CN115468207A - Building step heat supply system and method utilizing photovoltaic power generation and sandy soil high-temperature heat storage - Google Patents
Building step heat supply system and method utilizing photovoltaic power generation and sandy soil high-temperature heat storage Download PDFInfo
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- CN115468207A CN115468207A CN202211016258.1A CN202211016258A CN115468207A CN 115468207 A CN115468207 A CN 115468207A CN 202211016258 A CN202211016258 A CN 202211016258A CN 115468207 A CN115468207 A CN 115468207A
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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
Abstract
The invention discloses a building step heat supply system and method utilizing photovoltaic power generation and sandy soil high-temperature heat storage. The building step heat supply system comprises a photovoltaic power generation subsystem, a sandy soil 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 the sandy soil 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 the outlet of the fan is connected with the air inlet of the electric heater I, so that the air pipeline forms a closed circulation loop; the sandy soil-air heat exchange chamber is filled with sandy soil and used for storing heat energy in heated air. The invention maximally and effectively uses the electric energy generated by the photovoltaic when the grid connection cannot be realized for building heat supply, and is combined with the ground source heat pump, thereby realizing the cascade utilization of the energy for building heat supply and improving the use ratio of renewable energy.
Description
Technical Field
The invention belongs to the field of renewable energy source heat supply, and particularly relates to a building step heat supply system and method utilizing photovoltaic power generation and sandy soil high-temperature heat storage.
Background
Photovoltaic is a power generation system that converts solar radiation energy into electrical energy using the photovoltaic effect of semiconductor materials. Solar energy is a clean, safe and renewable energy source. Photovoltaic is susceptible to factors such as weather, seasons and climate, the generated energy is unstable, and the power consumption of a power grid fluctuates frequently, so that the phenomenon of light abandonment that large-area photovoltaic cannot be connected to the grid frequently occurs. To alleviate this problem, photovoltaic systems are typically configured with installed batteries to ensure stability on the utility side. However, the capacity and life of the battery are limited, and a large capacity battery means a higher initial cost.
The heat storage in the building step heating system is generally to convert the energy from renewable energy sources into heat energy in advance and store the heat energy for peak regulation in heating seasons, or directly serve as a heating source, so that the use ratio 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 heating cost is reduced.
In order to reduce the capacity and the investment of a storage battery and improve the electric energy utilization rate of a photovoltaic system when the grid connection cannot be carried out, the electric energy generated by photovoltaic is converted into heat energy to be stored for building heat supply. For example, chinese patent literature discloses a zero-emission heating system (application publication No. CN 113819510A) in which a middle-deep geothermal energy is coupled with solar energy, the system includes a power generation unit, an energy storage unit, and an energy consumption unit, the power generation unit includes a middle-deep buried pipe heat exchange device, solar photo-thermal heat collection paper, and a photovoltaic power generation system, and the energy storage unit includes a phase change boiler for converting electric energy into thermal energy for storage.
The patents, including those mentioned above, generally employ a thermal storage tank or a thermal storage tank filled with a phase change material as a thermal storage device. However, the phase-change material is high in cost and not beneficial to large-scale heat storage; on the other hand, although the specific heat capacity of water is large, the maximum heat storage temperature can only reach 100 ℃ under the standard atmospheric pressure, and the total heat storage amount is limited. Therefore, how to store the electric energy generated by photovoltaic when grid connection cannot be achieved with low cost and as much as possible, and consume fossil energy as little as possible, and provide clean and stable heat supply for buildings becomes a difficult problem.
Disclosure of Invention
Aiming at the defects or the improvement requirements of the prior art, the invention provides a building step heating system and a building step heating method by utilizing photovoltaic power generation and sandy soil high-temperature heat storage, and aims to maximally effectively use electric energy generated by photovoltaic when grid connection cannot be realized for building heating, and combine the building step heating system with a ground source heat pump to realize energy step utilization of building heating, improve the use ratio of renewable energy sources and realize the social target of carbon neutralization in the heating field.
