Effect of microscale mass and heat transport on phase change in tissues and tissue engineered equivalents

A numerical model for predicting heat and mass transport in biological tissues and tissue engineered equivalents during freezing is developed. The liberation of latent heat due to freezing is assumed to be rate-limited by the cellular-level biophysical processes of water transport and intracellular ice formation. Models for these processes are adopted from the literature to calculate the amount of phase change occurring at each control volume in the tissue domain as a function of temperature and time. The coupled model is applied to a freezing problem, analogous to cryopreservation. The results for both models are very similar in a test case using liver tissue parameters and suggest that the uncoupled approach to numerical solution would be adequate to accurately determine thermal history.