CN114935223A - Air source heat pump system - Google Patents
Air source heat pump system Download PDFInfo
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- CN114935223A CN114935223A CN202210642290.4A CN202210642290A CN114935223A CN 114935223 A CN114935223 A CN 114935223A CN 202210642290 A CN202210642290 A CN 202210642290A CN 114935223 A CN114935223 A CN 114935223A
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- 239000003507 refrigerant Substances 0.000 claims abstract description 125
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 37
- 239000007788 liquid Substances 0.000 claims description 43
- 238000010438 heat treatment Methods 0.000 claims description 37
- 238000000034 method Methods 0.000 claims description 20
- 238000005057 refrigeration Methods 0.000 claims description 15
- 238000001816 cooling Methods 0.000 description 17
- 239000007791 liquid phase Substances 0.000 description 9
- 239000003921 oil Substances 0.000 description 9
- 238000010586 diagram Methods 0.000 description 7
- 238000009833 condensation Methods 0.000 description 5
- 230000005494 condensation Effects 0.000 description 5
- 239000010725 compressor oil Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 238000004378 air conditioning Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B30/00—Heat pumps
- F25B30/06—Heat pumps characterised by the source of low potential heat
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- 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
- F25B31/002—Lubrication
- F25B31/004—Lubrication oil recirculating 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
- F25B41/31—Expansion 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
- F25B2600/00—Control issues
- F25B2600/25—Control of valves
- F25B2600/2513—Expansion valves
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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
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Heat-Pump Type And Storage Water Heaters (AREA)
- Air Conditioning Control Device (AREA)
Abstract
The invention discloses an air source heat pump system, comprising: the compressor comprises a gas outlet of the compressor and a gas return port of the compressor; a water side heat exchanger; the air side heat exchanger is connected with the water side heat exchanger; four ports of the four-way valve are respectively connected with an exhaust port of the compressor, a return air port of the compressor, the water side heat exchanger and the air side heat exchanger through connecting pipes; the one-way valve is connected between an exhaust port of the compressor and the four-way valve, and the compressor is in one-way conduction with the four-way valve; an electronic expansion valve disposed between an air-side heat exchanger and the water-side heat exchanger; a control module configured to: and after receiving the stop signal, closing the electronic expansion valve, controlling the compressor to keep open, and closing the whole machine when the stop condition is met. The air source heat pump system can store the refrigerant on the high-pressure side after shutdown, and can effectively prevent the technical problem of oil shortage of the compressor during restarting.
Description
Technical Field
The invention relates to the technical field of household appliances, in particular to an air source heat pump system.
Background
The refrigerant quantity balance of the refrigeration system is a key problem, and the quantity of the refrigerant quantity is directly related to the refrigeration and heating capacity and the energy efficiency of the system, and the stable and reliable running state of the system. Especially for an air source heat pump unit, a finned tube heat exchanger is usually used on an air side, a plate heat exchanger is usually used on a water side, and the difference of the inner volumes of the two heat exchangers is huge, so that the required refrigerant amount has obvious difference during the cooling and heating operation.
For a refrigeration system using refrigerant with low flammability such as R32, the system refrigerant charge generally has a minimum room area requirement, and the smaller the system refrigerant charge, the easier it is to meet the room area requirement for on-site installation. Therefore, for the R32 refrigerant air-source heat pump product, the system design considers that no accumulator or as small an accumulator as possible is used, thereby reducing the refrigerant charge in the system. In the system, most of the refrigerant in the system is stored in a condenser in the system operation because the temperature of the condensation side is high and the pressure is high during refrigeration. For an air source heat pump system, a finned tube heat exchanger with a large inner volume is generally selected for the air side, and a plate heat exchanger with a small inner volume is generally selected for the water side. A compromise system refrigerant quantity filling scheme is adopted for filling the refrigerant into the system at present, and the filled refrigerant quantity is between the inner volume of the plate heat exchanger and the inner volume of the fin type heat exchanger. In general, when a heat pump system is operated in a cooling mode, most of refrigerant accumulates in an air-side heat exchanger serving as a condenser, and the air-side heat exchanger has a larger internal volume, so that the amount of refrigerant required for the cooling mode cannot be satisfied. In the heating operation, the refrigerant is accumulated in the water side heat exchanger as a condenser, and the water side heat exchanger has a small inner volume, so that the amount of the refrigerant required for the heating operation is smaller than that for the cooling operation, and the refrigerant circulating in the system may be excessive. Therefore, the cooling and heating operation systems are not operated in the optimal state, and a series of reliability problems, such as oil return problems, low-pressure or high-pressure alarm problems, and the like, are caused.
