Energy-economy analysis of a novel spiral channeled conical turbulator inserted within the parabolic trough solar collector absorber tube

This study introduces a novel spiral channeled conical turbulator (SCCT) to enhance the hydrothermal and economic performance of a parabolic trough solar collector. Key design parameters, including spiral channel width (1-3 mm) and pitch (1-9 mm), are investigated, and the results are compared to those of a plain conical turbulator (PCT) and plain absorber tube. The inclined surfaces of the PCT and SCCT induce a strong radial flow, significantly improving heat transfer. Heat transfer and friction coefficients exhibit a direct correlation with spiral channel pitch but an inverse relationship with channel width. The PCT achieves the highest heat transfer enhancement, up to 550 % over a plain tube. However, the SCCT's aerodynamic geometry, enabled by its spiral channels, reduces pressure drop, yielding a higher and optimal performance evaluation criterion (PEC) compared to the PCT. The SCCT achieves a maximum PEC of 3.05 at a channel pitch of 5 mm and a width of 3 mm. This results in a 375 % improvement in heat transfer and a 280 % increase in the friction coefficient compared to plain absorber tubes. Economically, the PCT outperforms, with a levelized cost of energy (LCOE) of 0.405$/kWh and a payback time of 2.7 years. These results indicate that PCT is the optimal choice for heat transfer and economic performance, while SCCT is superior from a hydrothermal perspective.