Vac kiln for Costa Rica

[Den Socling]

Suppose we put the painted side toward the sun and a condenser on the other side. The wood would be stickered. Maybe we could control drying with humidity control. Maybe an alarm could pull lower chamber pressure if the wood got too warm. At night or anytime the painted side got too cool, the vac would shut down and the wood would equalize. What do you think, Sergey?

[serg]

Den, hi!
I think that this system will give positive result in heating.
Qualitative movement of air will not be. There will be a mould, the big difference on a stack.
What temperature in the afternoon in CR?
Sergey.

[Fla._Deadheader]

 HEY, A personal thread. 

  CR does not get above 80 degrees for very long each day, and that is just a few months of the year. The tank could be shaded some, if needed ??

[serg]

My opinion. In CR it is necessary to use a solar energy. I offer to heat water and to submit her(it) to registers. It is possible to strengthen heating of water due to mirrors. Cooling at night, the big pause, a stack will cool down strongly. In the afternoon energy will be directed on warming up of a stack. Drying will receive zero variant.
Stack to warm up, more energy is required 2-3 times.
Conclusion. It is possible to use the combined system of heating, in the afternoon the sun, at night maintenance with the help of the electric boiler. The tank should be warmed well. A pause of cooling of 20 minutes. My vacuum drying chamber works in Uzbekistan. Temperature in the summer of 45-50 degrees С. Economy of an electricity big.
Sergey.

[crtreedude]

Thanks for the help everyone - a little data here.

The temperature is variable in Costa Rica based on the altitude. Where Harold is, 82F would be warm - but, and it is a big one - the sun is direct. You won't believe how strong the sun is unless you have been in the tropics before. On the low lands (like the other farm Harold), it will get warmer - say 85 F.

When the sun is out, things heat up - it is just you only have 12 hours of sunlight year round. Doesn't really get cold at night either. If it rains the day before, when the sun shines, it can feel like a sauna. Harold hasn't experienced this yet.

The hot time of day is from 10:00 am to about 3:00 pm.  It is never like in the North in the Summer though. But that is ambient heat - not solar heat.

The solar heat is more intense - but the ambient heat is less due to the cooling during the night.

Oh, and electricity is very cheap here.

[Den Socling]

Sergey,

I'm thinking of this kiln as a steam vac. We leave enough air and vapor for natural convection. Since the location is so close to the equator, the sun is more directly overhead so one side might be painted black and the other side would be white or shaded.



Halfway up the shaded side would be a kiln condenser similar to this to cool and dry vapor that was rising on the black side. We would need to add a baffle under the cart. Air would flow through the stickered wood.

If the steel got too hot, we would pull the chamber pressure lower. This would interrupt the transfer to the wood and, since we lowered the boiling point, the wood would cool while a lot of water was removed.

If the wood started getting too cool, we would let the pressure back up and recover more heat.

Just thinking out loud, here. 

Den

[crtreedude]

Remember also labor is inexpensive - within reason, having someone move shading material on and off the vacuum might work fine. Just another chore to do on the farm - check temperature gauge and adjust shading.

If we can automate it - that is fine, but people will be around all the time - and they have no problem reading a guage.

[serg]

Den I with you agree. A solar energy to use in vacuum it is possible. You perfectly know that it is necessary to make: 45 degrees С, vacuum 0.09, plus movement of air through a stack. Can it is necessary apply the fan to good and fast heating switch off the fan and collect a condensate. Work behind experiment.
Sergey.

[Fla._Deadheader]

Anyone ever see an Autoclave ??  A BIG one Found one today, that is 50'' dia. X 24 feet long. Doors on both ends. Has a control box with needle type recorder. Has a track inside and 2 pipes, about 1'' dia., running the length of the tank, overhead. These have small holes, presumably to emit steam ?? Comes with 2 ball valves, one SS, one Bronze, probably 2? pipe. Many small pipes on the top outside, running the length of the tank.  Seals are Asbestos. Has insulation that can be removed if necessary.

