Bradley Doleman^a , Messiha Saad^a,*

Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-8, 2013, DOI:10.5098/hmt.v4.2.3006

Abstract Thermal diffusivity, specific heat, and thermal conductivity are important thermophysical properties of composite materials. These properties play a significant role in the engineering design process of space systems, aerospace vehicles, transportation, energy storage devices, and power generation including fuel cells. This paper examines these thermophysical properties of the AS4/3501-6 composite using the xenon flash method to measure the thermal diffusivity in accordance with ASTM E1461 and differential scanning calorimetry to measure the specific heat in accordance with ASTM E1269. The thermal conductivity was then calculated using a proportional relationship between the density, specific heat, and More >

Hyoe Hatakeyama^1,*, Tatsuko Hatakeyama²

Journal of Renewable Materials, Vol.1, No.2, pp. 113-123, 2013, DOI:10.7569/JRM.2012.634111

Abstract Lignin and saccharides are two major components of plants. Huge amounts of plant residues are obtained as by-products of large-scale industries, such as pulp and paper, bio-fuel and the food industry. In this paper, preparation of polyurethane (PU) foam directly from various kinds of industrial lignin and molasses, which have scarcely been utilized, is summarized based on our results obtained by recent investigation. A onestep reaction using hydroxyl groups of plant materials as an active site makes it possible to produce a wide variety of PU, such as foams, sheets, gels and composite matrix. In More >

S.-A. B. Al Omari^1,2, E. Elnajjar¹

FDMP-Fluid Dynamics & Materials Processing, Vol.9, No.2, pp. 91-109, 2013, DOI:10.3970/fdmp.2013.009.091

Abstract In a previous numerical study (Al Omari, Int. Communication in Heat and Mass Transfer, 2011) the heat transfer enhancement between two immiscible liquids with clear disparity in thermal conductivity such as water and a liquid metal (attained by co- flowing them in a direct contact manner alongside each other in mini channel) was demonstrated. The present work includes preliminary experimental results that support those numerical findings. Two immiscible liquids (hot water and liquid gallium) are allowed experimentally to exchange heat (under noflow conditions) in a stationary metallic cup where they are put in direct contact.… More >

Yuhang Jing¹, Ming Hu^2,3

CMC-Computers, Materials & Continua, Vol.38, No.1, pp. 43-59, 2013, DOI:10.3970/cmc.2013.038.043

Abstract Nanostructuring of thermoelectric materials bears promise for manipulating physical parameters to improve the energy conversion efficiency of thermoelectrics. In this paper the thermal transport in Si/Ge superlattice nanotubes is investigated by performing nonequilibrium molecular dynamics simulations aiming at realizing low thermal conductivity by surface roughening. Our calculations revealed that the thermal conductivity of Si/Ge superlattice nanotubes depends nonmonotonically on periodic length and increases as the wall thickness increases. However, the thermal conductivity is not sensitive to the inner diameters due to the strong surface scattering at thin wall thickness. In addition, introducing roughness onto the More >

Zichun Yang^1,2,3, Gaohui Su^1,4, Fengrui Sun¹

CMC-Computers, Materials & Continua, Vol.36, No.3, pp. 271-292, 2013, DOI:10.3970/cmc.2013.036.271

Abstract In this paper, we investigate the radiative properties and the effective thermal conductivity (ETC) of the opacified silica aerogel by theoretical method. The radiative properties of the opacified silica aerogel are obtained by the modified Mie Scattering Theory that is used for particle scattering in absorbing medium. The modified gamma distribution is used to take account of the non-uniformity of the particle size. The solid thermal conductivity of the composite material is obtained by considering the scale effect of the particles. Based on these calculated thermophysical properties the coupled heat conduction and radiation through the More >

Wei-Chung Tien¹, Yue-Tzu Yang¹, Cha’o-Kuang Chen^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.2, pp. 155-170, 2012, DOI:10.3970/cmes.2012.084.155

Abstract In this paper, the homotopy analysis method is applied to analyze the heat transfer of the oscillating base temperature processes occurring in a convective rectangular fin with variable thermal conductivity. This method is a powerful and easy-to-use tool for non-linear problems and it provides us with a simple way to adjust and control the convergence region of solution series. Without the need of iteration, the obtained solution is in the form of an infinite power series and the results indicated that the series has high accuracy by comparing it with those generated by the complex More >

Marco Dondero¹, Adrián P. Cisilino^1,2, J. Pablo Tomba¹

CMES-Computer Modeling in Engineering & Sciences, Vol.78, No.3&4, pp. 225-246, 2011, DOI:10.3970/cmes.2011.078.225

Abstract This paper introduces a numerical methodology for the design of random micro-heterogeneous materials with functionally graded effective thermal conductivities (ETC). The optimization is carried out using representative volume elements (RVEs), a parallel Genetic Algorithm (GA) as optimization method, and a Fast Multipole Boundary Element Method (FMBEM) for the evaluation of the cost function. The methodology is applied for the design of foam-like microstructures consisting of random distributions of circular insulated holes. The temperature field along a material sample is used as objective function, while the spatial distribution of the holes is the design variable. There More >

Tai-Ming Chang¹, Chien-Chou Weng¹, Mei-Jiau Huang^1,2, Chun-KaiLiu², Chih-Kuang Yu²

CMES-Computer Modeling in Engineering & Sciences, Vol.50, No.1, pp. 47-66, 2009, DOI:10.3970/cmes.2009.050.047

Abstract We employ the non-equilibrium molecular dynamics (NEMD) simulation to calculate the in-plane thermal conductivity of silicon thin films of thickness 2.2nm and 11nm. To eliminate the finite-size effect, samples of various lengths are simulated and an extrapolation technique is applied. To perform the quantum correction which is necessary as the MD simulation temperature is lower than Debye temperature, the confined phonon spectra are obtained in advance via the EMD simulations. The investigation shows the thermal conductivities corrected based on the bulk and thin-film phonon densities of states are very close and they agree excellently with More >

José Pedro Rino¹,Giovano de Oliveira Cardozo¹, Adalberto Picinin¹

CMC-Computers, Materials & Continua, Vol.12, No.2, pp. 145-156, 2009, DOI:10.3970/cmc.2009.012.145

Abstract A new parametrization for the previous empirical interatomic potential for indium antimonite is presented. This alternative parametrization is designed to correct the energetic sequence of structures. The effective empirical interatomic potential proposed consists of two and three body interactions which has the same functional form of the interatomic potential proposed by Vashishta et. al. to study other semiconductors (Branicio et al., 2003; Ebbsjo et al., 2000; Shimojo et al., 2000; Vashishta et al., 2008). Molecular dynamics simulations (MD) are performed to study high pressure phases of InSb up to 70 GPa and its thermal conductivity as a function of More >

Weixue Tian¹, Ronggui Yang²

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 123-142, 2008, DOI:10.3970/cmes.2008.024.123

Abstract In this paper, we investigated the effective thermal conductivity of three dimensional nanocomposites composed of randomly distributed binary nanoparticles with large differences (contrast ratio) in their intrinsic (bulk) thermal conductivity. When random composites are made from particles with very different thermal conductivity (large contrast ratio), a continuous phase of high thermal conductivity constituent is formed when its volumetric concentration reaches beyond the percolation threshold. Such a continuous phase of material can provide a potentially low resistance pathway for thermal transport in random composites. The percolation theory predicts the thermal conductivity of the random composites to… More >