No abstract

No abstract

No abstract

An experimental study focusing on the effects of different hydrogen enhancement levels on the engine performance and emission characteristics was conducted. The experimental data were compiled on a turbocharged lean-burn natural gas spark-ignition engine operated under various conditions, including idle. Data were taken for pure natural gas operation as well as hydrogen-enriched compressed natural gas (HCNG), including hydrogen volumetric fractions of 20, 30, and 40%. For comparison purposes, the lower heating value for each hydrogen/ natural gas ratio remained identical at each engine-operating condition. The results show that, under idle conditions, hydrogen addition can reduce the output of the engine of hydrocarbon and carbon monoxide emissions, which are the two largest problems associated with idle operation. It is also found that this reduction is more obvious at relatively delayed spark timings. Under normal operating conditions, hydrogen addition was found to be beneficial to simultaneously improving fuel economy and reducing HC emissions. Although hydrogen addition increases NO x emissions, this can be compensated for by retarding the spark timing and running leaner operation, which are allowed by the faster burning velocity and broader ignition limit of hydrogen.

No abstract