A heat pump air conditioning system with fire fighting function and a fire fighting control method

Abstract

The application discloses a heat pump air conditioning system with a fire-fighting function and a fire-fighting control method, wherein the system comprises a carbon dioxide heat pump air conditioning system formed by connecting components such as a compressor, a four-way reversing valve, an outdoor heat exchanger and a gas-liquid separator through pipelines; the system further comprises an outdoor release device, an indoor release device, a passenger room fire nozzle and a gas-liquid separator release nozzle arranged in the carbon dioxide heat pump air conditioning system. The heat pump air conditioning system with the fire-fighting function disclosed by the application realizes rapid and accurate treatment of a fire on a rail vehicle through the heat pump air conditioning system, has the characteristics of high reliability, and realizes different fire fighting of multi-stage fires through linkage of multiple fire extinguishing modes, so that the needs of treating different fires can be met.

Description

Technical Field

[0001] This invention relates to the field of rail transit air conditioning control technology, and in particular to a heat pump air conditioning system and fire control method with fire protection function. Background Technology

[0002] The safety and reliability of air conditioning units in the rail transit sector are particularly important. Carbon dioxide refrigerant, as a natural refrigerant, is non-flammable and non-explosive, and has excellent low-temperature heating performance. Under the premise that its thermal performance is comparable to conventional refrigerants, the main measures for fire protection in existing air conditioning systems are measures such as releasing low-temperature liquid refrigerant. For example, patent CN110553341B, a method for enabling a refrigeration system to achieve fire extinguishing, and its refrigeration and air conditioning systems, achieves fire extinguishing by adding an electric three-way valve to the heat exchanger pipeline to release the refrigerant. However, the three-way valve is susceptible to problems such as electrical system malfunctions affecting its release, causing system failures and rendering it unusable.

[0003] How to effectively ensure the fire safety reliability of rail transit is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] This invention addresses the aforementioned problems by proposing a heat pump air conditioning system with fire-fighting capabilities.

[0005] The technical means employed in this invention are as follows:

[0006] A heat pump air conditioning system with fire protection function includes a carbon dioxide heat pump air conditioning system formed by connecting a compressor, a four-way reversing valve, an outdoor heat exchanger, a dryer filter, a regenerator, a two-way expansion valve assembly, an indoor heat exchanger, and a gas-liquid separator through pipelines; it also includes...

[0007] An outdoor venting device is installed on the outdoor pipeline to release the cooling medium in the carbon dioxide heat pump air conditioning system to the outside for pressure relief and fire extinguishing when an outdoor fire is detected.

[0008] An indoor pressure relief device is installed on the indoor pipeline to release the cooling medium in the carbon dioxide heat pump air conditioning system into the room to relieve pressure and extinguish the fire when a fire is detected indoors.

[0009] The passenger compartment fire nozzles are installed on the indoor piping to release the cooling medium in the carbon dioxide heat pump air conditioning system into the room to extinguish the fire when a fire is detected indoors. The fire activation level of the passenger compartment fire nozzles is greater than that of the indoor venting device.

[0010] A gas-liquid separator vent nozzle, connected to the gas-liquid separator, is used to release the cooling medium inside the gas-liquid separator for fire extinguishing when a fire is detected. The fire activation level of the gas-liquid separator vent nozzle is greater than that of the fire activation level of the passenger compartment fire nozzle.

[0011] Furthermore, the passenger compartment fire nozzles are installed in the connecting passage between the carriages, and the passenger compartment fire nozzles are connected to the pipeline connecting the indoor heat exchanger and the bidirectional expansion valve group through the first pipeline, and the first pipeline is equipped with a solenoid valve.

[0012] Furthermore, the gas-liquid separator vent nozzle is connected to the gas-liquid separator via a second pipeline, which is equipped with a fusible plug. The gas-liquid separator vent nozzle is used to vent the liquid cooling medium inside the gas-liquid separator for fire extinguishing.

[0013] Furthermore, the outdoor venting device is connected via a pipeline to a pipeline that connects the four-way reversing valve and the outdoor heat exchanger;

[0014] The indoor venting device is connected to the pipeline connecting the bidirectional expansion valve assembly and the indoor heat exchanger via a pipeline.

[0015] Furthermore, the bidirectional expansion valve assembly is a bidirectional electronic expansion valve; or,

[0016] The bidirectional expansion valve assembly includes a refrigeration expansion valve assembly and a heating expansion valve assembly connected in parallel on the pipeline between the regenerator and the indoor heat exchanger.

[0017] The refrigeration expansion valve assembly includes an electronic expansion valve A and a one-way valve A connected in series.

[0018] The heating expansion valve assembly includes an electronic expansion valve B and a one-way valve B connected in series.

[0019] Furthermore, both the indoor and outdoor venting devices are pressure relief valves.

[0020] Furthermore, it also includes a quick-connect needle valve connected to the gas-liquid separator via a pipeline.

[0021] A fire control method using a heat pump air conditioning system with fire-fighting function as described in this invention includes the following steps: a fire monitoring system monitors the rail vehicle for fire, obtains the location and level of the fire, and controls the carbon dioxide heat pump air conditioning system to extinguish the fire based on the location and level of the fire.

[0022] When the fire level is Level 1 and the fire location is indoors, an indoor fire extinguishing strategy should be adopted:

[0023] When the carbon dioxide heat pump air conditioning system starts the heat pump heating mode, the compressor and the four-way reversing valve start working, and the two-way expansion valve group is closed, so that the compressor pressurizes the gaseous cooling medium in the carbon dioxide heat pump air conditioning system and delivers it to the indoor pipeline through the four-way reversing valve, and releases pressure and extinguishes fire through the indoor venting device.

