In a concentric, two$-$pipe heat exchanger, the pressurized water with a flow rate of $13250k\frac{g}{h}$ is heated from $35C$ to $120C$ with a flow of $5000k\frac{g}{h}$ with superheated water $($pressurized water$)$ at $300C$ inlet temperature. The total heat transfer coefficient is $1500\frac{W}{m^2}K.$

Use TS $1996$ Heat Exchangers standard for design.

a$)$ Find the required heat exchanger surface area and size to a suitable length. $($Note: It is not practical over a length of $3m,$ so it is manufactured in $2$ or $3m$ length and connected to each other.$)$