Prediction of the Cold Flow Properties in Biodiesel Blends

Abstract

The chemical compositions of biodiesel are analyzed by GC-MS, and their molecular structures are investigated on the basis of the hybrid orbital theory. The CFPP of biodiesel is studied by CFPP tester, the solution crystallization theory and the similarity-intermiscibility principle. Good correlation models are proposed for predict CFPP of biodiesel by chemical compositions and the CFPP of biodiesel-petrodiesel blends by biodiesel ratio. The study shows that biodiesel is mainly composed of SFAME (C14:0～C24:0) and UFAME (C16:1～C22:1, C18:2 and C18:3 ). Carbon atoms of the alkyl for SFAME arrange in a zigzag pattern by ∠CCC=109.5°. C-C carbon atoms of the alkenyl arrange in a zigzag pattern by ∠CCC=109.5°, too, carbon chain is curved by C=C in ∠CCC=122.0°, and curved degree increases with increasing unsaturated degree. CFPP of biodiesel is mainly determined by chemical compositions. CFPP increases with the amount and carbon chain length of SFAME. CFPP of biodiesel-petrodiesel blends is mainly determined by chemical compositions and ratio of biodiesel. To lower SFAME≥C20:0 biodiesel, such as PME, CSME, WME, SBME and RME, it blending with -10PD can formed a eutectic mixture. CFPP of the eutectic mixture is -12 °C. The biodiesel ratio for the lowest CFPP rang increases with decreasing SFAME. Such as SFAME contents in PME, CSME, WME, SBME and RME are 35.86、32.12、31.04、18.29 and 14.69 w% respectively, and the range of biodiesel ratio is 5～20、10～20、20～30、30～50 and 40～60 v% respectively. To higher SFAME≥C20:0 biodiesel, such as PNME, CFPP increases with PNME ratio.

Rapid Models for Predicting the Low‐Temperature Behavior of Diesel

“…A particularly important element of this assessment is the composition of the hydrocarbon chain; namely, the relationship between fatty acid (FA) content [13][14][15][16][17] and unsaturated FA content [18]. Advanced methods can also be used for CFPP prediction [5,7,19]. GC-MS was employed to predict the CFPP by chemical composition based on the hybrid orbital theory [19].…”

“…Advanced methods can also be used for CFPP prediction [5,7,19]. GC-MS was employed to predict the CFPP by chemical composition based on the hybrid orbital theory [19]. Near- [5] or mid-infrared [7] spectra were also applied to predict the CFPP values of biodiesel and its blends with a high degree of repeatability.…”

“…Most of the above-mentioned models have only been selected for predicting the CFPP of final biodiesel, and the CFPP values reported are relatively high. Furthermore, the temperature range of these models is not as wide as it needs to be: [19]. In addition, the average absolute deviation is usually around 1°C, but Wu et al report a deviation of 4°C in the case of their CFPP value for 24°C, which, thus far, is the lowest temperature at which CFPP has been tested [4].…”