To solve the problem of droplet entrainment at the outlet of a falling film evaporator and the liquid carryover of a compressor

the spatial distribution of droplet entrainment and the fluid hydrodynamic parameters of the evaporator were investigated in this study by utilizing computational fluid dynamics (CFD) during the phase change process. The accuracy of the numerical method was verified by the test results of prototypes K1 and K2

and the objective control parameters

including the amounts of droplet entrainment (φ≤0.37%)

average velocity of horizontal flow (vH≤0.24 m/s)

and average flow velocity at the outlet of baffle (vB ≤2.18 m/s) were established to evaluate the risk of the droplets entrainment at the evaporator outlet. Based on the established objective control parameters

the risk assessment of the falling film evaporator models (K3~K6) was carried out. The results showed that K3 and K4 met the requirements of the control parameters and had a lower risk of carrying liquid. In comparison

K5 and K6 had a higher risk of carrying liquid. Based on the predicted high-risk model with droplet entrainment

control parameter groups

such as reducing the outlet velocity of the distributor

increasing the diameter of the cylinder

and adjusting the gaps between the tube bundles

were adopted in the optimization design

and the distribution of the flow pattern outside the heat exchange tube was analyzed. The results indicated that the entrainment rate of droplets with the optimized evaporator is reduced by more than 75% compared to that before optimization

the state of the outside tube mainly exists in the form of droplet flow

and the distribution of the liquid phase outside the tube is relatively uniform. It was found that there is no liquid at the outlet of the falling-film evaporator through an optimized test (K5

K6)

which is expected to provide a fundamental basis for the optimization design of the subsequent falling-film evaporator.