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Re: 36" Tall Man's Oven Build
Hi Mark,
No, what I'm saying is that some of the influences of optimal draft through the chimney are simply out of our control. Because the inlet and outlet of the chimney are both subjected to wind influence, the pressure differentials between the two ends of the conduit can influence the effectivness of the draw through the chimney. This draw through the chimney is soley relient on the bouyancy of the the constituant gasses.
Just as an automotive engine needs fuel, compression, and spark/timing, combustion of wood requires "the three T's"; Time, Temperature, and Turbulence. Temperature is non-issue in a WFO. Time means time for the fuel and oxidizer molecules to mingle and find one-another. Turbulence is the the flow medium that allows the fuel and oxidizer to fold-together and mix into a combustible mixture. In our WFO's, the basic design is so that the flue gasses (which are high in temperature and more bouyant) rise upward and force there way out of the top of the door opening. This exidous is supplanted with incoming air which comes in low and spreads across the floor to feed the fire. This is all well and good, and works very well as a usable system.
However, at extremely high temperatures, the wood in a WFO will at times volatize at a rate wich is much greater than the static system design can optimize a mixing (time and turbulence) for the air and fuel constituants. Wood is a hydro-carbon fuel and hydrogen oxidizes much more easily than carbon. So, when conditions do not promote complete combustion, the hydrogen will play along, but not all of the carbon. The result is soot.
In short, all I am saying is that WFO's are what they are and that the major attributes that influences the spillage of an outdoor WFO is an ample throat area to the chimney and the effects of wind.
I think all WFO's will spill to some degree. It's OK. We just made sure our chimnry was high enough to keep any dense discharges of smoke from people's faces when burning the oven hard. Also, we're just talking about when the oven is at "high-fire".
Ken Morgan
Hi Mark,
No, what I'm saying is that some of the influences of optimal draft through the chimney are simply out of our control. Because the inlet and outlet of the chimney are both subjected to wind influence, the pressure differentials between the two ends of the conduit can influence the effectivness of the draw through the chimney. This draw through the chimney is soley relient on the bouyancy of the the constituant gasses.
Just as an automotive engine needs fuel, compression, and spark/timing, combustion of wood requires "the three T's"; Time, Temperature, and Turbulence. Temperature is non-issue in a WFO. Time means time for the fuel and oxidizer molecules to mingle and find one-another. Turbulence is the the flow medium that allows the fuel and oxidizer to fold-together and mix into a combustible mixture. In our WFO's, the basic design is so that the flue gasses (which are high in temperature and more bouyant) rise upward and force there way out of the top of the door opening. This exidous is supplanted with incoming air which comes in low and spreads across the floor to feed the fire. This is all well and good, and works very well as a usable system.
However, at extremely high temperatures, the wood in a WFO will at times volatize at a rate wich is much greater than the static system design can optimize a mixing (time and turbulence) for the air and fuel constituants. Wood is a hydro-carbon fuel and hydrogen oxidizes much more easily than carbon. So, when conditions do not promote complete combustion, the hydrogen will play along, but not all of the carbon. The result is soot.
In short, all I am saying is that WFO's are what they are and that the major attributes that influences the spillage of an outdoor WFO is an ample throat area to the chimney and the effects of wind.
I think all WFO's will spill to some degree. It's OK. We just made sure our chimnry was high enough to keep any dense discharges of smoke from people's faces when burning the oven hard. Also, we're just talking about when the oven is at "high-fire".
Ken Morgan
.
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