CN114992889B - Cascade heat pump system and control method thereof - Google Patents
Cascade heat pump system and control method thereof Download PDFInfo
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- CN114992889B CN114992889B CN202210579892.XA CN202210579892A CN114992889B CN 114992889 B CN114992889 B CN 114992889B CN 202210579892 A CN202210579892 A CN 202210579892A CN 114992889 B CN114992889 B CN 114992889B
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- refrigerant circulation
- pressure refrigerant
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- 238000000034 method Methods 0.000 title claims abstract description 39
- 239000003507 refrigerant Substances 0.000 claims abstract description 276
- 238000001704 evaporation Methods 0.000 claims description 38
- 230000008020 evaporation Effects 0.000 claims description 29
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 19
- 229910052731 fluorine Inorganic materials 0.000 claims description 19
- 239000011737 fluorine Substances 0.000 claims description 19
- 230000007613 environmental effect Effects 0.000 abstract description 7
- 238000005265 energy consumption Methods 0.000 abstract description 6
- 238000000926 separation method Methods 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 5
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- LVGUZGTVOIAKKC-UHFFFAOYSA-N 1,1,1,2-tetrafluoroethane Chemical compound FCC(F)(F)F LVGUZGTVOIAKKC-UHFFFAOYSA-N 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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
- F25B7/00—Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- 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
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
- F25B41/40—Fluid line arrangements
-
- 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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- 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)
- Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
Abstract
The invention relates to the technical field of cascade heat pumps, in particular to a cascade heat pump system and a control method thereof, and aims to solve the problem that the existing cascade heat pump system is easily influenced by ambient temperature and has a narrow operation range. The cascade heat pump system comprises a high-pressure refrigerant circulation loop, a first low-pressure refrigerant circulation loop, a second low-pressure refrigerant circulation loop and a bypass branch, wherein the first low-pressure refrigerant circulation loop, the second low-pressure refrigerant circulation loop and the bypass branch can be selectively operated; based on the above, the cascade heat pump system controls the operation states of the first low-pressure refrigerant circulation loop and the second low-pressure refrigerant circulation loop according to the acquired environmental temperature, so that the operation energy consumption of the cascade heat pump system is effectively reduced; and the operation state of the bypass branch is controlled according to the acquired operation parameters of the high-pressure refrigerant circulation loop, so that the high-pressure refrigerant circulation loop can be effectively ensured to always operate by controlling the on-off state of the bypass branch, and the operation range of the cascade heat pump system is effectively enlarged.
Description
Technical Field
The invention relates to the technical field of cascade heat pumps, and particularly provides a cascade heat pump system and a control method thereof.
Background
Along with the popularization of energy-saving and emission-reducing policies, more and more application occasions of high-temperature heating treatment by using a high-temperature heat pump system in industries such as food processing, spinning, chemical industry and the like are available. Industrial heating demands are vigorous, and the application demands on high-temperature heat pump systems are also increasing. First, the final heating temperature of high temperature heat pump systems is typically greater than 70 ℃ and even greater than 90 ℃. Second, the heating system is used at an ambient temperature ranging from-30 ℃ to 35 ℃ and even spans much larger, and needs to provide hot water or hot air at high temperature in both winter and summer.
The high temperature hot water used in industry has high temperature, which causes that the common heat pump system cannot meet the practical heating use requirement, and the technology for using the cascade heat pump system to provide high temperature hot water is very mature. The cascade heat pump system generally comprises a high-pressure refrigerant circulation loop and a low-pressure refrigerant circulation loop, and the high-pressure refrigerant circulation loop and the low-pressure refrigerant circulation loop exchange heat through a shared intermediate heat exchanger so as to achieve the purpose of providing high-temperature hot water. However, the existing cascade heat pump system is limited by the ambient temperature, and cannot be operated when the ambient temperature is higher or lower, that is, the operating range of the existing cascade heat pump system is narrow, so that hot water cannot be provided for users all the time, and inconvenience is brought to the users.
Accordingly, there is a need in the art for a new cascade heat pump system and control method thereof to solve the above-mentioned technical problems.
Disclosure of Invention
The invention aims to solve the technical problems, namely, the problem that the existing cascade heat pump system is easily influenced by the ambient temperature and has a narrow operating range.
In a first aspect, the present invention provides a control method of an overlapping heat pump system, the overlapping heat pump system includes a high-pressure refrigerant circulation loop, a first low-pressure refrigerant circulation loop, a second low-pressure refrigerant circulation loop and a bypass branch,
The high-pressure refrigerant circulation loop is provided with a first compressor, a first heat exchanger, a first throttling component and an intermediate heat exchanger, the first low-pressure refrigerant circulation loop is provided with a second compressor, the intermediate heat exchanger, a second throttling component and a second heat exchanger, the second low-pressure refrigerant circulation loop is provided with a fluorine pump, the second heat exchanger and the intermediate heat exchanger, two ends of the fluorine pump are connected with the first low-pressure refrigerant circulation loop, two ends of the second compressor are connected with the second low-pressure refrigerant circulation loop, the first low-pressure refrigerant circulation loop and the second low-pressure refrigerant circulation loop are arranged to be capable of selectively exchanging heat with the high-pressure refrigerant circulation loop through the intermediate heat exchanger,
The first end of the bypass branch is connected between the connection point of the fluorine pump and the first low-pressure refrigerant circulation loop and the second heat exchanger, the second end of the bypass branch is connected between the second compressor and the intermediate heat exchanger, a control valve is arranged on the bypass branch and can control the on-off state of the bypass branch,
The control method comprises the following steps:
Acquiring the ambient temperature of the cascade heat pump system;
controlling the operation states of the first low-pressure refrigerant circulation loop and the second low-pressure refrigerant circulation loop according to the ambient temperature;
Acquiring operation parameters of the high-pressure refrigerant circulation loop;
and controlling the operation state of the bypass branch according to the operation parameters of the high-pressure refrigerant circulation loop.
