Carbon dioxide heat pump heat storage system suitable for cross-seasonal regulation and operation method thereof

Abstract

The invention belongs to the technical field of industrial green electricity heat storage and cold storage, and particularly relates to a carbon dioxide heat pump heat storage system suitable for cross-seasonal regulation and control and an operation method thereof, the carbon dioxide heat pump heat storage system comprises a high-temperature compressor, a high-temperature heat exchanger, a medium-high temperature regenerator, a medium-temperature heat exchanger, a low-temperature regenerator, a low-temperature expansion machine and a low-temperature heat exchanger; the connecting state of a hot flow outlet of the medium-temperature heat exchanger, a hot flow inlet of the low-temperature heat regenerator and an inlet of the low-temperature expansion machine is adjusted, and the connecting state of a cold flow outlet of the low-temperature heat exchanger, a cold flow inlet of the low-temperature heat regenerator and a cold flow inlet of the medium-high temperature heat regenerator is adjusted; the flow of the circulating working medium in the low-temperature area subsystem is regulated and controlled, then a system operation mode adapting to seasonal changes is constructed, it can be guaranteed that operation parameters of all devices in the medium-high-temperature area subsystem are constant, and the influence of the environment is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial green power heat and cold storage, and particularly relates to a carbon dioxide heat pump heat storage system suitable for cross-season regulation and its operation method. Background Art

[0002] With the development of power generation technology, existing research has shown that using supercritical carbon dioxide instead of steam as the circulating working fluid in a generator set has advantages such as high cycle efficiency, compact equipment structure, and low initial capital investment within a certain power range. Therefore, the supercritical carbon dioxide cycle power generation system is a power generation method with very promising technology.

[0003] Large-scale thermal energy storage technology is one of the key technologies to solve the intermittency of renewable energy, shift power peaks, and match user load demands; currently, in the process of thermal energy storage and conversion and utilization, a heat pump is a high-energy-efficiency and high-cost-benefit heating solution; among them, industrial high-temperature heat pumps generally consist of a compressor, a high-temperature heat exchanger, a low-temperature heat exchanger, a regenerator, and a low-temperature expansion mechanism, and are used to provide thermal energy to industrial systems or provide cold energy to office buildings and large cold storages, etc.; therefore, a heat pump cycle using carbon dioxide as the circulating working fluid can achieve efficient heat transfer and storage between the high-temperature heat storage temperature zone and the heat storage medium, and can also achieve a good match between the low-temperature cold storage temperature zone and the environment or cold source; however, the cold source of existing industrial heat pumps usually mainly relies on the environment, and affected by seasonal changes, its heating load changes greatly, and each device in the system requires strong variable operating conditions ability, resulting in difficulties in regulating the heat pump system or the problem of unstable operation. Summary of the Invention

[0004] Aiming at the technical problems existing in the prior art, the present invention provides a carbon dioxide heat pump heat storage system suitable for cross-season regulation and its operation method to solve the technical problems that the cold source of existing industrial heat pumps usually mainly relies on the environment, its heating load changes greatly, and there are difficulties in regulation or unstable operation.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: The present invention provides a carbon dioxide heat pump heat storage system suitable for cross-season regulation, including a high-temperature compressor, a high-temperature heat exchanger, a medium-high temperature regenerator, a medium-temperature heat exchanger, a low-temperature regenerator, a low-temperature expander, and a low-temperature heat exchanger; The outlet of the high-temperature compressor is connected to the hot stream inlet of the high-temperature heat exchanger, the hot stream outlet of the high-temperature heat exchanger is connected to the hot stream inlet of the medium-high temperature regenerator, and the hot stream outlet of the medium-high temperature regenerator is connected to the hot stream inlet of the medium-temperature heat exchanger; the hot stream outlet of the medium-temperature heat exchanger is connected to both the hot stream inlet of the low-temperature regenerator and the inlet of the low-temperature expander; the hot stream outlet of the low-temperature regenerator is also connected to the inlet of the low-temperature expander; The outlet of the low-temperature expander is connected to the cold stream inlet of the low-temperature heat exchanger. The cold stream outlet of the low-temperature heat exchanger is connected to both the cold stream inlet of the low-temperature regenerator and the cold stream inlet of the medium-high temperature regenerator. The cold stream outlet of the low-temperature regenerator is also connected to the cold stream inlet of the medium-high temperature regenerator. The cold stream outlet of the medium-high temperature regenerator is connected to the inlet of the high-temperature compressor.

