Flow Cell Characterisation: Flow Visualisation, Pressure Drop and Mass Transport at 2D Electrodes in a Rectangular Channel

The reaction environment in a C-Flow Lab 5 × 5® laboratory-scale electrochemical flow cell was characterised in terms of fluid flow, hydraulic pressure drop and space averaged mass transport coefficient. The cell was studied in flow-by configuration with smooth, planar electrodes within its rectangular flow channels. The effect of a turbulence promoter (a polymer mesh with a volumetric porosity of 0.84) placed next to the working electrode was also evaluated. Electrolyte volumetric flow rates ranged from 0.3 to 1.5 dm3 min-1, corresponding to mean linear velocities of 2 to 10 cm s-1 past the electrode surface and channel Reynolds numbers of 53 to 265. The pressure drop was measured both over the electrode channel and through the whole cell as a function of mean linear velocity. The electrochemical performance was quantified using the limiting current technique, which was used to determine the mass transport coefficient over the same range of flow rate. Results were compared to well-characterised electrochemical flow reactors found in the literature. The mass transport enhancement factor due to the presence of the turbulence promoter was between 1.6 and 3.9 under the studied conditions. Reactant conversion in batch recirculation mode and normalised space velocity were predicted from the electrochemical plug flow reactor equation

Pyroelectric effect enhancement through product property under open circuit condition

An analytical model for the pyroelectric (PY) effect under open circuit condition and 2-2 connectivity laminates of various pairs of PY and nonpyroelectric (NP)/elastic materials has been developed. It is evident from our analysis that there indeed is a substantial dissimilarity between the PY coefficients and figure of merit for efficiency for various PY-NP pairs under short circuit and open circuit conditions. We believe this implies that there should be a greater distinction made between the PY coefficients under these two electrical conditions than previously thought. The indicators for various PY-NP material pairs that can be utilized to determine their PY coefficient enhancement potential under open circuit condition have been identified. The investigated PY materials are lead zirconate titanate (PZT-5H and PZT-5A), barium titanate, lithium tantalate, lithium niobate, and polyvinylidene fluoride (PVDF), while the NP materials are stainless steel, polytetrafluoroethylene (PTFE or Teflon), chlorinated polyvinyl chloride thermoplastic (CPVC), aluminum, zinc, and Invar 36. Extraordinarily large PY coefficient of 97×10-4 C m-2 K-1 at minimum thickness ratio Rmin is expected for PZT-5H-CPVC pair while PVDF-CPVC could show increase in the secondary PY coefficient of up to 350%. In addition, where the figure of merit for efficiency is concerned, for the same volume of the composite PZT-5A-PTFE pair it reaches 24, a 24-fold increase in efficiency at Rmin. Our analysis techniques should provide a methodological way for appraising the potentials of particular PY material and its 2-2 laminates for applications under open circuit condition such as PY X-ray generation, electron accelerator, and nuclear fusion

Control of volume resistivity in inorganic organic separators

Control of resistivity in NASA inorganic-organic separators is achieved by incorporating small percentages of high surface area, fine particle silica with other ingredients in the separator coating. The volume resistivity is predictable from the surface area of filler particles in the coating. The approach is applied to two polymer- plasticizer -filler coating systems, where the filler content of each is below the generally acknowledged critical pigment volume concentration of the coating. Application of these coating systems to 0.0254 cm thick (10-mil) fuel cell grade asbestos sheet produces inexpensive, flexible, microporous separators that perform as well as the original inorganic-organic concept, the Astropower separator

Improved, low cost inorganic-organic separators for rechargeable silver-zinc batteries

Several flexible, low-cost inorganic-organic separators with performance characteristics and cycle life equal to, or better than, the Lewis Research Center Astropower separator were developed. These new separators can be made on continuous-production equipment at about one-fourth the cost of the Astropower separator produced the same way. In test cells, these new separators demonstrate cycle life improvement, acceptable operating characteristics, and uniform current density. The various separator formulas, test cell construction, and data analysis are described

