Enhanced heat transfer in latent-heat thermal energy storage systems

This talk deals with recent developments in modeling and experimentation of solid-liquid phase change processes, with special attention to the geometries commonly encountered in or suggested for the latent-heat thermal energy storage (LHTES) systems, which use phase-change materials (PCM). The processes in these systems are multi-dimensional and complicated, and include phenomena such as convection in the liquid phase, sinking of solid in the liquid, volume change due to phase change, and super-cooling. Thus, their reliable modeling requires significant efforts, whereas experimentation in this field is quite difficult and could lead to results rather different from those characteristic of thermal-storage applications. The presentation is based, to a very large extent, on the author’s personal knowledge and experience in design and modeling of PCM systems. Our attention is dedicated to some indispensable details and subtleties, which can affect the processes significantly but are frequently overlooked. In particular, we present results of a multi-year study of latent-heat storage units, common and original, demonstrating theoretically and experimentally novel ways for heat transfer enhancement. It is shown that a so-called close-contact melting (CCM) may be reached in these systems, drastically reducing the melting time. Analytical modeling, which attempts to preserve main features of the process, reveals its governing dimensionless parameters, including the Fourier, Stefan, Archimedes and Prandtl numbers, along with additional groups representing the unit geometry. More general in-house numerical modeling is performed, as well, and its results are successfully generalized. Some other topics of interest in latent-heat thermal energy storage and thermal management systems are also discussed. In particular, various enhancement methods are presented and their merits are evaluated.
Bio :
Dr. Gennady Ziskind is Professor and former Head of Department of Mechanical Engineering (two full three-year terms 2017-2023) at Ben-Gurion University of the Negev (BGU) in Beer-Sheva, Israel. He earned his M.Sc. and D.Sc. degrees from the Faculty of Mechanical Engineering at the Technion–Israel Institute of Technology, in the field of aerosol mechanics. His present research deals with various aspects of heat and mass transfer and multiphase systems, including phase-change energy storage and thermal management. Dr. Ziskind has co-authored more than 90 journal articles and more than 100 conference papers. He is widely recognized as an expert in heat transfer, in general, and a leading researcher in the field of thermal energy storage and thermal management, in particular. Among other international activities, Dr. Ziskind served as Associate Editor of ASME Journal of Heat Transfer (two full terms in 2015-2021, awarded "Special Recognition for Exemplary Service"). In July 2019 he was appointed as Associate Editor of International Journal of Thermal Sciences (Elsevier). He is Delegate to the Assembly of International Heat Transfer Conferences, Member of the ASME Safety Standards Committee for Thermal Energy Storage (TES) Systems, and an active participant of several European research frameworks, including INPATH-TES and CSPplus. Dr. Ziskind co-chaired Eurotherm Seminars 99 (2014), 112 (2019) and 116 (2023), dedicated to Thermal Energy Storage, and organized INNOSTORAGE–Advances in Thermal Energy Storage International Conference in Israel in 2016. Dr. Ziskind serves as an evaluator of research proposals for the European Union and national research agencies abroad, and as Ph.D. theses examiner in Australia, Belgium, Canada, India, Ireland, Spain and Switzerland. His recent publications include a book, Phase-Change Materials for Thermal Management of Electronic Components, published by World Scientific Publishers in 2018, as a volume in the Encyclopedia of Thermal Packaging.