[Stoves] Conceptioal Errors and possible pitfals.

[Ron]

Crispin and list

See inserts below.


On May 7, 2013, at 1:35 PM, "Crispin Pemberton-Pigott" <crispinpigott at gmail.com> wrote:

> Dear Ron
>  
> >I am disappointed we have no section in 4.2.2 to look at.  
>  
> Protocol analysis is slightly more complicate than that.

    RWL1:  shall we best assume that we will not hear about 4.2.2, and should stop asking?

> 
> >I am no expert in this topic, but it seems to me that it makes no difference whether the reporting says 4.9 or 5.0.  
>  
> That is because you view the numbers are being very similar and you go on to describe the difference as 2%.
>      RWL2 :  Nope.  There are two 2%'s under discussion.  Mine was the difference between. 44 and 46% below.  I am advocating that if you think the  4.9 and 5.0 numbers is confusing, report both.

> > If the answer was 44%, have I a right to demand another test, since I thought it was going to be 46%?  Eventually there could be millions of dollars riding on this sort of 2% difference. (45% is the dividing line between groups 3 and 4).
>  
> When we are discussing conceptual problems, you cannot be distracted by the numbers, you must stick to first principles. The numbers will come later. You do not start by picking methods of convenience, you start by doing things correctly whether the numbers are similar or not.
    RWL3:  I am still waiting to hear the first  "conceptual problem".

>   
> >I care only that both numbers 4.9 and 5.0 are reported and the energies involved are done correctly. I care especially that energy in char is not treated as the same sort of loss as what slipped past the pot which started with 5 liters.
>  
> The step immediately after deciding on what the mass of water boiled is the calculation of the ‘specific fuel consumption’ based on that water quantity. If you divide by the wrong number, you get the wrong answer every time.
     RWL4:  So divide by both and the average and report all three.  I very much doubt the relative rankings of stoves by a tenth of a percent.  If you disagree, give us a numerical example that impacts relative rankings of stove types.


> If the 4.9 was instead 4.5, the error is much larger, do you agree?
   RWL5
>  
> >You ask at the end:   "Is this cognitive dissonance or conceptual error?"
> >I say this is neither.  The question is, did the test you described give a reasonably close approximation of heat transfer that was useful in separating stoves into four groupings.  
> 
> It is a conceptual error to use 4.9. If water is missing, then it was either boiled and evaporated, or else it leaked out. Water does not ‘boil’ by itself or get boiled with energy that did not come from the fuel burned. As any practical scientist will tell you, the mass of water boiled was 5 kg or 5 litres because it is a fact and not subject to interpretation.
>  
> >I suggest we have better things to than debate this sort of topic.  
>  
> I suggest you look a lot more closely at the concepts embedded in the WBT before sweeping anything aside.
>  
> The Simmering phase of the WBT (presently called the ‘Low Power phase’ as a way of evading the fact that the IWA participants called for and approved the removal of all simmering in stove tests) has a metric that is ‘specific’, meaning the emissions are given per unit of water simmered.
>  
> When simmering, the mass of water at the beginning and at the end is substantially different – often a litre. Here is an actual example: Beginning of simmering, 4.8 litres. End of simmering, 3.8 litres. Which number should be divided into the mass of fuel burned? Which should be divided into the mass of CO emitted? 5.0, 4.8. or 3.8? How do you get a specific emission number if the mass simmered changed during the evaluation? Is it even conceptually possible to get such a figure? What exactly is the aspect of performance being investigated when the question is being posed?
>  
> >An ISO process is underway.  
>  
> The ISO process has not yet commenced. One structure has been created. When it does, someone will form a committee and all interested countries will be invited to participate. If this does not happen you can expect to see resistance because the whole point of an ISO process is that the affected parties are consulted. There are 4 fast tracks for creating an ISO standard. If the consultation portion is omitted, you can expect there will be problems. There is at least $500m available for stove projects at the moment and no one wants any of it compromised by a controversial test method or questionable performance targets.
>  
> >We can point out big errors, but your example of 4.9 vs 5.0 doesn't rise to that level for me.  
>  
> That is because you are not approaching the problem conceptually and that is why conceptual discussion should take place before mathematical discussion (of which we have had plenty). If a lot of time is invested detailing the mathematics of an erroneous concept it will have been wasted.
>  
> >Put that in energy efficiency terms that matter, and we should all want to continue.  I repeat, though, that approach 4.2.2 is where the big league action (baseball jargon) now is.
>  
> Actually there is a lot more going on internationally than the discussion about 4.2.x. In fact there is very little discussion going on in open court about 4.2.x. There are a little groups working behind the scenes. In order to create some progress on conceptual matters and to garner public input on a real national standard I have been bringing questions to this forum to get ideas and concepts discussed because it is the largest. I thank everyone for all input on these issues. Some write privately of course.
>  
> As far as I know, only one national standard has been independently reviewed by competent experts and approved for comparative (not absolute) performance determination. I hope that will soon rise to two. The WBT 4.x.x is not one of these though it easily could be reviewed when it is ready.
>  
> Consider this: if the WBT is pressed into service as an ISO standard without being reviewed, some nation, wanting to know if it holds water enough to suspend their nation’s people from its beam, will have it reviewed. Suppose it contains significant conceptual, mathematical or procedural errors? What then? Word will get around. Other standards will be drafted and used instead. Why waste time?
>  
> What if it is culturally irrelevant? What if 90% of the cooking people do is not represented by water boiling and simmering (assuming they can keep the name ‘simmering’ out of the simmering portion)?
>  
> This is not a time for playing games. If you want to make comments on the validity of test results you have to understand the ideas and the performance metrics. Fortunately there are some very cool heads working on this right now.
>  
> Regards
> Crispin
>  
>  
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