A multi-stage heat exchange system and method for an underwater vehicle

Abstract

The application discloses a multi-stage heat exchange system and method of a submerged vehicle, comprising a plurality of heat exchange units connected in sequence, each heat exchange unit comprising unit headers, a plurality of heat exchange plate pairs and unit separators stacked in sequence, and a hot side flow channel, a cold side flow channel and a pre-cooling flow channel are arranged on each heat exchange plate pair; the heat exchanger is composed of a plurality of heat exchange units, realizing three-stage distribution and convergence, and a large mass flow working medium is subjected to multi-stage distribution / convergence heat exchange by the heat exchange units, flow distribution in a single flow channel is more uniform, heat exchange performance is improved, in addition, a vacuum insulation cavity is arranged between the heat recovery module and the pre-cooling module of each heat exchange unit, coupling heat transfer is reduced, efficient operation of the heat exchanger is ensured, when the core body expands at a high temperature, the vacuum layer provides a space allowance, and safety of the heat exchanger is improved.

Description

Technical Field

[0001] This invention relates to the field of heat exchange technology for submersibles, specifically to a multi-stage heat exchange system and method for submersibles. Background Technology

[0002] As the world deepens its exploration of the ocean, the strategic importance of the ocean in terms of resources and military affairs is becoming increasingly prominent. With continuous innovation in marine technology, submersible vehicles such as small submarines, YL (underwater submarines), and heavy UUVs are developing rapidly, and their in-depth development is of great significance to my country's goal of becoming a maritime power. Unlike small electric-powered submersibles, large submersibles primarily use thermal power, offering significant advantages in diving depth and range. Conventional thermal power mainly uses the steam Rankine cycle, which is bulky, heavy, and inefficient. In contrast, the supercritical carbon dioxide (SCO2) Brayton cycle is compact, highly efficient, and represents the future trend of next-generation underwater thermal power. The heat exchange equipment in a simple Brayton cycle system mainly includes a regenerator and a precooler, and the heat exchange equipment determines the operating efficiency of the Brayton cycle system. Furthermore, unlike land platforms, submersibles have limited internal space and complex seabed conditions, requiring heat exchangers with higher requirements for compactness, heat exchange efficiency, and safety and reliability.

[0003] Conventional SCO2 Brayton cycle systems typically design and manufacture regenerators and precoolers separately, connecting them in series via pipe boxes and pipelines. For submersibles, this results in low space utilization. Therefore, it is necessary to integrate the regenerator and precooler of the Brayton cycle system for submersibles. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a multi-stage heat exchange system and method for underwater vehicles. The heat exchange system has a compact structure and high heat exchange efficiency, and is used in high-power underwater vehicles powered by supercritical carbon dioxide Brayton cycle.

[0005] This invention is achieved through the following technical solution:

[0006] A multi-stage heat exchange system for a submersible includes several heat exchange units connected in sequence. Each heat exchange unit includes a unit manifold, several heat exchange plate pairs and a unit partition plate stacked in sequence. Each heat exchange plate pair is provided with a hot side flow channel, a cold side flow channel and a pre-cooling flow channel.

[0007] The inlets of the hot and cold flow channels of each heat exchange plate pair in each heat exchange unit are connected to the heat source and cold source outlet of the Brayton system through the hot fluid inlet channel and cold fluid inlet channel of the unit manifold. The outlet of the hot flow channel of the heat exchange plate pair is connected to the pre-cooling channel. The outlet of each pre-cooling channel is connected to the heat source inlet of the Brayton system through the hot fluid outlet channel of the unit manifold. The outlet of each cold flow channel is connected to the cold source inlet of the Brayton system through the cold fluid outlet channel of the unit manifold.

