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Post by bidouille on Jun 2, 2016 7:48:42 GMT -8
hi yasintoda , you' ve got to read in fench : la combustion du bois sera complète avec un apport d'oxygène , et dans des ciconstance spécifique, et entre parenthèse il faut comprendre qu'a lorigine d'une combustion il y a le triangle du feu qui comprend : ignition + carburant + comburant
soit:"étincelle + bois + oxygène de l'air "
ce qui en gros dit qu'en plus d'avoir du comburant ( oxygène ) il faut une ignition et pour une bonne combustion du bois et de la chaleur, le tout formant justement les circonstances spécifiques metionnées plus haut .
Il en résulte une formation de chaleur , de CO2 et de l'eau ( si et seulement si la combustion est complète ) , j'ajouterais qu'il y a aussi création de NOX en fonction de la chaleur ( entre 800 et 1100 °c le taux de NOx reste bas , à 1200 °c il commence à etre bien haut (cf flamme bleu sur bruleur fioul par recirculation de l'eau qui refroidis la flamme et permet d'avoir des taux de nox bas ) .
I just try to help translation into french and i make a small addition for the result of the théorical complet combustion , ( théorycal combustion is ; water +heat + Co2 ) but N ( azote ) under hot heat make NOx ( 78 % of azote in air = gas ballast + 21 % oxygene + 1 % rare gas =100 air ) .
Burning between 800 °c to 1100 °c is good after that NOx ( No and No2 ) are created at hight level ... and not to forget particuls ....
So complet combustion is : water + co2+heat + Nox + particuls
for the amounts of calorie into the vaprisating phase of water is 2259 Kj/Kg and for boiling water from 0°c to 100°c that's take 4.18 Kj/Kg.kelvin
Q=m*L with "m" is the mass in kg and "L" is the latent heat of the element ( here is water ) in kg
hope that will help a little
see you and thks for all your work
Fred
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terry
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Post by terry on Jun 2, 2016 11:57:53 GMT -8
Point D shows where water (at 100 degrees) is converted to steam (at 100 degrees, the same temperature), and the huge amount of energy required to do so is seen, much much more than the energy required to take it from 0 degrees to 100 degrees (line C).The above is not very clear, could you use other wording? As I understand it, it costs a certain amount of energy to take the water from 0 to 100 degrees. Then, to get it from 100 degrees to steam (the phase change) there's a huge amount of energy needed to achieve that. Maybe specifying the amounts would help? Haha, that was the main reason I used the graph, so I DIDN'T have to work out actual numbers! I had in the back on my mind that it took *roughly* ten times as much for the phase change as it did from 0-100, so a quick google found me the graph. It seems I had overestimated (or badly remembered) that figure, it does not look like ten times in the graph, but it does show that is is very much more. And sadly, I think for a LOT of people-tho perhaps not in the type interested enough in this field?-the concept of phase change would be hard to grasp, ie no temperature change yet huge amounts of energy required to cause the phase change. SOOoo many people tune out of science during school, absolutely no idea why, fascinating stuff! Anyway, I'll quickly try something else, maybe then between the two you might be able to mash them together for something you think works.
'The graph shows how the temperature of water rises as energy is added. (it starts from below freezing point which we will ignore. Unless the wood you use is itself below freezing!) As energy is added (the horizontal axis), the temperature rises along the straight line C, for every 'bit' of energy added there is a corresponding rise in temperature which is why it is a straight line.
When the water reaches boiling point (100) it no longer gets any hotter (seen by line D, it is horizontal even tho energy is still being put into the system) During this stage, the energy being absorbed by the water is not making the water any hotter, but rather is making the water change from 'liquid to gas', and this takes place with no change in temperature. Line E will ONLY begin once all of the water has become steam.'
Real dummies explanation, probably overkill but you can mash them together as you see fit.
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terry
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Post by terry on Jun 2, 2016 12:33:43 GMT -8
Hi Terry, I'm working on the french translation and I came across the following sentence you wrote : "Wood combusts completely with oxygen under specific circumstances (heat and ignition source), resulting in heat, CO2 and water." The words in parenthesis are not right in my opinion because they imply that heat and an ignition source are enough to make a complete combustion, but maybe I misunderstood the sentence. What did you mean ? thanks ! Yep, good catch, been meaning to fix that one too. It is called the fire triangle, ![]() Plenty of stuff on the net www.bbc.co.uk/education/guides/zqd2mp3/revision/3You will see later during that page (?) that a number of times I used phrases like '...(recall the three conditions needed, heat fuel and oxygen)' or similar. So in parenthesis is kinda right, but a bit odd. I think I was trying to say we need to start it, hence ignition source, once going as it is exothermic it maintains itself and grows. Ok, so lets fix it once and for all. "Wood combusts completely with oxygen under specific circumstances (heat and ignition source) resulting in heat, CO2 and water. Even kiln dried wood contains some moisture, and the chemical reactions in the fire have water as a product and so water is naturally present in the flue from both sources. These same end products are found in natural gas burners. On the surface, burning wood does not seem too difficult, some small dry branches with paper, put a match to it and the fire is started."
