A secondary loop thermal management system for CO2 heat pump air conditioners

Abstract

This invention belongs to the field of thermal management technology for rail vehicles, and discloses a secondary loop thermal management system for CO2 heat pump air conditioning, comprising: a CO2 processing module, including a compressor, a gas cooler, a throttling valve, an evaporator, and a gas-liquid separator; an outdoor air module, including a first heat exchanger and a second heat exchanger; an indoor air module, including a cooling module and a heating module; the heating module includes a third heat exchanger and a fourth heat exchanger, and the cooling module includes a fifth heat exchanger and a sixth heat exchanger; a drinking water module, including a heater; and an electrical and waste heat recovery module, including a transformer converter, a seventh heat exchanger, and a high-temperature energy storage device. The technical solution provided by this invention can achieve full energy recovery and cascaded energy utilization, achieving energy-saving and environmentally friendly effects; it can reduce the economic cost of CO2 heat pump air conditioning systems for rail vehicles and improve operational safety.

Description

Technical Field

[0001] This invention belongs to the field of thermal management technology for rail vehicles, and specifically relates to a secondary loop thermal management system for CO2 heat pump air conditioning. Background Technology

[0002] Currently, rail vehicles have become one of the most important means of transportation for convenient travel, but they have also caused increasingly significant energy consumption and carbon emissions. Therefore, it is urgent to propose a new thermal management strategy to address the energy problems and carbon emission challenges faced in the heating and cooling supply process of rail vehicles.

[0003] In current technologies, most rail vehicles in operating environments have been converted to electric drive, and the numerous electrical devices often generate substantial amounts of waste heat. Compared to typical small passenger vehicles, rail vehicles have higher heat loads and greater thermal inertia, resulting in significantly increased waste heat. If this waste heat is not recovered and utilized, it represents a substantial energy loss, hindering the achievement of dual-carbon goals and better energy conservation and environmental protection. Current rail vehicle technologies employ relatively simple thermal management systems, merely collecting the generated waste heat and discharging it into the outdoor environment to improve the thermal stability and safety of the rail vehicle's operating environment. However, it is evident that a large amount of waste heat is not recovered through any means, resulting in energy waste. Energy management and cascaded energy recovery and utilization on rail vehicles are crucial for improving energy efficiency.

[0004] Furthermore, driven by international legislation such as the Kigali Amendment to the Montreal Protocol, and to meet the demand for new refrigerant alternatives, CO2 heat pump air conditioning systems, which offer significant heating advantages at low temperatures, have been introduced into some rail vehicles. In the currently used direct CO2 heat pump air conditioning systems, the CO2 refrigerant directly exchanges heat with both the indoor and outdoor environments, thus requiring a large quantity of CO2 piping components with stringent high-pressure resistance requirements. The commonly used copper piping is expensive, increasing the overall cost of CO2 heat pump air conditioning. Moreover, considering the numerous joints required to connect the distributed thermal management equipment and piping, a malfunction at these joints or equipment could lead to significant leaks into the passenger compartment, posing a risk of suffocation.

[0005] In summary, in order to better utilize the excellent low-temperature heating efficiency of CO2, rail vehicles urgently need new thermal management systems and control methods to solve the aforementioned technical problems such as insufficient waste heat recovery and utilization, high cost of using the new refrigerant CO2, and poor safety. Summary of the Invention

[0006] The purpose of this invention is to provide a secondary loop thermal management system and its control method for CO2 heat pump air conditioning, to solve the technical problems of insufficient waste heat recovery and utilization and high cost of using the new refrigerant CO2 in existing technologies. The technical solution provided by this invention can achieve full energy recovery and energy cascade utilization, achieving energy-saving and environmental protection effects; it can reduce the economic cost of CO2 heat pump air conditioning systems for rail vehicles and improve operational safety.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a secondary loop thermal management system for CO2 heat pump air conditioners, comprising:

[0009] The CO2 processing module includes a compressor, a gas cooler, a throttle valve, an evaporator, and a gas-liquid separator;

[0010] The outdoor air module includes a first heat exchanger and a second heat exchanger;

[0011] An indoor air module includes a cooling module and a heating module; wherein the heating module includes a third heat exchanger and a fourth heat exchanger, and the cooling module includes a fifth heat exchanger and a sixth heat exchanger;

[0012] Drinking water module, including heater;

[0013] Electrical and waste heat recovery modules, including transformer converter, seventh heat exchanger and high-temperature energy storage device;

[0014] in,

[0015] In the CO2 circulation pipeline, the compressor outlet is connected to the compressor inlet in sequence through the first heat exchange channel of the gas cooler, the throttle valve, the first heat exchange channel of the evaporator, and the gas-liquid separator.

[0016] In the water circulation pipeline, the inlet of the second heat exchange channel of the gas cooler is connected to port a of the second four-way valve, and the outlet is connected to port a of the first four-way valve on one hand, and on the other hand, it is connected to port a of the first four-way valve after passing through the fifth solenoid valve and the heater in sequence; port b of the first four-way valve is connected to port b of the second four-way valve through the first heat exchanger, port c of the first four-way valve is connected to port c of the three-way valve, port d of the first four-way valve is connected to port d of the second four-way valve in sequence through the first solenoid valve and the fifth heat exchanger, and port d of the first four-way valve is also connected to port d of the second four-way valve in sequence through the second solenoid valve and the third heat exchanger in sequence; the inlet of the second heat exchange channel of the evaporator is connected to port c of the second four-way valve, and the outlet is connected to port b of the three-way valve; port a of the three-way valve is connected to port b of the second four-way valve through the first heat exchange channel of the seventh heat exchanger;

[0017] In the grease circulation pipeline, the outlet of the second heat exchange channel of the seventh heat exchanger is connected to the inlet of the high-temperature energy storage device via the third solenoid valve and the sixth heat exchanger in sequence. The outlet of the second heat exchange channel of the seventh heat exchanger is also connected to the inlet of the high-temperature energy storage device via the fourth solenoid valve and the fourth heat exchanger in sequence. The outlet of the high-temperature energy storage device is connected to the inlet of the second heat exchange channel of the seventh heat exchanger. The outlet of the high-temperature energy storage device is also connected to the inlet of the high-temperature energy storage device via the second heat exchanger and the transformer converter in sequence.

