$11-17$ A long, thin$-$walled double$-$pipe heat exchanger with tube and shell diameters of $1\mathrm{.}0$ cm and $2\mathrm{.}5$ cm $,$ respectively, is used to condense refrigerant$-134$a with water at $20C.$ The refrigerant flows through the tube, with a convection heat transfer coefficient of $h_i=4100\frac{W}{m^2}*K.$ Water flows through the shell at a rate of $0\mathrm{.}3k\frac{g}{s}.$ Determine the overall heat transfer coefficient of this heat exchanger.