Experimental Study on Energy Efficiency Enhancement in Thermal Systems Using Pulsating Heat Pipes with Al2O3 Nanofluid for Sustainable Development

The rapid development of electronic technologies has increased the demand for efficient and compact thermal management systems. Conventional cooling methods have already faced severe challenges imposed by the high heat generation rate and spatial constraints of modern devices. Pulsating heat pipes (PHPs) have been proposed as promising solutions owing to their passive working nature, compact structure, and excellent heat-transfer performance. However, the performance of the PHPs is strongly dependent on the properties of the working fluid and operation parameters. In this work, Al2O3/ethanol nanofluid is used to enhance the thermal efficiency of a copper PHP system. Experimental tests were conducted to examine the effects of filling ratio, inclination angle, and heat load on effective thermal conductivity and the overall heat transfer coefficient. The best thermal performance of Al2O3/ethanol nanofluid was achieved at a 50% filling ratio and 30° inclination, showing approximately a 15% increase in thermal conductivity compared with pure ethanol. Such an enhancement could be attributed to improved micro-convection and increased nanoparticle interactions in both the evaporator and condenser sections, which intensify heat transfer during phase transition. Moreover, the nanofluid showed superior thermal stability and repeatability over a 38-day testing period. This study demonstrates the capability of the Al2O3/ethanol nanofluid to overcome fluid-based limitations in PHPs and provides insights into optimizing system design. Future studies could scale up the experimental setup, test alternative combinations of nanofluids and base fluids, and integrate optimized PHP configurations into real platforms for electronic cooling.