Performance Evaluation of Mono and Hybrid Nanofluids for Enhanced Heat Transfer in Automotive Radiator Systems

Efficient thermal management is critical for automotive internal combustion engines, where conventional Ethylene Glycol water coolants often face limitations in heat transfer performance. This research work experimentally investigates the thermohydraulic behavior of mono TiO2, ZnO, and MWCNT nanofluids, and hybrid TiO2 + ZnO + MWCNT nanofluids. These nanofluids were prepared by mixing 0.1% volume fraction of nanoparticles into a water- (EG) base fluid. During testing, the nanofluid flow through the radiator was maintained within the range of 4-12 LPM. Results showed that the convective heat transfer coefficient was significantly enhanced by all nanofluids, relative to the base fluid. The MWCNT nanofluid achieved the highest heat transfer coefficient of 2086 W/m²K, representing a substantial improvement. Although increased pressure drops were observed for nanofluids, performance index analysis indicated that the MWCNT nanofluid offered the most favorable balance between heat transfer enhancement and hydraulic penalty, peaking at a performance index of 1.22. The hybrid TiO2 + ZnO + MWCNT nanofluid also demonstrated a strong performance index of 1.16, benefiting from the synergistic effects of multiple nanoparticles. These findings confirm the potential of MWCNT and hybrid nanofluids to significantly improve automotive radiator cooling performance. Major Findings: This research demonstrates the superior thermal-hydraulic performance of MWCNT and ternary hybrid nanofluids in automotive radiators, highlighting their capability to substantially improve heat transfer while maintaining acceptable pressure drop. This advances the application of nanotechnology in vehicle thermal management.