Refrigeration and heating integrated system based on phase change heat storage and control method

Abstract

The invention relates to the technical field of heat energy storage and heating, and provides a refrigeration and heating integrated system based on phase change heat storage and a control method, the refrigeration and heating integrated system comprises a solar heat collection module, a heat storage oil tank, a phase change heat storage module, an absorption refrigeration module, a heating and heat supplementing module and a multi-mode control module; the multi-mode control module is used for controlling the phase change heat storage module to store heat in a heating period in response to the valley electricity time; monitoring the temperature of a heat storage oil tank in response to the non-valley electricity time, switching a heat supply mode of the system based on a comparison result of the temperature of the heat storage oil tank and a set threshold value, and controlling the phase change heat storage module to store heat or driving the absorption type refrigeration module to refrigerate in response to triggering of a user cold load demand in a cold supply period; and in response to the situation that the user cold load demand is not triggered, the heating and heat supplementing module is controlled to supplement heat to the phase change heat storage module. By integrating solar heat collection, phase change heat storage and valley electricity heat compensation strategies, efficient utilization and multi-source cooperative energy supply of clean energy are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal energy storage and heating, and in particular to a solar absorption cooling and heating integrated system and method based on phase change heat storage. Background Art

[0002] The global energy system's long-term reliance on fossil fuels has led to a surge in carbon emissions and environmental degradation. Studies have shown that heating and cooling consume one-sixth of global fossil electricity generation, with coal-fired heating in northern China creating even greater pressure on both energy and the environment. In this context, solar absorption cooling systems have become a strategic breakthrough, as they can reduce air conditioning energy consumption by 80% and support a multi-energy, complementary energy network. Research has achieved breakthroughs in efficiency mechanisms, climate adaptability, and dynamic modeling through collector-refrigerator coupling optimization. However, further work is needed to address the challenges of coordinated multi-energy regulation.

[0003] Solar heating overcomes the bottleneck of intermittency through phase-change thermal storage technology. Research shows that integrated PCM can increase solar energy utilization by 30% and thermal efficiency by 40%. Combined with heat pump systems, it can achieve electricity savings of 42%-67%. In extreme scenario optimization, new PCMs such as fatty acid / inorganic salt hydrates demonstrate stability in the temperature range of -20°C to 100°C. Nano-enhanced materials enable thermal storage system efficiency of 50%. Composite PCMs reduce tank volume by 43% and increase solar energy utilization by 4.2%. Regarding synergistic strategies, a photovoltaic-valley power system achieves 47% daily electricity savings in winter through time-of-use regulation, providing a distributed solution for energy transition in rural areas of northern China. These breakthroughs signal that solar technology is making a critical leap from theoretical verification to engineering application through material innovation and system integration.

[0004] Despite the progress made, existing research still has significant limitations: (1) Most studies focus on centralized energy supply at the community level, lacking miniaturized system designs for rural single-family households; (2) The dynamic matching mechanism between thermal storage units, collectors, and chillers is not yet clear; (3) Control strategy research lags behind, failing to effectively coordinate the timing of multi-source energy supply and temperature thresholds. For example, traditional control logic often leads to incomplete charging and discharging of PCMs, resulting in low thermal efficiency; (4) Economic analysis often ignores the characteristics of rural scenarios, such as time-of-use electricity price response and equipment maintenance costs.

[0005] Therefore, how to focus on setting up small-scale heating and cooling systems for single-family households and improve the dynamic matching mechanism, control strategy and economic cost of heating and cooling has become a technical problem that needs to be solved urgently. Summary of the Invention

[0006] In view of this, the main purpose of the present invention is to provide a phase change heat storage solar absorption cooling and heating integrated method and system, aiming to at least solve the above-mentioned problems.

[0007] To achieve the above objectives, in a first aspect, the present invention provides an integrated cooling and heating system based on phase change heat storage, the system comprising: a solar thermal collection module, a heat storage tank, a phase change heat storage module, an absorption refrigeration module, a heating supplementary heat module and a multimodal control module; the solar thermal collection module is connected to the heat storage tank, the phase change heat storage module is respectively connected to the heat storage tank, the solar thermal collection module, the absorption refrigeration module and the heating supplementary heat module, and the solar thermal collection module, the phase change heat storage module, the heat storage tank, the absorption refrigeration module and the heating supplementary heat module transfer heat through heat transfer oil; the solar thermal collection module is used to collect solar energy and convert it into heat energy, which is output to the heat storage tank, the phase change heat storage module and the heating terminal module respectively; the phase change heat storage module is used to store the heat delivered by the solar thermal collection module and supply heat to the solar thermal collection module; the absorption refrigeration module is used to output cooling capacity to the building unit; and the heating supplementary heat module is used to supplement heat to the phase change heat storage module;

[0008] The multimodal control module is used to: during the heating period, in response to the time being off-peak time, control the phase change thermal storage module to store heat; in response to the time being non-off-peak time, monitor the temperature of the thermal storage oil tank, and switch the system's heating mode based on the comparison result of the thermal storage oil tank temperature with a set threshold value. The heating modes include: a mixed heating mode of the solar thermal collection module and the phase change thermal storage module and an independent heating mode of the phase change thermal storage module; during the cooling period, in response to the user's cooling load demand being triggered, control the phase change thermal storage module to store heat or drive the absorption refrigeration module to cool; in response to the user's cooling load demand not being triggered, control the heating heat supplement module to supplement heat to the phase change thermal storage module.

[0009] In the second aspect, the present invention provides a control method for a cooling and heating integrated system based on phase change heat storage, including the cooling and heating integrated system based on phase change heat storage disclosed in the first aspect, the method comprising the following steps: S1, during the heating period, judging whether the time is off-peak time or non-off-peak time, and switching the heating mode of the system according to the time judgment result; S101, if the time is off-peak time, controlling the phase change heat storage module to store heat; S102, if the time is non-off-peak time, monitoring the temperature of the heat storage oil tank, and switching the system based on the comparison result of the heat storage oil tank temperature with the set threshold value. The heating mode of the system includes: a mixed heating mode of the solar thermal collection module and the phase change heat storage module and an independent heating mode of the phase change heat storage module; S2, during the cooling period, determines whether the user's cooling load demand is triggered, and switches the system to the cooling mode or the heating supplement mode according to the demand determination result; S201, during the cooling period, determines that the user's cooling load demand is triggered, controls the phase change heat storage module to store heat or drives the absorption refrigeration module to cool; S202, during the cooling period, determines that the user's cooling load demand is not triggered, and controls the heating supplement module to supplement heat to the phase change heat storage module.

[0010] In the technical solution provided by the present invention, a solar absorption-type combined cooling and heating system based on phase change heat storage is constructed to meet the energy supply needs of single-family buildings in rural areas. By integrating solar thermal collection, phase change heat storage and valley electricity heating strategies, efficient utilization of clean energy and multi-source collaborative energy supply are achieved. Based on the year-round dynamic simulation and meteorological data analysis of the TRNSYS platform, the system has achieved remarkable results in technological breakthroughs, energy efficiency improvement and economic optimization. Under typical extreme weather conditions, the system maintains the continuity and stability of energy supply through valley electricity heating and multi-source cascade heat exchange mechanisms. The present invention fills the research gap in rural single-family miniaturized energy supply systems and solves the problems of unclear dynamic matching mechanism between heat storage units and collectors and lagging control strategies in existing achievements. Compared with centralized energy supply systems, SPCMS provides a replicable technical paradigm for rural energy transformation through distributed architecture and multi-modal control strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] 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.

[0012] Figure 1 This is a perspective diagram of the independent single-story building effect disclosed in the embodiment of this application;

[0013] Figure 2 This is a schematic diagram of the global horizontal irradiance and direct normal irradiance disclosed in the embodiments of this application.