[0024] When the fire level is Level 1 and the fire location is outdoors, an outdoor firefighting strategy shall be adopted:

[0025] When the carbon dioxide heat pump air conditioning system starts the air conditioning cooling mode, the compressor and the four-way reversing valve start working, and the two-way expansion valve group is closed, so that the compressor pressurizes the gaseous cooling medium in the carbon dioxide heat pump air conditioning system and delivers it to the outdoor pipeline through the four-way reversing valve, and then releases pressure and extinguishes the fire through the outdoor venting device.

[0026] When the fire level is level two and the fire location is indoors, the level two fire extinguishing strategy shall be adopted:

[0027] When the carbon dioxide heat pump air conditioning system starts the air conditioning cooling mode, the compressor and the four-way reversing valve start working, and the solenoid valve on the first pipeline is opened, so that the compressor pressurizes the gaseous cooling medium in the carbon dioxide heat pump air conditioning system and delivers it to the outdoor pipeline through the four-way reversing valve, and then enters the indoor pipeline through the bidirectional expansion valve group, and is depressurized and extinguished through the fire nozzles in the passenger room.

[0028] When the fire level is level three, a three-level fire extinguishing strategy is adopted:

[0029] The pipeline of the gas-liquid separator vent nozzle is opened to release the liquid cooling medium inside the gas-liquid separator for fire extinguishing.

[0030] Furthermore, the indoor and outdoor venting devices are pressure relief valves. When the fire level is Level 1, the carbon dioxide cooling medium is depressurized and extinguished by increasing the pressure in the pipeline of the carbon dioxide heat pump air conditioning system through the indoor or outdoor venting devices.

[0031] When the fire level is level two, the carbon dioxide cooling medium in the pipe of the carbon dioxide heat pump air conditioning system is depressurized and extinguished by opening the solenoid valve on the first pipe connected to the fire nozzle in the passenger compartment.

[0032] When the fire level is level three, the liquid cooling medium in the gas-liquid separator is released to extinguish the fire by melting the fusible plug on the second pipeline connected to the gas-liquid separator vent nozzle.

[0033] Furthermore, the indoor return air temperature is compared with the indoor ambient temperature threshold. If Ti1 < Th < Ti2, the fire level is determined to be Level 1 and the fire location is indoors. Here, Th is the indoor return air temperature, Ti1 is the first threshold of indoor ambient temperature, and Ti2 is the second threshold of indoor ambient temperature.

[0034] The outdoor fresh air temperature is compared with the outdoor ambient temperature threshold. If To < Te, the fire level is determined to be Level 1 and the fire location is outdoors. Here, Te is the outdoor fresh air temperature and To is the outdoor ambient temperature threshold.

[0035] Compare the indoor return air temperature with the indoor ambient temperature threshold. If Ti2 < Th, the fire level is determined to be Level II and the fire location is indoors.

[0036] If the temperature of the second pipeline connected to the gas-liquid separator vent nozzle is greater than the melting temperature of the fusible plug, the fire level is determined to be level three.

[0037] Furthermore, the outdoor fire extinguishing strategy also includes activating an outdoor axial flow fan to disperse the gaseous cooling medium released by the outdoor venting device.

[0038] Compared with existing technologies, the heat pump air conditioning system with fire-fighting function disclosed in this invention has the following beneficial effects: By setting an outdoor venting device, an indoor venting device, a passenger compartment fire nozzle, and a gas-liquid separator venting nozzle in the carbon dioxide heat pump air conditioning system of the rail vehicle, this invention achieves rapid and precise handling of fires in rail vehicles through the heat pump air conditioning system, and has the characteristics of high reliability. At the same time, by linking multiple fire extinguishing methods, it can realize different fire-fighting for multiple levels of fires, and can meet the needs of handling different fire situations. Attached Figure Description

[0039] Figure 1 This is a structural diagram of a first embodiment of the heat pump air conditioning system with fire-fighting function disclosed in this invention.

[0040] Figure 2 This is a structural diagram of a second embodiment of the heat pump air conditioning system with fire-fighting function disclosed in this invention;

[0041] Figure 3 This is a flowchart of a fire control method for a heat pump air conditioning system with fire protection function disclosed in this invention.

[0042] In the diagram: 1. Compressor; 2. Four-way reversing valve; 3. Outdoor venting device; 4. Outdoor heat exchanger; 5. Dryer filter; 6. Regenerator; 7. Two-way expansion valve assembly; 7-1. Electronic expansion valve A; 7-2. One-way valve A; 7-3. Electronic expansion valve B; 7-4. One-way valve B; 8. Indoor heat exchanger; 9. Gas-liquid separator; 10. Indoor venting device; 11. Indoor venting fan; 12. Axial flow fan; 13. Fusible plug; 14. Solenoid valve; 15. Passenger compartment fire nozzle; 16. Quick-connect needle valve; 17. Gas-liquid separator venting nozzle; 18. First pipeline; 19. Second pipeline. Detailed Implementation

[0043] Example 1

[0044] like Figure 1 The diagram shows a heat pump air conditioning system with fire-fighting function disclosed in this invention. It includes a carbon dioxide heat pump air conditioning system formed by connecting a compressor 1, a four-way reversing valve 2, an outdoor heat exchanger 3, a dryer filter 5, a regenerator 6, a bidirectional expansion valve assembly 7, an indoor heat exchanger 8, and a gas-liquid separator 9 via pipelines. In this embodiment, the bidirectional expansion valve assembly is a bidirectional electronic expansion valve, and also includes…

[0045] Outdoor relief device 3 is installed on the outdoor pipeline to release the cooling medium in the carbon dioxide heat pump air conditioning system to the outside for pressure relief and fire extinguishing when an outdoor fire is detected.

[0046] An indoor pressure relief device 10 is installed on the indoor pipeline to release the cooling medium in the carbon dioxide heat pump air conditioning system into the room for pressure relief and fire extinguishing when a fire is detected indoors.

[0047] The passenger compartment fire nozzle 15 is installed on the indoor pipeline to release the cooling medium in the carbon dioxide heat pump air conditioning system into the room to extinguish the fire when a fire is detected in the room. The fire activation level of the passenger compartment fire nozzle 15 is greater than the fire activation level of the indoor relief device 10.

[0048] The gas-liquid separator vent nozzle 17 is connected to the gas-liquid separator 9 and is used to release the cooling medium in the gas-liquid separator 9 to extinguish the fire when a fire is detected. The fire activation level of the gas-liquid separator vent nozzle 17 is greater than the fire activation level of the passenger compartment fire nozzle 15.

[0049] Specifically, in this embodiment, both the indoor venting device 10 and the outdoor venting device 3 are pressure relief valves. The outdoor venting device 3 is connected to the pipeline connecting the four-way reversing valve 2 and the outdoor heat exchanger 4 via a pipeline; the indoor venting device 10 is connected to the pipeline connecting the bidirectional electronic expansion valve and the indoor heat exchanger 8 via a pipeline. Specifically, the four ports of the four-way reversing valve 4 (including port d, port c, port e, and port s in the figure) are respectively connected to the compressor 1, the outdoor heat exchanger 4, the indoor heat exchanger 8, and the gas-liquid separator 9 via pipelines; the two ends of the a channel of the regenerator are respectively connected to the compressor 1 and the gas-liquid separator 9 via pipelines, the two ends of the b channel of the regenerator are respectively connected to the dryer filter 5 and the bidirectional electronic expansion valve via pipelines, and the other end of the bidirectional electronic expansion valve is connected to the indoor heat exchanger 8 via a pipeline. The passenger compartment fire nozzle 15 is located in the connecting passage between carriages, and is connected to the indoor heat exchanger 8 and the bidirectional electronic expansion valve via a first pipe 18. A solenoid valve 14 is installed on the first pipe 18. The gas-liquid separator vent nozzle 17 is connected to the gas-liquid separator 9 via a second pipe 18. A fusible plug 13 is installed on the second pipe 18. The gas-liquid separator vent nozzle 17 is used to vent the liquid cooling medium in the gas-liquid separator 9 for fire extinguishing.

[0050] The heat pump air conditioning system with fire-fighting function disclosed in this invention can not only provide normal cooling and heating for rail vehicles, but also extinguish fires in the event of a fire on the rail vehicles. The specific process is as follows:

[0051] I. Refrigeration Cycle Process of Heat Pump Air Conditioning System:

[0052] Compressor 1 compresses low-temperature, low-pressure carbon dioxide refrigerant to form a high-temperature, high-pressure supercritical gas, which is then discharged into four-way reversing valve 2. The carbon dioxide enters the outdoor heat exchanger 4 and the outdoor venting device 3 through the outdoor port of four-way reversing valve 2. The heat released by the refrigerant in the outdoor heat exchanger 4 is carried away by the air blown out by the outdoor axial flow fan 12. The refrigerant continues to flow from the outdoor heat exchanger 4 into the dryer filter 5. The refrigerant flowing out of the dryer filter 5 flows into the high-pressure side of the regenerator 6. The refrigerant flowing out of the high-pressure side of the regenerator 6 enters the bidirectional electronic expansion valve for throttling and expansion. The expanded low-temperature, low-pressure refrigerant flows out of the bidirectional electronic expansion valve and continues to flow into the indoor heat exchanger 8 and the indoor venting device 10. The heat carried by the air blown out by the indoor ventilator 11 is carried away by the refrigerant in the indoor heat exchanger 8. The refrigerant continues to enter the gas-liquid separator 9 through the four-way reversing valve 2. After the gas-liquid components are separated from the refrigerant, the refrigerant enters the low-pressure side of the regenerator 6 and finally enters the suction port of the compressor 1 to complete the system refrigeration cycle.

[0053] II. Heating Cycle Process of Heat Pump Air Conditioning:

[0054] Compressor 1 compresses the low-temperature, low-pressure carbon dioxide refrigerant, creating a high-temperature, high-pressure supercritical gas which is then discharged into the four-way reversing valve 2. The carbon dioxide enters the indoor heat exchanger 8 and the indoor venting device 10 through the indoor side port of the four-way reversing valve 2. The heat released by the refrigerant in the outdoor heat exchanger 8 is carried away by the air blown out by the indoor ventilation fan 11, raising the indoor temperature for heating. The refrigerant continues to flow from the indoor heat exchanger 8 to the bidirectional electronic expansion valve, where it undergoes throttling and expansion before flowing to the high-pressure side of the regenerator 6. The refrigerant flowing out of the high-pressure side of the regenerator 6 enters the dryer filter 5. The refrigerant flowing out of the dryer filter 5 enters the outdoor heat exchanger 4. After absorbing the heat of the air blown out by the outdoor axial fan 12, the refrigerant flows through the indoor venting device 3 and enters the four-way reversing valve 2. Then it flows out from the return gas port of the four-way reversing valve 2 and enters the gas-liquid separator 9. After the gaseous carbon dioxide refrigerant with separated liquid components enters the low-pressure side of the regenerator 6, it finally flows to the suction port of the compressor 1, thus completing the system's heat pump heating cycle.

[0055] When a fire occurs in a rail vehicle, the heat pump air conditioning system with fire-fighting function disclosed in this invention will activate its fire-fighting and extinguishing function to extinguish the fire. The specific process is as follows, which includes a three-level fire-fighting strategy:

[0056] III. First-level firefighting measures:

[0057] 1) Indoor fire situation

[0058] When a fire occurs, the indoor return air temperature sensor collects the indoor return air temperature Th. The indoor return air temperature Th is compared with the indoor ambient temperature threshold Ti1. If it exceeds the first safe value of ambient temperature (the first threshold of indoor ambient temperature) and the concentration detected by the ambient smoke detector is greater than the first threshold of indoor smoke concentration Do1, an alarm signal is issued. That is, when it is determined that a fire has occurred indoors, the compressor and reversing valve are started, the heat pump air conditioning system is put into heat pump heating mode, the compressor works, and the bidirectional electronic expansion valve is closed, so that the air conditioning system is pressurized. When the pressure reaches the set value, the indoor pressure relief device 10 releases pressure to extinguish the fire.

