Liquid dielectric

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

Effect of Drop Deformation on Heat Transfer to a Drop Suspended in an Electrical Field

Abstract: Heat transfer to a drop of a dielectric fluid suspended in another dielectric fluid in the presence of an electric field is investigated. We have analyzed the effect of drop deformation on the heat transport to the drop. The deformed drop shape is assumed to be a spheroid and is prescribed in terms of the ratio of drop major and minor diameter, Results are obtained for both prolate and oblate shapes with a range of diameter ratio b/a from 2.0 to 0.5. The internal problem where the bulk of the resistance to the heat transport is in the drop. as well as the external problem where the bulk of the resistance is in the continuous phase, are considered. The electrical field and the induced stresses are obtained analytically. The resulting flow field and the temperature distribution are determined numerically. Results indicate that the drop shape significantly affects the flow field and the heat transport to the drop. For the external problem, the steady-state Nusselt number increases with Peclet number for all drop deformations. For a fixed Peclet number, the Nusselt number increases with decreasing b/a. A simple correlation is proposed to evaluate the effect of drop deformation on the steady-state Nusselt number

Analysis of a static undulation on the surface of a thin dielectric liquid layer formed by dielectrophoresis forces

Abstract: A layer of insulating liquid of dielectric constant ɛOil and average thickness h− coats a flat surface at y = 0 at which a one-dimensional sinusoidal potential V(x,0)=VOcos(πx/p) is applied. Dielectrophoresis forces create a static undulation (or “wrinkle”) distortion h(x) of period p at the liquid/air interface. Analytical expressions have been derived for the electrostatic energy and the interfacial energy associated with the surface undulation when h(x)=h−-(1/2)Acos(2πx/p) yielding a scaling relationship for A as a function of h−, p, VO, ɛOil and the surface tension. The analysis is valid as A/p → 0, and in this limit convergence with numerical simulation of the system is shown.

An Overview of Electrical Processes Leading to Dielectric Breakdown of Liquids

Abstract: The electrical breakdown of a dielectric liquid under high stress requires that a number of interdependent, parallel as well as sequential electronic processes occur in the liquid and at the electrodes. In addition, there is the intervention of electrically-induced but non-electronic processes such as heating and the generation of a microscopic gas phase and changes in the chemical structure of the liquid molecules. The precise nature and sequence of these processes is extraordinarily difficult to establish largely because breakdown is an instability in which a liquid-gas, insulator-conductor transition occurs very rapidly. For example, breakdown of a n-hexane sample in a 2 mm gap between electrodes establishing a field of 106V cm−1 can be complete in less than 500 ns (Wong and Forster, 1977).