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Liquid-liquid equilibrium data were measured and analyzed for two ternary systems (biodiesel + methanol + glycerol and methyl palmitate + methanol + glycerol). Biodiesel, produced by the conventional chemical route at 60 °C for 60 min, using methanol and soybean oil at a molar rate of 10:1 and potassium hydroxide concentration (KOH) of 1 wt% exhibited thermal decomposition at temperatures between 100 and 250 ºC, reaching mass loss of approximately 98.8%, confirming soybean oil conversion into biodiesel by gas chromatography and thermogravimetry. Tie line composition quality was verified using Othmer-Tobias and Hand correlation equations. The distribution and selectivity coefficients were calculated for the immiscibility regions. The experimental tie line data exhibited good correlation in the UNIQUAC and NRTL thermodynamic models. The biodiesel system displayed deviations of 0.66 and 0.53% for the UNIQUAC and NRTL models, respectively. In addition, the methyl palmitate system showed a 1.23 and 0.48% deviation for the UNIQUAC and NRTL model, respectively. The individual behavior of the main biodiesel esters, based on the UNIQUAC model parameters, demonstrated that the type of fatty acid does not interfere in model correlation, likely due to the similarity between their composition and properties. [ABSTRACT FROM AUTHOR]

The sound generated by axial flow fans has become increasingly important in several industrial areas. These devices represent considerable noise sources that must be considered from the design stage. The scope of this research work is to present an axial fan design methodology based on the theory of the wing lift and to compare the aerodynamic and aeroacoustics behavior with the free vortex and the non-free vortex conditions. The effect of forward circumferential sweep on the rotor blades is analyzed in both conditions, which consists of a displacement in the tangential direction in the direction of rotor rotation. A cubic polynomial function is proposed for the construction of the blade geometry with circumferential sweep. It defines the center line of the blade and it is taken at 50% of the leading edge of each blade profile. The methodology for analyzing aeroacoustics behavior in fans is based on the integration of Computational Aeroacoustics and Computational Fluid Dynamics in order to analyze aerodynamic behavior, sound power level and sound pressure level at the preliminary design stage. It was verified that although both rotors present a similar aerodynamic behavior (the NFV rotor has a slightly lower performance), according to the analysis of local sound sources, the NFV rotor presents a slight decrease in the sound sources. It was also verified that the NFV rotor presents 2.2 dB less in sound pressure level than the FV rotor. [ABSTRACT FROM AUTHOR]

The draft tube is one of the main components that integrate a turbine, since it has the function of recovering the residual kinetic energy after the runner by the pressure energy. The search for a draft tube design that increases the efficiency of the turbine is always an engineering challenge. The hydromechanics components geometry optimization can be accomplished through the integration of optimization methods and CFD tools. In this work, the geometric optimization of a double diffuser draft tube of a Bulb turbine applied to ultra-low heads is presented, with the objectives of maximizing the pressure recovery coefficient, Cp, and increasing the hydraulic efficiency of the turbine, ηh. These improvements would make it possible to reduce the longitudinal length of the draft tube, thereby, making an easier insertion of this kind of turbines in water transport systems, with pressures around 3 [mH2O]. The optimization methodology was performed in the meridional plane, using twelve geometric variables in the draft tube through the integration of optimization methods and computational fluid dynamics. The optimized geometry obtained showed an increase in the Cp value of 0.71516, from the original geometry, to 0.83080. The results were extended to the 3D flow analysis, where the optimized turbine showed efficiency gains of 82% to 84%, when compared to the original turbine considering that its total length was reduced and its geometry simplified, resulting in a more compact and versatile equipment. The study also concluded that the applied methodology can be extended to other similar optimization problems in the design of hydraulic machines. [ABSTRACT FROM AUTHOR]