Method and system for enhancing nanoparticle radiant heat transport

Abstract

The invention provides a method and a system for enhancing radiation heat transport of nanoparticles. The method comprises the steps that nanoparticles are placed in a thermal radiation adjusting system, the thermal radiation adjusting system is provided with at least two second objects, at least one of the second objects has the nanoscale size, and the thermal radiation adjusting system is provided with at least two second objects containing a first element; based on first parameters of the nanoparticles, second parameters of the thermal radiation adjusting system are determined, so that excitation characteristics of local phonon polaritons of the second object are changed to improve thermal radiation flow of the thermal radiation adjusting system, and the first parameters comprise chemical compositions and shapes of the nanoparticles; the second parameter comprises at least one of the isotope type of the first element in the second object and the number of the second object. According to the method and the system, the radiation heat transfer coefficient of the nano particles can be greatly increased.

Description

Technical Field

[0001] The present application relates to the field of heat transfer regulation technology, specifically, to a method and system for enhancing radiative heat transport of nanoparticles, and in particular to a method for synergistically enhancing radiative heat transport of nanoparticles based on isotope effect and multi-body interaction. Background Art

[0002] Thermal radiation, as one of the three basic modes of heat transfer, plays a vital role in numerous natural phenomena and engineering systems. In the past few decades, near-field thermal radiation has attracted extensive attention due to its potential to achieve quasi-monochromatic emission and exceed the blackbody limit by several orders of magnitude. This provides a unique opportunity to utilize radiative heat transfer in various energy conversion and thermal management devices. Recently, it was theoretically discovered that the near-field radiative heat flow between two parallel polar dielectric plates can be enhanced by more than 1560 times through isotope engineering of surface phonon polaritons. With the continuous advancement of isotope-controlled material synthesis technology, the experimental demonstration and even practical application of this isotope effect may become increasingly feasible.

[0003] However, current methods and systems for enhancing radiative heat transport of nanoparticles, especially methods based on synergistic enhancement of radiative heat transport of nanoparticles based on isotope effect and multi-body interaction, still need further research and improvement. Summary of the invention

[0004] In view of the above problems, the present application provides a method and system for enhancing the radiative heat transport of nanoparticles. The method and system synergistically enhance the radiative heat transport of nanoparticles based on the isotope effect and multi-body interaction, so that the near-field heat flow can be greatly enhanced and the radiation heat transfer coefficient can be improved by several orders of magnitude.

[0005] In one aspect of the present application, a method for enhancing radiative heat transport of nanoparticles is proposed. The method comprises: placing the nanoparticle in a thermal radiation regulation system, the thermal radiation regulation system having at least two second objects, at least one of the second objects having a nanometer-scale size, the elements forming the nanoparticle having at least one first element, the first element being an element with a stable isotope, and the thermal radiation regulation system having at least two second objects containing the first element; based on the first parameter of the nanoparticle, determining the second parameter of the thermal radiation regulation system so that the excitation characteristics of the localized phonon polaritons of the second object change to increase the thermal radiation flow of the thermal radiation regulation system, the first parameter comprising the chemical composition and shape of the nanoparticle, the second parameter comprising at least one of the isotope type of the first element in the second object and the number of the second object.

[0006] This method can achieve a significant improvement in the radiation heat transfer coefficient by adjusting the second parameter while taking into account the isotope effect and the synergistic effect caused by the interaction of multiple objects.

[0007] According to an embodiment of the present invention, determining the second parameter of the thermal radiation regulation system based on the first parameter of the nanoparticles includes:

[0008] (1) calculating, when the thermal radiation regulating system only has the nanoparticle and one second object, the radiation heat transfer coefficient h between the nanoparticle and the second object when the second object has different chemical compositions and / or different shapes, so as to determine the chemical composition and / or shape of the second object;

[0009] The chemical composition of the second object is different, including: the chemical composition of the second object and the nanoparticle is the same, and the first element in the nanoparticle is replaced by an isotope;

[0010] (2) Calculating the heat transfer coefficient enhancement ratio Φ of the thermal radiation regulating system when the number of the second objects in the thermal radiation regulating system increases successively, so as to determine the number of the second objects.

[0011] According to an embodiment of the present invention, the radiation heat transfer coefficient h is a function of a specific operating temperature T and an inter-particle distance d, and the radiation heat transfer coefficient h is determined by the following formula:

[0012]

[0013] Among them, h ω is the spectral thermal conductivity, d is the distance between the nanoparticle and the second object,

[0014] τ(ω) is the energy transfer probability determined by the vector Green's function,

[0015] Θ(ω,T) is obtained by the following formula (2):

[0016]

[0017] in is the reduced Planck constant, k B is the Boltzmann constant.

[0018] According to an embodiment of the present invention, the heat transfer coefficient enhancement ratio Φ is determined by the following formula (3):

[0019]

[0020] Wherein, h is the radiation heat transfer coefficient between the nanoparticle and the second object, h minIt is the minimum radiation heat transfer coefficient between two objects in the thermal radiation regulation system.

