Heat Transfer Questions & Answers  
Question by Student #201527118
I asked you about what are the assumptions of the example problem that you solved at the end of today's lecture. then you said ask this question at here.
05.16.17
I forget which problem this was. If you describe the problem setup and give a short summary of the solution I'll remember the assumptions.
Question by Student #201127151
Professor, I am curious about the solution at question #3-(c) of assignment #6. Solving the problem, I obtained the following equation: at steady state with no heat generation and no radiation, $$ \overline{q' '}=\overline{h}(T_{PLATE} - T_{\infty}) $$ and isolate $T_{\infty}$ $$ T_{\infty}=T_{PLATE}-\frac{\overline{q' '}}{\overline{h}}. $$ Here $\overline{q' '}$ and $\overline{h}$ are bigger than zero. Therefore I think the solution is $$ T_{\infty}=20^{\circ}C-6^{\circ}Cm^{0.5}U_{\infty}^{-0.5} $$ rather than $$ T_{\infty}=20^{\circ}C+6^{\circ}Cm^{0.5}U_{\infty}^{-0.5} $$ Is there any problem about the equations?
Hm, here $T_\infty$ should be higher than $T_{\rm w}$, so your solution can't be correct. I'll give you 1 point bonus boost.
Question by Student #201700043
Dear professor, You said this morning the Reynolds number on a tube banks is equal to Red=\frac{\rho Umax D}{\mu } . Can we consider the Reynolds number is the same in all the bank? Because the temperature or Umax won’t be exactly the same if we are on the middle or on the top of the bank...
You need to improve the quality of your typesetting: the text is too hard to read.. Type the question again.
Question by Student #201700043
Dear professor, You said this morning the Reynolds number on a tube bank is equal to : $$ Red = \frac{ \rho Umax D}{\mu} $$ Can we consider the Reynolds number is the same in all the bank ? Because the Temperature or Umax won't be exactly the same if we are on the middle or on the top of the bank...
Yes, the Reynolds number is function of $U_{\rm max}$ everywhere within the bank. But you're right, $U_{\rm max}$ may vary within the bank but this is taken into consideration by the empirical correlations in the tables. 1.5 point bonus: I would have given 2 if you would have typeset $Umax$ as $U_{\rm max}$.
Question by Student #201327104
Professor, I have a question for Question 2 from Assignment 6. After I figured out that the $Re_{x}$ at one side of the plate is $3.2 \times 10^{5}$, I tried to find appropriate equation for this situation (Laminar,local). But, there are two equations available, and properties also fulfill both condition for the equations. In this case, Can I get same result with two equations? which equation is better for the situation in Question 2 ?
Well, what is the difference between these two equations? The answer lies there probably..
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