[0018] A further improvement of the present invention is that it also includes: a low-temperature expansion tank;

[0019] The low-temperature expansion tank is connected to ports d and b of the first four-way valve, respectively.

[0020] A further improvement of the present invention is that it further includes: a first water pump, a second water pump, a first oil pump, and a second oil pump;

[0021] The first water pump is located at the outlet of the second heat exchange channel of the gas cooler;

[0022] The second water pump is located at the outlet of the second heat exchange channel of the evaporator;

[0023] The first oil pump is located at the inlet of the high-temperature energy storage device;

[0024] The second oil pump is located at the outlet of the second heat exchange channel of the seventh heat exchanger.

[0025] A further improvement of the present invention is that,

[0026] The third and fourth heat exchangers of the heating plate are used to heat the crew compartment.

[0027] The fifth heat exchanger in the refrigeration module is used to refrigerate the crew compartment;

[0028] The fifth and sixth heat exchangers of the refrigeration module are used in conjunction to achieve dehumidification of the crew cabin;

[0029] The cooling air outlet of the cooling module is located in the upper part of the carriage; the heating air outlet of the heating module is located in the lower part of the carriage.

[0030] A further improvement of the present invention is that,

[0031] When formula (1) is satisfied, the vehicle enters the cooling mode; where,

[0032]

[0033] In the formula, A is an empirical coefficient; T air The ambient air temperature; Tindoor Indoor air temperature;

[0034] In cooling mode, the first solenoid valve is open and the second solenoid valve is closed; the third solenoid valve is open or closed, and the fourth solenoid valve is open or closed; the three-way valve's ports b and c are connected; the first four-way valve's ports c and d are connected, and ports a and b are connected; the second four-way valve's ports c and d are connected, and ports a and b are connected.

[0035] A further improvement of the present invention is that,

[0036] When formula (2) is satisfied, the vehicle enters heating mode; where,

[0037]

[0038] In the formula, B is an empirical coefficient; T air The ambient air temperature; T indoor Indoor air temperature;

[0039] In heating mode, the first solenoid valve is closed and the second solenoid valve is open; the third solenoid valve is open or closed, and the fourth solenoid valve is open or closed; the b and c ports of the three-way valve are connected; the c and b ports of the first four-way valve are connected, and the a and d ports are connected; the c and b ports of the second four-way valve are connected, and the a and d ports are connected.

[0040] A further improvement of the present invention is that,

[0041] When formula (3) is satisfied, the vehicle enters dehumidification mode; where,

[0042]

[0043] In the formula, C is an empirical coefficient; T air The ambient air temperature; T indoor Indoor air temperature; d indoor Indoor air humidity;

[0044] In dehumidification mode, the third solenoid valve is open, the first solenoid valve is open; the second solenoid valve is open or closed, and the fourth solenoid valve is open or closed.

[0045] A further improvement of the present invention is that,

[0046] When formula (4) is satisfied, the vehicle enters the waste heat recovery mode; where,

[0047]

[0048] In the formula, m is an empirical coefficient; T air The ambient air temperature; T indoor Indoor air temperature; T equi P represents the temperature of the transformer converter.cond P is the inlet pressure of the CO2 module gas cooler. evap This refers to the outlet pressure of the CO2 module evaporator.

[0049] In waste heat recovery mode, the fourth solenoid valve is open, the third solenoid valve is closed, the first solenoid valve is closed, and the second solenoid valve is open; the b and c ports of the second four-way valve are connected, and the a and d ports of the second four-way valve are connected; the b and c ports of the first four-way valve are connected, and the a and d ports of the first four-way valve are connected.

[0050] Under the premise of waste heat recovery mode, when formula (5) is satisfied, the oil direct heating method is adopted. At this time, the three-way valve c port and b port are connected. When formula (6) is satisfied, the oil and low temperature water circuit heat exchange is adopted to achieve heating in the form of heat pump. At this time, the three-way valve a port and b port are connected.

[0051]

[0052]

[0053] In the formula, n is an empirical coefficient; T was T represents the residual heat temperature. air The ambient air temperature.

[0054] A further improvement of the present invention is that,

[0055] When drinking water needs to be heated, the fifth solenoid valve opens; among which,

[0056] When both the crew cabin and drinking water require heating, the flow distribution ratio is allocated using formula (7);

[0057]

[0058] In the formula, E is an empirical coefficient; T dri Temperature of the drinking water heating tank; T indoor Indoor air temperature; m dri The water mass flow rate allocated to the drinking water heating circuit; m high This represents the total mass flow rate of the high-temperature water circuit.

[0059] A further improvement of the present invention is that,

[0060] When formula (8) is satisfied, the compressor frequency remains stable; when formula (8) is not satisfied and the calculation result is less than 1, the compressor frequency is increased; when formula (8) is not satisfied and the calculation result is greater than 3, the compressor frequency is decreased.

