The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
P. Choi - One of the best experts on this subject based on the ideXlab platform.
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Effect of Operating Pressure on Plasma Formation in the Transient Hollow Cathode Discharge
AIP Conference Proceedings, 2008Co-Authors: C. S. Wong, P. ChoiAbstract:The discharge development of a triggered pulsed hollow cathode discharge is investigated with respect to two regimes of Operating Pressure: the high Pressure regime at ∼ 10−2 mbar and the low Pressure regime at ∼ 10−5 mbar. The hollow cathode discharge studied here is performed with the UMFX device powered by either eight 2700 pF door‐knob capacitors connected in parallel and discharged at 40 kV or a single 1.85 μF capacitor discharged at 20 kV. The characteristics of the discharge is monitored by using magnetic probe for dI/dt measurement; PIN diodes and XRD for time‐resolved X‐ray signals; and pinhole camera for time‐integrated X‐ray imaging. At the high Operating Pressure regime, X‐rays are observed to be emitted from the tip of the anode only. At the low Operating Pressure regime, however, the heating of the plasma by the main capacitor discharge is significantly enhanced. In the case of low energy discharge (with 22 nF capacitor bank), a plume‐like plasma emitting in the soft X‐ray region is observed...
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Characteristics of a vacuum spark triggered by the transient hollow cathode discharge electron beam
IEEE Transactions on Plasma Science, 1995Co-Authors: C. S. Wong, P. ChoiAbstract:The discharge characteristics of a vacuum spark triggered by the transient hollow cathode discharge (THCD) electron beam is investigated over a wide variety of discharge conditions. Two systems of the vacuum spark device have been considered-the first system powered by eight 2700-pF doorknob capacitors charged to a voltage of 40 kV (input energy of 17.6 J); while the second system employs a single 1.85-/spl mu/F Maxwell capacitor discharged at a voltage of 20 kV (input energy of 370 J). The Operating Pressure of these systems has been varied over the range of 10/sup -2/ to 10/sup -5/ mbar in order to examine the effect of the Operating Pressure on the plasma formation of the vacuum spark discharge. The effectiveness of plasma heating has been found to be significantly enhanced in the two vacuum spark systems studied here. In particular, the plasma of the 17.6 J system has been observed to be heated to a condition hot enough to emit in the X-ray region when the Operating Pressure is reduced from 10/sup -2/ to 10/sup -5/ mbar. Similarly, in the case of the 370 J system, hot spot formation is also observed to occur only at a low Operating Pressure of 10/sup -4/ mbar.
C. S. Wong - One of the best experts on this subject based on the ideXlab platform.
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Effect of Operating Pressure on Plasma Formation in the Transient Hollow Cathode Discharge
AIP Conference Proceedings, 2008Co-Authors: C. S. Wong, P. ChoiAbstract:The discharge development of a triggered pulsed hollow cathode discharge is investigated with respect to two regimes of Operating Pressure: the high Pressure regime at ∼ 10−2 mbar and the low Pressure regime at ∼ 10−5 mbar. The hollow cathode discharge studied here is performed with the UMFX device powered by either eight 2700 pF door‐knob capacitors connected in parallel and discharged at 40 kV or a single 1.85 μF capacitor discharged at 20 kV. The characteristics of the discharge is monitored by using magnetic probe for dI/dt measurement; PIN diodes and XRD for time‐resolved X‐ray signals; and pinhole camera for time‐integrated X‐ray imaging. At the high Operating Pressure regime, X‐rays are observed to be emitted from the tip of the anode only. At the low Operating Pressure regime, however, the heating of the plasma by the main capacitor discharge is significantly enhanced. In the case of low energy discharge (with 22 nF capacitor bank), a plume‐like plasma emitting in the soft X‐ray region is observed...
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Characteristics of a vacuum spark triggered by the transient hollow cathode discharge electron beam
IEEE Transactions on Plasma Science, 1995Co-Authors: C. S. Wong, P. ChoiAbstract:The discharge characteristics of a vacuum spark triggered by the transient hollow cathode discharge (THCD) electron beam is investigated over a wide variety of discharge conditions. Two systems of the vacuum spark device have been considered-the first system powered by eight 2700-pF doorknob capacitors charged to a voltage of 40 kV (input energy of 17.6 J); while the second system employs a single 1.85-/spl mu/F Maxwell capacitor discharged at a voltage of 20 kV (input energy of 370 J). The Operating Pressure of these systems has been varied over the range of 10/sup -2/ to 10/sup -5/ mbar in order to examine the effect of the Operating Pressure on the plasma formation of the vacuum spark discharge. The effectiveness of plasma heating has been found to be significantly enhanced in the two vacuum spark systems studied here. In particular, the plasma of the 17.6 J system has been observed to be heated to a condition hot enough to emit in the X-ray region when the Operating Pressure is reduced from 10/sup -2/ to 10/sup -5/ mbar. Similarly, in the case of the 370 J system, hot spot formation is also observed to occur only at a low Operating Pressure of 10/sup -4/ mbar.
