Is Heat Transfer between 2 Walls Independent of Temperature Assumptions?

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SUMMARY

The discussion confirms that the heat transfer between two walls is independent of temperature assumptions when the positive direction for heat transfer fluxes is clearly defined. Specifically, defining the positive flow direction from external wall 2 to external wall 1 allows for valid equations regardless of the temperature values. This approach eliminates the need for specific temperature assumptions, streamlining the analysis of heat transfer scenarios.

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Shreya
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Homework Statement
Please refer the image
I am not sure if my solution is right, especially about the steady state condition. Am I allowed to assume T' > T1? Or should I consider 2 opposite heat fluxes and figure out their difference
Please be kind to help
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The question & my solution
 

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That all looks right.
##T'>T_1## is a perfectly reasonable assumption, but it does not need to be an assumption if the positive direction for the heat transfer fluxes is defined (rather than taking it be a non-negative quantity). Your equations are valid regardless of the values of the temperatures if the positive flow direction is defined to be from external wall 2 to external wall 1.
 
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haruspex said:
That all looks right.
##T'>T_1## is a perfectly reasonable assumption, but it does not need to be an assumption if the positive direction for the heat transfer fluxes is defined (rather than taking it be a non-negative quantity). Your equations are valid regardless of the values of the temperatures if the positive flow direction is defined to be from external wall 2 to external wall 1.
Thank You! That has really helped @haruspex
 
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