In a preferred embodiment of the above control method, the step of controlling the operation states of the first low-pressure refrigerant circulation circuit and the second low-pressure refrigerant circulation circuit according to the ambient temperature includes:
And if the ambient temperature is greater than or equal to the preset ambient temperature, controlling the first low-pressure refrigerant circulation loop not to operate and controlling the second low-pressure refrigerant circulation loop to operate.
In a preferred embodiment of the above control method, the step of controlling the operation states of the first low-pressure refrigerant circulation circuit and the second low-pressure refrigerant circulation circuit according to the ambient temperature further includes:
And if the ambient temperature is smaller than the preset ambient temperature, controlling the first low-pressure refrigerant circulation loop to operate, and controlling the second low-pressure refrigerant circulation loop not to operate.
In the preferred technical scheme of the control method, the step of acquiring the operation parameter of the high-pressure refrigerant circulation loop specifically includes:
acquiring the current refrigerant evaporation temperature and the maximum refrigerant evaporation temperature of the intermediate heat exchanger;
The step of controlling the operation state of the bypass branch according to the operation parameter of the high-pressure refrigerant circulation loop specifically includes:
and controlling the operation state of the bypass branch according to the current refrigerant evaporation temperature and the maximum refrigerant evaporation temperature.
In the above preferred technical solution of the control method, the step of controlling the operation state of the bypass branch according to the current refrigerant evaporation temperature and the maximum refrigerant evaporation temperature specifically includes:
Calculating the difference between the maximum refrigerant evaporation temperature and the current refrigerant evaporation temperature, and recording the difference as a first difference;
If the first difference value is smaller than a first preset difference value, controlling the bypass branch to operate; and/or
And if the first difference value is greater than or equal to the first preset difference value, controlling the bypass branch not to operate.
In the preferred technical scheme of the control method, the step of acquiring the operation parameter of the high-pressure refrigerant circulation loop specifically includes:
Acquiring the current suction pressure and the maximum suction pressure of the first compressor;
The step of controlling the operation state of the bypass branch according to the operation parameter of the high-pressure refrigerant circulation loop specifically includes:
and controlling the operation state of the bypass branch according to the current suction pressure and the maximum suction pressure.
In a preferred technical solution of the above control method, the step of controlling the operation state of the bypass branch according to the current suction pressure and the maximum suction pressure specifically includes:
calculating the difference between the maximum inhalation pressure and the current inhalation pressure, and recording the difference as a second difference;
if the second difference value is smaller than a second preset difference value, controlling the bypass branch to operate; and/or
And if the second difference value is greater than or equal to the second preset difference value, controlling the bypass branch not to operate.
In a preferred technical solution of the above control method, in a case where the first low-pressure refrigerant circulation circuit is operated and the bypass branch is not operated, the control method further includes:
acquiring the temperature of the refrigerant at the outlet of the second heat exchanger;
and further controlling the operation state of the bypass branch according to the temperature of the refrigerant at the outlet of the second heat exchanger.
In the above preferred technical solution of the control method, the step of "further controlling the operation state of the bypass branch according to the temperature of the refrigerant at the outlet of the second heat exchanger" specifically includes:
If the temperature of the refrigerant at the outlet of the second heat exchanger is less than or equal to the preset refrigerant temperature, controlling the bypass branch to operate; and/or
And if the temperature of the refrigerant at the outlet of the second heat exchanger is higher than the preset refrigerant temperature, controlling the bypass branch not to operate.
In another aspect, the present invention also provides a cascade heat pump system comprising a controller capable of executing the control method described in any one of the above preferred embodiments.
Under the condition of adopting the technical scheme, the cascade heat pump system can control the operation states of the first low-pressure refrigerant circulation loop and the second low-pressure refrigerant circulation loop according to the acquired environmental temperature so as to effectively reduce the operation energy consumption of the cascade heat pump system; the operation state of the bypass branch can be controlled according to the obtained operation parameters of the high-pressure refrigerant circulation loop, so that the high-pressure refrigerant circulation loop can be effectively ensured to always operate by controlling the on-off state of the bypass branch, the operation range of the cascade heat pump system is effectively enlarged, and the use requirement of a user is met.
Drawings
Preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:
FIG. 1 is a schematic view of the overall structure of the cascade heat pump system of the present invention;
FIG. 2 is a flow chart of the main steps of the control method of the present invention;
FIG. 3 is a flowchart showing the specific steps of a first preferred embodiment of the control method of the present invention;
FIG. 4 is a flowchart showing the specific steps of a second preferred embodiment of the control method of the present invention;
reference numerals:
1. a high-pressure refrigerant circulation circuit; 11. a first compressor; 12. a first heat exchanger; 13. a first throttle member; 14. an intermediate heat exchanger;
2. A first low-pressure refrigerant circulation circuit; 21. a second compressor; 22. a second throttle member; 23. a second heat exchanger; 24. a first one-way valve; 25. a second one-way valve;
3. A second low-pressure refrigerant circulation circuit; 31. a fluorine pump; 32. a third one-way valve;
4. a bypass branch; 41. a control valve;
5. a heat exchange waterway.
Detailed Description
Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are merely for explaining the technical principles of the present invention, and are not intended to limit the scope of the present invention. Those skilled in the art can adapt it as desired to suit a particular application. For example, the cascade heat pump system described in the present invention may be a household cascade heat pump system, or an industrial cascade heat pump system, which is not limited, and a person skilled in the art may set the application of the cascade heat pump system according to the actual use requirement. Such changes in the application do not depart from the basic principles of the invention and are intended to be within the scope of the invention.
