CO2 sub- / cross-conversion multi-condition comprehensive application refrigeration system

Abstract

The present invention discloses a CO2 sub- / cross-conversion multi-condition comprehensive application refrigeration system, which relates to the technical field of refrigeration equipment and materials, and in particular to a CO2 sub- / cross-conversion multi-condition comprehensive application refrigeration system. The present invention includes: a quick freezing system compressor unit, a low temperature system compressor unit, a parallel compressor unit, a heat recovery device assembly, an ejector throttling assembly, a medium temperature barrel pump liquid supply system, a low temperature barrel pump liquid supply system, a quick freezing barrel pump liquid supply system, a gas cooler, a plurality of regenerators, a plurality of electronic expansion valves, and a plurality of solenoid valves. The technical solution of the present invention solves the problems in the existing CO2 transcritical multi-condition application refrigeration system technology, such as low equipment integration, high construction cost and high energy consumption, which is not conducive to the overall heat recovery of the system due to the dispersion of the system; uneven liquid distribution of high-pressure common liquid affects the overall refrigeration effect; the pressure maintenance system of each working condition liquid storage container is separately set, resulting in high construction cost, and direct discharge of overpressure causes CO2 waste and increases the greenhouse effect.

Description

Technical Field

[0001] The invention discloses a CO2 sub- / cross-conversion multi-operating-condition comprehensive application refrigeration system, which relates to the technical field of refrigeration equipment and materials, and in particular to a CO2 sub- / cross-conversion multi-operating-condition comprehensive application refrigeration system. Background Art

[0002] At present, CO2 refrigeration system design has certain shortcomings due to the particularity of its physical and chemical properties. For example, when using CO2 transcritical design scheme for multi-condition applications:

[0003] 1. Most of the refrigeration systems corresponding to different working conditions are used to meet their respective usage requirements, and the system integration is low;

[0004] 2. In the actual use of the refrigeration system, due to changes in outdoor climate and other conditions, the outdoor ambient temperature in most parts of China will be lower than the critical temperature of CO2. Combined with the multi-temperature zone design of the cold storage, the overall system has the basis for CO2 sub- / trans-critical switching and multi-condition combined use. The previous technical solutions undoubtedly increased the construction cost and energy consumption;

[0005] 3. In the field of CO2 multi-condition shared high-pressure system, the low-circulation barrels of each working condition system often adopt parallel liquid replenishment. In actual use, due to the pressure difference of each low-circulation barrel, it is easy to cause uneven liquid distribution, affecting the overall refrigeration effect;

[0006] 4. In terms of heat recovery of exhaust waste heat from multi-operating system, the previous technology is not conducive to overall heat recovery due to the relatively scattered systems;

[0007] 5. Due to the low critical pressure of CO2, the system pressure is easy to exceed the design pressure when the shutdown time is long. In the design of existing multi-condition application technology, either a separate pressure maintenance system is set up for the liquid storage container corresponding to each working condition, or an overpressure direct discharge method is adopted. However, setting up a separate pressure maintenance system will lead to high cold storage construction costs, and the overpressure direct discharge method will cause CO2 waste and increase the greenhouse effect.

[0008] In view of the problems existing in the above-mentioned prior art, it is very necessary to study and design a new type of CO2 sub / cross conversion multi-condition comprehensive application refrigeration system to overcome the problems existing in the prior art. Summary of the invention

[0009] According to the technical problems raised in the above-mentioned prior art, such as low system integration, high equipment construction cost and energy consumption, uneven liquid distribution affecting the overall refrigeration effect, the system being relatively dispersed and not conducive to overall heat recovery, the high construction cost caused by the separate pressure maintenance system, and the direct discharge of overpressure causing CO2 waste and increasing the greenhouse effect, a CO2 sub / cross conversion multi-condition comprehensive application refrigeration system is provided. The overall system of the present invention can simultaneously meet the operation of three refrigeration conditions of medium temperature, low temperature and quick freezing, and reasonably allocate the start and stop of compressors and ejectors in each temperature zone according to changes in outdoor climate and exhaust pressure conditions, as well as the automatic switching of the ejector and the electronic expansion valve connected in parallel with it, to achieve stable switching of CO2 sub / cross conditions and multi-condition conversion, and effectively reduce the energy consumption of the system; secondly, the traditional multi-condition parallel liquid replenishment design method is changed, and a multi-stage series liquid replenishment method is adopted to effectively solve the problem of uneven liquid distribution in the refrigeration system, thereby ensuring reliable and stable liquid supply of the system; at the same time, the traditional multi-condition liquid storage container is changed In the pressure maintenance method, the high-pressure liquid storage container (the medium-temperature low-pressure circulation barrel in the present invention) releases pressure to the low-pressure liquid storage container (the low-temperature low-pressure circulation barrel in the present invention) through a pressure regulating valve, and finally the quick-frozen liquid storage container (the quick-frozen low-pressure circulation barrel in the present invention) maintains the overall pressure through a maintaining machine, thereby reducing the construction cost and energy consumption as a whole. In addition, when the pressure maintenance system fails, a pressure relief solenoid valve is connected in parallel to the safety valve on the liquid storage container. When the container is over-pressured, the solenoid valve is tripped first, and then the safety valve is tripped to protect the safety valve, thereby effectively avoiding the problem of safety valve failure caused by frequent tripping of the safety valve.

[0010] The technical methods used in the present invention are as follows:

[0011] A CO2 sub- / cross-conversion multi-mode comprehensive application refrigeration system includes: a quick freezing system compressor unit, a low temperature system compressor unit, a parallel compressor unit, a heat recovery device assembly, an ejector throttling assembly, a medium temperature barrel pump liquid supply system, a low temperature barrel pump liquid supply system, a quick freezing barrel pump liquid supply system, a gas cooler, a plurality of regenerators, a plurality of electronic expansion valves, and a plurality of solenoid valves;

[0012] Furthermore, the exhaust pipes of the quick freezing system compressor unit, the low temperature system compressor unit and the parallel compressor unit are connected to the heat source end inlet of the heat recovery device component through a pipe after merging;

[0013] Further, the heat source end outlet of the heat recovery device assembly is connected to the gas cooler air inlet through a pipeline, and the gas cooler outlet is connected to the heat source end inlet of the regenerator A through a pipeline;

[0014] Furthermore, the heat source end outlet of the regenerator A is connected to the inlet of the ejector throttling assembly through a pipeline;

[0015] Furthermore, the outlet of the ejector throttling assembly is connected to the liquid inlet of the medium-temperature barrel pump liquid supply system through a pipeline;

[0016] Furthermore, the air outlet of the medium-temperature barrel pump liquid supply system is connected to the low-temperature end inlet of the regenerator A through a pipeline, and its liquid outlet is connected to the heat source end inlet of the regenerator B through a pipeline;

[0017] Furthermore, the low temperature end outlet of the regenerator A is connected to the air intake of the parallel compressor unit through a pipeline;

[0018] Further, the heat source end outlet of the regenerator B is connected to the heat source end inlet of the regenerator C through a pipeline;

[0019] Furthermore, the heat source end outlet of the regenerator C is connected to the electronic expansion valve C and the liquid inlet of the low-temperature barrel pump liquid supply system in sequence through pipelines;