[0008] Preferably, the unit manifold is provided with a hot-side axial inlet, a pre-cooling module axial outlet, a cold-side axial outlet, and a cold-side axial inlet;

[0009] The hot-side axial inlet is connected to the inlet of the hot-side flow channel of each heat exchange plate pair through a flow channel; the precooling module axial outlet is connected to the outlet of each precooling flow channel through a flow channel; the cold-side axial outlet is connected to the outlet of the cold-side flow channel of each heat exchange plate pair through a flow channel; and the cold-side axial inlet is connected to the inlet of the cold-side flow channel of each heat exchange plate pair through a flow channel.

[0010] Preferably, the plurality of heat exchange units are provided with an axially arranged hot fluid general inlet channel, a precooling fluid general outlet channel, a cold fluid general inlet channel, and a cold fluid general outlet channel;

[0011] The total hot fluid inlet channel is connected to the axial inlet of the hot side of each unit manifold, the total precooling fluid outlet channel is connected to the axial outlet of the precooling module of each unit manifold, the total cold fluid inlet channel is connected to the axial inlet of the cold side of each unit manifold, and the total cold fluid outlet channel is connected to the axial outlet of the cold side of each unit manifold.

[0012] Preferably, the plurality of heat exchange plates are fitted with a precooling module, the precooling module includes stacked shell plates, the precooling flow channel is disposed on the side wall of the shell plate, and a vacuum insulation cavity is provided between the precooling module and the plurality of heat exchange plates.

[0013] Preferably, the heat exchange plate pair includes stacked hot fluid plate and cold fluid plate, with hot-side flow channels and cold-side flow channels respectively disposed on the hot fluid plate and cold fluid plate. The outlet of the hot-side flow channel is connected to the pre-cooling flow channel of the shell plate on the same plane through the flow channel. The flow channel is provided with a flow divider hole, which is connected to the inlet of the pre-cooling flow channel of the lower shell plate.

[0014] Preferably, the inlet of the precooling channel is provided with a flow divider, so that the precooling channel forms two channels, and the hot fluid in the two channels flows in opposite directions.

[0015] Preferably, both the hot-side flow channel and the cold-side flow channel are provided with multiple concentric flow divider rings to divide the hot flow channel into multiple flow dividers, and the width of the multiple flow dividers decreases sequentially from the inside to the outside.

[0016] Preferably, the fluid flows in opposite directions in the hot-side and cold-side channels of the heat exchange plate pair.

[0017] Preferably, the hot-side flow channel and the cold-side flow channel are provided with a turbulence structure.

[0018] A multi-stage heat exchange method for a multi-stage heat exchange system of a submersible, characterized in that the hot fluid and cold fluid of the Brayton cycle system enter the hot fluid inlet channel and cold fluid inlet channel of the unit manifold of each heat exchange unit after being split once.

[0019] The hot fluid inlet channel and cold fluid inlet channel of the unit manifold perform secondary flow separation of the hot fluid and cold fluid, so that the hot fluid and cold fluid enter the hot side flow channel and cold side flow channel of each heat exchange plate pair and perform primary heat exchange.

[0020] After the heat exchange and cooling, the hot fluid is split three times and enters the two pre-cooling channels corresponding to each heat exchange plate to exchange heat with the seawater for a second time. Then, it enters the hot fluid outlet channel of the unit manifold from the outlet of the pre-cooling channel, and then merges with the hot fluid after the second cooling of each heat exchange unit into the hot side of the Brayton cycle system.

