CN115468207B - Building cascade heating system and method using photovoltaic power generation and sand high-temperature heat storage - Google Patents
Building cascade heating system and method using photovoltaic power generation and sand high-temperature heat storage Download PDFInfo
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- CN115468207B CN115468207B CN202211016258.1A CN202211016258A CN115468207B CN 115468207 B CN115468207 B CN 115468207B CN 202211016258 A CN202211016258 A CN 202211016258A CN 115468207 B CN115468207 B CN 115468207B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D11/00—Central heating systems using heat accumulated in storage masses
- F24D11/02—Central heating systems using heat accumulated in storage masses using heat pumps
- F24D11/0214—Central heating systems using heat accumulated in storage masses using heat pumps water heating system
- F24D11/0221—Central heating systems using heat accumulated in storage masses using heat pumps water heating system combined with solar energy
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D11/00—Central heating systems using heat accumulated in storage masses
- F24D11/02—Central heating systems using heat accumulated in storage masses using heat pumps
- F24D11/0214—Central heating systems using heat accumulated in storage masses using heat pumps water heating system
- F24D11/0228—Central heating systems using heat accumulated in storage masses using heat pumps water heating system combined with conventional heater
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D18/00—Small-scale combined heat and power [CHP] generation systems specially adapted for domestic heating, space heating or domestic hot-water supply
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D19/00—Details
- F24D19/10—Arrangement or mounting of control or safety devices
- F24D19/1006—Arrangement or mounting of control or safety devices for water heating systems
- F24D19/1009—Arrangement or mounting of control or safety devices for water heating systems for central heating
- F24D19/1045—Arrangement or mounting of control or safety devices for water heating systems for central heating the system uses a heat pump and solar energy
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D19/00—Details
- F24D19/10—Arrangement or mounting of control or safety devices
- F24D19/1096—Arrangement or mounting of control or safety devices for electric heating systems
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
- F28D20/0052—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using the ground body or aquifers as heat storage medium
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D2101/00—Electric generators of small-scale CHP systems
- F24D2101/40—Photovoltaic [PV] modules
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B10/00—Integration of renewable energy sources in buildings
- Y02B10/20—Solar thermal
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- Thermal Sciences (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
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- Sustainable Energy (AREA)
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Abstract
本发明公开了一种利用光伏发电与沙土高温储热的建筑梯级供热系统和方法。所述建筑梯级供热系统包括光伏发电子系统、与该光伏发电子系统分别连接的沙土储热子系统和地源热泵子系统、与所述沙土储热子系统和地源热泵子系统均连接的用户供热水循环子系统；其中，沙土储热子系统包括通过空气管道依次连接的电加热器Ⅰ、沙土‑空气换热室、空气‑水换热器和风机，风机的出口与电加热器Ⅰ的空气入口连接，使得空气管道构成闭式循环回路；沙土‑空气换热室中填充沙土，用于存储已加热的空气中的热能。本发明最大化地将光伏在无法并网时产生的电能有效用于建筑供热，并与地源热泵结合，实现建筑供热的能源梯级利用，提高可再生能源的使用比例。
The present invention discloses a building cascade heating system and method using photovoltaic power generation and sand high-temperature heat storage. The building cascade heating system includes a photovoltaic power generation subsystem, a sand heat storage subsystem and a ground source heat pump subsystem respectively connected to the photovoltaic power generation subsystem, and a user hot water circulation subsystem connected to the sand heat storage subsystem and the ground source heat pump subsystem; wherein the sand heat storage subsystem includes an electric heater I, a sand-air heat exchange chamber, an air-water heat exchanger and a fan connected in sequence through an air duct, and the outlet of the fan is connected to the air inlet of the electric heater I, so that the air duct forms a closed circulation loop; the sand-air heat exchange chamber is filled with sand to store the heat energy in the heated air. The present invention maximizes the effective use of the electric energy generated by photovoltaics when it cannot be connected to the grid for building heating, and combines with a ground source heat pump to achieve cascade utilization of energy for building heating and increase the proportion of renewable energy used.
Description
Technical Field
The invention belongs to the field of renewable energy heat supply, and particularly relates to a building cascade heat supply system and method utilizing photovoltaic power generation and sand high-temperature heat storage.
Background
Photovoltaic is a power generation system that uses the photovoltaic effect of semiconductor materials to convert solar radiation energy into electrical energy. Solar energy is a clean, safe and renewable energy source. Photovoltaic is easily influenced by factors such as weather, seasons, climate and the like, generated energy is unstable, and power consumption of a power grid frequently fluctuates, so that a light rejection phenomenon that large-area photovoltaic cannot be connected to the grid frequently occurs. To alleviate this problem, photovoltaic systems are often configured to mount a battery to ensure stability on the power side. However, the capacity and life of the battery are limited, and a large capacity battery means a higher initial investment.