In order to achieve the above object, according to one aspect of the present invention, there is provided a building step heat supply system using photovoltaic power generation and sandy soil high temperature heat storage, comprising a photovoltaic power generation subsystem, a sandy soil heat storage subsystem and a ground source heat pump subsystem respectively connected to the photovoltaic power generation subsystem, and a user hot water supply circulation subsystem connected to both the sandy soil 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 the outlet of the fan is connected with the 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 used for converting electric energy into heat energy and heating air; the sandy soil-air heat exchange chamber is filled with sandy soil and used for storing heat energy in heated air in a high-temperature state; the air-water heat exchanger is used for transferring heat stored in the sandy soil-air heat exchange chamber to the hot water supply circulation subsystem of a user so as to realize heat storage and heat supply.
Preferably, the sandy soil-air heat exchange chamber comprises a sandy soil and air heat exchange coil inside; the accumulation height of the sandy soil meets the requirement that the air heat exchange coil can be completely covered; 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 air return main pipe are horizontally arranged, the upper ends of all the branch pipes are connected with the air supply main pipe, and the lower ends of all the branch pipes are connected with the air return main pipe.
Preferably, the sandy soil-air heat exchange chamber is arranged underground, the top of the sandy soil-air heat exchange chamber is spaced from the ground by a preset distance, and insulating layers are paved on the inner surfaces of all chamber walls of the sandy soil-air heat exchange chamber.
Preferably, the top of the sandy soil-air heat exchange chamber is provided with an air supply opening and an air exhaust opening, and the air supply opening and the air exhaust opening 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 supply blower, and the upper end of the air exhaust well is connected with an outdoor air outlet through an air pipe; an access door and a sand discharge port are arranged on the side surface of the sandy soil-air heat exchange chamber; 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 sandy soil-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 electric heating wire for air; both ends of the air electric heating wire are electrically connected with the photovoltaic power generation system; the air-water heat exchanger comprises an air cavity and a water coil; the inlet and outlet of the water coil pipe are both connected with a user hot water supply circulating system.
Preferably, the heat storage temperature of the sandy soil-air heat exchange chamber is more than 400 ℃.
Preferably, a thermometer is arranged in the sandy soil and at an air outlet of the electric heater I.
Preferably, the photovoltaic power generation subsystem comprises a solar photovoltaic panel, a power generation line and a power generation line, and the power generation line is sequentially connected with the MPPI controller, the storage battery and the inverter through electric wires; the other end of the inverter is connected to a local power grid through a wire, and the heating line is respectively connected with an electric heater I in the sandy soil heat storage subsystem and an electric heater II in the ground source heat pump subsystem through wires;
the user hot water supply circulating system comprises user heat equipment, an electric 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 hot water storage pump and the electric 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 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; the electric heater II is internally provided with a water electric heating wire electrically connected with the photovoltaic power generation system; the 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 water return valve are sequentially connected to form a water circulation loop; the buried pipe, the heat storage water return 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, wherein heat supply is performed according to the priority sequence of heat supply of the sandy soil heat storage subsystem, heat supply of the ground source heat pump subsystem and heat supply of the electric heating boiler in the user hot water circulation subsystem.
In general, at least the following advantages can be obtained by the above technical solution contemplated by the present invention compared to the prior art.
(1) The sandy soil heat storage subsystem uses sandy soil as a heat storage material, has the advantages of high density, high melting point, low price and easy obtaining, can realize large-scale heat storage with smaller volume, high temperature state and lower cost, and does not need to take strict sealing measures on the shell of the heat storage container; air is used as a heating medium for heat transfer, the specific heat capacity is small, excessive heat cannot be absorbed by the air, and the heat can be stored to the maximum extent; compared with a circulating pipeline taking water or heat conducting oil as a heat medium, the air circulating pipeline has small flow resistance, small power consumption and simple and convenient pipeline installation, and can be applied to heat supply of regional buildings in a large scale. Meanwhile, the electric energy generated by the photovoltaic power generation system when the grid connection cannot be realized is converted into high-temperature heat energy through the air heating wire and is stored in the sandy soil and the soil around the buried pipe, so that the building cleaning heat supply device can be used for building cleaning heat supply, the waste of the photovoltaic electric energy when the grid connection cannot be realized is effectively reduced, the utilization rate of solar energy is improved, and the capacity and the initial investment of a photovoltaic storage battery can be reduced.
