Question

Steam at 2 MPa and 75 percent quality fills a 0.8 m3
rigid vessel. Heat is transferred to
the steam until a pressure of 600 kPa is reached.
3.2.1 Represent the process on a P – v diagram with respect to saturation lines. (4)
Determine:
3.2.2 The mass of the steam in the vessel, and (7)
3.2.3 The initial internal energy of the steam.

Answer 1

At 2 MPa

$v_f= 0.001177m^3/kg; v_g=0.099587 m^3/kg\\ u_f=906.12kJ/kg ; u_{fg}=1693 kJ/kg\\ v_1 = v_f x_1(v_g-v_f)= 0.001177+0.75(0.099587-0.00117)=0.07498 m^3/kg\\$

3.2.1

3.2.2

$m= \frac{V}{v_1}= \frac{0.8}{0.07498}=10.67 kg\\ m_s = 0.75*10.67=8.0025 kg\\ m_l=0.25*10.67 =2.6675 kg$

3.2.3

$u_1=906.12+0.75*1693=2175.87 kJ/kg\\ U_1=mu_1=2*2175.87 = 4351.74 kJ$