Segmented printed circuit board electrode for locally-resolved current density measurements in all-vanadium redox flow batteries

One of the most important parameters for the design of redox flow batteries is a uniform distribution of the electrolyte solution over the complete electrode area. The performance of redox flow batteries is usually investigated by general measurements of the cell in systematic experimental studies such as galvanostatic charge-discharge cycling. Local inhomogeneity within the electrode cannot be locally-resolved. In this study a printed circuit board (PCB) with a segmented current collector was integrated into a 40 cm2 all-vanadium redox flow battery to analyze the locally-resolved current density distribution of the graphite felt electrode. Current density distribution during charging and discharging of the redox flow battery indicated different limiting influences. The local current density in redox flow batteries mainly depends on the transport of the electrolyte solution. Due to this correlation, the electrolyte flow in the porous electrode can be visualized. A PCB electrode can easily be integrated into the flow battery and can be scaled to nearly any size of the electrode area. The carbon coating of the PCB enables direct contact to the corrosive electrolyte, whereby the sensitivity of the measurement method is increased compared to state-of-the-art methods

Towards an approach for analysing external representations created during sensemaking using generative grammar

During sensemaking, users often create external representations to help them make sense of what they know, and what they need to know. In doing so, they necessarily adopt or construct some form of representational language using the tools at hand. By describing such languages implicit in representations we believe that we are better able to describe and differentiate what users do and better able to describe and differentiate interfaces that might support them. Drawing on approaches to the analysis of language, and in particular, Mann and Thompson’s Rhetorical Structure Theory, we analyse the representations that users create to expose their underlying ‘visual grammar’. We do this in the context of a user study involving evidential reasoning. Participants were asked to address an adapted version of IEEE VAST 2011 mini challenge 3 (interpret a potential terrorist plot implicit in a set of news reports). We show how our approach enables the unpacking of the heterogeneous and embedded nature of user-generated representations and allows us to show how visual grammars evolve and become more complex over time in response to evolving sensemaking needs

Methode zur Speicherung von elektrischer Energie in ionischen Fluessigkeiten

WO 2010094657 A1 UPAB: 20100908 NOVELTY - The redox-flow-battery comprises a water-free electrolyte having ionic fluid, positive and negative half cells (f) having ionic fluid, where the ionic fluids are same or different, and vanadium ions (V4+/V5+) as redox-pair for the positive half cell and V4+/V3+ as the redox pair for the negative half cell. The electrolyte comprises 0.1 wt.% of the ionic liquid(s). The operating temperature of the redox-flow-battery is -30 degrees C to 400 degrees C. The concentration of the vanadium ion in the electrolyte is 0.1-10 mol/l. DETAILED DESCRIPTION - The redox-flow-battery comprises a water-free electrolyte having ionic fluid, positive and negative half cells (f) having ionic fluid, where the ionic fluids are same or different, and vanadium ions (V4+/V5+) as redox-pair for the positive half cell and V4+/V3+ as the redox pair for the negative half cell. The electrolyte comprises 0.1 wt.% of the ionic liquid(s). The operating temperature of the redox-flow-battery is -30 degrees C to 400 degrees C. The concentration of the vanadium ion in the electrolyte is 0.1-10 mol/l. The redox pair is formed from the ionic liquid in both half cells of the redox-flow-battery. The electrolyte does not include the additive of stabilizing agent, acids and/or bases. The electrode (b) of the battery is metallic electrode, diamond electrode or indium-tin-oxide electrode. USE - Used as redox-flow-battery. ADVANTAGE - The redox-flow-battery has improved variability in selection of operating parameters such as temperature or selection of electrode material

Multiple headspace extraction for gas detection in ionic liquids

In this study multiple headspace extraction was used for the first time to measure the saturation concentration of carbon monoxide and oxygen in various ionic liquids (ILs). Many processes in ILs involve the reaction of gases so that the reactant solubility is not a mere characteristical parameter, but understanding the solubility of gases in ILs is required for assessing the feasibility of possible applications. Multiple headspace extraction has proofed to be a powerful tool to obtain solubilities in good accordance with literature data. The measured saturation concentration for carbon monoxide and oxygen in ILs based on rarely researched tetracyanoborates and other anions was in the range of 1.5-6.5 mmol/L. The great advantage of multiple headspace extraction is that it is a nonexpensive method that can be realised in most analytical laboratories by combination of a simple gas chromatograph and an eligible headspace injector

Development Study of an Air Independent Fuel Cell System for an Autonomous Underwater Vehicle

The paper is focused on the design concept of a fuel cell system for an autonomous underwater vehicle (AUV) developed within a common project of the German Navy research institute WTD 71, Fraunhofer ICT and the norwegian defense research institute “Forsvarets forskningsinstitutt (FFI)”. The presented work is therefore based on the boundary conditions for the system defined in this project. However, a more general approach is pursued by not only presenting the developed fuel cell system, but by defining a design strategy and applying it to the framework of the development in the project. For this, constraints and objectives which define the development will be defined as boundary conditions. Most of these boundary conditions also apply to the general development of air independent underwater systems and can therefore be used to outline similar systems. Based on the literature and the constraints, system and subsystem solutions for fuel cell systems are discussed to find the most suiting system for the AUV. The different system solutions are discussed on the basis of different objectives for the system design, namely space, runtime, stability and efficiency