tAir at $25$ flows inside a $20-$cm$-$inside$-$diameter tube which has a wall thickness of $10$ mm$.$ The surrounding environment temperature is $10.$ The convective heattransfer coefficient inside the tube is hi$=15$ W$/$m$2$ K$,$ and that of outside is h$0=5$ W$/$m$2$ K$.$ The thermal conductivity of the tube is $1\mathrm{.}5$ W$/$m K$,$ and the external emissivity is $0\mathrm{.}95.$ Assuming negligible internal radiation, determine the heat transfer rate through the tube per length and the outside surface temperature of the tube.o solve