calorific value of wood??

[Peter]

So your suggesting that you measure the volume of dry timber by immersing it in water?

 

Does that not rather defeat the object?

[John Barleycorn]

So your suggesting that you measure the volume of dry timber by immersing it in water?

 

Does that not rather defeat the object?

 

I thought that you were talking about a sample ?

 

In any case if you weighed it beforehand & after then you would also know how much water it had gained.

[Peter]

Nope, if you follow the quote trail, I was referring to firewoodman's method of quantifying his delivery.

[Pete Bannister]

Peter Raffle Sponsor ( interesting surname that..I see there are a few of you around) seams to be the last man standing who can see the wood for the trees. HaHa sorry.

 

Come on BackandPack: you'll be trying to tell us 'work it out with logs' next ( OK maybe the pun is too old-school to make it as a joke these days? Belies my age).

 

Wooww! I just had that Eureka moment Backandpack! Yes you and Archimedes are right...there is a logarithmic relationship between timber moisture content and exothermic energy of combustion...oh well maybe not..its just a bar of soap in the bathwater after all

 

Interesting thread though Firewoodman. Thanks for that and to Peter R-S and Marko for staying sane..oh and correct as well!

[firewoodman]

Nope, if you follow the quote trail, I was referring to firewoodman's method of quantifying his delivery.

 

to clear this up......

 

i fill an exact M3 measure with loosly tipped in firewood, as peter quoted it does not take into account the air as was Pete Bannister's point which i missed (and he missed my quote of me missing that)

 

my measure is a cubic meter of loose tipped firewood, it is also advertised/ described as a loose tipped cubic meter of firewood therefore the customer gets an exact measure of a cubic meter of loose tipped firewood. (usually more, but never less)

 

yes it has air in it, but so would a stacked cubic meter of wood but that is not what it is described as.

 

most of my customers could not tell the difference in species of wood, but there are a few who can, and i have converted some hardened "i'll only burn hardwood" customers over to softwood after they have tried it.

 

can i also point out that not all deciduous trees are hardwood, and not all coniferous trees are softwood. Also some conifers are deciduous and some broadleved trees are evergreen e.g larch and evergreen oak

[Peter]

I hope none of your customers are pedantic enough to insist on a cubic metre of logs, measured with no air gaps.......

 

If they are, then I really think you should measure it for them the Archimedes way, then they would get exactly what they deserve!

[Albedo]

Whilst my googling backs up the knowledgeable comments by the two Peters and other posters I’m sticking with this calorific value thing to see what I can find. I’m interested to find if there is a significant difference between species and if the CV is a useful bit of info or not. Below is a bit of info from 'science direct' where you can get abstracts from published bits of science.

 

Here the values for willow and pop are almost the same by species, but there is a difference of 8- 10 thousand kJ/kg between the younger and the older trees. Does this mean that younger coppice wood could be better firewood than older arb arrisings for example?

 

Abstract

The higher heating values of oven dry poplar wood were from 15,787 (cl. I-214 1-year old) to 24,275 kJ/kg (cl.I-214 2-year old). The average calorific values of willow wood (whole tree with bark) were from 16,169 (14-year old) to 22,572 kJ/kg (2-year old). It should be pointed out that the calorific value of wood is more favorable than that of bark, and the highest calorific values refer to 2-year-old trees.

Edited August 13, 2010 by Albedo
typo

[Albedo]

For those that have mentioned BTU as their prefered measurement unit, heres some conversion info I found.

 

•1 kJ/kg = 0.4299 Btu/ lbm = 0.23884 kcal/kg

•1 Btu/lbm = 2.326 kJ/kg = 1.8 kcal/kg

 

Assuming we haven't lost the will to live, let me know if I'm boreing you all to death:blushing:

[Pete Bannister]

Albedo's point

"Here the values for willow and pop are almost the same by species, but there is a difference of 8- 10 thousand kJ/kg between the younger and the older trees. Does this mean that younger coppice wood could be better firewood than older arb arrisings for example?"

 

well I must say...that is interesting.. I must read that paper and then maybe some eating of my own words might be in order! ...

but its Friday night and I'm going for a pint: deserved or not

Edited August 13, 2010 by Pete Bannister

[Albedo]

well I must say...that is interesting.. I must read that paper and then maybe some eating of my own words might be in order! ...

but its Friday night and I'm going for a pint: deserved or not

 

Glad you found it interesting Pete but no eating of words will be necessary, as everything youv'e said is backed up by all my own researches so far. All the water content stuff and the sameness of CV for hardwoods is there.

 

The impression I've got from this thread so far is that the voices of experience carry some weight. I feel a bit dumb as I'm doing my learning in the open, but if it weren't for this thread I wouldn't have done it and I wouldn't learn at all.

 

If you google 'calorific value of wood kj/kg science direct' it comes at the top of the list. The full abstract is there but you have to subscribe to get the article. (forgot how to post a link)

Edited August 13, 2010 by Albedo
typo