[0020] Further, the air outlet of the low-temperature barrel pump liquid supply system and the low-temperature end inlet of the regenerator B are connected by a pipeline;

[0021] Furthermore, the low temperature end outlet of the regenerator B is connected to the solenoid valve and the ejector throttling assembly in sequence through pipelines;

[0022] Further, the air outlet of the low-temperature barrel pump liquid supply system is connected to the low-temperature end inlet of the regenerator C through a pipeline;

[0023] Furthermore, the low temperature end outlet of the regenerator C is connected to the air intake of the low temperature system compressor unit through a pipeline;

[0024] Furthermore, the liquid supply port of the low-temperature barrel pump liquid supply system is connected to the heat source end inlet of the regenerator D through a pipeline;

[0025] Further, the heat source end outlet of the regenerator D is connected to the heat source end inlet of the regenerator E through a pipeline;

[0026] Furthermore, the heat source end outlet of the regenerator E is connected to the electronic expansion valve D and the liquid inlet of the quick freezing barrel pump liquid supply system in sequence through pipelines;

[0027] Furthermore, the air outlet of the quick freezing barrel pump liquid supply system is connected to the cold source end inlet of the regenerator D through a pipeline;

[0028] Furthermore, the cold source end outlet of the regenerator D is connected to the solenoid valve and the ejector throttling assembly through a pipeline;

[0029] Furthermore, the gas outlet of the quick freezing barrel pump liquid supply system is connected to the cold source end inlet of the regenerator E through a pipeline;

[0030] Furthermore, the cold source end outlet of the regenerator E is connected to the air intake of the quick-freezing system compressor unit through a pipeline.

[0031] Further, the quick freezing system compressor unit, the low temperature system compressor unit and the parallel compressor unit are all provided with a compressor and an oil separator;

[0032] Further, the quick freezing system compressor unit is connected to the quick freezing system compressor matching separator through pipelines by N quick freezing system compressors;

[0033] Further, the cryogenic system compressor unit is connected to the cryogenic system compressor supporting oil separators through pipelines by N cryogenic system compressors;

[0034] Furthermore, the parallel compressor unit also serves as the medium temperature system compressor unit. When there is no medium temperature load, it is used as a low-pressure parallel compressor to improve the system COP. The parallel compressor unit is composed of N medium temperature system compressors connected to the oil separators of the medium temperature system compressors through pipelines.

[0035] Furthermore, the oil outlets of the quick freezing system compressor supporting separator, the low temperature system compressor supporting oil separator and the medium temperature system compressor supporting oil separator are connected to the oil inlet of the oil tank through pipelines;

[0036] Furthermore, the oil tank outlet is connected to the stop valve and the air intake of the medium temperature system compressor through pipelines in sequence;

[0037] Furthermore, the oil outlet of the oil tank is connected to the oil return ports of the medium-temperature system compressor, the low-temperature system compressor and the quick-freezing system compressor through pipelines.

[0038] Further, the ejector throttling assembly comprises: an ejector A, an electronic expansion valve A, an ejector B and an electronic expansion valve B;

[0039] Furthermore, the ejector A and the electronic expansion valve A are connected in parallel, and their inlets are connected to the outlet of the heat source end of the regenerator A through a pipeline, and their outlets are connected to the liquid inlet of the medium-temperature barrel pump liquid supply system through a pipeline;

[0040] Furthermore, the ejector B and the electronic expansion valve B are connected in parallel; the inlets of the two are connected to the outlet of the heat source end of the regenerator A through a pipeline, and the outlet is connected to the liquid inlet of the medium-temperature barrel pump liquid supply system through a pipeline;

[0041] Furthermore, during operation, the control system automatically switches between transcritical and subcritical conditions based on changes in factors such as outdoor ambient temperature and exhaust pressure. An ejector is used during transcritical conditions, and an electronic expansion valve is used during subcritical conditions or when only a medium-temperature system is used.

[0042] Furthermore, the medium-temperature barrel pump liquid supply system includes: a medium-temperature low-pressure circulation barrel, a double-seat safety valve supporting a pressure relief solenoid valve A, a pressure regulating valve A, a medium-temperature system CO2 shielded pump, a medium-temperature system air return port, a medium-temperature system liquid supply port, a liquid level sensor supporting a liquid level switch and a liquid level gauge A and a pressure regulating valve C;

[0043] Furthermore, the liquid inlet of the medium-temperature low-pressure circulation barrel is connected to the ejector A, the electronic expansion valve A, the ejector B and the outlet of the electronic expansion valve B through a pipeline; the gas outlet of the medium-temperature low-pressure circulation barrel is connected to the low-temperature end inlet of the regenerator A through a pipeline, and the liquid outlet is connected to the heat source end inlet of the regenerator B through a pipeline;

[0044] Furthermore, the medium-temperature low-pressure circulation barrel is equipped with a double-seat safety valve with a pressure relief solenoid valve A and a liquid level sensor with a liquid level switch and a liquid level gauge A as standard;

[0045] Further, the medium-temperature low-pressure circulation barrel is connected to the medium-temperature system CO2 shielding pump and the medium-temperature system liquid supply port in sequence through pipelines;

[0046] Furthermore, a pressure regulating valve C is provided between the medium-temperature low-pressure circulation barrel and the liquid supply pipeline after the medium-temperature system CO2 shielding pump;

[0047] Further, the medium-temperature low-pressure circulation barrel is connected to the pressure regulating valve A and the low-temperature low-pressure circulation barrel in sequence through pipelines;

[0048] Further, the medium-temperature low-pressure circulation barrel is connected to the medium-temperature system air return port through a pipeline;

[0049] Furthermore, the medium temperature system air return port and the medium temperature system liquid supply port are connected to the terminal refrigeration evaporation equipment of the medium temperature system.

[0050] Furthermore, the cryogenic barrel pump liquid supply system includes: a cryogenic and low-pressure circulation barrel, a double-seat safety valve supporting a pressure relief solenoid valve B, a pressure regulating valve B, a cryogenic system CO2 shielded pump, a cryogenic system return air port, a cryogenic system liquid supply port, a liquid level sensor supporting a liquid level switch and a liquid level gauge B and a pressure regulating valve D;

[0051] Furthermore, the liquid inlet of the low-temperature and low-pressure circulation barrel is connected to the electronic expansion valve C and the outlet of the heat source end of the regenerator C in sequence through a pipeline, the liquid outlet is connected to the inlet of the heat source end of the regenerator D through a pipeline, and the gas outlet is connected to the inlet of the low-temperature end of the regenerator B and the inlet of the low-temperature end of the regenerator C through pipelines respectively;

[0052] Furthermore, the low-temperature and low-pressure circulation barrel is equipped with a double-seat safety valve with a pressure relief solenoid valve B and a liquid level sensor with a liquid level switch and a liquid level gauge B as standard;

[0053] Further, the low-temperature and low-pressure circulation barrel is connected to the low-temperature system CO2 shielding pump and the low-temperature system liquid supply port in sequence through pipelines;

[0054] Furthermore, a pressure regulating valve D is provided between the low-temperature and low-pressure circulation barrel and the liquid supply pipeline after the CO2 shielding pump of the low-temperature system;

[0055] Further, the low-temperature and low-pressure circulation barrel is connected to the pressure regulating valve B and the quick freezing barrel pump liquid supply system in sequence through pipelines;

[0056] Further, the low-temperature and low-pressure circulation barrel is connected to the return air port of the low-temperature system through a pipeline;

[0057] Furthermore, the low-temperature system air return port and the low-temperature system liquid supply port are connected to the low-temperature system terminal refrigeration evaporation equipment.

