[Stoves] Another high performance stove located

[Frank Shields]

Greetings Stovers and Crispin,

Also:

Let say you had burned a lot of the char during the process (instead of having it all left over as in your example). Like in a Rocket stove that burned to ash.

I now think we need to add another factor to the calculations. 

The energy in the biochar burned can be split into solid-C > CO and CO > CO2 energy. We can leave the solid-C values out of that heating food because they occur and release heat in the stove body. But the CO > CO2 heat can be used to cook food. Not really sure how to do this. But have an idea:

We then need the enthalpy value for solid-C to CO. 
We need the enthalpy value of CO
We need the enthalpy value for CO2

Then we just need to determine the values per gram (from mole) and the percentages of each as it goes from solid-C to CO2. We then can split the total energy found in the biochar used up in the process into Stove Heat to Volatile Heat.

Its the enthalpy of solid-C > CO thats the problem. 


IF this is even a way to determine these values AND if we should leave out the heat just heating the stove from calculating efficiency for cooking.

Regards

Frank



> On Nov 16, 2015, at 12:02 PM, Crispin Pemberton-Pigott <crispinpigott at outlook.com> wrote:
> 
> Thanks Frank
> 
> Do you think the volatiles will be as high as 25%? I find that surprisingly high. What would the carbon content be?
> 
> Thanks
> Crispin
> 
> Dear Crispin and Stovers,
> 
> Thanks for the example. This is the way I look at it:
> 
> Doing a TGA on a sample of fuel it might come out something like this Ponderosa Pine taken from REED book located on Paul Andersons webb site. 
> fixed Matter 17.17%
> Volatile Matter 82.54%
> Ash 0.28%
> Carbon 49.25%
> Hydrogen  5.99%
> Oxygen 44.36 %
> Nitrogen 0.06%
> Sulfur 0.03%
> HHV 2002 Kj.g
> HIV 19.66 Kj/g calculated
> 
> You started with 760 grams and ended with 193 grams after all flames stopped.
> Based on the REED TGA you should have started with 760 and ended with 131 grams char left
> Therefore you have 62.5 grams volatiles left in the remaining material along with all the char.
> 
> Using the TGA (and formula they use) you started with 
> 15200 kj energy
> 
> Using info from the REED document Biochar has 32 kj/g energy and Fixed Matter (biochar) of this sample = 17.17% of biomass
> You start with:
> 11008 kj volatiles energy
> 4192 kj biochar energy
> 
> You are left with:
> 4192 kj biochar energy
> 1240 kj volatile energy
> Totals 5432 kj energy
> 
> You used:
> 15200 - 5432 = 9768 kj energy to cook your food.
> 
> This method can be used on Rocket Stoves and all others eliminating all the mess-and-fuss of dragging out burning mass of fuel and sorting to get energy values of what is left.
> 
> 
> If we do it this way we have our ‘energy used’ values pertaining to the exact fuel we use. We just need to get a TGA and associated chemical values OR a TGA and calorimeter values. 
> 
> adding in ash complicates the calculations so I left those out. 
> 
> 
> Thanks
> 
> frank
> 
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> 
>> On Nov 15, 2015, at 4:29 PM, Crispin Pemberton-Pigott <crispinpigott at outlook.com <mailto:crispinpigott at outlook.com>> wrote:
>> 
>> Dear Friends of Clean Burning
>>  
>> I managed to test the small TLUD stove I obtained from Yogyakarta today for nearly three hours. It held 780 g of pellets and ignition material. They are wood pellets I got from Alex at the Stove Testing Camp so I presume they are pine – not sure. Alex…?
>>  
>> Here is the mass burn rate and power:
>>  
>> <image001.jpg>
>> The stove either had not been assembled correctly, or because of vibration travelling 50,000 km by air, the central metal tube had rotated with respect to the air controller. There was no primary air getting into the fuel at all except via internal leakage.  When the stove was demonstrated at the GIZ office in Accra last Saturday, it was in fact on “Low”. This misalignment was not visible from outside the stove, even looking under the bottom of the fuel canister. Only when taking it to pieces could it be seen that the alignment required correction.
>>  
>> On the chart above can be seen the mass loss line in black. The High zones have a different slope compared with the Low zone in the middle. The power curve (which is smoothed) shows there is only a small difference in power.
>>  
>> The fire started at High, turned it down to Low, then back up again after an hour. The total burn time was about 155 minutes. When it flamed out I left it for a while then dumped out the charcoal which looked like shrunken pellets. There was very little smoke from the char which when spread out, quickly extinguished. The char yield was 28% of the dry fuel mass.
>>  
>> Here is a picture of the data stream:
>> <image006.jpg>
>> It was a bit windy so the scale was shaking around but the fuel burned line (red) marches steadily up. Ignore the blue line. The green line is the 10 second burn rate detected by the scale, from -3 to +3 g.
>>  
>> Here is the stove:
>> <image007.png>
>> The plate with holes in it is a substitute for a pot, retaining the flame inside the chamber in spite of the wind. It has no effect on the mass burn rate. The lever under the handle controls the air supply which splits into primary and secondary after the regulator.  Paul Anderson reports the inside air paths are unconventional. It contains several ceramic components.
>>  
>> Regards
>> Crispin
>>  
>>  
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