Developing vanadium redox flow technology on a 9-kW 26-kWh industrial scale test facility: Design review and early experiments

Redox Flow Batteries (RFBs) have a strong potential for future stationary storage, in view of the rapid expansion of renewable energy sources and smart grids. Their development and future success largely depend on the research on new materials, namely electrolytic solutions, membranes and electrodes, which is typically conduced on small single cells. A vast literature on these topics already exists. However, also the technological development plays a fundamental role in view of the successful application of RFBs in large plants. Despite that, very little research is reported in literature on the technology of large RFB systems. This paper presents the design, construction and early operation of a vanadium redox flow battery test facility of industrial size, dubbed IS-VRFB, where such technologies are developed and tested. In early experiments a peak power of 8.9 kW has been achieved with a stack specific power of 77Wkg−1. The maximum tested current density of 635 mA cm−2 has been reached with a cell voltage of 0.5 V, indicating that higher values can be obtained. The test facility is ready to be complemented with advanced diagnostic devices, including multichannel electrochemical impedance spectroscopy for studying aging and discrepancies in the cell behaviors

Electromagnetic Device Optimization with Stochastic Methods

none1Device optimization using metaheuristic methods has been successfully applied to electromagnetic devices since their development in the early 1980s. Some recent examples of the application of metaheuristics in electromagnetic device design include, among others, genetic algorithms [Zaoui2007], evolution strategies [Coelho2007], Tabu search [Cogotti2000], artificial immune systems [Campelo2006], particle swarm optimization (PSO) [Ciuprina2002]. In this chapter the author summarizes some of his experiences in the use of two stochastic optimization techniques which are very suitable to typical electromagnetic devices and systems. First the algorithms are briefly introduced and then their application to typical challenging problems, including Polymer Exchange Membrane Fuel Cells (PEMFC), high- field-uniformity solenoids and Superconducting Magnetic Energy Storage (SMES) systems, is presented.noneP. AlottoAlotto, Piergiorgi

Dual-PEEC Modeling of a Two-Port TEM Cell for VHF Applications

Two-port TEM cells with rectangular cross section are commonly used to produce plane electromagnetic waves with high electric field. The non-uniform structure makes the use of numerical methods extremely useful in the design phase in order to achieve a very good behavior of the TEM cell over a wide frequency range of operation. In this paper an extended version of PEEC is used to study a real device and results are compared with experimental ones

A Second-Order Cell Method for Poisson's Equation

The Cell Method, similar to the Finite Integration Technique, is a well-established numerical method for the solution of field problems, however an often raised criticism is that it is limited to constant fields within elements. In this paper we show that for the case of Poisson’s equation the Cell Method can be extended to the second order convergence. Numerical results showing the order of convergence of the method are presented

Distributed and Lumped Parameter Models for Fuel Cells

The chapter presents a review of modeling techniques for three types of fuel cells that are gaining industrial importance, namely, polymer electrolyte membrane (PEMFC), direct methanol (DMFC), and solid oxide (SOFC) fuel cells (FCs). The models presented are both multidimensional, suitable for investigating distributions, gradients, and inhomogeneities inside the cells, and zero-dimensional, which allows for fast analyses of overall performance and can be easily interfaced with or embedded in other numerical tools, for example, for studying the interaction with static converters needed to control the electric power flow. Thermal dependence is considered in all models. Some special numerical approaches are presented, which allow facing specific problems. An example is the Proper Generalized Decomposition (PDG) that allows overcoming the challenges arising from the extreme aspect ratio of the thin electrolyte separating anode and cathode. The use of numerical modeling as part of identification techniques, particularly by means of stochastic optimization approaches, for extracting the material parameters from multiple in situ measurements is also discussed and examples are given. Merits and demerits of the different models are discussed

