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I'm new at heat transfer and I have three elementary questions from the book "Fundamentals of heat transfer" by Incropera et al. This is Example 1.1 in the book:

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(1) What is the definition of steady-state conditions? The authors haven't define them before in the book.

(2) The authors have written this comment at the end of the example: Note the direction of heat flow and the distinction between heat flux and heat rate. What is the definition of heat flow? They've defined the concepts of heat flux and heat rate but not heat flow. Can anyone tells me what is the direction of heat flow in this example?

(3) What is the relationships of heat flow to a temperature gradient?

Thanks in advance.

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  • $\begingroup$ What are your thoughts on this so for? $\endgroup$
    – Chet Miller
    Commented Jul 3, 2023 at 13:03
  • $\begingroup$ @ChetMiller I don't have the definitions to think about them. I know that energy transfer accur in the direction of decreasing temperature and the heat flux is in the $x$ direction and prependicular to the direction of transfer. Moreover, I think steady-state condition means temperature doesn't change with time at any point in the system. Am I correct? $\endgroup$
    – M.Ramana
    Commented Jul 3, 2023 at 13:12
  • $\begingroup$ Yes, on all points. $\endgroup$
    – Chet Miller
    Commented Jul 3, 2023 at 13:29
  • $\begingroup$ en.wikipedia.org/wiki/Thermal_conduction $\endgroup$
    – Gert
    Commented Jul 3, 2023 at 13:30
  • $\begingroup$ @ChetMiller Could you please help me about the questions (2) and (3)? $\endgroup$
    – M.Ramana
    Commented Jul 3, 2023 at 14:03

1 Answer 1

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Heat flux q is flow of heat per unit area. Heat flow Q is total flow rate of heat (J/s). $$q=-k\frac{dT}{dx}$$$$Q=Aq$$

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