Heating system and operation method thereof

Abstract

The invention discloses a heating system and an operation method thereof, and relates to the technical field of heat energy storage. The heating system comprises an air source heat pump, a packed bed phase change heat storage device and a radiator. The air source heat pump and the packed bed phase change heat storage device are connected in series to form a heat storage circulation loop; the packed bed phase change heat storage device and the radiator are connected in series to form a heat release circulation loop; a branch pipeline is further arranged in the heat release circulation loop; and the branch pipeline is connected with the packed bed phase change heat storage device in parallel. According to the operation method, by optimizing a flow curve and adopting a circulating water flow curve with linear growth and parabolic growth, the purpose of prolonging the effective heat release time of the packed bed phase change heat storage device is finally achieved, efficient heat storage can be achieved, and the effective heat release time is greatly prolonged; and a preferable scheme with wider adaptability is provided for efficient utilization and heat energy storage of the air source heat pump.

Description

Technical Field

[0001] The present invention relates to an energy system, in particular to a heating system and an operation method thereof, and belongs to the technical field of green energy and electric power industry. Background Art

[0002] With the continuous growth of energy demand and the increasing pressure of environmental protection, traditional heating methods have gradually exposed their shortcomings such as high energy consumption and serious pollution. Especially in the winter heating process, the heating system that relies on fossil fuels will aggravate air pollution and greenhouse gas emissions. Therefore, the development of energy-saving and environmentally friendly clean energy heating technology has become an important issue in today's society. As a new type of efficient clean heating equipment, air source heat pump extracts low-temperature heat energy from the air and transmits it to the room through compressor heating. It has the advantages of high energy conversion efficiency and low operating cost. Compared with traditional gas boilers or electric heating systems, air source heat pumps have higher energy efficiency ratio (COP) and do not produce harmful gas emissions during use. Therefore, they are increasingly widely used in the heating field. However, the operating efficiency of air source heat pumps in cold winter climates has certain limitations. In low temperature environments, the energy efficiency ratio (COP) of heat pumps is often significantly reduced, resulting in a decrease in system performance and may affect the user's heating needs. In addition, the operation of the air source heat pump system mainly depends on the external temperature conditions, and there is a certain instability. Especially in the case of large load fluctuations, the operating efficiency of the system cannot be effectively guaranteed. In order to solve these problems, the use of phase change thermal storage technology will be a feasible solution. Phase change materials can absorb or release a large amount of latent heat within a certain temperature range and have a high heat storage density. The introduction of a phase change thermal storage device in the air source heat pump system can store heat during non-heating peak periods and release heat when the heating demand is high, thereby balancing the system load and improving the stability and energy efficiency of the system. The packed bed phase change thermal storage device is a relatively mature thermal energy storage technology. It uses the high specific surface area of ​​the packed bed structure to enhance the heat exchange efficiency with the phase change material, which can effectively improve the speed and efficiency of thermal energy storage and release. However, the existing packed bed phase change thermal storage devices still face technical difficulties in practical applications, such as insufficient effective heat release time, uneven heat transfer, slow phase change process, and insufficient coupling between the heat pump system and the thermal storage device. Summary of the invention

[0003] In view of the above problems, the purpose of the present invention is to overcome the problems such as insufficient effective heat release time of the heating system of the air source heat pump coupled with a packed bed phase change heat storage device, and provide an air source heat pump coupled with a packed bed phase change heat storage device heating system and an operation method thereof. By optimizing the flow curve, the effective heat release time is increased, the heat transfer efficiency in the phase change heat storage process is improved, and the efficient and stable operation of the system under various working conditions is ensured, thereby overcoming the shortcomings of the prior art, providing a system configuration design scheme and a numerical simulation method for the renewable energy multi-energy complementary system, and improving the application effect of the energy system.

[0004] One aspect of the present invention provides a heating system, which is an air source heat pump coupled to a packed bed phase change thermal storage device heating system.

[0005] Optionally, the heating system comprises: an air source heat pump, a packed bed phase change thermal storage device, and a radiator; The air source heat pump is connected in series with the packed bed phase change heat storage device to form a heat storage circulation loop; The packed bed phase change heat storage device is connected in series with the radiator to form a heat release circulation loop; A branch pipeline is also provided in the heat release circulation loop; the branch pipeline is connected in parallel with the packed bed phase change heat storage device.

