Question $9$: Consider a double pipe heat exchanger that contains two

streams crude oil $($API $=26\mathrm{.}4)$ with $20,000$ B$/$D flow rate is to be

heated from $120C$ to $135C,$ and kerosene stream $(\frac{A}{P}$I $=34)$ with

$10,000\frac{B}{D}$ is to be cooled enters at $250C.$ Knowing that the pipe size

is $2\frac{1}{2}**1\frac{1}{4}$ IPS $,$ and the allowable $P=15$ psi.

$\frac{A}{P}$I $=\frac{141\mathrm{.}5}{Sp*Gr}-131\mathrm{.}5$

$>$ Suggest the number and the configuration of hairpins for the

heat exchanger.