The Forestry Forum is sponsored in part by:

iDRY Vacuum Kilns


Forestry Forum
Sponsored by:


TimberKing Sawmills



Toll Free 1-800-582-0470

LogRite Tools



Norwood Industries Inc.




Your source for Portable Sawmills, Edgers, Resaws, Sharpeners, Setters, Bandsaw Blades and Sawmill Parts

EZ Boardwalk Sawmills. More Saw For Less Money!

STIHLDealers.com sponsored by Northeast STIHL


Woodland Sawmills

Peterson Swingmills

 KASCO SharpTech WoodMaxx Blades

Turbosawmill

Sawmill Exchange

Michigan Firewood, your BRUTE FORCE Authorized Dealer

FARMA


Baker Products

ECHO-Bearcat

iDRY Wood Lumber Vacuum Drying for everyon

Nyle Kiln Dry Systems






Author Topic: Yet another solar kiln build started  (Read 4289 times)

0 Members and 1 Guest are viewing this topic.

Offline SawyerBrown

  • Senior Member x2
  • *****
  • Posts: 1092
  • Age: 62
  • Location: Central Illinois (Peoria)
  • Gender: Male
  • If you're gonna be stupid, ya gotta be tough!
    • Share Post
    • Saw It There
Re: Yet another solar kiln build started
« Reply #20 on: March 25, 2015, 03:34:47 PM »
OK, walls are up, held together with baling wire and masking tape (kidding).  Quit because that damp wind was just cutting through me and it was tough to work without gloves, even though I hate using gloves.  Maybe later this week it will warm up.

 

 
Pete Brown, Saw It There LLC.  Wood-mizer LT35HDG25, Farmall 'M', 16' trailer.  Custom sawing only (at this time).  Long-time woodworker ... short-time sawyer!

Offline Tree Dan

  • Senior Member
  • ****
  • Posts: 370
  • Age: 64
  • Location: N/W Ontario
  • Gender: Male
  • I may be In Canada but my heart Is also In the U.S
    • Share Post
Re: Yet another solar kiln build started
« Reply #21 on: March 25, 2015, 09:43:56 PM »
Looking mighty fine 8)
Is that a man door roughed in? plus are yaa putting in 2 barn doors?

The weather here has been nasty as well

Nice job...
Wood Mizer LT40HD, Kubota KX71, New Holland LS150, Case TR270
6400 John Deere/with loader,General 20" planer, Stihl 880, Stihl 361, Dolmar 460, Husqvarna 50  and a few shovels,
60" and 30" Log Rite cant hooks, 2 home built Tree Spades, Homemade log splitter

Offline SawyerBrown

  • Senior Member x2
  • *****
  • Posts: 1092
  • Age: 62
  • Location: Central Illinois (Peoria)
  • Gender: Male
  • If you're gonna be stupid, ya gotta be tough!
    • Share Post
    • Saw It There
Re: Yet another solar kiln build started
« Reply #22 on: March 26, 2015, 03:12:38 PM »
Ok, question for you guys ... been trying to decide how to attach the corrugated polycarbonate roofing.  Valleys or tops?  And if tops, use what they're calling a "no-drip spacer"?  Drill first?  And thinking I need to add purlins ... maybe 3 in a 10' span?

Thoughts?
Pete Brown, Saw It There LLC.  Wood-mizer LT35HDG25, Farmall 'M', 16' trailer.  Custom sawing only (at this time).  Long-time woodworker ... short-time sawyer!

Offline Andy White

  • In Memoriam
  • *
  • Posts: 809
  • Age: 68
  • Location: Brookeland Texas 75931
  • Gender: Male
  • I'm not so new anymore!!
    • Share Post
Re: Yet another solar kiln build started
« Reply #23 on: March 26, 2015, 07:51:29 PM »
SB,
Attach the screws on the ridges, not in the valleys. I used the corrugated poly filler strips under mine , mounted on purlins, and used the selftapping screws. No predrilling , mine is almost a year old now, and still no leaks! I treated the edges with flashing.
 

  

  

  

 
Trim length, and fold down and caulk with silicone, and done!     Andy
Learning by day, aching by night, but loving every minute of it!! Running HM126 Woodland Mill, Stihl MS290, Homemade Log Arch, JD 5103/FEL and complete woodshop of American Delta tools.

