Answer
$T_2=56.96°C$
Work Step by Step
For an ideal gas:
$PV=mRT$
Plugging in the values of $P_1=400\ kPa,\ V_1=100L=0.1m³,\ T_1=25°C=298.15\ K,$
$R=0.2870\ kJ/kg.K$, we get:
$m = 0.467\ kg$
The energy balance for this system reduces to:
$-W_{sh}=\Delta H = mc_p\Delta T$
With $W_{sh}=-15kJ, c_p=1.005\ kJ/kg$ we get to:
$\Delta T=31.96 °C$
$T_2=56.96°C$
