Study on Heat Transfer Performance Change According to Long-term Operation Using Carbon Nanotube and Graphene Nanofluid

Abstract

Critical heat flux refers to the sudden decrease in boiling heat transfer coefficient between a heated surface and fluid, which occurs when the phase of the fluid near the heated surface changes from liquid to vapor. For this reason, critical heat flux is an important factor for determining the maximum limit and safety of a boiling heat transfer. Recently, it is reported that the nanofluid is used as a working fluid for the critical heat flux enhancement. However, it could be occurred nano-flouling phenomena on the heat transfer surface due to nanoparticles deposition, when the nanofluid is applied in a heat transfer system. In this study, we experimentally carried out the effects of the nano-fouling phenomena in oxidized multi-wall carbon nanotube and oxidized graphene nanofluid systems. It was found that the boiling heat flux decreased by hourly 0.04 and 0.03 kW/m2, also the boiling heat transfer coefficient decreased by hourly 11.56 and 10.72 W/m2·K, respectively, in the thermal fluid system using oxidized multi-wall carbon nanotube or oxidized graphene nanofluid.