WO2021138861A1

WO2021138861A1 - Multi-cycle system

Info

Publication number: WO2021138861A1
Application number: PCT/CN2020/071062
Authority: WO
Inventors: 杨永安; 臧筑华; 王忠孝; 申杨; 魏德立; 刘长征; 朱轶群; 杜启含; 黄成军
Original assignee: 创远亿德(天津)集团有限公司; 天津冷源工程设计院; 天津博聚缘轻工日化鉴定科学研究院; 杨永安; 珠港澳工程设计(天津)有限公司; 臧筑华; 王忠孝; 申杨; 魏德立; 刘长征; 朱轶群; 杜启含; 黄成军
Priority date: 2020-01-09
Filing date: 2020-01-09
Publication date: 2021-07-15

Abstract

Disclosed is a multi-cycle system, comprising a first cycle unit, a second cycle unit and a third cycle unit. The multi-cycle system can realize a single-stage compression refrigeration cycle, a cascaded refrigeration cycle under various load working conditions, a single-stage compression heat pump cycle and a cascaded heat pump cycle under various load working conditions.

Description

A multi-circulation system

Technical field

The invention relates to the technical field of refrigeration and heat pumps, and more specifically, to a multi-cycle system that can realize both a single-stage compression cycle and a cascade cycle under various load conditions.

Background technique

The single-stage compression refrigeration system is limited by the compressor suction and discharge compression ratio, so it is not suitable for low temperature refrigeration systems with a compression ratio (the ratio of discharge pressure to suction pressure) greater than 12. In the prior art, when the compression ratio is greater than 12, a two-stage compression refrigeration system is usually used. The two-stage compression refrigeration unit can be driven by a motor, or it can be realized by multi-head configuration. However, the high and low pressure communication of these two methods makes it difficult to solve the oil return problem of the compressor. In a two-stage compression refrigeration cycle, the compression process is divided into two stages. The low-pressure working fluid vapor from the evaporator first enters the low-pressure compressor and is compressed to intermediate pressure, then enters the high-pressure compressor through the intercooler and is compressed to condensing pressure, and then discharged into the condenser. In this way, the pressure ratio at all levels can be moderate. Due to the intermediate cooling, the compressor can reduce the power consumption and improve the reliability and economy. However, this kind of refrigeration system is complicated and the control system is complicated, and it is difficult to achieve variable load conditions. Under system control.

When lower temperature refrigeration is required, a cascade refrigeration system is also a good solution. The heat absorbs heat through the working fluid of the low-temperature refrigeration system, and is transferred to the condensing evaporator connecting the low-temperature refrigeration system and the high-temperature refrigeration system, and then the high-temperature refrigeration system transfers the heat to the environment. However, this traditional cascade refrigeration system has complex systems and complex control systems, and it is difficult to achieve system control under variable load conditions.

In winter, as the pressure on environmental protection increases, the state vigorously promotes coal-to-electricity products. Air source heat pumps have been widely used due to their energy-saving and environmentally-friendly characteristics. It is widely used. However, the single-stage compression cycle has a high compression ratio and low system efficiency, and its application is subject to certain restrictions. To improve the efficiency of the air source heat pump and realize heating at an outdoor temperature of -25°C, a two-stage compression cycle can be used. However, when two-stage compression is used to achieve winter heating, if the system is designed to meet the heating load of -25℃ outdoor temperature, the cooling capacity of the system configuration in summer cooling is much greater than the cooling load of the building. More than half of the units in the system will be idle during operation, resulting in waste.

The traditional cascade system is used in a variety of working conditions, the system structure is complicated, the control system is complicated, the unit idle rate is high, the operating cost is high, and the initial investment is large.

The traditional system composed of three identical refrigeration modules has a complex structure, a huge unit, a large number of heat exchangers, a large heat exchange loss, and a large initial investment.

Summary of the invention

The purpose of the present invention is to provide a single-stage compression refrigeration cycle, a cascade refrigeration cycle under multiple load conditions, a single-stage compression heat pump cycle, and multiple load conditions in view of the technical defects existing in the prior art. The multi-circulation system of the lower cascade heat pump cycle reduces energy consumption, lowers operating costs, and saves energy.

The technical solutions adopted to achieve the purpose of the present invention are:

A multi-cycle system, characterized in that it includes a first circulation unit, a second circulation unit, and a third circulation unit; the first circulation unit includes a first compressor, a first four-way reversing valve, and a first heat exchange unit. The first circulation channel of the first functional heat exchanger, the first throttle valve and the first functional heat exchanger, the discharge end of the first compressor is connected to the first interface of the first four-way reversing valve, and the first The suction end of the compressor is connected to the third port of the first four-way reversing valve, the second port of the first four-way reversing valve, the first heat exchanger, the first throttle valve, The first circulation channel of the first functional heat exchanger and the fourth interface of the first four-way reversing valve are connected in sequence;

The second circulation unit includes 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 Valve, second two-way valve, three-way reversing valve, second four-way reversing valve, and fourth four-way reversing valve; the discharge end of the second compressor and the second four-way reversing valve The first port of the valve is connected, the second port of the second four-way reversing valve is connected to the first port of the fourth four-way reversing valve, and the second port of the fourth four-way reversing valve is connected to The first interface of the second heat exchanger is connected, and the second interface of the second heat exchanger is respectively connected to the first interface of the first two-way valve and the first interface of the second throttle valve , The second interface of the first two-way valve is respectively connected with the first interface of the second two-way valve and the second interface of the second circulation channel of the first functional heat exchanger, and the second throttle valve The second interface is respectively connected with the second interface of the second two-way valve and the second interface of the first flow channel of the second functional heat exchanger, and the second interface of the first flow channel of the second functional heat exchanger One interface is respectively connected to the fourth interface of the second four-way reversing valve and the third interface of the fourth four-way reversing valve, and the third interface of the second four-way reversing valve is connected to the third interface of the fourth four-way reversing valve. The third port of the three-way reversing valve is connected, the first port of the three-way reversing valve is connected to the suction end of the second compressor, and the first port of the second circulation channel of the first functional heat exchanger is connected. The interface is respectively connected with the second interface of the three-way reversing valve and the fourth interface of the fourth four-way reversing valve;

The third circulation unit includes a third compressor, a third circulation passage of the first functional heat exchanger, a third throttle valve, a second flow passage of the second functional heat exchanger, and a third four-way reversal Valve; the discharge end of the third compressor is connected to the first interface of the third four-way reversing valve, and the suction end of the third compressor is connected to the first port of the third four-way reversing valve Three-port connection, the second port of the third four-way reversing valve, the third circulation channel of the first functional heat exchanger, the third throttle valve, and the second port of the second functional heat exchanger The two flow passages and the fourth port of the third four-way reversing valve are connected in sequence; the first compressor is a low-power compressor, the second compressor is a medium-power compressor, and the third compressor It is a high-power compressor.

