CN109341132B - Heat pump system and control method thereof - Google Patents
Heat pump system and control method thereof Download PDFInfo
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- CN109341132B CN109341132B CN201811360760.8A CN201811360760A CN109341132B CN 109341132 B CN109341132 B CN 109341132B CN 201811360760 A CN201811360760 A CN 201811360760A CN 109341132 B CN109341132 B CN 109341132B
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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
- F25B13/00—Compression machines, plants or systems, with reversible cycle
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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
- F25B31/00—Compressor 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
- 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
- F25B43/00—Arrangements for separating or purifying gases or liquids; Arrangements for vaporising the residuum of liquid refrigerant, e.g. by heat
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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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- 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
- F25B49/022—Compressor control 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
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/07—Details of compressors or related parts
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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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- 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
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/19—Pressures
- F25B2700/193—Pressures of the compressor
- F25B2700/1931—Discharge pressures
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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
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/19—Pressures
- F25B2700/193—Pressures of the compressor
- F25B2700/1933—Suction pressures
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
Abstract
The invention provides a heat pump system and a control method thereof. The heat pump system comprises a compressor, an indoor heat exchanger, an outdoor heat exchanger, a flash evaporator and a pressure regulating device, wherein the compressor comprises a main cylinder and an auxiliary cylinder, the flash evaporator is arranged between the indoor heat exchanger and the outdoor heat exchanger, the pressure regulating device is arranged between a liquid refrigerant outlet of the flash evaporator and the indoor heat exchanger, a gaseous refrigerant outlet of the flash evaporator is connected to an air suction port of the auxiliary cylinder, and the pressure regulating device is used for regulating refrigerant pressure difference at two ends of the pressure regulating device under refrigeration working conditions so that the refrigerant pressure difference at two ends of the pressure regulating device is in a first preset range or the refrigerant pressure difference at two ends of the pressure regulating device is in a second preset range, and the minimum value of the second preset range is larger than the maximum value of the first preset range. According to the heat pump system, the switching between medium-pressure air supplementing and low-pressure air supplementing of the compressor can be conveniently realized, the structure and the control system are simple, and the realization cost is low.
Description
Technical Field
The invention belongs to the technical field of air conditioning, and particularly relates to a heat pump system and a control method thereof.
Background
Patent publication No. CN106766367a discloses an air conditioning system, which uses an auxiliary compression cylinder to directly compress refrigerant gas in an intermediate-pressure gas-liquid separator and send the compressed gas to a condenser together with master cylinder exhaust gas, and refrigerant liquid in the gas-liquid separator enters an evaporator for evaporation after secondary throttling. Compared with the conventional system, the system can reduce the throttling dryness of the refrigerant entering the evaporator and obviously improve the capacity energy efficiency value of the refrigeration system. The system is provided with two stop valves, and the switching of the air supplementing mode is realized by connecting the air outlet of the gas-liquid separator with the air inlet of the air supplementing cylinder or connecting the air outlet of the main compression cylinder through the opening and closing combination of the two stop valves, so that the cylinder body liquid impact damage caused by the excessive air supplementing and liquid carrying of the auxiliary compression cylinder is avoided.
However, the air supplementing mode conversion structure in the system is complex, so that the control system is complex, the control cost is high, and the implementation cost is high.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to provide the heat pump system and the control method thereof, which can conveniently realize the switching between the medium-pressure air supplement and the low-pressure air supplement of the compressor, and have simple structure and control system and lower realization cost.
In order to solve the above problems, the present invention provides a heat pump system including a compressor, an indoor heat exchanger, an outdoor heat exchanger, a flash evaporator, and a pressure adjusting device, wherein the compressor includes a main cylinder and an auxiliary cylinder, the flash evaporator is disposed between the indoor heat exchanger and the outdoor heat exchanger, the pressure adjusting device is disposed between a liquid refrigerant outlet of the flash evaporator and the indoor heat exchanger, a gaseous refrigerant outlet of the flash evaporator is connected to an air suction port of the auxiliary cylinder, and the pressure adjusting device is used for adjusting a refrigerant pressure difference across the pressure adjusting device under a cooling condition such that the refrigerant pressure difference across the pressure adjusting device is within a first preset range, or such that the refrigerant pressure difference across the pressure adjusting device is within a second preset range, wherein a minimum value of the second preset range is greater than a maximum value of the first preset range.
