Problem 1 (25pts) Consider a thin-walled tube of 10-mm diameter and 2-m length.
Water enters the tube from a large reservoir at mass flowrate = 0.3 kg/s and an inlet
temperature of 50°C. (a, 5pts) Draw the thermal circuit and (b, 20pts) calculate the
exit temperature of the water if it is heated by passing air at a temperature of 100°C
and $V = 10$ m/s in cross flow over the tube.
Hint: For the air heating process, the water outlet temperature follows:
$\frac{T_{\infty} - T_{m,o}}{T_{\infty} - T_{m,i}} = exp(-\frac{A}{\dot{m}c_p}\bar{U})$, where $1/\bar{U} = (1/h_i + 1/h_o)$
