Investigation on novel raceway pond with inclined paddle wheels through simulation and microalgae culture experiments

Abstract

The open raceway ponds are nowadays the most used large-scale reactors for microalgae culture. To avoid the stacking of microalgae, the paddle wheels are the most widely used to circulate and mix the culture medium. In this paper, a numerical simulation using computational fluid dynamics (CFD) was used to investigate the hydrodynamic characteristics of open raceway ponds with different types of paddle wheels (the traditional paddle wheels and the novel paddle wheels with specially inclined angle of the blades). The particle image velocimetry (PIV) was used to validate the reliability of the CFD model. The CFD simulation results showed that the novel raceway pond with 15° inclined angle of the blades had the best mixing efficiency under the same power consumption. Lastly, the results of microalgae culture experiments showed that the growth rates of Chlorella pyrenoidosa in the novel raceway pond with 15° inclined angle of the blades were higher than those in the traditional reactor. The results of the culture experiments and CFD simulations were identical with each other. Therefore, a novel paddle wheel with 15° inclined angle of the blades was obtained for better microalgae cultivation.

Image segmentation with fast distance transform (FDT) and morphological skeleton in microalgae Raceway culture systems applications

“…In some works such as that of (Zeng et al, 2016) aluminum oxide (Al 2 O 3 ) particles with a diameter of 10 µm are used. The particles used in this work are 100 µm in size and are capable of fulfilling their function.…”

“…The systems described in the literature, referring to the capture of images in Raceway bioreactors, are limited to obtaining images by sections, a particular case is that of (Zeng et al, 2016), which makes use of particle image velocimetry (PIV). However, the conditions of your system are different from those proposed here.…”

“…The FDT per se does not allow segmenting, so other processes are necessary. It is here where the morphological skeleton plays an important role to perform image segmentation based on the FDT, see Figure 1 C. The FDT has not been exploited in the hydrodynamic study of bioreactors, due to commercial particle image velocimetry systems are used (PIV) by cross-correlation algorithm to describe the displacement of the tracer (Zeng et al, 2016). In addition, image analysis through segmentation and distance maps has been focused on other areas such as the coffee study by Fourier transform (Hernandez-Aguirre et al, 2019).…”

Advanced CFD model of multiphase photobioreactors for microalgal derived biomass production

“…In terms of review multiphase CFD models, the review will summary the applications of CFD in simulation of mixing and mass transfer in PBRs in the last decade. It can be seen from Table 2.1 that CFD simulations have been 5 applied to many kinds of photobioreactors, such as raceway reactor (Xu et al, 2014;Hreiz et al, 2014;Prussi et al, 2014;Park and Li, 2015;Huang et al, 2015;Zeng et al,2016), flat plate (Shu et al, 2010;Zhang et al, 2012;Wang et al, 2014;Huang et al, 2014;2015;, airlift (Luo and Al-Dahhan, 2011;Li et al, 2012;Massart et al, 2014;Soman and Shastri, 2015), bubble column (Mortuza et al, 2012;Seo e al., 2012;Nauha and Alopaeus, 2013;2015;Gerdes et al, 2014;Gerdes et al, 2014;Bitog et al, 2014;Bari et al, 2014;2015), tubular (Moberg et al, 2012;Zhang et al, 2013;Gómez-Pérez, 2015;Cheng et al, 2016), stirred tank (Zhang, 2013;Delafosse et al, 2014;Delafosse et al, 2015;Krujatz et al, 2015), torus (Pruvost et al 2006;, virtual (Sato et al, 2010), Taylor-Couette (Gao et al, 2015a;2016a) and so on. CFD simulation was mainly used to design and optimize novel reactors or internals by studying the flow hydrodynamics, mass transfer and algae cell trajectory.…”

“…The dispersed turbulence model is commonly used, where the liquid phase turbulence is modeled using either an eddy viscosity model or a Reynolds stress model, while the gas phase is assumed to be laminar due to low flow rates usually employed. It can be seen from (Mortuza et al, 2012;Seo e al., 2012;Nauha and Alopaeus, 2013;2015;Gerdes et al, 2014;Gerdes et al, 2014;Bari et al, 2014;2015), airlift (Luo and Al-Dahhan, 2011;Massart et al, 2014;Soman and Shastri, 2015), flat plate (Shu et al, 2010;Zhang et al, 2012;Huang et al, 2014;Wang et al, 2014; and raceway reactor (Xu et al, 2014;Hreiz et al, 2014;Prussi et al, 2014;Park and Li, 2015;Huang et al, 2015c;Zeng et al,2016), the standard k-ε turbulence model and its variants were widely used to model the liquid turbulence because of its simplicity and lesser computational expensive. Sometimes the k-ε turbulence model was modified to account for the bubble induced turbulence (Luo and Al-Dahhan, 2011;Li et al, 2012).…”