terry
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Post by terry on Apr 24, 2016 14:29:43 GMT -8
'This design is similar to the earlier with a separate top piece, the most complicated mold is the back wall which has half of the lower part of the riser incorporated. It is possible to get away without making a second dedicated mold to cast the combustion chamber sides if a "fill piece" can be sticked into the mold prior to casting at the spot where the port should be. In this manner the one mold can cast both sides, one with an exit to the port due to the fill piece put into place before casting, the other without an exit. The top part of the firebox is the same as in the straight design and the other lower half of the riser is a relatively simple mold. For better understanding of the layout there's an exploded view below.' perhaps 'placed'
Yes, I see now Peter where I got confused with the wording here. Thinking about it, we need two different inserts. Very roughly, we need a 'full' insert so that a complete cavity (ie the port) is formed, and a thinner insert (thinner by the same amount as the wall thickness) so that a full wall is formed at the same place. To give a full course on mold making on your site is obviously impractical. Can I therefore suggest adding something along the following lines?
'It looks very complicated, but with some careful inspection and thought it is entirely within a competent home handyman's ability. Although seemingly more complicated, these molds are assembled no differently than described in the "How to build" section. A coated plywood box with suitably formed pieces of extruded polystyrene (or other) to form the final shape.'
How about you add 'To many this might be the first attempt to think with 'negative spaces' and how to disassemble the casting from the mold. I do believe it is within the capabilities of a good 'backyard tinkerer' so fear not. It might be a very good idea to test your molds with much cheaper materials, such as plaster of Paris, or even a weak cement sand mix, before (potentially) wasting the very expensive refractory castables on a mold that might need modification before the proper end result can be obtained.' Or similar.
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Post by peterberg on Apr 26, 2016 1:12:44 GMT -8
Ok, done the addition and the correction more or less. I have to disagree with you on the fill piece or insert as you seem to prefer. All the blocks which form the inside of the casting will stay in place, only one block (might be wood) the size and shape of the port is sticked, glued or screwed in, just for the second casting. That is entirely possible because of the fact I situated the port at the very end of that mold.
I need to think it over whether it would be meaningful to write a short course on mold making, Peter style. A back burner item, for now.
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terry
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Post by terry on Apr 26, 2016 4:08:08 GMT -8
Absolutely no problem with you disagreeing peter, at times I welcome it as I fear 'taking over'. That you stick to your guns is great, it means you think for yourself and take ownership of what is your website, take on board what you think worthwhile and discard the rest. Having said that (haha!) I think we are arguing 'at the limits of translation', I get what you are saying and think it actually is what I am saying. It is the nuances that are letting us down now. Most important is that you keep going, we can argue the toss later. Even more importantly, I am waiting for the next installment so get to it!
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Post by peterberg on Apr 26, 2016 5:40:43 GMT -8
I am in the midst of writing some articles in Dutch now. Bell explanation and two heaters are ready. I have to deside whether start translating or do other heaters first tomorrow(ish).
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Post by peterberg on Apr 27, 2016 8:05:52 GMT -8
OK Terry, a chunk of text is translated. The first sentence isn't right, I can see that, hope you would be able and willing to read through it all and suggest corrections. Thanks The first real article in this chapter is about bell systems and how they work. batchrocket.eu/en
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terry
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Post by terry on Apr 27, 2016 12:11:06 GMT -8
Used applications Somehow this does not sound right. Again we know what you mean but hmm. But I am really struggling! Does this work? 'Real world examples'? Or 'some real world applications', or 'examples in use.' They feel clunky to me too. Not to worry too much right now, how about simply 'applications'?? It can be fixed/improved later after it is all done, could even be clearer then.
Preface
'In this chapter complete mass heaters and variants without mass which are built around a batch rocket core are coming to stage. Not every article is illuminated by pictures because those are often protected by copyright. But measurements and sketches could be translated to 3D drawings in SketchUp format.'......................................'to stage', did that mean (like in a theatre) an actor appearing ? Very poetic! How about (as a lot of new concepts are appearing that WE all are aware of but I doubt a newcomer has the slightest idea of) 'In this chapter I show what is actually done to create a completed space heater using the combustion cores introduced previously. The concepts will be explained as I go, but not all of these will necessarily have accompanying photographs if copyright restrictions are in place.' If you wish you could add your next sentence but (to me) it is kinda redundant because unless you do it (make the sketchup drawings) I doubt the reader will. Still, as always, your call. (unless, and I don't know how these things work, it is intended that people add their sketchup drawings to your site?? Is that what you meant?)
