Supercooled liquid methane refueling system and method of use

Abstract

The application relates to a supercooled liquid methane filling system and a use method, which comprises at least a liquid nitrogen uniform dispersion circulating type liquid methane supercooler. The supercooler comprises a supercooler shell and a heat exchange core arranged in the supercooler shell, the heat exchange core is communicated with a liquid methane entering communication pipe and a liquid methane flowing-out communication pipe, the supercooler shell is communicated with a nitrogen gas flowing-out communication pipe and a liquid nitrogen backflow communication pipe; a spraying mechanism is arranged above the heat exchange core in the supercooler shell, the liquid nitrogen backflow communication pipe is communicated with a backflow pipeline, the backflow pipeline is communicated with a first port of a first three-way pipe at the tail end, a second port of the first three-way pipe is communicated with a liquid nitrogen entering communication pipe, and a third port of the first three-way pipe is communicated with the spraying mechanism; the spraying mechanism is used for spraying liquid nitrogen to the inner wall of the supercooler shell and the heat exchange core; and the inner wall of the supercooler shell is provided with a liquid level meter. The application can avoid liquid methane crystallization, reduce time cost and avoid large waste of liquid methane.

Description

Technical Field

[0001] This invention relates to the field of supercooled liquid methane preparation technology, specifically to a supercooled liquid methane filling system and its usage method. Background Technology

[0002] Liquid methane, as a novel clean fuel, possesses characteristics such as being non-toxic and environmentally friendly, and has been widely used in many fields. For example, with the development of aerospace propulsion technology towards high specific impulse and reusability, and the increasing maturity of related liquid rocket technologies, the research and engineering application of liquid oxygen / liquid methane cryogenic propellant combinations are accelerating both domestically and internationally.

[0003] Liquid methane offers at least the following significant technological advantages in aerospace propulsion: 1. Liquid methane is widely available and can be produced on a large scale through various methods such as natural gas liquefaction and biomass conversion, with a production cost only about 1 / 10 that of liquid hydrogen. 2. At atmospheric pressure, the density of liquid methane (424 kg / m³) is much higher than that of liquid hydrogen (70.8 kg / m³). For the same fuel mass requirements, the refueling volume of liquid methane is only about 1 / 6 that of liquid hydrogen, significantly reducing the onboard tank volume. 3. Compared to liquid hydrogen refueling systems, which require high-grade vacuum insulated tanks and highly efficient refrigeration equipment, liquid methane refueling systems simplify insulation structure design, reduce the difficulty of selecting cryogenic materials for pipelines and valves, and decrease the energy consumption and operating costs of the refrigeration system. 4. Its specific impulse performance is approximately 15% higher than that of conventional ambient temperature propellants. Considering these characteristics, using liquid methane as a propellant has become the most widely used propellant solution in reusable large and medium-sized launch vehicles.

[0004] Because liquid methane has an extremely low boiling point, approximately 111 K at atmospheric pressure, it is highly susceptible to vaporization during its loading into rocket propellants. This vaporization, caused by external heat leakage and flow resistance, leads to a two-phase flow, resulting in instability during loading and potentially impacting efficiency and system safety. Furthermore, when used as a space propellant, liquid methane's thermodynamic state is typically close to its boiling point, limiting its thermophysical properties and resulting in lower density and sensible cooling per unit volume. For the same propellant mass, lower density significantly increases propellant tank volume, hindering lightweight rocket design. Conversely, lower sensible cooling per unit volume exacerbates vaporization losses during storage and loading, complicating replenishment procedures and ultimately negatively impacting launch timing, reliability, and overall cost.

[0005] Therefore, supercooling liquid methane before refueling, thus bringing its temperature below liquid saturation, has become the primary method to avoid the aforementioned situation. Valid data shows that when liquid methane is cooled from 110 K to 100 K (i.e., after becoming supercooled), its density increases from 424 kg / m³ to 438.15 kg / m³, a 3.3% increase. Therefore, supercooled liquid methane not only reduces evaporation losses during propellant storage but also significantly increases its mass and sensible cooling capacity, thereby significantly improving the effective payload capacity of launch vehicles.

[0006] Currently, existing technologies typically use supercoolers for the online real-time preparation of supercooled liquid methane. The general principle is as follows: liquid nitrogen is located in the shell side of the supercooler and serves as a cold source, while liquid methane flows in the tube side of the supercooler. By immersing the tube side in the shell side, the liquid methane in the tube side exchanges heat with the liquid nitrogen in the shell side to cool down, thereby preparing supercooled liquid methane.

[0007] However, the above-mentioned process for preparing supercooled liquid methane has at least the following drawbacks: 1. Since the crystallization temperature of liquid methane is about 90 K, while the temperature of liquid nitrogen at atmospheric pressure is about 77 K, which is significantly lower than the crystallization temperature of liquid methane, the liquid methane in the tube side of the existing supercooler may crystallize and block ice during the preparation of supercooled liquid methane, which will terminate the refueling process and affect the subsequent launch mission.

[0008] 2. After the subcooled liquid methane preparation is completed, liquid nitrogen will remain in the shell side of the subcooler. If the flow of liquid methane is stopped directly at this point, the liquid methane in the tube side immersed in the remaining liquid nitrogen will crystallize due to the excessively low temperature. Therefore, the liquid nitrogen level must be completely drained to the bottom of the liquid methane tube side before the flow of liquid methane can be stopped and the system can be shut down. However, this operation not only increases time costs but also results in a significant waste of liquid methane.

[0009] Therefore, there is an urgent need for a liquid methane subcooler that can effectively prevent liquid methane crystallization, reduce time costs, and avoid large-scale waste of liquid methane. Summary of the Invention

[0010] The purpose of this invention is to provide a subcooled liquid methane refueling system and its usage method to solve at least some of the technical problems existing in the prior art.

[0011] To achieve the above objectives, the present invention provides the following solution: In a first aspect, the present invention provides a subcooled liquid methane refueling system, comprising a liquid methane storage tank, a liquid nitrogen storage tank, and a liquid nitrogen uniformly dispersed circulating liquid methane subcooler, wherein: The liquid nitrogen uniformly dispersed circulating liquid methane subcooler includes a subcooler shell and a heat exchange core disposed within the subcooler shell; The heat exchange core is connected to a liquid methane inlet pipe and a liquid methane outlet pipe, and the top and bottom of the subcooler shell are respectively connected to a nitrogen outlet pipe and a liquid nitrogen return pipe. A spraying mechanism is installed inside the subcooler shell, and the spraying mechanism is located above the heat exchange core. The end of the liquid nitrogen reflux connecting pipe furthest from the subcooler shell is connected to a reflux pipeline, which is equipped with a cryogenic pump and a second control valve. The end of the reflux pipeline is connected to the first port of a first tee pipe, and the second port of the first tee pipe is connected to a liquid nitrogen inlet connecting pipe, which is equipped with a third control valve. The third port of the first tee pipe is connected to the spraying mechanism. The spraying mechanism is used to spray liquid nitrogen onto the inner wall of the subcooler shell and the heat exchange core to achieve precooling of the subcooler shell and heat exchange between liquid nitrogen and liquid methane. The liquid methane storage tank is connected to the liquid methane inlet connecting pipe, the liquid nitrogen storage tank is connected to the liquid nitrogen inlet connecting pipe, and the liquid methane outlet connecting pipe is used to connect to the rocket storage tank; A level gauge is installed on the inner wall of the subcooler shell. The level gauge is used to monitor the liquid nitrogen level in the subcooler shell so that the liquid nitrogen level is always lower than the heat exchange core. The subcooler also includes a central controller, and the cryogenic pump, the second control valve, the third control valve, and the level gauge are all communicatively connected to the central controller.

[0012] According to one embodiment of the present invention, the liquid methane inlet connecting pipe is connected to the bottom end of the heat exchange core, and the end of the liquid methane inlet connecting pipe away from the heat exchange core is located on the bottom outer side of the subcooler housing; The liquid methane outflow connecting pipe is connected to the top of the heat exchange core, and the end of the liquid methane outflow connecting pipe away from the heat exchange core is located on the top outer side of the subcooler shell.

[0013] According to one embodiment of the present invention, the spraying mechanism includes at least bottom uniform distribution holes and side uniform distribution holes; The third port of the first three-way pipe is connected to the first port of the second three-way pipe, and the second port and the third port of the second three-way pipe are respectively connected to the bottom equalizing hole and the side equalizing hole; The bottom uniform distribution holes are configured corresponding to the heat exchange core to spray liquid nitrogen introduced into the liquid nitrogen inlet connecting pipe and / or liquid nitrogen returning from the return pipe onto the heat exchange core. The side uniform distribution holes are configured corresponding to the inner wall of the subcooler shell to spray liquid nitrogen introduced into the liquid nitrogen inlet connecting pipe onto the inner wall of the subcooler shell.

[0014] According to one embodiment of the present invention, the spraying mechanism further includes a first branch pipe, a second branch pipe, and a plurality of parallel distributed pipes; The two ends of the uniform distribution tube are sealed structures, the side uniform distribution holes are opened in the outermost uniform distribution tube, and the bottom uniform distribution holes are opened in the remaining uniform distribution tubes except for the outermost layer. One end of the first branch pipe and one end of the second branch pipe are respectively connected to the third port and the second port of the second tee pipe. The other end of the first branch pipe is connected to the equalizing pipe with the side equalizing hole, and the other end of the second branch pipe is connected to the equalizing pipe with the bottom equalizing hole. The first branch pipeline is equipped with a fourth control valve, and the second branch pipeline is equipped with a fifth control valve. Both the fourth and fifth control valves are communicatively connected to the central controller.

[0015] According to one embodiment of the present invention, the level gauge is a differential pressure level gauge; The inner wall of the subcooler housing is provided with a precooling liquid level scale and a working liquid level scale. Both the precooling liquid level scale and the working liquid level scale are lower than the heat exchange core, and the working liquid level scale is located between the precooling liquid level scale and the heat exchange core. The differential pressure level gauge is used to monitor whether the liquid nitrogen level is at the same height as the precooled liquid level scale and whether the liquid nitrogen level is at the same height as the working liquid level scale.

[0016] According to one embodiment of the present invention, the return pipeline is provided with a first control valve, and the first control valve is communicatively connected to the central controller; The first control valve is located between the liquid nitrogen reflux connecting pipe and the cryogenic pump, and the second control valve is located between the first tee pipe and the cryogenic pump.

[0017] According to one embodiment of the present invention, the bottom end of the subcooler housing is connected to a liquid nitrogen discharge pipe, and the liquid nitrogen discharge pipe is provided with a sixth control valve, which is communicatively connected to the central controller.

[0018] According to one embodiment of the present invention, the number of liquid nitrogen uniformly dispersed circulating liquid methane subcoolers is at least two, the liquid methane storage tank includes a first liquid methane storage tank and a second liquid methane storage tank, and the rocket tank includes a first rocket tank and a second rocket tank; The liquid methane inlet connecting pipe and the liquid methane outlet connecting pipe of the liquid nitrogen uniformly dispersed circulating liquid methane subcooler are respectively connected to the first liquid methane storage tank and the first rocket storage tank; The liquid methane inlet connecting pipe and the liquid methane outlet connecting pipe of the other liquid nitrogen uniformly dispersed circulating liquid methane subcooler are respectively connected to the second liquid methane storage tank and the second rocket storage tank; The liquid nitrogen inlet connecting pipes of the two liquid nitrogen uniformly dispersed circulating liquid methane subcoolers are both connected to the liquid nitrogen storage tank.

