Liquid dielectric

About: Liquid dielectric is a research topic. Over the lifetime, 3702 publications have been published within this topic receiving 45150 citations.

Circular electric mode microwave window

Abstract: For conducting very high microwave power at very high frequencies, circular waveguide transmitting a circular-electric-field mode is used. The vacuum-tight window of an electron tube is often the element with lowest power-handling capability. The inventive window has two dielectric plates with a space between them. There is a gap in the waveguide inner wall through which a dielectric fluid is circulated between the plates to cool them. The gap leads to a region containing wave-absorbing material such as water to absorb modes other than the circular-electric-field mode.

Improvement for Pressure Performance of Micro-EHD Pump with an Arrangement of Thin Cylindrical Electrodes

Abstract: A micro-electrohydrodynamic (EHD) pump is experimentally tested. In order to improve the static pressure performance, the EHD pump examined in this paper was fabricated with a series of thin stainless steel wires (the outer diameter is 0.3mm). The overall dimensions of the EHD pump were 30× 30×4.9mm and of the pumping channel were 24× 24× 0.9mm. An electrode pair consisted of one emitter electrode and two collector ones. The five sets of pumps were prepared for experiment. Those pumps were consisting of the number of electrode pairs from 1 to 5. The static pressure is measured with dibutyl-sebacate as a working fluid which has a dielectric constant, e / e 0=4.8 and a low electric conductivity, σ=4.7× 10-10S/m. The experimental results are compared with the theoretical results. In the theoretical model, the pressure is generated by Coulomb force which forces to move the unipolar ions in the high electric field. The experimental results indicate that the pressure increase as the number of electrode pairs increases and is generated up to 350Pa at an applied voltage of 1kV with 5 electrode pairs. Also, the experimental results show a good agreement with the theoretical ones. It is found that the theoretical model is useful for design of the high performance EHD pumps.

Behavior of a single bubble in a nonuniform d.c. electric field

Abstract: The effects of a nonuniform electric field on the formation, detachment, and breakup of a single inert bubble surrounded by a dielectric liquid were studied experimentally and numerically. In experiments, air bubbles were injected into kerosene at a constant flow rate through an orifice at the bottom wall of the test cell. The liquid was subjected to a nonuniform electric field, applied between the horizontal and vertical electrodes. During the experiments, the behavior of bubbles was recorded continuously, and the position, shape, and volume departure of the bubbles were digitally extracted from the sequential frames with the aid of graphical software. The experimental results show that in the presence of the nonuniform electric field, bubbles take a prolate shape and skew to the opposite direction of the ground electrode. With an increase in the electric potential, the bubble growth time and departure volume will decrease continuously. Bubble breakup is also observed at high enough voltages. As a furthe...

Droplet creation using liquid dielectrophoresis

Abstract: Dielectrophoresis (DEP) is defined as polarizable particles moving into regions of higher electric field intensity. In liquid DEP (LDEP), a dielectric liquid tends to flow toward regions of high electric field intensity under a non-uniform electric field. This work presents a theoretical model of LDEP based on parallel electrodes. The LDEP force is derived using the lump parameter electromechanical method. The relationship between the minimum actuation voltage and the electrode width is investigated experimentally and theoretically. We also propose a method for creating a 20 nl droplet of deionized water using LDEP. The creation of a water droplet containing 15 μm polystyrene beads is placed at the desired location from a continuous flow driven by LDEP using the developed method.

Overpressure protection for vaporization cooled electrical apparatus

Abstract: Overpressure protection for a vaporization cooled electrical inductive apparatus. A pressure responsive device is actuated by a predetermined pressure within a sealed housing and de-energizes a pump, thereby stopping the flow of dielectric fluid to the heat producing members which prevents further pressure increases within a tank due to continued vaporization of the dielectric fluid. In one embodiment, a discharge valve is actuated by the pressure responsive device to drain the dielectric fluid from the windings to prevent further pressure increases caused by continued vaporization of the dielectric fluid. A fusible link is provided to disconnect the windings of the electrical inductive apparatus from a source of electrical potential subsequent to the de-energization of the pump. In another embodiment, the pressure responsive device actuates the circuit breaker which disconnects the windings of the electrical inductive apparatus from the source of electrical potential.