Electronic edition ISSN 1574-0579

Solid-liquid phase transition process of water-based ferrofluid }

A. A. Agao-Agao¹ , K. Maki¹ , Y. Iwamoto¹ , Y. Ido¹ , I. Tolstorebrov² , T. M. Eikevik² , Y. Hirota³ , T. Miyazaki³

¹ Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, 466-8555, Japan
² Department of Energy and Process Engineering, Norwegian University of Science and Technology, Høgskoleringen 1, 7034 Trondheim, Norway
³ Ferrotec Material Technologies Corporation, Nihonbashi 2-3-4, Chuo-ku, Tokyo, 103-0027, Japan

Abstract
Cold thermal energy storage (CTES) technology uses advanced materials like magnetic nanofluids, also known as ferrofluids. This offers a promising solution for making cooling systems more efficient and supporting the cold chain in food preservation and medical storage. Ferrofluids are ferromagnetic particles coated with surfactants to prevent aggregation, forming stable colloidal suspensions in carrier fluids like water or oil. Recent attention has been focused on modifying the thermophysical properties of ferrofluids using magnetic field applications to enhance heat transfer and thermal management. However, the underlying mechanisms during the phase-transition process of ferrofluids are not well understood. In this study, we synthesized a water-based magnetic fluid via the co-precipitation method and performed a differential scanning calorimetry (DSC) analysis to investigate the effect of an applied magnetic field on the solidification and melting of a water-based ferrofluid. The results demonstrate that applying a magnetic field reduces the heat flow during phase transitions, suggesting potential applications in energy-efficient thermal management systems. Key words: DSC, ferrofluid, magnetic field, melting, solidification Figs 4, Refs 17.