[0006] In the present invention, the air source heat pump is based on the reverse Carnot cycle, extracting low-temperature heat energy from the outside air and raising the heat to a higher temperature through a compressor to heat the circulating water.

[0007] The packed bed phase change thermal storage device is a device that stores and releases thermal energy by combining a packed bed structure with a phase change material. The device mainly utilizes the latent heat characteristics of the phase change material, so that within a certain temperature range, a large amount of thermal energy can be efficiently stored and released through the phase change process.

[0008] Optionally, the heating system also includes: a first three-way mixing valve; the first port of the first three-way mixing valve is connected to port I of the packed bed phase change heat storage device, the second port of the first three-way mixing valve is connected to the water supply pipeline of the radiator, and the third port of the first three-way mixing valve is connected to the branch pipeline.

[0009] Optionally, the heating system further comprises: a second three-way mixing valve and a third three-way mixing valve; The port II-1 of the second three-way mixing valve is connected to the outlet of the air source heat pump, the port II-2 of the second three-way mixing valve is connected to the port I of the packed bed phase change heat storage device, and the port II-3 of the second three-way mixing valve is connected to the water supply pipeline of the radiator; Port III-1 of the third three-way mixing valve is connected to the inlet end of the air source heat pump, port III-2 of the third three-way mixing valve is connected to port II of the packed bed phase change heat storage device, and port III-3 of the third three-way mixing valve is connected to the return water pipeline of the radiator.

[0010] Optionally, the heating system comprises: In the heat storage mode, when the electricity is off-peak, the air source heat pump and the packed bed phase change heat storage device form a heat storage circulation loop, and the circulating water is heated to circulate heat storage in the packed bed phase change heat storage device; and heat release mode, when in peak heat usage, the packed bed phase change heat storage device, the radiator and the branch pipeline form a heat release circulation loop, wherein the packed bed phase change heat storage device is connected in series with the radiator, and the packed phase change heat storage device is connected in parallel with the branch pipeline; the heat energy in the packed bed phase change heat storage device heats the circulating water in the radiator.

[0011] In the present invention, the heating system uses electricity to drive the air source heat pump to store heat energy in the packed bed phase change thermal storage system during off-peak hours, and releases it during peak hours. In terms of heating, a branch is provided in the heating subsystem, and a three-way mixing valve is installed in front of the radiator (radiator) to control the supply / return water temperature of the radiator (radiator) by mixing the flow.

[0012] In the present invention, the operation mode of the entire air source heat pump coupled packed bed phase change thermal storage device heating system is determined according to the weather and user needs. The system has the following two working modes: (1) Heat storage mode: When the electricity is off-peak, the air source heat pump heats the circulating water to circulate and store heat in the packed bed phase change thermal storage device until it is full. In this circulating heat storage mode, the inlet temperature of the packed bed phase change thermal storage device is in a non-steady state, depending on the heating power of the air source heat pump and the circulating water flow rate.

[0013] (2) Heat release mode: During the peak heat consumption period, the heat energy stored in the packed bed phase change thermal storage device is used to heat the circulating water in the radiator. The return water from the radiator flows to the packed bed phase change thermal storage device for heat recovery. The outlet water flow of the packed bed phase change thermal storage device is mixed with the return water from another part of the radiator through the branch in a specific ratio by controlling the three-way mixing valve to maintain the required water supply temperature of the radiator under the current conditions. In addition, the return water flow distribution entering the packed bed phase change thermal storage device and the branch needs to follow an adjusted time-varying curve to deal with the problem of nonlinear decrease in the outlet water temperature of the packed bed phase change thermal storage device with the heat release process. On the other hand, the inlet temperature of the packed bed phase change thermal storage device (the return water temperature of the radiator) will change with the performance of the radiator, which is caused by the change in the supply water temperature. In this heat release mode, the heat release process modeling of the packed bed phase change thermal storage device needs to consider the dynamic changes of the circulating water inlet temperature and flow rate over time, that is, the inlet temperature and flow rate are both in a non-steady state, so as to better reflect the actual working conditions.

[0014] Another aspect of the present invention provides an operating method of the above-mentioned heating system, the operating method comprising: Establishing a heating device of an air source heat pump coupled with a packed bed phase change thermal storage device, wherein the heating device is selected from the above-mentioned heating system; Establish a numerical model of packed bed phase change thermal storage device; Establish a numerical model of user-side radiator; The heating equipment of the air source heat pump coupled with the packed bed phase change thermal storage device operates according to the circulating water flow curve solved by the numerical model of the packed bed phase change thermal storage device and the numerical model of the user-side radiator.

[0015] Optionally, the numerical model of the packed bed phase change thermal storage device is a one-dimensional transient cycle thermal storage mathematical model established by a concentric diffusion model.

[0016] In the present invention, during the cyclic heat storage process, the heat pump system directly extracts heat energy from the ambient air and transfers it to the circulating water. Subsequently, the circulating water transfers the heat energy to the packed bed thermal storage system, and the phase change material in the spherical capsule absorbs the heat energy, causing melting and storing the heat energy. It is worth noting that the thermal performance of the packed bed thermal storage system is closely related to the heating power of the air source heat pump system and the flow rate of the circulating water. Numerical methods have been widely used to simulate heat transfer processes. In the present invention, a one-dimensional transient cyclic heat storage mathematical model of the packed bed thermal storage system is established using the concentric diffusion model. The model divides the packed bed thermal storage system into two computational domains, the first computational domain covers the packed bed area where the circulating water flows, and the second computational domain involves the internal area of ​​the spherical capsule.

[0017] In order to improve computational efficiency and speed up calculations, the following assumptions were made during the modeling process: (1) For the heat transfer and flow of circulating water, the packed bed is equivalent to an isotropic porous medium; (2) The heat transfer and flow of circulating water in the packed bed are both one-dimensional and axial; (3) The thermal properties of circulating water are constant; (4) The packed bed spherical capsules are all spherical, and the same type of thermal storage units have a uniform hydraulic diameter; (5) The phase change heat storage medium is evenly filled in the spherical capsule, and the changes in volume and physical properties caused by the solid-liquid phase change are ignored; (6) The melting and solidification processes of the phase change thermal storage material occur in the same temperature range; (7) The thermal properties of the packed bed thermal storage unit are all constant; (8) Neglect the contact heat conduction and radiation heat transfer between the spherical capsules in the packed bed and the thermal resistance of their shells, ignore the radiation heat transfer between the circulating water, and ignore the heat exchange between the thermal storage system and the environment; (9) The maximum water temperature at the heat pump outlet shall not exceed 55°C.

[0018] Based on the above assumptions, the energy control equations of circulating water and phase change materials are as follows.

[0019] Optionally, in the numerical model of the packed bed phase change thermal storage device, the energy control equation of the circulating water is:

[0020] In the formula, is the porosity of the packed bed, is the heat transfer fluid density, is the specific heat capacity of the heat transfer fluid, is the temperature of the heat transfer fluid, is the flow rate of the heat transfer fluid, is the thermal conductivity of the heat transfer fluid, is the bulk heat transfer coefficient between the heat transfer fluid and the phase change capsule, is the radial direction of the phase change capsule, is the axial direction of the packed bed, , are the inner and outer radii of the phase change capsule, is the viscosity of the heat transfer fluid, and represent the Reynolds number and Prandtl number of the packed bed, respectively; In the numerical model of the packed bed phase change thermal storage device, the energy control equation of the phase change material (PCM) is:

[0021] In the formula, is the density of phase change material, is the specific enthalpy of the phase change material, is the effective thermal conductivity of the phase change material, is the solid-state specific heat capacity of the phase change material, is the liquid specific heat capacity of the phase change material, is the phase change enthalpy of the phase change material, is the melting temperature of the phase change material, is the solidification temperature of the phase change material, is the solid-state thermal conductivity of the phase change material, is the liquid thermal conductivity of the phase change material; In the numerical model of the packed bed phase change thermal storage device, the boundary conditions are:

[0022] In the formula, is the initial temperature of the system, is the packed bed inlet temperature, is the packed bed outlet temperature, is the heating power of the system, is the packed bed height.

[0023] In the present invention, according to the proposed assumptions, the packed bed is simulated as a one-dimensional computational domain, and the control equations of the mathematical model are solved in MATLAB R2020a by the implicit finite difference method. The time term and convection term of the equation are discretized by the forward difference method, and the discretization of the diffusion term is calculated by the central difference method. The calculation process is as follows Figure 3 shown.

[0024] In each time step, the temperature field of the heat exchange fluid is solved, and then this temperature field is used as the boundary condition to solve the internal temperature field of each heat storage unit in the calculation domain of the heat exchange fluid, and some thermal properties of the phase change heat storage medium are updated; the surface temperature of each heat storage unit is used as the temperature boundary condition to solve the temperature field of the heat exchange fluid; the solution is repeated alternately until the temperature field of the heat exchange fluid and the internal temperature field of each heat storage unit reach the convergence condition (the temperature field residual is less than 10 -6 ).

[0025] Optionally, in the user-end radiator numerical model (user-side radiator numerical model), the radiator performance is calculated using the logarithmic mean temperature difference method, the heating power of the radiator is calculated through iterative matching, and the radiator heating temperature and return water temperature are derived.

[0026] Optionally, the user-side radiator numerical model is:

[0027] In the formula, is the flow rate of circulating water in the packed bed, is the outlet water temperature of the packed bed, is the flow rate of circulating water in the radiator, is the flow rate of circulating water in the bypass, is the heating power of the radiator, The heating temperature of the radiator, is the return water temperature, is the radiator index, =1.2~1.3, is the logarithmic mean temperature difference.

[0028] In the present invention, the packed bed phase change thermal storage device is operated in series with the radiator during the heat release process to provide thermal energy. Therefore, the inlet temperature (T in ) is equal to the return water temperature of the radiator (T return ), which is affected by the thermal properties of the radiator, including the radiator’s water supply temperature (T supply ) and its heating power (P rad ). The radiator performance is evaluated using the Logarithmic Mean Temperature Difference (LMTD) method, assuming a quasi-steady-state condition for the radiator at each time step. In the case of a bypass hybrid configuration, the bypass water flow is denoted as V by , the radiator water supply temperature is calculated from the mixing point according to the heat balance equation. Figure 2 (b) shows the temperature and flow distribution at each point during the heat release process of the packed bed phase change thermal storage device.

[0029] Then, by iteratively matching the P calculated by the two sets of equations rad value, derive T fd and T r , including water circulation flow (V rad ) and the overall heat transfer coefficient (UA rad ). a represents the heat sink index, which is usually between 1.2 and 1.3 and is set to 1.25 in this study.

[0030] In the present invention, during the entire heat release process of the packed bed phase change thermal storage device, as heat is released, T out Usually decreases gradually, leading to T supply and T return The corresponding decrease eventually causes T in In order to describe the thermal response of the radiator during the heat release process, the present invention has developed a transient inlet boundary simulation program for a packed bed phase change thermal storage device coupled with the real-time thermal performance of the radiator. The coupled calculation process is as follows: Figure 4 In each time step of the heat transfer simulation of the packed bed phase change thermal storage device, T in T obtained by iterative calculation of the heat sink model returnThe values ​​are determined; the instantaneous circulating water flow rate is extracted from the predefined flow curve. Therefore, the updated circulating water inlet temperature and flow rate will be used as boundary conditions for the next calculation time step. This calculation method allows the heat transfer simulation of the packed bed phase change thermal storage device to be performed using the transient inlet boundary conditions defined by the radiator operating conditions.

[0031] Optionally, in the user-side radiator numerical model, a method for calculating a transient inlet boundary of a packed bed phase change thermal storage device coupled with real-time thermal performance of the radiator includes: S1. According to the design operating parameters and circulating water flow curve of the packed bed phase change thermal storage device , calculate the output , ,in, is the inlet temperature of the packed bed phase change thermal storage device, is the outlet water temperature of the packed bed phase change thermal storage device; S2. According to , , indoor and outdoor temperature, total heat transfer coefficient, water circulation flow, calculate radiator heating temperature, logarithmic mean temperature difference; S3, calculated by two sets of equations , ; S4. Determine whether .01kW , if satisfied, output , If not satisfied, re-assume , repeat step S2; S5. Order = , update the circulating water flow curve ; S6. Determine whether t satisfies If satisfied, the calculation ends; if not satisfied, repeat step S01; Among them, t tot To calculate the total duration, calculate the system operation status during this time period.

[0032] The beneficial effects that the present invention can produce include: 1. The present invention discloses a heating system of an air source heat pump coupled with a packed bed phase change heat storage device. In the heat storage mode, a portion of the hot water generated by the heat pump will be directed to the packed bed phase change heat storage device. After exchanging heat with the phase change material (PCM), the water at the outlet of the packed bed phase change heat storage device will be mixed with another portion of the hot water from the heat pump and the return water from the radiator, and then transported to the radiator. In the heat release mode, part of the radiator return water is directed to the packed bed phase change heat storage device for heat recovery. The three-way flow controller can mix the warm water at the outlet of the packed bed phase change heat storage device with another portion of the radiator return water passing through the bypass pipeline in a specific proportion to maintain the preset radiator water supply temperature. This operating method can achieve efficient heat storage and greatly extend the effective heat release time, providing a more adaptable preferred solution for efficient utilization of air source heat pumps and thermal energy storage.

[0033] 2. The present invention discloses an operating method of a heating system of an air source heat pump coupled with a packed bed phase change thermal storage device. By optimizing the flow curve and adopting linear and parabolic growth circulating water flow curves, the purpose of ultimately increasing the effective heat release time of the packed bed phase change thermal storage device is achieved, improving the heat transfer efficiency in the phase change thermal storage process, and ensuring efficient and stable operation of the system under various working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 It is a schematic diagram of a heating system of an air source heat pump coupled with a packed bed phase change thermal storage device; Figure 2 Schematic diagram of the operation mode of the heating system of the air source heat pump coupled with the packed bed phase change thermal storage device, wherein (a) is the thermal storage mode and (b) is the thermal release mode; Figure 3 It is the calculation flow chart of the packed bed thermal storage system in the heating system of the air source heat pump coupled packed bed phase change thermal storage device; Figure 4 It is a calculation flow chart of the transient simulation program of the packed bed phase change thermal storage device coupled with the real-time thermal performance of the radiator in the heating system of the air source heat pump coupled packed bed phase change thermal storage device; Figure 5 It is seven different circulating water flow curves in the operation of the heating system of the air source heat pump coupled with the packed bed phase change thermal storage device heating system; Figure 6 It is the change of the inlet water temperature of the packed bed phase change thermal storage device under different flow curves during the operation of the heating system of the air source heat pump coupled with the packed bed phase change thermal storage device; Figure 7It is the change of outlet water temperature of packed bed phase change thermal storage device under different flow curves during the operation of air source heat pump coupled packed bed phase change thermal storage device heating system; Figure 8 It is the change of radiator water supply temperature under different flow curves during the operation of the heating system of the air source heat pump coupled with the packed bed phase change thermal storage device.

[0035] In the attached figure: 1. Air source heat pump; 2. Packed bed phase change heat storage device; 3. Radiator (radiator); 4. Branch; 5. First three-way mixing valve; 6. Second three-way mixing valve; 7. Third three-way mixing valve; 8. First water pump; 9. Second water pump; 10. Water supply pipeline; 11. Return pipeline. DETAILED DESCRIPTION

[0036] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0037] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0038] Example 1 like Figure 1 and Figure 2 As shown, this embodiment provides an air source heat pump coupled with a packed bed phase change thermal storage device heating system, comprising an air source heat pump 1, a packed bed phase change thermal storage device 2, and a radiator 3; the air source heat pump 1 and the packed bed phase change thermal storage device 2 are connected in series to form a thermal storage circulation loop (such as Figure 2 As shown in Figure (a), a water pump 8 is also provided on the water inlet pipeline of the packed bed phase change heat storage device 2, and the water pump 8 is located between the air source heat pump 1 and the packed bed phase change heat storage device 2; the packed bed phase change heat storage device 2 and the radiator 3 and the branch 4 pipeline form a heat release circulation loop (as shown in Figure 1). Figure 2 As shown in Figure (b), the packed bed phase change heat storage device 2 is connected in series with the radiator 3, the packed phase change heat storage device 2 is connected in parallel with the branch 4 pipeline, and a water pump 9 is also provided on the water supply pipeline 10 between the first three-way mixing valve 5 and the radiator 3.

