Numerical simulation of the performance of air-breathing direct formic acid microfluidic fuel cells

• Published in: Micro & nano letters Vol. 12; no. 11; pp. 860 - 865
• Main Authors: Herlambang, Yusuf Dewantoro, Shyu, Jin-Cherng, Lee, Shun-Ching
• Format: Journal Article
• Language: English
• Published: Stevenage The Institution of Engineering and Technology 01.11.2017; John Wiley & Sons, Inc
• Subjects: Acids; air‐breathing direct formic acid microfluidic fuel cells; aqueous solution; Breathing; Brinkman equation; Butler–Volmer equation; charge equation; Charge transport; Computer simulation; COMSOL Multiphysics 5.1; Continuity equation; current density; current density distribution; Current distribution; Current loss; Density distribution; Diffusion layers; electrochemical electrodes; electrode spacing; Electrodes; electrolyte; electrolytes; Electrolytic cells; flow simulation; flow through porous media; Formic acid; Fuel cells; gas diffusion layer; Gaseous diffusion; Inlet flow; inlet flow rates; internal current loss; I–V curves; Mathematical analysis; Mathematical models; microchannel flow; microchannel width; momentum equation; numerical analysis; numerical simulation; organic compounds; Porous media; P–I curves; reactant concentration; Simulation; Special Issue: Selected Papers from The 12th Annual IEEE International Conference on Nano/Micro Engineered and Molecular Systems (IEEE-NEMS 2017); species transport equation; Sulfuric acid; sulphuric acid stream; Three dimensional models; three‐dimensional MFC model; Transport phenomena; flow simulation; COMSOL Multiphysics 5.1; gas diffusion layer; three-dimensional MFC model; electrolytes; sulphuric acid stream; charge equation; air-breathing direct formic acid microfluidic fuel cells; numerical analysis; fuel cells; species transport equation; momentum equation; numerical simulation; electrode spacing; aqueous solution; flow through porous media; electrochemical electrodes; P–I curves; inlet flow rates; Butler–Volmer equation; current density; continuity equation; Brinkman equation; microchannel flow; internal current loss; I–V curves; microchannel width; reactant concentration; organic compounds; electrolyte; current density distribution
• ISSN: 1750-0443; 1750-0443
• DOI: 10.1049/mnl.2017.0322

This work numerically investigated the effects of various factors on the performance of air-breathing direct formic acid microfluidic fuel cells. An MFC with a microchannel width of 1.5 mm, depth of 0.05 mm, and electrode spacing of 0.3 mm was used in the simulation. An MFC which was a 1.5-mm-wide, 0.05-mm-deep microchannel installed with two 0.3-mm-apart electrodes was used in the simulation. The mixture of formic acid at concentrations of 0.3, 0.5, and 1.0 M and 0.5-M sulphuric acid served as fuel, while a 0.5-M sulphuric acid stream served as the electrolyte introduced at inlet flow rates of 0.05, 0.1, and 0.5 mL/min. First, a three-dimensional MFC model was built using COMSOL Multiphysics 5.1 to simulate the fuel cell performance. Subsequently, I–V curves obtained from simulations and from published experimental data under similar operating conditions were compared to ensure the validity of the simulation. Transport phenomena were formulated with a continuity equation, momentum equation, species transport equation, and charge equation. Additionally, the flow through porous media in the gas diffusion layer was described using the Brinkman equation, whereas the Butler–Volmer equation was applied to obtain I–V and P–I curves. The current density distribution resulting from internal current loss and reactant concentration on both electrodes was also determined in this work.