Fast Ways to Make Water Evaporate

By Michael Rytting
Water forms steam as it evaporates.

Although water has a boiling point of 212 degrees Fahrenheit, there are ways to accelerate or otherwise aid in a more rapid transition from the liquid phase to the gas phase. Several factors, along with direct heat, effect the rate of evaporation for water.



Factors

Heat is the most obvious factor for aiding in the evaporation of water. However, pressure plays a role as well. Water boils in a vacuum well below 212 degrees Fahrenheit. Also, the vapor pressure, or partial pressure, of water can effect evaporation. The speed of air moving across a surface of water also can speed up the evaporation process. Combining the factors really speeds up evaporation. Heating water with warm air blowing across it aids in evaporation.

Pressure

Molecules like to spread out, and water is no different. Water is the most concentrated state of H2O, with steam being the least concentrated state. So, water wants to evaporate in an environment with low water partial pressure already. Also, the atmosphere pushes down on a surface of water and, if the atmospheric pressure can be reduced, either through high altitude or pulling a vacuum, water molecules are more apt to move away from the concentration of water and evaporate.

Velocity

The velocity of air on the surface of water can speed up evaporation in two ways. First, it can agitate the water, breaking up surface tension and increasing surface area, exposing more molecules to the atmosphere. Secondly, velocity and pressure have an inverse relationship (this is how lift works for airplanes). So, as air increases speed across the surface of water, it also lowers pressure locally. The combination of agitation and pressure drop work together to speed up evaporation.

Temperature

Water spilled on a hot sidewalk in the summer evaporates more rapidly than water spilled on that same sidewalk on a cold autumn day. Water evaporates without reaching its boiling point, and the hotter it is, the faster it evaporates. Obviously, as water reaches its boiling point through the addition of heat, it evaporates more rapidly, but any heat that can be added to the water speeds up the evaporation process.

About the Author

Michael Rytting has been writing since 2011. His professional interests focus on materials, especially plastics. He also has experience in metal refining and processing. He received a Bachelors of Science in chemical engineering from Brigham Young University and has been issued a U.S. patent.