  Questions

[Fla._Deadheader]

 Can I get a rough time schedule for drying one load in this kiln, if all goes well ??  Forgot the time frame involved. ?? It's all Hardwood.

[serg]

Fla, hi!
I understand (the computer translator not absolutely correctly a little translates) you want to do (make) independently vacuum furnace? You want to dry what wood? Breed, density, thickness and humidity?? Capacity square or round. All begins with calculations of durability on residual pressure (-1) from an atmosphere. What technology of vacuum drying?
You do (make) technology CR? To give advice (councils) on a forum, knowing half essence of a question, not correctly and dangerously.
Sergey.

[Fla._Deadheader]

Hi Sergey
 Trying to build a kiln to dry tropical hardwoods. I do not have exact information to answer your questions. I understand the problem with answering without all the required information.  I was just asking a rough guess, referencing from past experience of Oak. I will be away from the Internet very soon, and will need crtreedude to obtain the information for us.  Thanks for any and all assistance you offer. It is greatly appreciated.

[serg]

Well.
I shall wait with the big interest the information from you.
Density of an oak in Russia 690 - 720 kg/ М3, density of exotic breeds from 900 up to 1200 kg / m3. Term of drying will increase in 2 times.
Sergey.

[Den Socling]

Harold,

We will be able to give you some idea after you have run a few loads.    You are entering uncharted waters! The only thing I might guess is that it will be faster than a conventional kiln depending on how late into the evening we might have enough heat to keep it going.

A better idea would to be to use an auxiliary heat source during the night. Copper pipe running back and forth on the inside bottom of the black half ought to keep the convection going.

It's surely going to be faster than air drying. And the wood is much safer in a steel chamber.

Den

[Tom]

May I interrupt for a question?

Here is my observation:

The heat from the sun is derived in intensity by the directness of the rays.   Summer gets them coming straight down and winter gets them coming at an angle.  The direct rays provide more energy.

The temperature in CR being 80 degrees is because of ocean breezes and altitude.  Ocean breezes evaporate perspiration and  make you feel cool, but a solar collector (not affected by wind) will get real hot.  Altitude is cold because there is not as much air to heat.  The suns rays are the same as at sea level though and a collector should generate as much heat in either place.

So, the cooling of a kiln at night could be controlled by insulation and Mass (serg's water)

Here is the question (assuming the above to be correct)

Wouldn't  CR be an ideal place for solar collection because of the direction of the rays, regardless of ambient air temperatures?  And, why would ambient air temperatures, controlled by insulation, be much of a concern?

[Murf]

As a follow up to Tom's observation......

Wouldn't it be relatively simple to use a large tank of liquid as a thermal storage unit?

Use the heat of the sun durning the day to heat the liquid, and kiln, then all night draw the stored heat back out of the liquid and into the kiln. That way you could achieve a much more uniform heat.

The other point, if it's of any use, I would be more than willing to offer English / Russian translation if it would make the process any easier. 

[Den Socling]

The auxiliary heat could certainly be from water that was heated by the sun during the day. Then it gets pumped through the copper pipes I mentioned. There is a greater danger of overheating during the day. He needs a vac system capable of forcing the boiling point down.

[old3dogg]

I would have a back up heat source because the sun is just not reliable enough.

I feel that while vac drying you need to have constant heat. What if you get weird weather and the sun doesnt come out for 6 days?

Id be afraid of a solar powered vac kiln.

I wish you luck and maybe it will work but vacuum drying only works well if you are stacking wood between hot water plates. Unless of course you are drying thin wood. But then again, whats the point of a vac kiln?

Steam, solar or DH will work on thin wood. And much cheaper also!

[crtreedude]

It is here except for about 2 weeks out of the whole year. Clear almost every morning - about 4:00 PM get a rain of about an hour.

Then, during the time you harvest most of the wood - no rain at all for 3 months just about.

I wouldn't worry about lack of sun.

[old3dogg]

Still dont think it would it work. The weather just aint reliable enough.
Ya must have constant heat to vac dry. And a constant vaccum.
Cant start and stop. It just doesnt work in vac drying.