iDRY Vacuum Kilns

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Anyone used a water to air heat exchanger to DH dry lumber?

Started by oakiemac, March 29, 2010, 08:12:18 PM

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oakiemac

I have been looking at the maintenance and electric costs of running refrigeration equipment in my DH dryers. It occured to me that I have an almost endless supply of cold water at the bottom of my pond or I could even pound in a well head and pump water from the ground and circulate it through a heat exchanger. This would condense the vapor just the same as the refridgeration units but use a lot less energy and if it breaks I woulded have to call an HVAC guy.

I would still leave the DH units in place but turn off the compressor and circulate water through the heat exhanger with a fan sucking the air through it. A drip tray at the bottom would collec the condensate and drain it outside via a small hose.

Seems like this would work to me. I'd have to size the exhanger to be similar to the DH unit so the lumber would not be dried too fast or too slow and in the summer if the water was not cold enough then I can simply turn the compressors back on.
Any thoughts on this? ???
Mobile Demension sawmill, Bobcat 873 loader, 3 dry kilns and a long "to do" list.

Kcwoodbutcher

Sounds like it could work depending on the temp of the water. I would think you would want something around 40 degrees or below to establish a low EMC at a reasonable kiln temp. You don't mention what you are using for heat input.
My job is to do everything nobody else felt like doing today

Den Socling

I once saw a company that tried using pond water with air/water heat exchangers on vacuum kilns. They were a biological nightmare. Slime and who knows what grew inside the heat exchangers and piping. They hired me as a consultant and I switched them to cooling towers where I could treat the water. In your case, a cooling tower wouldn't keep the water cold enough except in the winter.

oakiemac

I dont think slime would be a problem. I'd suck from the bottom where the water is cold and clear. Algea only grows on top and since we are using this to cool with nothing would be baked onto the HX. I could also pound a well down about 15' and use ground water which would have minimal junk in it except it might be hard.

KC-the kilns are initially heated with electric heaters then the compressors provide the rest of the heat. Kind of like a heat pump. The pond water is pretty cold on the bottom but that is something that I need to measure to get an exact temp. Flow rate throught he HX is also a big factor on the amount of heat exchange.
Mobile Demension sawmill, Bobcat 873 loader, 3 dry kilns and a long "to do" list.

Kcwoodbutcher

But aren't the compressors part of the refrigeration system you're trying to eliminate?
My job is to do everything nobody else felt like doing today

Den Socling

oakiemac,

Pond water has biological activity no matter how cold it is. Shallow wells also are polluted with bugs. One group in particular is sulfate reducing bacteria. They live in the dark with no apparent food. They create nasty, black lumps of slime. Under the slime, sulfuric acid forms and it eats through heat exchangers in short order,

Den

ronwood

Could you use the pond as a heat sink and cool down the water in the closed loop?
Sawing part time mostly urban logs -St. Louis/Warrenton, Mo.
LT40HG25 Woodmizer Sawmill
LX885 New Holland Skidsteer

Den Socling


oakiemac

Using the pond as a heat sink woul work-just extra expense. This is all just food for thought and I like the idea of using some thing that I already have like the water that nature keeps cold. My main concerns would be if it was cold enough by time it goes through a pump and the piping to condense enough of the vapor. Might be an interesting project to start this summer. As if I didnt have enough to do all ready. :o

KC- I think the electric heaters might be enough to heat it up without the compressors, but then again it might not be and then I'd have to add extra heaters which would offset the savings. So your point is well taken. Another issure to ponder. ???
Mobile Demension sawmill, Bobcat 873 loader, 3 dry kilns and a long "to do" list.

Brian_Rhoad

I think Koeter, now Nova, dry kilns started out with water from a spring running through a "condensor".

submarinesailor

Oakie,

I like the idea.

If I was going to do something like this, I would considering using one of these, http://www.awebgeo.com/SlimJim16e0.html?page=SlimJim_Projects.asp and make it a closed loop system using a glycol coolant.  That would control any growth within the system.

Now, if you are really planning on doing this, give Jack DiEnna of the Geothermal National & International Initiative Inc. a call.  His number is 610-659-4998.  He should be able to guide you to the right people in your area.

Bruce

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