[0014] Figure 3 A schematic diagram of the ambient dry-bulb temperature and relative humidity disclosed in the embodiments of this application;

[0015] Figure 4 Schematic diagram of annual hourly and monthly heating and cooling loads disclosed in the embodiments of this application;

[0016] Figure 5 A schematic diagram of a solar energy and PCM combined cooling and heating system disclosed in an embodiment of the present application;

[0017] Figure 6 Schematic diagram of the solar energy and PCM combined cooling and heating simulation system disclosed in the embodiment of this application;

[0018] FIG7( a ) is a schematic diagram of a heating system strategy of a heating and cooling system according to an embodiment of the present application;

[0019] FIG7( b ) is a schematic diagram of a cooling system strategy of a logic heating and cooling system disclosed in an embodiment of the present application;

[0020] FIG8 is a schematic diagram of the temperature and energy of the heating system on February 25 disclosed in an embodiment of the present application;

[0021] FIG9( a ) is a schematic diagram of the temperature and energy of the heating system on December 12, according to an embodiment of the present application;

[0022] FIG9( b ) is a second schematic diagram of the temperature and energy of the heating system on December 12 disclosed in an embodiment of the present application;

[0023] FIG10( a ) is a schematic diagram showing temperature changes of a refrigeration system over 72 hours according to an embodiment of the present application;

[0024] FIG10( b ) is a second schematic diagram of the temperature change of the refrigeration system disclosed in an embodiment of the present application over 72 hours;

[0025] FIG10( c ) is a third schematic diagram of the temperature change of the refrigeration system disclosed in the embodiment of the present application over 72 hours;

[0026] FIG11( a ) is a schematic diagram showing temperature changes of a refrigeration system over 72 hours when a boiler is in operation according to an embodiment of the present application;

[0027] FIG11( b ) is a second schematic diagram of the temperature change of the refrigeration system over 72 hours when the boiler is running according to an embodiment of the present application;

[0028] FIG11( c ) is a third schematic diagram of the temperature change of the refrigeration system during 72 hours when the boiler is running according to an embodiment of the present application;

[0029] FIG12( a ) is a schematic diagram showing the thermal change results of the refrigeration system during 72 hours of boiler operation according to an embodiment of the present application;

[0030] FIG12( b ) is a schematic diagram of the thermal change results of the boiler-less refrigeration system for 72 hours disclosed in an embodiment of the present application;

[0031] FIG13( a ) is a schematic diagram of daily operation data of a PCM storage tank in winter disclosed in an embodiment of the present application;

[0032] FIG13( b ) is a schematic diagram of daily operation data of a PCM storage tank in summer disclosed in an embodiment of the present application;

[0033] Figure 14 This is a schematic diagram of the monthly energy share and solar energy share SFn disclosed in the embodiments of this application;

[0034] Figure 15 A schematic diagram of the annual system heat share disclosed in an embodiment of the present application;

[0035] FIG16( a ) is a schematic diagram of power variation during the winter operating season disclosed in an embodiment of the present application;

[0036] FIG16( b ) is a schematic diagram of power variation during the summer operating season disclosed in an embodiment of the present application;

[0037] Figure 17 A schematic diagram of the ratio of system power and cost disclosed in an embodiment of the present application;

[0038] FIG18( a ) is a schematic diagram of seasonal cost changes in winter operation disclosed in an embodiment of the present application;

[0039] FIG18( b ) is a schematic diagram of seasonal cost changes in summer operation disclosed in an embodiment of the present application;

[0040] Figure 19 This is a flow chart of a control method for an integrated cooling and heating system based on phase change heat storage disclosed in an embodiment of the present application;

[0041] Figure 20 This is a module diagram of the control system of the integrated cooling and heating system based on phase change heat storage disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0042] 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.

[0043] 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.

[0044] 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.

[0045] Embodiment 1: To achieve the above-mentioned purpose, the embodiment of the present invention provides an integrated cooling and heating system based on phase change heat storage, the system comprising: a solar thermal collection module, a heat storage tank, a phase change heat storage module, an absorption refrigeration module, a heating supplementary heat module and a multimodal control module; the solar thermal collection module is connected to the heat storage tank, the phase change heat storage module is respectively connected to the heat storage tank, the solar thermal collection module, the absorption refrigeration module and the heating supplementary heat module, and the solar thermal collection module, the phase change heat storage module, the heat storage tank, the absorption refrigeration module and the heating supplementary heat module transfer heat through heat transfer oil; the solar thermal collection module is used to collect solar energy and convert it into heat energy, which is output to the heat storage tank, the phase change heat storage module and the heating terminal module respectively; the phase change heat storage module is used to store the heat transmitted by the solar thermal collection module and supply heat to the solar thermal collection module; the absorption refrigeration module is used to output cooling capacity to the building unit; the heating supplementary heat module is used to supplement heat to the phase change heat storage module;

[0046] The multimodal control module is used to: during the heating period, in response to the time being off-peak time, control the phase change thermal storage module to store heat; in response to the time being non-off-peak time, monitor the temperature of the thermal storage oil tank, and switch the system's heating mode based on the comparison result between the thermal storage oil tank temperature and the set threshold value. The heating modes include: a mixed heating mode of the solar thermal collection module and the phase change thermal storage module and an independent heating mode of the phase change thermal storage module; during the cooling period, in response to the user's cooling load demand being triggered, control the phase change thermal storage module to store heat or drive the absorption refrigeration module to cool; in response to the user's cooling load demand not being triggered, control the heating heat supply module to supply heat to the phase change thermal storage module.

[0047] In some embodiments, the system further comprises a first oil pump and a second oil pump, the first oil pump being connected in series with the circuits where the solar thermal collection module and the heat storage oil tank are located, respectively, and the second oil pump being connected in series with the circuits where the heating and heat supplement module and the phase change heat storage module are located, respectively; during the heating period, in response to the time being the valley time, the phase change heat storage module is controlled to store heat as follows: during the heating period, in response to the time being the valley time, the first oil pump is turned off and the second oil pump is started, the heating and heat supplement module is controlled to start heating the heat transfer oil to 43°C±2°C, the second oil pump is turned on to store and release heat to the phase change heat storage module, and at the same time, the latent heat storage of the phase change heat storage module is matched with the building load to release heat. In some embodiments, the system includes a first valve and a second valve, the first valve being connected in series to a series circuit including a thermal storage tank, a phase change thermal storage module, and a solar thermal collection module, and the second valve being connected in series to a series circuit including a thermal storage tank and a phase change thermal storage module; in response to a non-valley time, the temperature of the thermal storage tank is monitored, and based on a comparison result between the thermal storage tank temperature and a set threshold, the system's heating mode is switched, the heating modes including: a mixed heating mode of a solar thermal collection module and a phase change thermal storage module and an independent heating mode of a phase change thermal storage module: in response to a non-valley time, the temperature of the thermal storage tank is monitored to be less than a set threshold and greater than 30°C±2°C, the first valve is switched to the series connection between the solar thermal collection module and the phase change thermal storage module, and the solar thermal collection module and the phase change thermal storage unit are controlled to be connected in series for heating; in response to a non-valley time, the temperature of the thermal storage tank is monitored to be less than 30°C±2°C, the first oil pump is turned off, and the second valve is controlled to switch to the phase change thermal storage module circuit, and the phase change thermal storage module is independently heated.

[0048] In some embodiments, the system includes a heating terminal module and a third valve. The heating terminal module is respectively connected to the solar thermal collection module, the thermal storage tank and the phase change thermal storage module. The heating terminal module is used to supply heat to the building unit. The third valve is connected in series with the circuit where the solar thermal collection module, the heating terminal module and the phase change thermal storage module are located. In response to the time being non-off-peak time, the temperature of the thermal storage tank is monitored, and the heating mode of the system is switched based on the comparison result between the thermal storage tank temperature and the set threshold. It also includes: in response to the time being non-off-peak time, if the thermal storage tank temperature is greater than or equal to the set threshold, the third valve is switched to the direct power supply circuit of the solar thermal collection module, the solar thermal collection module is controlled to preferentially supply heat to the heating terminal module, and the surplus heat is stored in the phase change thermal storage unit.

