Flow control applied in recirculation mode microbial fuel cells

• Main Authors: Yan-Ming Chen, 陳彥銘
• Other Authors: Yung-Chin Yang
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/br6pg5

博士 === 國立臺北科技大學 === 材料科學與工程研究所 === 106 === Flow control is a significant issue in microbial fuel cells (MFCs) because the activation losses and concentration losses of MFCs are influenced by the thickness of hydrodynamic boundary layer. On the other hand, dimensionless parameters are suitable to be applied as the parameters for flow control because they not only could address the flow impacts on MFCs, but also have the potential for reactor upgrading invariable of the reactor scale. In the present research study, three hydrodynamic boundary layers of thicknesses 1.6, 4.1, 5 cm and four dimensionless parameters like Reynolds number (Re), Péclet number (Pe), Schmidt number (Sc) and Sherwood number (Sh) were used to investigate the electricity output of recirculation mode microbial fuel cells. The results showed that high shear rate effects were obtained on the thin hydrodynamic boundary layer and maximum MFC voltage of 21 mV was reported with hydrodynamic boundary layers of thickness 1.6 cm. It was 15 times higher than that of 5 cm wall boundary layer thickness. In addition, the MFC anode activation losses of 1.6 cm hydrodynamic boundary layer thickness was 39 Ω, which was 0.79 times less than that of 5 cm hydrodynamic boundary layer thickness. High Reynolds number could enhance the convective flow of anolyte due to dominant inertial forces in the flow field. Therefore, the high mass transfer coefficient K of 4.76×10-7 m/s and thin diffusion layer thickness of 2.52×10-3 m were obtained at Re∞=1.6×101. Maximum power density and limited current density were 2422.8 mW/m2 and 4736.4 mA/m2, respectively. They were much higher than values at Re∞=0 by 1.61 times and 1.69 times, and these findings would be useful for effective MFC power production and applications in the future.