[0059] 2) Outdoor fire situation

[0060] Based on the comparison between the outdoor fresh air temperature Te and the outdoor ambient temperature threshold To, if the outdoor ambient temperature safety value is exceeded and the concentration detected by the ambient smoke detector is greater than the outdoor smoke concentration threshold, an alarm signal is issued. That is, when it is determined that a fire has occurred outdoors, the compressor and reversing valve are started, the heat pump air conditioning system is put into air conditioning cooling mode, the compressor works, and the bidirectional electronic expansion valve is closed. The air conditioning system is pressurized. When the pressure reaches the set value, the outdoor venting device 3 in the air conditioning system releases pressure to extinguish the fire. At the same time, the outdoor axial flow fan is started to further improve the refrigerant diffusion rate.

[0061] IV. Second-level firefighting measures:

[0062] After a fire breaks out in a railcar, it is necessary to isolate the burning carriage from the unburned carriage area. At this time, when a fire occurs, the indoor return air temperature sensor collects the indoor return air temperature Th. The indoor return air temperature Th is compared with the indoor ambient temperature threshold Ti2. If it exceeds the second safe value (second threshold of indoor ambient temperature) and / or the concentration detected by the ambient smoke detector is greater than the second threshold of indoor smoke concentration, an alarm signal is issued. If the second safe value of indoor ambient temperature is greater than the first safe value of indoor ambient temperature, and the second threshold of indoor smoke concentration is greater than the first threshold of indoor smoke concentration, indicating a major fire, the solenoid valve 14 is opened. At this time, low-temperature, low-pressure refrigerant is released through the passenger compartment fire nozzles 15, isolating the connecting passage between carriages and further isolating the spread of the fire.

[0063] V. Third-level firefighting measures:

[0064] When the fire is large, the temperature rise will cause the fusible plug 13 installed in the fire pipeline to melt at a temperature >145±10℃. A large amount of liquid carbon dioxide will be released from the gas-liquid separator discharge nozzle 17 through the pipeline. At this time, a large amount of liquid refrigerant in the system will be released from the nozzle, which can release a large amount of liquid carbon dioxide to extinguish the fire instantly, absorb heat from the surrounding environment, and play a role in cooling down and lowering the ignition point, further mitigating the further deterioration of the fire.

[0065] Furthermore, it also includes a quick-connect needle valve 16 connected to the gas-liquid separator via a pipeline. The main function of the quick-connect needle valve 16 is to connect a fire hose. When the fire hose is connected, the refrigerant in the gas-liquid separator can be sprayed out through the fire hose for manual fire extinguishing.

[0066] like Figure 3 As shown, the fire control method of the heat pump air conditioning system with fire protection function disclosed in this invention includes the following steps: the fire monitoring system monitors the rail vehicle for fire, and obtains the location and level of the fire. Specifically, the indoor return air temperature sensor collects the indoor return air temperature and compares the collected indoor return air temperature with the indoor ambient temperature threshold. If Ti1 < Th < Ti2, it is determined that the fire level is level one and the fire location is indoors. Here, Th is the indoor return air temperature, Ti1 is the first threshold of indoor ambient temperature, and Ti2 is the second threshold of indoor ambient temperature.

[0067] The outdoor fresh air temperature sensor collects the outdoor fresh air temperature and compares the collected outdoor fresh air temperature with the outdoor ambient temperature threshold. If To < Te, the fire level is determined to be Level 1 and the fire location is outdoors. Here, Te is the outdoor fresh air temperature and To is the outdoor ambient temperature threshold.

[0068] Compare the indoor return air temperature with the indoor ambient temperature threshold. If Ti2 < Th, the fire level is determined to be Level II and the fire location is indoors.

[0069] If the temperature of the second pipeline connected to the gas-liquid separator vent nozzle is greater than the melting temperature of the fusible plug, the fire level is determined to be level three.

[0070] Based on the location and severity of the fire, the following fire extinguishing strategies were employed to control the carbon dioxide heat pump air conditioning system for fire suppression.

[0071] When the fire level is Level 1 and the fire location is indoors, an indoor fire extinguishing strategy should be adopted:

[0072] When the carbon dioxide heat pump air conditioning system starts in heat pump heating mode, the compressor and four-way reversing valve start working, and the bidirectional electronic expansion valve is closed. This allows the compressor to pressurize the gaseous cooling medium in the carbon dioxide heat pump air conditioning system and deliver it to the indoor pipeline through the four-way reversing valve. Then, the gaseous cooling medium is depressurized and used to extinguish the fire through the indoor relief device. Specifically, in this embodiment, the indoor relief device is a pressure relief valve. When the fire level is level one, the compressor delivers carbon dioxide gas to the indoor pipeline and closes the bidirectional electronic expansion valve, making the pressure in the pipeline of the carbon dioxide heat pump air conditioning system greater than the threshold of the pressure relief valve. This allows the carbon dioxide cooling medium to be depressurized and used to extinguish the fire through the indoor relief device.

[0073] When the fire level is Level 1 and the fire location is outdoors, an outdoor firefighting strategy shall be adopted:

[0074] When the carbon dioxide heat pump air conditioning system starts in cooling mode, the compressor and four-way reversing valve start working, and the bidirectional electronic expansion valve is closed. This allows the compressor to pressurize the gaseous cooling medium in the carbon dioxide heat pump air conditioning system and deliver it to the outdoor pipeline through the four-way reversing valve. Then, the gaseous cooling medium is depressurized and used to extinguish the fire through the outdoor venting device. Specifically, in this embodiment, the outdoor venting device is a pressure relief valve. When the fire level is level one, the compressor delivers carbon dioxide gas to the outdoor pipeline, making the pressure in the pipeline of the carbon dioxide heat pump air conditioning system greater than the threshold of the pressure relief valve. This allows the carbon dioxide cooling medium to be depressurized and used to extinguish the fire through the outdoor venting device.

