CN115745713A - High-density hydrogen-oxygen propellant synchronous preparation system and method thereof - Google Patents

Abstract

The invention discloses a high-density hydrogen-oxygen propellant synchronous preparation system and a method thereof, belonging to the field of low-temperature equipment. The preparation process of the high-density oxyhydrogen propellant is coupled in the open helium liquefaction circulation flow, so that the high-efficiency integrated preparation of the high-density oxyhydrogen propellant combination can be realized, the preparation scale is far larger than that of the traditional methods such as a low-temperature refrigerator, evacuation and pressure reduction and the like, and the requirements of an aerospace launching field on a preparation and filling system of a densified low-temperature propellant are met. The temperature zones of the heat regenerators in the system are reasonable, a gradient temperature field with uniform temperature difference is formed, and the thermodynamic efficiency of the synchronous preparation system of the high-density hydrogen-oxygen propellant is effectively improved. The invention utilizes the liquid nitrogen medium with low price and high safety to pre-cool and compress the high-temperature helium working medium in two stages, and can effectively reduce the power of parts such as a helium compressor, a helium expander and the like.

Description

Synchronous preparation system and method for high-density oxyhydrogen propellant

Technical Field

The invention relates to the field of densification of low-temperature propellants, in particular to a system and a method for synchronously preparing a high-density oxyhydrogen propellant.

Background

Liquid hydrogen and liquid oxygen are a group of liquid rocket propellants with the highest specific impulse at present, can reach 450s, and can obviously improve the capability of a rocket for transporting effective loads when being applied to the upper level. Due to the superior properties of the liquid hydrogen/liquid oxygen low-temperature propellant, the liquid hydrogen/liquid oxygen low-temperature propellant is determined as the preferred propellant in projects such as manned lunar landing, manned deep space exploration and the like by NASA. It is also clear from the white paper of space shuttle in 2006 that is published in China that a new generation of carrier rocket adopting liquid hydrogen/liquid oxygen and liquid oxygen/kerosene low-temperature propellant will become the main development direction of space vehicles in China.

At present, liquid hydrogen liquid oxygen propellants are all in a thermodynamic saturated state when in use, and have the prominent defects of low density and unit volume refrigeration capacity and obvious insufficient thermophysical performance, thereby becoming the bottleneck of aerospace technology development. Therefore, the low-temperature propellant densification technology of liquid oxygen deep supercooling and liquid hydrogen slurrying and solid stating becomes the first choice for solving the problems, the density and the heat capacity of the liquid hydrogen and liquid oxygen propellant can be obviously improved, and the size and the structural weight of the rocket body can be reduced.

However, the existing low-temperature propellant densification device is usually only used for a single liquid oxygen propellant or liquid hydrogen propellant, and if synchronous supercooling of the liquid hydrogen and liquid oxygen combination is realized, the system is complex, large in size and low in operation efficiency. Meanwhile, for the deep supercooling of the liquid oxygen propellant, the conventional technology is difficult to supercool the liquid oxygen propellant to the temperature below 63.2K of the liquid nitrogen three-phase point, and if the liquid oxygen propellant is pumped out and decompressed, the liquid oxygen propellant is limited by the pressure of 148Pa of the liquid oxygen three-phase point, so that the overall efficiency is low, and the large-scale preparation cannot be carried out. For large-scale slurry and solid preparation of the liquid hydrogen propellant, precious liquid helium is often consumed, so that the overall economy of the system is poor when the high-density liquid hydrogen propellant is continuously produced and prepared.

Disclosure of Invention

The invention aims to provide a high-density oxyhydrogen propellant synchronous preparation system, designs a novel open helium liquefaction circulation flow, couples the preparation process of a high-density oxyhydrogen propellant in a circulation system, and realizes the high-efficiency synchronous preparation target of the high-density oxyhydrogen propellant and the high-density oxyhydrogen propellant.

The invention adopts the following technical scheme to realize the purpose of the invention:

in a first aspect, the invention provides a high-density hydrogen-oxygen propellant synchronous preparation system, which comprises a nitrogen precooler, a liquid nitrogen precooler, a first heat regenerator, a second heat regenerator, a third heat regenerator, a fourth heat regenerator, a fifth heat regenerator, a helium circulating pipeline, a first helium working medium expansion branch, a second helium working medium expansion branch, a liquid nitrogen pipeline, a liquid oxygen pipeline, a liquid hydrogen pipeline and a liquid helium pipeline;

the nitrogen precooler, the liquid nitrogen precooler, the second heat regenerator and the fourth heat regenerator are respectively provided with a first passage, a second passage and a third passage, wherein the first passages in the nitrogen precooler and the liquid nitrogen precooler respectively form heat exchange contact with the second passage and the third passage, and the second passages in the second heat regenerator and the fourth heat regenerator respectively form heat exchange contact with the first passage and the third passage; a first passage and a second passage which form heat exchange contact are arranged in the first heat regenerator, the third heat regenerator and the fifth heat regenerator;

the helium circulating pipeline is filled with a helium working medium, the helium circulating pipeline is sequentially connected with a helium compressor, a first passage of a nitrogen precooler, a first passage of a liquid nitrogen precooler, a first passage of a first heat regenerator, a first passage of a second heat regenerator, a first passage of a third heat regenerator, a first passage of a fourth heat regenerator, a first passage of a fifth heat regenerator, a throttle valve, a liquid helium storage tank, a second passage of the fifth heat regenerator, a second passage of the fourth heat regenerator, a second passage of the third heat regenerator, a second passage of the second heat regenerator, a second passage of the first heat regenerator, a second passage of the liquid nitrogen precooler and a second passage of the nitrogen precooler and then circulates to the helium compressor, and the helium working medium in the helium circulating pipeline continuously circulates from a gas state to a liquid state and then to a gas state in the pipeline;

the inlet end of the first helium working medium expansion branch is connected with the outlet end of the first passage of the first heat regenerator, the outlet end of the first helium working medium expansion branch is connected with the inlet end of the second passage of the second heat regenerator, a first helium expander is mounted on the first helium working medium expansion branch, part of high-pressure helium working medium flowing out of the first heat regenerator enters the first helium expander for isentropic expansion and generates cold energy, and then the cold energy is converged with helium working medium flowing out of the second passage of the third heat regenerator and enters the second passage of the second heat regenerator;

the inlet end of the second helium working medium expansion branch is connected with the outlet end of the first passage of the third heat regenerator, the outlet end of the second helium working medium expansion branch is connected with the inlet end of the second passage of the fourth heat regenerator, a second helium expander is installed on the second helium working medium expansion branch, part of high-pressure helium working medium flowing out of the third heat regenerator enters the second expander for isentropic expansion and generates cold energy, and then the cold energy is converged with helium working medium flowing out of the second passage of the fifth heat regenerator and enters the second passage of the fourth heat regenerator;

the inlet end of the liquid nitrogen pipeline is connected with a liquid nitrogen supply source, and the outlet end of the liquid nitrogen pipeline is emptied after the liquid nitrogen pipeline sequentially passes through a third passage of a liquid nitrogen precooler and a third passage of a nitrogen precooler;

the inlet end of the liquid oxygen pipeline is connected with a liquid oxygen supply source, the liquid oxygen pipeline is connected with a liquid oxygen pump, a liquid nitrogen bath heat exchanger and a third passage of a second heat regenerator in sequence and then is connected into a densification liquid oxygen storage tank, and liquid oxygen propellant conveyed by the liquid oxygen supply source is subjected to two-stage supercooling by the liquid nitrogen bath heat exchanger and the second heat regenerator and then is stored in the densification liquid oxygen storage tank;

the inlet end of the liquid hydrogen pipeline is connected with a liquid hydrogen supply source, the liquid hydrogen pipeline is connected with a liquid hydrogen pump and a third passage of a fourth heat regenerator in sequence and then is connected into a densification liquid hydrogen preparation and storage container, and a liquid hydrogen propellant conveyed by the liquid hydrogen supply source is supercooled by the fourth heat regenerator and then enters the densification liquid hydrogen preparation and storage container to exchange heat with liquid helium in a direct contact mode to form slurry hydrogen or solid hydrogen and directly store the slurry hydrogen or the solid hydrogen.