The multi-circulation system is characterized in that the first functional heat exchanger includes a shell, and the first circulation channel, the second circulation channel, and the third circulation channel are respectively provided in the shell along the length direction; The second functional heat exchanger includes a shell, in which the first flow channel and the second flow channel are respectively arranged along the length direction; the shell of the first functional heat exchanger and the second functional heat exchanger Heat exchange working fluids are respectively arranged in the shell of the heat exchanger.

When the multi-cycle system is a single-stage compression refrigeration cycle, in the second cycle unit: the first port of the second four-way reversing valve is connected to the second port, and the second four-way reversing valve is The third interface is connected to the fourth interface; the first interface of the fourth four-way reversing valve is connected to the second interface, and the third interface of the fourth four-way reversing valve is connected to the fourth interface; the first two The two-way valve and the second two-way valve are closed; the third port of the three-way reversing valve is connected to the first port; the discharge end of the second compressor and the first port of the second four-way reversing valve And the second interface, the first interface and the second interface of the fourth four-way reversing valve, the second heat exchanger, the second throttle valve, the first flow passage of the second functional heat exchanger , The third port and the fourth port of the second four-way reversing valve, the third port and the first port of the three-way reversing valve are sequentially connected back to the suction end of the second compressor to form a single stage Compression refrigeration cycle.

When the multi-cycle system is a low-load refrigeration cycle, the first cycle unit is a high-temperature compression refrigeration cycle, and the second cycle unit is a low-temperature compression refrigeration cycle; in the first cycle unit: the first The first port of the four-way reversing valve is connected to the second port, the third port of the first four-way reversing valve is connected to the fourth port; the discharge end of the first compressor, the first four-way reversing valve The first interface and the second interface of the directional valve, the first heat exchanger, the first throttle valve, the first circulation channel of the first functional heat exchanger, and the first four-way reversing valve The third interface and the fourth interface are sequentially connected back to the suction end of the first compressor to complete the high-temperature compression refrigeration cycle; in the second circulation unit: the first interface of the second four-way reversing valve Connected to the second interface, the third interface of the second four-way reversing valve is connected to the fourth interface; the first interface of the fourth four-way reversing valve is connected to the fourth interface, the fourth four-way The second port of the reversing valve is connected to the third port, the first two-way valve is open, the second two-way valve is closed, and the first port of the three-way reversing valve is connected to the third port; The discharge 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, and the first functional changeover The second circulation channel of the heat exchanger, the first two-way valve, the second throttle valve, the first flow channel of the second functional heat exchanger, the fourth interface of the second four-way reversing valve and the third The interface, the third interface and the first interface of the three-way reversing valve are sequentially connected back to the suction end of the second compressor to complete the cryogenic compression refrigeration cycle; the evaporator in the first cycle unit The first circulation passage of the first functional heat exchanger absorbs condensation heat released by the second circulation passage as a condenser in the second circulation unit.

When the multi-cycle system is a high-load refrigeration cycle, the second cycle unit is a high-temperature compression refrigeration cycle, and the third cycle unit is a low-temperature compression refrigeration cycle; in the second cycle unit: the second four-way commutation The first port of the valve is connected to the second port, the third port of the second four-way reversing valve is connected to the fourth port; the first port of the fourth four-way reversing valve is connected to the second port, so The third port of the fourth four-way reversing valve is connected to the fourth 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 to the second port; The discharge 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 The 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 connected in sequence Return to the suction end of the second compressor to complete the high-temperature compression refrigeration cycle; in the third cycle unit: the first interface of the third four-way reversing valve is connected to the second interface, and the first The third port of the three-to-four-way reversing valve is connected to the fourth port; the exhaust end of the third compressor, the third circulation channel of the first functional heat exchanger, the third throttle valve, and the The second flow channel of the second functional heat exchanger, the fourth interface and the third interface of the third four-way reversing valve are sequentially connected back to the suction end of the third compressor to complete low-temperature compression refrigeration Circulation; the second circulation passage of the first functional heat exchanger as an evaporator in the second circulation unit absorbs condensation heat released by the third circulation passage as a condenser in the third circulation unit.

When the multi-circulation system is a single-stage compression heat pump cycle, in the second circulation unit: the first port of the second four-way reversing valve is connected to the fourth port, and the second four-way reversing valve is connected to the The second port is connected to the third port, the first port of the fourth four-way reversing valve is connected to the second port, the third port of the fourth four-way reversing valve is connected to the fourth port, the first two The two-way valve and the second two-way valve are closed, the third port of the three-way reversing valve is connected to the first port; the discharge end of the second compressor, the first of the second four-way reversing valve Interface and the fourth interface, the first flow passage 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 port and the third port of the second four-way reversing valve, and the third port and the first port of the three-way reversing valve return to the suction end of the second compressor to form a single-stage compression heat pump cycle.

When the multi-cycle system is a low-load cascade heat pump cycle, the first cycle unit is a low-temperature heat pump cycle, and the second cycle unit is a high-temperature heat pump cycle; in the first cycle unit: the first The first port of a four-way reversing valve is connected to the fourth port, and the second port of the first four-way reversing valve is connected to the third port; the discharge end of the first compressor, the first port The first interface and the fourth interface of the four-way reversing valve, the first circulation channel of the first functional heat exchanger, the first throttle valve, the first heat exchanger, the first four-way The second interface and the third interface of the reversing valve are sequentially connected back to the suction end of the first compressor to complete the low-temperature heat pump cycle;

In the second circulation unit: the first port of the second four-way reversing valve is connected to the fourth port, the second port of the second four-way reversing valve is connected to the third port, and the fourth port is connected to the third port. The first port of the four-way reversing valve is connected to the fourth port, and the second port of the fourth four-way reversing valve is connected to the third port; the first two-way valve is opened, and the second two-way valve is Closed, the first port of the three-way reversing valve is connected to the second port; the discharge end of the second compressor, the first port and the fourth port of the second four-way reversing valve, the second port The first flow passage of the functional heat exchanger, the second throttle valve, the first two-way valve, the second circulation channel of the first functional heat exchanger, and the second interface of the three-way reversing valve Connect with the first interface in turn and return to the suction end of the second compressor to complete the high-temperature heat pump cycle;

The second circulation passage of the first functional heat exchanger as an evaporator in the second circulation unit absorbs condensation heat released by the first circulation passage as a condenser in the first circulation unit.

When the multi-cycle system is a high-load heat pump cycle, the second cycle unit is a low-temperature heat pump cycle, and the third cycle unit is a high-temperature heat pump cycle; in the second cycle unit: the second four-way The first port of the reversing valve is connected to the second port, the third port of the second four-way reversing valve is connected to the fourth port, and the first port of the fourth four-way reversing valve is connected to the fourth port , The second port of the fourth four-way reversing valve is connected to 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 to The third port is connected; the discharge end of the second compressor, the first port and the second port of the second four-way reversing valve, the first port and the fourth port of the fourth four-way reversing valve Interface, the second circulation channel of the first functional heat exchanger, the second two-way valve, the second throttle valve, the second heat exchanger, the fourth four-way reversing valve The second interface and the third interface, 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 second compression The suction end of the engine completes the low-temperature heat pump cycle; in the third cycle unit: the first interface of the third four-way reversing valve is connected to the fourth interface, and the third four-way reversing valve is connected to the fourth interface. The second interface 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, and the second flow passage of the second functional heat exchanger , The third throttle valve, the third circulation channel of the first functional heat exchanger, the second interface and the third interface of the third four-way reversing valve are sequentially connected back to the third compressor The suction end of the heat pump completes the high-temperature heat pump cycle; the third circulation channel of the first functional heat exchanger as the evaporator in the third circulation unit absorbs the second circulation as the condenser in the second circulation unit Condensation heat released by the channel.

