Inge Magdalena Sutjahja, Annisa Rahman, Risky Afandi Putri, Ahmad Swandi, Radhiah Anggraini, Surjani Wonorahardjo, Daniel Kurnia, Surjamanto Wonorahardjo
This paper reports electrofreezing experiments on the inorganic phase-change material (PCM) CaCl2·6H2O by using an insulated copper electrode that is commonly sold in the market. The effect of the applied voltage or electric field to the nucleation process is measured by the nucleation temperature, freezing temperature, supercooling degree, induction time, time for supercooling, and time for crystallisation. It is found that, compared to the zero field, the freezing temperature remains nearly constant while the nucleation temperature increases with increasing applied field, leading to a reduction in the supercooling degree. The decrease in the supercooling degree is approximately 6 K for an applied voltage of V = 5.0 kV or E = 107 V m-1. With the increase in the applied field the induction time decreased considerably along with reduction of the measured data spread as compared to the no-voltage case, while the crystallisation time for the phase transformation prolonged. The overall phenomena are analysed in terms of modification of the Gibbs free energy for crystallisation owing to the applied field, with the mechanism involving bubble generation and formation of a copper-chloride complex. © 2019, Association of Chemists and Chemical Engineers of Serbia. All rights reserved.
Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha No. 10, Bandung, 40132, Indonesia; Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Negeri Malang, Jl. Semarang No.5, Malang, 65145, Jawa Timur, Indonesia; Department of Architecture, School of Architecture, Planning and Policy Development, Institut Teknologi Bandung, Jl. Ganesha No. 10, Bandung, 40132, Indonesia
