S$2.$

Assumptions $1$ This is a steady$-$flow process since there is no change with time. $2$ Air is an ideal gas with variable specific heats. $3$ Potential energy changes are negligible. $4$ There are no work interactions.

Properties The gas constant of air is $0\mathrm{.}287$kPa$*\frac{m^3}{k}g.K($Table A$-1).$ The enthalpies are $($Table A$-17)$

$T_1=27C=300K{h}_1=300\mathrm{.}19k\frac{J}{k}g$

$T_2=42C=315K{h}_2=315\mathrm{.}27k\frac{J}{k}g$