Abstract: A study is carried out on the influence of fluid flow distribution in a falling film evaporator. A turbulence model on the water side flow is established and a falling film evaporator with rated load 600 kW is simulated by a computational fluid dynamics (CFD) program. It is found that the fluid flow and pressure misdistribution are very serious in the vertical direction of tubes, which increase the proportion of dry spots and deteriorate the heat transfer. To improve the situation, it is necessary to arrange structure and position of inlet tube plate reasonably. Within the reasonable pressure drop, an improved case that a porous plate is added in the middle of the inlet room is introduced and analyzed by CFD. The simulation results indicate that the improved inlet structure can effectively enhance the performance of fluid flow and pressure distribution on the falling film evaporator.

Key words: Dryout spots, Falling film evaporator, Flow uniformity, Numerical simulation