The heat storage in the building cascade heat supply system generally converts energy from renewable energy sources into heat energy in advance and stores the heat energy, and is used for peak shaving in a heat supply season, or directly used as a heat supply source, so that the use proportion of fossil energy or electric energy can be reduced, and when the heat source is used as a heat source of a ground source heat pump, the working efficiency of the heat pump can be improved, and the heat supply cost can be reduced.
In order to reduce the capacity and investment of the storage battery and improve the electric energy utilization rate of the photovoltaic system when grid connection cannot be achieved, the photovoltaic system has a patent for converting electric energy generated by the photovoltaic into heat energy to be stored for building heat supply. For example, chinese patent literature discloses a zero-emission heating system (application publication No. CN113819510 a) of coupling solar energy with geothermal energy in a middle-deep layer, the system includes a capacity unit, an energy storage unit and an energy consumption unit, the capacity unit has a middle-deep layer buried pipe heat exchange device, solar photo-thermal heat collection paper and a photovoltaic power generation system, the energy storage unit has a phase-change boiler, and the electric energy is converted into thermal energy for storage.
Patents including those mentioned above generally employ a heat storage water tank or a heat storage tank filled with a phase change material as a heat storage device. However, the phase change material has high cost, which is unfavorable for large-scale heat storage; on the other hand, the specific heat capacity of water is very large, but at standard atmospheric pressure, the maximum heat storage temperature can only reach 100 ℃, and the total heat storage capacity is limited. Therefore, it is a difficult problem to store as much as possible of the electrical energy generated by the photovoltaic cells when they cannot be connected to the grid at a low cost, consume as little fossil energy as possible, and provide clean and stable heat supply for the building.
Disclosure of Invention
Aiming at the defects or improvement demands of the prior art, the invention provides a building cascade heat supply system and a building cascade heat supply method utilizing photovoltaic power generation and sand high-temperature heat storage, which aim to maximally effectively utilize electric energy generated by photovoltaic when grid connection cannot be realized, and the building cascade heat supply system is combined with a ground source heat pump to realize the cascade utilization of energy sources of building heat supply, improve the use proportion of renewable energy sources and realize the social aim of carbon neutralization in the heat supply field in a boosting way.
In order to achieve the above object, according to one aspect of the present invention, there is provided a building cascade heat supply system for storing heat at a high temperature by using photovoltaic power generation and sand, comprising a photovoltaic power generation subsystem, a sand heat storage subsystem and a ground source heat pump subsystem which are respectively connected with the photovoltaic power generation subsystem, and a user hot water supply circulation subsystem which is connected with both the sand heat storage subsystem and the ground source heat pump subsystem; the sand heat storage subsystem comprises an electric heater I, a sand-air heat exchange chamber, an air-water heat exchanger and a fan which are sequentially connected through an air pipeline, wherein an outlet of the fan is connected with an air inlet of the electric heater I, so that the air pipeline forms a closed circulation loop; the electric heater I is connected with the photovoltaic power generation subsystem and is used for converting electric energy into heat energy and heating air; the sand-air heat exchange chamber is filled with sand and is used for storing heat energy in heated air at a high temperature; the air-water heat exchanger is used for transferring heat stored in the sand-air heat exchange chamber to the user hot water supply circulation subsystem so as to realize heat storage and heat supply.
Preferably, the sand-air heat exchange chamber comprises a sand-air heat exchange coil inside; the stacking height of the sand is enough to cover the air heat exchange coil pipe completely; the air heat exchange coil comprises an air supply main pipe, an air return main pipe and a plurality of branch pipes which are vertically arranged; the air supply main pipe and the return air main pipe are horizontally arranged, the upper ends of all branch pipes are connected with the air supply main pipe, and the lower ends of all branch pipes are connected with the return air main pipe.
Preferably, the sand-air heat exchange chamber is arranged underground, the top is spaced a preset distance from the ground, and heat insulation layers are paved on the inner surfaces of all chamber walls of the sand-air heat exchange chamber.
Preferably, the top of the sand-air heat exchange chamber is provided with an air supply outlet and an air outlet, and the air supply outlet and the air outlet are respectively connected with an air exhaust well and the ground through an air supply well; the upper end of the air supply well is connected with a ground air feeder, and the upper end of the air exhaust well is connected with an outdoor air outlet through an air pipe; the side surface of the sand-air heat exchange chamber is provided with an access door and a sand discharge port; the access door is higher than the accumulation height of the sand inside; the sand discharge port is arranged at the bottom of the side surface of the sand-air heat exchange chamber; a personnel movable platform and an overhaul ladder are arranged in the sand-air heat exchange chamber.
