engleski

Maintaining Desired Temperature and Relative Humidity throughout a Fuel Cell

A concept of using the product water to internally humidify the air stream in a PEM fuel cell without external humidification is investigated by a simple, pseudo 2-D model along a single channel. This model takes into account the mass and energy balance, water and heat generation rates, heat removal, and water transport through the membrane. The model and thus the concept were confirmed experimentally using a 5-segment fuel cell. The temperature of each segment is individually controlled, and the temperature and humidity of air could are measured between each segment. A temperature profile has been established that results in relative humidity being close to 100% throughout the cell without any external humidification. Such a profile can be acheived by applying spatially variable heat removal rates along the cathode channel. Operation with spatially variable heat removal resulted in improved performance yielding 0.618 V at 0.5 A/cm2 as compared to 0.548 V achieved in the case of isothermal hardware.

PEM fuel cell; Water management; Relative humidity; Segmented model; Humid air Mollier diagram

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