CN117889583A - Intermittent-expansion PVT auxiliary ground source heat pump system and operation method - Google Patents
Intermittent-expansion PVT auxiliary ground source heat pump system and operation method Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 23
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- 238000001816 cooling Methods 0.000 claims abstract description 24
- 230000005611 electricity Effects 0.000 claims abstract description 18
- 238000005338 heat storage Methods 0.000 claims abstract description 17
- 230000003993 interaction Effects 0.000 claims abstract description 8
- 238000010248 power generation Methods 0.000 claims abstract description 7
- 238000001704 evaporation Methods 0.000 claims description 35
- 230000008020 evaporation Effects 0.000 claims description 34
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 11
- 238000005485 electric heating Methods 0.000 claims description 10
- 238000003860 storage Methods 0.000 claims description 9
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- 238000005516 engineering process Methods 0.000 description 8
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- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 4
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B30/00—Heat pumps
- F25B30/06—Heat pumps characterised by the source of low potential heat
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24T—GEOTHERMAL COLLECTORS; GEOTHERMAL SYSTEMS
- F24T10/00—Geothermal collectors
- F24T10/10—Geothermal collectors with circulation of working fluids through underground channels, the working fluids not coming into direct contact with the ground
- F24T10/13—Geothermal collectors with circulation of working fluids through underground channels, the working fluids not coming into direct contact with the ground using tube assemblies suitable for insertion into boreholes in the ground, e.g. geothermal probes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
- F25B41/40—Fluid line arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
- H02S40/40—Thermal components
- H02S40/42—Cooling means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
- H02S40/40—Thermal components
- H02S40/42—Cooling means
- H02S40/425—Cooling means using a gaseous or a liquid coolant, e.g. air flow ventilation, water circulation
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
- H02S40/40—Thermal components
- H02S40/44—Means to utilise heat energy, e.g. hybrid systems producing warm water and electricity at the same time
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Abstract
The invention discloses an intermittent-expansion PVT auxiliary ground source heat pump system and an operation method thereof, wherein the system comprises a PVT cogeneration module, a power generation module and a power generation module, wherein the PVT cogeneration module is used for utilizing solar energy and outputting electric energy and heat energy; the geothermal energy module is used for heat interaction between other modules and geothermal energy; the heat pump unit module is used for providing heat energy or cooling energy for the heat supply and cooling module of the user by utilizing the geothermal energy; the auxiliary heating module is used for filling heat into soil or storing heat into the heat storage water tank by utilizing residual electricity; and the user heat and cold supply module is used for supplying heat and cold to the tail end. According to the invention, the indirect connection between the PVT array and the heat pump unit is planned and designed, so that the heat energy output by the PVT array is poured into soil, and the influence of solar energy intermittence on the system performance is reduced; in addition, the influence of the heat exchange quantity of the soil on the soil temperature is finely measured, the regional operation of the buried pipe array according to seasons and load conditions is considered, and the sustainability of the geothermal energy is maintained, so that the efficient and stable operation of the PVT auxiliary ground source heat pump system is ensured.
Description
Technical Field
The invention belongs to the technical field of comprehensive energy utilization, and particularly relates to an intermittent PVT auxiliary ground source heat pump system and an operation method thereof.
Background
In recent years, PVT (solar photovoltaic/thermal) technology is rapidly developed, the PVT technology combines photovoltaic cell technology with solar heat collection technology, solar energy can be effectively converted into electric energy, heat generated by photovoltaic effect is taken away by a cooling medium in a heat collection component of the PVT technology and is effectively utilized, efficient heat and power cogeneration of solar energy in a limited space can be realized, but the existing direct expansion PVT heat pump structure system is poor in stability and is easily influenced by seasons and weather factors, stable heat energy supply is difficult to provide for users at night or in extreme weather, and the liquid working medium PVT system usually takes a water tank as heat storage equipment, so that the heat generated in summer is more, the temperature of the water tank reaches a set point, and waste heat cannot be timely utilized.
The ground source heat pump is regarded as an important building heating and refrigerating technology because of its low carbon property, high energy efficiency ratio and stability, and converts low-grade geothermal energy into high-grade thermal energy by using a small amount of electric energy. Ground source heat pump systems have advantages in terms of energy efficiency ratio and operational stability compared to air source heat pump systems and are less affected by weather conditions. The ground source heat pump system also uses an advanced compressor technology, durable materials and an intelligent control system to ensure the long-term stable operation of the system, reduce the dependence on limited energy resources and meet the principles of sustainable development and environmental protection; in actual operation, the ground source heat pump system faces the challenge of unbalanced heat load and cold load, and long-term continuous operation can cause the problem of soil temperature decay due to the fact that heat extracted from soil exceeds natural temperature return of the soil, which not only can cause short-term non-sustainability of the ground heat energy, but also can significantly influence heating efficiency of the ground source heat pump system.