[0058] Furthermore, the quick freezing barrel pump liquid supply system includes: a quick freezing low-pressure circulation barrel, a double-seat safety valve supporting a pressure relief solenoid valve C, a maintenance unit, a solenoid valve for the maintenance unit, an expansion valve for the maintenance unit, a heat exchanger for pressure maintenance, a pressure controller, a quick freezing system CO2 shielded pump, a quick freezing system air return port, a quick freezing system liquid supply port, a liquid level sensor supporting a liquid level switch and a liquid level gauge C and a pressure regulating valve E;

[0059] Furthermore, the liquid inlet of the quick-freezing low-pressure circulation barrel is connected to the electronic expansion valve D and the outlet of the heat source end of the regenerator E in sequence through pipelines, and the gas outlet is connected to the inlet of the cold source end of the regenerator D and the inlet of the cold source end of the regenerator E through pipelines respectively;

[0060] Furthermore, the quick-freezing low-pressure circulation barrel is equipped with a double-seat safety valve with a pressure relief solenoid valve C and a liquid level sensor with a liquid level switch and a liquid level gauge C as standard;

[0061] Further, the quick-freezing low-pressure circulation barrel is connected to the quick-freezing system CO2 shielding pump and the quick-freezing system liquid supply port in sequence through pipelines;

[0062] Furthermore, the air intake port of the maintenance unit is connected to the return air port of the cold source end of the pressure maintenance heat exchanger through a pipeline, and the liquid supply port is connected to the solenoid valve for the maintenance unit, the expansion valve for the maintenance unit, and the liquid inlet of the cold source end of the pressure maintenance heat exchanger through a pipeline;

[0063] Furthermore, the air inlet of the heat source end of the pressure-maintaining heat exchanger is connected to the air outlet of the quick-freezing low-pressure circulation barrel through a pipeline; the liquid return port of the heat source end of the pressure-maintaining heat exchanger is connected to the liquid inlet of the quick-freezing low-pressure circulation barrel through a pipeline;

[0064] Furthermore, a pressure regulating valve E is provided between the quick-freezing low-pressure circulation barrel and the liquid supply pipeline after the CO2 shielding pump of the quick-freezing system;

[0065] Further, the quick-freezing low-pressure circulation barrel is connected to the air return port of the quick-freezing system through a pipeline;

[0066] Furthermore, the air return port of the quick freezing system and the liquid supply port of the quick freezing system are connected to the terminal refrigeration evaporation equipment of the quick freezing system.

[0067] Further, the heat recovery device assembly includes: a domestic water heat recovery device, an evaporator defrost water heat recovery device, a floor antifreeze water heat recovery device, a domestic water cooling source end interface, an evaporator defrost water cooling source end interface and a floor antifreeze water cooling source end interface;

[0068] Furthermore, a domestic water heat recovery device, an evaporator defrosting water heat recovery device, and a floor antifreeze water heat recovery device are sequentially connected through pipelines;

[0069] Furthermore, the heat source inlet of the domestic water heat recovery device is connected to the exhaust gas converging pipeline of the quick freezing system compressor unit, the low temperature system compressor unit and the parallel compressor unit through a pipeline;

[0070] Furthermore, the heat source outlet of the floor antifreeze water heat recovery device is connected to the air inlet of the gas cooler through a pipeline;

[0071] Further, the domestic water cooling source end interface is connected to the domestic water heat recovery device through a pipeline;

[0072] Furthermore, the evaporator defrost water cooling source end interface is connected to the evaporator defrost water heat recovery device through a pipeline;

[0073] Furthermore, the floor antifreeze water cooling source end interface is connected to the floor antifreeze water heat recovery device through a pipeline.

[0074] Furthermore, an electric regulating valve A is connected in parallel to the inlet and outlet pipes of the heat source end of the domestic water heat recovery device;

[0075] Furthermore, an electric regulating valve B is connected in parallel to the inlet and outlet pipes of the heat source end of the evaporator defrosting water heat recovery device;

[0076] Furthermore, an electric regulating valve C is connected in parallel to the inlet and outlet pipes of the heat source end of the water heat recovery device for floor antifreeze.

[0077] The specific working state of the present invention is as follows:

[0078] The whole system can meet the use conditions of three refrigeration conditions: medium temperature, low temperature and quick freezing. When the system is running, the CO2 gas refrigerant from the evaporation equipment enters the low-pressure circulation barrel, and then is heated by the regenerator and enters the compressor suction port. After being compressed by the compressor, the CO2 becomes a high-temperature and high-pressure state and enters the exhaust pipeline. After the exhaust pipelines of the three refrigeration compressor units are merged, they can pass through the domestic water heat recovery device, the evaporator defrosting water heat recovery device, and the floor antifreeze water heat recovery device in turn according to the use conditions. It can not only meet other water needs, but also utilize the waste heat of the unit to effectively improve the comprehensive energy utilization efficiency; after passing through the heat recovery equipment, it is transported to the gas cooler, completes a cooling in the cooler, and then flows It enters the heat source end of the regenerator, completes secondary cooling after heat exchange with the cold source end of the return air pipeline of the medium temperature system, and the fluid after secondary cooling under transcritical conditions flows into ejector A and ejector B respectively. Only the medium temperature system or subcritical conditions use the fluid after secondary cooling to flow into the electronic expansion valve A and electronic expansion valve B respectively; the CO2 fluid flowing into the ejector under transcritical conditions can be cooled three times with the gas cold source from the low-temperature refrigeration system and the quick-freezing system, and then flows into the low-pressure circulation barrel of the medium temperature system, one way is supplied to the evaporation equipment of the medium temperature system through the CO2 shielded pump of the medium temperature system, and the refrigeration cycle of the medium temperature system is completed; the other way is supplied to the low-temperature and low-pressure circulation barrel through the regenerator B, the regenerator C, and the electronic expansion valve C. Only the CO2 fluid flowing into the electronic expansion valves A and B under the medium temperature system or subcritical conditions enters the low-pressure circulation barrel of the medium temperature system. One route is supplied to the evaporation equipment of the medium temperature system through the CO2 shielded pump of the medium temperature system to complete the refrigeration cycle of the medium temperature system; the other route is supplied to the low-temperature and low-pressure circulation barrel through the regenerator B, the regenerator C, and the electronic expansion valve C. The low-temperature system low-pressure circulation barrel replenishment relies on the medium-temperature and low-pressure circulation barrel. The liquid coming out of the liquid bag of the medium-temperature and low-pressure circulation barrel flows through the regenerator B, and exchanges heat with the CO2 gas cold source from the outlet of the low-temperature and low-pressure circulation barrel to the ejector A to complete the primary cooling, and then enters the regenerator C to exchange heat with the CO2 gas from the outlet of the low-temperature and low-pressure circulation barrel to the suction port of the low-temperature system compressor to complete the secondary cooling, and then flows into the low-temperature and low-pressure circulation barrel, and supplies liquid to the evaporation equipment of the low-temperature system through the low-temperature system CO2 shielded pump to complete the refrigeration cycle of the low-temperature system; the same In principle, the liquid replenishment of the low-pressure circulation barrel of the quick freezing system uses the liquid from the low-temperature low-pressure circulation barrel. The liquid from the low-temperature low-pressure circulation barrel liquid bag flows through the regenerator D, and exchanges heat with the CO2 gas cold source from the outlet of the quick freezing low-pressure circulation barrel to the ejector B, completing the primary cooling, and then flows into the regenerator E, and exchanges heat with the CO2 gas from the outlet of the quick freezing low-pressure circulation barrel to the suction port of the quick freezing system compressor, completing the secondary cooling, and then flows into the quick freezing low-pressure circulation barrel, and is supplied to the quick freezing system evaporation equipment through the quick freezing system CO2 shielding pump, completing the quick freezing system refrigeration cycle. In terms of low-circulation barrel liquid level control, the liquid level can be controlled by the liquid level control components equipped on each low-circulation barrel.

