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Title: Molecular simulations of heat transport in water and aqueous solutions
Author: Iriarte Carretero, Irene
ISNI:       0000 0004 7656 892X
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2016
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This Thesis explores heat transfer mechanisms and non-equilibrium effects in ice and aqueous solutions using computational techniques. In the first chapter, a study of the thermal conductivity of ice phases Ih, VI and VII was performed for the TIP4P/Ice water model using both equilibrium and non-equilibrium molecular dynamics. Significant differences were found between experiment and simulation for phases Ih and VII, while better agreement was displayed by phase VI. Heat flux autocorrelation functions and their spectra were decomposed into acoustic and optic contributions, which were different for each of the phases studied. The thermal conductivity and spectra of a plastic phase appearing at high pressures and temperatures in several water models was studied and compared with phase VII. Results show a similar value of thermal conductivity despite having a different structure. In chapter two, the thermophoretic response of different nanosolutes was studied in infinitely dilute aqueous solutions using the single particle thermophoretic algorithm. A linear increase in the thermophoretic force was observed with increasing temperature and an inversion in the sign of the thermophoretic response was observed in the 250-400K temperature range. The free energy of solvation of the nanosolutes was studied and decomposed into its enthalpic and entropic contributions. A reasonable estimate of the Soret coefficient was obtained using these values. Finally, the thermopolarisation of TIP4P/2005 water was studied for a wide range of thermodynamic states. The effect features a significant enhancement near the critical point and a reversal in the sign of the thermopolarisation coefficient was observed at higher densities and lower temperatures. The thermopolarisation coefficient shows a strong correlation with the thermal expansion coefficient. The thermopolarisation response of the ice plastic phase was compared to ice VII, with the latter showing a stronger response despite the rotational freedom of the plastic phase.
Supervisor: Bresme, Fernando Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral