This dissertation deals with gasoline on-board exhaust gas fuel reforming to produce hydrogen in vehicle system. The automotive industry faces problems with regard to its consumption of fossil fuel and pollutants emissions. In current manner, hydrogen in vehicle is presented for the improvement of current vehicle system. Therefore, we must find a stable and continuous method for supplying hydrogen to the vehicle. In this dissertation, validation of the possibility of exhaust gas fuel reforming and elementary studies for vehicle application were investigated.
Thermodynamic equilibrium calculations were validated the appropriate on-board fuel reforming oxidant. According to results, lean burn exhaust gas was suitable for on-board fuel reforming system.
To confirm the suitable operating condition, catalytic reforming experiments were investigated. Elementary tests using iso-octane were investigated with Pt/CGO (0.5 wt. %). Exhaust gas with high oxygen concentration was produced less hydrogen. In commercial gasoline test, highest hydrogen production was obtained at the exhaust gas ratio of 2~3% at the fuel ratio of 5%. However, degradation occurred when under 700$\circ C$ and lack of oxidant supply. To operate sustainable reforming system, catalysts screening and applying fuel injector were investigated. Among Pt, Rh, Ru catalysts, Ru catalyst was activated until 600$\circ C$. Therefore, the Ru/CGO (0.5 wt. %) is suitable for on-board exhaust gas fuel reformer. In addition, application of fuel injector increased reforming performance at lower and higher exhaust gas ratio.
Operation tests of exhaust gas gasoline reforming were investigated at various exhaust gas condition on 600oC with Ru/CGO. Generally, catalytic exhaust gas fuel reforming produced about 1.5~2.5% of hydrogen energy fraction of gasoline in engine. With addition of carbon monoxide in reformate, energy fraction increases about 3~5%. Also, with connection of the reformer to engine, hydrogen was produced similar to micro reactor operation and improved fuel economy by 1~2% in DBL condition.
본 논문에서는 자동차 내에 큰 시스템의 변화 없이 지속적이고 안정적으로 수소를 생산하기 위해 배기가스를 산화제로 이용하는 가솔린 개질 시스템에 관한 연구를 수행하였다.
개질 산화제로 희박 연소 배기가스를 이용하는 것이 적합하다. Pt/CGO 촉매로 상용 가솔린을 개질하기 위해서는 800도 이상의 온도가 필요하여, 실제 차량에 도입하기 위해 600도에서도 작동하는 Ru/CGO 촉매를 이용하였고, 연료 분사기를 도입하여 안정적인 성능을 확보하였다. 개질기에 엔진 연료의 5%, 배기의 2~3%가 이용되었을 때, 전환효율 80% 수준의 수소 수득율을 확보하였다. 다양한 조성의 배기가스에 대해 엔진이 이용하는 가솔린 연료의 에너지 대비 약 1.5~2% 수준의 수소가 생성되었고, 일산화탄소를 포함시 약 3~5% 수준임을 확인하였다. 본 개질기를 실제 엔진과 연동하여 운전할 경우, 개질 반응이 일어나는 것을 확인하였으며, 엔진의 고부하 운전 조건에서 약 1~2% 연비가 향상됨을 확인하였다.
