Humidity in exhaled air & its condensation on the respoirator fibers.
Equipment
- Cotton mask or paper towel.
Writers
Ján Šikula
Activities
Activity in pairs. One of the pair puts on a mask and exhales intensely several times through the mouth. The second of the pair observes with a thermal camera the temperature of the surface of the mask/towel. It is advisable to use a sufficiently large area analysis with a display of the value and position of the maximum temperature.
Questions for discussion
Why do we reach a temperature greater than 41 °C on a mask when the body temperature is below 37 °C? Is the maximum surface temperature of the mask for the first to sixth exhaust the same?
Answer
Water vapor condenses on the fibers of the mask, which is contained in exhaled air. Condensation is a process in which the gaseous state turns into liquid, this is accompanied by the release of latent heat, this results in an increase in temperature.
Tip
Try using classic surgical masks or masks with nanofibers. What will be the surface temperature of the mask? If you have a microscope, compare the fiber structure in the surgical and cotton masks.