[Stoves] A call to stop using the WBT

[Andrew Heggie]

On 30 January 2018 at 21:25, Crispin Pemberton-Pigott
<crispinpigott at outlook.com> wrote:

>
> The energy value of the char has NEVER been in doubt. What has been in doubt is the assumption that ALL char produced will be carried forward as fuel to be burned in the same stove on the next replication of the test sequence.
>
> In other words, the WBT treats all char as if it is unburned raw fuel energy that will be consumer by the same stove on the next burn.
>
> The test method you refer to that permits remnant fuel to be carried forward is the HTP as implemented in the CSI protocol. It applies not to char only but any remnant fuel. Where such fuel is left over, the first valid test of the stove is the second in a sequence because the first test doesn't have 'carried forward fuel'.


My point being it recognises the principle that some energy can be
left in the part burned fuel and char in a TLUD is little different
from that


> Some char making TLUD's can indeed burn remnant char. We haven't discussed this on this list because of the obsession by some with cheating on the efficiency rating. There are stoves that can gasify the char, a good portion of it, if there is new fuel mixed into it.

It certainly isn't cheating to wish to show the energy in the char
remaining after a TLUD burn should be allowed for other than as waste.
On the whole there is no wish to burn the char in the same device, for
various reasons. The only obsession involved is wishing to promote
TLUD stoves as a cleaner type of woodburning. talk of what is done
with the char postdates that.
>
> The CSI test has the calculation needed if the amount of residual fuel or char is less than 'all of it'. Some TLUD gasifiers can only handle, for example, 50% of the remnant char. From that second burn more char is collected to be used in a subsequent burn.

As I said there is little desire to reburn the char in the next test,
it was the principal of allowing for it that I was referring to.

> The observant cook may be aware of it, but the programme manager is not if they are given a WBT result. That is why Xavier is calling for any WBT test result not to be used for making financial or product selection decisions.

Which again raises the point that the testing is only done to decide
funding and those interested in promoting a particular stove favour
one result over another.
I suspect people Like Kirk Harris and myself would like to see a more
catholic test which whilst being a surrogate for cooking enables good
repeatability in comparing various design iterations.

>
>>Of course it does but I acknowledge there may be some difficulty in measurement.
>
> 'Difficult in measurement' cannot be used in a national standard.

Maybe not but I'm sure we can get good practical estimates for my
purposes. In fact during these discussions on various tests I  begin
to wonder if you are asking for too fine a calculation and the effects
are only to be lost in the background "noise" from normal cooking
practicalities. No cook is going to be in a position to use a standard
fuel size, quality, calorific value or moisture content.
>
>
>
> Frankly, this matter is treated as if it is academic and of little consequence

See above it may well only be that for a small scale stove developer,
you are aiming for the big buck stove programme.

Andrew