[0021] According to an embodiment of the present invention, the nanoparticles and the second object support surface polaritons, and the number of objects participating in radiation heat transfer in the thermal radiation regulation system is greater than or equal to 3.

[0022] In another aspect of the present application, the present application proposes a thermal radiation regulation system. The thermal radiation regulation system is used to enhance the radiation heat transport of nanoparticles, the thermal radiation regulation system comprises at least two second objects, at least one of the second objects has a size in the nanometer scale, and the thermal radiation regulation system is configured to be able to adjust a second parameter of the thermal radiation regulation system based on a first parameter of the nanoparticles to enhance the thermal radiation flow of the thermal radiation regulation system, the first parameter comprises the chemical composition and shape of the nanoparticles, and the second parameter comprises at least one of the isotope type of the first element in the second object and the number of the second object.

[0023] The system can coordinate isotope correspondence and multi-body interaction to significantly improve the heat transfer coefficient enhancement ratio of the system.

[0024] According to an embodiment of the present invention, the shape of the second object includes at least one of a particle, a plate, a cavity and a columnar body.

[0025] According to an embodiment of the present invention, the thermal radiation conditioning system has at least one geometric dimension that is at least 10 times larger than the dimension of the nanoparticles. 2 times.

[0026] According to an embodiment of the present invention, the nanoparticles include c 11 BN particles, the second object includes c 11 BN particles, c 11 At least one of the BN plate and the Ag plate, the thermal radiation adjustment system has at least two of the c 11 BN particles, or at least one c 11 BN particles and a c 11 BN plate, or at least two Ag plates.

[0027] According to an embodiment of the present invention, adjusting the second parameter of the thermal radiation regulating system based on the first parameter of the nanometer example is performed using the method described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0029] Figure 1 This is a schematic diagram of the method for synergistically enhancing the radiative heat transport of nanoparticles based on the isotope effect and multi-body interaction in this application;

[0030] Figure 2 The relationship between the radiation heat transfer coefficient of a particle-plate two-body system with different isotopic compositions and the particle-plate distance;

[0031] Figure 3 is a graph showing the relationship between the phonon polariton excitation frequency of cubic boron nitride particles and plates and the ratio of boron isotopes;

[0032] Figure 4 The relationship diagram of the spectral radiation heat transfer coefficient of a particle-plate two-body system with different isotope compositions at two different particle-plate distances;

[0033] Figure 5 is a graph showing the relationship between the radiation heat transfer coefficient and the spacing in Example 1;

[0034] Figure 6 is another graph showing the relationship between the enhancement ratio of the heat transfer coefficient and the distance in Example 1;

[0035] Figure 7 is another graph showing the relationship between the enhancement ratio of the heat transfer coefficient and the distance in Example 1;

[0036] Figure 8 Another heat transfer coefficient enhancement ratio in Example 1 is a graph showing the relationship between the heat transfer coefficient enhancement ratio and the spacing.

[0037] Fig. 9 is a graph showing the relationship between the radiation heat transfer coefficient and the spacing in Example 2;

[0038] Fig.10 is another graph showing the relationship between the enhancement ratio of the heat transfer coefficient and the distance in Example 2;

[0039] Fig.11 is a graph showing the relationship between the enhancement ratio of a heat transfer coefficient and the distance in Example 3;

[0040] Fig.12 This is another graph showing the relationship between the enhancement ratio of the heat transfer coefficient and the distance in Example 3. DETAILED DESCRIPTION

[0041] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0042] In one aspect of the present application, a method for enhancing radiative heat transport of nanoparticles is proposed. The method comprises: placing the nanoparticle in a thermal radiation regulation system, the thermal radiation regulation system having at least two second objects, at least one of the second objects having a nanometer-scale size, the elements forming the nanoparticle having at least one first element, the first element being an element with a stable isotope, and the thermal radiation regulation system having at least two second objects containing the first element; based on the first parameter of the nanoparticle, determining the second parameter of the thermal radiation regulation system so that the excitation characteristics of the localized phonon polaritons of the second object change to increase the thermal radiation flow of the thermal radiation regulation system, the first parameter comprising the chemical composition and shape of the nanoparticle, the second parameter comprising at least one of the isotope type of the first element in the second object and the number of the second object.

[0043] This method can achieve a significant improvement in the radiation heat transfer coefficient by adjusting the second parameter while taking into account the isotope effect and the synergistic effect caused by the interaction of multiple objects.

[0044] In order to better understand the system and method proposed in this application, the following first explains the principle by which the method and system proposed in this application can achieve the above beneficial effects:

[0045] When free-space photons couple with polarized charges such as electrons, phonons, and excitons inside a material, quasiparticles are excited, which can break through the diffraction limitations of traditional optics and achieve subwavelength control of micro-nano devices. Among these quasiparticles, dielectric-supported phonon polaritons (SPhPs) play a dominant role in the infrared band. They can achieve ultra-low optical loss, long life, and high tunability. When the distance between the two radiators is less than the thermal wavelength corresponding to the temperature When the polaritons are coupled to the near-field, the radiation heat transfer coefficient can exceed the blackbody radiation limit by several orders of magnitude. This phenomenon is called near-field thermal radiation.