The liquid helium pipeline is connected with a liquid helium outlet at the bottom of the liquid helium storage tank, a densification liquid hydrogen preparation and storage container and a helium purifier in sequence and then is connected into a helium circulating pipeline in the fifth heat regenerator before the inlet end of the second channel; liquid helium stored in the liquid helium storage tank is input into the densification liquid hydrogen preparation and storage container through a liquid helium pipeline, directly contacts with supercooled liquid hydrogen input by the liquid hydrogen pipeline for heat exchange to form slurry hydrogen or solid hydrogen, the slurry hydrogen or the solid hydrogen is stored in the densification liquid hydrogen preparation and storage container, and the liquid helium is converted from a liquid state to a gas state and then enters a helium circulation pipeline for circulation.

Preferably, in the first aspect, the outlets of the first helium expander and the second helium expander are provided with a thermometer and a pressure gauge.

Preferably, the heat exchanger, the pipeline and the helium expander in the preparation system are all insulated from the environment for heat treatment.

Preferably, the liquid nitrogen bath heat exchanger is an open liquid nitrogen bath heat exchanger, the liquid oxygen pipeline is communicated with a heat exchange pipeline immersed in the liquid nitrogen bath in the heat exchanger, the liquid nitrogen cools the liquid oxygen in the liquid oxygen pipeline to generate nitrogen and directly evacuate the nitrogen, and the open liquid nitrogen bath heat exchanger is connected with a liquid nitrogen source for supplementing consumed liquid nitrogen.

Preferably, in the first aspect, the nitrogen precooler, the first reheater, the third reheater and the fifth reheater use gas-type heat exchangers.

Preferably, in the first aspect, the liquid nitrogen precooler, the second reheater and the fourth reheater use gas-liquid heat exchangers.

Preferably, in the first aspect, the paths for heat exchange in the nitrogen precooler, the liquid nitrogen precooler, the first regenerator, the second regenerator, the third regenerator, the fourth regenerator and the fifth regenerator are all arranged in a counter-flow manner.

As a preferable mode of the first aspect, the helium purifier employs an adsorption separation device, a membrane separation device, or a combustion condensation device capable of separating and purifying pure helium from a helium-hydrogen mixture gas.

Preferably, the helium gas compressor has a plurality of compressors arranged in series on the helium circulation line.

In a second aspect, the present invention provides a method for synchronously preparing high-density oxyhydrogen propellant by using the preparation system according to any one of the first aspects, comprising:

s1, inputting a liquid nitrogen medium into a liquid nitrogen pipeline through a self-pressurization method, sequentially flowing through a third passage of a liquid nitrogen precooler and a third passage of a nitrogen precooler to continuously release cold energy, and then emptying;

s2, keeping the liquid nitrogen medium continuously input into a liquid nitrogen pipeline, starting a helium compressor, a first helium expander and a second helium expander, compressing a helium working medium in a helium circulating pipeline by the helium compressor, then heating and boosting, and sequentially flowing through a first passage of a nitrogen precooler, a first passage of a liquid nitrogen precooler and a first passage of a first reheater to carry out three-stage cooling;

s3, helium working medium output by a first passage of the first heat regenerator is divided into a main flow part and a branch flow part, the branch helium working medium enters a first helium expander through a first helium working medium expansion branch to perform isentropic expansion, temperature reduction and depressurization, the outlet temperature is reduced to be lower than the liquid oxygen triple point temperature and then enters a helium circulation pipeline again, the branch helium working medium is mixed with returned helium working medium from a third heat regenerator and then enters a second passage of a second heat regenerator to release cold energy, and the main helium working medium sequentially flows through the first passage of the second heat regenerator and the first passage of the third heat regenerator to continuously absorb the cold energy for temperature reduction;

s4, helium working medium output by the first passage of the third heat regenerator is continuously divided into a main flow part and a branch flow part, the branch helium working medium enters the second helium expander through the second helium working medium expansion branch to perform isentropic expansion, temperature reduction and pressure reduction, the outlet temperature is reduced to be lower than the liquid hydrogen triple point temperature and then enters the helium circulation pipeline again, the branch helium working medium is mixed with the return helium working medium from the fifth heat regenerator and then enters the second passage of the fourth heat regenerator to release cold energy, and the main flow helium working medium sequentially flows through the first passage of the fourth heat regenerator and the first passage of the fifth heat regenerator to continuously absorb the cold energy for temperature reduction;

s5, helium working medium output by a first passage of a fifth heat regenerator is throttled by a throttle valve and then is converted from a gas state into a gas-liquid two-phase state, liquid helium is directly stored in a liquid helium storage tank and used for preparing slurry hydrogen or solid hydrogen, low-temperature gaseous helium working medium is mixed with gaseous helium working medium returned by a liquid helium pipeline and then sequentially flows through a second passage of the fifth heat regenerator, a second passage of a fourth heat regenerator, a second passage of a third heat regenerator, a second passage of the second heat regenerator, a second passage of a first heat regenerator, a second passage of a liquid nitrogen precooler and a second passage of a nitrogen precooler to continuously release cold energy, finally the helium working medium in a helium circulating pipeline enters a helium compressor again to be compressed, and the reciprocating circulation provides cold energy for deep supercooling of each low-temperature propellant;

s6, starting a liquid oxygen pump, continuously introducing liquid nitrogen into the liquid nitrogen bath heat exchanger, firstly inputting a liquid oxygen propellant into the liquid nitrogen bath heat exchanger through a liquid oxygen pipeline, absorbing the cold energy of the liquid nitrogen to finish primary supercooling, and directly exhausting the vaporized liquid nitrogen medium in the liquid nitrogen bath heat exchanger; then the liquid oxygen propellant enters a third passage of the second heat regenerator, and simultaneously absorbs the cold energy of the returned helium working medium output by the third heat regenerator and the helium working medium output by the first helium expander after primary expansion to complete secondary supercooling;

s7, starting a liquid hydrogen pump, inputting a liquid hydrogen propellant into a third passage of a fourth heat regenerator through a liquid hydrogen pipeline, and absorbing the cold energy of the returned helium working medium output by a fifth heat regenerator and the two-stage expanded helium working medium output by a second helium expander for supercooling to form triple-point liquid hydrogen and then entering a densification liquid hydrogen preparation and storage container; liquid helium in a liquid helium storage tank is input into a densification liquid hydrogen preparation and storage container through a liquid helium pipeline in a pressurization mode, the liquid hydrogen in a triple point state is directly subjected to heat exchange in a spraying mode, the liquid hydrogen in the triple point state is converted into a slurry hydrogen or solid hydrogen state, the liquid helium is discharged from the top of the container after being subjected to heat exchange and vaporization and enters a helium purifier through the liquid helium pipeline for purification, and purified pure helium is merged into a helium circulating pipeline and mixed with helium working medium from the liquid helium storage tank for recycling.

