1. The folded molecules diffuse from the liquid phase body to the evaporation surface
The diffusion rate in the liquid phase is the main factor controlling the rate of molecular distillation, so the thickness of the liquid layer should be reduced as much as possible and the flow of the liquid layer should be strengthened.
Second, the free evaporation of folded molecules on the surface of the liquid layer
The evaporation rate increases with the increase of temperature, but the separation factor sometimes decreases with the increase of temperature. Therefore, the economical and reasonable distillation temperature should be selected on the premise of the thermal stability of the material to be processed.
3. The folded molecules fly from the evaporation surface to the condensation surface.
During the evaporation of vapor molecules from the evaporation surface toward the condensation surface, they may collide with each other or with air molecules remaining between the two sides. Since the evaporation molecules are much heavier than the air molecules and mostly have the same direction of motion, their own collisions have little effect on the direction of flight and the rate of evaporation. The residual gas molecules have a chaotic thermal motion between the two sides, so the number of residual gas molecules is the main factor affecting the direction of flight and the evaporation rate.
4. The folded molecules condense on the condensation surface.
As long as there is enough temperature difference between the hot and cold sides (generally 70~100 °C), the form of the condensing surface is reasonable and smooth, it is considered that the condensation step can be completed in an instant, so it is very important to choose a reasonable condenser form.