What is the difference between a falling film evaporator and a regular heat exchanger?

Film evaporation involves feeding the liquid feed into the upper tube bank of the heating chamber of the film evaporator; through a liquid distribution and film-forming device, it is evenly distributed across the various heat exchange tubes. Under the influence of gravity, vacuum, and air flow, it flows in a uniform film form from top to bottom. During the flow process, the liquid is heated and vaporized by the heating medium in the shell side; the resulting steam together with the liquid phase enters the separation chamber of the evaporator. There, the steam and liquid are thoroughly separated, with the steam going into the condenser to be condensed (in a single-effect operation) or entering the next stage of the evaporator as a heating medium, thereby enabling multi-effect operation. The liquid phase, on the other hand, is discharged from the separation chamber. 　　 The main body of the equipment consists of heaters of stages I, II, and III, a separator, a heat pump, a condenser, a sterilizer, insulation pipes, a material pump, a water pump, and an instrument panel. All parts of this equipment that come into contact with materials are made of high-quality stainless steel. From Baidu Baike

In a falling film evaporator, the key principle is that the liquid flows down along the wall of the tube, forming a thin film; this liquid film is then evaporated. For a more in-depth analysis, please wait.