Compared with the prior art, the invention has the outstanding and beneficial technical effects that: the high-density hydrogen-oxygen propellant combination can be efficiently and integrally prepared, the preparation scale is far larger than that of the traditional methods such as a low-temperature refrigerator, evacuation and decompression, and the like, and the requirements of an aerospace launching site on a densification low-temperature propellant preparation and filling system are met. The low-temperature propellant has remarkable densification effect, the supercooling temperature can approach to the triple point temperature of 54.4K for the liquid oxygen propellant, and high-quality slurry hydrogen and solid hydrogen can be prepared by the liquid helium medium for the liquid hydrogen propellant. The temperature zones of the heat regenerators are reasonable, a gradient temperature field with uniform temperature difference is formed, and the thermodynamic efficiency of the synchronous preparation system of the high-density oxyhydrogen propellant is effectively improved. The power of components such as a helium compressor, a helium expander and the like can be effectively reduced by using a liquid nitrogen medium two-stage precooled compressed high-temperature helium working medium with low price and high safety.

The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings so as to fully understand the objects, the features and the effects of the present invention.

Drawings

FIG. 1 is a schematic diagram of a system for synchronously preparing high-density hydrogen-oxygen propellant according to the present invention.

In the figure: the system comprises a helium compressor 1, a nitrogen precooler 2, a liquid nitrogen precooler 3, a first reheater 4, a second reheater 5, a third reheater 6, a fourth reheater 7, a fifth reheater 8, a throttle valve 9, a liquid helium storage tank 10, a first helium expander 11, a second helium expander 12, a liquid oxygen pump 13, a liquid nitrogen bath heat exchanger 14, a densified liquid oxygen storage tank 15, a liquid hydrogen pump 16, a densified liquid hydrogen preparation and storage container 17, a helium purifier 18, a helium circulating pipeline 19, a first helium working medium expansion branch 20, a second helium working medium expansion branch 21, a liquid nitrogen pipeline 22, a liquid oxygen pipeline 23, a liquid hydrogen pipeline 24 and a liquid helium pipeline 25.

Detailed Description

The invention is further described in the following with specific embodiments in conjunction with the accompanying drawings.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, as those skilled in the art will recognize without departing from the spirit and scope of the present invention. The technical characteristics in the embodiments of the present invention can be combined correspondingly without mutual conflict.

In the description of the present invention, it should be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or be indirectly connected to the other element, i.e., intervening elements may be present. In contrast, when an element is referred to as being "directly connected" to another element, there are no intervening elements present.

In the description of the present invention, it is to be understood that the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.

Referring to fig. 1, in a preferred embodiment of the present invention, there is provided a system for the simultaneous preparation of high density hydrogen-oxygen propellant, the components comprising the system comprising: the system comprises a helium compressor 1, a nitrogen precooler 2, a liquid nitrogen precooler 3, a first reheater 4, a second reheater 5, a third reheater 6, a fourth reheater 7, a fifth reheater 8, a throttle valve 9, a liquid helium storage tank 10, a first helium expander 11, a second helium expander 12, a liquid oxygen pump 13, a liquid nitrogen bath heat exchanger 14, a densified liquid oxygen storage tank 15, a liquid hydrogen pump 16, a densified liquid hydrogen preparation and storage container 17, a helium gas purifier 18, a helium circulation pipeline 19, a first helium working medium expansion branch 20, a second helium working medium expansion branch 21, a liquid nitrogen pipeline 22, a liquid oxygen pipeline 23, a liquid hydrogen pipeline 24 and a liquid helium pipeline 25. The design of the synchronous preparation system aims to meet the densification and filling requirements of an aerospace launching site on different low-temperature propellants, the preparation process of the high-density oxyhydrogen propellant can be coupled in a circulating system on the basis of an open helium liquefaction circulating flow through the system, and the efficient synchronous preparation of two low-temperature propellants, namely densified liquid hydrogen and densified liquid oxygen is realized.

The specific connection form and working principle of each component in the high-density hydrogen-oxygen propellant synchronous preparation system are described in detail below.

In the synchronous preparation system, all components are connected and matched through a helium circulating pipeline 19, a first helium working medium expansion branch 20, a second helium working medium expansion branch 21, a liquid nitrogen pipeline 22, a liquid oxygen pipeline 23, a liquid hydrogen pipeline 24 and a liquid helium pipeline 25, wherein the helium circulating pipeline 19 is mainly used for circulating helium working media, the first helium working medium expansion branch 20 and the second helium working medium expansion branch 21 are arranged on the helium circulating pipeline 19 and are connected with a two-stage helium expander through branch pipelines to provide cold energy meeting the requirements of supercooling of liquid oxygen and supercooling of liquid hydrogen, after initial helium working media are compressed, precooling is carried out through liquid nitrogen and returning helium working media, heat exchange is carried out through a plurality of regenerators and coolers step by step for temperature reduction, and throttling is carried out to form gas-liquid mixed state densification, liquid helium is used for further supercooling of liquid hydrogen through the liquid helium pipeline 25, and helium gradually flows back along the helium circulating pipeline 19 to release the cold energy, so as to provide the cold energy for the helium working media, the liquid oxygen and the cold energy of the liquid hydrogen. And the liquid nitrogen pipeline 22 is used for providing liquid nitrogen working medium for precooling the helium working medium. The liquid oxygen pipeline 23 and the liquid hydrogen pipeline 24 are respectively used for realizing the densification and storage of the liquid oxygen and the liquid hydrogen. The heat exchange of the various working media and the propellant is realized by depending on heat exchangers such as a nitrogen precooler 2, a liquid nitrogen precooler 3, a first heat regenerator 4, a second heat regenerator 5, a third heat regenerator 6, a fourth heat regenerator 7, a fifth heat regenerator 8 and the like. In order to meet the heat exchange requirement, different heat exchange passages are required to be arranged in each heat exchanger to exchange heat for different working media, and the heat exchange device is specifically as follows:

the nitrogen precooler 2 is provided with a first passage, a second passage and a third passage, wherein the first passage forms heat exchange contact with the second passage and the third passage respectively, the first passage is used as a hot working medium side, and the second passage and the third passage are both used as a cold working medium side.

The liquid nitrogen precooler 3 is provided with a first passage, a second passage and a third passage, wherein the first passage forms heat exchange contact with the second passage and the third passage respectively, the first passage is used as a hot working medium side, and the second passage and the third passage are both used as a cold working medium side.