Preferably, the electric heater I comprises an air cavity and an air heating wire; both ends of the heating wire for air are electrically connected with the photovoltaic power generation system; the air-water heat exchanger comprises an air cavity and a water coil; both ends of the inlet and outlet of the water coil pipe are connected with a user hot water supply circulating system.
Preferably, the heat storage temperature of the sand-air heat exchange chamber is above 400 ℃.
Preferably, a thermometer is arranged in the sandy soil at the air outlet of the electric heater I.
Preferably, the photovoltaic power generation subsystem comprises a solar photovoltaic panel, a power generation circuit and a heating circuit, wherein the power generation circuit is sequentially connected with a MPPI controller, a storage battery and an inverter through wires; the other end of the inverter is connected to a local power grid through an electric wire, and the heating circuit is respectively connected with an electric heater I in the sand heat storage subsystem and an electric heater II in the ground source heat pump subsystem through an electric wire;
The user hot water supply circulating system comprises user heat equipment, an electric heating boiler and a user side circulating water pump.
Preferably, the storage battery is electrically connected with the fan, the heat pump unit, the ground source heat pump circulating water pump, the user side circulating water pump, the heat storage water pump and the electric heating boiler.
Preferably, the ground source heat pump subsystem comprises a heat pump unit, a ground source heat pump circulating water pump, a heat storage water pump, a plurality of ground buried pipes, an electric heater II, a heat pump side water supply valve, a heat pump side water return valve, a heat storage water supply valve and a heat storage water return valve; wherein, the electric heater II is internally provided with a heating wire for water which is electrically connected with a photovoltaic power generation system; the ground buried pipe, the heat pump side water supply valve, the ground source heat pump circulating water pump, the heat pump unit and the heat pump side backwater valve are sequentially connected to form a water circulation loop; the buried pipe, the heat storage backwater valve, the heat storage water pump, the electric heater II and the heat storage water supply valve are sequentially connected to form another water circulation loop.
According to another aspect of the invention, a heat supply method is provided, and heat supply is sequentially performed according to the priority order of the sand heat storage subsystem, the ground source heat pump subsystem and the electric heating boiler in the user hot water circulation subsystem.
In general, the above technical solutions conceived by the present invention can achieve at least the following advantageous effects compared to the prior art.
(1) The sand heat storage subsystem disclosed by the invention uses sand as a heat storage material, has the advantages of high density, high melting point, low cost and easiness in obtaining, can realize large-scale heat storage in a small volume and high-temperature state at low cost, and does not need to take strict sealing measures on the shell of the heat storage container; air is used as a heat medium for heat transfer, the specific heat capacity is small, and the heat can be stored maximally without absorbing excessive heat; compared with a circulating pipeline taking water or heat conducting oil as a heating medium, the air circulating pipeline has the advantages of small flowing resistance, small power energy consumption and simple and convenient pipeline installation, and can be applied to regional building heat supply on a large scale. Meanwhile, the electric energy generated by the photovoltaic power generation system when grid connection cannot be realized is converted into high-temperature heat energy through the electric heating wire for air, and the high-temperature heat energy is stored in soil around sandy soil and buried pipes, so that the high-temperature heat energy can be used for clean heat supply of buildings, the waste of the photovoltaic electric energy when grid connection cannot be realized is effectively reduced, the utilization rate of solar energy is improved, and the capacity of a photovoltaic storage battery and the initial investment of the photovoltaic storage battery can be reduced.
(2) The invention uses two technologies of heat storage and ground source heat pump for building heat supply, and carries out heat storage in a period of time before a heat supply season and a heat supply season; the energy cascade utilization strategy is adopted when the building supplies heat, and the heat is supplied according to the priority order of the sand-ground source heat pump-electric heating boiler, so that the operation efficiency of the ground source heat pump can be improved, the arrangement scale and initial investment of the buried pipes are reduced, the renewable energy proportion in the total energy consumption of the building heat supply is improved, and the use amount of fossil energy is reduced.
Drawings
FIG. 1-schematic diagram of a building cascade heating system utilizing photovoltaic power generation and sand high-temperature heat storage provided by an embodiment of the invention;
fig. 2-a schematic side structural diagram of a sand-air heat exchange chamber in a building cascade heating system using photovoltaic power generation and sand high-temperature heat storage according to an embodiment of the present invention;
Fig. 3-a schematic diagram of a multi-group arrangement shaft side of air heat exchange coils in a building cascade heat supply system utilizing photovoltaic power generation and sand high-temperature heat storage according to an embodiment of the invention.