It should be noted that in the description of the preferred embodiments, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying any relative importance unless expressly specified or limited otherwise. Furthermore, the terms "coupled," "connected," and "connected" are used in a broad sense, and may be mechanically coupled, electrically coupled, directly coupled, indirectly coupled via an intervening medium, or internally coupled, and thus should not be construed as limiting the invention. The specific meaning of the above terms in the present invention can be understood by those skilled in the art according to the specific circumstances.
Furthermore, it should be noted that in the description of the present application, although the respective steps of the control method of the present application are described in a specific order in the present application, these orders are not limitative, but a person skilled in the art may perform the steps in a different order without departing from the basic principle of the present application.
Based on the problem that the existing cascade heat pump system is easily influenced by the ambient temperature and has a narrow operation range, the invention provides a novel cascade heat pump system and a control method thereof, and aims to expand the operation range of the cascade heat pump system by selectively operating a first low-pressure refrigerant circulation loop, a second low-pressure refrigerant circulation loop and a bypass branch, thereby effectively ensuring that a high-pressure refrigerant circulation loop is always operated so as to meet the use requirement of a user.
Referring first to fig. 1, fig. 1 is a schematic diagram of the overall structure of the cascade heat pump system of the present invention. As shown in fig. 1, the cascade heat pump system of the present invention includes a high-pressure refrigerant circulation circuit 1, a first low-pressure refrigerant circulation circuit 2, and a second low-pressure refrigerant circulation circuit 3, wherein the high-pressure refrigerant circulation circuit 1 is provided with a first compressor 11, a first heat exchanger 12, a first throttle member 13, and an intermediate heat exchanger 14, the first low-pressure refrigerant circulation circuit 2 is provided with a second compressor 21, an intermediate heat exchanger 14, a second throttle member 22, and a second heat exchanger 23, the second low-pressure refrigerant circulation circuit 3 is provided with a fluorine pump 31, a second heat exchanger 23, and an intermediate heat exchanger 14, and the first low-pressure refrigerant circulation circuit 2 and the second low-pressure refrigerant circulation circuit 3 are provided so as to be able to exchange heat with the high-pressure refrigerant circulation circuit 1 selectively through the intermediate heat exchanger 14.
Based on the above structure, the cascade heat pump system of the invention effectively ensures that the high-pressure refrigerant circulation loop 1 always operates by selectively operating the first low-pressure refrigerant circulation loop 2 and the second low-pressure refrigerant circulation loop 3, thereby effectively expanding the operating range of the cascade heat pump system, effectively reducing the operating energy consumption of the cascade heat pump system and improving the user experience.
It should be noted that, the specific types of the refrigerants flowing in the high-pressure refrigerant circulation circuit 1, the first low-pressure refrigerant circulation circuit 2 and the second low-pressure refrigerant circulation circuit 3 are not limited in the present invention, and can be set by those skilled in the art according to practical situations. As a specific embodiment, the refrigerant in the high-pressure refrigerant circulation circuit 1 is the refrigerant R134a, and the refrigerant in the first low-pressure refrigerant circulation circuit 2 and the second low-pressure refrigerant circulation circuit 3 is the refrigerant R410A.
In addition, it should be noted that the specific structure of the intermediate heat exchanger 14 is not limited in the present invention, and it may be a shell-and-tube heat exchanger or a plate heat exchanger, and those skilled in the art may set the heat exchanger according to the actual situation. In this embodiment, the intermediate heat exchanger 14 is preferably a plate heat exchanger, so as to effectively improve the heat exchange efficiency of the refrigerant in the first low-pressure refrigerant circulation circuit 2 and the second low-pressure refrigerant circulation circuit 3 in the intermediate heat exchanger 14.
Preferably, the first low pressure refrigerant circulation circuit 2 and the second low pressure refrigerant circulation circuit 3 are connected to simplify the structure of the cascade heat pump system. As shown in fig. 1, the two ends of the fluorine pump 31 are connected to the first low-pressure refrigerant circulation circuit 2, and the two ends of the second compressor 21 are connected to the second low-pressure refrigerant circulation circuit 3; specifically, a first end of the fluorine pump 31 is connected between the second throttling member 22 and the second heat exchanger 23, and a second end of the fluorine pump 31 is connected between the intermediate heat exchanger 14 and the second throttling member 22. The intermediate heat exchanger 14 comprises a first heat exchange channel and a second heat exchange channel, and the second heat exchanger 23 comprises a first heat exchange tube, wherein the refrigerant in the high-pressure refrigerant circulation loop 1 flows through the first heat exchange channel, and the refrigerant in the first low-pressure refrigerant circulation loop 2 and the second low-pressure refrigerant circulation loop 3 flows through the second heat exchange channel and the first heat exchange tube, so as to achieve the purpose of heat exchange.
It should be noted that the present invention does not impose any limitation on the specific structures and specific models of the first compressor 11, the second compressor 21, the fluorine pump 31, the first throttling member 13, the second throttling member 22, the first heat exchanger 12 and the second heat exchanger 23; the first compressor 11 and the second compressor 21 may be variable frequency compressors or fixed frequency compressors, and preferably, the first compressor 11 and the second compressor 21 are variable frequency compressors so as to control the operation state of the cascade heat pump system; the fluorine pump 31 can be a fluorine-lined centrifugal pump, a fluorine-lined magnetic pump or a fluorine-lined self-priming pump; the first throttling member 13 and the second throttling member 22 may be electronic expansion valves, capillaries, or thermal expansion valves; the first heat exchanger 12 and the second heat exchanger 23 may be plate heat exchangers or shell and tube heat exchangers, which are not limitative, and may be set by those skilled in the art according to practical situations.
