Chapter 5 - Mass and Energy Analysis of Control Volumes - Problems - Page 261: 5-103

$\dot{W}_e=4.22 kW$

From the energy balance: $\dot{W}_e+\dot{W}_s+\dot{m}h_1=\dot{Q}+\dot{m}h_2$ $\dot{W}_e+\dot{W}_s-\dot{Q}=\dot{m}c_p(T_2-T_1)$ and since $\dot{W}_s=300W,\ \dot{m}=0.6\ kg/s,\ \dot{Q}=300W,\ c_p=1.005\ kJ/kg.°C,\ \Delta T=7°C$: $\dot{W}_e=4.22 kW$