BoatBanter.com - View Single Post - Peltier Cool Box

(Larry) wrote in message ...
In a couple of trawler and sailboat magazines, I've seen a peltier
cooler that doesn't have any cooling fins outside the box. The
junction heats up a fairly good sized copper braid (so you can bend
it) that goes to a thru-hull fitting of some solid metal the ocean
won't eat...stainless?? not sure. The idea is to have a
seawater-cooled solid state fridge which should cool the junction MUCH
better than fins in that hot engineroom or boiling bilge.....

Sorry I don't remember the company name...maybe someone else reading
this will know. Looks very interesting.

Yes, that's a very good system for cooling the junction while it's
powered, but it doesn't thermally isolate the junction (hence cool box
internals) while the Peltier is depowered. I really need the thermal
isolation you get with a thermosyphon (or some other) setup as the
solar powered Peltier typically runs only around eight hours a day.
Loss of "cold" overnight via the Peltier was a real problem with the
original air cooled arrangement.

Our cooling zig-zag in the engine compartment duct actually works
quite well, as that duct goes to the bottom of the engine compartment.
When the engine is running, air is dragged in through the duct from
abovedecks by virtue of the engine's aspiration, helping cool the
zig-zag. After the engine has been running, the thermally induced
airflow in that duct is from the outside in as the engine compartment
also has high level vents. When the engine is cold it seems there's
enough air movement in the duct to cool the thermosyphon return water
to only a few degrees above ambient.

Still, a few degrees above ambient air temp is often quite a few
degrees above seawater temp.

If there was an easy (moving-parts-free) way to combine a thermal
"diode" or "switch" with seawater cooling then that could be ideal,
but that'd be a bit difficult on my boat as the Peltier is above the
waterline.