Modeling and simulation of photobioreactors for biological hydrogen production

Androga, Dominic Deo
In applications of photofermentative hydrogen production, maintaining optimal temperature, feed composition, pH range and light intensity is the most critical objective for growth and proper functioning of the photosynthetic bacteria. Response Surface Methodology was applied to optimize temperature and light intensity for indoor hydrogen production using Rhodobacter capsulatus. Surface and contour plots of the regressions models developed revealed a maximum hydrogen production rate of 0.566 mol H2/m3/h at 27.5°C and 287 W/m2 and a maximum hydrogen yield of 0.326 mol H2/mol substrate at 26.8°C and 285 W/m2. For outdoor photofermentative hydrogen production many parameters are beyond manipulation, hence effective control of temperature in photobioreactors is a challenge. In this thesis, an internal cooling system was designed and built, and its performance in outdoor tubular photobioreactors was tested during summer months in Ankara, Turkey. Four tubular reactors with and without Rhodobacter capsulatus were operated in parallel. Counter-current and co-current cooling modes were implemented to stabilize the reactor temperature. The temperatures were found to be strongly influenced by the solar irradiance and the ambient air temperature during daytime; however, the surface temperature was found to be approximately constant along the reactor length. Counter-current cooling was found to be more effective compared to co-current cooling in controlling temperatures inside the reactor. High biomass growth rate (0.10 per hour) and hydrogen production rate (1.3 mol H2/m3/h) was achieved in the outdoor operations. The flow distribution in tubular reactors operated at steady state conditions was analyzed using computational fluid dynamics. A one-dimensional dynamic thermal model to describe the variations of temperature in tubular reactors operated outdoors with or without internal cooling was developed and verified with experimental data. The transient model included the effects of convection and radiative heat exchange on the reactor temperature throughout the day. The model established is useful in estimating the cost-effectiveness of producing hydrogen in large scale outdoors.


Implementation and analysis of temperature control strategies for outdoor photobiological hydrogen production
Deo Androga, Dominic; Koku, Harun; Uyar, Başar; Eroglu, Inci (null; 2014-01-01)
In applications of industrial biotechnology, maintaining an optimal temperature range is crucial for growth and proper functioning of microorganisms. For outdoor photobiological hydrogen production many parameters are beyond manipulation, hence effective control of temperature in photobioreactors is a challenge. In this work, an internal cooling system was designed and built, and its performance in outdoor tubular photobioreactors tested during summer months in Ankara, Turkey. Media with and without bacteri...
Modeling and sensitivity analysis of high temperature PEM fuel cells by using Comsol Multiphysics
Sezgin, Berna; Caglayan, Dilara Gulcin; DEVRİM, YILSER; Steenberg, Thomas; Eroğlu, İnci (2016-06-22)
The objective of this study is to observe the effect of the critical design parameters, velocities of inlet gases (hydrogen and air) and the conductivity of polymer membrane, on the performance of a high temperature PEM fuel cell. A consistent and systematic mathematical model is developed in order to study the effect of these parameters. The model is applied to an isothermal, steady state, three-dimensional PEM fuel cell in order to observe concentration profiles, current density profiles and polarization ...
Phototrophic hydrogen production by agar-immobilized Rhodobacter capsulatus
Elkahlout, Kamal E. M.; Yücel, Ayşe Meral; Eroğlu, İnci; Department of Biotechnology (2011)
photosynthetic bacteria is attractive field as production is fueled by solar energy. Hydrogen production potential of two photosynthetic bacteria R.capsulatus (DSM1710 wild type and R.capsulatus YO3 Hup- uptake hydrogenase deleted mutant strain) were examined in agar immobilized systems. In the present work agar and glutamate concentrations were optimized for immobilization of bacteria while feeding bacteria with 40/2-4 mM acetate/ glutamate. Immobilized bacteria produced hydrogen for 420-1428 hours coverin...
Direct synthesis of hydrogen storage alloys from their oxides
Tan, Serdar; Öztürk, Tayfur; Aydınol, Mehmet Kadri; Department of Metallurgical and Materials Engineering (2011)
The aim of this study is the synthesis of hydrogen storage compounds by electrodeoxidation technique which offers an inexpensive and rapid route to synthesize compounds from oxide mixtures. Within the scope of this study, two hydrogen storage compounds, FeTi and Mg2Ni, are aimed to be produced by this technique. In the first part, effect of sintering conditions on synthesis of FeTi was studied. For this purpose, oxide pellets made out of Fe2O3-TiO2 powders were sintered at temperatures between 900 °C – 1300...
Kinetic analysis of photosynthetic growth, hydrogen production and dual substrate utilization by Rhodobacter capsulatus
Sevinc, Pelin; Gündüz, Ufuk; EROĞLU, İNCİ; Yucel, Meral (2012-11-01)
Rhodobacter capsulatus is purple non-sulfur (PNS) bacterium which can produce hydrogen and CO2 by utilizing volatile organic acids in presence of light under anaerobic conditions. Photofermentation by PNS bacteria is strongly affected by temperature and light intensity. In the present study we present the kinetic analysis of growth, hydrogen production, and dual consumption of acetic acid and lactic acid at different temperatures (20, 30 and 38 degrees C) and light intensities (1500, 2000, 3000, 4000 and 50...
Citation Formats
D. D. Androga, “Modeling and simulation of photobioreactors for biological hydrogen production,” Ph.D. - Doctoral Program, Middle East Technical University, 2014.