Experimental Study on Pure Ammonia as a Single Fuel in a Range-Extended Electric Vehicle

Ammonia can significantly reduce carbon emissions when used in internal combustion engines. However, pure ammonia is considered difficult to ignite and has a slow flame propagation speed, which makes its application challenging. Furthermore, previous research on pure ammonia engines has been based on bench tests, with no vehicle-level tests reported to date. In this study, an engine was tested using pure ammonia as a single fuel in a range-extended hybrid electric vehicle. First, a pure ammonia hybrid power system was implemented in a light-duty vehicle. By motoring the engine instantly to its optimal operating window, the hybrid mode ensures a rapid transition to stable combustion. The results show that, using pure ammonia, the engine can operate stably within a speed range of 1000–3175 rpm. The engine achieves an output power of 45 kW, with an indicated thermal efficiency exceeding 40% under 3175 rpm. Compared to gasoline, pure ammonia has a longer ignition delay but a similar combustion duration. Pure ammonia requires an earlier spark timing and higher intake temperature. The ammonia and NO remain high even after being treated by a three-way catalyst. This research verifies the feasibility of using pure ammonia as a single fuel in hybrid modes, offering broad application prospects in scenarios such as marine power and stationary power generation.