Investigation of glycerol doping on ignition delay times and laminar burning velocities of gasoline and diesel fuel

Glycerol is a major by-product of biodiesel production. Per one tone of produced biodiesel, one hundred kilograms of glycerol is produced. Production of glycerol is increasing due to increase of demand for biodiesel. One of methods of glycerol utilization is combustion. Recent experimental studies with use of a diesel engine and a constant volume combustion chamber show that utilization of glycerol as a fuel results in lower NOx emissions in exhaust gases. It combusts slower than light fuel oil, what is explained by higher viscosity and density of glycerol. Glycerol has low cetane number, so to make combustion in a diesel engine possible at least one of the following conditions need to be fulfilled: a pilot injection, high temperature or high compression ratio. The aim of the paper is to compare glycerol to diesel and to assess influence of glycerol doping on gasoline and diesel fuel in dependence of pressure, temperature and equivalence ratio. The subject of this study is analysis of basic properties of flammable mixtures, such as ignition delay times and laminar burning velocities of primary reference fuels (diesel: n-heptane and gasoline: iso-octane). Calculations are performed with use of Cantera tool in Matlab and Python environments. Analyses of influence of glycerol on ignition delay times of n-heptane/air and iso-octane/air mixtures covered wide range of conditions: temperatures from 600 to 1600 K, pressure 10-200 bar, equivalence ratio 0.3 to 14, molar fraction of glycerol in fuel 0-1 in air. Simulations of LBV in air cover temperatures: 300 K and 500 K, pressures: 10, 40, 100, 200 bar and equivalence ratio from 0.3 to 1.9. Physicochemical properties of gasoline, diesel and glycerol are compared