S. Lorefice, E. Pessana, R. Romeo
CHARACTERIZATION OF NEW TEMPERATURE SENSOR BASED ON QUARTZ TUNING FORK OSCILLATOR

A new temperature system based on low cost quartz tuning forks, originally designed to be used in wristwatches, has been arranged for temperature measurements in a wide cryogenic temperature range from 77 K to 273 K.
The present paper concerns small quartz crystal tuning forks, with a fundamental frequency of 32768 Hz, as a temperature sensor by measuring the resonance frequency shift caused by an external temperature. Special attention has been given to the methodology, equipment and design to improve the stability in time of the output signal of the quartz tuning fork temperature sensor. After temperature calibration, a statistical study has been performed to estimate the parameters/coefficients of the fitted curves by using a Weight Total Least Squares “WTLS” method. The chi-square test has also been considered as an indicator of the agreement between the observed data and the predicted values.
Higher-order polynomial curves seem to be the ”best fits” for the experimental data provided by the temperature system. The study also shows a significant statistical improvement by introducing the fractional degree of 0.5 in the regression curves, in particular for the third degree polynomial regression. Moreover, the fractional polynomial curve results in a better smoothing of the experimental irregularities encountered at low temperatures.

Suyong Kwon, Joohyun Lee, Yong-Gyoo Kim
DEVELOPMENT OF THE THERMOELECTRIC FIGURE-OF-MERIT EVALUATION SYSTEM WORKING AT HIGH TEMPERATURE

New apparatus for evaluation of the figure of merit (ZT) of thermoelectric devices has been developed. ZT value is comprised of three physical quantities, Seebeck coefficient, electrical conductivity, and thermal conductivity. We have already reported ZT evaluation system working from -10 °C to 150 °C. In this study, we present new apparatus for evaluating the ZT value of devices between 150 °C and 700 °C by direct measurement of thermal conductivity using guarded hot plate method.

Le Chen, Zeyao Wang, Yaqiong Fu, Yunxia Wu, Jianbin Xu
ON-LINE MEASUREMENT OF SURFACE TEMPERATURE BASED ON AN INFRARED TARGET

Infrared thermal imager is increasingly used in different fields in production and life, as it possesses the advantages of quick response and non-contact. However, the accuracy of temperature measured by infrared thermal imager is affected seriously by surface emissivity, which limits the use of infrared thermal imager. This paper proposes an on-line measurement of surface temperature by infrared thermal imager based on an infrared target. The experimental results show that the proposed method reduces the error of temperature measurement to about 2%.

Ricardo A. N. Ferreira, Denise M. Camarano, Wilmar B. Ferraz, Pablo A. Grossi, Fábio A. Mansur
THERMAL DIFFUSIVITY OF URANIUM DIOXIDE FUEL PELLETS WITH ADDITION OF BERYLLIUM OXIDE BY THE LASER FLASH METHOD

A research program is in progress at CDTN – Centro de Desenvolvimento da Tecnologia Nuclear, aiming the development of fuel pellets made from a mixture of uranium dioxide microspheres or powder and beryllium oxide powder for increasing the thermal conductivity of the nuclear fuel. This type of fuel promises to be safer than current fuels, improving the performance of the reactor. In previous studies conducted at CDTN, fuel pellets were manufactured and tested considering the following weight percentages: 1, 2, 3, 5, 7 and 14wt.% of beryllium oxide (BeO) in mixture with microspheres of UO₂. Continuing this project, new uranium dioxide fuel pellets with addition of 2wt.% of BeO were manufactured and tested. The Laser Flash Method was employed to investigate the variation of thermal diffusivity at room temperature on those new pellets. The results obtained showed an increase of 12% in the thermal diffusivity with addition of 2wt.% of BeO in the uranium dioxide fuel pellets.

Pavel Neyezhmakov, Stanislav Pivnenko, Sergei Zub
ELECTRONIC CALIBRATION CERTIFICATE

The use of electronic calibration certificates provides a number of advantages. In NSC “Institute of Metrology” (Ukraine) development of electronic system for creation and storage of electronic calibration certificates was started. Also java applet program was developed for the purpose of creation of electronic calibration certificate in PDF with following electronic digital signature. The structure and contents of the certificate are fully compliant with COOMET Recommendation R/GM/15:2007.