The same reference numbers are used throughout the drawings to reference like elements or structures, wherein:
1-a solar photovoltaic panel; 2-MPPI controllers; 3-a storage battery; a 4-inverter; 5-heating wire for air; 6-heating wire for water; 7-an electric heater I; 8-sand-air heat exchange chamber; 9-sandy soil; 10-an air heat exchange coil; 11-an insulating layer; 12-an air-water heat exchanger; 13-a fan; 14-an air duct; 15-a heat pump unit; 16-a ground source heat pump circulating water pump; 17-burying a pipe; 18-a heat storage water pump; 19-an electric heater II; 20-user heat use device; 21-water coil; 22-a user side circulating water pump; 23-an electric heating boiler; 24-generating a power switch; 25-heating switch; 26-an electric heating wire control switch for air; 27-a heating wire control switch for water; 28-a heat pump side water supply valve; 29-a heat pump side backwater valve; 30-a heat storage water supply valve; 31-a heat storage backwater valve; 32-thermometer; 33-an air supply port; 34-an exhaust outlet; 35-an air supply well; 36-exhaust shaft; 37-floor blower; 38-an outdoor air outlet; 39-access door; 40-sand discharging port; 41-personnel activity platform; 42-railing; 43-maintenance ladder.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
Referring to fig. 1, a building cascade heat supply system using photovoltaic power generation and sand high temperature heat storage comprises a photovoltaic power generation subsystem, a sand heat storage subsystem, a ground source heat pump subsystem and a user hot water supply circulation subsystem. The sand heat storage subsystem comprises an electric heater I7, a sand-air heat exchange chamber 8, an air-water heat exchanger 12, a fan 13 and an air pipeline 14. The interior of the electric heater I7 comprises an air cavity and an air heating wire 5. Both ends of the heating wire 5 for air are electrically connected with a photovoltaic power generation system. The interior of the air-water heat exchanger 12 includes an air chamber and a water coil 21. Both inlet and outlet ends of the water coil 21 are connected with a user hot water supply circulating system. The ground source heat pump system has a heat pump unit 15 connected to the user supplied hot water circulation system.
The photovoltaic power generation subsystem comprises a solar photovoltaic panel 1, a power generation circuit and a heating circuit. The power generation line is sequentially connected with a power generation switch 24, an MPPI controller 2, a storage battery 3 and an inverter 4 through wires. The battery 3 is electrically connected to the blower 13, the heat pump unit 15, the ground source heat pump water circulating pump 16, the user side water pump 22, the heat storage water pump 18, and the electric heating boiler 23. The other end of the inverter 4 is connected to a local grid by means of wires. MPPI the controller 2 is used for detecting the voltage and the current in the power generation line, calculating the output power of the solar photovoltaic panel, and adjusting the output power to charge the storage battery 3 at the maximum output power. The storage battery 3 is used for storing electric energy generated by the solar photovoltaic panel 1 as chemical energy and outputting the electric energy in the form of electric energy at any time. The inverter 4 is used to convert direct current generated by the solar photovoltaic panel 1 into alternating current. The heating circuit of the photovoltaic power generation system is connected with a heating switch 25, an air heating wire 5, an air heating wire control switch 26, a water heating wire 6 and a water heating wire control switch 27 through wires. The air heating wire 5 is connected in series with the air heating wire control switch 26, and the water heating wire 6 is connected in series with the water heating wire control switch 27, and then both are connected in parallel.
The ground source heat pump subsystem comprises a heat pump unit 15, a ground source heat pump circulating water pump 16, a heat storage water pump 18, a plurality of buried pipes 17, an electric heater II 19, a heat pump side water supply valve 28, a heat pump side water return valve 29, a heat storage water supply valve 30 and a heat storage water return valve 31 which are sequentially arranged. The electric heater II 19 is internally provided with a heating wire 6 for water, which is electrically connected with a photovoltaic power generation system. The buried pipe 17, the heat pump side water supply valve 28, the ground source heat pump circulating water pump 16, the heat pump unit 15 and the heat pump side water return valve 29 are sequentially connected and form a water circulation loop. The buried pipe 17, the heat-storage backwater valve 31, the heat-storage water pump 18, the electric heater II 19 and the heat-storage water supply valve 30 are sequentially connected and form another water circulation loop.
The user hot water supply circulation subsystem comprises a user heat equipment 20, an electric heating boiler 23 and a user side water pump 22, and is connected with a water inlet and a water outlet of the condenser side of the heat pump unit 15 through water pipes.