[0006] Further, it also includes a hot stream inlet valve and a cold stream inlet valve; The inlet of the hot stream inlet valve is connected to the hot stream outlet of the medium-temperature heat exchanger, and the outlet of the hot stream inlet valve is connected to the hot stream inlet of the low-temperature regenerator. The inlet of the cold stream inlet valve is connected to the cold stream outlet of the low-temperature heat exchanger, and the outlet of the cold stream inlet valve is connected to the cold stream inlet of the low-temperature regenerator.

[0007] Further, it also includes a hot side bypass valve and a cold side bypass valve; The inlet of the hot side bypass valve is connected to the hot stream outlet of the medium-temperature heat exchanger, and the outlet of the hot side bypass valve is connected to the inlet of the low-temperature expander. The inlet of the cold side bypass valve is connected to the cold stream outlet of the low-temperature heat exchanger, and the outlet of the cold side bypass valve is connected to the cold stream inlet of the medium-high temperature regenerator.

[0008] Further, the switching states of the hot stream inlet valve and the hot side bypass valve are mutually exclusive.

[0009] Further, the switching states of the cold stream inlet valve and the cold side bypass valve are mutually exclusive.

[0010] Further, the high-temperature compressor is also connected to an electric motor; wherein, the high-temperature compressor is a turbine compressor.

[0011] Further, the low-temperature expander is also connected to a generator; wherein, the low-temperature expander is a turbine expander.

[0012] The present invention also provides an operation method for a carbon dioxide heat pump heat storage system suitable for cross-seasonal regulation, including a winter operation mode and a summer operation mode; In the winter operation mode, the connection state between the hot stream outlet of the medium-temperature heat exchanger and the hot stream inlet of the low-temperature regenerator is in communication, and the connection state between the hot stream outlet of the medium-temperature heat exchanger and the inlet of the low-temperature expander is disconnected; the connection state between the cold stream outlet of the low-temperature heat exchanger and the cold stream inlet of the low-temperature regenerator is in communication, and the connection state between the cold stream outlet of the low-temperature heat exchanger and the cold stream inlet of the medium-high temperature regenerator is disconnected; In the summer operation mode, the connection between the hot fluid stream outlet of the medium-temperature heat exchanger and the hot fluid stream inlet of the low-temperature regenerator is disconnected, and the connection between the hot fluid stream outlet of the medium-temperature heat exchanger and the inlet of the low-temperature expander is connected; the connection between the cold fluid stream outlet of the low-temperature heat exchanger and the cold fluid stream inlet of the low-temperature regenerator is disconnected, and the connection between the cold fluid stream outlet of the low-temperature heat exchanger and the cold fluid stream inlet of the medium-high temperature regenerator is connected.

[0013] Further, when the ambient temperature is lower than 0°C, the winter operation mode is enabled.