Preferably, a first throttle valve is provided between the outdoor heat exchanger and the flash vessel.
Preferably, a first control valve is provided on a line between the gaseous refrigerant outlet of the flash vessel and the suction port of the auxiliary cylinder.
Preferably, the pressure regulating device comprises a second control valve and a second throttle valve connected in parallel.
Preferably, the pressure adjusting device comprises a second throttle valve, when the opening degree of the second throttle valve is in a first range, the pressure difference between two ends of the second throttle valve is in a first preset range, and when the opening degree of the second throttle valve is in a second range, the pressure difference between two ends of the second throttle valve is in a second preset range.
Preferably, the heat pump system further comprises a four-way valve disposed at the discharge end of the compressor.
According to another aspect of the present invention, there is provided a control method of the heat pump system described above, including:
acquiring the operation condition of a heat pump system;
when the heat pump system is in a refrigeration mode, working parameters of a main cylinder of the compressor are obtained;
determining an air supplementing mode of the auxiliary cylinder according to working parameters of a main cylinder of the compressor;
the pressure regulating device is regulated so that the auxiliary cylinder is operated in the determined air-supplementing mode.
Preferably, before acquiring the operation parameter of the master cylinder of the compressor, the control method further includes:
controlling the auxiliary cylinder to operate according to a low-pressure air supplementing mode in a starting-up starting stage;
the first throttle opening is adjusted so that the suction superheat Δtsuc of the master cylinder is within a preset range.
Preferably, the preset range of the suction superheat Δtsuc of the master cylinder is 3 to 5 ℃.
Preferably, the step of determining the air supplementing mode of the auxiliary cylinder according to the operation condition of the heat pump system and the operation parameter of the main cylinder of the compressor comprises:
determining the suction-exhaust pressure ratio Pc/Pe of the master cylinder;
if Pc/Pe is less than n, controlling the heat pump system to operate in a low-pressure air supplementing mode;
and if Pc/Pe is more than or equal to n, controlling the heat pump system to operate in a medium-pressure air supplementing mode.
Preferably, the step of adjusting the pressure regulating device such that the auxiliary cylinder operates in the determined air-make-up mode comprises:
if Pc/Pe is smaller than n, controlling the second control valve to be opened, so that the pressure difference of the refrigerants at two ends of the pressure regulating device is within a first preset range;
if Pc/Pe is more than or equal to n, the second control valve is controlled to be closed, and the second throttle valve is regulated, so that the refrigerant pressure difference at two ends of the pressure regulating device is within a second preset range.
Preferably, the step of determining the air supplementing mode of the auxiliary cylinder according to the operation condition of the heat pump system and the operation parameter of the main cylinder of the compressor comprises:
determining the ratio Tc/Te of the condensing temperature and the evaporating temperature of the indoor heat exchanger;
the air make-up mode of the heat pump system is determined based on Tc/Te.
Preferably, when the heat pump system is in the heating mode, the second control valve is controlled to be in a closed state, so that the heat pump system operates in the medium-pressure air supplementing mode;
the opening combination of the first throttle valve and the second throttle valve is adjusted according to the suction superheat degree of the refrigerant in the master cylinder suction port and the refrigerant entrainment rate in the auxiliary cylinder suction port.
