CN111336707A - Carbon dioxide heat pump heating system with topologic homoembryo circulation - Google Patents
Carbon dioxide heat pump heating system with topologic homoembryo circulation Download PDFInfo
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- CN111336707A CN111336707A CN202010131918.5A CN202010131918A CN111336707A CN 111336707 A CN111336707 A CN 111336707A CN 202010131918 A CN202010131918 A CN 202010131918A CN 111336707 A CN111336707 A CN 111336707A
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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
- F25B7/00—Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit
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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
- F24D3/00—Hot-water central heating systems
- F24D3/18—Hot-water central heating systems using heat pumps
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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
- F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
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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
- F25B41/30—Expansion means; Dispositions thereof
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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
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
- F25B9/008—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide
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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
- F25B2309/00—Gas cycle refrigeration machines
- F25B2309/06—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
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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
- F25B2600/00—Control issues
- F25B2600/25—Control of valves
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- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Heat-Pump Type And Storage Water Heaters (AREA)
Abstract
The invention relates to a carbon dioxide heat pump heating system with topological homomorphic circulation, which comprises a carbon dioxide sub-circulation, a refrigerant sub-circulation and a water side circulation flow path which are in heat exchange connection with each other; in the operation process, the carbon dioxide heat pump heating system with the topological homomorphic cycle comprises a mechanical auxiliary supercooling cycle state and an overheating recovery overlapping cycle state. Compared with the prior art, the water path is connected in series, so that the condensation temperature of the refrigerant is reduced, a common heat pump compressor can be selected, the unit cost is reduced, and the practicability is enhanced; the carbon dioxide-water heat exchanger is additionally arranged to serve as a superheater, so that the exhaust heat loss of carbon dioxide is reduced, and the system energy efficiency is improved; the constructed topological homomorphic cycle can be switched between a mechanical auxiliary supercooling cycle and an overheating recovery overlapping cycle according to the change of the environmental temperature, the operation is always in higher energy efficiency, and the continuous and efficient heating in the whole heating season is ensured.
Description
Technical Field
The invention relates to the field of heat pump heating systems, in particular to a carbon dioxide heat pump heating system with topological homomorphic circulation.
Background
In order to solve the problem of serious environmental pollution caused by coal-fired heating in the north, a project of changing coal into electricity is developed in the heating area in the north, and an air source heat pump system is mainly pushed in recent years. Among them, the carbon dioxide heat pump heating system using natural working medium carbon dioxide as refrigerant has received wide attention because of its environmental protection, high efficiency and energy saving.
At present, the carbon dioxide heat pump heating system with better energy conservation and practicability mainly has two types: (1) the carbon dioxide transcritical heat pump heating system (CN208011829U) with mechanical auxiliary supercooling adopts a conventional refrigerant in an auxiliary mechanical cycle, and is used for supercooling carbon dioxide at the outlet of a gas cooler of a carbon dioxide system, reducing the temperature of the carbon dioxide before entering a throttling valve, reducing throttling loss and improving energy efficiency. (2) The carbon dioxide cascade heat pump heating system (CN106524552A, CN209857414U) comprises a carbon dioxide heat pump refrigeration cycle (low temperature level) and a heat pump refrigeration cycle (high temperature level), can respectively select the most appropriate refrigerants, and can cope with the severe cold working condition which can not be satisfied by a single-machine compression cycle.
However, the above two systems can not ensure continuous and efficient heating in the northern heating season: the mechanically-assisted supercooled carbon dioxide heat pump heating system has better performance when the ambient temperature is higher, but the performance can be seriously attenuated under the northern severe cold working condition because the main circulation of the system is still carbon dioxide single-stage compression. In addition, the system adopts a form of parallel water paths, and when the system is used for a radiator with higher water outlet temperature (65 ℃) which is the most common in northern heating, the auxiliary circulation condensation temperature is higher, and a medium-high temperature special compressor with higher cost needs to be selected and matched. The carbon dioxide overlapping heat pump heating system has obvious advantages in a low-temperature environment, but is limited by large heat exchange temperature difference loss of a high-temperature condensation side under a high-temperature working condition, and the energy efficiency is not as good as that of a mechanically-assisted supercooled carbon dioxide heat pump heating system.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a carbon dioxide heat pump heating system with topology homomorphic cycle, wherein a new topology homomorphic cycle is constructed to be beneficial to taking the advantages of the two carbon dioxide heat pump heating systems into consideration, so that the system is in an efficient operation state in the whole heating season.