In addition, it should be noted that the heat source of the second heat exchanger 23 is not limited in the present invention, and may be an air source or a ground source, which is not limited, so long as the heat exchange purpose of the second heat exchanger 23 can be achieved, and those skilled in the art can set the heat exchange device according to the actual situation. In the preferred embodiment, the heat source of the second heat exchanger 23 is an air source, so as to further reduce the energy consumption of the cascade heat pump system and improve the operation energy efficiency; specifically, the cascade heat pump system further includes a heat exchange fan (not shown in the drawing) disposed near the second heat exchanger 23 to enhance the heat exchange effect of the air and the refrigerant in the second heat exchanger 23.
Further, in the preferred embodiment, the cascade heat pump system further includes a bypass branch 4, a first end of the bypass branch 4 is connected between the connection point of the fluorine pump 31 and the first low-pressure refrigerant circulation loop 2 and the second heat exchanger 23, a second end of the bypass branch 4 is connected between the second compressor 21 and the intermediate heat exchanger 14, and the operation range of the cascade heat pump system can be further enlarged by the arrangement of the bypass branch 4, so that the high-pressure refrigerant circulation loop 1 can be effectively ensured to always operate, and the actual requirement of a user is met. It should be noted that the specific connection position of the first end and the second end of the bypass branch 4 is not limited in the present invention, and may be set by those skilled in the art according to the actual situation.
Preferably, the bypass branch 4 is provided with a control valve 41, and the control valve 41 is configured to control the on-off state and the refrigerant flowing direction of the bypass branch 4. It should be noted that the specific structure and type of the control valve 41 are not limited in the present invention, and those skilled in the art can set the control valve according to the actual situation.
As a specific embodiment, the control valve 41 is a reversing control valve configured to enable, by reversing control, both the refrigerant flowing in the bypass branch 4 to flow from the second end of the bypass branch 4 to the first end of the bypass branch 4 and the refrigerant flowing in the bypass branch 4 to flow from the first end of the bypass branch 4 to the second end of the bypass branch 4.
Specifically, the reversing control valve is configured to enable the refrigerant flowing in the first low-pressure refrigerant circulation circuit 2 to flow from the second end of the bypass branch 4 to the first end of the bypass branch 4 when the first low-pressure refrigerant circulation circuit 2 is in operation and the second low-pressure refrigerant circulation circuit 3 is not in operation. After being discharged from the exhaust port of the second compressor 21, a part of the refrigerant in the first low-pressure refrigerant circulation loop 2 enters the bypass branch 4 through the second end of the bypass branch 4, and the other part enters the intermediate heat exchanger 14 to exchange heat with the refrigerant in the high-pressure refrigerant circulation loop 1, then enters the second heat exchanger 23 after being throttled and depressurized by the second throttling member 22 and then being converged with the refrigerant flowing out of the first end of the bypass branch 4, and then returns to the second compressor 21 through the air inlet of the second compressor 21.
The reversing control valve is further configured to enable the refrigerant flowing in the second low-pressure refrigerant circulation circuit 3 to flow from the first end of the bypass branch 4 to the second end of the bypass branch 4 when the first low-pressure refrigerant circulation circuit 2 is not operating and the second low-pressure refrigerant circulation circuit 3 is operating. Specifically, a part of the refrigerant circulated by the fluorine pump 31 enters the bypass branch 4 through the first end of the bypass branch 4, and the other part enters the second heat exchanger 23 to absorb heat by evaporation and then is converged with the refrigerant flowing out of the second end of the bypass branch 4, and then enters the intermediate heat exchanger 14 to exchange heat with the refrigerant in the high-pressure refrigerant circulation loop 1, and the refrigerant after heat exchange enters the fluorine pump 31 again to participate in circulation.
In addition, when the first low-pressure refrigerant circulation circuit 2 and the second low-pressure refrigerant circulation circuit 3 are both operated, a person skilled in the art can control the direction of the reversing control valve to further control the flow direction of the refrigerant in the bypass branch 4, which is not limited in the present invention.
Preferably, the first low pressure refrigerant circulation circuit 2 is further provided with a first check valve 24, the first check valve 24 is disposed between the second compressor 21 and the second end of the bypass branch 4, the first check valve 24 is configured to allow the refrigerant to flow from one side of the exhaust port of the second compressor 21 to the second end of the bypass branch 4 and one side of the intermediate heat exchanger 14, and the first check valve 24 can effectively ensure that the refrigerant flowing out of the second end of the bypass branch 4 does not flow back into the second compressor 21 when the first low pressure refrigerant circulation circuit 2 is not operated and the second low pressure refrigerant circulation circuit 3 is operated.
Further, the first low pressure refrigerant circulation circuit 2 is further provided with a second one-way valve 25, the second one-way valve 25 is disposed between the first end of the bypass branch circuit 4 and the connection point between the fluorine pump 31 and the first low pressure refrigerant circulation circuit 2, the second one-way valve 25 is disposed to only allow the refrigerant to flow from one side of the connection point between the fluorine pump 31 and the first low pressure refrigerant circulation circuit 2 to the first end of the bypass branch circuit 4 and one side of the second heat exchanger 23, and the second one-way valve 25 can effectively ensure that the refrigerant flowing out of the first end of the bypass branch circuit 4 will not flow back into the fluorine pump 31 when the first low pressure refrigerant circulation circuit 2 is operated and the second low pressure refrigerant circulation circuit 3 is not operated.
It is further preferred that a third check valve 32 is further provided on the second low pressure refrigerant circulation circuit 3, the third check valve 32 being provided between the second heat exchanger 23 and the intermediate heat exchanger 14, specifically, the third check valve 32 being provided in parallel with the second compressor 21, the third check valve 32 being provided to allow refrigerant to flow from only one side of the second heat exchanger 23 to one side of the intermediate heat exchanger 14.
It should be noted that the specific structure and types of the first check valve 24, the second check valve 25, and the third check valve 32 are not limited in the present invention, and may be set by those skilled in the art according to the actual situation.
