#11  
Old 02-16-2011, 04:53 PM
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Default Re: Will this Flue be effective?

Yes, we do not even sell any round flue, the point is how to figure the cross sectional area.
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  #12  
Old 02-16-2011, 07:36 PM
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Default Re: Will this Flue be effective?

Although the Forno Bravo design looked like a good one from the get go and I assume it was designed by an engineer I modeled it anyway for the heck of it. I put it into the exact same scenario as the other vent which means again the numbers are all arbitrary but the general characteristics should hold true as should comparisons. As expected it passed with flying colors in my book. The airflow looks fairly smooth and uniform.
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  #13  
Old 02-16-2011, 07:49 PM
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Default Re: Will this Flue be effective?

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Originally Posted by Tscarborough View Post
Yes, we do not even sell any round flue, the point is how to figure the cross sectional area.
There's more to it then cross section. Airflow through a duct is subject to friction loses. In the HVAC industry this is measured in inches of water column per 100 feet. Friction is proportional to the surface area. Round ducting is most efficient because it encloses a given volume with the smallest surface area. Square duct will give you less surface area then a rectangle and the further out of ratio you go the higher the surface area gets. It sounds petty but it can actually make a pretty big difference, even different materials can make a large difference due to different textures.
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  #14  
Old 02-16-2011, 08:45 PM
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Default Re: Will this Flue be effective?

That is true, and I still have the reference books for frictional losses through various materials and cross sections with fluids and gases, but we are dealing with 3-4' of flue in this application.
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  #15  
Old 02-26-2011, 07:07 AM
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Default Re: Will this Flue be effective?

I'll let those with more smarts than me argue the vent situation, I just want to see more pics of this build.
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  #16  
Old 02-26-2011, 01:44 PM
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Default Re: Will this Flue be effective?

I may be missing something, but it seems to me that the flue opening partially climbing the dome would totally undo the 63% dome/opening ratio.

I see that the door arch itself is 63% of the dome height but the gasses would be leaving the dome much higher up, so the door arch height would become irrelevant.

Pretty cool software, though.
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  #17  
Old 02-26-2011, 07:37 PM
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Default Re: Will this Flue be effective?

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Originally Posted by TDVT View Post
I may be missing something, but it seems to me that the flue opening partially climbing the dome would totally undo the 63% dome/opening ratio.

I see that the door arch itself is 63% of the dome height but the gasses would be leaving the dome much higher up, so the door arch height would become irrelevant.

Pretty cool software, though.
For both model I did the assumption would be the inlet is at the proper ratio. If you are referencing the first model the inlet is only the semicircle at the front, the arched area is a wall.
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  #18  
Old 02-27-2011, 05:46 AM
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Default Re: Will this Flue be effective?

Build photos, Build photos, Build photos, Build photos...
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Old 05-01-2012, 01:06 PM
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Default Re: Will this Flue be effective?

Quote:
Originally Posted by shuboyje View Post
Here's an overly simplified model of the vent running a pretty realistic volume of standard air. It's not a model of a real world situation in operation in an oven, so the actual numbers mean little, but air is air and oven exhaust being drawn through by natural convection will experience the same effects. As you can see in the model the vent isn't really doing you much good as the air is not able to make that sharp of a turn at that velocity in that short of a distance.

I'll try to model the sloped sides you mention, but they will be very difficult if at all possible due to the limitations of the software I use.
Well I lit my first fire today and used a lot of green wet wood later to make a lot of smoke, None of the smoke passed beyond my flue, All was sucked up the chimney I am very happy to say. (I was worried by the computer model but Human and Oven say NO). I have now lit another fire and again all gasses are being sucked up the chimney without problem. The first arch is spotless.
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  #20  
Old 05-01-2012, 01:41 PM
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Default Re: Will this Flue be effective?

Terrific, my own vent is similar but not as extreme as yours.The big advantage is that it saves space and you can have a shallow entry for easier working of the oven. I see that the rectangular entry area of your flue is much the same as the area of the round section. Yours obviously works ok, but I think it is better if the entry area is larger than the area of the pipe.
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