~*~vvv~*~ said:
10 lbs wood = 85000 btu dry or 0% mc
20% mc= 2lbs water @ 1000btu/lb to evaporate= 85000-2000= 83000 btu
30%mc= 3lbs water @ 1000btu/lb to evaporate=85000-3000= 82000 btu
did i do that right?
No, because 10 pounds of wood at 20% MC actually only has 1.7 pounds of water by weight, and it only has 8.3 pounds of wood fiber. 10 pounds of wood at 30% MC only has 2.3 pounds water by weight, and 7.7 pounds of wood fiber. Also, you used the high heat value for wood rather than the low heat value. The high heat value includes the latent heat from the water formed by combustion, but with proper flue temps above 212º you never recover that... unless, of course, you use a Magic Heat. ;-P
So...
10 pounds @ 20% MC = 8.3 pounds wood fiber x 8000 BTU = 66,400 BTU - 1700 BTU lost evaporating the water = 64,700 BTU
10 pounds @ 30% MC = 7.7 x 8000 = 61,600 - 2300 = 59,300 BTU.
Of course, you will never see all that heat, because that would only occur at 100% burn efficiency, and those figures don't consider the heat lost up the flue... unless, of course, you use a Magic Heat. :shut: