Chapter 4 - Energy Analysis of Closed Systems - Problems - Page 210: 4-147

E

Energy balance: $Q-W_s=\Delta U$ With $Q=0.8\ kJ/s\times 30\ min\times 60\ s/min=1440\ kJ$ $W_e=-120 J/s\times 30\ min\times 60\ s/min=-216\ kJ$ $\Delta U=1656\ kJ=mc_v\Delta T$ Given $m=60kg,\ c_v=0.718\ kJ/kg.K,\ T_1=25°C$ $T_2=63.4°C$