Abstract
We propose a bi-directional electrohydrodynamic pump developed for transporting dielectric liquid, where the electrodes are symmetrically configured but the applied voltage is non-symmetric. The underlying principle for liquid transport comes from the so-called Onsager effect, which states that the ion concentration is increased as the electric field is increased. Multi-physics software is used to perform numerical simulation for the fluid flow, the electric potential, and the transport of ion concentrations for two kinds of electrode patterns. A flow-visualization experiment is also conducted to verify the physical models and numerical methods employed. It is found that significant reduction of the ion recombination constant is required to get matching of the experimental and simulation results. We demonstrate through a parametric study that there is an optimum distance between two large grounded electrodes for producing a maximum pumping velocity at the diameter of two small electrodes fixed at 0.3 mm. The effect of the size of large grounded electrodes on the pumping performance is also studied in terms of streamlines, electric field, and charge distribution. A general account is also given of the basic ideas of electrode arrangement for the enhancement of pumping.
Highlights
How to pump fluids in the transport system of miniand micro-scales has become a very important issue
We see the increase in the mean velocity upon the increase in D, which is consistent with the results presented in section ‘‘Parametric study with electrode pattern A.’’ We can see that both the experimental and numerical data are close to the parabolic profile indicating that the velocity is almost fully developed at the selected channel section
The pumping velocity is obtained with 2D numerical simulations at various sets of geometrical parameters
Summary
How to pump fluids in the transport system of miniand micro-scales has become a very important issue. Initial studies on EHD pumps driven by the SeyedYagoobi group (see the review article[18] and references therein) were motivated by the need to enhance heat transfer in pool boiling and heat pipes, where working fluids are characterized by relatively low permittivity They demonstrated the feasibility of applying the EHD pump to heat exchangers under a zero- or micro-gravity environment.[19] Their numerical model for the ion transport includes ion dissociation and recombination, but the Onsager effect has not been considered and the fluid flow is assumed to be driven only by the counter-charge in the dissociation layer (DSL). We in this study propose a bi-directional EHD pump composed of circular-cylindrical electrodes in a circulating channel of annular shape and explore the effect of key geometrical parameters, that is, electrode arrangement and size, on the pumping velocity. Under this section, we discuss the way in which bL is determined in this study in relation to the convergence problem of numerical simulation
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