Investigation on heat transfer and flow organization characteristics of porous medium in quick freezer based on entransy analysis model: A New Entransy Analysis Model

In the paper, a new Entransy analysis model of heat transfer process in porous medium is built, in which utilization efficiency of entransy is ideal Carnot efficiency and the field function characteristics of entransy are considered. Based on the cooling curve, surface temperature of cooling corns stacked in porous medium and convective heat transfer coefficient along quick freezer are predicted for the first time. Based on entransy theory, the coupling mechanism of conduction, convection and radiation in heat transfer process is quantitatively evaluated. The investigations of internal temperature gradient distribution in monomer and airflow organization efficiency in porous medium present field synergy characteristics of heat transfer process. It is found that convective heat transfer coefficients of the upper part of corn surface and the lower part in porous medium zone for the top layer stacked corns are significantly different. It is confirmed that radiation heat transfer could inhibit convective heat transfer under certain conditions. The surface heat transfer coefficient modified by radiation is used to predict cooling trend of central temperature and different cooling curves match well with measured values. The cooling curve of convex, concave and approximate straight line can be simulated by using the along convective heat transfer coefficient with high accuracy for different types of cooling process. It is found that developing of heat transfer process of conduction in corn or convection and radiation on the surface of the corn is a wavy distribution. Temperature gradient and airflow organization efficacy can reflect field synergy characteristics to a considerable extent. And the enhanced heat transfer characteristics of porous medium are found, which provides inspiration for the optimization design and performance evaluation in porous medium.