Hydrodynamic computational evaluation in solar tubular photobioreactors bends with different cross sections

In this article, the hydrodynamic behavior of a single-phase flow in various solar collectors with different cross sections (circular, octagonal, hexagonal and square), with same hydraulic diameter and longitudinal profile was analyzed. Secondary flow, pressure drop and shear stress were evaluated, because the photosynthetic efficiency and microalgae endurance depend on these properties. These parameters were reviewed at six different culture inlet rates in the collector (from 0,25 m/s to 0,5 m/s), emphasizing in the bends regions. A higher speed and agitation was pre-sent in the square solar collector, contrary to what happened to the circular one. Despite this, the circular solar collector remains the best option for the industrial implementation phase. However, the shear stress generated in the culture -as it passes through the 180° bend of the solar collector- affects the microalgae growth, as stated in the literature.