Influence of Natural Gas Composition on Turbocharged Stoichiometric SI Engine Performance

摘要

In certain applications, the use of natural gas can be beneficial when compared to conventional road transportation fuels. Benefits include fuel diversification and CO_2 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.