🚀 go-pugleaf

Andreas Haffner  <andreas.haffner@matforsk.nlh.no> wrote:
>Nick Pine wrote:
>> David Davis  <davisd@ucs.orst.edu> wrote:
>> >I have to agree with George. Logic tells me you have provided numerous
>> >small wet paths for energy transfer via the bubble walls. Before the
>> >bubbles transfer relied on convection in the air in the space.
>> 
>> A lot of little convection paths in series will have more thermal resistance
>> than one big one...

>Misunderstanding here, I think:

Perhaps so...

>Before you had one large convection path

Right...

>With the bubbles you have many small convection paths and additionally many
>*conduction* paths.

That may not be so bad... Water has a US R-value of about 0.25 ft^2-hr/Btu
per inch, as I recall, eg for downward heat conduction. So what would we have
as the simple aggregate conductive thermal resistance owing to the water films,
from one side of a wall to the other, if the 4" wall space were filled with
a regular matrix of 1/4" cubical bubbles with a 0.0001" (approx 12 micron,
on the order of an 80 F black body IR wavelength) wall thickness, ie if the
wall cross section were 2500 parts air and 1 part water in each direction? 

A 2500 x 2500 foot wall would have the equivalent of a 1 ft^2 thermally
conductive water shunt 4" thick with a US thermal resistance of 1, so the
wall would have an effective thermal conductance of 1/(2500^2 ft^2) or
an R-value of 6,250,000. Not bad :-) This is more easily investigated by
experiment. We need a few more serious 12 year old scientists... 

Nick