Heat Transfer Questions & Answers  


You don't have to find $T_{\rm sun}$ if it's not needed to find the answer to the problem.




You should be able to explain this on your own.




I don't understand your question. As written in the problem statement there is no heat transfer to the journal.






If you unroll the bearing into $xy$ coordinates, you have to give the same area to the bearing and the journal: otherwise this wouldn't be consistent. If you don't unroll the bearing and solve it in cylindrical coordinates, then you should use two different areas for the bearing and the journal.




I'm not sure what is confusing you. As you mention, when V.D. is important, $q^"=h(T_{\rm w}T_{\rm aw})$.




You can use other correlations too unless they specifically say they are not applicable to liquids.




You're on the right track, but this is not correct still. Work on it more — the diameter of the tubes should be somewhere in your areas.. Also, use the PREVIEW command and make sure your math show up clearly: your expressions are too close to each other and hard to read. Separate them on different lines.




Use the most accurate correlation generally. Yes, you can find the $h$ without knowing the surface temperature a priori through an iterative process.




Well, as you mention, $\mu_{\rm w}$ is the viscosity of the fluid at the wall determined at the temperature of the wall.




Find the wall temperature, and then find $\mu_{\rm w}$ from this wall temperature.




True, it could be this way, but I was thinking of a river section where the sides are flowing water.




Solve the problem and check if the simplified expression can be used or not. If it can not be used, resolve the problem with the full expression.



$\pi$ 