Electric Field Effects on the Stability of Vapor Microlayers: Enhancement of Heat Transfer

Materials ◽  
2003 ◽  
Author(s):  
Subramanian Sankaran ◽  
Jeffrey S. Allen ◽  
Leonard Gumennik
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Heat Fluxes ◽  
Enhancement Of Heat Transfer ◽  
Electric Field Effects ◽  
Heater Wire ◽  
Experimental Parameters ◽  
Flux Level ◽  
The Stability ◽  
The Relationship

The effect of dc electric fields on destabilization of a vapor microlayer formed during film boiling at various subcooling levels is investigated. High voltage electric fields up to 2000 volts were applied between a 127 μm heater wire and a screen electrode that is concentrically placed at a radius of 25 mm. The qmax and qmin heat fluxes were also measured for the various subcooling and electric field strengths. Up to 50% increase in the qmax and the qmin heat fluxes were observed when using the electric fields in this range of experimental parameters. The relationship among subcooling level for a given fluid, the heat flux level, and the electric field strength required to reach the qmin condition is of interest. The preliminary experimental results and the bubble departure and transition boiling patterns resulting from destabilization of the vapor microlayer are discussed.

Directionality and the Role of Polarization in Electric Field Effects on Radical Stability

2017 ◽  
Vol 70 (4) ◽  
pp. 367 ◽  
Author(s):  
Ganna Gryn'ova ◽  
Michelle L. Coote
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Radical Reactions ◽  
Electric Field Effects ◽  
Dissociation Energies ◽  
Barrier Heights ◽  
Diol Dehydratase ◽  
Group A ◽  
Activity Of Enzymes ◽  
The Stability

Accurate quantum-chemical calculations are used to analyze the effects of charges on the kinetics and thermodynamics of radical reactions, with specific attention given to the origin and directionality of the effects. Conventionally, large effects of the charges are expected to occur in systems with pronounced charge-separated resonance contributors. The nature (stabilization or destabilization) and magnitude of these effects thus depend on the orientation of the interacting multipoles. However, we show that a significant component of the stabilizing effects of the external electric field is largely independent of the orientation of external electric field (e.g. a charged functional group, a point charge, or an electrode) and occurs even in the absence of any pre-existing charge separation. This effect arises from polarization of the electron density of the molecule induced by the electric field. This polarization effect is greater for highly delocalized species such as resonance-stabilized radicals and transition states of radical reactions. We show that this effect on the stability of such species is preserved in chemical reaction energies, leading to lower bond-dissociation energies and barrier heights. Finally, our simplified modelling of the diol dehydratase-catalyzed 1,2-hydroxyl shift indicates that such stabilizing polarization is likely to contribute to the catalytic activity of enzymes.

Tuning the inter-molecular charge transfer, second-order nonlinear optical and absorption spectra properties of a π-dimer under an external electric field

2017 ◽  
Vol 19 (47) ◽  
pp. 31958-31964 ◽  
Author(s):  
Feng-Wei Gao ◽  
Hong-liang Xu ◽  
Zhong-Min Su
Keyword(s):  
Charge Transfer ◽  
Electric Field ◽  
Electric Fields ◽  
Nonlinear Optical ◽  
Stability Control ◽  
External Electric Fields ◽  
Optical Responses ◽  
Molecular Charge ◽  
Spectra Properties ◽  
The Stability

Different strengths of external electric fields enhance the stability, control the inter-molecular charge transfer and strengthen the nonlinear optical responses of a π-dimer.

Electric Field and Spinning Performance in Needleless Electrospinning

2014 ◽  
Vol 1048 ◽  
pp. 26-30 ◽  
Author(s):  
Xin Wang ◽  
Yuan Zhao ◽  
Hao Wang ◽  
Guang Ming Cai
Keyword(s):  
Experimental Investigation ◽  
Electric Field ◽  
Scale Up ◽  
Key Factors ◽  
Needleless Electrospinning ◽  
Modeling Analysis ◽  
Experimental Parameters ◽  
Spun Fiber ◽  
The Relationship

Different spinnerets can be used to generate needleless electrospinning with the potential to scale up the production of nanofibers. However, the electrospinning performance, normally refers to the quality of the as-spun fiber and the production rate, is dramatically different from different spinnerets. This study focuses on the electric field of different spinnerets under the same experimental parameters so as to understand the key factors that affect the electrospinning performance of upward needleless electrospinning. Modeling analysis suggested that the electric field could be further concentrated by optimizing the geometry of spinneret. Experimental investigation on needleless electrospinning from different spinnerets proved that the electrospinning performance was improved greatly with the optimization of the electric field of spinneret. Understanding of the relationship between electric field and spinning performance would benefit the design and development of needleless electrospinning.

