Thermodynamic exhaust system and method adopting periodic sweeping injection

Abstract

The invention belongs to the technical field of low-temperature propellant space storage, and discloses a thermodynamic exhaust system adopting periodic sweeping injection, which comprises a low-temperature propellant storage tank, a concentric multi-layer heat exchanger is arranged in the low-temperature propellant storage tank, and the concentric multi-layer heat exchanger sequentially comprises a hot layer, a cold layer and a spray layer from inside to outside, the fluid oscillator is arranged at the orifice of the spray layer and periodically sweeps and sprays fluid into the tank, the fluid in the cold layer cools the fluid in the hot layer and the fluid in the spray layer, and cold energy is fully utilized, so that the temperature and pressure in the storage tank are reduced. In addition, the concentric multi-layer heat exchanger enables the spray layer, the cold layer and the hot layer to be made into a heat exchanger device, cold energy of the cold layer can be further utilized and transmitted to the spray layer, and the energy utilization rate is improved. The fluid oscillator can enable the fluid to be periodically swept and ejected, disturbance to a flow field in the storage tank is further enhanced, and heat exchange of the fluid is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of cryogenic propellant space storage, and in particular to a thermodynamic exhaust system and method using periodic sweep injection. Background Art

[0002] Cryogenic propellants have the advantages of large specific impulse, non-toxicity and pollution-free, and are widely used in launch vehicles at home and abroad. There are corresponding requirements for the storage of cryogenic propellants. During the on-orbit stage, even if a lot of passive insulation work is done on the cryogenic storage tank, such as adding multiple layers of insulation, it is still impossible to avoid some heat leakage from seeping into the tank, causing thermal stratification of the fluid in the tank and causing the pressure in the tank to increase. If it is not controlled, it may cause safety problems such as leakage of cryogenic propellant and explosion of the tank. Therefore, pressure reduction must be carried out. The most traditional method of pressure reduction is to open a hole at the top to directly exhaust and reduce the pressure. However, during the on-orbit stage, in a microgravity environment, weak forces such as surface tension play a dominant role, and the gas-liquid mixing in the tank is serious. The pressure reduction effect of opening a hole at the top is not significant, and it will also result in a high loss of propellant storage. Thus, the thermodynamic exhaust system was born. It uses a circulating pump to extract the low-temperature liquid at the bottom of the tank and divides it into two paths. A small part of the branch is throttled and cooled, and then the branch is heat exchanged with the mainstream through a shell-and-tube heat exchanger. The mainstream after heat exchange is introduced into the spray rod and sprayed into the tank through the nozzle, so as to achieve the cooling and pressure reduction of the high-temperature fluid in the tank. However, through research and comparison, it was found that the cold capacity is not fully utilized in ordinary shell-and-tube heat exchangers, and the cold capacity of the branch fluid is not fully transferred to the tank. In addition, the disturbance of the flow field caused by the ordinary orifice injection into the tank is limited, especially the stirring ability in the vertical direction is poor, the thermal stratification phenomenon in the space is not well eliminated, and the heat exchange needs to be further strengthened. Summary of the invention

[0003] In response to the above defects or improvement needs of the prior art, the present invention provides a thermodynamic exhaust system and method using periodic sweeping injection, which fully utilizes the cooling capacity of the branch flow, enhances the heat and mass transfer capacity between the fluids in the storage tank, accelerates the elimination of thermal stratification, and reduces the temperature and pressure of the fluid in the storage tank as quickly as possible.

[0004] To achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided a thermodynamic exhaust system using periodic sweeping injection, comprising a cryogenic propellant storage tank, wherein a concentric multi-layer heat exchanger is arranged in the cryogenic propellant storage tank, wherein the concentric multi-layer heat exchanger comprises a hot layer, a cold layer and a spray layer in sequence from the inside to the outside, wherein a fluid oscillator is arranged at the orifice of the spray layer, and the fluid oscillator periodically sweeps and injects the fluid into the tank, and the fluid in the cold layer cools the fluid in the hot layer and the fluid in the spray layer, thereby making full use of the cold energy.

[0005] Preferably, it also includes a liquid pipeline connected to the bottom of the cryogenic propellant storage tank, the liquid pipeline is connected to a circulation pump, the outlet of the circulation pump is connected to a mainstream pipeline and a branch pipeline, the mainstream pipeline is connected to a hot layer inlet, and the branch pipeline is connected to a cold layer inlet.

