Multi-energy coupling cascade heating system based on light chasing photovoltaics and method of using the same

Abstract

The application discloses a multi-energy coupling cascade heating system based on light tracking photovoltaics and a use method thereof, and relates to the technical field of heating systems. The multi-energy coupling cascade heating system comprises a light tracking photovoltaic, a solar energy collector, a heat storage water tank, a circulating water tank, a heat storage tank and a user end. The application takes clean energy or low-price electricity such as solar energy and off-peak electricity as the power source of the system, thereby reducing the consumption of fossil energy. The heat storage tank is a buried heat storage tank encapsulating phase change materials, which stores sufficient heat in summer for cross-season use, thereby overcoming the problem of uneven energy space-time distribution.

Description

Multi-energy coupling cascade heating system based on solar tracking and its application method Technical Field

[0001] This invention belongs to the field of heating system technology, specifically relating to a multi-energy coupled cascade heating system based on solar tracking photovoltaics and its usage method. Background Technology

[0002] Heating is a crucial aspect of ensuring the livelihoods of residents in northern my country. However, the following problems exist in actual heating practices: First, traditional heating methods primarily rely on burning fossil fuels, leading to significant fossil fuel consumption in today's energy-scarce era. Second, while some regions have introduced clean energy sources like solar power for heating, the short daylight hours in northern winters mean that simply using solar thermal heating results in insufficient heat supply. Third, northern my country enjoys abundant sunshine and long hours in summer, providing ample heat that cannot be utilized in winter, creating a mismatch between time and space. Fourth, while coal-to-electricity conversion and heat pumps have been implemented in northern regions, the primary energy source remains electricity. Furthermore, my country's peak-valley electricity pricing policy results in higher operating costs for electricity-based heating strategies during peak hours. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a multi-energy coupled cascade heating system based on solar photovoltaic power. This system uses solar energy as the primary energy source, generating heat and electricity from solar energy. Simultaneously, it can utilize cross-seasonal heat storage to store summer energy and reuse this heat in winter, solving the problem of heat mismatch in time and space in northern regions. At the same time, the electric heating phase change floor provides an additional layer of protection against the instability of solar energy while maintaining heating time. The electric heating source is mainly the electricity stored in the batteries of concentrated photovoltaic power, supplemented by off-peak electricity, achieving efficient and clean heating and reducing costs to a certain extent.

[0004] The objective of this invention is achieved through the following technical solution.

[0005] A multi-energy coupled cascade heating system based on solar photovoltaic (PV) tracking includes: a concentrating photovoltaic (PV) unit, a solar collector, a hot water storage tank, a circulating water tank, a thermal storage tank, and a user terminal. The outlet of the circulating water tank is connected to the first port of a first three-way valve, the second port of the first three-way valve is connected to the first port of a second three-way valve, the second port of the second three-way valve is connected to the inlet of the concentrating PV unit, the outlet of the concentrating PV unit and the third port of the second three-way valve are respectively connected to the inlet of the solar collector, and the outlet of the solar collector is connected to the inlet of the hot water storage tank.

[0006] The heat storage tank is equipped with heat storage pipes and heat exchange pipes for exchanging heat. The heat storage tank surrounding the heat storage pipes and heat exchange pipes is filled with heat storage medium. The outlet of the hot water storage tank is connected to one port of a third three-way valve. The other two ports of the third three-way valve are respectively connected to the inlet of the heat storage pipe and one port of a fourth three-way valve. The other two ports of the fourth three-way valve are respectively connected to the outlet of the heat exchange pipe and the inlet of the user end. The inlet of the heat exchange pipe is connected to the third port of the first three-way valve. The outlet of the heat storage pipe is connected to the first port of a fifth three-way valve. The second port of the fifth three-way valve is connected to the inlet of the circulating water tank. The third port of the fifth three-way valve is connected to the outlet of the user end.

[0007] A first thermocouple is installed on the pipeline between the inlet of the heating pipeline and the fourth three-way valve, and a second thermocouple is installed on the pipeline between the second three-way valve and the first three-way valve. The user end includes a phase change material layer, and a third thermocouple is provided in the phase change material layer.

[0008] The controller is electrically connected to the first thermocouple, the second thermocouple, the third thermocouple, the first three-way valve, the second three-way valve, the third three-way valve, the fourth three-way valve, and the fifth three-way valve, respectively.

[0009] The above technical solution also includes: a battery, which is electrically connected to the concentrated photovoltaic.

[0010] In the above technical solution, the user terminal includes: a phase change floor, which includes: a wear-resistant layer, a phase change material layer, a heating pipe, an electric heating film, a first solid-solid phase change material layer, and a fireproof layer. The wear-resistant layer, the phase change material layer, the electric heating film, the first solid-solid phase change material layer, and the fireproof layer are parallel and connected sequentially from top to bottom. The heating pipe passes through the phase change material layer, and the inlet of the heating pipe serves as the inlet of the user terminal, and the outlet of the heating pipe serves as the outlet of the user terminal.

