Answer
$m_i=5.645\ kg$
$P_i=8931\ kPa$
Work Step by Step
From table A-6:
Initial ($P_1=1\ MPa, x_1=1$): $v_1=0.19436\ m³/kg,\ u_1=2582.8\ kJ/kg$
Final ($P_2=2\ MPa, T_2=300°C$): $v_2=0.12551\ m³/kg,\ u_2=2773.2\ kJ/kg$
From the material balance:
$m_i=m_2-m_1$
With $V=mv$ and $V_t=2\ m³$:
$m_1=10.29\ kg,\ m_2=15.94\ kg \rightarrow m_i=5.645\ kg$
From the energy balance:
$m_ih_i=m_2u_2-m_1u_1$
$h_i=3120.3\ kJ/kg,\ @400°C\rightarrow P_i=8931\ kPa$
