Navegando por Autor "Santos, N. A."
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Artigo Rheology and MT-DSC studies of the flow properties of ethyl and methyl babassu biodiesel and blends(Springer, 2011-02-27) Bicudo, Tatiana de Campos; Santos, N. A.; Rosenhaim, R.; Dantas, M. B.; Cavalcanti, E. H. S.; Barro, A. K.; Santos, I. M. G.; Souza, A. G.Biodiesel is an increasingly attractive alternative to diesel fuel. The main component of Babassu biodiesel is lauric acid (C12:0), which is a saturated fatty acid with a high melting point. Controlling flow properties, such as viscosity and the cold filter plugging point, is critical because viscosity affects atomization, and crystal formation resulting from decreases in temperature can negatively affect engine starting and performance. To evaluate its flow characteristics more fully, the rheological properties of babassu biodiesel were analyzed, taking into account variations in temperature. The crystallization temperature was determined by modulated temperature differential scanning calorimetry (MT-DSC). The curve of biodiesel viscosity as a function of the biodiesel refrigeration temperature contained an inflection point (corresponding to a steep increase in viscosity) that was coincident with both the transition from a Newtonian-type flow to a pseudoplastic-type flow and the crystallization temperature obtained by MT-DSC, indicating that the appearance of crystals in the biodiesel increased its viscosity. The rheological properties of fatty acid methyl and ethyl mixtures (FAME and FAEE) with metropolitan diesel were also evaluated; a higher FAME percentage reduced viscosity in blends up to B100Artigo Themo-oxidative stability ald cold flow properties of babassu biodiesel by PDSC ans TMDSC techniques(Springer, 2009-04-27) Bicudo, Tatiana de Campos; Santos, N. A.; Santos, J. R. J.; Sinfrônio, F. S. M.; Santos, I. M. G.; Antoniosi Filho, N. R.; Fernandes Jr, V. J.; Souza, A. G.The babassu (Orbignya PhalerataMart.) biodiesel has lauric esters as main constituents, resulting in high oxidative stability and low cloud and freezing points. In order to reduce these side effects, the saturated ethyl esters content was reduced by means of winterization process. The TMDSC and PDSC techniques were used to verify the thermal and oxidative stabilities of the ethyl babassu biodiesel. During the heating stage, the winterized solid phase of ethyl esters presented an endothermic transition associated to the solidification process. This behavior was not observed for the liquid winterized FAEE, confirming the efficiency of the winterization process