For a system without a liquid storage device or a gas separator, because the plate heat exchanger is positioned on a high-pressure side and the finned tube heat exchanger is on a low-pressure side, when the compressor is stopped, because the difference of the inner volumes of the two heat exchangers is overlarge, a large amount of refrigerants are stored in the finned tube heat exchanger, when the compressor is started again, the refrigerant enters the compressor from the low-pressure side, and then more compressor oil is taken away, so that the oil-empty phenomenon of the compressor is particularly serious, and the reliability of the long-term operation of the compressor is influenced.
Chinese patent No. CN201852347U, granted as shown in fig. 1, proposes a water source multi-split air conditioning system with a liquid storage device, in which a liquid storage device 4 is disposed, but the liquid storage device 4 does not have the function of storing extra redundant refrigerant when the heating is stopped, and there is no control method for improving reliability.
Disclosure of Invention
In order to solve the technical problem of oil shortage of the compressor during restarting caused by oil return of the compressor after the compressor is stopped in the prior art, the invention provides the air source heat pump system, which can effectively prevent the technical problem of oil shortage of the compressor during restarting by controlling the electronic expansion valve to be closed and controlling the compressor to be kept open after a stop signal is received, so that a refrigerant is stored on a high-pressure side.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides an air source heat pump system, comprising:
the compressor comprises an exhaust port of the compressor and a return port of the compressor;
a water-side heat exchanger that performs heat exchange between a refrigerant and water in an air-source heat pump system refrigeration cycle;
the air side heat exchanger is connected with the water side heat exchanger; which performs heat exchange between refrigerant and air in a refrigeration cycle of an air source heat pump system;
the four ports of the four-way valve are respectively connected with the exhaust port of the compressor, the return air port of the compressor, the water side heat exchanger and the air side heat exchanger through connecting pipes;
the one-way valve is connected between an exhaust port of the compressor and the four-way valve, and the compressor is in one-way conduction with the four-way valve;
an electronic expansion valve disposed between the air-side heat exchanger and the water-side heat exchanger;
a control module configured to:
and after a stop signal is received, closing the electronic expansion valve, controlling the compressor to keep open, and closing the whole machine when the stop condition is met.
In some embodiments of the present invention, in order to prevent a problem that a charged refrigerant amount cannot satisfy a condition that both a cooling operation and a heating operation can be performed in an optimal state, the air-source heat pump system further includes:
and the auxiliary liquid storage pipe section is connected between the water side heat exchanger and the air side heat exchanger, is arranged along the vertical direction and is provided with a top port and a bottom port, the top port is connected with the air side heat exchanger, and the bottom port is connected with the water side heat exchanger. The auxiliary liquid storage pipe section can assist the water side heat exchanger to store the refrigerant during heating operation, and more refrigerants can be circulated to the air side heat exchanger serving as a condenser during cooling operation, so that the optimal state of both cooling operation and heating operation can be met.
In some embodiments of the invention, the auxiliary reservoir section is located between the electronic expansion valve and the water side heat exchanger.
In some embodiments of the invention, in order to conveniently and reasonably determine the size of the auxiliary liquid storage pipe section and facilitate production and manufacturing, the method for determining the internal volume of the auxiliary liquid storage pipe section comprises the following steps:
respectively obtaining the total refrigerant quantity mc and mh of all components and tubing in the refrigeration operation and the heating operation under an ideal state;
respectively obtaining densities rho h and rho c of refrigerants in the auxiliary liquid storage pipe section in the refrigerating operation and the heating operation under the ideal state;
calculating the internal volume V of the auxiliary liquid storage pipe section: v = (mc-mh)/(ρ h- ρ c).
