CN115164433A - Cascade heat pump system and control method thereof - Google Patents
Cascade heat pump system and control method thereof Download PDFInfo
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- CN115164433A CN115164433A CN202210760226.6A CN202210760226A CN115164433A CN 115164433 A CN115164433 A CN 115164433A CN 202210760226 A CN202210760226 A CN 202210760226A CN 115164433 A CN115164433 A CN 115164433A
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- 238000000034 method Methods 0.000 title claims abstract description 28
- 239000003507 refrigerant Substances 0.000 claims abstract description 82
- 238000004891 communication Methods 0.000 claims abstract description 79
- 239000013589 supplement Substances 0.000 claims abstract description 62
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims abstract description 46
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 46
- 239000011737 fluorine Substances 0.000 claims abstract description 46
- 230000001502 supplementing effect Effects 0.000 claims abstract description 22
- 238000005286 illumination Methods 0.000 claims description 47
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- 230000007613 environmental effect Effects 0.000 claims description 5
- 238000005265 energy consumption Methods 0.000 abstract description 9
- 238000010438 heat treatment Methods 0.000 abstract description 9
- 230000001276 controlling effect Effects 0.000 description 20
- 239000007788 liquid Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 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
- 238000003889 chemical engineering Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
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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
- F25B27/00—Machines, plants or systems, using particular sources of energy
- F25B27/002—Machines, plants or systems, using particular sources of energy using solar energy
- F25B27/005—Machines, plants or systems, using particular sources of energy using solar energy in compression type systems
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- 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
- F25B41/40—Fluid line arrangements
- F25B41/42—Arrangements for diverging or converging flows, e.g. branch lines or junctions
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
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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 problems of high cost, high heat loss and low heat efficiency of the existing cascade heat pump system. Therefore, the cascade heat pump system comprises a high-pressure refrigerant circulation loop, a low-pressure refrigerant circulation loop, a solar air supplement branch and a first communication branch, wherein a second compressor and a fluorine pump are arranged in the low-pressure refrigerant circulation loop, two ends of the fluorine pump are connected with a second throttling component in parallel, and the energy consumption is reduced by selectively operating the second compressor and the fluorine pump; the solar air supplement branch is provided with a solar heat collection device, and the solar air supplement branch and the first communicating branch are connected with the low-pressure refrigerant circulation loop, so that part of the refrigerant flowing through the intermediate heat exchanger is introduced into the solar heat collection device to be heated and evaporated and then is used for supplementing air to the second compressor, and the energy consumption is reduced; in addition, the invention can avoid the problem of secondary heat exchange, thereby reducing the cost and heat loss and improving the heating efficiency.
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
With the popularization of policies of energy conservation and emission reduction, industries such as food processing, textile, chemical engineering and the like use high-temperature heat pump systems to carry out high-temperature heating treatment in more and more application occasions. The industrial heating demand is strong, and the application requirements of the high-temperature heat pump system are higher and higher. First, the final heating temperature of the high temperature heat pump system is typically greater than 70 ℃ or even over 90 ℃. Secondly, the working condition span of the application environment of the heating system is very large, the environmental temperature is from-30 ℃ to 35 ℃, and high-temperature hot water or hot air needs to be provided in both winter and summer.
The high temperature hot water used in industry is high, which results in that the common heat pump system cannot meet the actual heating requirement, and the technology of using the cascade heat pump system to provide high temperature hot water is mature. The cascade heat pump system generally comprises a high-pressure refrigerant circulation loop and a low-pressure refrigerant circulation loop, wherein the high-pressure refrigerant circulation loop and the low-pressure refrigerant circulation loop exchange heat through a shared intermediate heat exchanger to achieve the purpose of providing high-temperature hot water. However, outside the rated working condition, especially under the working condition of high ambient temperature, the cascade heat pump system still adopts the two-stage compression mode, which results in low flexibility and low energy efficiency of the cascade heat pump system. The existing part of the overlapping type heat pump systems utilize solar energy to solve the problems, but the existing overlapping type heat pump systems combined with the solar energy need to carry out secondary heat exchange with an air energy system through a heat exchanger, so that the overlapping type heat pump systems have the problems of high cost, high heat loss and low heat efficiency.
Accordingly, there is a need in the art for a new cascade heat pump system and a control method thereof to solve the above technical problems.
