A fast start up system for microfluidic direct methanol fuel cells

A novel simple and effective heating system for microfluidic direct methanol fuel cells was characterized experimentally. It consisted of a semi-conductive indium tin oxide heating layer of nanometer thickness that was applied to the anode and cathode cover plates and subjected to high electrical power. Within only 25 s, temperatures of up to 80 degrees C were reached in the vicinity of the membrane, which was verified experimentally. With this system the time needed to generate more than 90 % of the maximum output power of the fuel cell can be reduced to 20 s, thus overcoming the well known problem of long start up times in the order of minutes of this type of fuel cells. Furthermore, deeper insight into the role of the convective heat transfer is given. For the first time simultaneous measurements of the three-dimensional velocity and temperature distributions within the anode channel of a microfluidic direct methanol fuel cell were performed by means of luminescence lifetime imaging and astigmatism particle tracking velocimetry. The experimental results prove a significant cooling effect of the anode flow, whereas the influence of the cathode flow is small. Finally, various possible future improvements to increase the efficiency of the heating system are identified. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.