The pipe diameter and the length of the auxiliary liquid storage pipe section can be selected and determined according to the inner volume of the auxiliary liquid storage pipe section.
In some embodiments of the present invention, after the control module receives the shutdown signal, the control module further determines a current operation mode, closes the electronic expansion valve when the current operation mode is the heating mode, controls the compressor to keep on, and closes the entire machine when it is determined that the shutdown condition is satisfied.
In some embodiments of the present invention, the control module, after receiving the shutdown signal, further controls the compressor to operate at a set frequency, where the set frequency at least satisfies that a pressure difference between an exhaust port and an intake port of the compressor is not less than a pressure difference threshold.
In some embodiments of the invention, the set frequency is in the range of 30Hz to 60Hz, so that the high pressure side and the low pressure side maintain a proper pressure difference.
In some embodiments of the invention, the air-source heat pump system further comprises:
the fan is arranged on one side of the air side heat exchanger;
the control module further controls the fan to be kept on after receiving the stop signal, and the control method of the fan is as follows:
judging whether the current operation mode is a mute mode, when the current mode is the mute mode, the gear of the fan comprises a first gear and a second gear, and the wind speed of the first gear is greater than that of the second gear, and controlling the fan to operate according to the first gear;
when the current mode is the non-silent mode, the gears of the fan comprise a third gear and a fourth gear, the wind speed of the third gear is higher than that of the fourth gear, and the fan is controlled to operate according to the third gear.
In some embodiments of the present invention, the method for determining to shut down the whole machine includes that when any one of the following conditions is satisfied, the shutdown condition is satisfied, and the whole machine is shut down:
the air suction pressure reaches the lower limit value of the air suction pressure;
the exhaust pressure reaches an exhaust pressure upper limit value;
the exhaust temperature reaches the upper limit value of the exhaust temperature;
the high-pressure switch is switched off;
the low-pressure switch is switched off;
when the conditions are not met, the time upper limit value needs to be set, and when the duration of the shutdown control logic reaches the time upper limit value, shutdown is controlled, so that the system is prevented from being incapable of being shutdown for a long time.
In some embodiments of the invention, turning off the complete machine at least comprises turning off the compressor and the fan, and the complete machine enters a standby state.
Compared with the prior art, the technical scheme of the invention has the following technical effects:
according to the air source heat pump system, after the stop signal is received, the electronic expansion valve is controlled to be closed and the compressor is controlled to be kept open, and the refrigerant is stored on the high-pressure side under the combined action of the one-way valve and the closed electronic expansion valve, so that the oil return problem of the compressor can be solved. When the compressor is started next time, the low-pressure side refrigerant is less, the taken away compressor oil is less, and the technical problem that the compressor is lack of oil when the compressor is restarted can be effectively solved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic diagram of a prior art air source heat pump system;
FIG. 2 is a schematic diagram of an embodiment of an air-source heat pump system according to the present invention;
FIG. 3 is a timing diagram illustrating the control principles of an embodiment of the air-source heat pump system of the present invention;
FIG. 4 is yet another timing diagram illustrating the control principles of an embodiment of the air-source heat pump system of the present invention;
fig. 5 is a schematic diagram of a refrigerant cycle during heating operation in an embodiment of the air-source heat pump system according to the present invention;
fig. 6 is a schematic diagram of a refrigerant cycle during a cooling operation in an embodiment of the air-source heat pump system according to the present invention;
FIG. 7 is a schematic diagram of an auxiliary liquid storage section in an embodiment of an air-source heat pump system according to the present invention;
FIG. 8 is a flow chart illustrating the control principles of an embodiment of the air-source heat pump system of the present invention;
FIG. 9 is a flow chart of a method of determining the internal volume of an auxiliary liquid storage section in an embodiment of the air-source heat pump system of the present invention;
fig. 10 is a flow chart of yet another method for determining the internal volume of an auxiliary liquid storage section in an embodiment of an air-source heat pump system in accordance with the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
In the description of the present invention, it should be noted that the terms "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected unless otherwise explicitly stated or limited. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art. In the foregoing description of embodiments, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.
