Two-phase Convective Flow in Microchannel with Nanoporous Coating

Effect of nanoporous layer on convective heat transfer performance of microchannel has been investigated experimentally. Experimental studies were carried out in a microchannel of 672 μm hydraulic diameter using de-ionized (DI) water as the coolant. Nanoporous layer was developed on the heat transfer surface of the microchannel using electrophoretic deposition of Al2O3 nanoparticles. Both single-phase and two-phase convective heat transfer experiments were performed at different mass flux. Results from the microchannel with bare surface are used as the base line data. Critical heat flux (CHF) increases for the coated surface; up to 45% enhancement in CHF was observed, whereas heat transfer coefficient (HTC) was observed to reduce for the coated surface compared to the bare surface. This observation is in contradiction with several previous reports on pool boiling where significant enhancement in HTC is reported for the nanoporous coating. Possible reason of this contradiction is also explained in this report by performing molecular dynamics simulation.