Pressure matching design method for evaporation / sublimation system

Abstract

The invention discloses a pressure matching design method for an evaporation / sublimation system. The method comprises the following steps: determining a target heat dissipating capacity range [Qmin, i, Qmax, i] and a stable working pressure range [Psmin, i, Psmax, i]; the pressure adjusting range [Prmin, i, Prmax, i] of the pressure adjusting device is determined; determining an input pressure range [Pvmin, i, Pvmax, i] of the storage tank; according to the gas side pressure change range [Pvgmin, i, Pvgmax, i] of the water sublimation heat dissipation system, the gas side volume Vg0 of the working medium storage box and the gas side filling pressure Pg0 when the liquid side is filled with the working medium are adjusted; the theoretical working medium pressure Pf, i of the liquid working medium inlet position is obtained; when Pf, i belongs to [Prmin, i, Prmax, i] + / -1kPa, judging that the layout is reasonable; obtaining the reading Pfs, i of a pressure sensor at the inlet of the water sublimation heat dissipation device; when Pr, i and P'f, i are reversely deduced according to Pfs, i, when Pr, i belongs to [Prmin, i, Prmax, i] and P'f, i belongs to [Prmin, i, Prmax, i], it is judged that the layout is reasonable, and otherwise, the layout is adjusted. The system pressure matching design concept and the key parameter matching method are given, it is guaranteed that the water sublimation system is reliably applied to space tasks, and it is guaranteed that the water sublimation system stably operates in ground testing, in-orbit microgravity environment and lunar gravity environment.

Description

Technical Field

[0001] This invention belongs to the field of spacecraft thermal control technology and relates to a pressure matching design method for an evaporation / sublimation system. Background Technology

[0002] A water sublimation device is a thermal control system that dissipates heat from spacecraft by releasing a consumable medium into space. Utilizing the high vacuum environment of the spacecraft, the working medium, water, first freezes, then sublimates directly into water vapor and is released into outer space, thus removing waste heat from the spacecraft's thermal control system. Water sublimation devices are characterized by their simple structure, small size, and light weight, making them ideal auxiliary cooling devices for spacecraft with short-term high power consumption or operating environments with high temperatures. Water sublimation devices have been successfully applied multiple times in the thermal control systems of foreign spacecraft and extravehicular activity unit (EMU) life support systems (PLSS). With the gradual development of my country's lunar exploration and deep space exploration missions, water sublimation cooling technology has become one of the essential and necessary thermal control methods for my country's spacecraft. my country's independently developed water sublimation system has been applied to my country's deep space exploration missions, ensuring the successful implementation of the lunar sample return mission.

[0003] The water sublimation heat dissipation system utilizes the evaporation and sublimation of water in a vacuum environment to remove waste heat from the spacecraft. The water sublimation heat sink is the component in the system that performs the heat dissipation function. Its working principle is to achieve heat dissipation by controlling the stable evaporation-sublimation phase change of the liquid working fluid within a core component composed of porous media. The liquid working fluid is stored in the tank of the water sublimation heat dissipation system and distributed to various branches of the system under certain pressure and through specific components. Finally, it is evaporated and sublimated by the water sublimation heat sink and discharged into the vacuum environment where the spacecraft operates. This means that the water sublimation heat dissipation system operates as an open system. During the process of the liquid working fluid changing phase from the tank to a gas and being discharged into the vacuum environment through the water sublimation heat sink, the system's working fluid pressure needs to be stably reduced from the initial pressure of the tank to the vacuum environment pressure of the spacecraft. To achieve the corresponding temperature control functions and ensure the heat dissipation capacity and stable operation of the water sublimation heat sink, a matching working fluid delivery and distribution chain is necessary, along with reasonable fluid distribution and pressure control. This ensures that the pressure and fluid distribution of each branch of the sublimation heat dissipation system meet requirements under different gravity environments. This guarantees stable operation of the sublimation heat dissipation device, preventing uncontrolled leakage of the liquid working fluid into the vacuum environment through the porous structure of the device, and avoiding differences in heat transfer performance between different branches due to uneven flow distribution, or discrepancies between the actual system pressure and the sensor-displayed pressure caused by layout issues, which could lead to misjudgments of the operating status or control deviations. However, publicly available literature, both domestic and international, rarely mentions fluid distribution, pressure control methods, or system pressure matching design methods for sublimation heat dissipation systems. Summary of the Invention

[0004] The purpose of this invention is to overcome the aforementioned deficiencies and provide a pressure matching design method for evaporation / sublimation systems, solving the technical problems of fluid distribution, pressure control, and system pressure matching in water sublimation heat dissipation systems. This invention proposes a pressure matching design method for water sublimation systems in microgravity and gravity environments, providing the system pressure matching design concept and key parameter matching methods to ensure the reliable application of water sublimation systems in space missions and to ensure stable operation of water sublimation systems in ground testing, on-orbit microgravity environments, and lunar gravity environments.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A pressure matching design method for an evaporation / sublimation system includes:

[0007] S1 determines the target heat dissipation range of the water sublimation device [Q] min,i Q max,i And the pressure range for stable operation under the current pipeline layout [P] smin,i ,P smax,i ];

[0008] S2 is based on the target heat dissipation range of the water sublimation device [Q] min,i Q max,i and the pressure range for stable operation [P] smin,i ,P smax,i Determine the pressure regulation range of the branch pressure regulating device [P] rmin,i ,P rmax,i ];

[0009] S3 adjusts according to the pressure range of the branch pressure regulating device [P] rmin,i ,P rmax,i Determine the input pressure range of the pressure regulating device [P] vmin,i ,P vmax,i ];

[0010] S4 is based on the operating time t of the water sublimation device. i and target heat dissipation range [Q] min,i Q max,i Determine the required amount of liquid working fluid, m; determine the liquid storage tank volume, V0, based on the required amount of liquid working fluid, m.

