Electro-osmotic flow and heat transfer of a non-Newtonian nanofluid under the influence of peristalsis

This paper reports theoretical and numerical analysis of fluid flow and heat transfer in a cascade electro-osmotic flow (EOF) micropump for chip cooling. A simple analytical model is developed to determine the temperature distribution in a two-dimensional (2D) single channel EOF micropump with forced convection due to a voltage difference between both ends. Numerical simulations are performed to determine the temperature distribution in the domain which is compared with that predicted by the model. A novel cascade EOF micropump with multiple microchannels in series and parallel and with an array of interdigitated electrodes along the flow direction is proposed. The simulations predict the maximum flow rate and pressure capability of one single stage of the micropump and the analytical model employs equivalent circuit theory to predict the total flow rate and back pressure. Each stage of the proposed micropump comprises sump and pump regions having opposing electric field directions. The various design parameters of the micropump includes the height of the pump and sump (h), number of stages (n), channel width (w), thickness of the channel wall or fin (r), and width ratio of the pump and sump (s:p) regions. Numerical simulations are performed to predict the effects of these design parameters on the pump performance which is compared with that predicted by the analytical model. The micropump is used for cooling cooling of an Intel® CoreTM i5 chip which produces a maximum heat of 95 W over an area of 3.75 × 3.75 cm. Based on the parametric studies a design for the cascade EOF micropump is proposed which provides a maximum flow rate of 14.16 ml/min and a maximum back pressure of 572.5 Pa to maintain a maximum chip temperature of 310.63 K.

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Exact Solution of Electroviscous Flow and Heat Transfer in a Semi-annular Microcapillary

Journal of Heat Transfer ◽

10.1115/1.4031084 ◽

2015 ◽

Vol 138 (1) ◽

Cited By ~ 7

Author(s):

Ali Jabari Moghadam

Keyword(s):

Heat Transfer ◽

Temperature Fields ◽

Fluid Temperature ◽

Surface Cooling ◽

Bulk Fluid ◽

Flow And Heat Transfer ◽

Scale Ratio ◽

Potential Sign ◽

Electro Osmotic Flow ◽

Maximum Minimum

The electro-osmotic flow (EOF) and associated heat transfer are investigated in a semi-annular microcapillary. The potential, velocity, and temperature fields are solved by analytic approaches including the eigenfunction expansion and the Green’s function methods. By selecting the potential sign of each surface of the channel, the bulk fluid may flow in two opposite directions. Effects of the key parameters governing the problem are examined. The mass flow rate increases when the hydraulic diameter is increased or the electrokinetic radius is decreased. The results reveal that surface cooling and/or surface heating (of the inner or outer walls) strongly affects the fluid temperature distributions as well as the position of the maximum/minimum temperature region inside the domain; the latter indicates temperature gradients in fluid. Also, higher thermal scale ratio leads to broaden the temperature distribution. Depending on the value of the geometric radius ratio (and for all values of the thermal scale ratio), the fully developed Nusselt number approaches a specific value as the electrokinetic radius tends to infinity.

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