Water flows in a $2-$meter$-$long tube with a mass flow rate of $m^{}=0\mathrm{.}25kg*s^{-1}.$ Tube inner diameter is $5cm$ and

inflow temperature is $20C.$ The pipe is heated by an electric heater. The heat flux into water is $q_1^{}=10kW*m^{-2}$

in the first $1$ meter of the tube and $q_2^{}=20kW*m^{-2}$ in the second $1$ meter $($uniform in each section$).$ The flow in

the pipe is turbulent. $($a$)$ What is the outflow mean temperature of water? $($b$)$ Would the outflow temperature be

larger$/$smaller$/$identical if the flow could be kept laminar in the pipe $($with all parameters the same$)?$

Properties of water:

$k=0\mathrm{.}6W*m^{-1}{K}^{-1},=995kg*m^{-3},c_p=4\mathrm{.}2kJ*k{g}^{-1}{K}^{-1}$