After reading your article:"Why is it that
water freezes on the surface of a lake but not
below it?" here
I found this very interesting and gave me one more
question which should be interesting to others
too, I hope. Question: If warmer water was
to be sent from lower down, where it is warmer, to
the surface in the form of agitated turbulence, so
the water is moving, would this stop the ice
forming, so long as the volume of water was great
enough to keep ahead of the cold air?
I'm looking at ways to keep breathing holes
open for mammals trapped beneath ice during mid
winter freezes after seeing the movie "Big
Miracle." I'm sure there must be a better way of
keeping the ice from freezing up. Even an outboard
motor should work better. So far I have thought of
lowering a grid of pipes down low and pumping air
through the pipes which are full of small holes.
The thought was that the air bubbles would bring
warmer water to the surface and therefore keep the
ice from freezing over. I still haven't been able
to find out if the water is warmer at the bottom
or half way up yet. I also thought about vertical
pipes suspended in the water, going down deep and
ending about 10 feet below the surface to insulate
the water on its way up but whales and Orcas are
likely to break the pipes and hurt themselves.
Maybe soft pipes would work? I'm not in the areas
you normally answer questions for, I'm in New
Zealand, but if someone has time to give me some
advice I would really appreciate it, so will the
whales who get trapped and die.
Thanks |
Answer 1:
Interesting question! Conceptually, this idea
would work. In fact, a chemical engineer’s job is
to do such modeling! You could model the body of
water as a system such as a tank or a reactor
where there is a heat input and output. At the
surface of the water there is a heat drain where
heat is escaping with some rate that is related to
the surface properties of water and air. At the
bottom of the tank you have some heat input at
some rate. Turbulence would be a little difficult
to account for, but you could simplify and figure
out the necessary rate that heat needs to be
inputted to keep the temperature at the surface of
the water above freezing temperatures. A simple
temperature gradient can be assumed that goes from
hot to cold from the bottom to the top.
Considering the scope of a real project, however,
practical costs may outweigh the benefits. If
these analysis techniques are applied to a huge
body of water like the ocean, you can start to see
the difficulties in laying deep-water pipes that
provide enough heat to prevent the surface from
cooling. Some alternative solutions may be more
cost-effective. For instance, it might be more
practical to have icebreaker ships fragment the
ice as they pass through, and also apply a layer
of salt to aid in melting of the ice. Perhaps
using some sort of solar concentrator might be
able to do the trick as well, though this would
depend on the solar intensity around the area of
interest (generally, icy areas would imply lower
solar intensity).
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