overall thermal conductivity and specific heat capacity of the capsule after encapsulation, but they can be calculated based on the mass ratio of PCM and packaging material. The red curve in Figure 4 (a) is the corrected simulation result, which is in good agreement with the experimental data, with a maximum error of less than 2%. In summary, the phase change heat storage tank model established in the embodiment of the present invention has high accuracy and feasibility.

[0110] The system model established in the literature adopts seasonal heat storage heating and floor radiation heating, which is similar to ours. After adjusting the equipment parameters, including collector area, water tank volume, meteorological parameters, building load and other data, the seasonal water tank average temperature changes throughout the year are simulated. The comparison with the literature is shown in Figure 4(b), which is the experimental data of the STES heating system. The model's annual average temperature is 63.81°C, and the error with the literature is 2.91%. The temperature change trend is basically consistent with the literature, and the maximum temperature deviation is 11.2%. It can be seen that the system model established by the embodiment of the present application is accurate and feasible. In another embodiment, a simulation method based on a packed bed phase change heat storage heating system is provided for application in a single-family building. Specifically: Baoding City is located in North China, and its meteorological parameters are shown in the attached figure. Figure 5 As shown, attached Figure 5 This diagram shows Baoding's annual meteorological data. The heating season typically runs from mid-November to mid-March, providing favorable conditions for heat storage in phase-change thermal storage tanks during the off-season. However, solar radiation intensity decreases significantly in winter, so when setting up solar collectors, consider using a higher tilt angle or a larger collector area to ensure sufficient heat collection.

[0111] The heating model simulated by the system is shown in the attached Figure 6 As shown, Figure 6 This is a schematic diagram of a heating building model simulated in SketchUp. This two-story single-family residence has five temperature zones, an actual heating area of ​​100 square meters, and an indoor heating temperature set at 20°C during the heating season. Table 3 below provides the parameters of the main building envelope. The model was created in SketchUp and imported into TrnBuild for load simulation.

[0112]

[0113]

[0114] Table 3: Building envelope parameters

[0115] Through dynamic simulation in TRNSYS, the relevant parameters of the building in the heating season are as follows: Figure 7 As shown, attached Figure 7 The diagram below shows the relationship between building load, phase change tank inlet temperature and flow rate. The cumulative heating load during the heating season is 6627 kWh, mainly concentrated in January. The temperature and flow rate at the seasonal heat storage tank inlet are as follows: Figure 7As shown, the flow rate is controlled by a temperature-controlled diverter valve, primarily determined by the tank outlet temperature. The flow rate into the tank reaches its maximum set value at the end of January. The temperature is primarily affected by solar radiation and the diurnal temperature of the water tank, resulting in significant diurnal fluctuations. The average total horizontal solar radiation during the heating season is 312.5 kWh. Based on load simulation results, taking into account heat dissipation losses and seasonal heat storage in the thermal storage tank, the design area of ​​the solar collector is 25 m2.

[0116] In the energy storage stage, when using phase change materials (PCM) for thermal energy storage, the stored heat is calculated in the temperature range of 35–75°C. The heat storage capacity of this phase change material is 356kJ / kg, which is 2.18 times (by mass) and 3.16 times (by volume) that of water. Taking into account the material density and the porosity of the packed bed water storage tank, the volume of the seasonal phase change material water storage tank required to store the same amount of heat is only 46.48% of that of the seasonal water tank. Because the water tank has a larger surface area, its heat loss over a longer period of time is significantly higher than that of the phase change material water storage tank. Therefore, when calculating the effective heat supply, the volume required for the water tank is significantly larger than that of the phase change material water storage tank. Appendix Figure 8 This figure shows the temperature changes and heat storage capacity of a phase change material (PCM) thermal storage tank during the non-heating season. The green line represents the average temperature inside the tank, which gradually rises after the heating season ends, reaching a peak of 80.02°C in September. Thereafter, as solar radiation weakens and the temperature difference with the ambient temperature increases, heat losses increase, making further heat storage increasingly difficult. By November, the tank is barely absorbing any additional heat. At the start of the heating season, the average internal temperature of the tank is 74.46°C. The blue line represents the tank outlet temperature. The phase change process in the uppermost layer of the phase change material begins at the end of March and continues until mid-July, at which point the PCM in the lowermost layer completes its phase change. After the phase change process, solar energy continues to be stored as sensible heat. The red line represents the heat storage capacity in the tank. The highest heat storage capacity occurs in April, attributed to the combination of high solar radiation intensity and relatively low tank temperature, which creates favorable conditions for heat storage. Despite the higher collector outlet temperature in summer, the heat storage capacity decreases due to the rising tank temperature.

