Inlet air (15) humidified in an air bubbling (or other) humidifier (35)
that receives water from a tank (36) is sent to a hydrogen generator (27)
along with vaporized (23) diesel fuel (22) to produce hydrogen and
carbon monoxide (28) for either (a) mixing with the mainstream of exhaust
(18) fed to a catalytic converter (30) or (b) regenerating a pair
of NOx adsorption traps (38, 39), thereby reducing oxides of nitrogen (NOx),
to provide system exhaust (32) which may have less than 0.40 grams/bhp/hr
of NOx and 0.28 grams/bhp/hr of non-methane hydrocarbons. In other embodiments,
unhumidified air mixed with fuel feeds a homogeneous non-catalytic partial oxidizer
(27) to provide the required hydrogen and carbon monoxide.