[0019] Secondly, the present invention provides a method of using the subcooled liquid methane refueling system described in any one of the above contents.

[0020] According to an embodiment of the present invention, the method of use includes the following steps: S1. Liquid methane is continuously introduced into the liquid methane inlet connecting pipe through the liquid methane storage tank, while the third and fourth control valves are opened through the central controller and liquid nitrogen is continuously introduced into the liquid nitrogen inlet connecting pipe through the liquid nitrogen storage tank. S2. When the liquid nitrogen level is level with the pre-cooled liquid level mark, the fourth control valve is closed and the fifth control valve is opened simultaneously through the central controller. S3. When the liquid nitrogen level is level with the working liquid level mark, the first control valve, the cryogenic pump, and the second control valve are opened through the central controller. S4. When the subcooling of liquid methane is about to be completed, the third control valve is closed via the central controller; S5. When the liquid nitrogen storage is depleted, the first control valve, the cryogenic pump, the second control valve, and the fifth control valve are closed via the central controller.

[0021] Beneficial effects This invention has at least the following technical effects: Compared to existing supercoolers, this invention effectively avoids crystallization and ice blockage in liquid methane, without terminating the refueling process or affecting subsequent launch missions. Furthermore, because the "spray-type structural layout" in this invention is completely different from the "immersion-type structural layout" in existing technologies, it eliminates the need to wait for the liquid nitrogen level to completely drain to the bottom of the liquid methane tube before stopping the flow of liquid methane and implementing system withdrawal, thus avoiding increased time costs and significant waste of liquid methane. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of the liquid nitrogen uniformly dispersed circulating liquid methane subcooler in this invention; Figure 2 This is a schematic diagram of the overall structure of the spraying mechanism in this invention; Figure 3 for Figure 2 A bottom view; Figure 4 This is a schematic diagram of the overall structure of the present invention.

[0024] Explanation of reference numerals in the attached figures: 1. Subcooler shell; 2. Heat exchanger core; 3. Liquid methane inlet connecting pipe; 4. Liquid methane outlet connecting pipe; 5. Liquid nitrogen inlet connecting pipe; 6. Liquid nitrogen reflux connecting pipe; 7. Nitrogen outlet connecting pipe; 8. Liquid nitrogen discharge connecting pipe; 9. Return pipeline; 10. Cryogenic pump; 11. First control valve; 12. Second control valve; 13. Third control valve; 14. First tee pipe; 15. First branch pipeline; 16. Second branch pipeline; 17. Fourth control valve; 18. Fifth control valve; 19. Equalization pipe; 20. Bottom equalization orifice; 21. Side equalization orifice; 22. Liquid nitrogen storage tank; 23. First liquid methane storage tank; 24. Liquid nitrogen storage tank; 25. Second liquid methane storage tank; 26. First rocket tank; 27. Second rocket tank; 28. Second tee pipe; a. Precooled liquid level scale; b. Working liquid level scale. Detailed Implementation

[0025] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and to exemplify the principles of the present invention, and are not configured to limit the present invention. In addition, the structural components in the drawings are not necessarily drawn to scale. For example, the dimensions of some structural components or regions in the drawings may be enlarged for other structural components or regions to aid in the understanding of the embodiments of the present invention.

[0026] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of the embodiments of the present invention. In the description of the present invention, it should be noted that, unless otherwise stated, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0027] Furthermore, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a structure or component that includes a list of elements includes not only those elements but also other structural elements that are not expressly listed or inherent to the structure or component. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the article or apparatus that includes the element.

[0028] Spatial relation terms such as "below," "under," "under," "low," "above," "on," and "high" are used for descriptive convenience to explain the positioning of one element relative to a second element, indicating that these terms are intended to cover different orientations of the device, in addition to those different from those shown in the figure. Furthermore, phrases such as "one element on / below another element" can indicate that two elements are in direct contact, or that there are other elements between the two elements. In addition, terms such as "first" and "second" are also used to describe individual elements, areas, parts, etc., without specifically indicating order or sequence, and should not be considered restrictive. Similar terms are used throughout the description to represent similar elements.

[0029] It will be apparent to those skilled in the art that the present invention can be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention.

[0030] In the following embodiments, there may be descriptions such as "this subcooler". It should be understood that "this subcooler" refers to a liquid nitrogen uniformly dispersed circulating liquid methane subcooler as described in the following embodiments.

[0031] In the following embodiments, since both the first tee pipe 14 and the second tee pipe 28 are tee pipes, it should be understood that, for ease of description, the three ports of the first tee pipe 14 are respectively named the first port, the second port, and the third port of the first tee pipe 14, and the first port, the second port, or the third port of the first tee pipe 14 does not specifically refer to a port at a particular location in the first tee pipe 14. Similarly, the three ports of the second tee pipe 28 are respectively named the first port, the second port, and the third port of the second tee pipe 28, and the first port, the second port, or the third port of the second tee pipe 28 does not specifically refer to a port at a particular location in the second tee pipe 28.

[0032] Firstly, such as Figures 1-3 As shown, this embodiment provides a liquid nitrogen uniformly dispersed circulating liquid methane subcooler.

[0033] In this embodiment, the subcooler includes at least a subcooler housing 1 and a heat exchange core 2 disposed inside the subcooler housing 1. Wherein: The heat exchange core 2 is fixedly connected to and connected to a liquid methane inlet pipe 3 and a liquid methane outlet pipe 4. The top and bottom ends of the subcooler shell 1 are respectively fixedly connected to and connected to a nitrogen outlet pipe 7 and a liquid nitrogen return pipe 6.

