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High Temperature Emissivity
05-24-2013, 08:34 AM (This post was last modified: 05-26-2013 05:36 PM by acardoso.)
Post: #7
RE: High Temperature Emissivity
Assuming we can keep the temperature of the surface steady and, we can vary Trefl without modifying the geometry of the space, we do a series of thermograms modifying the heat sources, contributing for Trefl on the surface where we want the temperature measured.
With the equation
[Image: attachment.php?aid=116]

We build an equation system
[Image: attachment.php?aid=117]

Solving the system in order to T4 and ε we get the solutions

[Image: attachment.php?aid=118]

T and TreflX are expressed in Kelvin, t and tsurface in degrees Celcius.
σ= 5.670373(21) × 10−8 W m−2 K−4
Wx=σ∙(tsurface+273.15)4, tsurface= apparent temperature on the surface measured with camera set for 1 at emissivity.

Excel example

.xlsx  Temperature and emissivity.xlsx (Size: 11.23 KB / Downloads: 19)

Maple script

.zip  emissivity.zip (Size: 23.13 KB / Downloads: 13)

Formulas for LabView, Matlab, Maple
ε=-(-Trefl1^4*sigma+Trefl2^4*sigma+W1-W2)/(sigma*(Trefl1^4-Trefl2^4))
t=((W1*Trefl2^4-W2*Trefl1^4)/(-Trefl1^4*sigma+Trefl2^4*sigma+W1-W2))^(1/4)+273.15

Formulas for Excel
ε=-(-(Trefl1^4)*sigma+(Trefl2^4)*sigma+W1_-W2_)/(sigma*(Trefl1^4-Trefl2^4))
t=((W1_*Trefl2^4-W2_*Trefl1^4-W1_-W2_)/(-(Trefl1^4)*sigma+(Trefl2^4)*sigma+W1_-W2_))^(1/4)-273.15


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Messages In This Thread
High Temperature Emissivity - ajspires - 04-29-2013, 12:01 PM
RE: High Temperature Emissivity - Bobberry - 04-30-2013, 04:47 PM
RE: High Temperature Emissivity - ajspires - 05-01-2013, 10:39 AM
RE: High Temperature Emissivity - acardoso - 05-24-2013 08:34 AM

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