Compared with the prior art, the beneficial effects of the present invention are:

1. The multi-cycle system of the present invention can realize both a single-stage compression refrigeration cycle and a cascade refrigeration cycle under multi-load conditions during refrigeration, and can realize both a single-stage compression heat pump cycle and a multi-load operation during heating. In the case of the cascade cycle heat pump system, single-stage compression refrigeration cycle and cascade refrigeration cycle can be selected according to the required evaporation temperature and load size, and single-stage compression heat pump cycle and cascade refrigeration cycle can be selected according to the required condensation temperature and load size. Type heat pump circulation, the system is flexible, and the scope of application is wide.

2. In the multi-circulation system of the present invention, the first circulation unit and the third circulation unit are fixed units, and only the second circulation unit is a variable unit. Compared with the traditional system, the structure is simple, and the usage of the system unit is reduced. It reduces the energy consumption of the system, reduces the operating cost, reduces the initial investment cost of the system, and reduces the idle rate of the unit.

3. In the multi-circulation system of the present invention, the functional heat exchanger is a new type of heat exchanger, which has more heat exchange functions and better heat exchange performance than traditional evaporative condensers. The use of heat exchangers is reduced, the loss of heat exchange is reduced, and the heat exchange performance is improved.

4. The multi-circulation system of the present invention is simple. The single-stage compression refrigeration cycle and the cascade refrigeration cycle can be selected according to the required evaporating temperature and the size of the load, and the single-stage compression heat pump cycle and the cascade heat pump cycle can be selected according to the required condensing temperature and load size, that is, in different working conditions The efficient circulation method is selected to improve the efficiency of the system, reduce the energy consumption of the system, and save the cost of the system.

5. The high temperature level system and the low temperature level system in the multi-cycle system of the present invention are isolated, which solves the problem of uneven oil return that occurs when a two-stage compression cycle system is adopted.

6. The traditional system composed of three identical refrigeration modules has a complex structure, a large unit, a large number of heat exchangers, and a large heat exchange loss. The multi-cycle system of the present invention can reduce the number of heat exchangers and reduce the number of units. The volume not only simplifies the control system of the system, but also reduces the energy consumption of the system.

Description of the drawings

Figure 1 shows the principle diagram of the multi-circulation system of the present invention;

Figure 2 shows the principle diagram of the first functional heat exchanger;

Figure 3 shows the principle diagram of the second functional heat exchanger;

Figure 4 shows a schematic diagram of the interface of the three-way reversing valve;

Figure 5 shows a schematic diagram of the interface of the first four-way reversing valve;

Figure 6 shows a schematic diagram of the interface of the second four-way reversing valve;

Figure 7 shows a schematic diagram of the interface of the third four-way reversing valve;

Figure 8 shows a schematic diagram of the interface of the fourth four-way reversing valve.

Detailed ways

The present invention will be further described below with reference to the drawings and specific embodiments.

The principle diagram of the multi-circulation system of the present invention is shown in Fig. 1, and includes a first circulation unit, a second circulation unit, and a third circulation unit. The first circulation unit includes 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 functional heat exchanger The first circulation channel 3-1-1 of 3-1, wherein the schematic diagram of the interface of the first four-way reversing valve is shown in FIG. 5. The discharge end of the first compressor 1-1 is connected to the first port 7-1-1 of the first four-way reversing valve 7-1, and the suction end of the first compressor 1-1 Connected to the third port 7-1-3 of the first four-way reversing valve 7-1, the second port 7-1-2 of the first four-way reversing valve 7-1, the first The 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 port of the first four-way reversing valve 7-1 7-1-4 are connected in sequence. The second circulation unit includes 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, and a second functional heat exchanger 3-2 the first flow path 3-2-1, the second throttle valve 5-2, the first two-way valve 6-1, the second two-way valve 6-2, the three-way reversing valve 4, the second four The second four-way reversing valve 7-2 and the fourth four-way reversing valve 7-4 are shown in Fig. 6. The fourth four-way reversing valve 7-4 The schematic diagram of the interface is shown in Figure 7, and the schematic diagram of the three-way reversing valve 4 is shown in Figure 4. The discharge end of the second compressor 1-2 is connected to the first interface 7-2-1 of the second four-way reversing valve 7-2, and the second four-way reversing valve 7-2 The second interface 7-2-2 is connected to the first interface 7-4-1 of the fourth four-way reversing valve 7-4, and the second interface 7- of the fourth four-way reversing valve 7-4 4-2 is connected to the first interface of the second heat exchanger 2-2, and the second interface of the second heat exchanger 2-2 is respectively connected to the first interface of the first two-way valve 6-1 Is connected to the first port of the second throttle valve 5-2, and the second port of the first two-way valve 6-2 is connected to the first port and the first port of the second two-way valve 6-2, respectively. The second interface of the second circulation channel 3-1-2 of the functional heat exchanger 3-1 is connected, and the second interface of the second throttle valve 5-2 is connected to the second interface of the second two-way valve 6-2. The second interface is connected to the second interface of the first flow channel 3-2-1 of the second functional heat exchanger 3-2, and the first flow channel 3-2-1 of the second functional heat exchanger 3-2 The first interface is respectively connected with the fourth interface 7-2-4 of the second four-way reversing valve 7-2 and the third interface 7-4-3 of the fourth four-way reversing valve 7-4 , The third port 7-2-3 of the second four-way reversing valve 7-2 is connected to the third port 4-3 of the three-way reversing valve 4, and the third port of the three-way reversing valve 4 An interface 4-1 is connected to the suction end of the second compressor 1-2, and the first interface of the second circulation channel 3-1-2 of the first functional heat exchanger 3-1 is respectively connected to the 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 are connected. The third circulation unit includes a third compressor 1-3, a third circulation passage 3-1-3 of the first functional heat exchanger 3-1, a third throttle valve 5-3, and a second functional heat exchanger 3-1. The second flow passage 3-2-2 and the third four-way reversing valve 7-3 of the heat exchanger 3-2, wherein the interface diagram of the third four-way reversing valve 7-3 is shown in FIG. 8. The discharge end of the third compressor 1-3 is connected to the first port 7-3-1 of the third four-way reversing valve 7-3, and the suction end of the third compressor 1-3 Connected to the third port 7-3-3 of the third four-way reversing valve 7-3, the second port 7-3-2 of the third four-way reversing valve 7-3, the first The third circulation passage 3-1-3 of the functional heat exchanger 3-1, the third throttle valve 5-3, and the second flow passage 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 connected in sequence. 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 principle diagram of the first functional heat exchanger is shown in Fig. 2, and includes a housing 3-1-4. The first functional heat exchanger is provided with the first functional heat exchanger along the length direction in the housing 3-1-4. A circulation channel 3-1-1, a second circulation channel 3-1-2, and a third circulation channel 3-1-3. The principle diagram of the second functional heat exchanger is shown in FIG. 3, and includes a housing 3-2-3, and the first flow channels 3-2-1 are respectively provided in the housing 3-2-3 along the length direction. And the second runner 3-2-2. The shell 3-1-4 of the first functional heat exchanger and the shell 3-2-3 of the second functional heat exchanger are respectively provided with heat exchange working fluids.