[0006] Preferably, the outlet of the heat layer is connected to the spray layer, the liquid in the heat layer moves from bottom to top, and the liquid in the spray layer flows from bottom to bottom toward the fluid oscillator.

[0007] Preferably, a throttle valve is provided on the branch pipeline, which is connected to the cold layer inlet via the throttle valve, and the top of the cold layer is connected to the exhaust pipe.

[0008] Preferably, the exhaust pipe is communicated with the vacuum environment.

[0009] Preferably, the fluid oscillator is a Coanda swept fluid oscillator, which ejects a low-temperature fluid to exchange heat with a high-temperature fluid in the cryogenic propellant tank, thereby reducing the fluid temperature and tank pressure in the cryogenic propellant tank.

[0010] Preferably, the fluid oscillators in each column are distributed at equal intervals, and the fluid oscillators in two adjacent columns are distributed alternately.

[0011] Preferably, the interval between two adjacent fluid oscillators in each column is 60 mm, and the height difference between each fluid oscillator and the adjacent fluid oscillators in the adjacent column is 30 mm.

[0012] Preferably, the distance from each fluid oscillator to the center of the thermal layer is equal to the interval between two adjacent fluid oscillators in each column.

[0013] To achieve the above object, according to another aspect of the present invention, a thermodynamic exhaust method using periodic sweep injection is provided, which uses the above thermodynamic exhaust system and includes the following steps:

[0014] S1: When the pressure in the cryogenic propellant storage tank rises to the upper limit, the circulation pump is started to pump out the cryogenic propellant liquid in the storage tank. After passing through the circulation pump, it is divided into two routes: the mainstream pipeline and the branch pipeline. The main fluid is sent to the hot layer of the concentric multi-layer heat exchanger, and the branch fluid is sent to the cold layer of the concentric multi-layer heat exchanger after throttling, reducing pressure and temperature through the throttle valve. Then the branch fluid reaches the outlet of the cold layer and is discharged into the vacuum environment;

[0015] S2: After entering the hot layer, the main fluid will exchange heat with the branch fluid in the cold layer. After reaching the outlet of the hot layer, it will enter the spray layer, where it will exchange heat with the branch fluid in the cold layer to cool down, thus making full use of the cold energy.

[0016] S3: Then the main fluid enters the fluid oscillator at the outlet of the spray layer. Due to the Coanda effect in the fluid oscillator, it will eventually present a periodic sweeping jet flow state at the outlet of the fluid oscillator and be sprayed into the cryogenic propellant tank. The periodic sweeping jet in the vertical direction can strongly disturb the flow field of the cryogenic propellant fluid, enhance the heat and mass transfer capacity of the fluid in the tank, destroy the thermal stratification phenomenon in the cryogenic propellant tank, and achieve a rapid reduction in the pressure of the cryogenic propellant.

[0017] In general, the above technical solution conceived by the present invention has the following beneficial effects compared with the prior art:

[0018] 1. The present invention integrates the traditional spray rod and the shell-and-tube heat exchanger into one device by adopting a concentric multi-layer heat exchanger, which not only simplifies the system, but also transfers the cold energy to the fluid in the spray layer, thereby realizing full utilization of the cold energy.

[0019] 2. The present invention adopts the Coanda swept fluid oscillator to achieve periodic vertical sweeping of the liquid injected into the storage tank without introducing a power mechanism, thereby enhancing the disturbance of the flow field in the storage tank, greatly eliminating the thermal stratification phenomenon in the vertical direction, and quickly reducing the temperature and pressure in the storage tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of an embodiment of the present invention;

[0021] Figure 2 It is a schematic diagram of the structure of the injection module according to an embodiment of the present invention;

[0022] Figure 3 2 is a schematic diagram of the structure of a Coanda swept fluid oscillator according to an embodiment of the present invention;

[0023] Figure 4 Schematic diagram of the upward ejection of fluid in the Coanda swept fluid oscillator according to an embodiment of the present invention;

[0024] Figure 5 It is a schematic diagram of the downward injection of fluid in the Coanda swept fluid oscillator according to an embodiment of the present invention.