[0014] Further, when the ambient temperature is higher than 25°C, the summer operation mode is enabled.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The carbon dioxide heat pump thermal energy storage system applicable to cross-seasonal regulation and its operation method provided by the present invention connect the hot fluid stream outlet of the medium-temperature heat exchanger to both the hot fluid stream inlet of the low-temperature regenerator and the inlet of the low-temperature expander, and connect the cold fluid stream outlet of the low-temperature heat exchanger to both the cold fluid stream inlet of the low-temperature regenerator and the cold fluid stream inlet of the medium-high temperature regenerator. By adjusting the connection states of the hot fluid stream outlet of the medium-temperature heat exchanger to the hot fluid stream inlet of the low-temperature regenerator and the inlet of the low-temperature expander, and adjusting the connection states of the cold fluid stream outlet of the low-temperature heat exchanger to the cold fluid stream inlet of the low-temperature regenerator and the cold fluid stream inlet of the medium-high temperature regenerator, the flow of the circulating working fluid in the low-temperature subsystem is regulated, and then the system operation mode adapted to seasonal changes is constructed, which can ensure the constant operation parameters of each device in the medium-high temperature subsystem and reduce the influence of the environment; at the same time, it can effectively avoid the drastic changes in the operating states of the high-temperature compressor, high-temperature thermal energy storage and medium-temperature thermal energy storage during the transformation of different operation modes, and realize the stable thermal energy storage of the system; among them, in the winter operation mode, the low-temperature regenerator is connected to the cycle, and the cold quantity is recovered through the low-temperature regenerator, reducing the operating temperature of the low-temperature expander, ensuring the temperature matching between the low-temperature heat exchanger and the cold source, and avoiding the phenomenon of insufficient heat supply or the system being unable to supply heat due to too low cold source temperature in winter; in the summer operation mode, the low-temperature regenerator is isolated from the cycle, increasing the output power of the low-temperature expander, achieving a significant energy-saving effect and improving the energy efficiency of the system. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 A carbon dioxide heat pump heat storage system applicable to cross-season regulation provided by the present invention.

[0018] Among them, 1 is a high-temperature compressor, 2 is a high-temperature heat exchanger, 3 is a medium-high temperature recuperator, 4 is a medium-temperature heat exchanger, 5 is a low-temperature recuperator, 6 is a low-temperature expander, 7 is a low-temperature heat exchanger, 8 is a motor, and 9 is a generator; 51h is a hot stream inlet valve, and 51c is a cold stream inlet valve; 52h is a hot side bypass valve, and 52c is a cold side bypass valve. Specific embodiments

[0019] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer and more understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application; obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0020] As shown in the attached Figure 1 As shown in the figure, the present invention provides a carbon dioxide heat pump heat storage system applicable to cross-season regulation, including a medium-high temperature zone subsystem, a low-temperature zone subsystem, a hot stream inlet valve 51h, a cold stream inlet valve 51c, a hot side bypass valve 52h, and a cold side bypass valve 52c; the medium-high temperature zone subsystem is used to store high-quality heat and medium-temperature heat or supply hot water to users; the low-temperature zone subsystem is used for cold storage or as a cold source.

[0021] The medium-high temperature zone subsystem includes a high-temperature compressor 1, a high-temperature heat exchanger 2, a medium-high temperature recuperator 3, and a medium-temperature heat exchanger 4; the outlet of the high-temperature compressor 1 is connected to the hot stream inlet of the high-temperature heat exchanger 2, the hot stream outlet of the high-temperature heat exchanger 2 is connected to the hot stream inlet of the medium-high temperature recuperator 3, and the hot stream outlet of the medium-high temperature recuperator 3 is connected to the hot stream inlet of the medium-temperature heat exchanger 4; the hot stream outlet of the medium-temperature heat exchanger 4 is connected to the hot stream inlet of the low-temperature recuperator 5, and the hot stream outlet of the medium-temperature heat exchanger 4 is also connected to the inlet of the low-temperature expander 6 in the low-temperature zone subsystem; the cold stream inlet of the medium-high temperature recuperator 3 is connected to the cold stream outlet of the low-temperature recuperator 5 in the low-temperature zone subsystem, and the cold stream inlet of the medium-high temperature recuperator 3 is also connected to the cold stream outlet of the low-temperature heat exchanger 7 in the low-temperature zone subsystem; the cold stream outlet of the medium-high temperature recuperator 3 is connected to the inlet of the high-temperature compressor 1.

