Investigation on the heat transfer enhancement by nanofluid under electric field considering electrophorestic and thermophoretic effect

Nanofluid as heat transfer medium in microchannel heat sink is very common. It is a promising approach to employ electrohydrodynamic(EHD) effect to improve the heat transfer efficiency. A modified Buongiorno's model including EHD effect was established. And numerical simulations on flow and heat transfer for various electrode arrangements, various electric field intensity and frequencies were carried out. The numerical results show that, the main mechanisms to elevate the heat transfer in microchannel are chaotic convection induced by the electrophoretic effect and thermophoretic effect. The electrode-pair with top positive bottom negative arrangement and an alternating voltage are beneficial to the heat transfer enhancement. The heat transfer enhancement factor can be improved up to 10% and temperature on heated wall decreased up to 5 K for 1 V applied voltage. Besides, a moderate frequency of alternating electric field should be a good choice because about 20% increase in enhancement factor can be obtained. A promising approach can be provided for the design of microchannel heat sink based EHD effect.