To study the complex mechanisms of heat and mass exchange between gas, droplets, and liquid film within a supersonic separator, this chapter establishes a novel three-field two-fluid model based on the Euler–Euler–Euler approach and conducts experimental validation. The model considers both homogeneous and heterogeneous condensations, and interphase slip, allowing for a detailed analysis of the interactions between different phases. In this model, the gas phase, droplet phase, and liquid film phase are each treated as distinct continuous media, with their own sets of governing equations for mass, momentum, and energy conservation. The model captures the intricate dynamics of heat and mass transfer within the supersonic separator by solving these equations. Subsequently, the coupling of heat and mass transfer is examined to understand how energy and material exchanges influence the overall system performance. The study also predicts the separation performance under various operating conditions. The insights gained from this analysis are crucial for optimizing the design and operation of supersonic separators, particularly in applications involving condensation and strong swirling flows. This comprehensive research provides an effective methodology for enhancing the efficiency and effectiveness of supersonic separators. The findings offer valuable guidance for future technological developments in this field, contributing to more advanced and efficient separation technologies.