The real wood story of Btu continues

Just in case you haven't had enough in the recent threads about this, here is more information.
http://apt.allenpress.com/aptonline/?request=get-abstract&issn 35-6161&volume7&issue&page14
ABSTRACT
Compression drying is basically a process of forcing the free water in wood to move under high hydrostatic pressure through a solid structure. Fundamental information regarding the time-dependent characteristic of compression drying is necessary to develop efficient commercial processes. The purpose of this study is to provide an initial evaluation of the effect of some factors-pressure, wood density, and particle (chip) size-on free water extraction.
Five species-aspen, balsam fir, jack pine, red maple, and red oak-were tested in this study. For each species both typical pulp size chips and particles from hammermilled chips were used. Drying rates were determined under constant ram face pressures at 500 psi, 1,000 psi, 1,500 psi, and 2,000 psi, respectively. The concept of drying rate is one of the important factors in dealing with compression drying, especially in designing dewatering pressure cycles.
The most efficient compression drying is achieved during the first two minutes. Drying rates are negligible after 3 to 4 minutes of constant pressure in the 500 to 2,000 psi range. The analysis of variance for species shows highly significant differences in final moisture contents. Size of chips had a significant effect on final moisture contents. Compressed density of hammermilled chips is slightly higher than that of unrefined chips. High density chips require higher pressure to initiate effective drying rates.
http://www.kppc.org/KWWRS/ValueAdded /
Moisture content affects the energy content of wood when burned and the amount of wood fuel required to achieve desired heat or steam outputs. Harvested wood or wood from landscaping has a moisture content between 35 and 50 percent and an energy content of approximately 5,500 BTUs (British thermal units) per pound. Kiln-dried wood residue has a moisture content of 5 to 10 percent and an energy content of approximately 7,500 BTUs per pound. Wood separated from a process waste stream and used for cogeneration is typically air dried to a moisture content of 15 to 20 percent and has an energy content of approximately 6,000 to 6,500 BTUs per pound.
http://www.pelletheat.org/3/benefits /
Efficiency a.. More efficient fuel than cordwood. Pellets have five to 10 percent moisture content in comparison to 30 to 60 percent for cordwood and woodchips. This means pellets are a more efficient fuel. b.. Higher Btu content than cordwood. Wood pellets have a Btu output content of 350,000 per cub. Ft. of fuel, versus 70,000 to 90,000 for cordwood or wood chips. This means pellets produce more heat.
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Edwin Pawlowski wrote:

http://apt.allenpress.com/aptonline/?request=get-abstract&issn 35-6161&volume7&issue&page14
Well Duh! on the last sentence.

Something a little screwy here. 35-50 percent moisture is a rather large range. Even so, the numbers don't add up. How do they get they get 5,500 BTU from 35-50 percent moisture if 5-10 percent moisture produces 7,500 BTU. Assume that the 5-10 percent is really 5 percent then 0 percent would be 7894 BTU, 50 percent would be 3947 BTU, and 35 percent would be 5131 BTU. You can work it with 10 percent giving 7,500 BTU and it still doesn't come out. And that's is just considering that the water has no heat content.
In burning, a lot of the heat is going to be used up in driving the water off. I would suspect that a wood that produces 7900 BTU when 100 percent dry would net not 1/2 of that (3950 BTU) when the weight was 50 percent water but something like only 40 percent of dry wood or 3160 BTU as a maximum per pound. Driving off the water takes a lot of the heat.

a. Who in hell burns cordwood that is 60 percent water? Rather a specious argument for pellets.
b. Well yes if you compare it on a volume basis. What is the efficiency basis? storage space?
I love it, Ed, when those promoting a product or an idea get so carried away that they makes statements that are just plain silly.
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http://apt.allenpress.com/aptonline/?request=get-abstract&issn 35-6161&volume7&issue&page14
SNIP
Increases in moisture will take back some of the heat, because the pellets _do_ readsorb moisture, making covered storage necessary.
They do not, of course produce more heat in an absolute sense - can't be - but the density is favorable, the product is largely made of what normally becomes waste, or at least is here, and most important - can be augered into the box as needed to maintain proper burn. It's not Methane or fuel oil, but it's more convenient than wood, and a hell of a lot more convenient than gofer wood.
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