Development of A Droplet Entrainment Rate Model for A Vertical Two-Phase Flow

Existing droplet entrainment and deposition models were investigated and assessed, and a new entrainment model was proposed. The existing models were assessed through the entrained fraction measured in air-water and steam–water experiments at low pressure. The results showed that the Hewitt model predicts the air-water experiments better, and the Kataoka and SPACE code models predict the steam-water experiments better. However, because the existing models were developed based on the assumption of an equilibrium state owing to the difficulty of data acquisition, they are somewhat unreasonable to apply in transition phases. In order to solve this problem, the entrainment rate was calculated from the mass change in liquid film and this was used to develop the proposed model. The proposed model was assessed using the air-water and steam-water experiments and obtained better prediction results than the existing models.