The sandy soil heat storage subsystem sequentially connects the electric heater I7, the sandy soil-air heat exchange chamber 8, the air-water heat exchanger 12 and the fan 13 through an air pipeline 14, and an outlet of the fan 13 is connected with an air inlet of the electric heater I7 to form an air closed circulation pipeline. The sand-air heat exchange chamber 8 internally comprises sand 9 and an air heat exchange coil 10. The sand 9 has a certain pile height so that the air heat exchanging coil 10 is completely covered. The air heat exchange coil 10 comprises an air supply main pipe, an air return main pipe and a plurality of branch pipes which are vertically arranged. The air supply main pipe and the return air main pipe are horizontally arranged. The upper ends of all branch pipes are connected with the air supply main pipe, and the lower ends are connected with the return air main pipe.
In the sand heat storage subsystem, sand is used as a heat storage material because the stacking density of the sand is about 1300-1600kg/m 3, the specific heat capacity is 0.92 kJ/(kg·deg.C), and the melting point is as high as about 1650 deg.C. Compared with the same volume of water, the heat storage capacity of the water-based heat storage type heat storage device is only 28.4-35.0% of water below 100 ℃. However, when water is used as the heat storage material, it is limited by its boiling point, its maximum heat storage temperature is only 100 ℃, and sand can store heat in a high temperature form. When the ambient temperature is 20 ℃, the heat storage amount in the sandy soil at 400 ℃ is 1.35-1.67 times of the same volume of 100 ℃ water. Therefore, the high-temperature sand is more suitable for being used as a heat storage material for large-scale heat storage engineering, on one hand, the heat storage amount of the high-temperature sand is more than that of water, and on the other hand, compared with a phase change material, the sand is cheaper and more available. Moreover, the outer shell of the sand heat storage container does not need to be made into strict sealing measures, and the outer shell of the water and phase change material heat storage easy outer shell needs to be tightly sealed to prevent liquid leakage.
In the photovoltaic power generation subsystem, the heating wire 5 for air is used as an energy conversion device, and the heating wire 5 for air can convert electric energy into heat energy to be transferred to air and heat the air to a high temperature. Compared with water or heat conducting oil serving as a heat transfer heat medium, the air in the sand high-temperature heat storage system can be heated to a very high temperature without phase change, sand can be further raised to a high temperature of hundreds of degrees centigrade, the specific heat capacity of the air is small, the heat storage capacity in a heat medium circulation pipeline is small, and more heat generated by the air by the heating wire 5 can be transferred to the sand 9 for storage.
In the embodiment of the invention, the sand-air heat exchange chamber 8 is preferably arranged underground, and the top of the sand-air heat exchange chamber is at a certain distance from the ground. The arrangement is because when the sand-air heat exchange chamber 8 is arranged in the underground space, only heat transfer in a heat conduction mode exists between the outer shell of the sand-air heat exchange chamber 8 and surrounding soil, the temperature of the underground soil is constant, the thickness and initial investment of the heat preservation layer 11 on the inner surface of the chamber wall are reduced, and the occupation of the ground space can be reduced in large-scale application. It will be appreciated by those skilled in the art that the sand-air heat exchange chamber 8 may also be disposed above the ground.
Referring to fig. 2, in the embodiment, an air supply port 33 and an air exhaust port 34 are arranged at the top of the sand-air heat exchange chamber 8, and the air supply port 33 and the air exhaust port 34 are respectively connected with an air exhaust well 36 and the ground through an air supply well 35. The upper end of the air supply well 35 is connected with a ground air feeder 37, and the upper end of the air exhaust well 36 is connected with an outdoor air outlet 38 through an air pipe. The side of the sand-air heat exchange chamber 8 is provided with an access door 39 and a sand discharge port 40. The access door 39 is above the stack height of the interior sand 9. The sand discharge port 40 is arranged at the bottom of the side surface of the sand-air heat exchange chamber 8. The upper part of the sand-air heat exchange chamber 8 is provided with a personnel movable platform 41, and the height of the personnel movable platform is consistent with the bottom of the access door 39. The guard rails 42 are arranged on two sides of the personnel movable platform 41 to prevent personnel from falling off. The personnel movable platform 41 is connected with a vertically downward overhaul ladder 43 which can be directly communicated with the bottom of the sand-air heat exchange chamber 8.
In particular, when the sand-air heat exchange chamber 8 is operating normally, both the air supply opening 33 and the air discharge opening 34 are closed. During the construction phase of the sand-air heat exchange chamber 8, sand 9 may be transported into the sand-air heat exchange chamber 8 through the air supply shaft 35 and the air exhaust shaft 36, and the sand discharge port 40 may be kept closed. When the sand-air heat exchange chamber 8 needs to be overhauled, before the access door 39 is opened, the ground air blower 37, the air supply opening 33 and the air outlet 34 are required to be opened, normal-temperature air outside the ground is sent into the sand-air heat exchange chamber 8 for cooling, and after the indoor temperature of the sand-air heat exchange chamber 8 is reduced to a proper temperature, an overhauler can open the access door 39 for entering. When it is desired to service the air heat exchange coil 10 covered under the sand 9, it is necessary to open the sand discharge port 40 to discharge the sand 9.
