A study of rewetting and conjugate heat transfer influence on dryout and post-dryout phenomena with a multi-domain coupled CFD approach

摘要

In the present study, a multi-domain coupled computational fluid dynamics (CFD) approach is developed for the modeling of dryout and post-dryout heat transfer. For the fluid part, the thin film and gas core are modeled by the liquid film model and two-fluid model, respectively. For the solid part, the heating process is modeled by either using a constant heat source or solving the Joule heating problem. The fluid-solid conjugate heat transfer is calculated by using carefully designed coupling schemes which can automatically determine the operation mode for pre- and post-dryout regions. Unlike standalone simulations where only the inner wall temperature is predicted, coupled simulations are able to predict the outer wall temperature, allowing a direct comparison with experiments. Simulations were carried out for a wide range of flow conditions and validated against the corresponding steady state experiments. By newly introducing a film rewetting model, the current CFD code is capable of simulating the transient behavior of dryout. With the rewetting model, the coupled code successfully predicted the dryout hysteresis.