Offline Glenn1

  • Senior Member
  • ****
  • Posts: 495
  • Age: 64
  • Location: Winston Salem, NC
  • Gender: Male
  • Drying lumber one board at a time
    • Share Post
    • GPS Hardwoods
Re: Yet another solar kiln build started
« Reply #24 on: March 26, 2015, 09:48:15 PM »
That is one nice looking solar kiln!!
Vacutherm IDry, Nyle 53 Kiln, New Holland Skid Steer, Kaufman Gooseneck Trailer, Whitney 32A Planer

Offline YellowHammer

  • Senior Member x2
  • *****
  • Posts: 4540
  • Age: 54
  • Location: New Market, Alabama
  • Gender: Male
  • Take Steps to Save Steps
    • Share Post
    • Hobby Hardwood Alabama
Re: Yet another solar kiln build started
« Reply #25 on: March 26, 2015, 10:22:39 PM »
As said, screws through the ridges, fold or otherwise trap the edges down or the wind will get under it and try to pull it off. 
YH
HobbyHardwoodAlabama.com

Offline SawyerBrown

  • Senior Member x2
  • *****
  • Posts: 1092
  • Age: 62
  • Location: Central Illinois (Peoria)
  • Gender: Male
  • If you're gonna be stupid, ya gotta be tough!
    • Share Post
    • Saw It There
Re: Yet another solar kiln build started
« Reply #26 on: April 02, 2015, 09:38:17 AM »
That IS one nice looking kiln!!  Thanks for the advice.

Raining today, so no work gonna happen.  Yesterday got some more siding on and a few more 2x4's that will act as purlins, day before got a coat of flat black paint on.  (Andy, yours look nice all in a row, just have to toe-nail in one side ... I may have to rethink that ...)  Won't be long and I'll be ready for the poly roof.  So Andy, what did you do at the roof line on the tall/"north" side?  I was thinking of a short overhang with the poly I'll cut off ...
 

 

The north side will have double doors for loading on one end, and a "people door" on the other.
 

 

Sonny's been "helping" me clean up the lumber scraps   :D
 

 
Pete Brown, Saw It There LLC.  Wood-mizer LT35HDG25, Farmall 'M', 16' trailer.  Custom sawing only (at this time).  Long-time woodworker ... short-time sawyer!

Offline Planman1954

  • Senior Member
  • ****
  • Posts: 812
  • Location: Marion, Louisiana
  • Gender: Male
    • Share Post
Re: Yet another solar kiln build started
« Reply #27 on: April 02, 2015, 04:08:26 PM »
Are you using the piney woods design like I did? It looks like mine, except for the door area. I'm proud of you! Thanks for the progress photos. You'll be glad you took them when you look back on what you've accomplished on your own.
Norwood Lumbermate 2000 / Solar Dry Kiln /1943 Ford 9n tractor

Offline Tree Dan

  • Senior Member
  • ****
  • Posts: 370
  • Age: 64
  • Location: N/W Ontario
  • Gender: Male
  • I may be In Canada but my heart Is also In the U.S
    • Share Post
Re: Yet another solar kiln build started
« Reply #28 on: April 02, 2015, 08:27:07 PM »
The kiln is looking super, and the sky is blue and the sun is shinning. 8)

Your almost there.
Wood Mizer LT40HD, Kubota KX71, New Holland LS150, Case TR270
6400 John Deere/with loader,General 20" planer, Stihl 880, Stihl 361, Dolmar 460, Husqvarna 50  and a few shovels,
60" and 30" Log Rite cant hooks, 2 home built Tree Spades, Homemade log splitter

Offline WDH

  • Forester
  • Administrator
  • *****
  • Posts: 29502
  • Age: 66
  • Location: Perry, GA
  • Gender: Male
  • April 1998 - August 2008
    • Share Post
    • hamsleyhardwood.com
Re: Yet another solar kiln build started
« Reply #29 on: April 02, 2015, 08:53:59 PM »
Will you be loading with a machine like a tractor or fork lift, or will you be hand loading?
Woodmizer LT40HDD35, John Deere 2155, Kubota M5640SU, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Offline SawyerBrown

  • Senior Member x2
  • *****
  • Posts: 1092
  • Age: 62
  • Location: Central Illinois (Peoria)
  • Gender: Male
  • If you're gonna be stupid, ya gotta be tough!
    • Share Post
    • Saw It There
Re: Yet another solar kiln build started
« Reply #30 on: April 03, 2015, 08:42:05 AM »
Planman, same basic design, except instead of painting the interior black, I'm planning to put flat black painted sheet metal roofing on the underside of the rafters and run air through the gap.  I may be wrong about this, but it seems to me that since wood is an insulator, it's not going to retain much heat, but sheet metal is going to get pretty hot, and you get the added effect of radiated heat even on the underside.  (I know this from painting metal roofing as a kid ...  ;D ).   Do you agree or am I missing something, like surface area?

