Browsing by Author "Ouda, Alaa"
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Item Open Access Data supporting "Modifying supersaturation rate with membrane area can minimise scaling and improve control over crystal growth in membrane distillation crystallisation"(Cranfield University, 2023-06-30 11:09) Ouda, Alaa; McAdam, Ewan; Bajón fernández, YadiraThis Excel file consists of the data used to generate the figures in this paper. Each figure is placed in a separate Excel sheet while the formatting of the figures was consistent with a Word file.Item Open Access Methods to modify supersaturation rate in membrane distillation crystallisation: control of nucleation and crystal growth kinetics (including scaling)(Cranfield University, 2023-12-08 10:26) Ouda, Alaa; Bajón fernández, Yadira; McAdam, EwanThe attached Excel dataset consists of figure and table data used in this chapter. Each figure/table is placed in a separate Excel sheet while the formatting of the figures was consistent with a Word file.Item Open Access Methods to modify supersaturation rate in membrane distillation crystallisation: control of nucleation and crystal growth kinetics (including scaling)(Elsevier, 2023-11-10) Ouda, Alaa; Bajón Fernández, Yadira; McAdam, EwanWhile water vapour flux is often regarded as the critical parameter in membrane distillation crystallisation (MDC), there are multiple factors that will determine the kinetics of nucleation and crystal growth. A Nývlt-like equation is therefore introduced that can relate how multiple conditional parameters (membrane area, flux, temperature difference, crystalliser volume, magma density) independently modify nucleation rate and supersaturation, enabling a normalising approach for the characterisation of nucleation and crystal growth kinetics within MDC. Each parameter can be modified to increase supersaturation rate, which reduced induction time and broadened the metastable zone width (MSZW) at induction. An increase in supersaturation mitigated scaling and favoured bulk nucleation. This is due to the increase in volume free energy provided by the elevated supersaturation that reduces the critical energy requirement for nucleation to favour a homogeneous primary nucleation mechanism. An increase in temperature difference or magma density narrowed the MSZW. For each parameter, either supersaturation rate, supersaturation or induction time were fixed, while the other two factors were amended. While higher supersaturation rates generally favoured larger crystal sizes with broader size distributions, a high level of supersaturation at a low supersaturation rate increased particle size and narrowed the size distribution. In practice, these factors may be applied collectively and synergistically to deliver strict control over crystal growth, which remains a challenge for current evaporative technology. This was illustrated when facilitating an increase in supersaturation rate with membrane area, where an identical nucleation order was identified between membrane systems, from which it can be implied that MDC affords an inherently scalable solution for crystallisation.Item Open Access Modifying supersaturation rate with membrane area to volume ratio: scaling reduction and improved crystal growth control in membrane distillation crystallisation(Elsevier, 2023-06-13) Ouda, Alaa; Bajón Fernández, Yadira; McAdam, EwanThis study provides detailed characterisation of nucleation kinetics, induction time and supersaturation to understand scaling and crystal growth in membrane distillation crystallisation. Membrane area was used to moderate supersaturation rate, as a method to transition across the metastable zone without modifying boundary layer conditions. Increasing membrane area sustained the same water vapour flux but increased supersaturation rate within the crystallising solution (sodium chloride). This reduced induction time and increased the supersaturation level at induction. Membrane scaling was minimised by increasing supersaturation rate despite an increase in nucleation rate. This conforms with classical nucleation theory but contradicts membrane distillation crystallisation literature, where elevated supersaturation is often linked to advanced scaling. The transition from heterogeneous to homogeneous nucleation was evidenced once greater supersaturation at induction was achieved. The probability for scaling within the low supersaturation domain was confirmed through diagnostic investigation of the scaling deposit formed, and the growth mechanism within the scaling layer related to the relevant supersaturation region. Crystal size and morphology were also related to the metastable region, where membrane-to-volume ratio can facilitate higher nucleation rates complemented by greater crystal growth. This study provides critical insight for the development of scaling mitigation strategies and creates a basis for the sustainable design of thermal membrane crystallisation systems.