QUESTION $2(50\%)$

A shell and tube heat exchanger consists of $50$ thin walled tubes in a double pass arrangement. The tubes have an inner diameter of $12\mathrm{.}5$ mm and a total surface area of $47\mathrm{.}5m^2.$ Water enters the tubes at $15C$ and a total mass flow rate of $6\mathrm{.}5k\frac{g}{s}.$ The water is heated by air flowing through the shell at $200C$ and $5k\frac{g}{s}.$ The overall heat transfer coefficient for the heat exchanger is $U=200\frac{W}{m^2}K$

You may assume the following fluid properties:

$T_{}=15C$

Water