Disclosure of Invention
The present invention is directed to solving the above-mentioned problems, i.e., solving the problems of high cost, high heat loss and low thermal efficiency of the existing cascade heat pump system.
In a first aspect, the invention provides a cascade heat pump system, which includes a high-pressure refrigerant circulation loop, a low-pressure refrigerant circulation loop, a solar air supplement branch and a first communication branch, wherein the high-pressure refrigerant circulation loop is provided with a first compressor, a first heat exchanger, a first throttling member and an intermediate heat exchanger, the low-pressure refrigerant circulation loop is provided with a second compressor, the intermediate heat exchanger, a fluorine pump and a second heat exchanger, two ends of the fluorine pump are connected in parallel with the second throttling member, the solar air supplement branch is connected with the low-pressure refrigerant circulation loop, a first end of the solar air supplement branch is connected between the intermediate heat exchanger and the fluorine pump, a second end of the solar air supplement branch is connected with the first end of the first communication branch, the solar air supplement branch is provided with a third throttling member and a solar heat collection device, and a second end of the first communication branch is connected to an air supplement port of the second compressor.
In a preferred technical solution of the above overlapping type heat pump system, the overlapping type heat pump system further includes a second communicating branch, a first end of the second communicating branch is connected to a connection between the solar air make-up branch and the first communicating branch, and a second end of the second communicating branch is connected between the second heat exchanger and an air inlet of the second compressor.
In a preferred technical solution of the cascade heat pump system, a first control valve is disposed on the first communication branch, and the first control valve is configured to control on-off states of the solar energy air supplement branch and the first communication branch; and/or a second control valve is arranged on the second communication branch, and the second control valve is set to control the on-off state of the solar air supplementing branch and the second communication branch.
In a preferred technical solution of the above overlapping type heat pump system, the overlapping type heat pump system further includes a bypass branch, the bypass branch is disposed at two ends of the second compressor in parallel, a third control valve is disposed on the bypass branch, and the third control valve is set to be capable of controlling an on-off state of the bypass branch.
In a preferred technical scheme of the cascade heat pump system, the cascade heat pump system further comprises a heat exchange water path, and a part of the heat exchange water path is arranged in the first heat exchanger, so that water in the heat exchange water path exchanges heat with a refrigerant in the high-pressure refrigerant circulation loop through the first heat exchanger.
In a preferred technical solution of the above-mentioned cascade heat pump system, the cascade heat pump system includes a high-pressure refrigerant circulation loop, a low-pressure refrigerant circulation loop, a solar energy air supplement branch, a first communication branch and a second communication 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 low-pressure refrigerant circulation loop is provided with a second compressor, the intermediate heat exchanger, a fluorine pump and a second heat exchanger, two ends of the fluorine pump are provided with a second throttling component in parallel, the solar energy air supplement branch is connected to the low-pressure refrigerant circulation loop, a first end of the solar energy air supplement branch is connected between the intermediate heat exchanger and the fluorine pump, a second end of the solar energy air supplement branch is connected to a first end of the first communication branch and a first end of the second communication branch, the solar energy air supplement branch is provided with a third throttling component and a solar energy heat collecting device, a second end of the first communication branch is connected to an air supplement opening of the second compressor, a second end of the second communication branch is connected to a heat exchanger of the second compressor, and the control method includes: acquiring the illumination intensity at the solar heat collection device; and controlling the communication state of the solar air supplementing branch and the first communication branch and the second communication branch according to the illumination intensity.
In a preferred technical solution of the above control method, "controlling the communication state of the solar energy gas supplementing branch with the first communicating branch and the second communicating branch according to the illumination intensity" specifically includes: if the illumination intensity is smaller than the preset illumination intensity, controlling the solar energy air supplement branch to be not communicated with the first communicating branch and the second communicating branch; if the illumination intensity is greater than or equal to the preset illumination intensity, further acquiring the ambient temperature of the cascade heat pump system; and further controlling the communication state of the solar air supplementing branch and the first communication branch and the second communication branch according to the environment temperature.
In a preferred technical solution of the above control method, the step of controlling the communication states of the solar air supplement branch and the first and second communication branches according to the ambient temperature specifically includes: if the environmental temperature is lower than the preset environmental temperature, controlling the solar air supplement branch to be communicated with the first communicating branch and the second communicating branch; and if the environment temperature is greater than or equal to the preset environment temperature, controlling the solar air supplementing branch to be communicated with the second communicating branch and not communicated with the first communicating branch.