The second heat regenerator 5 is provided with a first passage, a second passage and a third passage, wherein the second passage is respectively in heat exchange contact with the first passage and the third passage, the first passage and the third passage are used as hot working medium sides, and the second passage is used as cold working medium sides.

The fourth regenerator 7 is provided with a first path, a second path and a third path, wherein the second path is in heat exchange contact with the first path and the third path respectively, the first path and the third path are used as hot working medium sides, and the second path is used as cold working medium sides.

The first heat regenerator 4 is provided with a first passage and a second passage which form heat exchange contact, the first passage is used as a hot working medium side, and the second passage is used as a cold working medium side.

The third regenerator 6 is provided with a first passage and a second passage which form heat exchange contact, the first passage is used as a hot working medium side, and the second passage is used as a cold working medium side.

The fifth regenerator 8 is provided therein with a first path and a second path which constitute heat exchange contact, the first path being a hot working medium side, and the second path being a cold working medium side.

In the embodiment of the present invention, the nitrogen precooler 2, the first reheater 4, the third reheater 6 and the fifth reheater 8 all use gas-liquid heat exchangers, and the liquid nitrogen precooler 3, the second reheater 5 and the fourth reheater 7 all use gas-liquid heat exchangers.

The helium circulating pipeline 19 is the core for transmitting the cold energy required by the densification of the liquid oxygen and the liquid hydrogen, and the helium circulating pipeline 19 is filled with a helium working medium. The helium circulating pipeline 19 is sequentially connected with the helium compressor 1, the first passage of the nitrogen precooler 2, the first passage of the liquid nitrogen precooler 3, the first passage of the first heat regenerator 4, the first passage of the second heat regenerator 5, the first passage of the third heat regenerator 6, the first passage of the fourth heat regenerator 7, the first passage of the fifth heat regenerator 8, the throttle valve 9, the liquid helium storage tank 10, the second passage of the fifth heat regenerator 8, the second passage of the fourth heat regenerator 7, the second passage of the third heat regenerator 6, the second passage of the second heat regenerator 5, the second passage of the first heat regenerator 4, the second passage of the liquid nitrogen precooler 3 and the second passage of the nitrogen precooler 2, and then circulates to the helium compressor 1 again. The helium working fluid in the helium circulating line 19 is continuously circulated from a gaseous state to a liquid state and then to a gaseous state in the line.

In the present invention, a plurality of helium compressors 1 may be provided, and the helium compressors are continuously arranged on the helium circulating pipeline 19 in a serial connection manner, so as to improve the helium compression effect.

In the helium working medium circulation process inside the helium circulation pipeline 19, the cold energy provided by the liquid nitrogen is not enough to enable the temperature of the helium working medium to reach below the triple point of liquid oxygen and liquid hydrogen, so that two branches are required to be further arranged on the helium circulation pipeline 19 to introduce a two-stage helium expander for cooling.

The inlet end of the first helium working medium expansion branch 20 is connected with the outlet end of the first passage of the first heat regenerator 4, the outlet end of the first helium working medium expansion branch 20 is connected with the inlet end of the second passage of the second heat regenerator 5, the first helium working medium expansion branch 20 is provided with a first helium expander 11, and part of high-pressure helium working medium flowing out of the first heat regenerator 4 enters the first helium expander 11 for isentropic expansion and generates cold energy and then joins with helium working medium flowing out of the second passage in the third heat regenerator 6 and enters the second passage of the second heat regenerator 5.

Similarly, the inlet end of the second helium working medium expansion branch 21 is connected to the outlet end of the first path of the third regenerator 6, the outlet end of the second helium working medium expansion branch 21 is connected to the inlet end of the second path of the fourth regenerator 7, a second helium expander 12 is installed on the second helium working medium expansion branch 21, and part of the high-pressure helium working medium flowing out of the third regenerator 6 enters the second expander 12 for isentropic expansion and generates cold energy, and then joins the helium working medium flowing out of the second path of the fifth regenerator 8 and enters the second path of the fourth regenerator 7.

An inlet end of a liquid nitrogen pipeline 22 is connected with a liquid nitrogen supply source, and an outlet end of the liquid nitrogen pipeline 22 is emptied after sequentially passing through a third passage of the liquid nitrogen precooler 3 and a third passage of the nitrogen precooler 2. The specific form of the liquid nitrogen supply source is not limited as long as liquid nitrogen can be supplied through the liquid nitrogen line 22. Liquid nitrogen supplied by a liquid nitrogen supply source forms low-temperature nitrogen through first heat exchange in a liquid nitrogen precooler 3, then absorbs heat further in a nitrogen precooler 2 to form high-temperature nitrogen, and finally is emptied. The liquid nitrogen supply source preferably adopts a self-pressurization mode to input liquid nitrogen into the liquid nitrogen pipeline 22, namely the liquid nitrogen is placed in the container, the inlet end of the liquid nitrogen pipeline 22 extends below the liquid level of the liquid nitrogen in the container, part of the liquid nitrogen forms a gas state in the container through heat absorption, the pressure in the container is further increased, and the rest of the liquid nitrogen is pressed into the liquid nitrogen pipeline 22.

Under the matching of the helium circulating pipeline 19, the first helium working medium expansion branch 20, the second helium working medium expansion branch 21 and the liquid nitrogen pipeline 22, a helium working medium is firstly compressed by the helium compressor 1 to form a high-temperature high-pressure helium working medium, then the helium working medium returned by the helium circulating pipeline 19 and low-temperature nitrogen in the liquid nitrogen pipeline 22 are cooled in the nitrogen precooler 2, then the helium working medium returned by the helium circulating pipeline 19 and liquid nitrogen in the liquid nitrogen pipeline 22 are continuously cooled in the liquid nitrogen precooler 3, and then the low-temperature helium working medium returned by the helium circulating pipeline 19 is input into the first heat regenerator 4 to be cooled. Therefore, after the nitrogen precooler 2, the liquid nitrogen precooler 3 and the first reheater 4 are cooled in three stages, the helium working medium forms a low-temperature gas state, but the low-temperature required by densification of liquid oxygen and liquid hydrogen is not reached at the moment. Therefore, the first helium working medium expansion branch 20 and the second helium working medium expansion branch 21 need to lead out two helium working medium branches from the helium circulating pipeline 19, and respectively perform isentropic expansion to reduce the temperature of the helium working medium, and the two helium working mediums after isentropic expansion need to be led into the helium circulating pipeline 19 again, so that the two helium working mediums are used for densifying liquid oxygen and liquid hydrogen on one hand, and are used for cooling a helium working medium main stream in the helium circulating pipeline 19 on the other hand. Therefore, in the process that a helium working medium main flow in the helium circulating pipeline 19 sequentially flows through the second heat regenerator 5, the third heat regenerator 6, the fourth heat regenerator 7 and the fifth heat regenerator 8, the temperature gradually decreases, finally the helium working medium main flow is converted from a gas state into a gas-liquid two-phase state after being throttled by the throttle valve 9, liquid helium is directly stored in the liquid helium storage tank 10 and is used for preparing slurry hydrogen or solid hydrogen, gaseous low-temperature helium gas is continuously discharged from the top of the liquid helium storage tank 10 and enters a helium circulating pipeline 19 loop in a return helium working medium mode, cold energy is continuously released again through the fifth heat regenerator 8, the fourth heat regenerator 7, the third heat regenerator 6 and the second heat regenerator 5 and then returns to the helium compressor 1, and circulation from the gas state to the liquid state and then to the gas state is completed.

