[Stoves] A call to stop using the WBT/ Boiling Time Factor

Tue Jan 30 03:08:58 CST 2018

This text is copied from my homepage:
https://www.biocoal.org/water-boiling-test-btf/

Water Boiling Test for cooking stoves - using the "Boiling Time Factor" / 
BTF

I want to make a proposal for a new Stove-Testing-Concept using the 
"Boiling Tine Factor" (BTF)

In a word: You use the size(number) of surface of the temperature curve as 
an indicator for the quality of the stove!
This means a simple "number" stands for the quality of the stove!

This number I call " BTF=boiling time factor "
I can draft a curve of the temperature over time. And i take into account 
the surface of the temperature curve above 80°C This is normally the 
temperature which is helpful for cooking.
The temperature is taken every 5 Minutes. The test goes over a period of 2 
hours. All the fuel is used during the first hour. That means that after 
the end the second hour- all the fuel is completely burned.
No need to search for left-over pieces charcoal- like in other testing 
procedures.

What's the idea behind this stove testing method?
I worked with fuel saving stoves in 1982 and 1985. I always disliked the 
ARLINGTON STOVE TESTING PROCEDUREs from 1982 because it means:
stopping the fire, weighting the charcoal, starting the fire (continuing) 
the fire from new.
Especially for larger community stoves with bigger fire I really found this 
method improper.

The BTF procedure takes into account:
* if the stove is a low-mass or a high-mass stove.
* It takes into account if the stove heats up quickly
* It takes into account if the stoves keeps the heat after the fuel is 
burned. (Also the chimney quality/damper effectivity).
This is because no fuel is added after one hour- during the 2nd hour. A 
quick drop of temperature (smaller surface) indicates a not-so-good stove.
If the temperature is kept for a while (= larger surface of the curve above 
the purple 80°C line) this gives an indication for a good stove.

So once more:
1) The stove testing times goes over 2 phases: One hour of heating and one 
more hour when no fuel is added.

2) You start to make a quick fire and reach the boiling point quickly. 
Afterwards the fuel is evenly distributed to be burnt for the remaining 1st 
hour.

3) The amount of water boiled should always be the same (2 litres for 
family stoves, 15 litres for community stoves).

4) The fuel is taken by volume (e.g. an empty can of about 1,5 litre) but 
the weight is also excactly noted. (1,5 litre for family stoves, 11,5 
litres for community stoves, but details on the volume and weight of the 
fuel still needs some re-thinking).

5) The water evaporated is measured in case a "Percentage heat utilized" 
figure wants to be calculated.
However the objective of the BTF is not to evaporate water- but to heat up 
water quickly and to keep it up hot above 80°C over an extended period in 
relation to
-a fixed amount of water and - a fixed amount of fuel.

Calculations:
There is no need to use integral calculations for finding the "surface 
above 80°C", simple use this formula: add up all temperatures minus-80°C 
every 5 minutes. (Only count the temperatures which are above 80°C). The 
first and last temperature number needs to be taken as 1/2.

Sample: 20min= 85°C, 25min=96°C, 30min=97°C, 35min=96°C, 40min=95°C, 
45min=96°C, 50min=93°C, 55min=96°C, 60min=92°C, 65min=91°C, 70min=90°C, // 
75min=89°C, 80min=87°C, 85min=84°C, ,
BTF, Boiling time factor: 5*1/2 +16+17+16+15+16+13+16+12+11+10+ 9+ 7+ 4*1/2 
= 162,5 = ~163

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20180130/e542cf7d/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: WQcyFbB9.png
Type: image/png
Size: 222962 bytes
Desc: not available
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20180130/e542cf7d/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: R3cb4eB2.png
Type: image/png
Size: 140569 bytes
Desc: not available
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20180130/e542cf7d/attachment-0001.png>