[0049] In some embodiments, the system includes a third oil pump, a first water pump, a second water pump, a fourth valve and an oil-water heat exchange module; the oil-water exchange module is connected to the phase change heat storage module and the absorption refrigeration module respectively; the absorption refrigeration module is connected to the oil-water exchange module and the heating and heat supplement module respectively; the third oil pump is connected in series with the circuit where the phase change heat storage unit and the oil-water exchange module are located, the first water pump is connected in series with the oil-water exchange module and the absorption refrigeration module are located, the second water pump is connected in series with the absorption refrigeration module and the heating and heat supplement module are located, and the fourth valve is connected in series with the oil-water exchange module and the absorption refrigeration module; During the cooling period, in response to the user's cooling load demand being triggered, the phase change heat storage module is controlled to store heat or drive the absorption refrigeration module to cool as follows: in response to the user's cooling load demand being triggered and the temperature of the phase change heat storage module being greater than the rated driving threshold of the absorption refrigeration module, the third oil pump and the first water pump are turned on to exchange heat with the phase change heat storage module, drive the absorption refrigeration module to work, and turn on the second water pump to maintain the cooling cycle; in response to the user's cooling load demand being triggered and the temperature of the phase change heat storage module being less than or equal to the rated driving threshold of the absorption refrigeration module, the first water pump is turned on and the fourth valve is switched to control the heating and heat supplement module to assist in heating.

[0050] In some embodiments, the system includes a fifth valve connected in series with the circuit containing the solar thermal collection module and the thermal storage tank. In response to the user's cooling load demand not being triggered, the system controls the heating module to supply heat to the phase change thermal storage module by: switching the fifth valve to the phase change thermal storage module circuit, activating the first oil pump, and controlling the phase change thermal storage module to be connected in series with the thermal storage tank to store heat. In some embodiments, the system further includes: switching the fifth valve to the thermal storage circuit between the solar thermal collection module and the phase change thermal storage module, activating the phase change thermal storage module to complete sensible and latent coupled heat storage, in response to the outlet temperature of the solar thermal collection module exceeding the phase change threshold of the phase change thermal storage module.

[0051] Embodiment 2: To achieve the above-mentioned purpose, the embodiment of the present invention provides a control method for a cooling and heating integrated system based on phase change heat storage, including the cooling and heating integrated system based on phase change heat storage disclosed in the above-mentioned embodiment 1, the method comprising the following steps: S1, during the heating period, judging whether the time is off-peak time or non-off-peak time, and switching the heating mode of the system according to the time judgment result; S101, if the time is off-peak time, controlling the phase change heat storage module to store heat; S102, if the time is non-off-peak time, monitoring the temperature of the heat storage tank, and based on the comparison result of the heat storage tank temperature with the set threshold value, switching the heating mode of the system according to the time judgment result; , switching the system's heating mode, the heating modes include: a mixed heating mode of a solar thermal collection module and a phase change heat storage module, and an independent heating mode of a phase change heat storage module; S2, during the cooling period, determining whether the user's cooling load demand is triggered, and switching the system to a cooling mode or a heating supplement mode based on the demand determination result; S201, during the cooling period, determining that the user's cooling load demand is triggered, controlling the phase change heat storage module to store heat or driving the absorption refrigeration module to cool; S202, during the cooling period, determining that the user's cooling load demand is not triggered, controlling the heating supplement module to supplement heat to the phase change heat storage module. In some embodiments, S101 is specifically:

[0052] During the heating period, if it is off-peak time, the first oil pump is turned off and the second oil pump is turned on. The heating and supplementary heat module is controlled to start heating the thermal oil to 43°C ± 2°C. The second oil pump is turned on to store and release heat to the phase change heat storage module. At the same time, the latent heat stored in the phase change heat storage module is matched with the building load for heat release. S102 is specifically as follows:

[0053] During the heating period, the time is determined to be non-off-peak time, and the temperature of the thermal storage tank is monitored. If the temperature of the thermal storage tank is lower than the set threshold and greater than 30°C ± 2°C, the first valve is switched to connect the solar thermal collection module and the phase change thermal storage module in series, and the solar thermal collection module and the phase change thermal storage unit are controlled to supply heat in series;

[0054] During the heating period, the time is determined to be non-off-peak hours, and the temperature of the thermal storage tank is monitored. If the temperature of the thermal storage tank is less than 30°C ± 2°C, the first oil pump is turned off, and the second valve is controlled to switch to the phase change thermal storage module circuit, and the phase change thermal storage module independently provides heat. In some embodiments, S201 is specifically as follows:

[0055] During the cooling period, if the user's cooling load demand is triggered and the temperature of the phase-change thermal storage module is greater than the rated driving threshold of the absorption refrigeration module, the third oil pump and the first water pump are turned on to exchange heat with the phase-change thermal storage module, driving the absorption refrigeration module to work, and the second water pump is turned on to maintain the cooling cycle;

[0056] During the cooling period, if the user's cooling load demand is triggered and the temperature of the phase change heat storage module is less than or equal to the rated driving threshold of the absorption refrigeration module, the first water pump is turned on and the fourth valve is switched to control the heating supplement module to assist in heating. S202 is specifically as follows:

[0057] During the cooling period, if the user's cooling load demand is not triggered, the fifth valve is switched to the phase change thermal storage module circuit, the first oil pump is turned on, and the phase change thermal storage module is controlled to be connected in series with the thermal storage tank to store heat.

[0058] Example 3: To achieve the above objectives, the present invention provides a solar absorption cooling and heating integrated system (SPCMS) based on phase change heat storage. The following innovative work is carried out for rural single-family households: (1) modular heat storage units are constructed, using paraffin wax / expanded graphite composite PCM (phase change temperature 37℃ / 109.4℃), and spiral tubes are used to enhance heat transfer and improve thermal conductivity; (2) a multi-modal control strategy is designed, coupling the time-of-use electricity price mechanism with irradiation matching to achieve adaptive switching between valley electricity storage and solar time-shifted energy supply; (3) a full-year dynamic simulation model is established, combined with Zhengzhou rural meteorological data, to quantify the energy supply reliability of the system under extreme weather conditions; (4) a full life cycle operation cost analysis is carried out. Through actual operation tests, the system is verified to be feasible in reducing grid dependence (electricity consumption in the cooling season accounts for less than 0.4%) and increasing renewable energy penetration (solar energy accounts for 53.7% in the heating season), providing theoretical support and technical paradigms for rural clean energy supply.

[0059] Regarding the system overview and building description, the model features a total heating area of 76 square meters and a floor height of 3.5 meters (excluding suspended ceilings). The single-story building is divided into a single thermal zone, with only the overall heating area considered. Based on the existing building dimensions, the building geometry was modeled using SketchUp software combined with the TRNSYS3D plug-in. The building model allows for evaluation of shading and radiation effects on walls and windows. Figure 1This is a rendering of a standalone single-story building. The geometric model was imported into the TRNSYS platform to calculate hourly heating and cooling loads over a one-year period. The model simulation also considers the impact of the building structure on the house, and the thermal characteristics of the building envelope are listed in Table 1. The thermal performance parameters of the single-story building envelope are described in Table 2 and meet the GB55015-2021 "General Specification for Energy Conservation and Renewable Energy Utilization in Buildings." Meteorological conditions were obtained from the Meteonorm international database. Based on the environmental conditions, a detailed dynamic simulation was performed in conjunction with TRNSYS18 to determine the hourly heating and cooling loads for the entire single-story building throughout the year. In the simulation study, the entire building's radiant floor system consists of 16 / 18mm diameter PEX pipes embedded between two layers of concrete. The floor surface is covered with a 0.01m thick layer of ceramic tiles, while the bottom is laid with a 0.08m thick layer of expanded polystyrene (EPS) to effectively reduce heat loss to the ground. The characteristics of the embedded PEX pipe are: thermal conductivity of 1.62 kJ / h·m·K, pipe spacing of 0.2 m, pipe outer diameter of 0.018 m, pipe inner diameter of 0.016 m, liquid specific heat capacity of 4.19 kJ / kg·K. Except for the thermal conductivity, all other parameters are the TRNSYS default values.