Team One Carbon Catcher Design Report

Overview The burning of fossil fuels largely contributes to the increase of CO2 in the atmosphere. The US Department of Transportation alone contributed almost 6 million metric tons of carbon dioxide emissions in 2018 (EIA). Due to this, this report proposes recycling captured CO2 into a base for cleaner burning fuel in order to reduce emissions from the transportation industry and many others, which has the potential to impact many areas. Extraction of atmospheric CO2 is possible through a membrane filtration system based on traditional nitrogen generation. The passive filtration system autonomously separates the CO2 from other air components, thereby reducing energy consumption. The system's working sensors and actuators utilize similar energy saving strategies, such as distributing cloud-computing services over multiple servers and mainframes to reduce computing power. The movement of air is directed by a scalable fan device, which is presented as a modular design to allow customization of fan parts to specific size and installation requirements. As an integrated device, Team 1’s Carbon Catcher operates with a high efficiency in order to maximize the commercial opportunity of converting captured CO2 into cleaner fuel while also reducing CO2 emissions and the greenhouse effect. Goal The goal of Team 1’s Carbon Catcher project proposal is to design a cost-effective, scalable, and modular atmospheric carbon dioxide removal system that is capable of being utilized in a range of urban environments and may fit a variety of different customer requirements or requests

Whitham's equations for modulated roll-waves in shallow flows

This paper is concerned with the detailed behaviour of roll-waves undergoing a low-frequency perturbation. We rst derive the so-called Whitham's averaged modulation equations and relate the well-posedness of this set of equations to the spectral stability problem in the small Floquet-number limit. We then fully validate such a system and in particular, we are able to construct solutions to the shallow water equations in the neighbourhood of modulated roll-waves proles that exist for asymptotically large time

Partial-wave analysis of the eta pi+ pi- system produced in the reaction pi-p --> eta pi+ pi- n at 18 GeV/c

A partial-wave analysis of 9082 eta pi+ pi- n events produced in the reaction pi- p --> eta pi+ pi- n at 18.3 GeV/c has been carried out using data from experiment 852 at Brookhaven National Laboratory. The data are dominated by J^{PC} = 0^{-+} partial waves consistent with observation of the eta(1295) and the eta(1440). The mass and width of the eta(1295) were determined to be 1282 +- 5 MeV and 66 +- 13 Mev respectively while the eta(1440) was observed with a mass of 1404 +- 6 MeV and width of 80 +- 21 MeV. Other partial waves of importance include the 1++ and the 1+- waves. Results of the partial wave analysis are combined with results of other experiments to estimate f1(1285) branching fractions. These values are considerably different from current values determined without the aid of amplitude analyses.Comment: 22 pages, 8 figure

Pyroelectric effect enhancement in laminate composites under short circuit condition

The pyroelectric coefficients of laminate composites under short circuit condition have been investigated by analytical modeling and numerical simulations. Indicators for various pyroelectric/non-pyroelectric material pairs that can be utilized to determine their pyroelectric coefficient enhancement credentials have been identified. Six pyroelectric materials were paired with six non-pyroelectric/elastic materials and their pyroelectric coefficient enhancement potential and figure of merit for efficiency were investigated. The best performing partnership out of the 36 pairs was lead zirconate titanate (PZT5H)-chlorinated polyvinyl chloride thermoplastic (CPVC) for thickness ratios (R) below 0.09 and PZT5H-zinc for R larger than 0.09 with both demonstrating total pyroelectric coefficient of approximately -20x10(-4) C m(-2) K(-1) at R=0.09, which corresponds to approximately 300% increase in the coefficient. PZT5H-CPVC also showed maximum of 800% rise in the pyroelectric coefficient while figure of merit for efficiency indicated up to twentyfold increase in its electrical response output per given thermal stimuli when compared to that of PZT5H by itself

Torque rheology of zircon feedstocks for powder injection moulding

In this work, a cellulose acetate butyrate (CAB) and polyethylene glycol (PEG) blend is used as the binder system in a zirconium silicate mineral powder feedstock for powder injection moulding. These irregular zircon powders make the mixing process and the selection of an optimal solid loading level a difficult task. Torque rheology methodologies combined with other techniques are used for evaluation of the parameters affecting the mixing process and determination of the critical powder volume concentration (CPVC). Temperature variations during the mixing process are monitored and used as an indicator of the friction energy of the system and thus for the optimal solid loading selection. There have thus far been limited amounts of work conducted on torque rheology of highly loaded feedstocks that incorporate a study of the system's temperature evolution. A detailed study could be a key factor for understanding the mixing behaviour of highly loaded feedstocks.The authors would like to acknowledge the companies GUZMÁNGLOBAL S.L and ALFAMIMTech for their support and partnership in the project IPT-2011-0931-020000 granted from the Spanish Ministry of the Economy and Competitiveness and the European Funds for Regional Development (FEDER). They would also kindly thank the Applied Mechanics Department of FEMTO-ST Institute and the ENSMM (Besançon, France) where some of the experimental works were performed. The suggestions and technical support of T. Barriere and G. Michele were much appreciated