[0075] When the fire level is level two and the fire location is indoors, the level two fire extinguishing strategy shall be adopted:

[0076] When the carbon dioxide heat pump air conditioning system starts in cooling mode, the compressor and four-way reversing valve begin operation. The solenoid valve on the first pipeline is opened, and the compressor pressurizes the gaseous cooling medium in the carbon dioxide heat pump air conditioning system and delivers it to the outdoor pipeline through the four-way reversing valve. Then, after passing through the bidirectional electronic expansion valve and the solenoid valve, the gaseous cooling medium is depressurized and used to extinguish the fire through the fire nozzles in the passenger compartment. Specifically, when the fire level is level two, the carbon dioxide cooling medium in the carbon dioxide heat pump air conditioning system is depressurized and used to extinguish the fire by opening the solenoid valve on the first pipeline connected to the fire nozzles in the passenger compartment.

[0077] Specific control strategies

[0078] Designed carbon dioxide usage M (kg):

[0079] M=K b (K1A+K2V);

[0080] A = A v +30A D ;

[0081] V = V v -V R ;

[0082] K b ---Material coefficient;

[0083] K1 --- Area coefficient (kg / m²) 2 ), take 0.2kg / m 2 ;

[0084] K2 --- Volume index (kg / m³) 3 ), take 0.7kg / m 2 ;

[0085] A---Reduced area;

[0086] A v ---The inner sides, bottom, and top of the carriage;

[0087] A D ---Total opening area of ​​the carriage;

[0088] V---Net volume of the carriage;

[0089] V v ---The volume of the carriage;

[0090] V R ---Volume of the fire-resistant and non-combustible areas of the carriage;

[0091] Based on the above parameters, the discharge mass flow rate W = M / t is derived, where t is the action time, which should not exceed 1 minute.

[0092] Discharge mass flow rate W = 3171.3(Cv1-Cv2)Ph (Gg / T) 1 / 2

[0093] In the formula

[0094] W---Electronic expansion valve discharge mass flow rate, kg / h;

[0095] Ph—High-pressure side working pressure, MPa;

[0096] Gg—gas phase density, kg / m³ 3 ;

[0097] T --- Discharge temperature, K;

[0098] Cv1 --- The minimum flow rate Cv value of the valve;

[0099] Cv2 --- The electronic expansion valve controls the flow rate Cv value;

[0100] The opening degree of the electronic expansion valve is H = bCv² + a*Th;

[0101] Among them, the temperature correction factor a and the electronic expansion valve discharge factor b are constants;

[0102] The electronic expansion valve adjusts its opening degree according to relevant parameters, further adapting to changes in indoor fire conditions and adjusting the flow rate. Different flow rates will further control the indoor ignition point, maximizing the balance between the system's refrigerant discharge and reducing the ignition point.

[0103] When the fire level is level three, a three-level fire extinguishing strategy is adopted:

[0104] The pipeline of the gas-liquid separator vent nozzle is opened to release the liquid cooling medium in the gas-liquid separator for fire extinguishing. Specifically, when the fire level is level three, the liquid cooling medium in the gas-liquid separator is released for fire extinguishing by melting the fusible plug on the second pipeline connected to the gas-liquid separator vent nozzle. That is, when the fire is large, the temperature rise will cause the fusible plug 13 installed in the fire pipeline to melt after the temperature is >145±10℃, thereby releasing the liquid cooling medium in the gas-liquid separator for fire extinguishing.

[0105] Furthermore, the outdoor fire extinguishing strategy also includes activating an outdoor axial flow fan to disperse the gaseous cooling medium discharged by the outdoor venting device, thereby increasing the dispersion rate of the refrigerant (liquid carbon dioxide) and improving fire extinguishing performance.

[0106] This invention utilizes an automatic pressure relief valve. Increased temperature creates pressure within the air conditioning system, which is then released to extinguish the fire through physical changes in the valve plates. This design offers high reliability. Furthermore, multiple fire extinguishing methods can be linked to address different fire situations. A quick-connect interface is added to the system to enable manual firefighting, further enhancing the flexibility and accuracy of fire suppression.

[0107] Example 2

[0108] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the bidirectional expansion valve assembly 7 is a bidirectional electronic expansion valve, while in this embodiment, as... Figure 2 As shown, the bidirectional expansion valve assembly 7 includes a refrigeration expansion valve assembly and a heating expansion valve assembly that are connected in parallel on the pipeline between the regenerator and the indoor heat exchanger.

[0109] The refrigeration expansion valve assembly includes an electronic expansion valve A7-1 and a one-way valve A7-2 connected in series.

[0110] The heating expansion valve assembly includes an electronic expansion valve B7-3 and a one-way valve B7-4 connected in series.

[0111] I. Air conditioning refrigeration cycle process of a heat pump air conditioning system with fire protection function:

[0112] Compressor 1 compresses low-temperature, low-pressure carbon dioxide refrigerant (cooling medium) to form a high-temperature, high-pressure supercritical gas, which is then discharged into four-way reversing valve 2. The carbon dioxide enters the outdoor heat exchanger 4 through the outdoor port of four-way reversing valve 2. The heat released by the refrigerant in the outdoor heat exchanger 4 is carried away by the air blown out by the outdoor axial flow fan 12. The refrigerant continues to flow from the outdoor heat exchanger 4 into the dryer filter 5. The refrigerant flowing out of the dryer filter flows into the high-pressure side (b channel) of the regenerator 6. The refrigerant flowing out of the high-pressure side (b channel) of the regenerator 6 enters the electronic expansion valve B7-3 for throttling and expansion. The expanded low-temperature, low-pressure refrigerant flowing out of the electronic expansion valve B7-3 continues to flow into the one-way valve B7-4. The refrigerant flowing out of the one-way valve B7-4 enters the inlet of the indoor heat exchanger 8. The heat carried by the air blown out by the indoor ventilator 11 is carried away by the refrigerant in the indoor heat exchanger 8. The refrigerant continues to enter the gas-liquid separator 9 through the four-way reversing valve 2. After the gas-liquid components are separated from the refrigerant in the gas-liquid separator 9, the refrigerant enters the low-pressure side (a channel) of the regenerator 6 and finally enters the suction port of the compressor 1 to complete the system refrigeration cycle.