In a preferred technical solution of the above control method, the cascade heat pump system further includes a bypass branch, the bypass branch is connected to the low-pressure refrigerant circulation loop, the bypass branch is disposed at two ends of the second compressor in parallel, and the control method further includes: acquiring the ambient temperature of the cascade heat pump system; and controlling the running states of the bypass branch, the fluorine pump and the second compressor according to the ambient temperature.
In a preferred embodiment of the above control method, the step of "controlling the operating states of the bypass branch, the fluorine pump, and the second compressor according to the ambient temperature" specifically includes: if the ambient temperature is lower than the preset ambient temperature, controlling the bypass branch and the fluorine pump not to operate, and controlling the second compressor to operate; controlling the bypass branch and the fluorine pump to operate and controlling the second compressor not to operate if the ambient temperature is greater than or equal to the preset ambient temperature.
Under the condition of adopting the technical scheme, the air supplementing device introduces a part of refrigerant flowing through the intermediate heat exchanger into the solar heat collecting device through the solar air supplementing branch to supplement air to the second compressor after heating and evaporating so as to effectively reduce the operation energy consumption; in addition, the invention effectively avoids the problem that the heat exchanger needs to carry out secondary heat exchange with the air energy system by directly applying the solar heat collection device, thereby effectively reducing the cost and the heat loss of the cascade heat pump system and improving the heating efficiency; in addition, the second compressor and the fluorine pump can be selectively operated in the low-pressure refrigerant circulation loop, so that the operation energy consumption of the cascade heat pump system can be further effectively reduced.
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 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 flow chart of the specific steps of a preferred embodiment of the control method of the present invention;
reference numerals:
1. a high pressure refrigerant circulation loop; 11. a first compressor; 12. a first heat exchanger; 13. a first throttle member; 14. an intermediate heat exchanger;
2. a low pressure refrigerant circulation loop; 21. a second compressor; 22. a fluorine pump; 23. a second heat exchanger; 24. a second throttling member; 25. a liquid storage member;
3. a solar energy air supplement branch; 31. a third throttling means; 32. a solar heat collection device;
4. a first communicating branch; 41. a first control valve;
5. a second communicating branch; 51. a second control valve;
6. a bypass branch; 61. a third control valve;
7. and a heat exchange water path.
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 only for explaining the technical principle of the present invention, and are not intended to limit the scope of the present invention. And can be adjusted as needed by those skilled in the art to suit particular applications. For example, the cascade heat pump system described in the present invention may be a domestic cascade heat pump system, and may also be an industrial cascade heat pump system, which are not limited, and those 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 are within the scope of the present invention without departing from the basic concept thereof.
It should be noted that, in the description of the preferred embodiments, unless explicitly stated or limited otherwise, the terms "first", "second", and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Furthermore, the terms "connected" and "connecting" should be interpreted broadly, such as mechanically or electrically, directly or indirectly through intervening elements, or internally to both elements, and thus should not be taken to limit the present invention. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Further, it should be noted that in the description of the present invention, although the steps of the control method of the present invention are described in a specific order in the present application, the order is not limited, and those skilled in the art may perform the steps in a different order without departing from the basic principle of the present invention.
Referring first to fig. 1, fig. 1 is a schematic diagram of a cascade heat pump system according to the present invention. As shown in fig. 1, the cascade heat pump system of the present invention includes a high-pressure refrigerant circulation loop 1, a low-pressure refrigerant circulation loop 2, a solar air make-up branch 3, and a first communication branch 4, wherein the high-pressure refrigerant circulation loop 1 is provided with a first compressor 11, a first heat exchanger 12, a first throttling component 13, and an intermediate heat exchanger 14, the low-pressure refrigerant circulation loop 2 is provided with a second compressor 21, an intermediate heat exchanger 14, a liquid storage component 25, a fluorine pump 22, and a second heat exchanger 23, and two ends of the fluorine pump 22 are connected in parallel with a second throttling component 24. The second compressor 21 and the fluorine pump 22 can be selectively connected to the low-pressure refrigerant circulation loop 2, so as to effectively reduce the operation energy consumption of the cascade heat pump system.