[0079] Compared with the prior art, the present invention has the following advantages:

[0080] 1. The present invention is based on the use conditions of the CO2 transcritical system. On the one hand, due to the existing solutions, under the conditions of multiple working conditions, the refrigeration systems corresponding to each working condition are mostly used to meet the respective use requirements, and the integration is low; on the other hand, in the actual use of the refrigeration system, based on the changes in outdoor climate and other conditions, the outdoor ambient temperature in most parts of China will be lower than the CO2 critical temperature. Combined with the multi-temperature zone use design of the cold storage, in most parts of my country, especially in the northern region, the overall system has the use conditions of CO2 sub / trans switching and multi-working conditions. The previous technical solutions undoubtedly increased the construction cost and power consumption; therefore, the present invention integrates multiple working condition systems into one system, making the system more compact, reducing construction costs and improving energy efficiency; in addition, by monitoring the outdoor climate and exhaust pressure and other conditions to determine the switching between the electronic expansion valve and the ejector, the sub / trans state conversion of the system is realized to improve the overall energy efficiency of the system.

[0081] 2. Based on the content introduced in Technical Advantage 1, the present invention optimizes the three refrigeration systems of medium temperature, low temperature and quick freezing into one refrigeration system, wherein the compressor of the medium temperature refrigeration system is not only the medium temperature load refrigeration equipment in the content of the present invention, but also can be used as the parallel compressor in the parallel compression technology of the CO2 transcritical system, which is used to maintain the system pressure in the medium temperature and low pressure circulation barrel. At the same time, through the use of the ejector, the parallel compressor can also bear part of the load of the low temperature and quick freezing system, thereby achieving a significant improvement in the system energy efficiency and meeting the requirements of multiple working conditions.

[0082] 3. In the prior art, in a multi-operating-condition refrigeration system, the low-circulation barrels of each operating-condition system generally adopt a parallel liquid replenishment method, that is, the liquid is transported from the high-pressure liquid storage device to the low-circulation barrels of each operating condition respectively. This method may easily lead to uneven liquid distribution due to the difference in pressure of each low-circulation barrel during actual use, thereby affecting the overall refrigeration effect. The present invention changes to a series liquid replenishment form by comprehensively considering the system use conditions. Specifically, the liquid coming out of the air cooler returns to the medium-temperature low-pressure circulation barrel after passing through the regenerator and the ejector or the electronic expansion valve. The low-temperature low-pressure circulation barrel is replenished with liquid from the medium-temperature low-pressure circulation barrel, and the quick-freezing low-pressure circulation barrel is replenished with liquid from the low-temperature low-pressure circulation barrel. This can effectively improve the stability of liquid replenishment in each operating-condition system during actual use.

[0083] 4. Three-in-one heat recovery technology: During the use of cold storage, there is usually a demand for domestic hot water, defrost water heating and floor antifreeze heating. In the past, the design of multi-condition high-pressure systems was relatively scattered, and the overall heat recovery effect was very unsatisfactory. The present invention integrates the multi-condition systems: medium temperature, low temperature and quick freezing systems into one refrigeration system, which not only saves equipment floor space, but also aggregates the exhaust heat of each dispersed system to make full use of waste heat. The three types of heat recovery are integrated into one system, ensuring that a large amount of stable heat source is provided for the three-in-one heat recovery. In addition, by connecting an electric regulating valve in parallel with the heat recovery heat exchanger, the outlet water temperature of each heat recovery heat exchanger can be adjusted, thereby achieving the purpose of energy saving and cost reduction.

[0084] 5. Due to the low critical pressure of CO2, the system pressure is easy to exceed the design pressure when the shutdown time is long. In the design of existing multi-condition application technology, either a separate pressure maintenance system is set up for the liquid storage container corresponding to each working condition, or an overpressure direct discharge method is adopted. However, setting up a separate pressure maintenance system will lead to high cold storage construction costs, and the overpressure direct discharge method will cause CO2 waste and increase the greenhouse effect. The present invention adopts a step-by-step pressure relief method, that is, by equipping the low-pressure circulation barrels of the medium-temperature and low-temperature systems with pressure regulating valves respectively, and equipping the CO2 low-pressure circulation barrel of the quick-freezing system with a pressure control auxiliary system, that is, a maintaining machine system; the high-pressure liquid storage container (the medium-temperature low-pressure circulation barrel in the present invention) releases pressure to the low-pressure liquid storage container (the low-temperature low-pressure circulation barrel in the present invention) through the pressure regulating valve, and finally the quick-freezing liquid storage container (the quick-freezing low-pressure circulation barrel in the present invention) maintains the overall pressure through the maintaining machine, thereby reducing the construction cost and energy consumption as a whole; in addition, each set of low-pressure circulation barrels is equipped with a double-seat safety valve and a matching pressure relief solenoid valve, which can automatically relieve pressure when the maintenance system fails and the system pressure exceeds the set pressure to ensure the safety of the entire system; wherein, by connecting the pressure relief solenoid valve in parallel to the safety valve, the solenoid valve can be relieved before the safety valve is tripped, so as to prevent the safety valve from being damaged by frequent tripping.

[0085] In summary, the technical solution of the present invention solves the problems in the existing CO2 transcritical multi-operating condition refrigeration system technology, such as low equipment integration, high construction cost and energy consumption, and poor overall heat recovery of the system due to the decentralized system; uneven high-pressure shared liquid distribution affects the overall refrigeration effect; a separate pressure maintenance system is set for each operating condition liquid storage container, resulting in high construction cost, and direct overpressure emission causes CO2 waste and increases the greenhouse effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0087] Figure 1 This is a layout diagram of the present invention.

