A horizontal Shell and tube exchanger is to be designed to condense $7\mathrm{.}56$ kg$/$sec isobutane at $827$ kN$/$m$2,$ using cooling water on the tube side. The water is available at $300$ K and is required in another process at $312\mathrm{.}5$K$.$ in outer diameter $(19\mathrm{.}05$mm$),14$ s$.$w$.$g$.(2\mathrm{.}11$ mm Wall$)$ tubes are to be used on $1$ in $(25\mathrm{.}4$ mm$)$ square pitch and the total scale resistance may be taken as $0\mathrm{.}00053$ m$2$K$/$W$.$ What size of the exchanger should be specified?