[Stoves] Comparable heat outputs of stoves

[psanders at ilstu.edu]

Stovers,

Jigme has offered to assist (with his students) on bringing together some info
on energy conversions into usable form.

Below are about 5 miscellaneous messages (including AJH's helpful message) and
then more notes from me on my conversion efforts.  Sort of messy as it stands,
so please do not read on unless you have a true interest.  You will eventually
see some results that are less rambling than what we have at present.

Paul

My reply to Jigme and other messages is below:
******************

Quoting Jigme Rangdrol <rangdrol at turboisp.com>:

> Greetings Paul Anderson.
>
> The WORD document causes a page fault error on this machine so I can 
> not read it. Can you please copy it as text and resend it?
>
JR,  here it is, and my comments are after it.

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 capitalized
> 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
******************
Spread sheet or cheat sheet, either is fine.  Could use the spread 
sheet to make
a nice one page (maybe more pages) printed sheet that could be in hand for use
without needing to go to a computer for a calculation.

Paul

*******************************
> It sounds like maybe you would rather have a spreadsheet program?
> Something you can use like a conversion program that does quick 
> calculations and conversions.
>
> I was thinking an actual printed cheat sheet.
> HTML and the text are a snap and the GIF, JPG are simple operations 
> from there.
> I put whatever puzzle has me going up as my wallpaper.
> I just need to know what it should contain.
>
> I think we may run out of time but I will keep at it if that is the case.
>
> My herd is Jr High math and science.We have 14 days left and pretty 
> much everything finished up.
> It would be a good way for them to use the technologie skills and try 
> to get a handle on conversions.
> The stoves, ANY fire I suspect, are a real treat for this mob.
>
> I still have trouble with this email thing.
> I will post a call for input if you like.
>
> Yes let's give it whirl!
>
> J.R.
>
>
>
> psanders at ilstu.edu wrote:
>
>> Dear Jigme,
>>
>> Great idea.  Let's do it.
>>
>> Note:  You did not send your message (nor this message) to the 
>> Stoves Listserve.
>> Was that your intention?  Please reply (after you read what is below) if you
>> want to proceed and how do we send something preliminary (this message with
>> modifications?) to the Stove Listserve.  We do want their inputs as we go
>> along, not just at the end.
>>
>> What grade-level do you teach, and what subjects?
>> But school is almost over.  When would this task be started and have 
>> the initial
>> results?  I was thinking I wanted something done in June, but 
>> students might not
>> be ready then.
>>
>> I am attaching a Word document which is what AJH sent to me via the 
>> Listserve.
>> Note that it has the address for an EXCELLENT conversion program, that I now
>> use almost daily.  We do not want to repeat that, just use those values and
>> unit for energy and power, plus add in things from the biomass aspect of our
>> work.  For example, AJH sent
>>
>> 18.6 MegaJoules per kilogramme of oven dry wood.
>>
>> That is sufficient to calculate the energy in other units, as found 
>> in each kg.,
>> and also in each pound.
>>
>> Or how many kg of oven dried wood are needed to make 50,000 kcal    
>> And that is
>> about 200,000 BTU when the conversion factor of 4 BTU per kcal is 
>> used, but the
>> actual value is 3.968321 BTU for one kcal, as given on the 
>> conversion program.
>>
>> Since most people do not have oven-dried wood as their fuel, we can make
>> adjustments to the numbers.  One source is:
>>
>> http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr13.pdf
>>
>> But another source what says it more clearly is:
>> http://www.gi.alaska.edu/ScienceForum/ASF12/1249.html   says:
>> So, which puts off more heat--one pound of oven-dry birch or one pound of
>> oven-dry aspen? It's a trick question, because all oven-dried woods 
>> have about
>> the same energy content, 8,600 Btu per pound. Oven-dried wood contains no
>> moisture, an impossible feat to achieve without baking wood in an 
>> oven before
>> burning it in a stove. Therefore, if firewood were sold by the 
>> oven-dried pound
>> instead of the cord, 10 pounds of aspen would be as valuable as 10 pounds of
>> birch, but the aspen would take up twice as much room in the woodshed.
>>
>> same source says:
>> Sampson's measurements are for air-dry wood with a 20 percent 
>> moisture content.
>> Wood is considered dry when it reaches a moisture content of 15 to 
>> 30 percent,
>> according to Shelton. Freshly cut, green wood contains 30 to 60 percent
>> moisture.
>> ******************* end of quotes ********
>> So, if we allow that most people are using 15% to 20% moisture wood, 
>> the 18.6
>> MegaJoules per kilo must come down by that amount, so the actual MG would be
>> about 16 or 15 MJ per kilo of common moisture (seasoned or air-dried? or
>> "regular") woody biomass.
>>
>> Do we need to also allow that some of the fuel must be used to boil away the
>> moisture, resulting in less combustibles available for making high
>> temperatures?
>>
>> My original objective was to get some ball-park comparisons.  Here 
>> is a start:
>>
>> 4 BTU =~ 1 kcal
>> 1 BTU =~ 0.25 kcal
>>
>> 50,000 kcal =~ 200,000 BTU
>>
>> 1 kg reg-wood =~ 16 MJ (+/- 2 MJ for wood type and moisture content)
>>
>> 1 kg reg-wood =~ 16 MJ =~ 3800 kcal =~ 15,000 BTU =~ 4.5 kWhr(t),
>> which means that a nicely sized residential cookstove that takes one hour to
>> fully consume 1 kg of regular woody biomass is operating in the 4 to 5 kWhr
>> range.  Because all of this energy is expressed as being in one hour of
>> constant burning, we can say that the power is a 4 to 5 kW stove.
>>
>> An "institutional stove" is estimated here to be about 5 times more powerful
>> than a residential cookstove, so it would be using in an hour 5 kg 
>> of reg-wood
>> and would be a 75,000 BTU  or 19,000 (almost 20,000 kcal) unit.
>>
>> Of course, if that stove was operated for only 30 minutes at its 
>> full power, the
>> amount of energy needed would be half of the above amounts.
>>
>> So, when my baker friend asked me about a stove that would 50,000 
>> kcal per hour,
>> (200,000 BTU) I can now say that that size represents 58 (almost 60)
>> kiloWatt-hour thermal and represents 210 MJ which is 13 kilos of reg-woody
>> biomass (or 29 lbs (almost 30 pounds)), which is 3/4 of a 40 lb bag of wood
>> pellets, but because wood pellets probably have less than the 15% moisture,
>> maybe only 25 pounds of pellets per hour would fire the combustion 
>> unit that he
>> needs.
>>
>> In summary, I now have the ability to make the comparisons that I 
>> want to make,
>> but I must do the work on a one-by-one case basis.  Now the task is 
>> to simplify
>> the above into some chart or table that covers more cases and can be easily
>> consulted.
>>
>> So, Jigme, does any of this make sense as a possible student project?
>>
>>
>>
>>
>> Quoting Jigme Rangdrol <rangdrol at turboisp.com>:
>>
>>> Greetings Paul Anderson et al
>>>
>>> I would be willing to make the compilation of a "cheat sheet" in 
>>> HTML, text and GIF/JPG a student assignment and post it here.
>>> I need to know if everyone has actually got an agreed source. I 
>>> would rely on my Glover.
>>>
>>>
>>>
>>> Paul S. Anderson wrote:
>>>
>>>> SNIP
>>>>
>>>
>>>> 1.  The unit equivalents:  kcal and BTU and KWthemal and kjoules.  
>>>> I am at a
>>>> loss for comparing them.  I would really like to have a look-up 
>>>> table for quick
>>>> comparisons.  Just having formulas of equvalents is not so easy.
>>>>
>>>
>>>
>>
>>
>>
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