ELECTROCHEMICAL SEPARATION OF FERRO/FERRICYANIDE USING A MEMBRANE FREE REDOX FLOW CELL
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Mohammed H. Chakrabarti[1], Edward Roberts[2]
(NOTE: All the information in this document including authors, title, text, equations, tables and figures have been altered and pasted from different manuscripts for the purpose of sample manuscript format only.
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ABSTRACT
Different configurations (Perspex and PTFE) of a membrane free flow cell containing equimolar concentrations of the ferro/ferricyanide redox couple in potassium carbonate electrolyte with porous electrodes have been studied in this work. The optimum combination of parameters such as concentration, cell potential and electrolyte flow rate have been analysed and compared with a flow cell described in the literature. It was observed that if Perspex cells were empty at the start of the experiment then the conversion obtained was more consistent with the literature.
Keywords: (10 Keywords Maximum) temperature, finite element, stiffness, Unbonded reinforcement, flow cell, ferrocene redox, …………….
1. INTRODUCTION
Redox Flow Batteries (RFB), having higher energy storage capacity than conventional lead-acid or nickel-cadmium batteries, show unique design features and technical characteristics that are beneficial for number of industrial energy storage applications such as distributed power conditioning, large scale grid-connected levelling, diesel replacement in remote areas and photovoltaic applications [1,2].
2. EXPERIMENTAL TESTING
2.1 Reactor Design Considerations
Membrane-free prototype electrochemical reactors have been designed for evaluating both aqueous- and organic-based redox couples for applications in RFBs. To eliminate the need for a cell membrane, porous electrodes were used to act as both a conducting material with a high surface area for redox reactions and a separator to allow charged electrolytes to be pumped away to two storage tanks. This arrangement ensured that charged electrolytes had minimal opportunity to mix and self- discharge [9]. Each prototype reactor consisted of two half-cells ………………
2.2 Mechanical Properties of Concrete
The compressive strength and modulus of elasticity of concrete are known to decrease with the rise in temperature. The modulus of elasticity decreases more rapidly …………
2.2.1 Compressive strength
The compressive strength of concrete (fc) on the day of test is given in Table 1. The reduction factor (kc) for the compressive strength at elevated temperature…………...
2.2.2 Thermal capacitance
Thermal capacitance of concrete, which is also known as volume specific heat, is a product of concrete density (ρc) and specific heat at constant pressure (cc). Both these properties depend on concrete temperature. The density of concrete is considered as constant whilst the effects of temperature have been ignored. For a concrete density of 2300 kg/m3 (145 pcf) and 2% of water content, the specific heat, according to Eurocode 2 [15], is expressed as Eq. (1).
(1 kg = 2.205 lb) (1)
3. PROPOSED ANALYTICAL MODELS
For calculation of deflection and crack width at service load, modification in the formulations presented by BS 8110, Part 2, Section 3.7 and clause 3.8.3 respectively has been proposed, while for the stress in external unbonded and bonded reinforcement simplified assumptions have been made to arrive at a suitable ………..
4. COMPARISON OF RESULTS AND DISCUSSION
A comparison of the recorded and predicted temperature propagation and beam deflection has been presented in the forthcoming sections. Theoretical concrete stress distribution at the beam mid-span cross-section has also been plotted and analyzed.
4.1 Temperature Distribution
The experimental and calculated temperatures were compared for the beam BES1 as it outlasted other beams [7]. The virtual mesh of the beam was selected so as to have points corresponding to the thermocouple locations in the beam. The theoretical temperature distribution was found to be very sensitive to the heat transfer coefficient of the boundary layer and the mesh size. A value of h=80 W/m2/oC (1.4x10-5 Btu/hr/ft2/oF) has been used throughout and the maximum mesh size was taken as 40 mm (1.5 in). The positions of thermocouples are shown in Fig. 1.
4.2 Aqueous (Perspex) Prototype Flow Cell
Electrochemical separation tests were also carried out in the Perspex prototype cell. In the first test, the cell was full of electrolyte before commencing. The flow rate used was about …………………….
5. CONCLUSIONS
Experiments were performed with the prototype redox flow cell used by Bae [7]. The results obtained in this research agreed well with the literature [8] and the differences were attributed to slight differences in the flow rates used. A different prototype cell …………………………….
Following conclusions may be drawn from the study reported in this paper.
- External unbonded bars retrofitted to reinforced concrete beams provide useful enhancement in load carrying capacity and may be used ………………...
2. The simplified analytical models proposed to estimate service load deflections compares well with the measured results……………………..
ACKNOWLEDGMENTS
The authors wish to acknowledge the support provided for this research by ………………….
NOTATION
fy, Es = yield strength and modulus of elasticity of steel bar, respectively
ffu, Ef = ultimate strength and modulus of elasticity of FRP bar, respectively
REFERENCES
[1] Alsyed HS, Alhozaimy MA. Ductility of Concrete Beams Reinforced with FRP Bars and Steel Fibers. J Compos Mater 1999;33(19):1792-1806.
[2] Al-Salloum AY, Alsayed HS, Almusallam HT, Amjad AM. Some Design Considerations for Concrete Beams Reinforced by GFRP Bars. In: Saadatmanesh H, and Ehsani RM, Editors. Proceeding of First International Conference on Composites in Infrastructure. Tucson, Arizona: 1996. p. 318-331.
[3] Neville MA. Properties of concrete. England: Longman Scientific & Technical, England, 1981. p. 529-565.
[4] ConFibreCrete. Development of Guidelines for the Design of Concrete Structures, Reinforced, Prestressed or Strengthened with Advanced Composites, 2000 (updated 17 May 2000; accessed on 25 April 2005). Available from http://www.shef.ac.uk/~tmrnet
[5] Lodi SH. Reinforced Concrete Slab Elements Under Bending and Twisting Moments. PhD thesis. Heriot-Watt University, Edinburgh, 1997.
tables and figures
List of Tables:
Table 1 – Mechanical properties of concrete
List of Figures:
Fig. 1 – Typical mid-span section and positions of thermocouples.
Fig. 2 – Cracked concrete model.
Fig. 3 – Tension softening curve for concrete.
Table 1–Mechanical properties of concrete
Beam / fcMPa (psi) / Ec
MPa (ksi) / fct
MPa (psi) /
XXXX / 30.45 (4416) / 30225 (4384) / 2.93 (425)
YYYY / 35.89 (5205) / 33390 (4843) / 3.26 (473)
ZZZZ / 33.22 (4818) / 31041 (4502) / 3.10 (450)
Fig. 1 External bar anchorage at one of the ends
Fig. 2 Proposed relation of α with temperature
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[1]1 Assistant Professor, Department of Environmental Engineering, …. University of ……………..., Ph. +.. (0).. ………, Fax. +.. (0).. ………, Email
[2] Senior Lecturer, School of ……………, University of ……………..……………..., Ph. +.. (0).. ………, Fax. +.. (0).. ………, Email