You then go on to bell etc. Again I suggest that what WE all accept as 'common knowledge' is not common to all new readers to your site. Or is it I wonder...maybe if you told us who it is you envisage would be your visitor?? If 'new people' will visit I suggest adding a bit more explanation, how about 'The true magic of this technology is realised once we couple the clean burn technology of the combustion unit/s covered previously with effective ways of harvesting that very clean, smokeless heat. This can be done in a number of different ways that allow us to have different applications. We can build a space heater for applications that require 'heat on demand', for example a workshop that is only occupied during the working hours. This type has very little mass but very high radiant output. For other cases (eg in a house) where long term 'constant heating' is needed we use much more mass that provides a lot of heat storage. These different approaches will be covered in this section.'
I guess it comes down to who is the audience. If the only people that arrive come from donkeys, or permies, these sort of explanations might not be required. You DO kinda explain all of the above when you introduced the bell and workshop heater, and is sufficient for the donkey and permie audience, but maybe a bit too sudden or a bit too much for the 'new guy'?
Bell theory
The word "bell" will be mentioned in this chapter quite often. In this article will be explaned what it is, how it works and what it is being used for. Just 'This article explains what it is....'
Workshop heater
Consisting of three oil barrels and a cast batch box rocket core. Very little mass, the core itself weighs in at 60 kg (132 lbs) heating up delay of this heater is extremely short as a consequence. How about 'The core itself weighs 60 kg (132 lbs) but as the three steel oil barrels have very little mass there is little delay to the heat output of the core, basically instant heat.' Or similar.
Bell with two benches
This has been a temporarily installment, built by a complete team in a little more than 3 days. Very interesting build, showed outstanding performance despite low expectations of some spectators. Is that needed? It sort of confuses the matter, or implies experimental in some way. In any case it is a bit clunky. If you want it in how about 'This was built during a workshop so not a permanent build and was built by......... A very......, it showed outstanding......'
'Bell workings, how and why' Maybe just 'What is a bell?'? Or 'The Bell. How it works and why'
To me, the next section needs quite a bit of work, and re-arranging. I am more than happy to give it a go but want to check that it is wanted. I know I have already suggested quite a few changes that possibly might not be welcomed.(?) There would be many more in this next bit. Luckily I got up very early this morning, and that means I can post this and probably catch you before you hit the sack. So I'll hold off doing anything on the next section till I get your response. Hopefully it is clear that I would not be offended in any way if you reject any of my suggested wordings or changes. But equally no point in doing the 'major work' on the next section if it is not wanted.
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Post by peterberg on Apr 27, 2016 12:40:29 GMT -8
Terry, I think our public is very diverse. Which means rocket people will read it but also complete novices. So I think it's of the utmost importance that all the information is there, clear and correct. Up till now I followed 90% of your suggestions so please, go ahead. Some corrections are good enough to plough back into the Dutch version.
I'll do the corrections tomorrow morning, need to go to sleep shortly.
