A Brayton cycle integrated heat exchanger and heat exchange method for a submersible

Abstract

This invention discloses a Brayton cycle integrated heat exchanger and heat exchange method for a submersible, comprising a regenerating module and a precooling module. The regenerating module includes several alternately stacked hot and cold flow plates. The precooling module is fitted outside the regenerating module, and a vacuum insulation cavity exists between the precooling module and the regenerating module. The heat exchanger is integrally machined with the submersible's shell. As part of the heat exchanger, the heat exchanger increases the shell thickness of the submersible, improving its compressive strength, while simultaneously reducing the shell thickness and the submersible's weight. A vacuum cavity is provided between the regenerating module and the precooling module. After the hot and cold fluids exchange heat once in the regenerating module, they then enter the precooling module for a secondary heat exchange with the surrounding seawater, improving heat exchange efficiency. The vacuum insulation cavity reduces coupling and provides deformation space for the thermal expansion of the regenerating module, improving the operational safety of the submersible.

Description

Technical Field

[0001] This invention relates to the field of heat exchange technology for submersibles, specifically to an integrated Brayton cycle heat exchanger and heat exchange method for submersibles. Background Technology

[0002] Small submersibles are primarily powered by electricity, while large submersibles mainly use thermal power, including steam Rankine cycle systems and Brayton cycle systems.

[0003] Conventional thermal power primarily utilizes the steam Rankine cycle, but this system is bulky, heavy, and inefficient. In contrast, the supercritical carbon dioxide Brayton cycle offers low compression power consumption, high efficiency, and a more compact structure, representing the future trend in underwater thermal power systems. The heat exchange equipment in a Brayton cycle system mainly includes a regenerator and a precooler, whose heat exchange capacity limits system efficiency. Furthermore, its application in submersibles faces challenges such as space constraints and high-temperature, high-pressure working fluids. Therefore, designing and developing a supercritical carbon dioxide Brayton cycle heat exchanger for submersibles that meets the requirements of confined spaces while offering high efficiency and safety is crucial. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides an integrated Brayton cycle heat exchanger for submersibles. This heat exchanger has a compact structure and is resistant to high temperature and high pressure, thereby improving the underwater operation safety of submersibles.

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

[0006] An integrated Brayton cycle heat exchanger for a submersible includes a regenerative module and a precooling module;

[0007] The regenerative module is a hollow columnar structure, which includes several alternately stacked hot flow plates and cold flow plates. The end face of the hot flow plate forms a hot side flow channel, and the end face of the cold flow plate forms a cold side flow channel.

[0008] The precooling module is sleeved outside the regenerating module, and there is a vacuum insulation cavity between the precooling module and the regenerating module. The precooling module includes several shell plates, and a precooling flow channel is provided on one side of the shell plate.

[0009] The outlets of the hot-side flow channels are respectively connected to the precooling flow channels of the concentric shell plates and the inlet of the precooling flow channels of the lower shell plate. After the hot fluid in the hot-side flow channel exchanges heat with the cold fluid in the cold-side flow channel, it enters the precooling flow channels of the two adjacent shell plates to exchange heat with the external environment of the submarine before flowing out.

[0010] 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.

[0011] Preferably, the flow divider rings of the cold flow plate and the hot flow plate are arranged with the same diameter.

[0012] Preferably, a vacuum insulation groove is provided between the hot flow plate and the cold flow plate and the shell plate on the same plane, and multiple stiffeners are provided in the vacuum insulation layer and evenly distributed around the circumference for connecting the shell plate on the same plane and the hot flow plate or the cold flow plate.

[0013] Preferably, 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, and the flow channel is provided with a diversion hole, which is connected to the inlet of the pre-cooling flow channel of the lower shell plate.

[0014] Preferably, the precooling channel comprises two semi-annular channels in which the hot fluid flows in opposite directions.

[0015] Preferably, the inlet of the precooling channel is provided with a flow divider, and the outlet of the precooling channel is provided with a baffle.

[0016] Preferably, the working fluid in the hot-side flow channel and the cold-side flow channel flows in opposite directions.