[0021] After the heat exchange and heating, the cold fluid flows into the cold fluid outlet channel of the unit manifold, and then flows into the cold side of the Brayton cycle system after merging with the heated cold fluid of each heat exchange unit.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] The present invention provides a multi-stage heat exchange system for a submersible, comprising multiple heat exchange units connected in sequence. Each heat exchange unit includes a regenerator module and a precooling module. The hot-side outlet of the regenerator module is directly connected to the inlet of the precooling module. The hot fluid enters the precooling module after heat exchange in the regenerator module to form a secondary heat exchange with seawater. This heat exchange unit integrates the functions of the regenerator and the precooler in the Brayton cycle, making the two integrated. The heat exchanger employs a conformal shell design to maximize the use of the limited internal space of the submersible, thus improving space utilization. Secondly, the heat exchange plates are fitted onto the submersible's shell and welded to it using vacuum diffusion welding, forming an integral structure. The heat exchanger serves as a pressure-bearing component while exchanging heat, enhancing the submersible's pressure resistance. This connection between the heat exchanger and the submersible saves space previously required for a fixed platform. Furthermore, the heat exchanger uses seawater outside the shell as a cold source and directly connects the regenerative module and the precooling module, thus requiring only two fluid inlets and two outlets. Its modular design allows for use with submersibles of different specifications. Finally, the entire heat exchanger consists of several heat exchange units, achieving three-stage flow distribution and convergence. High-mass-flow working fluid undergoes multi-stage flow distribution / convergence within the heat exchange units, resulting in more uniform flow distribution within each channel and improved heat exchange performance. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the multi-stage heat exchange system of the present invention;

[0025] Figure 2This is an exploded schematic diagram of the heat exchange unit of the present invention.

[0026] Figure 3 This is a schematic diagram of the unit current collector of the present invention.

[0027] Figure 4 This is a schematic diagram of the unit partition of the present invention.

[0028] Figure 5 This is a schematic diagram of the heat transfer plate of the present invention.

[0029] Figure 6 This is a schematic diagram of the cold fluid plate of the present invention.

[0030] In the diagram: 1-lower pressing plate, 2-heat exchange unit, 3-upper pressing plate, 4-hot side axial inlet, 5-precooling module axial outlet, 6-cold side axial outlet, 7-cold side axial inlet, 8-unit manifold, 9-unit partition, 10-cold fluid plate, 11-hot fluid plate, 12-unit axial hot side inlet, 13-unit axial cold side outlet, 14-unit axial cold side inlet, 15-unit precooling module axial outlet, 16-vacuum insulation cavity, 17-shell plate, 18-hot side flow channel, 19-precooling flow channel, 20-diversion hole, 21-diversion partition, 22-cold side flow channel. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings. These descriptions are intended to explain the invention and not to limit it.

[0032] See Figure 1 and 2 A multi-stage heat exchange system for a submersible includes several heat exchange units stacked sequentially to form a heat exchange module. The upper layer of the first-stage heat exchange unit and the lower layer of the last-stage heat exchange unit are respectively provided with an upper-layer clamping plate 3 and a lower-layer clamping plate 1. Each heat exchange unit includes a unit flow collector 8 stacked sequentially, several heat exchange plate pairs and a unit partition 9. Each heat exchange plate pair is provided with a hot-side flow channel, a cold-side flow channel and a pre-cooling flow channel.

[0033] The system has a total inlet and outlet for hot fluid and a total inlet and outlet for cold fluid, which run through all heat exchange units. Each unit manifold 8 has a hot fluid diversion inlet and outlet, as well as a cold fluid diversion inlet and outlet. The total inlet and outlet for hot fluid are connected to the hot fluid diversion inlet and outlet of each heat exchange unit's unit manifold 8, respectively. The total inlet and outlet for cold fluid are connected to the cold fluid diversion inlet and outlet of each heat exchange unit's unit manifold 8. The hot fluid diversion inlet of the unit manifold 8 is connected to the hot-side channel of each heat exchange plate pair, the outlet of the hot-side channel is connected to the pre-cooling channel, and the outlet of the pre-cooling channel is connected to the hot fluid diversion outlet of the unit manifold 8. The cold fluid diversion inlet and outlet of the unit manifold 8 are connected to the outlet and inlet of each cold-side channel of each heat exchange plate pair, respectively.

[0034] The total inlet and outlet of the hot fluid, as well as the total inlet and outlet of the cold fluid, are used to connect with the hot and cold sides of the Brayton cycle system and form a circulation. The total inlet is used to guide the fluid to each heat exchange unit, and the total outlet is used to collect the inflow after heat exchange and guide it to the Brayton cycle system. The total inlet and outlet of the fluid form four through channels on the entire heat exchanger, namely through all heat exchange plates and units, unit manifolds 8 and unit baffles 9.

