Which of the following is an evaporation heat transfer example?

• A. Ice massage
• B. Vapocoolant spray
• C. Cold bath
• D. Cryo cuff

Answer: (B)

Evaporation cooling happens when a liquid changes to a gas and takes heat from the skin as it vaporizes. A vapocoolant spray does this, because the liquid evaporates almost instantly on contact with the skin, pulling heat away and producing rapid cooling. Ice massage cools mainly by conduction through direct contact with the ice; as the ice warms and melts, some cooling occurs, but the primary mechanism is heat transfer via contact. A cold bath cools the body mainly through conduction (and some convection) from the water, not by evaporation. A cryo cuff also cools mainly through conduction from circulated coolant around the limb. So the evaporating spray exemplifies evaporation heat transfer.