The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
Example one
< basic operation principle of air conditioner >
The air source heat pump system performs refrigerant circulation of the heat pump system by using the compressor, the condenser, the electronic expansion valve and the evaporator. The refrigerant cycle includes a series of processes involving compression, condensation, expansion, and evaporation, and supplies refrigerant to the conditioned side cycle.
The compressor compresses a refrigerant gas in a low-temperature and low-pressure state and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.
The electronic expansion valve expands the high-temperature and high-pressure liquid-phase refrigerant condensed in the condenser into a low-pressure liquid-phase refrigerant. The evaporator evaporates the refrigerant expanded in the expansion valve and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor.
In the air source heat pump system in this embodiment, heat in the air is absorbed to heat water (heating cycle), the heated water can be directly supplied to a user, or the circulating water is used to heat indoor air, and the water can be cooled by exchanging heat between latent heat of evaporation of a refrigerant and the water, so that the indoor air is cooled by the circulating water.
An outdoor unit of the air source heat pump system includes a compressor and an air-side heat exchanger, an indoor unit of the air source heat pump system includes a water-side heat exchanger, and an electronic expansion valve may be installed in the indoor unit or the outdoor unit.
The water side heat exchanger and the air side heat exchanger serve as a condenser or an evaporator. When the water-side heat exchanger is used as a condenser, the air-source heat pump system is used as a heater in a heating mode, and when the water-side heat exchanger is used as an evaporator, the air-source heat pump system is used as a cooler in a cooling mode.
The air source heat pump system of the present embodiment is particularly directed to a heat pump system without an accumulator.
As shown in fig. 2, an air-source heat pump system in the present embodiment includes a compressor 11, a four-way valve 12, a water-side heat exchanger 13 and an air-side heat exchanger 14, wherein the water-side heat exchanger 13 is connected to the air-side heat exchanger 14, and an air outlet 110 of the compressor 11, a return air inlet 111 of the compressor 11, the water-side heat exchanger 13 and the air-side heat exchanger 14 are respectively connected to four ports of the four-way valve 12 through connecting pipes.
As shown in fig. 6, in the refrigeration cycle, the refrigerant gas in a low-temperature and low-pressure state is compressed by the compressor 11 in a refrigerant flow direction indicated by a line arrow, and the compressed refrigerant gas is discharged. The discharged refrigerant gas flows into the air-side heat exchanger 14 as a condenser, which condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.
The refrigerant discharged from the air-side heat exchanger 14 enters the electronic expansion valve 17, and the electronic expansion valve 17 expands the liquid-phase refrigerant in a high-temperature and high-pressure state condensed in the condenser into a low-pressure liquid-phase refrigerant, and then enters the water-side heat exchanger serving as an evaporator. The evaporator evaporates the refrigerant expanded in the expansion valve, absorbs heat in water, and returns refrigerant gas in a low-temperature and low-pressure state to the compressor.
As shown in fig. 5, in the heating cycle, the compressor 11 compresses the refrigerant gas in a low-temperature and low-pressure state as indicated by a dotted arrow, and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into a water side heat exchanger as a condenser, the condenser condenses the compressed refrigerant into a liquid phase, and heat is released into water through the condensation process.
The refrigerant coming out of the water-side heat exchanger enters the electronic expansion valve 17, and the electronic expansion valve 17 expands the liquid-phase refrigerant in a high-temperature and high-pressure state condensed in the condenser into a low-pressure liquid-phase refrigerant, which then enters the air-side heat exchanger serving as an evaporator. The evaporator evaporates the refrigerant expanded in the expansion valve, absorbs heat in the air, and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor.
For refrigeration systems using refrigerants such as R32, the system refrigerant charge typically requires a minimum room area, and a smaller system refrigerant charge will more readily satisfy the on-site room area requirements. Therefore, for this type of air source heat pump product, the system is often designed without using an accumulator to reduce the refrigerant charge in the system. The refrigerant charge is less, also because the pressure differential problem at compressor both ends leads to the refrigerant to flow to the low pressure side from the high pressure side after shutting down, and when starting up again, the refrigerant of low pressure side gets into the compressor, takes away the compressor oil of compressor in a large number, leads to the compressor lack of oil problem.
