CN111102758B - Multi-circulation system - Google Patents

Multi-circulation system Download PDF

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Publication number
CN111102758B
CN111102758B CN201911405678.7A CN201911405678A CN111102758B CN 111102758 B CN111102758 B CN 111102758B CN 201911405678 A CN201911405678 A CN 201911405678A CN 111102758 B CN111102758 B CN 111102758B
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China
Prior art keywords
interface
reversing valve
way reversing
valve
heat exchanger
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CN201911405678.7A
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CN111102758A (en
Inventor
杨永安
申杨
魏德立
黄成军
朱轶群
杜启含
王忠孝
刘长征
臧筑华
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Tianjin Cold Source Engineering Design Institute
TIANJIN XINGKONGJIAN Institute OF STRUCTURE TECHNOLOGY
Zhuhai Hong Kong Macau Engineering Design Tianjin Co ltd
Chuangyuan Yide Tianjin Group Co ltd
Original Assignee
Tianjin Cold Source Engineering Design Institute
TIANJIN XINGKONGJIAN Institute OF STRUCTURE TECHNOLOGY
Zhuhai Hong Kong Macau Engineering Design Tianjin Co ltd
Chuangyuan Yide Tianjin Group Co ltd
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • 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
    • 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
    • F25B1/00—Compression machines, plants or systems with non-reversible cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B13/00—Compression machines, plants or systems, with reversible cycle
    • 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
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F25B41/26—Disposition of valves, e.g. of on-off valves or flow control valves of fluid flow reversing 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
    • F25B41/30—Expansion means; Dispositions thereof
    • 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)
  • Fluid Mechanics (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)

Abstract

In the prior art, dual stage compression refrigeration systems are commonly employed when the compression ratio is greater than 12. The two-stage compression refrigerating unit can be driven by one motor, and can also be realized by multiple machine head matching. But the two modes are communicated with each other at high and low pressure, so that the oil return problem of the compressor is not easy to solve. In the two-stage compression refrigeration cycle, the compression process is divided into two stages, low-pressure working medium steam from an evaporator firstly enters a low-pressure compressor to be compressed to intermediate pressure, and then enters a high-pressure compressor to be compressed to condensing pressure through an intercooler, and is discharged into a condenser, so that the pressure ratio of each stage is moderate, the power consumption of the compressor can be reduced due to the intermediate cooling, and the reliability and the economy are improved. Aiming at the technical defects in the prior art, the invention provides a multi-cycle system capable of realizing single-stage compression refrigeration cycle, cascade refrigeration cycle under various load working conditions, single-stage compression heat pump cycle and cascade heat pump cycle under various load working conditions, thereby reducing energy consumption, operating cost and saving energy.

Description

Multi-circulation system
Technical Field
The invention relates to the technical field of refrigeration and heat pumps, in particular to a multi-circulation system capable of realizing single-stage compression circulation and cascade circulation under various load working conditions.
Background
A single stage compression refrigeration system is not suitable for use in a cryogenic refrigeration system having a compression ratio (ratio of discharge pressure to suction pressure) greater than 12, due to the limitation of the compressor suction-discharge compression ratio. In the prior art, dual stage compression refrigeration systems are commonly employed when the compression ratio is greater than 12. The two-stage compression refrigerating unit can be driven by one motor, and can also be realized by multiple machine head matching. But the two modes are communicated with each other at high and low pressure, so that the oil return problem of the compressor is not easy to solve. In the two-stage compression refrigeration cycle, the compression process is divided into two stages, low-pressure working medium steam from an evaporator firstly enters a low-pressure compressor to be compressed to intermediate pressure, and then enters a high-pressure compressor to be compressed to condensing pressure through an intercooler, and is discharged into a condenser, so that the pressure ratio of each stage is moderate, the power consumption of the compressor can be reduced due to the intermediate cooling, and the reliability and the economy are improved.
Overlapping refrigeration systems are also a good solution when lower temperature refrigeration is required. The heat absorbs heat through the working medium of the low-temperature-level refrigerating system, is transferred to a condensing evaporator connected with the low-temperature-level refrigerating system and the high-temperature-level refrigerating system, and is transferred to the environment by the working medium of the high-temperature-level refrigerating system. However, the traditional cascade refrigeration system is complex in system and control system, and system control under variable load working conditions is difficult to realize.
In winter, with the increase of environmental protection pressure, the country greatly promotes coal to change into electric products. The air source heat pump is widely used due to the characteristics of energy conservation and environmental protection. Is widely applied. However, single-stage compression cycle has high compression ratio, low system efficiency and limited application. The efficiency of the air source heat pump is improved and heating is realized at the outdoor temperature of minus 25 ℃, and a two-stage compression cycle can be adopted. However, when the two-stage compression is adopted to realize winter heat supply, if the system design is carried out according to the requirement of being capable of meeting the outdoor temperature heating load of minus 25 ℃, the cooling capacity of the system configuration is far greater than the cooling load of a building in summer, and more than half of units are idle in the system in summer operation, so that waste is formed.
The traditional cascade system is applied to various working conditions, and has the advantages of complex system structure, complex control system, high unit idle rate, high operation cost and large initial investment.
The traditional system consisting of three identical refrigeration modules is complex in structure, huge in unit, large in application number of heat exchangers, larger in heat exchange loss and larger in initial investment.
Disclosure of Invention
Aiming at the technical defects in the prior art, the invention provides a multi-cycle system capable of realizing single-stage compression refrigeration cycle, cascade refrigeration cycle under various load working conditions, single-stage compression heat pump cycle and cascade heat pump cycle under various load working conditions, thereby reducing energy consumption, operating cost and saving energy.
The technical scheme adopted for realizing the purpose of the invention is as follows:
the multi-circulation system is characterized by comprising a first circulation unit, a second circulation unit and a third circulation unit; the first circulating unit comprises a first compressor, a first four-way reversing valve, a first heat exchanger, a first throttle valve and a first circulating channel of a first functional heat exchanger, wherein the exhaust end of the first compressor is connected with a first interface of the first four-way reversing valve, the air suction end of the first compressor is connected with a third interface of the first four-way reversing valve, and a second interface of the first four-way reversing valve, the first heat exchanger, the first throttle valve, the first circulating channel of the first functional heat exchanger and a fourth interface of the first four-way reversing valve are sequentially connected;
The second circulation unit comprises a second compressor, a second heat exchanger, a second circulation channel of the first functional heat exchanger, a first flow channel of the second functional heat exchanger, a second throttle valve, a first two-way valve, a second two-way valve, a three-way reversing valve, a second four-way reversing valve and a fourth four-way reversing valve; the exhaust end of the second compressor is connected with a first interface of the second four-way reversing valve, a second interface of the second four-way reversing valve is connected with a first interface of the fourth four-way reversing valve, a second interface of the fourth four-way reversing valve is connected with a first interface of the second heat exchanger, a second interface of the second heat exchanger is respectively connected with a first interface of the first two-way valve and a first interface of the second throttle valve, a second interface of the first two-way valve is respectively connected with a first interface of the second two-way valve and a second interface of a second circulation channel of a first functional heat exchanger, a second interface of the second throttle valve is respectively connected with a second interface of the second two-way valve and a second interface of a first flow channel of the second functional heat exchanger, a first interface of the first flow channel of the second functional heat exchanger is respectively connected with a fourth interface of the second four-way valve and a first interface of the fourth four-way valve, a second interface of the fourth functional heat exchanger is respectively connected with a fourth interface of the fourth four-way valve, a second interface of the fourth four-way valve is respectively connected with a second interface of the four-way reversing valve, a third interface of the fourth three-way reversing valve is respectively connected with a fourth interface of the four-way reversing valve, and a third interface of the fourth three-way reversing valve is respectively connected with a fourth interface of the four-way reversing valve;
The third circulation unit comprises a third compressor, a third circulation channel of the first functional heat exchanger, a third throttle valve, a second flow channel of the second functional heat exchanger and a third four-way reversing valve; the exhaust end of the third compressor is connected with the first interface of the third four-way reversing valve, the air suction end of the third compressor is connected with the third interface of the third four-way reversing valve, and the second interface of the third four-way reversing valve, the third circulating channel of the first functional heat exchanger, the third throttle valve, the second flow channel of the second functional heat exchanger and the fourth interface of the third four-way reversing valve are sequentially connected; the first compressor is a low-power compressor, the second compressor is a medium-power compressor, and the third compressor is a high-power compressor.
The multi-circulation system is characterized in that the first functional heat exchanger comprises a shell, and the first circulation channel, the second circulation channel and the third circulation channel are respectively arranged in the shell along the length direction; the second functional heat exchanger comprises a shell, and the first flow channel and the second flow channel are respectively arranged in the shell along the length direction; and heat exchange working media are respectively arranged in the shell of the first functional heat exchanger and the shell of the second functional heat exchanger.
When the multi-cycle system is a single-stage compression refrigeration cycle, the second cycle unit is configured to: the first interface of the second four-way reversing valve is connected with the second interface, and the third interface of the second four-way reversing valve is connected with the fourth interface; the first interface of the fourth four-way reversing valve is connected with the second interface, and the third interface of the fourth four-way reversing valve is connected with the fourth interface; the first two-way valve and the second two-way valve are closed; the third interface of the three-way reversing valve is connected with the first interface; the exhaust end of the second compressor, the first interface and the second interface of the second four-way reversing valve, the first interface and the second interface of the fourth four-way reversing valve, the second heat exchanger, the second throttle valve, the first runner of the second functional heat exchanger, the third interface and the fourth interface of the second four-way reversing valve, the third interface and the first interface of the three-way reversing valve are sequentially connected back to the air suction end of the second compressor, so that a single-stage compression refrigeration cycle is formed.
When the multi-circulation system is a low-load refrigeration cycle, the first circulation unit is a high-temperature-stage compression refrigeration cycle, and the second circulation unit is a low-temperature-stage compression refrigeration cycle; in the first circulation unit: the first interface of the first four-way reversing valve is connected with the second interface, and the third interface of the first four-way reversing valve is connected with the fourth interface; the exhaust end of the first compressor, the first interface and the second interface of the first four-way reversing valve, the first heat exchanger, the first throttle valve, the first circulating channel of the first functional heat exchanger, the third interface and the fourth interface of the first four-way reversing valve are sequentially connected back to the air suction end of the first compressor, so that high-temperature-stage compression refrigeration cycle is completed; in the second circulation unit: the first interface of the second four-way reversing valve is connected with the second interface, and the third interface of the second four-way reversing valve is connected with the fourth interface; the first port of the fourth four-way reversing valve is connected with the fourth port, the second port of the fourth four-way reversing valve is connected with the third port, the first two-way valve is opened, the second two-way valve is closed, and the first port of the three-way reversing valve is connected with the third port; the exhaust end of the second compressor, the first interface and the second interface of the second four-way reversing valve, the first interface and the fourth interface of the fourth four-way reversing valve, the second circulation channel of the first functional heat exchanger, the first two-way valve, the second throttle valve, the first flow channel of the second functional heat exchanger, the fourth interface and the third interface of the second four-way reversing valve, the third interface and the first interface of the three-way reversing valve are sequentially connected back to the air suction end of the second compressor to complete low-temperature-stage compression refrigeration cycle; the first circulation channel of the first functional heat exchanger serving as an evaporator in the first circulation unit absorbs condensation heat released by the second circulation channel serving as a condenser in the second circulation unit.
When the multi-circulation system is a high-load refrigeration cycle, the second circulation unit is a high-temperature-stage compression refrigeration cycle, and the third circulation unit is a low-temperature-stage compression refrigeration cycle; in the second circulation unit: the first interface of the second four-way reversing valve is connected with the second interface, and the third interface of the second four-way reversing valve is connected with the fourth interface; the first interface of the fourth four-way reversing valve is connected with the second interface, and the third interface of the fourth four-way reversing valve is connected with the fourth interface; the second two-way valve is opened, the first two-way valve is closed, and the first interface of the three-way reversing valve is connected with the second interface; the exhaust end of the second compressor, the first interface and the second interface of the second four-way reversing valve, the first interface and the second interface of the fourth four-way reversing valve, the second heat exchanger, the second throttle valve, the second two-way valve, the second circulation channel of the first functional heat exchanger, the second interface and the first interface of the three-way reversing valve are sequentially connected back to the air suction end of the second compressor, so that high-temperature-stage compression refrigeration circulation is completed; in the third circulation unit: the first interface of the third four-way reversing valve is connected with the second interface, and the third interface of the third four-way reversing valve is connected with the fourth interface; the exhaust end of the third compressor, the third circulation channel of the first functional heat exchanger, the third throttle valve, the second flow channel of the second functional heat exchanger, the fourth interface of the third four-way reversing valve and the third interface are sequentially connected back to the air suction end of the third compressor to complete low-temperature-stage compression refrigeration cycle; the second circulation path of the first functional heat exchanger functioning as an evaporator in the second circulation unit absorbs condensation heat released from the third circulation path functioning as a condenser in the third circulation unit.
When the multi-circulation system is a single-stage compression heat pump circulation, the second circulation unit is as follows: the first port of the second four-way reversing valve is connected with the fourth port, the second port of the second four-way reversing valve is connected with the third port, the first port of the fourth four-way reversing valve is connected with the second port, the third port of the fourth four-way reversing valve is connected with the fourth port, the first two-way valve and the second two-way valve are closed, and the third port of the three-way reversing valve is connected with the first port; the exhaust end of the second compressor, the first interface and the fourth interface of the second four-way reversing valve, the first runner of the second functional heat exchanger, the second throttle valve, the second heat exchanger, the second interface and the first interface of the fourth four-way reversing valve, the second interface and the third interface of the second four-way reversing valve, the third interface and the first interface of the three-way reversing valve return to the air suction end of the second compressor, so that a single-stage compression heat pump cycle is formed.
When the multi-circulation system is a low-load cascade heat pump circulation, the first circulation unit is a low-temperature-level heat pump circulation, and the second circulation unit is a high-temperature-level heat pump circulation; in the first circulation unit: the first interface of the first four-way reversing valve is connected with the fourth interface, and the second interface of the first four-way reversing valve is connected with the third interface; the exhaust end of the first compressor, the first interface and the fourth interface of the first four-way reversing valve, the first circulating channel of the first functional heat exchanger, the first throttle valve, the first heat exchanger, the second interface and the third interface of the first four-way reversing valve are sequentially connected back to the air suction end of the first compressor, so that low-temperature-level heat pump circulation is completed;
In the second circulation unit: the first port of the second four-way reversing valve is connected with the fourth port, the second port of the second four-way reversing valve is connected with the third port, the first port of the fourth four-way reversing valve is connected with the fourth port, and the second port of the fourth four-way reversing valve is connected with the third port; the first two-way valve is opened, the second two-way valve is closed, and a first interface and a second interface of the three-way reversing valve are connected; the exhaust end of the second compressor, the first interface and the fourth interface of the second four-way reversing valve, the first runner of the second functional heat exchanger, the second throttle valve, the first two-way valve, the second circulating channel of the first functional heat exchanger, the second interface and the first interface of the three-way reversing valve are sequentially connected back to the air suction end of the second compressor, so that high-temperature-stage heat pump circulation is completed;
the second circulation path of the first functional heat exchanger functioning as an evaporator in the second circulation unit absorbs condensation heat released from the first circulation path functioning as a condenser in the first circulation unit.
When the multi-circulation system is a high-load heat pump circulation, the second circulation unit is a low-temperature-level heat pump circulation, and the third circulation unit is a high-temperature-level heat pump circulation; in the second circulation unit: the first port of the second four-way reversing valve is connected with the second port, the third port of the second four-way reversing valve is connected with the fourth port, the first port of the fourth four-way reversing valve is connected with the fourth port, the second port of the fourth four-way reversing valve is connected with the third port, the second two-way valve is opened, the first two-way valve is closed, and the first port of the three-way reversing valve is connected with the third port; the exhaust end of the second compressor, the first interface and the second interface of the second four-way reversing valve, the first interface and the fourth interface of the fourth four-way reversing valve, the second circulation channel of the first functional heat exchanger, the second two-way valve, the second throttle valve, the second heat exchanger, the second interface and the third interface of the fourth four-way reversing valve, the fourth interface and the third interface of the second four-way reversing valve, and the third interface and the first interface of the three-way reversing valve are sequentially connected back to the air suction end of the second compressor to complete low-temperature heat pump circulation; in the third circulation unit: the first interface of the third four-way reversing valve is connected with the fourth interface, and the second interface of the third four-way reversing valve is connected with the third interface; the exhaust end of the third compressor, the first interface and the fourth interface of the third four-way reversing valve, the second flow passage of the second functional heat exchanger, the third throttle valve, the third circulating passage of the first functional heat exchanger, and the second interface and the third interface of the third four-way reversing valve are sequentially connected back to the air suction end of the third compressor to complete high-temperature-stage heat pump circulation; the third circulation path of the first functional heat exchanger functioning as an evaporator in the third circulation unit absorbs condensation heat released from the second circulation path functioning as a condenser in the second circulation unit.
Compared with the prior art, the invention has the beneficial effects that:
1. the multi-circulation system can realize single-stage compression refrigeration circulation and cascade refrigeration circulation under a multi-load working condition during refrigeration, can realize single-stage compression heat pump circulation and the heat pump system of cascade circulation under the multi-load working condition during heating, can select the single-stage compression refrigeration circulation and the cascade refrigeration circulation according to the required evaporation temperature and the load, and can select the single-stage compression heat pump circulation and the cascade heat pump circulation according to the required condensation temperature and the load, and the system is flexible and has wide application range.
2. According to the multi-circulation system, the first circulation unit and the third circulation unit are fixed units, and only the second circulation unit is a variable unit, so that compared with a traditional system, the multi-circulation system is simple in structure, reduces the use amount of a system unit, reduces the energy consumption of the system, reduces the running cost, reduces the initial investment cost of the system, and reduces the idle rate of the unit.
3. The multi-circulation system provided by the invention has the advantages that the functional heat exchanger is a novel heat exchanger, and compared with the traditional evaporative condenser, the multi-circulation system has more heat exchange functions and better heat exchange performance. The use amount of the heat exchanger is reduced, the loss of heat exchange amount is reduced, and the heat exchange performance is improved.
4. The multi-circulation system is simple. The single-stage compression refrigeration cycle and the cascade refrigeration cycle can be selected according to the required evaporation temperature and the required load, and the single-stage compression heat pump cycle and the cascade heat pump cycle can be selected according to the required condensation temperature and the required load, namely, the efficient circulation mode is selected under different working conditions, so that the efficiency of the system is improved, the energy consumption of the system is reduced, and the cost of the system is saved.
5. The high-temperature-level system and the low-temperature-level system in the multi-circulation system are isolated, and the problem of uneven oil return when the two-stage compression circulation system is adopted is solved.
6. The traditional system consisting of three identical refrigeration modules has the advantages of complex structure, huge unit, large application quantity of heat exchangers and larger heat exchange loss.
Drawings
FIG. 1 is a schematic diagram of a multiple circulation system of the present invention;
FIG. 2 is a schematic diagram of a first functional heat exchanger;
FIG. 3 shows a schematic diagram of a second functional heat exchanger;
FIG. 4 is a schematic diagram of an interface of a three-way reversing valve;
FIG. 5 is a schematic diagram of an interface of a first four-way reversing valve;
FIG. 6 is a schematic diagram of an interface of a second four-way reversing valve;
FIG. 7 is a schematic diagram of an interface of a third four-way reversing valve;
fig. 8 is a schematic diagram of an interface of a fourth four-way reversing valve.
Detailed Description
The invention is further described below with reference to the drawings and specific examples.
The schematic diagram of the multi-circulation system of the invention is shown in fig. 1, and comprises a first circulation unit, a second circulation unit and a third circulation unit. The first circulation unit comprises a first compressor 1-1, a first four-way reversing valve 7-1, a first heat exchanger 2-1, a first throttle valve 5-1 and a first circulation channel 3-1-1 of a first functional heat exchanger 3-1, wherein the interface schematic diagram of the first four-way reversing valve is shown in fig. 5. The exhaust end of the first compressor 1-1 is connected with the first interface 7-1-1 of the first four-way reversing valve 7-1, the air suction end of the first compressor 1-1 is connected with the third interface 7-1-3 of the first four-way reversing valve 7-1, and the second interface 7-1-2 of the first four-way reversing valve 7-1, the first heat exchanger 2-1, the first throttle valve 5-1, the first circulation channel 3-1-1 of the first functional heat exchanger 3-1 and the fourth interface 7-1-4 of the first four-way reversing valve 7-1 are sequentially connected. The second circulation unit comprises a second compressor 1-2, a second heat exchanger 2-2, a second circulation channel 3-1-2 of the first functional heat exchanger 3-1, a first flow channel 3-2-1 of the second functional heat exchanger 3-2, a second throttle valve 5-2, a first two-way valve 6-1, a second two-way valve 6-2, a three-way reversing valve 4, a second four-way reversing valve 7-2 and a fourth four-way reversing valve 7-4, wherein the interface schematic diagram of the second four-way reversing valve 7-2 is shown in fig. 6, the interface schematic diagram of the fourth four-way reversing valve 7-4 is shown in fig. 7, and the interface schematic diagram of the three-way reversing valve 4 is shown in fig. 4. The exhaust end of the second compressor 1-2 is connected with a first interface 7-2-1 of the second four-way reversing valve 7-2, a second interface 7-2-2 of the second four-way reversing valve 7-2 is connected with a first interface 7-4-1 of the fourth four-way reversing valve 7-4, a second interface 7-4-2 of the fourth four-way reversing valve 7-4 is connected with a first interface of the second heat exchanger 2-2, a second interface of the second heat exchanger 2-2 is respectively connected with a first interface of the first two-way valve 6-1 and a first interface of the second throttle valve 5-2, a second interface of the first two-way valve 6-2 is respectively connected with a first interface of the second two-way valve 6-2 and a second interface of the second circulating channel 3-1-2 of the first functional heat exchanger 3-1, a second interface of the second throttle valve 5-2 is respectively connected with a second interface of the second two-way valve 7-2 and a second interface of the fourth functional heat exchanger 3-2, a second interface of the fourth throttle valve 5-2 is respectively connected with a second interface of the four-way reversing valve 7-2-4-2 and a first interface of the four-way reversing valve 3-2-4, a second interface of the four-way reversing valve 7-2-4 is respectively connected with a second interface of the fourth two-way reversing valve 7-2-4 and a first interface of the fourth functional heat exchanger 3-1-2-2, the first port 4-1 of the three-way reversing valve 4 is connected with the air suction end of the second compressor 1-2, and the first port of the second circulation channel 3-1-2 of the first functional heat exchanger 3-1 is respectively connected with the second port 4-2 of the three-way reversing valve 4 and the fourth port 7-4-4 of the fourth four-way reversing valve 7-4. The third circulation unit comprises a third compressor 1-3, a third circulation channel 3-1-3 of the first functional heat exchanger 3-1, a third throttle valve 5-3, a second flow channel 3-2-2 of the second functional heat exchanger 3-2 and a third four-way reversing valve 7-3, wherein the interface schematic diagram of the third four-way reversing valve 7-3 is shown in fig. 8. The exhaust end of the third compressor 1-3 is connected with the first interface 7-3-1 of the third four-way reversing valve 7-3, the suction end of the third compressor 1-3 is connected with the third interface 7-3-3 of the third four-way reversing valve 7-3, and the second interface 7-3-2 of the third four-way reversing valve 7-3, the third circulating channel 3-1-3 of the first functional heat exchanger 3-1, the third throttle valve 5-3, the second flow channel 3-2-2 of the second functional heat exchanger 3-2 and the fourth interface 7-3-4 of the third four-way reversing valve 7-3 are sequentially connected. The first compressor 1-1 is a low-power compressor, the second compressor 1-2 is a medium-power compressor, and the third compressor 1-3 is a high-power compressor.
In this embodiment, the schematic diagram of the first functional heat exchanger is shown in fig. 2, and includes a housing 3-1-4, where the first circulation channel 3-1-1, the second circulation channel 3-1-2, and the third circulation channel 3-1-3 are respectively disposed in the housing 3-1-4 along the length direction. The schematic diagram of the second functional heat exchanger is shown in fig. 3, and the second functional heat exchanger comprises a shell 3-2-3, wherein the first flow channel 3-2-1 and the second flow channel 3-2-2 are respectively arranged in the shell 3-2-3 along the length direction. Heat exchange working media are respectively arranged in the shell 3-1-4 of the first functional heat exchanger and the shell 3-2-3 of the second functional heat exchanger.
The multi-circulation system of the invention can realize single-stage compression circulation and cascade circulation under various load conditions. Under the condition of cooling in summer, the single-stage compression refrigeration cycle can be realized under the working condition that the single-stage compression refrigeration cycle can meet the requirements; when the single-stage compression refrigeration cycle cannot meet the required evaporation temperature, two cascade refrigeration cycles of a low-load working condition and a high-load working condition can be realized; under the condition of heating in winter, when the condensation temperature which can be met by the single-stage compression heat pump cycle is achieved, the single-stage compression heat pump system is achieved, and when the condensation temperature which can not be met by the single-stage compression heat pump cycle is achieved, the low-load cascade heat pump system and the high-load cascade heat pump system are achieved according to the required load.
When cooling in summer, the single-stage compression refrigeration cycle can be operated under the working condition that the single-stage compression refrigeration cycle can be met, and the multi-cycle system is the single-stage compression refrigeration cycle. In the second circulation unit: the first interface 7-2-1 of the second four-way reversing valve 7-2 is connected with the second interface 7-2-2, and the third interface 7-2-3 of the second four-way reversing valve 7-2 is connected with the fourth interface 7-2-4; the first port 7-4-1 of the fourth four-way reversing valve 7-4 is connected with the second port 7-4-2, and the third port 7-4-3 of the fourth four-way reversing valve 7-4 is connected with the fourth port 7-4-4; the first two-way valve 6-1 and the second two-way valve 6-2 are closed; the third port 4-3 of the three-way reversing valve 4 is connected with the first port 4-1. The exhaust end of the second compressor 1-2, the first interface 7-2-1 and the second interface 7-2-2 of the second four-way reversing valve 7-2, the first interface 7-4-1 and the second interface 7-4-2 of the fourth four-way reversing valve 7-4, the second heat exchanger 2-2, the second throttle valve 5-2, the first flow channel 3-2-1 of the second functional heat exchanger 3-2, the third interface 7-2-3 and the fourth interface 7-2-4 of the second four-way reversing valve 7-2, the third interface 4-3 and the first interface 4-1 of the three-way reversing valve 4 are sequentially connected back to the air suction end of the second compressor 1-2 to form a single-stage compression refrigeration cycle. The second compressor 1-2 sucks low-pressure gas from the first flow channel 3-2-1 of the second functional heat exchanger 3-2, the low-pressure gas is compressed and boosted by the second compressor 1-2 to become high-pressure gas, then the high-pressure gas is converted into low-pressure wet vapor through evaporation and absorption heat quantity of the first flow channel 3-2-1 and the second flow channel 7-2-2 of the second four-way reversing valve 7-2, the first flow channel 7-4-1 and the second flow channel 7-4-2 of the fourth four-way reversing valve 7-4 enter the second heat exchanger 2-2 to be condensed and released into high-pressure liquid, the high-pressure liquid is throttled and depressurized by the second throttle valve 5-2 to become low-pressure wet vapor, the low-pressure wet vapor enters the first flow channel 3-2-1 of the second functional heat exchanger 3-2 to be evaporated and absorbed into low-pressure vapor, cooling is realized, and the low-pressure wet vapor is returned to the refrigerating end of the second heat exchanger 2-1 through the fourth flow channel 7-2-4 and the third flow channel 7-4-3 of the second four-way reversing valve 7-2 and the third flow channel 7-4-2-3 and the third flow channel 4-2-2.
When the single-stage compression refrigeration cycle cannot meet the required evaporation temperature, the system can realize two different cascade refrigeration cycles according to different loads required, namely a low-load working condition cascade refrigeration cycle and a high-load working condition cascade refrigeration cycle.
Under the low-load working condition, the first circulation unit is a high-temperature-stage compression refrigeration cycle, the second circulation unit is a low-temperature-stage compression refrigeration cycle, and the multi-circulation system is a low-load refrigeration cycle. In the first circulation unit: the first port 7-1-1 of the first four-way reversing valve 7-1 is connected with the second port 7-1-2, and the third port 7-1-3 of the first four-way reversing valve 7-1 is connected with the fourth port 7-1-4. The exhaust end of the first compressor 1-1, the first interface 7-1-1 and the second interface 7-1-2 of the first four-way reversing valve 7-1, the first heat exchanger 2-1, the first throttle valve 5-1, the first circulating channel 3-1-1 of the first functional heat exchanger 3-1, the third interface 7-1-3 and the fourth interface 7-1-4 of the first four-way reversing valve 7-1 are sequentially connected back to the air suction end of the first compressor 1-1, so that high-temperature-stage compression refrigeration cycle is completed. In the second circulation unit: the first interface 7-2-1 of the second four-way reversing valve 7-2 is connected with the second interface 7-2-2, and the third interface 7-2-3 of the second four-way reversing valve 7-2 is connected with the fourth interface 7-2-4; the first port 7-4-1 of the fourth four-way reversing valve 7-4 is connected with the fourth port 7-4-4, the second port 7-4-2 of the fourth four-way reversing valve 7-4 is connected with the third port 7-4-3, the first two-way valve 6-1 is opened, the second two-way valve 6-2 is closed, and the first port 4-1 of the three-way reversing valve 4 is connected with the third port 4-3; the exhaust end of the second compressor 1-2, the first interface 7-2-1 and the second interface 7-2-2 of the second four-way reversing valve 7-2, the first interface 7-4-1 and the fourth interface 7-4-4 of the fourth four-way reversing valve 7-4, the second circulation channel 3-1-2 of the first functional heat exchanger 3-1, the first two-way valve 6-1, the second throttle valve 5-2, the first circulation channel 3-2-1 of the second functional heat exchanger 3-2, the fourth interface 7-2-4 and the third interface 7-2-3 of the second four-way reversing valve 7-2, the third interface 4-3 of the three-way reversing valve 4 and the first interface 4-1 are sequentially connected back to the air suction end of the second 1-2, so that the low-temperature stage compression refrigeration cycle is completed. In the high-temperature-stage compression refrigeration cycle, the first compressor 1-1 sucks medium-pressure gas from the first circulation channel 3-1-1 of the first functional heat exchanger 3-1, the medium-pressure gas is compressed into high-pressure gas through the first compressor 1-1, the high-pressure gas enters the first heat exchanger 2-1 through the first interface 7-1-1 and the second interface 7-1-2 of the first four-way reversing valve 7-1 to cool and release heat into high-pressure liquid, the high-pressure liquid is throttled and depressurized through the first throttle valve 5-1 to become medium-pressure wet steam, and then enters the first circulation channel 3-1-1 of the first functional heat exchanger 3-1 to evaporate, and the heat absorbed by low-temperature-stage condensation becomes medium-pressure gas and returns to the air suction end of the first compressor 1-1 through the fourth interface 7-1-4 and the third interface 7-1-3 of the first four-way reversing valve 7-1 to complete the high-temperature-stage compression refrigeration cycle. In the low-temperature-stage compression refrigeration cycle, the second compressor 1-2 sucks low-pressure gas from the first flow channel 3-2-1 of the second functional heat exchanger 3-2, the low-pressure gas is compressed into medium-pressure gas through the second compressor 1-2, the medium-pressure gas flows through the first flow channel 7-2-1 of the second four-way reversing valve 7-2, the second flow channel 7-2-2 and the first flow channel 7-4-1 of the fourth four-way reversing valve 7-4, the fourth flow channel 7-4-4 enters the second circulation channel 3-1-2 of the first functional heat exchanger 3-1 to be condensed, medium-pressure liquid is changed into medium-pressure liquid through the first two-way valve 6-1 to enter the second throttle valve 5-2 to be throttled and depressurized into low-pressure wet steam, the low-pressure wet steam is evaporated into low-pressure steam in the first flow channel 3-2-1 of the second functional heat exchanger 3-2 to generate low-pressure steam, and the low-pressure steam is compressed into the third flow channel 3-2-2 through the fourth flow channel 7-2-4-2 of the second four-way reversing valve 7-2, and the third flow channel 4-2-4-4 is compressed into the low-temperature-stage refrigeration stage through the third flow channel 3-2-4, and the third flow channel 4-2-4-side of the first functional heat exchanger 3-2-2. The first circulation path 3-1-1 of the first functional heat exchanger, which serves as an evaporator, of the first circulation unit absorbs condensation heat released from the second circulation path 3-1-2, which serves as a condenser, of the second circulation unit.