[0117] In the heating phase, for comparison, Figure 9A schematic diagram shows the evolution of the outlet and average temperatures of the seasonal hot water storage tank before the air source heat pump was activated during the heating season. The results show that the tank's outlet temperature fluctuates significantly with the average temperature. In early January, the tank's average and outlet temperatures converged, resulting in a significant drop in system performance. In contrast, the phase change material system maintained a more stable outlet temperature, continuously providing hot water at 60°C to the building. Even when the tank's average temperature dropped to 47.4°C, the system's heat output remained stable. The following sections analyze the temperature trends and internal temperature distribution of the hot water storage tank at several key time points.

[0118] Attachment Figure 10 The temperature changes in the system at the beginning of the heating season are shown. During this period, the building heating mainly relies on sensible heat. -1 ·K-1) is higher than the specific heat capacity of liquid phase change materials (3.3kJ·kg -1 K-1), and the water tank's mass is significantly greater than the PCM water storage tank's. This causes the PCM water storage tank's average temperature to drop more rapidly than the water tank's. In the early stages of the heating season, when heat storage is sufficient and heating demand is low, the supply temperature remains stable at 40°C, while the return water temperature of both systems fluctuates around 37°C.

[0119] Figure 11(a) shows a schematic diagram of the system's temperature parameters around December 6th. During this period, the outlet temperature of the PCM heat storage tank began to drop rapidly. During sensible heating, the outlet temperature is primarily determined by the temperature of the bottom layer of PCM. At this point, the sensible heat of the liquid PCM is gradually depleted from top to bottom, causing the temperature of the bottom layer of PCM to drop, which in turn leads to a decrease in the outlet temperature.

[0120] Figure 11(b) shows a schematic diagram of the temperature distribution within a PCM hot water storage tank. At this point, the top layer of PCM has completed its phase transition, with its temperature dropping to near its melting point. Meanwhile, the bottom layer of PCM has not yet undergone a phase transition, but due to the depletion of sensible heat, its temperature is rapidly decreasing, approaching a phase transition state.

[0121] Figure 12(a) shows a schematic diagram of the system-related temperature changes at the end of December. As the building heating demand increased, the outlet temperature of the water tank decreased, mainly due to the operation of the temperature-controlled water diverter valve, which increased the inflow into the water tank and caused the average temperature of the water tank to drop rapidly. In contrast, the phase change material water storage tank mainly provides heat through latent heat release, resulting in a slower decrease in its average temperature, while the outlet temperature remains stable near the phase change temperature. By December 24, the outlet temperature of the seasonal water tank dropped below that of the phase change material water storage tank, and its average temperature dropped below that of the phase change material water storage tank on December 19.

[0122] Figure 12(b) shows a schematic diagram of the internal temperature distribution of a phase change material water storage tank, revealing a clear thermal stratification phenomenon. The upper layer of solid phase change material is significantly affected by diurnal temperature fluctuations, with the temperature fluctuating around 45°C. The lower layer of phase change material remains in a phase change state, with the temperature stabilized at the phase change point. Due to the daytime heat replenishment of the water tank, the priority of heat storage is optimized, forming a sequence of daytime heating, nighttime heat release, and gradual activation of the phase change layer. As a result, the entire phase change process is prolonged. Studies have shown that the proportion of remaining energy in the phase change material water storage tank is inconsistent with the proportion of phase change material that has completed the phase change process. When half of the seasonal thermal storage energy remains in the water tank, only 30%–40% of the phase change material has completed the phase change process.

[0123] Figure 13(a) shows a schematic diagram of the temperature changes within the system in mid-January. During this period, the average tank temperature and the heating supply temperature dropped below 40°C, resulting in reduced building heating performance. Furthermore, the return water temperature fell below the minimum required for the heating system, necessitating supplementary heating from an air-source heat pump. At this point, the return water temperatures of the two systems differed significantly.