WDH, loading by hand, unfortunately.  I think I know where you're going with the question ... are the doors wide enough?  I've got about 10' of door opening (and, by the way, not much more between kiln and tool shed), so I could eventually pre-load at least that long if I ever got more equipment.  But thanks for asking!

Pete Brown, Saw It There LLC.  Wood-mizer LT35HDG25, Farmall 'M', 16' trailer.  Custom sawing only (at this time).  Long-time woodworker ... short-time sawyer!

Offline pineywoods

  • Senior Member x2
  • *****
  • Posts: 5156
  • Age: 83
  • Location: Marion, Louisiana
  • Gender: Male
  • Engineering analysis-just sittin thinkin about it
    • Share Post
Re: Yet another solar kiln build started
« Reply #31 on: April 03, 2015, 09:15:42 AM »
Sawyer, you will like the black sheet metal. Two big advantages. Wood is a poor solar collector, metal is much better and like you said, makes a bunch more heat. Enough extra that you can skimp on the insulation without much effect. Two, you will find significant heat gain on cloudy days..Sunlight is not what heats the metal, it's infra red radiation which penetrates clouds to some extent...Looks good, leaving a wide back door, your back will thank you...
1995 Wood Mizer LT 40, Liquid cooled kawasaki,homebuilt hydraulics. Homebuilt solar dry kiln.  Woodmaster 718 planner, Kubota M4700 with homemade forks and winch, stihl  028, 029, Ms390
100k bd ft club.Charter member of The Grumpy old Men

Offline GeneWengert-WoodDoc

  • Senior Member x2
  • *****
  • Posts: 2766
  • Location: Bishop, GA
  • Gender: Male
  • Author of "Sawing Hardwood Lumber"
    • Share Post
    • Book on Sawing hardwood Lumber
Re: Yet another solar kiln build started
« Reply #32 on: April 03, 2015, 11:44:27 AM »
If you have a black painted absorber surface, it will absorb basically all the solar energy input (visible solar energy and infrared energy) and convert it all to heat.  The key is the black paint and not what is under the paint.  So the amount of heat energy produced is the same whether the surface under the paint is metal or is wood, or any other material.  If it were different, then where would the energy be going?  Once the energy passes into the kiln, it is fully absorbed by the black paint regardless of the material under the paint.  The energy that comes into the kiln cannot just disappear.  It takes the same small amount of heat to heat a piece of metal as to heat a piece of wood.  Now, hot metal feels hotter because metal conducts heat to our fingers faster than does wood..you can handle a piece of wood at 180 F, but hot water or hot metal at 125F is too hot to handle.  Bottom line is that the material under the back paint does not matter for solar drying, but it might matter for your pocketbook if one type of material is free or lower cost.  Use whatever costs less and goes up easiest.

Note that most solar covers (glass fiberglass, plastic) do not transmit much infrared energy.  This means that once the energy in the kiln is heat, not much energy will leave the kiln as infrared energy through the clear cover.

Here is more technical info:  What is different, is that a flat absorber right under the clear collector will be hotter than if the walls and other absorbers in the kiln are painted black.  The reason is that there is more area, so the energy is dispersed, giving less temperature, but still the same amount of energy is in the kiln and energy is what drugs wood.  (Now, a lighted match would be even hotter, but the heat is in a small spot.  Likewise, a parabolic collector with the area of the solar kiln's roof is even hotter in a small spot, but the total energy is the same.  This is similar to using a magnifying glass to focus the energy on one spot and getting wood to burn.)  The flat plate right under the cover...it is hotter, but in a smaller spot than if the walls were the absorber.  But again, the overall energy input to the kiln is the same, and it is energy that evaporates water.  When cooking an egg or trying to boil water, we do need a certain temperature to do the job (water needs 212 F to boil), but for evaporating water from wood, it takes the same energy.

One small difference is that the closer the absorber is to the clear collector cover, the greater the heat loss by convection, as the air is hotter in that small space.  The hotter this absorber, the greater the infrared radiation losses as well.  For that reason, especially if the clear covers do not reflect nearly 100% of the infrared radiation (non-green glass does indeed reflect most IR; it is called solar glass), the overall efficiency is higher if the absorber is further away.  On the other hand, convection losses are reduced if the absorber is cooler (more area).  Further, the hotter the walls are if they are black and heated directly by sunlight, the greater the conduction losses.  This loss is about the same as the increased convection losses in the areas hit by sunlight.  Of course, if the fan baffles are black and the cover on the top of the lumber is black, there would be no conduction losses from these absorbers.. 

