[Stoves] Small clean burning TLUD

Ronal W. Larson rongretlarson at comcast.net
Mon Nov 30 15:03:35 CST 2015


Crispin and list

	1.  I thought there was enough data here to learn something meaningful about the test, if you are interested in TLUD performance.  There is not. 

	 2.  Anyone wanting to know what was going on needs to know at a minimum the initial weight of wood and the final weight of char; neither is given.   I say minimum, because we also need those two energy densities - probably near 18 and 30 MJ/kg.

	3.  It is also necessary to know how much water was boiled away - or what ever other data measures you used to determine the cooking and thermal efficiencies.  Did this scale possibly measure the decreasing weight of water as well as decreasing weight of pellets?  Or how was water loss measured?  Or did this particular test not have a water loss component?

	4.  Can you supply these five or more numbers so I can check how you calculated the E3 entry of 13.06 MJ/kg?  I get an average release power level over the almost 10,000 seconds of about 1.1 kW if the pellets have an energy density of 18 MJ/kg and the 600 gm (10.8 MJ) weight loss is all in pellets  (1 W = 1 J/sec).  How is this data being used?  What portion of that 1.1 kW went into making char?

	5.  I deduce from the given data that the accuracy of the weight measure at these ten second intervals is appreciably worse than 0.1 grams (the variation between ten second steps in column D varies from zero to 2 gms).  I doubt the actual pyrolysis front movement varies that much.  So, can you describe that weight measurement system a little more.  You average over 2 minutes in one column, but the plotting gives three average points in that time span I think.  I’d say fewer than almost 1000 data points would be more helpful - as I believe there is some artificial variation shown in the top two curves, not seen in the bottom one.   

	6.   I’d also find it helpful to know how much change was being made during the run to either primary or secondary air.  All the graphs show more power level variation (especially in the first half of the test) than I would expect in a TLUD that was being left alone.
	
Ron

ps  To others - it is possible to change the scales (up to 1000 watts helps) to show more of the top curve - but this is just a scale difference from the bottom curve.    I couldn’t find a way to vary the number of points being shown.




> On Nov 30, 2015, at 8:11 AM, Crispin Pemberton-Pigott <crispinpigott at outlook.com> wrote:
> 
> Dear Friends
>  
> I reported recently a small stove that was very clean-burning and I was able to run a simple test on it a few days ago.
>  
> Attached is the performance in terms of mass loss, nominal firepower and average cooking power.
>  
> The cooking power was calculated from the average thermal efficiency, ignoring the first 16 minutes during which the fire was getting established. The cooking efficiency was 56.9% averaged over 83 minutes.
>  
> Pretty impressive.
> Crispin
>  
> <Small TLUD.xlsx>_______________________________________________
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