[0025] In the attached figure: 1-cryogenic propellant storage tank, 2-concentric multi-layer heat exchanger, 21-hot layer, 22-cold layer, 23-spray layer, 3-fluid oscillator, 4-liquid pipeline, 5-circulation pump, 6-main pipeline, 7-branch pipeline, 8-throttle valve, 9-exhaust pipe. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] See also Figure 1 The present invention provides a thermodynamic exhaust system using periodic sweep injection, comprising a cryogenic propellant storage tank 1, wherein a concentric multilayer heat exchanger 2 is arranged inside the cryogenic propellant storage tank 1, wherein the concentric multilayer heat exchanger 2 comprises a hot layer 21, a cold layer 22 and a spray layer 23 from the inside to the outside, wherein a fluid oscillator 3 is arranged at the orifice of the spray layer 23, wherein the fluid oscillator 3 performs periodic sweep injection of the fluid into the tank, wherein the fluid in the cold layer 22 cools the fluid in the hot layer 21 and the fluid in the spray layer 23, thereby making full use of cold energy; the system also comprises a liquid pipeline 4 connected to the bottom of the cryogenic propellant storage tank 1, wherein the liquid pipeline 4 is connected to a circulating pump 5, wherein the outlet of the circulating pump 5 is connected to a mainstream pipeline 6 and a branch pipeline 7, wherein the mainstream pipeline 6 is connected to an inlet of the hot layer 21, and the branch pipeline 7 is connected to an inlet of the cold layer 22.

[0028] The outlet of the heat layer 21 is connected to the spray layer 23 , the liquid in the heat layer 21 moves from bottom to top, and the liquid in the spray layer 23 flows from bottom to bottom toward the fluid oscillator 3 .

[0029] The branch pipeline 7 is provided with a throttle valve 8, which is a low-temperature throttle valve. The throttle valve 8 is connected to the inlet of the cold layer 22, and the top of the cold layer 22 is connected to the exhaust pipe 9; the exhaust pipe 9 is in communication with the vacuum environment.

[0030] The fluid oscillator 3 is a Coanda swept fluid oscillator, which ejects low-temperature fluid to exchange heat with the high-temperature fluid in the cryogenic propellant tank 1, thereby reducing the fluid temperature and tank pressure in the cryogenic propellant tank 1; the fluid oscillator 3 and the concentric multi-layer heat exchanger 2 are made of the same aluminum alloy or copper. The dimensions of the fluid oscillator 3 in this embodiment are as follows: Figure 3 , the inlet width of the interaction zone d s =4mm, maximum width of interaction zone d L =10mm, feedback loop width d f = 2mm. The installation dimensions of the fluid oscillator 3 in this embodiment are marked as follows Figure 2 In each column, the fluid oscillators 3 are equally spaced, and in two adjacent columns, the fluid oscillators 3 are staggered; in each column, the interval between two adjacent fluid oscillators 3 is d z The height difference d between each fluid oscillator 3 and the adjacent fluid oscillator 3 in the adjacent column is 60 mm. iThe distance from each fluid oscillator 3 to the center of the thermal layer 21 is equal to the interval between two adjacent fluid oscillators 3 in each column, that is, in this embodiment, the fluid oscillators 3 in each column are spaced at an angle of 45°, and a total of 8 columns of fluid oscillators are installed.

[0031] Specifically, the cryogenic propellant liquid in the cryogenic propellant storage tank 1 fills the end a of the liquid pipeline 4, the end b of the liquid pipeline 4 is connected to the inlet of the circulation pump 5, and the outlet c of the circulation pump 5 is divided into two paths, namely the mainstream pipeline 6 and the branch pipeline 7. The inlet of the branch pipeline 7 is connected to the throttle valve 8, the outlet of the throttle valve 8 is connected to the inlet d end of the cold layer 22 of the concentric multi-layer heat exchanger 2, and the exhaust port e end of the cold layer 22 is connected to the vacuum environment; the outlet of the mainstream pipeline 6 is connected to the inlet f of the hot layer 21 of the concentric multi-layer heat exchanger 5, the outlet g of the hot layer 21 is connected to the inlet h of the spray layer 23, the outlet h of the spray 23 is connected to the inlet of the fluid oscillator 3, and the outlet i of the fluid oscillator 3 is connected to the fluid in the cryogenic propellant storage tank 1.