So, the bottom line is that there will be no important differences with the walls, fan baffles and lumber cover as the absorbers except the amount of black paint used (VT design for example) versus a flat plate absorber right under the clear collector covers, (so long as the walls are insulated and the clear cover reflects infrared).  That is, the black paint will absorb all the solar energy entering through the clear cover no matter what the shape or composition.  The biggest key for solar kiln design is to avoid energy losses from the kiln once this energy is in the kiln, thereby using as much of the solar energy for evaporation as possible.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Offline SawyerBrown

  • Senior Member x2
  • *****
  • Posts: 1092
  • Age: 62
  • Location: Central Illinois (Peoria)
  • Gender: Male
  • If you're gonna be stupid, ya gotta be tough!
    • Share Post
    • Saw It There
Re: Yet another solar kiln build started
« Reply #33 on: April 03, 2015, 05:46:44 PM »
Doc, really good explanation, thanks. 

I'm still thinking this through (and just for the sake of a good argument  ;D), isn't it really the amount of heat energy in the air, which is the only "fluid" that comes in contact with the wood?  If you could magically shut off all heat transfer from internal surfaces to the air, it would never warm up, and the wood would never dry ... all the energy would remain in the internal surfaces.  (And, I guess if there was no external heat transfer to air either, it would continue to heat up until it melted ...   :D).  So isn't the real question how much of that fixed amount of captured energy can you get into the air?  Since heat transfer is a function of delta-t (sorry, don't know how to make a "delta"), it seems like the hotter surface of the metal would result in more heat transfer to the air, via both convection and radiation.  And metal is better than wood because you get that higher delta-t on both sides.  But I'm sure I'm missing something!   :D

Sorry for all the questions, I'm just trying to learn and make sense of it all in my own head.
Pete Brown, Saw It There LLC.  Wood-mizer LT35HDG25, Farmall 'M', 16' trailer.  Custom sawing only (at this time).  Long-time woodworker ... short-time sawyer!

Offline Andy White

  • In Memoriam
  • *
  • Posts: 809
  • Age: 68
  • Location: Brookeland Texas 75931
  • Gender: Male
  • I'm not so new anymore!!
    • Share Post
Re: Yet another solar kiln build started
« Reply #34 on: April 03, 2015, 07:01:37 PM »
SB,
For the flashing at the top, I took a sheet of coil stock 14" wide, and broke it with a 7" leg with a hem on both edges for strength. Put it in the brake, and bend to 135, as the roof is at 45. It is lapped over the side flashings forming a shingle effect, and screwed as all the sheets. The screws here go thru the sheets and the flashing into the top purling. Really watertight. The vertical leg is nailed to the siding at the top with s/s nails.   smiley_smash smiley_smash smiley_smash
Learning by day, aching by night, but loving every minute of it!! Running HM126 Woodland Mill, Stihl MS290, Homemade Log Arch, JD 5103/FEL and complete woodshop of American Delta tools.

Offline GeneWengert-WoodDoc

  • Senior Member x2
  • *****
  • Posts: 2766
  • Location: Bishop, GA
  • Gender: Male
  • Author of "Sawing Hardwood Lumber"
    • Share Post
    • Book on Sawing hardwood Lumber
Re: Yet another solar kiln build started
« Reply #35 on: April 03, 2015, 10:46:40 PM »
Sawyer Brown.  Excellent comments.  Here is a further explanation.  The black paint will get as hot in any situation.  I think we agree on that.  Metal will conduct the heat to the other side, the dark side more easily than a piece of wood, especially if the wood is thicker.  But even so, eventually all the energy will leave the absorber and get into the air.  If it didn't leave, then the wood would have more energy, get hotter, etc.  If we had slate for the absorber, the rock would store energy, but eventually the energy will come out of the rock.  At an instant, around noon, one absorber might release more heat for that moment, but over the daylight hours, it will be equal for all absorbers if they are the same color.

You are correct that heat transfer from the collector depends on delta T.  The hotter the collector, the more heat transfer for that moment.  But now, if a cloud goes over the collector, the metal  absorber, if it is hotter, will quickly cool as it releases its energy.  Wood will release its energy more slowly and so will stay warmer for a while.  So, if we want to dry something in a few hours, metal has an advantage.  But over a days time, no difference.  By nightfall, the two collectors will have had the same energy input from the sun and will have released all this energy into the kiln.  So at the end of the day, the two will be at the same cool, energy state, ready to begin a new day the next morning.  Neither one stores or consumes energy over a 24 hour period...they both release 100% of the energy they absorbed.