The topological homomorphic cycle in the invention means that the structures and the connection sequences of the system parts corresponding to two different thermodynamic cycles are completely consistent, and the topological sense is homomorphic. Therefore, through reasonable component design and system control, the same set of system can be switched among different thermodynamic cycle states so as to match the appropriate environmental working condition.
The invention provides a carbon dioxide heat pump heating system with topological homomorphic circulation, which can run in two different states of mechanical auxiliary supercooling circulation and overheating recovery overlapping circulation in the same set of system. The corresponding component structures of the two circulation states and the connected system form are completely consistent, and the transition of the state parameters is realized through the adjustment of control logic.
The purpose of the invention can be realized by the following technical scheme:
the carbon dioxide heat pump heating system with the topologic homoembryo circulation comprises a carbon dioxide sub-circulation, a refrigerant sub-circulation and a water side circulation flow path which are in heat exchange connection with each other;
in the operation process, the carbon dioxide heat pump heating system with the topological homomorphic cycle comprises a mechanical auxiliary supercooling cycle state and an overheating recovery overlapping cycle state.
Further, the carbon dioxide sub-cycle comprises an evaporator, a carbon dioxide compressor, a carbon dioxide-water heat exchanger, a carbon dioxide-refrigerant heat exchanger and a carbon dioxide throttle valve.
Furthermore, the refrigerant sub-cycle comprises a refrigerant throttle valve, a refrigerant-water heat exchanger and a refrigerant compressor, wherein the carbon dioxide-refrigerant heat exchanger is connected to the refrigerant sub-cycle to realize heat exchange between the refrigerant sub-cycle and the carbon dioxide sub-cycle.
Furthermore, the water side circulation flow path comprises a radiator and a water pump, the refrigerant-water heat exchanger is connected into the water side circulation flow path to realize heat exchange between the water side circulation flow path and the refrigerant sub-circulation, and the carbon dioxide-water heat exchanger is connected into the water side circulation flow path to realize heat exchange between the water side circulation flow path and the carbon dioxide sub-circulation.
Further, when the carbon dioxide heat pump heating system with the topological homomorphic cycle is in a mechanical auxiliary supercooling cycle state: the carbon dioxide sub-cycle is used as a main cycle and is a carbon dioxide transcritical cycle; the refrigerant sub-cycle is used as an auxiliary cycle and is a mechanical supercooling cycle.
Further, during said mechanically assisted subcooling cycle condition: the carbon dioxide-water heat exchanger is used as a gas cooler; the carbon dioxide-refrigerant heat exchanger acts as a subcooler.
Further, when the carbon dioxide heat pump heating system with the topological homomorphic cycle is in an overheat recovery overlapping cycle state: the carbon dioxide sub-cycle is used as a low-temperature stage and is a carbon dioxide subcritical cycle; the refrigerant sub-cycle serves as a high temperature stage and is a refrigerant heat pump cycle.
Further, in the superheat recovery cascade cycle state: the carbon dioxide-water heat exchanger is used as a superheater; the carbon dioxide-water heat exchanger acts as a condenser.
Furthermore, the carbon dioxide sub-cycle is a transcritical cycle in a mechanical auxiliary supercooling cycle state, and the absorption and heat release processes of the carbon dioxide fluid are respectively carried out in a subcritical region and a supercritical region. The carbon dioxide sub-cycle is subcritical under the state of the overheat recovery overlapping cycle, and the processes of heat absorption and heat release of the carbon dioxide fluid are carried out in a subcritical region.
The carbon dioxide heat pump heating system with the topologically homomorphic circulation further comprises a closed circulation water path formed by sequentially connecting a water pump, a refrigerant-water heat exchanger, a carbon dioxide-water heat exchanger and the tail end of a radiator. The return water is in a serial form and sequentially flows through the refrigerant-water heat exchanger and the carbon dioxide-water heat exchanger.
The carbon dioxide heat pump heating system with the topology homoembryo circulation comprises two running states of a mechanical auxiliary supercooling circulation and an overheating recovery overlapping circulation, and the states are switched by changing a control logic. In practice, it is preferred that both cycles have an optimum intermediate pressure (i.e. carbon dioxide exhaust pressure) as the control variable for switching.
