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Thread: Finding Surface Area Temperature

  1. #1
    Associate Engineer
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    Finding Surface Area Temperature

    I need help on figuring out how to find the surface temperature of a given material. Say for example An R-20 wall. With outside temp at -20 and sustaining an indoor temp at 70.

    Correct me if im wrong but this is my best guess at it:

    Take .68(Inside air film) divide by total R-Value

    Take this percentage and multiply by Temperature difference (.68/20) * 90

    Subract above number from 70 ((70-(.68/20))

    Would this give you a surface temperature?
    Last edited by Kelly_Bramble; 12-01-2012 at 06:41 PM.

  2. #2
    Technical Fellow Kelly_Bramble's Avatar
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    Well I would look at the following calulator for ideas.

    http://www.engineersedge.com/heat_tr...iner-calcs.htm

  3. #3
    Technical Fellow Kelly_Bramble's Avatar
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    Also, see the attached document - somewhere around page 4.

    Arch-Heat-Flow-Basics-reduced.pdf

    heat-transfer-wall.gif
    Last edited by Kelly_Bramble; 12-02-2012 at 08:36 AM.

  4. #4
    Principle Engineer
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    Probably close enough.
    If you need greater accuracy, your .68 from natural convection may have to be adjusted for the actual indoor conditions.

  5. #5
    Associate Engineer
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    Thanks for all of your guys advice, im using it for HVAC purposes and trying to explain to a customer why she feels cold next to her window in the middle of winter.

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