Disclosure of Invention
In order to overcome the problems in the prior art, the invention provides an intermittent PVT auxiliary ground source heat pump system and an operation method thereof, wherein the intermittent PVT auxiliary ground source heat pump system is formed by programming and designing an indirect heat coupling connection of a PVT array and a heat pump unit, the influence of the heat exchange quantity of soil on the soil temperature is finely measured, the operation mode of a state switching system of a valve group is controlled by considering the regional operation of a buried pipe array according to seasons and loads, the irrigation and the use of geothermal energy are reasonably distributed, the solar energy is efficiently utilized, the sustainable property of the geothermal energy and the efficient and stable operation of the ground source heat pump are maintained, so that the consumption of primary energy is reduced, and the low carbonization process of an energy supply system is promoted.
The invention is realized by adopting the following technical scheme:
an intermittent expansion PVT auxiliary ground source heat pump system comprises a PVT cogeneration module, a geothermal energy module, a heat pump unit module, an auxiliary heating module and a user heat and cold supply module;
The PVT cogeneration module is used for efficiently converting solar energy into electric energy and heat energy and outputting the electric energy, the electric energy can be directly supplied to the system or is transmitted to a power grid through an inverter, and the heat energy is indirectly transmitted to the geothermal energy module through a plate heat exchanger;
the geothermal energy module is used for interacting with the PVT cogeneration module, the heat pump unit module and the auxiliary heating module with geothermal energy in soil; first: in the PVT cogeneration module, heat energy indirectly output by the plate heat exchanger is poured into soil through the buried pipe array so as to maintain the heat balance of the soil; second,: under the heating mode, geothermal energy is conveyed to the heat pump unit module, and under the cooling mode, the thermal energy output by the heat pump unit is conveyed to the geothermal energy module and is filled into soil, so that the heat supply and the cold supply of the system are efficiently realized; third,: under the condition that the PVT cogeneration module generates surplus electricity or the soil temperature is too low, the auxiliary heating module is communicated with the geothermal energy module, and the thermal energy output by the electric boiler is poured into the soil through the buried pipe array, so that the problem of short-term non-sustainability of the geothermal energy is solved;
The heat pump unit module is used for carrying out heat energy interaction with the geothermal energy module so as to efficiently provide heat energy or cooling energy for the heat supply and cooling module of the user; in the heat pump heating mode, the heat pump unit heats the heat storage water tank in the user heat supply and cooling module by utilizing the heat energy output by the geothermal energy module so as to supply heat to the end user, and in the heat pump cooling mode, the heat pump unit conveys the heat energy of the heat storage water tank in the user heat supply and cooling module to the geothermal energy module so as to supply cold to the end user;
the auxiliary heating module is used for heating the heat storage water tank in the user heat supply and cold supply module under the conditions of low electricity price, high end load, low soil temperature or ground source heat pump fault, so that the heat supply requirement of the system is met; in addition, under the conditions that the electricity price is low or the PVT cogeneration module outputs surplus electric energy in a non-heating season, the auxiliary heating module is utilized to convey heat energy to the geothermal energy module, and the irrigation heat of the geothermal energy is reasonably distributed so as to ensure the sustainability of the geothermal energy and the normal operation of the ground source heat pump in the heating season;
And the user heat and cold supply module is used for supplying heat and cold to the tail end of the user through the heat storage water tank and the cold storage water tank.
The PVT cogeneration module comprises a PVT heat collection/evaporation device, a plate heat exchanger, a PVT circulating pump and an inverter;
The hot water outlet of the plate heat exchanger is communicated with the inlet of the PVT heat collection/evaporation device through a PVT circulating pump, and the outlet of the PVT heat collection/evaporation device is communicated with the hot water inlet of the plate heat exchanger; the PVT heat collection/evaporation device is connected to the grid through an inverter.
The invention is further improved in that the medium adopted in the refrigerating fluid circulation loop formed by the plate heat exchanger and the PVT heat collection/evaporation device is a mixed solution of glycol and water.
The invention is further improved in that the geothermal energy module adopts an underground pipe array buried in soil, the underground pipe array and the plate heat exchanger form a water circulation loop through a pipeline and a stop valve, and the refrigerating fluid circulation loop and the water circulation loop are separated through the plate heat exchanger.