In specific implementation, the pipe diameters of the air supply main pipe and the return air main pipe of the air heat exchange coil 10 in the sand-air heat exchange chamber 8 are far larger than those of the branch pipes, and the arrangement of the main pipes ensures that the branch pipes are connected in the same form, so that the air flow resistance of the branch pipes is approximate, and the air flow rate in the branch pipes is approximate. Meanwhile, the number of the branch pipes is enough to ensure the sufficient heat exchange between the air and the sandy soil. When the stacking width of the sand 9 is large and the uniform heat storage of the sand cannot be met by a single group of air heat exchange coils 10, a plurality of groups of air heat exchange coils 10 which are connected in parallel and distributed in parallel along the width direction of the sand 9 are arranged in the sand air heat exchange chamber 8. Therefore, the temperature of the sandy soil can be increased or decreased uniformly, and the heat exchange efficiency of the air and the sandy soil is improved.
In the embodiment of the invention, the heat storage temperature of the sand-air heat exchange chamber 8 is above 400 ℃. All air pipelines 14 except the sand-air heat exchange chamber 8, the outer shell of the electric heater I7 and the outer shell of the air-water heat exchanger 12 are paved with heat insulation materials which can not burn when the heat storage temperature reaches a design value. The air pipe 14, the fan 13 and each part inside the fan 13 are made of materials which can work normally when the heat storage temperature reaches the design value.
In the embodiment of the invention, the water pipes at the two ends of the inlet and outlet of the user heating equipment 20, the air outlet of the electric heater I7, the water outlet of the electric heater II 19 and the sand 9 are provided with thermometers.
The embodiment of the invention also provides a heat supply method utilizing the building cascade heat supply system, which sequentially supplies heat according to the priority order of the heat supply of the sand heat storage subsystem, the heat supply of the ground source heat pump subsystem and the heat supply of the electric heating boiler in the user hot water circulation subsystem.
Specifically, the working conditions of the building cascade heat supply system utilizing photovoltaic power generation and sand high-temperature heat storage provided by the embodiment of the invention are divided into heat storage working conditions of a few weeks before a heat supply season, heat storage working conditions of a non-heat supply season, heat supply Ji Shan heat supply working conditions and heat supply season composite heat supply working conditions. The specific implementation mode is as follows:
Heat storage conditions several weeks before the heating season: in the first few weeks of the heating season, when the photovoltaic cannot normally generate power in a grid-connected mode, the power generation switch 24 is turned off, the heating switch 25 is turned on, the heating wire control switch 27 for water is turned off, the heating wire control switch 26 for air is turned on, and the fan 13 is started. At the moment, the electric energy generated by the solar photovoltaic panel 1 is converted into heat energy to heat the air in the electric heater I7, and the air temperature at the air outlet of the electric heater I7 is kept at 650 ℃ by controlling the air quantity of the fan 13. The high temperature air enters the sand-air heat exchange chamber 8 along the air pipeline 14 under the power of the fan 13, and heat is transferred to the sand through the air heat exchange coil 1010. As the air is continuously circulated, when the average temperature of the sandy soil is heated to 400 ℃, the heat storage amount of the sandy soil is considered to be saturated, at the moment, the fan 13 is turned off, the heating wire control switch 26 for air is turned off, the heating wire control switch 27 for water is turned on, and the heat storage water supply and return valves 30 and 31 are both opened to start the heat storage water pump 18. At this time, the electric energy generated by the solar photovoltaic panel 1 is converted into heat energy to heat the water in the electric heater II 19, and the heat is transported and stored in the soil around the buried pipe 17 by the heat storage water pump 18. When the photovoltaic power generation system can normally generate power in a grid-connected mode, the power generation switch 24 is closed, the heating switch 25 is opened, the heat storage water supply and return valves 30 and 31 and the heat storage water pump 18 are closed, and electric energy generated by the solar photovoltaic panel 1 is firstly stored in the storage battery 3. After the storage battery 3 is full of electricity, the electric energy generated by the solar photovoltaic panel 1 is converted into alternating current and is transmitted to a local power grid.
