Evaporation / sublimation heat dissipation working parameter prediction and failure criterion acquisition method

Abstract

The invention discloses an evaporation / sublimation heat dissipation working parameter prediction method. The method comprises the following steps: (1) dividing a starting process into three processes; (2) obtaining analytic solutions of the temperature, the heat transfer heat flow and the phase change interface position in the three processes; (3) obtaining changes of the temperature, the heat transfer heat flow and the phase change interface position of the liquid working medium in the evaporation process in the liquid supply cavity along with time, and entering step (4) when conditions are met; (4) obtaining changes of temperature, heat transfer heat flow and phase change interface position along with time when the liquid working medium enters the perforated plate for sublimation, and entering step (5) when conditions are met; and (5) taking data at the end of the previous process as initial values to obtain changes of the temperature, the heat transfer heat flow and the phase change interface position along with time in the process that the liquid working medium enters the perforated plate for evaporation, and entering the step (4) when conditions are met. According to the invention, necessary technical guarantee is provided for mastering the working characteristics of the evaporation / sublimation heat dissipation device and carrying out evaporation / sublimation heat dissipation development and failure judgment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of spacecraft thermal control, and relates to an evaporation / sublimation heat dissipation working parameter prediction and failure criterion acquisition method. BACKGROUND

[0002] Evaporation / sublimation heat dissipation is a kind of thermal control device for dissipating heat of a spacecraft by discharging consumable medium into space. The device can make the working medium freeze first and then sublimate directly into steam to be discharged into outer space, so as to take away the waste heat of the spacecraft and realize heat dissipation of the spacecraft thermal control system. The evaporation / sublimation heat dissipation is an ideal auxiliary heat dissipation device for a spacecraft with short-time high power consumption or a high working environment temperature. The evaporation / sublimation heat dissipation has been successfully applied to the thermal control of spacecraft thermal control systems and extravehicular activity unit (EMU) life support systems (PLSS) abroad.

[0003] The liquid with high latent heat of phase change such as water is used as the evaporation / sublimation working medium to obtain good heat dissipation effect, which is an effective way to solve the problem that the spacecraft in the field of deep space exploration cannot dissipate heat through traditional radiation. Although the evaporation / sublimation heat dissipation has been successfully applied in engineering practice many times, the evaporation / sublimation heat dissipation device operates in a vacuum environment, and the working medium has multiple phase change states during the operation of the evaporation / sublimation heat dissipation device, and the phase change occurs in a micro-nano porous medium. It is difficult to study the internal transient working process of the evaporation / sublimation heat dissipation through observation and measurement means, and there is currently a lack of effective test methods to obtain the micro process and parameters of the evaporation / sublimation heat dissipation operation. Therefore, the existing evaporation / sublimation heat dissipation research process mostly focuses on the heat dissipation capacity and the macro parameters in operation, and it is difficult to predict the failure. SUMMARY

[0004] The application aims to provide an evaporation / sublimation heat dissipation working parameter prediction and failure criterion acquisition method, and solve the technical problems that the transient characteristics of the micro phase change working process of the evaporation / sublimation heat dissipation and the failure criterion cannot be obtained by using the existing method and cannot be predicted by using experimental means. The application provides a transient modeling and analytical solution method for the starting process of the evaporation / sublimation heat dissipation, which provides necessary technical support for mastering the working characteristics of the evaporation / sublimation heat dissipation, developing the evaporation / sublimation heat dissipation device and judging the failure.

[0005] To achieve the above application purposes, the application provides the following technical scheme.

[0006] The application provides an evaporation / sublimation heat dissipation working parameter prediction and failure criterion acquisition method, and mainly comprises the following contents: theoretical analysis is carried out on the gas-liquid / gas-solid-liquid phase change heat and mass transfer problem in the porous medium under vacuum condition in the evaporation / sublimation heat dissipation starting process, a phase change heat and mass transfer mathematical model and a definite condition in the porous medium are established, an analytical solution of the one-dimensional gas-liquid / gas-solid-liquid phase change heat and mass transfer problem in the porous medium in different working processes of the evaporation / sublimation heat dissipation is derived by using gradient transformation, analysis is carried out based on the constraint condition of the analytical solution, and a failure comprehensive criterion in the evaporation / sublimation heat dissipation starting process is obtained.

[0007] The application provides an approximate analytical method for evaporation / sublimation heat dissipation working parameter prediction, and mainly comprises the following steps: theoretical analysis is carried out on the gas-liquid / gas-solid-liquid phase change heat and mass transfer problem in the porous medium under vacuum condition in the evaporation / sublimation heat dissipation starting process; a phase change heat and mass transfer mathematical model and a definite condition in the porous medium are established; and an analytical solution of the one-dimensional gas-liquid / gas-solid-liquid phase change heat and mass transfer problem in the porous medium in different working processes of the evaporation / sublimation heat dissipation is derived by using gradient transformation.

[0008] The application also comprises the following: based on the analytical solution and the corresponding constraint condition, a failure comprehensive criterion in the evaporation / sublimation heat dissipation starting process is obtained through analysis.

[0009] Theoretical analysis of the gas-liquid / gas-solid-liquid phase change heat and mass transfer problem in the porous medium under vacuum condition in the evaporation / sublimation heat dissipation starting process comprises three typical processes: evaporation in the liquid supply cavity, evaporation in the porous plate and sublimation in the porous plate; the phase change heat and mass transfer mathematical model and the definite condition in the porous medium are established for the three typical processes of evaporation in the liquid supply cavity, evaporation in the porous plate and sublimation in the porous plate.

[0010] The analytical solution of the one-dimensional gas-liquid / gas-solid-liquid phase change heat and mass transfer problem in the porous medium in different working processes of the evaporation / sublimation heat dissipation is derived by using gradient transformation and other methods.

[0011] The comprehensive criterion of the heat load-liquid supply mass flow rate and the like in the evaporation / sublimation heat dissipation starting process without "dry evaporation" can be obtained as follows:

[0012]

[0013] The criterion of the liquid supply pressure, the porous plate parameter and the heat load and the like in the evaporation / sublimation heat dissipation starting process without "breakthrough" is as follows:

[0014]

[0015] Specifically, the application provides an evaporation / sublimation heat dissipation working parameter prediction method, which comprises the following steps:

[0016] (1)The starting process of the evaporation / sublimation heat dissipation device is divided into three processes: the evaporation process of the liquid working medium in the liquid supply chamber, the evaporation process of the liquid working medium into the porous plate, and the sublimation process of the liquid working medium in the porous plate;

[0017] (2)The mathematical models of phase change heat and mass transfer in the three processes are established to obtain the analytical solutions of the effective area temperature, heat transfer heat flow, and phase change interface position in the three processes;

[0018] (3)Based on the analytical solutions of the effective area temperature, heat transfer heat flow, and phase change interface position in the evaporation process of the liquid working medium in the liquid supply chamber, the changes of the effective area temperature, heat transfer heat flow, and phase change interface position with time in the evaporation process of the liquid working medium in the liquid supply chamber are obtained, and when T w > 0 and δ e (t) = δ w , step (4) is entered, wherein T w is the temperature of the liquid working medium in the evaporation / sublimation heat dissipation device, δ e (t) is the evaporation interface position, and δ w is the height of the liquid supply chamber;