[0088] In the figure: 1. Quick freezing system compressor 2. Low temperature system compressor 3. Medium temperature system compressor 4. Quick freezing system compressor supporting oil separator 5. Low temperature system compressor supporting oil separator 6. Medium temperature system compressor supporting oil separator 7. Domestic water heat recovery device 8. Evaporator defrosting water heat recovery device 9. Floor antifreeze water heat recovery device 10. Gas cooler 11. Regenerator A12. Ejector A13. Electronic expansion valve A14. Medium temperature low pressure circulation barrel 15. Double seat Safety valve supporting pressure relief solenoid valve A16, pressure regulating valve A17, ejector B18, electronic expansion valve B19, regenerator B20, regenerator C21, electronic expansion valve C22, low temperature and low pressure circulation barrel 23, double seat safety valve supporting pressure relief solenoid valve B24, pressure regulating valve B25, solenoid valve 26, regenerator D27, regenerator E28, electronic expansion valve D29, quick freezing low pressure circulation barrel 30, double seat safety valve supporting pressure relief solenoid valve C31, solenoid valve 32 , maintenance unit 33, solenoid valve for maintenance unit 34, expansion valve for maintenance unit 35, heat exchanger for pressure maintenance 36, pressure controller 37, CO2 shielded pump for medium temperature system 38, air return port for medium temperature system 39, liquid supply port for medium temperature system 40, liquid level sensor, supporting liquid level switch and liquid level gauge A41, pressure regulating valve C42, CO2 shielded pump for low temperature system 43, air return port for low temperature system 44, liquid supply port for low temperature system 45, liquid level sensor, supporting liquid level switch and liquid level Gauge B46, pressure regulating valve D47, quick freezing system CO2 shielded pump 48, quick freezing system return air port 49, quick freezing system liquid supply port 50, liquid level sensor supporting liquid level switch and liquid level gauge C51, pressure regulating valve E52, CO2 system oil tank 53, throttle valve 54, domestic water cooling source end interface 55, evaporator defrost water cooling source end interface 56, floor antifreeze water cooling source end interface 57, electric regulating valve A58, electric regulating valve B59, electric regulating valve C. DETAILED DESCRIPTION

[0089] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0090] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0091] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0092] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps described in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0093] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0094] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0095] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0096] like Figure 1As shown, the present invention provides a CO2 sub- / cross-conversion multi-mode comprehensive application refrigeration system including: a quick freezing system compressor unit, a low temperature system compressor unit, a parallel compressor unit, a heat recovery device assembly, an ejector throttling assembly, a medium temperature barrel pump liquid supply system, a low temperature barrel pump liquid supply system, a quick freezing barrel pump liquid supply system, a gas cooler 10, a plurality of heat regenerators, a plurality of electronic expansion valves, and a plurality of solenoid valves; the exhaust pipes of the quick freezing system compressor unit, the low temperature system compressor unit, and the parallel compressor unit are connected to the heat source end inlet of the heat recovery device assembly through a pipeline after merging; the heat source end outlet of the heat recovery device assembly is connected to the gas cooler 1 0 air inlet is connected through a pipeline, the outlet of gas cooler 10 is connected to the inlet of the heat source end of regenerator A11 through a pipeline; the outlet of the heat source end of regenerator A11 is connected to the inlet of the ejector throttling assembly through a pipeline; the outlet of the ejector throttling assembly is connected to the liquid inlet of the medium-temperature barrel pump liquid supply system through a pipeline; the air outlet of the medium-temperature barrel pump liquid supply system is connected to the inlet of the low-temperature end of regenerator A11 through a pipeline, and its liquid outlet is connected to the inlet of the heat source end of regenerator B19 through a pipeline; the outlet of the low-temperature end of regenerator A11 is connected to the air intake of the parallel compressor unit through a pipeline; the outlet of the heat source end of regenerator B19 is connected to the heat source end of regenerator C20 The inlet is connected through a pipeline; the outlet of the heat source end of the heat regenerator C20 is connected to the electronic expansion valve C21 and the liquid inlet of the low-temperature barrel pump liquid supply system through a pipeline in sequence; the air outlet of the low-temperature barrel pump liquid supply system and the low-temperature end inlet of the heat regenerator B19 are connected through a pipeline; the low-temperature end outlet of the heat regenerator B19 is connected to the solenoid valve 25 and the ejector throttling assembly through a pipeline in sequence; the air outlet of the low-temperature barrel pump liquid supply system is connected to the low-temperature end inlet of the heat regenerator C20 through a pipeline; the low-temperature end outlet of the heat regenerator C20 is connected to the air intake of the low-temperature system compressor unit through a pipeline; the liquid supply port of the low-temperature barrel pump liquid supply system is connected to the heat source end inlet of the heat regenerator D26 through Pipeline connection; the heat source end outlet of the regenerator D26 is connected to the heat source end inlet of the regenerator E27 through a pipeline; the heat source end outlet of the regenerator E27 is connected to the electronic expansion valve D28 and the liquid inlet of the quick freezing barrel pump liquid supply system through a pipeline in turn; the air outlet of the quick freezing barrel pump liquid supply system is connected to the cold source end inlet of the regenerator D26 through a pipeline; the cold source end outlet of the regenerator D26 is connected to the solenoid valve 31 and the ejector throttling assembly through a pipeline; the air outlet of the quick freezing barrel pump liquid supply system is connected to the cold source end inlet of the regenerator E27 through a pipeline; the cold source end outlet of the regenerator E27 is connected to the air intake of the quick freezing system compressor unit through a pipeline.

[0097] The quick freezing system compressor unit, the low temperature system compressor unit and the parallel compressor unit are all provided with compressors and oil separators; the quick freezing system compressor unit is connected to the quick freezing system compressor supporting separator 4 through pipelines by N quick freezing system compressors 1; the low temperature system compressor unit is connected to the low temperature system compressor supporting oil separator 5 through pipelines by N low temperature system compressors 2; the parallel compressor unit also serves as the medium temperature system compressor unit, and is used as a low pressure level parallel compressor in the absence of medium temperature load to improve the system COP; the parallel compressor unit is connected to the medium temperature system compressor supporting oil separator 6 by pipelines by N medium temperature system compressors 3; the oil outlets of the quick freezing system compressor supporting separator 4, the low temperature system compressor supporting oil separator 5 and the medium temperature system compressor supporting oil separator 6 are connected to the oil inlet of the oil tank 52 through pipelines; the air outlet of the oil tank 52 is connected to the stop valve 53 and the air intake of the medium temperature system compressor 3 through pipelines in turn; the oil outlet of the oil tank 52 is connected to the oil return ports of the medium temperature system compressor 3, the low temperature system compressor 2 and the quick freezing system compressor 1 through pipelines.

[0098] The ejector throttling assembly includes: ejector A12, electronic expansion valve A13, ejector B17 and electronic expansion valve B18; ejector A12 and electronic expansion valve A13 are connected in parallel, and their inlets are connected to the outlet of the heat source end of the regenerator A11 through a pipeline, and their outlets are connected to the liquid inlet of the medium-temperature barrel pump liquid supply system through a pipeline; ejector B17 and electronic expansion valve B18 are connected in parallel; their inlets are connected to the outlet of the heat source end of the regenerator A11 through a pipeline, and their outlets are connected to the liquid inlet of the medium-temperature barrel pump liquid supply system through a pipeline; during operation, the control system automatically switches between transcritical and subcritical conditions in combination with changes in factors such as outdoor ambient temperature and exhaust pressure. The ejector is used in transcritical conditions, and the electronic expansion valve is used in subcritical conditions or when only the medium-temperature system is used.

