The performance of a Direct Methanol Fuel Cell has been experiment and analysis in this research. The performance of Direct Methanol Fuel Cell were tested by changing different parameter, such as methanol concentration, temperature, and the effect of carbon dioxide. This influence include transient and steady-state respond. Through the experiment and analysis, we hope we could understand the important factors which influence the performance of the DMFC. This experiment use Nafion® as membrane electrode assembly, and the ratio of flow channel area to total electrode area is 58%. The performance of the single cell was enhanced by increasing methanol concentration as the experiment result, no matter transient or steady-state respond. The best performance was obtained from 2M. The performance at transient or steady-state was also improved by increasing methanol/cell temperature. The product of the reaction, carbon dioxide, will cause more influence when cell work at higher current. In addition, there are few carbon dioxide which will appear as gaseous state.

Direct Methanol Fuel Cells (DMFCs) are a promising source of energy due to their potentially high energy density, facilitated fuel delivery and storage, and precluded fuel processing. However, DMFCs have several challenges which need to be resolved before they can replace existing energy sources. Some of the challenges include lower power density, relatively high cost, and uncertain reliability. These issues are all promoted, at least in part, by the methanol crossover phenomenon, wherein membrane permeability allows the undesirable species transport of methanol from anode to cathode. This phenomenon also causes the requirement of dilute fuel mixtures, which is undesirable from an energy density viewpoint. Steady flow polarization curves were first analyzed at various concentrations. An optimal concentration range was found wherein both methanol crossover and concentration losses were effectively minimized. During the study of transient phenomena, the fuel was first temporarily discontinued. It was found that a significant cell potential enhancement occurred due to anodic fuel concentration reduction and thus depleting the reactant crossover. The percentage voltage increase was considerably greater at higher concentrations. Based on the fuel discontinuation, a hydraulic pulsing operation was developed and tested. During some of these continuous pulsing schemes, fuel discontinuation did not result in an instantaneous cell potential enhancement mainly due to the internal inertia of the membrane. Nonetheless, a significant cell potential and fuel efficiency enhancement was observed. In addition, the pulse of both fuel and current density resulted in a significant power density increase.

Thesis (M. Tech.) (Engineering: Electrical, Dept.: Electronic Engineering))--Vaal University of Technology, 2008. / The demand for higher efficiency, sustainability and cleaner power sources increases daily. A Direct Methanol Fuel Cell is a power source that can be applied for small to medium household appliances and office equipment. It can ideally be used for operating appliances like notebook computers on remote sites where no electrical power is available. One of the problems in methanol fuel cells is methanol crossover. Methanol crossover occurs when methanol is not completely used in the process of generating electrons, and a certain percentage of the methanol is wasted. Crossover may damage the proton exchange membrane of the fuel cell and reduce the efficiency of a DMFC. Literature reviews were done and suggestions from other writers are discussed on how to reduce methanol crossover. This research focuses primarily on the fact that crossover can be controlled by controlling the methanol / water concentration. A prototype methanol controller was built with an ultrasonic sensor for detecting the density of the methanol/water mixture and a sensor for the temperature of the mixture; this was done because the density of the mixture is dependant on the temperature and the concentration. The controller was calibrated to determine the amount per volume of water and methanol which enables the controller to control the percentage of methanol in the water. The prototype also had the feature built in to adjust the mixture in order to enable the study on the effects of crossover. A data logger function was added to store collected data on a personal computer for the study on methanol and water. It was observed that the sensor was sensitive enough and was able to produce 1% increments of the level of methanol concentration in the water provided the temperature was stable. A methanol controller was successfully built to ensure the correct volume of methanol. / Telkom Centre of Excellence