[0022] The high-temperature compressor 1 is also connected to an electric motor 8, and the electric motor 8 is used to consume electric energy to drive the high-temperature compressor 1 to do work; preferably, the high-temperature compressor 1 is a turbine compressor; the cold fluid inlet of the high-temperature heat exchanger 2 is used to be connected to the outlet of the high-temperature heat storage medium source, and the cold fluid outlet of the high-temperature heat exchanger 2 is used to be connected to the inlet of the high-temperature heat storage medium source; wherein, the high-temperature heat storage medium source stores a high-temperature heat storage medium, so that the high-temperature heat storage medium exchanges heat with the high-quality heat in the high-temperature heat exchanger 2 to achieve the storage of high-quality heat; the cold fluid inlet of the medium-temperature heat exchanger 4 is used to be connected to the outlet of the medium-temperature heat storage medium source, and the cold fluid outlet of the medium-temperature heat exchanger 4 is used to be connected to the inlet of the medium-temperature heat storage medium source; wherein, the medium-temperature heat storage medium source stores a medium-temperature heat storage medium, so that the medium-temperature heat storage medium exchanges heat with the medium-temperature heat flow in the medium-temperature heat exchanger 4 to achieve the storage of medium-temperature heat; the medium-temperature heat storage medium source can be a hot water supply source for users to supply hot water to users.

[0023] The low-temperature zone subsystem includes a low-temperature recuperator 5, a low-temperature expander 6 and a low-temperature heat exchanger 7; the hot fluid inlet of the low-temperature recuperator 5 is connected to the hot fluid outlet of the medium-temperature heat exchanger 4, the hot fluid outlet of the low-temperature recuperator 5 is connected to the inlet of the low-temperature expander 6, the outlet of the low-temperature expander 6 is connected to the cold fluid inlet of the low-temperature heat exchanger 7, and the cold fluid outlet of the low-temperature heat exchanger 7 is connected to both the cold fluid inlet of the low-temperature recuperator 5 and the cold fluid inlet of the medium-high temperature recuperator 3; the cold fluid outlet of the low-temperature recuperator 5 is also connected to the cold fluid inlet of the medium-high temperature recuperator 3.

[0024] The low-temperature expander 6 is also connected to a generator 9, and the generator is driven to work through the low-temperature expander 6 to output power; preferably, the low-temperature expander 6 is a turbine expander; the hot fluid inlet of the low-temperature heat exchanger 7 is used to be connected to the outlet of the cold source, and the hot fluid outlet of the low-temperature heat exchanger 7 is used to be connected to the inlet of the cold source.

[0025] In the present invention, the hot fluid inlet valve 51h is arranged between the hot fluid outlet of the medium-temperature heat exchanger 4 and the hot fluid inlet of the low-temperature heat exchanger 5; specifically, the inlet of the hot fluid inlet valve 51h is connected to the hot fluid outlet of the medium-temperature heat exchanger 4, and the outlet of the hot fluid inlet valve 51h is connected to the hot fluid inlet of the low-temperature recuperator 5; the cold fluid inlet valve 51c is arranged between the cold fluid outlet of the low-temperature heat exchanger 7 and the cold fluid inlet of the low-temperature recuperator 5; specifically, the inlet of the cold fluid inlet valve 51c is connected to the cold fluid outlet of the low-temperature heat exchanger 7, and the outlet of the cold fluid inlet valve 51c is connected to the cold fluid inlet of the low-temperature recuperator 5.

[0026] The hot-side bypass valve 52h is arranged between the hot fluid stream outlet of the medium-temperature heat exchanger 4 and the inlet of the low-temperature expander 6; specifically, the inlet of the hot-side bypass valve 52h is connected to the hot fluid stream outlet of the medium-temperature heat exchanger 4, and the outlet of the hot-side bypass valve 52h is connected to the inlet of the low-temperature expander 6; the cold-side bypass valve 52c is arranged between the cold fluid stream outlet of the low-temperature heat exchanger 7 and the cold fluid stream inlet of the medium-high temperature regenerator 3; specifically, the inlet of the cold-side bypass valve 52c is connected to the cold fluid stream outlet of the low-temperature heat exchanger 7, and the outlet of the cold-side bypass valve 52c is connected to the cold fluid stream inlet of the medium-high temperature regenerator 3.

[0027] It should be noted that the hot-side bypass valve 52h is arranged in parallel on the hot fluid stream side pipeline of the low-temperature heat exchanger 5, and the cold-side bypass valve 52c is arranged in parallel on the cold fluid stream side pipeline of the low-temperature heat exchanger 5, and the on-off states of the hot fluid stream inlet valve 51h and the hot-side bypass valve 52h are mutually exclusive, and the on-off states of the cold fluid stream inlet valve 51c and the cold-side bypass valve 52c are mutually exclusive; that is, when the carbon dioxide heat pump energy storage system operates stably, when the on-off states of the hot fluid stream inlet valve 51h and the cold fluid stream inlet valve 51c are open, the on-off states of the hot-side bypass valve 52h and the cold-side bypass valve 52c are closed; or, when the hot fluid stream inlet valve 51h and the cold fluid stream inlet valve 51c are opened simultaneously, the hot-side bypass valve 52h and the cold-side bypass valve 52c are closed to ensure that the low-temperature regenerator 5 is completely isolated from the system cycle.

[0028] Working principle and operation method: The operation method of the carbon dioxide heat pump energy storage system applicable to cross-seasonal regulation described in the present invention includes a winter operation mode and a summer operation mode; by different operation modes in different seasons to adapt to the changes in the environment of different seasons; among them, when the ambient temperature is lower than 0 °C, the winter operation mode is enabled; when the ambient temperature is higher than 25 °C, the summer operation mode is enabled; it should be noted that when the ambient temperature is between 0-25 °C, the winter operation mode or the summer operation mode is enabled according to the actual needs of the user; among them, the system performance coefficient is higher when the summer operation mode is enabled, and it has better economy.

[0029] In the winter operation mode, the specific operations include: By controlling the switch state of the hot stream inlet valve 51h to open, the connection state between the hot stream outlet of the medium-temperature heat exchanger 4 and the hot stream inlet of the low-temperature recuperator 5 is made to be in communication; by controlling the switch state of the hot-side bypass valve 52h to closed, the connection state between the hot stream outlet of the medium-temperature heat exchanger 4 and the inlet of the low-temperature expander 6 is made to be disconnected; by controlling the switch state of the cold stream inlet valve 51c to open, the connection state between the cold stream outlet of the low-temperature heat exchanger 7 and the cold stream inlet of the low-temperature recuperator 5 is made to be in communication; by controlling the switch state of the cold-side bypass valve 52c to closed, the connection state between the cold stream outlet of the low-temperature heat exchanger 7 and the cold stream inlets of the medium-high temperature recuperator 3 being connected is made to be disconnected.

[0030] It should be noted that in the winter operation mode, the high-temperature and high-pressure carbon dioxide circulating working medium discharged from the high-temperature compressor 1 transfers heat to the high-temperature heat storage medium through the high-temperature heat exchanger 2, and then part of the heat is recovered by the medium-high temperature recuperator 3; the medium-temperature and high-pressure circulating working medium coming out of the medium-high temperature recuperator 3 transfers heat to the medium-temperature heat storage medium through the medium-temperature heat exchanger 4, the temperature of the circulating working medium is further reduced, and it enters the low-temperature recuperator 5 through the hot stream inlet valve 51h and is cooled to high-pressure liquid; the high-pressure liquid working medium flowing out of the low-temperature recuperator 5 expands, cools, and reduces pressure through the low-temperature expander 6 and drives the impeller of the generator 9 to output power; the low-temperature and low-pressure circulating working medium flowing out of the low-temperature expander 6 enters the low-temperature heat exchanger 7, the low-temperature and low-pressure circulating working medium exchanges heat with the cold source in the low-temperature heat exchanger 7 and becomes low-pressure gas, and then passes through the low-temperature recuperator 5 and the medium-high temperature recuperator 3 in sequence through the cold stream inlet valve 51c and enters the high-temperature compressor 1, forming a closed working cycle loop.

[0031] In the present invention, by controlling the temperature between the medium-temperature heat exchanger 4 and the hot stream inlet valve 51h, the temperature parameters of each device in the medium-high temperature zone subsystem can be made constant, ensuring the stable operation of the high-temperature compressor 1 to maintain the stability of the high-temperature heat storage load and the medium-temperature heat storage load; if the temperature of the cold source is further reduced, the temperature between the low-temperature heat exchanger 7 and the cold stream inlet valve 51c can be adjusted to be smaller, increasing the heat regeneration load of the low-temperature recuperator 5, reducing the temperature at the inlet of the low-temperature expander 6, making the temperature at the outlet of the low-temperature expander 6 lower, not only enabling the system to achieve heat exchange at a lower temperature, but also reducing the gas content rate at the outlet of the low-temperature expander 6, increasing the refrigeration capacity of the low-temperature heat exchanger 7, and improving the heat supply capacity and operation reliability of the system in winter.

[0032] In the summer operation mode, the specific operations include: By controlling the on-off state of the hot stream inlet valve 51h to closed, the connection between the hot stream outlet of the medium-temperature heat exchanger 4 and the hot stream inlet of the low-temperature recuperator 5 is disconnected; by controlling the on-off state of the hot-side bypass valve 52h to open, the connection between the hot stream outlet of the medium-temperature heat exchanger 4 and the inlet of the low-temperature expander 6 is connected; by controlling the on-off state of the cold stream inlet valve 51c to closed, the connection between the cold stream outlet of the low-temperature heat exchanger 7 and the cold stream inlet of the low-temperature recuperator 5 is disconnected; by controlling the on-off state of the cold-side bypass valve 52c to open, the connection between the cold stream outlet of the low-temperature heat exchanger 7 and the cold stream inlets of the medium-high temperature recuperator 3 are connected.

[0033] It should be noted that when the ambient temperature is higher than 25 °C, the operation mode of the system is switched to the summer operation mode; specifically, the hot-side bypass valve 52h and the cold-side bypass valve 52c connected in parallel with the low-temperature recuperator 5 are opened, and the hot stream inlet valve 51h and the cold stream inlet valve 51c are closed to isolate the low-temperature recuperator 5 from the cycle; it is worth noting that there are two reasons for switching to the summer operation mode: on the one hand, the equipment operation parameters in the medium-high temperature region are constant in the two operation modes, which do not affect the high-temperature heat storage load and the medium-temperature heat storage load of the system and do not change the stable operation state of the high-temperature compressor 1; on the other hand, in order to ensure the matching of the heat exchange process between the low-temperature heat exchanger 7 and the cold source, so as to improve the cycle energy efficiency of the system.

[0034] In the carbon dioxide heat pump heat storage system of the present invention, the high-temperature compressor 1, the high-temperature heat exchanger 2, the medium-high temperature recuperator 3, the medium-temperature heat exchanger 4, the hot stream inlet valve 51h, the low-temperature recuperator 5, the low-temperature expander 6, the low-temperature heat exchanger 7, and the cold stream inlet valve 51c are connected to form a closed-loop cycle, and the hot-side bypass valve 52h and the cold-side bypass valve 52c are arranged in parallel with the low-temperature recuperator 5; in the present invention, the high-temperature heat exchanger 2 is used to transfer and store high-temperature heat to the heat storage medium, the medium-temperature heat exchanger 4 is used to transfer and store medium-temperature heat to the heat storage medium, and the high-temperature heat exchanger 2 and the medium-temperature heat exchanger 4 can simultaneously achieve continuous and constant heat storage; the low-temperature recuperator 5 is used to cool the high-pressure working medium at the inlet of the low-temperature expander 6 to a liquid state by using the remaining cold of the low-temperature heat exchanger 7, further reducing the temperature at the outlet of the low-temperature expander 6, thereby enhancing the heat absorption capacity of the low-temperature heat exchanger 7; connecting the low-temperature recuperator 5 in parallel with the hot-side bypass valve 52h and the cold-side bypass valve 52c can realize the conversion of the operation mode in different seasons and improve the comprehensive energy efficiency of the system; among them, the high-temperature compressor 1 can maintain a stable operation state in two different operation modes of the system.

