Performance Evaluation of Ferric-based Nanofluids in Evacuated Tube Solar Thermal Systems

This research explores the thermal performance improvement of a U-tube evacuated tube solar collector (ETSC) using a Ferric/water nanofluid as the working medium. The nanofluid was synthesized using a two-step method with different volume concentrations ranging from ۰.۲۵% to ۲.۰% Fe+۳ nanoparticles. Stability was enhanced through the use of surfactants, and confirmed using zeta potential testing. Thermophysical properties such as thermal conductivity, specific heat, and viscosity were examined across a temperature range of ۲۵°C to ۵۰°C. Results show that increasing nanoparticle concentration improved thermal conductivity by up to ۱۳.۰۴%, while reducing specific heat capacity. The collector’s performance was tested under various mass flow rates and concentrations. The highest temperature difference recorded was ۹.۹°C at ۱.۰% concentration and ۰.۰۰۸۳ kg/s flow rate. Maximum energy efficiency reached ۷۲.۵۶% at ۱.۲۵% concentration and ۰.۰۰۴۱۶ kg/s. Entropy generation was lowest at ۲۶.۱۹ W/K for ۱.۵% volume concentration, indicating reduced irreversibility. An uncertainty analysis confirmed that measurement errors decreased at higher flow rates, supporting the reliability of the findings. The study concludes that Ferric/water nanofluid enhances the heat transfer and overall efficiency of ETSC systems.

کلیدواژه ها:

Energy ، Evacuated tube solar collector ، Nanofluids ، Solar energy ، Thermal exergy