[0124] Figure 13(b) shows the internal temperature distribution of the PCM water storage tank. Since early December, the PCM water storage tank has been providing hot water at 60°C. However, by mid-January, the heating temperature began to drop significantly. As the lowest layer of PCM gradually thinned during the phase change process, the heat transfer tank's ability to heat the heat transfer fluid weakened, causing the temperature to fail to reach the phase change temperature. However, the phase change process was not yet complete, and the outlet temperature fluctuated slightly, although the temperature of the upper layer of PCM fluctuated with the day and night.

[0125] In terms of operating characteristics, in a PCM hot water storage tank system, thermal energy collected during the day is initially stored in the upper layer of solid-state PCM. Because the heat transfer fluid (HTF) flows from top to bottom, this sensible heat is first utilized at night, before consuming the latent heat of the lowest layer of PCM. Even at the end of the heating season, when the seasonal thermal energy storage is completely depleted, the PCM hot water storage tank can still serve as a high-capacity daytime thermal energy storage unit.

[0126] In contrast, a water tank system operates as a completely liquid-filled reservoir, with the stored heat used first for heating in the summer, followed by the solar energy collected during the day during the heating season. This introduces a time delay between solar energy collection and utilization, a key factor in the long-term operation of air source heat pumps in water tank systems.

[0127] Attachment Figure 14A schematic diagram shows the cumulative effective heat supply over the entire heating season, calculated based on the temperature difference and flow rate between the inlet and outlet of the water storage tank. The cumulative effective heat supply of the phase-change material water storage tank peaked in February at 2070.8 kWh, then gradually declined with the introduction of the air-source heat pump. In contrast, the seasonal water tank system achieved a maximum effective heat supply of 1669.8 kWh in mid-January, 19.36% lower than that of the phase-change material water storage tank. This difference is primarily due to the seasonal water tank's higher heat losses in the early heating season and the reduced temperature difference between the upper and lower layers in the later stages, which limited its heating capacity.

[0128] The study found that after the seasonal water tank's effective heating capacity reaches its peak, the system's effective heating capacity declines significantly. This is because, as the average temperature of the water tank system decreases, even with the combined effects of solar collectors and air-source heat pumps, their large mass base prevents a significant increase in the seasonal water tank's outlet heating temperature within a short period of time. This results in a significant temperature deficit between the tank's inlet and outlet temperatures, causing the air-source heat pump to over-operate. The effective heating capacity only recovers after the tank's average temperature rises. PCM thermal storage tanks, however, can more promptly apply heat from solar energy and the air-source heat pump to the building load, eliminating this issue.

[0129] System energy efficiency evaluation, Figure 15 Schematic diagram of heat loss from the phase change thermal storage tank and water tank during the heating season. Because the seasonal water tank has a large heat dissipation area and stores a large amount of sensible heat, its heat loss temperature difference is large at the beginning of the heating season, exceeding the heat loss of the phase change thermal storage tank by 88.7%. As the water tank temperature decreases, the heat loss gradually decreases, reaching a minimum of 16.5% in mid-January. At this time, the average temperature of the phase change thermal storage tank is 49.8°C, while the temperature of the water tank is 32.1°C. Over the entire heating season, the total heat loss of the PCM thermal storage tank is 393.8 kWh, while the total heat loss of the seasonal water tank is 695.2 kWh, a 76.5% increase compared to the phase change thermal storage tank.

[0130] Figure 16 This chart illustrates the return water temperature changes of the phase change thermal storage tank and water tank systems during the heating season, as well as the start-up and shutdown of the air source heat pump. In early January, the return water temperature of the seasonal water tank system differed significantly from that of the PCM system. While the seasonal water tank's heating temperature failed to reach the set 40°C, the return water temperature remained above the minimum return water temperature of 30°C, meeting the minimum heating requirement. In mid-January, the return water temperature of the water tank system first dropped below 30°C, requiring auxiliary heating from the air source heat pump. The PCM thermal storage tank system, however, continued to provide heating normally until the return water temperature dropped below 30°C in February, when the air source heat pump was first activated.

[0131] In the seasonal water tank system, the air source heat pump was first started on January 11th and operated for a total of 525 hours, accounting for 18.3% of the total heating season, providing 1,133 kWh of heat to the system, with a solar energy guarantee rate of 82.9%. In the phase change thermal storage tank system, the air source heat pump was first started on January 29th and operated for a total of 288 hours, a 45.1% reduction compared to the water tank system, accounting for 10% of the total heating season, providing 619.3 kWh of heat to the system, with a solar energy guarantee rate of 90.7%, a 7.8% improvement over the water tank system.