The invention is further improved in that a plurality of ground buried pipe arrays are arranged in parallel, and the ground buried pipe arrays realize the zone operation of the ground buried pipes by controlling the opening and closing of the corresponding stop valves.
The invention is further improved in that the heat pump unit module comprises an evaporator, an electronic expansion valve, a condenser and a compressor.
The invention is further improved in that the auxiliary heating module adopts an electric boiler and is used for heating the heat storage water tank to meet the heat supply requirement under the conditions of low electricity price, high end load, low soil temperature or ground source heat pump failure, and for filling heat into soil under the conditions of non-heating season, low electricity price or surplus electric energy output by the PVT cogeneration module so as to maintain the soil heat balance.
The invention is further improved in that the user heating and cooling module comprises a heat storage water tank and a cold storage water tank.
The operation method of the intermittent PVT auxiliary ground source heat pump system comprises the following steps:
1) Counting historical electric heating cold load and weather data at a load side to manufacture a data set;
2) Determining a month strategy of heat interaction quantity of each device and soil and final soil temperature in the next year under the aim of maintaining soil temperature according to historical electric heating cold load and weather data;
3) Generating user load prediction data of the next day according to weather forecast and historical data;
4) Acquiring a next day system operation strategy according to a preset system mathematical model, electric heating cold load prediction data and a month strategy of the month;
5) And adjusting the operation mode of the system according to the operation strategy, and updating the month strategy of the month.
The invention has at least the following beneficial technical effects:
According to the intermittent-expansion PVT auxiliary ground source heat pump system, high-efficiency cogeneration is realized through a photovoltaic photo-thermal (PVT) technology, so that the comprehensive utilization efficiency of solar energy in a limited space is improved, the advantages of clean and renewable energy sources can be fully exerted, and the intermittent-expansion PVT auxiliary ground source heat pump system has important significance in solving the problem of space limitation faced by urban environment and limited space construction; the PVT array is indirectly and thermally coupled with the heat pump unit, so that the influence of seasonal and weather factors can be reduced, and the running stability of the system can be improved; in addition, low-grade heat energy output by the PVT array is injected into soil, sustainable maintenance of geothermal energy is realized, and through the design, the problems of soil temperature reduction and heating efficiency attenuation caused by long-term operation of a ground source heat pump are successfully solved, so that the electric energy consumption of a heat pump unit and the carbon emission in the energy supply process are reduced, and the operation stability of a system is remarkably improved.
According to the operation method of the intermittent PVT auxiliary ground source heat pump system, provided by the invention, under the aim of optimizing the system economy, factors such as illumination intensity, soil temperature and load and operation constraint of each device in the system are comprehensively considered, the influence of soil heat exchange quantity on the soil temperature is finely metered, and the regional operation of the ground pipe array according to seasons and loads is considered, so that the operation mode of the system in each period and the specific operation power of each device are determined, the operation efficiency of the system is effectively improved, and the operation cost of the system is reduced; compared with a timing or constant temperature control strategy in the traditional control method, the operation control method provided by the invention can more truly and fully consider the physical process of system operation and provide more operation optimization space.
Drawings
FIG. 1 is a block diagram of an intermittent PVT-assisted ground source heat pump system according to the present invention.
Fig. 2 is a flow chart of an operation method of the intermittent PVT auxiliary ground source heat pump system according to the present invention.
Fig. 3 is a schematic diagram of an intermittent PVT auxiliary ground source heat pump system according to the present invention in a PVT-to-soil irrigation mode.
Fig. 4 is a schematic diagram of an intermittent PVT auxiliary ground source heat pump system according to the present invention in a heating mode in which PVT and a ground pipe supply heat to a heat pump unit together.
Fig. 5 is a schematic diagram of an intermittent PVT auxiliary ground source heat pump system according to the present invention in a heating mode in which a ground pipe alone supplies heat to a heat pump unit.
Fig. 6 is a schematic diagram of an intermittent PVT auxiliary ground source heat pump system according to the present invention in a heat pump refrigeration mode in which the heat pump unit alone pumps heat to the ground pipe.
Reference numerals illustrate:
1-PVT heat collection/evaporation device; 2-an electric grid; 3-a first circulating water pump; 4-a first four-way valve; 5-a second circulating water pump; 6-a second four-way valve; 7-an array of buried pipes; 8-a first three-way valve; 9-a second three-way valve; 10-an electronic expansion valve; 11-a compressor; 12-a heat pump unit; 13-a third three-way valve; 14-a fourth three-way valve; 15-a first shut-off valve; 16-a second shut-off valve; 17-a third stop valve; 18-fourth shut-off valve.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.
