Study of Ammonia Dissociation System for Portable Fuel Cells

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In this research, the researchers have described a fuel-cell electric vehicle for trial purposes with the hydrogen generation system fueled with ammonia for compact vehicles. The system consists of a dissociator with Ruthenium/Alumina catalyst, aheat exchanger and an ammonia separator to remove residual ammonia. The dissociation system compactly unifies the heat exchanger and the dissociator to effectively rise the temperature of the system by installing some alumina balls just before catalyst. Therefore the system can be small in size enough to be installed on-board in the vehicle.The cruising time is about 160 minutes in the system. If the concentration of residual ammonia in the dissociated gas becomes 13 ppm or more, the residual ammonia will poison the proton exchange membrane (electrolyte) of the fuel cell, and cause the fuel cell to decrease the output. The residual ammonia in the separator must be removed, because the ammonia concentration in the dissociated gas reaches 13 ppm after 160 minutes in the experiment. If the residual ammonia is removed, the system can be expected to be about 2.5 times of the cruising time. In addition, it is estimated that the fuel cell will probably work for about 20 hours with 10 liters of liquid ammonia.In this research, the hydrogen generation system fueled with liquid ammonia for fuel cells was proposed, and the vehicle with the ammonia dissociation system was actually manufactured for a trial purpose. Ammonia will be also expected as an alternate fuel for the measure of the environmental problem. Although further improvement of energy efficiency and safety is needed, the fuel-cell electric vehicle can be one of the clean future vehides by assuming liquid ammonia as an alternate fuel for fuel cells.