This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record ; Data Availability Statement: The research data supporting this publication are provided within this paper. ; Supersonic separator is a kind of natural gas dehydration device with great potential, but its internal mass and heat transfer process has not been fully studied. In this study, a novel three-field two-fluid model described by Eulerian-Eulerian approach for supersonic separator considering the heat and mass transfer between gas, liquid droplets, and liquid film was developed and validated. The interphase slip, latent heat, film heat flux, and film phase change rate were studied. It revealed that the maximum centrifugal slip velocity of droplets can reach 24.9 m s−1. The maximum latent heat is 5.3 × 108 J m−3 from droplets to gas phase during condensation, and the minimum latent heat is -3.4 × 108 J m−3 during evaporation. The thickness of swirling liquid film at wet gas outlet is 21 μm, 47 μm, 74 μm and 89 μm, respectively. The liquid film temperature decreases to a minimum 304.1 K due to droplets deposition, where the maximum heat flux is 0.74 MW m−2. Besides, the frequency and velocity of the interfacial wave of liquid film were obtained by using the cross-correlation algorithm, and their maximum values was 11.07 Hz and 1.49 m s−1, respectively. In addition, for achieving higher dehydration efficiency, the optimal value of the foreign droplet mass concentration should be 0.01 kg m−3. The maximum separation efficiency and dew point depression of separator A are 85.11% and 40.32 °C, respectively. The model without considering the liquid film over-predicts the separation efficiency. ; National Natural Science Foundation of China