A Two-Charge Engine Concept: Hydrogen Enrichment
The first engine dynamometer test results are presented for a modified fuel system based on hydrogen enrichment for a V-8 I.C. engine. The engine burns mixtures of gasoline and hydrogen under ultralean conditions to yield extreme low NOx emissions with increased engine efficiency.
The hydrogen is produced in a compact onboard generator from gasoline and air. The hydrogen-rich product gas is cooled and mixed with the normal combustion air in a modified carburetor. The engine then operates in the conventional manner on atomized gasoline with spark ignition, but with hydrogen-enriched air and with a high spark advance of 40-50° BTDC. The engine thus receives two charges of fuel: a charge of gaseous fuel from the hydrogen generator, and the normal gasoline charge.
The results on hydrogen enrichment are compared with the 1973 V-8 baseline stock engine with emission controls, and the same engine without controls and operated at a maximum efficiency under lean conditions. All results are compared at level road load as a function of rpm.
Relative to the stock 1973 350 CID engine, an approximate 10 percent reduction in brake specific fuel consumption was measured over the entire level road load speed range. For the same condition, NOx emissions were reduced to below the equivalent 1977 EPA Standards (0.4 gm/mi). Further effort is required to reduce the remaining two exhaust pollutants to the corresponding level, i.e. 0.41 gm/mi HC and 3.4 gm/mi CO.
The hydrogen enrichment concept is compared with a pre-chamber stratified charge engine. The analogy is made that if the pre-chambers for each cylinder were combined into a single pre-combustor, it shows some similarities to the hydrogen generator.