Pump-free direct-cooling air conditioning system for large-depth underwater vehicle and refrigeration method

Abstract

The invention discloses a pump-free type direct-cooling air conditioning system for a large-depth underwater vehicle. The pump-free type direct-cooling air conditioning system comprises an air conditioner, a CO2 compressor, outboard cooling equipment and an outboard liquid tank. The air conditioner comprises an evaporator, and the evaporator is arranged in a user cabin. A cold source channel of the evaporator, the CO2 compressor, the outboard cooling equipment and the throttling device are sequentially communicated through pipelines to form an outer circulation pipeline, and CO2 refrigerants flow in the outer circulation pipeline. And the outboard cooling equipment is placed in the outboard liquid tank. The invention further discloses a refrigeration method based on the pump-free direct-cooling air conditioning system for the large-depth underwater vehicle. The system has the beneficial effects that non-toxic green super-transcritical CO is adopted as a refrigerant, the supercritical temperature and pressure of carbon dioxide are low, and the energy efficiency ratio is high.

Description

Technical Field

[0001] The present invention relates to the field of air conditioning and refrigeration, and in particular to a pumpless direct cooling air conditioning system for a deep underwater submersible. Background Art

[0002] Deep-sea submersibles typically operate at depths of 500-1000 meters, with seawater pressures of 5MPa-10MPa. The submersible's interior is a confined space, its hull seamlessly enclosed by seawater, preventing it from communicating with the outside atmosphere. To ensure a stable and comfortable environment within the submersible, the cabin air conditioning system is an essential component.

[0003] At present, traditional submersible air-conditioning systems mostly use Freon as refrigerant, and utilize indirect cooling and passive heat exchange principle technology to convert the heat in the cabin to the offboard seawater environment through three thermodynamic cycles. That is, the heat in the cabin is introduced into the offboard seawater through a seawater pump to cool the refrigerant, and the cooled refrigerant then cools the refrigerant water. The cooled refrigerant water is then transported to users throughout the ship through the refrigerant water pump group for cooling and dehumidification.

[0004] However, traditional submersible air conditioning systems have the following major issues: 1. Freon refrigerants have significant drawbacks. Freon itself is harmful to the human body, easily reacts with open flames, and is a major contributor to ozone depletion. If it leaks on a submersible, there's no effective way to deal with it. Furthermore, Freon refrigerant piping cannot be routed through the submersible. Furthermore, at great depths, passive heat exchange using seawater introduced from the outside presents significant systemic risks. Freon refrigerant cannot directly exchange heat with the seawater, significantly reducing heat exchange efficiency and lowering the energy efficiency of the air conditioning system. 2. Air conditioning heat exchange utilizes too many pumps and heat conversion systems, resulting in significant energy losses. The air conditioning system utilizes indirect cooling and passive heat exchange principles. Heat from the cabin or system equipment must be transferred to the outboard seawater environment through three thermal cycles. The refrigerant water, acting as an intermediate step, consumes a significant amount of overall resources and incurs significant heat losses. Furthermore, the introduction of seawater through pumps also consumes significant resources and generates significant heat losses, limiting the potential for further reductions in energy consumption and energy consumption with existing principles and technologies. Furthermore, the application of small nuclear reactor technology will significantly increase the heat load on existing submersibles, exponentially increasing cooling energy consumption, cooling capacity, air volume, and chilled water volume compared to conventional submersibles. Given the limited space and overall resources, achieving energy conservation and weight reduction in the cooling system becomes increasingly challenging and urgent. 3. The air conditioning system's various components are a major source of noise within the submersible, making vibration and noise reduction challenging. Existing vibration isolation and noise reduction structures no longer meet the submersible's requirements. 4. The systemic risks faced by the passive heat exchange method of introducing seawater from outside the ship are relatively large: At present, underwater submersibles generally use pump groups to introduce seawater from outside the ship into the boat, exchange heat with Freon in the condenser on the air-conditioning chiller, and then bring the heat out and return it to the seawater outside the ship to achieve cooling; as the depth of existing submersibles continues to increase, the pressure-bearing wall thickness of the seawater system needs to be greatly increased, resulting in a significant decrease in heat exchange efficiency and an increase in energy consumption. At the same time, due to the impact of pressure safety, the systemic risks faced by continuing to use the passive heat exchange method of introducing seawater from outside the cabin are relatively large.