[0035] See Figure 3 The figure is a plan view of the unit manifold 8. As the uppermost plate of each heat exchange unit, the unit manifold 8 guides the fluid from the main inlet to the hot and cold flow channels of the heat exchange unit and then returns the heat-exchanged fluid to the main outlet.

[0036] The unit manifold 8 is equipped with a hot-side axial inlet 4, a precooling module axial outlet 5, a cold-side axial outlet 6, and a cold-side axial inlet 7, which are part of the total inlet and outlet of the hot and cold fluids. The hot-side axial inlet 4 is connected to the total inlet of the hot fluid, the precooling module axial outlet 5 is connected to the total outlet of the hot fluid, the cold-side axial outlet 6 is connected to the total inlet of the cold fluid, and the cold-side axial inlet 7 is connected to the total outlet of the cold fluid.

[0037] The unit manifold 8 is also provided with a unit axial hot-side inlet 12, a unit axial cold-side outlet 13, a unit axial cold-side inlet 14, and a unit precooling module axial outlet 15. The unit axial hot-side inlet 12 is connected to the hot-side axial inlet 4 through a flow channel. The unit axial hot-side inlet 12 is connected to the hot-side flow channel of each heat exchange plate pair. The unit precooling module axial outlet 15 is connected to the precooling module axial outlet 5 through a flow channel. The unit precooling module axial outlet 15 is connected to the precooling flow channel outlet of each heat exchange plate pair. The unit axial cold-side outlet 13 is connected to the cold-side axial outlet 6 through a flow channel. The unit axial cold-side outlet 13 is connected to the cold-side flow channel outlet of each heat exchange plate pair. The unit axial cold-side inlet 14 is connected to the cold-side axial inlet 7 through a flow channel. The unit axial cold-side inlet 14 is connected to the cold-side flow channel inlet of each heat exchange plate pair.

[0038] The hot-side axial inlet 4, the precooling module axial outlet 5, the cold-side axial outlet 6, and the cold-side axial inlet 7 are all arc-shaped strip structures, and are evenly distributed on the unit collector plate 8.

[0039] See Figure 4The figure shows a schematic diagram of the unit partition 8. The unit partition is used to separate the lowest cold flow plate of the upper heat exchange unit from the unit flow collector of the adjacent lower heat exchange unit, so that each heat exchange unit forms a closed flow channel. In order to avoid the unit partition from blocking the fluid, the unit partition is provided with the following components: hot side axial inlet 4, precooling module axial outlet 5, cold side axial outlet 6, cold side axial inlet 7, hot side axial inlet 4, unit axial hot side inlet 12, unit axial cold side outlet 13, unit axial cold side inlet 14 and unit precooling module axial outlet 15.

[0040] The heat exchange unit includes a regeneration module and a precooling module. The regeneration module includes several pairs of heat exchange plates, each pair including two stacked cold fluid plates 10 and hot fluid plates 11. (See reference...) Figure 5 This figure is a schematic diagram of the structure of the heat transfer plate 11. (See attached diagram.) Figure 6 This is a schematic diagram of the structure of the heat fluid plate 10.

[0041] The heat exchanger plate 11 is an annular plate, and a hot-side flow channel 18 is provided on one side of the heat exchanger plate 11. The structure of the heat exchanger plate 10 is the same as that of the heat exchanger plate body, and a cold-side flow channel 22 is provided on one side of the heat exchanger plate 10. The precooling module includes a shell composed of multiple shell plates 17 stacked together. An annular precooling flow channel 19 is provided on one side of each shell. The shell is fitted on the outer wall of the heat exchanger module, and a vacuum insulation cavity is provided between the shell and the heat recovery module. Each shell plate is arranged in the same plane as the heat exchanger plate 11 and the heat exchanger plate 10.

