Dual fuel combustion of 1-hexanol with diesel and biodiesel fuels in a diesel engine: An experimental investigation and multi criteria optimization using artificial neural network and TOPSIS algorithm

Abstract

The use of renewable biofuels namely higher alcohol and biodiesel in diesel engines under dual fuel combustion (DFC) mode gains importance because of reduced usage of diesel and enhanced performance and emission characteristics. In this DFC study, 1-hexanol (HX) is injected at various premixed energy ratio (PER) of 10%, 20% and 30% in the intake port, while diesel/waste cooking oil biodiesel is directly injected as in the conventional combustion mode (CCM). The experiments are carried out using diesel (D100), B20, B50 and B100 in CCM as well as DFC mode at various engine loads. The comparison between CCM and DFC reveals that the DFC mode with PER of 10% increases the BTE at all loads. The DFC decreased the NOx emission at lower loads and increased it at high loads, while a decline in smoke emission along with an increase in CO (except at rated load) and HC emission are observed at all the loads. A maximum reduction in NOx emission is observed from the DFC of diesel-1-hexanol by 37.81%, 26.68%, and 3.01% at 25, 50 and 75% loads respectively, while it increased by 13.3% at 100% load compared to its CCM. The required data set for the optimisation are predicted using an artificial neural network (ANN) model trained by the measured data with higher R2 values in the range of 0.993–0.996, 0.9892 and 0.985–0.996 for performance, combustion and emission parameters respectively. To optimise the fuel combination and the PER of 1-hexanol for an effective operation of DFC at various loads, a multi-objective decision-making optimization technique TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) is adopted. The optimal conditions in terms of overall improved performance and emission are the CCM of D100 for 25% and 50% loads and the DFC of B50 and B70 with 30% PER of 1-hexanol for 75% and 100% loads respectively. This concludes the ability of the DFC of renewable biofuels to diminish fossil diesel usage as well as harmful pollutants.