A thermal management system using alumina (Al2O 3)/water as the nanofluid for green power sources was experimentally assessed in this paper. Basic thermal principles and formulas were utilized to evaluate the performance of an air-cooled heat exchanger. The Al 2O3/water nanofluid was produced at the concentrations of 0.5, 1.0, and 1.5 wt.%. The testing conditions of this experiments were above three concentrations, five coolant flow rates (0.8, 1.2, 1.6, 2.0, and 2.4 L/min.), and three heating powers (50, 100, and 150 W). Firstly, basic properties of nanoparticles were analyzed. Fundamental relationships of the Al2O3/water nanofluid with respect to temperatures and concentrations were measured such as: viscosity, density, and specific heat. Next, an innovative concept named efficiency factor (EF) was proposed to quantitatively evaluate the thermal system performance. The enhancement of thermal system performance compared with distilled water was then defined as an efficiency factor ratio (REF). The experimental results demonstrated that the efficiency factor ratios were optimal at low flow rate (0.8 L/min.) and low concentration (0.5%). Values of REF were all below 1.0 at high flow rates (1.2-2.4 L/min.). This research points out the direction of optimizing a thermal management system for green energy sources in the near future.
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