In order to solve the above problem, in some embodiments of the present invention, as shown in fig. 2 and 8, the air source heat pump system further includes a check valve 15 connected between the exhaust port 110 of the compressor 11 and the four-way valve 12, and the compressor 11 is in one-way communication with the four-way valve 12.
An electronic expansion valve 17 is provided between the air-side heat exchanger and the water-side heat exchanger.
As shown in fig. 3, the control module is configured to: when the stop signal is received, the electronic expansion valve 17 is closed, and the compressor 11 is controlled to be kept open, and when the stop condition is judged to be satisfied, the whole machine is closed.
In this embodiment, the electronic expansion valve 17 is closed and the compressor is controlled to be kept open after the shutdown signal is received, because the electronic expansion valve 17 is closed and the compressor is kept open, at this time, the compressor can continuously discharge the refrigerant on the low-pressure side to the high-pressure side, and because the electronic expansion valve 17 is closed, the refrigerant on the high-pressure side cannot flow to the low-pressure side through the connecting pipeline, and when the shutdown condition is met, the compressor is shutdown, because of the existence of the check valve 15, the refrigerant on the high-pressure side cannot flow to the low-pressure side through the compressor, and therefore, the refrigerant can be stopped on the high-pressure side. After the compressor is restarted, because the refrigerant of the low-pressure side is few, a large amount of refrigerants can not enter the compressor in a short time, and then a large amount of compressor oil of the compressor can not be taken away, and the problem of oil shortage of the compressor is avoided. Along with the circulation of the refrigerant, the refrigerant on the high-pressure side flows back to the low-pressure side through the electronic expansion valve 17, and then enters the compressor, so that the dynamic balance of the refrigerant is formed.
After the process is continued for a period of time, the whole machine is closed when the shutdown condition is judged to be met.
For a heat pump system using refrigerant such as R32, because the difference between the internal volumes of the two heat exchangers is large, the amount of refrigerant filled without using a liquid reservoir is small, and at the same time, a new problem is caused, that is, the amount of refrigerant filled cannot meet the problem that both the cooling operation and the heating operation can be operated in an optimal state, therefore, in some embodiments of the present invention, as shown in fig. 7, the air source heat pump system further includes an auxiliary liquid storage pipe segment 16 connected between the water-side heat exchanger and the air-side heat exchanger, the auxiliary liquid storage pipe segment 16 is arranged in a vertical direction and has a top port 161 and a bottom port 162, the top port 161 is connected with the air-side heat exchanger, and the bottom port 162 is connected with the water-side heat exchanger.
As shown in fig. 2 and 7, when the heat pump system is operated in heating mode, the refrigerant enters the auxiliary liquid storage pipe section 16 from the bottom port 162 and flows out from the top port 161, and the auxiliary liquid storage pipe section 16 needs to be filled with the supercooled high-pressure refrigerant coming out of the water side heat exchanger and then enters the electronic expansion valve 17. The auxiliary water side heat exchanger can play a role in storing the refrigerant, namely expanding the capacity of the water side heat exchanger, so that more refrigerants can be circulated to the water side serving as a condenser, and further the refrigerant can run in the best state in the heating running mode.
During refrigerating operation, the refrigerant enters the auxiliary liquid storage pipe section 16 from the top port 161 and flows out from the bottom port 162, the state of the refrigerant entering the liquid storage device is a low-pressure two-phase state, and the refrigerant entering the liquid storage device is stored in the liquid storage device in an upward-inlet-downward-outlet mode, so that the amount of the refrigerant stored in the liquid storage device is small, more refrigerants can be circulated to the air side heat exchanger serving as a condenser, and the refrigerant can be operated in an optimal state during a refrigerating operation mode. In addition, in the cooling and heating operation, the density of the high-pressure refrigerant is high, but the high-pressure refrigerant in the cooling mode is in the air side heat exchanger, the high-pressure refrigerant in the heating mode is in the water side heat exchanger, the volume difference between the high-pressure refrigerant in the air side heat exchanger and the high-pressure refrigerant in the heating mode is large, the liquid storage device stores a small amount of refrigerant in the cooling mode, and stores a large amount of refrigerant in the heating mode, so that the cooling and heating refrigerant quantity can be balanced in such a mode.