Based on the cold energy provided by the helium circulating pipeline 19 and the liquid nitrogen pipeline 22, the synchronous liquefaction of the liquid oxygen and the liquid hydrogen can be realized through the liquid oxygen pipeline 23 and the liquid hydrogen pipeline 24 respectively, and the liquid helium is introduced to prepare the slurry hydrogen or the solid hydrogen by the aid of the liquid helium pipeline 25.

The inlet end of a liquid oxygen pipeline 23 in the invention is connected with a liquid oxygen supply source, and the liquid oxygen pipeline 23 is connected with a liquid oxygen pump 13, a liquid nitrogen bath heat exchanger 14 and a third passage of a second regenerator 5 in sequence and then is connected with a densified liquid oxygen storage tank 15. The specific form of the liquid oxygen supply source is not limited, and the liquid oxygen propellant can be supplied. The liquid oxygen supply source conveys liquid oxygen propellant along a liquid oxygen pipeline 23 under the power action provided by a liquid oxygen pump 13, and the liquid oxygen propellant is stored in a densified liquid oxygen storage tank 15 at the temperature close to the three-phase point of the liquid oxygen after passing through the two-stage supercooling of the liquid nitrogen bath heat exchanger 14 and the second regenerator 5.

In the embodiment of the present invention, the liquid nitrogen bath heat exchanger 14 may be an open type liquid nitrogen bath heat exchanger. Open liquid nitrogen bath heat exchanger regards as the cold source with the liquid nitrogen, thereby the heat transfer cavity that holds the liquid nitrogen is uncovered and inside arrangement heat transfer pipeline forms the liquid nitrogen bath environment in the heat exchanger. The liquid oxygen pipeline 23 is communicated with a heat exchange pipeline immersed in a liquid nitrogen bath in the heat exchanger, and liquid nitrogen in the heat exchange cavity cools the liquid oxygen in the liquid oxygen pipeline 23 to generate nitrogen and directly exhaust the nitrogen. And the open liquid nitrogen bath heat exchanger is connected with a liquid nitrogen source, and when liquid nitrogen generated by cooling liquid oxygen is consumed, the liquid nitrogen source can directly supplement the liquid nitrogen to the open liquid nitrogen bath heat exchanger.

The inlet end of the liquid hydrogen pipeline 24 in the invention is connected with a liquid hydrogen supply source, and the liquid hydrogen pipeline 24 is connected with the liquid hydrogen pump 16 and the third passage of the fourth heat regenerator 7 in sequence and then is connected with the densification liquid hydrogen preparation and storage container 17. The specific form of the liquid hydrogen supply source is not limited, and the liquid hydrogen propellant can be supplied. The liquid hydrogen supply source delivers liquid hydrogen propellant along the liquid hydrogen pipeline 24 under the power provided by the liquid hydrogen pump 16, and the liquid hydrogen propellant is stored in the densified liquid hydrogen preparation and storage container 17 at a temperature (13.96K) close to the triple point of liquid hydrogen after being supercooled by the return helium working medium in the second pipeline of the fourth regenerator 7 and the helium working medium after secondary expansion. After the liquid hydrogen is supercooled from the standard boiling point (20.37K) to the triple point temperature (13.96K), the density is increased by 8.8 percent, and the sensible heat per unit volume is increased by 20 percent, but if the temperature is continuously reduced from the triple point state, slurry hydrogen or solid hydrogen is formed, when 60 percent of the solid hydrogen is generated, the density is increased by 16.8 percent, and the sensible heat per unit volume is increased by 34 percent. Thus, to further prepare slurry hydrogen or solid hydrogen, in the present invention, liquid helium is introduced into densification liquid hydrogen production and storage vessel 17 via liquid helium line 25, and liquid hydrogen at a triple point temperature (13.96K) is directly contact heat exchanged with liquid helium to form slurry hydrogen or solid hydrogen and stored directly in densification liquid hydrogen production and storage vessel 17.

The liquid helium pipeline 25 of the present invention is connected to the liquid helium outlet at the bottom of the liquid helium storage tank 10, the densification liquid hydrogen preparation and storage container 17, and the helium gas purifier 18 in sequence, and then is connected to the helium circulation pipeline 19 before the inlet end of the second passage in the fifth heat regenerator 8. The liquid helium is generally accumulated at the bottom of the liquid helium storage tank 10 under the action of gravity, so the inlet end of the liquid helium pipeline 25 needs to extend below the liquid level of the liquid helium, and the power for conveying the liquid helium in the liquid helium pipeline 25 can be provided by a cryogenic fluid pump or by a self-pressurization method with reference to the liquid nitrogen conveying method. The liquid helium stored in the liquid helium storage tank 10 is input into the densification liquid hydrogen preparation and storage container 17 through a liquid helium pipeline 25, directly exchanges heat with the supercooled liquid hydrogen input through a liquid hydrogen pipeline 24 in a contact manner to form slurry hydrogen or solid hydrogen, the slurry hydrogen or the solid hydrogen is stored in the densification liquid hydrogen preparation and storage container 17, and the liquid helium is converted from a liquid state to a gas state and then enters a helium circulation pipeline 19 for circulation. In order to ensure sufficient contact heat exchange between the liquid helium and the liquid hydrogen, a spraying device may be provided in the densification liquid hydrogen preparation and storage vessel 17 to spray the liquid helium into the densification liquid hydrogen preparation and storage vessel 17 from top to bottom in a spraying manner. In the process of contacting liquid helium and liquid hydrogen, the liquid helium absorbs heat to be vaporized, while the liquid hydrogen is mostly converted into slurry hydrogen or solid hydrogen, but the liquid helium and the solid hydrogen are directly contacted, so that part of hydrogen is inevitably mixed into the generated helium gas to form helium-hydrogen mixed gas. Therefore, the helium-hydrogen mixture gas is exhausted from the top gas outlet of the densification liquid hydrogen preparation and storage vessel 17 and then needs to be purified by passing it through the liquid helium line 25 into the helium purifier 18.

In the present invention, the helium purifier 18 may be any device capable of separating and purifying pure helium from a helium-hydrogen mixture gas, such as an adsorption separation device, a membrane separation device or a combustion condensation device. The adsorption separation equipment can selectively adsorb hydrogen or helium so as to purify the helium; the membrane separation equipment can separate hydrogen and helium through a membrane module; the combustion condensing equipment can be used for combusting hydrogen and then condensing water generated by combustion to further obtain purified helium.

