$2\mathrm{.}16$ A solution with a boiling point of $82C$ boils on the

outside of a $2\mathrm{.}5-cm$ tube with a No$.14$ BWG gauge

wall. On the inside of the tube flows saturated steam

at $420$ kPa $($abs$).$ The convection heat transfer co$-$

efficients are $8\mathrm{.}5k\frac{W}{m^2(K)}$ on the steam side and

$6\mathrm{.}2k\frac{W}{m^2(K)}$ on the exterior surface. Calculate the

increase in the rate of heat transfer if a copper tube is

used instead of a steel tube.