This scheme especially carries out the refrigerant balance to the heat pump system who does not have the reservoir, and no matter refrigeration mode still heats the mode homoenergetic and obviously promotes the operation effect.
In some embodiments of the present invention, the air-side heat exchanger may be implemented by, but not limited to, a finned tube heat exchanger, and the water-side heat exchanger may be implemented by, but not limited to, a plate heat exchanger.
In some embodiments of the present invention, after the control module receives the shutdown signal, the control module further determines a current operation mode, closes the electronic expansion valve when the current operation mode is the heating mode, controls the compressor to be kept open, and closes the entire machine when it is determined that the shutdown condition is satisfied.
In some embodiments of the invention, the auxiliary reservoir section is located between the electronic expansion valve 17 and the water side heat exchanger. When the shutdown control logic is executed, the check valve prevents the refrigerant from leaking to the low-pressure side from the high-pressure side, the auxiliary liquid storage pipe section can be used for expanding the capacity of the water-side heat exchanger, and more refrigerants are stored in the high-pressure side. When the heating operation is stopped, the electronic expansion valve 17 is closed first, the compressor and the fan continue to operate, the refrigerant is still discharged from the low-pressure side to the high-pressure side, the refrigerant stored in the high-pressure side (the water side heat exchanger and the auxiliary liquid storage pipe section) is increased, and the refrigerant stored in the low-pressure side (the air side heat exchanger) is reduced. When the compressor is normally started next time, the amount of refrigerant entering the compressor is reduced, and the amount of oil carried away is reduced, so that the operation reliability of the compressor at the starting stage is effectively improved.
For a system without a liquid storage device, the online scheme needs to calculate the most appropriate size of an auxiliary liquid storage pipe section and the refrigerant adding amount. On the premise that the pressure drop of the auxiliary liquid storage pipe section is allowed, the corresponding pipe diameter is thicker if the auxiliary liquid storage pipe section is shorter, and the pipe diameter can be thinner if the auxiliary liquid storage pipe section is longer, so that the refrigerant quantity stored in the auxiliary liquid storage pipe section is ensured within the allowable range without influencing the reliability. Meanwhile, the mode can increase the filling-free online piping, and is convenient for field installation.
In some embodiments of the present invention, the method for determining the internal volume of the auxiliary reservoir section comprises:
respectively obtaining total refrigerant quantities mc and mh of all components and tubing in the refrigerating operation and the heating operation under an ideal state;
respectively acquiring densities rho h and rho c of refrigerants in the auxiliary liquid storage pipe section during refrigeration operation and heating operation in an ideal state;
calculating the internal volume V of the auxiliary liquid storage pipe section: v = (mc-mh)/(ρ h- ρ c).
The internal volume V of the auxiliary liquid storage pipe section is selected to be proper in diameter and length, so that the internal volume of the auxiliary liquid storage pipe section is equal to V.
As shown in fig. 9, in some embodiments of the present invention, before obtaining the cooling operation and the heating operation in the ideal state, the method further includes a step of determining a theoretical cycle, and a step of selecting a type of the compressor, the finned tube heat exchanger, the electronic expansion valve 17 and the plate heat exchanger.
There are various ways to obtain the total refrigerant quantities mc and mh of all components and piping during the cooling operation and the heating operation in an ideal state, and the refrigerant quantity can be determined by adopting a simulation calculation mode or an experiment mode.
The method for determining the refrigerant quantity by adopting simulation calculation comprises the following steps: and calculating the total refrigerant quantity mc of all components and the piping during the standard refrigerating operation and the total refrigerant quantity mh of all components and the piping during the standard heating operation.
As shown in fig. 10, the method for determining the amount of refrigerant by calculation using a background test includes: and (3) testing the standard refrigerating working condition and the standard heating working condition by using a prototype without a liquid accumulator, and adjusting the refrigerant quantity to reach the optimal COP of the required capacity to obtain mc and mh respectively.
After obtaining the internal volume V of the auxiliary liquid storage pipe section, the method further includes calculating the total refrigerant charge M = mc + ρ cV, or M = mh + ρ hV.
