مدل سازي و شبيه سازي پيل سوختي ميكروبي

چكيده انگليسي :

Modeling and Simulation of Microbial Fuel Cells Ramin Sedaqatvand r sedaqatvand@ce iut ac ir Date of Submission 2012 02 08 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language PersianSupervisors Mohsen Nasr Esfahany mnasr@cc iut ac ir Tayebeh Behzad tbehzad@cc iut ac irAbstractMicrobial fuel cells are one of the newly emerged technologies in the field of energy recovery and treatingwastewaters simultaneously which have attracted interest in recent years In this study MFC model basedon the direct conduction of electrons in biofilm has been presented and validated by available experimentaldata from litrature The presented model is able to predict the measured data with an acceptable accuracy Furthermore the investigation of anode potential variations demonstrated that the produced current densityshifts from zero to a saturated value in a narrow range around half saturation voltage The substrateconcentration showed similar effects but in a wider range According to these observations it is determinedthat the maximum attainable current density from a pure culture biofilm composed of Geobactersulfurreducens is 2 42 A m2 with acetate as substrate under the specified conditions If the anodicchamber would perform in batch mode under the defined conditions the current pattern will be repeatedwith each fresh substrate injection with the existence of a mature biofilm The maximum current will reach3 12 mA in this case The performance of anodic compartment was examined in continuous flow for thefirst time The results obtained for continuous flow of substrate in a cylindrical anodic chamber with thebiofilm developed over its inner surface showed that the overall process was controlled by external masstransfer resistance In this situation reducing the diameter and increasing the length of the tube aregenerally favorable in viewpoint of both elevated current density and treatment efficiency The inletsubstrate concentration showed no influence on treatment efficiency while resulted in raising the currentdensity Treatment efficiency decreased with flow rate this effect saturated finally for high flow rates With defining a novel boundary condition for potential equation it would be possible for the first time toinvestigate the effects of external electrical load using polarization curves by conduction based model Theobtained results demonstrated that for a biofilm made up of G sulfurreducens and with the presence ofacetate the major overpotentials were associated with the mass transfer resistances It would be possible todetermine quantitatively the effects of biofilm conductivity and concentration film thickness on MFCperformance The contributions of ohmic and mass transfer polarization increased with decrease in thebiofilm conductivity and increase in the thickness of the concentration film adjacent to biofilm respectively These polarizations decreased the maximum output power density Finally by using theverified model the design parameters for an annular MFC with spiral anode were estimated employinggenetic algorithm and then validated for the first time The optimized parameters implied that the effectiveanode surface area increased by 64 76 for a screen with a mesh of 300 It is not possible to measuresurface area experimentally The polarization behavior of this system clarified that the ohmic overpotentialwas responsible for the major voltage drop due to the low biofilm conductivity obtained for the presentbiofilm The behavior of the MFC was examined with the constant concentration of 1 mgCOD cm3 andexternal load of 50 The potential gradient inside the biofilm was remarkable compared to the biofilmmade of G sulfurreducens The biofilm thickness increased unlimitedly due to not considering thedetachment of the biofilm causing the internal mass transfer resistance to increase continuously Keywords Microbial fuel cell modeling and simulation direct conduction parameter estimation geneti

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مدل سازي و شبيه سازي پيل سوختي ميكروبي

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