The invention provides a heat pump system, which comprises a compressor, an indoor heat exchanger, an outdoor heat exchanger, a flash evaporator and a pressure regulating device, wherein the compressor comprises a main cylinder and an auxiliary cylinder, the flash evaporator is arranged between the indoor heat exchanger and the outdoor heat exchanger, the pressure regulating device is arranged between a liquid refrigerant outlet of the flash evaporator and the indoor heat exchanger, a gaseous refrigerant outlet of the flash evaporator is connected to an air suction port of the auxiliary cylinder, and the pressure regulating device is used for regulating the refrigerant pressure difference at two ends of the pressure regulating device under refrigeration working conditions so that the refrigerant pressure difference at two ends of the pressure regulating device is in a first preset range or the refrigerant pressure difference at two ends of the pressure regulating device is in a second preset range, wherein the minimum value of the second preset range is larger than the maximum value of the first preset range. When the heat pump system is in a refrigerating working condition, the pressure difference at two ends of the pressure regulating device can be regulated through the pressure regulating device, so that the refrigerant pressure in the flash evaporator is in a low-pressure state which is the same as the refrigerant pressure in the indoor heat exchanger when the heat pump system is operated under a low-pressure ratio working condition, and low-pressure air supplementing is realized; when the heat pump system operates under the working condition of high pressure ratio, the refrigerant pressure in the flash evaporator is in an intermediate pressure state between the high pressure and the low pressure refrigerant pressure in the indoor heat exchanger, so that the medium pressure air supplement is realized, the conversion of the system air supplement mode under different working conditions can be realized through the pressure regulating device, the heat pump system can operate efficiently under different working conditions, the switching of the medium pressure air supplement and the low pressure air supplement of the compressor can be conveniently realized, the structure and the control system are simple, and the realization cost is lower.
Drawings
FIG. 1 is a schematic diagram of a heat pump system according to an embodiment of the present invention;
FIG. 2 is a refrigerant flow diagram of a low pressure air make-up mode of a heat pump system according to an embodiment of the present invention under refrigeration conditions;
FIG. 3 is a refrigerant flow diagram of a heat pump system in a start-up phase under refrigeration conditions according to an embodiment of the present invention;
FIG. 4 is a refrigerant flow diagram of a medium pressure air make-up mode of a heat pump system according to an embodiment of the present invention under refrigeration conditions;
FIG. 5 is a refrigerant flow diagram of a heat pump system according to an embodiment of the present invention under heating conditions;
FIG. 6 is a schematic diagram illustrating the overall refrigerant flow of a heat pump system according to an embodiment of the present invention;
FIG. 7 is a control schematic diagram of a heat pump system according to an embodiment of the present invention;
fig. 8 is a control flow chart of the heat pump system according to the embodiment of the invention.
The reference numerals are expressed as:
1. a master cylinder; 2. an auxiliary cylinder; 3. an indoor heat exchanger; 4. an outdoor heat exchanger; 5. a flash; 6. a first throttle valve; 7. a first control valve; 8. a second throttle valve; 9. a second control valve; 10. and a four-way valve.
Detailed Description
As shown in fig. 1 to 6 in combination, according to an embodiment of the present invention, a heat pump system includes a compressor including a master cylinder 1 and an auxiliary cylinder 2, an indoor heat exchanger 3, an outdoor heat exchanger 4, a flash tank 5, and a pressure adjusting device disposed between the indoor heat exchanger 3 and the outdoor heat exchanger 4, a liquid refrigerant outlet of the flash tank 5 and the indoor heat exchanger 3, a gaseous refrigerant outlet of the flash tank 5 being connected to an air suction port of the auxiliary cylinder 2, the pressure adjusting device being configured to adjust a refrigerant pressure difference across the pressure adjusting device under a cooling condition such that the refrigerant pressure difference across the pressure adjusting device is within a first preset range, or such that the refrigerant pressure difference across the pressure adjusting device is within a second preset range, wherein a minimum value of the second preset range is greater than a maximum value of the first preset range.
Wherein the indoor heat exchanger 3 and the outdoor heat exchanger 4 are both connected to the main cylinder 1 of the compressor, the flash vessel 5 is connected between the indoor heat exchanger 3 and the outdoor heat exchanger 4, and the gaseous refrigerant outlet of the flash vessel 5 is connected to the auxiliary cylinder 2 of the compressor.