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

[0018] A heat exchange method for an integrated Brayton cycle heat exchanger for a submersible includes the following processes:

[0019] In the Brayton cycle system, the hot fluid flows into the hot-side channels of each hot flow plate, while the cold fluid flows into the cold-side channels of each cold flow plate. The hot and cold fluids flow in opposite directions to exchange heat. The heated cold fluid enters the Brayton cycle system, while the cooled hot fluid is split and enters the pre-cooling channels corresponding to the hot flow plate and the lower cold flow plate. The hot fluid undergoes secondary heat exchange with seawater in the pre-cooling channels before entering the Brayton cycle system.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention provides an integrated Brayton cycle heat exchanger for a submersible. The heat exchanger is integrally machined with the submersible's shell, increasing the shell thickness and improving its pressure resistance while reducing its weight. A vacuum chamber is provided between the regenerator and precooling modules. After primary heat exchange in the regenerator, the hot and cold fluids then enter the precooler for secondary heat exchange with the surrounding seawater, improving heat exchange efficiency. The use of annular flow channels allows for longer flow channels compared to traditional rectangular printed circuit board heat exchangers, while also reducing flow resistance compared to multi-stage baffled flow channels. Due to the shorter length of the inner circumferential flow channel, the inner width of the plate heat exchange channel is wider than the outer width, resulting in more uniform heat exchange between the inner and outer channels. Furthermore, the vacuum insulation chamber reduces coupled heat transfer and provides deformation space for the thermal expansion of the regenerator, improving the submersible's operational safety. As the entire heat exchanger serves as a pressure-bearing component of the submersible, it saves the space required for a fixed platform. Attached Figure Description

[0022] Figure 1 This is an exploded schematic diagram of the heat exchanger core of the present invention.

[0023] Figure 2 This is a schematic diagram of the heat fluid plate of the present invention.

[0024] Figure 3 This is a schematic diagram of the cold fluid plate of the present invention.

[0025] In the diagram: 1-Upper pressure plate, 2-Hot flow plate, 3-Cold flow plate, 4-Lower pressure plate, 5-Flow divider, 6-Pre-cooling channel, 7-Vacuum insulation tank, 8-Cold side channel, 9-Cold side axial outlet, 10-Hot side axial inlet, 11-Shell plate, 12-Cold side axial inlet, 13-Flow divider hole, 14-Hot side channel, 15-Pre-cooling outlet. Detailed Implementation

[0026] 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.

[0027] See Figure 1 A Brayton cycle integrated heat exchanger for a submarine includes a regenerative module and a precooling module.

[0028] The regenerative module is a hollow columnar structure, which includes several alternately stacked hot flow plates 2 and cold flow plates 3. The end face of the hot flow plate 2 forms a hot side flow channel 14, and the end face of the cold flow plate 3 forms a cold side flow channel 8. The precooling module includes several precooling channels, which are respectively disposed on the hot flow plate 2 and the cold flow plate 3, and the precooling channels are sleeved on the outside of the hot side flow channel 14 and the cold side flow channel 8.

[0029] The regenerating module is provided with a hot flow axial inlet channel, a precooling module axial outlet channel, a cold flow axial inlet channel, and a cold flow axial outlet channel along its axial direction. The inlet of each hot-side channel 14 is connected to the hot flow axial inlet channel, and the outlet of each hot-side channel 14 is connected to the inlet of the precooling channel on the same hot flow plate and the inlet of the precooling channel on the lower cold flow plate 3, respectively. The outlet and inlet of each precooling channel are connected to the cold flow axial inlet channel and the cold flow axial outlet channel, respectively.

[0030] See Figure 2 The heat flow plate is an annular plate with an inner diameter the same as the outer diameter of the submarine's hull. The heat flow plate is used to fit onto the submarine's hull. The heat-side flow channel 14 is an annular groove. The heat flow plate is provided with a heat-side axial inlet 10 and a diversion hole 13. The inlet of the heat-side flow channel 14 is connected to the heat-side axial inlet 10, and the outlet of the heat-side flow channel 14 is connected to the diversion hole 13. The diversion hole 13 is connected to the pre-cooling flow channel of the heat flow plate and the pre-cooling flow channel of the cold flow plate 3, respectively. That is, the heat flow enters the heat-side flow channel 14 through the heat-side axial inlet 10 and then flows to the diversion hole 13. The diversion hole divides the heat flow into two paths, which enter the pre-cooling flow channel 6 of the heat flow plate and the pre-cooling flow channel of the lower cold flow plate, respectively. The heat flow in the two pre-cooling flow channels enters the axial flow outlet of the pre-cooling module from the outlet of the pre-cooling flow channel and then enters the Brayton cycle system.

[0031] The hot runner 14 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.

