[Stoves] Shields E450c as a way to test char-making stoves (attn: GACC testers)

[Ronal W. Larson]

Crispin and stoves list  (again ignored - why?)

1.  The "game"  I am playing is to ensure that charcoal-making stoves are treated fairly.  Saying that existing char at the end of a run has been "consumed" is not fair.

2.  Under a) - I repeat my original claim - you have no test in mind that will differentiate between char-making stoves.   If char is there, it has not been "consumed".

3.  Under b) -  The key sentences are your final two:   The direct cause is that the more char produced, the less fuel was claimed to have been consumed, which is clearly untrue. That is why the WBT was changed."       If char exists, the claim of less fuel is "clearly true",  not "clearly untrue".  Further,  the use of the formula A/(B-C) goes back at least to VITA days and is in there today.   On this main point under dispute, the WBT was NOT changed (thank goodness).  Or if I am wrong, please give a cite.

Ron


On Oct 22, 2013, at 4:02 PM, "Crispin Pemberton-Pigott" <crispinpigott at gmail.com> wrote:

> Dear Ron
>  
> I am not sure what game you are playing, or why.
>  
> a.       You have no test in mind for reporting on differences between char-making stoves.  They all achieve zero efficiency in your mind.
>  
> The efficiency is a stove is the work done divided by the energy in the fuel consumed.
>  
> b.      You believe the current 4.2.2 test to be erroneous, because it reports efficiencies using the A/(B-C) formula  (since C is energy in char and you won't measure that parameter).
>  
> That is quite incorrect. If you read the message previous to this I state quite clearly that there is no difference between the fuel consumption method proposed in the WBT 4.2.2 and the method I currently favour (SeTAR 3.052).
>  
> If you want to know the energy content of the char, ask.  The fuel consumption is expressed in a manner that speaks of its energy content.
>  
> Perhaps I should repeat that. The fuel consumption is expressed in the form of its potential energy production.
>  
> The system efficiency predicts fuel consumption. The WBT up to version 4.2.1 does not predict fuel consumption, hence it made erroneous comparisons of fuel performance.
>  
> You already stated the two methods for assessing energy consumption: energy in the fuel available and the net energy actually liberated from the fuel. One is analogous to the fuel consumption and the other is analogous to the energy efficiency and the heat transfer efficiency. In the latter two cases the CO and H2 production should be considered as they are combustion inefficiencies.
>  
> I hope that settles the matter. You cannot credit a stove that consumes fuel it happens not to burn. This applies whether it is CO, H2, char, char-in-ash, unburned N or S.
>  
> In particular I will continue highlight efforts to turn stoves testing for fuel consumption into a comparison of ‘energy consumption’ followed by a comparison of that energy calculated to be ‘equivalent dry fuel consumed’. It was that particular metric that has created all the misdirection in terms of comparative performance. The direct cause is that the more char produced, the less fuel was claimed to have been consumed, which is clearly untrue. That is why the WBT was changed.
>  
> Regards
> Crispin
>  
>  
> Ron
>  
>  
>  
> On Oct 22, 2013, at 3:08 PM, "Crispin Pemberton-Pigott" <crispinpigott at gmail.com> wrote:
> 
> 
> Dear Ron
>  
>     1.  Can you clarify your view on two points, which I take to be your viewpoints:
>  
> a.       There is no way to accurately test a char-making stove  (I say because you have not answered my requests for a test you would favor) .
>  
> It is very easy to test a char making stove. It has always been easy. There is nothing special or difficult about testing char making stoves.  Nearly every wood-burning stove that has ever existed makes some char. 
>  
> If we speak of fuel consumption, it is the raw fuel needed to complete a burn cycle. If there is fuel remaining that can be used in the next burn cycle, it is discounted from the raw fuel consumed on an energy content basis. What remains, whether fuel or not, that cannot be used in the same stove for the next burn cycle is considered to have been consumed.
>  
> If we speak of energy consumption, it is the raw fuel needed to complete a burn cycle expressed in terms of the energy content potential in that fuel, as received. If there is energy in the form of fuel remaining that can be used in the next burn cycle, it is discounted from the energy consumed. What remains whether fuel or not that cannot be used in the same stove for the next burn cycle is considered to have been energy consumed. The rating given is for the particular stove and the fuel needed for it to complete that burn cycle.
>  
> The emissions of PM and CO are determined and expressed on the basis of mass per MJ delivered into the cooking pots. This was agreed at the IWA meeting 18 months ago. The WBT4.1.2 has since been modified to suit this agreement.
>  
> b.      The present 4.2.2 WBT (Water Boiling Test), used by Jim Jetter and approved by the GACC,  which reports both amount and energy of produced char, is fundamentally in error.  
>  
> The WBT 4.2.2 used by Jim Jetter and approved by the GACC takes exactly the same approach to reporting the testing.  Fuel consumed is that necessary to replicate a burn cycle. We have been in agreement on this for more than a year.  
>  
> If one wants to know the energy content of the usable or unusable fuel or other materials remaining one is free to ask for such an analysis. The energy content of unusable fuel remaining does not affect the calculation of the raw fuel consumption. The fuel consumption is based upon the mass of fuel consumed but it is expressed in the form of Energy (MJ) in order to make possible comparisons between stoves that consume different types of fuel.
>  
> However the WBT 4.2.2 still contains fundamental errors of concept and execution in terms of calculating the energy content of fuels, the mass of water boiled, the specific fuel consumption, the average performance during the cold and hot start phases plus several other things.  The metrics for low power do not have a solid physical basis and are thus misleading.  The method of averaging the results of multiple test results is probably in error.
>  
> Is there anything else?
>  
> Regards
> Crispin

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