Performance Evaluation of an Absorber Tube of a Parabolic Trough Collector Fitted with Helical Screw Tape Inserts Using CuO/Industrial-Oil Nanofluid: A Computational Study

Abstract

Improvement of the performance of renewable energy harvesters is a crucial and complicated task. Among currently utilized renewable energy harvesters, parabolic solar collectors are some of the most promising and widely used apparatuses. However, researchers are still facing some issues regarding the optimization of PTC performance, including the enhancement of heat flux absorption by the absorber tubes. Among the proposed methods to overcome this drawback, the implementation of helical screw tape (HST) and nanofluids has proven to be most effective. In the present study, the CFD simulation of an absorber tube with HST is conducted. CuO/oil nanofluid with a nanoparticle volume fraction of 1 to 3% was chosen as the working fluid. The simulation is based on the realistic operational condition of a PTC absorber tube with corresponding nonuniform solar heat flux based on the local concentration ratio. The effects of the mass flow rate (Re), HST width and nanofluid volume fraction on pumping power and heat transfer are studied. Moreover, to combine the effect of both parameters, the performance evaluation criterion (PEC), a dimensionless variable, is calculated for all of the studied cases. Enhancement of the PEC parameter by the implementation of nanofluid and HST in comparison to base fluid passing through a plain tube is also determined and reported. According to the obtained results, with the implementation of the CuO/oil nanofluid, the PEC can be enhanced by 57.3–70.8, 68.7~86.4, and 83.4~105.9% for volume fractions of 1, 2, and 3%, respectively.