Investigation of flow boiling performance and the resulting surface deposition of graphene oxide nanofluid in microchannels

Graphene oxide (GO)-water nanofluid was prepared and applied in flow boiling experiment in microchannels. Boiling heat transfer experiments were performed at various mass flow rates, with the nanofluid concentration ranging from 0 to 0.05 wt%. The heat transfer performance was found to be deteriorated for graphene oxide nanofluids. Nanofluid with higher concentration had lower heat transfer coefficient. Surface deposition was found after experiment for different concentration and flow rate. The nanoparticle interaction mechanism and absorption between nanoparticles was proposed to clarify the deposition process: higher temperature, concentration and fluid flow would accelerate the interaction and deposition process. The film-like shape of graphene oxide contributed to the formation of non-porous structure of deposition that blocked nucleation sites. An energy dispersive spectrometer (EDS) analysis of the deposit was carried out and the graphene oxide was found to be reduced chemically during boiling process and thus causing the deposition. Finally, the deposition morphology of graphene oxide was compared with those observed by other researchers and similar deposition characteristics were confirmed. It further indicates that the deposition which was reported to increase critical heat flux could have a negative effect on heat transfer coefficient.