Because the cold quantity required by the densification of the liquid oxygen and the liquid hydrogen is realized by depending on the isentropic expansion of the two stages of helium expanders on the helium working medium, in order to ensure that the densification process of the liquid oxygen and the liquid hydrogen is reliably realized, the outlets of the first helium expander 11 and the second helium expander 12 can be provided with a thermometer and a pressure gauge, the outlet pressure of the first helium expander can be set according to the requirements of the supercooling of the liquid oxygen and the supercooling of the liquid hydrogen, and the efficient and rapid densification of the liquid oxygen and the liquid hydrogen is realized. Generally, the helium working medium outlet temperature of the first helium expander 11 needs to be controlled to 54.4K or less, and the helium working medium outlet temperature of the second helium expander 12 needs to be controlled to 13.86K or less. Therefore, in the synchronous preparation system, the temperature zones of the heat regenerators are reasonable, a gradient temperature field with uniform temperature difference is formed, and the thermodynamic efficiency of the synchronous preparation system for the high-density oxyhydrogen propellant is effectively improved. The power of components such as a helium compressor, a helium expander and the like can be effectively reduced by using a liquid nitrogen medium two-stage precooled compressed high-temperature helium working medium with low price and high safety.

In addition, because the working medium in the synchronous preparation system is in a low-temperature or ultralow-temperature state, various heat exchangers, pipelines and helium expanders in the system need to be subjected to heat insulation treatment with the external environment, namely, various heat exchangers, pipelines, helium expanders and the like in the system need to be wrapped by high-performance vacuum heat insulation materials, so that direct heat exchange with the external environment is avoided.

In addition, in order to improve the heat exchange efficiency, heat exchange passages formed in the nitrogen precooler 2, the liquid nitrogen precooler 3, the first heat regenerator 4, the second heat regenerator 5, the third heat regenerator 6, the fourth heat regenerator 7 and the fifth heat regenerator 8 are all arranged in a counter-flow mode, so that the cold and hot fluids for heat exchange heat in a counter-flow mode.

In another preferred embodiment of the present invention, the above-mentioned synchronous preparation system shown in fig. 1 is used to provide a synchronous preparation method of high-density hydrogen-oxygen propellant, which comprises the following steps:

s1, inputting a liquid nitrogen medium into a liquid nitrogen pipeline 22 through a self-pressurization method, enabling the liquid nitrogen medium to sequentially flow through a third passage of a liquid nitrogen precooler 3 and a third passage of a nitrogen precooler 2 to continuously release cold energy, and then emptying the liquid nitrogen.

S2, continuously inputting a liquid nitrogen medium into a liquid nitrogen pipeline 22, starting a helium compressor 1, a first helium expander 11 and a second helium expander 12, compressing a helium working medium in a helium circulating pipeline 19 through the helium compressor 1, then heating and boosting, changing from a low-pressure normal-temperature state to a high-pressure high-temperature state, and then sequentially flowing through a first passage of a nitrogen precooler 2, a first passage of a liquid nitrogen precooler 3 and a first passage of a first reheater 4 to carry out three-stage cooling.

S3, helium working medium output by the first passage of the first heat regenerator 4 is divided into a main flow and a branch flow, the branch helium working medium enters the first helium expander 11 through the first helium working medium expansion branch 20 to be subjected to isentropic expansion, temperature reduction and depressurization, the high-pressure state is converted into the low-pressure state, the temperature is greatly reduced, the outlet temperature is reduced to be lower than the liquid oxygen triple point temperature (54.4K), then the branch helium working medium enters the helium circulating pipeline 19 again, is mixed with the returned helium working medium from the third heat regenerator 6 and then enters the second passage of the second heat regenerator 5 to release cold energy, and the main helium working medium flows through the first passage of the second heat regenerator 5 and the first passage of the third heat regenerator 6 in sequence to continuously absorb the cold energy for cooling.

S4, helium working medium output by the first passage of the third heat regenerator 6 is continuously divided into a main flow and a branch flow, the branch helium working medium enters the second helium expander 12 through the second helium working medium expansion branch 21 to be subjected to isentropic expansion, temperature reduction and depressurization, the high-pressure state is converted into the low-pressure state, the temperature is greatly reduced, the outlet temperature is reduced to be lower than the liquid hydrogen triple point temperature (13.86K), the mixture enters the helium circulating pipeline 19 again, the mixture is mixed with the return helium working medium from the fifth heat regenerator 8 and then enters the second passage of the fourth heat regenerator 7 to release cold energy, and the main helium working medium flows through the first passage of the fourth heat regenerator 7 and the first passage of the fifth heat regenerator 8 in sequence to continuously absorb the cold energy for cooling.

S5, the helium working medium output by the first passage of the fifth heat regenerator 8 is throttled by a throttle valve 9 and then is converted from a gas state into a gas-liquid two-phase state, liquid helium is directly stored in a liquid helium storage tank 10 and used for preparing slurry hydrogen or solid hydrogen, the low-temperature gas helium working medium is mixed with the gas helium working medium returned by a liquid helium pipeline 25 and then sequentially flows through the second passage of the fifth heat regenerator 8, the second passage of the fourth heat regenerator 7, the second passage of the third heat regenerator 6, the second passage of the second heat regenerator 5, the second passage of the first heat regenerator 4, the second passage of the liquid nitrogen precooler 3 and the second passage of the nitrogen precooler 2 to continuously release cold energy, the low-temperature state is converted into a normal-temperature state, finally, the helium working medium in the helium circulating pipeline 19 enters the helium compressor 1 again to be compressed, and the reciprocating circulation provides cold energy for deep supercooling of each low-temperature propellant.

It should be noted that, in the subsequent low-temperature densification with liquid oxygen and liquid hydrogen, the steps S1 to S5 need to be performed all the time.

S6, keeping the helium working medium in the helium circulating pipeline 19 to continuously circulate back and forth to provide cold energy, starting the liquid oxygen pump 13, continuously introducing liquid nitrogen into the liquid nitrogen bath heat exchanger 14, firstly inputting a liquid oxygen propellant into the liquid nitrogen bath heat exchanger 14 through the liquid oxygen pipeline 23, absorbing the cold energy of the liquid nitrogen to finish primary supercooling, and directly evacuating the liquid nitrogen medium in the liquid nitrogen bath heat exchanger 14 by vaporization; and then the liquid oxygen propellant enters a third passage of the second heat regenerator 5, and simultaneously absorbs the returned helium working medium output by the third heat regenerator 6 and the cold energy of the helium working medium output by the first helium expander 11 after the first stage of expansion to finish the second stage of supercooling, and when the temperature of a liquid oxygen outlet is close to the temperature of a triple point, the liquid oxygen densification is finished and the liquid oxygen is stored in a densified liquid oxygen storage tank 15.

S7, keeping the helium working medium in the helium circulating pipeline 19 to continuously circulate back and forth to provide cold energy, starting a liquid hydrogen pump 16, inputting a liquid hydrogen propellant into a third passage of the fourth heat regenerator 7 through a liquid hydrogen pipeline 24, and absorbing the cold energy of the returned helium working medium output by the fifth heat regenerator 8 and the two-stage expanded helium working medium output by the second helium expander 12 for supercooling to form three-phase-point liquid hydrogen and then entering a densification liquid hydrogen preparation and storage container 17; liquid helium in the liquid helium storage tank 10 is input into a densified liquid hydrogen preparation and storage container 17 through a liquid helium pipeline 25 in a pressurization mode, direct heat exchange is carried out on the liquid helium in a triple point state through a spraying mode, the liquid hydrogen in the triple point state is converted into high-density forms such as slurry hydrogen or solid hydrogen, the liquid helium is discharged from the top of the container after heat exchange and vaporization and enters a helium purifier 18 through the liquid helium pipeline 25 for purification, and the purified high-purity helium is merged into a helium circulating pipeline 19 and mixed with a helium working medium from the liquid helium storage tank 10 for recycling.

