Experimental Study on Performance Analysis of Evacuated Tube Solar Collector with TiO₂ Nanofluid and Adjustable Parabolic Trough Reflector

Abstract

This paper presents enhancing the thermal performance of evacuated tube solar collectors (ETSCs) using titanium dioxide (TiO₂) nanofluids combined with reflector and sun-tracking mechanisms. ETSCs are a promising technology in solar thermal energy; however, their efficiency is often limited by the low thermal conductivity of conventional working fluids like water. To address this, TiO₂ nanoparticles were dispersed in water at concentrations of 0.05%, 0.15%, and 0.3% to evaluate their impact on ETSC performance in configurations with reflectors, angle tracking, and combined reflector and sun-tracking systems. Experimental results confirm the superior performance of TiO₂ nanofluids in outlet temperature, efficiency, and heat gain. The storage tank temperature increased from 56.7 °C with plain water to 73.4 °C at 0.05% and 78.2 °C at 0.3%. System efficiency improved from 21.4% to 23%. The highest efficiency was obtained with 0.3% nanofluid combined with reflector and sun-tracking. These results demonstrate a practical pathway to maximize solar energy capture.