Furthermore, in the preferred embodiment, the cascade heat pump system further includes a heat exchange water path 5, and a part of the heat exchange water path 5 is disposed in the first heat exchanger 12 to exchange heat with the refrigerant in the high-pressure refrigerant circulation circuit 1. It should be noted that the specific structure of the heat exchange waterway 5 is not limited in the present invention, and those skilled in the art can set the heat exchange waterway according to the actual situation.
Further, the high-pressure refrigerant circulation circuit 1 is further provided with a first air separation device (not shown in the figure), and the first air separation device is disposed at the air inlet of the first compressor 11. The first low-pressure refrigerant circulation circuit 2 is further provided with a second gas separation device (not shown in the figure) disposed at the gas inlet of the second compressor 21. The first air separation device and the second air separation device can effectively avoid the problem that the first compressor 11 and the second compressor 21 are in liquid impact, and effectively ensure the service lives of the first compressor 11 and the second compressor 21. It should be noted that, the specific structures of the first gas separation device and the second gas separation device are not limited in the present invention, and may be set by those skilled in the art according to practical situations.
Further, the cascade heat pump system further includes a temperature sensor for detecting an ambient temperature, a current refrigerant evaporation temperature of the intermediate heat exchanger 14, and a refrigerant temperature at an outlet of the second heat exchanger 23, a pressure sensor for detecting a current suction pressure of the first compressor 11, and a controller. It should be noted that, the specific structure, model, number and position of the temperature sensor and the pressure sensor are not limited in the present invention, and may be set by those skilled in the art according to practical situations.
The controller can control the operation states of the cascade heat pump system, for example, the controller can control the operation states of the first low-pressure refrigerant circulation circuit 2, the second low-pressure refrigerant circulation circuit 3, and the bypass branch 4, and the controller can also acquire the detection results of the temperature sensor and the pressure sensor, etc., which are not limitative. It will be understood by those skilled in the art that the present invention does not limit the specific structure and model of the controller, and the controller may be an original controller of the cascade heat pump system or a controller separately provided for executing the control method of the present invention, and those skilled in the art may set the structure and model of the controller according to actual use requirements.
Referring first to fig. 2, fig. 2 is a flow chart of main steps of the control method of the present invention. As shown in fig. 2, based on the cascade heat pump system described in the above embodiment, the control method of the present invention mainly includes the following steps:
s1: acquiring the ambient temperature of the cascade heat pump system;
s2: controlling the operation states of the first low-pressure refrigerant circulation loop and the second low-pressure refrigerant circulation loop according to the ambient temperature;
S3: acquiring operation parameters of a high-pressure refrigerant circulation loop;
S4: and controlling the operation state of the bypass branch according to the operation parameters of the high-pressure refrigerant circulation loop.
Firstly, in step S1, the controller acquires an ambient temperature of the cascade heat pump system detected by the temperature sensor; of course, the invention does not limit the specific time and mode of acquiring the ambient temperature, and the controller may acquire the ambient temperature in real time or at intervals, which is not limited, and may be set by a person skilled in the art according to practical situations. Preferably, the controller acquires the environmental temperature in real time, so that the running state of the cascade heat pump system can be timely and effectively adjusted, the running energy efficiency of the cascade heat pump system is further effectively improved, and the running range of the cascade heat pump system is enlarged.
Next, in step S2, the controller controls the operation states of the first low-pressure refrigerant circulation circuit 2 and the second low-pressure refrigerant circulation circuit 3 according to the ambient temperature.
It should be noted that, the specific control logic of step S2 is not limited in the present invention, the controller may control the on-off states of the first low-pressure refrigerant circulation loop 2 and the second low-pressure refrigerant circulation loop 3 according to the ambient temperature, and may also control the running speeds of the refrigerants in the first low-pressure refrigerant circulation loop 2 and the second low-pressure refrigerant circulation loop 3, which are not limited, and may be set by those skilled in the art according to practical situations.
Further, in step S3, the controller obtains the operation parameters of the high-pressure refrigerant circulation loop 1; of course, the present invention does not limit the specific parameter types of the operation parameters of the obtained high-pressure refrigerant circulation circuit 1, and the specific parameter types may be the operation frequency of the first compressor 11, or may be the discharge pressure or the suction pressure of the first compressor 11, which is not limited, and may be set by a person skilled in the art according to practical situations.
Next, in step S4, the controller controls the operation state of the bypass branch 4 according to the operation parameter of the high-pressure refrigerant circulation circuit 1.
It should be noted that, the specific control logic in step S4 is not limited in the present invention, the controller may control the on-off state of the bypass branch 4 according to the operation parameter of the high-pressure refrigerant circulation circuit 1, or may control the opening of the control valve 41 according to the operation parameter of the high-pressure refrigerant circulation circuit 1, so as to further control the operation state of the bypass branch 4, which is not limited, and may be set by a person skilled in the art according to the actual situation.
In addition, it should be noted that the specific execution sequence of the step S1 and the step S3 is not limited in the present invention, and may be executed simultaneously, or may be executed sequentially without any sequence, which is set by a person skilled in the art according to the actual situation.
Referring next to fig. 3, fig. 3 is a flowchart showing the specific steps of a first preferred embodiment of the control method of the present invention. As shown in fig. 3, based on the cascade heat pump system described in the above embodiment, the control method of the first preferred embodiment of the present invention includes the steps of:
s101: acquiring the ambient temperature of the cascade heat pump system;
S102: if the ambient temperature is greater than or equal to the preset ambient temperature, the first low-pressure refrigerant circulation loop is controlled to be not operated, and the second low-pressure refrigerant circulation loop is controlled to be operated;
S103: if the ambient temperature is less than the preset ambient temperature, controlling the first low-pressure refrigerant circulation loop to operate, and controlling the second low-pressure refrigerant circulation loop not to operate;
S104: acquiring the current refrigerant evaporation temperature and the maximum refrigerant evaporation temperature of the intermediate heat exchanger;
s105: calculating the difference between the maximum refrigerant evaporation temperature and the current refrigerant evaporation temperature, and recording the difference as a first difference;
S106: if the first difference value is smaller than a first preset difference value, controlling the bypass branch to operate;
S107: and if the first difference value is greater than or equal to a first preset difference value, controlling the bypass branch not to operate.