[0099] The medium-temperature barrel pump liquid supply system includes: a medium-temperature low-pressure circulation barrel 14, a double-seat safety valve supporting a pressure relief solenoid valve A15, a pressure regulating valve A16, a medium-temperature system CO2 shielded pump 37, a medium-temperature system return air port 38, a medium-temperature system liquid supply port 39, a liquid level sensor supporting a liquid level switch and a liquid level gauge A40 and a pressure regulating valve C41; the liquid inlet of the medium-temperature low-pressure circulation barrel 14 is connected to the outlets of the ejector A12, the electronic expansion valve A13, the ejector B17 and the electronic expansion valve B18 through a pipeline; the air outlet of the medium-temperature low-pressure circulation barrel 14 is connected to the low-temperature end inlet of the regenerator A11 through a pipeline, and the liquid outlet is connected to the heat source end inlet of the regenerator B19 through a pipeline; the medium-temperature low-pressure circulation barrel 14 is equipped with a double-seat safety valve with a pressure relief solenoid valve A15 and a liquid level sensor with a liquid level switch and a liquid level gauge A40; the medium-temperature low-pressure circulation barrel 14 is connected with the medium-temperature system CO2 shielded pump 37 and the medium-temperature system liquid supply port 39 in sequence through pipelines; a pressure regulating valve C41 is arranged between the medium-temperature low-pressure circulation barrel 14 and the liquid supply pipeline after the medium-temperature system CO2 shielded pump 37 pump; the medium-temperature low-pressure circulation barrel 14 is connected with the pressure regulating valve A16 and the low-temperature low-pressure circulation barrel 22 in sequence through pipelines; the medium-temperature low-pressure circulation barrel 14 is connected with the medium-temperature system return air port 38 through pipelines; the medium-temperature system return air port 38 and the medium-temperature system liquid supply port 39 are connected to the terminal refrigeration evaporation equipment of the medium-temperature system.

[0100] The cryogenic barrel pump liquid supply system includes: a cryogenic low-pressure circulation barrel 22, a double-seat safety valve supporting a pressure relief solenoid valve B23, a pressure regulating valve B24, a cryogenic system CO2 shielded pump 42, a cryogenic system return air port 43, a cryogenic system liquid supply port 44, a liquid level sensor supporting a liquid level switch and a liquid level gauge B45 and a pressure regulating valve D46; the liquid inlet of the cryogenic low-pressure circulation barrel 22 is connected to the electronic expansion valve C21 and the heat source outlet of the regenerator C20 through a pipeline in sequence, the liquid outlet is connected to the heat source inlet of the regenerator D26 through a pipeline, and the gas outlet is connected to the low-temperature inlet of the regenerator B19 and the low-temperature inlet of the regenerator C20 through a pipeline respectively; the cryogenic low-pressure circulation barrel 22 The standard double-seat safety valve is equipped with a pressure relief solenoid valve B23 and a liquid level sensor with a liquid level switch and a liquid level gauge B45; the low-temperature and low-pressure circulation barrel 22 is connected to the low-temperature system CO2 shielded pump 42 and the low-temperature system liquid supply port 44 in sequence through pipelines; a pressure regulating valve D46 is arranged between the low-temperature and low-pressure circulation barrel 22 and the liquid supply pipeline behind the low-temperature system CO2 shielded pump 42; the low-temperature and low-pressure circulation barrel 22 is connected to the pressure regulating valve B24 and the quick freezing barrel pump liquid supply system through pipelines; the low-temperature and low-pressure circulation barrel 22 is connected to the low-temperature system return air port 43 through pipelines; the low-temperature system return air port 43 and the low-temperature system liquid supply port 44 are connected to the terminal refrigeration evaporation equipment of the low-temperature system.

[0101] The quick freezing barrel pump liquid supply system includes: a quick freezing low-pressure circulation barrel 29, a double-seat safety valve supporting a pressure relief solenoid valve C30, a maintenance unit 32, a solenoid valve for maintaining the unit 33, an expansion valve for maintaining the unit 34, a heat exchanger for pressure maintenance 35, a pressure controller 36, a quick freezing system CO2 shielded pump 47, a quick freezing system air return port 48, a quick freezing system liquid supply port 49, a liquid level sensor supporting a liquid level switch and a liquid level gauge C50 and a pressure regulating valve E51; the liquid inlet of the quick freezing low-pressure circulation barrel 29 is connected to the electronic expansion valve D28 and the outlet of the heat source end of the regenerator E27 in sequence through pipelines, and the gas outlet is connected to the inlet of the cold source end of the regenerator D26 and the inlet of the cold source end of the regenerator E27 through pipelines respectively; the quick freezing low-pressure circulation barrel 29 is equipped with a double-seat safety valve supporting a pressure relief solenoid valve C30 and a liquid level sensor supporting a liquid level switch and a liquid level gauge C50 as standard; the quick freezing low-pressure circulation barrel 29 is connected to the The CO2 shielded pump 47 of the quick freezing system is connected to the liquid supply port 49 of the quick freezing system; the air intake of the maintenance unit 32 is connected to the return air port of the cold source end of the pressure maintenance heat exchanger 35 through a pipeline, and the liquid supply port is connected to the electromagnetic valve 33 for the maintenance unit, the expansion valve 34 for the maintenance unit, and the liquid inlet of the cold source end of the pressure maintenance heat exchanger 35 through a pipeline; the air inlet of the heat source end of the pressure maintenance heat exchanger 35 is connected to the air outlet of the quick freezing low-pressure circulation barrel 29 through a pipeline; the liquid return port of the heat source end of the pressure maintenance heat exchanger 35 is connected to the liquid inlet of the quick freezing low-pressure circulation barrel 29 through a pipeline; a pressure regulating valve E51 is provided between the quick freezing low-pressure circulation barrel 29 and the liquid supply pipeline after the quick freezing system CO2 shielded pump 47; the quick freezing low-pressure circulation barrel 29 is connected to the return air port 48 of the quick freezing system through a pipeline; the return air port 48 of the quick freezing system and the liquid supply port 49 of the quick freezing system are connected to the refrigeration evaporation equipment at the end of the quick freezing system.

[0102] The heat recovery device assembly includes: a domestic water heat recovery device 7, an evaporator defrost water heat recovery device 8, a floor antifreeze water heat recovery device 9, a domestic water cold source end interface 54, an evaporator defrost water cold source end interface 55 and a floor antifreeze water cold source end interface 56; the domestic water heat recovery device 7, the evaporator defrost water heat recovery device 8 and the floor antifreeze water heat recovery device 9 are connected in sequence through pipelines; the heat source end inlet of the domestic water heat recovery device 7 is connected to the exhaust merging pipeline of the quick freezing system compressor unit, the low temperature system compressor unit and the parallel compressor unit through a pipeline; the heat source end outlet of the floor antifreeze water heat recovery device 9 is connected to the air inlet of the gas cooler 10 through a pipeline; the domestic water cold source end interface 54 is connected to the domestic water heat recovery device 7 through a pipeline; the evaporator defrost water cold source end interface 55 is connected to the evaporator defrost water heat recovery device 8 through a pipeline;

[0103] The floor antifreeze water cooling source end interface 56 is connected to the floor antifreeze water heat recovery device 9 through a pipeline.

