This study focuses on the numerical analysis of two-phase flows with phase change, specifically evaporation and condensation, in confined systems. The aim was to select and validate a suitable numerical model within the ANSYS Fluent. From the available models, the Mixture model with the Evaporation - Condensation sub-model, utilizing the Lee model, was chosen. Unlike common approaches that rely on preset or estimated values for the Lee model correlation coefficients, this study presents their experimental validation on an experimental setup. The obtained data were implemented into a 3D model of the setup, which demonstrated good agreement with laboratory measurements. Analysis of the results revealed the dependence of the correlation coefficient values on saturation vapor pressure, where higher pressures and boiling temperatures lead to lower coefficient values, subsequently influencing the rate of phase change. This study contributes to a deeper understanding of multiphase phase changes, enhances the accuracy of numerical simulations, and has practical implications for the design and optimization of thermal equipment.