Under the high-load working condition, the second circulation unit is a high-temperature-stage compression refrigeration cycle, the third circulation unit is a low-temperature-stage compression refrigeration cycle, and the multi-circulation system is a high-load refrigeration cycle. In the second circulation unit: the first interface 7-2-1 of the second four-way reversing valve 7-2 is connected with the second interface 7-2-2, and the third interface 7-2-3 of the second four-way reversing valve 7-2 is connected with the fourth interface 7-2-4; the first port 7-4-1 of the fourth four-way reversing valve 7-4 is connected with the second port 7-4-2, and the third port 7-2-3 of the fourth four-way reversing valve 7-2 is connected with the fourth port 7-2-4; the second two-way valve 6-2 is opened, the first two-way valve 6-1 is closed, and the first port 4-1 of the three-way reversing valve 4 is connected with the second port 4-2. The exhaust end of the second compressor 1-2, the first interface 7-2-1 and the second interface 7-2-2 of the second four-way reversing valve, the first interface 7-4-1 and the second interface 7-4-2 of the fourth four-way reversing valve, the second heat exchanger 2-2, the second throttle valve 5-2, the second two-way valve 6-2, the second circulation channel 3-1-2 of the first functional heat exchanger 3-1, the second interface 4-2 and the first interface 4-1 of the three-way reversing valve 4 are sequentially connected back to the air suction end of the second compressor 1-2, so that high-temperature-level compression refrigeration circulation is completed. In the third circulation unit: the first port 7-3-1 of the third four-way reversing valve 7-3 is connected with the second port 7-3-2, and the third port 7-3-3 of the third four-way reversing valve 7-3 is connected with the fourth port 7-3-4; the exhaust end of the third compressor 1-3, the third circulation channel 3-1-3 of the first functional heat exchanger 3-1, the third throttle valve 5-3, the second flow channel 3-2-2 of the second functional heat exchanger 3-2, the fourth interface 7-3-4 and the third interface 7-3-3 of the third four-way reversing valve 7-3 are sequentially connected back to the air suction end of the third compressor 1-3, so that the low-temperature-stage compression refrigeration cycle is completed. In the high-temperature-stage compression refrigeration cycle, the second compressor 1-2 sucks medium-pressure gas from the second circulation channel 3-1-2 of the first functional heat exchanger 3-1, the medium-pressure gas is compressed into high-pressure gas through the second compressor 1-2, the high-pressure gas flows through the first interface 7-2-1, the second interface 7-2-2 and the first interface 7-4-1 of the fourth four-way reversing valve 7-2 and the second interface 7-4-2 of the fourth four-way reversing valve 7-4 to enter the second heat exchanger 2-2, heat is released into high-pressure liquid in a condensation way, the high-pressure liquid enters the second throttle valve 5-2 to be throttled and reduced into medium-pressure wet steam, the medium-pressure wet steam is evaporated in the second circulation channel 3-1-2 of the first functional heat exchanger 3-1 through the second two-way valve 6-2, the low-temperature-stage condensation heat is absorbed into medium-pressure gas, and then the medium-pressure gas is returned to the high-temperature-stage compressor through the second interface 4-2 and the first interface 4-1 of the three-way reversing valve 4-2 to complete the high-temperature-stage refrigeration cycle. In the low-temperature-stage compression refrigeration cycle, the third compressor 1-3 sucks low-pressure gas from the second flow channel 3-2-2 of the second functional heat exchanger 3-2, the low-pressure gas is compressed into medium-pressure gas through the third compressor 1-3, the medium-pressure gas enters the third circulation channel 3-1-3 of the first functional heat exchanger 3-1 through the first interface 7-3-1 and the second interface 7-3-2 of the third four-way reversing valve 7-3 to be condensed, the medium-pressure liquid is changed into medium-pressure liquid by heating to high Wen Jifang, the medium-pressure liquid is throttled and depressurized by the third throttle valve 5-3 to become low-pressure wet steam, and then enters the second flow channel 3-2-2 of the second functional heat exchanger 3-2 to be evaporated into low-pressure steam, refrigeration phenomenon is generated, and the low-pressure steam flows through the fourth interface 7-3-4 and the third interface 7-3-3 of the third four-way reversing valve 7-3 to return to the end of the third compressor 1-3, and the low-temperature-stage compression refrigeration cycle is completed. The second circulation path 3-1-2 of the first functional heat exchanger, which serves as an evaporator, of the second circulation unit absorbs condensation heat released from the third circulation path 3-1-3, which serves as a condenser, of the third circulation unit.
Under the heating condition in winter, when the condensing temperature which can be met by the single-stage compression heat pump cycle, only the second circulation unit circularly operates to realize the single-stage compression heat pump system, and the multi-circulation system is the single-stage compression heat pump cycle. In the second circulation unit: the first port 7-2-1 of the second four-way reversing valve 7-2 is connected with the fourth port 7-2-4, the second port 7-2-2 of the second four-way reversing valve 7-2 is connected with the third port 7-2-3, the first port 7-4-1 of the fourth four-way reversing valve 7-4 is connected with the second port 7-4-2, the third port 7-4-3 of the fourth four-way reversing valve 7-4 is connected with the fourth port 7-4-4, the first two-way valve 6-1 and the second two-way valve 6-2 are closed, and the third port 4-3 of the three-way reversing valve 4 is connected with the first port 4-1. The exhaust end of the second compressor 1-2, the first interface 7-2-1 and the fourth interface 7-1-4 of the second four-way reversing valve 7-2, the first flow channel 3-2-1 of the second functional heat exchanger 3-2, the second throttle valve 5-2, the second heat exchanger 2-2, the second interface 7-4-2 and the first interface 7-4-1 of the fourth four-way reversing valve 7-4, the second interface 7-2-2 and the third interface 7-2-3 of the second four-way reversing valve 7-2, and the third interface 4-3 and the first interface 4-1 of the three-way reversing valve 4 return to the air suction end of the second compressor 1-2 to form a single-stage compression heat pump cycle. The second compressor 1-2 sucks low-pressure gas from the second heat exchanger 2-2, the low-pressure gas is compressed and boosted by the second compressor 1-2 to be changed into high-pressure gas, then the high-pressure gas enters the first flow channel 3-2-1 of the second functional heat exchanger 3-2 through the first interface 7-2-1 and the fourth interface 7-2-4 of the second four-way reversing valve 7-2, the condensed and heat-released heat is changed into high-pressure liquid, the high-pressure liquid enters the second throttling valve 5-2 to be throttled and depressurized to become low-pressure wet vapor, the low-pressure wet vapor enters the second heat exchanger 2-2 to be evaporated and absorbed by the heat quantity to become low-pressure vapor, and the low-pressure vapor passes through the second interface 7-4-2 of the fourth four-way reversing valve 7-4, the first interface 7-4-1, the second interface 7-2-2 of the second four-way reversing valve 7-2, the third interface 7-2-3, the third interface 4-3 of the three-way reversing valve 4 and the first interface 4-1 back to the second compressor 1-2, and the single-stage compression air suction cycle is completed.
