Fadhel Aloulou^1,*, Sabrine Alila², Habib Sammouda¹

Journal of Renewable Materials, Vol.7, No.8, pp. 763-774, 2019, DOI:10.32604/jrm.2019.04071

Abstract The influence of nanofiberwood on the properties of the fresh condition of cement based mortars is not known in detail, despite recent advances in nanocellulose technology and it is related composite materials. Nanofiber wood from industrial waste, produced by high-pressure homogenization, was used as cement partial replacement for cement paste at a content ranging from 0% to 2% by weight of cement. The effect of the nanofiber wood content on the porosity, the compressive strength and the degree of hydration of the cement was investigated. Results have shown an improvement in the compressive strength by more than 50% with 1%… More >

Aklouche Leila¹, Monteau Jean-Yves², Rezzoug Sid-Ahmed¹, Maugard Thierry³, Guihard Luc², Cohendoz Stephane¹, Maache-Rezzoug Zoulikha^1,*

Journal of Renewable Materials, Vol.7, No.6, pp. 535-546, 2019, DOI:10.32604/jrm.2019.04361

Abstract Specific heat (Cp) and effective thermal conductivity (λ) of native maize starch (NS) were measured by DSC and transient heat transfer method, respectively, at different moisture contents and temperatures. The dependency of temperature (T) and moisture content (W) on the two parameters were investigated. The thermophysical properties of treated starch (TS) by four hydrothermal processes (RP-HMT, IV-HMT, DV-HMT and FV-HMT) were measured and compared to native strach. Hydrothermal treatments were performed at 3 bars (133°C) for 10 min. For Cp and λ measurements, moisture content varied for NS from 5 to 21.5% d.b. and from 8.8 to 25% d.b., respectively,… More >

Dounia Bendahou^1,2, Abdelkader Bendahou¹, Bastien Seantier¹, Bénédicte Lebeau³, Yves Grohens^1,*, Hamid Kaddami^2,*

Journal of Renewable Materials, Vol.6, No.3, pp. 299-313, 2018, DOI:10.7569/JRM.2017.634185

Abstract Hybrid aerogels have been prepared by freeze-drying technique after mixing water dispersions of cellulose microfibers or cellulose nanofibers and silica (SiO2) of type SBA-15 (2D-hexagonal). The prepared composites were characterized by different analysis techniques such as SEM, hot-filament, DMA, etc. These composites are compared to those previously prepared using nanozeolites (NZs) as mineral charge. The morphology studied by SEM indicated that both systems have different structures, i.e., individual fibers for cellulose microfibers WP-based aerogels and films for nanofibrillated cellulose NFC-based ones.... These differences seem to be driven by the charge of the particles, their aspect ratio and concentrations. These hybrid… More >

Rajendran Muthuraj, Abhishek Sachan, Mickael Castro*, Jean-François Feller, Bastien Seantier*, Yves Grohens

Journal of Renewable Materials, Vol.6, No.3, pp. 277-287, 2018, DOI:10.7569/JRM.2017.634182

Abstract In this work, thermally insulating and electrically conductive aerogels were prepared from cellulose nanofibers (CNF) and carbon nanotubes (CNTs) by environmentally friendly freeze-drying process. The thermal conductivity of neat CNF aerogel is 24 mW/(m·K) with a density of 0.025 g/cm3. With the addition of CNTs into CNF aerogel, the electrical conductivity was significantly increased while the thermal conductivity was increased to 38 mW/(m·K). Due to these interesting properties, the Seebeck coefficient and the figure of merit (ZT) of the CNF/CNTs aerogels were measured and showed that CNF/CNTs aerogel thermoelectric properties can be improved. The compressibility and electrical resistance of the… More >

M. Himabindu¹, K. Kamalakar², MSL Karuna², Aruna Palanisamy^1*

Journal of Renewable Materials, Vol.5, No.2, pp. 124-131, 2017, DOI:10.7569/JRM.2016.634137

Abstract Rigid polyurethane biofoams were prepared from karanja polyol which was derived by ring-opening reaction of epoxidized karanja oil. The polyol, which had a hydroxyl value of 186 mg KOH/g, was thoroughly characterized and the structure confirmed by spectral techniques. The foam formulations were developed to achieve shrinkage-free foams with water used as the blowing agent. The resulting foams were characterized for their mechanical properties like density, compression strength and flexural strength. The densities and mechanical properties, such as compression and flexural strength, varied with the amount of methylene diphenyl diisocyanate (MDI) for a fixed amount of polyol and other additives… More >

Chung-Fu Chen¹, Yi-Chia Cheng¹, Che-Wun Hong^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.109-110, No.3, pp. 263-283, 2015, DOI:10.3970/cmes.2015.109.263

Abstract Based on the Hellmann-Feynman theorem, which integrates the molecular dynamics simulation with computational quantum mechanics, this research simulates the ionic transport in the LiCl-KCl molten salt materials using so called “first principles molecular dynamics (FPMD)” technique without employing an empirical potential model. The main purpose of this computational FPMD focuses on the evaluation of important transport properties, such as diffusion coefficient, ionic conductivity, shear viscosity, and thermal conductivity, using the Green-Kubo relationship. All simulation results agree well with experimental data published in existing literatures within an acceptable range. FPMD calculations are proved to be a powerful tool for prediction of… More >

H. Imtiaz¹, F. M. Mahfouz²

CMES-Computer Modeling in Engineering & Sciences, Vol.108, No.3, pp. 171-192, 2015, DOI:10.3970/cmes.2015.108.171

Abstract This paper investigates numerically the conjugate heat transfer in a concentric enclosure that is formed between two concentric cylinders and filled with micropolar fluid. The wall of inner cylinder is considerably thick, while the wall of outer cylinder is very thin. The inner cylinder is heated from inner side through constant heat flux, whereas the outer cylinder is cooled and maintained at constant temperature. The induced buoyancy driven flow and associated conjugate heat transfer are predicted numerically by solving flow and energy governing equations considering a combination of finite difference and Fourier spectral methods. The study investigates the effect of… 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 combination method. 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 are presented details of the… 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 the theoretical predictions of a… More >