[0032] The hot flow plate is provided with a hot-side axial inlet 10 and a flow divider 13. The hot-side axial inlet 10 is connected to the inlet of each flow divider through a flow guide area. The outlet of the hot-side flow channel 14 is a baffled flow channel connected to the flow divider. The baffled flow channel is arranged radially along the hot flow plate and extends towards the outer ring wall of the hot flow plate. The flow divider is connected to the precooling flow channel of the hot flow plate and the precooling flow channel of the lower cold flow plate, respectively.

[0033] The hot flow plate is also provided with a cold side axial inlet 12 and a cold side axial outlet, which serve as through holes for the cold flow axial inflow channel and the cold flow axial outflow channel. The cold side axial inlet 12 is used to connect the inlet of the cold side flow channel 8 of two adjacent cold flow plates, and the cold side axial outlet is used to connect the outlet of the cold side flow channel 8 of two adjacent cold flow plates.

[0034] The precooling channel 6 on the hot runner plate is an annular channel. The inlet of the precooling channel 6 is directly opposite the diversion hole 13. The precooling outlet 15 of the precooling channel is symmetrically arranged along the center of the hot runner plate and the inlet. A diversion baffle 5 is provided at the inlet of the precooling channel 6 to divide the hot fluid into two paths in the precooling channel. The two paths flow in opposite directions and then flow out through the outlet of the precooling module axial flow outlet after merging. A baffle is provided in the middle of the outlet of the precooling channel to prevent the two paths of hot fluid from colliding when they merge.

[0035] The heat flow plate is concentrically fitted with a shell 11. An annular vacuum insulation groove 7 is provided between the shell 11 and the heat flow plate. Multiple ribs are provided in the vacuum insulation groove 7. The multiple ribs are evenly distributed around the circumference to improve the connection strength between the shell and the heat flow plate 2.

[0036] See Figure 3 The cold flow plate 3 is an annular plate with an inner diameter that is the same as the outer diameter of the submarine's hull. The cold flow plate 3 is used to fit onto the submarine's hull. The cold side flow channel 8 is an annular groove. The cold flow plate 3 is provided with a cold side axial outlet 9 and a cold side axial inlet 12. The inlet of the cold side flow channel 8 is connected to the cold side axial inlet 12, and the outlet of the cold side flow channel 8 is connected to the cold side axial outlet 9.

[0037] The cold-side flow channel 8 is provided with multiple concentric flow-dividing rings, which are arranged at intervals from the inside out, dividing the cold-side flow channel 8 into multiple flow channels. The width of the multiple flow channels decreases from the inside out. Since the length of the flow channel within the circumference is shorter, the width of the inner flow channel is greater than that of the outer flow channel, making the heat exchange of each flow channel more uniform. The outlets of the multiple flow channels are connected to the cold-side axial outlet 9 through the guide zone. The cold fluid enters the cold-side flow channel 8 through the cold-side axial inlet 12, then flows to the cold-side axial outlet 9, and enters the cold flow axial outflow channel before entering the Brayton cycle system.

[0038] The precooling channel 6 on the cold runner plate is an annular channel. The inlet of the precooling channel 6 is connected to the flow divider hole 13 of the hot runner plate. The precooling outlet 15 of the precooling channel is in the same position and structure as the precooling outlet 15 on the hot runner plate side. A flow divider 5 is provided at the inlet of the precooling channel 6 on the cold runner plate side to divide the hot fluid into two paths in the precooling channel. The two paths flow in opposite directions and then flow out through the outlet of the precooling module axial flow outlet after merging. A baffle is provided in the middle of the outlet of the precooling channel to prevent the two paths of hot fluid from colliding when they merge.

[0039] The cold flow plate is concentrically fitted with a shell 11, and an annular vacuum insulation groove 7 is provided between the shell 11 and the cold flow plate. Multiple ribs are provided in the vacuum insulation groove 7, evenly distributed around the circumference, to improve the connection strength between the shell and the cold flow plate. The cold flow plate is also provided with a hot-side axial inlet, which connects to the inlets of the hot-side flow channels 8 of two adjacent hot flow plates.

[0040] The hot-side channels, cold-side channels, and pre-cooling channels on the hot and cold runner plates are all machined by mechanical processing or photochemical etching. The cross-sections of the hot and cold runner channels can be rectangular, semi-circular, or elliptical, with a hydraulic diameter of 1–3 mm. Each branch channel of the hot and cold runner channels is equipped with a turbulence-inducing structure, which can be a direct-flow channel, a Z-shaped channel, or an S-shaped channel. The fluids in the hot and cold runner channels flow in opposite directions. In this embodiment, the thickness of the hot and cold runner plates is 1–4 mm. The hot and cold runner plates are made of stainless steel, aluminum alloy, copper alloy, or titanium alloy, with high welding quality, and can withstand seawater and carbon dioxide environments.