The carbon dioxide-water heat exchanger and the carbon dioxide-refrigerant heat exchanger have different main functions in a mechanical auxiliary supercooling circulation state and an overheating recovery overlapping circulation state. In the mechanically assisted subcooling cycle state, the carbon dioxide-water heat exchanger acts as a gas cooler and the carbon dioxide-refrigerant heat exchanger acts as a subcooler. In the superheat recovery cascade cycle state, the carbon dioxide-water heat exchanger acts as a superheater and the carbon dioxide-refrigerant heat exchanger acts as an evaporative condenser. In practice, it is preferable that the areas of the carbon dioxide-water heat exchanger and the carbon dioxide-refrigerant heat exchanger are designed with a certain redundancy.
When the carbon dioxide heat pump heating system with the topological homomorphic cycle operates in a state of a mechanical auxiliary supercooling cycle, the carbon dioxide heat pump heating system comprises a main cycle carbon dioxide transcritical cycle (carbon dioxide subcircuit) and an auxiliary mechanical supercooling cycle (refrigerant subcircuit). In the main cycle carbon dioxide transcritical cycle (carbon dioxide subcircuit), low-temperature and low-pressure carbon dioxide gas is compressed into high-temperature and high-pressure supercritical fluid in a carbon dioxide compressor, the high-temperature and high-pressure supercritical fluid sequentially flows through a carbon dioxide-water heat exchanger (a gas cooler) and a carbon dioxide-refrigerant heat exchanger (a subcooler) to be respectively cooled by water and refrigerant to become low-temperature and high-pressure supercritical fluid, the low-temperature and high-pressure supercritical fluid is throttled by a carbon dioxide throttle valve and then enters an evaporator, and the low-temperature and. In the auxiliary mechanical supercooling cycle (refrigerant sub-cycle), a low-temperature and low-pressure refrigerant is compressed into high-temperature and high-pressure gas by a compressor, enters a refrigerant-water heat exchanger to be cooled into low-temperature and high-pressure refrigerant liquid, passes through the throttling action of a refrigerant throttle valve, enters a carbon dioxide-refrigerant heat exchanger (subcooler) to absorb heat from carbon dioxide, and is changed into low-temperature and low-pressure refrigerant gas again.
When the carbon dioxide heat pump heating system with the topological homomorphic cycle operates in a state of an overheat recovery cascade cycle, the carbon dioxide heat pump heating system comprises a low-temperature-level carbon dioxide subcritical cycle (carbon dioxide subcircuit) and a high-temperature-level refrigerant heat pump cycle (refrigerant subcircuit). In the low-temperature carbon dioxide subcritical cycle (carbon dioxide subcircuit), low-temperature low-pressure carbon dioxide gas is compressed into high-temperature high-pressure gas in a carbon dioxide compressor, the high-temperature high-pressure gas sequentially flows through a carbon dioxide-water heat exchanger (superheater) and a carbon dioxide-refrigerant heat exchanger (evaporative condenser) to be respectively cooled by water and refrigerant to form low-temperature high-pressure carbon dioxide subcooled liquid, then flows through a carbon dioxide throttle valve to be throttled, enters an evaporator, absorbs heat from the environment and is changed into the low-temperature low-pressure carbon dioxide gas again. In the high-temperature-level refrigerant heat pump cycle (refrigerant subcircuit), a low-temperature low-pressure refrigerant is compressed into high-temperature high-pressure gas by a compressor, enters a refrigerant-water heat exchanger to be cooled into low-temperature high-pressure refrigerant liquid, passes through the throttling action of a refrigerant throttle valve, enters a carbon dioxide-refrigerant heat exchanger (evaporative condenser) to absorb heat from carbon dioxide, and is changed into low-temperature low-pressure refrigerant gas again.
The invention has the following excellent performance in technology:
1. in the aspect of energy conservation and emission reduction, the heat pump system is used for heat supply in the north, and compared with the traditional coal burning mode, the system has the advantages of environmental protection and energy conservation. The main cycle adopts natural environment-friendly working medium carbon dioxide, and the ozone layer destruction effect of the artificially synthesized refrigerant is weakened.
