Browsing by Author "Rodriguez Pascual, Marcos"

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    Effect of Operating Conditions on Ice Characteristics in Continuous Eutectic Freeze Crystallization
    (Wiley-VCH Verlag, 2014) Chivavava, Jemitias; Rodriguez Pascual, Marcos; Lewis, Alison Emslie
    The efficacy of eutectic freeze crystallization (EFC) in crystallizers and in subsequent downstream washing or filtration steps is a direct function of size and morphology of the crystalline products. These product characteristics are influenced by supersaturation and residence time. To investigate the effect of residence time and supercooling on ice product characteristics in a continuous EFC process, crystallization experiments were performed in an EFC crystallizer with Na2SO4 aqueous solution. Crystal size distribution and morphology during the crystallization process were analyzed by digital image processing. Longer residence times enhanced the mean crystal size and disk-shaped ice crystals were formed. Increasing supercooling resulted in a larger mean ice equivalent diameter.
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    In Situ Growth Measurements of Sodium Sulfate during Cooling Crystallization
    (Wiley-VCH Verlag, 2014) Egan, Timothy; Rodriguez Pascual, Marcos; Lewis, Alison Emslie
    Combined rainbow Schlieren deflectometry (RSD) and liquid crystal thermography (LCT) served as in situ non-intrusive techniques to determine local concentration and temperature fields based on refractive index gradients in solution during crystallization of sodium sulfate from aqueous solution. The combination of RSD with LCT allowed the decoupling of concentration and temperature effects. Convective mass transport happened during periods of fast, dendritic growth, but even higher levels occurred during the densification of the dendritic crystals, indicating significant mass deposition in this phase. The convection developed mainly as a result of concentration gradients as opposed to temperature gradients. A supersaturation field map was generated and growth kinetics of the sodium sulfate salt was determined. The kinetics followed a power law relationship, with constants in line with those in the literature.