[0046] like Figure 1As shown in the figure, for two nanoparticles, radiation heat transfer is determined by the distance between the two particles and the radiation characteristics. When other objects are introduced, the radiation heat transfer channels of the system will increase. In addition, multi-body interactions will also affect the original radiation heat transfer path between the two particles. Overall, the radiation heat transfer coefficient between the two particles will be greatly enhanced. In addition, when the isotopic composition between the two radiators is different, their radiation heat transfer coefficient may change by three orders of magnitude.

[0047] Compared with the two-parallel-plate system, the multi-body system is more complex, but it also provides additional degrees of freedom for thermal control. This is because the electromagnetic environment of the two-body system can be significantly changed by adding objects, resulting in the emergence of unique nonlinear dynamics and collective behaviors in the multi-body system. With the rapid development of nanotechnology and materials science, the isotope ratio in the material can be precisely controlled, and large-area stable growth has gradually become possible, thus providing technical support for adjusting the chemical composition of other participating thermal radiation objects in the thermal radiation regulation system according to the isotope elements contained in the nanoparticles. Therefore, if some participating media in the multi-body system are isotopically engineered, the radiation heat transfer intensity between key substances can be further enhanced.

[0048] The essence of radiation heat transfer can be considered to be determined by the propagation probability of electromagnetic waves of different wave vectors at various frequency points between two radiators. Because the excitation frequencies of phonon polaritons of dielectrics of different geometric shapes are different, in the radiation heat transfer process of a multi-body system involving objects of different geometric shapes, the heat flow between radiators whose composition materials are not completely the same is necessarily the largest. If the material composition of the two radiators is different, when their geometric shapes are also different, the excitation frequencies of the polaritons of the two radiators may be closer, thereby greatly enhancing the propagation probability of electromagnetic waves between the two radiators.

[0049] Therefore, the method proposed in the present application not only considers the isotope effect, but also compares and examines the influence of multiple systems (i.e., the number of objects participating in radiation heat transfer in the system is greater than 2) on radiation heat transfer. Specifically, the method proposed in the present application determines the second parameter of the thermal radiation regulation system according to the first parameter of the nanoparticles, which may include first adjusting the isotopes contained in the second object in the thermal radiation regulation system, i.e., the type, quantity, abundance, etc. of the first element, and selecting the isotopic composition of the second object that can best enhance the radiation heat transfer. Subsequently, based on the determined isotopic composition of the second object, the number of particles in the thermal radiation regulation system is adjusted, and the radiation heat transfer is further enhanced through the action of multiple systems.

[0050] According to an embodiment of the present invention, the nanoparticles and the second object support surface polaritons, and the number of objects participating in radiation heat transfer in the thermal radiation regulation system may be greater than or equal to three.

[0051] In some embodiments, the nanoparticles are preferably selected from materials that have a large percentage of isotope ratio change in the overall change in relative molecular mass of the material and support localized surface polaritons. The second object is also preferably selected from a material that supports surface polaritons at the operating temperature, and can be the same as the nanoparticles or different from the nanoparticles.

[0052] According to a specific embodiment of the present application, determining the second parameter of the thermal radiation regulation system according to the first parameter of the nanoparticles may include the following steps:

[0053] (1) calculating, when the thermal radiation regulating system only has the nanoparticle and one second object, a radiation heat transfer coefficient h between the nanoparticle and the second object when the second object has different chemical compositions and / or shapes, so as to determine the chemical composition and / or shape of the second object;

[0054] (2) Calculating the heat transfer coefficient enhancement ratio Φ of the thermal radiation regulating system when the number of the second objects in the thermal radiation regulating system increases successively, so as to determine the number of the second objects.

[0055] Specifically, in step (1), the radiation heat transfer coefficient h between the nanoparticle and the second object is first calculated when there is only one nanoparticle to enhance radiation heat transfer and one second object in the thermal radiation regulation system, and the second object has different chemical compositions and / or shapes.

