Stack Number Research Articles

An electron microscopic study on the turbostratic carbon formed in phenolic resin carbon by catalytic action of finely dispersed nickel

Very fine particles of certain substances are known to promote the catalytic graphitization of carbonaceous material, resulting in a unique carbon whose X-ray parameters, lying in the range of turbostratic carbon, remain almost unchanged even after more severe heat-treatments. To elucidate the actual structure of this type of carbon, its formation mechanism, and the reason for its high thermal-stability, a high resolution electron microscopic investigation was carried out on carbons derived from phenolic resin lightly and heavily doped with an organo-nickel compound. The electron microscopic texture of this carbon was found to consist of entangled lattice fringes of a stack number comparable with its X-ray L c -value (110 Å). This texture was analogous to that of some types of the hard carbon heated to very high temperatures, but the former was less sinuous in its lattice fringe and more open in its structure. The formation mechanism appeared to differ from that accepted for conventional nickel-catalyzed graphitization, and to be particularly related with nickel particles in a certain size range. The evidence obtained so far was not enough to suggest a new mechanism, but only to illustrate part of some of the possible, hitherto little known mechanisms which might proceed along with it. Thermal stability of the carbon was understood to be due to its structure being similar to the hard carbon, but the ultimate reason why this type of structure was thermally stable could be made clear only to a limited extent.

Ultrasonic studies in sulphosalicyclic acid chelates of Cd (II) and Th(IV) : Prakash, S. and Laxmi, S. Acustica, 19, No 2, pp 98–102 (1967)

Trade-off between shunt current loss and pumping loss is a major challenge in the design of the electrolyte piping network in a flow battery system. It is generally recognized that longer and thinner ducts are beneficial to reduce shunt current but detrimental to minimize pumping power. Base on the developed analog circuit model and the flow network model, we make case studies of multi-stack vanadium flow battery piping systems and demonstrate that both shunt current and electrolyte flow resistance can be simultaneously minimized by using longer and thicker ducts in the piping network. However, extremely long and/or thick ducts lead to a bulky system and may be prohibited by the stack structure. Accordingly, the intrinsic design trade-off is between system efficiency and compactness. Since multi-stack configurations bring both flexibility and complexity to the design process, we perform systematic comparisons among representative piping system designs to illustrate the complicated trade-offs among numerous parameters including stack number, intra-stack channel resistance and inter-stack pipe resistance. As the final design depends on various technical and economical requirements, this paper aims to provide guidelines rather than solutions for designers to locate the optimal trade-off points according to their specific cases.