The multi-cycle system of the present invention can realize both a single-stage compression cycle and a cascade cycle under multiple load conditions. In the case of summer cooling, a single-stage compression refrigeration cycle can be realized under the working conditions that the single-stage compression refrigeration cycle can meet; when the single-stage compression refrigeration cycle cannot meet the required evaporation temperature, it can achieve low-load working conditions and high Two cascade refrigeration cycles under load conditions; in the case of winter heating, when the single-stage compression heat pump cycle can meet the condensing temperature, a single-stage compression heat pump system is realized, and when the single-stage compression heat pump cycle cannot meet the required condensing temperature , According to the size of the required load, a low-load cascade heat pump system and a high-load cascade heat pump system can be realized.

When cooling in summer, when the single-stage compression refrigeration cycle can meet the working conditions, only the second circulation unit circulates, and the multi-cycle system is a single-stage compression refrigeration cycle. In the second circulation unit: the first port 7-2-1 of the second four-way reversing valve 7-2 is connected to the second port 7-2-2, and the second four-way reversing valve 7 The third interface 7-2-3 of -2 is connected to the fourth interface 7-2-4; the first interface 7-4-1 and the second interface 7-4 of the fourth four-way reversing valve 7-4 -2 connection, the third interface 7-4-3 of the fourth four-way reversing valve 7-4 is connected to the fourth interface 7-4-4; the first two-way valve 6-1 and the second two-way valve 6-2 is closed; the third port 4-3 of the three-way reversing valve 4 is connected to the first port 4-1. The discharge end of the second compressor 1-2, the first port 7-2-1 and the second port 7-2-2 of the second four-way reversing valve 7-2, the fourth port The first port 7-4-1 and the second port 7-4-2 of the two-way reversing valve 7-4, the second heat exchanger 2-2, the second throttle valve 5-2, the The first flow passage 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 port 4-3 and the first port 4-1 of the three-way reversing valve 4 are sequentially connected back to the 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 passage 3-2-1 of the second functional heat exchanger 3-2, and the low-pressure gas is compressed and boosted by the second compressor 1-2 to become high-pressure After the gas passes through the first port 7-2-1 and the second port 7-2-2 of the second four-way reversing valve 7-2, the first port of the fourth four-way reversing valve 7-4 7-4-1 and the second interface 7-4-2 enter the second heat exchanger 2-2 to condense and release heat to become a high-pressure liquid, and the high-pressure liquid is throttled and reduced by the second throttle valve 5-2 The pressure becomes low-pressure wet steam, and the low-pressure wet steam enters the first flow path 3-2-1 of the second functional heat exchanger 3-2 to evaporate and absorb heat to become low-pressure steam to realize cooling. The low-pressure steam passes through the second four-way The fourth port 7-2-4 and the third port 7-2-3 of the reversing valve 7-2, the third port 4-3 and the first port 4-1 of the three-way reversing valve 4 return to the first The suction side of the second compressor 1-2 completes a single-stage compression refrigeration cycle.

When the single-stage compression refrigeration cycle cannot meet the required evaporating temperature, the system can realize two different cascade refrigeration cycles according to the different loads required, which are the cascade refrigeration cycle under low load conditions and the cascade refrigeration cycle under high load conditions. Stacked refrigeration cycle.

Under low-load conditions, the first cycle unit is a high-temperature compression refrigeration cycle, the second cycle unit is a low-temperature compression refrigeration cycle, and the multi-cycle 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 to the second port 7-1-2, and the first four-way reversing valve 7 The third interface 7-1-3 of -1 is connected to the fourth interface 7-1-4. The exhaust end of the first compressor 1-1, the first port 7-1-1 and the second port 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, the first four-way reversing valve 7-1 The third interface 7-1-3 and the fourth interface 7-1-4 are sequentially connected back to the suction end of the first compressor 1-1 to complete the high-temperature compression refrigeration cycle. In the second circulation unit: the first port 7-2-1 of the second four-way reversing valve 7-2 is connected to the second port 7-2-2, and the second four-way reversing valve 7 -2 The third interface 7-2-3 is connected to the fourth interface 7-2-4; the first interface 7-4-1 and the fourth interface 7-4 of the fourth four-way reversing valve 7-4 -4 connection, the second port 7-4-2 of the fourth four-way reversing valve 7-4 is connected to the third port 7-4-3, the first two-way valve 6-1 is opened, and the The second two-way valve 6-2 is closed, the first port 4-1 of the three-way reversing valve 4 is connected to the third port 4-3; the discharge end of the second compressor 1-2, the The first port 7-2-1 and the second port 7-2-2 of the second four-way reversing valve 7-2 and the first port 7-4-1 of the fourth four-way reversing valve 7-4 With the fourth interface 7-4-4, 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 flow passage 3-2-1 of the second functional heat exchanger 3-2, the fourth interface 7-2-4 and the third interface 7- of the second four-way reversing valve 7-2 2-3. The third port 4-3 and the first port 4-1 of the three-way reversing valve 4 are sequentially connected back to the suction end of the second 1-2 to complete the cryogenic compression refrigeration cycle. In the high-temperature compression refrigeration cycle, the first compressor 1-1 sucks in medium-pressure gas from the first circulation passage 3-1-1 of the first functional heat exchanger 3-1, and the medium-pressure gas passes through the The first compressor 1-1 is compressed into high-pressure gas, and the high-pressure gas enters the first port 7-1-1 and the second port 7-1-2 of the first four-way reversing valve 7-1. A heat exchanger 2-1 condenses and releases heat into a high-pressure liquid, and the high-pressure liquid is throttled and pressure-reduced by the first throttle valve 5-1 to become medium-pressure wet steam and then enters the first functional heat exchanger 3- 1 evaporates in the first circulation channel 3-1-1, absorbs the condensation heat of the low-temperature stage and turns it into a medium-pressure gas after passing through the fourth port 7-1-4 of the first four-way reversing valve 7-1, The three ports 7-1-3 return to the suction end of the first compressor 1-1 to complete the high-temperature compression refrigeration cycle. In the low-temperature compression refrigeration cycle, the second compressor 1-2 sucks low-pressure gas from the first flow path 3-2-1 of the second functional heat exchanger 3-2, and the low-pressure gas is compressed by the second The machine 1-2 is compressed into medium-pressure gas, and the medium-pressure gas flows through the first port 7-2-1, the second port 7-2-2, and the fourth four-way valve 7-2 of the second four-way reversing valve 7-2. The first port 7-4-1 and the fourth port 7-4-4 of the reversing valve 7-4 enter the second circulation channel 3-1-2 of the first functional heat exchanger 3-1 to condense. The high-temperature stage heats up and becomes a medium-pressure liquid, and the medium-pressure liquid enters the second throttle valve 5-2 through the first two-way valve 6-1, throttling and reducing the pressure to become low-pressure wet steam, and the low-pressure wet steam enters the whole The first flow passage 3-2-1 of the second functional heat exchanger 3-2 evaporates into low-pressure steam, which produces a refrigeration phenomenon. The low-pressure steam passes through the fourth port 7 of the second four-way reversing valve 7-2. -2-4, the third interface 7-2-3, the third interface 4-3 of the three-way reversing valve 4, and the first interface 4-1 return to the suction end of the second compressor 1-2, Complete the cryogenic compression refrigeration cycle. The first circulation passage 3-1-1 of the first functional heat exchanger as an evaporator in the first circulation unit absorbs the second circulation passage 3-1-2 as a condenser in the second circulation unit Heat of condensation released.

