Putting my AA130 to use

 
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Lightning
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Post by Lightning » Tue. Aug. 09, 2022 3:35 pm

McGiever wrote:
Tue. Aug. 09, 2022 10:23 am
I feel for you bro!!
Love that...

Yeah sorry about your unfortunate learning experience there.... "Hey! Is there an easier way to get that dam ash sled outta there? What in tarnation were they thinking when they designed this unforsaken hunk of steel?!"


 
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Post by Retro_Origin » Wed. Aug. 10, 2022 8:26 pm

So rather than start a new thread (as I've been doing enough of lately!), I'd like to bring up the concept of heat transfer and maybe learn a few things.
My wife and I went to the pioneer tunnel this weekend (which was great) and I snooped over to look at the little steam engine they have there that they use for their train rides. The guy showed me the firebox and then I noticed the tube passageways for heat transfer...this sparked my 'train' of thought...the exhaust had to pass through those small tubes through the boiler to get to the stack. This design is also reversed (right?) as in the example of the really big boiler that Stoker Don posted a while back at the Direnzo breaker, where the water tubes were inside the firebox(?) to accept rising heat.
So 'laminar' flow is understandably the worst for heat transfer, as I understand. All AA and AHS owners are always pretty ecstatic about the effective heat transfer via the turbulence of exhaust gasses...but this allll has me wondering...
Is my Keystoker about the worst design for heat transfer since there is very little swirling action and the openings are medium-large?
Is the AA design even better because the burning coal bed also has direct contact with the wet walls?
Didn't EFM go from a 'tube' heat exchanger to a plate style? If so, why? (Duel fuel purposes?)
How can fast moving swirling gasses be an effective way to transmit heat?
How is the AA design 'double exchanging', the fan draws through the center and then when it makes the 180 turn is when it finally hits the boiler walls, in the vertical swirl chamber there isn't excessive surface area for exchange, is there?

Anyway, just looking for some info/principles on turbulators, best type of heat exchange, good designs forgotten or old designs improved....all that jazz.

 
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Post by McGiever » Wed. Aug. 10, 2022 11:52 pm

Might be I’m not reading right, but in reality the AA and AHS are “all” wet wall until it passes by the “popes hat” into the stove pipe.

 
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Post by Retro_Origin » Thu. Aug. 11, 2022 7:54 pm

Hmm, maybe I'm conveying my info poorly. Basically:
1. Heating air, to pass the heat to water seems like having an undesired middleman who wants to keep some for himself.
2. Heating water directly and skipping (as much of) the air part would be desired (like the live coals against the firetube/wet walls)
3. Given the gas created from burning and the need for removal, passing the heat to the air and then to water is then employed, so the questions are then:
What are the best ways to get that heat from the air into the water, and why do some boilers (unlike the AA) not seem to try to have direct contact with fire-boiler walls but are just content to heat a big air filled space and expect that heat to pass through the wetwalls?

 
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Post by Rob R. » Thu. Aug. 11, 2022 8:00 pm

It is a balance of combustion efficiency vs. thermal efficiency.

 
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Post by lzaharis » Thu. Aug. 11, 2022 10:57 pm

Retro_Origin wrote:
Wed. Aug. 10, 2022 8:26 pm
So rather than start a new thread (as I've been doing enough of lately!), I'd like to bring up the concept of heat transfer and maybe learn a few things.
My wife and I went to the pioneer tunnel this weekend (which was great) and I snooped over to look at the little steam engine they have there that they use for their train rides. The guy showed me the firebox and then I noticed the tube passageways for heat transfer...this sparked my 'train' of thought...the exhaust had to pass through those small tubes through the boiler to get to the stack. This design is also reversed (right?) as in the example of the really big boiler that Stoker Don posted a while back at the Direnzo breaker, where the water tubes were inside the firebox(?) to accept rising heat.
So 'laminar' flow is understandably the worst for heat transfer, as I understand. All AA and AHS owners are always pretty ecstatic about the effective heat transfer via the turbulence of exhaust gasses...but this allll has me wondering...
Is my Keystoker about the worst design for heat transfer since there is very little swirling action and the openings are medium-large?
Is the AA design even better because the burning coal bed also has direct contact with the wet walls?
Didn't EFM go from a 'tube' heat exchanger to a plate style? If so, why? (Duel fuel purposes?)
How can fast moving swirling gasses be an effective way to transmit heat?
How is the AA design 'double exchanging', the fan draws through the center and then when it makes the 180 turn is when it finally hits the boiler walls, in the vertical swirl chamber there isn't excessive surface area for exchange, is there?

Anyway, just looking for some info/principles on turbulators, best type of heat exchange, good designs forgotten or old designs improved....all that jazz.
======================================================================================================

The folks at All Canadian Heaters take thier example from Canadian Pacific steam locomotives with a vertical fire tubes and spiral diffusers to make the coal and flu gasses burn more effectively.

The Pikes Peak and Mt. Washington steam powered rack locomotives have vertical boilers.

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Post by tsb » Fri. Aug. 12, 2022 6:43 am

You mean sorta like this ?
100_3174.JPG
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Post by Retro_Origin » Fri. Aug. 12, 2022 11:23 am

Rob R. wrote:
Thu. Aug. 11, 2022 8:00 pm
It is a balance of combustion efficiency vs. thermal efficiency.
This is very helpful, thanks Rob!
tsb wrote:
Fri. Aug. 12, 2022 6:43 am
You mean sorta like this ?
100_3174.JPG
Ok yeah, are you fabbing this up yourself? Or is that an existent boiler?

It's easy for my mind to grasp how slow moving 'laminar' (?) flow air won't want to transfer heat because it will develop a cooler outside and the core of the air will remain warmer, but how does speeding up the airflow with turbulation really do anything different? Now the time the air is exposed to transfer surfaces has dropped, even though you're introducing more 'sides'/regions of the air to the transfer surface...

 
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Post by McGiever » Fri. Aug. 12, 2022 11:45 am

Perhaps turbulation aided in better fuel combustion beyond the fire pot. As well the turbulation causes heat to be scrubbed better along the fire side of the wet wall tubes. And remember with water circulation there is more scrubbing on inner wet walls as well.
After all what fuel/heat didn’t leave by way of the stack must of been captured in the heated space, no?

 
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Post by tsb » Fri. Aug. 12, 2022 12:03 pm


 
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Post by Retro_Origin » Fri. Aug. 12, 2022 12:52 pm

tsb wrote:
Fri. Aug. 12, 2022 12:03 pm
Retro

Sounded Easy at First
Pretty sweet! That's every man's dream! Was there any noticeable heat transfer difference than from previous boilers you've dealt with? (as in, were you burning significantly more or less consumption, or maybe stack temp vastly different) I know my friends Harman stovepipe was cool enough to leave my hand on for good, probably less than 140! Although that's a smaller unit than my boiler...
McGiever wrote:
Fri. Aug. 12, 2022 11:45 am
After all what fuel/heat didn’t leave by way of the stack must of been captured in the heated space, no?
Right but since that's not really measurable by me...my questions aren't really directed at "how can I get the most out of my coal" but rather, "what are the principles for best heat transfer, and why do different manufacturers seem to be taking significantly different strategies?"

 
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Post by tsb » Fri. Aug. 12, 2022 1:03 pm

Retro
It's been a good little boiler. Can't say if it's better or worse than other designs. I think coal quality is the most important factor. I burned it year around a couple of times and I felt that it was a waste of coal for just the two of us.

 
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Post by Lightning » Fri. Aug. 12, 2022 9:35 pm

Retro_Origin wrote:
Wed. Aug. 10, 2022 8:26 pm
Is my Keystoker about the worst design for heat transfer since there is very little swirling action and the openings are medium-large?
I imagine the Keystokers all have a similar design. So if yours is like my uncle's, the exhaust has to leave the burn chamber towards the bottom. This design exploits natural convection in it's favor. The hot gases off the burner rise and give up heat to be able to sink and exit at the bottom. With this concept in mind, I added an exhaust gas diverter to my handfed Clayton. The proof that it worked was in the numbers. It lowered the exiting flue gas temp and increased the stove temperature. So no, I don't think it's a bad design at all. A bad design would have the exhaust gases go straight up and out.
Retro_Origin wrote:
Wed. Aug. 10, 2022 8:26 pm
Is the AA design even better because the burning coal bed also has direct contact with the wet walls?
Better? I would say no. The radiated heat from the fuel bed is still accounted for whether it's in direct contact or not. The advantage with it being in direct contact is that the walls would stay cleaner. In a big box design with slow moving gases fly ash has an opportunity to build up and insulate the heat transfer surfaces. I would do a quick go over with a wire brush at almost every tending to keep the interior walls clean on my Clayton.
Retro_Origin wrote:
Wed. Aug. 10, 2022 8:26 pm
How can fast moving swirling gasses be an effective way to transmit heat?
Turbulence and keeps the transfering surfaces clean.
Retro_Origin wrote:
Wed. Aug. 10, 2022 8:26 pm
in the vertical swirl chamber there isn't excessive surface area for exchange, is there?
That's more fore cleaning dust and particulates out of the exhaust stream so your stove pipe and chimney don't get clogged up. But it does double duty with additional heat transfer area before leaving the boiler

 
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Post by Retro_Origin » Fri. Aug. 12, 2022 10:39 pm

Great stuff! So things I learned that I didn't think so much about, boiler designs have to go beyond heat transfer...cleanliness (dirty surface area will short circuit even a good design), combustion efficiency and some of the other things mentioned play higher roles than I initially thought.

And please don't anyone think I'm knocking or trying to disprove my keystoker, but would you rather have a boiler that looks like a bank safe or one fresh out of Willy Wonka's factory? Click, per clunkity, chick chick, wheez, whirrr, bzz..........a little sci-fi maybe...but from the 50's? That makes it steampunk! Can't wait to fire it up again! Bring forth winter!

 
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Post by Retro_Origin » Mon. Nov. 07, 2022 12:01 pm

Taking advantage of the warmer weather to try to get the axemen into the basement before winter!
How much does the boiler section weigh again?

Wire wheel and a super quick paint job on the base, will give it a real coat later but I had a can and figured I’d just get something on it
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