CN111623555A - Refrigerant active injection heat pump based on low-grade heat source and control method thereof - Google Patents

Refrigerant active injection heat pump based on low-grade heat source and control method thereof Download PDF

Info

Publication number
CN111623555A
CN111623555A CN202010341180.5A CN202010341180A CN111623555A CN 111623555 A CN111623555 A CN 111623555A CN 202010341180 A CN202010341180 A CN 202010341180A CN 111623555 A CN111623555 A CN 111623555A
Authority
CN
China
Prior art keywords
heat pump
heat source
temperature
refrigerant
throttle valve
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202010341180.5A
Other languages
Chinese (zh)
Inventor
涂虬
朱建军
邓晨冕
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ningbo Haizhipu Intelligent Technology Co ltd
Zhejiang Iqini Environmental Technology Co ltd
Ningbo University of Technology
Original Assignee
Ningbo Haizhipu Intelligent Technology Co ltd
Zhejiang Iqini Environmental Technology Co ltd
Ningbo University of Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ningbo Haizhipu Intelligent Technology Co ltd, Zhejiang Iqini Environmental Technology Co ltd, Ningbo University of Technology filed Critical Ningbo Haizhipu Intelligent Technology Co ltd
Priority to CN202010341180.5A priority Critical patent/CN111623555A/en
Publication of CN111623555A publication Critical patent/CN111623555A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • F25B30/02—Heat pumps of the compression type
    • 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
    • F25B40/00—Subcoolers, desuperheaters or superheaters
    • F25B40/02—Subcoolers
    • 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
    • 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

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)

Abstract

The refrigerant injection can improve the heating capacity and energy efficiency of the heat pump, but the injection heat comes from the heat pump itself and is passive injection, and the injection characteristic shows that the heat pump performance improvement amplitude is limited, and the heat pump cannot operate in an extremely low temperature environment. Aiming at the problem, the invention provides a refrigerant active injection heat pump based on a low-grade heat source, which makes full use of the low-grade heat source, such as solar energy, high-temperature waste water, waste gas and the like, so that the heat of an external heat source and an injection refrigerant can exchange heat sufficiently in a subcooler, the refrigerant with the heat is injected into a middle pressure cavity of a compressor, the external heat is converted into a heat pump unit, and heat power gain is obtained, thereby greatly improving the heating capacity and energy efficiency of the heat pump, effectively improving the use comfort of users, widening the application range of the heat pump and enabling the heat pump to be applied to regions below 15 ℃. Meanwhile, the invention also provides a control method of the refrigerant active jet heat pump based on the low-grade heat source.

