Biofuels - Experimental study of liquid-liquid equilibrium and performance evaluation in a diesel cycle engine
biodiesel, liquid-liquid equilibrium, UNIQUAC, NRTL, diesel, alcohols, diesel engine
The production and indiscriminate use of fossil fuels should decline in the coming decades due to global warming caused by greenhouse gas emissions, which lead to serious climatic disorder. Diversification of the global energy matrix has broadened and strengthened renewable energies and biofuels aimed at combining energy safety with sustainable development. Biodiesel is a feasible alternative to diesel owing to its similar properties and applications, without requiring changes to internal combustion engine. It is superior to fossil fuels because of its biodegradable, sustainable and environmentally friendly nature. This work presents the production of methyl biodiesel using commercial soybean oil in a homogeneous route with potassium hydroxide (KOH) in order to obtain liquid-liquid balance (ELL) data and its applicability in a diesel cycle engine. Initially, a comparison of equilibrium diagrams and an evaluation of thermodynamic models were evaluated between biodiesel (biodiesel + glycerol + methanol) and methyl palmitate, an ester isolated from biodiesel (methyl palmitate + glycerol + methanol). The results showed a good correlation with the UNIQUAC and NRTL models, in addition to showing a diagram with an extensive biphasic region. In order to propose new biofuel formulations, ELL studies in ternary systems were carried out containing Alcohols + Biodiesel + Diesel, focusing on the use of biodiesel as a stabilizing additive for alcohols in diesel mixtures, in other words, the miscibility of ternary systems was investigated . The authenticity of the phase equilibrium data was validated by the Othmer-Tobias and Hand equations. The distribution and selectivity coefficients calculated for the immiscibility regions indicated that the increase in the carbon chain strengthens the biodiesel solubility. The experimental data also correlated with the UNIQUAC and NRTL thermodynamic models. Both models showed high agreement with the experimental data, with deviation values (RMSD) lower than 1.78%. Finally, a diesel engine fed with biodiesel/methanol/n-butanol blended fuel was employed to investigate the effects of different fuel blend ratios and engine load on combustion characteristics in terms of specific fuel consumption and efficiency. brake heat. Two 2³ experimental designs with the addition of three central points were carried out, evaluating the effect of the variables, concentration of additives (methanol and n-butanol), molar ratio (B/M) and potency. Load is the main factor affecting the specific fuel consumption and thermal efficiency of the brake.