Rate of Heat Penetration During Sterilization.

[doc henderson]

another question I would have, is could it be augmented with radiant heat such as a heat lamps like for chicks shining on a slab.  would it heat faster than an air/wood interface?  @GeneWengert-WoodDoc 

[Southside]

such as a heat lamps like for chicks

See - chickens, it always comes down to needing chickens.  :D  And yet I am mocked.  ;D

[YellowHammer]

Assuming that the energy input to a pile of wood is the same, then wetter wood will take longer to get to the same temperature as dry wood.  As Doc H mentions, the enthalpy or latent heat or vaporization in water is very high, and as heat is applied to the water in the wood, a significant amount of that energy is used to evaporate the moisture, even though it's intended purpose is to heat the wood.  The wetter the wood, the longer it will take to heat, again, assuming the energy input is the same, whether using heat strips or chicken lights.  

In practice, I have noticed and now use as an indicator, the rate of heating of my sterilization cycles, as a deterministic confirmation of how dry my wood is in the kiln.  More than once, when the sterilization cycle was dragging, I would restest the stack and find wet spots in the stack.  So the dryer the stack, the quicker the wood will reach temp.

Of course, adding heat lamps, I use multiple halogens, to boost the heat input, will overcome this issue, and increase the heat rate at the sacrifice of energy input.  
 
Water conducts heat better than air, so wetter wood will have a more even temperature from case to core, but since the latent heat of vaporization will reduce the overall temperature of the stack, the actual temperature of the stack will be lower than a dry stack, in the same amount of time.

So in my experience, the dryer the stack, the quicker it will heat up.  

I'm thinking that a RF meat thermometer inserted in a drill hole may be an easy way to confirm core temperature, and when it displays the text "Chicken Done" on the scale the wood is cooked.

I'm getting hungry.  Anybody for KFC?

[K-Guy]

@Southside 
Have you thought about seeing a shrink about this chicken fetish? :D

[Southside]

It's all in me head.   :D

[boardmaker]

One thing we've done in the past is drill a hole in the sample and slide the rtd in.  Then, we put plumbers putty over the rear to seal the hole off.  It seems to work well.

[doc henderson]

@Southside We are not mocking (again with the birds) you as far as you know, I just cannot remember how the "whole" chicken thing got started, but I was afraid (some would say chicken)     (did not want to encourage you) to ask.  if heat strips or chicken lights would work, how about chicken strips??     @YellowHammer   . Would it help to rotate the wood inside the kiln such as a sort of rotisserie device.  I am sort of winging it now but what if you let the wood out during the day, and put it in the kiln at night to keep it safe and dry (roost).  with all of the "grain" in the kiln, I am sure the chickens will feel right at home!  I may not have a leg to stand on, but I may have one for dinner.  best regards you old gizzards!     .  I may check with my neighbor across the street, but I am not sure... about why I would cross the .... road.... 

[GeneWengert-WoodDoc]

Y-H,  you are correct basically, but if I use a very high wet-bulb, maybe one or two degrees below the DB, with wet wood I will not have to worry about the latent heat, as little evaporation will occur.  In fact steam condensation will add water.

If I use steam, then when the steam hits the cold wood (cold means surface under 212 F) then there will be huge amounts of energy released (reverse of heat of evaporation) to heat the wood when the steam condenses.  Plus the steam temperature might be 230 F or hotter, which means really fast heat transfer from the surface at 230 F and the core at 70 F.

Transferring heat from hot air without steam condensation is quite slow, although higher air flow speeds help, but higher speeds are expensive.

Does dry wood heat faster?  Dry wood is an insulator for heat.  Wet wood conducts heat.  In hot air at 150 F with low humidity, the wet wood surface will only get to the wet bulb (maybe 110 F) temperature until the surface gets under about 30% MC.  With dry wood, the surface will get to 150 F quickly.  So, actually, we could get similar rates, wet and dry, with certain conditions. The 

[YellowHammer]

You'd have to ask @customsawyer  about the chickens.  It was some very unusual advice I'd given him a little while back on a specialized kiln technique that might solve a problem he had.  He briefly discussed some of it at his Project in the kiln drying class.  

[doc henderson]

I remember the ongoing but not the beginning of the discussion,  I may be sorry I asked.   :D  

[WDH]

Bringing in the chickens is the last resort. 

[Don P]

My mind was wandering, if I had a tank of water boiling over the slab pile at the sawmill and threw in a 4" chunk timber, or at the far extreme, an 8x timber. How long would it take to sterilize it.

[Southside]

If the water is boiling then it is already sterile, no need to toss in that big chunk of wood.   :D

[doc henderson]

yes the water would be sterile, but the temp still has to be elevated at the center of the wood.  water has more heat density than air and if the wood was saturated with water, there would be faster heat transfer to the center.  Because water has a higher density than air, it would take more heat to get to that temp.  so just like cooking in boiling water, there is a time factor and it is different for each material.  like pasta vs frozen chicken!   @Southside   @YellowHammer  @WDH.  boiling water is at 212° in the liquid state but a solid chunk of wood may not be at the center.  only steam can be over 212° at standard pressure.  Thus the water in a pressure cooker or your radiator with a pressure cap can remain liquid at over 212°.  As well water can boil at less than 212° in a vacuum (low pressure) or at standard pressure.  It is the heat, not the temp that is required.  when anything goes through a phase change (water to steam)  heat is consumed to get to the higher energy state, but the temp does not change until there is excess heat.  Water changing to gas at less than 212° we call evaporation.  So the vacuum kilns are "boiling" water at a lower temp.  to be complete water as a solid we call ice and has low enough energy (heat) to form a crystal.  After seeing the movie "lawless" at a recent bachelor party, @Don P are you sure you are not talking about a moonshine still? :D  .  So different liquids have different boiling points and we can separate alcohols and water by boiling and re-condensing these compounds.  can be done by freezing as well.  freeze the mix and pull the ice out of the mix.  this is where adding alcohol to gas helps pull out water from fuel.  water can dissolve in gas or alcohol to some extent, and after that saturation of water in gas, it will separate on its own and form a bi-layer.  Sorry guys, at work and not too busy, so can go on and on! 8)

[Don P]

The problem with fractional distillation by freezing, making apple jack, is you aren't throwing away the heads and tails, you're concentrating them in what you are then drinking, a bad morning after the barn dance. Not that I know anything about cider gone bad :D

Some things will raise the boiling point of water as well, boil some pasta water and when it reaches boil throw some salt in it, the boil goes down and the temp increases.

[doc henderson]

So in theory, if your goal was to pull water out of the wood, then a vacuum would allow evaporation at a lower temp.  If the goal is to sterilize wood submersed in water, then the water could get to a higher temp if under pressure.  We us polyethylene glycol to stabilize wood.  And use individual molecules of ethylene glycol to let water have a higher boiling point.  Ethylene glycol is a poison to consume but PEG is not.  But the increased boiling point and lower freezing point of water containing "anti-freeze"  is from the large number of particles of ethylene glycol, and therefore does not work when they are all hooked together to form large (smaller number) molecules such as PEG.  PEG is used to displace water in wood prior to drying, and allows it to dry with less cracking.  @GeneWengert-WoodDoc 

[Southside]

Too bad it's Sunday - Chick-fil-A is closed and Doc has me hungry for pasta and chicken now.  Oh well, only one other option, headed to the coop. 

[doc henderson]

That is true Don.  I would never drink alcohol separated by freezing, but it could get rid of most of the water to make distillation easier (less volume overall)  The heads are the alcohols with the lowest boiling point such as acetone, and the tails are the highest boiling points such as methanol.  The sweet stuff in the middle is ethanol (moonshine whiskey).  Denatured alcohol is mostly ethanol but with all the others still in including isopropyl (rubbing), acetone (fingernail polish remover) and methanol (Wood)  alcohol.  I use denatured alcohol in a 5 gal jug to pre-dry my wood cookies but it becomes ineffective after it contains too much water.  My buddy has made a little MS, and the heads will burn your eyes and nose, so you do not want to taste it.  So my plan is to freeze my denatured used alcohol to get out most water, then distill it to get more pure alcohol.  I have done a lot of walnut, and the residual liquid has a lot of color that distillation would get rid of as well.  If you want a more uniform color on walnut cookies, then leave the color in.  The dark walnut color will stain the sapwood a darker color.

[doc henderson]

Some of us have to work on Sunday!  .  @Southside   You could "still"  make up some mash, or get a wood fire going and fill up the still.  I have been known to brew some beer.  with beer you drink the water with all the flavor of what was put in it.  With distillates, you are concentrating the alcohol.  Some terms  that I used to use interchangeably were,  Brewing that is boiling grains and other things like hops for flavor and to break down starches for food for the yeast.  Fermenting, or letting the yeast eat the sugars made in the brew stages, and excrete alcohol as a byproduct.  and distillation is to boil off and then recover the alcohols by condensation (cooling) the steam.  You can propagate yeast to save for the next batch by putting sugar in a medium for food in a "beak" er.  again with the chickens.   :D :D

[doc henderson]

That's a good point @Don p.  So salt dissolves into sodium and chloride and creates a lot of particles (ions)  to disrupt the crystalline structure (lowers freezing point)  and raise the boiling point.  This is why NaCl and other salts can be used as ice melt.  Of course table salt is corrosive to concrete and metal so we use ethylene glycol in engines and other salts CaCl for ice melt.  Just like medicines,  NaCl is prob. more effective but also has more side effects so we choose other chemicals.  As a side not, it is the ions that conduct electrical current, so I think they use a salt solution when doing Lichtenberg art.

[Mfrost459]

Ok so I am a bit confused but think I see where Southside is headed. What if we put the slabs in the chicken coop and raise the temp to 170. Then over the right amount of time we could have a dry slab and chicken dinner. Just wondering how long it would have to cook and what the WB temp should be for chicken?
This is a great topic and awesome discussion.

[PA_Walnut]

The pecan is 4" thick and the initial moisture content was 15% to 18%.  The specific gravity of pecan is about .70 to .72.  Initial temp at start-up was 130°.  I assume that the dryer the wood is, the longer it will take for the core to reach 133 degrees as less water would mean more air and less water, and water conducts heat better than air?

Follow the Facebook Marketplace paradigm and just say it's "well seasoned"...leaving you an "out" for any scientific challenge.