[0011] In the above technical solution, the battery is electrically connected to the electric heating film.

[0012] In the above technical solution, the heat storage tank includes: a tank body, a second solid-solid phase change material layer, a heat insulation material layer, and the heat storage medium. The heat insulation material layer is disposed on the inner wall of the tank body, the second solid-solid phase change material layer is disposed on the inner wall of the heat insulation material layer, and the heat storage medium is filled in the space enclosed by the heat insulation material layer.

[0013] The above technical solution also includes a thermal management system for managing the temperature of concentrated photovoltaic cells.

[0014] In the above technical solution, the heat storage tank is buried underground at a depth not exceeding 0.1m.

[0015] In the above technical solution, the thermal conductivity of the phase change material in the phase change material layer is not less than 1 W·m. -1 ·K -1 The phase change temperature of the phase change material in the phase change material layer is greater than or equal to 25℃ and less than 30℃, and the latent heat of phase change of the phase change material in the phase change material layer is not less than 250kJ·kg. -1 .

[0016] In the above technical solution, the electric heating film is a graphene heating film.

[0017] In the above technical solution, the phase transition temperature of the solid-solid phase change material in the first solid-solid phase change material layer is not higher than 25°C, and the thermal conductivity of the solid-solid phase change material in the first solid-solid phase change material layer is not higher than 0.2 W·m. -1 ·K -1 The phase transition temperature of the solid-solid phase change material in the second solid-solid phase change material layer is less than or equal to 50°C, and the thermal conductivity of the solid-solid phase change material in the second solid-solid phase change material layer is not higher than 0.2 W·m. -1 ·K -1 .

[0018] In the above technical solution, the thermal conductivity of the insulation material in the insulation layer is not higher than 0.04 W·m. -1 ·K -1 .

[0019] In the above technical solution, a third water pump is installed on the pipeline between the outlet of the circulating water tank and the first three-way valve, a second water pump is installed on the pipeline between the third three-way valve and the inlet of the heat storage pipeline, a first water pump is installed on the pipeline between the third three-way valve and the fourth three-way valve, and the controller is electrically connected to the first water pump, the second water pump and the third water pump respectively.

[0020] The above-mentioned method of using the multi-energy coupled cascade heating system based on solar tracking photovoltaics includes one of the following methods one through three:

[0021] Method 1: Open the port of the first three-way valve that connects to the outlet of the circulating water tank and the port that connects to the second three-way valve; close the port of the first three-way valve that connects to the inlet of the heat exchange pipe; open the port of the second three-way valve that connects to the first three-way valve; open the port of the second three-way valve that connects to the inlet of the concentrating photovoltaic unit or the inlet of the solar collector; open the port of the third three-way valve that connects to the outlet of the hot water storage tank and the port that connects to the inlet of the heat storage pipe; close the port of the third three-way valve that connects to the fourth three-way valve; close all ports of the fourth three-way valve; open the port of the fifth three-way valve that connects to the inlet of the circulating water tank and the port that connects to the outlet of the heat storage pipe; close the port of the fifth three-way valve that connects to the outlet of the user.

[0022] Method 2: Open all ports of the first three-way valve; open the port of the second three-way valve used to connect with the first three-way valve, and open the port of the second three-way valve used to connect with the inlet of the concentrating photovoltaic unit or the inlet of the solar collector; open the port of the third three-way valve used to connect with the outlet of the hot water storage tank and the port used to connect with the fourth three-way valve, and close the port of the third three-way valve used to connect with the inlet of the heat storage pipeline; open the port of the fourth three-way valve used to connect with the inlet of the user end, and open the port of the fourth three-way valve used to connect with the third three-way valve and / or the port used to connect with the outlet of the heat exchange pipeline; open the port of the fifth three-way valve used to connect with the inlet of the circulating water tank and the port used to connect with the outlet of the user end, and close the port of the fifth three-way valve used to connect with the outlet of the heat storage pipeline.

[0023] Method 3: Open the port of the first three-way valve that connects to the outlet of the circulating water tank and the port that connects to the inlet of the heat exchange pipe; close the port of the first three-way valve that connects to the second three-way valve; close all ports of the second three-way valve; close all ports of the third three-way valve; open the port of the fourth three-way valve that connects to the outlet of the heat exchange pipe and the port that connects to the inlet of the user; close the port of the fourth three-way valve that connects to the third three-way valve; open the port of the fifth three-way valve that connects to the inlet of the circulating water tank and the port that connects to the outlet of the user; close the port of the fifth three-way valve that connects to the outlet of the heat storage pipe.

[0024] In the above technical solutions, in methods one and two, when the controller obtains that the temperature of the water passing through the second thermocouple exceeds 30°C, it opens the port of the second three-way valve for connecting with the inlet of the solar collector and the port of the second three-way valve for connecting with the first three-way valve, and closes the port of the second three-way valve for connecting with the inlet of the concentrating photovoltaic.

