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Fractional Blackbody Emissive Power Solver. By: David Wheeler & William Tryon November 30, 2011. Introduction. It is often necessary to know the fraction of the total emission from a blackbody that is in a certain wavelength interval or band. - PowerPoint PPT Presentation
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By: David Wheeler & William TryonBy: David Wheeler & William Tryon
November 30, 2011November 30, 2011
It is often necessary to know the fraction of
the total emission from a blackbody that is in a certain wavelength interval or band.
A ‘Blackbody Radiation Function’ table can be used to lookup such values to calculate the total emissive power.
The calculations to find the total emissive power are long, quite monotonous, and can introduce errors.
Our object is to make this process quicker, easier, and more accurate.
Introduction
User Friendly Accurate Intuitive (no need for instructions) Easy of Use Universal (able to use on a wide variety of
problems) Visually Appealing Quick Able to accept small changes easily, in order
to gain a better understanding of the material
Main Objectives
Calculator Layout
Define the temperature of
the diffuse surface
Define the temperature of
the diffuse surface
Define up to three
wavelengths of interest
Define up to three
wavelengths of interest
If desired, enter the spectral,
normal emissivity for the specified range
If desired, enter the spectral,
normal emissivity for the specified range
The fraction of the radiation between the
specified wavelengths
The fraction of the radiation between the
specified wavelengths
Total emissivityTotal emissivity
Total emissive power
Total emissive power
Press Run! at any time to update the calculations
Press Run! at any time to update the calculations
Press Reset to erase all entriesPress Reset to
erase all entries
A diffuse surface at 1600K has the following
spectral, hemispherical emissivity:
ε = 0.40 for 0 < λ < 2μmε = 0.80 for 2 < λ < 5μmε = 0 for λ > 5μm
Determine the total hemispherical emissivity
and the total emissive power.
Sample Problem
Enter the following
parameters:• Surface
temperature
• λ1 and λ2
• ε1 and ε2 Push Run! Viola! There’s the
answers!
Sample Problem (cont.)
We wrote a MATLAB script that interpolates
the data from Table 12.1 We then designed and programed a Graphical
User Interface (GUI) to collect the required inputs
Using the interpolated data and the collected inputs, we performed the necessary calculations
We display the fractional radiation distribution, the total emissivity, and total emissive power.
How it Works!
The program is:
User Friendly Accurate Intuitive (no need for instructions) Easy of Use Universal (able to use on a wide variety of
problems) Visually Appealing Quick Able to accept small changes easily, in order to
gain a better understanding of the material
Conclusion
Ability to increase the number of specified
wavelengths. Higher order approximation for the fraction of
the blackbody emission in a spectral band (currently we use a linear fit)
Create a Java applet to improve availability Include additional outputs, such as the
spectral intensity for the specified wavelength.
Future Work
Questions?
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