[0034] A spray mechanism is installed inside the subcooler shell 1, and the spray mechanism is located directly above the heat exchange core 2. The end of the liquid nitrogen reflux connecting pipe 6 furthest from the subcooler shell 1 is fixedly connected to and connected to a reflux pipe 9. A cryogenic pump 10 and a second control valve 12 are installed on the reflux pipe 9. The end of the reflux pipe 9 (i.e., the end furthest from the liquid nitrogen reflux connecting pipe 6) is fixedly connected to and connected to the first port of a first three-way pipe 14. The second port of the first three-way pipe 14 is fixedly connected to and connected to a liquid nitrogen inlet connecting pipe 5, and a third control valve 13 is installed on the liquid nitrogen inlet connecting pipe 5. The third port of the first three-way pipe 14 is interconnected with the spray mechanism.

[0035] In this embodiment, with the above-mentioned configuration, the spraying mechanism can be used to spray liquid nitrogen introduced through the liquid nitrogen inlet connecting pipe 5 onto the inner wall of the subcooler shell 1; at the same time, the spraying mechanism can also be used to spray liquid nitrogen introduced through the liquid nitrogen inlet connecting pipe 5 and / or liquid nitrogen returning through the return pipe 9 onto the heat exchange core 2, so as to respectively realize the precooling of the subcooler shell 1 and realize the heat exchange between liquid nitrogen and liquid methane through the heat exchange core 2 (that is, to realize the subcooling treatment of liquid methane through the heat exchange between liquid nitrogen and liquid methane).

[0036] In this embodiment, a level gauge (not shown in the figure) is installed on the inner wall of the subcooler housing 1, and the height of the level gauge is lower than the height of the bottom of the heat exchange core 2. The level gauge is used to monitor the liquid nitrogen storage liquid 22 (liquid nitrogen storage liquid 22 is liquid nitrogen sprayed by the spray mechanism and temporarily stored inside the subcooler housing) inside the subcooler housing, so that the liquid nitrogen storage liquid 22 is always lower than the height of the bottom of the heat exchange core 2. The level gauge is prior art known in the art and will not be described in detail here.

[0037] In this embodiment, the subcooler further includes a central controller (not shown in the figure). The cryogenic pump 10, the second control valve 12, the third control valve 13, and the level gauge are all communicatively connected to the central controller, enabling the central controller to regulate the cryogenic pump 10, the second control valve 12, the third control valve 13, and the level gauge. The central controller is prior art known in the art and will not be described in detail here.

[0038] In one embodiment of the present invention, a liquid methane inlet connecting pipe 3 is fixedly connected to and communicates with the bottom end of the heat exchange core 2, and the end of the liquid methane inlet connecting pipe 3 away from the heat exchange core 2 is located on the bottom outer side of the subcooler housing 1. A liquid methane outlet connecting pipe 4 is fixedly connected to and communicates with the top end of the heat exchange core 2, and the end of the liquid methane outlet connecting pipe 4 away from the heat exchange core 2 is located on the top outer side of the subcooler housing 1.

[0039] In one embodiment of the present invention, such as Figure 1 As shown, the spraying mechanism includes at least bottom uniform distribution holes 20 and side uniform distribution holes 21. Wherein: The third port of the first tee pipe 14 (i.e. Figure 1 The first port of the second three-way pipe 28 is fixedly connected and connected to the port of the first three-way pipe 14 near the spray mechanism. The second port and the third port of the second three-way pipe 28 are respectively connected to the bottom uniform distribution hole 20 and the side uniform distribution hole 21. That is, the first three-way pipe 14 can be connected to the spray mechanism through the second three-way pipe 28. The bottom uniform distribution holes 20 are correspondingly arranged with the heat exchange core 2 to spray liquid nitrogen introduced into the liquid nitrogen inlet pipe 5 and / or liquid nitrogen returning from the return pipe 9 onto the heat exchange core 2, thereby enabling heat exchange between liquid nitrogen and liquid methane (i.e., subcooling of liquid methane) through heat exchange between liquid nitrogen and liquid methane in the heat exchange core 2; the side uniform distribution holes 21 are correspondingly arranged with the inner wall of the subcooler shell 1 to spray liquid nitrogen introduced into the liquid nitrogen inlet pipe 5 onto the inner wall of the subcooler shell 1, thereby enabling precooling of the subcooler shell 1 through contact between liquid nitrogen and the inner wall of the subcooler shell 1.

[0040] In one embodiment of the present invention, such as Figure 2 and Figure 3As shown, the spraying mechanism also includes a first branch pipe 15, a second branch pipe 16, and several parallel distribution pipes 19 arranged in parallel. like Figure 2 As shown, the two ends of the distribution pipe 19 are sealed structures.

[0041] like Figure 3 As shown, the side uniform distribution hole 21 is formed on the outermost uniform distribution tube 19, and the bottom uniform distribution hole 20 is formed on the remaining uniform distribution tubes 19 except for the outermost one.

[0042] like Figure 1 and Figure 2 As shown, one end of the first branch pipe 15 and one end of the second branch pipe 16 are fixedly connected and communicate with the third port and the second port of the second tee pipe 28, respectively. The other end of the first branch pipe 15 is fixedly connected and communicated with the equalization pipe 19 (i.e., the outermost equalization pipe 19 mentioned above) which has a side equalization hole 21, and the other end of the second branch pipe 16 is fixedly connected and communicated with the equalization pipe 19 (i.e., the other equalization pipes 19 except the outermost one) which has a bottom equalization hole 20.

[0043] like Figure 1 and Figure 2 As shown, the first branch pipeline 15 is equipped with a fourth control valve 17, and the second branch pipeline 16 is equipped with a fifth control valve 18. Both the fourth control valve 17 and the fifth control valve 18 are communicatively connected to the central controller so that the central controller can regulate the fourth control valve 17 and the fifth control valve 18.

[0044] Specifically, in this embodiment, such as Figure 3 As shown, the number of equalization tubes 19 can be six. Among them, the number of side equalization holes 21 is several and is evenly opened on the two outermost equalization tubes 19 in sequence, and the number of bottom equalization holes 20 is several and is evenly opened on the four middle equalization tubes 19 in sequence.

[0045] Preferably, the level gauge can be a differential pressure level gauge known in the art.

[0046] In one embodiment of the present invention, such as Figure 1 As shown, the inner wall of the subcooler housing 1 is provided with a precooling liquid level scale a and a working liquid level scale b, and the heights of both the precooling liquid level scale a and the working liquid level scale b are lower than the height of the bottom of the heat exchange core 2. Specifically, the working liquid level scale b is located between the precooling liquid level scale a and the bottom of the heat exchange core 2, meaning the height of the precooling liquid level scale a is lower than the height of the working liquid level scale b.

[0047] In this embodiment, the differential pressure level gauge can be used to monitor whether the liquid level of the liquid nitrogen reservoir 22 is at the same height as the pre-cooled liquid level mark a. Simultaneously, the differential pressure level gauge can also be used to monitor whether the liquid level of the liquid nitrogen reservoir 22 is at the same height as the working liquid level mark b.

[0048] Furthermore, in order to coordinate with the second control valve 12 to control the opening and closing of the return pipeline 9, in this embodiment, a first control valve 11 is also provided on the return pipeline 9, and the first control valve 11 is communicatively connected to the central controller so that the central controller can regulate the first control valve 11. Wherein, for example... Figure 1 As shown, the first control valve 11 can be located between the liquid nitrogen reflux connecting pipe 6 and the cryogenic pump 10, and the second control valve 12 can be located between the first tee pipe 14 and the cryogenic pump 10.

[0049] Furthermore, when the liquid nitrogen level in the liquid nitrogen reservoir 22 is too high, in order to allow the liquid nitrogen level in the liquid nitrogen reservoir 22 to drop more quickly and further prevent the liquid nitrogen level in the liquid nitrogen reservoir 22 from contacting the heat exchange core 2 (i.e., to further prevent the liquid nitrogen level in the liquid nitrogen reservoir 22 from being higher than the bottom of the heat exchange core 2), in this embodiment, the bottom end of the subcooler shell 1 is connected to a liquid nitrogen drain pipe 8. A sixth control valve (not shown in the figure) is installed on the liquid nitrogen drain pipe 8. The sixth control valve is communicatively connected to the central controller so that the central controller can regulate the sixth control valve. When the liquid nitrogen level in the liquid nitrogen reservoir 22 is too high, the central controller receives a signal transmitted from the differential pressure level gauge and opens the sixth control valve. At this time, the liquid nitrogen reservoir 22 can flow out quickly through the liquid nitrogen drain pipe 8, thereby allowing the liquid nitrogen level in the liquid nitrogen reservoir 22 to drop more rapidly.

[0050] It should be understood that the above-mentioned "liquid nitrogen storage liquid 22 liquid level is too high" can be interpreted as when the liquid level of liquid nitrogen storage liquid 22 is higher than the height of the working liquid level mark b.

[0051] Optionally, the heat exchange core 2 can be a plate-fin structure or a tube-and-shell structure, etc., without particular limitation. When the heat exchange core 2 is a plate-fin structure, the end of the heat exchange core 2 near the bottom distribution holes 20 is the nitrogen-side open side. When the heat exchange core 2 is a tube-and-shell structure, the liquid methane heat exchange tubes in the heat exchange core 2 are arranged in a cross-shaped configuration, so that the liquid nitrogen sprayed on the heat exchange core 2 can exchange heat between the wall surface of the heat exchange core 2 and the tube side of the liquid methane.

[0052] Preferably, in this embodiment, the heat exchange core 2 can be a tube-and-shell structure.

[0053] Secondly, this embodiment provides a method of using the liquid nitrogen uniformly dispersed circulating liquid methane subcooler as described in any one of the first aspects. In this embodiment, the method of using the liquid nitrogen uniformly dispersed circulating liquid methane subcooler includes, but is not limited to, the following steps: The first step, before commencing the formal liquid methane subcooling operation, is to simultaneously stabilize the liquid methane flow and precool the subcooler shell 1: Liquid methane is continuously introduced into the liquid methane inlet connecting pipe 3. The liquid methane flows through the heat exchange core 2 and out through the liquid methane outlet connecting pipe 4, thereby stabilizing the flow of liquid methane. At the same time, the third control valve 13 and the fourth control valve 17 are opened by the central controller (at this time, the first control valve 11, the second control valve 12 and the fifth control valve 18 are all closed), and liquid nitrogen is continuously introduced into the liquid nitrogen inlet connecting pipe 5. At this time, the liquid nitrogen is sprayed onto the inner wall of the subcooler shell 1 through the side distribution holes 21, thereby precooling the subcooler shell 1.

[0054] In the first step, the liquid nitrogen flowing out through the side distribution hole 21 will accumulate inside the subcooler shell 1 and form a liquid nitrogen reservoir 22. When the liquid level of the liquid nitrogen reservoir 22 gradually rises to be level with the precooling liquid level mark a, it can be determined that the stabilization of liquid methane flow and the precooling of the subcooler shell 1 are completed.