It should be noted that the present invention does not limit the specific types of the refrigerants flowing in the high-pressure refrigerant circulation circuit 1 and the low-pressure refrigerant circulation circuit 2, and those skilled in the art can set the types according to actual situations. In a specific embodiment, the refrigerant in the high-pressure refrigerant circuit 1 is the refrigerant R134a, and the refrigerant in the low-pressure refrigerant circuit 2 is the refrigerant R410A.
In addition, it should be noted that the present invention does not limit the specific structure of the intermediate heat exchanger 14, and it may be a shell-and-tube heat exchanger or a plate heat exchanger, and those skilled in the art can set the structure according to the actual situation. In the present 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 low-pressure refrigerant circulation circuit 2 in the intermediate heat exchanger 14.
Specifically, the intermediate heat exchanger 14 includes a first heat exchange channel and a second heat exchange channel, the refrigerant in the high-pressure refrigerant circulation loop 1 flows through the first heat exchange channel, the refrigerant in the low-pressure refrigerant circulation loop 2 flows through the second heat exchange channel, and the first heat exchange channel and the second heat exchange channel are arranged in a staggered manner, so as to achieve the purpose of exchanging heat between the refrigerant in the high-pressure refrigerant circulation loop 1 and the refrigerant in the low-pressure refrigerant circulation loop 2.
In addition, it should be noted that the present invention does not set any limit to the specific structures and specific models of the first compressor 11, the second compressor 21, the fluorine pump 22, the first throttling means 13, the second throttling means 24, the first heat exchanger 12, and the second heat exchanger 23; the first compressor 11 and the second compressor 21 may be frequency conversion compressors, and may also be fixed frequency compressors, preferably, the first compressor 11 and the second compressor 21 are frequency conversion compressors, so as to control the operation state of the cascade heat pump system; the fluorine pump 22 can be a fluorine-lined centrifugal pump, a fluorine-lined magnetic pump or a fluorine-lined self-priming pump; the first throttling component 13 and the second throttling component 24 can be electronic expansion valves, capillary tubes 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 restrictive and can be set by those skilled in the art according to the actual situation.
In addition, the solar air supplement branch 3 is connected to the low-pressure refrigerant circulation loop 2, a first end of the solar air supplement branch 3 is connected between the intermediate heat exchanger 14 and the fluorine pump 22, a second end of the solar air supplement branch 3 is connected to a first end of the first communication branch 4, a third throttling component 31 and a solar heat collection device 32 are arranged on the solar air supplement branch 3, and a second end of the first communication branch 4 is connected to an air supplement port (port c in fig. 1) of the second compressor 21. Of course, the present invention does not limit the specific structure of the third throttling component 31 and the solar heat collecting device 32, and the third throttling component 31 may be an electronic expansion valve or a capillary tube; the solar heat collecting device 32 may be a heat collecting plate or a heat collecting tube, as long as it can collect heat to evaporate the refrigerant, and those skilled in the art can set the heat collecting device according to actual situations.
Further, the cascade heat pump system further comprises a second communication branch 5, a first end of the second communication branch 5 is connected to a connection position of the solar energy air supplementing branch 3 and the first communication branch 4, and a second end of the second communication branch 5 is connected between the second heat exchanger 23 and an air inlet (port b in fig. 1) of the second compressor 21; in fig. 1, the port a is a discharge port of the second compressor 21.
Preferably, a first control valve 41 is arranged on the first communicating branch 4, and the first control valve 41 is set to control the on-off state of the solar air supplement branch 3 and the first communicating branch 4; the second communication branch 5 is provided with a second control valve 51, and the second control valve 51 is set to control the on-off state of the solar air supplement branch 3 and the second communication branch 5.
The solar air supplement branch 3 can be selectively communicated with the first communication branch 4 and the second communication branch 5, wherein part of the refrigerant flowing through the intermediate heat exchanger 14 can enter the solar heat collection device 32 through the solar air supplement branch 3 to be heated and evaporated, and under the condition that the solar air supplement branch 3 is communicated with the first communication branch 4, the evaporated refrigerant can return to the second compressor 21 through the air supplement port to be supplemented with air, so that the operation energy efficiency of the low-pressure refrigerant circulation loop 2 is improved; in addition, under the condition that the solar energy supplementing branch 3 is communicated with the second communicating branch 5, the second control valve 51 can adjust the opening degree to divert more refrigerants evaporated by the solar energy heat collecting device 32 to the outlet of the second heat exchanger 23 and then return to the second compressor 21 through the air inlet, so as to avoid the excessive gaseous refrigerants supplemented to the second compressor 21 by the first communicating branch 4.
