In certain applications, the use of natural gas can be
beneficial when compared to conventional road transportation fuels.
Benefits include fuel diversification and CO₂ reduction, allowing
future emissions regulations to be met. The use of natural gas in
vehicles will also help to prepare the fuel and service
infrastructure for future transition to gaseous renewable
fuels.
The composition of natural gas varies depending on its source,
and engine manufacturers must be able to account for these
differences. In order to achieve highly fuel flexible engines, the
influence of fuel composition on engine properties must first be
assessed. This demand is especially important for engines with high
power densities.
This paper summarizes knowledge acquired from engine dynamometer
tests for different compositions of natural gas. Various levels of
hydrocarbons and hydrogen in a mixture with methane have been
tested at full load and various engine speeds. The experiments have
been performed on a light-duty turbocharged stoichiometric
spark-ignited truck engine with a wastegate turbocharger and cooled
exhaust gas recirculation. Stoichiometric (closed loop controlled)
engine operation was chosen for all experiments with the aim of
achieving maximum engine power output. Engine response to fuel
quality variations is presented in a form of plots of constant
combustion phasing and constant knock intensity.