Problem $2$:

It is desired to design an oil cooler with sea water using a finned tube double$-$pipe heat exchanger. Engine oil at a rate of $3k\frac{g}{s}$ will be cooled from $65C$ to $55C$ by sea water at $20C.$ The sea water outlet temperature is $30C,$ and it flows through the inner tube. The properties which are assumed to be constant as well as the design data are given below. Fouling factors for the engine oil and sea water are $0\mathrm{.}000176$ and $0\mathrm{.}000088m^2*\frac{K}{W},$ respectively. Calculate the surface area of the heat exchanger as well as the number of hairpins and pressure drops for both streams. Make your comments on the obtained results from a designer's viewpoint.