[0132] This study uses the system coefficient of performance (SCOP) as the evaluation index of system energy consumption, which is the ratio of the energy provided by the system to the electrical energy consumed. Figure 17(a) and 17(b) The energy distribution and system performance coefficients of the phase-change thermal storage tank system and the water tank system during the heating season are shown in Figure 2. In the seasonal phase-change thermal storage tank system, the average SCOP value was 13.75, while in the seasonal water tank system, the SCOP value was only 9.22, 4.53 points lower than the phase-change thermal storage tank system. The difference between the two was mainly concentrated in January. The air source heat pump in the seasonal water tank system began operating in early January, while the energy consumption of the PCM thermal storage tank system was mainly concentrated in February. The comparison results of various aspects of the PCM tank system and the water tank system are shown in Figure 2. Figure 18 shown.

[0133] In terms of system optimization and economic evaluation, to improve the system's solar energy utilization during the heating season and reduce heat pump operating time, the parameters of the collector and seasonal heat storage tank in the seasonal heating system were optimized. The installation cost of the vacuum tube collector is $64.8-117.7 per square meter, while the current procurement cost of phase change thermal storage material is $0.22-0.71 per kilogram. In comparison, the optimized cost of the collector is much lower than that of the seasonal heat storage tank.

[0134] Typically, the ratio of the solar collector area to the building's heating area is approximately 1:5. Considering that residential buildings are located in the northern hemisphere, where winters are cold, this ratio can be appropriately increased to maximize the contribution of solar energy to building energy consumption. Solar collectors are installed on building roofs, and their area is limited by the total roof area, so the collector area is set at 32 square meters. Increasing the inclination of the solar collector can increase the amount of solar energy collected in the winter, but it also reduces the storage of seasonal solar energy in the summer. To ensure effective summer heat storage, the collector's inclination should not exceed 55 degrees.

[0135] Figure 19(a) shows a comparison of the seasonal thermal storage tank outlet temperature during the heating season after adjusting the solar collector parameters and without using an air-source heat pump. The optimized system absorbs more solar radiation during the heating season, increasing the sensible heat consumption phase temperature by a maximum of 2.83°C, extending the 60°C hot water supply duration by 403 hours, delaying the initial start-up of the air-source heat pump by 310 hours, and increasing the solar energy guarantee rate from 90.7% to 98.5%, significantly enhancing the system's heating stability.

[0136] The volume of the heat storage tank is adjusted by adjusting the height of the tank. Figure 19(b) shows the change in outlet temperature at different tank heights. The results show that when the tank height increases from 3.60 meters to 3.80 meters (the tank volume increases by 5.56%), the minimum heating temperature of the system meets the heating requirements and ensures 100% heating load. This not only effectively reduces the dependence on auxiliary heating equipment, but also improves the utilization efficiency of solar energy, further improving the overall performance of the system. This adjustment significantly improves the heating stability and economy of the system without increasing energy consumption. The environmental performance of the phase change seasonal heat storage system is evaluated by carbon dioxide emission reduction, and the calculation formula is as follows:

[0137]

[0138] Where ΔC is the CO2 emission reduction in the heating season, kg; Q u is the effective heat provided by solar energy in a year, MJ; F CO2 is the carbon emission factor, coal is 3.662, natural gas is 1.48; W coal is the calorific value of standard coal per unit mass, which is 29.308MJ / kg; η con Efficiency of conventional energy heating units.

[0139] Compared with conventional heating systems, the optimized seasonal phase change heat storage system can reduce carbon emissions by approximately 3725.9 kg per year. Compared with the seasonal water tank system, the effective heating capacity is increased by 4079.6 MJ, and carbon emissions are reduced by 17.1%. It has significant energy-saving performance and long-term development prospects.

[0140] The study constructed a life cycle cost (LCC) model to analyze the economics of the phase change thermal storage system. The cost structure model is as follows:

[0141]

[0142] Among them C invest is the initial investment, mainly including collectors and storage tanks, etc. op,t is the operation and maintenance cost in year t, B saving,tis the energy saving benefit in year t (compared with traditional gas boilers), r is the discount rate, which is 5%, and n is the system life, which is calculated as 20 years.

