Experimental Study Of Influence Of Gravity On Performane Of A Passive Derict Methanol Fuel Cell

Passive direct methanol fuel cell is considered to be the future hope that willalternative to the today widespread use about lithium batteries in the field of portablepower. The mass transfer process is quite different accompanied by theelectrochemical reaction and the characteristics are also significantly affect theperformance of cells. The influence of parameters on the mass transfer characteristicsin passive direct methanol fuel cell there are many forces, including buoyancy,surface tension, the electrochemical reaction source term of pressure and capillaryforce, etc. To one FC has been designed, important parameters that could be easilyadjusted always include the methanol concentration, the cells operating temperature,and cells placement angle, etc. And the affect of cells placement angle which alsomean influence of gravity to cells performance has been described more than others.Two-phase flow inside passive-DMFC anode that bubble growth characteristicsis different with the active one. This paper will continuation passive-DMFCexperimental research, then re-design visualization, set up a transparent viewingwindow on anode and instant access to the bubble growth under different currentdensity variation. According to the experiment results, anode bubble growth will bedifferent when in different current indenty. The difference will be more obvious whenthe anode up.Observe and analyze the data of the visual image will found that thecharacteristics of bubble growth characteristics is basically divided into three intervalswhich include the cell anode down, the cell vertical placement and the cell anode up.When the cell anode down, the bubbles move out of the membrane will be moredifficult, time will be langer and the size will be larger. When cell at90o, the time andsize will be greatly reduced, but the bubbles still gather at the upper edge of the plateholes. When anode up, the bubbles appear in the same plate hole position will morethan one, and hardly effect on each other, the bubble departure time and the size of thedetachment will have little difference in the inclination range.In generally, they are not only have the diffusion caused by differentconcentration but also have mixed convection due to gravity and other forces causedby this transfer process. The intensity about them can not be effectively distinctionclearly. And change the cell dip will change the angle between the two driving forces which will make the performance curve of current density different and thus can getsome indirect data to infer the related processes. Apply the micro-gravity technologywill make this result more contrast. Accounting to the experimental results, theelectrochemical source pressure on the anode bubble growth is obviously. In themixed convection, the intensity between forced convection and the natural convectionshould in the same order of magnitude.