Answer
a) $\Delta h =447.79\ kJ/kg$
b) $\Delta h =448.40\ kJ/kg$
c) $\Delta h =415.60\ kJ/kg$
Work Step by Step
a)For an ideal gas:
$\Delta h = \int c_p dT = \frac{1}{M}\int\bar{c}_pdT$
$\Delta h = \frac{1}{M} (aT+b/2.T^2+c/3.T^3+d/4.T^4)_{T_1}^{T_2}$
With $T_2=1000K, T_1=600K$, and the constant values from table A-2c:
$\Delta h =447.79\ kJ/kg$
b) Since $T_{avg}=800K$, $c_{p,avg}\approx c_{p,\ 800K}=1.121\ kJ/kg.K$
$\Delta h =c_p\Delta T$
$\Delta h =448.40\ kJ/kg$
c) $c_{p,\ 300K} = 1.039\ kJ/kg.K$
$\Delta h =415.60\ kJ/kg$
