<div dir="ltr"><div>Dear Ron and Stoves;</div><div><br></div><div>There are limitations about what I can say based on my trials because of the subjective nature of evaluation. Unless I am really lucky to hit on something strikingly successful, I think that my preliminary tests are best at identifying problem burners to be eliminated from more rigorous trials and expensive. Ultimately, a successful burner designs get incorporated into a real stove system that is subjected to quantitative testing for emissions and efficiency. That last step is not likely to be done by me.</div>
<div><br></div><div>For flames, I assess quality by the proportion of blueness vs yellowness, brighter yellow vs deeper yellow-orange flame (if comparing two prototypes side by side), ability of the flame to stay lit, ability for the flame to propagate across the burner's holes, stability of the flame's shape, symmetry of the aggregated flamelets, and flame height. </div>
<div><br></div><div>In my judgment, the burner with the best flame was the burner with the discontinuous annular ports for pyrolytic gas ("Retangular") which had blue flames at the base, and a bright yellow center. A close second was the burner with the concentrator below the secondary air ports ("ConcBelow"). I couldn't judge whether putting a cylinder into the center of those burners was an improvement or not. The burner with no obstructions above the fuel bed ("OpenChim") was intended as a control to see if the other burner designs interfered with gasification rate. Its flame had a light blue base and conical yellow center. Going into the soot tests, I ranked that flame as third.</div>
<div><br></div><div>The burner with the concentrator disk above the secondary air ports ("ConcAbove") had the tallest flame that was darker yellow when run next to Rectangular and ConcBelow. That type of tall, yellow conical flame has been reported to produce soot on the bottom of pots, so I judged it to not be as good at the other burners. </div>
<div><br></div><div> </div>
<div><br></div><div>The soot test, with a pot of cold water, is good at getting a better feeling for smoke production than judging smoke emissions by eye, especially because the pot-bottom accumulates soot over the duration of a burn. The conditions are also closer to real cooking. However, the soot test is a partially subjective evaluation of blackness. When it is used to compare a sequence of burns, it is reliable over a coarse scale of categories {clean, detectable, dusting, moderate, black}, so it is better at eliminating bad burners than at discriminating between good burners. There was a small amount of variability for any particular treatment that could be caused by variations in fuel quality, or ambient conditions of temperature, humidity, and air turbulence.</div>
<div><br></div><div>In my case, the soot test identified the ConcAbove burner as a bad burner that was "black" in five replications. The Rectangular burner was "detectable" in four cases, and "dusting" in a fifth. I could not discriminate between the other burners, because they were all "dusting".</div>
<div><br></div><div><br></div><div>My overall conclusion is that the Rectangular burner seems to outperform all the others. The ConcAbove seems to under perform all the others. "All the others" seem acceptable to continue testing, but I can't reliably rank them with the soot test and using my present TLUD. A larger TLUD may be a more discriminating test.</div>
<div><br></div><div><div><br></div><div>Just a note on some flickering in my video of flames: I am running my tests outside in a sheltered alcove, and the stoves are in a shield. However, there is still some ambient air turbulence that causes the flames to flicker. In some sense it is good to test in "cooking outdoors" conditions, because you get a sense for flame stability. </div>
<div><br></div><div>Cheers,</div><div>Julien</div>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, May 6, 2014 at 12:11 AM, Ronal W. Larson <span dir="ltr"><<a href="mailto:rongretlarson@comcast.net" target="_blank">rongretlarson@comcast.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid">Julien: cc list<br>
<br>
It seems A4 is a little better than A2 in terms of soot. How would you compare flame “quality" of A3 to A1? Or to earlier tests.<br>
<br>
In some of the earlier video, there were occasional “flashes” of light from both stoves in the evening video. Presumably not desirable. Where are those coming from? Might they have also been occurring in A3?<br>
<br>
Ron<br>
<div><div><br>
<br>
On May 5, 2014, at 8:27 PM, Julien Winter <<a href="mailto:winter.julien@gmail.com" target="_blank">winter.julien@gmail.com</a>> wrote:<br>
<br>
> Hi Stovers;<br>
><br>
> At the suggestion of Paul Anderson, I ran single tests on the burner with the concentrator below secondary air holes (ConcBelow), and the discontinuous annular (Rectangular) burner. In these tests I put a 2.5 cm diameter cylinder in the center of the burners to direct flamelets upwards in the chimney.<br>
><br>
> A pdf is attached. Photographic conditions were not ideal (nor was my old camera), but good enough to see how the flamelets were affected.<br>
><br>
> I can't say if the central cylinder was an improvement, because my soot test was not that sensitive. However, the central cylinder didn't appear to increase soot production compared to having no cylinder, nor did it slow down the rate of gasification.<br>
><br>
> Future, more detailed experimentation could include a central cylinder to see if it reduces the mass of soot produces, and increases the rate of heat transfer to the pot.<br>
><br>
> Cheers,<br>
> Julien.<br>
><br>
> --<br>
> Julien Winter<br>
> Cobourg, ON, CANADA<br>
</div></div>> <Test of Gas Burners on a ND-TLUD v0.04 Appendix.pdf>_______________________________________________<br>
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</blockquote></div><br><br clear="all"><br>-- <br><div dir="ltr">Julien Winter<br>Cobourg, ON, CANADA<br></div>
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