[0042] The hot-side flow channel 18 is an annular groove. The inlet of the hot-side flow channel 18 is connected to the axial hot-side inlet 12 of the unit. The outlet of the hot-side flow channel 18 is connected to the diversion hole 20 through the flow channel. The diversion hole 20 is connected to the pre-cooling flow channels of the two shell plates corresponding to the heat exchange plate. That is, the hot fluid enters the hot-side flow channel 18 through the axial hot-side inlet 12 of the unit, and then flows to the diversion hole 20. The diversion hole divides the hot fluid into two paths, which enter the pre-cooling flow channel 6 corresponding to the hot fluid plate and the pre-cooling flow channel corresponding to the lower cold fluid plate, respectively. The hot fluid in the two pre-cooling flow channels enters the axial outlet of the unit pre-cooling module from the outlet of the pre-cooling flow channel, and then merges into the total hot fluid outlet through the axial outlet of the pre-cooling module.

[0043] The outlet of the hot side flow channel 18 is connected to the diversion hole through the baffle flow channel. The baffle flow channel is arranged radially along the hot flow plate and extends towards the outer ring wall of the hot flow plate. The diversion hole is connected to the pre-cooling flow channel corresponding to the hot flow plate and the pre-cooling flow channel corresponding to the lower cold flow plate, respectively. In other words, after heat exchange, the hot fluid is divided into two paths and enters the heat exchange plate to perform secondary heat exchange with the external seawater in the pre-cooling flow channels of the two corresponding shell plates.

[0044] The hot runner 18 is provided with multiple concentric flow dividers, which are arranged at intervals from the inside out, dividing the hot runner into multiple flow dividers. The width of the multiple flow dividers decreases from the inside out. Since the length of the flow divider inside the circumference is shorter, the width of the inner flow divider is greater than the width of the outer flow divider, making the heat exchange of each flow divider more uniform.

[0045] The heat flow plate is also provided with a cold unit axial cold side outlet 13, a unit axial cold side inlet 14, a hot side axial inlet 4, a precooling module axial outlet 5, a cold side axial outlet 6, and a cold side axial inlet 7.

[0046] The precooling channel 19 is an annular channel. The inlet of the precooling channel 19 is directly opposite the diversion hole 20. The precooling outlet of the precooling channel is connected to the axial outlet 15 of the unit precooling module. The axial outlet 15 of the unit precooling module is symmetrically arranged with the diversion hole along the center of the hot fluid plate. A diversion baffle 21 is provided at the inlet of the precooling channel 19 to divide the hot fluid into two paths in the precooling channel. The two hot fluids flow in opposite directions and flow out through the axial outlet 15 of the unit precooling module after merging. A baffle is provided in the middle of the axial outlet 15 of the unit precooling module to avoid the two hot fluids from colliding when they merge.

[0047] The hot fluid plate is concentrically fitted with the shell plate on the same plane, and a vacuum groove is provided between the hot fluid plate and the shell plate. The hot fluid plate and the shell plate are connected by a flow channel between the hot side flow channel outlet and the pre-cooling flow channel inlet. The flow diversion hole is located on the flow channel, and multiple connecting ribs are provided in the vacuum groove to improve the connection strength between the shell plate and the hot fluid plate.

[0048] See again Figure 6 The cold side flow channel 22 is an annular groove. The inlet of the cold side flow channel 8 is connected to the unit axial cold side inlet 14. The outlet of the cold side flow channel 8 is connected to the unit axial cold side outlet 13 through the guide zone. The structure of the cold side flow channel 8 is the same as that of the hot side flow channel, and both are equipped with a flow splitting ring, which will not be described in detail.

