Overall Performance Investigation and Optimization of a Multi-fuel Operated Compression Ignition Engine Using Coupled Taguchi and Grey Relational Analysis

[Image: see text] Biofuels are regarded as the best diesel fuel substitute due to their low sulfur concentration, reduced aromatic hydrocarbon content, renewable nature, and higher oxygen content. In this research article, the impact of producer gas, Calophyllum inophyllum oil, diesel, and a blend of C. inophyllum–producer gas fuel on a variable compression ratio (VCR) compression ignition (CI) engine, and the performance and emission parameters are evaluated. Several test runs are undertaken at a constant speed of 1500 rpm to predict the performance and emission characteristics of the test engine by changing input parameters such as engine load, CR, and fuel mode of operation. The brake thermal efficiency, BTE, is considered the performance characteristic, and CO, HC, NO(X), and opacity are considered the emission characteristics for the present study. The biofuel, or producer gas, employed in this study is prepared from waste biomasses, such as leaves, small tree branches, vegetable waste, and cow dung, aiding waste management for a sustainable environment. In addition, a coupled Taguchi–Grey relational analysis technique is used to predict the best possible combination of control factors for optimizing the overall output responses. 12 kg load, a CR of 18, and diesel fuel are found to be the optimum input parameters of an engine toward optimum performance. A confirmation test is performed at the end to validate the outcome of the experiment. An enhancement in performance of 22.75% is observed with the considered Grey relational grade model.