A Methodology to Virtualize Technical Engineering Laboratories: MastrLAB-VR

Due to the importance given today to innovation, the education sector is evolving thanks digital technologies. Virtual Reality (VR) can be a potential teaching tool offering many advantages in the field of training and education, as it allows to acquire theoretical knowledge and practical skills using an immersive experience in less time than the traditional educational process. These assumptions allow to lay the foundations for a new educational environment, involving and stimulating for students. Starting from the objective of strengthening the innovative teaching offer and the learning processes, the case study of the research concerns the digitalization of MastrLAB, High Quality Laboratory (HQL) belonging to the Department of Structural, Building and Geotechnical Engineering (DISEG) of the Polytechnic of Turin, a center specialized in experimental mechanical tests on traditional and innovative building materials and on the structures made with them. The MastrLAB-VR has been developed, a revolutionary innovative training tool designed with the aim of educating the class in total safety on the techniques of use of machinery, thus reducing the dangers arising from the performance of potentially dangerous activities. The virtual laboratory, dedicated to the students of the Building and Civil Engineering Courses of the Polytechnic of Turin, has been projected to simulate in an absolutely realistic way the experimental approach to the structural tests foreseen in their courses of study: from the tensile tests to the relaxation tests, from the steel qualification tests to the resilience tests on elements at environmental conditions or at characterizing temperatures. The research work proposes a methodology for the virtualization of technical laboratories through the application of Building Information Modelling (BIM), starting from the creation of a digital model. The process includes the creation of an independent application, which with Oculus Rift technology will allow the user to explore the environment and interact with objects through the use of joypads. The application has been tested in prototype way on volunteers, obtaining results related to the acquisition of the educational notions exposed in the experience through a virtual quiz with multiple answers, achieving an overall evaluation report. The results have shown that MastrLAB-VR is suitable for both beginners and experts and will be adopted experimentally for other laboratories of the University departments

Computation of Relative 1-Cohomology Generators From a 1-Homology Basis for Eddy Currents Boundary Integral Formulations

Efficient boundary integral formulations based on stream functions for solving eddy current problems in thin conductors, which are modeled by the orientable combinatorial two-manifold with boundary, need generators of the first relative cohomology group to make the problem well defined. The state-of-the-art technique is to compute directly the relative cohomology generators with a combinatorial algorithm having linear worst-case complexity. In this paper, we propose to compute the relative cohomology generators from the homology generators, introducing a novel and general algorithm whose running time is again linear in the worst case. The advantage is that one may use an off-the-shelf software to compute the homology generators and implement only a simple and cheap procedure to obtain the required relative cohomology generators. Although the presented applications relate to ac power systems, the proposed technique is of general interest, and may be used for other applications in computational science and engineering. \ua9 2016 IEE

Numerical simulation framework for weakly coupled multiphysical problems in electrical engineering

Every engineering discipline faces the fact of ever-shortening time-to-market windows and development cycles. In order to counteract these, virtual prototyping, simulation and problem optimization are employed in a rapidly increasing number of cases. Yet, the key to efficient problem formulation by professionals still lies in the use of sophisticated simulation software capable of processing numerous diverse design and optimization tasks in a versatile way. More often than not, different tools for different workflows need to be coordinated and interdepend on each others data in the design process chain. When toolchains need to be run multiple times, as it is typically the case in numerical optimization, the lineup overhead tends to be tedious to both man and machine. This paper describes different aspects concerning the design of a software and data framework which tackles the problem of lining up software tools that may be incoherent in terms of data exchange and control mode. The resulting system covers all parts of multiphysical simulation problems that may arise in electrical engineering and its adjoining disciplines as an application of the finite element method

A validated dynamical model of a kW-class Vanadium Redox Flow Battery

The development of redox flow batteries depends on the research on new materials as well as on the technological development, but also on appropriate models which allow to simulate their performance in operative conditions. Very few investigations are reported in the literature concerning the technology, modeling and simulation of large-scale Vanadium Redox Flow Battery systems, built around multi-cell stacks. This paper regards the modeling of an industrial-sized 9 kW test facility. In particular, a complete dynamic model is presented, that takes into account all thermal effects occurring inside the stack, resulting in a complex non-linear coupled formulation, that allows to simulate the battery operation in any realistic conditions. The model is able to simulate the thermal behavior both in standby, i.e. without power and reactant flow, as well as in load operation, i.e. in charge and discharge. The numerical implementation of the model is described in detail. The model validation is also described, consisting in comparing computed data with experimental measurements taken on the available test facility