Research of the impact of EGR rate on energy and environmental parameters of compression ignition internal combustion engine fuelled by hydrogenated vegetable oil (HVO) and biobutanol - Castor oil fuel mixtures

The use of the second-generation biodiesel has become an increasing priority in the modern world, and adding a biobutanol additive further improves the engine's environmental characteristics. As biobutanol degrades lubri-cation characteristics of a fuel blend, HVO and biobutanol blends were supplemented with up to 5% castor oil in the research to form a three-component fuel blend. This blend increases NOx emissions in proportion to the increase of the biobutanol concentration in the fuel blend. The most widely used method of reducing NOx emissions in modern motorisation is the use of EGR. Therefore, this article analyses not only the impact of different EGR rates on both environmental and energy characteristics of the engine. Using various EGR rates with HVO and biobutanol mixtures, the rate of heat release (ROHR) in premixed combustion phase decreased, but in controlled combustion phase it increased in the convergence of its value to that of conventional diesel. A decrease in BTE values was also observed with HVO and biobutanol mixtures, increasing EGR rate. When increasing EGR rate of HVO and biobutanol, BSFC increased both in terms of volume and mass; Smoke, HC and NOx, CO and CO2 emissions also decrease with HVO and biobutanol mixtures compared with conventional diesel.