Effect of strong electric field on heat transfer enhancement in a mini channel containing Al2O3/oil nanofluid

The present work aims to investigate the heat transfer and pressure drop of Alumina/oil nanofluid flow in a miniaturized square channel in the presence of strong DC electric fields. The high voltage was applied using a thin wire on top of the channel. The bottom of the channel was used as both a ground electrode and a heated surface. Results showed that increasing particle concentration caused heat transfer augmentation for all Reynolds numbers. Applying a strong electric potential of 15.51 kV resulted in considerable heat transfer enhancement of 52% for the nanofluid with 0.3% volume fraction, at the Reynolds number of 7. This considerable enhancement can be attributed to the formation of the ion injection-based secondary flows and motion of the particles. The generated secondary flow disrupts the boundary layer and increases the heat absorption from the heated surface. The experiments were confined to the volume fraction of 0.3% since the rapid agglomeration of particles occurred on electrode and walls at the volume fraction of 0.5%.