[0005] In summary, traditional submersible air-conditioning systems are increasingly unable to meet the goals of achieving efficient energy supply, energy saving and noise reduction, and weight and emission reduction for underwater equipment at full depth. It is very necessary to design a new submersible air-conditioning system to meet the overall needs of large depths. Summary of the Invention

[0006] The purpose of the present invention is to provide a pumpless direct cooling air-conditioning system for a deep underwater submersible in order to improve the energy efficiency of the air-conditioning system in order to address the deficiencies of the prior art.

[0007] The technical solution adopted by the present invention is: a pumpless direct cooling air conditioning system for a deep-sea submersible, comprising an air conditioner, a CO2 compressor, an outboard cooling device and an outboard liquid tank; The air conditioner includes an evaporator, which is arranged in the user cabin; The outlet of the cold source channel of the evaporator is connected to the CO2 compressor through a pipeline, the outlet of the CO2 compressor is connected to the heat source inlet of the outboard cooling equipment through a pipeline, the heat source outlet of the outboard cooling equipment is connected to the cold source channel inlet of the evaporator through a throttling device, the cold source channel of the evaporator, the CO2 compressor, the outboard cooling equipment and the throttling device are connected in sequence through pipelines to form an external circulation pipeline, and CO2 refrigerant flows in the external circulation pipeline; the outboard cooling equipment is placed in the outboard liquid tank.

[0008] According to the above scheme, an oil separator is installed on the pipeline between the CO2 compressor and the outboard cooling equipment.

[0009] According to the above scheme, the outboard cooling equipment includes a heat exchange coil, an air inlet manifold and a liquid outlet manifold; the inlet end of the heat exchange coil is connected to the air inlet manifold, and the outlet end of the heat exchange coil is connected to the liquid outlet manifold; the inlet end of the air inlet manifold is connected to the throttling device through a pipeline, and the outlet end of the liquid outlet manifold is connected to the CO2 compressor through a pipeline.

[0010] According to the above solution, the heat exchange coil is fixed on the installation frame.

[0011] According to the above scheme, a mounting plate is provided at the lower end of the mounting frame, and the mounting plate is connected to the underwater submersible.

[0012] According to the above scheme, the pumpless direct cooling air-conditioning system for deep-sea submersibles includes multiple air conditioners placed in different user cabins. The outlet of the cold source channel of the evaporator of each air conditioner is connected to the inlet of the CO2 compressor through a pipeline, and the inlet of the cold source channel of each evaporator is connected to the throttling device through a pipeline.

[0013] According to the above scheme, the CO2 compressor adopts a variable frequency compressor.

[0014] According to the above scheme, the liquid outlet manifold of the outboard cooling equipment is higher than the throttling device.

[0015] The present invention also adopts a supercritical CO2 passive refrigeration method based on the above-mentioned pumpless direct cooling air-conditioning system for deep-sea submersibles. The method is as follows: the CO2 refrigerant is compressed by a CO2 compressor to become supercritical CO2, and flows autonomously to the outboard of the underwater submersible under the action of pressure. In the outboard cooling equipment, the supercritical CO2 exchanges heat with the cooling seawater in the outboard liquid tank, and becomes supercooled liquid CO2 after being condensed and dissipating heat. Under the action of its own gravity, the CO2 reaches the throttling device. After throttling by the throttling device, the CO2 undergoes a phase change and enters the evaporator of the air conditioner in each cabin in a gas-liquid two-phase mixed state, exchanges heat with the indoor air and evaporates. The superheated gaseous CO2 formed after evaporation enters the CO2 compressor, and a new round of refrigeration cycle is carried out.

