Enhancement of engine characteristics through zirconium nano particle addition and split injection parameter optimization for the adaptability of eucalyptus biofuel in diesel engine

[Display omitted] •Biofuel blend along with nanoparticle is optimized and calibrated for CRDI engine operation.•Engine parameters are optimized using CCD, RSM, ANOVA and desirability test.•Lower emission levels of CO, HC and smoke are achieved using biofuel blend.•Most desirable condition obtained is 40% of EL, 500 bar of FIP, 21% of PM, 16° DT, and 28° PT bTDC.•Enhanced performance and minimized emissions are achieved by the addition of ZrO2 nanoparticle. The ever-growing demand for fuel sources, the rising prices of gasoline and diesel, and the harmful exhaust gases in the atmosphere are a few of the many reasons why biofuels need to be utilized. The use of eucalyptus oil as biodiesel in compression ignition (CI) engines shows promising results under numerous conditions, with properties such as high volatility and low viscosity and it innately emits lesser emissions during combustion. In a fully accelerated engine setup, key factors such as the performance and emissions of the engine are optimized using statistical techniques. The research involves a structured approach to investigating the capability of a 20% volumetric blend of eucalyptus oil (Eu20) mixed in diesel and is compared with a diesel under commensurable conditions. The ordered experimentations are performed on a common rail direct injection (CRDi) engine setup using the central composite design (CCD) along with Response Surface Methodology and desirability tests for easier calibration. All the optimal engine inputs are obtained from the developed multivariate regression model. Interaction effects are employed to identify the most influential factor through monitoring the interaction of two specific input factors on a single response. From the desirability tests, predicted with the highest desirability of 0.974, the optimal responses recorded are brake thermal efficiency (BTE) of 16.766%, brake specific fuel consumption (BSFC) of 0.516 kg/kW-hr, carbon monoxide (CO) of 0.17%, hydrocarbon (HC) of 16.22 ppm and oxides of nitrogen (NOx) of 77.565 ppm. Moreover, confirmatory tests are performed on the engine with responses having an error below 8%. From this experimentation, it has been found that the heating value of eucalyptus oil leads to lower BTE and higher fuel consumption rate even after the optimization. So that, to enhance the performance characteristics of the engine, the zirconium oxide (ZrO2) nanoparticles are mixed with the Eu20 at 50 and 100 ppm concentrations. While testing for the