Sensitivity analysis of the thermal performance of a parabolic trough concentrator using Al₂O₃ and SiO₂/Vegetable oil as heat transfer fluid

This paper aims to highlight the use of different heat transfer fluid (HTF) configurations based on vegetable oils in Parabolic Trough Solar Concentrator (PTSC). Rapeseed and jatropha oils as innovative heat transfer materials combined with SiO₂ and Al₂O₃ to obtain six (6) HTF configurations are used in a 1-dimensional PTSC model. The thermophysical properties of the nanofluids are determined from correlations derived from the literature, using Gauss-Seidel method from a numerical code developed in Matlab software. Model validation is obtained. Thermal sensitivity analysis shows that the use of rapeseed increases the thermal efficiency of the PTSC by around 4.21 % compared with jatropha. The use of nanofluids reduces thermal losses within the system due to thermal gradients. For a fixed irradiance and each 1 %-4 % increase in volume fraction, thermal efficiency increases by around 1.96 % when Al₂O₃/rapeseed is used and by 0.47 % when SiO₂/rapeseed is used compared with rapeseed. Similarly, thermal efficiency increases by around 1.98 % when Al₂O₃/jatropha is used and decreases by around 0.20 % when SiO₂/jatropha is used compared with jatropha. However, the positive effects of nanoparticles on thermal conductivity alone are not always sufficient to improve thermal efficiency, and thermal effects on heat capacity should also be considered.