Because wood is a thermal insulator, the black wood surface will be essentially the same temperature as a black metal surface if they have the same area, are facing the same direction, etc.  The difference is that the metal will feel hotter to the touch, as mentioned earlier.  The amount of energy used to heat the wood is very small, and that energy will eventually be released as night comes.  With more area, which happens when the walls and fan baffels and top cover of the lumber pile are used as absorbers, the absorber temperature will be cooler and so delta T will be smaller, but the increase in area will make up for that difference.  The formula is energy release by convection = (convection coefficient) x (temperature of surface - temperature of air) x (area). 

Consider this...if we had a metal absorber painted black and also insulated the back side really well, the top side would then be twice as hot, delta T would double, and energy convection rates would double.  The area for convection is half however, so the energy per minute is the same.  But, the total energy input, which is the amount of incoming solar would still be the same, and the energy output also, even if the absorber is hotter.  So, think about energy and not heat or hotness.  Isn't an absorber that is an insulated piece of metal really close to a piece of wood?

Although this discussion might be considered theoretical, in 1961 at the U.S. Forest Products Lab I made four small solar kilns and used one or two layers of covering and compared them, and used a metal absorber right under the clear covers and compared that to black painted walls.  The two layers of cover increased performance (much hotter air in the kiln), but the type of absorber had no effect on kiln air temperature.

There was a master thesis written at Colorado State Univeristy in about 1968 about the energy balance in a solar kiln, That has even more technical info.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Offline Planman1954

  • Senior Member
  • ****
  • Posts: 812
  • Location: Marion, Louisiana
  • Gender: Male
    • Share Post
Re: Yet another solar kiln build started
« Reply #36 on: April 04, 2015, 10:45:59 AM »
SawyerBrown...you ARE using the piney woods design. It will work great. The painted black metal attached under your rafters will have your kiln heated on a hot summer day upwards to 180 degrees plus. Keep the pics coming!
Norwood Lumbermate 2000 / Solar Dry Kiln /1943 Ford 9n tractor

Offline SawyerBrown

  • Senior Member x2
  • *****
  • Posts: 1092
  • Age: 62
  • Location: Central Illinois (Peoria)
  • Gender: Male
  • If you're gonna be stupid, ya gotta be tough!
    • Share Post
    • Saw It There
Re: Yet another solar kiln build started
« Reply #37 on: April 04, 2015, 11:55:26 AM »
Thanks, all!  ... Andy for the advice on overhang, Doc for the excellent explanation (which now makes perfect sense), and to Planman for the encouragement!  Hope to get more done today and next week before several days of predicted rain.
Pete Brown, Saw It There LLC.  Wood-mizer LT35HDG25, Farmall 'M', 16' trailer.  Custom sawing only (at this time).  Long-time woodworker ... short-time sawyer!

Offline WDH

  • Forester
  • Administrator
  • *****
  • Posts: 29502
  • Age: 66
  • Location: Perry, GA
  • Gender: Male
  • April 1998 - August 2008
    • Share Post
    • hamsleyhardwood.com
Re: Yet another solar kiln build started
« Reply #38 on: April 04, 2015, 08:10:18 PM »
With your hardwoods at 180 degrees, I suspect that bad things might happen  :).  Pine and hardwood, especially oak, are two different animals.

Brings to mind a quote by Lee Trevino on golf.  "You can talk to a slice, but a hook won't listen". 

Pine can stand the intense heat and rapid drying.  White oak won't listen. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5640SU, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Offline LeeB

  • Senior Member x2
  • *****
  • Posts: 8032
  • Age: 60
  • Location: Yellville Arkansas
  • Gender: Male
  • proud to be a TEXAN in Arkansas
    • Share Post
Re: Yet another solar kiln build started
« Reply #39 on: April 05, 2015, 03:13:20 AM »
Boy Danny. You sure are old. I haven't heard that name in a long time.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.


Share via delicious Share via digg Share via facebook Share via linkedin Share via pinterest Share via reddit Share via stumble Share via tumblr Share via twitter

xx
solar kiln started

Started by xlogger on Drying and Processing

55 Replies
7670 Views
Last post August 03, 2015, 07:07:37 AM
by GeneWengert-WoodDoc
xx
Pre-build solar kiln questions(Photos of kiln building progress)

Started by caveman on Drying and Processing

58 Replies
8297 Views
Last post April 17, 2016, 06:35:35 PM
by caveman
xx
Another Solar Kiln Build

Started by Josef on Drying and Processing

26 Replies
3571 Views
Last post November 10, 2016, 09:59:42 AM
by pineywoods
xx
Solar kiln build

Started by Fil-Dill on Drying and Processing

17 Replies
4439 Views
Last post February 12, 2011, 09:49:54 AM
by Den Socling
 


Powered by EzPortal