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This run uses an aqueous solution that is approximately 15.5 wt.% Na2SO4. Initially, the pressure was about 259 MPa. 05/10/04 17:39:45: The run starts with a fluid at about 291 K. Upon cooling, the fluid contracts. 05/10/05 04:48:45: The system is supercooled over 20 K below the liquidus point before crystals, presumably mirabilite, suddenly start growing. With this initial crystal growth, the volume increases slightly. Upon further cooling, the crystals continue to grow more slowly. 05/10/05 12:20:45: The system is ultimately supercooled about 8 degrees below the eutectic temperature before suddenly freezing. The volume decreases rapidly, indicating that the solid formed is a high-density phase of ice. Further cooling does not result in any significant changes. Since the solution in the connecting tubing is frozen solid, the pressure and volume transducers do not fully reflect conditions inside the pressure cell. Since the ice has contracted upon freezing, the pressure inside the cell is likely lower. 05/10/06 06:33:45: The system is then warmed up until the material in the connecting tube softens and the pressures equalize. As the pressure inside the cell increases, the volume decreases. 05/10/06 07:33:45: Around 245.7K eutectic growth and melting occur. The process is reversible with very slight changes in temperature. 05/10/06 19:03:45: With sufficient warming, all the ice melts and the remaining mirabilite crystals begin to slowly dissolve up until the liquidus point. As they dissolve, the dense crystals collapse towards the bottom of the cell. 05/10/10 22:53:44: After the final crystals dissolve, the system returns to the original liquid curve.
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