Electrorheology

MRS Bulletin ◽  
1991 ◽  
Vol 16 (8) ◽  
pp. 38-43 ◽  
Author(s):  
Therese C. Jordan ◽  
Montgomery T. Shaw
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
High Speed ◽  
Flow Properties ◽  
Electric Field Effects ◽  
Properties Of Materials ◽  
Strong Electric Fields ◽  
Silica Suspensions ◽  
Type Of Behavior ◽  
Damping Systems

The influence of electric fields on the deformation and flow properties of materials has been a subject of interest for many years. Recently, there has been renewed interest in a particular branch of these electric field effects—the electrorheological (ER) effect. The ER effect is also known as the Winslow effect after its founder Willis Winslow. Winslow observed that applying strong electric fields to nonaqueous silica suspensions activated with a small amount of water caused rapid solidification of the originally fluid material. This type of behavior was seen as instrumental in the development of high-speed valves, reactive damping systems, and a host of other applications.

Investigation of Retention Properties for YMnO3 Based Metal/Ferroelectric/Insulator/Semiconductor Capacitors

2003 ◽  
Vol 784 ◽  
Author(s):  
T. Yoshimura ◽  
D. Ito ◽  
H. Sakata ◽  
N. Shigemitsu ◽  
K. Haratake ◽  
...  
Keyword(s):  
Electric Field ◽  
Leakage Current ◽  
Electric Fields ◽  
Retention Time ◽  
Memory Retention ◽  
Frenkel Emission ◽  
Transient Spectroscopy ◽  
Leakage Current Mechanism ◽  
Capacitance Transient ◽  
The Relationship

ABSTRACTThe memory retention properties of Pt/YMnO3/Y2O3/Si capacitors were investigated for the application of ferroelectric gate transistors. The epitaxially grown Pt/YMnO3/Y2O3/Si capacitors showed ferroelectric type hysteresis loop on the capacitance-voltage properties. Although the retention time of the as-deposited capacitors was ∼103 s, it was prolonged up to 104 s when the leakage current density was reduced from 4×10-8 A/cm2 to 2×10-9 A/cm2 by the annealing under N2 ambience. To reveal the relationship between the retention time and leakage current, the leakage current mechanism was investigated comparing several conduction mechanisms. It was found that the dominant leakage mechanisms at high and low electric fields were Poole-Frenkel emission from the Y2O3 layer and ohmic conduction, respectively. This result indicates that the leakage current was limited by the Y2O3 layer at high electric field and was mainly dominated by the amount of defects in the YMnO3 layer at low electric field. From the pseudo isothermal capacitance transient spectroscopy (ICTS), it was determined that the trap density was in an order of 1015 cm-3. Since the variation of the leakage current by annealing was observed only in the low electric field region, it is suggested that the retention properties of the Pt/YMnO3/Y2O3/Si capacitors was influenced by the amount of defects in the YMnO3 layer.

Stability of a positive column in the presence of an axial magnetic field

1982 ◽  
Vol 28 (1) ◽  
pp. 113-124 ◽  
Author(s):  
Mahinder S. Uberoi ◽  
Chuen-Yen Chow
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electron Density ◽  
Electric Fields ◽  
Positive Column ◽  
Axial Magnetic Field ◽  
Previous Analysis ◽  
Self Consistent ◽  
The Stability ◽  
Axisymmetric Perturbations

Self-consistent infinitesimal perturbations of electron density and electric field are used to analyse the stability of the plasma. The axisymmetric perturbations are stable for any magnetic and electric field strengths. The non-axisymmetric perturbations with azimuthal modes m ≥ 1 and less than a certain integer are unstable for certain ranges of magnetic and electric fields. The mode m = 2 can be more unstable than the mode m = 1. Previous analysis by other authors was confined to the case m = 1 and the perturbations were not self-consistent. Our results differ significantly from the earlier results.

Electric field effects on the stability of a thermogravitational flow in a vertical capacitor

2002 ◽  
Vol 56 (4) ◽  
pp. 493-513 ◽  
Author(s):  
Serguei R. Kosvintsev ◽  
Igor Yu. Makarikhin ◽  
Serguei A. Zhdanov ◽  
Manuel G. Velarde
Keyword(s):  
Electric Field ◽  
Electric Field Effects ◽  
Field Effects ◽  
The Stability
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