Biodiesel fuel flow property

However, one of the limitations of using biodiesel fuel for diesel engines is higher cold flow properties compared with petroleum diesel fuel (4). Cold properties consist of cloud point, pour point, and cold filter plugging point. The cloud point is a temperature at which the fuel starts to thicken and cloud, the pour point is a temperature at which the fuel thickens and no longer pours, and the cold filter plugging point is the lowest temperature at which fuel still flows through a specific filter. These... 

Despite its many advantages as a renewable alternative fuel, biodiesel presents a number of problems that must be resolved for it to be attractive for more widespread applications. These problems include improving relatively poor cold flow properties, monitoring and maintaining fuel quality... 

Waynick, J. A. 1997. Evaluation of the Stability, Lubricity, and Cold Flow Properties of Biodiesel Fuel. In Proc., 6th International Conference on Stability and Handling of Liquid Fuels. Atlanta GA IASH. 

Fatty acid methyl esters and other esters of fatty acids and a lower alcohol can be added at a low ratio to most diesel fuels without substantially changing fuel characteristics. It has been reported that in blends containing 30 percent biodiesel, low-temperature flow properties are not greatly affected (12), but at higher blend levels, the properties of the methyl ester may affect the properties of the fuel. With few exceptions, pure biodiesel does not meet minimum low-temperature requirements and may exceed manufacturers maximum viscosity for diesel fuels. 

Dr Adam Harvey at Newcastle University (Harvey, 2006) is examining the use of oscillatory baffle reactors as components to intensify the production of biodiesel fuels. The research at Newcastle University uses rapeseed oil as the feedstock, the atfiaction being generally that it is a renewable energy source, it reduces CO2 emissions and pollution and it attracts tax relief in the UK at present. The range of PI projects in this area include a portable plant, solid catalysts (which allow a reduced number of process steps compared to liquid catalysts), the development of a reactive extraction process direct from the oilseeds, examination of cold flow properties and the production of biodiesel from algae. 

Esters of levulinic acid produced from either methanol or ethanol are under active development as blend components in diesel formulations. These esters are similar to the biodiesel fatty acid methyl esters (FAME) now used in European low emission diesel formulations. FAME has certain disadvantages as automotive fuel components in diesel due to cold flow properties (24) and gum... 

Fatty acid stmcture (composition and imsaturation degree) of vegetable oils used as feedstocks considerably affect the physical properties of biodiesel such as viscosity, cold flow properties, oxidation stability and exhaust emission profile (Knothe 2008). Even, there are many successful attempts to predict the biodiesel properties from the fatty acid composition of the plant oils. Fatty acid distribution of some common vegetable oils is given in Table 2. Higher saturated fatty acid based biodiesel has higher viscosity, cold flow temperatures, oxidation stability and calorific value while higher imsaturated fatty acid based biodiesel shows a combination of improved fuel properties as a whole (Knothe 2005 Ramos 2009 Kumar 2013). 

Abstract Thermal analytical methods such as differential scanning calorimetry (DSC) have been successfully applied to neat petrodiesel and engine oils in the last 25 years. This chapter shows how DSC and P-DSC (pressurized DSC) techniques can be used to compare, characterize, and predict some properties of alternative non-petroleum fuels, such as cold flow behavior and oxidative stability. These two properties are extremely important with respect to the operability, transport, and long-term storage of biodiesel fuel. It is shown that the quantity of unsaturated fatty acids in the fuel composition has an important impact on both properties. In addition, it is shown that the impact of fuel additives on the oxidative stability or the cold flow behavior of biodiesel can be studied by means of DSC and P-DSC techniques. Thermomicroscopy can also be used to study the cold flow behavior of biodiesel, giving information on the size and the morphology of crystals formed at low temperature. 

Palm oil methyl ester presents an onset of crystallization above 0 °C (i.e. 6 °C) and a steep crystallization slope (Fig. 13.3a). Thus, its cold flow properties will be poorer than those of the rapeseed methyl ester. The crystallized fractions (CFs) determined at -15 °C for MEl, ME2 and DF are 2.3,1.5 and 25.9%, respectively. These percentages were calculated using the enthalpy of crystallization of DF (210 J/g) obtained elsewhere [9]. The same linear relation obtained for diesel fuels has been used for biodiesel and biodiesel blends ... 

The cold flow properties of diesel fuel and biodiesel blends are given in Table 13.4. As can be seen from these results, there is almost no influence when ME2 is blended with DF. This situation changes when MEl is blended with DF, where the quantity of precipitated crystals and the cold flow parameters are higher than those of neat DF and increase when MEl is increased from 10 to 30%. As was expected after the analyses of the pure compounds, blends of MEl with DF have lower cold flow parameters compared with blends of ME2 with DF. 

Although biodiesel is an excellent source of fuel, it has some disadvantages which include relatively poor cold flow properties and dilficulty in maintaining fuel quality during long-term storage. The latter is a matter of oxidation stability and will be discussed in this part. 

The properties of a biodiesel fuel that are determined by the structure of its component fatty esters include ignition quality, cold flow, oxidative stability, viscosity, and lubricity. The present work discusses the influence of the structure of fatty esters on these properties. Not all of these properties have been included in biodiesel standards, although all of them are essential to the proper functioning of the fuel. This article begins, however, with brief summaries on the historical background, production, and analysis of biodiesel. 

Besides CP (ASTM D2500) and PP (ASTM D97), two test methods for the low-temperature flow properties of conventional DF exist, namely the low-temperature flow test (LTFT used in North America ASTM D4539), and cold filter plugging point (CFPP used outside North America for example the European standard EN 116) (CEN). These methods have also been used to evaluate biodiesel and its blends with No. 1 and No. 2 conventional DF. Low-temperature filterability tests were stated to be necessary because of better correlation with operability tests than CP or PP (Owen and Coley, 1995). However, for fuel formulations containing at least 10 vol% methyl esters, both LTFT and CFPP are linear functions of CP (Dunn and Bagby, 1995). Additional statistical analysis showed a strong 1 1 correlation between LTFT and CP (Dunn and Bagby, 1995). 

Adapted from Joshi, R.M., Pegg, M.J., 2007. Flow properties of biodiesel fuel blends at low temperatures. Fuel 86 (1—2), 143—151. Available at http //www.sciencedirect.eom/science/article/pii/S0016236106002122 (accessed 26.08.15.) with permission from Elsevier. 

Another important fuel property is viscosity, which measures the fuel s flow resistance. Higher viscosity lowers the performance, as is the case with the direct use of vegetable oils. In addition, biodiesel is subjected to oxidation, which might lead... 

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