An Enhanced Thermal Resistance of Heat Pipe Working with Mono and Hybrid Nanofluids: A Comprehensive Review

Heat pipes are typically regarded as very efficient thermal management devices due to their passive functioning, excellent thermal conductivity and compact design. In recent years, using nanofluids as working fluids has emerged as a viable method for improving heat pipe thermal performance. This comprehensive review objectively evaluates the increase of thermal resistance in heat pipes using mono and hybrid nanofluids. The paper outlines the key heat transfer mechanisms driving nanofluid-based heat pipes, such as increased thermal conductivity, enhanced capillary action, surface wettability change and nanoparticle-induced micro-convection. The influence of mono nanofluids such as Al 2 O 3 , CuO, TiO 2 , SiO 2 and graphene-based nanofluids, and hybrid nanofluids on thermal resistance under various operating conditions like heat input, filling ratio, inclination angle, nanoparticle concentration and particle size is compared. Additionally, it is included that the effects of nanoparticle deposition, long-term stability, and possible problems including agglomeration and increased viscosity. Overall, the reviewed research shows that, because of the synergistic effects of various nanoparticles, hybrid nanofluids typically provide better thermal resistance reduction than mono nanofluids. In advanced thermal management applications including electronics cooling, renewable energy systems and industrial heat recovery, this analysis offers important insights into the choice of appropriate nanofluids and operating conditions for maximizing heat pipe performance.