Andreas Lemmer - One of the best experts on this subject based on the ideXlab platform.
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Influence of Operating Pressure on the biological hydrogen methanation in trickle-bed reactors
Bioresource Technology, 2018Co-Authors: Timo Ullrich, Frank Graf, Jonas Lindner, Katharina Bär, Friedemann Mörs, Andreas LemmerAbstract:In order to investigate the influence of Pressures up to 9 bar absolute on the productivity of trickle-bed reactors for biological methanation of hydrogen and carbon dioxide, experiments were carried out in a continuously operated experimental plant with three identical reactors. The Pressure increase promises a longer residence time and improved mass transfer of H2 due to higher gas partial Pressures. The study covers effects of different Pressures on important parameters like gas hourly space velocity, methane formation rate, conversion rates and product gas quality. The methane content of 64.13 ± 3.81 vol-% at 1.5 bar could be increased up to 86.51 ± 0.49 vol-% by raising the Pressure to 9 bar. Methane formation rates of up to 4.28 ± 0.26 m3 m−3 d−1 were achieved. Thus, Pressure increase could significantly improve reactor performance.
Rong Wang - One of the best experts on this subject based on the ideXlab platform.
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polyamide imide hollow fiber membranes crosslinked with amine appended inorganic networks for application in solvent resistant nanofiltration under low Operating Pressure
Journal of Membrane Science, 2016Co-Authors: Laurentia Setiawan, Rong WangAbstract:Abstract The development of polyamide-imide (PAI) hollow fiber membranes for solvent-resistant nanofiltration (SRNF) in polar aprotic solvents such as dimethylformamide (DMF) under low Operating Pressure of 2 bar is reported in current study. Highly porous PAI substrates were fabricated and crosslinked with (3-aminopropyl)trimethoxysilane (APTMS). The resultant membranes were solvent-stable and showed higher hydrophilicity and better mechanical property. A 30-min conditioning with either isopropanol or deionized water after the crosslinking reaction was found to affect the morphology of the membranes and thus their nanofiltration performance. Membranes conditioned with isopropanol consistently showed higher solvent fluxes coupled with lower rejections of Rose Bengal (RB) ranging 75–87%. On the other hand, membranes conditioned with deionized water had lower fluxes and high RB rejections of 96–99%. The best-performing membrane achieved a permeability of 6.4 L/(m2 h bar) in IPA and 0.9 L/(m2 h bar) in DMF with RB rejections of over 97% and 98%, respectively, under 2 bar Operating Pressure, showing their potential to be used in SRNF processes effectively.
Aaron D. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic analysis of energy density in Pressure retarded osmosis: The impact of solution volumes and costs
Journal of Membrane Science, 2015Co-Authors: Kevin K. Reimund, Jeffrey R. Mccutcheon, Aaron D. WilsonAbstract:A general method was developed for estimating the volumetric energy efficiency of Pressure retarded osmosis via Pressure-volume analysis of a membrane process. The resulting model requires only the osmotic Pressure, π, and mass fraction, w, of water in the concentrated and dilute feed solutions to estimate the maximum achievable specific energy density, u, as a function of Operating Pressure. The model is independent of any membrane or module properties. This method utilizes equilibrium analysis to specify the volumetric mixing fraction of concentrated and dilute solution as a function of Operating Pressure, and provides results for the total volumetric energy density of similar order to more complex models for the mixing of seawater and riverwater. Within the framework of this analysis, the total volumetric energy density is maximized, for an idealized case, when the Operating Pressure is π/(1+w-1), which is lower than the maximum power density Operating Pressure, δπ/2, derived elsewhere, and is a function of the solute osmotic Pressure at a given mass fraction. It was also found that a minimum 1.45. kmol of ideal solute is required to produce 1. kWh of energy while a system Operating at "maximum power density Operating Pressure" requires at least 2.9. kmol. Utilizing this methodology, it is possible to examine the effects of volumetric solution cost, operation of a module at various Pressure, and operation of a constant Pressure module with various feed.
