N. Laaroussi^1*, Y. Chihab¹, M. Garoum¹, L-V. Bénet², F. Lacroux³

FDMP-Fluid Dynamics & Materials Processing, Vol.11, No.4, pp. 354-365, 2015, DOI:10.3970/fdmp.2015.011.354

Abstract This study is based on the modeling of the air flow in the hall building including heating and air-conditioning systems. The building contains two converter stations “valves” considered as heat sources. Heat transfer in the hall is numerically simulated using the standard k-ε model of turbulence. For a very hot weather, this study aims to evaluate the local temperatures in the ambient air of the hall, with assuming running valves and air conditioning device in open loop with a 35°C inlet temperature. The study has shown that the air conditioning is efficient enough to maintain More >

Zan Wu^a, Zhaozan Feng^b, Bengt Sundén^a,*, Lars Wadsö^c

Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-10, 2014, DOI:10.5098/hmt.5.18

Abstract Thermal conductivity and rheology behavior of two aqueous nanofluids, i.e., alumina and multi-walled carbon nanotube (MWCNT) nanofluids, were experimentally investigated and compared with previous analytical models. Information about the possible agglomeration size and interfacial thermal resistance in the nanofluids were obtained and partially validated. By incorporating the effects of interfacial thermal resistance, a revised model was found to accurately reproduce the experimental data based on the agglomeration size extracted from the rheology analysis. In addition, the thermal conductivity change of the alumina/water nanofluid with elapsed time was investigated. Thermal conductivity measurements were also conducted for More >

Junjie Chen^*, Longfei Yan, Wenya Song

Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-6, 2014, DOI:10.5098/hmt.5.16

Abstract To understand the effect of different thermal conductivities on catalytic combustion characteristics, effect of thermal conductivity on micro-combustion characteristics of hydrogen-air mixtures in Pt/γ-Al₂O₃ catalytic micro-combustors were investigated numerically with detailed chemical kinetics mechanisms. Three kinds of wall materials (100, 7.5, and 0.5 W/m·K) were selected to investigate the effect of heat conduction on the catalytic combustion. The simulation results indicate that the catalytic reaction restrains the gas phase reaction in Pt/γ-Al₂O₃ catalytic micro-combustors. The gas phase reaction restrained by Pt/γ-Al₂O₃ catalysts is sensitive to thermal boundary condition at the wall. For most conditions, the gas phase More >

Etim S. Udoetok^*

Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-5, 2013, DOI:10.5098/hmt.v4.2.3008

Abstract A model for the coefficient of thermal conductivity of binary mixtures of gases has been derived. The theory presented is based on the assumption of random fluctuations between two possible extreme arrangements of a binary gas mixture. The results obtained from the new model compared favorably with published experimental results. The proposed new model provides a simple approach without sacrificing much accuracy compared to previous models. It is applicable to any binary mixture of gases which includes monoatomic gas mixture, polyatomic gas mixtures and mixtures involving rare gases. The new model can be very useful More >

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 >