Study of Ammonia Dissociation System for Portable Fuel Cells

在这项研究中，研究人员描述了一种用于试验目的的燃料电池电动汽车，其氢生成系统以氨为燃料用于紧凑型汽车。该系统由钌/氧化铝催化剂解离器、热交换器和氨分离器组成，以除去残余氨。分解系统将换热器和分解器组合在一起，通过在催化剂前安装氧化铝球，有效地提高了系统的温度。因此，该系统的尺寸可以小到足以安装在车辆上，巡航时间约为160分钟。如果离解气体中的残留氨的浓度变为13 ppm或更高，则残留氨将使燃料电池的质子交换膜（电解质）中毒，并导致燃料电池的输出降低。分离器中残留的氨必须除去，因为在实验中160分钟后离解气体中的氨浓度达到13 ppm。如果去除残留的氨，则可以预计系统的巡航时间为2.5倍左右。另外，估计10升液氨的情况下，燃料电池大概可以工作20小时左右。本研究提出了以液氨为燃料的燃料电池用氢生成系统，并实际制造了具有氨分解系统的车辆进行试验。氨也有望作为一种替代燃料来解决环境问题。虽然需要进一步提高能源效率和安全性，但通过假设液氨作为燃料电池的替代燃料，燃料电池电动汽车可以成为未来清洁车辆之一。

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.