Visualisation and Thermovision of Fuel Combustion Affecting Heat Release to Reduce NO_x and PM Diesel Engine Emissions

Abstract

Research was conducted on fuels with additives that selectively affect the rate of kinetic (dQk/dα) and diffusion (dQd/dα) combustion in the diesel engine cylinder. In addition to the base fuel (DFB), DFKA fuel with an additive reducing dQk/dα, DFDA fuel with an additive increasing dQd/dα, and DFS fuel with both additives were tested. The main purpose of such dQ/dα course control in the engine cylinder was to simultaneously reduce the emissions of nitrogen oxides (NOx) and particulate matter (PM), and to increase the efficiency of the combustion process. Similar to the course of the dQ/dα, the course of the combustion temperature (Tc(α)) affects the NOx produced and the number of afterburned solid particles; the influence of the fuel additives on the functional curves was analysed. In addition to analysis of the temperature Tc(α) calculated from the indicator diagrams, Tc(α) analysis was conducted using the two-colour method, which allows the analysis of the isotherm distributions locally and temporarily. The two-colour method required prior endoscopic visualisation of the fast-changing processes inside the engine cylinder. Parameters defined by pressure, temperature, heat release rate, and visualisation and thermovision in the engine cylinder (as a function of the crank angle) allowed for an in-depth cause and effect analysis. It was determined why combustion of DFS fuel with both additives produced a synergy resulting in the simultaneous reduction in NOx and PM emissions in the exhaust gas and an increase in combustion efficiency. This publication relates to the field of Mechanical Engineering.

Keywords

• diesel engine
• fuel additives
• kinetic and diffusion combustion
• visualisation
• flame temperature
• two-colour method