Dynamic Characteristics of DMFC/Battery System for Notebook PC

Abstract

Many research groups have been working on direct methanol fuel cells for the portable applications because of the convenience of using the liquid fuel, methanol. Particularly the direct methanol fuel cells are studied for military applications because of increasing use of power-hungry, state-of-the-art, and wearable electronic digital equipment by today’s soldiers. Life time of the potable power supply devices becomes more important as the amount of power consumption of the electronic and communicational equipment increases. At present, direct methanol fuel cells (DMFCs) which uses liquid methanol without a reformer are considered to meet these requirements best. In order to achieve rapid start-up and high reliability required for these applications, we combined a DMFC with a lithium-ion battery. In the present work, the sharing of power consumption at the start-up and the response characteristics of each component of the fuel cell/battery hybrid system to power consumption were investigated. The characteristics of battery charging at the rated operation also were determined when hybrid system was running a notebook PC. Recent DMFC investigations have identified important system engineering issues such as long term stability, under static and dynamic loads, and response to the dynamic operation. Argyropoulos et al. have shown that the dynamic performance of the DMFC is affected by complex interactions of electrode kinetics and mass transport processes. It was also shown that the dynamic response of the DMFC cell voltage is significantly affected by the methanol solution flow rate, methanol concentration and applied cathode air pressure.