An Experimental Study of Moisture Transport through a Porous Plate

摘要

This investigation was made in order to clarify the mechanism of moisture transport and to prevent the flooding that appears in a polymer electrolyte membrane fuel cell stack. The characteristics of heat and mass transport, between constant-temperature water and dry air, through a porous media plate with very small pores were investigated. Experiments were performed with an air velocity of 1.2-8.8 m/s and water temperatures of 20°C, 46°C and 67°C. The effects of various parameters, such as air velocity, porosity of the porous media, plate thickness, water temperature, vacuum impregnation etc., on moisture transport through the porous plate were measured. A porous plate with pore diameters of 3.5 μm and thermal conductivity of 20.2 W/m K was used. The heat and mass transfer performance was shown to increase with air velocity and water temperature. It was also understood that vacuum impregnation had a remarkable affect on the transport of moisture through the porous plate. In addition, a parameter called the moisture absorption rate was introduced to evaluate the utilization degree of capacity of air to absorb moisture. The moisture absorption rate decreased with increases in air velocity and water temperature.