Ron, The burner I am using is the burner that Belonio developed for rice hulls. I use the same number of holes and the same hole diameter as he proposed. I added a burner housing that reduces the length of the diffusion tail. But I do not think that the burner housing makes much of a difference until it is coupled with the radiant dome.
With his burner, Belonio reported an average time of over 8 minutes to bring a liter of water to a boil. Since my burner is a Belonio burner, since the diameter of my reactor is the same as his, I am confident that the dome allows the boiling time to be reduced by 50%. Last week I sent a video of the dome in operation to Belonio, and he was quite positive about this development. I plan to do more boiling tests next week with a proper boiling pot with a lid. I wonder how much of a difference a lid might make. I plan to use a pot with a whistle that will begin to blow when a certain pressure has been reached. When the whistle blows, I will stop my stopwatch. Otherwise I do not know exactly when to say that water has begun to boil. I hesitate to use a standard water boiling pot because the bottom appears to be too reflective. I need a boiling pot with a lid and a whistle that can adsorb thermal radiation efficiently. Also I wish I had a thermocouple that could withstand temperatures as high as 800 C. What I really want to test at this point is dome-shaped ceramic foam. Thanks. Paul On Sun, Mar 11, 2012 at 4:08 AM, <[email protected]> wrote: > Paul etal > > Nice short 13 second video. Very clear. > > Is it possible to repeat a timed boiling test with the only difference > being whether there is a strainer in or out? Might also try different > pots, artificially changing the pot height, etc Anything to give more > numerical values. > > This is is to more exactly quantify your earlier observation that the > input energy seemed to be about a doubling. > > Ron > > ------------------------------ > *From: *"Paul Olivier" <[email protected]> > *To: *[email protected] > *Cc: *"Discussion of biomass cooking stoves" < > [email protected]>, "Andrew Heggie" <[email protected]>, > "Crispin Pemberton-Pigott" <[email protected]> > *Sent: *Saturday, March 10, 2012 1:33:24 PM > > *Subject: *Re: [Stoves] radiant heat capture, total heat measurement > > Ron, > > This is not a very good video clip, but it does show the entire 150 > gasifier: > http://youtu.be/8IcXDAK37gA > This is a rough prototype made by hand. > The mass-produced product should look better. > > Also I do not envision that this gasifier be operated as a stand-alone > device. > For safety reasons it should be set within a counter-top enclosure, as > seen here: > http://dl.dropbox.com/u/22013094/150%20Gasifier/Jpegs/008.jpg > > Thanks. > Paul > > On Sun, Mar 11, 2012 at 2:48 AM, Paul Olivier <[email protected]>wrote: > >> Ron, >> >> I did yesterday an experiment with aluminum foil to reflect back up the >> thermal radiation emitted from the dome. >> The aluminum starts to wrinkle and crack well before the burn is complete. >> >> Also I tried yesterday a wire mesh of an aperture of 30 mesh. >> This did not work as well as what I am using now (a stainer that I bought >> in the market). >> I have yet to find the factory that makes this strainer, >> and I do not have the instrument that is needed to measure its aperture. >> >> Ron, I think that the foam that you have found offers the most promise. >> I am sure that this foam will deliver more radiant energy than stainless >> steel wire mesh. >> Also I hope to employ a type of funnel that would surround the dome and >> focus the laterally emitted thermal radiation toward the pot. >> Finally the pot has to absorb and not reflect. >> >> Thanks. >> Paul >> >> >> >> On Sun, Mar 11, 2012 at 1:58 AM, <[email protected]> wrote: >> >>> Andrew, Paul, Crispin, list: >>> >>> 1. The last several paragraphs below are coming out more negatively >>> on radiant heat capture than I think are appropriate. Remember, the >>> initial information provided by Paul Olivier on March 2, when he said: >>> >>> "When a wire mesh dome is placed on top of the burner and burner >>> housing, >>> this roughly doubles the amount of heat being transferred to a pot:" >>> >>> 2. I think this doubling has little to do with the exchange below >>> (and a few earlier that are similar). Radiant heaters are widely sold >>> because of their efficiency in heat transfer - in many cases involving zero >>> convection. Given we have only one (above) piece of data for one stove, >>> the chances are that a doubling is not the maximum we can achieve. >>> >>> 3. I would look at this as a conservation of energy problem. We know >>> that we can transfer more energy to the pot if the radiator is hotter. >>> There may be catalysts that we can employ. We know how to use reflectors >>> and obtain high absorption (and sometimes simultaneously low emissivity) >>> In my reading on ceramic foam, I found that some foam is being >>> employed so as to have gas combustion take place inside the foam!. >>> >>> 4. I hope that others can perform some experiments along these >>> lines. >>> >>> Ron >>> >>> ------------------------------ >>> *From: *[email protected] >>> *To: *"Discussion of biomass cooking stoves" < >>> [email protected]> >>> *Sent: *Saturday, March 10, 2012 3:31:17 AM >>> >>> *Subject: *Re: [Stoves] radiant heat capture, total heat measurement >>> >>> On Fri, 9 Mar 2012 12:25:49 +0200, Crispin Pemberton-Pigott wrote: >>> >>> >>...and passes visible light and higher frequency infra red from hot >>> bodies, >>> >like the sun, >>> > >>> > >>> > >>> >Most of it, the rest makes it warmer (absorbs). >>> >>> Yes that which it absorbs make it warmer but equally as a warm body at >>> equilibrium it will be re emitting longer wavelength IR. >>> > >>> > >>> > >>> >>but absorbs the lower energy infra red from cooler bodies like earth >>> and >>> >our bodies. >>> > >>> > >>> > >>> >Yes, and because it is warm, and active in the IR, it also emits IR but >>> with >>> >a low emissivity. In other words if you know the emissivity, you can >>> read >>> >the temperature with an IR gun. >>> >>> it is emitting a different (lower) frequency from which it has >>> absorbed. >>> > >>> > >>> > >>> >But more to the point I was saying that at a lower (non 90°) angle, it >>> >starts to reflect radiation from the top of the surface. Look at glass >>> at a >>> >low angle and it looks like a mirror. >>> >>> Agreed >>> > >>> > >>> > >>> >The point is that when reflecting heat, if the incident angle is past a >>> >critical value, it reflects pretty much all of it so the issues Kevin >>> >mentioned about the mirroring on the back don’t come into play. >>> >>> This depends on the refractive index of the two materials, going from >>> a lower to higher there is always some light transmission, the other >>> way round and you have total reflection, this is how a light fibre >>> works. >>> > >>> > >>> > >>> >Paul’s question was about reflecting the heat. So the principles are the >>> >reflectivity, surface finish, incident angle and emissivity. While a >>> stove >>> >may be good at sending IR radiation towards the pot, pots are not all >>> that >>> >good at picking it up, actually. Stainless steel pots are quite >>> reflective >>> >and do better picking up heat by convection. >>> >>> The major salient point is that radiation from heating something by >>> flame/flue gases is only ever going to extract a minor portion of the >>> heat in the gas stream. Consider a black body in the gas flow, it can >>> never be hotter than the gas flow downstream of it, as you make it >>> hotter it radiates more heat but the rejected gas flow is also hotter, >>> either way you still need to have the convection do most of the work. >>> AJH >>> >>> _______________________________________________ >>> Stoves mailing list >>> >>> to Send a Message to the list, use the email address >>> [email protected] >>> >>> to UNSUBSCRIBE or Change your List Settings use the web page >>> >>> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org >>> >>> for more Biomass Cooking Stoves, News and Information see our web site: >>> http://www.bioenergylists.org/ >>> >>> >> >> >> -- >> Paul A. Olivier PhD >> 27C Pham Hong Thai Street >> Dalat >> Vietnam >> >> Louisiana telephone: 1-337-447-4124 (rings Vietnam) >> Mobile: 090-694-1573 (in Vietnam) >> Skype address: Xpolivier >> http://www.esrla.com/ >> > > > > -- > Paul A. Olivier PhD > 27C Pham Hong Thai Street > Dalat > Vietnam > > Louisiana telephone: 1-337-447-4124 (rings Vietnam) > Mobile: 090-694-1573 (in Vietnam) > Skype address: Xpolivier > http://www.esrla.com/ > -- Paul A. Olivier PhD 27C Pham Hong Thai Street Dalat Vietnam Louisiana telephone: 1-337-447-4124 (rings Vietnam) Mobile: 090-694-1573 (in Vietnam) Skype address: Xpolivier http://www.esrla.com/
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