Performance characteristics of ammonia engines using direct injection strategies

In this study performance characteristics of ammonia engines using direct injection strategies are investigated. Ammonia is a carbon-free fuel, and thus its combustion does not produce carbon dioxide, a critical greenhouse gas. Ammonia can be produced by using renewable energy sources (e.g., wind and solar) and used as an energy carrier. Recent research also has shown that the efficiency of solar thermochemical production of ammonia can be increased by combining the ammonia solid-state synthesis cycle with hydrogen production. Ammonia is under consideration for a potential storage method for wind energy. Ammonia’s nature as carbon-free and its ability to be renewably produced make it an alternative to fossil fuels. In this study two direct injection strategies are tested and performance data, and exhaust emissions are recorded and analyzed. The first strategy tested liquid direct injection in a compression-ignition (diesel) engine utilizing highly advanced injection timings. Ammonia was used with dimethyl ether (DME) in a duel fuel combustion strategy. Ammonia was mixed with DME prior to injection. DME was chosen as a diesel substitute for its close fuel properties to ammonia. Three ammonia-DME ratios were tested: 100%DME, 60%DME-40%NH3, and 40%DME-60%NH3. Engine speeds of 1900 rpm and 2500 rpm were used based on the operational capability of 40%DME-60%NH3. Operation at 40%DME-60%NH3 required injection timing ranging from 90-340. Highly advanced injection timings resulted in homogeneous charge compression ignition combustion (HCCI). Cycle-to-cycle variations were reduced with increased load. NOx,