[0060]

[0061] Table 1: Description of building structure parameters

[0062]

[0063]

[0064] Table 2: U-value of single-storey buildings [W / ㎡·K]

[0065] Regarding environmental data analysis: This single-story building has relatively abundant solar energy resources and belongs to the third category of areas. The annual direct normal irradiance is equal to 719.94kWh / m 2 , the annual diffuse horizontal irradiance is equal to 875.29kWh / m 2 ,like Figure 2 shown. Figure 3The ambient dry-bulb temperature and relative humidity for each hour throughout the year are shown. The temperature fluctuates significantly in the seasons, with the highest reaching 39.05°C and the lowest reaching -8.8°C, while the relative humidity is relatively stable. According to the building model above, heating is required to keep the room temperature at 20°C and cooling at 24°C. Taking into account that the actual cooling use of rural users is generally during the high temperature period during the day (12:00-16:00) and the rest period at night (18:00-21:00), the cooling time in the study is determined to be 11:00-19:00. This is because the temperature is relatively low at night, the air conditioning usage time is shorter, and it can also save electricity costs. By dynamically simulating the building's thermal behavior every hour throughout the year, the heating and cooling loads for one year (the sum of the sensible heat and latent heat cooling loads) can be obtained, such as Figure 4 The bar chart shows seasonal variations in heating and cooling loads, while the fluctuation chart reflects daily trends influenced by solar radiation and ambient temperature. Peak and annual values for the building's heating and cooling loads are as follows: peak heating load is 2.15 kW, peak cooling load is 4.90 kW, and total load peak load is 7.05 kW. Annual heating load is 2961.92 kWh, annual cooling load is 2432.72 kWh, and total load is 5394.64 kWh. The heating and cooling cycle, established based on residents' general needs, provides heating for 121 days and cooling for 118 days. Cooling can be turned off or on based on actual demand.

[0066] Regarding the system modeling and detailed information in TRNSYS: In view of the characteristics of heating and cooling demand of rural single-family houses, this paper proposes a multi-source coupled solar energy supply system (SPCMS) based on phase change thermal storage. The system operates in coordination with solar collectors (SC) and electric thermal storage units (ETS). The system diagram is as follows: Figure 5 As shown: During the day, solar energy preferentially heats the phase-change thermal storage module, while excess heat is stored in the oil tank, providing short-term, stable heating. The phase-change storage tank releases heat during periods of insufficient radiation, ensuring stable heating. At night, secondary energy storage is achieved during the off-peak hours of the ETS, achieving thermal and electrical decoupling. The load network distributes this stored low-temperature thermal energy as needed to heating terminals in winter or drives absorption chillers in summer to generate 7-12°C chilled water for cooling.

[0067] Regarding solar heating systems: Aiming at the energy supply needs of rural single-family houses, this paper constructs a solar-phase change thermal storage coupled heating system based on the TRNSYS platform ( Figure 6The core of the system consists of a TESS-71 solar collector (parameters: area 45 m2, number of collectors 15, fluid specific heat 1.67 kJ / kg·K, interception efficiency 0.7, collector inclination 35°), a 156 insulated thermal storage tank, a 512 plate-type oil-water heat exchanger, a 700 electric boiler, and a phase-change thermal storage unit. The operating logic is as follows: During the day, the solar collector transfers heat energy to the thermal storage tank via a thermal oil circulation system. When the monitoring module detects that the tank temperature is ≥50°C (adjustable threshold), the terminal radiant heating network prioritizes heat conversion. Excess heat is stored across time periods using phase-change material (paraffin-based composite PCM, phase change temperature 37°C). In low-irradiance conditions or during nighttime operation, the control system automatically switches to the phase-change thermal storage unit for power supply, while simultaneously activating the electric boiler (operating during off-peak hours) to supplement the heat source, ensuring heating reliability and maintaining the indoor temperature within the designed range of 20±2°C.

[0068] Regarding the single-effect absorption cooling system: the system integrates TESS library 107 single-effect absorption chiller (1S-ABS), 510 closed cooling tower and phase change heat storage unit to form a solar-driven combined cooling and heating chain ( Figure 6 During the day, the solar collector preferentially heats the PCM thermal storage unit to the drive temperature (90°C). This heat is then circulated through the heat medium to provide heat for the 1S-ABS (single-stage absorption chiller) (rated COP = 0.7), generating 7-12°C chilled water for delivery to the terminal. When the PCM thermal storage temperature is below 90°C and the load demand is not met, an electric boiler (thermal efficiency ≥ 90%) is activated for auxiliary heating, ensuring stable cooling output (room temperature 26±2°C). The 510 cooling tower uses flow control to efficiently dissipate condensation heat while recovering some waste heat for preheating domestic hot water, improving system energy efficiency. The absorption chiller parameters are as follows: rated cooling capacity 11kW, COP 0.7, hot water inlet temperature 88°C, cooling water inlet temperature 31°C, chilled water inlet temperature 15°C, chilled water outlet temperature 10°C, maximum hot water flow rate 4250kg / h, maximum cooling water flow rate 9180kg / h, and maximum chilled water flow rate 2770kg / h.

[0069] Regarding the description of the heat storage unit: As the core component of the system simulation, this paper uses the 1334 phase change tank model (the specific information is as follows: the tank volume is 0.5m 3, box height 1m, bottom circumference 2.51m, fluid specific heat 2kJ / kg·K, heat exchanger efficiency 0.9, heat exchanger fluid specific heat 1.67kJ / kg·K, phase change latent heat 215 / 262kJ / kg, initial temperature 45 / 110℃, phase change temperature 37 / 109.4℃, top heat loss coefficient 0.08W / ㎡·K, edge heat loss coefficient 0.08W / ㎡·K, bottom heat loss coefficient 0.08W / ㎡·K), its structure is a flat-bottomed cylindrical constant volume storage tank with a built-in immersed spiral tube heat exchanger. The tank is filled with solid-liquid phase change material (PCM), and a heat transfer fluid (HTF) circulates in the heat exchanger. The model is constructed based on the following assumptions: Quasi-isothermal assumption: The PCM in the tank has a high Biot number (B i >0.1) interface, ignoring the internal temperature gradient, and equivalent to a lumped parameter model; Heat exchanger simplification: using a one-dimensional radial heat transfer model, ignoring axial heat conduction, and only considering the radial heat flow between the tube wall and the PCM; Fluid physical property consistency: HTF inlet physical property parameters (density ρ htf Specific heat capacity Cp htf ) maintains dynamic thermal equilibrium with the HTF in the storage tank, avoiding the complexity of two-phase flow. The heat transfer process can be summarized as follows. The main function of the phase change storage system is to exchange heat between the heat transfer fluid (HTF) and the phase change material at the phase change temperature. The heat transfer rate from the heat flowing into the heat exchanger to the storage tank can be expressed as:

[0070]

[0071] When there is no heat flow, there is no heat transfer in the immersion heat exchanger. The outlet temperature of the heat exchanger can be expressed as:

[0072] Where, is the inlet mass flow rate into the tank, Cp hx is the specific heat of the heat exchanger fluid, T in,hx is the temperature of the fluid entering the immersion heat exchanger, T out,hx is the temperature of the fluid leaving the immersion heat exchanger, T tank Tank temperature. In the two-phase region, the solution to the energy balance is slightly different because the temperature of the fluid does not change. Instead, we see an increase or decrease in the amount of solid material, with a corresponding change in the total energy. The net change in energy for a two-phase fluid can be expressed as:

[0073] ΔQ=(Q flow +Q hx -Q loss,top -Q loss,bottom -Q loss,edges )(3)

[0074] This formula can be expanded to:

[0075]

[0076] In the model, we identify the variable x as the "mass" of solid in the two-phase mixture, with a value of 0 corresponding to pure liquid and a value of 1 corresponding to pure solid. A value between 0 and 1 indicates that the mixture is part liquid and part solid at the melting / freezing temperature. We can then equate the change in mass to the net change in energy: Where Δx is the change in mass of the two-phase fluid; h is the change in mass of the two-phase fluid; fg The latent heat of fluid melting; Δt is the simulation time step; M tank The mass of the fluid in the storage tank.