[0025] In the above technical solution, in the second method, when the controller obtains that the temperature of the water passing through the first thermocouple is lower than 35°C, it opens the port of the fourth three-way valve for connecting with the outlet of the heat exchange pipe; when the controller obtains that the temperature of the water passing through the first thermocouple is higher than 40°C, it closes the port of the fourth three-way valve for connecting with the outlet of the heat exchange pipe and opens the port of the fourth three-way valve for connecting with the third three-way valve.

[0026] In the above technical solutions, in methods two and three, when the controller obtains through the third thermocouple that the temperature in the phase change material layer is lower than the phase change temperature of the phase change material in the phase change material layer, the electric heating film heats the phase change material layer until the temperature in the phase change material layer is greater than or equal to the phase change temperature of the phase change material in the phase change material layer.

[0027] In the above technical solution, when the indoor ambient temperature at the user end is lower than 15°C, the electric heating film is activated to heat the room until the indoor ambient temperature at the user end reaches 20°C.

[0028] In the above technical solution, the heat storage medium is a phase change material. In the first method, when the temperature of the heat storage medium in the heat storage tank is higher than its phase change temperature, the port of the third three-way valve that is connected to the outlet of the hot water storage tank and the port that is connected to the inlet of the heat storage pipeline are closed.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) This invention uses clean energy sources such as solar energy and off-peak electricity or low-cost electricity as the power source of the system, thereby reducing the consumption of fossil energy;

[0031] (2) The present invention connects the second three-way valve to the thermal management system of the concentrating photovoltaic system. While the thermal management system manages the thermal of the concentrating photovoltaic system, it preheats the cold water entering the solar collector to reduce energy loss. At the same time, the second three-way valve and the second thermocouple are set to control the water temperature entering the thermal management system to ensure the efficient operation of the concentrating photovoltaic system.

[0032] (3) The present invention uses a heat storage tank as a buried heat storage tank to encapsulate phase change material, which stores sufficient heat in summer for use across seasons and overcomes the problem of uneven energy distribution in time and space.

[0033] (4) A phase change material layer is filled in the phase change floor to maintain the heating temperature for a longer time, and a fourth three-way valve and the first thermocouple are installed at the inlet end to realize multi-energy cascade heating.

[0034] (5) A second solid-solid phase change material layer is filled in the heat storage tank, and a first solid-solid phase change material layer is filled in the phase change floor to achieve better heat preservation effect. Attached Figure Description

[0035] Figure 1 is a schematic diagram of the structure of the multi-energy coupled cascade heating system of the present invention.

[0036] 1: Concentrated photovoltaic, 2: Solar collector, 3: Hot water storage tank, 4: First water pump, 5: Phase change floor, 6: Wear-resistant layer, 7: Phase change material layer, 8: Heating pipe, 9: Electric heating film, 10: First solid-solid phase change material layer, 11: Fireproof layer, 12: Circulating water tank, 13: Battery, 14: Second water pump, 15: Third water pump, 16: First three-way valve, 17: Second three-way valve, 18: Third three-way valve, 19: Fourth three-way valve, 20: Fifth three-way valve, 21: Heat storage tank, 22: Insulation material layer, 23: Second solid-solid phase change material layer, 24: Heat storage medium, 25: Heat storage pipe, 26: Heat exchange pipe. Detailed Implementation

[0037] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0038] Example 1

[0039] As shown in Figure 1, a multi-energy coupled cascade heating system based on solar tracking photovoltaics includes: a concentrating photovoltaic (PV) unit 1, a solar collector 2, a hot water storage tank 3, a circulating water tank 12, a thermal storage tank 21, and a user terminal. The concentrating PV unit 1 can track the sun according to the light intensity. The outlet of the circulating water tank 12 is connected to the first port of a first three-way valve 16, the second port of the first three-way valve 16 is connected to the first port of a second three-way valve 17, the second port of the second three-way valve 17 is connected to the inlet of the concentrating PV unit 1, the outlet of the concentrating PV unit 1 and the third port of the second three-way valve 17 are respectively connected to the inlet of the solar collector 2, and the outlet of the solar collector 2 is connected to the inlet of the hot water storage tank 3.

[0040] The heat storage tank 21 is equipped with heat storage pipes 25 and heat exchange pipes 26 for exchanging heat. The heat storage tank 21 around the heat storage pipes 25 and heat exchange pipes 26 is filled with heat storage medium 24. The outlet of the hot water storage tank 3 is connected to one port of a third three-way valve 18. The other two ports of the third three-way valve 18 are connected to the inlet of the heat storage pipe 25 and one port of a fourth three-way valve 19, respectively. The other two ports of the fourth three-way valve 19 are connected to the outlet of the heat exchange pipe 26 and the inlet of the user end, respectively. The inlet of the heat exchange pipe 26 is connected to the third port of the first three-way valve 16. The outlet of the heat storage pipe 25 is connected to the first port of a fifth three-way valve 20. The second port of the fifth three-way valve 20 is connected to the inlet of the circulating water tank 12. The third port of the fifth three-way valve 20 is connected to the outlet of the user end.

