Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations SSS148 on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

thermal conductivity comparison glass and concrete 2

Status
Not open for further replies.

vij36

Electrical
Dec 27, 2018
134
Dear All,

I am trying to compare the thermal conductivity of
10 mm tempered glass and 6" concrete wall.

Any inputs or best practices for evaluation please ...
 
Replies continue below

Recommended for you

You look up the thermal conductivity by Google search, then you calculate the R-factor for each case.
 
This comparison requirement is for selecting either glass wall or brick wall for living rooms.

Should i check for convection also ? But convection involves liquids and gases ...
 
Dear sir,
I could not understand your comment "vacuum environment "

Could you please elaborate ...
 
Your wall, glass or otherwise, is surrounded by what?

Moreover,
> units in row 7 are incorrect, should be W/mm^2-K
> row 12 is nonsensical, because you used mm^2 as the area unit. The temperature for conduction is the delta temperature, not the absolute. Absolute temperature only shows up in radiated heat and heat transfer coefficient calculations.
> mm^2 for area is a nonsensical
> row 16 is nonsensical, since that's per mm^2 of area.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
Your living room and outside environment is filled with air, which is a gas. Therefore, you should consider convection.

You have an HVAC problem here. There are a lot of HVAC knowledge in books, for example ASHRAE Handbook, that can aid you in solving your problems.
 
If you want a glass wall then choose glass.

If you want a concrete wall then choose concrete.

Design the HVAC accordingly.
 
@MintJulip - best advise!
@vij36: text book suff - heat transfer has 3 elements, conduction, convection and radiation. Each element has constant for specific maerials that are easy to find. If you are really considering building a room, then for HVAC design you will be able to find table/graphs that will tell you the amount of heat influx based on temperature difference. The tables etc ha solved the problem for you in a standard way that will be valid for most cases.

Best regards, Morten
 
Here is a third option. Instead of concrete or glass panes, consider glass blocks, then contact the manufacturer for the K or R value. For regular glass panes, concrete blocks or plain concrete walls CE or ME handbooks will have those values.
 
MortenA said:
text book suff - heat transfer has 3 elements, conduction, convection and radiation. ...

my doubt is whether it is glass or brick wall the surrounding media such as air remains the same. Or if I am wrong will the surrounding area's medium such as air will have separate effects on glass and brick ?

 
IRStuff said:
You need to explain the problem, in MORE DETAIL, rather than just tossing out random disjoint questions.

Apologize for the inconvenience.

Am relatively new to hvac material selection.

Basically the task in my hand is to choose between 10 mm glass or porotherm brick.

Glass U value is ranging from 1.67 to 5.88. W/ m k
Link

Porotherm thermobrick U value is 0.6 W/ m k
Link

So for less heat gain inside should we need to choose less U vale material ?

Spare me if I am awfully wrong . [ponder]
 
IRStuff said:
Aren't glass blocks a bit 1960s?

Are the double glazing units are better than glass blocks ? Will the spacer can improve the hvac performance ?
 
Glass blocks are thick, so should be less conductive than double pane, but double pane is more modern and you can see through it. This is all pretty common knowledge.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor