jimb740
Posts: 4
Joined: Tue Sep 04, 2007 11:03 am

### heat temp through glass

I need to know if there is a formula for heat loss/gained when traveling from glass to air(or vice versa)PLEASE.Thank You.
JIM B.

scotta740
Posts: 17
Joined: Tue Sep 04, 2007 11:03 am
I think I may have found something for you check out: http://irc.nrc-cnrc.gc.ca/pubs/cbd/cbd039_e.html
Scott A.

jimb740
Posts: 4
Joined: Tue Sep 04, 2007 11:03 am
thanks Scott. may be helpful later but only scanned and saw nothing on air and different path of glass than needed. But thanks fo your help.
JIM B.

Craig_Bridge
Former Expert
Posts: 1297
Joined: Mon Oct 16, 2006 11:47 am
I need to know if there is a formula for heat loss/gained when traveling from glass to air(or vice versa)
If you do some research into basic thermodynamics, you will find that there are three basic types of heat transfer (radiant, convection, and conduction). Heat is also transfered by any fluid transfer (in terms of a building this would be "infiltration" or intentional air exchange).

Each of these different heat transfer mechanisms have vary different formulas.

Radiant heat behaves like an electromagnetic wave at a significantly lower frequency (longer wavelength) than visible or typically what is considered infrared. In this case, each air (or gas) / glass boundary represents a reflectance and transmittance boundary condition and the type of glass. Low "E" glass is designed to reflect more and transmit less. Many specialty glass manufacturers will provide these properties.

Equations for convection currents and associated heat transfer have been well described for years and the film coeficient for various glasses are close enough form most purposes.

Conduction is a much simpler mechanism and glass is a good thermal conductor so modern window designs to minimize heat transfer are typically multple panes separated by a vacuum or special gas.

Do some resarch into these heat transfer mechanisms to find the specifics.
-Craig

jimb740
Posts: 4
Joined: Tue Sep 04, 2007 11:03 am
thanks Craig! I was able to find the heat capacity of air and now i should be able use it, once i get a ball park of how much air is in my chamber.
JIM B.