[0055] The second step, after completing the stabilization of the liquid methane flow and the pre-cooling of the subcooler shell 1, is to proceed with the formal liquid methane subcooling process: When the liquid nitrogen level in the storage tank 22 gradually rises to the same height as the pre-cooled liquid level mark a, the differential pressure level gauge will detect the signal and transmit it to the central controller. Upon receiving the signal, the central controller will close the fourth control valve 17 and simultaneously open the fifth control valve 18 (i.e., the central controller closes the fourth control valve 17 and simultaneously opens the fifth control valve 18). Simultaneously, the continuous flow of liquid methane into the liquid methane inlet pipe 3 and liquid nitrogen into the liquid nitrogen inlet pipe 5 must be maintained, while the first control valve 11 and the second control valve 12 must remain closed. At this time, liquid nitrogen will be sprayed onto the heat exchange core 2 through the bottom distribution holes 20, thereby achieving heat exchange between liquid nitrogen and liquid methane inside the heat exchange core 2 and realizing the continuous online preparation of subcooled liquid methane.

[0056] In the second step, when the liquid nitrogen reservoir 22 gradually rises to the same height as the working liquid level mark b, the differential pressure level gauge will detect the signal and transmit it to the central controller. After receiving the signal, the central controller will open the first control valve 11, the cryogenic pump 10, and the second control valve 12 (i.e., the central controller opens the first control valve 11, the cryogenic pump 10, and the second control valve 12). At this time, the liquid nitrogen reservoir 22 can be refluxed through the return pipeline 9, thereby keeping the liquid nitrogen reservoir 22 at the same height as the working liquid level mark b and maintaining the continuous online preparation of subcooled liquid methane.

[0057] In the second step, when the first control valve 11, the cryogenic pump 10, and the second control valve 12 are in the open state (that is, when the liquid nitrogen storage 22 is refluxed), the central controller will dynamically control the real-time opening degree of the third control valve 13 and the real-time opening degree of the second control valve 12, so that the liquid nitrogen entering the connecting pipe 5, the liquid nitrogen refluxed in the return pipe 9, and the vaporized liquid nitrogen in the supercooler shell 1 (the vaporized liquid nitrogen will flow out through the nitrogen flow out connecting pipe 7) are always in a dynamic balance, so as to keep the liquid level of the liquid nitrogen storage 22 always level with the height of the working liquid level scale b.

[0058] The third step involves closing the third control valve 13 in advance via the central controller when the liquid methane subcooling process is nearing completion. This stops the flow of liquid nitrogen, and the subcooled liquid methane is prepared solely through the reflux of liquid nitrogen. During this process, the liquid nitrogen reservoir 22 gradually vaporizes, causing its level to gradually decrease until it is completely consumed. At this point, the central controller closes the first control valve 11, the cryogenic pump 10, the second control valve 12, and the fifth control valve 18, simultaneously stopping the flow of liquid methane into the liquid methane inlet connecting pipe 3. This completes the subcooling of the liquid methane, thus fulfilling the refueling task.

[0059] It should be understood that, in the above-mentioned process, during the stabilization of liquid methane flow and the precooling of the subcooler shell 1, only the liquid nitrogen introduced through the liquid nitrogen inlet connecting pipe 5 sprays onto the inner wall of the subcooler shell 1. After the stabilization of liquid methane flow and the precooling of the subcooler shell 1 are completed, and the liquid level of the liquid nitrogen reservoir 22 is between the precooling liquid level mark a and the working liquid level mark b, only the liquid nitrogen introduced through the liquid nitrogen inlet connecting pipe 5 sprays onto the heat exchange core 2. When the liquid level of the liquid nitrogen reservoir 22 is level with the working liquid level mark b, the liquid nitrogen introduced through the liquid nitrogen inlet connecting pipe 5 and the liquid nitrogen returning through the return pipe 9 will both spray onto the heat exchange core 2. When the subcooling of the liquid methane is about to be completed, only the liquid nitrogen returning through the return pipe 9 sprays onto the heat exchange core 2.

[0060] Through the above configuration, the "spray-type structural layout" in this subcooler completely overturns the "immersion-type structural layout" in the prior art. Specifically, the liquid nitrogen in this subcooler can be sprayed onto the heat exchange core 2 to facilitate heat exchange between liquid nitrogen and liquid methane. Simultaneously, the liquid nitrogen level in the storage tank 22 remains consistently below the bottom of the heat exchange core 2. Therefore, compared to existing subcoolers (which immerse the tube side flowing with liquid methane in the shell side containing liquid nitrogen), this subcooler avoids the crystallization and ice blockage of liquid methane caused by immersion, and eliminates the need to wait for the liquid nitrogen level to completely drain to the bottom of the liquid methane tube side before stopping the flow of liquid methane and implementing system withdrawal.

[0061] Furthermore, the "spray-type structural layout" in this subcooler is completely different from the existing "liquid nitrogen pre-cooling from the bottom of the shell side" method. The existing method cannot achieve rapid and uniform pre-cooling of the subcooler shell side, while this subcooler can achieve rapid and uniform pre-cooling of the subcooler shell 1 by spraying from top to bottom through the side uniform distribution holes 21.

[0062] In summary, compared to existing supercoolers, this supercooler effectively prevents liquid methane from crystallizing and causing ice blockage, thus avoiding interruption of the refueling process and impacting subsequent launch missions. Furthermore, because the "spray-type structural layout" in this supercooler is completely different from the "immersion-type structural layout" in existing technologies, it eliminates the need to wait for the liquid nitrogen level to completely drain to the bottom of the liquid methane tube before stopping the flow of liquid methane and implementing system withdrawal, thereby reducing time costs and preventing significant waste of liquid methane.

