A Taguchi-fuzzy based multi-objective optimization study on the soot-NOx-BTHE characteristics of an existing CI engine under dual fuel operation with hydrogen

The present energy situation and the concerns about global warming has stirred active research interest in non-conventional and alternative fuel resources to reduce the emission and the unabated fossil fuel dependency footprint, particularly for transportation, power generation and agricultural sectors. Among various alternatives, hydrogen has been extensively studied and concluded to be a viable and promising alternative fuel option on existing IC engine platforms in bridging the contemporary gap to the long term fuel cell based power train roadmap. Further, with the advent of EPA Tier 4 interim and final emission mandates the limits of the regulated emissions are challenging the practical limits of current engine design and calibration strategies. With a compliance directive of a substantial reduction in Soot and NOx emission levels simultaneously than its immediately preceding directives, engine manufacturers are being increasingly challenged to meet the paradox of curtailing particulate matter and NOx emissions on one hand and maintaining consumer expectations of increased thermal efficiency on the other. In this respect, various studies on the application of hydrogen as a dual fuel in existing IC engines offer the motivation to explore the potential in exploiting the inherent superior combustion characteristics of hydrogen as an in situ solution to the emission and performance trade-off challenges of conventional diesel combustion. In the present study, an experimental investigation was carried out existing CI engine with hydrogen as a dual fuel. A Timed Manifold Injection (TMI) system was adopted to analyze the effect of durations of hydrogen induced on the performance and emission characteristics as compared to baseline diesel operation. Previous studies have already clearly established the virtues of hydrogen in mitigating the emission footprint of conventional diesel operation along with improved performance characteristics. However, with the penalty of increased NOx emissions with hydrogen participation, a definite study specifically addressing the NOx-Soot-BTHE trade-off vantage achievable on existing CI engines under the purview of existing emission mandates is yet to be addressed. Based on an experimental investigation, the present study employs offline calibration techniques centered on the rationale of the fuzzy logic based Taguchi analysis to investigate the optimal soot-NOx-BTHE trade-off regime of operation based on different hydrogen injection strategies.