Wood "Freeze" Drying ?

Hmmm.... Sublimation of firewood moisture... interesting.

-- MW

As far as ice cubes losing mass I believe that is due more to modern day frost free freezers removing moisture. hmmmmmmm maybe i can store my firewood in a chest freezer.

I would have to say from 28 years of selling fuel in the Seattle area that it will lose it's moisture. we will have rain for weeks which soaks the wood. 2 weeks of mid teens to lower 20's and the wood is freeze dried. Sucks the moisture right out of it.

Wood will definitely dry in the winter. I think technically the term "freeze drying" is used when some article containing water is frozen, then a vacuum is applied so the water ice can transform directly into a vapor - process called sublimation. Under normal atmospheric conditions, the ice would have to melt first. I suspect that what seems like "freeze drying" at normal atmospheric pressure is actually a slight melting of the ice, but not necessarily enough to leave a puddle or traces of water visilbe to the unaided eye, followed by evaporation.

I would also suspect all the wood really cares about is relative humidity. If you have a 95 degree summer day with 90% RH, there may not be as much drying going on as a 35 degree winter day with 30% RH. I suspose the wood could also dry if the air temp were below freezing if the wood happend to be in the sun or have some other way to pick up a bit of heat.

Corey

cozy heat for my feet said:

I would also suspect all the wood really cares about is relative humidity.
Corey

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Equilibrium moisture content (EMC) of wood in an outdoor environment depends upon both temperature and relative humidity. Judging by the EMC of wood in Alaska in the coldest months, I think it implies wood can somehow sublimate moisture, otherwise fresh cut wood could never obtain these EMC levels when it is frozen solid.

I got this link from Marty last year and found it interesting. Page 7 starts the table of measurements.

http://www.woodweb.com/knowledge_base_images/zp/equilibrium_moisture_content.pdf

For what it's worth, the process of sublimation will occur without a vacuum. If the temp is well below freezing for several days, did you ever notice the ice on your porch, drive way, etc... goes away, yet it definitely didn't melt. Ice cubes in a freezer will also show this principle.

Moisture frozen in wood even at depths in the wood will sublimate. Probably at a slower rate than a warm summer day, but that would take a government grant and several million dollars to study.

Warren

Willhound said:

Neat report, Mo.

Warren, you are exactly correct! A government grant for several million $$$ should just about do it. I'll start on the grant application, but one of you will have to submit it since I'm one a them "dang foreigners". I figure a couple of million should allow us all to meet somewhere cold along with way too many cases of beer (the strong Canadian stuff, of course) and sit and watch a wood pile sublimate. Someone will have to bring their moisture content thingamabob and take a measurement now and again.

Are you in?

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I am soooo in!

I'm there, dude. I'll take readings from the thing-a-ma-bob as long as the beer holds out.