Performance of parabolic trough collector having rotating receiver: Effect of elliptical insert and hybrid nanofluid

This study considers three parabolic trough collector models with rotating receiver tubes and elliptical inserts of two orientations and one with a smooth receiver tube. Hybrid nanofluid is considered as a working medium by mixing copper oxide and aluminum oxide nanoparticles in water. Computational experiments are performed with a 1% concentration in terms of vol. of hybrid nanofluids by considering a mixture of copper oxide and aluminum oxide nanoparticles in water (aluminum oxide 25%- copper oxide 75%, aluminum oxide 50%- copper oxide 50%, and aluminum oxide 75%- copper oxide 25%). Rate of flow for the simulation is considered to vary from 0.016 to 0.033 kg/s. Again, this study focuses on utilizing rotating receiver tubes with a varying velocity of 0-15 rad/s to overcome the stratification of high temperature at the surface. Results show that enhanced values for the temperature at outlet, heat transfer coefficient, and thermal efficiency are noted for a model with elliptical inserts of major diameter 28 mm (longitudinal orientation) at 15 rad/s receivers speed for nanofluid-1 (aluminum oxide 75%- copper oxide 25%) at 0.033 kg/s. The highest increment in heat transfer coefficient, as well as thermal efficiency for the model with a 28 mm major diameter elliptical insert (longitudinal orientation), is 44.21% and 29.21% respectively. Highlights Use of a spinning receiver reduces the problem of uneven temperature distribution at receiver surface. Maximum 375 K outlet temperature is noted at 15 rad/s for elliptical insert of diameter 28 mm (longitudinal orientation) at 0.016 kg/s. The elliptical insert received the maximum thermal efficiency rating of 82.03%. An elliptical insert in receiver increases pump work by 18.13% than smooth receiver.