[0039] The heating system comprises: a first three-way mixing valve 5 , a second three-way mixing valve 6 and a third three-way mixing valve 7 .

[0040] The first port of the first three-way mixing valve 5 is connected to the port I of the packed bed phase change heat storage device 2, the second port of the first three-way mixing valve 5 is connected to the water supply pipeline 10 of the radiator 3, and the third port of the first three-way mixing valve 5 is connected to the branch pipeline 4.

[0041] Port II-1 of the second three-way mixing valve 6 is connected to the outlet of the water pump 8, port II-2 of the second three-way mixing valve 6 is connected to port I of the packed bed phase change thermal storage device 2, and port II-3 of the second three-way mixing valve 6 is connected to the water inlet of the water pump 9; Port III-1 of the third three-way mixing valve 7 is connected to the inlet end of the air source heat pump 1, port III-2 of the third three-way mixing valve 7 is connected to port II of the packed bed phase change heat storage device 2, and port III-3 of the third three-way mixing valve 7 is connected to the return water pipe 11 of the radiator 3.

[0042] In this embodiment, the operation mode of the heating system is determined according to the weather and user needs, and there are the following two working modes: (1) Heat storage mode: When the electricity is at low peak, the air source heat pump 1 heats the circulating water to circulate and store heat in the packed bed phase change heat storage device 2 until it is full.

[0043] (2) Heat release mode: During peak heat usage, the heat energy stored in the packed bed phase change heat storage device 2 is used to heat the circulating water in the radiator 3. Part of the return water from the radiator 3 flows to the packed bed phase change heat storage device 2 for heat recovery. The outlet water flow of the packed bed phase change heat storage device 2 is mixed with another part of the return water from the radiator 3 through the branch 4 in a specific ratio by controlling the three-way mixing valve to maintain the required water supply temperature for the radiator under the current conditions.

[0044] Example 2 This embodiment provides an operation method of a heating system of an air source heat pump coupled with a packed bed phase change thermal storage device, comprising: Step S1: Establishing an air source heat pump coupled with a packed bed phase change thermal storage device heating system according to Example 1; Step S2: Establish a numerical model of the packed bed phase change thermal storage device and use the finite difference method to couple and solve it, such as Figure 3 shown.

[0045] Step S3: Establish a transient simulation numerical model of the packed bed phase change thermal storage device coupled with the real-time thermal performance of the radiator, and simulate and solve it, such as Figure 4 shown.

[0046] Step S4: using different circulating water flow curves to simulate the air source heat pump coupled packed bed phase change thermal storage device heating system, and analyzing the thermal performance of the system operation under different circulating water flow curves.

[0047] Example 3 The heat load of the heating system obtained in Example 1 was calculated, and the parameters related to the heat load calculation are listed in Table 1. The total heat transfer coefficient (UA) of the radiator system was calculated to be 0.56 kW / K, and the design water circulation flow rate (V total ) is constant at 3.38 m³ / h. Based on energy balance calculation, to maintain indoor thermal comfort (T room = 20℃), when the design outdoor temperature is -5℃, the residential heating load is 26.81 kW. At this time, the supply and return water temperatures of the radiator (T supply / T return ) were 45.7℃ and 38.9℃ respectively.

[0048] Table 1 Basic parameters of user-side heating

[0049] Example 4 Different circulating water flow curves are used to analyze the heat release performance of the heating system and optimize its thermal performance. The main purpose is to extend its effective heat release time. The heat release process of the packed bed phase change thermal storage device is simulated and analyzed. Table 2 shows the relevant parameters of the performance simulation experiment.

[0050] This embodiment studies seven different heat transfer fluid flow strategies, and the seven flow curve configurations are flow curves 0 to 6, such as Figure 5 As shown. Except for flow curve 0, the other six configurations (flow curves 1–6) are designed as time-increasing flow configurations to offset the effect of temperature drop during the heat release process of the packed bed thermal storage device. In flow curve 0, the baseline configuration keeps the flow rate fixed, V f is 1.859 m³ / h; while the flow configurations of flow curves 1 to 6 increase with time. Furthermore, flow curves 1, 5, and 6 increase from zero to V f The design of flow curves 2 to 4 takes into account that after 0.9 hours, V f The temperature at the outlet of the packed bed thermal storage device decreases significantly due to the heat exchange of the circulating water in the storage tank. In addition, flow curves 4 and 5 use a parabolic flow configuration that is different from other linear configurations.

[0051] Figure 6 , Figure 7 and Figure 8The packed bed thermal storage device inlet temperature, packed bed thermal storage device outlet temperature and radiator water supply temperature are shown respectively. Table 2 summarizes the heat release performance of the packed bed thermal storage system under different circulating water flow curves. Here, SOC refers to the heat storage state of the packed bed thermal storage device, which is calculated as the heat energy released during the effective heat release period divided by the total heat energy storage capacity. The results show that flow curves 2, 4, 5 and 6 can provide effective heat for more than 2 hours; the difference in effective heat release time among these four flow curves is not significant, at most 5%. Therefore, the SOC of these four configurations is higher (71.37% to 79.92%) because they have a longer effective heat release period. Compared with the baseline flow curve 0, the use of these four flow curves can extend the effective heat release period by about 172.5%. Flow curve 2 and flow curve 3 both use a step-linear flow configuration. Compared with flow curve 2, flow curve 3 has a lower SOC (42.1%) and a shorter effective heat release time (1.18 hours) because the circulating water flow rate in flow curve 3 increases slowly and the extracted heat energy (33.25 kWh) is less than that in flow curve 2 (61.97 kWh), resulting in a lower radiator water supply temperature. Flow curve 4 has better SOC and effective heat release time than flow curve 3 because the parabolic growth of the circulating water flow rate can maintain the radiator water supply temperature, thereby keeping the inlet temperature of the packed bed thermal storage device at the required temperature threshold for a long time.

[0052] Table 2 Basic parameters of user-side heating

[0053] In summary, the present invention specifically discloses an air source heat pump coupled packed bed phase change thermal storage device heating system and an operation method thereof. By optimizing the flow curve and adopting linear growth and parabolic growth circulating water flow curves, the purpose of ultimately increasing the effective heat release time of the packed bed phase change thermal storage device is achieved, improving the heat transfer efficiency in the phase change thermal storage process, and ensuring efficient and stable operation of the system under various working conditions.

[0054] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

[0055] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0056] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0057] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A heating system, characterized in that: The heating system comprises: Air source heat pump (1), packed bed phase change heat storage device (2), radiator (3); The air source heat pump (1) and the packed bed phase change heat storage device (2) are connected in series to form a heat storage circulation loop; The packed bed phase change heat storage device (2) and the radiator (3) are connected in series to form a heat release circulation loop; A branch pipeline (4) is also provided in the heat release circulation loop; the branch pipeline (4) is connected in parallel with the packed bed phase change heat storage device (2).

2. The heating system according to claim 1, characterized in that: The heating system further comprises: a first three-way mixing valve (5); a first port of the first three-way mixing valve (5) is connected to port I of the packed bed phase change heat storage device (2), a second port of the first three-way mixing valve (5) is connected to a water supply pipeline of the radiator (3), and a third port of the first three-way mixing valve (5) is connected to a pipeline of the branch (4).

3. The heating system according to claim 1, characterized in that: The heating system further comprises: A second three-way mixing valve (6) and a third three-way mixing valve (7); Port II-1 of the second three-way mixing valve (6) is connected to the outlet end of the air source heat pump (1), port II-2 of the second three-way mixing valve (6) is connected to port I of the packed bed phase change heat storage device (2), and port II-3 of the second three-way mixing valve (6) is connected to the water supply pipeline of the radiator (3); Port III-1 of the third three-way mixing valve (7) is connected to the inlet end of the air source heat pump (1), port III-2 of the third three-way mixing valve (7) is connected to port II of the packed bed phase change heat storage device (2), and port III-3 of the third three-way mixing valve (7) is connected to the return water pipeline of the radiator (3).

