Low Voltage Electrohydrodynamic Micropump for Cooling of Electronic Device

2011 ◽  
Author(s):  
Comlan Fandohan ◽  
A. G. Agwu Nnanna
Keyword(s):  
Electric Field ◽  
Flow Rate ◽  
High Voltage ◽  
Electric Potential ◽  
Low Voltage ◽  
Electronic Device ◽  
Dielectric Material ◽  
Maximum Velocity ◽  
High Heat ◽  
Dielectric Fluid

To dissipate the high heat generated in microprocessors and electronic components, electrohydrodynamic (EHD) micropumps are often used. An EHD system involves the interaction of a flow field and an applied electric field; specifically, an ion-drag EHD micropump uses the interaction of an electric field with electric charges, dipoles or particles embedded in a dielectric fluid in order to generate a net flow. These EHD micropumps, require high voltage to drive the fluid, and as a result have not gained wide application. This study presents a systematic analytical method of reducing the high voltage requirement. The approach is to select a dielectric material such that flow rate is maximized with low electric potential. It is known that the dielectric maximum velocity is a function of the dielectric potential, dielectric permittivity, and viscosity. In this paper, a flow rate is assumed to be sufficient. The electric potential is decreased by selecting the appropriate fluid. Fluid of high permittivity and low viscosity will enhance the potential factor there by, decreasing the potential.

Electrohydrodynamics (EHD)-Induced Flow in Different Channel Configurations

2016 ◽  
Author(s):  
C. C. Ngo ◽  
M. Sanghvi ◽  
J. Patel
Keyword(s):  
Kinetic Energy ◽  
High Voltage ◽  
Power Supply ◽  
Dielectric Material ◽  
Dielectric Fluid ◽  
Wire Electrode ◽  
High Voltage Power Supply ◽  
Cross Sectional ◽  
Pump Test ◽  
Induced Flow

Electrohydrodynamics (EHD) is the study of flow field induced by an electric field. The concept behind EHD is to transform electrical energy into kinetic energy. The induced kinetic energy can then be utilized for many applications such as chip-integrated cooling, drying in the food industry, reducing drag of aircrafts, spraying of dielectric material for printing, controlling particulate matter emissions as well as EHD thrusters and pumping. The focus of the present study is the use of EHD to induce flow in various channel configurations. The operation principle of an EHD pump is based on the interaction among electrically charged particles inside the dielectric fluid and their migration to the grounded plate. Corona discharge, produced by applied high voltage difference, is an electrical discharge brought on by the ionization of fluid surrounding the electrodes. For the current work, this applied voltage to the electrode is in the order of 10–30 kV generated by a DC power supply while the resulting electric current generated is very small in the order of μA to mA. EHD pumps are becoming more attractive for industrial application nowadays due to the lack of moving parts, simple and compact design with light structural weight as compared to conventional pumps or cooling fans. In addition, there is less operating noise and no vibration during the operation of EHD pumps. The main focus of our present work is to perform an experimental study to determine the induced flow rate at different applied voltages using various channel and wire electrode configurations. The basic experimental setup consists of an EHD pump test section, a high-voltage power supply, an air velocity transmitter and a data acquisition system. EHD pump test sections with different geometries of channel (e.g., circular, square and rectangular channels with the same cross-sectional area) along with different wire electrode configurations were constructed and tested. Measurements were taken from the corona threshold voltage to the sparkover voltage. The objective of the present study is to evaluate various designs of EHD pumps by comparing the EHD pumping efficiency.

scholarly journals Percolation effects in the capacitive properties of metal-oxide varistors in the range of high voltage

2014 ◽  
Vol 04 (02) ◽  
pp. 1450013 ◽  
Author(s):  
A. S. Tonkoshkur ◽  
I. V. Gomilko ◽  
A. Yu Lyashkov
Keyword(s):  
Electric Field ◽  
High Voltage ◽  
Percolation Theory ◽  
Low Voltage ◽  
Chemical Compositions ◽  
Infinite Cluster ◽  
Potential Barriers ◽  
Highly Nonlinear ◽  
Capacitive Properties ◽  
Manufacturing Techniques

C–V characteristics of ZnO -based ceramic structures used in manufacturing high-voltage and low-voltage varistors of different chemical compositions and manufacturing techniques have been investigated. A correlation between the intensity of electric field corresponding to transition of the C–V characteristics to the negative capacitances and average sizes of grains of a varistor structure has been established. Obtained data have been interpreted with the use of notions of the percolation theory of electric conductivity. The Shklovskii–De Gennes model has been used. It has been shown that on the highly nonlinear segment of C–V characteristics of a varistor structure, the size of an infinite cluster are limited to several intercrystallite potential barriers. This result is observed in all kinds of investigated varistor ceramics.

scholarly journals Numerical computation of the domain of operation of an electrospray of a very viscous liquid

2010 ◽  
Vol 648 ◽  
pp. 35-52 ◽  
Author(s):  
F. J. HIGUERA
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Electric Current ◽  
Viscous Liquid ◽  
Stationary Solution ◽  
Flow Rate ◽  
Electric Charge ◽  
Applied Field ◽  
Dielectric Fluid ◽  
Viscous Shear

A numerical study is carried out of the injection of a very viscous liquid of small electrical conductivity at a constant flow rate through an orifice in a metallic plate under the action of an electric field. The conditions under which the injected liquid can form an elongated meniscus with a thin jet emanating from its tip are investigated by computing the flow, the electric field and the transport of electric charge in the meniscus and a leading region of the jet. A stationary solution is found only for values of the flow rate above a certain minimum. At moderate values of the applied field, this minimum flow rate decreases when the applied field or the conductivity of the liquid increase. The electric shear stress acting on the surface of the liquid is not able to drive the liquid into the jet at flow rates smaller than the minimum while, for any flow rate higher than the minimum, the transfer of electric current to the surface may occur in a slender region of the jet where charge relaxation effects are small and the field induced by the electric charge of the jet is important. At high values of the applied field, the flow rate must be higher than another minimum, which increases with the applied field, in order for the viscous stress to balance the strong electric stress acting on the meniscus. The two conditions taken together determine lower and upper bounds for the applied field at a given flow rate, but the value of the applied field at which a stationary jet is first established when this parameter is gradually increased is higher than the lower bound, leading to hysteresis. When the liquid is electrosprayed in a surrounding dielectric fluid, the viscous shear stress that this fluid exerts on the surface of the jet eventually balances the electric shear stress and stops the continuous stretching of the jet. A fraction of the conduction current is left in the jet when the effect of the outer liquid comes into play in the region where this current is transferred to the surface, and no stationary solution is found above a maximum flow rate that decreases when the viscosity of the outer liquid increases or the applied field decreases. Order of magnitude estimates of the electric current and the conditions in the current transfer region are worked out.

Electric Field Orientation for Gene Delivery Using High-Voltage and Low-Voltage Pulses

2012 ◽  
Vol 245 (10) ◽  
pp. 661-666 ◽  
Author(s):  
J. Orio ◽  
M. Coustets ◽  
C. Mauroy ◽  
J. Teissie
Keyword(s):  
Gene Delivery ◽  
Electric Field ◽  
High Voltage ◽  
Low Voltage ◽  
Field Orientation ◽  
Voltage Pulses

Enhanced Flow Boiling of Ethanol in Open Microchannels With Tapered Manifolds in a Gravity-Driven Flow

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Philipp Buchling ◽  
Satish Kandlikar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Flow Rate ◽  
Electronics Cooling ◽  
High Heat ◽  
Dielectric Fluid ◽  
High Heat Flux ◽  
Gravity Driven ◽  
Gravity Driven Flow

There is a clear need for cooling high heat flux generating electronic devices using a dielectric fluid without using a pump. This paper explores the feasibility of employing ethanol as a dielectric fluid in a horizontal, open microchannel heat sink configuration with a tapered gap manifold to yield very low pressure head requirements. The paper presents experimental results for such a system utilizing ethanol as a working fluid under gravity-driven flow. A heat flux of 217 W/cm2 was dissipated with a pressure drop of only 9 kPa. The paper further presents parametric trends regarding flow rate and pressure drop characteristics that provide basic insight into designing high heat flux systems under a given gravity head requirement. Based on the results, interrelationships and design guidelines are developed for the taper, ethanol flow rate and imposed heat flux on heat transfer coefficient and gravity head requirement for electronics cooling. Reducing flow instability, reducing pressure drop, and enhancing heat transfer performance for a dielectric fluid will enable the development of pumpless cooling solutions in a variety of electronics cooling applications.

Low-Voltage Variable Gain Current Amplifier for High-Voltage Signal Processing

2009 ◽  
Vol 129 (8) ◽  
pp. 1511-1517
Author(s):  
Nicodimus Retdian ◽  
Jieting Zhang ◽  
Takahide Sato ◽  
Shigetaka Takagi
Keyword(s):  
Signal Processing ◽  
High Voltage ◽  
Low Voltage ◽  
Current Amplifier ◽  
Variable Gain ◽  
Voltage Signal
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