[0077] Regarding parameter calculation: By analyzing the recorded data of the system, the symbols in the calculation refer to the system diagram Figure 5 To systematically evaluate the collected data, this study used the following indicators:

[0078] The heat calculation for the electric boiler heat source to supplement the heat storage system during off-peak hours is as follows:

[0079] in, The mass flow rate is the flow rate entering the phase change tank for heat exchange, Cp o is the specific heat capacity of oil (1.67 kJ / (kg·K)), and t1 is the duration of the EB circuit operation (h).

[0080] The heat storage capacity (QS) of the PCM tank is calculated as follows:

[0081] in, is the mass flow rate from SC to PCM during the day, and t2 is the duration of the collector supplying heat to the tank during the day.

[0082] Heat release Q of PCM tank R The calculation is as follows:

[0083] in, is the mass flow rate of heat released by the PCM tank during the day, Cp w is the specific heat capacity of water (4.19 kJ / (kg·K)), and t3 is the duration of discharge of the PCM tank.

[0084] When OP1 meets the starting conditions, the solar collector Q sc The heat supplied to the fuel tank is calculated as follows:

[0085] in, is the mass flow rate of the thermal oil through the solar collector, and t4 is the duration of OP1 operation.

[0086] When the oil tank temperature reaches the predetermined threshold, the heat Q transferred from the oil tank to the heating terminal w Calculate as follows:

[0087] in, is the mass flow rate of the terminal circuit entering the tank, and t5 is the duration.

[0088] For an absorption chiller, the heat supply Q from the PCM storage chiller,in and cooling energy to generate Q chiller,out , obtained from equations (11) and (12), respectively.

[0089]

[0090] and The hot water and cold water flowing through the chiller in a certain period of time, t6 chiller running time, T 16 and T 17 are the hot water inlet and outlet temperatures, T 20 and T 21 are the outlet and inlet temperatures of the chilled water. Therefore, the COP of the chiller can be chiller The coefficient of performance is defined as follows:

[0091]

[0092] The solar fraction SFn is defined as the solar fraction supplied to the system Q solar,out Solar Energy and Solar Q solar,out The ratio of the total energy to the auxiliary energy. The auxiliary energy corresponds to the heat energy provided by the electric boiler EB in this paper. Therefore, it can be calculated using equation (14).

[0093] In terms of the system operation strategy, regarding the heating mode: Based on the multi-source collaborative energy supply architecture of SC, EB, and PCMST, this system adopts a time-of-use electricity price regulation strategy to achieve dynamic thermal management. The operation logic is divided into three modes: SC-PCMST hybrid mode: When the oil tank T3 heated by SC ≥ the set threshold (e.g., 50°C), EV1 / EV2 / EV3 switch to the SC direct supply loop, and the oil tank heating takes priority to meet the building demand. The surplus heat is then injected into PCMST for storage through the adjustment of three valves; if 30°C < T3 < the threshold, switch the EV3 / EV5 / EV7 valves to achieve series heating of SC and PCMST, and improve the utilization rate of low-temperature heat sources through OT / PCMST cascade heat exchange. PCMST independent energy supply: During non-valley electricity periods or when the SC irradiation is insufficient, turn off the OP1 pump, and only release heat through PCMST. The return water of the floor heating flows into PCMST for heat exchange through the adjustment of EV3 / EV5. Valley electricity period (22:00 - 8:00): EB starts to heat the heat-conducting oil to 43°C, opens the OP2 pump to store and release heat in PCMST, and at the same time completes the latent heat accumulation of the heat storage body and the heat release matching the building load. The operation logic of the system is as Figure 7a shown. Regarding the cooling mode: The cooling mode of this system adopts a time-of-use adaptive control strategy, and sets adjustable cooling periods according to the farmers' work and rest patterns combined with the outdoor temperature. When T1 ≥ 109.4°C, switch the three-way valve EV1 / EV2 to the heat storage loop, and drive the heat-conducting oil to flow through PCMST to complete sensible-latent heat coupling heat storage. When the cooling demand is triggered, start the OP3 / WP4 pumps to transport the high-temperature heat-conducting oil (T1 ≥ 109.4°C) in PCMST to the oil-water heat exchanger for heat exchange to drive the absorption chiller to work, and at the same time start the WP3 pump to maintain the cooling cycle; if the temperature of the heat-conducting oil T < 90°C (the rated driving threshold of the absorption chiller) during the heat release stage of PCMST, then联动开启WP5泵及电锅炉辅助加热模块,通过EV9 / EV10阀门切换流向,使其经锅炉补热至90℃后输入制冷机。产生的冷冻水(7-12℃)经WP2泵输送至用户末端设备。运行逻辑如 Figure 7b shown.

[0094] It should be noted that there is an unclear expression "联动开启WP5泵及电锅炉辅助加热模块" in the original text. It might need to be further clarified for a more accurate translation.Regarding the daily analysis of heating simulation: In view of the fluctuations in solar radiation intensity and low temperature environment characteristics during the winter heating cycle, this study selected typical single-day operation data for comparative analysis. In view of the differential impact of clear sky and cloudy / hazy weather on system energy efficiency, December 11 and January 4 were selected as typical meteorological days to represent the two types of operating conditions (note that these two operating days are not extremely cold or hot weather). Based on the timing characteristics of the energy management strategy, the system operation mode is divided into three typical operating conditions (as shown in the color range at the bottom of Figures 8 and 9): SC-PCMST hybrid energy supply mode (light green period), valley power auxiliary energy supply mode (dark blue period) and PCMST independent energy supply mode (white period). Among them, the hybrid mode corresponds to the coordinated operation of direct solar energy supply and phase change thermal storage under high irradiation conditions. The grid load transfer strategy is implemented during the valley power period, and the thermal storage unit is relied upon to achieve thermal and electric decoupling energy supply in the remaining periods. Based on the time-of-use electricity price control strategy, the electric boiler (EB) is automatically started through the control logic during the valley electricity price period (22:00-08:00), and its heat output temperature peak is set to 43°C. Thermodynamic monitoring data show that this temperature threshold can simultaneously achieve the matching of the latent heat storage of the phase change thermal storage tank (PCMST) with the terminal heating demand. In the solar energy-dominated energy supply stage (13:15-18:22), the temporal evolution of the collector outlet temperature and the thermal oil storage tank temperature showed a significant positive correlation, and the two reached extreme values of 63.53°C and 59°C at 14:30 and 15:03 respectively, corresponding to an instantaneous solar irradiation intensity of 364.09W / m 2 . When the tank temperature monitoring value exceeds the set threshold (T≥50℃), the system automatically switches to the direct supply mode of the oil tank heat exchanger, and stabilizes the floor heating inlet water temperature at 35±0.5℃ by adjusting the flow direction of the three-way valve EV1 / EV3, thereby maintaining the indoor thermal environment temperature in the range of 22.0±1℃, as shown in Figure 8. The data in the figure show that the surplus solar heat in this stage is injected into the PCMST through the EV1 opening adjustment to complete the phase change heat storage, verifying the effectiveness of the sensible heat-latent heat coupling storage mechanism. It is worth noting that in the annual operation cycle, OT exhibits significant time-based energy supply characteristics: its energy contribution rate exceeds 85% of the total building heat load demand in 14.87% of the time periods, and achieves full energy coverage in 7% of the time periods. This phenomenon is attributed to the fact that the solar direct supply system fully covers the building heat load demand under high irradiation intensity conditions. The PCMST independent energy supply mode is activated in two time periods (08:00-13:15 and 18:22-22:00), such as Figure 8a Thermodynamic analysis shows that in the stage of solar radiation intensity attenuation, the system relies on PCMST to release heat to meet the load demand, and the cumulative heat release reaches 77.869MJ ( Figure 8bIt is worth noting that the overall thermal efficiency of the PCMST is 68.4%, which is affected by the accumulation of residual heat from historical operations (heat storage in the previous cycle was not fully released); if calculated based on a single-day storage / release cycle, its daily efficiency can reach 100%. Although the simulated indoor temperature is slightly higher than the recommended value of the "Code for Design of Heating, Ventilation and Air-conditioning for Civil Buildings" (18-22°C), combined with the actual ventilation conditions of rural houses (the air exchange rate in the TRNBuild model is set at 0.5h-1) and the thermal comfort preferences of residents, this temperature range is still within the standard-defined adaptive thermal comfort zone (a deviation of ±1.5°C is acceptable).