[0063] Thirdly, such as Figure 4 As shown, this embodiment provides a subcooled liquid methane refueling system, which includes a liquid nitrogen uniformly dispersed circulating liquid methane subcooler as described in any one of the first aspects.

[0064] In one embodiment of the present invention, the refueling system includes at least a first liquid methane storage tank 23, a liquid nitrogen storage tank 24, and a second liquid methane storage tank 25. Simultaneously, in this refueling system, the subcooler (i.e., Figure 4 The number of subcooler housings 1) can be two (for ease of description, we will refer to them as...). Figure 4 The upper middle subcooler casing 1 is named the first subcooler. Figure 4 The lower part of the subcooler housing 1 is named the second subcooler. Wherein: The first liquid methane storage tank 23 and the second liquid methane storage tank 25 can both be used to store liquid methane, and the liquid nitrogen storage tank 24 can be used to store liquid nitrogen.

[0065] In this embodiment, as Figure 4As shown, the first liquid methane storage tank 23 can be fixedly connected and communicated with the liquid methane inlet connecting pipe 3 in the first subcooler, so as to continuously supply liquid methane into the liquid methane inlet connecting pipe 3 in the first subcooler. The liquid methane outlet connecting pipe 4 in the first subcooler can be fixedly connected and communicated with the first rocket tank 26. The second liquid methane storage tank 25 can be fixedly connected and communicated with the liquid methane inlet connecting pipe 3 in the second subcooler, so as to continuously supply liquid methane into the liquid methane inlet connecting pipe 3 in the second subcooler. The liquid methane outlet connecting pipe 4 in the second subcooler can be fixedly connected and communicated with the second rocket tank 27. The liquid nitrogen storage tank 24 can be fixedly connected and communicated with both the liquid nitrogen inlet connecting pipes 5 in the first subcooler and the liquid nitrogen inlet connecting pipe 5 in the second subcooler, so as to continuously supply liquid nitrogen into both the liquid nitrogen inlet connecting pipes 5 in the first subcooler and the liquid nitrogen inlet connecting pipe 5 in the second subcooler.

[0066] In this embodiment, the first rocket propellant tank 26 and the second rocket propellant tank 27 can be the first-stage rocket propellant tank and the second-stage rocket propellant tank, respectively.

[0067] Furthermore, both the nitrogen outlet pipe 7 in the first subcooler and the nitrogen outlet pipe 7 in the second subcooler can be connected to a nitrogen emission tower, which can effectively discharge the large amount of nitrogen generated during the heat exchange process, thereby avoiding the accumulation of nitrogen and abnormal pressure rise, and thus ensuring the stable operation of the filling system.

[0068] With the above configuration, the refueling system in this embodiment can form a "dual-path parallel" refueling system, that is, it can simultaneously provide supercooled liquid methane to the rocket's first-stage and second-stage propellant tanks, thereby ensuring efficient synchronization of the refueling process.

[0069] It should be understood that the charging system incorporating this subcooler includes, but is not limited to, the charging system disclosed in the third aspect above. In other words, any charging system using this subcooler should be included within the scope of protection of this invention.

[0070] It should be understood that the above-described embodiments or examples of the present invention can be combined with each other and have corresponding technical effects.

[0071] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A subcooled liquid methane refueling system, characterized in that: Includes a liquid methane storage tank, a liquid nitrogen storage tank (24), and a liquid nitrogen uniformly dispersed circulating liquid methane subcooler, wherein: The liquid nitrogen uniformly dispersed circulating liquid methane subcooler includes a subcooler shell (1) and a heat exchange core (2) disposed in the subcooler shell (1). The heat exchange core (2) is connected to a liquid methane inlet connecting pipe (3) and a liquid methane outlet connecting pipe (4). The top and bottom of the subcooler shell (1) are respectively connected to a nitrogen outlet connecting pipe (7) and a liquid nitrogen return connecting pipe (6). A spraying mechanism is provided inside the subcooler shell (1), and the spraying mechanism is located above the heat exchange core (2); the end of the liquid nitrogen reflux connecting pipe (6) away from the subcooler shell (1) is connected to a reflux pipe (9), the reflux pipe (9) is provided with a cryogenic pump (10) and a second control valve (12), the end of the reflux pipe (9) is connected to the first port of a first three-way pipe (14), the second port of the first three-way pipe (14) is connected to a liquid nitrogen inlet connecting pipe (5), the liquid nitrogen inlet connecting pipe (5) is provided with a third control valve (13), and the third port of the first three-way pipe (14) is connected to the spraying mechanism; the spraying mechanism is used to spray liquid nitrogen onto the inner wall of the subcooler shell (1) and the heat exchange core (2) to achieve precooling of the subcooler shell (1) and heat exchange between liquid nitrogen and liquid methane; The liquid methane storage tank is connected to the liquid methane inlet connecting pipe (3), the liquid nitrogen storage tank (24) is connected to the liquid nitrogen inlet connecting pipe (5), and the liquid methane outlet connecting pipe (4) is used to connect to the rocket storage tank. A level gauge is provided on the inner wall of the subcooler housing (1). The level gauge is used to monitor the liquid level of the liquid nitrogen storage liquid (22) in the subcooler housing so that the liquid level of the liquid nitrogen storage liquid (22) is always lower than that of the heat exchange core (2). The subcooler also includes a central controller, and the cryogenic pump (10), the second control valve (12), the third control valve (13) and the level gauge are all communicatively connected to the central controller.

2. The subcooled liquid methane refueling system according to claim 1, characterized in that: The liquid methane inlet connecting pipe (3) is connected to the bottom end of the heat exchange core (2), and the end of the liquid methane inlet connecting pipe (3) away from the heat exchange core (2) is located on the bottom outer side of the subcooler shell (1). The liquid methane outflow connecting pipe (4) is connected to the top of the heat exchange core (2), and the end of the liquid methane outflow connecting pipe (4) away from the heat exchange core (2) is located on the top outer side of the subcooler housing (1).