[0061]

[0062] In the formula, F is an empirical coefficient; Q is the heating or cooling capacity; W is the compressor power consumption; P cond P is the inlet pressure of the CO2 module gas cooler. evap This refers to the outlet pressure of the CO2 module evaporator.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] The secondary loop thermal management system provided by this invention is specifically a modular secondary loop thermal management system. It can fully recover and cascade the energy of the waste heat utilization loop modules on rail vehicles, achieving energy-saving and environmental protection effects. Furthermore, in this invention, CO2 circulation is integrated into a single module to provide total energy, while the remaining heat exchange modules in the system use water or oil for heat exchange. This reduces the amount of copper CO2 piping used, allowing the adoption of circulating coolant piping with lower pressure requirements. The circulating heat exchange medium within the system becomes a currently mature and widely used coolant, reducing the economic cost of the CO2 heat pump air conditioning system for rail vehicles. Moreover, the secondary system switches between cooling and heating media. Even in the event of a pipeline failure leading to coolant leakage or other accidental accidents, the coolant leaking into the passenger compartment will not pose the same threat to passenger safety as a CO2 leak, thus improving the safety of the CO2 heat pump system used on rail vehicles.

[0065] In this invention, when the transformer converter has excess heat that needs to be recovered, it enters the waste heat recovery mode, which circulates the oil circuit and allows the heat from the transformer converter to enter the indoor air module for heat exchange with the indoor air, thereby increasing the indoor temperature.

[0066] In this invention, when the drinking water module has a heat requirement, the fifth solenoid valve is opened, and air absorbs heat from the gas cooler of the CO2 module to reach a high temperature, then enters the drinking water module to heat the water. There is no need to design a separate water heating module; the drinking water can be heated simply by utilizing the waste heat of the system, thereby achieving full energy recovery and cascade utilization, and thus achieving energy conservation and environmental protection. Attached Figure Description

[0067] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0068] Figure 1 This is a schematic diagram of a secondary loop thermal management system for a CO2 heat pump air conditioner provided in an embodiment of the present invention;

[0069] The annotations in the figure are explained as follows:

[0070] 100. CO2 processing module; 1. Compressor; 2. Gas cooler; 3. Throttling valve; 4. Evaporator; 5. Gas-liquid separator;

[0071] 200. Outdoor air module;

[0072] 300. Indoor air module; 6. Third heat exchanger; 7. Fourth heat exchanger; 8. Fifth heat exchanger; 9. Sixth heat exchanger; 10. Cooling air outlet; 11. Heating air outlet; 12. First solenoid valve; 13. Second solenoid valve; 14. Third solenoid valve; 15. Fourth solenoid valve;

[0073] 400. Drinking water module; 16. Fifth solenoid valve; 17. First water pump;

[0074] 500. Electrical and waste heat recovery module; 18. Transformer converter; 19. Seventh heat exchanger;

[0075] 20. First oil pump; 21. High-temperature energy storage device; 22. Second oil pump; 23. Second water pump; 24. Three-way valve; 25. First four-way valve; 26. Second four-way valve; 27. Low-temperature expansion tank. Detailed Implementation

[0076] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0077] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0078] The present invention will now be described in further detail with reference to the accompanying drawings:

[0079] Please see Figure 1The present invention discloses a secondary loop thermal management system for a CO2 heat pump air conditioner, comprising:

[0080] CO2 processing module 100 includes compressor 1, gas cooler 2, throttle valve 3, evaporator 4 and gas-liquid separator 5;

[0081] Outdoor air module 200, including a first heat exchanger and a second heat exchanger;

[0082] The indoor air module 300 includes a cooling module and a heating module; wherein the heating module includes a third heat exchanger 6 and a fourth heat exchanger 7, and the cooling module includes a fifth heat exchanger 8 and a sixth heat exchanger 9.

[0083] Drinking water module 400, including heater;

[0084] The electrical and waste heat recovery module 500 includes a transformer converter 18, a seventh heat exchanger 19, and a high-temperature energy storage device 21.

[0085] The outlet of compressor 1 is sequentially connected to the inlet of compressor 1 via the first heat exchange channel of gas cooler 2, the throttle valve 3, the first heat exchange channel of evaporator 4, and gas-liquid separator 5. Inside gas cooler 2, water flows in from port a of the second four-way valve 26 and flows out from the outlet of the second heat exchange channel, connecting to the first water pump 17. The outlet of the first water pump 17 is connected to port a of the first four-way valve 25 on one hand, and to a branch line on the other, connecting to the fifth solenoid valve 16. The drinking water enters the drinking water module 400 and then returns to port a of the first four-way valve 25; port b of the first four-way valve 25 is connected to the first heat exchanger, and the outlet of the first heat exchanger is connected to port b of the second four-way valve 26; port c of the first four-way valve 25 is connected to port c of the three-way valve 24; port d of the first four-way valve 25 has two branches, which are respectively connected to the first solenoid valve 12 and the second solenoid valve 13, and then converge and connect to port d of the second four-way valve 26 after passing through the fifth heat exchanger 8 and the third heat exchanger 6; in the evaporator 4, water flows from the second four-way valve 26 The oil flows in through port c and out to the second water pump 23. The outlet of the second water pump 23 is connected to port b of the three-way valve 24. Port a of the three-way valve 24 is connected to the first heat exchange channel of the seventh heat exchanger 19, and its outlet is connected to port b of the second four-way valve 26 as a waste heat recovery branch associated with the water circuit. The oil undergoes heat exchange in the second heat exchange channel of the seventh heat exchanger 19, and its outlet is connected to the second oil pump 22. The oil pump outlet has two branches, which are connected to the third solenoid valve 14 and the fourth solenoid valve 15 respectively, and then enter the sixth heat exchanger 9 and the second four-way valve 24 respectively. The four heat exchangers 7 converge at the outlet and enter the high-temperature energy storage device 21. The outlet of the high-temperature energy storage device 21 has two branches: one connects to the inlet of the second heat exchange channel of the seventh heat exchanger 19, and the other connects to the second heat exchanger of the outdoor air module 200. Its outlet connects to the transformer converter 18, and then enters the first oil pump 20, returning to the inlet of the high-temperature energy storage device 21. In addition, there is a low-temperature expansion tank 27 connected to the d port and b port of the first four-way valve 25 respectively, so as to control the water volume of the circulating water circuit.

