Multi-criteria evaluation of a nanofluid-based linear Fresnel solar collector

Solar linear Fresnel reflector (LFR) is a promising concentrating technology, which presents important advantages such as the low investment cost, the reduced wind loads and the relatively low land utilization factor. The objective of this work is to investigate an innovative way for enhancing the thermal performance of LFR, especially at high temperatures. The utilization of nanofluid as heat transfer fluid is the investigated thermal enhancement method and more specifically the use of CuO nanoparticle dispersed on Syltherm 800 (6% volumetric concentration). The examined collector has total net aperture equal to 154 m2 and concentration ratio of 58.36. The primary reflectors are curved mirrors, the secondary reflectors have compound parabolic shape and the receiver is an evacuated tube. The operation with nanofluid is compared to the operation with pure thermal oil for various inlet temperatures from 350 K up to 650 K and flow rate equal to 200 L/min. According to the final results, the maximum thermal efficiency enhancement with the nanofluid is close to 0.8%, while the pumping work demand is increased up to 50% with the nanofluid. Various criteria like the exergy efficiency, overall efficiency and entropy generation are applied in order to evaluate the nanofluid utilization properly. Finally, the operation with nanofluid is found to be beneficial, especially in high-temperature levels. The analysis is conducted with SolidWorks Flow Simulation with a validated model.