[0035] The carbon dioxide heat pump energy storage system suitable for cross-seasonal regulation according to the present invention constructs the winter mode and summer mode of the heat pump cycle by regulating the flow of the circulating working fluid in the low-temperature subsystem, effectively solving the problem of insufficient heat supply or inability to supply heat constantly in the heat pump cycle under low ambient temperature in winter, and at the same time ensuring the stable operation of the high-temperature compressor and the medium-high temperature heat storage load in the high-temperature area; specifically, by adopting a low-temperature recuperator in parallel with a bypass valve, the conversion between the winter and summer operation modes can be realized, which can ensure the constant operation parameters of each device in the medium-high temperature area, avoid the drastic changes in the operation states of the high-temperature compressor, high-temperature heat storage and medium-temperature heat storage during the conversion between the two modes, and realize the stable heat storage of the system; among them, in the winter operation mode, the cold quantity is recovered by the low-temperature recuperator, the operating temperature of the low-temperature expander is reduced, the temperature matching between the low-temperature heat exchanger and the cold source is ensured, and the problem of insufficient heat supply or inability of the system to supply heat caused by too low cold source temperature in winter is solved; in the summer operation mode, the low-temperature recuperator is isolated from the cycle by the bypass valve, the output power of the low-temperature expander is increased, a remarkable energy-saving effect is realized, and the energy efficiency of the system is improved.

[0036] It should be noted that the system according to the present invention can ensure the constant operation parameters of each device in the medium-high temperature area in both operation modes, avoid the drastic changes in the device operation states during the conversion between the two modes, solve the problem of insufficient heat supply or inability of the system to supply heat caused by too low cold source temperature in winter, and improve the energy efficiency of the system.

[0037] The above embodiments are only one of the implementation manners capable of realizing the technical solution of the present invention. The scope of protection required by the present invention is not only limited by this embodiment, but also includes any changes, substitutions and other implementation manners that are easily conceivable by those skilled in the art within the technical scope disclosed by the present invention.

Claims

1. A carbon dioxide heat pump heat storage system suitable for cross-season regulation, characterized in that: It comprises a high-temperature compressor (1), a high-temperature heat exchanger (2), a medium-high temperature heat regenerator (3), a medium-temperature heat exchanger (4), a low-temperature heat regenerator (5), a low-temperature expander (6) and a low-temperature heat exchanger (7); The outlet of the high-temperature compressor (1) is connected to the hot flow inlet of the high-temperature heat exchanger (2), the hot flow outlet of the high-temperature heat exchanger (2) is connected to the hot flow inlet of the medium-high temperature heat exchanger (3), the hot flow outlet of the medium-high temperature heat exchanger (3) is connected to the hot flow inlet of the medium-temperature heat exchanger (4); the hot flow outlet of the medium-temperature heat exchanger (4) is connected to both the hot flow inlet of the low-temperature heat exchanger (5) and the inlet of the low-temperature expander (6); the hot flow outlet of the low-temperature heat exchanger (5) is also connected to the inlet of the low-temperature expander (6); The outlet of the low-temperature expander (6) is connected to the cold stream inlet of the low-temperature heat exchanger (7), the cold stream outlet of the low-temperature heat exchanger (7) is connected to the cold stream inlet of the low-temperature regenerator (5) and the cold stream inlet of the medium-high temperature regenerator (3), the cold stream outlet of the low-temperature regenerator (5) is also connected to the cold stream inlet of the medium-high temperature regenerator (3); the cold stream outlet of the medium-high temperature regenerator (3) is connected to the inlet of the high-temperature compressor (1).

2. A carbon dioxide heat pump heat storage system suitable for cross-season regulation according to claim 1, characterized in that: Also included is a hot stream inlet valve (51h) and a cold stream inlet valve (51c); The inlet of the hot stream inlet valve (51h) is connected to the hot stream outlet of the medium-temperature heat exchanger (4), and the outlet of the hot stream inlet valve (51h) is connected to the hot stream inlet of the low-temperature regenerator (5); the inlet of the cold stream inlet valve (51c) is connected to the cold stream outlet of the low-temperature heat exchanger (7), and the outlet of the cold stream inlet valve (51c) is connected to the cold stream inlet of the low-temperature regenerator (5).

3. A carbon dioxide heat pump heat storage system suitable for cross-season regulation according to claim 2, characterized in that: Also includes a hot side bypass valve (52h) and a cold side bypass valve (52c); The inlet of the hot side bypass valve (52h) is connected to the hot flow outlet of the medium-temperature heat exchanger (4), and the outlet of the hot side bypass valve (52h) is connected to the inlet of the low-temperature expander (6); the inlet of the cold side bypass valve (52c) is connected to the cold flow outlet of the low-temperature heat exchanger (7), and the outlet of the cold side bypass valve (52c) is connected to the cold flow inlet of the medium- and high-temperature regenerator (3).

4. The carbon dioxide heat pump heat storage system suitable for cross-seasonal regulation according to claim 3 is characterized in that: The switching states of the hot stream inlet valve (51h) and the hot side bypass valve (52h) are mutually exclusive.

5. The carbon dioxide heat pump heat storage system suitable for cross-season regulation according to claim 3, characterized in that: The switching states of the cold stream inlet valve (51c) and the cold side bypass valve (52c) are mutually exclusive.

6. The carbon dioxide heat pump heat storage system suitable for cross-seasonal regulation according to claim 1, characterized in that: The high-temperature compressor (1) is also connected to an electric motor (8); wherein the high-temperature compressor (1) is a turbine compressor.

7. The carbon dioxide heat pump heat storage system suitable for cross-season regulation according to claim 1, characterized in that: The low-temperature expander (6) is also connected to a generator (9); wherein the low-temperature expander (6) is a turbine expander.

8. The method for operating a carbon dioxide heat pump heat storage system suitable for cross-season regulation according to any one of claims 1 to 7, characterized in that: Includes winter operation mode and summer operation mode; In the winter operation mode, the connection state between the hot flow outlet of the medium-temperature heat exchanger (4) and the hot flow inlet of the low-temperature regenerator (5) is connected, and the connection state between the hot flow outlet of the medium-temperature heat exchanger (4) and the inlet of the low-temperature expander (6) is disconnected; the connection state between the cold flow outlet of the low-temperature heat exchanger (7) and the cold flow inlet of the low-temperature regenerator (5) is connected, and the connection state between the cold flow outlet of the low-temperature heat exchanger (7) and the cold flow inlet of the medium- and high-temperature regenerator (3) is disconnected; In the summer operation mode, the connection state between the hot flow outlet of the medium-temperature heat exchanger (4) and the hot flow inlet of the low-temperature regenerator (5) is disconnected, and the connection state between the hot flow outlet of the medium-temperature heat exchanger (4) and the inlet of the low-temperature expander (6) is connected; the connection state between the cold flow outlet of the low-temperature heat exchanger (7) and the cold flow inlet of the low-temperature regenerator (5) is disconnected, and the connection state between the cold flow outlet of the low-temperature heat exchanger (7) and the cold flow inlet of the medium- and high-temperature regenerator (3) is connected.

9. The method for operating a carbon dioxide heat pump heat storage system suitable for cross-seasonal regulation according to claim 8, characterized in that: When the ambient temperature is below 0°C, winter operation mode is enabled.

10. The method for operating a carbon dioxide heat pump heat storage system suitable for cross-season regulation according to claim 8, characterized in that: When the ambient temperature is higher than 25°C, summer operation mode is enabled.

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