Under high load conditions, the second cycle unit is a high-temperature compression refrigeration cycle, the third cycle unit is a low-temperature compression refrigeration cycle, and the multi-cycle system is a high-load refrigeration cycle. In the second circulation unit: the first port 7-2-1 of the second four-way reversing valve 7-2 is connected to the second port 7-2-2, and the second four-way reversing valve 7 The third interface 7-2-3 of -2 is connected to the fourth interface 7-2-4; the first interface 7-4-1 and the second interface 7-4 of the fourth four-way reversing valve 7-4 -2 connection, the third port 7-2-3 of the fourth four-way reversing valve 7-2 is connected to the fourth port 7-2-4; the second two-way valve 6-2 is opened, the first two-way The valve 6-1 is closed, and the first port 4-1 of the three-way reversing valve 4 is connected to the second port 4-2. The discharge 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, and the fourth four-way reversing valve The first port 7-4-1 and the second port 7-4-2 of the 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 port 4-2 and the first port 4-1 of the three-way reversing valve 4 are connected back in turn To the suction end of the second compressor 1-2, the high-temperature stage compression refrigeration cycle is completed. In the third circulation unit: the first port 7-3-1 of the third four-way reversing valve 7-3 is connected to the second port 7-3-2, and the third four-way reversing valve 7 -3 third interface 7-3-3 is connected to the fourth interface 7-3-4; the exhaust end of the third compressor 1-3, the third interface of the first functional heat exchanger 3-1 Circulation channel 3-1-3, the third throttle valve 5-3, the second flow passage 3-2-2 of the second functional heat exchanger 3-2, the third four-way reversing valve The fourth interface 7-3-4 and the third interface 7-3-3 of 7-3 are sequentially connected back to the suction end of the third compressor 1-3 to complete the low-temperature compression refrigeration cycle. In the high-temperature 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, and the medium-pressure gas passes through the The second compressor 1-2 is compressed into high-pressure gas, and the high-pressure gas flows through the first port 7-2-1, the second port 7-2-2, and the fourth four-way valve of the second four-way reversing valve 7-2 The first port 7-4-1 and the second port 7-4-2 of the reversing valve 7-4 enter the second heat exchanger 2-2 to condense and release heat into high-pressure liquid, and the high-pressure liquid enters the second heat exchanger 2-2. The throttle valve 5-2 throttles and reduces the pressure to become medium-pressure wet steam, and the medium-pressure wet steam enters the second circulation channel 3 of the first functional heat exchanger 3-1 through the second two-way valve 6-2 -Evaporate in 1-2, absorb the condensation heat of the low-temperature stage and turn it into a medium-pressure gas, and then return to the second compressor through the second port 4-2 and the first port 4-1 of the three-way reversing valve 4 The suction side of 1-2 completes the high-temperature compression refrigeration cycle. In the low-temperature compression refrigeration cycle, the third compressor 1-3 sucks low-pressure gas from the second flow passage 3-2-2 of the second functional heat exchanger 3-2, and the low-pressure gas passes through the third Compressors 1-3 are compressed into medium-pressure gas, and the medium-pressure gas enters the first port 7-3-1 and the second port 7-3-2 of the third four-way reversing valve 7-3. Condensation in the third circulation channel 3-1-3 of the functional heat exchanger 3-1, heats up to the high-temperature stage and becomes a medium-pressure liquid. The medium-pressure liquid is throttled and pressure-reduced by the third throttle valve 5-3. The low-pressure wet steam enters the second flow passage 3-2-2 of the second functional heat exchanger 3-2 and evaporates into low-pressure steam, causing a refrigeration phenomenon. The low-pressure steam flows through the third four-way reversal The fourth port 7-3-4 and the third port 7-3-3 of the valve 7-3 return to the suction end of the third compressor 1-3 to complete the low-temperature compression refrigeration cycle. The second circulation passage 3-1-2 of the first functional heat exchanger as an evaporator in the second circulation unit absorbs the third circulation passage 3-1-3 as a condenser in the third circulation unit Heat of condensation released.

In the case of winter heating, when the single-stage compression heat pump cycle can meet the condensing temperature, only the second circulation unit circulates to realize a single-stage compression heat pump system, and the multi-circulation system is a 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 to the fourth port 7-2-4, and the second four-way reversing valve 7 The second interface 7-2-2 of -2 is connected to the third interface 7-2-3, and the first interface 7-4-1 and the second interface 7-4 of the fourth four-way reversing valve 7-4 -2 connection, the third interface 7-4-3 of the fourth four-way reversing valve 7-4 is connected to the fourth interface 7-4-4, the first two-way valve 6-1 and the second two-way valve 6-2 is closed, and the third port 4-3 of the three-way reversing valve 4 is connected to the first port 4-1. The discharge 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 second function The first runner 3-2-1, the second throttle valve 5-2, the second heat exchanger 2-2, the fourth four-way reversing valve 7-4 of the heat exchanger 3-2 The second interface 7-4-2 and the first interface 7-4-1, the second interface 7-2-2 and the third interface 7-2-3 of the second four-way reversing valve 7-2, three-way The third port 4-3 and the first port 4-1 of the reversing valve 4 return to the 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, and the low-pressure gas is compressed and boosted by the second compressor 1-2 to become high-pressure gas and then exchanged by the second four-way The first port 7-2-1 and the fourth port 7-2-4 of the valve 7-2 enter the first flow path 3-2-1 of the second functional heat exchanger 3-2 to release heat from condensation and become High-pressure liquid, high-pressure liquid enters the second throttle valve 5-2 to throttle and reduce pressure to become low-pressure wet steam, low-pressure wet steam enters the second heat exchanger 2-2 to evaporate and absorb heat to become low-pressure steam, and low-pressure steam passes through all The second port 7-4-2 of the fourth four-way reversing valve 7-4, the first port 7-4-1, and the second port 7-2-2 of the second four-way reversing valve 7-2 The third port 7-2-3, the third port 4-3 of the three-way reversing valve 4, and the first port 4-1 return to the suction end of the second compressor 1-2 to complete the winter single-stage compression heat pump cycle .

