Why Does the Convection Heat Transfer Coefficient Vary with Temperature?

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SUMMARY

The convection heat transfer coefficient (h) is not a constant and varies with temperature, particularly in real-world applications where flow conditions change. In scenarios with constant flow, h can be treated as constant, but this is not universally applicable. The discussion highlights the importance of understanding the relationship between temperature and h, emphasizing that variations occur due to changes in fluid properties and flow dynamics.

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Homework Statement


I have a question about part b for this question:
rDSwksQ.png


In the solution apparently h1 and h2 are a function of temperature as shown here:
Enib80a.png


However, I thought the convection heat transfer coefficient is a constant. I have done some problems where it is constant but in this case it is not. Does anyone know why? When is it constant and when is it not?
 
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Moderator's note: thread moved from Intro Physics to Engineering.

(Hopefully somebody can help out.)
 
In real world situations, the convective heat transfer coefficient is not going to be constant unless the flow is constant. Maybe you can cite some examples of where it was treated as constant.

Chet
 

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