2. In the aspect of the advancement of equipment, the superheater is additionally arranged in the cascade cycle, so that the improved superheat recovery cascade cycle and the mechanical auxiliary supercooling cycle are topologically identical in system structure, two different thermodynamic cycles can be realized in the same system, the system is compact, the equipment cost is lower, and the economy is good.
3. In the aspect of universality of the system, the system is switched under different circulation states to match different environment working conditions, higher energy efficiency can be ensured in severe cold areas with large-range environment temperature change of-30-15 ℃, and the use range of the unit is widened.
Compared with the prior art, the invention has the following advantages:
1. compared with a mechanical auxiliary supercooling carbon dioxide transcritical heat pump heating system with a water path connected in parallel, the water path of the system adopts a series connection mode, the condensation temperature of a refrigerant is reduced, a common heat pump compressor can be selected and matched, the unit cost is reduced, and the practicability is enhanced.
2. Compared with a carbon dioxide cascade heat pump heating system, the system is additionally provided with the carbon dioxide-water heat exchanger as a superheater, so that the exhaust heat loss of carbon dioxide is reduced, and the system energy efficiency is improved.
3. Compared with a system which can only operate in a single cycle state, such as a mechanical auxiliary supercooling carbon dioxide transcritical heat pump heating system or a carbon dioxide overlapping heat pump heating system, the topological homomorphic cycle constructed by the system can be switched between the mechanical auxiliary supercooling cycle and the overheating recovery overlapping cycle according to the change of the environmental temperature, the system can operate at higher energy efficiency all the time, and continuous and efficient heating in the whole heating season is ensured.
Drawings
FIG. 1 is a schematic structural diagram of a carbon dioxide heat pump heating system with a topologically homomorphic cycle according to the present invention;
in the figure: 1. the system comprises an evaporator, 2, a carbon dioxide compressor, 3, a carbon dioxide-water heat exchanger, 4, a carbon dioxide-refrigerant heat exchanger, 5, a carbon dioxide throttle valve, 6, a refrigerant throttle valve, 7, a refrigerant-water heat exchanger, 8, a refrigerant compressor, 9, backwater, 10, effluent, 11, a radiator, 12 and a water pump.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
The main components of the carbon dioxide heat pump heating system with topologically homomorphic cycle in the embodiment include an evaporator 1, a carbon dioxide compressor 2, a carbon dioxide-water heat exchanger 3, a carbon dioxide-refrigerant heat exchanger 4, a carbon dioxide throttle valve 5, a refrigerant throttle valve 6, a refrigerant-water heat exchanger 7, and a refrigerant compressor 8, which are shown in fig. 1.
The refrigerants selected in the embodiment are synthetic refrigerants, and in the embodiment, novel environment-friendly refrigerants such as R134a and R1234yf are preferable.
The carbon dioxide sub-cycle comprises an evaporator 1, a carbon dioxide compressor 2, a carbon dioxide-water heat exchanger 3, a carbon dioxide-refrigerant heat exchanger 4 and a carbon dioxide throttle valve 5. The refrigerant sub-cycle comprises a refrigerant throttle valve 6, a refrigerant-water heat exchanger 7 and a refrigerant compressor 8, and the carbon dioxide-refrigerant heat exchanger 4 is connected to the refrigerant sub-cycle to realize heat exchange between the refrigerant sub-cycle and the carbon dioxide sub-cycle. The water side circulation flow path comprises a radiator 11 and a water pump 12, the refrigerant-water heat exchanger 7 is connected into the water side circulation flow path to realize heat exchange between the water side circulation flow path and the refrigerant sub-circulation, and the carbon dioxide-water heat exchanger 3 is connected into the water side circulation flow path to realize heat exchange between the water side circulation flow path and the carbon dioxide sub-circulation. The return water 9 is in series connection and flows through the refrigerant-water heat exchanger 7 and the carbon dioxide-water heat exchanger 3 in sequence.
In a specific embodiment, the carbon dioxide heat pump heating system with the topologically homomorphic cycle further comprises a water side circulation flow path, under the driving of the water pump 12, the return water 9 sequentially flows through the refrigerant-water heat exchanger 7 and the carbon dioxide-water heat exchanger 3 to be heated, and the outlet water 10 is sent to the tail ends of the radiator 11 and the like to heat the external air.
In specific operation, the carbon dioxide heat pump heating system with the topological homomorphic cycle comprises two operation states of a mechanical auxiliary supercooling cycle and an overheating recovery overlapping cycle, and the switching of the states is completed through control logic change. In the present embodiment, the optimum intermediate pressure (temperature) in both the cycle states is preferably used as the control variable for switching.
When the carbon dioxide heat pump heating system with the topological homomorphic cycle operates in a mechanical auxiliary supercooling cycle state, the carbon dioxide heat pump heating system comprises a main cycle carbon dioxide transcritical cycle (carbon dioxide subcircuit) and an auxiliary mechanical supercooling cycle (refrigerant subcircuit). In the main cycle carbon dioxide transcritical cycle (carbon dioxide subcircuit), the carbon dioxide-water heat exchanger 3 serves as a gas cooler, the carbon dioxide-refrigerant heat exchanger 4 serves as a subcooler, the low-temperature and low-pressure carbon dioxide gas is compressed into high-temperature and high-pressure supercritical fluid in the carbon dioxide compressor 2, sequentially flows through the carbon dioxide-water heat exchanger 3 (gas cooler) and the carbon dioxide-refrigerant heat exchanger 4 (subcooler), is respectively cooled by water and refrigerant, enters the evaporator 1 after the throttling action of the carbon dioxide throttle valve 5, absorbs heat from ambient air, and is changed into the low-temperature and low-pressure carbon dioxide gas again. In the auxiliary mechanical refrigeration cycle (refrigerant sub-cycle), low-temperature and low-pressure refrigerant gas enters a refrigerant compressor 8, is compressed into high-temperature and high-pressure gas, flows through a refrigerant-water heat exchanger 7, is cooled by water, finally enters a carbon dioxide-refrigerant heat exchanger 4 (subcooler) through a throttle valve 6, absorbs heat from carbon dioxide, and becomes low-temperature and low-pressure refrigerant gas again.
When the carbon dioxide heat pump heating system with the topological homomorphic cycle operates in an overheat recovery cascade cycle state, the carbon dioxide heat pump heating system comprises a low-temperature-level carbon dioxide subcritical cycle (carbon dioxide subcircuit) and a high-temperature-level mechanical refrigeration cycle (refrigerant subcircuit). In the low-temperature-level carbon dioxide transcritical cycle (carbon dioxide subcircuit), the carbon dioxide-water heat exchanger 3 serves as a superheater, the carbon dioxide-refrigerant heat exchanger 4 serves as an evaporative condenser, low-temperature and low-pressure carbon dioxide gas is compressed into high-temperature and high-pressure gas in a carbon dioxide compressor, sequentially flows through the carbon dioxide-water heat exchanger 3 (superheater) and the carbon dioxide-refrigerant heat exchanger 4 (evaporative condenser), is respectively cooled by water and refrigerant, enters the evaporator 1 after the throttling action of the carbon dioxide throttle valve 5, absorbs heat from ambient air, and is changed into low-temperature and low-pressure carbon dioxide gas again. In a high-temperature-stage mechanical refrigeration cycle (refrigerant sub-cycle), low-temperature and low-pressure refrigerant gas enters a refrigerant compressor 8, is compressed into high-temperature and high-pressure gas, flows through a refrigerant-water heat exchanger 7, is cooled by water, finally enters a carbon dioxide-refrigerant heat exchanger 4 (evaporative condenser) through a throttle valve 6, absorbs heat from carbon dioxide, and becomes low-temperature and low-pressure refrigerant gas again.
The carbon dioxide-water heat exchanger 3 and the carbon dioxide-refrigerant heat exchanger 4 in this embodiment serve different functions in the two cycles to match the heat exchange of the two fluids in different states. In this embodiment, it is preferable that both the carbon dioxide-water heat exchanger 3 and the carbon dioxide-refrigerant heat exchanger 4 have a suitably increased heat exchange area.