Firstly, in step S101, the controller acquires an ambient temperature of the cascade heat pump system detected by the temperature sensor; of course, the invention does not limit the specific time and mode of acquiring the ambient temperature, and the controller may acquire the ambient temperature in real time or at intervals, which is not limited, and may be set by a person skilled in the art according to practical situations. Preferably, the controller acquires the environmental temperature in real time, so that the running state of the cascade heat pump system can be timely and effectively adjusted, the running energy efficiency of the cascade heat pump system is further effectively improved, and the running range of the cascade heat pump system is enlarged.
Then, the controller controls the operation states of the first low-pressure refrigerant circulation circuit 2 and the second low-pressure refrigerant circulation circuit 3 according to the ambient temperature.
It should be noted that, the specific control logic of the above steps is not limited in the present invention, the controller may control the on-off states of the first low-pressure refrigerant circulation loop 2 and the second low-pressure refrigerant circulation loop 3 according to the ambient temperature, and may also control the running speeds of the refrigerants in the first low-pressure refrigerant circulation loop 2 and the second low-pressure refrigerant circulation loop 3, which are not limited, and may be set by those skilled in the art according to practical situations.
Preferably, in step S102, if the ambient temperature is greater than or equal to the preset ambient temperature, the controller controls the first low-pressure refrigerant circulation circuit 2 not to operate and controls the second low-pressure refrigerant circulation circuit 3 to operate, so as to effectively reduce the operation energy consumption of the cascade heat pump system.
Further, in step S103, if the ambient temperature is less than the preset ambient temperature, the controller controls the first low-pressure refrigerant circulation loop 2 to operate, and controls the second low-pressure refrigerant circulation loop 3 not to operate, so as to effectively ensure that the heat exchange amount of the intermediate heat exchanger 14 can make the high-pressure refrigerant circulation loop 1 normally operate, so as to meet the use requirement of the user.
It should be noted that, the specific setting value of the preset environmental temperature is not limited, and a person skilled in the art may set the setting value according to the actual operation condition of the cascade heat pump system, or may obtain the setting value according to the actual use requirement of the user, which is not limited.
Further preferably, in step S104, the controller acquires the current refrigerant evaporation temperature and the maximum refrigerant evaporation temperature of the intermediate heat exchanger 14 detected by the temperature sensor. It should be noted that, the present invention does not limit the specific time and mode for obtaining the current refrigerant evaporating temperature, and those skilled in the art can set the present invention according to the actual situation.
Then, the controller controls the operation state of the bypass branch 4 according to the current refrigerant evaporation temperature and the maximum refrigerant evaporation temperature; of course, the present invention does not limit the specific control logic of this step, for example, the controller may compare the current refrigerant evaporating temperature with the maximum refrigerant evaporating temperature, and control the operation state of the bypass branch 4 according to the comparison result.
Preferably, in step S105, the controller calculates a difference between the maximum refrigerant evaporation temperature and the current refrigerant evaporation temperature, and records the difference as a first difference.
The controller then controls the operating state of the bypass branch 4 in dependence on the first difference. Specifically, in step S106, if the first difference is smaller than the first preset difference, which indicates that the current refrigerant evaporating temperature is close to the maximum refrigerant evaporating temperature at this time, the first compressor 11 is at risk of stopping due to the too high intake air temperature and thus causing the high-pressure refrigerant circulation loop 1 to not operate, and the controller controls the bypass branch 4 to operate, so as to reduce the refrigerant evaporating temperature of the intermediate heat exchanger 14 by reducing the refrigerant condensing temperature of the intermediate heat exchanger 14, thereby effectively ensuring that the high-pressure refrigerant circulation loop 1 can normally operate.
Further, in step S107, if the first difference is greater than or equal to the first preset difference, which indicates that the current refrigerant evaporating temperature differs greatly from the maximum refrigerant evaporating temperature at this time, the current refrigerant evaporating temperature does not cause the problem that the first compressor 11 is stopped due to the too high intake air temperature and the high-pressure refrigerant circulation loop 1 is not operated, and the controller controls the bypass branch 4 not to operate, so as to improve the operation efficiency of the cascade heat pump system.
It should be noted that, the specific setting value of the first preset difference value is not limited in the present invention, and a person skilled in the art may set the specific setting value according to the actual operation condition of the cascade heat pump system, or may obtain the specific setting value according to the actual use requirement of the user, which is not limited; preferably, the first preset difference is 1 ℃, so as to ensure the high-pressure refrigerant circulation loop 1 to operate efficiently to the greatest extent.
In addition, it should be noted that the specific execution sequence of the step S101 and the step S104 is not limited in the present invention, and may be executed simultaneously, or may be executed sequentially without any sequence, which is set by a person skilled in the art according to the actual situation.
