Is Heat Transfer between 2 Walls Independent of Temperature Assumptions?

In summary, the assumption of T>T_1 is not necessary for the validity of the equations if the positive flow direction is defined to be from external wall 2 to external wall 1. This applies regardless of the actual values of the temperatures.
  • #1
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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  • #2
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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  • #3
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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1. How does heat transfer occur through two walls?

Heat transfer occurs through two walls through three main mechanisms: conduction, convection, and radiation. Conduction is the transfer of heat through direct contact between two materials, while convection is the transfer of heat through the movement of fluids. Radiation is the transfer of heat through electromagnetic waves.

2. What factors affect the rate of heat transfer through two walls?

The rate of heat transfer through two walls is affected by the material of the walls, the thickness of the walls, the temperature difference between the two sides of the walls, and the presence of any insulating materials.

3. How can the heat transfer through two walls be reduced?

The heat transfer through two walls can be reduced by using insulating materials, such as foam or fiberglass, to create a barrier between the two walls. Additionally, increasing the thickness of the walls and reducing the temperature difference between the two sides can also decrease the rate of heat transfer.

4. What is the difference between conductive and convective heat transfer through two walls?

Conductive heat transfer occurs through direct contact between two materials, while convective heat transfer occurs through the movement of fluids. In the case of two walls, conductive heat transfer would occur between the two walls themselves, while convective heat transfer would occur between the air or fluid inside the walls.

5. How does insulation affect the heat transfer through two walls?

Insulation acts as a barrier to heat transfer, reducing the rate at which heat can pass through the two walls. This is because insulation materials have low thermal conductivity, meaning they are not good conductors of heat. Therefore, they can help to trap heat inside a space or prevent heat from entering a space from the outside.

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