[0113] II. Air conditioning heating cycle process of a heat pump air conditioning system with fire protection function:

[0114] Compressor 1 compresses the low-temperature, low-pressure carbon dioxide refrigerant, forming a high-temperature, high-pressure supercritical gas which is then discharged into the four-way reversing valve 2. The carbon dioxide enters the indoor heat exchanger 8 through the indoor port of the four-way reversing valve 2. The heat released by the refrigerant in the outdoor heat exchanger is carried away by the air blown out by the indoor ventilation fan 11, raising the indoor temperature for heating. The refrigerant continues to flow from the indoor heat exchanger 8 into the electronic expansion valve A7-1. The expanded, low-temperature, low-pressure refrigerant flowing out of the electronic expansion valve A7-1 continues to flow into the one-way valve A7-2. The refrigerant flowing out of A7-2 enters channel b of the regenerator 6. The refrigerant flowing out of channel b of the regenerator 6 enters the dryer filter 5. The refrigerant flowing out of the dryer filter 5 enters the outdoor heat exchanger 4. After absorbing the heat of the air blown out by the outdoor axial fan 12, the refrigerant enters the four-way reversing valve 2. Then, it flows out from the return port of the four-way reversing valve 2 and enters the gas-liquid separator 9. After the gaseous carbon dioxide refrigerant with separated liquid components enters channel a of the regenerator 6, it finally flows to the suction port of the compressor 1, thus completing the system's heat pump heating cycle.

[0115] The heat pump air conditioning system with fire protection function disclosed in this invention uses two one-way electronic expansion valves and two one-way valves between the regenerator and the indoor heat exchanger. One electronic expansion valve and one one-way valve are connected in series to form a refrigeration expansion valve group and a heating expansion valve group, respectively. Then, the two expansion valve groups are connected in parallel to form a bidirectional expansion valve group. Since only one-way electronic expansion valves and one-way valves are used, the cost of the heat pump is reduced. At the same time, it has the advantages of high operational reliability and low maintenance cost. Compared with the bidirectional electronic expansion valve, the solution of this invention is cost-effective, costing about 1 / 3 of the cost of the bidirectional electronic expansion valve.

[0116] Furthermore, the electronic expansion valve A and the electronic expansion valve B have the following relationship:

[0117] Cvbi<Cvh≤Cvb<Cvai<Cvc≤Cva;

[0118] Where Cva is the maximum flow coefficient of electronic expansion valve A, and Cvb is the maximum flow coefficient of electronic expansion valve B;

[0119] Cvai is the actual flow coefficient of electronic expansion valve A, Cvai=Qc / ((Thh-Tss)*Cp);

[0120] Cvbi is the actual flow coefficient of electronic expansion valve B, Cvbi=Qh / ((Thh-Tss)*Cp);

[0121] Cvc is the theoretical flow coefficient of electronic expansion valve A, Cvc=Qc / ((Th-Ts)*Cp);

[0122] Cvh is the theoretical flow coefficient of electronic expansion valve B, Cvh=Qh / ((Th-Ts)*Cp);

[0123] Qc is the cooling load; Qh is the heating load; Ts is the theoretical supply air temperature; Th is the theoretical return air temperature; Tss is the actual supply air temperature; Thh is the actual return air temperature; Cp is the specific heat of air at constant pressure.

[0124] This control strategy can match the appropriate electronic expansion valve control method according to the system load demand to the maximum extent, so that the system's cooling capacity matches the appropriate outdoor load and shortens the time to reach the target temperature.

[0125] The control method for a heat pump air conditioning system with fire-fighting function disclosed in this invention includes the following steps:

[0126] When a heat pump air conditioning system with fire protection capabilities is used for cooling operations:

[0127] The heat pump air conditioning system with fire protection function is activated in cooling mode. Based on the collected cooling load Qc, the opening of electronic expansion valve A is controlled using an opening control strategy. The specific opening control strategy for electronic expansion valve A is as follows:

[0128] Calculate the temperature control accuracy K and the suction superheat ΔT;

[0129] Temperature control accuracy K = Th - Tic;

[0130] Intake superheat ΔT = Tx - To;

[0131] The opening degree of the electronic expansion valve A is controlled according to the temperature control accuracy K and the intake superheat ΔT.

[0132] When K > 1℃, the opening degree of electronic expansion valve A is y = Te × a1 + △T × b1 + Cvai;

[0133] For a temperature of 0.5 < K ≤ 1℃, the opening degree of electronic expansion valve A is y = Te × a² + ΔT × b² + Cvai;

[0134] 0<K≤0.5℃, the opening degree of electronic expansion valve A is y=Te×a3+△T×b3+Cvai;

[0135] -0.5<K≤0℃, the opening degree of electronic expansion valve A is y=Te×a4+△T×b4+Cvai;

[0136] Where Cvai is the actual flow coefficient of electronic expansion valve A, Cvai=Qc / ((Thh-Tss)*Cp); Qc=kA(Te-Th); k is the heat transfer coefficient of the vehicle body surface; A is the surface area of ​​the vehicle body; Ts is the theoretical supply air temperature; Th is the theoretical return air temperature; Tx is the intake air temperature; To is the intake air saturation temperature; Te is the ambient temperature; Tic is the target temperature; Tss is the actual supply air temperature; Thh is the actual return air temperature; Cp is the specific heat of air at constant pressure; a1-a4 are the cooling ambient temperature coefficients, constants obtained from experimental data; b1-b4 are the cooling superheat coefficients, constants obtained from experimental data;

