Answer
$Q_i=22.6\ kJ$
Work Step by Step
From tables A-11:
Initial ($x_1=0, T_1=24°C$): $v_1=0.0008260\ m³/kg,\ u_1=84.44\ kJ/kg,\ h_e=84.98\ kJ/kg$
The volume of the tank with $m_1=5\ kg$:
$V=m_1v_1=0.004130\ m³$
The final specific volume with $m_2=0.25\ kg$:
$v_2=V/m_2=\ 0.01652\ m³/kg$
At the final state ($T_2=24°C,\ v_2$): $x_2=0.5056,\ u_2=164.67\ kJ/kg$
From the material balance:
$m_e=m_1-m_2=4.75\ kg$
From the energy balance:
$Q_i-m_eh_e=m_2u_2-m_1u_1$
$Q_i=22.6\ kJ$
