Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 2023

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

New empirical correlations for the viscosity of selected organic phase change materials

Cieśliński Janusz Tadeusz, Fabrykiewicz Maciej, Wiśniewski Tomasz Stefan, Kubiś Michał, Smoleń Sławomir, Eicke Albrecht, Dutkowski Krzysztof, Głuszek-Czarnecka Małgorzata

Archives of Thermodynamics

2023

Vol. 44, no. 4

123--139

Although there are many methods and instruments for measuring viscosity, it is still difficult to determine a reliable value of the dynamic viscosity of complex chemicals such as paraffins and fatty acids. This is due to the complex and heterogeneous structure of these compounds in the case of commercial products. On the other hand, the measuring instrument should be selected very carefully, including its measuring principle and measuring range. This paper presents results of viscosity measurements of three organic PCMs (phase change materials) obtained in four different research institutions. Commercial products: paraffin, myristic acid (97%) and mixture of palmitic acid (55%) and stearic acid (45%) were selected as PCMs. Four different viscometers, namely Fungilab V-Pad, Rheotest LK 2.2, Rheometer Anton Paar MCR 102, and Brookfield DV-II + Pro have been used to determine temperature dependent dynamic viscosity of the tested PCMs. Using a large database of present measurement results, correlations were developed to calculate the dynamic viscosity of fatty acids and paraffins, which predict the experimental data within a band of ±20%.

Stability investigation of the pcm nanocomposites

Cieśliński Janusz T., Boroń Paulina, Fabrykiewicz Maciej

Acta Mechanica et Automatica

2023

Vol. 17, no. 3

381--389

Ensuring the stability is a key issue to be solved for the technical application of nanocomposites. In this work, fatty acid P1801 served as base phase change material (PCM)P1801, and its main ingredients are palmitic acid (58%) and stearic acid (38%). Titania (TiO2) and alumina (Al2O3) with mass concentrations of 1% and 5% were selected as nanoparticles, while polyvinylpyrrolidone (PVP) or oleic acid (OA) with mass concentrations of 5% were tested as surfactants. On the basis of the measured temperature distributions in the sample, which is subject to melting and solidification processes, it was determined which of the tested nanocomposites are stable and which are not. In addition, a thermal test was proposed to assess the stability of the produced nanoPCM, which consists in measuring the temperature distribution versus time according to a precisely given procedure.