According to the invention, through designing indirect thermal coupling connection between the PVT array and the heat pump unit and filling the heat energy output by the PVT array into the soil, the influence of environmental factors such as air temperature, illumination intensity and the like on the system performance is reduced, and the stable operation of the PVT auxiliary ground source heat pump system is realized; meanwhile, the influence of the heat exchange quantity of the soil on the soil temperature is finely measured, the ground buried pipe array is considered to perform zone operation according to the change of seasons and loads, the system operation mode is switched by controlling the state of the valve group, the heat filling and the use of the geothermal energy are reasonably distributed, the sustainability of the geothermal energy is maintained, the efficient and stable operation of the PVT auxiliary ground source heat pump system is ensured, and the consumption of primary energy is further reduced.
In a first aspect, as shown in fig. 1, the present invention provides an intermittent PVT auxiliary ground source heat pump system, wherein the system apparatus includes: the PVT heat collection/evaporation device 1, the plate heat exchanger, the buried pipe array 7, the heat pump unit 12 consisting of an evaporator, a condenser, an electronic expansion valve 10 and a compressor 11, an electric boiler, a heat storage and cold storage water tank and a plurality of valves can be divided into a PVT cogeneration module, a geothermal energy module, a heat pump unit module, an auxiliary heating module and a user heating and cooling module according to functions.
(1) PVT cogeneration module: the device comprises a PVT heat collection/evaporation device 1, a plate heat exchanger, a first circulating water pump 3 and an inverter; the first circulating water pump 3 is respectively connected with the PVT heat collection/evaporation device 1 and the plate heat exchanger, the plate heat exchanger is mainly arranged for separating a geothermal energy module from a PVT cogeneration module, in the PVT cogeneration module, mixed liquid of glycol and water (the specific proportion is determined according to the working environment temperature) is used in the PVT heat collection/evaporation device 1, working medium flowing in the geothermal energy module and the buried pipe array 7 is water, and the plate heat exchanger is used for providing buffering between two hydraulic loops so as to ensure that different flow control can be realized in two subsystems; in addition, as the scale of the buried pipe array 7 is larger, the total flow of the internal working medium is relatively larger, and the consumption of glycol can be obviously reduced through the plate heat exchanger, the method is not only beneficial to reducing the risk of glycol leakage, but also can effectively control the running cost of the system; the PVT array is indirectly and thermally coupled with the heat pump unit through the plate heat exchanger, so that the influence of environmental factors such as air temperature, illumination intensity and the like on the energy efficiency of the system can be reduced, the mode switching frequency of the system is reduced, and the stable operation of the system is realized; the PVT heat collection/evaporation device 1 also converts solar energy into dc energy by using photovoltaic effect, and converts dc energy into ac energy by using an inverter, and this part of the energy may be directly supplied to other devices in the system, or the surplus energy may be connected to the power grid 2 by using the inverter.
(2) And a geothermal energy module: the ground pipe array 7 is used for carrying out heat interaction with the soil, the ground pipe array 7 is provided with a plurality of ground pipes which are arranged in parallel, the number of the ground pipe array is specifically set according to the requirement of a user, and the ground pipe array can realize the zone operation of the ground pipes by controlling the opening and closing of the first stop valve 15, the second stop valve 16, the third stop valve 17 and the fourth stop valve 18; the water outlets of the ground buried pipe array 7 are connected through a second four-way valve 6, the water inlets are connected with a second circulating water pump 5, and the first four-way valve 4 and the second four-way valve 6 are controlled according to the load working condition, the weather condition, the water outlet temperature of the PVT heat collection/evaporation device 1 and the soil temperature to switch the operation mode of the system.
(3) And a heat pump unit module: the heat pump unit 12 is composed of a plate heat exchanger connected with the PVT cogeneration module, an evaporator connected with the ground pipe array 7 of the geothermal energy module, an electronic expansion valve 10, a condenser connected with a heat preservation energy storage water tank (a heat storage or cold storage water tank) and a compressor 11.
(4) Auxiliary heating module: the electric boiler is used for heating the hot water storage tank to meet the heat supply requirement under the conditions of low electricity price, high end load, low soil temperature or ground source heat pump failure, and for filling heat into the soil under the conditions of non-heating season, low electricity price or surplus power output by the PVT cogeneration module so as to maintain the soil heat balance
(4) User heat and cold supply module: and heat and cold are supplied to the tail end of the user through the heat storage water tank and the cold storage water tank respectively.