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terry
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Post by terry on Apr 27, 2016 18:15:20 GMT -8
Terry, I think our public is very diverse. Which means rocket people will read it but also complete novices. So I think it's of the utmost importance that all the information is there, clear and correct. Up till now I followed 90% of your suggestions so please, go ahead. Some corrections are good enough to plough back into the Dutch version. I'll do the corrections tomorrow morning, need to go to sleep shortly. Ok Peter, thanks for the go ahead. Agree with everything you wrote, and thinking about Donkey or permie members, even from them (ie us) there are often still many questions. In other words, the more comprehensive and clear it is the better for all, new people or not. Hopefully I will have time now to complete this section, if not I'll come back to it later. As I will be changing it so much I thought I should at least give an explanation. Yes we have the normal language awkwardness at times, perhaps a few typos to boot, but 'educationally' I think there is a massive error in how it was put together. The word 'bell' in english ( have no idea in dutch) has no analogue at all with the usage of the word in this context. I even went as far as checking the dictionary (in case I missed an obscure definition) but no, the 'normal and standard' definition reigns. So the first para goes straight into how 'our' bell works. If you did not know what 'our' bell is, you could forgive the person reading it if they had a crazy idea in their head. 'The effect is simplest to explain on the basis of a big bell which is placed on the ground.' 'Hmm, what sort of bell, a huge one like in the cathedral bell tower? Does the metal it is made of matter? How big should it be, and where can I buy a second hand bell of that size anyway.' etc etc. Ok I laboured the point a little, but due to the person reading having NO idea of what a 'bell' is in this context, then very naturally his comprehension is zero. Which kinda defeats the purpose of an educational text. So, I will be re-arranging things a little and hopefully you approve and we end up with a comprehensible result for the newcomer. For example, you do not 'define' a bell until the third para ' So, a bell heater is a hollow space with an exhaust which is situated down low, often lower than the entry.' Whilst being late to the party (in the third para) I would argue that is an insufficient definition, or at least one that does not readily communicate itself to the new comer. I think you should provide your own, complete definition. Sure I could write something here, but you de expert anyway! It just needs to be kept in mind that a new person to this field ONLY has the definition of 'a metallic object that rings when struck' when he reads the word 'bell'. Using that defn. then nothing you have written makes any sense. As *we* are using it in an entirely novel way, WE need to provide this new and complete definition for them. Only then can you move on to explaining how the bell works. I started correcting some of the following paragraphs, but I think I would be best re-writing it and submitting it to you. That needs more time than I have this instant, so I will stop here. If I don't have anything tonight don't worry, I will get it done. There is enough here for you to chew on over breakfast!
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terry
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Post by terry on Apr 27, 2016 22:42:45 GMT -8
[assumption:a clear and understandable definition of a bell has been given as the first item in this section. That will either come from peter, or if he wishes I can add it later] So, having described what a bell is, it is simple to see how and why it works as well as it does. Hot exhaust gas from the combustion unit enters into the bell, and as we all know, hot air rises. As the bell is *very much larger* than the pipe feeding it with the hot exhaust, the hot exhaust does not rush through it as might be first assumed. As it enters the very much larger space of the bell it slows down immensely further allowing the principle of 'hot air rises' to take place. The hottest part of the gases rise to the top of the bell, and gives the heat it contains to the interior surface of the bell and in the process cooling, thus falling within the bell. As hot exhaust is continually entering the bell, an exit must be provided (in other words, the 'normal chimney flue'). This exit is usually placed as low in the bell as practical. The converse of 'hot air rises' is naturally, 'cold air falls'. It is clear then that the gases which do leave the bell and out the chimney are the coldest gases. In this manner we can easily, and successfully, 'harvest the heat'. The advantages of this is not hard to imagine, all anyone needs to do is recall any normal wood burning space heater and remember how hot the flue gets. In fact, it might not be wrong to say in a conventional wood heater it is the hottest gases that escape, clearly not as good a solution as is being presented here. A picture tells a thousand words, what a bell is and how it works can be clearly seen below. 