Papers by Keyword: Experimental

Abstract: The isobaric specific heat was measured experimentally for two kind of hybrid nanofluids like water and ethylene glycol based reduced graphene oxide-nanodiamond (rGO-ND) hybrid nanofluids at different particle volume loadings of 0.2%, 0.4%, 0.6%, 0.8% and 1.0%, and in the temperature range from 293 K to 333 K, respectively. The obtained experimental specific heat data was used for the artificial neural network (ANN) algorithms of Support Vector Regression (SVR), and Levenberg-Marquardt (LM) models for the predictions. Results indicated that, the specific heat of water, and ethylene glycol-based hybrid nanofluids at 1.0% vol. of hybrid nanofluid is lowered by 1.09% and 1.10% at a temperature of 333 K, compared to their own base fluids. The SVR and LM models for the specific heat of water-based hybrid nanofluids predict accurately with a correlation coefficient of 0.99849, and 0.99957, similarly, the SVR and LM models for the specific heat of ethylene glycol-based hybrid nanofluids predict accurately with a correlation coefficient of 0.99998, and 0.99906, respectively. The obtained data was compared with other kind of nanofluids data. The polynomial regression equation was proposed for the water and ethylene glycol-based hybrid nanofluids through the SVR model.

Abstract: 3D-printing technology is being used as a regular approach in prototyping and the production of machine components. However, despite their metallic counterparts, there are many issues including infill pattern, density, and stress concentration coefficient in 3D printing that are not well-defined. The infill density plays a significant role in the printing time and mechanical properties of the printed objects. On the other hand, like metallic materials, changing geometry, such as fillet radius and hole alters the strength of the printed elements. In this work, experimental works have been conducted to determine the effect of infill density on the tensile strength of 3D printed elements. Furthermore, various standard specimens for tensile testing have been prepared to investigate the effects of fillet radius and in-plane hole diameters on the tensile strength of PLA 3D-printed elements with different infill density. Using the experimental results, the tensile stress concentration coefficients as a function of fillet radius, hole diameters, and infill density have been determined. The results of the present work can be used as a guideline for analytical design and manufacturing 3D printing objects.

Abstract: The paper presents the experimental and numerical investigations of the tensile properties of bamboo-glass fibres hybrid reinforced unsaturated polyester composites. The stacking configuration was GGBBBGG and GBGBGBG, with G and B, respectively denoted BFRP and GFRP. The hybrid composites were manufactured using a resin infusion technique. It was found that the tensile strength of the GGBBBGG was higher than that of GBGBGBG, but the elastic modulus seemed not significantly different. Hence, the glass fibres positioned at the outer layer (as skin of a sandwich composite) gave the better tensile properties than that of the alternating configuration. Numerical work utilising an extended finite element method (XFEM) had been undertaken, and a reasonable agreement on the failure load was found between the numerical and experimental results. However, the numerical load-displacement curves were underpredicted, which might be due to the load train of the testing equipment and also, the model did not include delamination within the layers.

Abstract: This work presents a theoretical drying study of sisal fiber. Fibers with moisture content of around 11.2% were dried in an oven in the temperature 90°C. A transient and three-dimensional mathematical modeling to predict heat and mass transfer in a bed of fiber was proposed and numerically solved by using the finite-volume method. Results of the average moisture content and surface temperature were compared with experimental data to verify the consistence of the proposed model, and good agreement was verified.

Abstract: This work presents a drying study of banana fruit (cylindrical slices) using heat, mass and shrinkage lumped models, and experiments in different drying conditions. Whole bananas were peeled, sliced manually (cylindrical pieces) and dried in an oven at constant drying condition (40 and 70°C). Drying, heating and shrinkage lumped models were proposed and fitted to experimental data. Results revealed which air temperature affects significantly the moisture removal, heating and shrinkage of bananaslices. Furthermore, results revealed which air temperature affects significantly the moisture migration, heating and shrinkage rates of banana slices. The fitted results presented good agreement with experimental data.

