Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 12/08/2014 02:30:02

Title: Does surface tension affect heat transfer?
Post by: thedoc on 12/08/2014 02:30:02

Margaret Feaster asked the Naked Scientists:
   
I was just wondering. does the surface tension of my hot coffee slow down the heat loss to the atmosphere?

I can't say enough about how wonderful your work is - I would not miss a single episode of any of your podcasts  (http://www.thenakedscientists.com/HTML/podcasts/)ever if I could help it!
What do you think?

Title: Re: Does surface tension affect heat transfer?
Post by: Atomic-S on 12/08/2014 06:05:19

Surface tension arises from the cohesion of molecules. This is the same phenomenon that controls the vapor pressure of the vapor that evaporates off of the liquid in an enclosed container at a specific temperature, but in an open situation, it would be related to the evaporation rate. Evaporation is an important way of transferring heat away from a liquid. So one could say that where there is higher surface tension, there will be lower heat loss because the adhesion responsible for surface tension also retards evaporation.  This is not to say, however, that the surface tension is itself an insulating layer in the sense that Styrofoam would be; it is simply another manifestation of the same phenomenon that, along with other circumstances such as wind speed, controls the evaporation rate.