[0143] The cost of SAT as a heat storage medium is $319 / m 3 For large-volume purchases (over one ton), the cost will be reduced to $232.3 / m 3 The total cost of the collector is $2073.6, and the total initial investment of the system is $4672.4. The price of natural gas in China is $0.58 / m 3 , while in Europe and other regions, natural gas prices are relatively expensive, at $0.85 / m 3 Some regions also encourage energy conservation and emission reduction through carbon tax policies (US$50 / ton CO2). The changes of LCC in different situations are as follows: Figure 20 As shown in Figure 2, the system has a minimum payback period of 5.9 years and a maximum NPV of $6,801.5. If policies exist to subsidize the initial investment, with a 20% subsidy, the payback period is shortened to 4.7 years.

[0144] In summary, to study the application of phase change materials in seasonal thermal energy storage, the present invention provides a dynamic simulation platform based on TRNSYS to simulate the performance of a solar seasonal thermal energy storage system (STES) for independent buildings in Baoding, China during the heating season. This embodiment uses a packed bed phase change material water storage tank to simulate the temperature distribution and variation trend within the water storage tank, covering detailed analysis of different time periods. By innovatively coupling the transient system simulation software TRNSYS with the multi-physics field simulation software COMSOL, this study effectively overcomes the limitations of traditional modular simulation and compensates for the lack of common components, thereby achieving higher-precision system modeling.

[0145] The research results show that the proposed phase change material hot water storage tank has significant advantages over traditional water tanks in terms of energy efficiency and operational performance, showing its strong potential in small-scale residential solar seasonal thermal energy storage applications. The main conclusions are as follows:

[0146] The packed bed phase change material thermal storage tank requires only 46.48% of the volume of a conventional water tank to achieve the same theoretical heat storage capacity (accounting for pore effects). Compared to the water tank, it reduces heat loss by 43.4% and increases the maximum effective heat supply by 24.1%. However, the PCM system requires an additional 619.3 kWh of auxiliary heat to maintain indoor temperatures during the heating season. Its solar energy utilization rate reaches 90.7%, which is better than the 82.9% of the water tank system. As a result, the seasonal coefficient of performance of the water tank system is 4.53 lower than that of the phase change material thermal storage system.

[0147] When the water tank system reaches its maximum effective heat supply, delayed heat return occurs as the internal temperature approaches uniformity, slowing heat transfer to the building. This increases the operating frequency of the heat pump and increases power consumption. The phase change material system, which releases and utilizes heat more efficiently, successfully alleviates this problem and improves overall performance. The solar collector area was expanded to 32m 2 The solar energy efficiency of the seasonal phase change material system was significantly improved by increasing the volume of the hot water storage tank by 5.56%. Under these conditions, the system can provide stable heating without the need for auxiliary heat sources, greatly enhancing operational reliability.

[0148] Example 3

[0149] To achieve the above objectives, an embodiment of the present invention provides a packed bed phase change thermal storage heating simulation system, comprising:

[0150] The dynamic simulation module of the seasonal thermal storage heating system is used to build a dynamic simulation platform for the seasonal thermal storage heating system through the transient system simulation model TRNSYS, define system component parameters and energy flow relationships, and obtain the dynamic performance and real-time simulation results of the thermal storage heating system;

[0151] A filled phase-change heat storage module includes a phase-change heat storage unit for a filled heat storage heating simulation system as disclosed in the above embodiment, and is used to collect temperature distribution, change trend, and phase change process in the filled phase-change heat storage unit to obtain simulation data of the heat storage unit;

[0152] The multi-physics coupling simulation module is used to import the simulation data of the packed bed phase change thermal storage unit into the multi-physics simulation software COMSOL by controlling the time step to be consistent, establish a coupled simulation model of the coupled transient system simulation model and the multi-physics simulation model, and obtain coupled simulation results;

[0153] The strategy optimization and output module is used to optimize and output the design parameters and control strategies of the thermal storage unit based on the coupled simulation results.