Description

Refrigerant active injection heat pump based on low-grade heat source and control method thereof
Technical Field
The invention relates to a heat pump, in particular to a refrigerant active injection heat pump based on a low-grade heat source and a control method thereof.
Background
With the development of economy, the continuous improvement of the living standard of people and the development of urbanization construction, the application of the air-conditioning heating system is increasingly wide, and the energy consumption of buildings caused by the wide application is huge. In the global range, the building energy consumption of developed countries accounts for about 37-40% of the total social energy consumption, the building energy consumption of China accounts for more than 33% of the total social energy consumption, and in the building energy consumption, the energy consumption of air conditioners and heating equipment accounts for the largest proportion and is as high as more than 65%. On the other hand, people put higher requirements on comfort and sanitation of living environment, and the conventional air conditioner has generally low energy efficiency and serious heat production and energy efficiency attenuation in low-temperature environment; the coal-fired boiler is not only insanitary, but also pollutes the environment, is the main cause of haze generation, and is easy to cause gas poisoning. Therefore, it is difficult for conventional air conditioning and heating apparatuses to meet the requirements for high-quality life and energy efficiency. The project of changing coal into electricity, which is currently in progress, adopts an electric energy driven heat pump to gradually replace the traditional heating equipment, and has become a great trend, and under the promotion of the project, the heat pump starts to enter common families and is accepted by wide consumers.
When the heat pump is used for heating, the problems of serious heating capacity and energy efficiency attenuation at low ambient temperature exist, and the problems become main factors for preventing the popularization and the application of the technology. In order to solve the problems, the conventional heat pump mostly adopts an enhanced vapor injection technology, and the principle of the enhanced vapor injection technology is that a part of refrigerant with intermediate pressure is sucked through an intermediate pressure suction hole, the refrigerant is mixed with the partially compressed refrigerant and then compressed, and a single compressor realizes two-stage compression, so that the flow of the refrigerant in a condenser is increased, the enthalpy difference of a main circulation loop is increased, and the efficiency of the compressor is further improved.
Although the air injection enthalpy increasing technology improves the heating capacity and the energy efficiency of the heat pump to a certain extent, the refrigerant injection with the subcooler is a passive refrigerant injection because the injection refrigerant and the refrigerant in the main loop adopt internal heat exchange and do not absorb heat from the outside, so that the actual improvement range of the heating capacity and the energy efficiency of the heat pump is limited, in the practical application process, the heating capacity improvement range of the passive refrigerant injection heat pump is generally about 10%, after an optimization control measure is taken, the maximum improvement range does not exceed 20%, and the energy efficiency improvement range of the heat pump is more limited, so that the use of the heat pump is limited, and when the environmental temperature is lower than-15 ℃, the low-temperature heat pump cannot play a heating role.
Disclosure of Invention
The invention aims to solve the technical problem of providing a refrigerant active injection heat pump based on a low-grade heat source, which has good heating capacity and energy efficiency and wide application range.
In order to solve the technical problems, the invention provides a low-grade heat source-based refrigerant active injection heat pump with the following structure: the system comprises a heat pump system, an injection system, an external heat source and an external heat source pump, wherein the heat pump system comprises a compressor, a condenser, an evaporator, a main throttle valve and a four-way valve which are communicated in a circulating manner; the injection system comprises a subcooler and a subcooling throttle valve, a refrigerant heat exchange tube and an external heat source heat exchange tube are arranged on the subcooler, one end of the subcooling throttle valve is communicated with the outlet end of the condenser, the other end of the subcooling throttle valve is communicated with the inlet end of the refrigerant heat exchange tube, the outlet end of the refrigerant heat exchange tube is communicated with an intermediate pressure cavity of the compressor, and an external heat source pump is communicated between the inlet end of the external heat source heat exchange tube and the outlet.
After adopting the structure, compared with the prior art, the invention has the following advantages: the refrigerant active jet heat pump based on the low-grade heat source can fully utilize an external heat source, particularly the low-grade heat source, and convert the low-grade heat source into the high-grade heat source, so that the heat exchange performance of the subcooler can be effectively improved, the heating capacity and the energy efficiency of the heat pump are greatly improved, the problem that the heating capacity and the energy efficiency of the heat pump are seriously attenuated at low environmental temperature is solved, the heat pump can be applied to the area with the environmental temperature lower than-15 ℃, and the application range of the heat pump is greatly widened.
The invention relates to a refrigerant active injection heat pump based on a low-grade heat source, wherein an external heat source temperature sensor is arranged at the outlet end of an external heat source, a subcooler inlet temperature sensor is arranged at the inlet end of a refrigerant heat exchange tube, and a subcooler outlet temperature sensor is arranged at the outlet end of the refrigerant heat exchange tube.
The structure can accurately control the starting and stopping of the external heat source pump, so that the heat pump can run more stably, and the heating capacity and the energy efficiency of the heat pump are ensured.
Another technical problem to be solved by the present invention is to provide a control method for the above-mentioned low-grade heat source based refrigerant active injection heat pump.
In order to solve the technical problem, the invention provides a control method of a refrigerant active injection heat pump based on a low-grade heat source, which comprises the following steps:
in the operation process of the heat pump, the temperature T of the external heat source is detected in real time through the temperature sensor of the external heat sourceh,inDetecting the temperature T of the injection inlet of the subcooler at the inlet end of the refrigerant heat exchange tube in real time through the temperature sensor at the inlet of the subcoolerinj,inThe temperature T of the injection inlet of the subcooler at the outlet end of the refrigerant heat exchange tube is detected in real time by a subcooler outlet temperature sensorinj,out；