[0056] When considering a multi-body system, the isotopic composition and geometric shape of the objects involved in the radiation heat transfer have an important influence on the near-field thermal radiation. The following uses the radiation heat transfer characteristics of a particle-plate two-body system and the isotope effect therein as a sample to illustrate the influence of the isotope effect and the geometric shape of the object on the radiation heat transfer:

[0057] cBN (cubic boron nitride) with adjustable isotope nanoparticles 11 B isotopically enriched c 11 BN(0% 10 B) Taking the flat plate as the second object as an example, the influence of different isotope compositions and the shape of the second object on the radiation heat transfer coefficient h is explained:

[0058] It is specially noted here that, in order to maintain generality, in this embodiment, the chemical composition of the second object and the nanoparticles is first fixed, and the radiation heat transfer coefficient h between the particles and the second object is investigated when the distance between the particles and the second object increases from small to large under the shape of the second object:

[0059] Let the second object have a chemical composition of c 11 BN(containing 0% 10 B) plate, the nanoparticles are10 B isotopically enriched c 10 BN(100% 10 B) nanoparticles. Figure 2 The total radiation heat transfer coefficient of two cBN particles with different isotope ratios when the particle-plate distance D changes from 1 micron to 20 nanometers shows that as the particle-plate distance D decreases, the radiation heat transfer coefficient h increases significantly, which is a typical feature of near-field thermal radiation caused by photon tunneling due to polariton coupling. At the same time, when D is between 1 micron and 280 nanometers, c 11 BN particles-c 11 The radiation heat transfer coefficient of the BN flat plate combination is greater than c 10 BN particles-c 11 BN plate combination: The near-field enhancement effect between two parallel plates made of the same material is generally greater than that between different materials with lower electromagnetic mode matching. However, when D drops below 100 nm, the radiation heat transfer coefficient of the c10BN-c11BN (plate) combination remains higher.

[0060] The above results show that the mode matching condition between two objects depends not only on the material properties but also on the geometric shape. For radiators of different shapes, the excitation frequency of their polaritons is not the same. For example, the polariton excitation frequency of nanoparticles needs to satisfy ε(ω pt )=-2, and the polariton excitation frequency of the infinitely thick plate needs to satisfy ε(ω pl )=-1 condition.

[0061] refer to Figure 3 The excitation frequencies of the phonon polaritons of cubic boron nitride particles and plates vary with the ratio of boron isotopes as shown in the figure. Specifically, the excitation frequencies of the two phonon polaritons of cubic boron nitride materials of different geometric shapes vary with 10 B increases. For a certain isotope ratio, the excitation frequency ω of the phonon polaritons in the material plane pl It must be higher than the local phonon polariton excitation frequency ω of the particle pt :For c 11 BN, its ω pl and ω pt They are 2.338×10 14 rad / s and 2.287×10 14 rad / s; for c 10 BN, its ω pl and ω pt They are 2.402×10 14 rad / s and 2.35×10 14 rad / s.

[0062] That is, if these polaritons can be excited and coupled, c 10 Localized phonon polaritons and c 11 The surface phonon polaritons of the BN slab are closer, better matched, and more strongly coupled. Figure 4 , when D = 20 nm, c 10 BN particles-c 11 The radiation heat transfer coefficient between the BN plates is large, as shown by the spectral radiation heat transfer coefficient of the particle-plate two-body system with different isotopic compositions at D = 20 nm. Figure 4 As shown in Figure 2, at D = 1 μm, the coupling becomes weaker due to the exponential decay of these phonon resonance modes as the distance increases, and c 11 BN nanoparticles and c 11 The BN slab has stronger non-resonant mode contribution at lower frequencies, c 11 BN particles-c 11 The radiation heat transfer coefficient between the BN plates is larger.

[0063] The results of the above-mentioned embodiments indicate that, under certain working conditions, the radiation heat transfer coefficient between different geometric shapes or even different materials can be controlled by adjusting the isotope ratio.

[0064] In some preferred embodiments of the present application, the geometric dimensions of the nanoparticles can be much smaller than other geometric dimensions in the system to meet the dipole approximation description. Specifically, the radius of the nanoparticles is much smaller than other characteristic system dimensions, such as the distance between particles, the distance between particles and the plate, the thickness of the plate, the skin depth of the material, and the thermal wavelength. The above conditions can be obtained by adjusting the relevant parameters of the second object. Under the dipole approximation condition, the size of the nanoparticles does not affect the enhancement effect on the heat transfer coefficient in the present invention.

[0065] Preferably, the polarizability α can be used to measure the effect of the external electromagnetic field on the electron cloud around the particle, which determines the absorption, extinction and scattering of the particle. Under the dipole approximation, the optical polarizability α of the nanoparticle can be described by the Clausius-Mossotti formula:

[0066]

[0067] Here, R is the particle radius, ω is the angular frequency, and ε is the frequency-dependent complex dielectric function of the material.

[0068] When photons interact with particles such as electrons, phonons, and excitons inside a material, the response of particles inside the material to photons determines the material's absorption, transmission, and reflection properties, thereby determining the material's reflectivity, transmittance, and absorptivity to photons of a specific wavelength. According to the fluctuation-dissipation theorem, the radiation heat transfer coefficient between two radiators can be written as the aforementioned formula (1).

[0069] According to an embodiment of the present invention, unless otherwise specified, the radiation heat transfer coefficient h is a function of a specific operating temperature T and an inter-particle distance d. Specifically, the radiation heat transfer coefficient h is determined by the following formula:

[0070]

[0071] Among them, h ω is the spectral thermal conductivity, d is the distance between the nanoparticle and the second object,

[0072] τ(ω) is the energy transfer probability determined by the vector Green's function,

[0073] Θ(ω,T) is obtained by the following formula (2):

[0074]

[0075] in is the reduced Planck constant, k B is the Boltzmann constant.

[0076] In this application, unless otherwise specified, those skilled in the art can determine the energy transfer probability τ(ω) by using a vector Green's function according to actual needs. The vector Green's function is a common tool used to describe the response of a vector field, which represents the vector field generated at a given position and direction due to the application of a vector point source at another position.

[0077] Thus, according to the above operation, the isotope situation and / or shape of the second object can be changed, such as making the second object a flat plate, particle or other shaped object, and calculating the radiation heat transfer coefficient h between the second object and the nanoparticle when the isotope abundance, isotope type and / or shape are different, and determining the situation of the second object when the enhancement effect is greater. Then, the above step (2) can be performed:

[0078] The heat transfer coefficient enhancement ratio Φ of the thermal radiation regulating system is calculated when the number of the second objects in the thermal radiation regulating system increases successively to determine the number of the second objects.

[0079] As mentioned above, after adding other objects into the system, especially when there are two nanoparticles in the system, the local electromagnetic state density between the two nanoparticles can be better matched in a wider spectrum range, and the radiation heat transfer coefficient will be significantly enhanced. If the isotope effect between the two nanoparticles is adjusted at the same time, the synergistic effect of the radiation heat transfer coefficient between the two nanoparticles can be greatly improved, even up to eight orders of magnitude.

[0080] Specifically, in step (2), the number of second objects in the thermal radiation regulating system may be increased sequentially, and the heat transfer coefficient enhancement ratio Φ of the thermal radiation regulating system may be calculated. According to an embodiment of the present invention, the heat transfer coefficient enhancement ratio Φ is determined by the following formula (3):

[0081]

[0082] Wherein, h is the radiation heat transfer coefficient between the nanoparticle and the second object, h min It is the minimum radiation heat transfer coefficient between two objects in the thermal radiation regulation system.

[0083] For example, in some specific embodiments, the number of second objects in the system can be increased in sequence according to the situation of the second object determined in step (1), and the value of the heat transfer coefficient enhancement ratio Φ of the system is calculated for each increase of the second object, and the number of second objects when the value of Φ is larger is selected to determine the number of objects in the thermal radiation regulation system. In this way, based on the isotope effect, the exponential enhancement of radiation heat transfer can be achieved through the action of multiple systems.

[0084] In another aspect of the present application, the present application proposes a thermal radiation regulation system. In some embodiments, the system can utilize the aforementioned method to achieve the thermal radiation enhancement effect of nanoparticles.

[0085] According to an embodiment of the present application, a thermal radiation regulation system is used to enhance the radiation heat transport of nanoparticles, the thermal radiation regulation system comprising at least two second objects, at least one of the second objects having a size at the nanoscale, the thermal radiation regulation system being configured to be able to adjust a second parameter of the thermal radiation regulation system based on a first parameter of the nanoparticles to improve the radiation heat transfer coefficient of the thermal radiation regulation system, the first parameter comprising the chemical composition and shape of the nanoparticles, the second parameter comprising at least one of the isotope type of the first element in the second object and the number of the second objects.

[0086] The system can coordinate isotope correspondence and multi-body interaction to significantly improve the heat transfer coefficient enhancement ratio of the system.

[0087] According to an embodiment of the present invention, the shape of the second object includes at least one of a particle, a plate, a cavity, and a columnar body.

[0088] According to an embodiment of the present invention, the thermal radiation conditioning system has at least one geometric dimension that is at least 10 times larger than the dimension of the nanoparticles. 2 times. For example, at least one of the multiple geometric dimensions of the second object can be made much larger than the size of the nanoparticles, so that the system of the nanoparticles and the second object can be suitable for dipole approximation description: the geometric dimensions of the nanoparticles are much smaller than other geometric dimensions to meet the requirements of dipole approximation description. Specifically, the radius of the nanoparticles is much smaller than other characteristic system dimensions, such as the distance between particles, the distance between particles and the plate, the thickness of the plate, the skin depth of the material, and the thermal wavelength. Under the dipole approximation conditions, the size of the nanoparticles does not affect the enhancement effect on the heat transfer coefficient in the present invention, so it has a wider range of application scenarios.

[0089] According to an embodiment of the present invention, the nanoparticles include c 11 BN particles, the second object includes c 11 BN particles, c 11 At least one of the BN plate and the Ag plate, the thermal radiation adjustment system has at least two of the c 11 BN particles, or at least one c 11 BN particles and a c 11 BN plate, or at least two Ag plates.

[0090] According to an embodiment of the present invention, adjusting the second parameter of the thermal radiation regulating system based on the first parameter of the nanometer example is performed using the method described above.

[0091] In general, the method proposed in this application can achieve a significant enhancement of the thermal radiation of nanoparticles, and the radiation heat transfer coefficient h can be enhanced by several orders of magnitude.

[0092] The above-mentioned method and system of the present application are described in detail below through specific examples. In the following examples, unless otherwise specified, R represents the radius of the nanoparticle, which is 5nm to meet the dipole approximation condition, d represents the distance between the two farthest nanoparticles, the temperature of the high-temperature nanoparticles is set to 300.01K, and the temperature of the low-temperature nanoparticles is set to 300K. Cubic boron nitride is selected as the nanoparticle material to ensure that its phonon polaritons can be excited at the set temperature. Among them, the isotope ratio of the boron element in cubic boron nitride is adjustable. It should be specially noted here that in the embodiments, only two cubic boron nitride materials with different isotopic enrichments are considered, namely c 10 BN and c 11 BN.

[0093] Embodiment 1:

[0094] refer to Figure 5 , the distance d between the two nanoparticles at the edge ranges from 10R to 2000R; first consider the combination of only two nanoparticles, when the isotope combination of the two nanoparticles is c 11 BN-c 10 When BN, the radiation heat transfer coefficient is Figure 5 shown by the lower dashed line.

[0095] Furthermore, when only the mass effect of isotopes is considered, c 10 BN nanoparticles were replaced by c 11 BN nanoparticles, forming c 11 BN-c 11 BN combination. Furthermore, only the material composition of the isotope mass effect is considered to be completely consistent with the c 11 BN-c 11 The radiation heat transfer coefficient of the BN nanoparticle combination is greatly enhanced at all particle spacings. When d = 10R, the original c 11 BN-c 10 The radiation heat transfer coefficient between the BN nanoparticles was enhanced by 4400 times. The heat transfer coefficient enhancement ratio increased with the increase of the particle spacing. When the distance between the nanoparticles was large, the radiation heat transfer coefficient enhancement ratio was 5530.

[0096] Furthermore, when only multi-body interactions are considered, in the original c 11 BN-c 10 Insert a c 11 BN nanoparticles, using the interaction between the introduced nanoparticles and the original particles to form c 11 BN-c 11 BN-c 10 BN three-particle system, radiation heat transfer coefficient comparison Figure 6 shown.

[0097] Furthermore, when considering only multi-body interactions, 11 BN-c 11 BN-c 10 In the BN three-particle system, the original c 11 BN-c 10 The radiation heat transfer coefficient between BN nanoparticles is enhanced only when the interparticle distance is smaller (d < 30R). 11 BN-c 10 The radiation heat transfer coefficient between the BN nanoparticles was enhanced by 17 times. Since the localized surface phonon polaritons of nanoparticles decay exponentially with distance, the multi-body interaction of the above three-body system becomes extremely weak when the distance between the nanoparticles is large. 11 BN-c11 BN-c 10 The enhancement effect of the BN three-particle system on the heat transfer coefficient is almost zero.

[0098] Furthermore, it can be seen from the above results that the three-particle system formed by considering only the multi-body interaction without considering the isotope effect is different from the original c 11 BN-c 10 Compared with BN nanoparticles, the radiation heat transfer coefficient enhancement effect is very limited, which is two orders of magnitude smaller than the enhancement ratio of the heat transfer coefficient using the isotope effect in a two-body system.

[0099] Furthermore, in Example 1, the isotope effect is taken into account and multi-body interaction is introduced to form a three-particle system with adjustable isotopes. The radiation heat transfer coefficient is compared with Figure 7 As shown in the schematic diagram.

[0100] like Figure 7 As shown, in the three-particle system with multiple isotopes adjustable in this embodiment 1, the original c 11 BN-c 10 Compared with BN nanoparticles, c 11 BN-c 11 BN-c 11 The radiation heat transfer coefficient of the BN three-particle system is sharply enhanced at all spacings.

[0101] When the spacing is small (d<34R), c 11 BN-c 11 BN-c 11 The heat transfer coefficient of the BN three-particle system can be enhanced by 4 orders of magnitude. 11 BN-c 11 BN-c 11 When the distance between the two outermost particles in the BN three-particle system is d = 10R, except for the three c 11 In addition to the very strong localized phonon polariton resonance between BN particles, there is also a configuration resonance in the system caused by the interaction of three particles at a relatively close distance, and the heat transfer coefficient is enhanced by a ratio of 16464.

[0102] When c 11 BN-c 11 BN-c 11 When the distance between the two outermost particles in the BN three-particle system is d=16R, the maximum heat transfer coefficient enhancement ratio can reach 55700. This enhancement effect is at least one order of magnitude higher than that of the single isotope effect or the three-particle system with unadjustable isotopes. When the distance between the nanoparticles is large, due to the attenuation of the localized phonon polaritons, the heat transfer coefficient enhancement ratio approaches the result of considering only the isotope effect, which is 5530.

[0103] refer to Figure 8The comparison of the enhancement ratio of the radiation heat transfer coefficient shown in the figure shows that when only the isotope effect and the influence of multi-body interaction on the enhancement ratio of the radiation heat transfer coefficient are considered, the three-particle system with multiple isotopes adjustable has the largest enhancement ratio of the heat transfer coefficient at all distances.

[0104] Embodiment 2:

[0105] Select c in Example 1 11 BN-c 10 The combination of BN two nanoparticles is a reference benchmark for the effect of the present invention.

[0106] The difference from Example 1 is that the third object introduced in this example is not an isotope-tunable particle, but an isotope-tunable cBN plate (pl).

[0107] Specifically, based on Example 1, an isotope-adjustable particle-plate system is formed, referring to Fig. 9 When the distance between the two particles and the plate is d = 6R (ie d / R = 6), the original c 11 BN-c 10 Compared with the BN two-nanoparticle system, c 11 BN-c 11 BN-c 11 The radiation heat transfer coefficient of the particle-plate system in BN(pl) is enhanced by more than three orders of magnitude at all spacings.

[0108] When c 11 BN-c 11 BN-c 11 When the distance between the two edge particles in the BN(pl) particle-plate system is d=10R, the localized phonon polariton resonance between the two particles plays a dominant role. 11 BN-c 10 BN two-particle combination, such as Fig.10 As shown, the heat transfer coefficient enhancement ratio is 5510.

[0109] Furthermore, if Fig.10 As shown, when c 11 BN-c 11 BN-c 11 When the distance between the two edge particles in the BN(pl) particle-plate system is d = 400R, the localized phonon polaritons between the two particles decay sharply, but the c 11 At this time, the importance of the BN plate as a new radiation transmission channel is highlighted.

[0110] Furthermore, if Fig.10As shown in the figure, due to the small distance between the particles and the plate (i.e., d / R = 6), there is also strong mode coupling between the nanoparticles and the plate, which plays a dominant role when d = 400R. 11 BN-c 10 The maximum heat transfer coefficient enhancement ratio of the BN two-particle combination is 3.48×10 8 , that is, the heat transfer coefficient is enhanced by more than 8 orders of magnitude.

[0111] Embodiment 3:

[0112] The difference from Example 1 and Example 2 is that in this embodiment, two silver plates are introduced as the second object. The thickness of the two silver plates is 1 micron. The two 1-micron-thick silver plates form a parallel silver cavity, which confines the two nanoparticles in the cavity to form an isotope-adjustable particle-silver cavity multi-body system, such as Fig.11 shown.

[0113] In this embodiment 3, when the distance H between the two silver plates is 10R, Fig.11 As shown, compared with the original c 11 BN-c 10 Compared with the BN two-nanoparticle system, the Ag-c 11 BN-c 11 The radiation heat transfer coefficient of the BN-Ag particle-silver cavity multi-body system is enhanced by nearly two orders of magnitude at all spacings.

[0114] Furthermore, when d = 22R, due to the absorption of the thermal radiation energy of the high-temperature particles by the non-resonant frustrated mode of the silver cavity material, the formed Ag-c 11 BN-c 11 The heat transfer coefficient enhancement ratio of the BN-Ag particle-silver cavity multi-body system is the smallest, only 90.

[0115] Furthermore, when d>22R, since the silver cavity material confines the radiation energy between the two particles to the cavity, considering the conservation of energy, the enhancement effect of the silver cavity on the heat transfer coefficient between the two nanoparticles increases with the increase of the spacing, reaching eight orders of magnitude within the maximum spacing range (d>945R).

[0116] Embodiment 4:

[0117] Different from Example 3, the enhancement ratio of the radiation heat transfer coefficient between two nanoparticles is determined by using different cavity materials that support the surface wave excitation frequency.

[0118] Although the silver cavity material enhances the radiation heat transfer coefficient between nanoparticles by more than two orders of magnitude, the surface mode of the silver material can only be excited in the ultraviolet band and cannot produce mode resonance with nanoparticles that support surface excitons in the infrared band. The heat transfer coefficient enhancement ratio can be further improved.

[0119] In this embodiment, it is assumed that the dielectric function of the cavity material can be described by using the Durood model.

[0120] Furthermore, the Durood model can be expressed as:

[0121]

[0122] For simplicity, this embodiment 4 assumes that ε ∞ =4, and Γ is fixed to 1×10 11 rad / s. By controlling the surface equivalent plasma frequency of the hypothetical material to ω p is a key parameter that can achieve mode resonance matching or mismatch between the cavity wall material and the two nanoparticles in the cavity.

[0123] The thickness of the imaginary cavity material plate in Example 4 is 1 micron. Fig.12 As shown in the figure, after forming a particle-hypothetical material cavity four-body system, the heat transfer coefficient enhancement ratio is ω by isotope engineering the particles in the cavity. p Very sensitive.

[0124] refer to Fig.12 , in ω p =2.561×10 14 rad / s, the formed Hypo-c 11 BN-c 11 The radiation heat transfer coefficient of the BN-Hypo combination can be compared to c 11 BN-c 10 The BN two-particle combination is seven orders of magnitude larger.