[0041] The regenerative module is provided with an upper pressure plate 1 and a lower pressure plate 4 at both ends. The upper pressure plate 1 is provided with a hot fluid inlet and outlet, a cold fluid inlet and outlet, and is connected to the hot fluid axial inflow channel, the precooling module axial flow outlet, the cold fluid axial inflow channel and the cold fluid axial outflow channel, respectively. Adjacent hot flow plates and cold flow plates are solid-state welded by vacuum diffusion welding, and the inner ring walls of the hot flow plates and cold flow plates are welded to the hull of the submersible. After all the hot flow plates and cold flow plates are alternately stacked and welded, the hot side axial inlets 10 of all the hot flow plates and cold flow plates form the hot fluid axial inflow channel, the precooling channel outlets of all the hot flow plates and cold flow plates form the precooling module axial flow outlet, the cold side axial inlets 12 of all the hot flow plates and cold flow plates form the cold fluid axial inflow channel, and the cold side axial outlets 9 of all the hot flow plates and cold flow plates form the cold fluid axial outflow channel.

[0042] See again Figure 1 The heat exchange method of the Brayton cycle integrated heat exchanger for the submersible of the present invention will be described in detail below, including the following steps:

[0043] Step 1: Using vacuum diffusion welding technology, the upper clamping plate, several hot fluid plates, cold fluid plates, and lower clamping plate are solid-phase welded to form a heat exchanger;

[0044] The shell plates on the hot and cold flow plates form the outer shell, and the vacuum insulation grooves on the hot and cold flow plates form the vacuum insulation cavity. The cavity is evacuated to a vacuum and sealed, leaving a safety margin for thermal expansion. The entire heat exchanger body is machined simultaneously with the submarine hull to form an integrated pressure-bearing device.

[0045] The diameters of the flow rings in the hot-side flow channel 14 and the cold-side flow channel 8 are the same, forming rigid support for the two adjacent hot and cold flow plates, thereby improving the rigidity of the entire heat exchanger.

[0046] Step 2: The heat flow axial inlet channel of the heat exchanger is connected to the turbine outlet of the Brayton cycle system. The heat flow that does work on the turbine enters the hot side channel of each heat flow plate from the heat flow axial inlet channel. The axial outlet of the precooling module is connected to the precooler inlet of the Brayton cycle system.

[0047] The axial inflow channel of the cold flow is connected to the compressor outlet of the Brayton cycle system, and the axial outflow channel of the cold flow is connected to the cold side inlet of the regenerator of the Brayton cycle system.

[0048] Step 3: After the hot fluid enters the hot flow axial confluence channel, it is split. After the split, the hot fluid enters the hot side flow channel 14 of each hot flow plate through the hot side axial inlet 10. After the cold fluid enters the cold flow axial confluence channel, it is split. After the split, the hot fluid enters the cold side flow channel 8 of each cold flow plate through the cold side axial inlet 12.

[0049] The hot fluid and the cold fluid exchange heat. The cold fluid that has been heated by the heat exchange enters the cold flow axial outlet channel through the outlet of the cold side channel 8, and then enters the Brayton cycle system.

[0050] After heat exchange and cooling, the hot fluid passes through the diversion holes into the pre-cooling channels 6 of the hot flow plate and the lower cold flow plate, and is divided into two streams that flow in opposite directions in the pre-cooling channels. It then exchanges heat with the seawater outside the shell for a second time. After cooling down again, the hot fluid enters the axial flow outlet of the pre-cooling module and enters the Brayton cycle system.

[0051] In this embodiment, the heat transfer fluid is SCO2.

[0052] The Brayton cycle integrated heat exchanger for submersibles provided by this invention has the following beneficial effects:

[0053] 1. The printed circuit board heat exchanger is processed simultaneously with the submarine shell to form an integrated pressure-bearing device. The heat exchanger does not require an additional fixed platform, and other shell sections can be used to bear pressure on the upper and lower sides of the column heat exchanger. Therefore, a thicker clamping plate is not required, reducing space occupation and the weight of the whole machine. The regenerator, precooler and shell are integrated into one unit, eliminating the need for pipe boxes and connecting pipelines, resulting in high space utilization.