[0104] An electric regulating valve A57 is connected in parallel on the inlet and outlet pipes of the heat source end of the domestic water heat recovery device 7; an electric regulating valve B58 is connected in parallel on the inlet and outlet pipes of the heat source end of the evaporator defrost water heat recovery device 8; an electric regulating valve C59 is connected in parallel on the inlet and outlet pipes of the heat source end of the floor antifreeze water heat recovery device 9.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A CO2 sub- / cross-conversion multi-condition comprehensive application refrigeration system, characterized by: The CO2 sub- / cross-conversion multi-mode comprehensive application refrigeration system comprises: a quick freezing system compressor unit, a low temperature system compressor unit, a parallel compressor unit, a heat recovery device component, an ejector throttling component, a medium temperature barrel pump liquid supply system, a low temperature barrel pump liquid supply system, a quick freezing barrel pump liquid supply system, a gas cooler (10), a plurality of regenerators, a plurality of electronic expansion valves, and a plurality of solenoid valves; The exhaust pipes of the quick freezing system compressor unit, the low temperature system compressor unit and the parallel compressor unit are connected to the heat source end inlet of the heat recovery device component through a pipeline after merging; The heat source end outlet of the heat recovery device assembly is connected to the air inlet of the gas cooler (10) through a pipeline, and the gas cooler (10) outlet is connected to the heat source end inlet of the heat regenerator A (11) through a pipeline; The heat source outlet of the regenerator A (11) is connected to the inlet of the ejector throttling assembly via a pipeline; The outlet of the ejector throttling component is connected to the liquid inlet of the medium-temperature barrel pump liquid supply system through a pipeline; The air outlet of the medium-temperature barrel pump liquid supply system is connected to the low-temperature end inlet of the regenerator A (11) through a pipeline, and the liquid outlet is connected to the heat source end inlet of the regenerator B (19) through a pipeline; The low temperature end outlet of the regenerator A (11) is connected to the air intake of the parallel compressor unit through a pipeline; The heat source end outlet of the regenerator B (19) is connected to the heat source end inlet of the regenerator C (20) via a pipeline; The heat source outlet of the regenerator C (20) is connected to the electronic expansion valve C (21) and the liquid inlet of the low-temperature barrel pump liquid supply system in sequence through pipelines; The air outlet of the cryogenic barrel pump liquid supply system and the low-temperature end inlet of the regenerator B (19) are connected by a pipeline; The low temperature end outlet of the regenerator B (19) is connected to the solenoid valve (25) and the ejector throttling assembly in sequence through pipelines; The air outlet of the cryogenic barrel pump liquid supply system is connected to the low-temperature end inlet of the regenerator C (20) through a pipeline; The low temperature end outlet of the regenerator C (20) is connected to the air intake of the low temperature system compressor unit through a pipeline; The liquid supply port of the cryogenic barrel pump liquid supply system is connected to the heat source end inlet of the regenerator D (26) through a pipeline; The heat source end outlet of the regenerator D (26) is connected to the heat source end inlet of the regenerator E (27) via a pipeline; The heat source end outlet of the regenerator E (27) is connected to the electronic expansion valve D (28) and the liquid inlet of the quick freezing barrel pump liquid supply system in sequence through pipelines; The gas outlet of the quick freezing barrel pump liquid supply system is connected to the cold source inlet of the regenerator D (26) through a pipeline; The cold source outlet of the regenerator D (26) is connected to the solenoid valve (31) and the ejector throttling assembly via a pipeline; The gas outlet of the quick freezing barrel pump liquid supply system is connected to the cold source inlet of the regenerator E (27) through a pipeline; The cold source outlet of the regenerator E (27) is connected to the air intake of the quick freezing system compressor unit through a pipeline.

2. The CO2 sub- / cross-conversion multi-condition comprehensive application refrigeration system according to claim 1 is characterized in that: The quick freezing system compressor unit, low temperature system compressor unit and parallel compressor unit are all provided with a compressor and an oil separator; The quick freezing system compressor unit is composed of N quick freezing system compressors (1) connected to a quick freezing system compressor matching separator (4) through pipelines; The cryogenic system compressor unit is composed of N cryogenic system compressors (2) connected to the cryogenic system compressor matching oil separator (5) through pipelines; The parallel compressor unit also serves as a medium temperature system compressor unit. When there is no medium temperature load, it is used as a low-pressure parallel compressor to improve the system COP. The parallel compressor unit is composed of N medium temperature system compressors (3) connected to the oil separator (6) of the medium temperature system compressor through pipelines. The oil outlets of the quick freezing system compressor supporting separator (4), the low temperature system compressor supporting oil separator (5) and the medium temperature system compressor supporting oil separator (6) are connected to the oil inlet of the oil tank (52) via pipelines; The gas outlet of the oil tank (52) is connected to the stop valve (53) and the gas intake of the medium temperature system compressor (3) in sequence through pipelines; The oil outlet of the oil tank (52) is connected to the oil return ports of the medium temperature system compressor (3), the low temperature system compressor (2) and the quick freezing system compressor (1) via pipelines.

3. The CO2 sub- / cross-conversion multi-condition comprehensive application refrigeration system according to claim 1 is characterized in that: The ejector throttling assembly comprises: an ejector A (12), an electronic expansion valve A (13), an ejector B (17) and an electronic expansion valve B (18); The ejector A (12) and the electronic expansion valve A (13) are connected in parallel, and their inlets are connected to the outlet of the heat source end of the regenerator A (11) through a pipeline, and their outlets are connected to the liquid inlet of the medium-temperature barrel pump liquid supply system through a pipeline; The ejector B (17) and the electronic expansion valve B (18) are connected in parallel; their inlets are connected to the outlet of the heat source end of the regenerator A (11) through a pipeline, and their outlets are connected to the liquid inlet of the medium-temperature barrel pump liquid supply system through a pipeline; During operation, the control system automatically switches between transcritical and subcritical conditions based on changes in outdoor ambient temperature and exhaust pressure. An ejector is used during transcritical operation, and an electronic expansion valve is used during subcritical conditions or when only a medium-temperature system is used.

4. The CO2 sub- / cross-conversion multi-mode comprehensive application refrigeration system according to claim 1 is characterized in that: The medium-temperature barrel pump liquid supply system comprises: a medium-temperature low-pressure circulation barrel (14), a double-seat safety valve supporting a pressure relief solenoid valve A (15), a pressure regulating valve A (16), a medium-temperature system CO2 shielded pump (37), a medium-temperature system air return port (38), a medium-temperature system liquid supply port (39), a liquid level sensor supporting a liquid level switch and a liquid level gauge A (40) and a pressure regulating valve C (41); The liquid inlet of the medium-temperature low-pressure circulation barrel (14) is connected to the outlets of the ejector A (12), the electronic expansion valve A (13), the ejector B (17) and the electronic expansion valve B (18) through a pipeline; the gas outlet of the medium-temperature low-pressure circulation barrel (14) is connected to the low-temperature end inlet of the regenerator A (11) through a pipeline, and the liquid outlet is connected to the heat source end inlet of the regenerator B (19) through a pipeline; The medium-temperature low-pressure circulation barrel (14) is equipped with a double-seat safety valve, a pressure relief solenoid valve A (15), and a liquid level sensor, a liquid level switch and a liquid level gauge A (40). The medium-temperature low-pressure circulation barrel (14) is connected to the medium-temperature system CO2 shielded pump (37) and the medium-temperature system liquid supply port (39) in sequence through pipelines; A pressure regulating valve C (41) is provided between the medium-temperature low-pressure circulation barrel (14) and the liquid supply pipeline after the medium-temperature system CO2 shielded pump (37); The medium-temperature low-pressure circulation barrel (14) is connected to the pressure regulating valve A (16) and the low-temperature low-pressure circulation barrel (22) in sequence through pipelines; The medium-temperature low-pressure circulation barrel (14) is connected to the medium-temperature system air return port (38) via a pipeline; The medium temperature system air return port (38) and the medium temperature system liquid supply port (39) are connected to the terminal refrigeration evaporation equipment of the medium temperature system.

