Papers by Keyword: Thermal Characterization

Abstract: The quest to research the new engineering materials for energy applications is increasing day by day due to decrease in fossil fuel materials. Moreover, the management of municipal solid waste (MSW) by converting it to the energy is need of our society to address the energy shortage as well as environmental issues. Refused derived fuel (RDF) material is one of the energy products of MSW, whose reliability and quality with respect to the energy is analyzed in this work. Three different RDF materials (RDF-A, RDF-B and RDF-C) have been characterized by thermal analysis techniques to suggest best RDF based on energy efficiency. The results showed that the RDF-A contains higher amounts of carbon (52.44%) and hydrogen (4.184%) contents and good calorific value (5278 kcal/kg), which leads to a better fuel quality. TGA analysis revealed that with the increase in volatile matter fraction of RDF materials, the retention time under combustion atmosphere has also been increased accordingly. In the light of all results RDF-A was suggested to be a good candidate for energy applications and can be used as fuel for various combustion reactions.

Abstract: This paper reports on the thermal characterization, via the thermal conductivity, of natural materials, such as mulch and lava rock and their usefulness as building insulation. Experiments were carried out using a scale one monitored wall (i.e. heat flux and temperature sensors) exposed to a heating source on one side and to an air conditioned space on the other. The wall system was composed of an 8.85 cm thick cavity, where the mulch and lava rock were placed. The cavity was enclosed between two layers of pine wood (40 mm thick each). After the experiments and statistical data manipulation, the estimated thermal conductivity of the materials were 0.48 ± 0.001 W.m^-1.K^-1 and 0.129 ± 0.003 W.m^-1.K^-1 for mulch and lava-rock, respectively. That is, mulch has a thermal conductivity comparable to that of bulk hemp while lava rock has a thermal conductivity comparable to that of hemp brick. These values indicate the usefulness of mulch, compared to the impracticality of using lava-rocks materials for building insulation.

Abstract: As the raw materials used in the ceramic materials manufacturing are natural, it is important to use them as a alternative materials, thus decreasing the elements demand taken from nature. This paper aims the characterization of foundry solid powder exhaust from a brazilian company located in Joinville - SC as an alternative raw material for ceramic coating by X-ray diffraction (XRD), thermal analysis (DSC) and thermogravimetric (TG). The dust depletion is caused in the manufacturing mold sand process, when the bentonita (clay), silica sand and coal during the metal parts production are mixed in green sand production. The raw materials were characterized through X-ray diffraction (XRD), thermal (DSC) and thermogravimetric analisys (TG). The atomized powder thermogravimetric analysis curve shows three intervals associated with the mass loss and it is typical of clay commercial application.

Abstract: A new mixed laser crystal, Yb0.006Y0.923Lu0.071VO4, has been successfully grown using the Czochralski method. X-ray powder diffraction analysis shows that the crystal has ZrSiO4 structure. Density, thermal expansion coefficients, specific heat and thermal diffusion coefficients were measured, and the thermal conductivity coefficients were determined.

Abstract: Concentrating Solar Power Technology (CSP) is nowadays growing mainly due to the technical and economic success of the first projects and to the stable green pricing or support mechanisms that bridges the initial gap in electricity costs (i.e. feed-in tariffs). Future growth will depend on a successful cost reduction and on a strong effort in R&D to optimize the potential for technical improvement [1]. Testing of new materials, components and systems is still of key importance to drive research and innovation improvements to a commercial stage. Receiver manufacturers are investing in R&D in order to improve performances and reduce costs, while project developers are demanding standards to help them evaluate satisfactorily the risks and the benefits of introducing new developments in commercial power plants. The Solar Thermal Energy Department, of the National Renewable Energy Centre (CENER) and the Applied Optics Department of the Universidad de Zaragoza (UZ) have joined efforts to develop a characterization equipment able to measure as far as possible most of the receiver optical and thermal properties. In this paper the testing facility developed by CENER-UZ is described technically. The methodology for optical and thermal characterization of solar receivers for parabolic trough collectors is explained and the preliminary results are presented and discussed in detail.

Abstract: Soils play a decisive role in the manufacture of building materials, especially, tiles and bricks. Production techniques cause negative impacts on the environment and add additional time to the production process. Three samples obtained from Paraíba State were characterized by thermal characterization, granulometric and physical-mechanical techniques. Thermal analysis was undertaken in two different atmospheres, at a flow rate of 110 ml/min and a heating rate of 10oC/min. Evaluation of the soils through their thermal characteristics for use in soil-cement bricks production is elucidated.

Abstract: The open photoacoustic cell technique (OPC) was carried out in order to measure the thermal diffusivity of hardmetal. Hardmetal is usually processed by the conventional powder technology techniques: mix of WC + Co powders, compacting, and liquid phase sintering A new method to process hardmetal parts is hereby described. Parts of WC-15%wt Co were processed by using high pressure – high temperature sintering. It was used the pressure of 5GPa, temperature of 1350 oC, and time of 2 minutes of sintering. In addition to the thermal diffusivity, heat capacity was considered and the thermal conductivity achieved. Results matched with the values of the literatures where others photoacoustic techniques have been employed. It was achieved a thermal capacity of 3.34J/cm3K, thermal diffusivity of 0.35cm2/s, and thermal conductivity of 116.9W/mK. It reveals that the HPHT processed WC- 15%wtCo hardmetal is able to work as a cutting tool, in the thermal point of view.