After the total refrigerant charge M is calculated, whether the standard refrigeration capacity energy efficiency and the standard heating capacity energy efficiency reach the standard after test is further included, and when the standard refrigeration capacity energy efficiency and the standard heating capacity energy efficiency reach the standard, tests of other working conditions are carried out, and reliability is verified. And when the standard is not met, the model of the compressor, the finned tube heat exchanger, the electronic expansion valve 17 and the plate heat exchanger is selected again after the theoretical cycle is corrected.
In some embodiments of the present invention, after the control module receives the shutdown signal, the control module further controls the compressor to operate at a fixed frequency according to a set frequency, where the set frequency at least satisfies that a differential pressure between an exhaust port and an intake port of the compressor is not less than a differential pressure threshold.
In some embodiments of the present invention, the frequency is set to a value in the range of 30Hz to 60Hz, so that the high pressure side and the low pressure side maintain a suitable pressure difference.
In some embodiments of the invention, a fan is disposed on one side of the air-side heat exchanger, and the control module further controls the fan to be kept on after receiving the shutdown signal.
In some embodiments of the present invention, the fan is controlled to remain on at a non-low speed, i.e., a relatively high speed, to promote heat transfer.
In some embodiments of the present invention, the air-source heat pump system further comprises a normal mode and a silent mode, and the normal mode and the silent mode respectively have a fan control gear corresponding to each other.
During the silent mode, the gear of fan includes first gear and second gear, and the wind speed of first gear is greater than the second gear, is not limited to above-mentioned two gears under this mode of course, also can set up more gears and further refine control range.
During the non-silent mode, the gear of fan includes third gear and fourth gear, and the wind speed of third gear is greater than the fourth gear, is not limited to above-mentioned two gears under this mode of course, also can set up more gears and further refine control range.
The gear of the fan in the silent mode and the non-silent mode is independently set, under a general condition, the wind speed of the first gear is smaller than that of the third gear, and the noise generated by the fan is reduced in a mode of limiting the rotating speed of the fan.
In some embodiments of the present invention, a control method of the fan is:
judging whether the current operation mode is a mute mode, and controlling the fan to operate according to a first gear when the current mode is the mute mode;
and when the current mode is the non-mute mode, controlling the fan to operate according to a third gear.
For the heat pump system without the mute mode, the control is carried out according to the control logic of the non-mute mode during the control.
In some embodiments of the present invention, the method for determining to shut down the whole machine includes that when any one of the following conditions is satisfied, the shutdown condition is satisfied, and the whole machine is shut down:
the air suction pressure reaches the lower limit value of the air suction pressure;
the exhaust pressure reaches an exhaust pressure upper limit value;
the two steps are respectively used for protecting the air suction pressure and the exhaust pressure, so that the safety of the system operation pressure is guaranteed.
The exhaust temperature reaches the upper limit value of the exhaust temperature so as to protect the system at high temperature.
The high-pressure switch is switched off;
the low-pressure switch is turned off;
when the conditions are not met, the time upper limit value needs to be set, when the electronic expansion valve is closed and the duration time for controlling the compressor to be kept open reaches the time upper limit value, the shutdown is controlled, and the system is prevented from being incapable of being shutdown for a long time after receiving a shutdown signal.
In some embodiments of the present invention, as shown in fig. 4, turning off the complete machine at least includes turning off the compressor and the fan, and the complete machine enters a standby state.
After the compressor is shut down, the high pressure side and the low pressure side cannot be communicated, so that the high pressure side and the low pressure side are always in a pressure difference state after the compressor is shut down, and the refrigerant is stored to the high pressure side.
In the foregoing description of embodiments, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are also within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. An air-source heat pump system, comprising:
the compressor comprises a gas outlet of the compressor and a gas return port of the compressor;
a water side heat exchanger;
the air side heat exchanger is connected with the water side heat exchanger;
the four ports of the four-way valve are respectively connected with the exhaust port of the compressor, the return air port of the compressor, the water side heat exchanger and the air side heat exchanger through connecting pipes;
the one-way valve is connected between an exhaust port of the compressor and the four-way valve, and the compressor is in one-way conduction with the four-way valve;
an electronic expansion valve disposed between the air-side heat exchanger and the water-side heat exchanger;
a control module configured to:
and after a stop signal is received, closing the electronic expansion valve, controlling the compressor to keep open, and closing the whole machine when the stop condition is met.