[0086] In another embodiment of the present invention, a secondary loop thermal management system for a CO2 heat pump air conditioner is disclosed, comprising:

[0087] The CO2 processing module 100 includes a compressor 1, a gas cooler 2, a throttle valve 3, an evaporator 4, and a gas-liquid separator 5 connected in sequence. Specifically, the CO2 processing module 100 is used to perform a transcritical CO2 cycle to provide cooling / heating capacity for the entire secondary loop thermal management system. The compressor 1 may specifically be a transcritical CO2 compressor.

[0088] The outdoor air module 200 includes a first heat exchanger with a coolant as the working fluid and a second heat exchanger with grease as the working fluid; specifically, the outdoor air module 200 is used to realize heat exchange between the coolant in the secondary loop thermal management system and the outdoor air; the coolant may be water; further illustratively, the high-speed rail converter transformer must be equipped with a grease cooling circuit.

[0089] The indoor air module 300 includes a cooling module and a heating module. The heating module includes a third heat exchanger 6 using a coolant as the working fluid and a fourth heat exchanger 7 using grease as the working fluid; both heat exchangers can heat the passenger compartment. The cooling module includes a fifth heat exchanger 8 using a coolant as the working fluid and a sixth heat exchanger 9 using grease as the working fluid. The fifth heat exchanger 8 can cool the passenger compartment. When the fifth heat exchanger 8 and the sixth heat exchanger 9 work together, they can dehumidify the passenger compartment, improving passenger comfort. Further... Explanatoryly, the indoor air module 300 is used to meet the target temperature requirements inside the cabin, which is a basic operational requirement. In a further preferred technical solution, the cooling air outlet 10 of the cooling module is located in the upper part of the carriage, and the sinking of cold air makes the temperature distribution in the entire carriage more uniform from top to bottom, so as to improve the comfort of passengers. Similarly, the heating air outlet 11 of the heating module is located in the lower part of the carriage, and the rising of hot air achieves the same effect. Through the above configuration, the effect of "hot air blowing on the feet and cold air blowing on the face" can be achieved.

[0090] The drinking water module 400 is used to heat the drinking water on the rail vehicle and is a permanent heating plate; specifically, by way of bypassing the gas cooler 2, the drinking water can be heated separately.

[0091] The electrical and waste heat recovery module 500 is used to recover and balance the heat used by the transformer converter 18. Considering the safety of high-voltage electrical components, the circulation loop involved in this module uses grease as the working fluid for heat transfer. Specifically, the electrical and waste heat recovery module 500 includes a seventh heat exchanger 19 with coolant as the working fluid for waste heat recovery; a second oil pump 22 for waste heat recovery to pump grease and realize oil flow; a first oil pump 20 to circulate oil, enabling the transformer converter 18 to directly provide heat to the indoor air module 300; and a high-temperature energy storage device 21 for flexible storage of waste heat energy in the oil circuit system, to solve the time-domain imbalance between waste heat production and other heat-using locations in the vehicle.

[0092] In addition, a low-temperature expansion tank 27 is added to the water circulation loop to ensure that each water path is connected to this low-temperature expansion tank 27, thereby balancing the water consumption of the entire loop. This ensures that the water consumption is not too low, which would result in insufficient heat transfer, nor too high, which would result in insufficient flow of the working fluid and increased losses along the water path. Therefore, the expansion tank can reduce losses and make fuller use of the heat in the loop.

[0093] The secondary loop thermal management system for CO2 heat pump air conditioning in rail vehicles provided in this invention differs from the conventional primary system's direct discharge of waste heat. The system designed in this invention can fully utilize waste heat. Furthermore, unlike a typical primary system, this invention integrates the transcritical CO2 circulation into a separate CO2 processing module and uses water for heat exchange in the secondary circulation system. On one hand, because the secondary system uses water as the working fluid, the amount of copper piping used to carry high-pressure CO2 can be reduced, thereby lowering costs and improving economic efficiency. Also, because the water pressure is much lower than the CO2 piping pressure, valve components and other components experience less wear, further improving economic efficiency. On the other hand, because the working fluid is water, even if it leaks into the passenger compartment, there will be no significant safety hazard, effectively avoiding the risk of passenger asphyxiation due to excessive CO2 caused by pipeline leaks.

[0094] In another embodiment of the present invention, a control method for an integrated thermal management system for rail vehicles is disclosed. Based on the secondary loop thermal management system for CO2 heat pump air conditioning described above in the embodiments of the present invention, the method includes the following steps:

[0095] CO2 working fluid is fed into a transcritical CO2 compressor for compression, temperature increase, and pressure increase. Then, it releases heat through the gas cooler 2 in the CO2 processing module 100, and is then throttled by the throttle valve 3 before entering the evaporator 4 for heat absorption. The CO2 after heat exchange enters the gas-liquid separator 5 and finally returns to the compressor to complete the CO2 transcritical cycle. This cycle ensures that the gas cooler 2 can continuously provide heat and the evaporator 4 can continuously provide cooling, thereby providing a stable supply of cooling / heating to the entire secondary loop system.

[0096] By using a secondary loop to heat the target heat exchanger, the currently mature and widely used coolant can be used as the heat transfer medium for the secondary system. On the one hand, this can prevent leaks caused by pipeline failures that could threaten the safety of the occupants; on the other hand, it can reduce the use of CO2 copper pipelines, thereby saving costs and improving the economic efficiency of system utilization.