[0041] A first thermocouple is installed on the pipeline between the inlet of the heating pipeline 8 and the fourth three-way valve 19, and a second thermocouple is installed on the pipeline between the second three-way valve 17 and the first three-way valve 16. The user end includes: a phase change material layer 7, in which a third thermocouple is provided.

[0042] The controller is electrically connected to the first thermocouple, the second thermocouple, the third thermocouple, the first three-way valve 16, the second three-way valve 17, the third three-way valve 18, the fourth three-way valve 19, and the fifth three-way valve 20, respectively. The coordination between multiple energy sources in the entire system is achieved through the switching of the first, third, fourth, and fifth three-way valves.

[0043] Example 2

[0044] Based on Embodiment 1, the user end includes: a phase change floor 5, which includes: a wear-resistant layer 6, a phase change material layer 7, a heating pipe 8, an electric heating film 9, a first solid-solid phase change material layer 10, and a fireproof layer 11. The wear-resistant layer 6, the phase change material layer 7, the electric heating film 9, the first solid-solid phase change material layer 10, and the fireproof layer 11 are parallel and connected sequentially from top to bottom. The heating pipe 8 passes through the phase change material layer 7 and is in direct contact with the phase change material layer 7. The inlet of the heating pipe 8 serves as the inlet of the user end, and the outlet of the heating pipe 8 serves as the outlet of the user end.

[0045] It also includes: battery 13, which is electrically connected to the concentrator photovoltaic 1 via an inverter (not shown in the figure). The concentrator photovoltaic 1 can store electricity in battery 13 for daily use by the user. Battery 13 is electrically connected to the electric heating film 9, which is directly powered by the battery. When the battery power is insufficient, it can be powered by off-peak electricity.

[0046] The thermal storage tank 21 is buried underground at a depth not exceeding 0.1m and can be placed in a well-insulated area. The thermal storage tank 21 includes: a tank body, a second solid-solid phase change material layer 23, a thermal insulation material layer 22, and a thermal storage medium 24. The tank body is a welded steel plate tank. The thermal insulation material layer 22 is disposed on the inner wall of the tank body. The second solid-solid phase change material layer 23 is disposed on the inner wall of the thermal insulation material layer 22. The thermal storage medium 24 is filled in the space enclosed by the thermal insulation material layer 22.

[0047] It also includes: a thermal management system for managing the temperature of the concentrating photovoltaic unit 1. The water inlet of the concentrating photovoltaic unit 1 is the water inlet of the thermal management system, which is existing technology and can be referenced in [1] or [2]:

[0048] [1] Bai Haoliang, Wang Chen, Lu Jing, et al. Heat dissipation technology and development status of solar cells in concentrated photovoltaic systems [J]. Chemical Industry and Engineering Progress: 1-22.

[0049] [2]Sharma S,Sellami N,Tahir AA,et al.Performance Improvement of a CPVSystem:Experimental Investigation into Passive Cooling with Phase ChangeMaterials[J].Energies,2021,14(12).

[0050] The thermal conductivity of the phase change material in phase change material layer 7 is not less than 1 W·m. -1 ·K -1 The phase change temperature of the phase change material in phase change material layer 7 is greater than or equal to 25℃ and less than 30℃, and the latent heat of phase change of the phase change material in phase change material layer 7 is not less than 250kJ·kg -1 The phase change material layer 7 can be, for example, a hydrated inorganic salt compound.

[0051] The electric heating film 9 is a graphene heating film.

[0052] The phase transition temperature of the solid-solid phase change material in the first solid-solid phase change material layer 10 is not higher than 20℃, and the thermal conductivity of the solid-solid phase change material in the first solid-solid phase change material layer 10 is not higher than 0.2 W·m. -1 ·K -1 The phase transition temperature of the solid-solid phase change material in the second solid-solid phase change material layer 23 is less than or equal to 50℃, and the thermal conductivity of the solid-solid phase change material in the second solid-solid phase change material layer 23 is not higher than 0.2 W·m. -1 ·K -1 .

[0053] The thermal conductivity of insulation material 22 in the insulation layer is not higher than 0.04 W·m. -1 ·K-1 .

[0054] A third water pump 15 is installed on the pipeline between the outlet of the circulating water tank 12 and the first three-way valve 16. A second water pump 14 is installed on the pipeline between the third three-way valve 18 and the inlet of the heat storage pipeline 25. A first water pump 4 is installed on the pipeline between the third three-way valve 18 and the fourth three-way valve 19. The controller is electrically connected to the first water pump 4, the second water pump 14, and the third water pump 15 respectively. All three water pumps are Meilun Aite 1WZB-15Z type water pumps.

[0055] The heat storage pipe 25 is located below the heat exchange pipe 26. The distance between the heat storage pipe 25 and the bottom of the heat storage tank 21 is 40-50cm, and the heat exchange pipe 26 is 40-50cm from the top of the tank.