When the single-stage compression heat pump cycle cannot meet the required evaporating temperature, the system can realize two different cascade heat pump cycles according to the different loads required. They are the cascade heat pump cycle under low load conditions and the high load conditions. Stacked heat pump cycle.

Under low-load conditions, the first circulation unit is a low-temperature heat pump cycle, the second circulation unit is a high-temperature heat pump cycle, and the multi-circulation system is a low-load cascade heat pump cycle. In the first circulation unit: the first port 7-1-1 of the first four-way reversing valve 7-1 is connected to the fourth port 7-1-4, and the first four-way reversing valve 7 The second interface 7-1-2 of -1 is connected to the third interface 7-1-3. The discharge end of the first compressor 1-1, the first port 7-1-1 and the fourth port 7-1-4 of the first four-way reversing valve 7-1, the first function The first circulation channel 3-1-1 of the heat exchanger 3-1, the first throttle valve 5-1, the first heat exchanger 2-1, and the first four-way reversing valve 7- The second interface 7-1-2 and the third interface 7-1-3 of 1 are sequentially connected back to the suction end of the first compressor 1-1 to complete the low-temperature 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 to the fourth port 7-2-4, and the second four-way reversing valve 7 The second interface 7-2-2 of -2 is connected to the third interface 7-2-3, and the first interface 7-4-1 and the fourth interface 7-4 of the fourth four-way reversing valve 7-4 -4 connection, the second port 7-4-2 of the fourth four-way reversing valve 7-4 is connected to the third port 7-4-3; the first two-way valve 6-1 is opened, the second two-way The valve 6-2 is closed, and the first port 4-1 of the three-way reversing valve 4 is connected to the second port 4-2. The discharge 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 second function heat exchange The first flow path 3-2-1 of the device 3-2, the second throttle valve 5-2, the first two-way valve 6-1, the second functional heat exchanger 3-1 The circulation channel 3-1-2, the second port 4-2 and the first port 4-1 of the three-way reversing valve 4 return to the suction end of the second compressor 1-2 to complete the high-temperature heat pump cycle. In the high-temperature stage 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, and the medium-pressure gas passes through the second The compressor 1-2 is compressed into high-pressure gas, and the high-pressure gas enters the second function through the first port 7-1-1 and the fourth port 7-1-4 of the second four-way reversing valve 7-2 The first flow passage 3-2-1 of the heat exchanger 3-2 condenses and releases heat into a high-pressure liquid, and the high-pressure liquid enters the second throttle valve 5-2 to throttle and reduce pressure to become medium-pressure wet steam. The 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, absorbs the condensation heat of the low-temperature stage and turns it into a medium-pressure gas. The second port 4-2 and the first port 4-1 of the three-way reversing valve 4 return to the suction end of the second compressor 1-2 to complete the high-temperature stage cycle. In the low-temperature stage cycle, the first compressor 1-1 sucks low-pressure gas from the first heat exchanger 2-1, and the low-pressure gas is compressed by the first compressor 1-1 into a medium-pressure gas. The pressurized gas flows through the first port 7-1-1 and the fourth port 7-1-4 of the first four-way reversing valve 7-1 into the first cycle of the first functional heat exchanger 3-1 Condensation in the channel 3-1-1, heat release to the high-temperature stage becomes a medium-pressure liquid, the medium-pressure liquid is throttled and pressure-reduced by the first throttle valve 5-1 to become low-pressure wet steam, and the low-pressure wet steam passes through the The first heat exchanger 3-1 evaporates into low-pressure steam, and the low-pressure steam returns to the office through the second port 7-2-2 and the third port 7-2-3 of the first four-way reversing valve 7-1. The suction end of the first compressor 1-1 completes the low-temperature stage cycle. The second circulation passage 3-1-2 of the first functional heat exchanger as an evaporator in the second circulation unit absorbs the first circulation passage 3-1-1 as a condenser in the first circulation unit Heat of condensation released.

Under high load conditions, the second circulation unit is a low-temperature heat pump cycle, the third circulation unit is a high-temperature heat pump cycle, and the multi-circulation system is a high-load 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 to the second port 7-2-2, and the fourth four-way reversing valve 7 The third interface 7-2-3 of -2 is connected to the fourth interface 7-2-4, and the first interface 7-4-1 and the fourth interface 7-4 of the fourth four-way reversing valve 7-4 -4 connection, the second port 7-4-2 of the fourth four-way reversing valve 7-4 is connected to the third port 7-4-3, the second two-way valve 6-2 is opened, and the first two-way The valve 6-1 is closed, and the first port 4-1 of the three-way reversing valve 4 is connected to 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 fourth four-way reversing valve The first interface 7-4-1 and the fourth interface 7-4-4 of 7-4, the second circulation channel 3-1-2 of the first functional heat exchanger 3-1, the second two-way The valve 6-2, the second throttle valve 5-2, the second heat exchanger 2-2, the second interface 7-4-2 of the fourth four-way reversing valve 7-4 and the second Three ports 7-4-3, the fourth port 7-2-4 of the second four-way reversing valve 7-2 and the third port 7-2-3, the third port of the three-way reversing valve 4 The interface 4-3 and the first interface 4-1 are sequentially connected back to the suction end of the second compressor 1-2 to complete the low-temperature heat pump cycle. In the third circulation unit: the first port 7-3-1 of the third four-way reversing valve 7-3 is connected to the fourth port 7-3-4, and the third four-way reversing valve 7 -3’s second port 7-3-2 is connected to the third port 7-3-3; the exhaust end of the third compressor 1-3, the third four-way reversing valve 7-3 An interface 7-3-1 and a fourth interface 7-3-4, the second flow passage 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 of the third four-way reversing valve 7-3 -3 is sequentially connected back to the suction end of the third compressor 1-3 to complete the high-temperature heat pump cycle. In the high-temperature stage cycle, 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, and the medium-pressure gas passes through the third Compressor 1-3 compresses into high-pressure gas, and high-pressure gas flows through the first port 7-3-1 and the fourth port 7-3-4 of the third four-way reversing valve 7-3 to enter the second functional changer. The second flow passage 3-2-2 of the heater 3-2 condenses and releases heat into high-pressure liquid to realize heat supply, and the high-pressure liquid enters the third throttle valve 5-3 to throttle and reduce pressure to become 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, absorbs the condensation heat of the low-temperature stage into a medium-pressure gas, and is exchanged by the third four-way The second port 7-3-2 and the third port 7-3-3 of the valve 7-3 return to the suction end of the third compressor 1-3 to complete the high-temperature stage cycle. In the low-temperature stage cycle, the second compressor 1-2 sucks low-pressure gas from the second heat exchanger 2-2, and the low-pressure gas is compressed by the second compressor 1-2 into a medium-pressure gas. The gas passes through the first port 7-2-1 of the second four-way reversing valve 7-2, the second port 7-2-2, and the first port 7-4 of the fourth four-way reversing valve 4-2 -1. The fourth interface 7-4-4 enters the second circulation channel 3-1-2 of the first functional heat exchanger 3-1 to condense, and releases heat to the high-temperature stage to become a medium-pressure liquid, a medium-pressure liquid It enters the second throttle valve 5-2 through the second two-way valve 6-2 to throttle and reduce pressure to become low-pressure wet steam, and the low-pressure wet steam enters the second heat exchanger 2-2 to evaporate and become Low-pressure steam, the low-pressure steam flows through the second port 7-4-2 of the fourth four-way reversing valve 7-4, the third port 7-4-3, and the second four-way reversing valve 7-2. The four ports 7-2-4, the third port 7-2-3, the third port 4-3 of the three-way reversing valve 4, and the first port 4-1 return to the suction of the second compressor 1-2 At the gas end, the low-temperature level cycle is completed. The third circulation passage 3-1-3 of the first functional heat exchanger as an evaporator in the third circulation unit absorbs the second circulation passage 3-1-2 as a condenser in the second circulation unit Heat of condensation released.