[0097] In this embodiment of the invention, Figure 1A schematic diagram of the secondary loop system is shown. The short dashed line in the diagram represents the CO2 circulation route; the solid line represents the water circulation route; and the dotted dashed line represents the grease circulation route. According to different operating modes and the heat demand of each heat-consuming unit at different times, the mode is switched by switching valves in the system to achieve full waste heat recovery and full utilization of energy. The different operating modes and corresponding control methods are described in detail below.

[0098] Specifically, in this embodiment of the invention, when the rail vehicle enters the cooling mode, port bc of the three-way valve 24 opens, ports cd and ab of the first four-way valve 25 open, and ports cd and ab of the second four-way valve 26 open. On one hand, the low-temperature water pump provides power to the water, enabling low-temperature water circulation. The water undergoes heat exchange in the evaporator 4 of the CO2 treatment module 100, absorbing cooling capacity and decreasing in temperature. It is then pumped out by the low-temperature water pump, switching the three-way valve 24 of the water circuit. Water enters from port b and flows out from port c, then flows to the first four-way valve 25, entering from port c and flowing out from port d. This allows the water to flow into the cooling plate of the indoor air module 300 for heat exchange, and then flows through the second four-way valve 26, entering from port d and flowing out from port c, returning to the evaporator 4 of the CO2 treatment module 100 for re-entry. Heat exchange is performed to complete the circulation of the evaporator 4 sections. On the other hand, a high-temperature water pump provides power to circulate the water in the high-temperature water circuit. The water undergoes heat exchange in the gas cooler 2 of the CO2 treatment module 100 and is pumped out by the high-temperature water pump. The water flows out to the first four-way valve 25, enters from port a and exits from port b, allowing the water to flow into the heat exchanger of the outdoor air module 200 to release heat to the outside environment. Then it flows through the second four-way valve 26, enters from port b and exits from port a, allowing the water to flow back to the gas cooler 2 of the CO2 treatment module 100 to re-exchange heat and complete the circulation of the gas cooler 2 sections.

[0099] Specifically, in this embodiment of the invention, when the rail vehicle enters the heating mode, port bc of the three-way valve 24 opens, ports bc and ad of the first four-way valve 25 open, and ports bc and ad of the second four-way valve 26 open. On one hand, the low-temperature water pump provides power to circulate the water in the low-temperature water circuit. The water undergoes heat exchange in the evaporator 4 of the CO2 treatment module 100 and is pumped out by the low-temperature water pump. The three-way switching valve of the water circuit is switched, allowing water to enter from port b of the three-way valve 24 and flow out from port c. The water then flows to the first four-way valve 25, entering from port c and flowing out from port b, allowing the water to flow into the heat exchanger of the outdoor air module 200 to exchange heat with the environment. Then, it flows through the second four-way valve 26, entering from port b and flowing out from port c, allowing the water to flow back to the evaporator 4 of the CO2 treatment module 100 for renewed heat exchange, completing the process in the evaporator 4. The water circulates through the gas cooler 2 of the CO2 treatment module 100. On the other hand, the high-temperature water pump provides power to circulate the water in the high-temperature water circuit. The water exchanges heat in the gas cooler 2 of the CO2 treatment module 100, absorbs heat, and rises in temperature. It is then pumped out by the high-temperature water pump and flows to the first four-way valve 25. The water enters from port a and exits from port d, allowing it to flow into the heating plate of the indoor air module 300 for heat exchange. Then it flows through the second four-way valve 26, entering from port d and exiting from port a, allowing the water to flow back to the gas cooler 2 of the CO2 treatment module 100 for heat exchange again, thus completing the circulation of the gas cooler 2 plate.

[0100] Specifically, in this embodiment of the invention, the vehicle can enter a waste heat recovery mode during heating mode. Waste heat recovery has two implementation methods: the first is that the grease circuit of the transformer converter 18 directly enters the heat exchanger in the passenger compartment for direct heating, at which time the fourth solenoid valve 15 is opened. The corresponding oil circuit path is as follows: the waste heat recovery oil pump directly pumps grease into the indoor air module 300, exchanges heat with the passenger compartment heat exchanger to provide heat, then flows into the high-temperature energy storage module for heat storage, flows through the waste heat recovery heat exchanger (at this time, no heat exchange occurs in this heat exchanger), and finally returns to the waste heat recovery compressor 1 to complete the direct heating grease circulation.

[0101] The second method involves the waste heat recovery heat exchanger directly exchanging heat with the low-temperature water circuit heat exchanger, transferring heat to the heat pump's heat exchanger. The heat pump then provides heating. In this case, the fourth solenoid valve 15 opens, the three-way valve 24 opens channels ab, and the second four-way valve 26 opens ports bc and ad. The corresponding system route is as follows: the grease from the high-temperature energy storage module enters the waste heat recovery heat exchanger. The grease circuit exchanges heat with the low-temperature water circuit within the waste heat recovery heat exchanger. The grease then enters the waste heat recovery oil pump, flows through the indoor air module 300, and finally returns to the high-temperature energy storage module to complete the grease circuit cycle. The water circuit changes in the low-temperature water circuit. After heat exchange in the evaporator 4, the water enters the low-temperature water pump and is pumped to the three-way switching valve. It then enters through port b of the three-way valve 24, flows out through port a, flows into the waste heat recovery heat exchanger for heat exchange, then enters through port b of the second four-way valve 26, flows out through port c, and returns to the evaporator 4 to complete the low-temperature water circuit cycle.

[0102] In a specific example of this invention, when formula (1) is satisfied, the vehicle enters the cooling mode, and the corresponding valve opening changes. The first solenoid valve 12 opens, the second solenoid valve 13 closes, the three-way valve 24 opens the bc port, and the water circuit four-way switching valve changes direction according to the passage direction of the cooling mode described above.

