New UDS design, should be more efficient.

Discussion in 'UDS Builds' started by stubbyq, May 4, 2015.

  1. stubbyq

    stubbyq Newbie

    So I work at a nuclear power plant, and of an engineering mind.  I noticed my UDS burned through considerably more fuel in the winter than in the summer....duh......right? Takes more energy to heat up cold air.  Well, I've taken inspiration from the more efficient design of the reactor core, and applied it to a UDS.  Here is what I've got.

    Very simple.  I've taken the intake pipes and put them inside the drum.  This allows some of the waste heat that escapes the the sides of the drum to preheat the intake air prior to reaching the firebox.  The cooking grate rests on the 90* elbows for the down pipes.  3 one inch holes are all that is drilled for the 3/4" pipes.  No other holes in the drum.

    I know, I know.  "But it takes more energy from the fire to heat the incoming air.....The differential temperature of the air leaving, and air going in is what causes the flow.  The incoming air will heat up and stop flow....."  

    First, the pipes are heated by waste heat that would leak outside the sides of the barrel.  Second, basic heat exchanger physics is that none are 100% efficient.  The air in the down pipes will be warmed, but never reach cooking temps.  Third.......we use the same design to make a nuclear reactor more efficient.  If it's good enough for a power plant, it's good enough for my smoker.

    Right now, the smoker is lit with no meat load on it.  It's cruising at about 280*f.  This is the WFO temp.  I'm gonna monitor it every hour until the temp dies off.  results to come.

    My only "if" is that 3 three quarter inch down pipes might not be enough air flow.  I did that to eliminate the chance of a 'teetering' cooking grate, and 1" pipes just looked too big.  I'll be loading this thing up to max capacity (4 butts) this weekend to check performance.

    I now leave it to the forum to poke holes, ask questions, and make design change suggestions.

    My only request is that IF this works, you put StuBByQ somewhere in the name.
    Last edited: May 4, 2015
  2. rmmurray

    rmmurray Master of the Pit

    That is certainly an interesting design idea. I really hope it works out for you. Sounds like it's going good so far. I'm in, let's see what this baby does in winter.
  3. fwismoker

    fwismoker Master of the Pit

    I make mine efficient for Wintertime use just by putting a reflectix koozie on.   It's all about efficient convenction.

    Not saying what you propose won;'t work but a reactor is a different concept than air flow.  FWIW I'll get pretty much Summertime fuel use.  It can be 25 below and the frozen ground will be completely dry at the end of a cook which tells me how efficient this concept is. 

    The pipes on the inside like you have will hamper with moving cooking grates up and and out.  Love you thinking outside the box though!  

    Last edited: May 4, 2015
  4. stubbyq

    stubbyq Newbie

    I use the same technique on my mini-WSM.  Works great.  I noticed in your pictures you have the same mini-WSM, and Big Pappa kit that I have.  The one you have in the middle is my question.  How did you make that one?  I'd like a PM, so we don't derail this thread.
  5. stubbyq

    stubbyq Newbie

    The two hour temp check is 300*f.  This is with no meat load, and wide open.  I'll update at 4 hours.
    Last edited: May 4, 2015
  6. fwismoker

    fwismoker Master of the Pit

    Cool will do... I came up with the koozie a while back, Glad to see it's being used!
  7. stubbyq

    stubbyq Newbie

    After 4 hours temp is still 290*f.  Looks like it was calming down from 320*f an hour ago.  Maybe ash build up on the coals is choking fire?  Anyway, I'm shutting down now to sleep. More testing on the weekend.  I'll check temp again in the morn to make sure it's sealed.
  8. dirtsailor2003

    dirtsailor2003 Smoking Guru OTBS Member

    So youve tried high temps what about low temps? 225-250? Can you get that low? Combustion fires need cold air to make the hot air flow so you may find out that pre-heating it may make it stall. Especially when you need to draw the cold air down through your heated environment.
    Last edited: May 4, 2015
  9. fwismoker

    fwismoker Master of the Pit

    Case I get what you're saying but I think it wouldn't stop him from achieving the cooler temps but  more the hotter temps. If he's getting 300 then you'd think it'd get worse going hotter based off that?  (kinda like flooding a carburetor)....or maybe i'm over thinking it. lol

    Anyways I'm all for experimentation for the betterment of BBQ..... i mean mankind. ;)
    Last edited: May 4, 2015
  10. timberjet

    timberjet Master of the Pit

    Very interesting. I will be watching this.
  11. What size grates did you go to? I see you didn't post where your from? You can insulate a drum. 55 in a 85. 85 in a 110.
  12. bmaddox

    bmaddox Master of the Pit

    300 with all three intakes wide open? what is the outside temp?

    If I have all three of my intakes open it runs over 400 degrees.
  13. I like the design. I'm going to keep an eye on it and see how it plays out. let us know how the fuel consumption goes.

    Happy smoken.

  14. stubbyq

    stubbyq Newbie

    Outside was about 65*, with zero wind.
  15. stubbyq

    stubbyq Newbie

    Your 400* temp just proves the preheating is taking place in my smoker.  My air flow is slower because I'm not getting 70* air to my's warmer.  Preheating the air is bound to slow down the intake.  Physics dictates that it won't stop, but the dilemma is that it might slow to the point the fire doesn't get enough air to maintain temp.  The cycle might then feeds itself to eventually slow air to the point the fire goes low.  

    BUT!!! then the fire cools, and the intake is not preheated as much......SO there is less preheating and a greater differential temperature (as compared to the cooled fire? maybe?).......does it recover with more air flow?  The middle of summer will be the real test.  Here, the summer nights might be in the 80's.....August will tell.

    A single lump of charcoal burns at 700* and with air temp even 80+* the smoker 'breaths' enough to maintain flow.  The real question is what happens when I heat that air to 140*-ish.  Can it maintain enough differential temp to create the differential pressure to cause enough flow?......

    then you have to account for the flow restriction of the meat being on the grate.(yes, your meat creates a differential pressure to smoke/air flow).............the engineering of this idea gets exponentially huge the more you think about it, because each parameter feeds all the other parameters.  I've decided just to do it, and let the physics work itself out.
    1.  I got the replacement Weber  22.5" kettle grates from Walmart.  2. I'm in Leland, NC. it's just outside of Wilmington.  3.  I did insulate that way (drum in drum) with my Mini-WSM,(it works great) but I was looking for a single drum that acted the same way.
    Last edited: May 6, 2015
  16. bmaddox

    bmaddox Master of the Pit

    It will be really interesting to see how this performs over time.
  17. stubbyq

    stubbyq Newbie

    Tropical storm on my cook day this weekend.  I opted not to move the smoker closer to the house, and cook during the storm.  We'll just have to wait until next weekend.  Supposed to me a normal storm then.
  18. Not a tropical storm here in Arkansas but lots of flooding. I'm on the side of a hill and flooded.

    Happy smoken.

  19. stubbyq

    stubbyq Newbie

    First, Arkansas is where my mother's family is from.  Grandma has an old school wood oven my ancestors brought to Oregon with them.  I'm going to make sure it ends up at my house.  I drove there through once.......there are hills?
  20. stubbyq

    stubbyq Newbie

    It was in the 70s last night, 80 during the day (stupid levels of humidity, for SE North Carolina is all swamp).  Looks like this Sunday promises to really test the smoker. <fingers crossed>  I'll be doing up two butts.  It's an average load (for me at least), and I don't need to do more than that for my next serving o' the masses.  I ask the masses of the forum if there is anything I haven't thought about, or missed?  Something that could help, maybe?  Your feedback a appreciated.

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