When the temperature T of the external heat sourceh,inTemperature T of ejection outlet of subcooler is not more thaninj,outWhen the heat pump is started, the external heat source pump is controlled to stop running, so that the external heat source can not enter the subcooler;
when the temperature T of the external heat sourceh,inTemperature T of ejection outlet of subcoolerinj,outAnd when the heat pump is started, the external heat source pump is controlled to run, so that the external heat source can enter the subcooler.
Compared with the prior art, the control method of the refrigerant active injection heat pump based on the low-grade heat source has the following advantages that:
the control method of the low-grade heat source-based refrigerant active jet heat pump can enable the heat pump to fully utilize an external heat source, particularly a low-grade heat source, and convert the low-grade heat source into a high-grade heat source, thereby not only effectively improving the heat exchange performance of a subcooler in the heat pump and greatly improving the heating capacity and energy efficiency of the heat pump, but also enabling the heat pump to be applied to an area with the environmental temperature lower than-15 ℃, and greatly widening the application range of the heat pump.
The invention relates to a control method of a low-grade heat source-based refrigerant active injection heat pump, wherein in the low-grade heat source-based refrigerant active injection heat pump, a suction temperature sensor is arranged on a pipeline connected with a compressor suction port, and an evaporator inlet temperature sensor is arranged on a pipeline connected with an inlet end of an evaporator;
the main throttle valve is controlled and adjusted according to the superheat degree of the heat pump, and the superheat degree of the heat pump is defined as follows:
compressor suction temperature TsDefrost temperature Tdef；
When the actual superheat degree is larger than the target superheat degree, the main throttle valve is opened greatly;
when the actual superheat degree is smaller than the target superheat degree, the main throttle valve is closed;
when the actual superheat degree is equal to the target superheat degree, the main throttle valve keeps the current opening degree;
wherein the target superheat degree is a system preset temperature value of the heat pump, and the suction temperature T of the compressorsThe defrosting temperature T is obtained by an air suction temperature sensordefAcquired by an evaporator inlet temperature sensor.
The control and regulation of the main throttle valve can effectively ensure the operational reliability of the heat pump.
The invention relates to a control method of a low-grade heat source-based refrigerant active injection heat pump, wherein in the low-grade heat source-based refrigerant active injection heat pump, a pipeline connected with the outlet end of a condenser is provided with a condenser outlet temperature sensor, and a pipeline connected with the exhaust port of a compressor is provided with a high-pressure sensor;
the supercooling throttle valve is controlled and adjusted according to the supercooling degree of the heat pump, and the supercooling degree of the heat pump is defined as:
saturation temperature P corresponding to high pressure of heat pumpd_tLiquid tube temperature Tliq；
When the actual supercooling degree is larger than the target supercooling degree, the opening of the supercooling throttle valve is large;
when the actual supercooling degree is less than the target supercooling degree, the supercooling throttle valve is closed;
when the actual supercooling degree is equal to the target supercooling degree, the supercooling throttle valve keeps the current opening degree;
wherein, the target supercooling degree is a system preset temperature value of the heat pump and a saturation temperature P corresponding to the high pressure of the heat pumpd_tThe temperature T of the liquid pipe is obtained by conversion after the high-pressure sensor obtains the high-pressure of the heat pumpliqAcquired by a condenser outlet temperature sensor.
The control and regulation of the supercooling throttle valve can effectively ensure the operation reliability of the heat pump.
The invention relates to a control method of a low-grade heat source-based refrigerant active injection heat pump, wherein in the low-grade heat source-based refrigerant active injection heat pump, an exhaust temperature sensor is arranged on a pipeline connected with an exhaust port of a compressor;
the supercooling throttle valve is corrected and adjusted according to the exhaust superheat degree of a compressor of the heat pump, and the exhaust superheat degree of the compressor of the heat pump is defined as:
compressor discharge temperature Td-saturation temperature P corresponding to high pressure of heat pumpd_t；
When the actual compressor exhaust superheat degree is less than a set value B, the supercooling throttle valve is closed to be small;
when the actual compressor exhaust superheat degree is larger than a set value C, the supercooling throttle valve is opened greatly;
when the set value B is less than or equal to the actual compressor exhaust superheat degree and less than or equal to the set value C, the supercooling throttle valve is controlled and adjusted according to the target supercooling degree of the heat pump;
the set value B and the set value C are both system preset temperature values of the heat pump, and the set value C is larger than the set value B; compressor discharge temperature TdAcquired by an exhaust gas temperature sensor.
The above-described corrective adjustment of the subcooling throttle valve can further ensure the operational reliability of the heat pump.
The invention discloses a control method of a refrigerant active injection heat pump based on a low-grade heat source, which further comprises the following steps:
after the external heat source pump is started to operate,
when the temperature T of the injection inlet of the subcoolerinj,in+ set value A is less than or equal to external heat source temperature Th,in< temperature T of ejection outlet of subcoolerinj,outWhen the heat pump is in a continuous running state, the external heat source pump is kept in a continuous running state;
when the temperature T of the external heat sourceh,in< temperature T of injection inlet of subcoolerinj,inWhen the value is + the set value A, controlling the external heat source pump to stop running;
wherein the set value A is a system preset temperature value of the heat pump, and the injection inlet temperature T of the subcoolerinj,in+ set value A < subcooler jet outlet temperature Tinj,out。
The control method can effectively prevent the external heat source pump in the heat pump from being started and stopped frequently, so that the heat pump can run more stably, and the heating capacity and the energy efficiency of the heat pump are ensured.
Drawings
FIG. 1 is a simplified schematic diagram of a prior art heat pump system for heating;
FIG. 2 is a graph of cycle pressure enthalpy for heat pump heating according to the prior art;
FIG. 3 is a detailed schematic diagram of the system of the present invention based on the low-grade heat source for heating the refrigerant by the active injection heat pump;
FIG. 4 is a simplified schematic diagram of the system of the present invention for heating a low grade heat source based refrigerant active injection heat pump;