[0103]

[0104] In the formula, A is an empirical coefficient (4≤A≤5, obtained from surveys); T air Ambient air temperature, in K; T indoor The indoor air temperature is expressed in Kelvin (K).

[0105] In a specific example of this invention, when formula (2) is satisfied, the vehicle enters the heating mode, and the corresponding valve opening changes. The first solenoid valve 12 is closed, the second solenoid valve 13 is opened, the three-way valve 24 opens the bc port, and the water circuit four-way switching valve changes direction according to the passage direction of the heating mode described above.

[0106]

[0107] In the formula, B is an empirical coefficient (1≤B≤2, obtained from surveys); T air Ambient air temperature, in K; T indoor The indoor air temperature is expressed in Kelvin (K).

[0108] In a specific example of this invention, when formula (3) is satisfied, the vehicle enters the dehumidification mode. At this time, the third solenoid valve 14 is opened and the first solenoid valve 12 is also opened. The water circuit and the oil circuit work together to dehumidify the indoor air, thereby increasing the comfort of the passenger compartment.

[0109]

[0110] In the formula, C is an empirical coefficient (4≤C≤4.5, obtained from a survey); T air Ambient air temperature, in K; T indoor Indoor air temperature, in Kelvin (K); d indoor Indoor air humidity.

[0111] In a specific example of this invention, when formula (4) is satisfied, the vehicle enters the waste heat recovery mode. At this time, the fourth solenoid valve 15 is opened, and the waste heat recovery oil pump is used to pump the working fluid oil for heat transfer. The heat of the transformer converter 18 itself is used to heat the air in the passenger compartment, thereby achieving the effect of not wasting heat and completing the waste heat recovery.

[0112]

[0113] In the formula, m is an empirical coefficient (18≤m≤20, obtained from surveys); T air Ambient air temperature, in K; T indoor Indoor air temperature, in K; T equi P represents the temperature of the transformer converter, in Kelvin (K). cond P is the inlet pressure of the CO2 module gas cooler (i.e., the compressor discharge pressure), in MPa. evap This is the outlet pressure of the CO2 module evaporator (i.e., the compressor inlet pressure), in MPa.

[0114] In specific examples of the embodiments of the present invention, there are two waste heat recovery methods (specifically, one is that the oil directly enters the indoor heat exchanger for direct heating; the other is that the oil exchanges heat with the low-temperature water circuit and then heats through a heat pump). When formula (5) is satisfied, the oil direct heating method is adopted; when formula (6) is satisfied, the oil exchanges heat with the low-temperature water circuit and heats through a heat pump.

[0115]

[0116]

[0117] In the formula, n is an empirical coefficient (1.6 ≤ n ≤ 2.2, obtained from surveys); T was Waste heat temperature, in Kelvin (K); T air The ambient air temperature is expressed in Kelvin (K).

[0118] In a specific example of this invention, when the drinking water in the vehicle needs to be heated, the fifth solenoid valve 16 is opened to obtain a bypass branch connected to the normal circulation loop. The heat obtained from the gas cooler 2 in the CO2 processing module 100 is used to heat the drinking water at any time to meet the needs of passengers in the vehicle for hot drinking water. When both the passenger compartment and the drinking water need to be heated, the flow distribution ratio is allocated by formula (7).

[0119]

[0120] In the formula, E is an empirical coefficient (0.7≤E≤1.5, obtained from a survey); T dri Temperature of the drinking water heating tank; T indoor Indoor air temperature, unit: K; m dri The water mass flow rate allocated to the drinking water heating circuit; m high This represents the total mass flow rate of the high-temperature water circuit.

[0121] In a specific example of this invention, when the heating / cooling capacity of the entire system is sufficient or does not meet the preset requirements, the compressor 1 will perform a corresponding frequency conversion operation. By increasing the frequency, the heating / cooling capacity of the system can be improved, or by decreasing the frequency, the power consumption of the system can be reduced. When the calculated value is within the range shown in formula (8), the frequency of the compressor 1 remains stable. When it is less than 1, the compressor 1 increases the frequency to improve the heating / cooling capacity of the system. When it is greater than 3, the compressor 1 decreases the frequency, which can reduce power consumption and reduce the exhaust temperature and pressure of the compressor 1 to improve safety.

[0122]

[0123] In the formula, F is an empirical coefficient (1.5≤F≤2.5, obtained from research); Q is the heating / cooling capacity, in kW; W is the compressor power consumption, in kW; P cond P is the inlet pressure of the gas cooler in the CO2 processing module (i.e., the compressor discharge pressure), in MPa. evap This refers to the evaporator outlet pressure of the CO2 treatment module (i.e., the compressor inlet pressure), in MPa.

[0124] In a further preferred embodiment of the present invention, a high-temperature energy storage device 21 is provided in the electrical and waste heat recovery module 500, which can temporarily store excess waste heat and call it when other heat-consuming devices have a heat demand; if there is no heat demand for a long time, in order to balance the heat inside the vehicle, a high-temperature oil pump can be used to pump oil to the outdoor air module 200 for heat exchange with the outdoor air.

[0125] In the control method of the present invention, based on the real-time status parameters inside the vehicle compartment, various indicators are comprehensively considered, and the valve group in the system is adjusted to realize the switching of cooling and heating modes and the treatment of waste heat recovery, thereby achieving effective energy utilization and real-time precise control of temperature and humidity inside the vehicle.