[0011] The gas-side volume V of the working fluid storage tank is set according to the liquid volume V0 of the storage tank. g0 The working fluid filling temperature T0 and the gas-side filling pressure P when the liquid is filled with the working fluid. g0 According to V g0 T0 and P g0 Calculate the range of air-side pressure variation [P]vgmin,i ,P vgmax,i ];

[0012] when Adjust the gas-side volume V of the working fluid storage tank g0 The gas-side filling pressure P when the liquid is filled with the working fluid g0 Recalculate the range of air-side pressure variation [P] vgmin,i ,P vgmax,i ], until [P vgmin,i ,P vgmax,i ]∈[P vmin,i ,P vmax,i ];

[0013] S5 obtains the theoretical working fluid pressure P at the liquid working fluid inlet location of the water sublimation heat dissipation device. f,i ;

[0014] When P f,i ∈[P rmin,i ,P rmax,i If the pressure is ±1 kPa, the current pipeline layout is determined to be reasonable, and the process proceeds to step S6; otherwise, the process returns to step S2 to adjust the pipeline layout.

[0015] S6 acquires the reading P from the pressure sensor located at the inlet of the sublimation heat sink. fs,i ;

[0016] When P fs,i ∈[P rmin,i ,P rmax,i If the current pipeline layout is deemed reasonable, then it can be determined that the current pipeline layout is reasonable.

[0017] when According to P fs,i Pressure P at the outlet position of the reverse pressure regulating device r,i Pressure P' at the inlet of the water sublimation heat dissipation device f,i When P r,i ∈[P rmin,i ,P rmax,i And P' f,i ∈[P rmin,i ,P rmax,i If the current pipeline layout is deemed reasonable, then return to step S1 to adjust the pipeline layout.

[0018] Furthermore, in step S1, based on the maximum pore size r of the porous plate in the water sublimation system... i Thickness d i Permeability coefficient K i Porosity ε i And the layout of the liquid supply pipeline determines the pressure range for stable operation of the water sublimation unit [P] smin,i ,P smax,i ].

[0019] Furthermore, in step S2, based on the target heat dissipation range [Q] of the water sublimation device... min,i Q max,i and the pressure range for stable operation [P] smin,i ,P smax,i Determine the pressure regulation range of the branch pressure regulating device [P] rmin,i ,P rmax,i The methods include:

[0020] Heat dissipation Q of each branch i Pressure P of the branch pressure regulating device r,i The following relationship must be satisfied:

[0021] Q i =α i P r,i , where α i For r i K i ε i Correlation coefficient; Q i ∈[Q min,i Q max,i ];

[0022] and,

[0023] [P rmin,i ,P rmax,i ]∈[P smin,i ,P smax,i ].

[0024] Furthermore, in step S4, based on the operating time t of the water sublimation device... i and target heat dissipation range [Q] min,i Q max,i Methods for determining the required quantity m of the liquid working fluid include:

[0025]

[0026] Among them, Q i h represents the heat dissipation of each branch. e Let N be the latent heat of vaporization of the liquid working fluid, N be the number of branches in the water sublimation system, and i represent the branch number, i = 1, 2, ..., N;

[0027] Methods for determining the liquid storage tank volume V0 based on the required liquid working fluid m include:

[0028] V0 = m / ρ0;

[0029] Where ρ0 is the density of the liquid working medium in the tank at the filling temperature.

[0030] Furthermore, in step S4, according to V g0T0 and P g0 The range of gas-side pressure variation in the evaporation / sublimation heat dissipation system was calculated using the Clapeyron ideal gas law [P]. vgmin,i ,P vgmax,i Specifically:

[0031] P vg =P g0 V g0 T g / (V g T g0 );

[0032] Among them, P vg P is the gas-side pressure. vg ∈[P vgmin,i ,P vgmax,i ], T g V is the gas-side temperature of the tank storing the working fluid. g T is the gas-side volume of the tank storing the working fluid. g0 The initial gas-side temperature of the tank storing the working fluid.

[0033] Furthermore, in step S4, when or P vg ≥P c Adjust the gas-side volume V of the working fluid storage tank. g0 The gas-side filling pressure P when the liquid is filled with the working fluid g0 Recalculate the range of air-side pressure variation [P] vgmin,i ,P vgmax,i ], until [P vgmin,i ,P vgmax,i ]∈[P vmin,i ,P vmax,i ]; P c This refers to the allowable pressure of the tank shell material.

[0034] Furthermore, in step S5, P f,i It is calculated based on the output pressure of the pressure regulating device and the pressure and pressure drop generated by the pipeline layout.

[0035] Furthermore, in step S6, according to P fs,i Pressure P at the outlet position of the reverse pressure regulating device r,i Pressure P' at the inlet of the water sublimation heat dissipation device f,i The methods include:

[0036] P r,i =P fs,i +ΔP 2f,i -ΔP 2,i ;

[0037] P' f,i =P r,i-ΔP 1f,i +ΔP 1,i ;

[0038] Wherein, ΔP 1,i ΔP is the additional pressure increase or decrease from the outlet of the pressure regulating device to the inlet of the water sublimation heat dissipation device caused by the difference in pipe height. 1f,i ΔP is the flow resistance of the pipe from the outlet of the pressure regulating device to the inlet of the water sublimation heat dissipation device. 2,i ΔP is the additional pressure rise or fall of the pressure sensor element from the outlet of the pressure regulator to the inlet of the liquid working fluid in the sublimation heat exchanger caused by the piping layout. 2f,i The flow resistance of the pipeline from the outlet of the pressure regulating device to the inlet of the liquid working medium of the water sublimation heat dissipation device.