fig. 5 is a cycle pressure-enthalpy diagram for heating of the refrigerant active injection heat pump based on the low-grade heat source of the present invention.
Description of reference numerals:
for the prior art heat pump: 101. a compressor; 102. a condenser; 103. an evaporator; 104. a main throttle valve; 105. a subcooler; 106. a cold throttle valve.
For the low-grade heat source-based refrigerant active injection heat pump of the invention: 1. a compressor; 2. a condenser; 3. an evaporator; 4. a main throttle valve; 5. a four-way valve; 6. a liquid storage tank; 7. a gas-liquid separator; 8. an outdoor fan; 9. a heat preservation water tank; 10. a main machine water pump; 11. a refrigerant conduit; 12. a heat-preserving water conduit; 13. a high pressure switch; 14. a high pressure sensor; 15. a low pressure switch; 16. a subcooler; 17. a subcooling throttle valve; 18. a refrigerant heat exchange tube; 19. an external heat source heat exchange tube; 20. an external heat source; 21. an external heat source pump; 22. an external heat source temperature sensor; 23. a subcooler inlet temperature sensor; 24. a subcooler outlet temperature sensor; 25. an exhaust gas temperature sensor; 26. an intake air temperature sensor; 27. a condenser outlet temperature sensor; 28. an evaporator inlet temperature sensor.
Detailed Description
The present invention will be described in detail with reference to the drawings and the detailed description, and the present invention is based on a low-grade heat source.
The simplified schematic diagram of the system in the heating process of the heat pump in the prior art is shown in fig. 1:
when the refrigerant is not injected, the heat pump cycle proceeds as follows: the supercooling throttle valve 106 is closed, the compressor 101 runs, the refrigerant enters the compressor 101 through the air suction port of the compressor 101 and is compressed, then is changed into high-temperature gaseous refrigerant and is discharged from the air outlet of the compressor 101, then flows into the condenser 102 and exchanges heat with air or water, the refrigerant which releases heat flows into the evaporator 103 through the subcooler 105 and the main throttle valve 104, exchanges heat with air in the evaporator 103, and finally returns to the air suction port of the compressor 101 and enters the compressor 101 again;
when the refrigerant is injected, the heat pump cycle proceeds as follows: the supercooling throttle valve 106 is opened, and is adjusted according to a certain target (for example, adjusted according to the supercooling degree or the superheat degree of the heat pump), the refrigerant enters the compressor 101 through the air suction port of the compressor 101 and is compressed, then is changed into a high-temperature gaseous refrigerant and is discharged from the air discharge port of the compressor 101, then flows into the condenser 102 and exchanges heat with air or water, then the refrigerant flows through two paths, the main circulation path flows into the evaporator 103 through the cooler 105 and the main throttle valve 104, exchanges heat with air in the evaporator 103, and finally returns to the air suction port of the compressor 101 and enters the compressor 101 again; the other path is throttled by a cold throttle valve 106, enters the subcooler 105, exchanges heat with the refrigerant in the main circulation flow path, and is finally injected into an intermediate pressure cavity of the compressor 101 under the action of pressure difference.
The corresponding pressure-enthalpy diagram of the heat pump in the prior art for heating is shown in fig. 2, wherein h is specific enthalpy and P is pressure.
V in FIGS. 1 and 2A、VB、VCAnd VDThe refrigerant state point is the refrigerant state point when the refrigerant is not injected, and corresponds to the refrigerant state point after the air suction port of the compressor 101, the air discharge port of the compressor 101, the outlet of the condenser 102 and the main throttle valve 104 are throttled respectively; v1-V9Is a refrigerant state point at the time of refrigerant injection, and V1、V2、V3、V4And V8Respectively corresponding to the corresponding state points V of the refrigerant in the main circulation flow path after the compressor 101 suction port, the compressor 101 exhaust port, the main throttle valve 104 inlet, the main throttle valve 104 outlet and the compressor 101 first-stage compression5、V6And V7Respectively corresponding to the state points V of the refrigerant of the injection flow path at the inlet of the supercooling throttle valve 106, the outlet of the supercooling throttle valve 106 and entering the middle pressure cavity of the compressor 1019Corresponding to the point in the state where the main circulation flow passage refrigerant and the injection flow passage refrigerant are mixed in the intermediate chamber of the compressor 101.
As can be seen from fig. 2, the refrigerant undergoes two-stage compression in the compressor 101, where V1To V8For the first stage of compression, V9To V2For the second stage of compression.
Heating capacity Q of heat pump of the prior art according to the heat pump cycle principleh,VEqual to the air energy Q absorbed by the evaporator 103e,VWith compression work EPVAnd the expression is as follows:
Qh,V＝Qe,V+EPV
wherein the air energy Q absorbed by the evaporator 103e,VThe expression of (a) is:
Figure BDA0002468536640000061
one part of refrigerant returns to the compressor 101 after exchanging heat in the evaporator 103, the other part of refrigerant is sprayed to the middle cavity of the compressor 101, and the two parts of refrigerant are mixed and then compressed in the second stage, so the expression of the compression work of the heat pump in the prior art is as follows:
Figure BDA0002468536640000071
energy efficiency COP of prior art heat pumpVThe expression of (a) is:
Figure BDA0002468536640000072
in the above expression, mVAnd mi,VCompressor displacement and refrigerant injection mass flow rates, respectively.
The above shows that: performance gains of prior art heat pumps result from increased air energy (V) from subcooling5Dot and V3Point enthalpy difference) and increase in compression work, and the heat of injection (V) of the refrigerant7Dot and V6The heating amount calculated by the enthalpy difference of the points) is not calculated to the heating amount Qh,VIn (1).
Therefore, the heat of the refrigerant injection comes from the heat pump itself when the heat pump heats in the prior art, and is therefore passive injection, the performance improvement range of the heat pump is limited, and therefore the invention aims to develop a refrigerant active injection heat pump based on the action of an external low-grade heat source, so that the low-grade heat source, such as solar energy, waste heat and the like, is fully utilized, and the purpose of greatly improving the heating capacity and energy efficiency of the heat pump is achieved.
Example 1:
