Based on the method that intrinsic light and heat information measures high temperature translucent medium thermal conductivity and absorptance simultaneously
Technical field
The present invention relates to the method simultaneously obtaining high temperature translucent medium temperature correlation thermal conductivity and band absorption coefficient, belong to translucent medium physical measurement technical field.
Background technology
High temperature translucent medium radiation physical property and thermal physical property parameter be translucent medium is analyzed in its application process, important parameter needed for Design and optimization. In recent years, along with developing rapidly of the modern high technologies such as the infrared characteristic of Aero-Space, infrared acquisition, target and environment, laser, electronic device, biomedicine, the translucent medium physical parameter that varies with temperature when high temperature, multidimensional becomes particularly important. The research carrying out participating medium heat radiation physical property and related discipline is respectively provided with significance for dual-use field.
The research of phase-change heat-storage material has great importance for thermal energy storage. Wherein the research for its thermal conductivity and absorptance is particularly important. Deeply understand this thermal physical property parameter and it is carried out experiment measuring and theory analysis in the field such as material science and solar energy thermal-power-generating, also there is important using value. And under normal circumstances, absorptance and spectral correlation, and thermal conductivity can change with material temperature. Therefore, for the measurement of the thermal conductivity varied with temperature and band absorption coefficient in actual application by significant.
Due in actual measurement process, there is certain measurement error in experimental facilities, be used alone light in some cases or thermal information can not to complete the resultant error measured or obtain of radiant heat physical property relatively big, and the inverting for the hot physical property of temperature correlation needs more metrical information.
Summary of the invention
A kind of method simultaneously measuring high temperature translucent medium temperature Thermal Conductivity Varying With Temperature and band absorption coefficient based on intrinsic light and heat information of offer is provided, to solve existing measuring method, to there is resultant error relatively big, and for problem that the inverting of the hot physical property of temperature correlation needs more metrical information.
The present invention solves that above-mentioned technical problem adopts the technical scheme that:
First the translucent medium will measured heats to temperature T0, then use the radiant intensity of detector measurement sample upper surface different directions. And use the Temperature Distribution of diverse location in thermocouple measurement medium. Using the measured result initial condition as inverse problem, then utilize the method that Particle Swarm Optimization obtains high temperature translucent medium temperature correlation thermal conductivity and band absorption coefficient simultaneously.
A kind of method simultaneously measuring high temperature translucent medium temperature Thermal Conductivity Varying With Temperature and band absorption coefficient of the present invention, concretely comprises the following steps:
Step one, by testing sample heating to a certain fixed temperature T0;
Step 2, stops heating, uses detector to measure the radiant intensity q (θ of its different directions at the upper surface of testing samplej), and use the temperature T within thermocouple measurement testing samplei, wherein, θjDiverse location residing for the radiation direction respectively different with i and thermocouple; As shown in Figure 1.
Step 3, utilizes reverse temperature intensity method, it is assumed that three key band absorptances of testing sample are κλ1, κλ2And κλ3, assume that the thermal conductivity that testing sample varies with temperature is λ (T)=a simultaneously1+a2·T+a3·T2; The unit of λ (T) is W/ (m K); A in formula1、a2、a3Represent three warm variable coefficients of thermal conductivity respectively;
Step 4, solves radiation transfer equation and Heat Conduction Differential Equations, it is thus achieved that testing sample interior temperature distribution Ti,est, lower footnote est represents value of calculation;
Step 5, utilizes the testing sample internal temperature T that step 2 obtainsiValue of calculation T corresponding with step 4i,est, in conjunction with formula:
Obtain the object function F in reverse temperature intensity algorithm1,obj, wherein n is total thermocouple number;
Step 6, it is judged that whether the object function in step 5 is less than setting threshold epsilon1, thermal conductivity λ (the Τ)=a of testing sample that if so, then will assume in step 31+a2·T+a3·T2W/ (m K) exports as a result and (namely exports a1、a2、a3Value), otherwise adopt Particle Swarm Optimization correction sample thermal conductivity and three key band absorptances, return step 4;
Step 7, warm Thermal Conductivity Varying With Temperature step 6 exported is as final sample thermal conductivity, and three key band absorptances step 6 exported are κλ1, κλ2And κλ3Initial value as Particle Swarm Optimization;
Step 8, solves radiation transfer equation and Heat Conduction Differential Equations, it is thus achieved that calculate the radiant intensity q of testing sample upper surface different directionsest(θj), lower footnote est represents value of calculation;
Step 9, utilizes the different directions radiant intensity q (θ measuring gained in step 2j) with step in corresponding value of calculation qest(θj), in conjunction with formula:
Obtain the object function F in Particle Swarm Optimization2,obj; Wherein, m is the direction number measuring the radiant intensity obtained;
Step 10, it is judged that whether the object function in step 8 is less than setting threshold epsilon2, if so, then by the band absorption coefficient κ of the testing sample of acquisitionλ1, κλ2And κλ3Export as a result, the method completing simultaneously to obtain high temperature translucent sample temperature Thermal Conductivity Varying With Temperature and band absorption coefficient, otherwise adopt three key band absorptances of Particle Swarm Optimization correction, and warm Thermal Conductivity Varying With Temperature step 6 exported is as sample thermal conductivity, returns step 8.
Step 4 and step 8 obtain the method in the temperature field in computational fields: utilize Heat Conduction Differential Equations
Realize, wherein ρ and cpRepresenting density and the specific heat capacity of testing sample respectively, T and h represents sample temperature and convection transfer rate respectively;QrRepresenting radiant heat flux density, wherein footnote w1 and w2 represents coboundary and the lower boundary of testing sample respectively; T∞Represent the temperature of surrounding fluid.
Step 4 and step 8 obtain the method for the radiation field intensity in computational fields: utilize radiation transfer equation
Realize, κ in formulaλkRepresenting the kth band absorption coefficient of testing sample, k represents different bands of a spectrum, and I represents radiant intensity, IbRepresenting the radiant intensity of black matrix at identical temperature, z represents thickness of sample; Ib,λkRepresent the radiant intensity of the kth bands of a spectrum of black matrix;
The method obtaining the heat flow density in Heat Conduction Differential Equations is: utilize equation
Realizing, in formula, ε represents the emissivity of testing sample upper surface, and σ represents this special fence-Boltzmann constant, Ib,λkRepresent the radiant intensity of the kth bands of a spectrum of black matrix.
The invention has the beneficial effects as follows:
The present invention provides a kind of method that experiment obtains high temperature translucent medium temperature correlation thermal conductivity and band absorption coefficient in conjunction with inversion algorithm simultaneously. The inventive method is based on intrinsic light and heat information and realizes. The measuring method that the present invention proposes introduces intrinsic light and heat information integration technology on the basis of reverse temperature intensity, it is possible to be greatly improved the precision for translucent medium thermophysical property measurement.
Measurement process use heater by translucent medium heating to a certain high temperature, by temperature-responsive (thermal signal) and own direction radiant intensity (optical signal) of detector measurement testing sample, indirectly obtain, finally by reverse temperature intensity technology, thermal conductivity and the spectral absorptance that testing sample varies with temperature. The present invention is by setting up the forward and inverse problem model of the translucent medium heat conduction radiation coupled and heat-exchange of thermal conductivity and the band absorption coefficient varied with temperature, under the premise that other parameters of medium are known, it is proposed that the method adopting Particle Swarm Optimization Simultaneous Inversion high temperature translucent medium temperature correlation thermal conductivity and band absorption coefficient. Basic ideas are the temperature-responsive and the direction radiant intensity own that record testing sample by experiment, the method simultaneously obtaining high temperature translucent medium temperature correlation thermal conductivity and band absorption coefficient then in conjunction with Particle Swarm Optimization.
The present invention is by setting up band absorption coefficient and the direct problem of translucent medium heat conduction radiation coupled and heat-exchange that thermal conductivity varies with temperature and reverse temperature intensity model, solve high temperature translucent medium temperature correlation thermal conductivity and many bands of a spectrum absorptance can not directly measure problem inaccurate with measurement result, it is proposed that a kind of method simultaneously obtaining high temperature translucent medium temperature correlation thermal conductivity and band absorption coefficient. Advantage is in that: model is simple, it is simple to theory solves; Adopt Particle Swarm Optimization, during this Algorithm for Solving optimization problem, have simple, efficient and sensitivity advantages of higher. This invention provides one method fast and accurately for researching high-temperature translucent medium temperature correlation thermal conductivity and many bands of a spectrum absorptance, and space flight, defense and commercial industry tool are of great significance.
Therefore say that the invention solves existing measuring method exists resultant error relatively greatly, and the problem of the inverting more metrical informations of needs for the hot physical property of temperature correlation. Measurement process use heater by translucent medium heating to a certain high temperature, intrinsic temperature by detector measurement testing sample responds and direction radiant intensity, indirectly obtains, finally by reverse temperature intensity technology, thermal conductivity and the band absorption coefficient that testing sample varies with temperature. By setting up the forward and inverse problem model of the translucent medium heat conduction radiation coupled and heat-exchange of thermal conductivity and the band absorption coefficient varied with temperature, under the premise that other parameters of medium are known, propose the method adopting Particle Swarm Optimization Simultaneous Inversion high temperature translucent medium temperature correlation thermal conductivity and band absorption coefficient, improve the precision for translucent medium thermophysical property measurement.
Accompanying drawing explanation
Fig. 1 is the experimental provision schematic diagram simultaneously obtaining high temperature translucent medium temperature correlation thermal conductivity and band absorption coefficient described in detailed description of the invention one.
Detailed description of the invention
The method simultaneously obtaining high temperature translucent medium temperature correlation thermal conductivity and band absorption coefficient described in detailed description of the invention one, present embodiment, the concrete operation step of the method is:
Step one, by testing sample heating to a certain fixed temperature T0;
Step 2, stops heating, uses detector to measure the radiant intensity q (θ of its different directions at the upper surface of testing samplej), and use the temperature T within thermocouple measurement testing samplei, wherein, θjDiverse location residing for the radiation direction respectively different with i and thermocouple; As shown in Figure 1.
Step 3, utilizes reverse temperature intensity method, it is assumed that three key band absorptances of testing sample are κλ1, κλ2And κλ3, assume that the thermal conductivity that testing sample varies with temperature is λ (T)=a simultaneously1+a2·T+a3·T2; The unit of λ (T) is W/ (m K);
Step 4, solves radiation transfer equation and Heat Conduction Differential Equations, it is thus achieved that testing sample interior temperature distribution Ti,est, lower footnote est represents value of calculation;
Step 5, utilizes the testing sample internal temperature T that step 2 obtainsiValue of calculation T corresponding with step 4i,est, in conjunction with formula:
Obtain the object function F in reverse temperature intensity algorithm1,obj, wherein n is total thermocouple number;
Step 6, it is judged that whether the object function in step 5 is less than setting threshold epsilon1, thermal conductivity λ (the Τ)=a of testing sample that if so, then will assume in step 31+a2·T+a3·T2W/ (m K) exports as a result, otherwise adopts Particle Swarm Optimization correction sample thermal conductivity and three key band absorptances, returns step 4;
Step 7, warm Thermal Conductivity Varying With Temperature step 6 exported is as final sample thermal conductivity, and three key band absorptances step 6 exported are κλ1, κλ2And κλ3Initial value as Particle Swarm Optimization;
Step 8, solves radiation transfer equation and Heat Conduction Differential Equations, it is thus achieved that calculate the radiant intensity q of testing sample upper surface different directionsest(θj), lower footnote est represents value of calculation;
Step 9, utilizes the different directions radiant intensity q (θ measuring gained in step 2j) with step in corresponding value of calculation qest(θj), in conjunction with formula:
Obtain the object function F in Particle Swarm Optimization2,obj; Wherein, m is the direction number measuring the radiant intensity obtained;
Step 10, it is judged that whether the object function in step 8 is less than setting threshold epsilon2, if so, then by the band absorption coefficient κ of the testing sample of acquisitionλ1, κλ2And κλ3Export as a result, the method completing simultaneously to obtain high temperature translucent sample temperature Thermal Conductivity Varying With Temperature and band absorption coefficient, otherwise adopt three key band absorptances of Particle Swarm Optimization correction, and warm Thermal Conductivity Varying With Temperature step 6 exported is as sample thermal conductivity, returns step 8.
The high temperature translucent medium transient radiation heat-transfer couple physical model that first present embodiment designs three key band absorptances and thermal conductivity varies with temperature, then set up corresponding mathematical model and method for solving, by measuring Temperature Distribution and the direction radiant intensity own obtaining testing sample, reverse temperature intensity reconstruction is utilized to go out temperature correlation thermal conductivity and the band absorption coefficient of high temperature translucent medium.
Detailed description of the invention two, present embodiment are further illustrating method described in detailed description of the invention one, and step 4 and step 8 obtain the method in the temperature field in computational fields and be: utilize Heat Conduction Differential Equations
Realize, wherein ρ and cpRepresenting density and the specific heat capacity of testing sample respectively, T and h represents temperature and convection transfer rate respectively;QrRepresenting radiant heat flux density, wherein footnote w1 and w2 represents coboundary and the lower boundary of testing sample respectively.
Detailed description of the invention three, present embodiment are further illustrating method described in detailed description of the invention one or two, and step 4 and step 8 obtain the method for the radiation field intensity in computational fields and be: utilize radiation transfer equation
Realize, κ in formulaλkRepresenting the kth band absorption coefficient of testing sample, k represents different bands of a spectrum, and I represents radiant intensity, IbRepresenting the radiant intensity of black matrix at identical temperature, z represents thickness of sample.
Detailed description of the invention four, present embodiment are further illustrating method described in detailed description of the invention one, two or three, and the method obtaining the heat flow density in Heat Conduction Differential Equations is: utilize equation
Realizing, in formula, ε represents the emissivity of testing sample upper surface, and σ represents this special fence-Boltzmann constant.