[0056] The solar collectors are plate collectors, and the concentrated photovoltaics are placed in areas with ample sunlight on the ground.

[0057] Example 3

[0058] The method of using the multi-energy coupled cascade heating system in Example 1 or Example 2 includes one of the following methods one to three:

[0059] Method 1 (Sunny weather without heating, such as summer daytime): Open the port of the first three-way valve 16 that connects to the outlet of the circulating water tank 12 and the port that connects to the second three-way valve 17; close the port of the first three-way valve 16 that connects to the inlet of the heat exchange pipe 26; open the port of the second three-way valve 17 that connects to the first three-way valve 16; open the port of the second three-way valve 17 that connects to the inlet of the concentrating photovoltaic 1 or the port that connects to the inlet of the solar collector 2. The ports connected to the outlet are opened; the port of the third three-way valve 18 connected to the outlet of the hot water storage tank 3 and the port connected to the inlet of the heat storage pipe 25 are opened, and the port of the third three-way valve 18 connected to the fourth three-way valve 19 is closed; all ports of the fourth three-way valve 19 are closed; the port of the fifth three-way valve 20 connected to the inlet of the circulating water tank 12 and the port connected to the outlet of the heat storage pipe 25 are opened, and the port of the fifth three-way valve 20 connected to the outlet of the user is closed.

[0060] Method 2 (Sunny weather requiring heating, such as winter daytime): Open all ports of the first three-way valve 16; open the port of the second three-way valve 17 connected to the first three-way valve 16, and open the port of the second three-way valve 17 connected to the inlet of the concentrating photovoltaic unit 1 or the inlet of the solar collector 2; open the port of the third three-way valve 18 connected to the outlet of the hot water storage tank 3 and the port connected to the fourth three-way valve 19; close the third three-way valve 16. 8 is a port for connecting to the inlet of the heat storage pipe 25; open the port of the fourth three-way valve 19 for connecting to the inlet of the user end, open the port of the fourth three-way valve 19 for connecting to the third three-way valve 18 and / or for connecting to the outlet of the heat exchange pipe 26; open the port of the fifth three-way valve 20 for connecting to the inlet of the circulating water tank 12 and for connecting to the outlet of the user end, and close the port of the fifth three-way valve 20 for connecting to the outlet of the heat storage pipe 25;

[0061] Method 3 (Weather without sunlight and requiring heating, such as winter nights): When it is cloudy and there is no sun, the solar collector cannot operate, and the heat storage tank is driven first. Open the port of the first three-way valve 16 that connects to the outlet of the circulating water tank 12 and the port that connects to the inlet of the heat exchange pipe 26; close the port of the first three-way valve 16 that connects to the second three-way valve 17; close all ports of the second three-way valve 17; close all ports of the third three-way valve 18; open the port of the fourth three-way valve 19 that connects to the outlet of the heat exchange pipe 26 and the port that connects to the inlet of the user end; close the port of the fourth three-way valve 19 that connects to the third three-way valve 18; open the port of the fifth three-way valve 20 that connects to the inlet of the circulating water tank 12 and the port that connects to the outlet of the user end; close the port of the fifth three-way valve 20 that connects to the outlet of the heat storage pipe 25.

[0062] In both modes 1 and 2, cold water can enter the thermal management system for preheating. However, when the controller receives a water temperature exceeding 30°C after passing through the second thermocouple, it opens the ports of the second three-way valve 17 (connected to the inlet of the solar collector 2) and the first three-way valve 16, and closes the port of the second three-way valve 17 (connected to the inlet of the concentrating photovoltaic unit 1). If the water temperature is too high, the water from the circulating tank will not flow through the thermal management system. In mode 2, when the controller receives a water temperature below 35°C after passing through the first thermocouple, the heat storage tank 21 is activated for supplementary heating, i.e., the port of the fourth three-way valve 19 (connected to the outlet of the heat exchange pipe 26) is opened. When the controller receives a water temperature above 40°C after passing through the first thermocouple, the heat storage tank is stopped, i.e., the port of the fourth three-way valve 19 (connected to the outlet of the heat exchange pipe 26) is closed, and the port of the fourth three-way valve 19 (connected to the third three-way valve 18) is opened.

[0063] In methods two and three, when the controller obtains through the third thermocouple that the temperature in the phase change material layer 7 is lower than the phase change temperature of the phase change material in the phase change material layer 7, the electric heating film 9 heats the phase change material layer 7 until the temperature in the phase change material layer 7 is greater than or equal to the phase change temperature of the phase change material in the phase change material layer 7, preferably 5 to 8°C higher than its phase change temperature, and then the electric heating film 9 stops heating.

[0064] When the indoor ambient temperature at the user's end is below 15℃, the electric heating film 9 is activated to heat the room until the indoor ambient temperature at the user's end reaches 20℃.