It should be noted that the present invention does not limit any specific type or specific structure of the first control valve 41 and the second control valve 51, and in the preferred embodiment, the first control valve 41 and the second control valve 51 are both solenoid valves to more effectively and precisely control the amount of air supplement to the second compressor 21.
Preferably, in this embodiment, the cascade heat pump system further includes a bypass branch 6, the bypass branch 6 is disposed at two ends of the second compressor 21 in parallel, a third control valve 61 is disposed on the bypass branch 6, and the third control valve 61 is configured to control an on-off state of the bypass branch 6. Further, the third control valve 61 is a check valve, and the check valve is configured to allow the refrigerant to flow from one side of the second heat exchanger 23 to one side of the intermediate heat exchanger 14.
The cascade heat pump system can selectively connect the second compressor 21 and the fluorine pump 22 into the low-pressure refrigerant circulation loop 2 so as to reduce the operation energy consumption. When the second compressor 21 is operated, the fluorine pump 22 is not operated, and the third control valve 61 is in a closed state; when the fluorine pump 22 is operated, the second compressor 21 and the second throttling member 24 are in a closed state, and the third control valve 61 is in an open state.
Further preferably, the cascade heat pump system further comprises a heat exchange water path 7, and a part of the heat exchange water path 7 is arranged in the first heat exchanger 12, so that water in the heat exchange water path 7 exchanges heat with refrigerant in the high-pressure refrigerant circulation loop 1 through the first heat exchanger 12, and the requirement of a user for preparing hot water is effectively met.
Further, the cascade heat pump system further includes an illuminometer, a temperature sensor and a controller, the illuminometer can acquire the illumination intensity at the solar heat collection device 32, and the temperature sensor can acquire the ambient temperature at which the cascade heat pump system is located, of course, the specific structures and the arrangement positions of the illuminometer and the temperature sensor are not limited, and can be set by a person skilled in the art. The controller can obtain the detection results of the illuminometer and the temperature sensor, and the controller can also control the operation state of the cascade heat pump system, for example, the communication state of the solar air make-up branch 3 with the first communication branch 4 and the second communication branch 5, and the like, which is not limiting. It can be understood by those skilled in the art that the present invention does not limit the specific structure and type of the controller, and the controller may be the original controller of the cascade heat pump system, or may be a controller separately configured to execute the control method of the present invention, and those skilled in the art can set the structure and type of the controller according to the actual use requirement.
Referring 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 illumination intensity of a solar heat collection device;
s2: and controlling the communication state of the solar energy air supplementing branch and the first communication branch and the second communication branch according to the illumination intensity.
First, in step S1, the controller obtains the illumination intensity at the solar heat collection device 32 through the illuminometer, and of course, the controller can obtain the illumination intensity in real time or at certain time intervals, which is not limiting, and the present invention does not set any limitation on the specific obtaining manner of the illumination intensity at the solar heat collection device 32, and is set by a person skilled in the art.
Next, in step S2, the controller controls the communication state of the solar energy air supplement branch 3 with the first communication branch 4 and the second communication branch 5 according to the illumination intensity. The controller can compare the ratio of the illumination intensity to the preset illumination intensity with the preset ratio, and selectively communicate the solar energy air-supplementing branch 3 with the first communication branch 4 or the second communication branch 5 according to the comparison result, or communicate the solar energy air-supplementing branch with the second communication branch 5, and the controller can set the solar energy air-supplementing branch according to the actual situation, and the invention does not limit the specific control mode of the step S2.
Referring next to fig. 3, fig. 3 is a flowchart illustrating specific steps of a 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 preferred embodiment of the present invention includes the following steps:
s101: acquiring the illumination intensity of a solar heat collection device;
s102: if the illumination intensity is smaller than the preset illumination intensity, the solar energy air supplement branch is controlled not to be communicated with the first communicating branch and the second communicating branch;
s103: if the illumination intensity is greater than or equal to the preset illumination intensity, further acquiring the ambient temperature of the cascade heat pump system;
s104: if the ambient temperature is lower than the preset ambient temperature, controlling the solar air supplement branch to be communicated with the first communicating branch and the second communicating branch;
s105: and if the ambient temperature is greater than or equal to the preset ambient temperature, controlling the solar air supply branch to be communicated with the second communicating branch and not communicated with the first communicating branch.