[0054] 2. The heat exchanger has a vacuum or vacuum packing insulation layer between the regeneration and precooling modules to reduce coupled heat transfer and ensure the efficient operation of the heat exchanger. When the regeneration module expands at high temperature, the vacuum insulation layer provides space margin, which improves the safety of the heat exchanger and reduces the impact of coupled heat transfer between modules.

[0055] 3. The heat exchanger's regeneration and precooling module divides the core into several pairs of cold and hot fluid plates through flow dividers and baffles, and forms four precooling channels of the same length in each pair of plates to improve cooling efficiency.

[0056] 4. The hot and cold side flow channels of this heat exchanger are the entire circumference. In a diffusion welding furnace of the same volume, the flow channels can be processed to be longer than those of a traditional rectangular printed circuit board heat exchanger, and the flow resistance is smaller than that of a multi-stage baffle flow channel.

[0057] 5. In this invention, since the inner length of the circumferential flow channel is relatively short, the inner width of the plate heat exchange flow channel is wider than that of the outer side, making the heat exchange of the inner and outer flow channels more uniform. At the same time, the flow channel shape can adopt Z-shape, S-shape, etc., which increases the optimization space of heat exchange and flow resistance and can meet the design requirements of multiple heat exchange conditions.

[0058] 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 Brayton cycle integrated heat exchanger for a submersible, characterized in that, Includes a regenerating module and a precooling module; The regenerative module is a hollow columnar structure, which includes several alternating hot flow plates (2) and cold flow plates (3). The end face of the hot flow plate (2) forms a hot side flow channel (14), and the end face of the cold flow plate (3) forms a cold side flow channel (8). The precooling module is fitted outside the regenerating module, and there is a vacuum insulation cavity between the precooling module and the regenerating module. The precooling module includes several shell plates, and a precooling flow channel (6) is provided on one side of the shell plate. The outlet of the hot side flow channel (14) is connected to the precooling flow channel of the concentric shell plate and the inlet of the precooling flow channel of the lower shell plate. After the hot fluid in the hot side flow channel (14) exchanges heat with the cold fluid in the cold side flow channel, it enters the precooling flow channel of the two adjacent shell plates and exchanges heat with the external environment of the submarine before flowing out.

2. The Brayton cycle integrated heat exchanger for a submersible according to claim 1, characterized in that, Both the hot-side flow channel (14) and the cold-side flow channel are provided with multiple concentric flow dividers, which divide the hot flow channel into multiple flow dividers. The width of the multiple flow dividers decreases sequentially from the inside to the outside.

3. The Brayton cycle integrated heat exchanger for a submersible according to claim 2, characterized in that, The flow divider rings of the cold flow plate and the hot flow plate are arranged with the same diameter.

4. The Brayton cycle integrated heat exchanger for a submersible according to claim 1, characterized in that, Vacuum insulation grooves (7) are provided between the hot flow plate and the cold flow plate and the shell plate on the same plane, respectively. Multiple stiffeners are provided in the vacuum insulation layer and are evenly distributed around the circumference to connect the shell plate on the same plane and the hot flow plate or the cold flow plate.

5. The Brayton cycle integrated heat exchanger for a submersible according to claim 1, characterized in that, 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.

6. The Brayton cycle integrated heat exchanger for a submersible according to claim 1, characterized in that, The precooling channel comprises two semi-annular channels in which the hot fluid flows in opposite directions.

7. The Brayton cycle integrated heat exchanger for a submersible according to claim 6, characterized in that, The inlet of the precooling channel is equipped with a flow divider, and the outlet of the precooling channel is equipped with a baffle.

8. The Brayton cycle integrated heat exchanger for a submersible according to claim 1, characterized in that, The working fluids in the hot-side and cold-side channels flow in opposite directions.

9. The Brayton cycle integrated heat exchanger for a submersible according to claim 1, characterized in that, The hot-side and cold-side flow channels are equipped with turbulence structures.

10. A heat exchange method for a Brayton cycle integrated heat exchanger for a submersible according to any one of claims 1-9, characterized in that, The process includes the following: In the Brayton cycle system, the hot fluid flows into the hot-side channels of each hot flow plate, while the cold fluid flows into the cold-side channels of each cold flow plate. The hot and cold fluids flow in opposite directions to exchange heat. The heated cold fluid enters the Brayton cycle system, while the cooled hot fluid is split and enters the pre-cooling channels corresponding to the hot flow plate and the lower cold flow plate. The hot fluid undergoes secondary heat exchange with seawater in the pre-cooling channels before entering the Brayton cycle system.

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