Effects Of Liquid Conductivity Research Articles

Effect of liquid conductivity on optical and electric performances of the electrowetting display system with a thick dielectric layer

The effect of liquid conductivity on both the optical and electric performances of the electrowetting display system with a thick fluoropolymer insulating layer was investigated in this study. Low-conductivity deionized water and aqueous ionic solutions with different conductivities were used as the conducting liquids and tested in both the open electrowetting systems and the electrowetting display devices. The sessile droplet test was used to study the electrowetting performance of liquid droplets with different conductivities on fluoropolymer coated electrode and an experimental platform was designed to measure the leakage current of the liquid/fluoropolymer/electrode contact. 2.7-inch EWD specimens were also prepared for the experiments. The on-switching response time, the maximum aperture ratio of pixels and the current-voltage characteristic on device level were studied experimentally. We focused on the influence of liquid conductivity on the optical performance of the electrowetting displays. The test showed that, with deionized water, the leakage current value of the EWD cell was lower than 10 nA/cm2 at 30 V, while the average on-switching time and maximum aperture ratio water were 37.8 ms and 46.7%, respectively. The using of low-conductivity water as conducting liquid in electrowetting displays with a thick fluoropolymer insulating layer was discussed.

Analysis of Electrical Discharge Plasma in a Gas‐Liquid Flow Reactor Using Optical Emission Spectroscopy and the Formation of Hydrogen Peroxide

Optical emission spectroscopy was used to characterize an electrical discharge plasma reactor with a liquid H2O film contacting different carrier gases. The plasma gas temperatures for Ar, He, and 1% N2 in Ar were 1000–1200 K and did not vary significantly with liquid flow rate. Increasing solution conductivity by adding KCl to deionized water in the Ar case lowered the temperature by 13%, increased the discharge power and lowered the H2O2 formation rates. The temperature was highest in the case of air (2400 K), and in the case of Ar the temperature increased with the addition of O2. The temperatures for this reactor are comparable to previous studies with discharges in humid gases, while the effects of liquid conductivity were similar to those reported with direct discharge in the liquid phase.

Effects of liquid conductivity upon gaseous discharge of droplets

The effect that liquid conductivity has upon gaseous breakdown and conduction between a droplet and a sharp grounded metal point was investigated as a function of the droplet charge level and point-to-droplet gap. A uniform stream of equally spaced 1210 mu m droplets was studied in passing the point at 2.05 m/s at a rate of 465/s. The negative droplet charge was set at 24, 40, 55, and 60% of the Rayleigh hydrodynamic instability limit (i.e. 3*10/sup -10/ C) for liquid conductivity values in the 10/sup -4/-10/sup 1/ S/m range characterizing electrostatic crop sprays. No significant conductivity effect was found for charges up to the 55% level; the most conductive liquid exhibited a significantly ( alpha <0.10) higher discharge current at the 60% charge level. For close gaps, droplets departed the grounded point region with a reversed charge, indicating they were overneutralized by a positive-ion flux from the grounded point.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Investigations into the mechanisms of electrohydrodynamic spraying of liquids: I. Effect of electric field and the environment on pendant drops and factors affecting the formation of stable jets and atomization

The effect of an applied electric field on pendant and flowing drops (through a capillary) was studied by observing the droplet profile as a function of applied voltage. With pendant drops of hexadecane, application of the electric field caused a reduction in the apparent surface tension, γ app. In surrounding gases such as N 2, CO 2, and Ar, droplet profiles similar to those in air were observed. While gases such as He and Ne have low breakdown potentials, no change in droplet profile upon application of an electric field was detectable. The glow discharge in He was investigated for oil (insulator), water, glycerol, and a brass tip, for both positive and negative potentials. Conducting liquids such as water and glycerol permitted discharge to take place from the surface of the droplet, whereas insulating oils forced the discharge to occur at the metal tip, where the drop is attached. With flowing drops, the liquid conductivity was a major factor in the electrostatic disruption of the liquid surface. With insulating liquids such as paraffinic oil, no disruption occurred due to the lack of sufficient free ions in the bulk liquid. With conducting liquids such as water, very unstable streams were produced. Stable jets having a conical base were only produced with semiconducting liquids (nonpolar liquids with dissolved ionic materials). The cone angle at the base of the jet increased, whereas its length decreased with an increase in applied voltage. At higher voltages, secondary jets were produced from the primary one, whose number increased with an increase in the applied field. The effect of liquid conductivity, applied voltage, flow rate, and capillary diameter on the stability of jets was investigated by measuring the critical voltage, φ c, at which transition from the pulsating mode to the stable jet mode occurred. By measuring the current carried by the jet, the charge-to-mass ratio could also be calculated. Some measurements of droplet size distribution were made using a practical sprayer and a particle measuring system for measuring droplet diameters in flight. These measurements were made as a function of applied voltage, conductivity, and flow rate. The results obtained clearly demonstrate the importance of applied voltage, liquid conductivity and flow rate in the formation of stable jets and the subsequent process of electrohydrodynamic atomization. At a given voltage and flow rate an optimum conductivity range is necessary for producing the most stable jet, the narrowest size distribution, and the smallest droplet size. This could be accounted for in terms of the electric forces acting on the liquid, which are related to the relaxation time of the liquid. The influence of flow rate on the production of stable jets and the subsequent atomization could also be understood in terms of the inertial and electrostatic forces which act in the same direction. At a given conductivity and voltage, stability is enhanced by increasing the flow rate, but at the expense of producing larger droplets.