Ice growth in aviation jet fuel

Experimental studies were performed to gain a better understanding of ice growth in aviation jet fuel at low temperatures. Dissolved water precipitated from fuel to form fine water droplets of diameters typically no more than 5 μm as the fuel was cooled. Some water droplets could remain in a metastable supercooled state to temperatures below −30 °C. At temperatures below that, supercooled water droplets appeared to freeze to form metastable ice particles. Examples of this type of ice have been reported and may be stacking disordered ice (I) composed of randomly stacked layers of cubic ice (Ic) and hexagonal ice (Ih) sequences. Ice particles, exhibiting Ih polymorph characteristics, were found to nucleate and grow on surfaces at sub-zero temperatures. These hexagonal ice particles were observed to grow at the expense of the metastable ice particles near them. The observed mass transfer of water from metastable ice particles to deposition on the hexagonal ice particles in aviation jet fuel was attributed to the augmented Wegener-Bergeron-Findeisen (WBF) process and the Ostwald ripening process. The two processes supported the growth of hexagonal ice particles until the metastable ice particles near them were completely exhausted.