When the heat pump system is in a refrigerating working condition, the pressure difference at two ends of the pressure regulating device can be regulated through the pressure regulating device, so that the refrigerant pressure in the flash tank 5 is in a low-pressure state which is the same as the refrigerant pressure in the indoor heat exchanger 3 when the heat pump system is operated under a low-pressure ratio working condition, and low-pressure air supplementing is realized; when the heat pump system operates under the working condition of high pressure ratio, the refrigerant pressure in the flash generator 5 is in an intermediate pressure state between the high pressure and the low pressure refrigerant pressure in the indoor heat exchanger 3, so that medium pressure air supplement is realized, and the conversion of the system air supplement mode under different working conditions can be realized through the pressure regulating device, so that the heat pump system can operate efficiently under different working conditions, the switching of the medium pressure air supplement and the low pressure air supplement of the compressor can be conveniently realized, the structure and the control system are simple, and the realization cost is lower.
In this embodiment, when the pressure difference between the refrigerant at both ends of the pressure adjusting device is within a first preset range, the refrigerant pressure at the gaseous refrigerant outlet of the flash evaporator 5 is low, when the pressure difference between the refrigerant at both ends of the pressure adjusting device is within a second preset range, the refrigerant pressure at the gaseous refrigerant outlet of the flash evaporator 5 is medium pressure, and when the refrigerant pressure is low, the refrigerant pressure at the gaseous refrigerant outlet of the flash evaporator 5 is equal to the refrigerant pressure in the indoor heat exchanger 3 or the pressure difference is within a smaller range; when the refrigerant pressure is medium pressure, the pressure difference between the refrigerant pressure of the gaseous refrigerant outlet of the flash evaporator 5 and the refrigerant pressure in the indoor heat exchanger 3 is in a larger range, so that the refrigerant pressure of the gaseous refrigerant outlet of the flash evaporator 5 is between the pressure of the low-pressure refrigerant in the indoor heat exchanger 3 and the pressure of the high-pressure refrigerant of the compressor exhaust port.
A first throttle valve 6 is provided between the outdoor heat exchanger 4 and the flash tank 5. The first throttle valve 6 is used for performing first throttling and depressurization on the refrigerant after heat release and condensation of the outdoor heat exchanger 4, and reducing the pressure of the refrigerant, so that the liquid refrigerant can be partially gasified, and enough gaseous refrigerant is generated in the flash evaporator 5, thereby meeting the air supplementing requirement of a heat pump system.
Preferably, a first control valve 7 is provided in the line between the gaseous refrigerant outlet of the flash tank 5 and the suction port of the auxiliary cylinder 2. The first control valve 7 is arranged on the air supplementing pipeline and can control the on-off of the air supplementing pipeline, so as to control whether the heat pump system supplements air or not. The first control valve 7 is not required to be arranged on the air supplementing pipeline, so that the air supplementing pipeline is always communicated with the gaseous refrigerant outlet of the flash evaporator 5 and the air suction port of the auxiliary cylinder 2, and the air supplementing operation of the compression cylinder is realized. The first control valve 7 is, for example, a shut-off valve, and may be another type of electromagnetic valve having an opening and closing function, or the like.
In this embodiment, the pressure regulating means comprises a second control valve 9 and a second throttle valve 8 connected in parallel.
The air suction port of the auxiliary cylinder 2 can be respectively connected with the medium-pressure air supply port or the low-pressure air supply port through the valve opening and closing combination adjustment of the second control valve 9 and the second throttle valve 8, so that the conversion of the system mode under different working conditions is realized, and the heat pump system can realize the efficient operation under different working conditions. Under the working condition of high pressure ratio, the air suction port of the auxiliary cylinder 2 is connected with the medium pressure air supplementing phase through valve opening and closing combination adjustment, and at the moment, the indoor heat exchanger 3 is connected with the flash generator 5 through the second throttle valve 8 to realize the medium pressure air supplementing phase; when the air conditioner operates under the working condition of low pressure ratio, the air suction port of the auxiliary cylinder 2 is connected with the low pressure air supplementing port through valve opening and closing combination adjustment, at the moment, the indoor heat exchanger 3 is directly connected with the flash evaporator 5 through a connecting pipeline, and the pressure in the flash evaporator 5 is the same as the pressure of the refrigerant in the indoor heat exchanger 3, so that low pressure air supplementing is realized.