When the single-stage compression heat pump cycle cannot meet the required evaporation temperature, the system can realize two different cascade heat pump cycles according to different loads required, namely a low-load working condition cascade heat pump cycle and a high-load working condition cascade heat pump cycle.
Under the low-load working condition, the first circulation unit is a low-temperature-level heat pump circulation, the second circulation unit is a high-temperature-level heat pump circulation, and the multi-circulation system is a low-load cascade heat pump circulation. In the first circulation unit: the first interface 7-1-1 of the first four-way reversing valve 7-1 is connected with the fourth interface 7-1-4, and the second interface 7-1-2 of the first four-way reversing valve 7-1 is connected with the third interface 7-1-3. The exhaust end of the first compressor 1-1, the first interface 7-1-1 and the fourth interface 7-1-4 of the first four-way reversing valve 7-1, the first circulation channel 3-1-1 of the first functional heat exchanger 3-1, the first throttle valve 5-1, the first heat exchanger 2-1, the second interface 7-1-2 and the third interface 7-1-3 of the first four-way reversing valve 7-1 are sequentially connected back to the air intake end of the first compressor 1-1, so that low-temperature heat pump circulation is completed. In the second circulation unit: the first port 7-2-1 of the second four-way reversing valve 7-2 is connected with the fourth port 7-2-4, the second port 7-2-2 of the second four-way reversing valve 7-2 is connected with the third port 7-2-3, the first port 7-4-1 of the fourth four-way reversing valve 7-4 is connected with the fourth port 7-4-4, and the second port 7-4-2 of the fourth four-way reversing valve 7-4 is connected with the third port 7-4-3; the first two-way valve 6-1 is opened, the second two-way valve 6-2 is closed, and the first port 4-1 of the three-way reversing valve 4 is connected with the second port 4-2. The exhaust end of the second compressor 1-2, the first interface 7-2-1 and the fourth interface 7-2-4 of the second four-way reversing valve 7-2, the first flow channel 3-2-1 of the second functional heat exchanger 3-2, the second throttle valve 5-2, the first two-way valve 6-1, the second circulation channel 3-1-2 of the first functional heat exchanger 3-1, the second interface 4-2 and the first interface 4-1 of the three-way reversing valve 4 return to the air suction end of the second compressor 1-2, and high-temperature heat pump circulation is completed. In the high-temperature-stage circulation, the second compressor 1-2 sucks medium-pressure gas from the second circulation channel 3-1-2 of the first functional heat exchanger 3-1, the medium-pressure gas is compressed by the second compressor 1-2 to be changed into high-pressure gas, the high-pressure gas enters the first circulation channel 3-2-1 of the second functional heat exchanger 3-2 through the first interface 7-1-1 and the fourth interface 7-1-4 of the second four-way reversing valve 7-2 to condense and release heat to be high-pressure liquid, the high-pressure liquid enters the second throttling valve 5-2 to throttle and decompress to be changed into medium-pressure wet steam, the medium-pressure wet steam enters the second circulation channel 3-1-2 of the first functional heat exchanger 3-1 through the first two-way valve 6-1 to evaporate, and the condensed heat absorbed by the low-temperature stage is changed into medium-pressure gas and then returns to the air suction end of the second compressor 1-2 through the second interface 4-2 and the first interface 4-1 of the three-way reversing valve 4 to complete the high-temperature-stage circulation. In the low-temperature-stage circulation, the first compressor 1-1 sucks low-pressure gas from the first heat exchanger 2-1, the low-pressure gas is compressed into medium-pressure gas through the first compressor 1-1, the medium-pressure gas flows through the first interface 7-1-1 and the fourth interface 7-1-4 of the first four-way reversing valve 7-1, enters the first circulation channel 3-1 of the first functional heat exchanger 3-1 to be condensed, the medium-pressure liquid is subjected to high Wen Jifang heat change into medium-pressure liquid, the medium-pressure liquid is subjected to throttling and depressurization through the first throttle valve 5-1 to become low-pressure wet steam, the low-pressure wet steam is evaporated through the first heat exchanger 3-1 to become low-pressure steam, and the low-pressure steam is returned to the air suction end of the first compressor 1-1 through the second interface 7-2-2 and the third interface 7-2-3 of the first four-way reversing valve 7-1, so that the low-temperature-stage circulation is completed. The second circulation path 3-1-2 of the first functional heat exchanger, which serves as an evaporator, of the second circulation unit absorbs condensation heat released from the first circulation path 3-1-1, which serves as a condenser, of the first circulation unit.
Under the high-load working condition, the second circulation unit is a low-temperature-level heat pump circulation, the third circulation unit is a high-temperature-level heat pump circulation, and the multi-circulation system is a high-load heat pump circulation. In the second circulation unit: the first port 7-2-1 of the second four-way reversing valve 7-2 is connected with the second port 7-2-2, the third port 7-2-3 of the fourth four-way reversing valve 7-2 is connected with the fourth port 7-2-4, the first port 7-4-1 of the fourth four-way reversing valve 7-4 is connected with the fourth port 7-4-4, the second port 7-4-2 of the fourth four-way reversing valve 7-4 is connected with the third port 7-4-3, the second two-way valve 6-2 is opened, the first two-way valve 6-1 is closed, and the first port 4-1 of the three-way reversing valve 4 is connected with the third port 4-3. The second compressor 1-2, the first interface 7-2-1 and the second interface 7-2-2 of the second four-way reversing valve 7-2, the first interface 7-4-1 and the fourth interface 7-4-4 of the fourth four-way reversing valve 7-4, the second circulation channel 3-1-2 of the first functional heat exchanger 3-1, the second two-way valve 6-2, the second throttle valve 5-2, the second heat exchanger 2-2, the second interface 7-4-2 and the third interface 7-4-3 of the fourth four-way reversing valve 7-4, the fourth interface 7-2-4 and the third interface 7-2-3 of the second four-way reversing valve 7-2, and the third interface 4-3 and the first interface 4-1 of the three-way reversing valve 4 are sequentially connected back to the air suction end of the second compressor 1-2, thereby completing the low-temperature heat pump circulation. In the third circulation unit: the first port 7-3-1 of the third four-way reversing valve 7-3 is connected with the fourth port 7-3-4, and the second port 7-3-2 of the third four-way reversing valve 7-3 is connected with the third port 7-3-3; the exhaust end of the third compressor 1-3, the first interface 7-3-1 and the fourth interface 7-3-4 of the third four-way reversing valve 7-3, the second flow channel 3-2-2 of the second functional heat exchanger 3-2, the third throttle valve 5-3, the third circulation channel 3-1-3 of the first functional heat exchanger 3-1, the second interface 7-3-2 and the third interface 7-3-3 of the third four-way reversing valve 7-3 are sequentially connected back to the air suction end of the third compressor 1-3, so that high-temperature heat pump circulation is completed. In the high-temperature-stage circulation, the third compressor 1-3 sucks medium-pressure gas from the third circulation channel 3-1-3 of the first functional heat exchanger 3-1, the medium-pressure gas is compressed by the third compressor 1-3 to be changed into high-pressure gas, the high-pressure gas flows through the first interface 7-3-1 and the fourth interface 7-3-4 of the third four-way reversing valve 7-3 to enter the second flow channel 3-2-2 of the second functional heat exchanger 3-2 to condense and release heat into high-pressure liquid, heat supply is realized, the high-pressure liquid enters the third throttling valve 5-3 to throttle and decompress to be changed into medium-pressure wet steam, the medium-pressure wet steam enters the third circulation channel 3-1-3 of the first functional heat exchanger 3-1 to evaporate, and the condensed heat of the low-temperature stage is absorbed to be changed into medium-pressure gas, and then the medium-pressure gas flows back to the air suction end of the third compressor 1-3 through the second interface 7-3-2 and the third interface 7-3-3 of the third four-way reversing valve 7-3, and the high-temperature-stage circulation is completed. In the low-temperature-stage circulation, the second compressor 1-2 sucks low-pressure gas from the second heat exchanger 2-2, the low-pressure gas is compressed into medium-pressure gas through the second compressor 1-2, the medium-pressure gas is evaporated into low-pressure wet vapor through the first port 7-2-1, the second port 7-2-2 and the first port 7-4-1 of the fourth four-way reversing valve 4-2 of the second four-way reversing valve 7-2, the fourth port 7-4-4 enters the second circulation channel 3-1 of the first functional heat exchanger 3-1 to be condensed, the medium-pressure liquid is changed into medium-pressure liquid by heat to high Wen Jifang, the medium-pressure liquid enters the second throttling valve 5-2 through the second two-way valve 6-2 to be throttled and depressurized into low-pressure wet vapor, the low-pressure wet vapor enters the second heat exchanger 2-2 to be evaporated into low-pressure vapor, and the low-pressure vapor flows through the second port 7-4-2 of the fourth port 7-4, the third port 7-4-3, the fourth port 7-4-2, the fourth port 7-2-4-4 and the third port 4-2 to be completely sucked into the third port 4-2, and the third port 7-2-4-4, and the third port 4-2-4-side reversing valve and the third port is completely compressed. The third circulation path 3-1-3 of the first functional heat exchanger, which serves as an evaporator, of the third circulation unit absorbs condensation heat released from the second circulation path 3-1-2, which serves as a condenser, of the second circulation unit.
