2018 Heat Transfer Final Exam  




Hint: Assuming a pump efficiency of 100%, it can be shown that the pump power is related to the bulk velocity inside the pipe through the following expression: $$ {\cal P}=\frac{\rho u_{\rm b}^3 \pi f L D}{8}$$ where $L$ is the length of the pipe, $D$ is the diameter of the pipe, $f$ the friction factor, and $u_{\rm b}$ the bulk velocity inside the pipe. I will give a bonus to the those who can prove the latter from basic principles. 








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