[0039] Furthermore, the pipeline layout includes the arrangement of pressure regulating devices, pressure sensors, and water sublimation heat exchange devices in each branch of the evaporation / sublimation system along the direction of gravity.

[0040] Furthermore, the pressure range for stable operation of the water sublimation unit is calculated according to the following formula:

[0041]

[0042] Among them, P s,i For the water sublimation unit to operate stably, P sat,i P is the saturated vapor pressure corresponding to the working temperature of the liquid working fluid. env For the operating environment pressure of the water sublimation cooling system, P fw,i For the water sublimation heat dissipation device, the water supply pressure, A r,i Where μ is the evaporative heat dissipation area, and μ is the dynamic viscosity of the liquid working fluid. Let ρ be the mass flow rate of the working fluid evaporation, ρ be the density of the liquid working fluid, σ be the surface tension of the liquid working fluid, and θ be the mass flow rate of the working fluid evaporation. i K represents the contact angle between the liquid working fluid and the porous plate. i Let d be the permeability coefficient of the porous plate. i r is the thickness of the perforated plate. i This represents the maximum aperture of the perforated plate.

[0043] Compared with the prior art, the present invention has at least one of the following advantages:

[0044] (1) The present invention matches the pressure of the water sublimation heat dissipation system through a three-level design, so that the water sublimation heat dissipation system can reasonably control the pressure and fluid distribution of the entire system and each branch during the entire life cycle of the water sublimation heat dissipation system, such as ground testing and lunar operation, thereby achieving stable operation of the system;

[0045] (2) This invention meets the needs of parameter design and system layout design in the development of water sublimation heat dissipation system, and provides essential technical support for the development of water sublimation heat dissipation system.

[0046] (3) The pressure matching design method of water sublimation system in microgravity and gravity environment adopted in this invention provides the necessary technical guarantee for solving the application of water sublimation system in spacecraft, and the test and application under multiple force fields on the ground and in orbit. Attached Figure Description

[0047] Figure 1 The following are the design and implementation steps for the pressure matching of the water sublimation system of this invention;

[0048] Figure 2 This is a schematic diagram of the water sublimation system of the present invention. Detailed Implementation

[0049] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0050] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0051] This invention proposes a pressure matching design method for evaporation / sublimation systems applicable to microgravity and gravity environments. This method enables reasonable fluid distribution and pressure control throughout the entire life cycle of the water sublimation system, ensuring that the pressure and fluid distribution of the entire system and its individual branches meet requirements when the water sublimation heat dissipation system operates under different gravity environments, such as ground testing and lunar surface operation. This provides essential technical support for the development, testing, and application of water sublimators.

[0052] The water sublimation cooling system comprises a liquid working fluid tank and various cooling branches connected to the tank via liquid pipelines. There can be one or more cooling branches. For water sublimation systems with multiple branches, each parameter is indicated by the subscript i, where i = 1, 2, ..., N, and N is the number of branches. The tank consists of a liquid chamber and a gas chamber. The liquid chamber is used to fill the liquid working fluid required for the water sublimation system to operate, and the gas chamber is used to store the gaseous working fluid compressed at a certain pressure. Each branch is connected to the liquid chamber of the tank via liquid pipelines. Each branch includes pressure regulating elements (pressure regulating devices), pressure monitoring devices (pressure sensors), fluid distribution elements, and water sublimation cooling devices that can evaporate / sublimate the liquid working fluid to a vacuum environment, valves, etc., all connected in series via liquid pipelines. When a valve in a branch is opened, the liquid working fluid in the tank is released under the pressure of the gas chamber, ultimately evaporating / sublimating in the water sublimation cooling device and transforming into gas, which is then discharged into the external vacuum environment.

[0053] This invention provides a pressure matching design method for a water sublimation system applicable to microgravity and gravity environments. Its main purpose is to match the pressure of the water sublimation heat dissipation system through a three-level design, so that the pressure and fluid distribution of the entire system and its branches can be reasonably controlled during the entire life cycle operation of the water sublimation heat dissipation system, such as ground testing and lunar surface operation, thereby achieving stable system operation. The three levels of factors considered in the pressure matching design of the water sublimation heat dissipation system are: (1) Matching the full-cycle working pressure of the sublimator tank and the input and output pressures of the pressure regulating devices of each branch of the water sublimation system. Its basic requirement is: as the working mass and temperature of the tank liquid chamber change, the maximum value of the gas pressure in the gas chamber of the sublimator tank (P) vmax ) and minimum value (P) vmin All pressures should be matched with the upstream input pressure of each branch pressure regulating device to ensure the output pressure (P) of the pressure regulating device. r,i (1) Design; (2) Matching the output pressure of each branch pressure regulating device of the water sublimation system with the stable working pressure of the water sublimation heat dissipation device. The basic requirement is: based on the heat dissipation capacity (Q) of the water sublimation heat dissipation device. i Demand, stable operating pressure range of water sublimation heat dissipation device P s,i P s,i ∈P smin,i ,P smax,i Determine the output pressure (P) of the matching pressure regulator. r,i(3) The layout of the pressure regulating device and pressure detection device of the water sublimation system in gravity / microgravity / lunar gravity environments should be matched with the system pressure. The space water sublimation heat dissipation system needs to operate in the microgravity environment of space and the gravity environment of the lunar surface, and needs to be tested and verified on the ground. In the gravity environment, the actual pressure of each branch and the measured pressure displayed by the pressure sensor will be different due to the different pipeline layout. Since the stable operation and heat dissipation of the water sublimation heat dissipation device are sensitive to pressure, the design should ensure that the heat exchange performance of each branch is not different due to uneven pressure, or that the pressure displayed by the sensor is inconsistent with the actual pressure of the system, which will lead to deviation in the control of the water sublimation heat exchange device. Based on the above analysis, the design process for matching the pressure of the water sublimation system is as follows. Figure 1 It mainly includes the following steps:

