Hybrid GO-MXene nanofluids in 3D oscillating heat pipes for efficient urban PV cooling: Improved energy, exergy, and economic performance

The efficiency and longevity of photovoltaic (PV) panels are significantly impaired by excessive operational heat accumulation, which can reduce electrical efficiency by 0.4–0.5% per °C above 25°C and lead to 20–30% annual energy losses in urban environments. This study presents an innovative passive thermal management system integrating a three-dimensional oscillating heat pipe (3D-OHP) with hybrid graphene oxide (GO)–MXene (Ti 3 C 2 T x ) nanofluids at concentrations of 0.1 wt% and 0.2 wt%, leveraging GO’s high thermal conductivity (up to 3000 W/m.K) and MXene’s low viscosity and hydrophilicity for enhanced heat transfer and stability. Experiments conducted in Mashhad, Iran, under solar irradiances of 660–1090 W/m 2 , demonstrate that the 0.2 wt% GO-MXene nanofluid reduces thermal resistance by 41.1% (compared to 35.6% for MXene and 28.2% for GO alone), lowers panel temperature by over 24°C (versus 21.2°C for MXene, 15.4°C for GO, and 6.3°C for water), and boosts electrical power output by 14.9% (peaking at 48.3 W versus 42.1 W for the uncooled panel). This results in an additional 43 W/day of electricity generation, outperforming MXene (38.4 W/day), GO (27.3 W/day), and water (16.8 W/day) coolants. First-law electrical efficiency improves to 11.51% (from 10.02% uncooled), while peak exergy efficiency reaches 30.9% (versus 27.4% for MXene, 24.6% for GO, and 22.1% for water). Thermophysical enhancements include a 6% increase in thermal conductivity (to 0.651 W/m.K) with only a 31% viscosity rise (to 1.17 mPa.s), supported by zeta potentials exceeding ± 30 mV for stability. Economic evaluation yields a Levelized Cost of Energy (LCOE) of 0.083 USD/kWh and Levelized Cost of Storage (LCOS) of 0.273 USD/kWh for GO-MXene, balancing superior performance with affordability compared to water (LCOE: 0.071 USD/kWh; LCOS: 0.09 USD/kWh) and other nanofluids (GO LCOE: 0.086 USD/kWh; MXene LCOE: 0.080 USD/kWh). This scalable, surfactant-free system advances sustainable urban solar technologies by mitigating thermal stress, enhancing efficiency, and supporting net-zero energy goals with minimal environmental impact.