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This paper presents design, development, and testing of a custom-made calibration environment for the calibration of temperature sensors applied in a guarded hot plate apparatus for thermal conductivity measurements. Description of an in situ calibration principle and realization are introduced. Results of numerical simulation, as well as those of experimental validation are given in a separate section of the paper. According to the results, proposed in situ calibration by using the applied guarded hot plate apparatus elements improves both accuracy and traceability the of thermal conductivity measurement. © 2018 Serbian Society of Heat Transfer Engineers.

This paper presents design, development, and testing of a custom-made calibration environment for the calibration of temperature sensors applied in a guarded hot plate apparatus for thermal conductivity measurements. Description of an in situ calibration principle and realization are introduced. Results of numerical simulation, as well as those of experimental validation are given in a separate section of the paper. According to the results, proposed in situ calibration by using the applied guarded hot plate apparatus elements improves both accuracy and traceability the of thermal conductivity measurement. © 2018 Serbian Society of Heat Transfer Engineers.

This paper presents the Metrological Laboratory for Thermophysical Quantities (MLTV) and its actual measurement possibilities. The MLTV is located in the Department of Thermal Engineering and Energy of the Institute of Nuclear Sciences VINCA in Serbia. It was founded in 1963, accredited by the National Accreditation Body in 2007 and became the national designated laboratory for thermophysical quantities and received the status of a EURAMET Associate Member in 2015. Today, the laboratory develops, maintains and disseminates traceability of different national standards, such as those for thermal conductivity of insulations and poorly conductive solid materials from 250 K to 350 K, thermal diffusivity of a large variety of solid materials from 200 K to 1450 K and specific heat and specific electrical resistivity from 250 K to 2400 K of electroconductive solid materials. Total hemispherical and spectral normal emissivity from 1200 K to 2400 K of electroconductive solid materials are also measured in the MLTV. The methods and experimental setups for the realization and measurement of all of these standards and quantities are described with corresponding examples.

This work presents the development of an experimental set-up for measurements of thermal conductivity of solid materials, such as ceramics, polymers, rubbers, glasses, biological materials, etc. whose thermal conductivity lies in the approximate range between 0.1 and 2 W/mk The set-up was designed on the principle of the single-sided guarded hot plate method. In order to find the optimal design for generation of traceable 1-D heat flux through an investigated 300 mm x 300 mm specimen, a numerical heat transfer finite element method analysis was performed. The principal components of the measuring apparatus, such as hot plate with thermopile, cold plate, and auxiliary hot plate, were constructed according to the obtained results of simulations. Software for the control of experiment and data acquisition was developed using the LabVIEW programming environment.

Nanopowders based on gadolinium zirconium oxide (Gd2Zr2O7) doped by europium ions (Eu3+) were successfully prepared using a flame combustion method. This material is suitable for various optical devices. The structure of prepared materials has been confirmed and characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and photoluminescence (PL) techniques. The luminescence properties of synthesized nanopowders were characterized by emission spectra and luminescence lifetimes by using the streak camera system. PL spectra were obtained at three different excitation wavelengths (Optical Parametric Oscilator (OPO) at 360 nm, laser diode at 365 nm and Ar laser line at 514.5 nm). The strong emission lines at 611 nm and 630 nm corresponding to the D-5(0) - GT F-7(2) long lived transition could be used as a new red light source in optical devices. (C) 2014 Elsevier B.V. All rights reserved.