[Stoves] Comparable heat outputs of stoves

[AJH]

On Sat, 27 May 2006 12:01:01 -0500, Paul S. Anderson wrote:

>1 KWt = ____ BTU  = _____ kcal =  _____ kjoules, results from ____ kilos (0r

Paul you are mixing power (W) with energy (kWhr(t) or BTU).

Power is the rate of releasing energy in the same way speed is the
rate of covering distance.

What you want is:

1KiloWatthour(thermal) or kWhr(t) = 3412.142BTU= 859.8452kcal
=3600kJoules, (note that 3600 is the number of seconds in an hour)

(conversion c/o a neat freeware program
http://joshmadison.net/software/convert/)

Joules and Watts are named after people so are capitalised

>1 kilo of normally dry woody biomass yields .................

We seem to have standardised on 18.6 MegaJoules per kilogramme of oven
dry wood.

As 1 Joule per second is a Watt if we burn this 18.6MJ in an hour we
yield 18.6million/3600 Watt per second= 5.167kWhr(t). 

The only reason for using kWhr is that people in the west are used to
paying their utility bills in this unit, to distinguish between
electricity and heat we add the (e) or (t).

When we have discussed this in the past there has been some reluctance
on the part of the American contributors to depart from imperial
measure yet it was pointed out to me by a [stoves] contributor that

"The Omnibus Trade and Competitiveness Act of 1988 amended the Metric
Conversion Act of 1975, designating the SI system as the preferred
measurement system for the United States. "

Calories (cal) and British Thermal Units (btu) were the means of
measuring heat (same as energy) they were the amount of heat necessary
to raise a unit mass of water through one degree of temperature. The
british unit used lb and Fahrenheit, the metric originally used gramme
and centigrade.

Then Joule discovered there was a direct link between work (force time
distance) and heat , so units of heat could be unified with those of
work with appropriate conversion constants. 

The SI system came later and made the kilogramme the unit mass. I
believe the big calorie then became standardised as 1000 old calories.

Thus a calorie could be equated with a force of one Newton pushed
through a distance of one metre (=1 Joule) times 4.1868 (the
conversion factor).


AJH