[0126] Further illustrative explanation of the inventive points of this invention: When there is waste heat that needs to be recovered, such as when the transformer converter module has excess heat that needs to be recovered, the control system enters the waste heat recovery mode, opening the first oil pump 20 and the second oil pump 22 to circulate the oil circuit, allowing the heat from the transformer converter module to enter the indoor air module 300 for heat exchange with the indoor air, thus raising the indoor temperature. Similarly, when the drinking water module 400 has a heat demand, the fifth solenoid valve 16 is opened, allowing air to absorb heat from the gas cooler 2 of the CO2 module to reach a high temperature, which then enters the drinking water module 400 to heat the water. This eliminates the need for a separate water heating module; the system's waste heat can be used to heat the drinking water, achieving full energy recovery and cascade utilization, thereby achieving energy conservation and environmental protection. Furthermore, this invention integrates CO2 circulation into a single module to provide total energy, while the remaining heat exchange modules in the system use water or oil for heat exchange. This invention reduces the amount of copper CO2 piping used, replacing it with circulating coolant piping that requires lower pressure resistance. This allows the circulating heat exchange medium to be a readily available and mature coolant, reducing the economic cost of the CO2 heat pump air conditioning system for rail vehicles. Furthermore, the secondary system switches between cooling and heating media. Even in the event of a pipeline failure leading to coolant leakage, the leaked coolant will not pose the same safety threat to occupants as a CO2 leak, thus improving the safety of the CO2 heat pump system on rail vehicles. In the control method of this invention, based on real-time conditions and parameters within the carriage, various indicators are comprehensively considered to adjust the valve group within the system, achieving switching between cooling and heating modes and waste heat recovery. This enables efficient energy utilization and real-time, precise control of the temperature and humidity inside the carriage.

[0127] In summary, this invention specifically discloses a secondary loop thermal management system for CO2 heat pump air conditioning in rail vehicles. The integrated thermal management system includes: a CO2 processing module 100, an indoor air module 300, an outdoor air module 200, an electrical and waste heat recovery module 500, and a drinking water module 400. The technical solution provided by this invention can change the type of working fluid flowing over a large area (specifically, transitioning from a CO2 system to a water circulation system) through a secondary system, thereby improving system safety, reducing the cost of using the CO2 system, and fully utilizing waste heat. This can solve various cost and performance problems left over from the use of CO2 heat pump air conditioning in rail vehicles.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A secondary loop thermal management system for a CO2 heat pump air conditioner, characterized by, The application relates to a heat pump system, which comprises: a CO2 processing module (100) comprising a compressor (1), a gas cooler (2), a throttle valve (3), an evaporator (4) and a gas-liquid separator (5); an outdoor air module (200) comprising first and second heat exchangers; an indoor air module (300) comprising a refrigeration plate block and a heating plate block; wherein the heating plate block comprises third and fourth heat exchangers (6, 7), and the refrigeration plate block comprises fifth and sixth heat exchangers (8, 9); a drinking water module (400) comprising a heater; an electrical and waste heat recovery module (500) comprising a transformer converter (18), a seventh heat exchanger (19) and a high-temperature energy storage device (21); wherein, in the CO2 circulation pipeline, the outlet of the compressor (1) is connected in sequence with the first heat exchange channel of the gas cooler (2), the throttle valve (3), the first heat exchange channel of the evaporator (4), the gas-liquid separator (5) and the inlet of the compressor (1); in the water circulation pipeline, the inlet of the second heat exchange channel of the gas cooler (2) is connected with the a port of a second four-way valve (26), the outlet is connected in sequence with the a port of a first four-way valve (25) via a fifth electromagnetic valve (16) and the heater, and is connected with the a port of the first four-way valve (25); the b port of the first four-way valve (25) is connected with the b port of the second four-way valve (26) via the first heat exchanger; the c port of the first four-way valve (25) is connected with the c port of a three-way valve (24); the d port of the first four-way valve (25) is connected in sequence with the fifth heat exchanger (8) via a first electromagnetic valve (12) and the second four-way valve (26); the d port of the first four-way valve (25) is also connected in sequence with the third heat exchanger (6) via a second electromagnetic valve (13) and the second four-way valve (26); the inlet of the second heat exchange channel of the evaporator (4) is connected with the c port of the second four-way valve (26), and the outlet is connected with the b port of the three-way valve (24); the a port of the three-way valve (24) is connected with the b port of the second four-way valve (26) via the first heat exchange channel of the seventh heat exchanger (19); in the fat oil circulation pipeline, the outlet of the second heat exchange channel of the seventh heat exchanger (19) is connected in sequence with the sixth heat exchanger (9) via a third electromagnetic valve (14) and the inlet of the high-temperature energy storage device (21); the outlet of the second heat exchange channel of the seventh heat exchanger (19) is also connected in sequence with the fourth heat exchanger (7) via a fourth electromagnetic valve (15) and the inlet of the high-temperature energy storage device (21); the outlet of the high-temperature energy storage device (21) is connected with the inlet of the second heat exchange channel of the seventh heat exchanger (19), and is also connected in sequence with the second heat exchanger, the transformer converter (18) and the inlet of the high-temperature energy storage device (21).

2. A secondary loop thermal management system for a CO2 heat pump air conditioner according to claim 1, characterized in that, The application further comprises: a low-temperature expansion water tank (27); the low-temperature expansion water tank (27) is connected with the d and b ports of the first four-way valve (25).

3. A secondary loop thermal management system for a CO2 heat pump air conditioner according to claim 1, wherein The application further comprises: a first water pump (17), a second water pump (23), a first oil pump (20) and a second oil pump (22). The first water pump (17) is arranged at the outlet of the second heat exchange channel of the gas cooler (2); The second water pump (23) is arranged at the outlet of the second heat exchange channel of the evaporator (4); The first oil pump (20) is arranged at the inlet of the high-temperature energy storage device (21); The second oil pump (22) is arranged at the outlet of the second heat exchange channel of the seventh heat exchanger (19).