[0016] The beneficial effects of the present invention are: 1. The present invention uses non-toxic green super-transcritical CO2 as a refrigerant to replace traditional Freon refrigerants. The supercritical temperature and pressure of carbon dioxide are low, the engineering feasibility is good, and the energy efficiency ratio is high. It has green and clean characteristics. Even if it leaks, it can be removed by boat carbon dioxide absorption, which is safe and reliable.

[0017] 2. The outboard heat exchanger of the present invention shares common design with the hull. The heat exchanger is placed in the outboard water tank or outside the ship, allowing the refrigerant to directly exchange heat with seawater, eliminating the need for a seawater pump to introduce seawater into the pressure-resistant hull. Furthermore, utilizing the high-pressure characteristics of supercritical carbon dioxide (critical pressure of 7.29 MPa), a compressor is used to compress the low-temperature, superheated gaseous CO2 into high-temperature, high-pressure supercritical CO2, with a maximum pressure of over 15 MPa. This prevents high-pressure seawater from penetrating the outboard heat exchanger, significantly improving energy utilization and system safety at great depths.

[0018] 3. In the present invention, supercritical carbon dioxide is coupled with passive cooling technology to circulate without the need for a water pump, changing the principle of the refrigeration system and eliminating two pump groups and intermediate heat exchange links. The refrigerant is laid throughout the ship, reducing the heat transfer consumption in the intermediate process of Freon cooling refrigerant water-refrigerant water-return cooling air, as well as the energy consumption of the water pump, effectively reducing the energy consumption of the system and solving the problem that traditional Freon refrigerant media cannot penetrate the bulkhead and be laid throughout the ship. At the same time, it saves a lot of overall space and weight resources, making the system design simpler and the equipment smaller in size and weight.

[0019] 4. The present invention eliminates two cold water pump groups by laying the refrigerant throughout the ship and exchanging heat outboard. At the same time, it uses the low-temperature refrigeration characteristics of CO2 to reduce the fan speed, thereby eliminating about half of the noise sources in the system and significantly improving the stealth level of the entire boat. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is an overall schematic diagram of Example 1.

[0021] Figure 2 This is a schematic structural diagram of the outboard cooling equipment in Example 1.

[0022] Among them: 1. Outboard liquid tank; 2. Outboard cooling equipment; 3. CO2 compressor; 4. Air conditioner; 5. Air intake manifold; 6. Throttle device; 7. Oil separator; 8. Liquid outlet manifold; 9. Heat exchange coil; 10. Mounting plate. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Example 1 like Figure 1 The pumpless direct cooling air conditioning system for a deep-sea submersible shown includes an air conditioner 4, a CO2 compressor 3, an outboard cooling device 2, and an outboard liquid tank 1; The air conditioner 4 includes an evaporator, which is arranged in the user cabin; the outlet of the cold source channel of the evaporator is connected to the CO2 compressor 3 through a pipeline, and the cold source of the evaporator exchanges heat with the air in the user cabin; the outlet of the CO2 compressor 3 is connected to the heat source inlet of the outboard cooling device 2 through a pipeline, and the heat source outlet of the outboard cooling device 2 is connected to the cold source channel inlet of the evaporator through a throttling device 6, and the cold source channel of the evaporator, the CO2 compressor 3, the outboard cooling device 2 and the throttling device 6 are connected in sequence through pipelines to form an external circulation loop, and the CO2 refrigerant flows in the external circulation loop; the outboard cooling device 2 is placed in the outboard liquid tank 1.

[0025] In the present invention, the pumpless direct cooling air-conditioning system for a deep underwater submersible can be used for heat dissipation in multiple user cabins; that is, the pumpless direct cooling air-conditioning system for a deep underwater submersible includes multiple air conditioners 4 placed in different user cabins, and the outlet of the evaporator cold source channel of each air conditioner 4 is connected to the inlet of the CO2 compressor 3 through a pipeline, and the inlet of the cold source channel of each evaporator is connected to the throttling device 6 through a pipeline; the air in each user cabin directly exchanges heat with the cold source of the corresponding evaporator.