[0019] (4)The data of the effective area temperature, heat transfer heat flow, and phase change interface position at the end of the previous process are taken as initial values, which are substituted into the analytical solutions of the effective area temperature, heat transfer heat flow, and phase change interface position in the sublimation process of the liquid working medium into the porous plate to obtain the changes of the effective area temperature, heat transfer heat flow, and phase change interface position with time in the sublimation process of the liquid working medium into the porous plate, and when T w > 0, T pw < 0, and δ e (t) < δ w + δ p , step (5) is entered; wherein T pw is the liquid zone temperature of the porous plate, and δ p is the thickness of the porous plate;

[0020] (5)The data of the effective area temperature, heat transfer heat flow, and phase change interface position at the end of the previous process are taken as initial values, which are substituted into the analytical solutions of the effective area temperature, heat transfer heat flow, and phase change interface position in the evaporation process of the liquid working medium into the porous plate to obtain the changes of the effective area temperature, heat transfer heat flow, and phase change interface position with time in the evaporation process of the liquid working medium into the porous plate, and when T w > 0, T pw > 0, δ e (t) < δ w + δ p , and δ i (t) = 0, step (4) is entered; wherein δ i (t) is the thickness of the ice layer;

[0021] (6) When the end condition is met, the effective area temperature, heat transfer heat flow and phase change interface position in the three processes are obtained.

[0022] Further, in the evaporation process of the liquid working medium in the liquid supply cavity, the effective area includes the liquid region of the liquid supply cavity and the gas region of the liquid supply cavity;

[0023] In the process of the liquid working medium entering the porous plate evaporation, the effective area includes the liquid region of the liquid supply cavity, the liquid region of the porous plate and the gas region of the porous plate;

[0024] In the process of the liquid working medium entering the porous plate sublimation, the effective area includes the liquid region of the liquid supply cavity, the liquid region of the porous plate, the ice region of the porous plate and the gas region of the porous plate.

[0025] Further, in the evaporation process of the liquid working medium in the liquid supply cavity, the phase change heat and mass transfer mathematical model includes a mass balance differential equation and an energy balance differential equation;

[0026] The mass balance differential equation and the energy balance differential equation are respectively:

[0027]

[0028] The boundary conditions and initial conditions are:

[0029]

[0030] T w | t＝0,x≥0 = T g ;

[0031] At the evaporation interface, there is:

[0032]

[0033]

[0034] Where, m w is the mass of the liquid working medium in the evaporation / sublimation heat dissipation device, t is time, p w is the density of the liquid working medium, a w is the equivalent thermal diffusivity of the liquid region of the liquid supply cavity, d w is the thickness of the liquid supply cavity, x is the coordinate along the height direction of the evaporation / sublimation heat dissipation device, is the liquid supply mass flow rate of the liquid working medium, k w is the equivalent thermal conductivity of the liquid supply cavity, is the evaporation mass flow rate of the liquid working medium; T w is the temperature of the liquid working medium in the sublimator, Q is the heat load of the evaporation / sublimation heat dissipation device, A r is the heated area of the evaporation / sublimation heat dissipation device, T gTin is the temperature of the liquid supply, δ e t is the location of the evaporation interface; h e L is the latent heat of the liquid working medium, T e Tin is the temperature of the evaporation interface, m is the evaporation mass flow rate.

[0035] Further, in the process of the liquid working medium entering the porous plate for evaporation in step (2), the mathematical model of phase change heat and mass transfer includes an energy balance differential equation;

[0036] The energy balance differential equation is:

[0037]

[0038] The boundary conditions and initial conditions are:

[0039]

[0040]

[0041] In the porous plate, there are:

[0042]

[0043]

[0044] At the evaporation interface of the liquid working medium, there are:

[0045]

[0046] wherein subscript pw represents the liquid zone of the porous plate, T e1 Tin is the temperature of the evaporation interface when the liquid working medium obtained from the evaporation process in the liquid supply cavity fills the liquid supply cavity, x2 is a coordinate along the thickness direction of the porous plate, T pin Tin is the temperature of the evaporation interface when the liquid working medium obtained from the evaporation process in the liquid supply cavity fills the liquid supply cavity, x2 is a coordinate along the thickness direction of the porous plate, T w (δ w , t1) is the temperature of the liquid supply cavity at x = δ w when the liquid working medium obtained from the evaporation process in the liquid supply cavity fills the liquid supply cavity, t1 is the time when the liquid working medium fills the liquid supply cavity, T pw Tin is the temperature of the evaporation interface when the liquid working medium obtained from the evaporation process in the liquid supply cavity fills the liquid supply cavity, x2 is a coordinate along the thickness direction of the porous plate, T pw α is the equivalent thermal diffusivity of the liquid zone of the porous plate, δ pw (t) is the thickness of the liquid zone of the porous plate, T e Tin is the temperature of the evaporation interface when the liquid working medium obtained from the evaporation process in the liquid supply cavity fills the liquid supply cavity, x2 is a coordinate along the thickness direction of the porous plate, T pw k is the equivalent thermal conductivity of the liquid zone of the porous plate; T e Tin is the temperature of the evaporation interface when the liquid working medium obtained from the evaporation process in the liquid supply cavity fills the liquid supply cavity, x2 is a coordinate along the thickness direction of the porous plate, T w Hin is the height of the liquid supply cavity.

[0047] Further, in the process of the liquid working medium entering the porous plate for sublimation, the phase change heat and mass transfer mathematical model includes a one-dimensional transient heat conduction equation of heat transfer;

[0048] The one-dimensional transient heat conduction equation of heat transfer is:

[0049] The liquid supply cavity region:

[0050]

[0051]

[0052]

[0053] In the formula, δ w is the height of the liquid supply cavity, T pin2 is the temperature of the interface between the porous plate and the liquid supply cavity when the liquid working medium enters the porous plate for sublimation, t2 is the time when the evaporation process in the porous plate ends, c w is the equivalent specific heat capacity of the liquid supply cavity;

[0054] For the liquid region of the porous plate, we have:

[0055]

[0056] The boundary conditions are:

[0057]

[0058] In the formula, the subscripts pw and pi respectively represent the liquid region containing the porous plate and the ice region of the porous plate, x2 is the coordinate along the thickness direction of the porous plate, T f is the temperature of the ice-liquid interface, δ f (t) is the ice-liquid interface, h s is the sublimation latent heat of ice. Let the position of the sublimation interface in the porous plate be δ s (t), the thickness of the ice region in the porous plate be δ pi (t), the thickness of the liquid region in the porous plate be δ pw (t), and δ s (t) = δ pi (t) + δ f (t).

[0059] For the ice region of the porous plate, we have:

[0060]

[0061] The boundary conditions are:

[0062]

[0063]

[0064] where T mi is the temperature of the ice region of the porous plate, k mi is the equivalent thermal conductivity of the ice region of the porous plate, x is the coordinate along the height direction of the evaporation / sublimation heat dissipation device, h s is the latent heat of sublimation of the working fluid, is the mass flow rate of sublimation of the working fluid, T s is the interface temperature of sublimation of the working fluid;

[0065] There is an energy balance relationship at the ice-liquid interface and the ice-air interface:

[0066]

[0067] where ρ i is the density of ice.

[0068] Further, the analytical solution of the effective region temperature of the liquid working fluid in the evaporation process in the liquid supply cavity is:

[0069]

[0070] The analytical solution of the effective region heat transfer heat flux of the liquid working fluid in the evaporation process in the liquid supply cavity is:

[0071]

[0072] The equation of the phase change interface position of the liquid working fluid in the evaporation process in the liquid supply cavity is:

[0073] The initial condition is δ e (0) = 0

[0074] where t is time, ρ w is the density of the liquid working fluid, α w is the equivalent thermal diffusivity of the liquid region of the liquid supply cavity, x is the coordinate along the height direction of the evaporation / sublimation heat dissipation device, is the liquid supply mass flow rate, Q is the heat load of the evaporation / sublimation heat dissipation device, A r is the heated area of the evaporation / sublimation heat dissipation device, T g is the liquid supply temperature, q w (x, t) represents the heat transfer heat flux, ierfc is the inverse error function, h e is the evaporation latent heat of the liquid working fluid.

[0075] Further, the analytical solution of the effective region temperature of the liquid working fluid in the evaporation process in the liquid supply cavity is:

[0076] The temperature of the liquid supply cavity is:

[0077]

[0078] wherein,

[0079] Temperature of liquid zone in the porous plate:

[0080]

[0081] wherein, is the error function, x2is the coordinate along the thickness direction of the porous plate, a pw is the equivalent thermal diffusivity of the liquid zone in the porous plate, k w is the equivalent thermal conductivity of the liquid zone in the porous plate, T pin is the temperature at the interface between the porous plate and the liquid supply cavity, T e is the evaporation temperature, δ w is the thickness of the liquid supply cavity.

[0082] The analytical solution of the effective area heat flux during the process of the liquid working medium entering the porous plate for evaporation is:

[0083] Heat flux of the liquid supply cavity:

[0084]

[0085] wherein, t1is the time for the liquid working medium to fill the liquid supply cavity through the evaporation process in the liquid supply cavity.

[0086] The position of the phase change interface during the process of the liquid working medium entering the porous plate for evaporation is:

[0087]

[0088] wherein, σ is the surface tension of the liquid working medium, r is the average pore diameter of the porous plate, θ is the contact angle between the liquid working medium and the micro-porous wall surface of the porous plate, P p is the liquid supply pressure, P sat is the saturation vapor pressure at the evaporation interface, K is the permeability coefficient of the porous plate, ε is the porosity of the porous plate, ρ w is the density of the liquid working medium, A r is the heating area of the evaporation / sublimation heat dissipation device, δ pw (t) is the thickness of the liquid zone in the porous plate, μ is the dynamic viscosity of the liquid working medium, is the liquid supply mass flow rate, is the evaporation mass flow rate, which can be obtained by the formula wherein,

[0089] The gas zone of the porous plate is a channel for the gas to be discharged to the external space, which participates in heat and mass transfer, but the zone is not involved in the evaporation / sublimation phase change, which can be ignored by comparing the heat exchange of the gas with the porous medium and the latent heat of the evaporation / sublimation phase change, so the heat balance equation of the gas zone of the porous plate is ignored in the modeling calculation of the present application, and the liquid zone and the ice zone are mainly investigated.

[0090] Further, the analytical solution of the temperature of the effective area participating in heat and mass transfer in the process of the liquid working medium entering the porous plate for sublimation is:

[0091] The temperature of the liquid supply cavity is:

[0092]

[0093] wherein,

[0094] The temperature of the liquid zone of the porous plate is:

[0095] 0 < x2 < δ f (t), δ f (t) ≤ δ p .

[0096] wherein, T' pin is the temperature at the interface of the porous plate and the liquid supply cavity.

[0097] The temperature of the ice zone of the porous plate is:

[0098] δ f (t) < x2 < δ s (t), δ s (t) ≤ δ p

[0099] wherein, α pw is the equivalent thermal diffusion coefficient of the liquid zone of the porous plate, T f is the temperature of the ice-liquid interface, α pi is the equivalent thermal diffusion coefficient of the ice zone of the porous plate, x2 is the coordinate along the thickness direction of the porous plate, δ pi is the thickness of the ice zone of the porous plate, δ mw is the thickness of the liquid zone of the porous plate, h s is the sublimation latent heat of ice, k mi is the equivalent thermal conductivity of the ice zone of the porous plate.

[0100] The analytical solution of the heat flow participating in heat and mass transfer in the process of the liquid working medium entering the porous plate for sublimation is:

[0101] The liquid zone of the liquid supply cavity:

[0102] 0 < x < δ w .

[0103] where,

[0104] where, δ w is the thickness of the liquid supply cavity, q w is the heat flux of the liquid supply cavity, δ s is the sublimation interface position, t2 is the duration of the evaporation process in the porous plate;

[0105] The energy balance equation at the phase change interface position in the process of the liquid working medium entering the porous plate sublimation is:

[0106] Ice-liquid interface position:

[0107]

[0108] Sublimation interface position:

[0109]

[0110] The phase change interface position in the process of the liquid working medium entering the porous plate sublimation is:

[0111] Ice-liquid interface position:

[0112]

[0113] Sublimation interface position:

[0114]

[0115] where,

[0116] where, d p is the particle size of the microparticles constituting the porous plate, δ p is the thickness of the porous plate, k is the Boltzmann constant, m m is the mass of the vapor molecules of the liquid working medium, P o is the ambient pressure, P sat is the saturation vapor pressure of the evaporation surface.

[0117] An evaporation / sublimation heat dissipation failure criterion acquisition method, comprising steps (1)-(6) of the above-mentioned evaporation / sublimation heat dissipation working parameter prediction method, further comprising:

[0118] Step (7): obtaining a failure criterion according to the analytical solutions of the effective region temperature, heat flux, and phase change interface position in the three processes, and the failure criterion is used to judge whether the evaporation / sublimation heat dissipation device appears dry-out or breakdown failure.

[0119] Further, the criterion for judging that dry-out does not occur in the evaporation / sublimation heat dissipation operation is:

[0120]

[0121] wherein, is the mass flow rate of the liquid supply, he is the latent heat of the liquid working medium, c w is the equivalent specific heat of the liquid region of the liquid supply cavity, T w is the temperature of the liquid supply, a w is the equivalent thermal diffusivity of the liquid region of the liquid supply cavity;

[0122] The criterion for determining that breakdown does not occur in the evaporation / sublimation heat dissipation operation is:

[0123]

[0124] wherein, P p is the pressure of the liquid supply, is the mass flow rate of the liquid working medium flowing in the porous plate, d p is the thickness of the porous plate, p w is the density of the liquid working medium, and e is the porosity of the porous plate.

[0125] Compared with the prior art, the present application has at least one of the following beneficial effects:

[0126] (1) The present application breaks through the approximate analytical solution method for predicting the transient operating parameters of the evaporation / sublimation heat dissipation device, meets the needs of design and operating characteristic analysis during the development of the evaporation / sublimation heat dissipation device, and provides essential technical support for the development of the evaporation / sublimation heat dissipation device;

[0127] (2) The approximate analytical solution method for predicting the transient operating parameters of the evaporation / sublimation heat dissipation device used in the present application can numerically simulate the heat exchange and phase change process during the start-up and operation of the evaporation / sublimation heat dissipation device, and provides convenience for detailed understanding of the working process of the evaporation / sublimation heat dissipation device;

[0128] (3) According to the output results of the approximate analytical solution method for predicting the transient operating parameters of the evaporation / sublimation heat dissipation device of the present application, not only the temperature and mass flow rate of the liquid supply of each part during the start-up process of the evaporation / sublimation heat dissipation device can be obtained, but also parameters that cannot be measured by experiments, such as the change of the phase change interface position and the change of the mass flow rate of the evaporation / sublimation gas, can be obtained, which has important guiding significance in the research and application fields of the evaporation / sublimation heat dissipation device;

[0129] (4) According to the output results of the approximate analytical solution method for predicting the transient operating parameters of the evaporation / sublimation heat dissipation device of the present application, the failure criterion during the start-up process of the evaporation / sublimation heat dissipation device can be obtained, and then the failure behavior under the combination of the corresponding design parameters (such as pore diameter) and working conditions (such as pressure and heat flux density) can be predicted, which is beneficial to improving the design efficiency and performance of the evaporation / sublimation heat dissipation device. BRIEF DESCRIPTION OF DRAWINGS

[0130] Figure 1 The schematic diagram for typical working process of the evaporation / sublimation heat dissipation device of the present application;

[0131] Figure 2 The schematic diagram for evaporation / sublimation heat dissipation working mode;

[0132] Figure 3 The comparison between in-orbit evaluation result and ground evaluation result of the present application, wherein (a) is the prediction of phase change interface by the present method (single cycle), (b) is the prediction of phase change interface by the experimentally verified numerical method (multiple cycles), and (c) is the comparison between the numerical method and the experimental result. DETAILED DESCRIPTION

[0133] The features and advantages of the present application will become more apparent from the detailed description of the application.

[0134] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. Unless specifically stated otherwise, the drawings are not drawn to scale and are merely intended to conceptually illustrate the features described herein.

[0135] In order to master the transient working characteristics of the evaporation / sublimation heat dissipation, it is particularly important to simulate and analyze the working process of the evaporation / sublimation heat dissipation device by using the numerical modeling method. Not only can the micro working process of the evaporation / sublimation heat dissipation be revealed, but also the working performance of the evaporation / sublimation heat dissipation device can be predicted, and then the failure criterion can be obtained. Furthermore, the theoretical support can be provided for the design of the evaporation / sublimation heat dissipation device in the future, and therefore it has very important significance.

[0136] The present application breaks through the existing lumped parameter analysis method for the steady state and working performance of the evaporation / sublimation heat dissipation device, and proposes a transient modeling and analytical solution method for the starting process of the evaporation / sublimation heat dissipation device, so as to solve the technical problems that the micro phase change working process transient characteristics and failure criterion in the evaporation / sublimation heat dissipation research process cannot be obtained by using the existing method and cannot be predicted by using the experimental method. In order to master the working characteristics of the evaporation / sublimation heat dissipation device, the necessary technical support can be provided for the development and failure judgment of the evaporation / sublimation heat dissipation device.

[0137] The application provides an evaporation / sublimation heat dissipation working parameter prediction method, mainly including the following main steps: (1) simplifying the evaporation / sublimation heat dissipation device into a basic unit composed of a liquid supply cavity and a porous plate, and dividing the gas-liquid / gas-solid-liquid phase change heat and mass transfer in the porous medium under the vacuum condition in the starting process into three typical stages, namely, the evaporation process of the liquid working medium in the liquid supply cavity of the evaporation / sublimation heat dissipation device, the evaporation process of the liquid working medium into the porous plate and the process of the working medium into the porous plate icing and sublimation. In the evaporation process in the liquid supply cavity, the effective area of the evaporation / sublimation heat dissipation device participating in the heat and mass transfer includes the liquid zone of the liquid supply cavity and the gas zone of the liquid supply cavity; in the evaporation process of the porous plate, the effective area of the evaporation / sublimation heat dissipation device participating in the heat and mass transfer includes the liquid zone of the liquid supply cavity, the liquid zone of the porous plate and the gas zone of the porous plate; in the evaporation process of the porous plate, the effective area of the evaporation / sublimation heat dissipation device participating in the heat and mass transfer includes the liquid zone of the liquid supply cavity, the liquid zone of the porous plate, the ice zone of the porous plate and the gas zone of the porous plate; (2) establishing the heat balance, mass balance and force balance differential equations of the liquid zone of the liquid supply cavity and the gas zone of the liquid supply cavity in the evaporation process of the liquid working medium in the liquid supply cavity of the evaporation / sublimation heat dissipation device, determining the boundary conditions and initial conditions, and analytically solving through the gradient transformation method to obtain the analytical solution of the temperature, heat transfer heat flow and phase change interface position of the liquid zone of the liquid supply cavity and the gas zone of the liquid supply cavity; (3) in the evaporation process of the liquid working medium in the liquid supply cavity to the vacuum environment, when the liquid supply mass flow rate is greater than the evaporation mass flow rate, the liquid working medium will accumulate in the liquid supply cavity, and when the liquid working medium fills the liquid supply cavity, the liquid working medium will enter the porous plate connected with the liquid supply cavity under the action of pressure, and the evaporation / sublimation heat dissipation device enters the evaporation working section in the porous plate.(4) With the evaporation heat absorption of the liquid working medium in the porous plate, the temperature of the liquid-gas interface will gradually decrease. When the temperature and pressure of the liquid-gas interface decrease to the triple point temperature and pressure of the working medium, and the temperature gradient is less than 0, the liquid will crystallize in the porous plate and evaporate / sublimate to the vacuum environment, and the evaporation / sublimation heat dissipation device enters the sublimation working section in the porous plate. At this time, the heat balance, mass balance and force balance differential equations are established for the liquid region of the liquid supply cavity, the liquid region of the porous plate, the ice region of the porous plate and the gas region of the porous plate, the boundary conditions and initial conditions are determined, and the analytical solution of the temperature, heat flow and ice-liquid, ice-gas phase change interface position in each region is obtained by gradient transformation method. During the working process of the evaporation / sublimation heat dissipation device, the ice-liquid, ice-gas phase change interface position and ice layer thickness and other parameters are dynamically changed. When the ice layer thickness in the porous plate becomes 0 under the interaction of the ice-gas interface sublimation / ice-liquid interface melting, the temperature and pressure of the ice-gas / ice-liquid interface rise to the triple point temperature and pressure of the liquid working medium, and the temperature gradient is greater than 0, the sublimation working section in the porous plate ends, and the evaporation process in the porous plate is entered again, which marks the evaporation / sublimation heat dissipation device enters the evaporation-sublimation circulating working process in the porous plate.

[0138] The application also provides an evaporation / sublimation heat dissipation working parameter prediction and failure criterion acquisition method, which further comprises:

[0139] (6) After meeting the calculation time length or other calculation conditions, the temperature, heat flow, phase change interface position and other parameters of the evaporation / sublimation heat dissipation device obtained in each stage and the running failure mode of the evaporation / sublimation heat dissipation device are analyzed, and then the running failure conditions of the evaporation / sublimation heat dissipation device are derived according to the analytical solution.

[0140] The modeling analysis is based on the following assumptions: (a) the uneven distribution of the liquid working medium in the liquid supply cavity and the porous plate of the evaporation / sublimation heat dissipation device is ignored; (b) when the temperature and pressure of the evaporation interface working medium reach the triple point pressure and temperature of the working medium, the liquid working medium will crystallize when the temperature continues to decrease; (c) the radiation heat exchange between the evaporation / sublimation heat dissipation device and the surrounding environment is ignored in the space environment.

[0141] Based on the above assumptions, the heat balance, mass balance and analytical solution method for the working process of the evaporation / sublimation heat dissipation device are as follows:

[0142] (1) Evaporation process in the liquid supply cavity of the evaporation / sublimation heat dissipation device

[0143] In the starting stage of the evaporation / sublimation heat dissipation device, the liquid working medium at a certain temperature enters the evaporation / sublimation heat dissipation device and is exposed to a vacuum environment. Taking the liquid working medium in the evaporation / sublimation heat dissipation device as the research object, the mass conservation relationship, energy balance equation and boundary conditions are as follows:

[0144]

[0145] T w | t＝0,x≥0 = T g (4)

[0146] Among them, is the mass of the liquid working medium in the evaporation / sublimation heat dissipation device, ρ w is the density of the liquid working medium, c w is the specific heat of the liquid working medium, α w is the equivalent thermal diffusivity of the liquid zone of the liquid supply cavity, k w is the equivalent thermal conductivity of the liquid zone of the liquid supply cavity, δ e (t) is the gas-liquid interface position, δ w is the height of the liquid supply cavity, is the liquid supply mass flow rate of the liquid working medium, is the evaporation mass flow rate of the liquid working medium. T w is the temperature of the liquid working medium in the evaporation / sublimation heat dissipation device, Q is the heat load of the evaporation / sublimation heat dissipation device, A r is the effective heat dissipation area of the evaporation / sublimation heat dissipation device, T g is the initial temperature, δ e (t) is the evaporation interface position, and x is the coordinate along the thickness direction of the evaporation / sublimation heat dissipation device.

[0147] At the evaporation interface, there are:

[0148]

[0149]

[0150] Among them, h e is the latent heat of evaporation of the liquid working medium, T e is the evaporation interface temperature, is the evaporation mass flow rate.

[0151] The equation and boundary conditions of equation (2) are converted, which can be transformed into heat flux q w (x,t) function:

[0152]

[0153] q w | t＝0,x≥0 =0 (9)

[0154]

[0155] The similar transformation and integration of equation (7) can obtain the heat flux distribution function of the liquid supply cavity of the evaporation / sublimation heat dissipation device:

[0156]

[0157] And the implicit differential equation of the evaporation interface position is:

[0158]

[0159] Its initial condition is δ e (0)=0, and equation (12) can be solved to obtain the position of the evaporation interface of the liquid supply cavity of the evaporation / sublimation heat dissipation device.

[0160] Since the steam generated by the evaporation of the liquid working medium will produce a certain pressure drop when passing through the porous plate to the vacuum environment, the evaporation mass flow rate of the liquid working medium depends on many factors: the temperature of the liquid working medium, the heating heat, the thickness of the porous plate, the pore size, the porosity, the vacuum environment pressure and other parameters. According to the pressure drop of the gas flowing through the porous plate, the evaporation mass flow rate of the liquid working medium under a certain pressure difference is:

[0161]

[0162] Wherein, P sat is the saturation vapor pressure of the evaporation surface, P o is the environmental pressure, k is the Boltzmann constant, m m is the mass of the working gas molecules, δ p is the thickness of the porous plate, r is the pore size of the porous plate, nA r is the number of micropores of the cross-sectional area of the porous plate. Joint equation (1), equation (12), equation (13) can obtain the temperature T w of the liquid zone in the liquid supply cavity:

[0163]

[0164] In the formula, ierfc is the inverse error function.

[0165] (2) Analysis of evaporation process in porous plate

[0166] Evaporation process in porous plate, liquid completely fills the supply liquid cavity and enters the porous plate evaporation, affected by flow resistance, flow rate decreases, forced convection weakens, at this time the heat transfer process is simplified as one-dimensional heat conduction. For convenience of calculation, in the analysis of evaporation process in porous plate, the coordinate in the thickness direction of the supply liquid cavity is still recorded as x, and the coordinate in the thickness direction of the porous plate is recorded as x2, then x2=x-δ w . Taking the temperature distribution at the end of the evaporation process in the supply liquid cavity as the initial condition of the process, the energy balance equation and boundary condition of the supply liquid cavity region are as follows:

[0167]

[0168] Where, T pin (t) is the temperature at the position where the supply liquid cavity and the porous plate intersect, T w (δ w ,t1) is the temperature of the supply liquid cavity at x=δ w when the liquid fills the supply liquid cavity, t1 is the time when the liquid fills the supply liquid cavity.

[0169] The liquid region of the porous plate has:

[0170]

[0171] The liquid evaporation interface has:

[0172]

[0173] Where, subscript pw represents the liquid region of the porous plate, T e1 is the temperature of the evaporation interface when the liquid fills the supply liquid cavity obtained from equation (14), T pw is the temperature of the liquid region of the porous plate, α pw is the equivalent thermal diffusivity of the liquid region of the porous plate, δ pw (t) is the thickness of the liquid region of the porous plate, T e is the evaporation temperature, k pw is the equivalent thermal conductivity of the liquid region of the porous plate.

[0174] Transforming the equation shown in equation (15) and the boundary conditions, the heat flow equation is obtained, and the heat flow equation in the supply liquid cavity is solved by heat flow method:

[0175]

[0176]

[0177] Where, q w (δ wt1) is the heat flux distribution of the liquid supply cavity when it is filled with the liquid working medium obtained from formula (14).

[0178] Solving formula (23) can obtain:

[0179]

[0180] wherein,

[0181] Further, the temperature of the liquid supply cavity can be obtained:

[0182]

[0183] The heat flux of the liquid zone of the porous plate:

[0184]

[0185] The temperature of the liquid zone of the porous plate:

[0186]

[0187] wherein, c2=q w (δ w ,t) can be obtained from formula (25). q w (δ w ,t) in the formula can be obtained from formula (25).

[0188] The force analysis of the liquid in the porous plate can obtain the position of the evaporation interface in the porous plate:

[0189]

[0190] In the formula, σ is the surface tension of the liquid working medium, r is the average pore diameter of the porous plate, θ is the contact angle of the liquid working medium and the micro-porous wall surface of the porous plate, P p is the liquid supply pressure, P sat is the saturation vapor pressure of the evaporation interface, K is the permeability coefficient of the porous plate, ε is the porosity of the porous plate, ρ w is the density of the liquid working medium, A r is the area of the porous plate, μ is the dynamic viscosity of the liquid working medium, is the liquid supply mass flow rate, is the evaporation mass flow rate, which can be obtained from formula (13), but q

[0191] (3) Sublimation process in the porous plate

[0192] The liquid working substance evaporates and absorbs heat in the porous plate, which lowers the temperature of the porous plate and the working substance, and lowers the saturated vapor pressure at the evaporation interface. When the saturated vapor pressure at the evaporation interface is lower than the triple-point pressure of the liquid working substance, the working substance at the evaporation interface begins to freeze and sublimes at the interface with the vacuum, thereby dissipating the heat transferred by the liquid working substance to the vacuum environment. Under the effect of sublimation heat dissipation, the thickness of the frozen region of the working substance in the porous plate will increase; meanwhile, under the influence of the system heat load, the interface between the liquid working substance and the solid working substance will also migrate in the porous medium, thereby affecting the thickness of the frozen region of the working substance. At this time, due to the freezing of the liquid working substance in the porous region, the flow of the liquid working substance to the vacuum side of the porous plate almost stops. Neglecting the effect of convection brought by the liquid flow, a one-dimensional transient heat conduction equation describing the heat transfer of the evaporation / sublimation heat dissipation device is established as follows:

[0193] The liquid supply cavity region:

[0194]

[0195] In the formula, δ w is the thickness of the liquid supply cavity, T pin2 is the temperature of the interface between the porous plate and the liquid supply cavity when the sublimation process into the porous plate begins, and t2 is the time when the evaporation process in the porous plate ends.

[0196] For the liquid region of the porous plate, the following equation is obtained:

[0197]

[0198] The boundary condition is:

[0199]

[0200] Let the subscripts pw and pi respectively represent the liquid region of the porous plate and the ice region of the porous plate, T f is the temperature of the ice-liquid interface, δ f (t) is the ice-liquid interface. Let the position of the sublimation interface in the porous plate be δ s (t), the thickness of the ice region in the porous plate be δ pi (t), the thickness of the liquid region in the porous plate be δ pw (t), δ s (t) = δ pi (t) + δ f (t), and h s be the sublimation latent heat of ice, then for the ice region of the porous plate, the following equation is obtained:

[0201]

[0202] The boundary condition is:

[0203]

[0204] The energy balance at the ice-liquid interface and the ice-air interface is:

[0205]

[0206] The heat flow equation in the liquid supply cavity is:

[0207]

[0208] The heat flow boundary condition is:

[0209]

[0210] q w (0,t)=Q / A r , (43)

[0211] The energy balance at the ice-liquid interface and the ice-air interface is:

[0212]

[0213] The temperature of the liquid supply cavity is obtained by solving:

[0214]

[0215] wherein,

[0216] The temperature of the liquid zone of the porous plate is obtained by the same method:

[0217]

[0218] wherein, T' pin is the temperature at the interface between the porous plate and the liquid supply cavity at each time, which can be obtained by equation (46).

[0219] The temperature of the ice zone of the porous plate is:

[0220]

[0221] The position of the ice-liquid interface is obtained by the energy equation at the ice-liquid interface:

[0222]

[0223] wherein, The position equation of the sublimation interface is:

[0224]

[0225] (4) Evaporation / sublimation heat dissipation failure criterion and verification

[0226] According to the above results, further analysis can be obtained that the condition of not "evaporating dry" in the start of the evaporation / sublimation heat dissipation device is: in the evaporation process in the liquid supply cavity, δ e (t) = 0, the moving speed of the evaporation interface position That is, the heat load-liquid supply mass flow multi-parameter comprehensive criterion can be obtained from formula (12):

[0227]

[0228] In the evaporation process in the porous plate, if the liquid working medium is evaporated under the action of the liquid supply pressure, the capillary force of the porous plate, the flow resistance, etc., and the evaporation interface moves to the boundary of the porous plate and the vacuum, its temperature is higher than the triple point temperature of the liquid working medium, the moving speed and acceleration of the evaporation interface to the vacuum side are both greater than 0, then the liquid working medium will "break through" the porous plate, directly enter the vacuum without icing, which reduces the utilization rate of the liquid working medium and causes the heat dissipation to fail. That is, in formula (29), when δ pw (t) = δ p , T pw (δ p , t) > 273.16 K, then the liquid supply pressure-porous plate parameter-heat load criterion for not "breaking through" in the start of the evaporation / sublimation heat dissipation can be obtained from formula (29):

[0229]

[0230] Embodiment:

[0231] As Figure 1 and Figure 2 , according to the initial conditions, the steps of modeling, analytically solving and failure prediction of the evaporation / sublimation heat dissipation device working process are as follows:

[0232] (1). The evaporation / sublimation heat dissipation device is in a storage state at the initial working time, in a vacuum environment, without liquid inside, the initial conditions and boundary conditions of the temperature and heat flow in the evaporation process in the liquid supply cavity of the evaporation / sublimation heat dissipation device are given, the analytical solution of the temperature and heat flow in the evaporation process in the liquid supply cavity and the position of the evaporation interface are obtained, and the temperature distribution and heat flow distribution in the evaporation process in the liquid supply cavity and the change of the position of the evaporation interface with time are obtained. If T w > 0 and δ e (t) < δ w , it is considered that the liquid working medium does not fill the liquid supply cavity; if T w > 0 and δ e (t) = δ w , the liquid working medium fills the liquid supply cavity, and the analytical solution of the evaporation process in the porous plate in step (2) is used for solving.

[0233] (2). If Tw > 0, T pw > 0 and δ e (t) < δ w + δ p , the temperature and the phase change interface position data at the end of the previous process are substituted into the analytical solution of the temperature, heat flux and evaporation interface position of each zone in the porous plate obtained by solving the evaporation process in the porous plate, to obtain the temperature of the liquid supply chamber, the liquid zone / gas zone in the porous plate, the distribution and change of the heat flux transferred with time, and the change of the evaporation interface position in the porous plate with time. The calculation is ended until the calculation end condition or the condition of the freezing of the liquid working medium in the porous plate is met: T w > 0, T pw < 0, δ e (t) < δ w + δ p .

[0234] (3). If the freezing in the porous plate of the evaporation / sublimation heat dissipation device is determined according to the calculation result of step (2), the calculation result of step (2) is substituted into the analytical solution of the temperature, heat flux and sublimation interface position of each zone in the porous plate obtained by solving the sublimation process in the porous plate, to obtain the temperature of the liquid supply chamber, the liquid zone / ice zone / gas zone in the porous plate, the distribution and change of the heat flux transferred with time, and the change of the ice-liquid interface and the ice-gas sublimation interface position in the porous plate with time. The calculation result is determined, and the calculation is ended if the calculation end condition is met; otherwise, when T w > 0, T pw > 0, δ e (t) < δ w + δ p , δ i (t) = 0, the ice layer in the porous plate disappears, and step (2) is performed when the thickness of the ice zone is zero.

[0235] The analytical solution obtained by using the above steps and the present application can be used to predict the working process of the evaporation / sublimation heat dissipation device from the storage state, and the change law of the temperature, heat flux and phase change interface position in the starting and running process of the evaporation / sublimation heat dissipation device can be obtained. The prediction of the ice-liquid and ice-gas sublimation interface by the analytical analysis method is consistent with the prediction result of the numerical theoretical model verified by the experiment, such as Figure 3 .

[0236] If it is desired to investigate the evolution law of the running state of the evaporation / sublimation heat dissipation device which is not in the storage state at the initial time, the corresponding initial condition is determined, which is substituted into the analytical solution described in step (2) or step (3), to obtain the change law of the temperature, heat flux and phase change interface position in the running process from the corresponding stage.

[0237] If the initial condition of the evaporation / sublimation heat dissipation device is known, the boundary condition is confirmed to be consistent with the boundary condition of the present application, the design and operating parameters of the evaporation / sublimation heat dissipation device can be substituted into the failure criterion of the evaporation / sublimation heat dissipation device to estimate whether the evaporation / sublimation heat dissipation device will appear "dry out" or "breakdown" failure under the current design state. The liquid supply pressure of the evaporation / sublimation heat dissipation device under different parameter combinations that may occur "breakdown" failure is predicted by the analysis method, as shown in Table 1. Among them, according to the estimation, when the startup heat load is 0.6 W / cm 2 , the "breakdown" failure liquid supply pressure of the porous plate with a thickness of 0.8 mm is about 21 kPa. The evaporation / sublimation heat dissipation device is designed to carry out experiments under this condition, and "breakdown" occurs when the liquid supply pressure rises to 18.9 kPa, which is basically consistent with the experimental data, with an error of about 2 kPa, which is within the acceptable range of engineering experiments.

[0238] Table 1 "Breakdown" failure prediction of evaporation / sublimation heat dissipation device

[0239]

[0240]

[0241] The present application has been described in detail with reference to specific embodiments and exemplary examples, but these descriptions are not to be construed as limiting the present application. Those skilled in the art understand that various equivalent substitutions, modifications or improvements can be made to the technical solutions and embodiments of the present application without departing from the spirit and scope of the present application, and these all fall within the scope of the present application. The scope of protection of the present application is subject to the appended claims.

[0242] The contents not described in detail in the specification of the present application are well-known technologies to those skilled in the art.

Claims

1. A method for predicting working parameters of evaporation / sublimation heat dissipation, characterized in that: include: (1) The startup process of the evaporation / sublimation heat dissipation device is divided into three processes: the evaporation process of the liquid working medium in the liquid supply chamber, the process of the liquid working medium entering the porous plate and evaporating, and the process of the liquid working medium sublimating in the porous plate; (2) Establish a mathematical model of phase change heat and mass transfer in the three processes and obtain analytical solutions for the effective area temperature, heat transfer flux, and phase change interface position in the three processes; (3) Based on the analytical solution of the effective area temperature, heat transfer heat flux and phase change interface position during the evaporation of the liquid working medium in the liquid supply cavity, the changes of the effective area temperature, heat transfer heat flux and phase change interface position with time during the evaporation of the liquid working medium in the liquid supply cavity are obtained. When T w >0 and δ e (t) = δ w , go to step (4), where T w is the temperature of the liquid working medium in the evaporation / sublimation heat sink, δ e (t) is the position of the evaporation interface, δ w is the height of the liquid supply cavity; (4) The data of effective area temperature, heat transfer flux and phase change interface position at the end of the previous process are used as initial values, and the analytical solutions of effective area temperature, heat transfer flux and phase change interface position in the process of liquid working medium entering the porous plate for sublimation are obtained to obtain the changes of effective area temperature, heat transfer flux and phase change interface position with time in the process of liquid working medium entering the porous plate for sublimation. When T is satisfied w >0,T pw <0,δ e (t)<δ w +δ p When , go to step (5); where T pw is the temperature of the liquid zone of the porous plate, δ p is the thickness of the porous plate; (5) The data of effective area temperature, heat transfer heat flux and phase change interface position at the end of the previous process are used as initial values, and the analytical solution of effective area temperature, heat transfer heat flux and phase change interface position in the process of liquid working medium entering the porous plate for evaporation is obtained to obtain the changes of effective area temperature, heat transfer heat flux and phase change interface position with time in the process of liquid working medium entering the porous plate for evaporation. When T is satisfied w >0,T pw >0,δ e (t)<δ w +δ p , δ i When (t) = 0, go to step (4), where δ i (t) is the thickness of the ice layer; (6) When the end conditions are met, the changes in effective area temperature, heat transfer heat flux and phase change interface position over time in the three processes are obtained.

2. The method for predicting evaporation / sublimation heat dissipation working parameters according to claim 1, characterized in that: During the evaporation process of the liquid working medium in the liquid supply cavity, the effective area includes the liquid area of ​​the liquid supply cavity and the gas area of ​​the liquid supply cavity; When the liquid working medium enters the porous plate and evaporates, the effective area includes the liquid area of ​​the liquid supply cavity, the liquid area of ​​the porous plate and the gas area of ​​the porous plate; When the liquid working medium enters the porous plate and sublimates, the effective area includes the liquid area of ​​the liquid supply cavity, the liquid area of ​​the porous plate, the ice area of ​​the porous plate and the gas area of ​​the porous plate.

3. The method for predicting evaporation / sublimation heat dissipation working parameters according to claim 1, characterized in that: In the evaporation process of the liquid working medium in the liquid supply chamber in step (2), the phase change heat and mass transfer mathematical model includes a mass balance differential equation and an energy balance differential equation; The mass balance differential equation and energy balance differential equation are: The boundary conditions and initial conditions are: T w | t＝0,x≥0 =T g ; At the evaporation interface: Among them, m w is the mass of the liquid working medium in the evaporation / sublimation heat sink, t is the time, ρ w is the density of the liquid working medium, α w is the equivalent thermal diffusivity of the liquid area of ​​the liquid supply cavity, δ w is the thickness of the liquid supply cavity, x is the coordinate along the height direction of the evaporation / sublimation heat sink, is the mass flow rate of liquid working medium, k w is the equivalent thermal conductivity of the liquid supply cavity, is the evaporation mass flow rate of the liquid working medium; T w is the temperature of the liquid working medium in the sublimator, Q is the heat load of the evaporation / sublimation heat sink, A r is the heating area of ​​the evaporation / sublimation heat sink, T g is the supply temperature, δ e (t) is the position of the evaporation interface; h e is the latent heat of vaporization of the liquid working medium, T e is the evaporation interface temperature, is the evaporation mass flow rate.

4. The method for predicting evaporation / sublimation heat dissipation working parameters according to claim 1, characterized in that: In the process of step (2) when the liquid working medium enters the porous plate for evaporation, the phase change heat and mass transfer mathematical model includes an energy balance differential equation; The energy balance differential equation is: The boundary conditions and initial conditions are: The porous plate contains: At the evaporation interface of the liquid working medium, there are: Wherein, the subscript pw represents the porous plate liquid area, T e1 is the temperature of the evaporation interface when the liquid working medium fills the liquid supply chamber obtained by the evaporation process in the liquid supply chamber, x2 is the coordinate along the thickness direction of the porous plate, T pin is the temperature at the interface between the porous plate and the liquid supply chamber, T w (δ w , t1) is the time when the liquid working medium obtained by the evaporation process in the liquid supply chamber fills the liquid supply chamber x=δ w The temperature of the liquid supply cavity, t1 is the time when the liquid working medium fills the liquid supply cavity, T pw is the temperature of the liquid zone of the porous plate, α pw is the equivalent thermal diffusivity of the porous plate liquid area, δ pw (t) is the thickness of the liquid zone of the porous plate, T e is the evaporation temperature, k pw is the equivalent thermal conductivity of the porous plate liquid area; T e is the evaporation temperature, δ w is the height of the liquid supply chamber.

5. The method for predicting evaporation / sublimation heat dissipation working parameters according to claim 1, characterized in that: In step (2), during the sublimation of the liquid working medium entering the porous plate, the phase change heat and mass transfer mathematical model includes a one-dimensional transient heat conduction equation for heat transfer; The one-dimensional transient heat conduction equation for heat transfer is: Liquid supply cavity area: Where, δ w is the height of the liquid supply chamber, T pin2 is the temperature of the interface between the porous plate and the liquid supply chamber when the sublimation process enters the porous plate, t2 is the time when the evaporation process in the porous plate ends, c w is the equivalent specific heat capacity of the liquid supply cavity; For the porous plate liquid area: The boundary conditions are: Where, the subscripts pw and pi represent the liquid area and ice area of ​​the porous plate, respectively; x2 is the coordinate along the thickness direction of the porous plate; T f is the temperature of the ice-liquid interface, δ f (t) is the ice-liquid interface, h s is the latent heat of sublimation of ice. The position of the sublimation interface in the porous plate is δ s (t), the thickness of the ice area inside the porous plate is δ pi (t), the thickness of the liquid area in the porous plate is δ pw (t), δ s (t) = δ pi (t)+δ f (t); For the porous plate ice area: The boundary conditions are: Where, T mi is the temperature of the ice zone of the porous plate, k mi is the equivalent thermal conductivity of the porous plate ice area, x is the coordinate along the height direction of the evaporation / sublimation heat sink, h s is the latent heat of sublimation of the working fluid, is the sublimation mass flow rate of the working fluid, T s is the sublimation interface temperature of the working fluid; There is an energy balance relationship at the ice-liquid interface and the ice-air interface: Where, ρ i is the density of ice.

6. The method for predicting evaporation / sublimation heat dissipation working parameters according to claim 1, characterized in that: During the evaporation process of the liquid working medium in the liquid supply cavity, the analytical solution of the effective area temperature during the evaporation process of the liquid working medium in the liquid supply cavity is: The analytical solution for the heat transfer heat flux in the effective area during the evaporation of the liquid working medium in the liquid supply cavity is: The equation for the phase change interface position during the evaporation of the liquid working medium in the liquid supply chamber is: Its initial condition is δ e (0)=0 Where t is time, ρ w is the density of the liquid working medium, α w is the equivalent thermal diffusion coefficient of the liquid area of ​​the liquid supply cavity, x is the coordinate along the height direction of the evaporation / sublimation heat sink, is the mass flow rate of the liquid supply, Q is the heat load of the evaporation / sublimation heat sink, A r is the heating area of ​​the evaporation / sublimation heat sink, T g is the supply liquid temperature, q w (x, t) represents the heat transfer flow, ierfc is the inverse residual error function, h e is the latent heat of vaporization of the liquid working medium.

7. The method for predicting evaporation / sublimation heat dissipation working parameters according to claim 6, characterized in that: The analytical solution for the temperature of the effective area involved in heat and mass transfer when the liquid working medium enters the porous plate and evaporates is: Liquid supply cavity temperature: in, Temperature of porous plate liquid zone: Where c2 = q w (δ w ,t), erf() is the error function, x2 is the coordinate along the thickness direction of the porous plate, α pw is the equivalent thermal diffusivity of the porous plate liquid area, k w is the equivalent thermal conductivity of the porous plate liquid area, T pin is the temperature at the interface between the porous plate and the liquid supply chamber, T e is the evaporation temperature, δ w is the thickness of the liquid supply cavity. The analytical solution for the heat transfer heat flux in the effective area participating in heat and mass transfer during the evaporation of the liquid working medium entering the porous plate is: Heat flow in the liquid supply cavity: in, t1 is the time it takes for the liquid working medium obtained through the evaporation process in the liquid supply chamber to fill the liquid supply chamber. The position of the phase change interface during the evaporation of the liquid working medium entering the porous plate is: Where σ is the surface tension of the liquid medium, r is the average pore size of the porous plate, θ is the contact angle between the liquid medium and the microporous wall of the porous plate, and P p is the supply pressure, P sat is the saturated vapor pressure of the evaporation interface, K is the permeability coefficient of the porous plate, ε is the porosity of the porous plate, ρ w is the density of the liquid working fluid, A r is the heating area of ​​the evaporation / sublimation heat sink, δ pw (t) is the thickness of the liquid region of the porous plate, μ is the dynamic viscosity of the liquid working medium, is the mass flow rate of the supply liquid, is the evaporation mass flow rate, which can be expressed by Get, among them, 8. The method for predicting evaporation / sublimation heat dissipation working parameters according to claim 7, characterized in that: The analytical solution for the temperature of the effective area involved in heat and mass transfer when the liquid working medium enters the porous plate and sublimates is: The temperature of the liquid supply cavity is: in, The temperature of the liquid zone of the porous plate is: Among them, T' pin is the temperature at the interface between the porous plate and the liquid supply chamber. The temperature of the ice zone of the porous plate is: Among them, α pw is the equivalent thermal diffusion coefficient of the porous plate liquid area, T f is the temperature of the ice-liquid interface, α pi is the equivalent thermal diffusion coefficient of the ice area of ​​the porous plate, x2 is the coordinate along the thickness direction of the porous plate, δ pi is the thickness of the ice zone on the porous plate, δ mw is the thickness of the liquid zone of the porous plate, h s is the latent heat of sublimation of ice, k mi is the equivalent thermal conductivity of the porous plate ice zone; The analytical solution of the heat transfer heat flux involved in heat and mass transfer during the sublimation of the liquid working medium into the porous plate is: Liquid area of ​​the liquid supply cavity: in, Among them, δ w is the thickness of the liquid supply cavity, q w is the heat transfer flow in the liquid supply cavity, δ s is the position of the sublimation interface, t2 is the duration of the evaporation process in the porous plate; The energy balance equation at the phase change interface during the sublimation of the liquid working medium into the porous plate is: Ice-liquid interface position: Sublimation interface location: The position of the phase change interface during the sublimation of the liquid working medium entering the porous plate is: Ice-liquid interface position: Sublimation interface location: in, Among them, d p is the particle size of the microparticles used to construct the porous plate, δ p is the thickness of the porous plate, k is the Boltzmann constant, m m is the mass of liquid working medium vapor molecules, P o is the environmental pressure, P sat is the saturated vapor pressure of the evaporation surface.

9. A method for obtaining evaporation / sublimation heat dissipation failure criterion, characterized in that: The method comprises steps (1) to (6) of the method for predicting working parameters of evaporation / sublimation heat dissipation according to any one of claims 1 to 8, and further comprises: Step (7): Obtain failure criteria based on the analytical solutions of the effective area temperature, heat transfer heat flux and phase change interface position in the three processes. The failure criteria are used to determine whether the evaporation / sublimation heat dissipation device has dried out or broken down.

10. The method for obtaining evaporation / sublimation heat dissipation failure criterion according to claim 9, characterized in that: The criteria for determining whether evaporation and drying do not occur during evaporation / sublimation heat dissipation operation are: in, is the mass flow rate of the liquid supply, h e is the latent heat of vaporization of the liquid working medium, c w is the equivalent specific heat of the liquid area of ​​the supply cavity, T w is the supply liquid temperature, α w is the equivalent thermal diffusivity of the liquid area in the liquid supply cavity; The criteria for judging whether "breakdown" occurs during evaporation / sublimation heat dissipation operation are: Among them, P p is the supply pressure, is the mass flow rate of the liquid working medium in the porous plate, δ p is the thickness of the porous plate, ρ w is the density of the liquid working medium, and ε is the porosity of the porous plate.

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