Effects of Natural Gas Percentage on Performance and Emissions of a Natural Gas/Diesel Dual-Fuel Engine

Book chapter, 2015

Due to rising costs of conventional fossil fuels, and increasingly stringent limits on emissions (especially “greenhouse gases”), use of cleaner, cheaper gaseous fuels in internal combustion engines is expected to increase in the future. A popular application is the operation of heavy-duty diesel engines using combinations of compressed natural gas (CNG), supplied with the intake air and diesel injected to initiate combustion. Extensive efforts have already been made in both industry and academia to minimize pollutant emissions and maintain diesel-equivalent performance in this dual-fuel mode, but further knowledge of effects of fundamental parameters is required to optimize the combustion. Thus, this paper presents an experimental investigation of the influence of the CNG to diesel fuel ratio on the performance (effective expansion ratio, pressure and heat release rates) and emissions (HC, CO, NOx and CO2) from a CNG/diesel dual-fuel engine operating under varying load conditions but constant engine speed.