[Stoves] A few stove questions

[Kevin Chisholm]

Dear Frank

frank wrote:
> Dear stovers,
> I have a few questions:
>
> Does water at boiling have 1561 J/g energy? That is 4.186 J/C/g starting 
> at -273 deg C (0 deg K).and going to + 100 deg C?
>   
That would be the energy to raise 1 kG from 0C to 100C at normal sea 
level atmospheric pressure.

> If you need an additional 2260 J/g after the water reaches 100 deg C to 
> bring it to a boil that is like bringing the temperature to (2260 / 
> 4.186) 540 deg. C but water does not go above 100 deg C (?). How is this 
> energy stored until it builds up to boiling point? Where is it?
>   

As it boils, the extra energy goes into converting the liquid water into 
a vapor, and it goes off with the vapor. If you immediately condensed 
this water vapor  at 100C and returned it to liquid water at 100C, you 
would get back your 2260 J/g
> If measuring the temperature along a very tall stack is there a place 
> where the temperature drops to 100 deg C (but still has the +2260 J/g 
> energy) and the water condenses releasing the +2260 J/g so the 
> temperature goes up?
>   

Maybe yes, maybe no.. depends on the site specifics. Usually, stacks and 
operating procedures are designed so this will not happen; there can be 
stack corrosion problems.
> If the fire under Lannys stove is of the size that before the heat 
> exits  it is reduced (fins and length) to below 100 deg C.  will the 
> released heat be included in heating the water and we should go by the 
> HHV and not the LHV of the wood? And is this a goal of producing the 
> 'perfect' stove?
>   

If you have a "condensing stack, then you can indeed recover teh energy 
in teh HHV. Indeed, some boilers in Germany have efficiencies of GREATER 
than 100%, simply they are condensing boilers, rated against 
non-condensing boiler standards.

Best wishes,

Kevin
>
> Thanks again,
> Frank
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