Experimental Investigation and RSM Modeling of the Effects of Injection Timing on the Performance and NOx Emissions of a Micro-Cogeneration Unit Fueled with Biodiesel Blends

The (partial or total) substitution of petro-diesel with biodiesel in internal combustion engines (ICEs) could represent a crucial path towards the decarbonization energy sector. However, critical aspects are related to controversial issue possible increase Nitrogen Oxides (NOx) emissions. In such framework, proposed study aims at investigating effects share and injection timing on performance NOx emissions diesel micro combined heat power (CHP) system. An experimental campaign has been conducted considering following operating conditions: (i) reference standard (17.2° BTDC), an early (20.8° late (12.2° BTDC); (ii) low (0.90 kW), partial (2.45 full (3.90 kW) output load; (iii) four fuel blends different (B) shares (B0, B15, B30, B100). Experimental data were also elaborated thanks response surface modelling (RSM) technique, aiming quantifying influences above-listed variables their trends responses, obtaining set predictive numerical models that basis for model-based design optimization procedures. results show: overall improvement engine due presence blend —in particular, B30 B100 have shown peak values both electrical (29%) thermal efficiency (42%); effective benefits SOI strategies emissions, quantified average reduction 27% early-to-late injection, 16% standard-to-late strategy. Moreover, it emerged NOx-reduction capabilities strategy decrease higher rates; through discussion high-prediction-capable, parametric, data-driven models, extensive RSM analysis how promotes whenever overcomes calculated threshold is proportional load (from about 66.5% 85.7% share).