This embodiment compares with the parallelly connected supplementary subcooling carbon dioxide of machinery in water route transcritical heat pump heating system, and this system water route adopts the series connection form, has reduced the condensing temperature of refrigerant, can match common heat pump compressor, reduces the unit cost, has strengthened the practicality. Compared with a carbon dioxide cascade heat pump heating system, the system is additionally provided with the carbon dioxide-water heat exchanger as a superheater, so that the exhaust heat loss of carbon dioxide is reduced, and the system energy efficiency is improved. Compared with a system which can only operate in a single cycle state, such as a mechanical auxiliary supercooling carbon dioxide transcritical heat pump heating system or a carbon dioxide overlapping heat pump heating system, the topological homomorphic cycle constructed by the system can be switched between the mechanical auxiliary supercooling cycle and the overheating recovery overlapping cycle according to the change of the environmental temperature, the system can operate at higher energy efficiency all the time, and continuous and efficient heating in the whole heating season is ensured.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.
Claims (10)
1. A carbon dioxide heat pump heating system with topological homoembryo circulation is characterized by comprising a carbon dioxide sub-circulation, a refrigerant sub-circulation and a water side circulation flow path which are in heat exchange connection with each other;
in the operation process, the carbon dioxide heat pump heating system with the topological homomorphic cycle comprises a mechanical auxiliary supercooling cycle state and an overheating recovery overlapping cycle state.
2. The topologically homeostatic carbon dioxide heat pump heating system of claim 1, wherein the carbon dioxide sub-cycle comprises an evaporator (1), a carbon dioxide compressor (2), a carbon dioxide-water heat exchanger (3), a carbon dioxide-refrigerant heat exchanger (4) and a carbon dioxide throttle valve (5).
3. The topologically homeostatic carbon dioxide heat pump heating system of claim 2, wherein the refrigerant sub-cycle comprises a refrigerant throttle valve (6), a refrigerant-water heat exchanger (7) and a refrigerant compressor (8);
the carbon dioxide-refrigerant heat exchanger (4) is connected to a refrigerant sub-cycle to realize heat exchange between the refrigerant sub-cycle and the carbon dioxide sub-cycle.
4. The topologically homeostatic carbon dioxide heat pump heating system of claim 3, wherein the water side circulation path comprises a radiator (11) and a water pump (12);
the refrigerant-water heat exchanger (7) is connected to a water side circulation flow path to realize heat exchange between the water side circulation flow path and the refrigerant sub-circulation;
the carbon dioxide-water heat exchanger (3) is connected to the water side circulation flow path to realize heat exchange between the water side circulation flow path and the carbon dioxide subcirculation.
5. The topologically homeostatic carbon dioxide heat pump heating system of claim 4, wherein in the mechanically assisted subcooling cycle state:
the carbon dioxide sub-cycle is used as a main cycle and is a carbon dioxide transcritical cycle;
the refrigerant sub-cycle is used as an auxiliary cycle and is a mechanical supercooling cycle.
6. The topologically homeostatic carbon dioxide heat pump heating system of claim 5, wherein in the mechanically assisted subcooling cycle state:
the carbon dioxide-water heat exchanger (3) is used as a gas cooler;
the carbon dioxide-refrigerant heat exchanger (4) acts as a subcooler.
7. The topologically homeostatic carbon dioxide heat pump heating system of claim 4, wherein in the overheat recovery cascade cycle state:
the carbon dioxide sub-cycle is used as a low-temperature stage and is a carbon dioxide subcritical cycle;
the refrigerant sub-cycle serves as a high temperature stage and is a refrigerant heat pump cycle.
8. The topologically homeostatic carbon dioxide heat pump heating system of claim 5, wherein in the superheat recovery cascade cycle state:
the carbon dioxide-water heat exchanger (3) is used as a superheater;
the carbon dioxide-water heat exchanger (3) is used as a condenser.
9. The topologically homeostatic carbon dioxide heat pump heating system of claim 1, wherein the carbon dioxide sub-cycle is a transcritical cycle in a mechanically assisted supercooling cycle state, and the absorption and release processes of the carbon dioxide fluid are respectively performed in a subcritical region and a supercritical region;
the carbon dioxide sub-cycle is subcritical under the state of the overheat recovery overlapping cycle, and the processes of heat absorption and heat release of the carbon dioxide fluid are carried out in a subcritical region.
10. The topologically homeostatic carbon dioxide heat pump heating system of claim 1, wherein the control variables for switching between the mechanical assisted subcooling cycle state and the superheat recovery cascade cycle state are: both cycle conditions have optimal intermediate pressures and/or temperatures.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113357692A (en) * | 2021-06-04 | 2021-09-07 | 中国科学院广州能源研究所 | Circulating water waste heat recovery system of thermal power plant |
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