It should be noted that, in the process of densification by the liquid oxygen propellant and the liquid hydrogen propellant, the temperatures of the propellants finally stored in the storage tank need to be close to the respective triple point temperatures, and the specific end point temperature needs to be determined according to the desired degree of densification. Different end temperatures correspond to different propellant densities, and the lower the temperature, the higher the densification degree is, but the energy consumption is increased, so that reasonable balance is needed according to actual needs.

In conclusion, the preparation process of the high-density oxyhydrogen propellant can be coupled in the circulating system through the open helium liquefaction circulating process, so that the liquid oxygen and the liquid hydrogen realize synchronous supercooling densification, the densified low-temperature propellant with higher density and larger heat capacity is obtained, the filling amount can be obviously increased, the rocket body size and the structure weight of the carrier rocket are reduced, and the storage time is prolonged. For the space launching field needing different low-temperature propellants, the invention can solve the problems that different low-temperature propellants need to be prepared separately and the efficiency is low, and greatly improves the supply capacity and the supply quality of the low-temperature propellants of the space launching field.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are also included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (10)

1. A high-density hydrogen-oxygen propellant synchronous preparation system is characterized by comprising a nitrogen precooler (2), a liquid nitrogen precooler (3), a first heat regenerator (4), a second heat regenerator (5), a third heat regenerator (6), a fourth heat regenerator (7), a fifth heat regenerator (8), a helium circulating pipeline (19), a first helium working medium expansion branch (20), a second working medium expansion branch (21), a liquid nitrogen pipeline (22), a liquid oxygen pipeline (23), a liquid hydrogen pipeline (24) and a liquid helium pipeline (25);

a first passage, a second passage and a third passage are arranged in the nitrogen precooler (2), the liquid nitrogen precooler (3), the second heat regenerator (5) and the fourth heat regenerator (7), wherein the first passages in the nitrogen precooler (2) and the liquid nitrogen precooler (3) are respectively in heat exchange contact with the second passage and the third passage, and the second passages in the second heat regenerator (5) and the fourth heat regenerator (7) are respectively in heat exchange contact with the first passage and the third passage; a first passage and a second passage which form heat exchange contact are arranged in the first heat regenerator (4), the third heat regenerator (6) and the fifth heat regenerator (8);

the helium circulating pipeline (19) is filled with a helium working medium, the helium circulating pipeline (19) is sequentially connected with a helium compressor (1), a first passage of a nitrogen precooler (2), a first passage of a liquid nitrogen precooler (3), a first passage of a first regenerator (4), a first passage of a second regenerator (5), a first passage of a third regenerator (6), a first passage of a fourth regenerator (7), a first passage of a fifth regenerator (8), a throttle valve (9), a liquid helium storage tank (10), a second passage of a fifth regenerator (8), a second passage of a fourth regenerator (7), a second passage of a third regenerator (6), a second passage of the second regenerator (5), a second passage of the first regenerator (4), a second passage of the liquid nitrogen precooler (3) and a second passage of the nitrogen precooler (2), and then is recirculated to the helium compressor (1), and gaseous helium is continuously circulated from the helium compressor (19) to the helium circulating pipeline;

the inlet end of the first helium working medium expansion branch (20) is connected with the outlet end of a first passage of the first heat regenerator (4), the outlet end of the first helium working medium expansion branch (20) is connected with the inlet end of a second passage of the second heat regenerator (5), a first helium expander (11) is installed on the first helium working medium expansion branch (20), part of high-pressure helium working medium flowing out of the first heat regenerator (4) enters the first helium expander (11) for isentropic expansion and generates cold energy, and then the cold energy and helium working medium flowing out of the second passage in the third heat regenerator (6) are converged and enter the second passage of the second heat regenerator (5);

the inlet end of the second helium working medium expansion branch (21) is connected with the outlet end of the first passage of the third heat regenerator (6), the outlet end of the second helium working medium expansion branch (21) is connected with the inlet end of the second passage of the fourth heat regenerator (7), a second helium expander (12) is installed on the second helium working medium expansion branch (21), part of high-pressure helium working medium flowing out of the third heat regenerator (6) enters the second expander (12) for isentropic expansion and generates cold energy, and then the cold energy and the helium working medium flowing out of the second passage in the fifth heat regenerator (8) are converged and enter the second passage of the fourth heat regenerator (7);

the inlet end of the liquid nitrogen pipeline (22) is connected with a liquid nitrogen supply source, and the outlet end of the liquid nitrogen pipeline (22) is evacuated after passing through a third passage of the liquid nitrogen precooler (3) and a third passage of the nitrogen precooler (2) in sequence;

the inlet end of the liquid oxygen pipeline (23) is connected with a liquid oxygen supply source, the liquid oxygen pipeline (23) is connected with a liquid oxygen pump (13), a liquid nitrogen bath heat exchanger (14) and a third channel of the second heat regenerator (5) in sequence and then is connected into a densified liquid oxygen storage tank (15), and liquid oxygen propellant conveyed by the liquid oxygen supply source is stored in the densified liquid oxygen storage tank (15) after passing through the two-stage supercooling of the liquid nitrogen bath heat exchanger (14) and the second heat regenerator (5);

the inlet end of the liquid hydrogen pipeline (24) is connected with a liquid hydrogen supply source, the liquid hydrogen pipeline (24) is connected with third passages of a liquid hydrogen pump (16) and a fourth heat regenerator (7) in sequence and then is connected into a densification liquid hydrogen preparation and storage container (17), and liquid hydrogen propellant conveyed by the liquid hydrogen supply source enters the densification liquid hydrogen preparation and storage container (17) after being cooled by the fourth heat regenerator (7) and then is subjected to direct contact type heat exchange with liquid helium to form slurry hydrogen or solid hydrogen which is directly stored.

The liquid helium pipeline (25) is connected with a liquid helium outlet at the bottom of the liquid helium storage tank (10), a densification liquid hydrogen preparation and storage container (17) and a helium gas purifier (18) in sequence and then is connected with a helium circulating pipeline (19) in the fifth heat regenerator (8) before the inlet end of the second passage; liquid helium stored in the liquid helium storage tank (10) is input into a densification liquid hydrogen preparation and storage container (17) through a liquid helium pipeline (25), and directly exchanges heat with supercooled liquid hydrogen input through a liquid hydrogen pipeline (24) in a contact mode to form slurry hydrogen or solid hydrogen, the slurry hydrogen or the solid hydrogen is stored in the densification liquid hydrogen preparation and storage container (17), and the liquid helium is converted from a liquid state to a gas state and then enters a helium circulation pipeline (19) for circulation.

2. The system for synchronously preparing high-density oxyhydrogen propellant according to claim 1, wherein the outlets of the first helium expander (11) and the second helium expander (12) are provided with a temperature gauge and a pressure gauge.

3. The system for synchronously preparing high-density oxyhydrogen propellant according to claim 1, wherein the heat exchanger, the pipeline and the helium expander in the preparation system are all insulated from the environment.