as shown in fig. 3, the refrigerant active jet heat pump based on the low-grade heat source of the invention comprises a heat pump system, a jet system, an external heat source 20 and an external heat source pump 21, the heat pump system comprises a compressor 1, a condenser 2, an evaporator 3, a main throttle valve 4, a four-way valve 5, a liquid storage tank 6, a gas-liquid separator 7, an outdoor fan 8, a heat preservation water tank 9 and a host water pump 10, the condenser 2 is provided with a refrigerant conduit 11 and a heat preservation water conduit 12, an exhaust port of the compressor 1 is communicated with a D port of the four-way valve 5, an E port of the four-way valve 5 is communicated with an inlet port of the refrigerant conduit 11 on the condenser 2, an outlet end of the refrigerant conduit 11 is communicated with one end of the liquid storage tank 6, the other end of the liquid storage tank 6 is communicated with one end of the main throttle valve 4, an S port of the four-way valve 5 is communicated with an inlet end of a gas-liquid separator 7, an outlet end of the gas-liquid separator 7 is communicated with an air suction port of the compressor 1, a host water pump 10 is communicated between an inlet end of a heat preservation water guide pipe 12 and an outlet end of a heat preservation water tank 9, an outlet end of the heat preservation water guide pipe 12 is communicated with an inlet end of the heat preservation water tank 9 through a pipeline, and an outdoor fan 8 is arranged close to the evaporator 3; a high-pressure switch 13 and a high-pressure sensor 14 are arranged on a pipeline connected with an exhaust port of the compressor 1, and a low-pressure switch 15 is arranged on a pipeline connected with an air suction port of the compressor 1; the injection system comprises a subcooler 16 and a subcooling throttle valve 17, wherein a refrigerant heat exchange tube 18 and an external heat source heat exchange tube 19 are arranged on the subcooler 16, one end of the subcooling throttle valve 17 is communicated with the outlet end of the condenser 2, and one end of the subcooling throttle valve 17 in the embodiment is communicated with a pipeline between the outlet end of the refrigerant guide tube 11 and one end of the liquid storage tank 6; the other end of the supercooling throttle valve 17 is communicated with the inlet end of a refrigerant heat exchange tube 18, the outlet end of the refrigerant heat exchange tube 18 is communicated with the middle pressure cavity of the compressor 1, an external heat source pump 21 is communicated between the inlet end of an external heat source heat exchange tube 19 and the outlet end of an external heat source 20, the outlet end of the external heat source heat exchange tube 19 is connected out through a pipeline, and the external heat source 20 in the embodiment can be hot water, steam or hot air heated by low-grade heat sources such as solar energy, waste heat and the like; an external heat source temperature sensor 22 is arranged at the outlet end of the external heat source 20, a subcooler inlet temperature sensor 23 is arranged at the inlet end of the refrigerant heat exchange tube 18, and a subcooler outlet temperature sensor 24 is arranged at the outlet end of the refrigerant heat exchange tube 18; an exhaust temperature sensor 25 is arranged on a pipeline connected with an exhaust port of the compressor 1, an air suction temperature sensor 26 is arranged on a pipeline connected with an air suction port of the compressor 1, a condenser outlet temperature sensor 27 is arranged on a pipeline connected with an outlet end of the condenser 2, and an evaporator inlet temperature sensor 28 is arranged on a pipeline connected with an inlet end of the evaporator 3.
Fig. 4 shows a simplified schematic diagram of a system for heating a low-grade heat source-based refrigerant active injection heat pump in this embodiment:
when the refrigerant is not injected, the heat pump cycle proceeds as follows: the supercooling throttle valve 17 is closed, the compressor 1 is operated, the refrigerant enters the compressor 1 through an air suction port of the compressor 1 and is compressed, then is changed into high-temperature gaseous refrigerant and is discharged from an air outlet of the compressor 1, then flows into the condenser 2 and exchanges heat with air or water, the refrigerant emitting heat flows into the evaporator 3 through the main throttle valve 4, exchanges heat with the air in the evaporator 3, and finally returns to the air suction port of the compressor 1 and enters the compressor 1 again;
when the refrigerant is injected, the heat pump cycle proceeds as follows: the supercooling throttle valve 17 is opened, and is adjusted according to a certain target (for example, according to the supercooling degree or the superheat degree of the heat pump), and an external heat source 20 is input into the subcooler 16; the compressor 1 operates, refrigerant enters the compressor 1 through an air suction port of the compressor 1 and is compressed, then is changed into high-temperature gaseous refrigerant and is discharged from an air outlet of the compressor 1, then flows into the condenser 2 and exchanges heat with air or water, then the refrigerant flows through two paths, a main circulation path flows into the evaporator 3 through the main throttle valve 4, exchanges heat with air in the evaporator 3, and finally returns to the air suction port of the compressor 1 and enters the compressor 1 again; the other path is throttled by a cold throttle valve 17, enters a subcooler 16, exchanges heat with an external heat source 20, and is finally injected into an intermediate pressure cavity of the compressor 1 under the action of pressure difference.
The corresponding pressure-enthalpy diagram of the low-grade heat source based refrigerant active injection heat pump in the present embodiment during heating is shown in fig. 5:
the expression of the heating capacity of the refrigerant active injection heat pump based on the low-grade heat source in the embodiment is as follows:
Qh,V＝Qe,V+Qsc,inj+EPV
wherein Q issc,injThe heat quantity absorbed by the refrigerant in the subcooler is expressed as:
Figure BDA0002468536640000081
the expression of the compression work of the refrigerant active injection heat pump based on the low-grade heat source in the embodiment is as follows:
Figure BDA0002468536640000091
as can be seen from the above, the heating capacity of the refrigerant active injection heat pump based on the low-grade heat source in the present embodiment is larger than the heating capacity of the heat pump of the related art by the heat quantity Q absorbed by the refrigerant in the subcoolersc,injTherefore, the energy efficiency COP of the low-grade heat source-based refrigerant active injection heat pump in the embodimentVThis is also followed by an increase.
Example 2:
the embodiment discloses a control method of a low-grade heat source-based refrigerant active injection heat pump in embodiment 1, which comprises the following steps:
in the operation process of the heat pump, the opening degree of the main throttle valve 4 and the supercooling throttle valve 17 is adjusted according to a certain target, such as the supercooling degree or the superheat degree of the heat pump; while detecting the external heat source temperature T in real time by the external heat source temperature sensor 22h,inThe subcooler injection inlet temperature T at the inlet end of the refrigerant heat exchange tube 18 is detected in real time by a subcooler inlet temperature sensor 23inj,inThe subcooler spray inlet temperature T at the outlet end of the refrigerant heat exchange tube 18 is detected in real time by a subcooler outlet temperature sensor 24inj,out；
When the temperature T of the external heat sourceh,inEqual to or lower than the temperature of the ejection outlet of the subcoolerTinj,outWhen the heat source is cooled, the external heat source pump 21 is controlled to stop running, so that the external heat source 20 cannot enter the subcooler 16;
when the temperature T of the external heat sourceh,inTemperature T of ejection outlet of subcoolerinj,outAt this time, the external heat source pump 21 is controlled to start operation so that the external heat source 20 can enter the subcooler 16.
In the present embodiment, the main throttle 4 is controlled and adjusted according to the superheat of the heat pump, which is defined as:
compressor suction temperature TsDefrost temperature Tdef；
When the actual superheat degree is larger than the target superheat degree, the main throttle valve 4 is opened to be large;
when the actual superheat degree is less than the target superheat degree, the main throttle valve 4 is closed;
when the actual superheat degree is equal to the target superheat degree, the main throttle valve 4 keeps the current opening degree;
wherein the target superheat degree is a system preset temperature value of the heat pump, and the suction temperature T of the compressorsDefrost temperature T obtained by suction temperature sensor 26defAcquired by the evaporator inlet temperature sensor 28.
The supercooling throttle valve 17 is controlled and adjusted according to the supercooling degree of the heat pump, and the supercooling degree of the heat pump is defined as:
saturation temperature P corresponding to high pressure of heat pumpd_tLiquid tube temperature Tliq；
When the actual supercooling degree is larger than the target supercooling degree, the supercooling throttle valve 17 is opened;
when the actual supercooling degree is less than the target supercooling degree, the supercooling throttle valve 17 is closed;
when the actual supercooling degree is equal to the target supercooling degree, the supercooling throttle valve 17 maintains the current opening degree;
wherein, the target supercooling degree is a system preset temperature value of the heat pump and a saturation temperature P corresponding to the high pressure of the heat pumpd_tThe liquid pipe temperature T is obtained by converting the high pressure sensor 14 after acquiring the high pressure of the heat pumpliqAcquired by a condenser outlet temperature sensor 27.
In order to ensure the operation reliability of the heat pump, the supercooling throttle valve 17 is corrected and adjusted according to the compressor discharge superheat degree of the heat pump, which is defined as:
compressor discharge temperature Td-saturation temperature P corresponding to high pressure of heat pumpd_t；
When the actual compressor exhaust superheat degree is less than a set value B, the supercooling throttle valve 17 is closed;
when the actual compressor exhaust superheat degree is larger than a set value C, the supercooling throttle valve 17 is opened to be large;
when the set value B is less than or equal to the actual compressor exhaust superheat degree and less than or equal to the set value C, the supercooling throttle valve 17 is controlled and adjusted according to the target supercooling degree of the heat pump;
the set value B and the set value C are both system preset temperature values of the heat pump, and the set value C is larger than the set value B; compressor discharge temperature TdAcquired by an exhaust gas temperature sensor 25.
The set point B and the set point C can be at the compressor discharge temperature TdUnder and over high conditions, the over-cooling throttle valve 17 is used for controlling and regulating the exhaust temperature T of the compressordTo ensure the exhaust temperature T of the compressordAlways in the reliability range; for example, the existing heat pump generally requires the exhaust superheat degree of a compressor to be more than 10 ℃, and the set value B can be set to be 15-20 ℃ under the condition of ensuring a certain margin; the exhaust temperature T of the compressor of the existing heat pumpdThe protection value of the heat pump is generally about 120 ℃, and the saturation temperature P is corresponding to the high pressure of a general heat pump (the frequency limit high pressure is 37-38 bar)d_tAbout 60 ℃, and the set value C can be set to be 45-55 ℃ under the condition of ensuring a certain margin.
Of course, since the subcooling throttle valve 17 is normally adjusted according to the subcooling degree control of the heat pump, and the subcooling throttle valve 17 is adjusted by correction according to the degree of superheat of the compressor discharge air of the heat pump in order to ensure the operational reliability of the heat pump, when the opening degree of the subcooling throttle valve 17 is adjusted, the operational reliability of the heat pump needs to be preferentially ensured, that is, on the premise that the operational reliability of the heat pump can be ensured, the subcooling throttle valve 17 is adjusted according to the subcooling degree control of the heat pump.
Example 3:
the difference between the present embodiment and embodiment 2 is that the present embodiment adds a control method for preventing frequent start and stop of the external heat source pump 21, and specifically includes the following steps:
during the operation of the heat pump, the opening degree of the main throttle valve 4 and the supercooling throttle valve 17 is adjusted according to a certain target, and the external heat source temperature T is detected in real time by the external heat source temperature sensor 22h,inThe subcooler injection inlet temperature T at the inlet end of the refrigerant heat exchange tube 18 is detected in real time by a subcooler inlet temperature sensor 23inj,inThe subcooler spray inlet temperature T at the outlet end of the refrigerant heat exchange tube 18 is detected in real time by a subcooler outlet temperature sensor 24inj,out；
When the temperature T of the external heat sourceh,inTemperature T of ejection outlet of subcoolerinj,outWhen the heat source enters the subcooler 16, the external heat source pump 21 is controlled to start to operate, so that the external heat source 20 can enter the subcooler 16;
after the external heat source pump 21 is started to operate,
when the temperature T of the injection inlet of the subcoolerinj,in+ set value A is less than or equal to external heat source temperature Th,in< temperature T of ejection outlet of subcoolerinj,outIn this case, the external heat source pump 21 is kept in a continuous operation state;
when the temperature T of the external heat sourceh,in< temperature T of injection inlet of subcoolerinj,inWhen the value is + the set value A, controlling the external heat source pump 21 to stop running;
wherein the set value A is a system preset temperature value of the heat pump, and the injection inlet temperature T of the subcoolerinj,in+ set value A < subcooler jet outlet temperature Tinj,out。
The setting value a is mainly set to prevent frequent switching of the heat source, and may be determined based on actual Th, in changes.
The setting value A is mainly set to prevent the external heat source pump 21 from being started and stopped frequently, so that the specific value can be set according to the actual external heat source temperature Th,inA change is determined.
The manner of adjusting the opening degrees of the main throttle 4 and the subcooling throttle 17 in this embodiment is the same as that in embodiment 2, and therefore, the description thereof is omitted.
The above examples are only for describing the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should be made within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.

Claims (7)

1. A refrigerant active injection heat pump based on a low-grade heat source is characterized in that: the heat pump system comprises a heat pump system, an injection system, an external heat source (20) and an external heat source pump (21), wherein the heat pump system comprises a compressor (1), a condenser (2), an evaporator (3), a main throttle valve (4) and a four-way valve (5) which are communicated in a circulating manner; the injection system comprises a subcooler (16) and a subcooling throttle valve (17), a refrigerant heat exchange tube (18) and an external heat source heat exchange tube (19) are arranged on the subcooler (16), one end of the subcooling throttle valve (17) is communicated with the outlet end of a condenser (2), the other end of the subcooling throttle valve (17) is communicated with the inlet end of the refrigerant heat exchange tube (18), the outlet end of the refrigerant heat exchange tube (18) is communicated with the middle pressure cavity of a compressor (1), and an external heat source pump (21) is communicated between the inlet end of the external heat source heat exchange tube (19) and the outlet end of an external heat source (20).
2. A refrigerant active injection heat pump based on a low-grade heat source according to claim 1, characterized in that: an external heat source temperature sensor (22) is arranged at the outlet end of the external heat source (20), a subcooler inlet temperature sensor (23) is arranged at the inlet end of the refrigerant heat exchange tube (18), and a subcooler outlet temperature sensor (24) is arranged at the outlet end of the refrigerant heat exchange tube (18).
3. A method for controlling a low-grade heat source based active injection heat pump for refrigerant, according to claim 2, comprising the steps of:
in the operation process of the heat pump, the opening of the main throttle valve (4) and the supercooling throttle valve (17) is adjusted according to a certain target, and meanwhile, the external heat source temperature sensor (22) detects the opening in real timeTemperature T of external heat sourceh,inThe temperature T of the injection inlet of the subcooler at the inlet end of the refrigerant heat exchange tube (18) is detected in real time by the subcooler inlet temperature sensor (23)inj,inDetecting in real time the subcooler spray inlet temperature T at the outlet end of the refrigerant heat exchange tube (18) by passing through the chiller outlet temperature sensor (24)inj,out；
When the temperature T of the external heat sourceh,inTemperature T of ejection outlet of subcooler is not more thaninj,outWhen the heat source enters the subcooler (16), controlling the external heat source pump (21) to stop running so that the external heat source (20) does not enter the subcooler (16);
when the temperature T of the external heat sourceh,inTemperature T of ejection outlet of subcoolerinj,outAnd controlling the external heat source pump (21) to start operation so that the external heat source (20) can enter the subcooler (16).
4. The method of claim 3, wherein the method comprises: in the low-grade heat source-based refrigerant active injection heat pump, a suction temperature sensor (26) is arranged on a pipeline connected with a suction port of the compressor (1), and an evaporator inlet temperature sensor (28) is arranged on a pipeline connected with an inlet end of the evaporator (3);
the main throttle valve (4) is controlled and adjusted according to the superheat degree of the heat pump, and the superheat degree of the heat pump is defined as follows:
compressor suction temperature TsDefrost temperature Tdef；
When the actual superheat degree is larger than the target superheat degree, the main throttle valve (4) is opened to be large;
when the actual superheat degree is smaller than the target superheat degree, the main throttle valve (4) is closed;
when the actual superheat degree is equal to the target superheat degree, the main throttle valve (4) keeps the current opening degree;
wherein the target superheat degree is a system preset temperature value of the heat pump, and the suction temperature T of the compressorsA defrost temperature T obtained by the suction temperature sensor (26)defIs acquired by the evaporator inlet temperature sensor (28).
5. The method of claim 3, wherein the method comprises: in the low-grade heat source-based refrigerant active jet heat pump, a pipeline connected with the outlet end of the condenser (2) is provided with a condenser outlet temperature sensor (27), and a pipeline connected with the exhaust port of the compressor (1) is provided with a high-pressure sensor (14);
the supercooling throttle valve (17) is controlled and adjusted according to the supercooling degree of the heat pump, and the supercooling degree of the heat pump is defined as:
saturation temperature P corresponding to high pressure of heat pumpd_tLiquid tube temperature Tliq；
When the actual supercooling degree is larger than the target supercooling degree, the supercooling throttle valve (17) is opened to be large;
when the actual supercooling degree is less than the target supercooling degree, the supercooling throttle valve (17) is closed;
when the actual supercooling degree is equal to the target supercooling degree, the supercooling throttle valve (17) keeps the current opening degree;
wherein, the target supercooling degree is a system preset temperature value of the heat pump and a saturation temperature P corresponding to the high pressure of the heat pumpd_tThe high pressure sensor (14) obtains the high pressure of the heat pump and then converts the high pressure to obtain the temperature T of the liquid pipeliqIs acquired by the condenser outlet temperature sensor (27).
6. The method for controlling a low-grade heat source based active injection heat pump for refrigerant according to claim 5, wherein: in the refrigerant active injection heat pump based on the low-grade heat source, an exhaust temperature sensor (25) is arranged on a pipeline connected with an exhaust port of the compressor (1);
the supercooling throttle valve (17) is corrected and adjusted according to the exhaust superheat degree of a compressor of the heat pump, and the exhaust superheat degree of the compressor of the heat pump is defined as:
compressor discharge temperature Td-saturation temperature P corresponding to high pressure of heat pumpd_t；
When the actual compressor exhaust superheat degree is less than a set value B, the supercooling throttle valve (17) is closed;
when the actual compressor exhaust superheat degree is larger than a set value C, the supercooling throttle valve (17) is opened greatly;
when the set value B is less than or equal to the actual compressor exhaust superheat degree and less than or equal to the set value C, the supercooling throttle valve (17) is controlled and adjusted according to the target supercooling degree of the heat pump;
the set value B and the set value C are both system preset temperature values of the heat pump, and the set value C is larger than the set value B; compressor discharge temperature TdIs acquired by the exhaust gas temperature sensor (25).
7. The method for controlling a low-grade heat source based active injection heat pump for refrigerant, according to claim 3, 4, 5 or 6, further comprising the steps of:
after the external heat source pump (21) is started,
when the temperature T of the injection inlet of the subcoolerinj,in+ set value A is less than or equal to external heat source temperature Th,in< temperature T of ejection outlet of subcoolerinj,outKeeping the external heat source pump (21) in a continuous operation state;
when the temperature T of the external heat sourceh,in< temperature T of injection inlet of subcoolerinj,inWhen the external heat source pump (21) is controlled to stop running at the + set value A;
wherein the set value A is a system preset temperature value of the heat pump, and the injection inlet temperature T of the subcoolerinj,in+ set value A < subcooler jet outlet temperature Tinj,out。
CN202010341180.5A 2020-04-27 2020-04-27 Refrigerant active injection heat pump based on low-grade heat source and control method thereof Pending CN111623555A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010341180.5A CN111623555A (en) 2020-04-27 2020-04-27 Refrigerant active injection heat pump based on low-grade heat source and control method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010341180.5A CN111623555A (en) 2020-04-27 2020-04-27 Refrigerant active injection heat pump based on low-grade heat source and control method thereof