Heat storage conditions in non-heating season: in the period from the end of the heating season to several weeks before the next year of the heating season, when the photovoltaic cannot normally generate power in a grid-connected mode, the power generation switch 24 is turned off, the heating switch 25 is turned on, the heating wire control switch 27 for water is turned on, the heating wire control switch 26 for air is turned off, the heat storage water supply valve 30 and the water return valve 31 are both opened, and the heat storage water pump 18 is started. The electrical energy generated by the solar photovoltaic panel 1 is now stored in the form of thermal energy in the soil surrounding the buried pipe 17. When the temperature of the soil in the buried pipe 17 reaches a certain temperature, the heating wire control switch 27 for water is turned off, and the heat storage water pump 18 is turned off. This is to avoid other environmental problems caused by excessive temperature of the soil in the vicinity of the buried pipe 17. When the photovoltaic power generation system can normally generate power in a grid-connected mode, the power generation switch 24 is closed, the heating switch 25 is opened, the heat storage water supply and return valves 30 and 31 and the heat storage water pump 18 are closed, and the solar photovoltaic panel 1 sequentially stores power for the storage battery 3 and supplies power for a local power grid.
Single heating condition of heating season sand: in the heating season, the single-heating working condition of the sandy soil is preferentially entered, at the moment, the fan 13 and the user side water pump are started, heat in the sandy soil is transported into the air-water heat exchanger 12 by air and is transferred to water in the water supply coil 21, and the water temperature at the inlet and outlet ends of the heat equipment 20 for the user can meet the design requirement by adjusting the fan 13 and the user side water pump. Meanwhile, if the photovoltaic power generation system cannot be connected to the grid, the power generation switch 24 is opened, the heating switch 25 and the heating wire control switch 26 for air are closed, and electric energy generated by the solar photovoltaic panel 1 is converted into heat energy and transported into the sand-air heat exchange chamber 8. If the photovoltaic power generation system can normally generate power in a grid-connected mode, the power generation switch 24 is closed, the heating switch 25 is opened, and the solar photovoltaic panel 1 stores power to the storage battery 3 and supplies power to a local power grid.
Heating season composite heating working condition: in the heating season, if the photovoltaic power generation system is in a grid-connected power generation state for a long time, meanwhile, the heat stored in the sandy soil is continuously taken out for heating, the heat stored in the sandy soil can be continuously reduced, and after a period of time, the user thermal load cannot be met only by virtue of the operation of the sandy soil high-temperature heat storage system. When the water temperatures at the inlet and outlet ends of the heat equipment 20 of a user cannot meet the design requirements by adjusting the fan 13 and the water pump at the user side, the heat supply working condition is entered into a heat supply season composite heat supply working condition, at the moment, the fan 13 in the sand high-temperature heat storage system is still in an operation state, and meanwhile, the heat pump unit 15, the ground source heat pump circulating water pump 16 and the heat pump side water supply and return valves 28 and 29 in the ground source heat pump system are opened. The heat generated by the heat pump unit 15 is transported to the user heat equipment 20 in the building. If the heat pump unit 15 is started to operate in extremely cold weather and cannot meet the heat load of users in the building, the electric heating boiler 23 is started to assist in heat supply.
In the above various working conditions, when all the electric equipment operates, the electric energy in the storage battery 3 is preferentially used, and when the electric energy in the storage battery 3 is exhausted, the electric energy in the local power grid is used, wherein the electric energy comprises a fan 13, a user side water pump, a ground source heat pump circulating water pump 16, a heat storage water pump 18 and a heat pump unit 15.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (9)
1. The building cascade heat supply system is characterized by comprising a photovoltaic power generation subsystem, a sand heat storage subsystem and a ground source heat pump subsystem which are respectively connected with the photovoltaic power generation subsystem, and a user hot water supply circulation subsystem which is connected with both the sand heat storage subsystem and the ground source heat pump subsystem;
The sand heat storage subsystem comprises an electric heater I (7), a sand-air heat exchange chamber (8), an air-water heat exchanger (12) and a fan (13) which are sequentially connected through an air pipeline (14), wherein an outlet of the fan (13) is connected with an air inlet of the electric heater I (7), so that the air pipeline forms a closed circulation loop; the electric heater I (7) is connected with the photovoltaic power generation subsystem and is used for converting electric energy into heat energy and heating air; the sand-air heat exchange chamber (8) is filled with sand and is used for storing heat energy in heated air; the air-water heat exchanger (12) is used for transferring heat stored in the sand-air heat exchange chamber (8) to a user hot water supply circulation subsystem so as to realize heat storage and heat supply;
The ground source heat pump subsystem comprises a heat pump unit (15), a ground source heat pump circulating water pump (16), a heat storage water pump (18), a plurality of ground buried pipes (17) and an electric heater II (19), a heat pump side water supply valve (28), a heat pump side water return valve (29), a heat storage water supply valve (30) and a heat storage water return valve (31); wherein, the electric heater II (19) is internally provided with a heating wire (6) for water, which is electrically connected with the photovoltaic power generation subsystem; the ground buried pipe (17), the heat pump side water supply valve (28), the ground source heat pump circulating water pump (16), the heat pump unit (15) and the heat pump side water return valve (29) are sequentially connected to form a water circulation loop; the buried pipe (17), the heat storage backwater valve (31), the heat storage water pump (18), the electric heater II (19) and the heat storage water supply valve (30) are sequentially connected to form another water circulation loop.