Referring next to fig. 4, fig. 4 is a flowchart showing the specific steps of a second preferred embodiment of the control method of the present invention. As shown in fig. 4, based on the cascade heat pump system described in the above embodiment, the control method of the second preferred embodiment of the present invention includes the steps of:
S201: acquiring the ambient temperature of the cascade heat pump system;
S202: if the ambient temperature is greater than or equal to the preset ambient temperature, the first low-pressure refrigerant circulation loop is controlled to be not operated, and the second low-pressure refrigerant circulation loop is controlled to be operated;
S203: if the ambient temperature is less than the preset ambient temperature, controlling the first low-pressure refrigerant circulation loop to operate, and controlling the second low-pressure refrigerant circulation loop not to operate;
s204: acquiring the current suction pressure and the maximum suction pressure of the first compressor;
S205: calculating the difference between the maximum suction pressure and the current suction pressure, and recording the difference as a second difference;
S206: if the second difference value is smaller than a second preset difference value, controlling the bypass branch to operate;
s207: and if the second difference value is greater than or equal to a second preset difference value, controlling the bypass branch not to operate.
First, in step S201, the controller acquires an ambient temperature where the cascade heat pump system is located, which is detected by the temperature sensor; of course, the invention does not limit the specific time and mode of acquiring the ambient temperature, and the controller may acquire the ambient temperature in real time or at intervals, which is not limited, and may be set by a person skilled in the art according to practical situations. Preferably, the controller acquires the environmental temperature in real time, so that the running state of the cascade heat pump system can be timely and effectively adjusted, the running energy efficiency of the cascade heat pump system is further effectively improved, and the running range of the cascade heat pump system is enlarged.
Then, the controller controls the operation states of the first low-pressure refrigerant circulation circuit 2 and the second low-pressure refrigerant circulation circuit 3 according to the ambient temperature.
It should be noted that, the specific control logic of the above steps is not limited in the present invention, the controller may control the on-off states of the first low-pressure refrigerant circulation loop 2 and the second low-pressure refrigerant circulation loop 3 according to the ambient temperature, and may also control the running speeds of the refrigerants in the first low-pressure refrigerant circulation loop 2 and the second low-pressure refrigerant circulation loop 3, which are not limited, and may be set by those skilled in the art according to practical situations.
Preferably, in step S202, if the ambient temperature is greater than or equal to the preset ambient temperature, the controller controls the first low-pressure refrigerant circulation circuit 2 not to operate and controls the second low-pressure refrigerant circulation circuit 3 to operate, so as to effectively reduce the operation energy consumption of the cascade heat pump system.
Further, in step S203, if the ambient temperature is less than the preset ambient temperature, the controller controls the first low-pressure refrigerant circulation circuit 2 to operate, and controls the second low-pressure refrigerant circulation circuit 3 not to operate, so as to effectively ensure that the heat exchange amount of the intermediate heat exchanger 14 can make the high-pressure refrigerant circulation circuit 1 normally operate, so as to meet the use requirement of the user.
It should be noted that, the specific setting value of the preset environmental temperature is not limited, and a person skilled in the art may set the setting value according to the actual operation condition of the cascade heat pump system, or may obtain the setting value according to the actual use requirement of the user, which is not limited.
Further preferably, in step S204, the controller acquires the current suction pressure and the maximum suction pressure of the first compressor 11 detected by the pressure sensor. It should be noted that, the present invention does not limit the specific time and mode of acquiring the current inhalation pressure, and those skilled in the art can set the present invention according to the actual situation.
Then, the controller controls the operation state of the bypass branch 4 according to the current suction pressure and the maximum suction pressure; of course, the present invention is not limited to the specific control logic of this step, and for example, the controller may compare the current suction pressure with the maximum suction pressure, and control the operation state of the bypass branch 4 according to the comparison result.
Preferably, in step S205, the controller calculates a difference between the maximum suction pressure and the current suction pressure, and records the difference as a second difference.
The controller then controls the operating state of the bypass branch 4 in dependence on the second difference. Specifically, in step S206, if the second difference is smaller than the second preset difference, which indicates that the current suction pressure is close to the maximum suction pressure at this time, the first compressor 11 is at risk of stopping due to the excessively high suction pressure and thus the high-pressure refrigerant circulation circuit 1 is not operating, and the controller controls the bypass branch 4 to operate, so as to reduce the refrigerant evaporation temperature of the intermediate heat exchanger 14 by reducing the refrigerant condensation temperature of the intermediate heat exchanger 14, thereby reducing the suction pressure of the first compressor 11, and ensuring that the high-pressure refrigerant circulation circuit 1 can normally operate.
Further, in step S207, if the second difference is greater than or equal to the second preset difference, which indicates that the current suction pressure is greater than the maximum suction pressure at this time, the first compressor 11 can normally operate, the controller controls the bypass branch 4 not to operate, so as to improve the operation efficiency of the cascade heat pump system.
It should be noted that, the specific setting value of the second preset difference is not limited, and a person skilled in the art may set the specific setting value according to the actual operation condition of the cascade heat pump system, or may obtain the specific setting value according to the actual use requirement of the user, which is not limited.
In addition, it should be noted that the specific execution sequence of the step S201 and the step S204 is not limited in the present invention, and may be executed simultaneously, or may be executed sequentially without any sequence, which is set by a person skilled in the art according to the actual situation.
In addition, in the case that the first low pressure refrigerant circulation circuit 1 is operated and the bypass branch 4 is not operated, that is, in the case that the first low pressure refrigerant circulation circuit 1 is operated and the first difference value is greater than or equal to the first preset difference value or the second difference value is greater than or equal to the second preset difference value, the control method of the present invention further includes obtaining the temperature of the refrigerant at the outlet of the second heat exchanger 23, and further controlling the operation state of the bypass branch 4 according to the temperature of the refrigerant at the outlet of the second heat exchanger 23, so as to effectively avoid the problems of frosting, even frost cracking, of the second heat exchanger 23.
It should be noted that, the present invention does not limit the specific timing and mode of acquiring the refrigerant temperature at the outlet of the second heat exchanger 23, and does not limit the specific control logic of the above steps, so that those skilled in the art can set the method according to the actual situation.
