Thermal performance comparison of oscillating heat pipes with SiO2/water and Al2O3/water nanofluids

Thermal performances of two same oscillating heat pipes (OHPs) charged with SiO2/water and Al2O3/water nanofluids, respectively, were investigated experimentally. Both the average evaporator wall temperature and the overall thermal resistance of the OHPs at different nanoparticle mass concentrations (0-0.6 wt% for silica nanofluids and 0-1.2 wt% for alumina nanofluids) and at the volume filling ratio of 50% were tested and compared. Experimental results showed that different nanofluids caused different thermal performances of OHPs. Within the experimental range, using the alumina nanofluid instead of pure water enhanced the heat transfer of the OHP (reductions in the evaporator wall temperature and thermal resistance of the OHP of about 5.6 degrees C (or 8.7%) and 0.057 degrees C/W (or 25.7%), respectively, were obtained), while using the silica nanofluid instead of pure water deteriorated the thermal performance of the OHPs (with the evaporator wall temperature and the thermal resistance of the OHP being increased by 3.5 degrees C (or 5.5%) and 0.075 degrees C/W (or 23.7%), respectively). A preliminary analysis was conducted for the different effects induced by the addition of different nanoparticles to pure water, and it was found that the change of surface condition at the evaporator and condenser due to different nanoparticle deposition behaviors was the main reason for the thermal performance improvement or deterioration of the OHPs charged with different nanofluids. (C) 2011 Elsevier Masson SAS. All rights reserved.