Development and assessment of a closed-loop pulsating heat pipe employing TiO2/SiO2 nanofluids utilizing metallic nanoparticles

Abstract

This study aims to investigate the potential improvements in Closed-Loop Pulsating Heat Pipes (CLPHPs) by utilizing hybrid nanofluids (HNFs) composed of metallic as well oxide nanoparticles. CLPHPs function through dual phase flow to transfer heat between evaporators and condensers, with their performance being heavily dependent on the thermal conductivity of the working fluid. This research examines the performance of CLPHPs using four different working fluids: titanium dioxide (TiO) and silicon dioxide (SiO) HNF, TiO₂ mono nano solvent, SiO₂ mono nano solution, and distilled water, across a range of operating conditions. A Closed-Loop Pulsating Heat Pipes was constructed and tested using four different working fluids. The study analyzed several operational parameters, including nanoparticle weight concentrations ranging from 0.2 % to 0.3 %, filling ratios between 60 % and 70 %, and heat inputs from 25 to 75 watts. The findings revealed that the TiO₂/SiO₂ HNF reduced thermal resistance by 28 to 52 % compared to distilled water and by 15 to 40 % compared to mono nanofluids under identical operating conditions (filling proportion, nanoparticle concentration, as well heat input). These results indicate that the hybrid nanofluid significantly enhances heat transfer performance. The CLPHP filled with TiO₂/SiO₂ HNF demonstrated optimal performance at a 70 % filling fraction and a nanoparticle weighted concentration of 0.3 %. Nevertheless, perpetuating solidity of TiO₂/SiO₂ HNF remains a challenge, largely attributable to hydrophobic essence of SiO₂ nano components, which can affect their dispersion and long-term stability.