[0054] (1) Determine the maximum pore size r of the porous medium in the water sublimation heat dissipation device. i Permeability coefficient K i Thickness d i Parameters such as Q are used to determine the target heat dissipation range of the water sublimation heat dissipation device design. i ∈[Q min,i Q max,i ];

[0055] (2) Based on the maximum aperture r of the perforated plate of the water sublimation heat dissipation device i Thickness d i Permeability coefficient K i Porosity ε i The layout of the liquid supply pipeline, etc., determines the stable operating pressure range P of the water sublimation heat dissipation device. s,i P s,i ∈[P smin,i ,P smax,i The internal flow resistance ΔP of the water sublimation heat dissipation device i The flow resistance ΔP of the liquid supply pipeline in the branch is f,i ;

[0056] (3) According to the heat dissipation range Q of the water sublimation heat dissipation device i Determine the pressure regulation range P of the branch pressure regulating device. r,i ∈[P rmin,i ,P rmax,i Its pressure range should meet [P] rmin,i ,P rmax,i ]∈[P smin,i ,P smax,i The heat dissipation Q of the water sublimation heat dissipation device. i It is related to its parameter design and water supply pressure, and can be expressed as Q. i =f(Pr,i ,r i ,K i ,ε i Given that the design parameters of the water sublimation heat dissipation device are fixed, Q i With P r,i The relationship between them Q i =α i P r,i It can be determined by the specific design of the water sublimation heat dissipation device;

[0057] (4) According to the pressure adjustment range P of the pressure regulating device r,i Required input pressure range P v,i ∈[P vmin,i ,P vmax,i ], where P r,i The required input pressure range is determined by the specific design of the pressure regulating device. Simultaneously, the minimum design dimensions of the core pressure regulating element of the branch pressure regulating device must be determined based on constraints such as system volume and weight, to optimize the volume and weight of the branch pressure regulating device.

[0058] (5) Based on the working time t of the water sublimation heat dissipation device i and heat dissipation power Q i Assess its liquid working fluid requirements Where h e The latent heat of vaporization of the liquid working fluid is given; the liquid volume of the working fluid tank is then determined, denoted as V0, where V0 = m / ρ0, and ρ0 is the density of the liquid working fluid in the tank at the filling temperature; the total volume V and the gas-side volume V of the working fluid tank are then defined. g0 The working fluid filling temperature T0 and the gas-side filling pressure P when the liquid is filled with the working fluid. g0 Calculate the range of air-side pressure change P based on the range of air-side volume change before and after use. vg ∈[P vgmin ,P vgmax ], where V = V0 + V g0 When the gas side is filled with ultrapure gas working fluid, it can be based on P g0 T g0 V g0 In addition, the changes in gas and liquid volumes due to the consumption of the liquid working fluid are assessed using the Clapeyron ideal gas law to evaluate the gas-side pressure changes throughout the entire lifecycle of the water sublimation cooling system. Determine its maximum range of variation [P] vgmin ,P vgmax ].if Then adjust the tank volume and the gas-side filling pressure P. g0 , so that [P vgmin ,P vgmax ]∈P vmin ,Pvmax ], and P vg <Permissible pressure range P of tank shell material> c This range is determined by factors such as the material strength, thickness, and design of the storage tank.

[0059] (6) Determine the impact of the system piping and component layout on the output pressure of the pressure regulating device and the inlet pressure of the water sublimation unit under gravity, microgravity, and lunar gravity environments. Under the current layout, the theoretical working fluid pressure at the liquid working fluid inlet of the water sublimation heat dissipation device is denoted as P, under the combined effects of gravity, the gas working fluid pressure in the working fluid tank of the water sublimation system, and the pressure regulating device. f,i P f,i =P r,i -ΔP 1f,i +ΔP 1,i ΔP 1,i ΔP is the additional pressure increase or decrease from the pressure regulator to the inlet of the sublimation heat sink caused by the difference in pipe height. 1,i =ρgh 1,i ΔP 1f,i For the flow resistance of the pipeline, if P f,i ∈[P rmin,i ,P rmax,i If the pipeline layout is reasonable, it can meet the system pressure matching requirements;

[0060] (7) The reading of the pressure sensor located at the inlet of the water sublimation heat dissipation device is denoted as P. fs,i P fs,i =P r,i -ΔP 2f,i +ΔP 2,i ΔP 2,i ΔP is the additional pressure rise or fall caused by the piping layout, from the pressure regulator outlet to the liquid working fluid inlet of the sublimator. 2,i =ρgh 2,i ΔP 2f,i This refers to the flow resistance in the pipeline. The purpose of installing a pressure sensor within the sublimation cooling system is to monitor the supply pressure at the inlet of the sublimation cooling device, used to determine whether the output pressure of the pressure regulating device is normal. If P... fs,i ∈[P rmin,i ,P rmax,i If the output pressure of the pressure regulator is normal, then it can be determined that the output pressure is normal; otherwise, it can be determined that the output pressure of the pressure regulator is abnormal. This is because the water sublimation cooling device P... f,i P fs,i All are affected by system layout and gravity. For water sublimation heat dissipation systems with multiple liquid supply branches, the height difference of the pressure regulating device, pressure sensor, and water sublimation heat exchanger along the direction of gravity will cause a gravitational effect on P. fi P fsiThe effects are not consistent, and their differences between lunar and terrestrial gravity environments also vary. If the pressure sensor of the i-th branch shows its predicted reading in either a terrestrial or lunar gravity environment... It needs to be based on P r,i =P fs,i -ΔP 2f,i +ΔP 2,i Pressure P at the outlet position of the reverse pressure regulating device r,i And the pressure P at the inlet of the sublimation heat dissipation device. f,i If P r,i ∈[P rmin,i ,P rmax,i ]、P f,i ∈[P rmin,i ,P rmax,i If the actual liquid supply pressure at the inlet of the water sublimation heat dissipation device meets the requirements, then there is no need to optimize the layout design. Otherwise, return to step (2) to optimize the system layout design until the pressure matching conditions are met.

[0061] In summary, based on the system design, the pressure range of the water sublimation reactor inlet throughout the entire working cycle was verified under gravity, microgravity, and lunar gravity environments. Specifically, when designing the pressure matching for the water sublimation system, the following design criteria were used: matching the working fluid pressure at the beginning and end of the first-stage sublimation reactor tank with the input and output pressures of the pressure regulating devices in each branch of the water sublimation system; matching the output pressure of each branch pressure regulating device in the second-stage water sublimation system with the stable working pressure of the water sublimation heat dissipation device; and matching the layout of the pressure regulating and pressure detection devices in the third-stage water sublimation system under gravity / microgravity / lunar gravity environments with the system pressure matching design criteria. These are summarized as follows:

[0062]

[0063] When performing design calculations for lunar gravity and other gravitational environments, the value of g in the formula can be converted to the value under the corresponding gravitational field.

[0064] in, P sat,i P is the saturated vapor pressure corresponding to the working temperature of the liquid working fluid. env For the operating environment pressure of the water sublimation cooling system, A r,i Where μ is the evaporative heat dissipation area, and μ is the dynamic viscosity of the liquid working fluid. Let ρ be the mass flow rate of the working fluid evaporation, ρ be the density of the liquid working fluid, σ be the surface tension of the liquid working fluid, and θ be the mass flow rate of the working fluid evaporation. i The contact angle between the liquid working fluid and the porous plate, ΔP i ΔP f,i ΔP 1f,i ΔP 2f,i ΔP 1,i and ΔP2,i The calculations can be performed using fluid dynamics methods based on the actual design, which will not be elaborated here.

[0065] Example:

[0066] like Figure 2 In practical applications, water sublimation cooling systems may contain more branches. For Figure 2 The example shows a water sublimation system with two branches, where parameters are indicated by subscripts i = 1, 2. In this example, the design, heat dissipation performance, stable operating pressure, and internal flow resistance of the water sublimation cooling devices in both branches are assumed to be identical, i.e., Q1 = Q2, P s,1 =P s,2 ΔP1 = ΔP2, and their subscripts are omitted in the following text;

[0067] (1) Design a water sublimation heat dissipation device and determine that its target heat dissipation range is Q∈[180,350]W;

[0068] (2) Determine the stable operating pressure range P of the water sublimation heat dissipation device s P s ∈[8,22]±1kPa and the internal flow resistance ΔP≈2kPa of the water sublimation heat dissipation device, and the flow resistance ΔP of the liquid supply pipeline of the branch where it is located. f,1 ≈0.6kPa, ΔP f,2 ≈0.5kPa;

[0069] (3) Determine the pressure regulation range P of the branch pressure regulating device based on the heat dissipation range Q of the water sublimation heat dissipation device. r ∈[11,20]±1kPa, its pressure range satisfies [P rmin ,P rmax ]∈[P smin ,P smax The heat dissipation Q of a water sublimation heat dissipation device is related to its parameter design and water supply pressure, and can be expressed as Q = f(P). r In this case, the design parameters of the water sublimation heat dissipation device are determined by the specific design and measurement of the water sublimation heat dissipation device, and Q and P are... r The correlation between them is approximately Q≈17.6P. r ;

[0070] (4) According to the pressure adjustment range P of the pressure regulating device r Determine the required input pressure range P v ∈[100,300]±5kPa, P rThe required input pressure range is determined by the specific design of the pressure regulating device. Simultaneously, the minimum design dimensions of the core pressure regulating element of the branch pressure regulating device must be determined based on system volume and weight constraints to ensure that the volume and weight of the branch pressure regulating device meet the system's volume and weight constraints.

[0071] (5) Based on the working time t of the sublimation heat dissipation device of each branch. i The rated heat dissipation power Q is used to assess its liquid working fluid requirement of 8 kg. Where h e The latent heat of vaporization of the liquid working fluid is 2500 kJ / kg; therefore, the liquid volume V0 of the working fluid tank is determined to be 8 L, and the density ρ0 of the liquid working fluid in the tank at the filling temperature is 0.998 kg / m³. 3 ;

[0072] (6) Set the total volume of the working fluid storage tank V = 18L and the gas-side volume V g0 =10L, working fluid filling temperature T0 = 23℃ and gas-side filling pressure P when the liquid side is full of working fluid. g0 =290±5kPa, calculate the range of air-side pressure change P based on the range of air-side volume change before and after use. vg ∈[140,298]±5kPa, where V=V0+V g0 When the gas side is filled with ultrapure gas working fluid, it can be based on P g0 T g0 V g0 In addition, considering the changes in gas and liquid volumes due to the consumption of the liquid working fluid, the pressure change on the gas side of the water sublimation cooling system throughout its entire application cycle is evaluated using the Clapeyron ideal gas law. vg =P g0 V g0 T g / (V g T g0 ), determine its maximum range of variation [P] vgmin ,P vgmax ].if Then adjust the tank volume and the gas-side filling pressure P. g0 , so that [P vgmin ,P vgmax ]∈P vmin ,P vmax ], and P vg <Permissible pressure range P of tank shell material> c =6.4MPa, this range is determined by the material strength, thickness, and design of the storage tank;

[0073] (7) Determine the impact of the system piping and component layout on the output pressure of the pressure regulating device and the inlet pressure of the water sublimation unit under gravity, microgravity, and lunar gravity environments. Under the current layout, the theoretical working fluid pressure at the liquid working fluid inlet of the water sublimation heat dissipation device is denoted as P, under the combined effects of gravity, the gas working fluid pressure in the working fluid tank of the water sublimation system, and the pressure regulating device. f,i P f,i =P r -ΔP 1f,i +ΔP 1,i ΔP 1,i ΔP is the additional pressure increase or decrease from the pressure regulator to the inlet of the sublimation heat sink caused by the difference in pipe height. 1,i =ρgh 1,i ΔP 1f,i For the flow resistance of the pipeline, if P f,i ∈[P rmin,i ,P rmax,i If the pressure is ±1 kPa, the pipeline layout is reasonable and can meet the system pressure matching requirements. In this case, h 1,1 =0.15m, h 1,2 =0.08m, 11.87kPa <P f,1 <20.87kPa, 11.28kPa <P f,2 <20.28kPa, P f,i ∈[P rmin,i ,P rmax,i ±1 kPa, i = 1, 2; Under lunar gravity, the gravitational acceleration is 1 / 6 of that on Earth. Substitute this into P f,i Under predictable lunar surface conditions, 10.64 kPa <P fm,1 <19.64kPa, 10.63kPa <P fm,2 <19.63kPa, P fm,i ∈[P rmin,i ,P rmax,i The reading of ±1 kPa indicates that the pipeline layout is reasonable.

[0074] (7) The reading of the pressure sensor located at the inlet of the water sublimation heat dissipation device is denoted as P. fs,i P fs,i =P r,i -ΔP 2f,i +ΔP 2,i ΔP 2,i ΔP is the additional pressure rise or fall caused by the piping layout from the pressure regulator outlet to the liquid working fluid inlet of the water sublimator, which is represented by the pressure sensing element (pressure sensor). 2,i =ρgh 2,i ΔP 2f,iThis refers to the flow resistance in the pipeline. The purpose of installing a pressure sensor within the sublimation cooling system is to monitor the supply pressure at the inlet of the sublimation cooling device, used to determine whether the output pressure of the pressure regulating device is normal. If P... fs,i ∈[P rmin ,P rmax If the output pressure of the pressure regulator is normal, then it can be determined that the output pressure is normal; otherwise, it can be determined that the output pressure of the pressure regulator is abnormal. This is because the water sublimation cooling device P... fi P fsi All are affected by system layout and gravity. For water sublimation heat dissipation systems with multiple liquid supply branches, the height difference of the pressure regulating device, pressure sensor, and water sublimation heat exchanger along the direction of gravity will cause a gravitational effect on P. f,i P fs,i The effects are not consistent, and their differences between lunar and terrestrial gravity environments also vary. If the pressure sensor of the i-th branch shows its predicted reading in either a terrestrial or lunar gravity environment... It needs to be based on P r,i =P fs,i -ΔP 2f,i +ΔP 2,i Pressure P at the outlet position of the reverse pressure regulating device r,i And the pressure P at the inlet of the sublimation heat dissipation device. f,i If P r,i ∈[P rmin,i ,P rmax,i ]、P f,i ∈[P rmin,i ,P rmax,i If the actual liquid supply pressure at the inlet of the water sublimation heat dissipation device meets the requirements, then no optimization design of the layout is needed. Otherwise, return to step (2) to optimize the system layout until the pressure matching condition is met. In this case, h 2,1 =0.208m, h 1,2 =0.08m, 12.44kPa <P fs,1 <21.44kPa, 11.28kPa <P fs,2 <20.28kPa, P fs,2 ∈[P rmin,2 ,P rmax,2 ±1kPa, P fs,1 Maximum value range > P rmax,1 ±1 kPa indicates that during ground testing, the pressure sensor reading for branch 1 may exceed the preset maximum water supply pressure of the sublimation cooling device for that branch. Although the actual water supply pressure at the inlet of the sublimation cooling device meets the pressure matching requirements, this situation needs to be confirmed during system operation monitoring to avoid system fault alarms. The P reading in this case... fs,1 Maximum value range > Prmax,1 The ±1 kPa scenario is merely a special case in practical applications. In most practical applications, P can be achieved. fs,i ∈[P rmin,i ,P rmax,i ±1kPa, but it is also possible that the minimum reading of a pressure sensor in a certain branch may occur. <P rmin,i The case of ±1 kPa should be analyzed in detail.

[0075] According to the system design, the pressure range of the water sublimator inlet during the entire working cycle was checked under gravity, microgravity, and lunar gravity environments. That is, when designing the pressure matching of the water sublimation system, the matching design criteria for the working medium pressure at the beginning and end of the first-stage sublimator tank and the input and output pressures of the pressure regulating devices of each branch of the water sublimation system, the matching design criteria for the output pressure of each branch of the second-stage water sublimation system and the stable working pressure of the water sublimation heat dissipation device, and the relationship between the layout of the pressure regulating devices and pressure detection devices of the water sublimation system under gravity / microgravity / lunar gravity environments and the system pressure matching design criteria are summarized as follows: Equation (2):

[0076]

[0077] When performing design calculations for lunar gravity and other gravitational environments, the value of gravitational acceleration g in the formula is converted to the value under the corresponding gravitational field.

[0078] in, P sat P is the saturated vapor pressure corresponding to the working temperature of the liquid working fluid. env For the operating environment pressure of the water sublimation cooling system, A r Where μ is the evaporative heat dissipation area, and μ is the dynamic viscosity of the liquid working fluid. Let ρ be the mass flow rate of the working fluid evaporation, ρ be the density of the liquid working fluid, σ be the surface tension of the liquid working fluid, θ be the contact angle between the liquid working fluid and the porous plate, and ΔP and ΔP' be the contact angles between the liquid working fluid and the porous plate. f ΔP 1f ΔP 2f ΔP1 and ΔP2 can be calculated using fluid dynamics methods based on the actual design, and will not be elaborated here.

[0079] During the Chang'e 5 mission, based on ground test results of the lunar water sublimation cooling system with two branches, due to layout influences, the pressure P of the pressure sensing element at the liquid working fluid inlet of branch 1 of the water sublimation cooling device under ground gravity conditions was determined. fs,1 Compared to the pressure P at the outlet of pressure regulating device 1 in its corresponding branch f,1 Approximately 0.56 kPa; Under lunar gravity, the pressure P of the pressure sensing element at the liquid working fluid inlet of branch 1 of the water sublimation heat dissipation device. fs,1Compared to the pressure P at the outlet of pressure regulating device 1 in its corresponding branch f,1 The pressure is approximately 0.1 kPa. The pressure P of the pressure sensing element at the inlet of the liquid working fluid in branch 2 of the ground gravity water sublimation heat dissipation device is... fs,2 Compared to the pressure P at the outlet of the corresponding branch from the pressure regulating device 2 f,2 Approximately 0.7 kPa; Under lunar gravity, the pressure P of the pressure sensing element at the liquid working fluid inlet of branch 1 of the water sublimation heat dissipation device. fs,1 Compared to the pressure P at the outlet of pressure regulating device 1 in its corresponding branch f,1 The pressure difference is approximately 0.1 kPa, which is within the pressure matching design range.

[0080] During the Chang'e 6 mission, based on ground test results of the lunar sublimation heat dissipation system with two branches, due to layout influences, the pressure P of the pressure sensing element at the liquid working fluid inlet of branch 2 of the sublimation heat dissipation device under ground gravity conditions was determined. fs,2 Compared to the pressure P at the outlet of pressure regulating device 2 in its corresponding branch f,2 The pressure drops by approximately 1.07 kPa, and P appears. fs,2 <P rmin,2 In the case of ±1 kPa, since this is only a change in the pressure sensor reading caused by gravity and layout, it does not affect the actual output pressure of the pressure regulating device and the actual inlet pressure of the water sublimation heat sink, and therefore does not affect the heat dissipation Q of the water sublimation heat sink.

[0081] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0082] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A pressure matching design method for an evaporation / sublimation system, characterized in that, include: S1 determines the target heat dissipation range of the water sublimation device [Q] min,i Q max,i And the pressure range for stable operation under the current pipeline layout [P] smin,i ,P smax,i ]; S2 is based on the target heat dissipation range of the water sublimation device [Q] min,i Q max,i and the pressure range for stable operation [P] smin,i ,P smax,i Determine the pressure regulation range of the branch pressure regulating device [P] rmin,i ,P rmax,i ]; S3 adjusts according to the pressure range of the branch pressure regulating device [P] rmin,i ,P rmax,i Determine the input pressure range of the pressure regulating device [P] vmin,i ,P vmax,i ]; S4 is based on the operating time t of the water sublimation device. i and target heat dissipation range [Q] min,i Q max,i Determine the required amount of liquid working fluid, m; determine the liquid storage tank volume, V0, based on the required amount of liquid working fluid, m. The gas-side volume V of the working fluid storage tank is set according to the liquid volume V0 of the storage tank. g0 The working fluid filling temperature T0 and the gas-side filling pressure P when the liquid is filled with the working fluid. g0 According to V g0 T0 and P g0 Calculate the range of air-side pressure variation [P] vgmin,i ,P vgmax,i ]; when Adjust the gas-side volume V of the working fluid storage tank g0 The gas-side filling pressure P when the liquid is filled with the working fluid g0 Recalculate the range of air-side pressure variation [P] vgmin,i ,P vgmax,i ], until [P vgmin,i ,P vgmax,i ]∈[P vmin,i ,P vmax,i ]; S5 obtains the theoretical working fluid pressure P at the liquid working fluid inlet location of the water sublimation heat dissipation device. f,i ; When P f,i ∈[P rmin,i ,P rmax,i If the pressure is ±1 kPa, the current pipeline layout is determined to be reasonable, and the process proceeds to step S6; otherwise, the process returns to step S2 to adjust the pipeline layout. S6 acquires the reading P from the pressure sensor located at the inlet of the sublimation heat sink. fs,i ; When P fs,i ∈[P rmin,i ,P rmax,i If the current pipeline layout is deemed reasonable, then it can be determined that the current pipeline layout is reasonable. when According to P fs,i Pressure P at the outlet position of the reverse pressure regulating device r,i Pressure P' at the inlet of the water sublimation heat dissipation device f,i When P r,i ∈[P rmin,i ,P rmax,i And P' f,i ∈[P rmin,i ,P rmax,i If the current pipeline layout is deemed reasonable, then return to step S1 to adjust the pipeline layout.

2. The pressure matching design method for an evaporation / sublimation system according to claim 1, characterized in that, In step S1, based on the maximum pore size r of the porous plate in the water sublimation system... i Thickness d i Permeability coefficient K i Porosity ε i And the layout of the liquid supply pipeline determines the pressure range for stable operation of the water sublimation unit [P] smin,i ,P smax,i ].

3. The pressure matching design method for an evaporation / sublimation system according to claim 2, characterized in that, In step S2, based on the target heat dissipation range [Q] of the water sublimation device... min,i Q max,i and the pressure range for stable operation [P] smin,i ,P smax,i Determine the pressure regulation range of the branch pressure regulating device [P] rmin,i ,P rmax,i The methods include: Heat dissipation Q of each branch i Pressure P of the branch pressure regulating device r,i The following relationship must be satisfied: Q i =α i P r,i , where α i For r i K i ε i Correlation coefficient; Q i ∈[Q min,i Q max,i ]; and, [P rmin,i ,P rmax,i ]∈[P smin,i ,P smax,i ]。 4. The pressure matching design method for an evaporation / sublimation system according to claim 3, characterized in that, In step S4, based on the working time t of the water sublimation device... i and target heat dissipation range [Q] min,i Q max,i Methods for determining the required quantity m of the liquid working fluid include: Among them, Q i h represents the heat dissipation of each branch. e Let N be the latent heat of vaporization of the liquid working fluid, N be the number of branches in the water sublimation system, and i represent the branch number, i = 1, 2, ..., N; Methods for determining the liquid storage tank volume V0 based on the required liquid working fluid m include: V0 = m / ρ0; Where ρ0 is the density of the liquid working medium in the tank at the filling temperature.

5. The pressure matching design method for an evaporation / sublimation system according to claim 4, characterized in that, In step S4, according to V g0 T0 and P g0 The range of gas-side pressure variation in the evaporation / sublimation heat dissipation system was calculated using the Clapeyron ideal gas law [P]. vgmin,i ,P vgmax,i Specifically: P vg =P g0 V g0 T g / (V g T g0 ); Among them, P vg P is the gas-side pressure. vg ∈[P vgmin,i ,P vgmax,i ], T g V is the gas-side temperature of the tank storing the working fluid. g T is the gas-side volume of the tank storing the working fluid. g0 The initial gas-side temperature of the tank storing the working fluid.

6. The pressure matching design method for an evaporation / sublimation system according to claim 5, characterized in that, In step S4, when or P vg ≥P c Adjust the gas-side volume V of the working fluid storage tank. g0 The gas-side filling pressure P when the liquid is filled with the working fluid g0 Recalculate the range of air-side pressure variation [P] vgmin,i ,P vgmax,i ], until [P vgmin,i ,P vgmax,i ]∈[P vmin,i ,P vmax,i ]; P c This refers to the allowable pressure of the tank shell material.

7. The pressure matching design method for an evaporation / sublimation system according to claim 1, characterized in that, In step S5, P f,i It is calculated based on the output pressure of the pressure regulating device and the pressure and pressure drop generated by the pipeline layout.

8. The pressure matching design method for an evaporation / sublimation system according to claim 1, characterized in that, In step S6, according to P fs,i Pressure P at the outlet position of the reverse pressure regulating device r,i Pressure P' at the inlet of the water sublimation heat dissipation device f,i The methods include: P r,i =P fs,i +ΔP 2f,i -ΔP 2,i ; P’ f,i =P r,i -ΔP 1f,i +ΔP 1,i ; Wherein, ΔP 1,i ΔP is the additional pressure increase or decrease from the outlet of the pressure regulating device to the inlet of the water sublimation heat dissipation device caused by the difference in pipe height. 1f,i ΔP is the flow resistance of the pipe from the outlet of the pressure regulating device to the inlet of the water sublimation heat dissipation device. 2,i ΔP is the additional pressure rise or fall of the pressure sensor element from the outlet of the pressure regulator to the inlet of the liquid working fluid in the sublimation heat exchanger caused by the piping layout. 2f,i The flow resistance of the pipeline from the outlet of the pressure regulating device to the inlet of the liquid working medium of the water sublimation heat dissipation device.

9. The pressure matching design method for an evaporation / sublimation system according to claim 1, characterized in that, The pipeline layout includes the arrangement of pressure regulating devices, pressure sensors, and water sublimation heat exchangers in each branch of the evaporation / sublimation system along the direction of gravity.

10. The pressure matching design method for an evaporation / sublimation system according to claim 1, characterized in that, The pressure range for stable operation of the water sublimation unit is calculated using the following formula: Among them, P s,i For the water sublimation unit to operate stably, P sat,i P is the saturated vapor pressure corresponding to the working temperature of the liquid working fluid. env For the operating environment pressure of the water sublimation cooling system, P fw,i For the water sublimation heat dissipation device, the water supply pressure, A r,i Where μ is the evaporative heat dissipation area, and μ is the dynamic viscosity of the liquid working fluid. Let ρ be the mass flow rate of the working fluid evaporation, ρ be the density of the liquid working fluid, σ be the surface tension of the liquid working fluid, and θ be the mass flow rate of the working fluid evaporation. i K represents the contact angle between the liquid working fluid and the porous plate. i Let d be the permeability coefficient of the porous plate. i r is the thickness of the perforated plate. i This represents the maximum aperture of the perforated plate.

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