[0049] The hot fluid plate and cold fluid plate are integrally formed with the shell plate on the same plane. The hot-side flow channel, cold-side flow channel, and pre-cooling flow channel are all processed by mechanical machining or photochemical etching. The cross-section of the hot-side and cold-side flow channels can be rectangular, semi-circular, or elliptical, with a hydraulic diameter of 1-3 mm. The fluids in the hot-side and cold-side flow channels flow in opposite directions. Each branch channel of the hot-side and cold-side flow channels is equipped with a turbulence structure, which can be a direct flow channel, a Z-shaped channel, or an S-shaped channel. The pre-cooling flow channel shown in the figure is Z-shaped, with an inclination angle of 5-45°, which increases the optimization space for heat exchange and flow resistance and can meet the design requirements of multiple heat exchange conditions. In this embodiment, the thickness of the hot fluid plate and cold fluid plate is 1-4 mm. The hot fluid plate and cold fluid plate are made of stainless steel, aluminum alloy, copper alloy, or titanium alloy, with high welding quality and the ability to withstand seawater and carbon dioxide environments.

[0050] The following describes in detail a heat exchange method for a multi-stage heat exchange system for a submarine provided by the present invention, including the following steps:

[0051] Step 1: According to the rules of underwater vehicles, prepare several heat exchange units on the hull of the underwater vehicle, and install clamping plates at both ends of the first-stage heat exchange unit and the last-stage heat exchange unit.

[0052] Each heat exchange unit consists of multiple heat exchange plate pairs and is fitted onto the hull of the submersible. The heat exchanger is welded to the hull using vacuum welding, so that the entire heat exchanger and the submersible hull form an integral structure. While exchanging heat, the heat exchanger also serves as a pressure-bearing device, improving the pressure resistance of the submersible. The connection between the heat exchanger and the submersible saves the space required for arranging a fixed platform.

[0053] Step 2: Connect the heat exchanger's main hot flow inlet to the turbine outlet of the Brayton cycle system, and connect the heat exchanger's main hot flow outlet to the precooler inlet of the Brayton cycle system; connect the heat exchanger's main cold flow inlet to the compressor outlet of the Brayton cycle system, and connect the heat exchanger's main cold flow outlet to the cold side inlet of the regenerator of the Brayton cycle system.

[0054] This heat exchanger integrates the functions of the regenerator and precooler in the SCO2 Brayton cycle, with the fluid inlet and outlet integrated into one unit. This maximizes the use of the limited internal space of the submersible. Simultaneously, other shell sections can be used to provide pressure support for the upper and lower sides of the cylindrical heat exchanger, thus eliminating the need for thick clamping plates and reducing space occupation and overall weight. The integrated regenerator, precooler, and shell eliminate the need for pipe boxes, connecting pipelines, and fixed platforms, resulting in high space utilization. The integrated Brayton heat exchanger uses seawater outside the shell as a cold source, directly connecting the regenerator and precooler modules. Therefore, the entire unit requires only two fluid inlets and two outlets: a total axial inlet 4 on the hot side, a total axial inlet 7 on the cold side, a total axial outlet 5 for the precooler module, and a total axial outlet 6 on the cold side. Its modular design allows for the use of submersibles of different specifications.

[0055] Step 3: The hot fluid discharged from the turbine of the Brayton cycle system after doing work enters the heat exchange system through the total heat flow inlet. After entering the total heat flow inlet, the hot fluid undergoes the first stage of diversion. The diverted hot fluid enters each heat exchange unit from the total heat flow inlet of the unit manifold 8 for secondary diversion. After the secondary diversion, the hot fluid enters the hot side flow channel 18 of each heat flow plate 11 from the axial inlet 4 on the hot side along the flow channel.

[0056] The cold fluid pressurized by the compressor in the Brayton cycle system enters the heat exchange system through the cold flow main inlet. After entering the cold flow main inlet, the cold fluid undergoes a first-stage diversion. The diverted cold fluid then enters each heat exchange unit through the cold fluid main inlet of the unit manifold 8 for a second diversion. After the second diversion, the cold fluid enters the cold side flow channel 22 of each heat flow plate 11 along the flow channel from the cold side axial inlet 7.