[0154] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0155] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0156] The above is a detailed introduction to a packed bed phase change heat storage heating simulation system, simulation method, heat storage unit, device, product, equipment and medium provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for general technical personnel in this field, based on the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A phase change heat storage unit for a filling type heat storage heating simulation system, characterized in that: include: Solar thermal collectors, which collect solar energy and convert it into heat; The packed bed phase change heat storage tank is formed by filling capsules encapsulating phase change materials. A water layer is provided at the bottom of the phase change heat storage tank, and the top of the phase change heat storage tank is connected to a buffer water tank through a pipe. Temperature-controlled diverter valve adjusts flow distribution according to the outlet temperature of the heat storage tank and the buffer water tank; Air source heat pump, used to provide supplemental heating when the return water temperature falls below a set threshold.

2. The phase change heat storage unit for a filling type heat storage heating simulation system according to claim 1, characterized in that: The phase change material is sodium acetate trihydrate, the phase change temperature of the phase change material is 58-61° C., and the latent heat storage density of the phase change material is 264 kJ / kg.

3. The phase change heat storage unit for a filling type heat storage heating simulation system according to claim 1, characterized in that: The return water temperature threshold range of the air source heat pump is 30-35°C.

4. A simulation method for a packed bed phase change thermal storage heating system, characterized in that: The following steps are involved: S1, build a dynamic simulation platform for seasonal thermal storage heating system through the transient system simulation model TRNSYS, define system component parameters and energy flow relationships, and obtain the dynamic performance and real-time simulation results of the thermal storage heating system; S2, using the packed-bed phase change thermal storage unit for thermal storage heating system simulation according to any one of claims 1 to 3, simulating the temperature distribution, change trend, and phase change process in the packed-bed phase change thermal storage unit in TRNSYS, and obtaining simulation data of the packed-bed thermal storage unit; S3, by controlling the time step to be consistent, the simulation data of the packed bed phase change thermal storage unit is imported into the multi-physics simulation software COMSOL, a coupled simulation model of the coupled transient system simulation model and the multi-physics simulation model is established, and the coupled simulation results are obtained; S4, based on the coupled simulation results, optimize and output the design parameters and control strategy of the thermal storage unit.

5. The simulation method of the packed bed phase change thermal storage heating system according to claim 4, characterized in that: The simulation model of the multi-physics simulation software COMSOL includes multi-physics local thermal non-equilibrium simulation and non-isothermal flow simulation, wherein the simulation process includes heat conduction, heat convection and non-isothermal flow in porous media.

6. The simulation method of the packed bed phase change thermal storage heating system according to claim 5, characterized in that: The coupled simulation model for establishing the coupled transient system simulation model and the multi-physics field simulation model is as follows: the coupled simulation model couples the simulation modules of solid heat transfer and fluid heat transfer in the multi-physics field local thermal non-equilibrium module, and couples the simulation modules of free porous medium flow and fluid flow in the non-isothermal flow simulation.

7. The simulation method of the packed bed phase change thermal storage heating system according to claim 4, characterized in that: S3 includes the following steps: S31, the simulation model of the simplified packed bed phase change heat storage unit is a two-dimensional rotationally symmetric model. The packed bed region of the simplified phase change heat storage unit is a porous medium, and the porosity of the packed bed phase change heat storage unit varies radially.

8. A packed bed phase change thermal storage heating simulation system, characterized in that: include: The dynamic simulation module of the seasonal thermal storage heating system is used to build a dynamic simulation platform for the seasonal thermal storage heating system through the transient system simulation model TRNSYS, define system component parameters and energy flow relationships, and obtain the dynamic performance and real-time simulation results of the thermal storage heating system; A filled phase change heat storage module, comprising a phase change heat storage unit for a filled heat storage heating simulation system according to any one of claims 1 to 3, for collecting temperature distribution, change trend, and phase change process in the filled phase change heat storage unit to obtain simulation data of the heat storage unit; The multi-physics coupling simulation module is used to import the simulation data of the packed bed phase change thermal storage unit into the multi-physics simulation software COMSOL by controlling the time step to be consistent, establish a coupled simulation model of the coupled transient system simulation model and the multi-physics simulation model, and obtain coupled simulation results; The strategy optimization and output module is used to optimize and output the design parameters and control strategies of the thermal storage unit based on the coupled simulation results.

9. An electronic device, characterized in that: comprising a memory and a processor, wherein: The memory is used to store computer programs; The processor is used to execute the computer program to implement the simulation method of the packed bed phase change thermal storage heating system according to any one of claims 4 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: The computer program is used to be executed by a processor to implement the simulation method of the packed bed phase change thermal storage heating system according to any one of claims 4 to 7.

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