Reverse flow UDS?

[tmehlhorn]

Interesting idea matt. However i think the main problem you have here is that in order to fill the cooking chamber with smoke it will also fill the tube your smoke is coming from to. When it pushes smoke down far enough to get out of the exhaust at the bottom the smoke from the inlet tube would be down far enough to choke out the fire. Plus this would be too much smoke probably imo. Another idea of similar nature that might work, is to build a uds as usual but cut an exhaust valve just below your bottom cooking grate. This would fill the top end with lots of smoke and allow it to escape without getting low enough to choke out the fire. But once again the excess heavy smoke might be to much on the food.?

Not to say it wouldnt work just need lots of forethought in engineering. With what i said above your oulet not forcing too much smoke back up your inlet, choking out your fire, and getting a good even heat into the inner barrel.
Which commercial cabinet smoker are you refering to, would love to see a diagram of their workings?

[Phubar]

I'm with Colonel00....
I love drawings!

[Matt_A]

Originally Posted by woodbutcher1

Mat,not meaning to get you ticked off,this wheel works,don't try to re-invent it.

Won't get me ticked off at all... I know the UDS wheel works, but I'm always looking for interesting projects that are "different". Just my perversity showing, I guess.

[Matt_A]

Originally Posted by colonel00

I think it might work. One thing to consider is how much will the heat source actually heat the bottom of the cylinder which could potentially keep the air towards the top stagnant. Give it a shot. If you were closer I would love to help.

I was thinking about this while I was working on a my "real" work. I could see whee the convective radiation could cause a rising column of heat that would interfere with the smoke moving freely to the exhaust. Perhaps a offset heat shield to keep the direct heat away from the bottom of the inner cylinder might be called for.

The physics of this work because as the fire creates the updraft in the space between the cylinders, the air pressure will increase at the top of the barrel. The pressure will automatically seek relief, which is accomplished by going down the inside barrel and out the unheated exhaust stack. Thermal transfer is always from hot to cold.

[Babyboomerboy]

I say the only true way of knowing if your idea will work is to build it and try it out. Just be sure to take a lot of pictures so we can keep up with your plan. Good luck.

[tmehlhorn]

Well after looking for a few i didnt really find any cabinet smokers that were true reverse flow smokers. I did find some that said reverse flow, what i noticed is the fire was still directly below and allowed heat and smoke to still rise straight up to the food, the only thing i noticed was the exhaust line was lower in the smoker and not at the top.

Not sure if i was missing something if there is another cabinet smoker out there i was missing with a diagram please post. But if these are the kind you were refering to think they could be mimicked as in my cheesy 30 sec diagram below. Heat and smoke rise to the top and fill barrel before exiting through the exahaust below the food level but high enough not to choke out your fire. Hey i could also be nuts but this seems the most viable to get what i think your after.

[Matt_A]

tmehlhorn, I don't remember the maker, it was a couple years ago. The firebox was underneath with the heat riser being behind the cooking chamber and entering the cooking chamber near the top. The exhaust was near the bottom of the cooking chamber.

[bover]

Might want to check with Mr. Moocow. He built a very impressive vertical reverse flow that appears to utilize the same thermodynamics that you're proposing Matt. When you break it down, the only real difference is box vs. drum.

[orangeblood]

Originally Posted by Bbq Bubba

like putting the charcoal on the lid and the food in the bottom of the barrell?

funny!

[Teleking]

Originally Posted by tmehlhorn

Well after looking for a few i didnt really find any cabinet smokers that were true reverse flow smokers.

Pit Maker smokers

Cheers

[MG_NorCal]

With the right stack and lid, it should work, however a few thoughts:

Unless you insulate the outer shell, the reverse-flow design will be dramatically less fuel efficient.
Access to the cooking chamber will be difficult.
You’ll have to build an access door for the charcoal basket, which tends to make designs less air-tight.
Finding a cylindrical outer shell to contain a drum may be difficult. Making a double outer shell that will allow insulation will be even more so.

In short, the advantages of a drum are lost and you might as well go box-shaped.

[tim hawk]

the vault

[Wampus]

Originally Posted by Matt_A

tmehlhorn, I don't remember the maker, it was a couple years ago. The firebox was underneath with the heat riser being behind the cooking chamber and entering the cooking chamber near the top. The exhaust was near the bottom of the cooking chamber.

SORT of sounds like a Ole Hickory. Although the exhaust stacks are still at the top, the firebox is indeed at the bottom and isolated from the smoke/cook chamber. The smoke and heat come up the back of the smoker and then roll around the meat and then out, but IT has a round top, and I assume it helps the direction of the smoke/heat?

You know.....this WOULD help with that whole direct heat, nasty smell of grease on coals problem.

TRY IT.....and follow up here!

[Matt_A]

Originally Posted by MG_NorCal

In short, the advantages of a drum are lost and you might as well go box-shaped.

I agree, it was just one of those questions that popped into my head.... decided to see if anybody had tried it.

[Matt_A]

Originally Posted by Bbq Bubba

like putting the charcoal on the lid and the food in the bottom of the barrell?

What, you never heard of a Caja China? Nothing odd about the charcoal on top...