[0057] Hot and cold fluids flow in opposite directions and exchange heat in the heat exchange plate pairs. After the cold fluids are heated by heat exchange in each heat exchange plate pair, they enter the unit manifold 8 from the cold side axial outlet 6 and then enter the total cold fluid outlet before entering the cold side inlet of the regenerator of the Brayton cycle system.

[0058] After the heat exchangers have cooled down, the hot fluid enters the two pre-cooling channels of the heat exchanger through the diversion holes. Under the action of the diversion baffle 21, the hot fluid is divided three times to form two opposing hot fluids. The hot fluid is cooled a second time in the pre-cooling channels by the seawater in the external environment of the submersible. After the second cooling, the hot fluid enters the unit manifold 8 from the axial outlet 15 of the unit pre-cooling module and then enters the axial outlet of the pre-cooling module. After entering the total outlet of the cold fluid, it enters the cold side inlet of the regenerator of the Rayton cycle system.

[0059] The following are the flow paths of the hot and cold fluids:

[0060] Hot-side fluid: Hot-side axial total inlet 4 → Unit manifold 8 → Unit axial hot-side inlet 12 → Hot-side flow channel 18 → Flow divider 20 and flow divider 21 → Pre-cooling flow channel 19 → Unit pre-cooling module axial outlet 15 → Unit manifold 8 → Pre-cooling module axial total outlet 5.

[0061] Cold side fluid: Cold side axial total inlet 7 → Unit manifold 8 → Unit axial cold side inlet 14 → Cold side flow channel 22 → Unit axial cold side outlet 13 → Unit manifold 8 → Cold side axial total inlet 7.

[0062] The entire heat exchanger consists of several heat exchange units, achieving three-stage flow distribution and convergence. The high-mass-flow working fluid undergoes multi-stage flow distribution / convergence heat exchange within the heat exchange units, resulting in more uniform flow distribution within a single channel and improved heat exchange performance. Secondly, the hot and cold channels as well as the precooling channel adopt an annular structure. In a diffusion welding furnace of the same volume, this allows for the fabrication of longer channels compared to traditional rectangular printed circuit board heat exchangers, while also reducing flow resistance compared to multi-stage baffled channels. Furthermore, a vacuum insulation cavity is set between the regenerating module and the precooling module of each heat exchange unit to reduce coupled heat transfer and ensure efficient operation of the heat exchanger. When the core expands at high temperatures, the vacuum layer provides a space margin, improving the safety of the heat exchanger.

[0063] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A multi-stage heat exchange system for a submersible vehicle, the system comprising: The application relates to a heat exchange device, which comprises a plurality of sequentially connected heat exchange units, each heat exchange unit comprising sequentially stacked unit headers (8), a plurality of heat exchange plate pairs and unit separators (9), each heat exchange plate pair being provided with a hot side flow channel, a cold side flow channel and a precooling flow channel; the heat exchange plate pair comprises stacked hot fluid plates and cold fluid plates, the hot side flow channel and the cold side flow channel are arranged on the hot fluid plates and the cold fluid plates respectively, a precooling module is arranged outside the hot fluid plates and the cold fluid plates, the precooling module comprises stacked shell plates, the hot fluid plates and the cold fluid plates are integrally formed with the same plane shell plates, the precooling flow channel is arranged on the side wall of the shell plate, a vacuum heat insulation cavity is arranged between the precooling module and the hot fluid plates and the cold fluid plates; the outlet of the hot side flow channel is communicated with the precooling flow channel of the same plane shell plate through a flow channel, a flow distribution hole is arranged on the flow channel, the flow distribution hole is communicated with the inlet of the precooling flow channel of the lower shell plate; the inlets of the hot side flow channel and the cold side flow channel of each heat exchange plate pair of each heat exchange unit are respectively connected with the turbine outlet and the compressor outlet of a Brayton cycle system through the hot fluid inlet channels and the cold fluid inlet channels of the unit headers (8), the outlet of the hot side flow channel of the heat exchange plate pair is connected with the precooling flow channel, the outlet of each precooling flow channel is connected with the compressor inlet of the Brayton cycle system through the hot fluid outlet channels of the unit headers (8), and the outlet of each cold side flow channel is connected with the heat source inlet of the Brayton cycle system through the cold fluid outlet channels of the unit headers (8).