In a second aspect, as shown in fig. 2, the present invention further provides a method for operating the above-mentioned intermittent PVT auxiliary ground source heat pump system, where the method centrally controls the operating power of the heat pump unit 12 in the system, the geothermal energy module, the PVT cogeneration module, and the first four-way valve 4, the second four-way valve 6, the first three-way valve 8 and the second three-way valve 9 connected to the geothermal energy module and the auxiliary heating module, and is used to control the first stop valve 15, the second stop valve 16, the third stop valve 17 and the fourth stop valve 18 and the heat exchange amount thereof for the ground pipe array to operate in a partition, and an optimization model is built according to the physical equipment and the operating mode of the system.
A) System mathematical model
The objective of the overall control scheduling is to reduce the running cost as much as possible on the premise of meeting the load demands of users, so that the objective function is as follows:
wherein lambda i pur,λsol is the buying price and selling price at the i-th moment respectively; The electricity buying and selling quantity at the moment i are respectively; the unit of the buying and selling electricity is kWh;
Model constraints include energy balance constraints and plant operating constraints; energy balance constraints include electrical energy balance, thermal energy balance, and cooling energy balance; the energy balance constraint refers to conservation of energy supplied by the equipment of the inter-expansion PVT auxiliary ground source heat pump system and energy consumed by the system; the power supply equipment and the power supply mode in the system comprise: the PVT heat collection/evaporation device 1 supplies power and the power grid 2 purchases power; the power consumption device and the power consumption mode include: the user group electric load, the heat pump unit 12 power consumption, the electric boiler power consumption, and the first circulating water pump 3 and the second circulating water pump 5 power consumption; the heating equipment in the system comprises: an electric heating boiler, a heat pump unit 12 and a heat storage water tank, wherein the system uses a heat mode to group heat loads for users; the refrigeration equipment in the system comprises: the heat pump unit is used for grouping the cooling requirement of a user in a cooling mode in the system; the equipment operation constraint is mathematical description of equipment energy transfer and energy conversion processes in the system, and comprises PVT cogeneration constraint, constraint of heat pump unit heating capacity or refrigerating capacity and electric power, constraint of electric boiler heating capacity and electric power, constraint of heat exchange between a buried pipe and soil through the buried pipe, constraint of change of soil temperature along with heat exchange between the buried pipe and soil and energy storage constraint; wherein the PVT cogeneration constraint is:
wherein is the generated energy of the PVT heat collection/evaporation device 1 at the moment I, n pvt is the area of the PVT array, I i is the solar radiation intensity at the moment I, τ g,αpv is the transmittance of the PVT outer layer glass cover plate and the absorptivity of the photovoltaic panel respectively, I is the power generation efficiency of the PVT heat collection/evaporation device 1 corresponding to the moment I, the power generation efficiency linearly decreases with the temperature of the PVT panel, T rc,ηre,βpv is the reference temperature respectively, the power generation efficiency corresponding to the reference temperature, and the temperature coefficient of the photovoltaic panel power generation, I is the generated energy of the PVT heat collection/evaporation device 1 corresponding to the moment I, I is the heat filling amount of the PVT heat collection/evaporation device 1 to the ground pipe array 7 at the moment I and the heat loss of the PVT heat collection/evaporation device 1 and the surrounding environment respectively, and U loss is the heat loss coefficient of the PVT heat collection/evaporation device 1 and the surrounding environment.
In order to finely measure the influence of the soil heat exchange quantity on the soil temperature, the use and the heat filling of geothermal energy are distributed more reasonably, according to the drilling characteristics of the buried pipe array 7, the dimensionless temperature corresponding coefficient of the borehole wall temperature t b of the buried pipe array 7 along with the step heat flow change delta G ghe is obtained in advance, and is represented by G (·) and the common influence of all the step heat flow changes before the moment i on the borehole wall temperature is considered, wherein the dimensionless temperature corresponding coefficient is represented by the following formula:
Wherein t g, represents the temperature of the undisturbed soil at the far end and the temperature of the borehole wall of the buried pipe array 7 at the moment i, κ, n and L represent the thermal conductivity of the soil, the number of buried pipes and the depth of the single buried pipe, respectively, G (·) is the temperature response coefficient, which is related to the geometric parameters and time of the buried pipe array 7, and approximates the temperature of the borehole wall of the buried pipe array 7 at the moment i to the temperature of the soil at the moment i; therefore, the pipe wall temperature of the buried pipe corresponding to the moment i, namely the soil temperature, can be obtained from the heat exchange amount of the buried pipe array 7 and the soil before the moment i by the above formula.