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 or orifice throttling devices.

The multi-cycle system of the present invention can realize single-stage compression cycle and cascade cycle under multiple load conditions. Under the evaporating temperature that the single-stage cycle can meet, a single-stage compression refrigeration cycle can be realized; in the case that the single-stage compression refrigeration cycle cannot meet the required evaporating temperature, according to the required load size, low-load working conditions and high-load working conditions can be realized There are two types of cascade refrigeration cycles; in the case of winter heat pumps, when the single-stage cycle can meet the required condensing temperature, a single-stage compression heat pump cycle can be realized; when the single-stage compression heat pump cycle cannot meet the required condensing temperature, According to the required load, low-load cascade heat pump system and high-load cascade heat pump system are realized; in the refrigeration system, the first circulation unit is a fixed unit, which serves as the high-temperature stage of the cascade refrigeration system under low-load conditions Cycle, the third cycle unit is a fixed unit, as the low-temperature stage cycle of the high-load cascade refrigeration system, only the second cycle unit is the variable unit, and the second cycle unit can be used as a single-stage compression refrigeration cycle, under low-load conditions The low-temperature stage cycle of the cascade refrigeration system and the high-temperature stage cycle of the cascade refrigeration system under high load conditions; in the heat pump system, the first circulation unit is a fixed unit, which serves as the low temperature of the cascade heat pump system under low load conditions Stage circulation, the third circulation unit is a fixed unit, as the high-temperature stage circulation of the high-load cascade heat pump system, only the second circulation unit is the change unit, and the second circulation unit can be used as a single-stage compression heat pump cycle, low-load work Consider the high-temperature stage cycle of the cascade heat pump system and the low-temperature stage cycle of the cascade heat pump system under high load conditions. The system of the present invention can realize single-stage compression cycle and cascade cycle under multiple load conditions, and can realize single-stage compression refrigeration cycle, multiple cascade refrigeration cycles, single-stage compression heat pump cycle and multiple cascade cycles. Heat pump cycle, select efficient cycle mode under a variety of load conditions, and the first cycle unit and the third cycle unit are fixed units, only the second cycle unit is a variable unit to improve the efficiency of the system, reduce the system Energy consumption saves the cost of the system.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made. These improvements and modifications It should also be regarded as the protection scope of the present invention.

Claims

A multi-cycle system, characterized in that it includes a first circulation unit, a second circulation unit, and a third circulation unit; the first circulation unit includes a first compressor, a first four-way reversing valve, and a first heat exchange unit. The first circulation channel of the first functional heat exchanger, the first throttle valve and the first functional heat exchanger, the discharge end of the first compressor is connected to the first interface of the first four-way reversing valve, and the first The suction end of the compressor is connected to the third port of the first four-way reversing valve, the second port of the first four-way reversing valve, the first heat exchanger, the first throttle valve, The first circulation channel of the first functional heat exchanger and the fourth interface of the first four-way reversing valve are connected in sequence;

The second circulation unit includes 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 Valve, second two-way valve, three-way reversing valve, second four-way reversing valve, and fourth four-way reversing valve; the discharge end of the second compressor and the second four-way reversing valve The first port of the valve is connected, the second port of the second four-way reversing valve is connected to the first port of the fourth four-way reversing valve, and the second port of the fourth four-way reversing valve is connected to The first interface of the second heat exchanger is connected, and the second interface of the second heat exchanger is respectively connected to the first interface of the first two-way valve and the first interface of the second throttle valve , The second interface of the first two-way valve is respectively connected with the first interface of the second two-way valve and the second interface of the second circulation channel of the first functional heat exchanger, and the second throttle valve The second interface is respectively connected with the second interface of the second two-way valve and the second interface of the first flow channel of the second functional heat exchanger, and the second interface of the first flow channel of the second functional heat exchanger One interface is respectively connected to the fourth interface of the second four-way reversing valve and the third interface of the fourth four-way reversing valve, and the third interface of the second four-way reversing valve is connected to the third interface of the fourth four-way reversing valve. The third port of the three-way reversing valve is connected, the first port of the three-way reversing valve is connected to the suction end of the second compressor, and the first port of the second circulation channel of the first functional heat exchanger is connected. The interface is respectively connected with the second interface of the three-way reversing valve and the fourth interface of the fourth four-way reversing valve;

