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Post by chozen on Sept 25, 2022 19:17:55 GMT -8
I have been wanting to build a DSR2 in my kitchen as a combination cooktop, oven and heater. If I viewed the design correctly. it uses a ceiling mounted exhaust for the batch box. I am also working under the idea that a hotter temperature for secondary air is better. If this is actually the case then a larger heat transfer surface could aid in achieving that increase in heat. A layer of sheet metal, added just below ceiling level and opening at the front to allow air intake, could be formed to provide a venturi around the opening in the ceiling, and this would heat the secondary air, regardless of the burn type. I made a sketchup drawing to convey my idea. It just portrays the ceiling and metal sheet, without the exterior walls. (first time trying to post image.) secondary air
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Post by peterberg on Sept 26, 2022 1:18:44 GMT -8
As I see it, you are actually planning to build a DSR3. Which differs a great deal from the DSR2. The DSR3 is the only one sporting a port in the ceiling. Your assumption that the hotter the secondary air the better is a false one. What's more, this core doesn't have a guided secondary air provision, at all. All the air is coming in through the upper half of the door frame. Heating the combustion air up means it'll expand, quite a lot in fact. Bringing the air temperature up to about 420 ºC (788 ºF) will result in an expansion rate of 100%, i.e. the total volume will be twice as large. Making it even hotter means the content of oxygen in the total volume of hot air will be lowered even more. The overall effect is that one have to transport a huge volume of hot air through a combustion system in order to get enough oxygen in for combustion of the fuel. This isn't beneficial, more of the unburned gases will be blown away before there's enough oxygen present to combust it. Please read my post about this same problem, regarding the same DSR3 core. donkey32.proboards.com/thread/3710/dsr1-vortex-aspects-dsr3?page=12In short: just warming up the secondary air is OK, to a degree. Making it scalding hot isn't, rather the contrary. All that's needed is already done in the design, what you propose is already tried and turned down.
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sertus
New Member
Plato is dear to me, but truth is even dearer to me!
Posts: 20
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Post by sertus on Sept 27, 2022 4:01:09 GMT -8
Dear Peter! Forgive me for using this very personal address, but it shows the deep respect I have for you and your work on this forum! To avoid the problem of a large increase in the volume of the hot secondary air, I thought of doubling the size of the space through which it enters. After reading your last post, I also saw another way to solve the problem - partially isolating the channel through which the secondary air enters. In cars, additional cooling is used to cool the air heated by the compression from the turbine before it reaches the engine cylinders. In the stove I built, the secondary air is heated by the hearth below and the secondary chamber above. Visually, the stove burns well and beautifully with the secondary air valve open, but what you wrote and the logic suggests - either a larger volume of heated secondary air or cooler secondary air is needed to maintain the amount of oxygen necessary for post-combustion in the secondary chamber . There is such a dialectical law: "The law of unity and struggle of opposites. At the heart of development may be found the opposite beginning, whose struggle leads to the development of energy and is the stimulus to movement.' I insulate the secondary air duct so that it is cool and saturated with oxygen. I insulate the hearth and secondary combustion chamber so that they are as hot as possible and ensure optimal temperatures for oxidation / combustion. Dear Peter, You are an inspiration! Be healthy! Stefan
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Post by chozen on Sept 27, 2022 7:05:23 GMT -8
Ok, thank you Peter for answering my questions, and correcting my faulty guesses. And yes I was looking at a DSR3 and also the vortex. But I looked at so many designs that I misremembered.
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Post by peterberg on Sept 28, 2022 1:00:34 GMT -8
Dear Peter! Forgive me for using this very personal address, but it shows the deep respect I have for you and your work on this forum! Hi Stefan, I won't object to such a personal address when followed by such a gracious compliment. This one in particular is a good contender for to put in a nice frame and to hang it above my bed.
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