Definition of saturated steam

When the liquid evaporates in a limited confined space, the liquid molecules enter the upper space through the liquid surface and become vapor molecules. Because the vapor molecules are in turbulent thermal motion, they collide with each other and collide with the container wall and the liquid surface. When they collide with the liquid surface, some molecules are attracted by the liquid molecules and return to the liquid to become liquid molecules. . At the beginning of evaporation, when the liquid evaporates in a limited enclosed space, the liquid molecules enter the upper space through the liquid surface and become vapor molecules. Because the vapor molecules are in turbulent thermal motion, they collide with each other and collide with the container wall and the liquid surface. When they collide with the liquid surface, some molecules are attracted by the liquid molecules and return to the liquid to become liquid molecules. . At the beginning of evaporation, the number of molecules entering the space is more than the number of molecules in the return liquid. As the evaporation continues, the density of the space vapor molecules continues to increase, so the number of molecules in the return liquid also increases. When the number of molecules entering the space per unit time is equal to the number of molecules in the returning liquid, the evaporation and condensation are in a dynamic equilibrium state. At this time, although the evaporation and condensation are still going on, the density of vapor molecules in the space no longer increases. The state at this time is called the saturated state. The liquid in the saturated state is called saturated liquid, and its steam is called dry saturated steam (also called saturated steam).