Question

Find the missing properties and give the phase of the substance

a.  H₂O T = 120°C, v = 0.5 m³/kg u = ? P = ? x = ?

b.  H₂O T = 100°C, P = 10 MPa u = ? x = ? v = ?

c.  N₂ T = 200 K, P = 200 kPa v = ? u = ?

d.  NH₃ T = 100°C, v = 0.1 m³/kg P = ? x = ?

e.  N₂ T = 100 K, x = 0.75 v = ? u = ? 

Answer 1

(a)  v_f < v < v_g => L+V mixture, P = 198.5 kPa,

x = (0.5 - 0.00106)/0.8908 = 0.56,

u = 503.48 + 0.56 × 2025.76 = 1637.9 kJ/kg

(b)  compressed liquid, v = 0.001039 m³/kg,

u = 416.1 kJ/kg 

(c)  200 K, 200 kPa v = 0.29551 m³/kg ;

u = 147.37 kJ/kg 

(d)   v > v_g => superheated vapor, x = undefined P = 1600 + 400 × 0.1 - 0.10539 0.08248-0.10539 = 1694 kPa

(e)  100 K, x = 0.75 v = 0.001452 + 0.75 × 0.02975 = 0.023765 m³/kg u

= -74.33 + 0.75 ×137.5 = 28.8 kJ/kg

States shown are placed relative to the two-phase region, not to each other.