Abstract: The mechanical characteristics of a fiber reinforced material depend on a number of parameters related to the structure and characteristics of the component materials, the volumetric distribution, orientation, geometry and adhesion of the fibers to the matrix. The modification of these characteristics over time is due to the varied mechanical demands (repeated or lasting), the thermal and humidity demands, the chemical agents and the influence of aging. The paper presents some observations resulting from experimental tests on polyester-glass composite materials developed in the Materiaux Composites laboratory.

Abstract: This paper presents the methodology of designing a transducer for the experimental measurement of forces. For this purpose, an elastic element of the shape of the letter "S" is designed and manufactured. The elastic element designed in SolidWorks is subjected to virtual testing, using the finite element method in ANSYS. After validating the results obtained considering the maximum values ​​of the stresses that appear for the nominal load, the experimental model of the transducer is realized. The central part of the elastic element behaves like a fixed double beam subjected to bend by the measuring force. On this beam are bonded strain gauge transducers, which measure the deformations produced by bending. The transducer is calibrated, in order to obtain the calibration constant, based on the obtained characteristic, that is, the dependence of the specific strain-deformation and force. The transducer thus constructed can be used in force measurement applications.

Abstract: In this chapter the adsorption fundamentals using biomass as adsorbents in the removal of metallic ions are presented. The research as shows the importance of many factors that affects the adsorption, such as the biomass superficial area, system temperature, pH, initial concentration of the metal, biomass amount and status (living or dead). The study was directed at the approach of two applications using Saccharomyces cerevisiae yeast in the adsorption of Cd²⁺ metal ions. In the first application it is discussed the influence of the pH of the medium and the biomass status (living or dead) in the adsorption of Cd²⁺, in batch. In the second application, it was studied the adsorption of Cd²⁺metallic ions through the Saccharomyces cerevisiae yeast immobilized in chitosan, in fixed bed, where the influence inlet mass flow rate and the initial effluent concentration on the adsorption capacity and percentage of Cd²⁺ ions removal are evaluated.The studies realized are supported by statistical analysis with 95% confidence intervals.

Abstract: The foam-mat dryingprocessof egg white, developed in the food industry, promotes a porous product, brittle and easy to grind. The powderedegg white has a good rehydration properties, safer consumption and storage conditions than fresh product, keeping the high level of proteins and vitamins contained in the egg. In this way, the objective of this work is to study, through numerical computational simulation, the physical aspects of the duck egg white foam-matdrying process. For this, the foam was characterized by its density, percentage of expansion, air over run, stability and moisture. Temperature (50, 60 and 70°C), stirring rate (levels 6, 7 and 8) and stirring time (4, 5 and 6 minutes) are taken as input conditions and the product final moisture and drying time are the output variables. Drying was performed based on the complete factorial 23 + 3 central point experimental design in this procedure. It has been observed that the time and stirring rate significantly influence the product final moisture and that the drying temperature is predominant for the total process time. From the foam moisturedata, adjustments of empirical mathematical models were made; evidencing that theModifiedPage and the Page models provided the best results, with a standard deviation lower than 0.01 and the coefficient of determination above 0.99. For this analysis, the case where the drying temperature, time and the stirring rate were, respectively, 70 °C, 6 minutes and 8 level, presented the best results.

Abstract: The present work had the objective of studying the osmotic dehydration process of cassava cubes (Manihot esculentaCrantz.) in ternary solutions containing water, sucrose, and sodium chloride. The osmotic dehydration process was studied by using a 2⁴ factorial planning with central points at different conditions of temperature (19-63°C), solute concentration (23-67% w/w), operating time (70-190 min.) and NaCl concentration (0-20% w/w). The process optimization was verified through the performance ratio of minimum solids gain, in conjunction with the maximum moisture loss and reduction of water activity of the material. From the analysis, the optimum condition for osmotic dehydration of cassava cubes was temperature52°C, concentration of the osmotic solution 56%solute,10% NaCl concentration,160 minutes of immersion time and 180 rpm . The study of osmotic dehydration kinetics in the optimized condition showed that the moisture loss reached equilibrium in 180 minutes and the solids gain in 30 minutes. The model of Azuara and contributors was fitted to experimental data of moisture lost and total solids gain, in the optimal condition and good agreement were obtained. From this comparison, the average effective diffusivity coefficients of moisture (1.99x10^-8m2/s) and total solids (2.77x10^-8m2/s) were estimated.