Comparative analysis of thermal performance in heat pipe heat exchangers employing two distinct convective heat transfer media

Heat pipe heat exchangers (HPHEs) offer an efficient solution for industrial waste heat recovery by utilizing latent heat transfer. This study compared a traditional water-based HPHE and one augmented with 1% silver nanoparticles by volume. The HPHEs with distinct 500-mm evaporator and condenser sections were assessed on parameters like temperature distribution, heat transfer rates, thermal resistance, and effectiveness under varying thermal loads (70-90 W) and hot/cold fluid mass flow rates (0.2-0.6 kg min-1 and 0.1-0.3 kg min-1). The nanofluid HPHE demonstrated superior performance, with a 12.21 degrees C peak evaporator temperature difference and 39.25% maximum effectiveness at optimal conditions, exceeding the DI water HPHE by over 10%. The higher heat fluxes proportionally improved heat transfer parameters. Moderate mass flow rates around 0.2 kg min-1 (hot fluid) and 0.1 kg min-1 (cold fluid) optimized performance. The unconventional adiabatic-less design improved heat transfer compared to traditional heat pipes. The nanofluid HPHE's exceptional heat recovery capacity proves its viability for harnessing low-grade industrial waste heat, leading to significant energy savings. The study provides critical insights into thermal performance enhancements through synergistic HPHE design modifications and nanoparticle augmentation of the working fluid.