Impact of fuel injection timing on engine characteristics of CRDi diesel engine with H 2 enrichment through RSM optimization

The current research investigates experimental and numerical optimization of key engine characteristics of a multifuel automotive CI engine blended with hydrogen fuel (10%–30% energy share) under variable pilot diesel injection timings (15–23°bTDC). Engine characteristics results were obtained as optimum and improved at optimal conditions, which is 30% hydrogen supplement with diesel (D+H 2 30%) and advanced fuel injection timing (23°bTDC) at full load (100%) compared to pure diesel. So, performance, combustion, and emission parameters were found, BTE maximum and improved by 7.5%, BSFC drops by 19.3% over pure diesel, and 20.28% diesel replaced by hydrogen, and ICP, HRR, and MRPR are enhanced by 26%, 25%, and 8.2% than pure diesel because of hydrogen enrichment, coupled with optimized injection timing, which enhances combustion efficiency due to improved flame speed and better air-fuel mixing, and CO, CO 2 , and HC are observed, attributed to cleaner and more complete combustion promoted by addition of hydrogen, which also reduced by 67%, 25%, and 34.48% but NO x climbed by 946.11 ppm compared to diesel due to higher in-cylinder temperatures associated with hydrogen-assisted combustion and advanced injection timing. Numerical analysis from optimization via CCD strategy under RSM is applied to model, and under optimized conditions optimum values were obtained, which are closely same as experimental condition, and residuals were found BTE, MRPR, improves by 1.07%, 1.39%, and BSFC, CO, CO 2 drop by 2.05%, 2.19%, 0.761%, but NO x rose by 1.10% from actual values. Combined Desirability is 0.8614, which means a good model for optimization.