[Stoves] Good enough stove?

Mon Nov 23 13:25:52 CST 2015

Dear Frank

There is a guy in India who is contributing to the work of Working Group 3 (Field Testing) who says he can give me an ultimate analysis of any biofuel based on 4 measurements. It reminds me of the work of Dr Tom Reed who proposed a general case for all biomass composition. On an ash-free dry basis, all biomass is substantially the same, and when factoring in the volatile %, a ‘pretty good guess’ can be made for the overall composition. In that case, using a formula I dug out of a mouldy book, I can calculate the energy content of the fuel by adding in the ash and moisture again.

How well this applies to dung and highly processed fuels, I don’t know. It will be helpful to compare the theory and practice of this and your (and other?) approaches. It will make the science of stoves more accessible.

I am offline for a little while.  We will pick this up again in Beijing.

Regards

Crispin

Dear Crispin,

Interesting. A single stove with different inserts and a collection of fuels that are often mixed. Lets not make it easy! 

Any combination of 1) fuels (and fuel mixes) and 2) stove inserts for any 3) task that actually works can be tested. For example if you fill a TLUD with cow manure it likely will not complete a task of boiling seven liters of water for an hour - so no need to test.

So gather your one stove with insert, your one fuel (or mix) and state the one task and test to make sure the task can be completed.

The fuel description is two parts:

1) the general physical description of type, size, shape, bark included, etc to gather fuel as close to that being used as possible.

2) then fine tune the fuel by normalizing energy values using the two volatile ones and the char (DAF) and moisture.

And make sure the task has a sharp end point when completed so to stop the clock.  

So if you have a calorimeter to get total energy and a furnace with pipes to determine volatile energy and can ash samples to determine char DAF content (without ash included) we are ready to go.

 Regards

Frank

Frank Shields

On Nov 22, 2015, at 3:30 PM, Crispin Pemberton-Pigott <crispinpigott at outlook.com <mailto:crispinpigott at outlook.com> > wrote:

Dear Frank the Patient

The stoves currently in use are burning everything. The description given by John Davies is apt: a box with a chimney. 

>The fuels you list are very different so do you have several stoves designed to burn each of the different fuels? 

Well that is the problem: no, there is a single stove. ‎ A possible high efficiency option is the use of inserts optimised for each fuel, but they are often burned together. For example people often mix dung and wood. Some efforts have been made to find 'more efficient' stoves which usually means extracting more heat without improving the combustion efficiency. I will check. 

>The fuels need to be prepared as they are likely going to be on site regarding moisture and size, densified (pellets or pressed into cylinders), split, ground etc. Any process that is likely to take place at the location in prep for the combustion apparatus.

This is how to do a contextual test in a lab. There is no need to drag the lab into the field if you know what they are going to do and use. 

The stoves are designed to heat and cook. And bake I think, at least some of them. The major issue I see is they are all similar to the Mongolian baseline stoves, which is to say, copies of a Russian portable wood stove. 

>Only the stoves that can actually use the fuel and expect to do a good job for the task intended. 

But we already know they are going to use all those fuels. Now what?

Regards

Crispin

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