4. The secondary circuit thermal management system for the CO2 heat pump air conditioner according to claim 1, wherein the third heat exchanger (6) and the fourth heat exchanger (7) of the heating block are used for heating the passenger compartment; The fifth heat exchanger (8) of the refrigeration block is used for refrigerating the passenger compartment; The fifth heat exchanger (8) and the sixth heat exchanger (9) of the refrigeration block are used for dehumidifying the passenger compartment in cooperation; The refrigeration outlet (10) of the refrigeration block is arranged on the upper part of the vehicle cabin, and the heating outlet (11) of the heating block is arranged on the lower part of the vehicle cabin.

5. The secondary circuit thermal management system for the CO2 heat pump air conditioner according to claim 1, wherein when formula (1) is satisfied, the vehicle enters the refrigeration mode; wherein In the refrigeration mode, the first electromagnetic valve (12) is opened, the second electromagnetic valve (13) is closed, the third electromagnetic valve (14) is opened or closed, the fourth electromagnetic valve (15) is opened or closed, the b port and the c port of the three-way valve (24) are connected, the c port and the d port of the first four-way valve (25) are connected, the a port and the b port are connected, the c port and the d port of the second four-way valve (26) are connected, and the a port and the b port are connected.

6. The secondary circuit thermal management system for the CO2 heat pump air conditioner according to claim 1, wherein when formula (2) is satisfied, the vehicle enters the heating mode; wherein ，（1） In the formula, A is an empirical coefficient, and has a value range of 4≤A≤5; is the ambient air temperature, in K; is the indoor air temperature, in K; In the heating mode, the first electromagnetic valve (12) is closed, the second electromagnetic valve (13) is opened, the third electromagnetic valve (14) is opened or closed, the fourth electromagnetic valve (15) is opened or closed, the b port and the c port of the three-way valve (24) are connected, the c port and the b port of the first four-way valve (25) are connected, the a port and the d port are connected, the c port and the b port of the second four-way valve (26) are connected, and the a port and the d port are connected.

7. The secondary circuit thermal management system for the CO2 heat pump air conditioner according to claim 1, wherein when formula (3) is satisfied, the vehicle enters the dehumidification mode; wherein In the dehumidification mode, the third electromagnetic valve (14) is opened, the first electromagnetic valve (12) is opened, the second electromagnetic valve (13) is opened or closed, and the fourth electromagnetic valve (15) is opened or closed. ,（2） In the formula, B is an empirical coefficient, and has a value range of 1≤B≤2; is the ambient air temperature, in K; is the indoor air temperature, in K; 8. The secondary circuit thermal management system for the CO2 heat pump air conditioner according to claim 1, wherein when formula (4) is satisfied, the vehicle enters the waste heat recovery mode; wherein ​ ​ ， （3） In the formula, C is an empirical coefficient, and has a value range of 4≤C≤4.5; is the ambient air temperature, in K; is the indoor air temperature, in K; is the indoor air humidity; ​ ​ ​ ，（4） wherein m m is an empirical coefficient, with a value ranging from 18≤m≤20; Tamb is the ambient air temperature, in K; Tin is the indoor air temperature, in K; Ttrans is the transformer inverter temperature, in K; Pco2in is the CO2treatment module gas cooler inlet pressure, in MPa; Pco2out is the CO2treatment module evaporator outlet pressure, in MPa; In the waste heat recovery mode, the fourth solenoid valve (15) is opened, the third solenoid valve (14) is closed, the first solenoid valve (12) is closed, and the second solenoid valve (13) is opened; the b port and the c port of the second four-way valve (26) are connected in communication, the a port and the d port of the second four-way valve (26) are connected in communication; the b port and the c port of the first four-way valve (25) are connected in communication, and the a port and the d port of the first four-way valve (25) are connected in communication; Under the premise of the waste heat recovery mode, when formula (5) is satisfied, the oil direct heating mode is adopted, at this time, the c port and the b port of the three-way valve (24) are connected in communication; when formula (6) is satisfied, the oil and low-temperature water circuit heat exchange is adopted to realize heating in the heat pump mode, at this time, the a port and the b port of the three-way valve (24) are connected in communication; ， （5） ， （6） In the formula, n n is an empirical coefficient, and the value range is 1.6≤n≤2.2; Tres is the residual heat temperature, and the unit is K; Tamb is the ambient air temperature, and the unit is K.

9. The secondary circuit thermal management system for a CO2 heat pump air conditioner according to claim 1, characterized in that, When the drinking water needs to be heated, the fifth solenoid valve (16) is opened; wherein, When both the passenger cabin and the drinking water need to be heated, the flow distribution ratio is distributed through formula (7); ， （7） wherein E E is an empirical coefficient, having a value ranging from 0.7 T is the temperature of the drinking water heating tank, in K; T is the temperature of the indoor air, in K; is the mass flow rate of water distributed to the drinking water heating circuit; is the total mass flow rate of the high-temperature water circuit.

10. The secondary circuit thermal management system for a CO2 heat pump air conditioner according to claim 1, characterized in that, When formula (8) is satisfied, the compressor (1) frequency is maintained stable; when formula (8) is not satisfied and the formula calculation result is less than 1, the compressor (1) is frequency-increased; When formula (8) is not satisfied and the formula calculation result is greater than 3, the compressor (1) is frequency-decreased; ， （8） wherein, F F is an empirical coefficient, and the value range is 1.5≤F≤2.5; Q is the heating or cooling capacity, and the unit is kW; W is the compressor power consumption, and the unit is kW; P1 is the CO2 treatment module gas cooler inlet pressure, and the unit is MPa; P2 is the CO2 treatment module evaporator outlet pressure, and the unit is MPa.

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