Partial discharge (PD) has been known as the main consequence of hydrogen (H2) formation in transformer oils, the cause of serious damages to the equipment. Herein, experimental and theoretical analyses were merged to find the best nanoadsorbent among zinc oxide (ZnO), titanium dioxide (TiO2) and carbon nanotubes (CNTs) model nanoparticles for H2 adsorption from transformer oil. Hydrogen content and PD were decreased by nanoparticle incorporation, but thermal conductivity was increased. Experimental results showed no obvious effect on the total acid number and the moisture content of the oil resulting from nanoparticles. TiO2 adsorbed the highest amount of H2 (85%) and remarkably increased the breakdown voltage by 14% and the highest reduction in the PD, but ZnO and CNTs limitedly assisted in H2 adsorption. Theoretical analyses (density functional theory), in agreement with practical experimental, predicted that the H2 adsorption energy of TiO2 (3.57 eV) was higher than those of ZnO (2.75 eV) and CNT (0.0037 eV).