(2) The invention applies two technologies of heat storage and ground source heat pump to heat supply of buildings, and heat storage is carried out in the heat supply season and a period of time before the heat supply season; when building heat supply is carried out, the strategy of energy gradient utilization is adopted, heat supply is carried out according to the priority sequence of sandy soil, a ground source heat pump and an electric heating boiler, the operation efficiency of the ground source heat pump can be improved, the arrangement scale and the initial investment of a buried pipe are reduced, the proportion of renewable energy sources in the total energy consumption of building heat supply is improved, and the use amount of fossil energy sources is reduced.
Drawings
Fig. 1 is a schematic diagram of a building step heating system using photovoltaic power generation and sandy soil high-temperature heat storage according to an embodiment of the present invention;
fig. 2 is a schematic side view of a sandy soil-air heat exchange chamber in a building step heating system using photovoltaic power generation and sandy soil high-temperature heat storage according to an embodiment of the present invention;
fig. 3 is a schematic side view of a plurality of sets of arrangement shafts of air heat exchange coils in the building step heat supply system using photovoltaic power generation and sandy soil high-temperature heat storage provided by the embodiment of the invention.
The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:
1-solar photovoltaic panel; 2-MPPI controller; 3-a storage battery; 4-an inverter; 5-electric heating wire is used for air; 6-electric heating wire for water; 7-electric heater I; 8-sandy soil-air heat exchange chamber; 9-sandy soil; 10-air heat exchange coil; 11-a heat-insulating layer; 12-air-water heat exchanger; 13-a fan; 14-an air duct; 15-heat pump set; 16-ground source heat pump circulating water pump; 17-buried pipe; 18-heat storage water pump; 19-electric heater ii; 20-user heat equipment; 21-water coil pipe; 22-user side circulating water pump; 23-an electric boiler; 24-a power generation switch; 25-a heat-generating switch; 26-controlling a switch by an electric heating wire for air; 27-controlling a switch by an electric heating wire for water; 28-heat pump side water supply valve; 29-a heat pump side water return valve; 30-heat storage water supply valve; 31-heat storage water return valve; 32-a thermometer; 33-an air supply outlet; 34-an air outlet; 35-blast well; 36-an air exhaust shaft; 37-ground blower; 38-outdoor air outlet; 39-access door; 40-a sand discharge port; 41-personnel activity platform; 42-a railing; 43-maintenance ladder.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Referring to fig. 1, a building step heating system using photovoltaic power generation and sandy soil high-temperature heat storage comprises a photovoltaic power generation subsystem, a sandy soil 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 electric heater i 7 includes an air chamber and an electric wire 5 for air inside. And two ends of the air heating wire 5 are electrically connected with the photovoltaic power generation system. The interior of the air-water heat exchanger 12 includes an air chamber and a water coil 21. Both ends of the inlet and the outlet of the water coil 21 are connected with a hot water supply circulating system of a user. The ground source heat pump system has a heat pump unit 15 connected to a user hot water circulation system.