First, in step S101, the controller obtains the illumination intensity at the solar heat collection device 32 through the illuminometer, and of course, the controller can obtain the illumination intensity in real time or at certain time intervals, which is not limiting, and the present invention does not limit any specific obtaining manner of the illumination intensity at the solar heat collection device 32, and the skilled person can set the method according to the actual situation.
And then, the controller controls the communication state of the solar energy air supplementing branch 3, the first communication branch 4 and the second communication branch 5 according to the illumination intensity.
Preferably, in step S102, if the illumination intensity is less than the preset illumination intensity, the controller controls the solar energy gas supplementing branch 3 to be not communicated with the first communicating branch 4 and the second communicating branch 5. In this situation, the heat collected by the solar heat collecting device 32 and converted by the solar energy is not enough to evaporate the refrigerant flowing out of the intermediate heat exchanger 14, and therefore, the solar energy air supplementing branch 3 is not communicated with the first communicating branch 4 and the second communicating branch 5, so as to effectively avoid the problem of liquid impact occurring in the second compressor 21, and further effectively guarantee the service life of the second compressor 21.
It should be noted that, the present invention does not limit any specific setting value of the preset illumination intensity, and the setting value may be set according to the actual operation condition of the cascade heat pump system, or may be set according to the actual heat collecting condition of the solar heat collecting device 32, and it is understood that the change of the specific setting value of the preset illumination intensity does not depart from the basic principle of the present invention, and still falls into the protection scope of the present invention.
Further, in step S103, if the illumination intensity is greater than or equal to the preset illumination intensity, the controller further obtains the ambient temperature of the cascade heat pump system through the temperature sensor.
Then, the controller further controls the communication state of the solar energy air supplement branch 3 with the first communication branch 4 and the second communication branch 5 according to the environment temperature. It should be noted that the present invention does not set any limit to the specific control logic of the present step, and the skilled person can set it by himself.
As a specific implementation manner, in step S104, if the ambient temperature is lower than the preset ambient temperature, the controller controls the solar air supplement branch 3 to be communicated with both the first communicating branch 4 and the second communicating branch 5, so that part of the refrigerant in the low-pressure refrigerant circulation loop 2 passes through the intermediate heat exchanger 14, and then the solar air supplement branch 3 and the first communicating branch 4 supplement air to the second compressor 21, and the air supplement amount of the second compressor 21 is regulated and controlled by the second communicating branch 5.
It should be noted that the specific opening degrees of the first control valve 41 and the second control valve 51 are not limited in the present invention, and can be set by a person skilled in the art according to actual situations.
Further, in step S105, if the ambient temperature is greater than or equal to the preset ambient temperature, the controller controls the solar air supplement branch 3 to be communicated with the second communicating branch 5 and not communicated with the first communicating branch 4.
In addition, in the preferred embodiment, the control method of the present invention further includes controlling the operation states of the bypass branch 6, the fluorine pump 22 and the second compressor 21 according to the ambient temperature, so as to achieve the purpose of reducing the energy consumption in the low-pressure refrigerant circulation loop 2 under the large-span ambient condition by selectively operating the fluorine pump 22 and the second compressor 21, and further improving the operation energy efficiency of the cascade heat pump system.
Specifically, if the ambient temperature is less than a preset ambient temperature, the controller controls the bypass branch 6 and the fluorine pump 22 not to operate, and controls the second compressor 21 to operate; if the ambient temperature is greater than or equal to the preset ambient temperature, the controller controls the bypass branch 6 and the fluorine pump 22 to operate, and controls the second compressor 21 not to operate.
It should be noted that the preset ambient temperature in step S104 and step S105 is the same as the preset ambient temperature in the above steps, but it should be understood that the invention does not limit the specific set value of the preset ambient temperature, and those skilled in the art can set the set value according to the actual situation.
