Enhancing CI engine performance and emissions through PCCI and sustainable combustion solutions with waste cooking oil biodiesel blends a comparative study

The limited availability of petroleum fuels and pollution concerns has led to the search for alternative energy sources. The most advantages of utilizing biodiesel are the simultaneous decrease of HC as well as CO emissions. Nevertheless, significant challenges remain, such as extreme NOx and smoke opacity emissions. To mitigate these issues, strategies like premixed charge compression ignition (PCCI) mode have been developed, which can lower NOx and smoke opacity levels. The novelty of the present study was establish to investigates the effects of various blends of waste cooking oil (WCO) biodiesel (B15D85, B30D70, B45D55, and B60D40) on combustion characteristics, emissions, and efficiency in conventional diesel combustion (CDC) and PCCI modes. In PCCI mode, a 20% premix ratio (PR) of diesel is vaporized outside the engine manifold, while the remaining fuel is burned conventionally before reaching TDC. Results reveal that in CDC mode, increasing the proportion of biodiesel in the blends led to decreased brake thermal efficiency (BTE), exhaust gas temperature (EGT), HC, and CO, while brake-specific energy consumption (BSEC), NOx, and smoke opacity increased. In contrast, PCCI mode demonstrated enhanced BTE alongside reductions in NOx and smoke opacity emissions due to the manifold enhancing the homogeneity of the mixture and decreasing combustion temperature. The B60D40 blend in PCCI mode achieved the lowest average NOx at 325 ppm and the minimum EGT at full load at 192 °C, along with reduced HC and CO emissions. While, B15D85 produced the lowest NOx and smoke opacity values, achieving the highest BTE of 34.6% and NOx emissions at 288 ppm in PCCI mode. Finally, using B60D40 PCCI showed BTE almost equal to diesel in CDC with extremely lower NOx and smoke emissions diesel.