[0095] pass Figure 9a The thermodynamic monitoring curve reveals that the oil tank temperature remained in the suboptimal range of 30-45°C for 5.604 hours at night. The system improved the utilization rate of low-temperature heat sources through OT and PCMST cascade heat exchange, realized the series heating of SC and PCMST, and ensured that the composite heat flow temperature was maintained at 35°C. During the day, the temperature of the thermal oil storage tank was always lower than the heating threshold (T<45°C). The system continued to use the phase change heat storage tank (PCMST) as the heat source and provided heating through latent heat-sensible heat conversion until the phase change material was completely solidified. EB started on time to provide timely heat supplement to keep the heating at the design value (35°C). Full-day energy flow Figure 9b Analysis shows that the solar collector system (SC) does not contribute to heat production during the day, while the nighttime OT cascade heat supply is 22.85 MJ. Furthermore, during off-peak hours, the electric boiler (EB) provides supplemental heat to the phase change tank, resulting in a total heat storage of 69.742 MJ in the PCMST. The total heat released over 24 hours is 131.436 MJ. Therefore, the daily heat release far exceeds the stored heat, resulting in a 100% daily thermal efficiency for the PCM tank. This efficiency demonstrates the thermal cycling stability of the PCM material and the effectiveness of the system control strategy. Figure 9b The time series distribution of heat further shows that the typical peak-shaving characteristics of the heat storage tank during the heat release stage are highly coupled with the solar radiation intensity decay period, confirming the core role of phase change heat storage in cross-time energy scheduling.

[0096] Regarding the simulation analysis of the absorption refrigeration system: the thermodynamic characteristics of the system in the summer working condition with the auxiliary electric boiler (Electric Boiler, EB) in operation and non-operation mode are compared (Figures 10 and 11), revealing the energy regulation mechanism of the multi-source coupled cooling system. In the working condition without EB intervention (Figure 10), when the outlet temperature of the solar collector (Solar Collector, SC) exceeds the phase change threshold (T ≥ 109.4℃) of the phase change thermal storage tank (PCMST), the system triggers the heat storage mode (charging signal Flag = 1, Figure 10c). When the user's cooling load demand is triggered, the PCMST releases heat through the plate heat exchanger, driving the temperature to 90°C, thereby activating the absorption refrigeration cycle (discharge signal Flag = 1). The system has a 7-hour charge / discharge parallel operation period. When the ambient temperature is lower than 24°C (Figure 10, the next day), the refrigeration unit automatically shuts down based on the control logic to reduce energy consumption. Under the condition of insufficient solar radiation and complete phase change and solidification of the PCMST heat storage body ( Figure 11a The next day), the EB auxiliary heating module was started, and the water flow path was switched through the valve to couple the PCMST latent heat release (68.26MJ) with the EB sensible heat supplement (21.397MJ), so that the driving temperature was stabilized at the 90℃ threshold, ensuring the continuous operation of the refrigerator ( Figure 11c Heating signal timing). Comparative analysis shows that on a typical clear sky day (Figure 12), the SC alone can meet the cooling demand, and its daytime irradiance peak reaches 946.87W / m 2 The system instantaneous heat gain reaches 11.79kW. The thermal performance evaluation shows that the maximum COP of the refrigeration unit reaches 0.65 (rated value 0.7), accounting for 92.8% of the design performance. The supply water temperature of the chilled water system is maintained at 10℃, and the return water temperature gradient after heat exchange by the fan coil is about 5℃. The indoor thermal environment simulation results show that ( Figure 10b , 11b). During the cooling period, room temperature fluctuations ranged from 24.45-26.89°C (EB shutdown mode) to 26.62-28.0°C (EB assist mode), respectively, meeting the dynamic thermal comfort zone defined by ASHRAE 55-2023. Figure 12 further quantifies the contributions of each system component per day. Under EB assist, the actual chiller cooling capacity reached a maximum of 137.2 MJ per day, with a cooling power of 4.23 kWh per hour.

[0097] Regarding the performance analysis of the phase change thermal storage tank: the daily changes in the heat storage, heat release and thermal efficiency of the PCM tank during the whole year are shown in Figure 13. Figure 13a As shown, during the heating season operation cycle, the thermal efficiency of PCM reached more than 95% in 55% of the time periods, and its lowest thermal efficiency was 60%. The reason for this was the excessive release of phase change latent heat in the previous operation cycle, which caused the system to be unbalanced between heat storage and building heat load demand when the temperature control mechanism was activated the next day. It is worth noting that the SC energy supply system achieved full energy supply coverage in 8.2% of the time periods, causing the average overall thermal efficiency of the system to drop to 84%. After data correction and excluding the influence of this operating condition, the average thermal efficiency of the PCM system in the heating season increased to 91.4%. This result effectively confirmed that the phase change material has good cycle stability and robustness of the control system strategy. Under cooling season conditions ( Figure 13b), since the cooling load is affected by the dynamic fluctuations of meteorological parameters (solar irradiance, ambient temperature), the daily heat release of PCMST presents significant non-steady-state characteristics, and the simulated hysteresis effect caused by the thermal inertia of the system is superimposed, which leads to two typical abnormal operating conditions: heat storage > heat release, corresponding to the fluctuation of the phase change ratio of the tank; only the heat release mode is triggered, corresponding to the SC temperature not reaching the phase change heat storage temperature. It is worth noting that the system's adaptive shutdown strategy based on ambient temperature feedback (threshold T < 24°C shutdown) results in 8.5% of the time period thermal efficiency data missing (not included in the statistics). After excluding the shutdown period, the average thermal efficiency of the cooling season is 79%. In comparison, the thermal efficiency fluctuation of the cooling season is more obvious, such as Figure 13b shown. Figure 14 Energy ratio analysis shows that the PCMST exhibits significant differences in multi-source coupling characteristics under cooling and heating conditions. During the cooling period, solar energy contributes almost entirely to the system's heat source, reaching a theoretical maximum solar fraction of 99%. The auxiliary heat supply from the electric boiler (EB) is negligible. This phenomenon is attributed to the temporal and spatial matching between the absorption chiller's driving temperature threshold (T ≥ 90°C) and solar irradiation intensity. Under heating conditions, however, solar energy alone cannot meet the building's annual heat load demand. After introducing EB heating through a coordinated peak-valley electricity price control strategy, the system's solar fraction (SFn) averages as high as 68%, significantly improving heat load coverage stability and verifying the necessity of a multi-source complementary mechanism in energy scheduling.