The first compressor 1-1, the second compressor 1-2 and the third compressor 1-3 are any one of a scroll compressor, a rotor compressor, a screw compressor and a piston compressor.
The first throttle valve 5-1, the second throttle valve 5-2 and the third throttle valve 5-3 are electronic expansion valves, thermal expansion valves, capillary tubes or orifice plate throttle devices.
The multi-circulation system can realize single-stage compression circulation and cascade circulation under various load working conditions. The single-stage compression refrigeration cycle can be realized at the evaporating temperature which can be met by the single-stage cycle; under the condition that the single-stage compression refrigeration cycle cannot meet the required evaporation temperature, two cascade refrigeration cycles of a low-load working condition and a high-load working condition are realized according to the required load; under the condition of a winter heat pump, when the single-stage circulation can meet the required condensation temperature, the single-stage compression heat pump circulation can be realized; under the condition that the single-stage compression heat pump cycle cannot meet the required condensation temperature, a low-load cascade heat pump system and a high-load cascade heat pump system are realized according to the required load; in the refrigerating system, the first circulating unit is a fixed unit, and is used as a high-temperature-stage cycle of the cascade refrigerating system under a low-load working condition, the third circulating unit is a fixed unit, and is used as a low-temperature-stage cycle of the cascade refrigerating system under a high-load working condition, only the second circulating unit is a change unit, and the second circulating unit can be used as a single-stage compression refrigerating cycle, a low-temperature-stage cycle of the cascade refrigerating system under the low-load working condition and a high-temperature-stage cycle of the cascade refrigerating system under the high-load working condition; in the heat pump system, the first circulation unit is a fixed unit, and is used as a low-temperature-stage circulation of the cascade heat pump system under a low-load working condition, the third circulation unit is a fixed unit, and is used as a high-temperature-stage circulation of the cascade heat pump system under a high-load working condition, only the second circulation unit is a change unit, and the second circulation unit can be used as a single-stage compression heat pump circulation, a high-temperature-stage circulation of the cascade heat pump system under the low-load working condition and a low-temperature-stage circulation of the cascade heat pump system under the high-load working condition. The system capable of realizing single-stage compression circulation and cascade circulation under various load working conditions can realize single-stage compression refrigeration circulation, various cascade refrigeration circulation, single-stage compression heat pump circulation and various cascade heat pump circulation, and adopts a high-efficiency circulation mode under various load working conditions, the first circulation unit and the third circulation unit are fixed units, and only the second circulation unit is a variable unit, so that the efficiency of the system is improved, the energy consumption of the system is reduced, and the cost of the system is saved.
The foregoing is merely a preferred embodiment of the invention, and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (8)

1. The multi-circulation system is characterized by comprising a first circulation unit, a second circulation unit and a third circulation unit; the first circulating unit comprises a first compressor, a first four-way reversing valve, a first heat exchanger, a first throttle valve and a first circulating channel of a first functional heat exchanger, wherein the exhaust end of the first compressor is connected with a first interface of the first four-way reversing valve, the air suction end of the first compressor is connected with a third interface of the first four-way reversing valve, and a second interface of the first four-way reversing valve, the first heat exchanger, the first throttle valve, the first circulating channel of the first functional heat exchanger and a fourth interface of the first four-way reversing valve are sequentially connected;
the second circulation unit comprises a second compressor, a second heat exchanger, a second circulation channel of the first functional heat exchanger, a first flow channel of the second functional heat exchanger, a second throttle valve, a first two-way valve, a second two-way valve, a three-way reversing valve, a second four-way reversing valve and a fourth four-way reversing valve; the exhaust end of the second compressor is connected with a first interface of the second four-way reversing valve, a second interface of the second four-way reversing valve is connected with a first interface of the fourth four-way reversing valve, a second interface of the fourth four-way reversing valve is connected with a first interface of the second heat exchanger, a second interface of the second heat exchanger is respectively connected with a first interface of the first two-way valve and a first interface of the second throttle valve, a second interface of the first two-way valve is respectively connected with a first interface of the second two-way valve and a second interface of a second circulation channel of a first functional heat exchanger, a second interface of the second throttle valve is respectively connected with a second interface of the second two-way valve and a second interface of a first flow channel of the second functional heat exchanger, a first interface of the first flow channel of the second functional heat exchanger is respectively connected with a fourth interface of the second four-way valve and a first interface of the fourth four-way valve, a second interface of the fourth functional heat exchanger is respectively connected with a fourth interface of the fourth four-way valve, a second interface of the fourth four-way valve is respectively connected with a second interface of the four-way reversing valve, a third interface of the fourth three-way reversing valve is respectively connected with a fourth interface of the four-way reversing valve, and a third interface of the fourth three-way reversing valve is respectively connected with a fourth interface of the four-way reversing valve;
The third circulation unit comprises a third compressor, a third circulation channel of the first functional heat exchanger, a third throttle valve, a second flow channel of the second functional heat exchanger and a third four-way reversing valve; the exhaust end of the third compressor is connected with the first interface of the third four-way reversing valve, the air suction end of the third compressor is connected with the third interface of the third four-way reversing valve, and the second interface of the third four-way reversing valve, the third circulating channel of the first functional heat exchanger, the third throttle valve, the second flow channel of the second functional heat exchanger and the fourth interface of the third four-way reversing valve are sequentially connected; the first compressor is a low-power compressor, the second compressor is a medium-power compressor, and the third compressor is a high-power compressor.
2. The multiple circulation system according to claim 1, wherein the first functional heat exchanger includes a housing in which the first, second, and third circulation passages are provided in a length direction, respectively; the second functional heat exchanger comprises a shell, and the first flow channel and the second flow channel are respectively arranged in the shell along the length direction; and heat exchange working media are respectively arranged in the shell of the first functional heat exchanger and the shell of the second functional heat exchanger.
3. The multiple circulation system according to claim 1, wherein when the multiple circulation system is a single-stage compression refrigeration cycle, the second circulation unit: the first interface of the second four-way reversing valve is connected with the second interface, and the third interface of the second four-way reversing valve is connected with the fourth interface; the first interface of the fourth four-way reversing valve is connected with the second interface, and the third interface of the fourth four-way reversing valve is connected with the fourth interface; the first two-way valve and the second two-way valve are closed; the third interface of the three-way reversing valve is connected with the first interface; the exhaust end of the second compressor, the first interface and the second interface of the second four-way reversing valve, the first interface and the second interface of the fourth four-way reversing valve, the second heat exchanger, the second throttle valve, the first runner of the second functional heat exchanger, the third interface and the fourth interface of the second four-way reversing valve, the third interface and the first interface of the three-way reversing valve are sequentially connected back to the air suction end of the second compressor, so that a single-stage compression refrigeration cycle is formed.