4. The heating system according to any one of claims 1 to 3, characterized in that: The heating system comprises: In a heat storage mode, when the electricity is off-peak, the air source heat pump (1) and the packed bed phase change heat storage device (2) form a heat storage circulation loop, and the circulating water is heated to circulate heat in the packed bed phase change heat storage device (2); and heat release mode, when in peak heat usage, the packed bed phase change heat storage device (2) and the radiator (3) and the branch (4) pipeline form a heat release circulation loop, wherein the packed bed phase change heat storage device (2) and the radiator (3) are connected in series, and the packed bed phase change heat storage device (2) and the branch (4) pipeline are connected in parallel; the heat energy in the packed bed phase change heat storage device (2) heats the circulating water in the radiator (3).

5. The method for operating a heating system according to any one of claims 1 to 4, characterized in that: The operation method comprises: Establish a heating device of an air source heat pump coupled with a packed bed phase change thermal storage device, wherein the heating device is selected from the heating system according to any one of claims 1 to 4; Establish a numerical model of packed bed phase change thermal storage device; Establish a numerical model of user-side radiator; The heating equipment of the air source heat pump coupled with the packed bed phase change thermal storage device operates according to the circulating water flow curve solved by the numerical model of the packed bed phase change thermal storage device and the numerical model of the user-side radiator.

6. The operating method according to claim 5, characterized in that: The numerical model of the packed bed phase change heat storage device is a one-dimensional transient cycle heat storage mathematical model established by a concentric diffusion model.

7. The operating method according to claim 5, characterized in that: In the numerical model of the packed bed phase change thermal storage device, the energy control equation of the circulating water is: In the formula, is the porosity of the packed bed, is the heat transfer fluid density, is the specific heat capacity of the heat transfer fluid, is the temperature of the heat transfer fluid, is the flow rate of the heat transfer fluid, is the thermal conductivity of the heat transfer fluid, is the bulk heat transfer coefficient between the heat transfer fluid and the phase change capsule, is the radial direction of the phase change capsule, is the axial direction of the packed bed, , are the inner and outer radii of the phase change capsule, is the viscosity of the heat transfer fluid, and represent the Reynolds number and Prandtl number of the packed bed, respectively; In the numerical model of the packed bed phase change thermal storage device, the energy control equation of the phase change material is: In the formula, is the density of phase change material, is the specific enthalpy of the phase change material, is the effective thermal conductivity of the phase change material, is the solid-state specific heat capacity of the phase change material, is the liquid specific heat capacity of the phase change material, is the phase change enthalpy of the phase change material, is the melting temperature of the phase change material, is the solidification temperature of the phase change material, is the solid-state thermal conductivity of the phase change material, is the liquid thermal conductivity of the phase change material; In the numerical model of the packed bed phase change thermal storage device, the boundary conditions are: In the formula, is the initial temperature of the system, is the packed bed inlet temperature, is the packed bed outlet temperature, is the heating power of the system, is the packed bed height.

8. The operating method according to claim 5, characterized in that: In the user-side radiator numerical model, the radiator performance is calculated using the logarithmic mean temperature difference method, the heating power of the radiator is calculated through iterative matching, and the radiator heating temperature and return water temperature are derived.

9. The operating method according to claim 5, characterized in that: The numerical model of the user-side radiator is: In the formula, is the flow rate of circulating water in the packed bed, is the outlet water temperature of the packed bed, is the flow rate of circulating water in the radiator, is the flow rate of circulating water in the bypass, is the heating power of the radiator, The heating temperature of the radiator, is the return water temperature, is the radiator index, =1.2~1.3, is the logarithmic mean temperature difference.

10. The operating method according to claim 9, characterized in that: In the user-side radiator numerical model, the calculation method of the transient inlet boundary of the packed bed phase change thermal storage device coupled with the real-time thermal performance of the radiator includes: S1. According to the design operating parameters and circulating water flow curve of the packed bed phase change thermal storage device , calculate the output , ,in, is the inlet temperature of the packed bed phase change thermal storage device, is the outlet water temperature of the packed bed phase change thermal storage device; S2. According to , , indoor and outdoor temperature, total heat transfer coefficient, water circulation flow, calculate radiator heating temperature and logarithmic mean temperature difference; S3, calculated by two sets of equations , ; S4. Determine whether .01kW , if satisfied, output , If not satisfied, re-assume , repeat step S2; S5. Order = , update the circulating water flow curve ; S6. Determine whether t satisfies If satisfied, the calculation ends; if not satisfied, repeat step S01.

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