[0098] Regarding system cost analysis: Figure 15The multi-source energy supply characteristics of the SPCMS system during the heating and cooling seasons were quantitatively analyzed. Thermodynamic statistics show that during the heating season, the cumulative heat supply from the solar thermal collector (SC), the phase change thermal storage tank (PCMST), and the supplementary heat from the electric boiler (EB) were 10,231.65 MJ, 7,311.7 MJ, and 5,643.55 MJ, respectively. On the demand side, SC and PCMST accounted for 53.7% and 46.3%, respectively. Regarding the heat storage capacity of the PCMST, EB and SC accounted for 76.48% and 23.52%, respectively. During the cooling season, 5,334.7 MJ of heat generated by the SC was dispatched across time periods through the PCMST, combined with the supplementary heat supply of 21.39 MJ from the EB, resulting in a total energy supply ratio of 99.6% for the PCMST (5,080.4 MJ) and 0.4% for the EB. Under heating conditions, the SC heating share (53.7%) surpassed the PCMST (46.3%), demonstrating the feasibility of solar energy as the primary heat source, maximizing renewable energy utilization and minimizing power losses. During the cooling load cycle, the system's phase change heat storage mechanism boosted solar energy conversion efficiency to 95.2%, reducing EB power consumption to 0.4%. Therefore, this system's operating strategy effectively couples off-peak electricity thermal storage (EB heating during off-peak electricity price periods) with time-shifted solar energy supply, fully utilizing solar energy. Figure 16 shows the simulated power distribution characteristics of the SPCMS system during the heating and cooling seasons. In winter, the entire system consumed 1905.11 kWh, with the electric boiler (EB) circuit consuming 1821.70 kWh during off-peak periods, representing a significant 95.6% of the heating power. The operating power of the solar thermal system (SC) and the terminal circulation system (0.02 kW water pump) accounted for only 1.3% and 3%, respectively. Although increasing the solar collector area can further reduce operating costs, we must be wary of the exponential increase in initial investment caused by equipment expansion. Compared to the summer period, the participation of EB has dropped significantly. The absorption chiller circuit (chiller rated power 11kW + cooling tower fan 0.07kW + dual water pump 0.067kW) and the terminal circuit (water pump 0.03kW + fan 0.138kW) account for 60.5% and 36.8% of the total system power, respectively. Figure 17 According to the calculation of time-of-use electricity price and instantaneous electricity consumption, Figure 17Figures 18 and 19 show the simulation results of the total cost ratio and operating cost characteristics of this system in the heating and cooling seasons. In winter, the EB operating cost is 652.72 yuan (accounting for 94.1%), and the SC and terminal system costs are 14.14 yuan (2%) and 27.1 yuan (3.9%) respectively. The total operating cost of the heating system during the entire heating season is 693.96 yuan, that is, the specific operating cost is 0.075 yuan / m2·day, which is much lower than the central heating benchmark price issued by Zhengzhou City (0.19 yuan / m2·day), and can save up to 60.5% of the heating fee. In summer, the operating cost of the chiller circuit is 333.6 yuan (accounting for 64.2%), the terminal circuit cost is 171.6 yuan (33.0%), and the total cooling cost is 519.9 yuan. Compared with the conventional 1.5-horsepower air conditioner cooling at 1.5 kWh / hour, running for 8 hours a day, it saves 34.2% of energy. This study verified the engineering feasibility of the SPCMS system in reducing operating costs (total cost reduction >50%) and increasing the proportion of renewable energy (solar energy utilization rate of 53.7% in the heating season) through multi-source coordination and time-of-use electricity pricing strategies.

[0099] In general, this study aims to meet the energy supply needs of rural single-family buildings by constructing a solar absorption-type combined cooling and heating system based on phase change thermal storage. By integrating solar thermal collection, phase change thermal storage and valley electricity heating strategies, the system achieves efficient utilization of clean energy and multi-source coordinated energy supply. Based on the full-year dynamic simulation and meteorological data analysis of the TRNSYS platform, the system has achieved the following academic results in terms of technological breakthroughs, energy efficiency improvement and economic optimization: (1) Technological innovation and system optimization: The thermal storage unit adopts paraffin / expanded graphite composite phase change material (phase change temperature 37℃ / 109.4℃) and spiral tube enhanced heat transfer structure. Combined with the time-of-use electricity price mechanism and the adaptive control strategy of irradiation matching, the system achieves efficient dynamic matching of valley electricity thermal storage, solar time-shifted energy supply and load demand, solving the problem of incomplete PCM charging and discharging in traditional control strategies. (2) Energy efficiency and improved renewable energy penetration: Simulation results show that the system's solar energy contribution in the heating season reaches 53.7%, and the solar energy guarantee factor (SF) is as high as 68%, and the average daily efficiency of the phase change thermal storage unit reaches 91.4%; in the cooling season, the solar energy contribution exceeds 99.6%, and the grid dependence is less than 0.4%. Compared with traditional central heating and conventional air-conditioning systems, the SPCMS reduces the annual operating costs of heating and cooling by 60.5% and 34.2% respectively while ensuring a stable indoor thermal environment (20±2℃ for heating and 26±2℃ for cooling, in compliance with ASHRAE 55-2023 standards), verifying its significant advantages in increasing renewable energy penetration and reducing carbon emissions. (3) Extreme weather adaptability verification: Under typical extreme weather conditions (such as cloudy days in winter and insufficient radiation days in summer), the system maintains the continuity and stability of energy supply through valley power heating and multi-source cascade heat exchange mechanism. For example, under extreme winter conditions, the heat storage unit completely changes phase, releasing 131.436MJ of heat per day, and the daily thermal efficiency reaches the theoretical extreme value; in summer, the COP of the chiller reaches 0.65 (92.8% of the design value), and the indoor temperature fluctuation range is controlled within the comfortable range, which fully demonstrates the robustness of the system under complex climatic conditions. (4) Breakthroughs compared with existing research: This study fills the research gap of rural single-household miniaturized energy supply systems, and solves the problems of unclear dynamic matching mechanism between heat storage units and collectors and lagging control strategies in existing results. Compared with centralized energy supply systems, SPCMS provides a replicable technical paradigm for rural energy transformation through distributed architecture and multi-modal control strategies.

[0100] 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.

[0101] The above is a detailed introduction to the control method, system, device, product, equipment and medium of a solar absorption cooling and heating integrated system based on phase change heat storage 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 cooling and heating integrated system based on phase change heat storage, characterized in that: The system comprises: Solar thermal collection module, thermal oil storage tank, phase change thermal storage module, absorption refrigeration module, heating and heat supplement module and multi-modal control module; The solar thermal collection module is connected to the thermal storage tank, and the phase change thermal storage module is respectively connected to the thermal storage tank, the solar thermal collection module, the absorption refrigeration module and the heating and heat supplement module, and the solar thermal collection module, the phase change thermal storage module, the thermal storage tank, the absorption refrigeration module and the heating and heat supplement module perform heat transfer through thermal oil; The solar thermal collection module is used to collect solar energy and convert it into thermal energy, which is then output to the thermal storage tank, the phase change thermal storage module and the heating terminal module respectively; The phase change heat storage module is used to store the heat delivered by the solar energy heat collection module and to supply heat to the solar energy heat collection module; The absorption refrigeration module is used to output cooling capacity to the building unit; The heating and heat supplement module is used to supplement heat to the phase change heat storage module; The multimodal control module is used to: During the heating period, in response to the time being off-peak time, the phase change thermal storage module is controlled to store heat; in response to the time being non-off-peak time, the temperature of the thermal storage tank is monitored, and based on the comparison result between the thermal storage tank temperature and the set threshold, the system's heating mode is switched. The heating modes include: a mixed heating mode of the solar thermal collection module and the phase change thermal storage module, and a separate heating mode of the phase change thermal storage module; During the cooling period, in response to the user's cooling load demand being triggered, the phase change heat storage module is controlled to store heat or drive the absorption refrigeration module to cool; in response to the user's cooling load demand not being triggered, the heating heat supplement module is controlled to supplement heat to the phase change heat storage module.

2. The integrated cooling and heating system based on phase change heat storage according to claim 1, characterized in that: The system further includes a first oil pump and a second oil pump, wherein the first oil pump is connected in series with the circuits where the solar thermal collection module and the heat storage tank are located, and the second oil pump is connected in series with the circuits where the heating and heat supplementing module and the phase change heat storage module are located. During the heating period, in response to the time being the valley time, the phase change heat storage module is controlled to store heat as follows: During the heating period, in response to the time being off-peak electricity time, the first oil pump is turned off and the second oil pump is started, the heating and heat replenishment module is controlled to start heating the thermal oil to 43℃±2℃, and the second oil pump is turned on to store and release heat to the phase change heat storage module, and at the same time, the latent heat storage of the phase change heat storage module is matched with the building load to release heat.