[0137] When a heat pump air conditioning system with fire protection capabilities is used for heating:

[0138] The heat pump air conditioning system with fire protection function is activated in heating mode. Based on the collected heating load Qh, the opening of electronic expansion valve B is controlled using an opening control strategy. The specific opening control strategy of electronic expansion valve B is as follows:

[0139] Calculate the temperature control accuracy K and the suction superheat ΔT;

[0140] Temperature control accuracy K = Th - Tic;

[0141] Intake superheat ΔT = Tx - To;

[0142] The opening degree of the electronic expansion valve B is controlled according to the temperature control accuracy K and the intake superheat △T.

[0143] When K > 1℃, the opening degree of electronic expansion valve B is y = Te × a5 + △T × b5 + Cvbi;

[0144] For a temperature of 0.5 < K ≤ 1℃, the opening degree of the electronic expansion valve B is y = Te × a6 + △T × b6 + Cvbi;

[0145] 0<K≤0.5℃, the opening degree of electronic expansion valve B is y=Te×a7+△T×b7+Cvbi;

[0146] -0.5<K≤0℃, electronic expansion valve B opening y=Te×a8+△T×b8+Cvbi;

[0147] Where Cvbi is the actual flow coefficient of electronic expansion valve B, Cvbi=Qh / ((Thh-Tss)*Cp); Qh=kA(Te-Th); k is the heat transfer coefficient of the vehicle body surface; A is the surface area of ​​the vehicle body; Tss is the actual supply air temperature; Thh is the actual return air temperature; Cp is the specific heat of air at constant pressure; Ts is the theoretical supply air temperature; Th is the theoretical return air temperature; Tx is the intake air temperature; To is the intake air saturation temperature; Te is the ambient temperature; Tic is the target temperature; Tss is the actual supply air temperature; Thh is the actual return air temperature; Cp is the specific heat of air at constant pressure; a5-a8 are the heating ambient temperature coefficients, constants obtained from experimental data; b5-b8 are the heating superheat coefficients, constants obtained from experimental data.

[0148] The heat pump air conditioning system control method with fire-fighting function disclosed in this invention has the purpose of high temperature control accuracy, fast cooling rate, and energy saving and consumption reduction.

[0149] Meanwhile, since the refrigerant uses different flow channels for cooling and heating modes, the mutual influence between the two modes can be reduced. Different valve types and flow coefficients are selected for different modes, which provides better adaptability to systems with large differences in cooling and heating loads. This is especially true in southern China where the summer and winter loads differ greatly. Therefore, this solution can minimize the overall energy consumption of the unit. Using different flow channels means that if a valve is damaged in the cooling mode, it will not affect the heating mode, allowing it to continue to be used, which improves the maintainability of the system. At the same time, the frequency of valve use is reduced, extending the valve life and reducing the risk of system operation.

[0150] Furthermore, the action time of the electronic expansion valve is delayed relative to the time of change of the ambient temperature gradient. Preferably, the delay time is 5 seconds. That is, when the ambient temperature sensor detects a change in the ambient temperature and the ambient temperature is at different gradients, a certain delay is made until the ambient temperature is stable before adjusting the opening of the electronic expansion valve to achieve the adjustment of different ambient temperatures. For example, when the ambient temperature sensor detects a change in the ambient temperature from the first gradient (e.g., 17.9℃) to the second gradient (e.g., 18.2℃), the electronic expansion valve A should be delayed for a certain time (e.g., 5 seconds) before adjusting the opening of the electronic expansion valve A from 380 steps to 400 steps. Because the action time of the electronic expansion valve is delayed relative to the time of change of the ambient temperature gradient, the collected ambient temperature can be more accurate, the electronic expansion valve can be controlled more precisely, and thus the heat pump effect can be guaranteed.

[0151] Furthermore, when a heat pump air conditioning system with fire protection function is used in cooling mode, the compressor operating frequency Fe = x1Te + y1, where x1 is the ambient temperature coefficient and y1 is the correction coefficient;

[0152] When a CO2 heat pump is used for heating, the compressor's operating frequency is Fe = x2Te + y2, where x2 is the ambient temperature coefficient and y2 is the correction coefficient.

[0153] The compressor frequency control uses the above control logic, which enables the compressor to adapt to load changes caused by changes in ambient temperature as quickly as possible, thereby achieving the goal of increasing the compressor's cooling rate and saving energy.

[0154] Comparison of cooling modes, with target temperature Tic = 24℃, ambient temperature Te = 30℃, and initial (0 min) return air temperature Thh = 29℃:

[0155]

[0156] As can be seen from the data table, under refrigeration conditions, this solution offers better valve control precision, faster cooling rate, and smaller temperature fluctuations.

[0157] Heating mode comparison, with target temperature Tic = 18℃, ambient temperature Te = 10℃, and initial (0 min) return air temperature Thh = 12℃:

[0158]

[0159] As can be seen from the data table, the heat pump mode, which uses a different electronic expansion valve orifice and control scheme than the cooling mode, can shorten the time to reach the target temperature and has smaller temperature fluctuations.

[0160] The fire-fighting function of the heat pump air conditioning system disclosed in this embodiment is almost identical to that of Embodiment 1 in terms of fire control process. The only difference is that Embodiment 1 requires the two-way electronic expansion valve to be closed at different fire extinguishing stages in order to form high pressure in the air conditioning pipeline, while in this embodiment, electronic expansion valve A and electronic expansion valve B are required at different fire extinguishing stages in order to form high pressure in the air conditioning pipeline.