The fire triangle shows the three things needed for a fire to start and keep going.
![]() [for some reason the image will not appear in the post, I see it whilst typing. Hmm odd. anyway, it is in the link above]
![]() The complete combustion of wood (which is made up of hydrocarbons) results in the following
the hydrogen atoms combine with oxygen to make water vapour, H2O
the carbon atoms combine with oxygen to make carbon dioxide, CO2
the maximum amount of energy is released
These same end products are found in natural gas burners.
Lessen or remove on of the sides of a triangle then combustion will not be complete combustion but rather incomplete combustion. Water vapour and carbon dioxide are still produced, but two other products are also produced:
carbon monoxide, CO, a colourless toxic gas
particles of carbon, which appear as soot and smoke, and which cause breathing problems
On the surface, burning wood does not seem too difficult, some small dry branches with paper, put a match to it and the fire is started.' I THINK that all ties in now, no mention of water in the wood here, that comes later in the *, and I think it is self explanatory when it does appear. Boy, you change one tiny little thing and look what happens!!! Anyway, just hold off until peter gives it the go ahead, he may not want it growing this much! |
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terry
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Post by terry on Jun 2, 2016 12:56:13 GMT -8
Was a bit too messy for my liking, hope this is better.
The fire triangle shows the three things needed for a fire to start and keep going.
![]() [for some reason the image will not appear in the post, I see it whilst typing. Hmm odd. anyway, it is in the link above]
The complete combustion of wood (which is made up of hydrocarbons) results in the following: the hydrogen atoms combine with oxygen to make water vapour (H2O), the carbon atoms combine with oxygen to make carbon dioxide (CO2), and the maximum amount of energy is released.
These same end products are found in natural gas burners.
Lessen or remove one of the sides of the fire triangle then combustion will not be complete combustion but rather incomplete combustion. Water vapour and carbon dioxide are still produced, but two other products are also produced: carbon monoxide (CO), a colourless toxic gas and particles of carbon, which appear as soot and smoke. Additionally, the maximum amount of heat is NOT produced.
On the surface, burning wood does not seem too difficult, some small dry branches with paper, put a match to it and the fire is started. Once we have the fire, to have it burn cleanly takes just a bit more thought and effort. We need higher temperatures than the few hundred degrees of a small fire and we need to 'keep it under control', not let it grow excessively. By insulating the fire itself we keep the heat from the fire 'within the fire' which aids complete combustion and retains most of the heat from the fire within the combustion chamber. ' |
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Post by peterberg on Jun 2, 2016 13:25:05 GMT -8
Yes I know, lots of people get that hazy look when I talk about phase change. But I'd think this is better so I'll implement it in the morning.
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Post by peterberg on Jun 3, 2016 1:42:26 GMT -8
Terry, I think the corrections are done now. Just to be sure, read through it and see everything is as expected.
And yes, this correcting and re-correcting is getting quite messy at times, but the end results is what really counts.
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terry
Junior Member
Posts: 128
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Post by terry on Jun 3, 2016 2:45:45 GMT -8
Lessen or remove on of the sides of a triangle then combustion will not be complete combustion but rather incomplete combustion. one
It is not perfect, but I think it is acceptable. If it were to be published in a book, then yes further editing to fix little things would be needed. I think our/any energy to be expended would best be put towards any future additions.
It was kinda exhausting eh peter!!
Still and all, I think we can take a well earned break, congrats, you have been good to work with.
Will keep an eye on any additions in the future.
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Post by peterberg on Jun 3, 2016 4:12:26 GMT -8
Thanks, Terry.
To me, it is quite close to perfect. Remember, the English version is the source for other translations. We have three of those going on now, Lord knows what will happen in a couple of years' time. Unless Pablo and Yasin are producing lots of text I'll have some time to spend on bell sizing and exploded view thingies.
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Deleted
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Post by Deleted on Jun 3, 2016 23:05:57 GMT -8
Congrats to both of you, peter and terry ! Your break is without a doubt well earned !
@ fred : merci pour les corrections, je suis d'accord avec toi pour les NOx et les particules. Pour l'instant on se focalise sur la traduction et on y ajoutera des modifications après pour ne pas trop complexifier le travail de traduction.
thanks for the corrections, I agree with you for the NOx and the particles but the modifications will be added once the translation work is done, in order to simplify the process.
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Post by bidouille on Jun 6, 2016 9:17:40 GMT -8
Salut , hi You are welcome , yasintoda  , i've done nothing , so big thanks at all of you for this great work into this knowledge's door . have a good break . and i'll wait for next step like lot's of us ... if i can help i'll do, just ask , no problem ... |
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Post by peterberg on Jun 10, 2016 7:59:07 GMT -8
Terry,
An article about bell sizing is ready in draft (and dutch). What do you think of the idea to shift the whole of bell theory to the 'Building' section? The 'Applications' chapter will become overly large anyway.
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terry
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Post by terry on Jun 10, 2016 14:00:27 GMT -8
Terry, An article about bell sizing is ready in draft (and dutch). What do you think of the idea to shift the whole of bell theory to the 'Building' section? The 'Applications' chapter will become overly large anyway. hi peter well, all I can say is that it took a long time to load all the pics on the applications page!, so yes it may be getting a bit big. The question becomes, will it be out of order? That would require some sort of re-write or modification. But, as we only intend to do this once then we'd better get it right and have a re-write if necessary. Both thee and me can have a think about how best to move it, and put the ideas forward tomorrow.....I have only just seen this and you no doubt are if not already in bed, soon to be. The reason for the change is back to my 'constant' harping on how people take in knowledge, so to have a section all about sizing of bells and not explain what a bell is etc until much later would not be good. In any case, there exists sentences like ' There are rules of thumb to come later that allow us to know the size of the bell that relates to the size of the combustion unit. At all times there must be a certain temperature in the exit flue (roughly 80-100 C / 175-210 F) in order for sufficient draw to occur. In other words, we cannot have cooler than ambient air as the flue temp.' which would no longer make sense if the bell sizing came earlier. As usual, probably the best way to 'see' what to do is to see it written first, it is so much easier to take it in when viewed on your page. So perhaps do that anyway, in addition to you and I having a think about the re-order. Just 'get it out there', no doubt a bit of editing will be required anyway. I see you changed the pics, whilst not being a thing of beauty it does at least look a bit more presentable. How woulda thunk that lipstick on a pig DOES make a difference! Anyway, joking aside, do you agree the two pics should be swapped around? If you read the description ' The entry of the hot exhaust from the metal oil drum (at left) can be seen to enter the single skin bell about halfway up', that particular sentence applies to the pic further up the page, not the one just above that description. If you want to keep those pics in that order, then maybe change that sentence along the lines of 'The entry of the hot exhaust from the metal oil drum enters the single skin bell about halfway up (seen clearly in the earlier smaller picture 'however far up') I'll leave the wording to you. My daughter surprised me and turned up unannounced last night, so we should get a start on the video. A bit of editing after that and we'll see what sort of product we get. So keep an eye on that in my other thread, I'll kind of slant the video with the purpose (in the back of my mind) that it might be useful in here somehow, along the lines already discussed. |
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Post by peterberg on Jun 11, 2016 0:19:17 GMT -8
Hmmm... My idea was to keep the bell theory and sizing together and shift this to Building. Maybe even split the Applications in two parts to prevent it from becoming too unwieldy.
But, no harm done, I'll get to translating first. Then you'll be able to see it through. I changed one picture in the Bell theory section.
The French translation is coming on nicely, there's work to do as well...
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Post by peterberg on Jun 11, 2016 7:43:42 GMT -8
OK Terry, I did the translation of Bell sizing, it is just between Bell theory and Three barrel batch rocket. Would you be so kind to cast a strict eye?
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terry
Junior Member
Posts: 128
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Post by terry on Jun 11, 2016 13:10:36 GMT -8
looks pretty good, so not too strict an eye needed this time.
'The size of a bell and how to calculate need some clarification, this aspect is also investigated by means of experiments. Most people suppose the heat extraction capacity of a bell is tied to the volume but this is not the case. Not the volume is determinative but the wall and ceiling area of a bell is taking up heat so this is where we need to look at. The shape of a bell is almost insignificant, as long as the gases are slowed down enough. When the bell is a factor 5 wider than the riser or the pipe through which the gases are entering this will be sufficient in a vast majority of the cases. More is better in this here, the more the gases are slowed down the better gravity has control over it. We just had to wait until someone wanted to figure it out.'
The size of a bell and it's method of calculation needs some clarification. Most people would suppose the heat extraction capacity of the bell is governed by volume, but this is not the case. Broadly speaking the governing factor is surface area, namely the walls and ceiling of the bell, so this is what is used in our sizing of the bell. The shape of the bell is almost insignificant, care only needs to be taken that the gases slow down enough and that undue friction is not created. A good workable minimum is 5 times the size [in any dimension??] of the entry flue for the width of the bell. In the vast majority of cases this will be sufficient, though more is better as the more the gases are slowed the better the separation of hot and cold gases.
'Klemen Urbanija from Radomlje, Slovenia found out after a lot of tinkering that a 15 cm (6") system with a single bell could comprise an inside surface area of 6 m² (64.6 sq ft), excluding the floor. The temperature of the exhaust gases were down to 60º Celsius (140º Fahrenheit). He built his experiment outside the house and changed it several times until the results were satisfying, then he tore it down and moved it inside the house. There this particular size yielded problems again because the chimney stack was built out of bricks. Which extracted heat itself and the draw wasn't sufficient so he was forced to adjust the size of the bell again in order to raise the exhaust temperature. Eventually, the whole thing ended at a size of 5.3 m² (57 sq ft), without counting the outside of the firebox and the floor of the bell.'
The correct sizing of the bell was hard won by experimentation, and like all open source projects contributions come from many different people. Klemen Urbanija from Radomlje, Slovenia found out after a lot of tinkering that a 15 cm (6") system with a single bell with an internal surface area of 6 m² (64.6 sq ft), excluding the floor, gave an exhaust temperature 60º Celsius (140º Fahrenheit). He built his experiment outside the house and changed it several times until the results were satisfying, then he tore it down and moved it inside the house. A new round of problems emerged due to the chimney stack being made of bricks, which extracted heat from the exhaust thereby killing the draw. This needed a new round of tinkering and rebuilding of the bell in order to raise the exhaust temperature and restore the draw. The final result was a figure of 5.3 m² (57 sq ft) of 'heat absorption area'. This is important to grasp, and once grasped it can be seen that the floor area of the bell will not be part of the 'heat absorption area' as the flue exits above it. Equally, if the firebox is built into the bell then the surface area of the firebox within the bell will not be part of the 'heat absorption area' as no heat is absorbed there. ['heat absorption area' got a bit messy there, if you don't think it works let me know]
'The term which is being used to indicate the inside area of a bell is ISA, short for Internal Surface Area. The difference between a steel bell which is shedding its heat immediatly and one that is storing heat in a stone or brick like mass is marginal as far as ISA concerns. My workshop heater (see article Three barrel batch rocket) is built out of three oil barrels which are together just as large as Klemen's masonry bell and bench. Both systems sports a comparable exhaust temperature.'
The term we use for the total area available for heat absorption within the bell is ISA, short for internal surface area. As noted, this does not include the floor area as that floor does not (directly) absorb heat. The difference between a steel bell which is shedding its heat immediately and one that is storing heat in a mass of stone or brick is marginal in terms of ISA. My workshop heater (see article Three barrel batch rocket) is built out of three oil barrels which together have the same ISA as Klemen's masonry bell and bench. Both systems have a comparable exhaust temperature.
'Scaling up of these numbers posed a long-standing problem which was finally solved in 2015. In that year the bell with two cul-de-sac benches was built during the MHA meeting (see article Bell with dead-end benches). The maximum ISA of a 20 cm (8") system and a masonry bell without chimney bypass turned out to be 9.4 m² (101 sq ft). The whole scaling system of the batch rocket is tied to the size of the riser and it turned out this can be done the same way. The cross section area of a 20 cm (8") diameter riser is 314 cm² (48.7 sq in), of a 15 cm (6") diameter riser 177 cm² (27.4 sq in). The cross section area of the first riser is a factor 1.77 larger than the second, so is the ISA of the respective bells. The consequence of this is that a 22 cm (8.66") system should be able to drive a bell with an ISA of 11.4m² (123 sq ft). And a 12,5 cm (5") system should be alright with a bell ISA of 3.7 m² (39.8 sq ft).'
Scaling up of these numbers posed a long-standing problem which was finally solved in 2015. It turned out that the same critical dimension used to scale the size of fireboxes up or down, the cross sectional area of the heat riser, can also be used to scale the bell ISA up and down from the base result determined by Klemen. 2015 was the year that the bell with two cul-de-sac benches was built during the MHA meeting (see article Bell with dead-end benches). The maximum ISA of that 20 cm (8") system and a masonry bell without chimney bypass turned out to be 9.4 m² (101 sq ft). The ratio of Klemen's heat riser to the MHA riser was 1.77, and the same ratio of 1.77 appeared appeared in both ISAs. We had found it!
As a consequence we can use the following 'table', and simply extrapolate or interpolate as required [any limits to this extrapolation??]
heat riser cross section 12.4 cm2 (5") ISA 3.7m2 (39.8 sq ft)
15 (6") 5.3 (57)
20 (8") 9.4 (101)
22 (8.66) 11.4 (123)
[I think that covered them all, check for errors. I didn't particularly and tidy up the table ]
'When the bell is fitted with a chimney bypass it could be larger than the figures mentioned here but it will make the construction more complicated, not to mention vulnerable to malfunction.'
When the bell is fitted with a chimney bypass it could be larger than the figures mentioned here but it will make the construction more complicated, not to mention vulnerable to malfunction.
actually, that did take longer than I thought it would!
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, i've done nothing , so big thanks at all of you for this great work into this knowledge's door .