3. The integrated cooling and heating system based on phase change heat storage as claimed in claim 2, characterized in that: The system includes a first valve and a second valve, wherein the first valve is connected in series with a series circuit including a thermal storage tank, a phase change thermal storage module, and a solar thermal collection module, and the second valve is connected in series with a series circuit including a thermal storage tank and a phase change thermal storage module; In response to the time being a non-off-peak time, the temperature of the thermal storage tank is monitored, and based on the comparison result between the thermal storage tank temperature and the set threshold value, the heating mode of the system is switched. The heating modes include: a mixed heating mode of the solar thermal collection module and the phase change thermal storage module and an independent heating mode of the phase change thermal storage module. In response to the time being a non-valley time, monitoring the temperature of the thermal storage tank to be less than a set threshold and greater than 30°C±2°C, switching the first valve to connect the solar thermal collection module and the phase change thermal storage module in series, and controlling the solar thermal collection module and the phase change thermal storage unit to supply heat in series; In response to the time being non-off-peak time, the temperature of the thermal storage oil tank is monitored to be less than 30°C±2°C, the first oil pump is turned off, and the second valve is controlled to switch to the phase change thermal storage module circuit, and the phase change thermal storage module independently provides heat.

4. The integrated cooling and heating system based on phase change heat storage as claimed in claim 3, characterized in that: The system includes a heating terminal module and a third valve, wherein the heating terminal module is respectively connected to the solar thermal collection module, the thermal oil storage tank and the phase change thermal storage module, and the heating terminal module is used to supply heat to the building unit, and the third valve is connected in series with the circuit where the solar thermal collection module, the heating terminal module and the phase change thermal storage module are located; The step of monitoring the temperature of the thermal storage tank in response to the time being a non-off-peak time, and switching the heating mode of the system based on a comparison result between the thermal storage tank temperature and a set threshold value, further includes: In response to the time being non-off-peak time, if the temperature of the heat storage oil tank is monitored to be greater than or equal to a set threshold, the third valve is switched to the direct power supply circuit of the solar thermal collection module, and the solar thermal collection module is controlled to preferentially supply heat to the heating terminal module, and the surplus heat is stored in the phase change heat storage unit.

5. The integrated cooling and heating system based on phase change heat storage according to claim 1, characterized in that: The system includes a third oil pump, a first water pump, a second water pump, a fourth valve and an oil-water heat exchange module; The oil-water exchange module is connected to the phase change heat storage module and the absorption refrigeration module respectively; The absorption refrigeration module is connected to the oil-water exchange module and the heating and heat supplement module respectively; The third oil pump is connected in series with the circuit where the phase change heat storage unit and the oil-water exchange module are located; the first water pump is connected in series with the circuit where the oil-water exchange module and the absorption refrigeration module are located; the second water pump is connected in series with the circuit where the absorption refrigeration module and the heating and heat supplement module are located; and the fourth valve is connected in series with the circuit where the oil-water exchange module and the absorption refrigeration module are located; During the cooling period, in response to the user's cooling load demand being triggered, the phase change thermal storage module is controlled to store heat or the absorption refrigeration module is driven to cool as follows: In response to the user's cooling load demand being triggered and the temperature of the phase change heat storage module being greater than the rated driving threshold of the absorption refrigeration module, the third oil pump and the first water pump are turned on to exchange heat with the phase change heat storage module, driving the absorption refrigeration module to work, and the second water pump is turned on to maintain the cooling cycle; In response to the user's cooling load demand being triggered and the temperature of the phase change heat storage module being less than or equal to the rated driving threshold of the absorption refrigeration module, the first water pump is turned on and the fourth valve is switched to control the heating supplement module to assist in heating.

6. The integrated cooling and heating system based on phase change heat storage as claimed in claim 5, characterized in that: The system includes a fifth valve, which is connected in series with the circuit where the solar thermal collection module and the thermal storage tank are located; In response to the user's cooling load demand not being triggered, the heating heat supply module is controlled to supply heat to the phase change heat storage module as follows: in response to the user's cooling load demand not being triggered, the fifth valve is switched to the phase change heat storage module circuit, the first oil pump is turned on, and the phase change heat storage module is controlled to be connected in series with the heat storage tank to store heat.

7. The integrated cooling and heating system based on phase change heat storage according to claim 6, characterized in that: The system further comprises: In response to the outlet temperature of the solar thermal collection module being greater than the phase change threshold of the phase change heat storage module, the fifth valve is switched to the heat storage circuit of the solar thermal collection module and the phase change heat storage module, driving the phase change heat storage module to complete sensible heat-latent heat coupled heat storage.

8. A control method for an integrated cooling and heating system based on phase change heat storage, characterized in that: The method comprises the following steps: S1, during the heating period, determines whether the time is off-peak or non-off-peak, and switches the system's heating mode according to the time determination result; S101, if the time is valley time, control the phase change heat storage module to store heat; S102, if the time is non-off-peak time, monitoring the temperature of the thermal storage tank, and switching the system's heating mode based on a comparison result between the thermal storage tank temperature and a set threshold value, the heating modes including: a hybrid heating mode of a solar thermal collection module and a phase change thermal storage module, and a standalone heating mode of a phase change thermal storage module; S2, during the cooling period, determines whether the user's cooling load demand is triggered, and switches the system to cooling mode or heating mode according to the demand determination result; S201, during the cooling period, determining that the user's cooling load demand is triggered, and controlling the phase change thermal storage module to store heat or driving the absorption refrigeration module to cool; S202 , during the cooling period, it is determined that the user's cooling load demand is not triggered, and the heating supplementary heat module is controlled to supplement heat to the phase change heat storage module.

9. The control method of the integrated cooling and heating system based on phase change heat storage according to claim 8, characterized in that: The S101 is specifically as follows: During the heating period, if it is off-peak time, the first oil pump is turned off and the second oil pump is turned on. The heating and replenishing module is controlled to start heating the thermal oil to 43°C ± 2°C. The second oil pump is turned on to store and release heat to the phase change thermal storage module. At the same time, the latent heat stored in the phase change thermal storage module is matched with the building load and released. The S102 is specifically as follows: During the heating period, it is determined that the time is not off-peak time, and the temperature of the thermal storage tank is monitored. If the temperature of the thermal storage tank is less than a set threshold and greater than 30°C ± 2°C, the first valve is switched to connect the solar thermal collection module and the phase change thermal storage module in series, and the solar thermal collection module and the phase change thermal storage unit are controlled to be connected in series for heating; During the heating period, the time is determined to be non-off-peak time, and the temperature of the thermal storage tank is monitored. If the temperature of the thermal storage tank is less than 30°C ± 2°C, the first oil pump is turned off, and the second valve is controlled to switch to the phase change thermal storage module circuit, and the phase change thermal storage module independently provides heating.

10. The control method of the integrated cooling and heating system based on phase change heat storage according to claim 8, characterized in that: The S201 is specifically as follows: During the cooling period, if the user's cooling load demand is triggered and the temperature of the phase-change thermal storage module is greater than the rated driving threshold of the absorption refrigeration module, the third oil pump and the first water pump are turned on to exchange heat with the phase-change thermal storage module, driving the absorption refrigeration module to work, and the second water pump is turned on to maintain the cooling cycle; During the cooling period, if the user's cooling load demand is triggered and the temperature of the phase change heat storage module is less than or equal to the rated driving threshold of the absorption refrigeration module, the first water pump is turned on and the fourth valve is switched to control the heating supplement module to assist in heating. The S202 is specifically as follows: During the cooling period, if the user's cooling load demand is not triggered, the fifth valve is switched to the phase change thermal storage module circuit, the first oil pump is turned on, and the phase change thermal storage module is controlled to be connected in series with the thermal storage tank to store heat.

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