Publications (1)

Publication Number Publication Date
CN111623555A true CN111623555A (en) 2020-09-04

Family

ID=72258087

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010341180.5A Pending CN111623555A (en) 2020-04-27 2020-04-27 Refrigerant active injection heat pump based on low-grade heat source and control method thereof

Country Status (1)

Country Link
CN (1) CN111623555A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115289732A (en) * 2022-07-04 2022-11-04 广东纽恩泰新能源科技发展有限公司 Heat pump system control method and device, electronic equipment and storage medium

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115289732A (en) * 2022-07-04 2022-11-04 广东纽恩泰新能源科技发展有限公司 Heat pump system control method and device, electronic equipment and storage medium
CN115289732B (en) * 2022-07-04 2023-11-21 广东纽恩泰新能源科技发展有限公司 Heat pump system control method and device, electronic equipment and storage medium

Similar Documents

Publication Publication Date Title
CN109282545B (en) Air-supplying and enthalpy-increasing control method of low-temperature direct-current variable-frequency heat pump system
WO2019200951A1 (en) Air conditioning heat pump system and control method
CN103629873B (en) The control method of Two-stage Compression air-conditioning system
CN109099610B (en) Air-supplementing enthalpy-increasing refrigerating system, air conditioner and air conditioner control method
CN109556210B (en) Control method of low-temperature triple heat supply pump system
CN202993700U (en) Two-stage compression refrigeration system with liquid supplementing and cooling functions
CN110848845B (en) Air supplementing and enthalpy increasing heat pump system, control method and air conditioner
CN110285598B (en) Enhanced vapor injection air conditioning system and method, enhanced vapor injection air conditioner and readable storage medium
CN110749116A (en) Enthalpy-increasing auxiliary road control method for low-temperature heat pump system, low-temperature heat pump system and enthalpy-increasing auxiliary road structure of low-temperature heat pump system
CN100439809C (en) Air supplementing system and air supplementing control method for compressor
CN108317772B (en) Air-supplying and enthalpy-increasing system and household appliance
CN2926935Y (en) Low-temperature heat pump air conditioning system
CN111288677A (en) Air source heat pump system and control method thereof
CN111623555A (en) Refrigerant active injection heat pump based on low-grade heat source and control method thereof
CN2849548Y (en) Air supplementing system of compressor
CN111829215A (en) Control method for improving refrigeration energy efficiency of low-temperature heat pump unit through electromagnetic valve
CN108759157B (en) One-time throttling two-stage compression heat pump system
CN115111811A (en) All-weather air source heat pump
CN108167184B (en) Scroll compressor wide area adaptive system
CN114353383B (en) Air source heat pump unit control method and air source heat pump unit
CN212029926U (en) Refrigerant active injection heat pump based on low-grade heat source
CN111649504B (en) Refrigerant active injection heat pump based on solar energy and control method thereof
CN215571358U (en) Compound refrigerating system with natural cooling function
CN115164431A (en) Injection refrigerating system
CN211400161U (en) Heat pump system and air conditioner

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination