Effect of Isobutanol Addition on the Biodiesel Density

Abstract

Higher alcohols such as butanol isomers have received remarkable attention as alternative fuels for compression ignition engines because of their great potential as blending components in mixtures with biodiesel and diesel resulting in significant reduction in greenhouse gases and harmful pollutants. In this context, the influence of temperature and pressure on the density of used cooking oil biodiesel, 1-butanol, isobutanol, and biodiesel mixtures with different levels of isobutanol (0.0500, 0.0941, and 0.1397 by mass) was assessed over the temperature range of 298–343 K and pressures up to 30 MPa. For this purpose, a vibrating tube densimeter was calibrated using water and n-octane. The average expanded uncertainty of measured density at a confidence level of 0.95 (k = 2) was estimated to be 0.80 kg m–3. The densities of all the systems were represented by the Tait equation of state with AARD % (0.01–0.035%) including the results for the new Tait equation for the biodiesel + isobutanol blends. When isobutanol is added to biodiesel to form a 14% by mass of alcohol, the density of mixture decreases 11 kg.m–3. Thermal expansivity and isothermal compressibility increase with maximum deviations of 9.6 % and 7.8 % at 343 K and atmospheric pressure.

Density Measurements and PC-SAFT Modeling for Beef Tallow Fatty Acid Methyl Esters (FAME Mixture) + Alkane up to 70 MPa

“…Moreover, the density for the FAME mixture reported in this work was contrasted with those values for biodiesel fuels collected from the literature ,,,,, at 303 and 393 K, as shown in Figure S1. The highest density was observed for the beef tallow FAME mixture; it was related to the corresponding behavior for pure saturated fatty acid methyl esters.…”

“…Another remarkable characteristic is that the κ T magnitude occurred in the same range regardless of the different oil and fat feedstocks, ,,,− as depicted in Figure S3 at 303 and 393 K; these κ T values almost agreed in a single smooth curve as the temperature increases. Therefore, the changes in volumetric properties for saturated or unsaturated esters were almost insensitive to pressure changes at a constant temperature.…”

“…A distinctive performance was noticed on density values for the FAME mixture + alkane blend with a low content of alkane at about (x alkane ≈ 0.3), and the magnitude for this property seemed to be similar and the difference between both densities was within the experimental uncertainty for most of the data sets. Moreover, the density for the FAME mixture reported in this work was contrasted with those values for biodiesel fuels collected from the literature 26,28,29,31,32,34 at 303 and 393 K, as shown in Figure S1. The highest density was observed for the beef tallow FAME mixture; it was related to the corresponding behavior for pure saturated fatty acid methyl esters.…”

“…Experimental volumetric properties for different types of biodiesel and biodiesel blends have been reported in the literature. − Zhao et al have reported thermophysical properties for binary systems constituted by hexadecane + esters (methyl butyrate, methyl decanoate, ethyl hexanoate, and ethyl heptanoate). Ferreira et al measured densities for used cooking oil biodiesel up to 30 MPa in the interval of 298.41 to 343.23. Tat and Van Gerpen determined densities of 10 different first- and second-generation biodiesel fuels at temperatures from 293.15 to 373.15 K and pressures up to 32.5 MPa.…”

“…Decane and dodecane have been usually used as surrogates for fossil diesel since these are common components of fossil diesel; , the combustion characteristics for these alkanes have been widely studied, and dodecane has just about the same volatility and cetane number against fossil diesel . Experimental volumetric properties for different types of biodiesel and biodiesel blends have been reported in the literature. − Zhao et al have reported thermophysical properties for binary systems constituted by hexadecane + esters (methyl butyrate, methyl decanoate, ethyl hexanoate, and ethyl heptanoate). Ferreira et al measured densities for used cooking oil biodiesel up to 30 MPa in the interval of 298.41 to 343.23.…”