Answer
a) $\dot{m}_R=0.0338\ kg/s$
b) $\dot{Q}_H=7.04\ kW$
c) $COP=4.40$
d) $\dot{W}_{i,min}=0.740\ kW$
Work Step by Step
From tables A-11 to A-13, for R-134a:
Inlet ($x_1=0.15, T_1=12°C$): $P_1=443.3\ kPa\ h_1=96.54\ kJ/kg$
Outlet ($P_2=P_1, x_2=1$): $h_2=257.33\ kJ/kg$
From tables A-4 to A-6, water:
Inlet ($x_3=0, T_3=60°C$): $h_3=251.18\ kJ/kg$
Outlet ($T_4=40°C, x_4=0$): $h_4=167.53\ kJ/kg$
a) $\dot{Q}_L=\dot{m}_w(h_3-h_4),\ \dot{m}_w=0.065\ kg/s$
$\dot{Q}_L=5.437\ kW=\dot{m}_R(h_2-h_1)$
$\dot{m}_R=0.0338\ kg/s$
b) $\dot{Q}_H=\dot{W}_i+\dot{Q}_L,\ \dot{W}_i=1.6\ kW$
$\dot{Q}_H=7.04\ kW$
c) $COP_{HP}=\dot{Q}_H/\dot{W}_i$
$COP=4.40$
d) $COP_{HP, max}=\dfrac{1}{1-\frac{T_L}{T_H}},\quad T_L=25°C,\ T_H=T_3$
$COP_{HP, max}=9.51=\dot{Q}_H/\dot{W}_{i,min}$
$\dot{W}_{i,min}=0.740\ kW$
