Taguchi-based optimization of design and fuel parameters of partially premixed charge CI engine fuelled with biodiesel and butanol blends

Simultaneous control of NOx and smoke emission of compression ignition engine was the major challenge for the researchers as their formation mechanisms are inversely proportional to each other. In the present study, combustion process was modified as partially premixed charge combustion (PPCC) which supplies a premixed charge of fuel and air through inlet valve in addition to the fuel injected into the cylinder. This resulted in reduction of combustion temperature with lean air fuel ratio. To investigate the influence of various factors on these emissions, six design factors and two fuel factors of the engine were selected as factors and NOx, smoke, and brake thermal efficiency were selected as responses for the investigation. Experimental test matrix was designed based on Taguchi L-18 orthogonal array. Multi response Signal to Noise (MRSN) ratio was calculated for the response variables and the optimum combination level of factors was obtained simultaneously using Taguchi's parametric design and the same was tested experimentally. Influence of each factor and most influencing factor on the chosen objective was determined by analyzing the variance of the MRSN ratio. This investigation reveals that among the factors tested, main injection fuel is the most influencing factor with a maximum percentage contribution of 44.5. It has been observed that normal combustion mode parameters have more influence with a percentage of contribution of 80 when compared with the parameters of PPCC mode. It has also been observed that fuel factors have higher percentage contribution of 53 compared with the design factors contribution of 43.6.

Automated summary

The study focused on simultaneously controlling NOx and smoke emissions of compression ignition engines by modifying the combustion process to partially premixed charge combustion (PPCC). Experimental results showed that the main injection fuel is the most influencing factor on emissions, while normal combustion mode parameters have a greater impact on combustion efficiency. Additionally, fuel factors were found to have a higher contribution to emissions compared to design factors.