In addition, it should be noted that, the present invention does not set any limit to the specific execution sequence of the step of controlling the communication state of the solar energy gas supplementing branch 3 with the first communication branch 4 and the second communication branch 5 according to the illumination intensity and the step of controlling the operation state of the bypass branch 6, the fluorine pump 22 and the second compressor 21 according to the ambient temperature; preferably, the two steps can be executed simultaneously, so as to further effectively improve the operation energy efficiency of the cascade heat pump system.
Specifically, in the case that the ambient temperature is less than the preset ambient temperature and the illumination intensity is less than the preset illumination intensity, the controller controls the bypass branch 6 and the fluorine pump 22 not to operate, and controls the second compressor 21 to operate, so as to effectively ensure the operation energy efficiency; in addition, the controller still controls solar energy tonifying qi branch 3 and first intercommunication branch 4 and second intercommunication branch 5 not to be linked together to effectively avoid second compressor 21 to appear liquid attack phenomenon.
Under the condition that the ambient temperature is greater than or equal to the preset ambient temperature and the illumination intensity is less than the preset illumination intensity, the controller controls the bypass branch 6 and the fluorine pump 22 to operate, controls the second compressor 21 not to operate, and controls the pumping power of the fluorine pump 22 to be much less than that of the second compressor 21, so as to reduce the operation energy consumption by operating the fluorine pump 22; in addition, the controller still controls solar energy tonifying qi branch 3 and first intercommunication branch 4 and second intercommunication branch 5 not to be linked together to effectively avoid second compressor 21 to appear liquid attack phenomenon.
Under the condition that the ambient temperature is lower than the preset ambient temperature and the illumination intensity is greater than or equal to the preset illumination intensity, the controller controls the bypass branch 6 and the fluorine pump 22 not to operate, and controls the second compressor 21 to operate so as to effectively ensure the operation energy efficiency; in addition, the controller also controls the solar air supplement branch 3 to be communicated with the first communicating branch 4 and the second communicating branch 5, one part of the refrigerant passing through the solar heat collection device 32 supplements air to the second compressor 21 through the first communicating branch 4 and the air supplement port, the air supplement amount is increased, and one part of the refrigerant is converged with the refrigerant passing through the second heat exchanger 23 through the second communicating branch 5 and then returns to the second compressor 21 through the air inlet, so that the enthalpy difference of the low-pressure refrigerant circulation loop 2 is increased, and two-stage compression can be realized, and the heating capacity of the overlapping heat pump system is effectively improved.
Under the condition that the ambient temperature is greater than or equal to the preset ambient temperature and the illumination intensity is greater than or equal to the preset illumination intensity, the controller controls the bypass branch 6 and the fluorine pump 22 to operate and controls the second compressor 21 not to operate, so as to effectively reduce the operation energy consumption; in addition, the controller also controls the solar air supplement branch 3 to be communicated with the second communicating branch 5 and not communicated with the first communicating branch 4 so as to increase the enthalpy difference of the low-pressure refrigerant circulating loop 2, and the operation cost of the cascade heat pump system can be further reduced by the common operation mode of the solar air supplement branch 3 and the fluorine pump 22, and the operation energy efficiency can be improved.
It is understood that the specific operation modes of the cascade heat pump system of the present invention are not limited to the above four, and those skilled in the art can set the specific operation modes according to the actual situations.
So far, the technical solutions of the present invention have 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 the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.
Claims (10)
1. A cascade heat pump system is characterized in that the cascade heat pump system comprises a high-pressure refrigerant circulation loop, a low-pressure refrigerant circulation loop, a solar air supplement branch and a first communication branch,
the high-pressure refrigerant circulating loop is provided with a first compressor, a first heat exchanger, a first throttling component and an intermediate heat exchanger, the low-pressure refrigerant circulating loop is provided with a second compressor, the intermediate heat exchanger, a fluorine pump and a second heat exchanger, the two ends of the fluorine pump are connected in parallel with a second throttling component,
the solar air supplement branch is connected with the low-pressure refrigerant circulation loop, the first end of the solar air supplement branch is connected between the intermediate heat exchanger and the fluorine pump, the second end of the solar air supplement branch is connected with the first end of the first communication branch, a third throttling component and a solar heat collection device are arranged on the solar air supplement branch, and the second end of the first communication branch is connected to the air supplement opening of the second compressor.
2. The cascade heat pump system of claim 1, further comprising a second communication branch,
the first end of the second communication branch is connected to the joint of the solar air supplementing branch and the first communication branch, and the second end of the second communication branch is connected between the second heat exchanger and the air inlet of the second compressor.