2. Building step heating system according to claim 1, characterized in that the sand-air heat exchange chamber (8) comprises inside sand (9) and air heat exchange coils (10); the stacking height of the sand (9) is enough to fully cover the air heat exchange coil (10); the air heat exchange coil (10) comprises an air supply main pipe, an air return main pipe and a plurality of branch pipes which are vertically arranged; the air supply main pipe and the return air main pipe are horizontally arranged, the upper ends of all branch pipes are connected with the air supply main pipe, and the lower ends of all branch pipes are connected with the return air main pipe.
3. Building step heating system according to claim 1 or 2, characterized in that the sand-air heat exchange chamber (8) is arranged underground, the top of which is spaced a predetermined distance from the ground, and that the insulation layer (11) is laid on the inner surfaces of all the chamber walls of the sand-air heat exchange chamber (8).
4. A building step heating system according to any one of claims 1-3, characterized in that the top of the sand-air heat exchange chamber (8) is provided with an air supply opening (33) and an air outlet (34), and the air supply opening (33) and the air outlet (34) are respectively connected with an air exhaust well (36) and the ground through an air supply well (35); the upper end of the air supply well (35) is connected with a ground air feeder (37), and the upper end of the air exhaust well (36) is connected with an outdoor air outlet (38) through an air pipe; an access door (39) and a sand discharge port (40) are arranged on the side surface of the sand-air heat exchange chamber (8); the access door (39) is higher than the stacking height of the sand (9) inside; the sand discharge port (40) is arranged at the bottom of the side surface of the sand-air heat exchange chamber (8); a personnel movable platform (41) and an overhaul ladder (43) are arranged in the sand-air heat exchange chamber (8).
5. Building step heating system according to claim 1, characterized in that the electric heater i (7) comprises an air chamber and an air heating wire (5); both ends of the heating wire (5) for air are electrically connected with the photovoltaic power generation subsystem; the air-water heat exchanger (12) comprises an air cavity and a water coil (21); both ends of an inlet and an outlet of the water coil pipe (21) are connected with a hot water supply circulation subsystem of a user.
6. Building cascade heating system according to claim 1, characterized in that the heat storage temperature of the sand-air heat exchange chamber (8) is above 400 ℃.
7. Building step heating system according to claim 2, characterized in that a thermometer (32) is provided in the sandy soil (9) at the air outlet of the electric heater i (7).
8. The building step heat supply system according to claim 1, wherein the photovoltaic power generation subsystem comprises a solar photovoltaic panel (1), a power generation circuit and a heating circuit, and the power generation circuit is sequentially connected with a MPPI controller (2), a storage battery (3) and an inverter (4) through electric wires; the other end of the inverter (4) is connected to a local power grid through an electric wire, and the heating circuit is respectively connected with the sand heat storage subsystem and the ground source heat pump subsystem through electric wires;
The user hot water supply circulation subsystem comprises a user heat utilization device (20), an electric heating boiler (23) and a user side circulating water pump (22).
9. A heating method using the building cascade heating system according to any one of claims 1-8, wherein heating is performed sequentially in order of priority of heating by the sand heat storage subsystem, heating by the ground source heat pump subsystem, and heating by the electric heating boiler in the user hot water circulation subsystem.
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| CN119289745A (en) * | 2024-10-23 | 2025-01-10 | 中国科学院大学 | A multi-energy cogeneration system that uses sand as a medium to collect waste heat and waste electricity |
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| CN113639486A (en) * | 2021-09-17 | 2021-11-12 | 华东交通大学 | Ground source heat pump coupling system based on photovoltaic light and heat |
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| CN215003111U (en) * | 2021-04-18 | 2021-12-03 | 呼和浩特市博洋可再生能源有限责任公司 | Wind-solar complementary DC heating facility agriculture and animal husbandry soil heat storage device |
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| CN103807908A (en) * | 2014-03-13 | 2014-05-21 | 兰州理工大学 | Building foundation type sandy soil heat storage self-heating system |
| CN205717463U (en) * | 2016-04-15 | 2016-11-23 | 青岛敏深风电科技有限公司 | A kind of high-efficiency heat-accumulating heating plant |
| CN113639486A (en) * | 2021-09-17 | 2021-11-12 | 华东交通大学 | Ground source heat pump coupling system based on photovoltaic light and heat |
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