3. The subcooled liquid methane refueling system according to claim 1, characterized in that: The spraying mechanism includes at least a bottom uniform distribution hole (20) and a side uniform distribution hole (21); The third port of the first three-way pipe (14) is connected to the first port of the second three-way pipe (28), and the second port and the third port of the second three-way pipe (28) are respectively connected to the bottom equalization hole (20) and the side equalization hole (21); The bottom uniform distribution hole (20) is configured correspondingly to the heat exchange core (2) to spray the liquid nitrogen introduced into the liquid nitrogen inlet connecting pipe (5) and / or the liquid nitrogen returning from the return pipe (9) onto the heat exchange core (2). The side uniform distribution hole (21) is configured correspondingly to the inner wall of the subcooler shell (1) to spray the liquid nitrogen introduced into the liquid nitrogen inlet connecting pipe (5) onto the inner wall of the subcooler shell (1).

4. The subcooled liquid methane refueling system according to claim 3, characterized in that: The spraying mechanism also includes a first branch pipe (15), a second branch pipe (16), and several parallel distributed pipes (19). The two ends of the uniform distribution tube (19) are sealed structures. The side uniform distribution hole (21) is opened in the outermost uniform distribution tube (19), and the bottom uniform distribution hole (20) is opened in the remaining uniform distribution tubes (19) except for the outermost layer. One end of the first branch pipe (15) and one end of the second branch pipe (16) are respectively connected to the third port and the second port of the second tee pipe (28), the other end of the first branch pipe (15) is connected to the equalization pipe (19) with the side equalization hole (21), and the other end of the second branch pipe (16) is connected to the equalization pipe (19) with the bottom equalization hole (20). The first branch pipeline (15) is equipped with a fourth control valve (17), and the second branch pipeline (16) is equipped with a fifth control valve (18). Both the fourth control valve (17) and the fifth control valve (18) are communicatively connected to the central controller.

5. The subcooled liquid methane refueling system according to claim 1, characterized in that: The level gauge is a differential pressure level gauge; The inner wall of the subcooler housing (1) is provided with a precooling liquid level scale (a) and a working liquid level scale (b). Both the precooling liquid level scale (a) and the working liquid level scale (b) are lower than the heat exchange core (2), and the working liquid level scale (b) is located between the precooling liquid level scale (a) and the heat exchange core (2). The differential pressure level gauge is used to monitor whether the liquid level of the liquid nitrogen storage liquid (22) is at the same height as the pre-cooled liquid level scale (a) and to monitor whether the liquid level of the liquid nitrogen storage liquid (22) is at the same height as the working liquid level scale (b).

6. The subcooled liquid methane refueling system according to claim 1, characterized in that: The return pipeline (9) is equipped with a first control valve (11), which is communicatively connected to the central controller; The first control valve (11) is located between the liquid nitrogen reflux connecting pipe (6) and the cryogenic pump (10), and the second control valve (12) is located between the first three-way pipe (14) and the cryogenic pump (10).

7. The subcooled liquid methane refueling system according to claim 1, characterized in that: The bottom end of the subcooler housing (1) is connected to a liquid nitrogen discharge pipe (8), and the liquid nitrogen discharge pipe (8) is equipped with a sixth control valve, which is communicatively connected to the central controller.

8. The subcooled liquid methane refueling system according to claim 1, characterized in that: The number of liquid nitrogen uniformly dispersed circulating liquid methane subcoolers is at least two, the liquid methane storage tank includes a first liquid methane storage tank (23) and a second liquid methane storage tank (25), and the rocket tank includes a first rocket tank (26) and a second rocket tank (27). The liquid methane inlet connecting pipe (3) and the liquid methane outlet connecting pipe (4) of the liquid nitrogen uniformly dispersed circulating liquid methane subcooler are respectively connected to the first liquid methane storage tank (23) and the first rocket storage tank (26); The liquid methane inlet connecting pipe (3) and the liquid methane outlet connecting pipe (4) of the other liquid nitrogen uniformly dispersed circulating liquid methane subcooler are respectively connected to the second liquid methane storage tank (25) and the second rocket storage tank (27); The liquid nitrogen inlet connecting pipes (5) of the two liquid nitrogen uniformly dispersed circulating liquid methane subcoolers are both connected to the liquid nitrogen storage tank (24).

9. A method of using the subcooled liquid methane refueling system according to any one of claims 1-8.

10. The method of using the subcooled liquid methane refueling system according to claim 9, characterized in that: The method of use includes the following steps: S1. Liquid methane is continuously introduced into the liquid methane inlet connecting pipe (3) through the liquid methane storage tank. At the same time, the third control valve (13) and the fourth control valve (17) are opened through the central controller, and liquid nitrogen is continuously introduced into the liquid nitrogen inlet connecting pipe (5) through the liquid nitrogen storage tank (24). S2. When the liquid level of the liquid nitrogen storage liquid (22) is level with the pre-cooled liquid level scale (a), the fourth control valve (17) is closed and the fifth control valve (18) is opened at the same time through the central controller. S3. When the liquid level of the liquid nitrogen storage liquid (22) is flush with the working liquid level scale (b), the first control valve (11), the cryogenic pump (10), and the second control valve (12) are opened through the central controller. S4. When the subcooling of liquid methane is about to be completed, close the third control valve (13) through the central controller. S5. When the liquid nitrogen storage liquid (22) is consumed, the first control valve (11), the cryogenic pump (10), the second control valve (12) and the fifth control valve (18) are closed through the central controller.

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