[0065] The heat storage medium is a phase change material. In Method 1, when the temperature of the heat storage medium in the heat storage tank is higher than its phase change temperature, the port of the third three-way valve 18 connected to the outlet of the hot water storage tank 3 and the port connected to the inlet of the heat storage pipe 25 are closed. This stops the heat storage in the heat storage tank. The heat storage medium can be paraffin wax, with a phase change temperature greater than 50℃ and less than 60℃, and a latent heat of phase change of not less than 200 kJ·kg⁻¹. -1 .

[0066] Example 4

[0067] Based on Example 1 or Example 2, the concentrated photovoltaic system monitors and rotates to ensure maximum light intake. For details on concentrated photovoltaic systems, please refer to the following literature: Chen Jin, Wang Yuehong, Chen Liquan, et al. Research on Regulation and Control Strategy of Concentrated Photovoltaic Sun Tracking System [J]. Measurement and Control Technology, 2018, 37(02):75-79.

[0068] Example 5

[0069] Based on winter conditions in Tianjin, the system operates according to Method 2 during the day and Method 3 at night, supplying heating to 1000m² of the multi-energy coupled cascade heating system. 2 Using phase change flooring as the standard, the area heat index method is employed to estimate the user-end heat load. The calculation formula is as follows:

[0070] Q h =q h ×S

[0071] Q in the formula h Design heat load for building heating, W; q h The design heat index for heating is taken as 70 W·m. -2 S represents the building's heating area, in meters. 2 The building heating design heat load can be obtained as: Q h =1000m 2 ×70W / m 2 × = 70000W;

[0072] The formula for calculating the heat loss of civil buildings is:

[0073]

[0074] Q in the formula y Annual heat consumption for building heating, kJ; t i The indoor temperature during the heating season is ℃, taken as 16℃; t j The outdoor average temperature during the heating season is expressed in °C, taken as -0.6 °C; t o Let n be the outdoor temperature during the heating season, in °C, taken as -7°C; n be the number of heating days, taken as 120 days. The annual heating consumption can be calculated as follows:

[0075]

[0076] Similarly, the daily heating consumption can be obtained as: Q y1 =4.4×10 6 kJ

[0077] Taking into account the heat loss during the entire heating process and the impact of cloudy and rainy weather on solar collectors, the heat distribution of the entire cascade heating system during the heating season is as follows: 90% of the heat is provided by solar energy, 10% by energy storage tanks, and 30% by electric heating.

[0078] Heating capacity per square meter of flat-plate solar collectors in Tianjin during winter: Q v ≈5kw·h

[0079] Considering a total loss of 33% during all flow periods in winter, the required effective area for flat-plate solar collector installation is: A e =124.57m 2

[0080] The formula for calculating the required mass of paraffin wax for the thermal storage tank is as follows:

[0081]

[0082] Where m1 is the mass of paraffin (as the heat storage medium 24) required for the heat storage tank, and c p The specific heat capacity of paraffin is kJ / kg·kJ. -1 t1 is the temperature of the cryogenic water entering the thermal storage tank, in °C; t2 is the phase transition temperature of paraffin in the thermal storage tank, in °C; r is the latent heat of phase transition of paraffin, in kJ·kg⁻¹. -1 The required mass of paraffin wax is calculated as follows:

[0083]

[0084] Considering the volume change that occurs during the phase transition of paraffin, the value with the lower density between the solid and liquid phases is selected for calculation, which is 770 kg·m³. -3 Therefore, the required volume of the thermal storage tank is 187.2 m³. 3 .

[0085] Therefore, it can be seen that 124.57m was laid. 2 The solar collector is designed to be 187.2m². 3 The thermal storage tank can provide heating loads to users throughout the year.

[0086] Example 6

[0087] Compared with traditional heating methods:

[0088] The annual coal consumption using coal as a heat source is:

[0089]

[0090] q in the formula net —The lower heating value of coal, 28000 kJ·kg -1 Substituting the data, we can obtain

[0091]

[0092] The formula for calculating the reduction of flue gas emissions is:

[0093]

[0094]

[0095] m fc =0.01m 煤

[0096] in the formula —Carbon dioxide emissions, in tons; —Sulfur dioxide emissions, t; m fc —Dust emissions, in tons; —Carbon emission factor, standard coal is taken as 0.726 kg carbon / kg coal; substituting the data yields

[0097]

[0098] m fc =0.01 × 18.714 = 0.18714 tons

[0099] In summary, the multi-energy coupled cascade heating system of this invention can save 18.714 tons of coal per year and reduce emissions of 49.817 tons of carbon dioxide, 0.3743 tons of sulfur dioxide, and 0.18714 tons of dust.

[0100] This invention compares the multi-energy coupled cascade heating system with novel heating methods:

[0101] Taking the emerging air source heat pump as an example, the formula for calculating the electrical energy required to provide heating throughout the year is as follows:

[0102]

[0103] Where E represents electrical energy consumption, and COP is the coefficient of performance of the air source heat pump.

[0104] Substituting the data, we get:

[0105]

[0106] In summary, the multi-energy coupled cascade heating system of this invention can save approximately 3.64 × 10⁻⁶ kWh of electricity. 7 kw·h.

