Optimizing diesel engine performance with nanoparticle-biodiesel blends: a hybrid priority machine learning and multi-criteria decision-making approach

• Study evaluated thirty nanoparticle–biodiesel blends for diesel engine performance. • Employed k-means clustering with MEREC-TOPSIS for optimal nanoparticle selection. • Diesel engine showed improved BTE, reduced BSFC, CO, NOx, UBHC, vibration, and noise. • Aluminium oxide ranked highest with TOPSIS CCi score of 1.000. Nanoparticles blended biodiesel fuels hold significant promise in improving performance of the diesel engine. However, selection of the most suitable nanoparticle to be blended with the biodiesel to achieve enhanced performance of the engine remains a subject of investigation. Consequently, this study has been conducted with an aim to identify the optimum nanoparticle that results in the optimal performance of the diesel engine. Different nanoparticle-biodiesel blends have been prepared and used in a diesel engine for experimental investigations. Output parameters of the diesel engine including brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), carbon mono oxide (CO), nitrogen oxide (NOx), unburnt hydrocarbon (UBHC), vibration and noise have been measured. A novel hybrid approach comprising of k-means machine learning (ML) clustering and multi criteria decision making (MCDM) methods have been used to analyse the experimental results so as to select the optimum nanoparticles. k-means clustering method has been used to group the nanoparticles in the best, the worst and the average clusters while MCDM aids in ranking the top five nanoparticles. Results reveal that CO and BSFC, with weights of 24.7% and 22%, are the highest priority output parameters, respectively. Conversely, BTE and Noise, with weights of 6.3% and 1.3% are the lowest priority output parameters, respectively. Further, aluminium oxide nanoparticle is found to be the optimum one as its rank is 1. Findings of the present study may help the decision makers to deduce well-informed decisions pertaining to the use of more efficient and environmentally friendly nanoparticle-biodiesel blends to achieve sustainable transportation solutions.