Date of Award

2013

Degree Type

Thesis

Department

Chemical and Biomedical Engineering

First Advisor

Gatica, Jorge

Subject Headings

Algae, Computational fluid dynamics, Biomass energy, Algae Dewatering Gravity settler Inclined gravity settler Fluid dynamics Fluid flow Particle trajectories

Abstract

Algae are the future of lipid sources for biodiesel production. Algae can produce more biodiesel than soybean and canola oil and can be grown in more diverse locations. Algae concentrations are naturally around 0.1 by weight. Enough water must be removed for the algae level to reach 5 , the minimum concentration in which lipids can be used in the transesterification process for biofuel production is 5 . Current dewatering methods involve the use of settling tanks and centrifugation. The costs of centrifugation limit the commercial viability of algae based biodiesel. A novel inclined gravity settler design at Cleveland State University is analyzed in this project. A major difference between this and a traditional gravity settler is that the inlet of this gravity settler is at the top, whereas traditional gravity settlers have inlets at the bottom. A computational fluid dynamics model for the system has been developed to allow tie simulations of fluid flow and particle trajectories over time. These simulations determine the optimal conditions for algae dewatering. Results show that the concentration increase of algae is largely dependent on the settler's angle of inclination, inlet flow rate, and the split ratio of water between the overflow (predominantly water) and underflow (concentrated algae) outlets. A 50-fold concentration increase requires multiple settlers set up in series. A two- or three-settler design is sufficient to increase algae concentration the desired level

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