Preferably, if the temperature of the refrigerant at the outlet of the second heat exchanger 23 is less than or equal to the preset refrigerant temperature, the controller controls the bypass branch 4 to operate, so that the refrigerant flowing out of the exhaust port of the second compressor 21 directly enters the second heat exchanger 23 through the bypass branch 4, and further, the problem that the second heat exchanger 23 frosts or even frost cracks due to too low temperature is effectively avoided.
Further, if the temperature of the refrigerant at the outlet of the second heat exchanger 23 is greater than the preset refrigerant temperature, the controller controls the bypass branch 4 not to operate, so as to effectively ensure the operation energy efficiency of the cascade heat pump system.
It should be noted that the present invention does not limit the specific set value of the preset refrigerant temperature, and a person skilled in the art can set the preset refrigerant temperature according to the actual operation condition of the cascade heat pump system.
Thus far, the technical solution of the present invention has been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of protection of the present invention is not limited to these specific embodiments. Equivalent modifications and substitutions for related technical features may be made by those skilled in the art without departing from the principles of the present invention, and such modifications and substitutions will fall within the scope of the present invention.
Claims (6)
1. A control method of a cascade heat pump system is characterized in that the cascade heat pump system comprises a high-pressure refrigerant circulation loop, a first low-pressure refrigerant circulation loop, a second low-pressure refrigerant circulation loop and a bypass branch,
The high-pressure refrigerant circulation loop is provided with a first compressor, a first heat exchanger, a first throttling component and an intermediate heat exchanger, the first low-pressure refrigerant circulation loop is provided with a second compressor, the intermediate heat exchanger, a second throttling component and a second heat exchanger, the second low-pressure refrigerant circulation loop is provided with a fluorine pump, the second heat exchanger and the intermediate heat exchanger, two ends of the fluorine pump are connected with the first low-pressure refrigerant circulation loop, two ends of the second compressor are connected with the second low-pressure refrigerant circulation loop, the first low-pressure refrigerant circulation loop and the second low-pressure refrigerant circulation loop are arranged to be capable of selectively exchanging heat with the high-pressure refrigerant circulation loop through the intermediate heat exchanger,
The first end of the bypass branch is connected between the connection point of the fluorine pump and the first low-pressure refrigerant circulation loop and the second heat exchanger, the second end of the bypass branch is connected between the second compressor and the intermediate heat exchanger, a control valve is arranged on the bypass branch and can control the on-off state of the bypass branch,
The control method comprises the following steps:
Acquiring the ambient temperature of the cascade heat pump system;
Controlling the operation states of the first low-pressure refrigerant circulation loop and the second low-pressure refrigerant circulation loop according to the ambient temperature, wherein,
If the ambient temperature is greater than or equal to the preset ambient temperature, the first low-pressure refrigerant circulation loop is controlled to be not operated, and the second low-pressure refrigerant circulation loop is controlled to be operated;
If the ambient temperature is smaller than the preset ambient temperature, controlling the first low-pressure refrigerant circulation loop to operate, and controlling the second low-pressure refrigerant circulation loop not to operate;
Acquiring operation parameters of the high-pressure refrigerant circulation loop;
Controlling the operation state of the bypass branch according to the operation parameters of the high-pressure refrigerant circulation loop;
the obtaining the operation parameters of the high-pressure refrigerant circulation loop includes:
acquiring the current refrigerant evaporation temperature and the maximum refrigerant evaporation temperature of the intermediate heat exchanger, or acquiring the current suction pressure and the maximum suction pressure of the first compressor;
the controlling the operation state of the bypass branch according to the operation parameters of the high-pressure refrigerant circulation loop includes:
And controlling the operation state of the bypass branch according to the current refrigerant evaporation temperature and the maximum refrigerant evaporation temperature, or controlling the operation state of the bypass branch according to the current suction pressure and the maximum suction pressure.
2. The control method according to claim 1, wherein the step of controlling the operation state of the bypass branch according to the current refrigerant evaporation temperature and the maximum refrigerant evaporation temperature specifically includes:
Calculating the difference between the maximum refrigerant evaporation temperature and the current refrigerant evaporation temperature, and recording the difference as a first difference;
If the first difference value is smaller than a first preset difference value, controlling the bypass branch to operate; and/or
And if the first difference value is greater than or equal to the first preset difference value, controlling the bypass branch not to operate.
3. The control method according to claim 1, wherein the step of controlling the operation state of the bypass branch according to the current suction pressure and the maximum suction pressure specifically includes:
calculating the difference between the maximum inhalation pressure and the current inhalation pressure, and recording the difference as a second difference;
if the second difference value is smaller than a second preset difference value, controlling the bypass branch to operate; and/or
And if the second difference value is greater than or equal to the second preset difference value, controlling the bypass branch not to operate.
4. A control method according to any one of claims 2 or 3, wherein in the case where the first low-pressure refrigerant circulation circuit is operated and the bypass branch is not operated, the control method further comprises:
acquiring the temperature of the refrigerant at the outlet of the second heat exchanger;
and further controlling the operation state of the bypass branch according to the temperature of the refrigerant at the outlet of the second heat exchanger.
5. The method according to claim 4, wherein the step of further controlling the operation state of the bypass passage according to the temperature of the refrigerant at the outlet of the second heat exchanger comprises:
If the temperature of the refrigerant at the outlet of the second heat exchanger is less than or equal to the preset refrigerant temperature, controlling the bypass branch to operate; and/or
And if the temperature of the refrigerant at the outlet of the second heat exchanger is higher than the preset refrigerant temperature, controlling the bypass branch not to operate.
6. A cascade heat pump system, characterized in that it comprises a controller capable of executing the control method of any one of claims 1 to 5.
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| CN117469871B (en) * | 2023-12-26 | 2024-04-05 | 珠海格力电器股份有限公司 | Control method and device of refrigeration system, refrigeration system and storage medium |
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