3. The cascade heat pump system according to claim 2, wherein a first control valve is disposed on the first communication branch, and the first control valve is configured to control on/off states of the solar air supplement branch and the first communication branch; and/or
And a second control valve is arranged on the second communication branch, and the second control valve is set to control the on-off state of the solar air supplementing branch and the second communication branch.
4. The cascade heat pump system of claim 1, further comprising a bypass branch,
the bypass branches are arranged at two ends of the second compressor in parallel, third control valves are arranged on the bypass branches, and the third control valves are set to be capable of controlling the on-off states of the bypass branches.
5. The cascade heat pump system according to any one of claims 1 to 4, further comprising a heat exchange water circuit,
and a part of the heat exchange water path is arranged in the first heat exchanger, so that the water in the heat exchange water path exchanges heat with the refrigerant in the high-pressure refrigerant circulating loop through the first heat exchanger.
6. 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 low-pressure refrigerant circulation loop, a solar energy gas supplementing branch, a first communicating branch and a second communicating branch,
the high-pressure refrigerant circulating loop is provided with a first compressor, a first heat exchanger, a first throttling component and an intermediate heat exchanger, the low-pressure refrigerant circulating loop is provided with a second compressor, the intermediate heat exchanger, a fluorine pump and a second heat exchanger, the two ends of the fluorine pump are connected in parallel with a second throttling component,
the solar air supplement branch is connected with the low-pressure refrigerant circulation loop, the first end of the solar air supplement branch is connected between the intermediate heat exchanger and the fluorine pump, the second end of the solar air supplement branch is connected with the first end of the first communicating branch and the first end of the second communicating branch, a third throttling component and a solar heat collecting device are arranged on the solar air supplement branch, the second end of the first communicating branch is connected to an air supplement opening of the second compressor, the second end of the second communicating branch is connected between the second heat exchanger and an air inlet of the second compressor,
the control method comprises the following steps:
acquiring the illumination intensity at the solar heat collection device;
and controlling the communication state of the solar air supplementing branch and the first communication branch and the second communication branch according to the illumination intensity.
7. The control method according to claim 6, wherein the step of controlling the communication status of the solar energy gas supplementing branch with the first communication branch and the second communication branch according to the illumination intensity specifically comprises:
if the illumination intensity is smaller than the preset illumination intensity, controlling the solar energy air supplement branch to be not communicated with the first communicating branch and the second communicating branch;
if the illumination intensity is greater than or equal to the preset illumination intensity, further acquiring the ambient temperature of the cascade heat pump system;
and further controlling the communication state of the solar air supplementing branch and the first communication branch and the second communication branch according to the environment temperature.
8. The control method according to claim 7, wherein the step of controlling the communication state of the solar air supply branch with the first communication branch and the second communication branch according to the ambient temperature specifically comprises:
if the environmental temperature is lower than the preset environmental temperature, controlling the solar air supplement branch to be communicated with the first communicating branch and the second communicating branch;
and if the environment temperature is greater than or equal to the preset environment temperature, controlling the solar air supplementing branch to be communicated with the second communicating branch and not communicated with the first communicating branch.
9. The control method according to claim 6, wherein the cascade heat pump system further comprises a bypass branch, the bypass branch is connected to the low-pressure refrigerant circulation loop, the bypass branch is arranged at two ends of the second compressor in parallel, and the control method further comprises:
acquiring the ambient temperature of the cascade heat pump system;
and controlling the running states of the bypass branch, the fluorine pump and the second compressor according to the ambient temperature.
10. The control method according to claim 9, wherein the step of controlling the operating states of the bypass branch, the fluorine pump, and the second compressor according to the ambient temperature specifically comprises:
if the ambient temperature is lower than the preset ambient temperature, controlling the bypass branch and the fluorine pump not to operate, and controlling the second compressor to operate;
and if the ambient temperature is greater than or equal to the preset ambient temperature, controlling the bypass branch and the fluorine pump to operate, and controlling the second compressor not to operate.
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| CN202210760226.6A CN115164433A (en) | 2022-06-30 | 2022-06-30 | Cascade heat pump system and control method thereof |
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| CN202210760226.6A CN115164433A (en) | 2022-06-30 | 2022-06-30 | Cascade heat pump system and control method thereof |
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