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. Looking closely at the bottom right, we can see where the temperature measuring probe enters the bell and into the exhaust flue. The inside of the bell is nothing but 'space'. It does allow the hot exhaust to enter, slow down greatly, rise to the top of the bell and give its heat to the bell, cool and then fall down to almost the floor before leaving the bell via the chimney flue. (The use of metal oil drums will be explained in an upcoming section, for now simply grasp the bell concept and how it works) The first person to utilise the concept of bells to harvest heat was in 1910 by V. E. Grum-Grzhimailo, professor of metallurgy at the university of Saint Petersburg. Of course the simple description just above of how a bell harvests the heat does not reflect the true, more complex reality of what occurs. The simple description above was quite a static picture, the reality is that it is a constantly changing very dynamic system indeed. The internal walls of the bell do not 'only' trap the heat, the external walls of the bell radiate heat. At times the internal walls of the bell might get hot enough that they cannot absorb any more heat, and heat absorption will increase/be forced lower down the walls. As the heat carrying capacity of the bell is reached, the temp of the escaping gases will rise (as they can no longer give heat to the walls). So, a constantly changing set of forces/actions occurring, yet even so the exhaust gas will almost never reach the same temperature as the incoming gas. If the temperature of the exhaust gas is high enough, and the heat lost to the external world is wanted, then we can extend this idea of the bell by recognising that the exhaust of one bell can be considered as the heat input to another bell. This second bell works in exactly the same way as described above, the end result being that it's exhaust is lower than the temperature of the gases that entered it. This second bell concept is naturally more efficient (usually, ultimately it depends on what the flue temp is....if it is low enough with a single bell then the second is not needed as one bell has done the job). Adding a second bell could increase the efficiency of heat harvesting, but it also introduces greater complexity. 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 100 C) in order for the draw to occur. In other words, we cannot have zero degrees as the flue temp. An additional real advantage of the bell system is that it creates almost no, or negligible, friction or resistance to the flow of gases though it. That this is achieved with such a simple construction is an added bonus. By comparison, the German/Austrian way of building a mass/masonry heater uses a system of channels to give the heat to the mass. The surface area of these 'long' channels, coupled with the (relatively) small diameter of the channels themselves imposes much greater friction/resistance to the flow of gases. This then requires as a necessity that it be a very strong drafting system indeed in order to overcome the friction. In addition to all of that, we can see that ALL of the gases flow thru all of the system together, the hottest together with the coldest as the separation of hot and cold (as in the bell) has not occurred. The 'simple' bell system, as pictured above, is very effective but has a singular disadvantage, all the the mass is located within the single brick skin. This makes them 'large'. There are techniques available that can counteract that. Placing the combustion unit higher within the structure as opposed to floor level results in the storage of heat at a higher temperature because the gases need to sink lower than where the combustion unit is located. Additionally, internal structures (eg, columns) can be built inside the simple brick skin that can absorb, and then release later, heat. With such measures it is possible to reduce the size of bell needed using the simple 'single skin' method. All of the heaters to be described later are working bell systems in one way or another. One last comment on the system pictured above. It is an example of what might be called a hybrid, half way between a bell and a metal drum system. It shows the combinations available for the demands required. In the above, the metal bell gives off radiant heat whilst it charges the bell as it exits the house. The bell has a four hour lag, by that is meant the exterior surface of the bell reaches its hottest temperature four hours after the fire has reached its hottest temperature. It had to be absorbed and travel from the internal surface of the bricks to the external surface before it can radiate to the room. Instant heat from the metal oil drum, stored heat that is released slowly over night (or indeed until the next burn) from the attached bell. As a matter of interest, the exit temperature of the flue gases (measured in the centre of the gas stream) stay within a range between 50 -70 degrees celsius. No doubt some cups of coffee are hotter than that. [Note, that is my picture. I don't care if it is used, no doubt there is a better one available somewhere. I at least knew where to find it!! But I did think it essential to show a picture of a bell at least. IF that pic is useful, I would clean it up and take a shot from a more useful angle. We don't want people to think these will always be ugly!!]
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Post by peterberg on Apr 28, 2016 6:42:41 GMT -8
Terry, I've read it all and I see what you mean by readable text. I will use it, with minor alterations only. That picture is clear to me but I doubt it is clear to a novice so I'll search for another, more glamourous example. I would like people could picture such a thing in their own abode.
I'll come back to you when the definition is written and the changes are made.
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Post by peterberg on Apr 28, 2016 7:08:38 GMT -8
How about this as a definition?
"A bell heater has actually nothing in common with a church bell. The only resemblance is the high, generous space inside. It isn't a heater as such but rather a heat extractor, its workings are based on the buoyancy of hot gases. Made of steel, brick, refractory, cob or stone it is an enclosed space, the exhaust opening situated close to floor level. The hot gases can be produced inside the bell or in a separate enclosure."
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terry
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Post by terry on Apr 28, 2016 12:40:57 GMT -8
How about this as a definition? "A bell heater has actually nothing in common with a church bell. The only resemblance is the high, generous space inside. It isn't a heater as such but rather a heat extractor, its workings are based on the buoyancy of hot gases. Made of steel, brick, refractory, cob or stone it is an enclosed space, the exhaust opening situated close to floor level. The hot gases can be produced inside the bell or in a separate enclosure." Hmm, well in the very first part of this section we have 'The word "bell" will be mentioned in this chapter quite often' and the first explanation explains 'bell heater'. To many this may seem very pedantic indeed, but I do have a lot of experience with learning and what are the biggest barriers to learning, and frankly the biggest barrier, by far, are words and what they mean. This is so overlooked in society it almost beggars belief (and causes me to shake my head every day). I mean you'd think the education system would have grasped this but.....anyway, that is a rant for another day. An important term that needs to be understood is 'Bell'. It has become part of the language of building these types of heaters and as such its usage and meaning must be understood. Contrary to what might be expected, it has nothing to do with a church bell or any other bell of that nature. It is nothing more than a large enclosed space, meaning 'four walls, a top and bottom'. It can be any shape that works best for the situation, it can be constructed of any material that suits the purpose best, including steel/metal, brick, refractory, stone, clay dug out of the backyard mixed with straw. You can build for speed, you can build it for looks, you can build it for cheapness and each purpose has a range of materials that suit that purpose. When we put these two elements together, the combustion units described earlier coupled with a bell, we have made ourselves a bell heater. As you will see from some of the sketchup drawings we combine these two elements so that the very hot, very clean exhaust from the combustion unit enters the bell and 'allow the magic to happen'. EDIT I had to post that draft so I could see how it fits in with what I had written earlier, it is very hard to see earlier posts when replying. Anyway, you can see an assumption just above, that you will show some of those sketchup drawings to illustrate. A suitable photo/s would also be equally good. If something like that works, or the guts of it, then very likely we would not need the first sentence of what was written above, ie (argghh, now I am replying it is gone again!) Oh well, scrolling down...' So, having described what a bell is, it is simple to see how and why it works as well as it does. Hot exhaust gas from the combustion unit enters into the bell, and as we all know, hot air rises. As the bell is *very much larger* than the pipe feeding it with the hot exhaust, the hot exhaust does not rush through it as might be first assumed' etc etc. that can go, not needed, and it seems to flow OK from the explanation. I would keep it as a new para. hope that helps, as always feel free to edit or modify as you see fit.
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terry
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Post by terry on Apr 28, 2016 12:59:28 GMT -8
Terry, I've read it all and I see what you mean by readable text. I will use it, with minor alterations only. That picture is clear to me but I doubt it is clear to a novice so I'll search for another, more glamourous example. I would like people could picture such a thing in their own abode. I'll come back to you when the definition is written and the changes are made. that made me chuckle. Hey, at least my face was not in that picture eh? Again with seeing the posts whilst replying...anyway one thing I forgot was your very good point about the combustion unit can be external or internal to the bell. Maybe just tag that on the end of what was written, as we had just defined bell heater as the combination of the two elements...'The combustion unit can be external or internal to the bell.' hope that works
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Post by peterberg on Apr 28, 2016 13:07:57 GMT -8
OK, I have to assemble the pieces and read through it again. I'll hit the sack in a few minutes, staying awake and working untill the single digit hours doesn't do any good to readability of any article.
Have a nice day Terry, I'll get to it tomorrow (middle European time shifted to Daylight Saving Time). And thanks, I think this is an important article to get it right. There might be some more pieces translated for you to wade through as well.
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terry
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Post by terry on Apr 29, 2016 12:57:24 GMT -8
hey, up again early so you might catch this before sleep.
The main point right now is 'give me a day' and I should get to most of the new stuff.
I have a few points to raise, and will use this post as a 'marker' or 'placeholder'. I think right now you just keep writing, and maybe after all that is done we can look at some of these points and see if it would be worthwhile incorporating them.
First off, what occurred to me as I read the barrels was 'kinda half finished'. Sure, it is 'only' a workshop heater. Yes, I too at the moment just stack and lift out of the way to stock the fire Hebel blocks. And, you have seen the photo of mine, it does not scream 'finished and 'professional looking' or 'yeah, I am now certain I can convince the wife to have one of these in her house' haha. For now all of that is fine, but at some future stage I think some of the nicer (and there would be many) completed constructions should be part of the picture gallery. After all, 'any competent home DIY handyman' can build these, and quite a few of them surely do decoration/renovation work, so it should also be true that a 'very nice looking final product' is also within their capabilities. I KNOW I can, mine is a one season only, temporary construction to see if the size I have is sufficient for the job. Next years will be very nicely done.
Some other random thoughts. The video of your burn, some parts were extremely impressive. My favourite part was how the coals reduced down to nothing. magic. The shot of the riser with flames was also impressive, as they always are. But hey, I know that it was an internal shot of the riser, because I am quite familiar with the topic, but the new dude reading your site for the first time would be scratching his head because he would NOT know-and why should he?-that it as a switch to a shot of the riser. (a very similar comprehension problem to the earlier one of 'not defining bell'). I also noticed the way you started, and then stoked, the fire was (if I am remembering correctly) in direct contradiction of something you wrote earlier about a top down fire. I think that was in these pages. Again, (and you gotta know how people take in data) they are learning a new thing, they get told 'this is how you do it' and later in that learning get told something contradictory. They may not even consciously recall that it is contradictory, instead they have this hazy fuzz of 'huh, this does not make sense' and might not be able to put their finger on exactly why it suddenly no longer makes sense. [Yes, maybe I am labouring the point, but I think if I do then it becomes clearer how much of this is true or how it might be true. And if that is allowed, then if we are after an educational text then it makes sense to fix these easily fixed things]
As I said, this is a placemarker so these random thoughts that occur don't get forgotten.
I notice my photo was still being used, I guess that means it was useful. At some stage I will clean it all up and provide a better picture if you want to keep it in.
Another over arching thought...'WHY do we want people to read these pages?' I would presume because *all of us here think this technology is fantastic and should be adopted more widely* or something similar. So putting myself back into the shoes of the 'uneducated, but interested, newcomer' I don't think yet that 'This is why you should be interested' has been stated, or shown. This would be somewhere quite introductory, preceding (yet leading them to seek) the explanatory sections. In this youtube age I think the best way to do that is an informative, entertaining video. I envisage (as a film director haha) 'stack the fire. Start the fire. Go outside and film the no smoke produced. Show fire burn down. Show flue temp. No smoke, low flue temp shows very high efficiency. Show only four kg of wood heats house for x hours. Add very large solid piece of hardwood to glowing coals. go outside and show ten seconds of very light hazy smoke as the log catches fire.'
All edited so no waffling, perhaps no voice and any explanations done written, nice music as a backdrop. To me there is nothing more impressive than there being no smoke. Any woodburner KNOWS there is smoke, especially on start up. the other advantages, like lovely warm bell for hours on hours can never be known till you experience it. But ALL people who burn wood KNOW there is smoke. So I think that would be their hook, and they would then more avidly read the rest because 'They now know why they are interested'.
I am happy to give that a go. I'd probably do it for my own thread anyway, and if it looks useful for your purposes then all the better.
A question I have been wondering. About 'why bells work as well as they do'. I wonder if you (or others, it seems no-one else joins in this thread anymore) have any thoughts on this. I guess this applies to 'mass' in general, not only bells. I don't really like the barrel, I am certain I will not have one in the finished build. Yes, it is instant so that is good, but it is a 'harsh, angular, kinda nasty' heat if you follow. Nothing like the 'soothing, gentle' warmth from the bell. (see, I do have a bit of poetry in me!!)
I am sure it was on donkeys, somewhere there was a thread that went into radiant heat, and i recall there were some external links to discussion/explanation of the effectiveness of different wavelengths in radiant heat. From memory there were three (?) categories of radiant heat, with differing levels of comfort. I think they used Bolztmans law (or something) to do the calculations. dunno, 'near radiant', 'far radiant', things along those lines.
SOooo, long winded introduction over, sure the barrel gets very hot, throws off this harsh hot radiation that, quite literally, 'pushes you away'. (get too close to the barrel and you will see what I mean) OTOH, the bell never gets above 65 degrees (say), you can touch it, you can hug it, yet you are very nicely warmed by it. The question I am wondering then due to that temperature, and using Bolztmans law (if that was what it was) would the calculations of the TYPE of radiant (infrared) heat given by the bell fall into what they called 'the most effective/efficient' type of radiant heat??
In other words, yes the bell works as explained, stores the heat for long periods, yet I have never seen yet any investigation into the TYPE of heat it intrinsically gives off.
Anyways, food for thought.
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