Densities and Viscosities of Minority Fatty Acid Methyl and Ethyl Esters Present in Biodiesel

Abstract

Biodiesels have several known components in their composition. The majority of components is well described in the literature, but a minority of components are poorly characterized. These are however required to develop reliable models to predict the biodiesel behavior. This work considers minor components of biodiesel: the polyunsaturated compounds (in C18), the monounsaturated (in C16, C20, and C22), and the long-chain saturated esters. In this work, densities and viscosities of pure fatty acid ester minor components of biodiesel fuel were measured (three ethyl esters and seven methyl esters), at atmospheric pressure and temperatures from (273.15 to 373.15) K. Correlations for the densities and viscosities with temperature are proposed. Three predictive models were evaluated in the prediction of densities and viscosities of the pure ethyl and methyl esters here reported. The GCVOL group contribution method is shown to be able to predict densities for these compounds within 1.5 %. The methods of Ceriani et al. (CM) and of Marrero et al. (MG) were applied to the viscosity data. The first show a better predictive capacity to provide a fair description of the viscosities of the minority esters here studied.

Correlation and prediction of biodiesel density for extended ranges of temperature and pressure

“…Pratas et al obtained A = À5.7 Â 10 À4 MPa À1 [36] by fitting Eq. (10) to high pressure densities for laurate, myristate, and oleate methyl esters, reported by Pratas et al [55,56]. The Eq.…”

“…With this extension (extended GCVOL) densities of tertiary alcohols, alkynes, carboxylic acids, allenes, cycloalkanes, fluorides, bromides, iodides, thiols, sulfides, sulfates, amines, nitriles, and nitro compounds were calculated with an average mean deviation of 1.5% for a database of 1040 compounds. Pratas et al [55,56] applied the original CGVOL to density prediction of pure FAMEs present in biodiesel in greater content, and those existing in minority. They concluded that for the majority FAMEs the density can be predicted within an ARD of 0.5%, except for the methyl linoleate since the model describes poorly the effect of unsaturation on density.…”

“…Pratas et al [36] also applied the original and the extended GCVOL models to 18 biodiesel samples of soy, rapeseed, palm, cottonseed, jatropha, and mixtures thereof at temperatures between 273.15 and 373.15 K and densities from 815 to 898 kg m À3 , and obtained overall ARDs of 0.6% and 2.7% for the original and the extended GCVOL, respectively. To solve the precision lack for the polyunsaturation ester effect, Pratas et al [36] found new parameter values A i , B i , and C i relative to the double bond (ACH@) contribution, based on density data measured for FAMEs [55,56]. This revised variant of GCVOL was applied to the 18 biodiesels leading to a decrease in the overall ARDs to 0.25% in density, corresponding to %2 kg m À3 [36].…”

Physiochemical and Phase Behaviour Study of Jatropha curcus Oil - Ethanol Microemulsion Fuels Using Sorbitane Fatty Esters

“…The two vertices at the bottom depict weight percent of JCO at left side and ethanol at right, while the upper vertex represents span. The composition at each point in diagram demonstrates weight percent of three components A, B, C as under [30].…”

“…For instance, the cetane number and gross heating values are directly related to density and affect fuel efficiency [26][27][28]. Similarly, viscosity is an important parameter for development of fuels that governs the engine operation [29][30]. Surface tension is one of the vital PCP that directly affects fuel atomization due to cohesive forces and hence the biodiesel with higher surface tension values hamper the correct fuel atomization on an engine combustion chamber due to difficulty in small fuel droplet formation [31].…”