Specifically, when the second control valve 9 is closed and the first control valve 7 is opened, the outdoor heat exchanger 4 is connected with the indoor heat exchanger 3 through the first throttle valve 6, the flash tank 5 and the second throttle valve 8, at this time, the refrigerant pressure in the flash tank 5 is the intermediate pressure between the high pressure and the low pressure, at this time, the suction pressure of the auxiliary cylinder 2 is the intermediate pressure, namely, the medium pressure air supplementing, in the operation mode, the auxiliary cylinder 2 reduces the dryness of the refrigerant entering the indoor heat exchanger 3 through sucking the medium pressure air, so that the unit mass refrigeration capacity and the system operation energy efficiency of the master cylinder 1 are improved, the mode is suitable for the occasion that the throttle dryness of the indoor heat exchanger 3 is larger, namely, the occasion that the suction and the discharge pressure of the compressor is larger, and when the suction and discharge pressures are larger, the air supplementing pressure is provided to improve the air supplementing mass flow of the auxiliary cylinder 2, and the improvement of the capacity energy efficiency of the heat pump system is more beneficial.
When the first control valve 7 is opened and the second control valve 9 is also opened, the pressure of the refrigerant in the flash evaporator 5 is the same as the pressure of the refrigerant at the indoor heat exchanger 3, at the moment, the suction pressure of the auxiliary cylinder 2 is low pressure suction, low pressure air supplement is realized, the dryness of the inlet of the indoor heat exchanger 3 is reduced by compressing the refrigerant gas separated from the flash evaporator 5, the service efficiency of the indoor heat exchanger 3 is improved, the unit mass refrigeration capacity and the system energy efficiency of the main cylinder 1 are increased, the device is suitable for occasions with lower load and occasions with low suction-discharge pressure ratio, the adverse influence caused by overlarge air supplement liquid carrying rate due to small air supplement under the low-load operation condition is avoided, and the operation reliability of the heat pump system is ensured.
In the embodiment, the low-pressure air supplementing and medium-pressure air supplementing of the auxiliary cylinder can be conveniently switched by simply combining and controlling the second throttle valve 8 and the second control valve 9, so that the heat pump system can switch modes under different load conditions, the operation efficiency of the heat pump system under different working conditions is ensured, the structure is simple, and the control cost is greatly reduced.
In another embodiment, not shown, the pressure regulating device comprises a second throttle valve 8, wherein when the opening of the second throttle valve 8 is within a first range, the pressure difference across the second throttle valve 8 is within a first preset range, and when the opening of the second throttle valve 8 is within a second range, the pressure difference across the second throttle valve 8 is within a second preset range. The second throttle valve 8 can have a larger opening adjustment range, so that the refrigerant pressure difference at two ends of the second throttle valve 8 can be kept within a first preset range in the adjustment process of the second throttle valve 8, and the low-pressure air supplement of the heat pump system is realized; the pressure difference of the refrigerants at the two ends of the second throttle valve 8 can be kept within a second preset range, and medium-pressure air supplement of the heat pump system is realized. Since the adjustment range of the second throttle valve 8 can meet the low-pressure air-supplementing requirement and the high-pressure air-supplementing requirement of the heat pump system, the second control valve 9 is not required.
The heat pump system further comprises a four-way valve 10, wherein the four-way valve 10 is arranged at the exhaust end of the compressor. By arranging the four-way valve 10, the switching of the refrigerating and heating working conditions of the heat pump system can be conveniently realized.
Referring to fig. 7 and 8 in combination, according to an embodiment of the present invention, a control method of the heat pump system includes: acquiring the operation condition of a heat pump system; when the heat pump system is in a refrigeration mode, working parameters of a main cylinder 1 of the compressor are obtained; determining an air supplementing mode of the auxiliary cylinder 2 according to the working parameters of the main cylinder 1 of the compressor; the pressure regulating device is adjusted such that the auxiliary cylinder 2 is operated in the determined air-make-up mode.