The heat exchange heat between the buried pipe array and the soil at the moment i is represented by , namely the net heat exchanged between the buried pipe array and the soil at the moment i, if/> is positive, the heat extraction of the buried pipe array from the soil at the moment i is represented, otherwise, the heat filling of the buried pipe array into the soil is represented, and the heat exchange heat is specifically represented by the following constraint:
is the heat quantity of the ground pipe array 7 to the heat pump unit 12, the heat pump unit 12 to the ground pipe array 7, the ground pipe array 7 to the electric boiler and the PVT heat collecting/evaporating device 1 to the ground pipe array 7 at the moment i respectively.
B) System operation mode
I) PVT irrigation mode to soil: as shown in fig. 3, when the output temperature of the PVT heat collection/evaporation device 1 is 3 ℃ higher than the soil temperature/> and the heat pump unit 12 is off, the PVT heat collection/evaporation device 1 uses a plate heat exchanger to inject the heat energy output by the PVT heat collection/evaporation device into the soil through the buried pipe array 7; at the moment, the plate heat exchanger and the buried pipe array 7 are communicated through the second circulating water pump 5 by adjusting the first four-way valve 4 and the second four-way valve 6 and bypass the overheat pump unit 12 so as to realize that the PVT heat collection/evaporation device 1 irrigates heat to soil; in addition, if summer is taken, only the third stop valve 17 and the fourth stop valve 18 are opened, only the partial buried pipe array 7 is filled with heat, and if other seasons are taken, the first stop valve 15, the second stop valve 16, the third stop valve 17 and the fourth stop valve 18 are opened, and the whole buried pipe array 7 is filled with heat;
ii) a heating mode of heating heat supplied to the heat pump unit by PVT and the buried pipe together: as shown in fig. 4, when the output temperature of the PVT heat collection/evaporation device 1 is 3 ℃ or higher than the soil temperature/> and the heat pump unit 12 is in the heating mode, the plate heat exchanger, the ground pipe array 7 and the evaporator of the heat pump unit 12 are connected by adjusting the first four-way valve 4 and the second four-way valve 6, so that the PVT heat collection/evaporation device 1 and the ground pipe array 7 supply heat to the heat pump unit together;
iii) Heating mode that ground buried pipe supplies heat to heat pump unit alone: as shown in fig. 5, when the intensity of solar radiation is weaker, the output temperature of the PVT heat collection/evaporation device 1 does not reach the temperature for filling heat into soil, and the first four-way valve 4 and the second four-way valve 6 are adjusted to connect the ground pipe array 7 with the evaporator of the heat pump unit 12, so that the heat supply of the ground pipe array 7 to the heat pump unit 12 is realized;
iv) a heat pump refrigerating mode in which the heat pump unit independently fills heat into the ground buried pipe: as shown in fig. 6, when the intensity of solar radiation is weaker, the output temperature of the PVT heat collection/evaporation device 1 does not reach the temperature for heating the soil, and the first four-way valve 4 and the second four-way valve 6 are adjusted to connect the ground buried pipe array 7 with the condenser of the heat pump unit 12, so that the heat pump refrigeration mode of heating the soil by the heat pump unit 12 is realized; in this mode, only the first stop valve 15 and the second stop valve 16 are opened, and the influence of PVT heat filling on the heat pump cooling efficiency is reduced.
In addition, according to actual situations of peak-to-valley electricity prices, soil temperatures and load demands, there may be situations in the above modes that the electric boiler is used for assisting in heat filling to soil through the ground pipe array 7 and supplying heat to the tail end through the electric boiler by adjusting the first four-way valve 4, the second four-way valve 6, the first three-way valve 8 and the second three-way valve 9.
Load prediction and model solving
After determining the objective function and constraint conditions of the inter-expansion PVT auxiliary ground source heat pump system model, solving the model by using a multi-objective optimization method based on scene generation. Firstly, making a data set by counting historical thermoelectric cold load and weather data at a load side; secondly, determining a month strategy of the heat interaction quantity of each equipment and soil and the final soil temperature in each month in the next year under the constraint of maintaining the sustainable operation of geothermal energy for a plurality of years according to the historical data of the past climate and load so as to provide a short-term system operation strategy basis when a system in the next year specifically operates; thirdly, when the system actually operates, the electric heating and cooling load data of the load side of each day are estimated, the specific method is that the load data are generated by carrying out prediction and load data according to the past climate and history data, and taking the temperature, humidity, wind speed and the predicted peak value and the predicted average value of the next-day cooling and heating load in the next-day weather forecast as data characteristics; fourthly, acquiring a next-day system operation strategy and solving a next-day equipment operation strategy according to the mathematical model of the intermittent PVT auxiliary ground source heat pump system, the electric heating cold load prediction data of the load side and the month strategy of the month; and finally, according to the operation strategy of the specific equipment and the heat interaction strategy with soil provided by the model, adjusting the operation mode of the intermittent PVT auxiliary ground source heat pump system, corresponding parameters and power of the equipment according to the strategy, and updating the month strategy of the month.
While the invention has been described in detail in the foregoing general description and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that modifications and improvements can be made thereto. Accordingly, such modifications or improvements may be made without departing from the spirit of the invention and are intended to be within the scope of the invention as claimed.
Claims (10)
1. The intermittent expansion type PVT auxiliary ground source heat pump system is characterized by comprising a PVT cogeneration module, a geothermal energy module, a heat pump unit module, an auxiliary heating module and a user heat supply and cold supply module;
The PVT cogeneration module is used for efficiently utilizing solar energy and outputting electric energy and heat energy, wherein the electric energy is used for supplying power to the system or is transmitted to a power grid through an inverter, and the heat energy is transmitted to the geothermal energy module;
The geothermal energy module is used for interacting with the PVT cogeneration module, the heat pump unit module and the auxiliary heating module with geothermal energy in soil; first: the heat energy output by the PVT cogeneration module is poured into soil through a buried pipe; second,: under the heating mode, the geothermal energy extracted by the geothermal energy module is transmitted to the heat pump unit module, and under the cooling mode, the thermal energy output by the heat pump unit is transmitted to the geothermal energy module and is filled into the soil; third,: under the condition that the surplus photovoltaic power generation or the soil temperature is too low, the auxiliary heating module and the geothermal energy module are communicated, and the thermal energy output by the electric boiler is poured into the soil through the buried pipe;
the heat pump unit module is used for carrying out heat energy interaction with the geothermal energy module and providing heat energy or cooling energy for the heat supply and cooling module of the user; in the heat pump heating mode, the heat pump unit heats the heat storage water tank in the user heat supply and cooling module by utilizing the heat energy output by the geothermal energy module so as to supply heat to the end user, and in the heat pump cooling mode, the heat pump unit conveys the heat energy of the heat storage water tank in the user heat supply and cooling module to the geothermal energy module so as to supply cold to the end user;
The auxiliary heating module is used for heating the heat storage water tank in the user heat supply and cold supply module under the conditions of low electricity price, high end load, low soil temperature or ground source heat pump fault, so as to meet the heat supply requirement of the system; in addition, under the conditions of non-heating season and low electricity price or surplus electric energy output by the PVT cogeneration module, the auxiliary heating module is utilized to convey heat energy to the geothermal energy module so as to ensure the sustainable performance of the geothermal energy and the efficient operation of the ground source heat pump in winter;
And the user heat and cold supply module is used for supplying heat and cold to the tail end of the user through the heat storage water tank and the cold storage water tank.
2. An intermittent PVT auxiliary ground source heat pump system according to claim 1, wherein the PVT cogeneration module comprises a PVT heat collection/evaporation device, a plate heat exchanger, a PVT circulation pump, and an inverter;
The hot water outlet of the plate heat exchanger is communicated with the inlet of the PVT heat collection/evaporation device through a PVT circulating pump, and the outlet of the PVT heat collection/evaporation device is communicated with the hot water inlet of the plate heat exchanger; the PVT heat collection/evaporation device is connected to the grid through an inverter.
3. The system of claim 2, wherein the medium used in the refrigerating fluid circulation loop comprising the plate heat exchanger and the PVT heat collection/evaporation device is a mixed solution of ethylene glycol and water.
4. An intermittent PVT-assisted ground source heat pump system according to claim 2, wherein the geothermal energy module employs an array of ground pipes buried in the soil, the array of ground pipes and the plate heat exchanger constitute a water circulation circuit through a shut-off valve and a pipe, and the refrigerating fluid circulation circuit and the water circulation circuit are separated by the plate heat exchanger.
5. An intermittent PVT-assisted ground source heat pump system according to claim 4 wherein a plurality of ground pipe arrays are provided, the plurality of ground pipes are arranged in parallel, and the ground pipe arrays realize the zoned operation of the ground pipes by controlling the opening and closing of the corresponding shut-off valves.
