(Solved): A heat exchanger filled with ethanol (See Figure 2.1) is designed to promote boiling at a constant ...

A heat exchanger filled with ethanol (See Figure 2.1) is designed to promote boiling at a constant and uniform temperature $T=60^{?}\mathrm{C}$ over its entire volume. The upper surface of the heat exchanger is cooled by an air flow with a free stream velocity $v_{?}=$ $10\mathrm{m}/\mathrm{s}$ at a temperature $T_{?}=20^{?}\mathrm{C}$. We are interested in the convective cooling due to the air flow over a section of the heat exchanger's upper surface located between the lines $x=x_1=0.8m$ and $x=x_2=1.5m$. The heat exchanger is $2m$ deep (in $y$ direction). You can neglect heat losses from all vertical sides. The critical Reynolds number is $R{e}_c=6\times 10^5$. Figure 2.1 Heat dissipation component and heat exchanger 1. Calculate the average convection coefficient $\stackrel{?}{h}$ over the section located between $x=x_1$ and $x=x_2$. [12 Marks] II. Calculate the friction force acting over the same section located between $x=x_1$ and $x=x_2$ using the Chilton Colburn Analogy. [6 Marks] Air Properties: At film temperature: $v=16.69\times 10^{?6}{\mathrm{m}}^2/\mathrm{s},k=26.9\times 10^{?3}\mathrm{W}/\mathrm{m}.\mathrm{K},\mathrm{Pr}=0.7$ $?=1.12\mathrm{kg}/{\mathrm{m}}^3$