What is the dry type evaporator?

In a dry shell and tube evaporator, the freon evaporates in the heat exchanger tube, and the refrigerant liquid filling amount is very small, accounting for about 35% to 40% of the volume of the contents of the tube group. 

However, during the evaporation process, the refrigerant does not have a free liquid surface, so it is called a "dry evaporator".