Oxides of Nitrogen in the Combustion Products of an Ammonia Fueled Reciprocating Engine

A single cylinder investigation was conducted to determine concentration of oxides of nitrogen resulting from combustion of ammonia and air in a spark ignition engine over a range of fuel-air ratios typical of normal engine operation with ammonia. Nitric oxide concentrations exceeded that with hydrocarbons.

Spectroscopic observations during the expansion process gave concentrations in some instances an order of magnitude greater than exhaust gas determinations. The results imply a different mechanism for nitric oxide formation with ammonia fuel than with hydrocarbons and that some equilibrating process may take place between combustion and exhaust to reduce otherwise even greater than measured exhaust gas concentrations.