Improving Flow Properties of Rapeseed-Based Biodiesel at Low Temperatures

Abstract

The cold flow properties of rapeseed-based biodiesel (RME) were studied by gas chromatography-mass spectrometry (GC-MS), multifunctional low temperature tester and thermal analysis. Two approaches for reducing cold filter plugging point (CFPP) of RME were investigated: blending with winter petrodiesel, treating with cold flow improver (CFI) additives and the effect of CFI to combustion characteristics of RME. A good correlation model was proposed for prediction CFPP by RME blending ratio. The study shows that the RME was mainly composed of fatty acid methyl esters (FAME): C14:0–C24:0, C16:1–C22:1, C18:2 and C18:3. The mass fraction of saturated fatty acid methyl esters (SFAME) and unsaturated fatty acid methyl esters (UFAME) was 14.69% and 83.40%, respectively. The CFPP of RME was -7 °C. Blending with -10 petrodiesel (-10PD) decreased the CFPP to -12 °C. Treating with CFI additives (volume fraction ≤ 1.5%) decreased the CFPP of RME and RME/-10PD to -11 and -28 °C, respectively. Small amount of CFI additives hardly affected combustion characteristics of biodiesel. This study has effectively improved cold flow properties of biodiesel and provided guide for using biodiesel at low temperatures.