A crafts forum. CraftBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » CraftBanter forum » Craft related newsgroups » Glass
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Monitoring electricity consumption of a device?



 
 
Thread Tools Display Modes
  #21  
Old September 20th 05, 05:47 AM
external usenet poster
 
Posts: n/a
Default

Right Henry H. did have an idea (or reported an idea) to achieve very
even heating by using compressed air through stainless tubes to set up
convective currents in a fusing/casting kiln. Henry is also not a kiln
former. In any case, the idea was not to cool down the kiln, but to
achieve more even heating.

The problem with that idea was the bane of every kilnworker producing
gallery quality work--crap landing on your work. Even a slight breeze
can stir up refractory dust from the primer or brick and ****ify the
piece. Also, convective currents already exist in a kiln naturally when
there is an air gap under the shelf. Uneven heating is more a problem
when firing fast or when the elements or kiln height are configured
wrong.

Ads
  #22  
Old September 20th 05, 02:52 PM
Joe
external usenet poster
 
Posts: n/a
Default



Nah, that was Ritchie Havens. I believe he was the first performer of the whole
weekend.

Joe

nJb wrote:


That's Henry Halem. Henry Havens was that guy that sang at Woodstock.

--
Jack

Plonked by Native American

bobo1148atxmissiondotcom

http://photos.yahoo.com/bc/xmissionbobo/


  #24  
Old September 21st 05, 02:20 AM
external usenet poster
 
Posts: n/a
Default

Good point. I hadn't even considered that. It would be a good idea for
annealing. I thought he had mentioned it for heat processes. It seems
like we discussed it at one point and he didn't mention it was for
annealing.

  #25  
Old September 21st 05, 05:03 AM
nJb
external usenet poster
 
Posts: n/a
Default

Joe wrote:

Nah, that was Ritchie Havens. I believe he was the first performer of the whole
weekend.

Joe


You're thinking of Richie Valens, the guy that was killed in the skiing
accident with Sonny Holly. Richie Havens is a gated community in Florida.

--
Jack

Plonked by Native American

bobo1148atxmissiondotcom


http://photos.yahoo.com/bc/xmissionbobo/
  #27  
Old September 21st 05, 11:58 AM
external usenet poster
 
Posts: n/a
Default

"Evenivity" is a Blanthornism. Brian Blanthorn of the Isle of Wight, he
of pebbles and a pioneer in devitrification as design. It actually
refers to even firing in a bunch of different ways. Because,
kilnformers are very concerned with uniform temperature across the
whole range of process temps, not only annealing. Uneven temperature at
fusing and slump temps can cause more problems actually than uneven
temperature at annealing. For example if you have a 30f difference from
the center to the margin of a flat piece, it will still anneal fine.
But that difference at fusing temperatures could present big problems
in the outcome of the piece. Evenivity at fuseing temperatures is
extremely important.

  #28  
Old September 21st 05, 02:29 PM
Joe
external usenet poster
 
Posts: n/a
Default



nJb wrote:



Richie Havens is a gated community in Florida.


Nuh-uh, the Gated Community is somewhere near Microsoft HQ.

I've noticed *everybody's* English languageing abilitythings have gone to hell in the
past 5 years. Might be due to the effects of new-kew-luhr radiationism.

Joe

  #29  
Old September 22nd 05, 12:58 AM
Mike Firth
external usenet poster
 
Posts: n/a
Default

Well, at lower temps, one entrains air and keeps it from moving, so you
want a fluffy blanket or other stuff on the outside. If you consider fiber
a conductor, I have to say: relative to what? I hope nobody is considering
packed fiber all the way out. Packed fiber is supposed to reflect heat, as
the specific mechanism, but below the temps that works at (1700F as I
recall) volume of non-convective air will work well.
The pipe was originally suggested by me because the person wanted to cool
the kiln easier. Since kiln work is crash cooled, I assumed the request was
for bringing an extra insulated box down through the annealing range.

--
Mike Firth
No more levees
Bury old Orleans
Raise New Orleans up if it is worth saving
--
wrote in message
ups.com...
Right Mike,,, Henry Havens? You're drunk, right?

At a given thickness (generally agreed to be 7-8" by longtime furnace
builders and engineers) Conductive heat loss through packed fiber is
not reduced in proportion to the radiant heat loss from the surface.
Efficiency proceeds in reverse. That's the theoretical point.The
practical point is, yes at some point additional fiber cost begins to
outweigh energy savings. But even if fiber were free, it still wouldn't
make sense. Remember that fiber is an insulator, but it also conducts
heat energy. In general conductive heat transfer is the most efficient
form of heat transfer. But don't get the wrong idea, obviously the
sheer volume of radiant heat loss per unit area of surface surpasses
the conductive heat loss of an insulating material, at some minimum
level. Ask a guy with an under-insulated furnace. So, you see we aren't
dealing with absolutes, but defined equations. Too much either way, and
efficiency is reduced.

My point is, the fact that you can't insulate further with a conductive
material is not the end of the story. Efficiency can and has been
increased by engineering techniques that are used outside the studio
glass arena.The trick is to limit heat transfer via conduction, while
also limiting the corresponding increase in radiant heat loss per unit
area. A hint, air is one of our best insulators, and it is free. It
insulates well because of its low heat conductivity. However, it is a
great medium for radiant heat loss. Which also fiber is not... and so
on, and so on...

As a side note, efficiency can also be increased by investing some
additional energy in stopping loss from the system.So that, while the
overall energy used by the system is increased, the proportion of
energy within the system put to work, not lost to the surroundings, has
increased. This activity can take different forms.



  #30  
Old September 22nd 05, 01:48 PM
external usenet poster
 
Posts: n/a
Default

It would be misleading to say that fiber is a "conductor". But, as a
solid it does conduct heat energy. In general we can state that the
more dense a material, the better in conducts heat. (Don't ask me if
that goes for all material or what exceptions there are.) I.e. a solid
is more heat conductive than a gas.

However a denser material may be much more effective in stopping
radiant heat loss. Which is why as you (sort of) point out, a furnace
maker packs fiber insulation: Radiant heat loss is the *primary issue*
at higher temperatures. Packed fiber is more effective reflecting heat
energy, and limiting radiant heat loss.

So Mike in short the question for an engineer is, how does one take
advantage of the best qualities of packed fiber (stopping radiant heat
loss) while ammeliorating its undesirable qualities (heat conduction).

Wrapping your furnace in an outer layer of less dense home insulation
is a simple attempt on the right track. But not the best solution.
Because, you are increasing surface area dramatically, while still
using a (far less dense) solid material. As I said, a gas is going to
be the least heat conductive material. So, the least amount of material
thickness and resulting increase in outside surface area. And at lower
temperatures (near the outside of your furnace) there are also things
one can do with emmisivity of materials to combat the tendency of a gas
to pass radiant heat energy.

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Hurricane Charley Fred Needlework 270 September 5th 04 07:24 PM


All times are GMT +1. The time now is 11:37 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CraftBanter.
The comments are property of their posters.