2. The air-source heat pump system of claim 1, further comprising:
and the auxiliary liquid storage pipe section is connected between the water side heat exchanger and the air side heat exchanger, is arranged along the vertical direction and is provided with a top port and a bottom port, the top port is connected with the air side heat exchanger, and the bottom port is connected with the water side heat exchanger.
3. The air-source heat pump system of claim 2, wherein the auxiliary reservoir section is located between the electronic expansion valve and the water-side heat exchanger.
4. The air-source heat pump system of claim 2, wherein the internal volume of the auxiliary reservoir segment is determined by:
respectively obtaining the total refrigerant quantity mc and mh of all components and tubing in the refrigeration operation and the heating operation under an ideal state;
respectively acquiring densities rho h and rho c of refrigerants in the auxiliary liquid storage pipe section during refrigeration operation and heating operation in an ideal state;
calculating the internal volume V of the auxiliary liquid storage pipe section: v = (mc-mh)/(ρ h- ρ c).
5. The air-source heat pump system according to claim 1, wherein the control module, after receiving the shutdown signal, further comprises determining a current operation mode, closing the electronic expansion valve when the current operation mode is the heating mode, and controlling the compressor to remain on, and closing the entire machine when it is determined that the shutdown condition is satisfied.
6. The air-source heat pump system according to any one of claims 1-5, wherein the control module, upon receiving a shutdown signal, further comprises controlling the compressor to operate at a set frequency that at least satisfies that a pressure differential between an exhaust port and an intake port of the compressor is not less than a pressure differential threshold.
7. The air-source heat pump system of claim 6, wherein the set frequency is in the range of 30Hz to 60 Hz.
8. The air-source heat pump system according to any one of claims 1-5, further comprising:
the fan is arranged on one side of the air side heat exchanger;
the control module also controls the fan to be kept on after receiving the shutdown signal;
the control method of the fan comprises the following steps:
judging whether the current operation mode is a mute mode, when the current mode is the mute mode, the gear of the fan comprises a first gear and a second gear, and the wind speed of the first gear is greater than that of the second gear, and controlling the fan to operate according to the first gear;
when the current mode is the non-silent mode, the gears of the fan comprise a third gear and a fourth gear, the wind speed of the third gear is higher than that of the fourth gear, and the fan is controlled to operate according to the third gear.
9. The air-source heat pump system according to any one of claims 1 to 5, wherein the judging method for shutting down the whole machine comprises the following steps of shutting down the whole machine when any one of the following conditions is met, and establishing a shutdown condition:
the suction pressure reaches the lower limit value of the suction pressure;
the exhaust pressure reaches an exhaust pressure upper limit value;
the exhaust temperature reaches the upper limit value of the exhaust temperature;
the high-pressure switch is switched off;
the low-pressure switch is switched off;
the duration of the shutdown control logic reaches an upper time limit.
10. The air-source heat pump system according to any one of claims 1-5, wherein shutting down the complete machine comprises shutting down at least the compressor and the fan, the complete machine entering a standby state.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210642290.4A CN114935223A (en) | 2022-06-08 | 2022-06-08 | Air source heat pump system |
| PCT/CN2022/136619 WO2023103968A1 (en) | 2021-12-07 | 2022-12-05 | Air source heat pump system |
| CN202280061663.7A CN117940706A (en) | 2022-06-08 | 2022-12-05 | Air source heat pump system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210642290.4A CN114935223A (en) | 2022-06-08 | 2022-06-08 | Air source heat pump system |
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| CN114935223A true CN114935223A (en) | 2022-08-23 |
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| CN202210642290.4A Pending CN114935223A (en) | 2021-12-07 | 2022-06-08 | Air source heat pump system |
| CN202280061663.7A Pending CN117940706A (en) | 2022-06-08 | 2022-12-05 | Air source heat pump system |
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|---|---|---|---|---|
| WO2023103968A1 (en) * | 2021-12-07 | 2023-06-15 | 青岛海信日立空调***有限公司 | Air source heat pump system |
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| CN117940706A (en) | 2024-04-26 |
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Application publication date: 20220823 |