Thermal conductivity prediction of 2- dimensional square-pore metallic nanoporous materials with kinetic method approach

Huang, Congliang; Lin, Zizhen; Feng, Yanhui; Zhang, Xinxin; Wang, Ge

doi:10.1016/j.ijthermalsci.2016.09.033

Cited by 15 publications

(8 citation statements)

References 68 publications

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“…Heat transfer is by conduction. The heat flux qy in the y-direction is related to the temperature gradient by Fourier's law qy = −k ∂T ∂y (12) where k denotes the thermal conductivity, with heat considered to be transferred predominantly by free electrons in the case of sufficiently pure metals [2,6]. In the metal, energy carriers (free electrons) may reach plane y from the top or bottom (Figure 1).…”

Section: Theoretical Formulation Of Heat Conduction and Thermal Condumentioning

confidence: 99%

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Formulation of heat conduction and thermal conductivity of metals

Chebbi

2019

Open Physics

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The well-known low-pressure monatomic gas thermal conductivity expression is based on the Maxwell-Boltzmann velocity distribution and involves the mean particle velocity, the gas heat capacity at constant volume and the particle mean free path. The extension of the formula to a free electron Fermi gas, using the Fermi velocity along with the Sommerfeld electronic heat capacity, was demonstrated in the literature using the Boltzmann transport equation. A different formulation of heat conduction in sufficiently pure metals, yielding the same formula for the thermal conductivity, is provided in the present investigation using the free electron Fermi gas energy distribution with the thermal conductivity determined from the net heat transfer occurring due to random motions of the free electrons in the presence of temperature gradient. Potential applications of this approach include extension of the present kinetic model incorporating quantum effects to cases in which electron scattering occurs such as in nanowires and hollow nanowires.

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Section: Theoretical Formulation Of Heat Conduction and Thermal Condumentioning

confidence: 99%

“…The impact of Brownian motion on the thermal conductivity enhancement factor is discussed in [9,11]. Other new materials having high thermal conductivities include metal foams, materials combining nanomaterials and nanofoams [7], and metallic nanoporous materials [12].…”

Section: Introductionmentioning

confidence: 99%

Formulation of heat conduction and thermal conductivity of metals

Chebbi

2019

Open Physics

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“…To probe the capacity of the wood to maintain heat, the dry‐wood and wet‐wood thermal conductivities were both measured . The dry‐wood thermal conductivity is about 0.37 W·m −1 ·K −1 measured by hot‐wire method, much smaller than the one of water which is about 0.60 W·m −1 ·K −1 . The low thermal conductivity can inhibit heat transporting into the bulk water.…”

Section: Materials and Experiments Systemmentioning

confidence: 99%

“…[34][35][36][37][38] The dry-wood thermal conductivity is about 0.37 W·m −1 ·K −1 measured by hot-wire method, [39][40][41][42] much smaller than the one of water which is about 0.60 W·m −1 ·K −1 . [43][44][45][46] The low thermal conductivity can inhibit heat transporting into the bulk water. Because the bottom-layer wood floats in the water, it is also essential to study the wet-wood thermal conductivity, which was measured to be of 0.401 W·m −1 ·K −1 , greater than that of the dry wood but less than that of the water.…”

Section: Bottom-layer Woodmentioning

confidence: 99%

High performance of carbon-particle/bulk-wood bi-layer system for solar steam generation

et al. 2018

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Summary To relieve the fresh water shortage, bi‐layer systems have been widely applied to give high efficiencies of solar steam generation. In current work, a bi‐layer system (C‐wood) is obtained with the low‐cost carbon particles as the light absorbing layer and the boxwood as the supporting layer. The application of wood could lead to both good water transportation and good local heat management in the system, and carbon particles could supply a high light absorptivity at a broad optical absorption wave bands (mostly larger than 98%), which results from the complex three‐dimensional porous structure formed by the wide‐size‐distribution carbon particles. Because simultaneously possessing a high light absorptivity, good water transportation, and good local heat management, the C‐wood system gives a 65% evaporation efficiency under an illumination power of 1 sun. This system is also durable for a future industry applications. Comparing the energy loss of the C‐wood system in the evaporation process with the ones of other systems prepared in this work, we conclude that a low top‐surface reflection of light of the C‐wood system should be responsible for the high evaporation efficiency. It demonstrates that the carbon particle is a promising material for an application in solar steam generation systems for easily accessible resources, low cost, and effective light absorptivity.

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“…A large number of interests have been focused on finding novel first-layer nanomaterials for high efficiency of light absorbing, such as, gold nanoparticle [11][12][13][14], graphene [15,16], carbon black nanoparticles [17,18], carbon foam [10,19], activated carbon [20] and carbon nanotubes [21]. The porous material is usually applied as the second layer material because of its high capillary effect and low thermal conductivity [22][23][24][25][26], such as wood [27,28], carbonized wood [29], carbonized mushrooms [30], and cellulose nanofibers [31]. Although a large number of studies have been carried out to look for cheaper and more efficient materials to increase the evaporation rate of the bi-layered structure for solar steam generation, to our knowledge, there is still no detailed study about the influence factors of the evaporation process in a bi-layer system, especially the ambient air velocity, the porosity of the second layer, etc.…”

Section: Introductionmentioning

confidence: 99%

Influence factors of the evaporation rate of a solar steam generation system: A numerical study

Zhong

Huang

et al. 2019

International Journal of Heat and Mass Transfer

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Many efforts have been dedicated to improve the solar steam generation by using a bi-layer structure. In this paper, a two-dimensional mathematical model describing the water evaporation in a bi-layer structure is firstly established and then the finite element method is used to simulate the effects of different influence factors on the evaporation rate. Results turn out that: besides the high solar energy absorptivity of the first-layer, an optimum porosity of the second-layer porous material should be applied and the optimum porosity is about 0.45 in this work. This optimum porosity is determined by the balance between the positive effect of the lowering effective thermal conductivity of the second layer and the negative effect of the reduced vapor diffusivity in the second layer when the porosity is decreased. The influence of the thermal conductivity of the second-layer porous material is negligible because the effective thermal conductivity of the second layer is determined by the porosity while a larger porosity means more water in the second layer. The ambient air velocity could greatly enhance the evaporation rate, and the evaporation rate will decrease linearly with the increase of the air relative humidity. This study is expected to supply some information for developing a more effective bi-layer solar steam generation system.

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Thermal conductivity prediction of 2- dimensional square-pore metallic nanoporous materials with kinetic method approach

Cited by 15 publications

References 68 publications

Formulation of heat conduction and thermal conductivity of metals

Formulation of heat conduction and thermal conductivity of metals

High performance of carbon-particle/bulk-wood bi-layer system for solar steam generation

Influence factors of the evaporation rate of a solar steam generation system: A numerical study

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