Biofuels properties


N. De Lima Da Silva1, M. Wolf Maciel1 and R. Maciel Filho1

1School of Chemical Engineer, State University of Campinas (UNICAMP), Brazil

Keywords: biodiesel, density, viscosity, heat capacitiesl, enthalpy
property: density, viscosity, heat capacitiesl, enthalpy
material: biodiesel, vegetable oils

The physicochemical properties of biodiesel such as density, viscosity, heat capacity and enthalpy may influence the combustion and exhaustive emission. This work presents a comparative study of heat capacities, enthalpy, density, viscosity, and iodine value of biodiesel from six raw materials. The biodiesel were made using bioethanol and sodium hydroxide as catalyst in laboratory scale. The raw materials used were crude soybean oil, castor oil, palm oil, animal fat, waste frying oil, and coconut oil. The heat capacities and enthalpies were measured in the temperature range from 283 to 423 K. The density and viscosity were determined at 313 K (40 °C) and a rheological study of the viscosity variation with the temperature were presented. These properties are very important to design and to define operating strategies for industrial plants of biodiesel with desired properties and required equipments and systems for industrial plants of biodiesel. The results show an increase of the viscosity with the density. It is in agreement with Dermirbas [1] and it is influenced by the original crude oil. The viscosity variation from castor oil, frying oil, animal fats and crude soybean oil were according to exponential decrease, it is in agreement with Wang [2] for Newtonian fluids. The results show that the biodiesel properties are influenced by the original raw materials. The biodiesel viscosity decreases as temperature increases, according to Goodrum [3]; this is attributed to a reduction in cohesive forces between the molecules in the liquid as temperature increases. The determination of iodine value is important because the unsaturation can lead to deposit formation and storage stability problems with fuel. In this study, only the frying oil biodiesel had an iodine value larger than the Europe specifications.

References
  1. Dermirbas A. Fuel 87, 1743-1748 (2007).

  2. Wang T., Briggs J.L., JAOCS 79, 831-836 (2002).

  3. Goodrum J. W., Geller D. P., and Adams T.T., JAOCS 79, 961-964 (2002).

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