The photovoltaic power generation subsystem comprises a solar photovoltaic panel 1, a power generation circuit and a heat generation circuit. The power generation circuit is connected with a power generation switch 24, an MPPI controller 2, a storage battery 3 and an inverter 4 in sequence through wires. The storage battery 3 is electrically connected with the fan 13, the heat pump unit 15, the ground source heat pump circulating water pump 16, the user side water pump 22, the hot water storage pump 18 and the electric boiler 23. The other end of the inverter 4 is connected to the local grid by a wire. The MPPI controller 2 is used for detecting voltage and current in a power generation line, calculating output power of the solar photovoltaic panel, and adjusting to charge the storage battery 3 with maximum output power. The storage battery 3 is used for storing the 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 configured to convert the direct current generated by the solar photovoltaic panel 1 into an alternating current. A heating switch 25, an air electric heating wire 5, an air electric heating wire control switch 26, a water electric heating wire 6 and a water electric heating wire control switch 27 are connected to a heating circuit of the photovoltaic power generation system through electric wires. The air electric heating wire 5 is connected in series with the air electric heating wire control switch 26, the water electric heating wire 6 is connected in series with the water electric heating wire control switch 27, and then the two 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 hot water storage 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 hot water storage water supply valve 30 and a hot water storage water return valve 31 which are sequentially arranged. And a water electric heating wire 6 electrically connected with the photovoltaic power generation system is arranged in the electric heater II 19. 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 to form a water circulation loop. The buried pipe 17, the heat storage water return 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.
The user hot water supply circulation subsystem comprises user heat equipment 20, an electric boiler 23 and a user side water pump 22, and is connected with a water inlet and a water outlet at the condenser side of the heat pump unit 15 through water pipes.
The sand heat storage subsystem connects the electric heater I7, the sand-air heat exchange chamber 8 and the air-water heat exchanger 12 with the fan 13 in sequence through the air pipeline 14, and the outlet of the fan 13 is connected with the air inlet of the electric heater I7 to form an air closed circulation pipeline. The sand-soil-air heat exchange chamber 8 comprises sand soil 9 and an air heat exchange coil 10. The sand 9 has a certain pile height so that the air heat exchange coil 10 is completely covered. The air heat exchange coil 10 includes an air supply main pipe, an air return main pipe and a plurality of branch pipes vertically arranged. The air supply main pipe and the air return main pipe are both 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 air return main pipe.
In the sand heat storage subsystem, sand is used as the heat storage material because the bulk density of sand is about 1300-1600kg/m 3 The specific heat capacity is 0.92 kJ/(kg. DEG C), and the melting point is up to 1650 ℃. Compared with the same volume of water, the heat storage quantity below 100 ℃ is only 28.4-35.0% of the water. However, water as a heat storage material has a maximum heat storage temperature of only 100 ℃ due to its boiling point, whereas 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 to 1.67 times of that of water at 100 ℃ in the same volume. Therefore, the high-temperature sandy soil is more suitable to be used as a heat storage material for large-scale heat storage engineering, on one hand, the heat storage amount of the high-temperature sandy soil is more than that of water, and on the other hand, compared with a phase-change material, the sandy soil is cheaper and more easily obtained. Moreover, the shell of the sand heat storage container does not need to be made into strict sealing measures, and the shell of the water and phase-change material for heat storage is easy to be strictly sealed to prevent liquid leakage.
In the photovoltaic power generation subsystem, the air-use electric heating wire 5 is used as an energy conversion device, and the air-use electric heating wire 5 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 conduction oil as a heat transfer medium, the air in the sandy soil high-temperature heat storage system can be heated to a very high temperature without phase change, the sandy soil can be further heated to a high temperature of hundreds of degrees centigrade, the specific heat capacity of the air is small, the heat storage amount in the heat transfer medium circulation pipeline is small, and more heat generated by the electric heating wire 5 for the air can be transferred to the sandy soil 9 to be stored.
In the embodiment of the present invention, it is preferable to dispose the sandy soil-air heat exchange chamber 8 underground, and the top of the chamber should be spaced from the ground. The arrangement is that when the sandy soil-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 sandy soil-air heat exchange chamber 8 and the surrounding soil, the temperature of the underground soil is constant, the thickness and initial investment of the insulating layer 11 on the inner surface of the chamber wall can be 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 located above ground level.
Referring to fig. 2, in specific implementation, the top of the sand-air heat exchange chamber 8 is provided with an air supply outlet 33 and an air exhaust outlet 34, and the air supply outlet 33 and the air exhaust 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 blast well 35 is connected with a ground blower 37, and the upper end of the 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 sandy soil-air heat exchange chamber 8. The access door 39 is above the pile height of the internal sand 9. The sand discharge port 40 is arranged at the bottom of the side surface of the sandy soil-air heat exchange chamber 8. The upper part of the sandy soil-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 railing 42 is arranged on two sides of the personnel activity platform 41 to prevent personnel from falling. The personnel moving platform 41 is connected with a vertically downward maintenance ladder 43 which can be directly communicated with the bottom of the sandy soil-air heat exchange chamber 8.
In specific implementation, when the sandy soil-air heat exchange chamber 8 normally operates, the air supply opening 33 and the air exhaust opening 34 are both closed. When the sand-air heat exchange chamber 8 is in the construction stage, sand 9 can be transported into the sand-air heat exchange chamber 8 through the blast well 35 and the exhaust well 36, and the sand discharge port 40 is kept closed. When the sandy soil-air heat exchange chamber 8 needs to be overhauled, before the access door 39 is opened, the ground blower 37, the air supply port 33 and the air exhaust port 34 are opened, normal temperature air outside the ground is supplied into the sandy soil-air heat exchange chamber 8 for cooling, and when the indoor temperature of the sandy soil-air heat exchange chamber 8 is reduced to an appropriate temperature, an overhaul person can open the access door 39 for entering. When the air heat exchange coil 10 covered under the sandy soil 9 needs to be overhauled, the sandy soil 9 needs to be discharged by opening the sand discharge port 40.
During specific implementation, the pipe diameters of the air supply main pipe and the air return main pipe of the air heat exchange coil 10 in the sandy soil-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 each branch pipe is approximate, and the air flow in each branch pipe 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 accumulated width of the sandy soil 9 is large and a single group of air heat exchange coil pipes 10 cannot meet the requirement of uniform heat storage of the sandy soil, a plurality of groups of air heat exchange coil pipes 10 which are connected in parallel and distributed in parallel along the width direction of the sandy soil 9 are arranged in the sandy soil air heat exchange chamber 8. Therefore, the temperature of the sandy soil can be uniformly increased or decreased, 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 sandy soil-air heat exchange chamber 8 is above 400 ℃. All the air pipelines 14 except the sandy soil-air heat exchange chamber 8, the shell of the electric heater I7 and the shell of the air-water heat exchanger 12 are paved with heat-insulating materials which can not be combusted when the heat storage temperature reaches the designed 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, thermometers are respectively arranged on water pipes at the inlet and outlet ends of the user heat equipment 20, an air outlet of the electric heater I7, a water outlet of the electric heater II 19 and the sandy soil 9.
The embodiment of the invention also provides a heat supply method by utilizing the building step heat supply system, which sequentially supplies heat according to the priority sequence of heat supply of the sandy soil heat storage subsystem, heat supply of the ground source heat pump subsystem and heat supply of the electric heating boiler in the user hot water circulation subsystem.