[0161] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A heat pump air conditioning system with fire fighting function, applied to a railway vehicle, comprising a carbon dioxide heat pump air conditioning system formed by a compressor, a four-way reversing valve, an outdoor heat exchanger, a drying filter, a regenerator, a two-way expansion valve group, an indoor heat exchanger and a gas-liquid separator connected through pipelines; characterized in that: Further comprising, an outdoor relief device arranged on the outdoor pipeline for releasing the supercritical gaseous cooling medium in the carbon dioxide heat pump air conditioning system to the outdoor for pressure relief and fire extinguishing when a first level fire is detected in the outdoor; an indoor relief device arranged on the indoor pipeline for releasing the supercritical gaseous cooling medium in the carbon dioxide heat pump air conditioning system to the indoor for pressure relief and fire extinguishing when a first level fire is detected in the indoor; the indoor relief device and the outdoor relief device are both pressure relief valves; a passenger compartment fire nozzle arranged at the connecting passage between the carriages, which is connected with the pipeline connecting the indoor heat exchanger and the two-way expansion valve group through a first pipeline, and an electromagnetic valve is arranged on the first pipeline for releasing the supercritical gaseous cooling medium in the carbon dioxide heat pump air conditioning system to the indoor for isolation and fire extinguishing when a second level fire is detected in the indoor; a gas-liquid separator relief nozzle connected with the gas-liquid separator through a second pipeline, and a fusible plug is arranged on the second pipeline for releasing the liquid cooling medium in the gas-liquid separator for fire extinguishing when a third level fire is detected; the fire level and the determination position process are as follows: comparing the indoor return air temperature with the indoor environment temperature threshold value, if Ti1 comparing the outdoor fresh air temperature with the outdoor environment temperature threshold value, if To comparing the indoor return air temperature with the indoor environment temperature threshold value, if Ti2 if the temperature of the second pipeline connected with the gas-liquid separator relief nozzle is greater than the melting temperature of the fusible plug, it is determined that the fire level is the third level.

2. The heat pump air conditioning system with fire fighting function according to claim 1, characterized in that: the outdoor relief device is connected with the pipeline connecting the four-way reversing valve and the outdoor heat exchanger through a pipeline; the indoor relief device is connected with the pipeline connecting the two-way expansion valve group and the indoor heat exchanger through a pipeline.

3. The heat pump air conditioning system with fire fighting function according to claim 1, characterized in that: the two-way expansion valve group is a two-way electronic expansion valve; or, the two-way expansion valve group includes a refrigeration expansion valve group and a heating expansion valve group arranged in parallel on the pipeline between the heat regenerator and the indoor heat exchanger; the refrigeration expansion valve group includes an electronic expansion valve A and a one-way valve A connected in series; the heating expansion valve group includes an electronic expansion valve B and a one-way valve B connected in series.

4. The heat pump air conditioning system with fire fighting function according to claim 1, characterized in that: a quick-connection needle valve connected with the gas-liquid separator through a pipeline is further included.

5. A fire control method for the fire-fighting heat pump air conditioning system according to any one of claims 1 to 4, characterized by: the following steps are included: a fire monitoring system monitors the rail vehicle for fire, obtains the occurrence position and the fire level of the fire, and controls the carbon dioxide heat pump air conditioning system for fire extinguishing according to the occurrence position and the fire level of the fire by using the following fire extinguishing strategies; when the fire level is the first level and the fire position is the indoor, the indoor fire extinguishing strategy is adopted: The carbon dioxide heat pump air conditioning system starts the heat pump heating mode, the compressor and the four-way reversing valve start to work, and the bidirectional expansion valve group is closed, so that the compressor pressurizes the gaseous cooling medium in the carbon dioxide heat pump air conditioning system and delivers it to the indoor pipeline through the four-way reversing valve, and the indoor relief device is used for pressure relief and fire extinguishing; When the fire level is level one and the fire location is outdoor, the outdoor fire extinguishing strategy is adopted: The carbon dioxide heat pump air conditioning system starts the air conditioning cooling mode, the compressor and the four-way reversing valve start to work, and the bidirectional expansion valve group is closed, so that the compressor pressurizes the gaseous cooling medium in the carbon dioxide heat pump air conditioning system and delivers it to the outdoor pipeline through the four-way reversing valve, and the outdoor relief device is used for pressure relief and fire extinguishing; When the fire level is level two and the fire location is indoor, the level two fire extinguishing strategy is adopted: The carbon dioxide heat pump air conditioning system starts the air conditioning cooling mode, the compressor and the four-way reversing valve start to work, and the electromagnetic valve on the first pipeline is opened, so that the compressor pressurizes the gaseous cooling medium in the carbon dioxide heat pump air conditioning system and delivers it to the indoor pipeline through the four-way reversing valve after passing through the bidirectional expansion valve group, and the passenger room fire nozzle is used for pressure relief and fire extinguishing; When the fire level is level three, the level three fire extinguishing strategy is adopted: The pipeline of the gas-liquid separator relief nozzle is opened, and the liquid cooling medium in the gas-liquid separator is released for fire extinguishing.

6. The fire control method of the heat pump air conditioning system with fire fighting function according to claim 5, characterized in that: The indoor relief device and the outdoor relief device are pressure relief valves, when the fire level is level one, the pressure of the pipeline of the carbon dioxide heat pump air conditioning system is increased to release the carbon dioxide cooling medium from the indoor relief device or the outdoor relief device for pressure relief and fire extinguishing; When the fire level is level two, the electromagnetic valve on the first pipeline connected with the passenger room fire nozzle is opened to release the carbon dioxide cooling medium in the pipeline of the carbon dioxide heat pump air conditioning system from the passenger room fire nozzle for pressure relief and fire extinguishing; When the fire level is level three, the fusible plug on the second pipeline connected with the gas-liquid separator relief nozzle is melted to release the liquid cooling medium in the gas-liquid separator for fire extinguishing.

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