‘Heat engine’ mechanism of latent heat release during the recalescence stage in supercooled heterogeneous icing

Supercooled icing on solid surfaces is a universal phenomenon, which can be generally divided into five stages: liquid cooling (supercooling), nucleation, recalescence, solidification and solid cooling. The nucleation and recalescence processes, which are highly transient and kinetically controlled, are typically neglected in macroscopic simulation by assuming a solid mass fraction at the end of the recalescence. This work develops an alternative to simulate these highly non-equilibrium processes based on the Molecular Dynamics (MD) method and NVE ensemble. A unique ‘heat engine’ mechanism of latent heat release during the recalescence is identified through investigating transient evolution of energies. Driven by the competition of heat release from the solidification and the heat dissipation to the surrounding liquid, the water-ice mixture approaches quasi-equilibrium to the solidification temperature during the recalescence process. A new formula for calculating the ice mass fraction at the end of recalescence is proposed and validated against different simulation and experimental data, which can be used as the initial condition for subsequent icing modeling.