Specifically, the working conditions of the building step heat supply system utilizing photovoltaic power generation and sandy soil high-temperature heat storage provided by the embodiment of the invention are divided into a heat storage working condition several weeks before a heating season, a heat storage working condition in a non-heating season, a single heat supply working condition in a heating season and a composite heat supply working condition in the heating season. The specific implementation mode is as follows:
heat storage conditions several weeks before the heating season: in several weeks before the heating season, when the photovoltaic can not be normally grid-connected for power generation, the power generation switch 24 is turned off, the heating switch 25 is turned on, the water electric heating wire control switch 27 is turned off, the air electric heating wire control switch 26 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 volume of the fan 13. High-temperature air enters the sandy soil-air heat exchange chamber 8 along the air pipeline 14 under the power action of the fan 13, and heat is transferred to sandy soil through the air heat exchange coil 1010. With the continuous circulation of the air, when the average temperature of the sandy soil is heated to 400 ℃, that is, the sandy soil heat storage amount is considered to be saturated, at this time, the fan 13 is turned off, the electric heating wire control switch 26 for air is turned off, the electric heating wire control switch 27 for water is turned on, the heat storage water supply and return valves 30 and 31 are both opened, and the heat storage water pump 18 is started. At the moment, 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 energy is transported and stored into the soil around the buried pipe 17 through the heat storage water pump 18. When the photovoltaic power generation system can normally perform grid-connected power generation, the power generation switch 24 is closed, the heating switch 25 is disconnected, 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. When the storage battery 3 is fully charged, the electric energy generated by the solar photovoltaic panel 1 is converted into an alternating current form and is transmitted to a local power grid.
The heat storage working condition in the non-heating season is as follows: in the period from the end of the heat supply season to several weeks before the next heat supply season, when the photovoltaic can not be normally connected with the grid for power generation, the power generation switch 24 is switched off, the heating switch 25 is switched on, the water electric heating wire control switch 27 is switched on, the air electric heating wire control switch 26 is switched off, the heat storage water supply and return valves 30 and 31 are both opened, and the heat storage water pump 18 is started. At this time, the electric energy generated from the solar photovoltaic panel 1 is stored in the soil around the buried pipe 17 in the form of thermal energy. When the soil temperature in the buried pipe 17 reaches a certain temperature, the water heating wire control switch 27 is turned off, and the heat storage water pump 18 is turned off. This is to avoid overheating of the soil near the buried pipe 17 causing other environmental problems. When the photovoltaic power generation system can be normally connected to the grid for power generation, 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 successively stores electricity for the storage battery 3 and supplies electricity for a local power grid.
Sand single heat supply working condition in heat supply season: in the heat supply season, the sandy soil single heat supply working condition is preferentially entered, at the moment, the fan 13 and the user side water pump are started, heat in the sandy soil is transported to the air-water heat exchanger 12 by air and is transferred to water in the water coil pipe 21, and the water temperatures at the inlet and the outlet of the user heat equipment 20 meet the design requirements 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 turned off, the heating switch 25 and the air heating wire control switch 26 are turned on, and electric energy generated by the solar photovoltaic panel 1 is converted into heat energy and is transported to the sandy soil-air heat exchange chamber 8. If the photovoltaic power generation system can be normally connected to the grid for power generation, the power generation switch 24 is closed, the heating switch 25 is opened, and the solar photovoltaic panel 1 successively stores power for the storage battery 3 and supplies power for a local power grid.
The compound heating working condition in the heating season is as follows: in the heat supply season, if the photovoltaic power generation system is in a grid-connected power generation state for a long time, heat stored in sandy soil is continuously taken out for heat supply, the heat stored in the sandy soil can be continuously reduced, and after a period of time, the heat load of a user cannot be met only by the operation of the sandy soil high-temperature heat storage system. When the temperature of water at the inlet and outlet ends of the user heat equipment 20 cannot meet the design requirements by adjusting the fan 13 and the user-side water pump, the composite heat supply working condition of a heat supply season is entered, the fan 13 in the sandy soil high-temperature heat storage system is still in a running state at the moment, 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 started. The heat generated by the heat pump unit 15 is transported to the user heat equipment 20 in the building. If extreme cold weather is met, the heat pump unit 15 is started to run and cannot meet the heat load of users in the building, and the electric boiler 23 is started to supply heat in an auxiliary mode.
In the above various working conditions, when all the electric devices are operated, 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 reused, wherein the electric energy comprises a fan 13, a user side water pump, a ground source heat pump circulating water pump 16, a hot water storage pump 18 and a heat pump unit 15.
It will be understood by those skilled in the art that the foregoing is only an exemplary embodiment of the present invention, and is not intended to limit the invention to the particular forms disclosed, since various modifications, substitutions and improvements within the spirit and scope of the invention are possible and within the scope of the appended claims.
Claims (10)
1. A building step heat supply system utilizing photovoltaic power generation and sandy soil high-temperature heat storage is characterized by comprising a photovoltaic power generation subsystem, a sandy soil 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 the sandy soil heat storage subsystem and the ground source heat pump subsystem;
the sandy soil heat storage subsystem comprises an electric heater I (7), a sandy soil-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 the outlet of the fan (13) is connected with the 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 used for converting electric energy into heat energy and heating air; the sandy soil-air heat exchange chamber (8) is filled with sandy soil and used for storing heat energy in heated air; the air-water heat exchanger (12) is used for transferring heat stored in the sandy soil-air heat exchange chamber (8) to a hot water supply circulation subsystem of a user so as to realize heat storage and heat supply.
2. A building step heating system according to claim 1, wherein said sandy soil-air heat exchange chamber (8) internally comprises a sandy soil (9) and air heat exchange coil (10); the accumulation height of the sandy soil (9) meets the requirement that the air heat exchange coil (10) can be 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 air return main pipe are horizontally arranged, the upper ends of all the branch pipes are connected with the air supply main pipe, and the lower ends of all the branch pipes are connected with the air return main pipe.
3. A building step heating system according to claim 1 or 2, wherein the sandy soil-air heat exchange chamber (8) is arranged underground, the top of the sandy soil-air heat exchange chamber is spaced from the ground by a preset distance, and the inner surfaces of all the chamber walls of the sandy soil-air heat exchange chamber (8) are paved with insulating layers (11).
4. A building step heating system according to any one of claims 1-3, wherein the top of the sandy soil-air heat exchange chamber (8) is provided with an air supply port (33) and an air exhaust port (34), the air supply port (33) and the air exhaust port (34) are respectively connected with the 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 supply blower (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 sandy soil-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 sandy soil-air heat exchange chamber (8); a personnel movable platform (41) and an overhaul ladder (43) are arranged in the sandy soil-air heat exchange chamber (8).
5. The building step heating system according to claim 1, wherein the electric heater I (7) comprises an air cavity and an electric heating wire (5) for air; both ends of the air electric heating wire (5) are electrically connected with the photovoltaic power generation system; the air-water heat exchanger (12) comprises an air chamber and a water coil (21); the inlet and outlet ends of the water coil (21) are connected with a hot water supply circulating system of a user.
6. A building step heating system according to claim 1, wherein the heat storage temperature of the sandy soil-air heat exchange chamber (8) is above 400 ℃.
7. A building step heating system according to claim 2, wherein a thermometer (32) is provided in said sandy soil (9) at the air outlet of said electric heater i (7).
8. The building step heating system according to claim 1, wherein the photovoltaic power generation subsystem comprises a solar photovoltaic panel (1), a power generation line and a heating line, and the power generation line is sequentially connected with the MPPI controller (2), the storage battery (3) and the inverter (4) through electric wires; the other end of the inverter (4) is connected to a local power grid through a wire, and the heating circuit is respectively connected with the sandy soil heat storage subsystem and the ground source heat pump subsystem through wires;
the user hot water supply circulation system comprises user heat equipment (20), an electric boiler (23) and a user side circulating water pump (22).
9. The building step heating system according to claim 1, wherein the ground source heat pump subsystem comprises a heat pump unit (15), a ground source heat pump circulating water pump (16), a hot water storage 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); wherein, a water electric heating wire (6) electrically connected with the photovoltaic power generation system is arranged in the electric heater II (19); 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 to form a water circulation loop; the underground pipe (17), the heat storage water return 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.
10. A heating method using the step heating system for buildings according to any one of claims 1 to 9, characterized in that heat supply is performed according to the priority order of the sand heat storage subsystem heat supply, the ground source heat pump subsystem heat supply and the electric boiler heat supply in the user hot water circulation subsystem.
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