[0026] Preferably, an oil separator 7 is provided on the pipeline between the CO 2 compressor 3 and the outboard cooling device 2 for separating the CO 2 refrigerant and the lubricating oil.

[0027] In the present invention, the CO2 compressor 3 generates significant heat and pressure during operation. Lubricating oil is used to reduce friction and wear in the CO2 compressor 3. However, over time, the lubricating oil decomposes due to the high temperature and high pressure and is discharged with the gas, causing contamination of the CO2 circuit and reducing heat exchange efficiency. Therefore, an oil separator 7 is installed in the pipeline to separate the CO2 refrigerant and the lubricating oil.

[0028] In the present invention, CO2 refrigerant flows between the outboard cooling equipment 2 and the air conditioner 4 (specifically, the evaporator of the air conditioner 4) in each user cabin through the CO2 compressor 3, and the heat in each user cabin is directly transferred to the cooling seawater in the outboard liquid tank 1 through supercritical CO2, thereby achieving the purpose of heat dissipation in the cabin.

[0029] In the present invention, the outboard liquid tank 1 is a liquid tank provided outside the pressure-resistant shell of the underwater submersible. The interior of the outboard liquid tank 1 is connected with the external seawater. The buoyancy of the underwater submersible is changed by adjusting the amount of seawater in the outboard liquid tank 1.

[0030] Preferably, if Figure 2As shown, the outboard cooling equipment 2 includes a heat exchange coil 9, an air intake manifold 5 and a liquid outlet manifold 8; the inlet end of the heat exchange coil 9 is connected to the air intake manifold 5, and the outlet end of the heat exchange coil 9 is connected to the liquid outlet manifold 8; the inlet end of the air intake manifold 5 is connected to the throttling device 6 through a pipeline, and the outlet end of the liquid outlet manifold 8 is connected to the CO2 compressor 3 through a pipeline.

[0031] In the present invention, the heat exchange coil 9 is fixed to a mounting frame, the lower end of which is provided with a mounting plate 10, which is connected to the underwater submersible. The outboard cooling device 2 is designed to conform to the hull structure. It uses outboard seawater to cool and condense the high-temperature refrigerant compressed by the air conditioner 4. Under deep and low temperatures underwater, the outboard seawater is directly used for natural convection cooling, thereby reducing the overall energy consumption of the air conditioning system.

[0032] In the present invention, the CO2 compressor 3 adopts a variable frequency compressor with high energy efficiency ratio and low vibration and noise. The CO2 compressor is precisely designed according to the refrigeration capacity requirements and taking into account the different heat exchange coefficients of the system at different temperatures.

[0033] In the present invention, the air conditioner 4 is used to exchange heat with CO2, transfer the heat in the cabin to the system and discharge it outside the underwater submersible.

[0034] Example 2 A supercritical CO2 passive refrigeration method based on the pumpless direct cooling air conditioning system for a deep underwater submersible as described in Example 1, the method is as follows: the CO2 refrigerant is compressed by the CO2 compressor 3 to become high-temperature and high-pressure supercritical CO2 (at this time, the temperature is ≥31.26°C and the pressure is 7.29 MPa~15MPa), and flows autonomously to the outboard of the underwater submersible under the action of pressure, and the refrigerant and lubricating oil are separated by the oil separator 7. In the outboard cooling device 2, the supercritical CO2 exchanges heat with the cooling seawater in the outboard liquid tank 1, and after being condensed and dissipated, it becomes a high-pressure and medium-temperature supercooled liquid CO2 (temperature is 15°C~31.26°C and pressure is 7.29 MPa~15MPa), and then reaches the throttling device 6 under its own gravity. After throttling by the throttling device 6, the CO2 undergoes phase change and enters the evaporator of each user cabin air conditioner 4 in a gas-liquid two-phase mixed state, exchanges heat with the air in the cabin and evaporates. After evaporation, the low-temperature superheated (the temperature is 10℃~20℃) gaseous CO2 enters the CO2 compressor 3, and a new round of refrigeration cycle begins.

[0035] In the present invention, according to the characteristics of supercritical CO2 refrigerant, its pressure can reach up to 15MPa, so the system adopts piping materials with a pressure rating of 15MPa or above to ensure the safety of the system at great depths.

[0036] In the present invention, the outboard cooling device 2 is arranged in the outboard liquid tank 1, and the outboard liquid tank 1 is at the top of the submersible, that is, the outboard cooling device 2 is at the top of other devices of the present invention, and the other devices are located inside the submersible.

[0037] The contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0038] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A pumpless direct cooling air conditioning system for deep-sea submersibles, characterized in that: Including air conditioner, CO2 compressor, outboard cooling equipment and outboard tanks; The air conditioner includes an evaporator, which is arranged in the user cabin; The outlet of the cold source channel of the evaporator is connected to the CO2 compressor through a pipeline, the outlet of the CO2 compressor is connected to the heat source inlet of the outboard cooling equipment through a pipeline, the heat source outlet of the outboard cooling equipment is connected to the cold source channel inlet of the evaporator through a throttling device, the cold source channel of the evaporator, the CO2 compressor, the outboard cooling equipment and the throttling device are connected in sequence through pipelines to form an external circulation pipeline, and CO2 refrigerant flows in the external circulation pipeline; the outboard cooling equipment is placed in the outboard liquid tank.

2. The pumpless direct cooling air conditioning system for a deep underwater submersible according to claim 1, characterized in that: An oil separator is installed on the pipeline between the CO2 compressor and the outboard cooling equipment.

3. The pumpless direct cooling air conditioning system for a deep underwater submersible according to claim 1, characterized in that: The outboard cooling equipment includes a heat exchange coil, an air inlet manifold and a liquid outlet manifold; the inlet end of the heat exchange coil is connected to the air inlet manifold, and the outlet end of the heat exchange coil is connected to the liquid outlet manifold; the inlet end of the air inlet manifold is connected to the throttling device through a pipeline, and the outlet end of the liquid outlet manifold is connected to the CO2 compressor through a pipeline.

4. The pumpless direct cooling air conditioning system for a deep underwater submersible according to claim 3, characterized in that: The heat exchange coil is fixed on the installation frame.

5. The pumpless direct cooling air conditioning system for a deep underwater submersible according to claim 4, characterized in that: A mounting plate is provided at the lower end of the mounting frame, and the mounting plate is connected to the underwater submersible.

6. The pumpless direct cooling air conditioning system for a deep underwater submersible according to claim 1, characterized in that: The pumpless direct cooling air-conditioning system for deep-sea submersibles includes multiple air conditioners placed in different user cabins. The outlet of the cold source channel of the evaporator of each air conditioner is connected to the inlet of the CO2 compressor through a pipeline, and the inlet of the cold source channel of each evaporator is connected to the throttling device through a pipeline.

7. The pumpless direct cooling air conditioning system for a deep underwater submersible according to claim 1, wherein: The CO2 compressor uses a variable frequency compressor.

8. The pumpless direct cooling air conditioning system for a deep underwater submersible according to any one of claims 1 to 7, characterized in that: The liquid outlet header of the outboard cooling equipment is higher than the throttling device.

9. A supercritical CO2 passive refrigeration method based on the pumpless direct cooling air conditioning system for deep underwater submersibles according to claim 1, characterized in that: The method is as follows: the CO2 refrigerant is compressed by a CO2 compressor to become supercritical CO2, and flows autonomously to the outboard of the underwater submersible under the action of pressure. In the outboard cooling equipment, the supercritical CO2 exchanges heat with the cooling seawater in the outboard liquid tank, is condensed and dissipates heat to become supercooled liquid CO2, and reaches the throttling device under the action of its own gravity. After throttling by the throttling device, the CO2 undergoes a phase change and enters the evaporator of the air conditioner in each cabin in a gas-liquid two-phase mixed state, exchanges heat with the indoor air and evaporates. The superheated gaseous CO2 formed after evaporation enters the CO2 compressor, and a new round of refrigeration cycle is carried out.

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