gsomdahl on sun 3 jul 11
I just returned from a tour in Norway. On old cottages there some of the
chimneys that are small at the bottom and widen at the top (see link).
Would this cause the hot flu gasses to expand increasing the draft? Has
this been tried on kilns? How would this effect passive dampers?
Gene
Typical Norwegian chimney: http://www.flickr.com/photos/wold/1185288547/
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This is a post only account. Send replies to "gene" at my ".com" domain nam=
ed "somdahl".
Alice DeLisle on mon 4 jul 11
Gene wrote: ". . . I just returned from a tour in Norway. On old =3D
cottages there some of the
chimneys that are small at the bottom and widen at the top (see link).
Would this cause the hot flu gasses to expand increasing the draft? Has
this been tried on kilns? How would this effect passive dampers?. . ."
There were similar chimneys on coal burning locomotives. Maybe that =3D
helped with updraft while keeping them short. Here are links to a =3D
couple of photos:
http://www.btcomm.com/trains/primer/whyscale/bach460.jpg=3D20
http://www.teamalco.com.au/images/TA07_SAR750.jpg
Alice DeLisle
wanderland@att.net
http://www.etsy.com/shop/IslandTextures
pdp1 on sat 9 jul 11
Hi Burien, all...
While I am not in the front of the Class on Chimney or Draw/Draft dynamics,
I believe that a chimney or Flue which increases in section as it ascends,
would slow the Draft, and, allow the Gasses to cool somewhat as they egress=
.
A Chimney which enlarges as it ascends, and, then, constricts again, would
break even for draught, while allowing the Gasses to cool a little as they
slow and roil in the mid part.
Wood Burning Locomotives used to use this sort of Chimney or Flue, I
imagine, to reduce the liklihood of live Embers being loosed on to the
World...and their condition was not one in which draft or draw from the
Chimney or Flue was significant, since they often blew Steam exhaust throug=
h
their Fire to conduce the gaseous combustion by-products out the Flue or
Chimney anyway.
Coal or Oil Burning Locomotives used a short stubby cylindrical Flue.
Probably a merely widening or enlarging Flue, would be ideal for a Wood
Burning Stove, if constructed deferentially, since it would allow easier
controll of the draft for the Stove not to over-run and waste the Wood
Fuel...or needing to be dampened as much as otherwise, to prevent it.
Probably some Kilns could benifit from such a Chimney...depending on how
they are run, and, for what effects or process particularly, since it would
favor an interest to encourage lingering reduction conditions, or slower
rises or to manage stable and held conditions ( even as would dempening a
straight Chimney, of course ).
Phil
L v
----- Original Message -----
From: "douglas fur"
> Gene
> Typical Norwegian chimney
> Would this cause the hot flu gasses to expand increasing the draft?
> As the cross section increases the velocity decreases. Gasses expand to
> fill a container. Given a roughly constant volume of gasses moving throug=
h
> a
> kiln they will expand or contract to fit the crross section- the ware
> chamber has the largest cross section so the gasses move slowest therefor=
e
> releasing heat to the pots...
>
> Has this been tried on kilns?
> I've seen tapers going the other way- the concept being; as the gasses
> cool
> they lose volume so the crossection is reduced to maintane the velocity
>
> My first thought was it has to do with snow or rain. Evergreens in the
> snow
> often have a chimney at their base so maybe this shape mimics this so
> there's less snow melting and soaking into the chimney
>
> DRB
> Burien
douglas fur on sat 9 jul 11
Gene
Typical Norwegian chimney
Would this cause the hot flu gasses to expand increasing the draft?
As the cross section increases the velocity decreases. Gasses expand to
fill a container. Given a roughly constant volume of gasses moving through =
a
kiln they will expand or contract to fit the crross section- the ware
chamber has the largest cross section so the gasses move slowest therefore
releasing heat to the pots...
Has this been tried on kilns?
I've seen tapers going the other way- the concept being; as the gasses cool
they lose volume so the crossection is reduced to maintane the velocity
My first thought was it has to do with snow or rain. Evergreens in the snow
often have a chimney at their base so maybe this shape mimics this so
there's less snow melting and soaking into the chimney
DRB
Burien
Frances Howard on sun 10 jul 11
Another explanation for big chimneys: it is easier for Santa Claus to get
down them without getting singed.
Frances Howard
-----Original Message-----
From: pdp1
Sent: Sunday, July 10, 2011 2:08 AM
To: Clayart@LSV.CERAMICS.ORG
Subject: Re: Norwegian chimneys
Hi Burien, all...
While I am not in the front of the Class on Chimney or Draw/Draft dynamics,
I believe that a chimney or Flue which increases in section as it ascends,
would slow the Draft, and, allow the Gasses to cool somewhat as they egress=
.
A Chimney which enlarges as it ascends, and, then, constricts again, would
break even for draught, while allowing the Gasses to cool a little as they
slow and roil in the mid part.
Wood Burning Locomotives used to use this sort of Chimney or Flue, I
imagine, to reduce the liklihood of live Embers being loosed on to the
World...and their condition was not one in which draft or draw from the
Chimney or Flue was significant, since they often blew Steam exhaust throug=
h
their Fire to conduce the gaseous combustion by-products out the Flue or
Chimney anyway.
Coal or Oil Burning Locomotives used a short stubby cylindrical Flue.
Probably a merely widening or enlarging Flue, would be ideal for a Wood
Burning Stove, if constructed deferentially, since it would allow easier
controll of the draft for the Stove not to over-run and waste the Wood
Fuel...or needing to be dampened as much as otherwise, to prevent it.
Probably some Kilns could benifit from such a Chimney...depending on how
they are run, and, for what effects or process particularly, since it would
favor an interest to encourage lingering reduction conditions, or slower
rises or to manage stable and held conditions ( even as would dempening a
straight Chimney, of course ).
Phil
L v
----- Original Message -----
From: "douglas fur"
> Gene
> Typical Norwegian chimney
> Would this cause the hot flu gasses to expand increasing the draft?
> As the cross section increases the velocity decreases. Gasses expand to
> fill a container. Given a roughly constant volume of gasses moving throug=
h
> a
> kiln they will expand or contract to fit the crross section- the ware
> chamber has the largest cross section so the gasses move slowest therefor=
e
> releasing heat to the pots...
>
> Has this been tried on kilns?
> I've seen tapers going the other way- the concept being; as the gasses
> cool
> they lose volume so the crossection is reduced to maintane the velocity
>
> My first thought was it has to do with snow or rain. Evergreens in the
> snow
> often have a chimney at their base so maybe this shape mimics this so
> there's less snow melting and soaking into the chimney
>
> DRB
> Burien
-----
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