Investigation into the Emissivity of a Thin Tungsten Wire with Oxidized Surface in the Unsteady Heat Conduction Regime

• Published in: Thermal engineering 2023-03, Vol.70 (3), p.210-214
• Main Authors: Zeodinov, M. G., Pronkin, A. A., Krynitskaya, D. A.
• Format: Article
• Language: English
• Subjects: Analog to digital converters; Conduction heating; Conductive heat transfer; Emissivity; Engineering; Engineering Thermodynamics; Heat and Mass Transfer; High vacuum; Lithium-ion batteries; Microcontrollers; Properties of Working Bodies and Materials; Rechargeable batteries; Time measurement; Tungsten; Unsteady heat conduction; Wire
• ISSN: 0040-6015; 1555-6301
• DOI: 10.1134/S0040601523030084

Modern diagnostic tools offer a new approach to solving thermophysical problems, considerably saving measurement time: those measurements that previously required hours can now be made in just a few minutes A procedure is proposed for determining the emissivity of a thin metal wire within several minutes in the regime of unsteady-state heat conduction. Many researchers, including G.M. Kondrat’ev, who proposed to determine the emissivity by the regular regime method, tried to implement this procedure in practice but faced technical problems inherent in experimental work, including the requirements for high vacuum and taking measurements using fast-response instruments. Technical difficulties forced researchers to limit the temperature range, increase the experiment time, or perform computer simulations of the heating-cooling process. This procedure can be implemented in practice due to the use of a fast-response measurement system based on an Arduino Uno microcontroller and an L-Card E14-140 analog-to-digital converter capable of recording signals at 40 ms intervals. Lithium-ion batteries were used to miniaturize the unit and reduce the interference level. The values of emissivity of a tungsten wire with an oxidized surface, determined by the selected and the calorimetric method in the temperature range of 400–870 K, are in good agreement. The temperature range is limited only by the voltage of the used battery.