Authors : Nir Haimovich, Dario R Dekel, Simon Brandon
We present the application of our thermal battery system-level simulator in novel multiple-cell thermal analyses. Several model batteries are chosen to demonstrate the simulator's versatility and robustness in developing advanced thermal battery designs. The heat transfer phase-change model and supporting mass balance are modified to improve model consistency. Simulation results are presented from several case-studies covering different battery structures and operating conditions, including low and high current densities, different number of electro-active cells, various internal and external battery geometrical details, the use of salt buffers, external flanges, and inhomogeneous initial conditions
Authors : Alina Amel, Sarah B Smedley, Dario R Dekel, Michael A Hickner, Yair Ein-Eli
The effect of the cross-linker chemical structure on the properties and chemical stability of anion exchange membrane is the focus of this study. Two different cross-linkers were investigated, one with linear hexyl chain between crosslinking sites, and the other, ether in the center of the alkyl linker. These two cross-linkers have a fundamental difference in their polarity and hydrophilicity. The ether-containing cross-linker is more polar and therefore will improve membrane's water uptake and conductivity. Swelling and conductivity measurements were performed at various temperatures for both types
Authors : Dario R Dekel
Activated carbon is a porous carbon material with developed nano-sized pores and a high specific surface area (> 1,000 m2g À1). Nowadays, the technical term “nanoporous carbon” is very often used to mean “activated carbon,” but the activated carbon should be strictly defined as a porous carbon prepared by an activation process consisting of a gasification reaction to form the developed nano-sized pore structure in the carbon matrix. The activated carbons have been widely utilized as industrial materials, for example, an adsorbent, decolorizing agent, deodorant, and catalyst. The details of the preparation method, pore structure, and
Authors : John R Varcoe, Plamen Atanassov, Dario R Dekel, Andrew M Herring, Michael A Hickner, Paul A Kohl, Anthony R Kucernak, William E Mustain, Kitty Nijmeijer, Keith Scott, Tongwen Xu, Lin Zhuang
This article provides an up-to-date perspective on the use of anion-exchange membranes in fuel cells, electrolysers, redox flow batteries, reverse electrodialysis cells, and bioelectrochemical systems (e.g. microbial fuel cells). The aim is to highlight key concepts, misconceptions, the current state-of-the-art, technological and scientific limitations, and the future challenges (research priorities) related to the use of anion-exchange membranes in these energy technologies. All the references that the authors deemed
Authors : Dario R Dekel
In the last few years, developmental work on anion conductive membranes for AMFC has significantly increased and several polymer chemistries have already been tested at very small AMFC scales. On the other hand, scarce work is being done on anion conductive ionomers, and just a very few groups are working on electrocatalysts for the electrodes of this technology. From the limited materials developed for this technology, peak power density records of almost 200mW/cm2 were already achieved. Non-published data suggests that the actual power densities that can be achieved with today's state-of-the-art anion conductive polymers are even
Authors : Nir Haimovich, Dario R Dekel, Simon Brandon
We present a complete and detailed thermal simulator designed for the computational analysis of thermal batteries from the level of a single cell up to that of the entire system. Our simulator is based on a comprehensive transient and two-dimensional (axisymmetric) mathematical heat-transfer model, with significant flexibility in the geometrical modeling and the materials used. The model accounts for different aspects of heat transfer, including conduction, joule heating, heat of reactions, and latent heat of fusion associated with electrolyte phase change (salt solidification). It is supported by a simplified mass balance involving
Authors : Dario R Dekel
As a rule, thermal batteries consist of a series or series-parallel arrays of cells. Each cell comprises an anode, electrolyte-separator, cathode, and a pyrotechnic heat source. Activation of the cell occurs when sufficient heat is applied to melt the electrolyte. Lithium alloys and immobilized molten lithium are typically used as anodes. Molten lithium anodes possess the advantage of higher capacity and faster kinetics. One disadvantage is the formation of lithium nitride due to nitrogen attack, which results in serious degradation of the lifetime of thermal batteries. The author proposes a new lithium anode composite for thermal
Authors : Dario R Dekel, David Hasson, Raphael Semiat
In Part I of this work, permeation flows of a large number of solvents were measured and found to exhibit a wide spread in permeate flux levels. The flux of both pure and mixed solvents was mainly affected by surface tension and viscosity.
This paper presents a transport model describing solvent–membrane interactions, governed by viscous and surface forces. The model relates the flux of a solvent mixture with easily measurable solvent and membrane properties (surface tension, viscosity and membrane hydrophobicity).
Extensive flux measurements of mixed solvents belonging to several chemical families were well correlated
Effect of solvent properties on permeate flow through nanofiltration membranes: Part I. Investigation of parameters affecting solvent flux
Authors : Dario R. Machado (Dekel), David Hasson, Raphael Semiat
The objective of the present study was to characterize transport properties of solvents permeating through solvent resistant nanofiltration membranes that have only recently become available. Permeation flows of a number of solvents of different chemical families were measured in a batch cell. The solvents studied were alcohols, paraffins, ketones, acetates, and water, as well as their binary mixtures. The experimental data revealed a marked variation in the level of permeate flux among the various
Authors : Gideon S Grader, Dario R Dekel, Raphael Semiat
Acetate, nitrate, and oxalate precursors for YBCO have been spray pyrolyzed under different conditions. Shelled and nonhollow microparticles were obtained from acetate and nitrate precursors, while nonhollow agglomerates were obtained from the oxalate suspension. At low furnace temperatures, the temperature and residence time of the particles were insufficient for complete decomposition of the precursors leading to Cu2O and Cu metal in the product. At 900 °C and above, reduced forms of CuO were not detected by x-ray measurements, and up to ∼60 wt.% YBCO was obtained. An approximate model predicting the
