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29 results on '"Allen, R. W. K."'

6. An investigation of CO2 splitting using nanosecond pulsed corona discharge: effect of argon addition on CO2 conversion and energy efficiency

Author

Universidad de Sevilla. Departamento de Física Aplicada II, Moss, M. S., Yanallah, Khelifa, Allen, R. W. K., Pontiga Romero, Francisco de Paula, Universidad de Sevilla. Departamento de Física Aplicada II, Moss, M. S., Yanallah, Khelifa, Allen, R. W. K., and Pontiga Romero, Francisco de Paula

Abstract

The plasma chemical splitting of carbon dioxide (CO2) to produce carbon monoxide (CO) in a pulsed corona discharge was investigated from both an experimental and a numerical standpoint. High voltage nanosecond pulses were applied to a stream of pure CO2 and its mixture with argon, and the gaseous products were identified using Fourier transform infrared spectroscopy. Due to the shape of pulses, the process of CO2 splitting was found to proceed in two phases. The first phase is dominated by ionization, which generates a high electron density. Then, during the second phase, direct electron impact dissociation of CO2 contributes to a large portion of CO production. Conversion and energy efficiency were calculated for the tested conditions. The conversions achieved are comparable to those obtained using other high pressure non-thermal discharges, such as dielectric barrier discharge. However, the energy efficiencies were considerably higher, which are favorable to industrial applications that require atmospheric conditions and elevated gas flow rates.

Published
2017

23. Evaluation of a Microfluidic Device for the Electrochemical Determination of Halide Content Sin Ionic Liquids.

Author

Ge, R., Allen, R. W. K., Aldous, L., Bown, M. R., Doy, Nicola, Hardacre, C., Maclnnes, J. M., McHale, G., and Newtons, M. I.

Subjects
*MICROFLUIDIC devices, *MICROTECHNOLOGY, *FLUIDIC devices, *ELECTROCHEMISTRY, *HALIDES, *IONIC liquids, *ELECTROCHEMICAL analysis, *VOLTAMMETRY, *SQUARE waves, *ELECTROMAGNETIC waves, *CHROMATOGRAPHIC analysis
Abstract

A microfluidic device designed for electrochemical studies on a microliter scale has been utilized for the examination of impurity levels in ionic liquids (ILs). Halide impurities are common following IL synthesis, and this study demonstrates the ability to quantify low concentrations of halide in a range of ILs to levels of ∼5 ppm, even in ILs not currently measurable using other methods such as ion chromatography. To validate the mixer device, the electrochemistry of ferrocene was also examined and compared with spectroscopic and bulk electrochemistry measurements. An automated "sample preparation, delivery, and calibration" method was developed, and the chip successfully used for linear sweep, cyclic voltammetry (under both quiescent and steady-state flowing conditions), square wave voltammetry, and differential pulse voltammetry. An effective method of electrochemically cleaning the electrodes is also presented. [ABSTRACT FROM AUTHOR]

Published
2009
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24. A Course in Experimentation.

Author

Fuller, O. M., Clift, R., Allen, R. W. K., Bhap, D., Faroer, R., Fung, D. T.-F., Munz, R. J., and Oberoi, A. S.

Published
1974

28. Performance degradation and recovery of YSZ membrane under sulphuric acid thermal decomposition

Author

He, Guanghu and Allen, R. W. K.

Subjects
660
Abstract

The effect of sulphur dioxide (SO2) present in the cathode feed stream on the performance of a 8 mole% yttria-stabilized zirconia/platinum (8YSZ/Pt) cell was studied. SO2 concentration of 30% in oxygen (5ml/min) and helium (30ml/min) was exposed to the cell applying an external dc voltage of 1.5V at 850˚C. Experiments showed that the cell performance had a sharp degradation (type I degradation) followed by a gradual degradation (type II degradation) inferred from current and oxygen permeate flux changes. Type II degradation may be related to formation of sulphide on cathode of membrane cell during the SO2 exposure period. Strong but short dc voltage pulses could reduce significantly membrane performance degradation impacting upon both charge transfer and mass transfer properties. In this work, the optimum voltage pulse for achieving the most stable membrane performance in SO2 exposure time was 10V, 0.08s length. High pulse frequency was helpful for achieving a high and stable membrane performance SO2 exposure tests lasting up to 2 hours. An oxygen separation process based on a YSZ tubular membrane was constructed and initial proof of concept experiments performed. Performance degradation by sulphur poisoning and recovery by voltage pulse of YSZ tubular membrane were also observed with this system. However, the oxygen permeation flux of the YSZ tubular membrane was lower than that of YSZ planar membrane, which may be related to YSZ thickness and the gas flow pattern. Initial experiments to integrate the membrane system into the thermal decomposition of H2SO4 to produce SO2 and O2 were carried out in a quartz tube reactor filled with an alumina supported Pt catalyst. A promising and feasible method of monitoring oxygen in-situ to determine acid conversion was proposed. Future work should concentrate on improvement of YSZ tubular membrane configuration and deeper integration of membrane operation and acid decomposition.

Published
2013

29. Development of a micro-channel contactor-separator for immiscible liquids.

Author

Chan, T. Y., Priestman, G. H., MacInnes, J. M., and Allen, R. W. K.

Subjects
*MICROCHANNEL flow, *MASS transfer, *ETCHING, *OIL separators, *LIQUID-liquid interfaces, *MICROFLUIDICS
Abstract

A new concept of micro-channel contactor-separator is developed for operation with immiscible liquids. It has potential for application with micro-reactors or for mass transfer operations. A prototype device is made in glass using a photo-chemical etching process, including etching across a gap to produce sections of shallow channel. It is tested using oil and water, and the behaviour studied using amicroscope in conjunction with a digital video camera. The basis of operation is to use a simple T-junction to produce slugs of typically the oil phase in the water phase. The slugs then flow along a straight channel toward a separation section, which consists of small side channels running perpendicular from the main channel. The side channels carry water to the water outlet, whilst the oil flows out along the main channel. The side channels have a restricted opening where they join the main channel and the extra interfacial force at this point is intended to prevent the oil phase from entering. The operating conditions over which the system operated successfully were determined experimentally. These were found to agree reasonably well with conditions predicted based on CFD analysis. [ABSTRACT FROM AUTHOR]

Published
2008
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