The third circulation unit includes a third compressor, a third circulation passage of the first functional heat exchanger, a third throttle valve, a second flow passage of the second functional heat exchanger, and a third four-way reversal Valve; the discharge end of the third compressor is connected to the first interface of the third four-way reversing valve, and the suction end of the third compressor is connected to the first port of the third four-way reversing valve Three-port connection, the second port of the third four-way reversing valve, the third circulation channel of the first functional heat exchanger, the third throttle valve, and the second port of the second functional heat exchanger The two flow passages and the fourth port of the third four-way reversing valve are connected in sequence; the first compressor is a low-power compressor, the second compressor is a medium-power compressor, and the third compressor It is a high-power compressor.
The multi-circulation system according to claim 1, wherein the first functional heat exchanger comprises a shell, and the first circulation channel, the second circulation channel, and the second circulation channel are respectively provided in the shell along the length direction. Three circulation channels; the second functional heat exchanger includes a shell in which the first flow channel and the second flow channel are respectively arranged along the length direction; the shell of the first functional heat exchanger and the A heat exchange working medium is respectively arranged in the shell of the second functional heat exchanger.
The multi-cycle system according to claim 1, wherein when the multi-cycle system is a single-stage compression refrigeration cycle, in the second cycle unit: the first port of the second four-way reversing valve and The second interface is connected, and the third interface of the second four-way reversing valve is connected to the fourth interface; the first interface of the fourth four-way reversing valve is connected to the second interface, and the fourth four-way reversing valve is connected to the second interface. The third port of the valve is connected to the fourth port; the first two-way valve and the second two-way valve are closed; the third port of the three-way reversing valve is connected to the first port; the discharge of the second compressor Air end, 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 section Flow valve, the first flow path 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 connected back in sequence To the suction end of the second compressor, a single-stage compression refrigeration cycle is formed.
The multi-cycle system according to claim 1, wherein when the multi-cycle system is a low-load refrigeration cycle, the first cycle unit is a high-temperature compression refrigeration cycle, and the second cycle unit is a low-temperature compression refrigeration cycle. Refrigeration cycle; in the first cycle unit: the first port of the first four-way reversing valve is connected to the second port, and the third port of the first four-way reversing valve is connected to the fourth port; so The discharge 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, and the first functional heat exchanger The first circulation channel, the third interface and the fourth interface of the first four-way reversing valve are sequentially connected back to the suction end of the first compressor to complete a high-temperature compression refrigeration cycle; the second cycle unit Middle: The first port of the second four-way reversing valve is connected to the second port, and the third port of the second four-way reversing valve is connected to the fourth port; the fourth port of the fourth four-way reversing valve is connected to the The first port is connected to the fourth port, the second port of the fourth four-way reversing valve is connected to the third port, the first two-way valve is opened, the second two-way valve is closed, and the three-way valve is closed. The first port of the reversing valve is connected to the third port; the discharge end of the second compressor, the first port and the second port of the second four-way reversing valve, and the fourth four-way reversing valve The first interface and the fourth interface of the first functional heat exchanger, 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 port and the third port of the second four-way reversing valve, and the third port and the first port of the three-way reversing valve are sequentially connected back to the suction end of the second compressor to complete cryogenic compression refrigeration Circulation; the first circulation passage of the first functional heat exchanger as an evaporator in the first circulation unit absorbs condensation heat released by the second circulation passage as a condenser in the second circulation unit.
The multi-cycle system according to claim 1, wherein when the multi-cycle system is a high-load refrigeration cycle, the second cycle unit is a high-temperature compression refrigeration cycle, and the third cycle unit is a low-temperature compression refrigeration cycle; In the second circulation unit: the first port of the second four-way reversing valve is connected to the second port, and the third port of the second four-way reversing valve is connected to the fourth port; The first port of the two-way reversing valve is connected to the second port, and the third port of the fourth four-way reversing valve is connected to the fourth port; the second two-way valve is opened, the first two-way valve is closed, and the three The first port of the two-way reversing valve is connected to the second port; the discharge end of the second compressor, the first port and the second port of the second four-way reversing valve, and the fourth four-way reversing valve The first interface and the second interface of the 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 The second interface and the first interface of the three-way reversing valve are sequentially connected back to the suction end of the second compressor to complete the high-temperature compression refrigeration cycle; in the third cycle unit: the third four-way switch The first port of the directional valve is connected to the second port, and the third port of the third four-way reversing valve is connected to the fourth port; the discharge end of the third compressor and the first functional heat exchanger The third circulation channel, the third throttle valve, the second flow channel of the second functional heat exchanger, the fourth interface and the third interface of the third four-way reversing valve are connected back to the The suction end of the third compressor completes a low-temperature compression refrigeration cycle; the second circulation channel of the first functional heat exchanger serving as an evaporator in the second circulation unit absorbs Condensation heat released by the third circulation channel of the condenser.
The multi-circulation system according to claim 1, wherein when the multi-circulation system is a single-stage compression heat pump cycle, in the second circulation unit: the first interface of the second four-way reversing valve and The fourth interface is connected, the second interface of the second four-way reversing valve is connected to the third interface, the first interface of the fourth four-way reversing valve is connected to the second interface, and the fourth four-way reversing valve is connected to the second interface. The third port of the valve is connected to 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 to the first port; the discharge of the second compressor The gas end, the first interface and the fourth interface of the second four-way reversing valve, the first flow channel of the second functional heat exchanger, the second throttle valve, the second heat exchanger, the The second port and the first port of the fourth four-way reversing valve, the second port and the third port of the second four-way reversing valve, and the third port and the first port of the three-way reversing valve return to the place The suction end of the second compressor forms a single-stage compression heat pump cycle.
The multi-circulation system according to claim 1, wherein when the multi-circulation system is a low-load cascade heat pump cycle, the first circulation unit is a low-temperature heat pump cycle, and the second circulation unit is a high-temperature heat pump cycle. Stage heat pump circulation; in the first circulation unit: the first port of the first four-way reversing valve is connected to the fourth port, and the second port of the first four-way reversing valve is connected to the third port; The discharge end of the first compressor, the first interface and the fourth interface of the first four-way reversing valve, the first circulation passage of the first functional heat exchanger, and 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 suction end of the first compressor to complete the low-temperature heat pump cycle;

In the second circulation unit: the first port of the second four-way reversing valve is connected to the fourth port, the second port of the second four-way reversing valve is connected to the third port, and the fourth port is connected to the third port. The first port of the four-way reversing valve is connected to the fourth port, and the second port of the fourth four-way reversing valve is connected to the third port; the first two-way valve is opened, and the second two-way valve is Closed, the first port of the three-way reversing valve is connected to the second port; the discharge end of the second compressor, the first port and the fourth port of the second four-way reversing valve, the second port The first flow passage of the functional heat exchanger, the second throttle valve, the first two-way valve, the second circulation channel of the first functional heat exchanger, and the second interface of the three-way reversing valve Connect with the first interface in turn and return to the suction end of the second compressor to complete the high-temperature heat pump cycle;

The second circulation passage of the first functional heat exchanger as an evaporator in the second circulation unit absorbs condensation heat released by the first circulation passage as a condenser in the first circulation unit.
The multi-circulation system according to claim 1, wherein when the multi-circulation system is a high-load heat pump cycle, the second circulation unit is a low-temperature heat pump cycle, and the third circulation unit is a high-temperature heat pump cycle In the second circulation unit: the first interface of the second four-way reversing valve is connected to the second interface, the third interface of the second four-way reversing valve is connected to the fourth interface, and the first The first port of the four-way reversing valve is connected to the fourth port, the second port of the fourth four-way reversing valve is connected to the third port, the second two-way valve is opened, and the first two-way valve is opened. The valve is closed, the first port of the three-way reversing valve is connected to the third port; the discharge end of the second compressor, the first port and the second port of the second four-way reversing valve, the 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 first Two heat exchangers, 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 of the three-way reversing valve The three ports and the first port are sequentially connected back to the suction end of the second compressor to complete the low-temperature heat pump cycle; in the third circulation unit: the first port and the first port of the third four-way reversing valve Four-port connection, the second port of the third four-way reversing valve is connected to the third port; the exhaust end of the third compressor, the first port and the fourth port of the third four-way reversing valve Interface, the second flow path of the second functional heat exchanger, the third throttle valve, the third circulation channel of the first functional heat exchanger, the second of the third four-way reversing valve The interface and the third interface are sequentially connected back to the suction end of the third compressor to complete the high-temperature heat pump cycle; the third circulation channel of the first functional heat exchanger as the evaporator in the third circulation unit Absorb the condensation heat released by the second circulation channel as the condenser in the second circulation unit.