To solve this problem it is necessary to apply the concepts related to the heat exchange of a body.
By definition heat exchange in terms of mass flow can be expressed as
[tex]W = \dot{m}c_p \Delta T[/tex]
Where
[tex]C_p =[/tex] Specific heat
[tex]\dot{m}[/tex]= Mass flow rate
[tex]\Delta T[/tex] = Change in Temperature
Our values are given as
[tex]C_p = 1.005kJ/kgK \rightarrow[/tex] Specific heat of air
[tex]T_1 = 50\°C[/tex]
[tex]\dot{m} = 2kg/s[/tex]
[tex]W = 8kW[/tex]
From our equation we have that
[tex]W = \dot{m}c_p \Delta T[/tex]
[tex]W = \dot{m}c_p (T_2-T_1)[/tex]
Rearrange to find [tex]T_2[/tex]
[tex]T_2 = \frac{W}{\dot{m}c_p}+T_1[/tex]
Replacing
[tex]T_2 = \frac{8}{2*1.005}+(50+273)[/tex]
[tex]T_2 = 326.98K \approx 53.98\°C[/tex]
Therefore the exit temperature of air is 53.98°C