Papers by Author: Ze Ting Yu

Abstract: In this work, a transparent passive DMFC was constructed to investigate the transients in open circuit voltage (OCV) and the cell temperature difference, which changed as a consequence of the methanol crossover phenomenon, including anode temperature difference (ATD), cathode temperature difference (CTD) and methanol solution temperature difference (MTD). Experiments were carried out in a passive DMFC with an active membrane area of 9 cm2, at ambient temperature and pressure. Results showed that the OCV of the passive DMFC became relatively stable as the cell temperature difference rose to a relatively stable value about 30 min later. At the middle and high current densities (>2.21 mA cm^-2), the performance increased continuously with increasing the waiting time, but became stable when the waiting time was longer than 30 min. The experimental results indicated that the performance of the passive DMFC could be more objectively characterized by collecting polarization data simultaneously when the cell temperature rises to a relatively stable value. Without the temperature measuring equipment, a waiting time about 30 min would be a good choice for collecting polarization data.

Abstract: In this work, a transparent passive DMFC was constructed to investigate the CO₂ bubble behavior in perforated current-collector (PECC) and parallel current-collector (PACC) by using a digital camera. Experiments were carried out in a passive DMFC with active membrane area of 9 cm², working at ambient temperature and pressure. Results showed that small discrete bubbles appeared in PECC at low current densities; while the PECC was predominated by big bubbles at high current densities, which led to deterioration of methanol mass transfer. On the contrary, the PACC was more efficient to remove CO₂ bubbles than the PECC did. Therefore, it gained a better performance at high current densities.

Abstract: In this work, the effect of the current-collector structure on the performance of a passive direct methanol fuel cell (DMFC) was investigated. Parallel current-collector (PACC) and other two kinds of perforated current collectors (PECC) were designed, fabricated and tested. The studies were conducted in a passive DMFC with active membrane area of 9 cm², working at ambient temperature and pressure. Two kinds of methanol solution of 2 M and 4 M were used. Results showed that the PACC as anode current-collector has a positive effect on cell voltage and power. For the cathode current-collector structure, the methanol concentration of 2 M for PECC-2 (higher open ratio 50.27 %) increased performance of DMFC. But the methanol concentration of 4 M led to an enhancement of fuel cell performance that used PACC or PECC-2 as cathode current-collector.