INVESTIGATION OF THERMAL PERFORMANCE ENHANCEMENT IN AUTOMOTIVE RADIATORS USING AL2O3–WATER NANOFLUID

Abstract

This study experimentally evaluates the thermal performance of an automotive radiator when conventional water coolant is replaced with aluminum oxide (Al2O3–water nanofluids. The objective was to quantify the effects of nanoparticle concentration (0.001–0.01 vol%) and coolant flow rate (7–10 L/min) on key thermal and hydraulic parameters, including heat transfer rate, convective heat transfer coefficient, Reynolds number, and pressure drop. Nanofluids were synthesized using the two-step method with mechanical stirring to ensure suspension stability and tested in a closed-loop radiator system under controlled laboratory conditions with a constant inlet coolant temperature of 50 °C. Results revealed a consistent enhancement in heat transfer performance with increasing nanoparticle concentration and flow rate. At 0.007 vol% concentration and 10 L/min, the nanofluid achieved a heat transfer coefficient of approximately 1437 W/m²·K, exceeding water by more than 25%. Although nanofluid usage resulted in a moderate pressure drop due to higher viscosity, the trade-off was favorable as overall thermal efficiency improved significantly. These findings suggest that dilute Al2O3 nanofluids are a promising alternative coolant for next-generation automotive thermal management systems. Keywords Automotive radiator, heat exchanger, nanofluid, Al2O3–convective heat transfer, pressure drop