[0125] When p =2.561×10 14 rad / s, the cavity material can be 11 BN nanoparticles produce strong mode resonance, and the cavity confines the heat flow to propagate within the cavity, so that the particle-hypothetical material cavity four-body system can achieve a heat transfer coefficient enhancement of seven orders of magnitude.

[0126] Furthermore, in contrast, when ω p Gradually away from 2.561×10 14 rad / s, the surface mode corresponding to the cavity material cannot be connected with c 11 BN nanoparticles produce resonance, and the heat transfer coefficient enhancement ratio drops sharply.

[0127] When p Less than 2×10 14 rad / s or greater than 4.4×10 14 rad / s, the heat transfer coefficient is enhanced to below 6000.

[0128] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0129] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0130] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0131] Unless otherwise specified, the terms used in this application have the commonly known meanings generally understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this application).

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for enhancing radiative heat transport of nanoparticles, characterized in that: include: The nanoparticles are placed in a thermal radiation conditioning system, wherein the thermal radiation conditioning system has at least two second objects, at least one of the second objects has a size in the nanometer range, The elements forming the nanoparticles include at least one first element, the first element is an element with a stable isotope, and the thermal radiation adjustment system includes at least two second objects containing the first element; Based on the first parameter of the nanoparticle, a second parameter of the thermal radiation regulation system is determined, so that the excitation characteristics of the localized phonon polaritons of the second object are changed to increase the thermal radiation flow of the thermal radiation regulation system, The first parameter includes the chemical composition and shape of the nanoparticles, The second parameter includes at least one of an isotope type of the first element in the second object and a quantity of the second object.

2. The method according to claim 1, characterized in that Based on the first parameter of the nanoparticles, determining the second parameter of the thermal radiation regulation system comprises: (1) calculating, when the thermal radiation regulating system only has the nanoparticle and one second object, the radiation heat transfer coefficient h between the nanoparticle and the second object when the second object has different chemical compositions and / or different shapes, so as to determine the chemical composition and / or shape of the second object; The chemical composition of the second object includes: the chemical composition of the second object and the nanoparticle is the same, and the first element in the nanoparticle is replaced by an isotope; (2) Calculating the heat transfer coefficient enhancement ratio Φ of the thermal radiation regulating system when the number of the second objects in the thermal radiation regulating system increases successively, so as to determine the number of the second objects.

3. The method according to claim 2, characterized in that The radiation heat transfer coefficient h is a function of a specific operating temperature T and a distance d between particles. The radiation heat transfer coefficient h is determined by the following formula: Among them, h ω is the spectral thermal conductivity, d is the distance between the nanoparticle and the second object, τ(ω) is the energy transfer probability determined by the vector Green's function, Θ(ω,T) is obtained by the following formula (2): in is the reduced Planck constant, k B is the Boltzmann constant.

4. The method according to claim 3, characterized in that The heat transfer coefficient enhancement ratio Φ is determined by the following formula (3): Wherein, h is the radiation heat transfer coefficient between the nanoparticle and the second object, h min It is the minimum radiation heat transfer coefficient between two objects in the thermal radiation regulation system.

5. The method according to any one of claims 1 to 4, characterized in that: The nanoparticles and the second object support surface polaritons, and the number of objects participating in radiation heat transfer in the thermal radiation regulation system is greater than or equal to 3.

6. A thermal radiation regulation system, characterized in that: The thermal radiation regulation system is used to enhance the radiative heat transport of nanoparticles, and the thermal radiation regulation system comprises: at least two second objects, at least one of the second objects having a size in the nanometer range, The thermal radiation regulation system is configured to adjust a second parameter of the thermal radiation regulation system based on the first parameter of the nanostructured sample to increase the thermal radiation flow of the thermal radiation regulation system. The first parameter includes the chemical composition and shape of the nanoparticles, The second parameter includes at least one of an isotope type of the first element in the second object and a quantity of the second object.

7. The heat radiation adjustment system according to claim 6, characterized in that: The shape of the second object includes at least one of a particle, a plate, a cavity, and a columnar body.

8. The heat radiation adjustment system according to claim 6 or 7, characterized in that: The thermal radiation regulating system has at least one geometric dimension that is at least 10 times larger than the dimension of the nanoparticles. 2 times.

9. The heat radiation adjustment system according to claim 8, characterized in that: The nanoparticles include c 11 BN particles, The second object includes c 11 BN particles, c 11 At least one of the BN plate and the Ag plate, The thermal radiation adjustment system has at least two 11 BN particles, or at least one c 11 BN particles and a c 11 BN plate, or at least two Ag plates.

10. The heat radiation adjustment system according to claim 6, characterized in that: The adjusting of the second parameter of the thermal radiation regulating system based on the first parameter of the nano-example is performed by using the method described in any one of claims 1-5.

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