[0107] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for using a multi-energy coupled cascade heating system based on solar-guided photovoltaics, characterized in that, The multi-energy coupled cascade heating system based on solar photovoltaic (PV) includes: a concentrating photovoltaic (PV) unit (1), a solar collector (2), a hot water storage tank (3), a circulating water tank (12), a thermal storage tank (21), and a user terminal. The outlet of the circulating water tank (12) is connected to the first port of a first three-way valve (16), the second port of the first three-way valve (16) is connected to the first port of a second three-way valve (17), the second port of the second three-way valve (17) is connected to the inlet of the concentrating PV unit (1), the outlet of the concentrating PV unit (1) and the third port of the second three-way valve (17) are respectively connected to the inlet of the solar collector (2). The outlet of the hot water storage tank (3) is connected to the inlet of the hot water storage tank (3); the hot water storage tank (21) is equipped with a hot water storage pipe (25) and a heat exchange pipe (26) for exchanging heat. The hot water storage tank (21) around the hot water storage pipe (25) and the heat exchange pipe (26) is filled with a hot water storage medium (24). The outlet of the hot water storage tank (3) is connected to one port of a third three-way valve (18). The other two ports of the third three-way valve (18) are connected to the inlet of the hot water storage pipe (25) and one port of a fourth three-way valve (19), respectively. The other two ports of the fourth three-way valve (19) are connected to the outlet of the heat exchange pipe (26) and the inlet of the user end, respectively. The inlet of the pipeline (26) is connected to the third port of the first three-way valve (16), the outlet of the heat storage pipeline (25) is connected to the first port of a fifth three-way valve (20), the second port of the fifth three-way valve (20) is connected to the inlet of the circulating water tank (12), and the third port of the fifth three-way valve (20) is connected to the outlet of the user end; the heat storage tank (21) is buried underground at a depth not exceeding 0.1m; a first thermocouple is installed on the pipeline between the inlet of the heating pipeline (8) and the fourth three-way valve (19), and a second thermocouple is installed on the pipeline between the second three-way valve (17) and the first three-way valve (16), and the user end... The end includes: a phase change material layer (7), in which a third thermocouple is provided; the controller is electrically connected to the first thermocouple, the second thermocouple, the third thermocouple, the first three-way valve (16), the second three-way valve (17), the third three-way valve (18), the fourth three-way valve (19) and the fifth three-way valve (20); the use method of the multi-energy coupling cascade heating system based on solar photovoltaic includes the following three methods: Method 1: open the port of the first three-way valve (16) for connecting with the outlet of the circulating water tank (12) and the port for connecting with the second three-way valve (17), and close the port of the first three-way valve (16) for connecting with the inlet of the heat exchange pipe (26);Open the port of the second three-way valve (17) for connection with the first three-way valve (16); open the port of the second three-way valve (17) for connection with the inlet of the concentrating photovoltaic (1) or for connection with the inlet of the solar collector (2); open the port of the third three-way valve (18) for connection with the outlet of the hot water storage tank (3) and for connection with the inlet of the heat storage pipe (25); close the port of the third three-way valve (18) for connection with the fourth three-way valve (19); close all ports of the fourth three-way valve (19); open the port of the fifth three-way valve (20) for connection with the inlet of the circulating water tank (12) and for connection with the outlet of the heat storage pipe (25); close the fifth three-way valve. Valve (20) is used to connect to the outlet of the user end; Method 2: Open all ports of the first three-way valve (16); open the port of the second three-way valve (17) used to connect to the first three-way valve (16), open the port of the second three-way valve (17) used to connect to the inlet of the concentrating photovoltaic (1) or the port used to connect to the inlet of the solar collector (2); open the port of the third three-way valve (18) used to connect to the outlet of the hot water storage tank (3) and the port used to connect to the fourth three-way valve (19), close the port of the third three-way valve (18) used to connect to the inlet of the heat storage pipe (25); open the port of the fourth three-way valve (19) used to connect to the inlet of the user end, open the fourth three-way valve (19) The port of valve (19) is used to connect with the third three-way valve (18) and / or to connect with the outlet of the heat exchange pipe (26); the port of valve (20) used to connect with the inlet of the circulating water tank (12) and the port used to connect with the outlet of the user are opened, and the port of valve (20) used to connect with the outlet of the heat storage pipe (25) is closed; when the controller obtains that the temperature of the water passing through the first thermocouple is lower than 35°C, the port of valve (19) used to connect with the outlet of the heat exchange pipe (26) is opened; when the controller obtains that the temperature of the water passing through the first thermocouple is higher than 40°C, the port of valve (19) used to connect with the outlet of the heat exchange pipe (26) is closed. Method 3: Open the port of the first three-way valve (16) for connecting with the outlet of the circulating water tank (12) and the port for connecting with the inlet of the heat exchange pipe (26), close the port of the first three-way valve (16) for connecting with the port of the second three-way valve (17); close all ports of the second three-way valve (17); close all ports of the third three-way valve (18); open the port of the fourth three-way valve (19) for connecting with the outlet of the heat exchange pipe (26) and the port for connecting with the inlet of the user end, close the port of the fourth three-way valve (19) for connecting with the third three-way valve (18);Open the port of the fifth three-way valve (20) for connecting to the inlet of the circulating water tank (12) and the port for connecting to the outlet of the user end; close the port of the fifth three-way valve (20) for connecting to the outlet of the heat storage pipe (25).

