Study on the heat transfer enhancement of hydro-turbine thrust bearing with nano-oil

The thrust bearing in a hydro-turbine unit carries the entire axial load, and its cooling performance is crucial for operational safety due to the substantial frictional heat generated. This study numerically investigates the enhancement of heat dissipation in a large-scale 100-MW thrust bearing using lubricating oil doped with copper oxide nanoparticles. Nano-oils with mass concentrations ranging from 0.1 to 0.5 wt% were prepared and experimentally characterized. Their thermal performance was compared with that of pure oil under varying inlet temperatures (297–303 K) and mass flow rates (50–200 kg/s) by means of a validated CFD model. Results demonstrate that the 0.4 wt% nano-oil yields the optimal performance under baseline conditions (300 K, 132 kg/s). It reduces the pad temperature by 0.31 K and raises the outlet oil temperature by 0.14 K, indicating improved heat extraction. The corresponding Performance Evaluation Criterion (PEC) reaches 1.070, reflecting a 7 % overall thermo-hydraulic improvement. Notably, the 0.4 wt% nano-oil achieves comparable cooling without requiring lower inlet temperatures or higher flow rates, thereby lowering the energy consumption of the cooling system. This work provides a quantitative basis for the energy-efficient implementation of nano-oils in hydro-turbine thrust bearing system.