5. The CO2 sub- / cross-conversion multi-condition comprehensive application refrigeration system according to claim 1 is characterized in that: The cryogenic barrel pump liquid supply system comprises: a cryogenic and low-pressure circulation barrel (22), a double-seat safety valve supporting a pressure relief solenoid valve B (23), a pressure regulating valve B (24), a cryogenic system CO2 shielded pump (42), a cryogenic system air return port (43), a cryogenic system liquid supply port (44), a liquid level sensor supporting a liquid level switch and a liquid level gauge B (45), and a pressure regulating valve D (46); The liquid inlet of the low-temperature and low-pressure circulation barrel (22) is connected to the electronic expansion valve C (21) and the heat source outlet of the regenerator C (20) in sequence through pipelines, the liquid outlet is connected to the heat source inlet of the regenerator D (26) through pipelines, and the gas outlet is connected to the low-temperature inlet of the regenerator B (19) and the low-temperature inlet of the regenerator C (20) through pipelines respectively; The low-temperature and low-pressure circulation barrel (22) is equipped with a double-seat safety valve, a pressure relief solenoid valve B (23), and a liquid level sensor, a liquid level switch and a liquid level gauge B (45). The low-temperature and low-pressure circulation barrel (22) is connected to the low-temperature system CO2 shielded pump (42) and the low-temperature system liquid supply port (44) in sequence through pipelines; A pressure regulating valve D (46) is provided between the low-temperature and low-pressure circulation barrel (22) and the liquid supply pipeline after the low-temperature system CO2 shielded pump (42); The low-temperature and low-pressure circulation barrel (22) is connected to the pressure regulating valve B (24) and the quick freezing barrel pump liquid supply system in sequence through pipelines; The low-temperature and low-pressure circulation barrel (22) is connected to the low-temperature system air return port (43) via a pipeline; The low-temperature system air return port (43) and the low-temperature system liquid supply port (44) are connected to the low-temperature system terminal refrigeration evaporation equipment.

6. The CO2 sub- / cross-conversion multi-mode comprehensive application refrigeration system according to claim 1 is characterized in that: The quick freezing barrel pump liquid supply system comprises: a quick freezing low-pressure circulation barrel (29), a double-seat safety valve supporting a pressure relief solenoid valve C (30), a maintenance unit (32), a solenoid valve for maintaining the unit (33), an expansion valve for maintaining the unit (34), a heat exchanger for maintaining pressure (35), a pressure controller (36), a quick freezing system CO2 shielded pump (47), a quick freezing system air return port (48), a quick freezing system liquid supply port (49), a liquid level sensor supporting a liquid level switch and a liquid level gauge C (50) and a pressure regulating valve E (51); The liquid inlet of the quick-freezing low-pressure circulation barrel (29) is connected to the electronic expansion valve D (28) and the heat source outlet of the regenerator E (27) in sequence through pipelines, and the gas outlet is connected to the cold source inlet of the regenerator D (26) and the cold source inlet of the regenerator E (27) through pipelines respectively; The quick-freezing low-pressure circulation barrel (29) is equipped with a double-seat safety valve, a pressure relief solenoid valve C (30), and a liquid level sensor, a liquid level switch and a liquid level gauge C (50). The quick-freezing low-pressure circulation barrel (29) is connected to the quick-freezing system CO2 shielded pump (47) and the quick-freezing system liquid supply port (49) in sequence through pipelines; The air intake port of the maintenance unit (32) is connected to the air return port of the cold source end of the pressure maintenance heat exchanger (35) through a pipeline, and the liquid supply port is connected to the solenoid valve (33) for the maintenance unit, the expansion valve (34) for the maintenance unit, and the liquid inlet of the cold source end of the pressure maintenance heat exchanger (35) through a pipeline; The air inlet of the heat source end of the pressure-maintaining heat exchanger (35) is connected to the air outlet of the quick-freezing low-pressure circulation barrel (29) through a pipeline; the liquid return port of the heat source end of the pressure-maintaining heat exchanger (35) is connected to the liquid inlet of the quick-freezing low-pressure circulation barrel (29) through a pipeline; A pressure regulating valve E (51) is provided between the quick-freezing low-pressure circulation barrel (29) and the liquid supply pipeline after the quick-freezing system CO2 shielded pump (47); The quick-freezing low-pressure circulation barrel (29) is connected to the quick-freezing system air return port (48) via a pipeline; The quick freezing system air return port (48) and the quick freezing system liquid supply port (49) are connected to the refrigeration evaporation equipment at the end of the quick freezing system.

7. The CO2 sub- / cross-conversion multi-mode comprehensive application refrigeration system according to claim 1 is characterized in that: The heat recovery device assembly comprises: a domestic water heat recovery device (7), an evaporator defrost water heat recovery device (8), a floor antifreeze water heat recovery device (9), a domestic water cooling source end interface (54), an evaporator defrost water cooling source end interface (55) and a floor antifreeze water cooling source end interface (56); The domestic water heat recovery device (7), the evaporator defrosting water heat recovery device (8), and the floor antifreeze water heat recovery device (9) are connected in sequence through pipelines; The heat source inlet of the domestic water heat recovery device (7) is connected to the exhaust gas converging pipeline of the quick freezing system compressor unit, the low temperature system compressor unit and the parallel compressor unit through a pipeline; The heat source outlet of the floor antifreeze water heat recovery device (9) is connected to the air inlet of the gas cooler (10) through a pipeline; The domestic water cooling source end interface (54) is connected to the domestic water heat recovery device (7) via a pipeline; The evaporator defrosting water cooling source end interface (55) is connected to the evaporator defrosting water heat recovery device (8) through a pipeline; The floor antifreeze water cooling source end interface (56) is connected to the floor antifreeze water heat recovery device (9) through a pipeline.

8. The CO2 sub- / cross-conversion multi-mode comprehensive application refrigeration system according to claim 7 is characterized in that: The domestic water heat recovery device (7) is connected in parallel to the inlet and outlet pipes at the heat source end of the domestic water heat recovery device (7); The electric regulating valve B (58) is connected in parallel to the inlet and outlet pipes of the heat source end of the evaporator defrosting water heat recovery device (8); An electric regulating valve C (59) is connected in parallel to the inlet and outlet pipes of the heat source end of the floor antifreeze water heat recovery device (9).

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