[0032] Reference Figure 1 and Figure 2 The hot layer pipe fg, the spray layer pipe gh and the fluid oscillator pipe hi are made of the same metal material. The cold layer 22 transfers the cold energy to the hot layer 21 and the spray layer 23 through the pipe wall, realizing full utilization of cold energy. After the main fluid is cooled by heat exchange, it flows into the fluid oscillator 3 from the outlet of the spray layer 23, and then periodically sweeps and sprays from the outlet of the fluid oscillator 3 in the vertical direction into the cryogenic propellant storage tank 1, cooling and reducing the pressure of the fluid in the tank. In addition, this periodic sweeping spray in the vertical direction has a stronger disturbance on the flow field of the fluid in the tank, which can achieve cooling and reducing pressure more quickly.

[0033] Reference Figure 3 , Figure 4 and Figure 5 The fluid oscillator 3 includes an inlet end h, an outlet end i and a barrier portion arranged therebetween, so that the fluid oscillator 3 is divided into a separation bubble formation zone op in the middle and a feedback loop q and a feedback loop r between the barrier portion and the side wall of the fluid oscillator 3 through the barrier portion, and the barrier portion is arranged on the inner wall surface o and the inner wall surface p; the fluid enters from the inlet end h of the Coanda sweeping fluid oscillator, and under any small disturbance, the fluid initially flows along one side of the inner wall surface according to the Coanda effect (such as Figure 4 At this time, along the inner wall surface p side), due to the flow limiting effect of the outlet, part of the fluid flows back through the feedback loop r and replenishes the separation bubble on the inner wall surface p side, and the separation bubble gradually grows to Figure 5 When in the state, the main fluid will be pushed to flow along the inner wall surface o side wall surface, and this cycle will be repeated, which will cause the fluid passing through the Coanda swept fluid oscillator to be periodically swept and ejected.

[0034] Under the influence of continuous heat leakage, the cryogenic propellant in the cryogenic propellant storage tank 1 heats up and part of the liquid evaporates into gas, causing the pressure in the storage tank to increase. Therefore, the present invention adopts a thermodynamic exhaust method of periodic sweep injection, which adopts the above-mentioned thermodynamic exhaust system, including the following steps:

[0035] S1: When the pressure in the cryogenic propellant storage tank 1 rises to the upper limit, the circulation pump 5 is started to pump out the cryogenic propellant liquid in the storage tank. After passing through the circulation pump 5, the cryogenic propellant liquid is divided into two paths at the c end, namely, the main flow pipeline 6 and the branch flow pipeline 7. The main flow is sent to the hot layer inlet f end of the concentric multilayer heat exchanger 2, and the branch flow is sent to the cold layer inlet d end of the concentric multilayer heat exchanger 2 after throttling, reducing pressure and temperature through the throttle valve 8. Then, the branch flow reaches the cold layer outlet e end and is discharged into the vacuum environment;

[0036] S2: After entering the hot layer 21, the main fluid will exchange heat with the branch fluid of the cold layer 22, and after reaching the outlet g of the hot layer 21, it will enter the spray layer 23, where it will exchange heat with the branch fluid of the cold layer 22 to cool down, thus achieving full utilization of cold energy;

[0037] S3: Then the main fluid enters the fluid oscillator 3 at the outlet h of the spray layer 23. Due to the Coanda effect in the fluid oscillator 3, it finally presents a periodic sweeping jet flow state at the outlet i of the fluid oscillator and is sprayed into the cryogenic propellant tank 1. The periodic sweeping jet in the vertical direction can strongly disturb the flow field of the cryogenic propellant fluid, enhance the heat and mass transfer capacity of the fluid in the tank, destroy the thermal stratification phenomenon in the cryogenic propellant tank 1, and achieve a rapid reduction in the pressure of the cryogenic propellant.

[0038] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A thermodynamic exhaust system using periodic sweep injection, comprising a cryogenic propellant storage tank (1), characterized in that: The cryogenic propellant storage tank (1) is provided with a concentric multi-layer heat exchanger (2), which includes a hot layer (21), a cold layer (22) and a spray layer (23) in order from the inside to the outside. A fluid oscillator (3) is provided at the orifice of the spray layer (23), and the fluid oscillator (3) performs periodic sweeping spraying of the fluid in the tank, so that the fluid in the cold layer (22) cools the fluid in the hot layer (21) and the fluid in the spray layer (23), thereby fully utilizing the cold energy.

2. A thermodynamic exhaust system using periodic sweep injection as claimed in claim 1, characterized in that: It also includes a liquid pipeline (4) connected to the bottom of the cryogenic propellant storage tank (1), the liquid pipeline (4) is connected to a circulation pump (5), the outlet of the circulation pump (5) is connected to a main pipeline (6) and a branch pipeline (7), the main pipeline (6) is connected to an inlet of a hot layer (21), and the branch pipeline (7) is connected to an inlet of a cold layer (22).

3. A thermodynamic exhaust system using periodic sweep injection as claimed in claim 2, characterized in that: The outlet of the heat layer (21) is connected to the spray layer (23), the liquid in the heat layer (21) moves from bottom to top, and the liquid in the spray layer (23) flows from bottom to bottom toward the fluid oscillator (3).

4. A thermodynamic exhaust system using periodic sweep injection as claimed in claim 2, characterized in that: The branch pipeline (7) is provided with a throttle valve (8), which is connected to the inlet of the cold layer (22) through the throttle valve (8), and the top of the cold layer (22) is connected to the exhaust pipe (9).

5. A thermodynamic exhaust system using periodic sweep injection as claimed in claim 4, characterized in that: The exhaust pipe (9) is in communication with the vacuum environment.

6. A thermodynamic exhaust system using periodic sweep injection as claimed in claim 1, characterized in that: The fluid oscillator (3) is a Coanda swept fluid oscillator, which ejects a low-temperature fluid to exchange heat with a high-temperature fluid in the cryogenic propellant storage tank (1), thereby reducing the fluid temperature and tank pressure in the cryogenic propellant storage tank (1).

7. A thermodynamic exhaust system using periodic sweep injection as claimed in claim 6, characterized in that: The fluid oscillators (3) in each column are distributed at equal intervals, and the fluid oscillators (3) in two adjacent columns are distributed in an alternating manner.

8. A thermodynamic exhaust system using periodic sweep injection as claimed in claim 7, characterized in that: The interval between two adjacent fluid oscillators (3) in each column is 60 mm, and the height difference between each fluid oscillator (3) and the adjacent fluid oscillator (3) in the adjacent column is 30 mm.

9. A thermodynamic exhaust system using periodic sweep injection as claimed in claim 6, characterized in that: The distance between each fluid oscillator (3) and the center of the thermal layer (21) is equal to the distance between two adjacent fluid oscillators (3) in each column.

10. A thermodynamic exhaust method using periodic sweep injection, using the thermodynamic exhaust system according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: When the pressure in the cryogenic propellant storage tank (1) rises to the upper limit, the circulation pump (5) is started to pump out the cryogenic propellant liquid in the storage tank. After passing through the circulation pump (5), the liquid is divided into two paths: a main flow pipeline (6) and a branch flow pipeline (7). The main flow is sent to the hot layer (21) of the concentric multi-layer heat exchanger (2). The branch flow is sent to the cold layer (22) of the concentric multi-layer heat exchanger (2) after throttling, reducing pressure and temperature through the throttle valve (8). The branch flow then reaches the cold layer outlet (22) and is discharged into a vacuum environment. S2: After the main fluid enters the hot layer (21), it exchanges heat with the branch fluid of the cold layer (22), and after reaching the outlet of the hot layer (21), it enters the spray layer (23), and exchanges heat with the branch fluid of the cold layer (22) in the spray layer (23) to cool down, thereby achieving full utilization of cold energy; S3: The main fluid then enters the fluid oscillator (3) at the outlet of the spray layer (23). Due to the Coanda effect in the fluid oscillator (3), the main fluid eventually presents a periodic sweep jet flow pattern at the outlet of the fluid oscillator and is sprayed into the cryogenic propellant storage tank (1). The periodic sweep jet in the vertical direction can strongly disturb the flow field of the cryogenic propellant fluid, enhance the heat and mass transfer capacity of the fluid in the storage tank, destroy the thermal stratification phenomenon in the cryogenic propellant storage tank (1), and achieve a rapid reduction in the pressure of the cryogenic propellant.

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