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Title: Molecular-scale effects of additives on the nucleation, growth and crystal properties of long-chain alkyl methyl-esters
Author: Jiang, Haiyang
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2012
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Biodiesel is a diesel-related fuel manufactured from vegetable oils, recycled grease, or animal fats. It is technically competitive with, or offers technical advantages when compared to, conventional diesel fuel. However, the freezing and gelling behaviour of many biodiesel formulations are potentially limiting their applications. It is known that the use of additives is an efficient way to improve the cold flow properties of formulated, so it is very important to clarify the mechanism and effect of additives. Molecular cluster modelling work has been explored to study the effect of additives on crystallization temperature, meta-stable zone width and solubility. A new method has been developed for the prediction of crystallisability through the comparison of structural variability of molecular clusters of pure naphthalene, pure biphenyl, and naphthalene in the presence of biphenyl and vice versa. The approach has been validated through the experimental determination of crystallization temperatures and meta-stable zone width. The predicted growth morphologies of methyl stearate have been derived through attachment energy calculations and the resulting surface chemistry of the morphological habit faces characterized. Molecular simulations using grid search methods combined with experimental observed images were used to investigate the solvent-mediated effect on crystal habits of methyl stearate. Tubidometric studies employing a 100ml batch crystallizer operating in a polythermal mode confirmed the change of crystallization temperature and the meta-stable zone width of methyl stearate with or without additives. Related crash-cooling studies enabled the characterization of crystallization kinetics with or without additives through examination of set paints as a function of supersaturation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available