The control method further includes, before acquiring the operation parameters of the master cylinder 1 of the compressor: the auxiliary cylinder 2 is controlled to operate according to a low-pressure air supplementing mode in a starting-up starting stage; the opening degree of the first throttle valve 6 is adjusted so that the suction superheat Δtsuc of the master cylinder 1 is within a preset range. During the startup phase, since the refrigerant is stored in the flash tank 5, the risk that the refrigerant stored in the flash tank 5 enters the auxiliary cylinder 2 to cause the auxiliary cylinder 2 to generate liquid impact easily occurs, and the refrigerant entering the auxiliary cylinder 2 can be all gaseous refrigerant by controlling the auxiliary cylinder 2 to operate according to the low-pressure air supplementing mode, so that the liquid refrigerant is effectively prevented from entering the auxiliary cylinder 2 to generate liquid impact phenomenon, and the compressor operation is effectively protected.
By controlling the opening degree of the first throttle valve 6, the suction superheat degree of the master cylinder 1 can be made within a preset range, and the problem of reduction in operation energy efficiency due to an excessively high suction superheat degree of the compressor master cylinder 1 can be avoided.
Preferably, the preset range of the suction superheat Δtsuc of the master cylinder 1 is 3 to 5 ℃.
The step of determining the air supplementing mode of the auxiliary cylinder 2 according to the operation condition of the heat pump system and the operation parameter of the main cylinder 1 of the compressor includes:
determining an air suction/exhaust pressure ratio Pc/Pe of the master cylinder 1;
if Pc/Pe is less than n, controlling the heat pump system to operate in a low-pressure air supplementing mode;
and if Pc/Pe is more than or equal to n, controlling the heat pump system to operate in a medium-pressure air supplementing mode.
The step of adjusting the pressure adjusting means such that the auxiliary cylinder 2 is operated in the determined air-make-up mode comprises:
if Pc/Pe is smaller than n, the second control valve 9 is controlled to be opened, so that the pressure difference of the refrigerants at two ends of the pressure regulating device is within a first preset range;
if Pc/Pe is more than or equal to n, the second control valve 9 is controlled to be closed, and the second throttle valve 8 is regulated, so that the refrigerant pressure difference at the two ends of the pressure regulating device is within a second preset range. Wherein n has a value of 1.5 to 2.0.
The step of determining the air supplementing mode of the auxiliary cylinder 2 according to the operation condition of the heat pump system and the operation parameter of the main cylinder 1 of the compressor includes:
determining the ratio Tc/Te of the condensing temperature and the evaporating temperature of the indoor heat exchanger 3;
the air make-up mode of the heat pump system is determined based on Tc/Te. Wherein the condensing temperature and evaporating temperature of the indoor heat exchanger 3 are detected by a temperature sensing bulb arranged in the middle of the indoor heat exchanger 3. The value range of Tc/Te can be set according to the actual working condition of the heat pump system.
When the heat pump system is in the heating mode, the second control valve 9 is controlled to be in a closed state, so that the heat pump system operates in the medium-pressure air supplementing mode; the opening combination of the first throttle valve 6 and the second throttle valve 8 is adjusted according to the suction superheat degree of the refrigerant in the suction port of the master cylinder 1 and the refrigerant entrainment rate in the suction port of the auxiliary cylinder 2.
The operation of the heat pump system of the present embodiment will be described below:
when the heat pump system is started in the refrigeration mode, in order to ensure that excessive refrigerant liquid in the flash evaporator 5 enters the auxiliary cylinder 2 in the starting stage, the operation is performed in the low-pressure air supplementing mode in the starting initial stage, and the air suction superheat degree delta Tsu of the main cylinder 1 is controlled to be within a reasonable range by adjusting the opening degree of the first throttle valve 6, and the delta Tsu is generally at a value of 3-5 ℃. After the stable operation is carried out for a period of time, judging whether the system is operated in a medium-pressure air supplementing mode or a low-pressure air supplementing mode by detecting the value of the air suction/exhaust pressure ratio Pc/Pe of the main cylinder 1, and when Pc/Pe is smaller than n, the system is operated in the low-pressure air supplementing mode, and then the second control valve 9 needs to be opened; when Pc/Pe is more than or equal to n, the second control valve 9 is closed, the refrigerant enters the indoor heat exchanger 3 from the liquid refrigerant outlet of the flash evaporator 5 through the second throttle valve 8, the medium-pressure air supplementing operation is realized, and the suction superheat degree of the refrigerant of the main cylinder suction port and the refrigerant liquid carrying rate of the auxiliary cylinder suction port can meet the design target by adjusting the opening degrees of the first throttle valve 6 and the second throttle valve 8. Wherein the value of n is 1.5-2.0.