2. The multi-stage heat exchange system of a submersible vehicle according to claim 1, wherein, The unit header (8) is provided with a hot side axial inlet (4), a precooling module axial outlet (5), a cold side axial outlet (6) and a cold side axial inlet (7); The hot side axial inlet (4) is communicated with the inlet of the hot side flow channel of each heat exchange plate pair through a flow channel, the precooling module axial outlet (5) is connected with the outlet of each precooling flow channel through a flow channel, the cold side axial outlet (6) is connected with the outlet of the cold side flow channel of each heat exchange plate pair through a flow channel, and the cold side axial inlet (7) is connected with the inlet of the cold side flow channel of each heat exchange plate pair through a flow channel.

3. The multi-stage heat exchange system of a submersible vehicle according to claim 1, wherein, The plurality of heat exchange units are provided with axially arranged hot fluid total inlet channels, precooling fluid total outlet channels, cold fluid total inlet channels and cold fluid total outlet channels; The hot fluid total inlet channels are respectively connected with the hot side axial inlets (4) of each unit header (8), the precooling fluid total outlet channels are respectively communicated with the precooling module axial outlets (5) of each unit header (8), the cold fluid total inlet channels are respectively communicated with the cold side axial inlets (7) of each unit header (8), and the cold fluid total outlet channels are respectively communicated with the cold side axial outlets (6) of each unit header (8).

4. The multi-stage heat exchange system of a submersible vehicle according to claim 1, wherein, The inlet of the precooling flow channel is provided with a flow distribution separator, so that the precooling flow channel forms two flow channels, and the hot fluid in the two flow channels flows in opposite directions.

5. The multi-stage heat exchange system of a submersible vehicle according to claim 1, wherein, A plurality of concentric flow distribution rings are arranged in the hot side flow channel and the cold side flow channel, the hot flow channel is divided into a plurality of flow distribution channels, and the widths of the plurality of flow distribution channels decrease from inside to outside.

6. The multi-stage heat exchange system of a submersible vehicle according to claim 1, wherein, The hot side flow channel and the cold side flow channel of the heat exchange plate pair are arranged in a reverse flow mode.

7. The multi-stage heat exchange system of a submersible vehicle according to claim 1, wherein, The hot side flow channel and the cold side flow channel are provided with a flow disturbing structure.

8. A method for multi-stage heat exchange of a multi-stage heat exchange system of a submersible vehicle according to any one of claims 1 to 7, characterized in that, The hot fluid and the cold fluid of the Brayton cycle system are divided once and then enter the hot fluid inlet channels and the cold fluid inlet channels of the unit header plates of the heat exchange units; The hot fluid inlet channels and the cold fluid inlet channels of the unit header plates divide the hot fluid and the cold fluid again, so that the hot fluid and the cold fluid enter the hot side flow channels and the cold side flow channels of the heat exchange plate pairs and are subjected to primary heat exchange; The heat exchange-cooled hot fluid is divided three times and then enters two pre-cooling flow channels corresponding to the heat exchange plate pairs, is subjected to secondary heat exchange with seawater, and then flows out of the unit header plates through the hot fluid outlet channels before being mixed with the secondary-cooled hot fluid of the heat exchange units and entering the compressor of the Brayton cycle system; The heat exchange-heated cold fluid is mixed in the cold fluid outlet channels of the unit header plates, and then is mixed with the heated cold fluid of the heat exchange units before entering the heat source of the Brayton cycle system.

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