Improvement of Diesel Exhaust Emissions by Injecting Water or Metal-Salt Solutions into the Combustion Chamber

摘要

The effect of water and several aqueous metal-salt solutions on NOx and smoke lowering in an IDI diesel engine was examined. The water and solutions were directly injected into a divided chamber independent of the fuel injection. The results showed that significant lowering in NOx over a wide operation range could be achieved with water and metal-salt solutions which were injected just prior to the fuel injection. The degrees of NOx lowering with the metal-salt solutions were larger than with the water alone, and smoke emissions were also simultaneously lowered with alkali-metal solutions. With sodium-salt solutions, NOx decreased by more than 60 % and smoke decreased 50 % below conventional operation. The sodium-salt solution reduced dry soot significantly, while total particulate matter increased with increases in the water soluble fractions.