4. The multiple circulation system according to claim 1, wherein when the multiple circulation system is a low load refrigeration cycle, the first circulation unit is a high temperature stage compression refrigeration cycle, and the second circulation unit is a low temperature stage compression refrigeration cycle; in the first circulation unit: the first interface of the first four-way reversing valve is connected with the second interface, and the third interface of the first four-way reversing valve is connected with the fourth interface; the exhaust end of the first compressor, the first interface and the second interface of the first four-way reversing valve, the first heat exchanger, the first throttle valve, the first circulating channel of the first functional heat exchanger, the third interface and the fourth interface of the first four-way reversing valve are sequentially connected back to the air suction end of the first compressor, so that high-temperature-stage compression refrigeration cycle is completed; in the second circulation unit: the first interface of the second four-way reversing valve is connected with the second interface, and the third interface of the second four-way reversing valve is connected with the fourth interface; the first port of the fourth four-way reversing valve is connected with the fourth port, the second port of the fourth four-way reversing valve is connected with the third port, the first two-way valve is opened, the second two-way valve is closed, and the first port of the three-way reversing valve is connected with the third port; the exhaust end of the second compressor, the first interface and the second interface of the second four-way reversing valve, the first interface and the fourth interface of the fourth four-way reversing valve, the second circulation channel of the first functional heat exchanger, the first two-way valve, the second throttle valve, the first flow channel of the second functional heat exchanger, the fourth interface and the third interface of the second four-way reversing valve, the third interface and the first interface of the three-way reversing valve are sequentially connected back to the air suction end of the second compressor to complete low-temperature-stage compression refrigeration cycle; the first circulation channel of the first functional heat exchanger serving as an evaporator in the first circulation unit absorbs condensation heat released by the second circulation channel serving as a condenser in the second circulation unit.
5. The multiple circulation system according to claim 1, wherein when the multiple circulation system is a high-load refrigeration cycle, the second circulation unit is a high-temperature-stage compression refrigeration cycle, and the third circulation unit is a low-temperature-stage compression refrigeration cycle; in the second circulation unit: the first interface of the second four-way reversing valve is connected with the second interface, and the third interface of the second four-way reversing valve is connected with the fourth interface; the first interface of the fourth four-way reversing valve is connected with the second interface, and the third interface of the fourth four-way reversing valve is connected with the fourth interface; the second two-way valve is opened, the first two-way valve is closed, and the first interface of the three-way reversing valve is connected with the second interface; the exhaust end of the second compressor, the first interface and the second interface of the second four-way reversing valve, the first interface and the second interface of the fourth four-way reversing valve, the second heat exchanger, the second throttle valve, the second two-way valve, the second circulation channel of the first functional heat exchanger, the second interface and the first interface of the three-way reversing valve are sequentially connected back to the air suction end of the second compressor, so that high-temperature-stage compression refrigeration circulation is completed; in the third circulation unit: the first interface of the third four-way reversing valve is connected with the second interface, and the third interface of the third four-way reversing valve is connected with the fourth interface; the exhaust end of the third compressor, the third circulation channel of the first functional heat exchanger, the third throttle valve, the second flow channel of the second functional heat exchanger, the fourth interface of the third four-way reversing valve and the third interface are sequentially connected back to the air suction end of the third compressor to complete low-temperature-stage compression refrigeration cycle; the second circulation path of the first functional heat exchanger functioning as an evaporator in the second circulation unit absorbs condensation heat released from the third circulation path functioning as a condenser in the third circulation unit.
6. The multiple circulation system according to claim 1, wherein when the multiple circulation system is a single-stage compression heat pump cycle, the second circulation unit: the first port of the second four-way reversing valve is connected with the fourth port, the second port of the second four-way reversing valve is connected with the third port, the first port of the fourth four-way reversing valve is connected with the second port, the third port of the fourth four-way reversing valve is connected with the fourth port, the first two-way valve and the second two-way valve are closed, and the third port of the three-way reversing valve is connected with the first port; the exhaust end of the second compressor, the first interface and the fourth interface of the second four-way reversing valve, the first runner of the second functional heat exchanger, the second throttle valve, the second heat exchanger, the second interface and the first interface of the fourth four-way reversing valve, the second interface and the third interface of the second four-way reversing valve, the third interface and the first interface of the three-way reversing valve return to the air suction end of the second compressor, so that a single-stage compression heat pump cycle is formed.
7. The multiple circulation system of claim 1, wherein when the multiple circulation system is a low load cascade heat pump cycle, the first circulation unit is a low temperature stage heat pump cycle and the second circulation unit is a high temperature stage heat pump cycle; in the first circulation unit: the first interface of the first four-way reversing valve is connected with the fourth interface, and the second interface of the first four-way reversing valve is connected with the third interface; the exhaust end of the first compressor, the first interface and the fourth interface of the first four-way reversing valve, the first circulating channel of the first functional heat exchanger, the first throttle valve, the first heat exchanger, the second interface and the third interface of the first four-way reversing valve are sequentially connected back to the air suction end of the first compressor, so that low-temperature-level heat pump circulation is completed;
In the second circulation unit: the first port of the second four-way reversing valve is connected with the fourth port, the second port of the second four-way reversing valve is connected with the third port, the first port of the fourth four-way reversing valve is connected with the fourth port, and the second port of the fourth four-way reversing valve is connected with the third port; the first two-way valve is opened, the second two-way valve is closed, and a first interface and a second interface of the three-way reversing valve are connected; the exhaust end of the second compressor, the first interface and the fourth interface of the second four-way reversing valve, the first runner of the second functional heat exchanger, the second throttle valve, the first two-way valve, the second circulating channel of the first functional heat exchanger, the second interface and the first interface of the three-way reversing valve are sequentially connected back to the air suction end of the second compressor, so that high-temperature-stage heat pump circulation is completed;
the second circulation path of the first functional heat exchanger functioning as an evaporator in the second circulation unit absorbs condensation heat released from the first circulation path functioning as a condenser in the first circulation unit.
8. The multiple circulation system according to claim 1, wherein when the multiple circulation system is a high-load heat pump cycle, the second circulation unit is a low-temperature-stage heat pump cycle, and the third circulation unit is a high-temperature-stage heat pump cycle; in the second circulation unit: the first port of the second four-way reversing valve is connected with the second port, the third port of the second four-way reversing valve is connected with the fourth port, the first port of the fourth four-way reversing valve is connected with the fourth port, the second port of the fourth four-way reversing valve is connected with the third port, the second two-way valve is opened, the first two-way valve is closed, and the first port of the three-way reversing valve is connected with the third port; the exhaust end of the second compressor, the first interface and the second interface of the second four-way reversing valve, the first interface and the fourth interface of the fourth four-way reversing valve, the second circulation channel of the first functional heat exchanger, the second two-way valve, the second throttle valve, the second heat exchanger, the second interface and the third interface of the fourth four-way reversing valve, the fourth interface and the third interface of the second four-way reversing valve, and the third interface and the first interface of the three-way reversing valve are sequentially connected back to the air suction end of the second compressor to complete low-temperature heat pump circulation; in the third circulation unit: the first interface of the third four-way reversing valve is connected with the fourth interface, and the second interface of the third four-way reversing valve is connected with the third interface; the exhaust end of the third compressor, the first interface and the fourth interface of the third four-way reversing valve, the second flow passage of the second functional heat exchanger, the third throttle valve, the third circulating passage of the first functional heat exchanger, and the second interface and the third interface of the third four-way reversing valve are sequentially connected back to the air suction end of the third compressor to complete high-temperature-stage heat pump circulation; the third circulation path of the first functional heat exchanger functioning as an evaporator in the third circulation unit absorbs condensation heat released from the second circulation path functioning as a condenser in the second circulation unit.
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