6. An intermittent PVT-assisted ground source heat pump system according to claim 2 wherein the heat pump unit module comprises an evaporator, an electronic expansion valve, a condenser, and a compressor.
7. An intermittent PVT auxiliary ground source heat pump system according to claim 6 wherein the auxiliary heating module employs an electric boiler for heating the hot water tank to meet heating demand in case of low electricity price, high end load, low soil temperature or ground source heat pump failure, and for supplying heat to soil to maintain soil heat balance in case of non-heating season and low electricity price or PVT cogeneration module outputting surplus electric energy.
8. An intermittent PVT-assisted ground source heat pump system according to claim 6 wherein the user heating and cooling module comprises a hot water storage tank and a cold water storage tank.
9. A method of operating an intermittent PVT-assisted ground source heat pump system according to any one of claims 1 to 8, comprising:
1) Counting historical electric heating cold load and weather data at a load side to manufacture a data set;
2) Determining a month strategy of heat interaction quantity of each device and soil and final soil temperature in the next year under the aim of maintaining soil temperature according to historical electric heating cold load and weather data;
3) Generating user load prediction data of the next day according to weather forecast and historical data;
4) Acquiring a next day system operation strategy according to a preset system mathematical model, electric heating cold load prediction data and a month strategy of the month;
5) And adjusting the operation mode of the system according to the operation strategy, and updating the month strategy of the month.
10. The method of claim 9, wherein the mathematical model of the inter-expansion PVT-assisted ground source heat pump system comprises:
The objective function is:
wherein lambda i pur,λsol is the buying price and selling price at the i-th moment respectively; The electricity buying and selling quantity at the moment i are respectively; the unit of the buying and selling electricity is kWh;
Model constraints include energy balance constraints and plant operating constraints; energy balance constraints include electrical energy balance, thermal energy balance, and cooling energy balance; the energy balance constraint refers to conservation of energy supplied by the equipment of the inter-expansion PVT auxiliary ground source heat pump system and energy consumed by the system; the power supply equipment and the power supply mode in the system comprise: PVT heat collection/evaporation device supplies power and power grid electricity purchasing; the power consumption device and the power consumption mode include: user group electric load, heat pump unit power consumption, electric boiler power consumption, and circulating water pump power consumption; the heating equipment in the system comprises: the system comprises an electric heating boiler, a ground source heat pump and a heat storage water tank, wherein the system uses a thermal mode to group the heat load of users; the refrigeration equipment in the system comprises: the ground source heat pump uses a cold mode in the system to group the cold demands of users; the equipment operation constraint is mathematical description of equipment energy transfer and energy conversion processes in the system, and comprises PVT cogeneration constraint, constraint of heat pump unit heating capacity or refrigerating capacity and electric power, constraint of electric boiler heating capacity and electric power, constraint of heat exchange between a buried pipe and soil through the buried pipe, constraint of change of soil temperature along with heat exchange between the buried pipe and soil and energy storage constraint;
In order to finely measure the influence of the soil heat exchange quantity on the soil temperature, the use and the heat filling of geothermal energy are distributed more reasonably, according to the drilling characteristics of the buried pipe array, the dimensionless temperature corresponding coefficient of the borehole wall temperature t b of the buried pipe array along with the step heat flow change delta G ghe is obtained in advance, and is represented by G (·) and the common influence of all the step heat flow changes before the moment i on the borehole wall temperature is considered, the method is specifically represented by the following formula:
Wherein represents the temperature of the soil at the far end which is not disturbed and the temperature of the borehole wall of the buried pipe array at the moment i, κ, n and L represent the thermal conductivity of the soil, the number of buried pipes and the depth of the single buried pipe respectively, G (·) is the temperature response coefficient, which is related to the geometric parameters and time of the buried pipe array, and the borehole wall temperature of the buried pipe array at the moment i is approximated to the soil temperature at the moment i; therefore, the wall temperature of the buried pipe corresponding to the moment i, namely the soil temperature at the moment i, can be obtained by the heat exchange quantity of the buried pipe array and the soil before the moment i;
The heat exchange quantity between the buried pipe array and the soil at the moment i is represented by , namely the net heat exchanged between the buried pipe array and the soil at the moment i, if is positive, the heat is taken from the soil by the buried pipe array at the moment i, otherwise, the heat is filled into the soil, and the heat is specifically represented by the following formula:
and is the heat transferred to the heat pump unit by the ground pipe array at the moment i, the heat transferred to the ground pipe array by the heat pump unit, the heat transferred to the ground pipe array by the electric boiler and the heat transferred to the ground pipe array by the PVT heat collection/evaporation device respectively.
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