4. The system for synchronously preparing the high-density oxyhydrogen propellant according to claim 1, wherein the liquid nitrogen bath heat exchanger (14) adopts an open liquid nitrogen bath heat exchanger, the liquid oxygen pipeline (23) is communicated with a heat exchange pipeline immersed in the liquid nitrogen bath in the heat exchanger, the liquid nitrogen cools the liquid oxygen in the liquid oxygen pipeline (23) to generate nitrogen and directly evacuate the nitrogen, and the open liquid nitrogen bath heat exchanger is connected with a liquid nitrogen source for supplementing consumed liquid nitrogen.

5. The system for synchronously preparing high-density hydrogen-oxygen propellant as claimed in claim 1, wherein the nitrogen precooler (2), the first regenerator (4), the third regenerator (6) and the fifth regenerator (8) adopt gas-gas type heat exchangers.

6. The system for synchronously preparing the high-density oxyhydrogen propellant according to claim 1, wherein the liquid nitrogen precooler (3), the second regenerator (5) and the fourth regenerator (7) adopt gas-liquid heat exchangers.

7. The system for synchronously preparing the high-density oxyhydrogen propellant according to claim 1, wherein paths for heat exchange in the nitrogen precooler (2), the liquid nitrogen precooler (3), the first regenerator (4), the second regenerator (5), the third regenerator (6), the fourth regenerator (7) and the fifth regenerator (8) are arranged in a counter-flow manner.

8. The system for synchronously preparing high-density hydrogen-oxygen propellant as claimed in claim 1, wherein the helium purifier (18) adopts an adsorption separation device, a membrane separation device or a combustion condensation device which can separate and purify pure helium from the helium-hydrogen mixed gas.

9. The system for synchronously preparing high-density hydrogen and oxygen propellant as claimed in claim 1, wherein there are a plurality of helium compressors (1) arranged in series on the helium circulating pipeline (19).

10. A method for simultaneously preparing a high-density hydrogen-oxygen propellant by using the preparation system as claimed in any one of claims 1 to 9, comprising:

s1, inputting a liquid nitrogen medium into a liquid nitrogen pipeline (22) through a self-pressurization method, sequentially flowing through a third passage of a liquid nitrogen precooler (3) and a third passage of a nitrogen precooler (2) to continuously release cold energy, and then emptying;

s2, keeping a liquid nitrogen medium continuously input into a liquid nitrogen pipeline (22), starting a helium compressor (1), a first helium expander (11) and a second helium expander (12), compressing a helium working medium in a helium circulating pipeline (19) through the helium compressor (1), then heating and boosting, and sequentially flowing through a first passage of a nitrogen precooler (2), a first passage of a liquid nitrogen precooler (3) and a first passage of a first reheater (4) to perform three-stage cooling;

s3, helium working medium output by a first passage of a first heat regenerator (4) is divided into a main flow part and a branch flow part, the branch helium working medium enters a first helium expander (11) through a first helium working medium expansion branch (20) to carry out isentropic expansion, temperature reduction and pressure reduction, the outlet temperature is reduced to be lower than the temperature of a liquid oxygen triple point, then the branch helium working medium enters a helium circulation pipeline (19) again, is mixed with the return helium working medium from a third heat regenerator (6) and then enters a second passage of the second heat regenerator (5) to release cold energy, and the main flow helium working medium sequentially flows through the first passage of the second heat regenerator (5) and the first passage of the third heat regenerator (6) to continuously absorb the cold energy for temperature reduction;

s4, helium working medium output by a first passage of the third heat regenerator (6) is continuously divided into a main flow and a branch flow, the branch helium working medium enters the second helium expander (12) through the second helium working medium expansion branch (21) to be subjected to isentropic expansion, temperature reduction and pressure reduction, the outlet temperature is reduced to be lower than the liquid-hydrogen triple point temperature and then enters the helium circulating pipeline (19) again, the branch helium working medium is mixed with the return helium working medium from the fifth heat regenerator (8) and then enters a second passage of the fourth heat regenerator (7) to release cold energy, and the main helium working medium sequentially flows through the first passage of the fourth heat regenerator (7) and the first passage of the fifth heat regenerator (8) to continuously absorb the cold energy for temperature reduction;

s5, a helium working medium output by a first passage of a fifth heat regenerator (8) is throttled by a throttle valve (9) and then is converted from a gaseous state into a gas-liquid two-phase state, liquid helium is directly stored in a liquid helium storage tank (10) and used for preparing slurry hydrogen or solid hydrogen, a low-temperature gaseous helium working medium is mixed with the gaseous helium working medium returned by a liquid helium pipeline (25) and then sequentially flows through a second passage of the fifth heat regenerator (8), a second passage of a fourth heat regenerator (7), a second passage of a third heat regenerator (6), a second passage of a second heat regenerator (5), a second passage of a first heat regenerator (4), a second passage of a liquid nitrogen precooler (3) and a second passage of a nitrogen precooler (2) to continuously release cold energy, finally the helium working medium in a helium circulating pipeline (19) enters a helium compressor (1) again to be compressed, and the reciprocating circulation provides cold energy for deep supercooling of each low-temperature propellant;

s6, starting a liquid oxygen pump (13), continuously introducing liquid nitrogen into the liquid nitrogen bath heat exchanger (14), firstly inputting a liquid oxygen propellant into the liquid nitrogen bath heat exchanger (14) through a liquid oxygen pipeline (23), absorbing the cold energy of the liquid nitrogen to complete the first stage of supercooling, and directly evacuating the liquid nitrogen medium in the liquid nitrogen bath heat exchanger (14) by vaporization; then liquid oxygen propellant enters a third passage of the second heat regenerator (5), and simultaneously absorbs the cold energy of the returned helium working medium output by the third heat regenerator (6) and the helium working medium after the first stage of expansion output by the first helium expander (11) to complete the second stage of supercooling, and when the temperature of a liquid oxygen outlet is close to the temperature of a triple point, the liquid oxygen densification is completed and the liquid oxygen is stored in a densified liquid oxygen storage tank (15);

s7, starting a liquid hydrogen pump (16), inputting a liquid hydrogen propellant into a third passage of a fourth heat regenerator (7) through a liquid hydrogen pipeline (24), and absorbing a return helium working medium output by a fifth heat regenerator (8) and the cold energy of the helium working medium output by a second helium expander (12) after secondary expansion to perform supercooling to form liquid hydrogen in a triple-point state and then enter a densification liquid hydrogen preparation and storage container (17); liquid helium in a liquid helium storage tank (10) is input into a densification liquid hydrogen preparation and storage container (17) through a liquid helium pipeline (25) in a pressurization mode, the liquid helium directly exchanges heat with liquid hydrogen in a triple point state through a spraying mode, the liquid hydrogen in the triple point state is converted into slurry hydrogen or a solid hydrogen state, the liquid helium is discharged from the top of the container after heat exchange and vaporization and enters a helium purifier (18) through the liquid helium pipeline (25) for purification, and pure helium obtained through purification is merged into a helium circulating pipeline (19) and mixed with helium working medium from the liquid helium storage tank (10) for recycling.

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