2. The method of use according to claim 1, characterized in that, Also includes: Battery (13), which is electrically connected to the concentrated photovoltaic (1).

3. The method of use according to claim 2, characterized in that, The user terminal includes: a phase change floor (5), the phase change floor (5) includes: a wear-resistant layer (6), the phase change material layer (7), a heating pipe (8), an electric heating film (9), a first solid-solid phase change material layer (10) and a fireproof layer (11). The wear-resistant layer (6), the phase change material layer (7), the electric heating film (9), the first solid-solid phase change material layer (10) and the fireproof layer (11) are parallel and connected sequentially from top to bottom. The heating pipe (8) passes through the phase change material layer (7). The inlet of the heating pipe (8) serves as the inlet of the user terminal, and the outlet of the heating pipe (8) serves as the outlet of the user terminal.

4. The method of use according to claim 3, characterized in that, The battery (13) is electrically connected to the electric heating film (9).

5. The method of use according to claim 4, characterized in that, The heat storage tank (21) includes: a tank body, a second solid-solid phase change material layer (23), a heat insulation material layer (22), and the heat storage medium (24). The heat insulation material layer (22) is disposed on the inner wall of the tank body, the second solid-solid phase change material layer (23) is disposed on the inner wall of the heat insulation material layer (22), and the heat storage medium (24) is filled in the space enclosed by the heat insulation material layer (22).

6. The method of use according to claim 5, characterized in that, Also includes: Thermal management system for managing the temperature of concentrated photovoltaic (1) units.

7. The method of use according to claim 5, characterized in that, The thermal conductivity of the phase change material in the phase change material layer (7) is not less than 1 W·m. -1 ·K -1 .

8. The method of use according to claim 5, characterized in that, The phase change temperature of the phase change material in the phase change material layer (7) is greater than or equal to 25°C and less than 30°C, and the latent heat of phase change of the phase change material in the phase change material layer (7) is not less than 250 kJ·kg⁻¹. -1 .

9. The method of use according to claim 5, characterized in that, The electric heating film (9) is a graphene heating film.

10. The method of use according to claim 5, characterized in that, The phase transition temperature of the solid-solid phase change material in the first solid-solid phase change material layer (10) is not higher than 25℃, and the thermal conductivity of the solid-solid phase change material in the first solid-solid phase change material layer (10) is not higher than 0.2 W·m. -1 ·K -1 The phase transition temperature of the solid-solid phase change material in the second solid-solid phase change material layer (23) is less than or equal to 50℃, and the thermal conductivity of the solid-solid phase change material in the second solid-solid phase change material layer (23) is not higher than 0.2 W·m. -1 ·K -1 The thermal conductivity of the insulation material in the insulation layer (22) is not higher than 0.04 W·m. -1 ·K -1 A third water pump (15) is installed on the pipeline between the outlet of the circulating water tank (12) and the first three-way valve (16). A second water pump (14) is installed on the pipeline between the third three-way valve (18) and the inlet of the heat storage pipeline (25). A first water pump (4) is installed on the pipeline between the third three-way valve (18) and the fourth three-way valve (19). The controller is electrically connected to the first water pump (4), the second water pump (14) and the third water pump (15) respectively.

11. The method of use according to claim 7, characterized in that, In methods one and two, when the controller obtains that the temperature of the water passing through the second thermocouple exceeds 30°C, it opens the port of the second three-way valve (17) for connecting with the inlet of the solar collector (2) and the port of the second three-way valve (17) for connecting with the first three-way valve (16), and closes the port of the second three-way valve (17) for connecting with the inlet of the concentrating photovoltaic (1); in methods two and three, when the controller obtains that the temperature in the phase change material layer (7) is lower than the phase change temperature of the phase change material in the phase change material layer (7) through the third thermocouple, the electric heating film (9) heats the phase change material layer (7) until the temperature in the phase change material layer (7) is greater than or equal to the phase change temperature of the phase change material in the phase change material layer (7).

12. The method of use according to claim 7, characterized in that, When the indoor ambient temperature at the user end is lower than 15°C, the electric heating film (9) is activated to heat until the indoor ambient temperature at the user end reaches 20°C. The heat storage medium (24) is a phase change material. In the first method, when the temperature of the heat storage medium (24) in the heat storage tank (21) is higher than its phase change temperature, the port of the third three-way valve (18) used to connect with the outlet of the hot water storage tank (3) and the port used to connect with the inlet of the heat storage pipe (25) are closed.

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