Finansavimas

Simulation model of the four-cylinder diesel engine operated on microalgal oil and intended to analyze variation of in-cylinder process parameters (pressure, pressure rise rate, temperature, temperature rise rate, and heat release rate) was created in AVL Boost v2018. These combustion-related parameters in the combustion model were updated every crank degree while the break mean effective pressure and air-to-fuel ratio was updated once every engine cycle. The following conclusions can be drawn:1) At the end of the compression process of a diesel engine microalgal oil demonstrated higher values of in-cylinder pressure and in-cylinder temperature in comparison to diesel fuel that could be explained by: (i) the longer phase of combustion which predetermines better fuel efficiency, (ii) higher values of in-cylinder pressure and in-cylinder temperature facilitate the ignition (heats the unburned portion of the charge) and shortens the delay before its ignition. 2) Due to higher density and lower energy content, microalgal oil distinguishes for a longer injection duration compared to diesel fuel that predetermines higher values of heat release rate during the mixing controlled combustion phase what, at the same time, positively influences better burn out of the solid particles and the overall decrease in smoke opacity. 3) Results revealed that the exhaust gas recirculation (EGR) system reduces the in-cylinder temperature that can be explained by the following facts: (i) filling the cylinders with fresh air was reduced as EGR valve recirculating part of the exhaust gas back to combustion chamber, (ii) formation of richer mixture (lower air-fuel ratio) led to decrease in heat release rate during the premixed combustion phase followed by sudden increase during the mixing controlled combustion phase, (iii) lower heat release rate, in-cylinder temperature and air-fuel ratio acted in favor of NOx reduction as well as prevented the formation of this harmful compound.