It will be readily appreciated by those skilled in the art that the above advantageous ways can be freely combined and superimposed without conflict.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention. The foregoing is merely a preferred embodiment of the present invention, and it should be noted that it will be apparent to those skilled in the art that modifications and variations can be made without departing from the technical principles of the present invention, and these modifications and variations should also be regarded as the scope of the invention.
Claims (11)
1. A heat pump system, characterized by comprising a compressor, an indoor heat exchanger (3), an outdoor heat exchanger (4), a flash evaporator (5) and a pressure regulating device, wherein the compressor comprises a main cylinder (1) and an auxiliary cylinder (2), the flash evaporator (5) is arranged between the indoor heat exchanger (3) and the outdoor heat exchanger (4), the pressure regulating device is arranged between a liquid refrigerant outlet of the flash evaporator (5) and the indoor heat exchanger (3), a gaseous refrigerant outlet of the flash evaporator (5) is connected to an air suction port of the auxiliary cylinder (2), and the pressure regulating device is used for regulating refrigerant pressure differences at two ends of the pressure regulating device under a refrigeration working condition, so that the refrigerant pressure differences at two ends of the pressure regulating device are in a first preset range, or the refrigerant pressure differences at two ends of the pressure regulating device are in a second preset range, wherein the minimum value of the second preset range is larger than the maximum value of the first preset range;
the pressure regulating device comprises a second control valve (9) and a second throttle valve (8) which are connected in parallel, and the suction-exhaust pressure ratio Pc/Pe of the main cylinder (1) is determined;
if Pc/Pe is smaller than n, controlling the second control valve (9) to be opened, so that the pressure difference of the refrigerants at two ends of the pressure regulating device is within the first preset range to reduce the dryness of the refrigerants entering the indoor heat exchanger (3);
if Pc/Pe is more than or equal to n, the second control valve (9) is controlled to be closed, and the second throttle valve (8) is regulated, so that the refrigerant pressure difference at two ends of the pressure regulating device is within the second preset range to reduce the dryness of the refrigerant entering the indoor heat exchanger (3).
2. Heat pump system according to claim 1, characterized in that a first throttle valve (6) is arranged between the outdoor heat exchanger (4) and the flash vessel (5).
3. Heat pump system according to claim 1, characterized in that a first control valve (7) is arranged in the line between the gaseous refrigerant outlet of the flash tank (5) and the suction opening of the auxiliary cylinder (2).
4. A heat pump system according to any one of claims 1-3, characterized in that the pressure regulating means comprises a second throttle valve (8), the pressure difference across the second throttle valve (8) being within a first preset range when the opening of the second throttle valve (8) is within a first range, and the pressure difference across the second throttle valve (8) being within a second preset range when the opening of the second throttle valve (8) is within a second range.
5. A heat pump system according to any one of claims 1-3, characterized in that the heat pump system further comprises a four-way valve (10), the four-way valve (10) being arranged at the discharge end of the compressor.
6. A control method of the heat pump system according to any one of claims 1 to 5, comprising:
acquiring the operation condition of a heat pump system;
when the heat pump system is in a refrigeration mode, working parameters of a main cylinder (1) of the compressor are obtained;
determining an air supplementing mode of the auxiliary cylinder (2) according to the working parameters of the main cylinder (1) of the compressor;
the pressure regulating device is regulated so that the auxiliary cylinder (2) operates in the determined air-supplementing mode.
7. The control method according to claim 6, characterized in that it further comprises, before acquiring the operating parameters of the master cylinder (1) of the compressor:
the auxiliary cylinder (2) is controlled to operate according to a low-pressure air supplementing mode in a starting-up starting stage;
the opening degree of the first throttle valve (6) is regulated so that the suction superheat degree delta Tsu of the main cylinder (1) is within a preset range.
8. The control method according to claim 7, characterized in that the preset range of the suction superheat Δtsuc of the master cylinder (1) is 3-5 ℃.
9. The control method according to claim 6, wherein the step of determining the air supply mode of the auxiliary cylinder (2) according to the operation condition of the heat pump system and the operation parameter of the main cylinder (1) of the compressor comprises:
determining an air suction/exhaust pressure ratio Pc/Pe of the master cylinder (1);
if Pc/Pe is less than n, controlling the heat pump system to operate in a low-pressure air supplementing mode;
and if Pc/Pe is more than or equal to n, controlling the heat pump system to operate in a medium-pressure air supplementing mode.
10. A control method according to claim 9, characterized in that the step of adjusting the pressure adjusting means such that the auxiliary cylinder (2) is operated in the determined air-make-up mode comprises:
if Pc/Pe is smaller than n, the second control valve (9) is controlled to be opened, so that the refrigerant pressure difference at the two ends of the pressure regulating device is within a first preset range;
if Pc/Pe is more than or equal to n, the second control valve (9) is controlled to be closed, and the second throttle valve (8) is regulated, so that the refrigerant pressure difference at two ends of the pressure regulating device is within a second preset range.
11. The control method according to claim 6, wherein,
when the heat pump system is in a heating mode, the second control valve (9) is controlled to be in a closed state, so that the heat pump system operates in a medium-pressure air supplementing mode;
the opening combination of the first throttle valve (6) and the second throttle valve (8) is adjusted according to the suction superheat degree of the refrigerant in the suction port of the main cylinder (1) and the refrigerant entrainment rate of the suction port of the auxiliary cylinder (2).
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| CN201811360760.8A CN109341132B (en) | 2018-11-15 | 2018-11-15 | Heat pump system and control method thereof |
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| WO2020255192A1 (en) * | 2019-06-17 | 2020-12-24 | 三菱電機株式会社 | Refrigeration circuit device |
| CN110986416A (en) * | 2019-11-25 | 2020-04-10 | 珠海格力节能环保制冷技术研究中心有限公司 | Double-air-supplement heat pump system and control method thereof |
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| CN102232167A (en) * | 2008-10-01 | 2011-11-02 | 开利公司 | Liquid vapor separation in transcritical refrigerant cycle |
| CN105698425A (en) * | 2016-02-22 | 2016-06-22 | 广东美芝制冷设备有限公司 | Refrigeration device |
| CN205351844U (en) * | 2016-01-06 | 2016-06-29 | 广东美的制冷设备有限公司 | Changes in temperature type air conditioning system and single cold mould air conditioning system |
| CN106196787A (en) * | 2016-07-11 | 2016-12-07 | 珠海格力电器股份有限公司 | The control method of heat pump and heat pump |
| CN209085113U (en) * | 2018-11-15 | 2019-07-09 | 珠海格力电器股份有限公司 | Heat pump system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| DK2737265T3 (en) * | 2011-07-26 | 2018-03-19 | Carrier Corp | COOLING TEMPERATURE CONTROL LOGIC |
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|---|---|---|---|---|
| CN102232167A (en) * | 2008-10-01 | 2011-11-02 | 开利公司 | Liquid vapor separation in transcritical refrigerant cycle |
| CN205351844U (en) * | 2016-01-06 | 2016-06-29 | 广东美的制冷设备有限公司 | Changes in temperature type air conditioning system and single cold mould air conditioning system |
| CN105698425A (en) * | 2016-02-22 | 2016-06-22 | 广东美芝制冷设备有限公司 | Refrigeration device |
| CN106196787A (en) * | 2016-07-11 | 2016-12-07 | 珠海格力电器股份有限公司 | The control method of heat pump and heat pump |
| CN209085113U (en) * | 2018-11-15 | 2019-07-09 | 珠海格力电器股份有限公司 | Heat pump system |
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