Just solve partB

Continuing with

the previous

question, having

shown that it is

not feasible to

shutoff the

water without

freezing, you are

curious about

the potential to

optimize this

arrangement.

Assume as before that during street repairs houses get water from a temporary above$-$

ground $50-$mm diameter plastic pipe that runs along the street.

Assume as before that the ambient temperature is $-10^($@$)$C and the convection coefficient on

the outside of the tube is h$\_(0)=20$W$//$m$^(2)$K$.$ Assume the water enters the above$-$ground tube

at a temperature of $10^($@$)$C $($admittedly a bit high, but chosen to simply your interpolation on

an exam!$).$ To be conservative, neglect any insulating effect of the tube material.

a$)$ For a water mass flow rate of $0\mathrm{.}5$kg$//$s$,$ assuming fully developed flow, what is the

convection coefficient on the inside of the tube?

b$)$ Neglect your answer from $($a$)$ If the tube length is restricted to $125$ m $,$ what is the

minimum flow rate to keep the water from reaching freezing temperature at the end of the

tube? $($HINT: ASSUME THAT THIS FLOW RATE WILL CORRESPOND TO LAMINAR FULLY$-$

Properties of liquid water may be taken from the following table $($same as before$)$: